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N;
MONTHLY NOTICES
OF THB
ROYAL ASTRONOMICAL SOCIETY.
tJO«TAisisro
L
PAPERS, ABSTRACTS OF PAPERS, AKD
REPORTS OF THE PROCEEDINGS
OF THE SOCIETY
FROM NOVEMBER 19C7 TO NOVEMBER 1908.
VOL. LXVIII.
LONDON :
ROYAL ASTRONOMICAL SOCIETY,
BURLIKOTON HOUSE, W.
J908.
/THE NEW York]
/PUBLIC LIBRARY
{ATTOR, LENOX AND I
TILDEN FOUNDATlONf. |
W 1909 l\
I N 1) E X.
Annoiil Geueml Meeting, 1908 Februsrj* 14, report of the ..». 219
AnmiLic pjipjri, saggeated expUnatiou of Jewish Calendar daXan id,
E/B. KnoQ 334
ArtiiiciAl hurizon, note on Ciipt Gftdsden's, H H. Turner * «... 535
AMftta Jind present property of the Society... , 225
A»todftt«s propoaeJ ..,,,..,....... , 449
elected 537
Aitroifraphic Catalogue (Oxford |iortion)j on the relative numbers of
star ima^'^es photographed in ditlerent parts of the plates,
H. H, Turner 397
Chart and Catalogue, Conncll note on the 305
Auditorn, report of the 224
Baldwin, J. AL, photometric measurements of Saturn, August to
December 1907 ...,..„.. 368
.^^^^~— ' ^— —— « errttt u m 494
— '■ photometric mea»uremeuts of Neptune, January to
April 1908 614
— « . — ^ —errata 677
Ball, Sir Rol>ert, note on the tdngh ei| nation whirhcornpriwa the theory
of the fundamental instruroeats of the Observatory 17 1
Bfrr&Ard, E. £., obserTatioDS of Saturn'^j ring at the time of its dis-
appearance in 1907, made with the 40*inch refractor of the
Yerkes Obeervatory „..,.....,. ,.... 346
— — erratum 494
additional oLaervatioof^ of the dibiaj^pi^arancfi uud re-
appearances of th« rings of Stiturn in 1907-iJ, rojide with the
4a-Lnch refractor of the Yerkes ObfiervHtory ... 360
a few observations of the planet Saturn and his rings
in the years 1897-1904 366
the Tariability of the nucleus of the planetary nebula,
N.aC.7662 465
note on the period of variation of Barnard's variable
nebula in Andromeda, H. H. Turner 481
on the parallax aod proper motion of the double star
Krueger 60 ............ 629
Bequests to the generaJ fundd of the Society ..,, 224
^Bombay Obserratory, note on the adopted co-ordinates of^ A. H. W.
Downing ».... 487
Brown, E. W., on the lunar iucqualitles due to planetary action 1 48
— the motion of the
ecliptic and the figure of the Efirth * 450
Bamliam, S. W., the proper motion of small stars ..... 5 '7
Bye-laws, alterations to the, woposed by the Council and adopted by
the Annual General Meeting, 1908 219
Owxibridg© Observatory, repw* a/ rA^proceddiiiga of 26%
OukdidMtagprotfofed j, Si, 147, 220, 331, 449, 4%, S'ST
Obp0 of Good Mope, Soyta Obaerratory, report of the proceedings ut . .. 2^1
<«)
Indent,
Christb, Sir W. H, M,, and H, A* H. Christie, on an improTcd roethcKl
of illuTuiiiAting th<? field in a transit instmin^'nt, and its effect
on the diacoTdance in reversed positimis of thf instrument »
CUxton^ T. F.> observations of the transit of Mercury at MaiiritiuB,
1907 November 14 , , : *..... ,,♦,,♦
Coeloiitat reflector, description c»f & 24-iiicb loog-foGus, J, H. BeynoMs...
Ooniets t —
HallevX perturbations of, in the past, P. H. Cowell and A. C. D.
Crommeliti ,, , .,.ni, rji, 375, 510,
^ nd A-C.D.
perturbations of, 1759-1910, P. H. Cowdl &nd A^
tablea >;iving approxiroat*' values of its perturbations by
JuyutiT and SatErn^ P. H. Cowell ami A. C* D, Cromnielin ►..
fl 1907 (Daniel), spectrnm of, J, Eversbftd
d 1907 (Diiniel), oUervations from photojrrapbs, Boyal Obscrvatoiy,
Greenwich. ♦..
d 1907 (Daniel)^ pbotosfraphs of^ Max Wolf
d 1907 (Daniel), observed at the RadcUlfe ObeerTatory, Oxford......
Comets of 1907, Cmiueil note on ,
Cortie, Hev. A. L., note to Capt. D&unt*s ptipcr on helium Dji abaorptiou
in the neigh bourhooii by hUD-spota .,...,,,......,..-....,....,....,,.,
Coimeilr report of the, to thu Eis^hty-fei^'hth Annual General Meeting...
Cowell, P. H., note oa the ancient solar eclipses discussed by, A. C. D,
Croniinelm -. ...„.,.
on ancient eclipses
Cowell, P. H., and A. C. D. Crommelin, tb« perturbations of Hal Icy *a
comet in the past : first paper, the period 1301-1531
second |>nper, the apparition
1S1
374
4S8
6d5
379
458
16
126
iSo
574
290
625
221
18
109
«
of 1232
1066 to 1301 .
1066
240 to A. D 760
Comet, 1 759-' 1910
' third paper, the period from
fourth paper, the period 760-
fifth paper, the period B.o,
' the perturbations of H alley's
^— table giving approximate
values of the ) perturbations of Hal ley ^s comet by Jupiter and
Saturn in the first and fourth quadranta of the orbit
-^— tha orbit of Jupiter's eighth
SAicUite...
Crommclin, A. C. D., note on the sjicient solar oclipses discussed by Mr
Cowell „. ,
-' firwt approximation to the orbit of J VIII. =CJ, ...
Crommolio, A, C. D., and P. H. Cowell, the perturbfttions of Haliey's
comet in the past •. first pa|^r, the jwriod 1301 to 153 1 . .,
- — — — — second pa[>er, the apparition
of 1222
1066 to 1 301.
to 1066.
to A.D. 760
cornet, 1750- 1910
third paper, the period from
fourth paper, the period 760
fifth pa{)er| the period JI.C. 240
thf perturbations of H alley *a
— table giving approximate
values of the perturbations of Halley'^ comet by Jupiter and
Saturn ...,...„
the otUt oC Ju^itfei's eighth
sat&JJltB,,
375
510
665
379
458
576
iS
457
III
173
375
510
379
45S
%1^
Index.
Cvavofftti in the sol&r atmosphere and in interplanetary hpace, H. F.
NewaU ,
(3)
PAOB
Daant, R. A. C, obeerraiions of helium D, absorption in the neigbboor*
hood of sun -spots in 1907 ,. 620
— — — ' — note by Rev, A, L. Cortio 625
Downing, A. M, W., oecnltationa of Qranus by the Moon in 1908, viaible
at British ObHervaloriea........... ,,.,*....,...... .....,.,»,,., 127
— ephemeris of Flora near the time of opposition in
J908..,, , , 216
note on the adopted ao-ordinatea of th« Bombay
(Colaba) ObservatoTy 487
the totAl solar eclipse of 1910 M^y 8 664
DUnaink Observatory, report of the proceedinga of .„,„„,.. S71
Durham Obeervatory, report of the proceedings of ♦*...,, 271
Eddington^ A* 3., on the mean diatanoes of the Groombridge stars 104
— ' on the ntatheuiatical theory of two atar^dnfts, and on
the ayntematic motions of zodiacal stars ,..,.,...*.....„., 58S
Kditiburgh, Royal Observatory, report of the proceedings of ,,. 267
Equation, the single, which eompris^'d the theory of the fundamental
instruments of the Observatory, Sir E. Ball 171
Smta 80, 448, 494, 628, 677
TMiiln. J. K-, obituary notice of..... 231
Espln, Rev. T. E,, miorometrical measur&s of double stars (fifth aeries) 202
new double stars ,, ....,206, 523
- — = — — Tt^port of bis Observatory — 278
Everibed, John, the ultra-violet region in sun-spot spectra 12
^—- the spectrum of Comet 1907 (/(Daniel) 16
— - — — solar prominences in 1907, obtisrved at Eodaikilnal
Oboenratory 515
Pellows elected... ...I, 81, 147, 219, 333, 449. 495. 537
FrAnklin-Adams, J., report of his Obaervatory^ ,,. 278
Ftmnksr W. B.» the relation between ^tar colours and spectra ..», 673
Fnuiz, Julius, proposals respecting lunar nomenclature „, 135
Otdflltn, Captain, note on his '^ Spanner " artificial horizon, H. H«
Turner ....,,.
Qibaon« Winifred, and Karl Pearson, further considerations on the cor-
rtiktioiis of st**lUr characters ................ .,..,.
Gill, Sir D., the Gobi Medal presented to bim for his contributions to
the astronomy of the southern hBmisphere, etc, .........319, 230,
Olawow Obsarvatory, report of the pr<kceediugs of
0«^ Medal, the, presented to Sir David Gill for his oontributiona to
ihe Astronomy of the southern hemisphere, etc. 219, 230,
Greenfrich, Royal Ob$«rvatory, observations of the satellite of Neptune
from photographs tiucon between 1906 December 27 and 1907
April 24
— — ^ ^ observations of minor planets from
photographs taken with the 30-inch reflector during the year
1906
* ■'- ■ results of micrometer measures of
double stars made with the iS-iuch refractor in the year 1906 ...
— firof»t*r motioua of \ iS6CaTrington stars
from a direct comparison between Carrlngton's catalogue for
1855 and the Greenwich second niue-yt-ar catalogue for 1900 ...
— observatiooa of comet d 1907 from
photographs taken with the 30-ir]ch reflector of the Thomp^ti
equatorial and the astrogr&phk Jj inch refractor.
- oot& ou pht/tographs of Fhoebo
535
41s
317
273
317
33
35
39
126
(4) Index,
PAGE
Gr«eiiwich, Eoy&l Observatory, obserrations of Saturn's ninth s&tellite,
Phoebe t from photographs taken with the 30-inch reflector in
1907 .., 211
observations of occultationa of stare by
the ifoon, made in the year 1907.................... .,..»,.. 213
' eg.
report of the proceedings of . , 258
_, jiote on the discovery of a moving
object near Jupiter (1 90S CJ) 373'
note on the newly discovered eighth
satellite of Jupiter ,,,... ...,..„,. 456
results of miirrometor tiiesBuros of
double stars made with the 28-iiicb refnictor in the year 1907 525
observations of Jopiter*s sixth, sevunth^
aod ci^htl] satellites, from ]>hotograpbs t&kvn with the 30-inch
reflector in 1907-8 - 5S2
' observations of the satfUite of Neptune^
from photographs taken between 1907 December 10 aud 1908
March 19 .., 586
' diagrjtm showing the t>oeitions of
Jupiter's sat*41ites VI, VII, and VIII, from photographs
taken iluHog the oppo.sition of 1907-8 .,.. 671
diagram showing the positions of
Saturn^s ninth satellite^ PhtEbe, during the oppositioo of 1907 671
Groombridge stara^ on the mean distances of the, A. 3, Eddingtou ...... 104
Hagen, Rev. J. G., note on F Cephei ., 676
Hale, G, E., some opportuiiiiies for astronomical work with inexpensive
apparatus ....*.* ,,♦,, .,.,...... 64 1
Hallp Asaph, obituary notice of ...,. 243
Hayn, F., Conneil *uote on his researches ou the Moon's physical
libration ,. .,,. ,.,... .', 297
^ - ■ -^ — ^ — erratum 44S
Heath, Walter, occnltation of the Hyades... 31
the ratlins of the Moon for libration - 4' '5 .,.„ $68
Herschel, A. S., obituary notice of , .,... 231
Einks^ A. R.j solar jiaralkx papers. No. 6 : construction of a standard
cataloguo of photographic atar-plaeea 82
Huggins, Sir William, report of his Obaervatorj' ,. 27S
Hypergeoraetrical functions, F {i/6» 5/6, 3, sin'' i) and F ( - l/6» 7/6, 3,
iin» j), tables of, C. J. MerJield ., 605
Inexpensive apparatnsi some opportuoities for astronomical work with,
G. E. Hale
Itmes, R. T. A., disappearance of Saturn's ring-system, 1907 October
to November „ 32, 209
the transit of Mercury, 1907 November 14 , 128
reapfiearsnce of Saturn's ring, January 1908 37a
^^— magnitnde of ij Argfls, 1908 .,„ 613
Instruments of the Observatory^ not© on the single equation which com-
prises the theory of the, Sir R. Ball 171
International Uuiou for Solar Research, papers of the compnting bureaUj
No, I : position of the Sun':^ axi^ of rotutiou, H. H. 'tinier ... 9S
Council note on the meeting of
the third conference, I907.... ..........*» . 295
papers of the computing burean.
No. 2 : furtlmr note on the position of the Suu*8 axis of rota-
tion, H. H. Turner 609
papers of the computing burean,
No. 3 : on posAible periodic inequalities in the epoch of san
spot variation, H. H.Turner 656
InUrpIaneury sp&ce^ cyanogen in, H. F. Kewall..... *„...,,. 2
Index. is)
PAaE
J F. J. C, obituwy notice of ♦.... , 245
Jewish Calendar datet in Aramaic papyri, suggested explanation of,
E. B. Knobcl , 334
Jondtheerts^ Robert, obaervfttioii du paswage dfi Mercure sur le Soleil le
14 Nor. 1907 , 131
Japiter^ a*tellite VllI, note on the diftcovery of a moving object near
Jupiter, Koyal Observatory » Greenwich ., , 373
-^ note on the newly discoveredt Koyal Obaervft-
tory, Greenwich , 45^
-^ first approximation to the orbit of, A, C, D,
Cnommelin „..,.,.... ,.. .,♦..... 457
the orbit of, P, H. Cowell and A. 0. D.
Cromnieliri „*... * ♦ ,,....»*,,, 576
Jnpitar, aatellites VI, VII, and VIII, observations from photographs,
1907-8, Royal CJbservatory, Greenwich ..,.„ » 582
diagram showing the positions
of, 1907-S, from photographs taken at tht; Royal Observatory,
Greenwich...*, ..,,-,,. * ,.,,♦ 671
Kelvin, Lord^ obituary notice of «..,.♦»..♦...,., 234
Kennelly, D, J., obitunry notice of .„ , ., 237
Kiiobel, E. B.,a sugge<)ted explanation of the ancient Jewish calendar
dates in the Aramaic piipyri trauslated by Profe&^r A. H.
Sayce and Mr. A. E. Cowley 334
KodaikAnal and Madras Observatories, reiKJrt of the proceedinga of 260
Lsmea, photo- visual, note on the permanency of, W. J. S. Lookyer and
H. Den ni* Taylor 19
Library, etc., list of donors to the .,....,... * — 311
Liverpo^il Ohserratory, report of the proceedings of „.„ 272
Lockyer, W, J. S., note on the perinaneno}' of some photo-viflual lenses i
with addenduTfi by H. Deniii^j Taylor ,.... ......*» 19
Loewy, Maurice, obituary notifre of... ,,....,.. 249
LoilAr nomenolature, committee on : proposals made by Dr. Franz, M,
Puiseux, Profeasor W. H. Hckering, and Mr. 8aunder. 135
MeltHjiime Obsenratory, report of the proceedings of 2S3
Mflboonie and Sydney Gl>ser^'tttorks, joint re[>ort on the measurement
of astrograpbic plates 2S4
Mereory^ transit of, 1907 November 14, observed at Johannesburg,
by R. T, A. Innes[ete.] , t2S
™ — by E, T. Whitt-low ......... 130
— — - — by Robert Joncklieere...... 131
— -^ — in Mauritius, by T. F.
CUxton 374
Mtcfield, C. J., tables of the two hypergeometrical functions, F(i/6,
5/6, 2, sin^ i) and F( - 1/6, 7/6, 2, ain^ J), between the limits
iota equaU 90 and i^ degrees 605
Minor PUiietdr ol)servatlons from photographs takvn at the Eoyal
Observatory, Greenwich, 1906 , 35
ephemcris of Flora near the time of opposition in 1908,
A. M. W. DtJwninK 21$
lloon, bright rnys on the, H. G. Tonikin;^ , .♦.♦ 571
occnkations of the Hyades by the, W, Heath 31
-= > TJraniia by the, in 190S, A. M. W. Downing 127
— - — ~ — stars by tlie, in 1907, observed at the Eoyul Ob-
aervatory, Greenwich 213
— — ph%^8ical libratiou of the. Council note on Dr. Hayn*8 researches 2^1
— ' erratum \^
t^^iuB of the, for libntioR ' 4°*^, W. Heath ^CA
(6) Index.
WMum
Moon, theory and tftblea of the : —
Lunar iaequftlities <fue to |>lanetary action^ E. W. Brown 148
Cunncil note on reaearehea on the action of planets on the Moon ... 299
On the lunar iuequalities due to the motion of the ecliptic and the
figureof the Karth, E, W, Brown 450
Conaiderationa on the form and arrangement of new tables of the
Moon, S. Ncweomb ...,*.,, 53S
Nebulffij J—
H IV. 74 Cepbei, Max Wolf 30
N.G.G. 7662, the variflbUity of the nucleus of. E, E. Barnard 465
-— ^ note on its period of variation, H. H» Turner 4S1
Lengths of axes and position angle*> uf 52 oral BebulBet Max Wolf,,. 626
Keptune» the satellite of, observatioua from photographs^ 1906-8, Boyal
Observatory, Greenwieli »,.,......,.,, , , 33, 586
- — ' -photometric nieasuri'inenta of, 1908, J, M. Baldwin 614
Newall, H* F., apectroiacopic observationa of cyanogen in the solar at*
moiiphere and in iuterplaiietary 8pao« 2
— address on proa en ting the Gold Medal to Sir David Gill
for his contributions to the astronomy of the southeni
hemisphere, etc. ,.., »..,,. 317
Newall teleaeope, Cambridge Obsirvatory, report of the wrork of the ... 270
Neweomh, Simon, cousi derations on the foi-m and arrangement of new
tables of the Moon ., .,..,. 538
Obituary Noticed : Aasotijatea: —
Hall, Asajph.... ......,.,,. ..» 243
Jmnasen, Pierre J iilea C(!»Bar *... 245
Loewy, Maurice 249
Tr^pied, Charlw ,...., , 252
Yogei Hermann Carl 254
Obituury Notices : Fellowa : —
Estfaile, James Kennedy , 231
Hersohel, Alexander Stewart 231
Kelvin, Lord .,... , ., 234
Kennelly, David Joseph 237
Perkins, Thomas , 23S
Petrie, James George 23S
Robion, Thomaa 238
Eouth. Edward John ....„ 239
Rttsaell, Henry Chamberlain. 241
OhieiTatories, report* of proceedings of , ..,.., 258
Offioera and Council, 1 90x8-9, liat of .., , 331
Oxford, Raddiffe Observatory » report of the proceedings of .,......,, 272
^ observations of Daniel's comet {d 1907) 574
Oxford University Observatory^ report of the proceedings of -. 274
PeaTion, Karl, and Winifred Gibson, ftirthcT considerations on the cor-
relations of stellar characters , » ,., 415
— — ^ — an example of Professor Pearson's
calrnlation of correlation in the case of the periodic ineqnidities
of !ong-|venod variables, H. H. Turner 544f ^7
Pe«k, Sir Wilfrid, re|H>rt of his Observatoiy 279
Perkins, Thomas, obituary notice of 238
Perth Observatory, Western Australia, rei>ort of the proceedings of ...... 280
Petrie, J. G,, obituary notice of 23S
Photographs, celestial list of reprodnctioiis of 226
Pickering, W. H,, proposals respecting lunar nomenclature 142
PlmDetsAnd sat«]/itefl, Council note on the diacovftty of^ 1907 288
Index.
(7)
PUt€« :—
Photo visuaI hnsep, W. J. S. Loclcyer 29
Ncbol* H. IV, 74Ce|>hei. Max Wolf 30
Pbotogf&pha of spectrographs, G. K. Hale «.. 76
Comaid 1907 (Daniel) /Max Wolf „.. , I«0
llJumiiiation of field uf tmnsit iiistruni€iit, Sir W. H. M. and
H. A, Cbrifltie , 186
Smtuni, 1907, E. E. Bwtiard, 358, 366
PUnetary nebula, N, O. C. 7662, E. E, Barnard 480
Oa^tain badsdeu's "Spnner " horizrjn, H.H.Turner .,,... 535
The double star Knieger 60, E. E. Barnard , 654
Jupiier*9aftt«llitea VI, VII, and VIII, Jioyjil Observatory, Greenwich 671
Satam's ninth satellite (Phftbe), E^yal Obiiervatory , Greenwich .., 671
PrMents announced ,....2, Si, 148, 333, 450,495, 537
Procressand pr^setit stsite of thf^ Society, 190S ..,,.. Z2i
PnuieationB of the Society „..,., .,, , 230
Pntietix, P., proposals respecting lunar nomenclature ,. 137
Refraction, astronomical, an empirical law of, H. H. Turner ».....* 496
Rejmolda, J. IL, description of u 244nch long-focu* c<slo8tat reHector ... 48S
Robairta, A. W., report of hia Observatory ,.....,.,... ., 286
' 00 his methcd of determining the absolute dimenaions
of an Algol variable stAi, Rev. J. lutein 490
note to the above ^►aper, H, H. Turner ..,.. 492
note on Father Stein s paper ** On Dr. Koberts's method
of det«miining the absolute dimensioua of an Algol rariftble
star" .„....., ..,„. 536
Bobton» Thomaa, obituary notice of ,.,. 238
Ronth, £. J., obituary notice of ajg
Rogb^' p Tem pie Obeervatory , report of the proceedings of ,,,.....,..» 27 5
H* C., obitxtary notice of 24!
Yt
k
Sfttnn], disappearance' of the Hug system of, R. T. A. Inncit 32,
obaeryationa of the rin^^ of, at the time of iL'^ disappearance in
1907, made with the 40-inch refractor of the Yerkes Obsenra-
tory, E. E, B.Trnard
' additional observations of the disapp^aranceii and reappearances
of the rings in 1907-S, made with the 40-inch refractor of the
Yorkcs Observatory, E. E. Barnard..,..
a few ob^enratioQH of, made in jS 97 -1904, E, E. Barnard
>' photometric men a urements of, 1907, J, M. Baldwin ,
— — — reappearance of the ring of, 1908, R, T. A. Innes
note on the conriition for the jmsaage of the Earth throngh the
plane of the ring, H. H. Turner
S&tnni's ninth satellite. Phiebe, observations from photographii of, taken
at the Royal Observatory, Greenwich ., ,..,. 127^
diajL^ram showing the j^ositiorji* ot» 1907,
from photographs taken at tlie Royal ubaervHtory, Greenwich
Sannder, S. A., proposals resiiecting liumr nomenclature. «..
report of his Obaervatoiy
Solniiier, J., researches on the solar constant and the temperatar« of the
Sun »..»....
Soott, J. U, measures of southern double ^tara in 1907
8ea,T. J. J^ on the orbit of the binary star iS 80
on the orbit of ^ 515 = 4© Cass iopeiie „,,.. ........
on the orbit of 0 552 = 11 Orionia
note on the com pa rati v-e eccey^tncities of Tisiul B-Iid
209
346
360
3^
372
460
211
671
144
279
662
484
192
195
198
vpectraifcoplc biimtj stars.,. .., ^ ,^^,^ 201
(8) Imiex.
See, T. J» J., orbital elements of double «tarB„.. „,, 565
Solar Rese&rcb, IntematiDiiai Unioo for, papem of the computing bnreftu,
Nos. 1-3 ., ,... 9^»6o9» 656
'^ —Council note oo the an^eting of
the third Oonference, 1907 .,... ........»..».,. 295
South Kensington, S<jUr Phyaics Oliservatory, report of the proceed-
ings of ,,..„*...,....« .,,. .,.,.. ♦ 275
, Royal College of Science^ report of the proceed*
ingsof ^ - .,.*.«.. 277
St»r CataloguFs : —
Carri II g ton's catiilogue for i855» comparison with the Greenwich
second nine-3*car catalogue for 1900, Royal Observatory,
Greenwich,,.. .*,, 48
Star coloura and spectra, the relatitm l>etween, W. S. Franka .,... ., 67a
Star drifts (two), on tbe matbeniatieal theory of, aod on tbe systematic
in otioDS of zodiacal atam, A. S. Eddington 5^8
Star image;}, on tbe relatiTC numbers of, photograpbed in different parts
of tbe platt's far the Oxford portion of tbe Astrographic
Catalogue, H. H. Turner .., 397
Star places, pbotograpbic, conatruntion of a standard catalogue of,
A. IL Hinka. 82
Stars, distribution of, CouncO note on reB^arches in IQ07 ..***.. 303
Stara^ doable : —
Resulta of micrometer meaaurafl made at the Royal Observatory,
Greenwieb, 1906-1907 .,, , „... 39, 525
$ 80, orbit of, T. J. J. See 192
^ 513=48 Caiisiopeire, orbit of , T. J. J. See 195
^ 552= 11 Orionia, orbit of, T. J, J. See ..„ 19S
Note on the comparative eecGntricitiea of vianal and apectroacopio
binary stars, T. J. J. See .„„...,... 20I
Kicronietncal nieaaurea of doubli* stars (fifth serioa) Rev. T. £.
Espin ...„,... 202
New double stars, Rev. T. E. Espin 206, 523
Council note on .,.,.. .,..,.,. 300
Meaaures of southern binary stars in 1907, J. Tebhutt,,. , 396
Measures ofsoutbern double stara in 1907, J. L. Scott .,,..... 484
i3 4i6» orbit of» J. Voute 563
Orbit*l elements of 2 2, 5524, 3483, ^3883. ^581, AC 5, 2 3123,
2 1 88a, Dembowftki 15, :i2438, ami 8ecchi 2, T. J. J. See 565
Krueger 60, parallax and proper motion of, E. E. Barnard »,,... 629
Stars, Groombridge, nienn distances of the, A. S» Eddington. 104
Stars, pro|>er motions of :^
Prof>er niotiona of 1186 CKrringtou etara, Eoyal Observatory,
Green wicb..... ,....,.„,.......», ,.,»«*., 48
The proper motion of aniall stars, S. W, Burnham .„.. 517
The parallax and proper motion of Krueger 60, E. E. Barnard 629
Stars, spectra of ; —
Council nnta on stellar sijectroscopy in 1907 306
Relation between star colours and spectra, W, S. Franka ...» 87J
Stars, variable: —
Council not t^ on „,.. 30a
Corrections to Professor Tiirner^s pa]>eron the olAiaifiGation of long-
period variable stars, Kev. .L Stein ,..,..... 4S2
Go Dr. Roberts a method of determining the abiolnte dimensions
of an Algol varittbl« j^tar^ R«v. J. Siein ..., .,. .,. 490
note to tbe abovf pawr, H. H. Turner 492
— note on Father Stein s paper, A. W. Roberts ....„ 536
Example of Prof. K. Pcarstni^^ oalcnlation of correlution in the
case of Ion g-peitod variables, H. II. Turner ..,**♦ S44» ^77
1^ Serpent! a, note ou the period of. H. H. Turner .....,„.*..,♦ 560
ti Argila, magnitude of, T908, R. T. A. Innes .,,,...,... 613
yCeplm, note on, Rev. J. G. tlagen , 678
•
Index,
(9)
Sttftn. RtT. J*, corrections to Profitesor Tamer's jiAper "On tlie clossi*
fication of lonfE p*rio<l Turiable stars, and a possible physical
interpretation** ,,,.♦..,.,, ,♦,.,..♦*♦.* 4S2
on Dr. Roberts's method of determining the absolute dimensions
of an Algol variable star ..., 490
__^.. note to the above paper, H. H. Turner ,,», 492
- note on Father Stein h fjaper, A. W. Roberts ,. 536
Stellar characters, further consideration.'* on the correlations of, Karl
Pearson and Winifred Gibson .....,..,........,.....,,,.... 415
Stonyhnrst G^llege Observatory, report of the procetxlings of„» »».,.. 277
Son, atinoi»phere of, spectroscopic observations of cyanogen iu the,
K F. Niwall 2
Sati» edipset:^ —
Not« on the ancient solar eclipses diAcnssed by lir. Cowellp
A. C. D. Crommelin , » iS
On ancient eel ipse^t, r. U* Cowell ..,.,... ,. 109
The total eclipae of 1910 May.S, A, M. W. Downing 664
Son, psrallax ot the :—
Solar paiallMX piipers, No. 6, A. R. Hinks.,*, „. ,, S2
Snn, prominences, 1907, Coancil note on .. 294
— — —observed at Kodaik^al Observatory, J.
fivershed ., ,, 515
San, rotation of, note on the position of the Sud^s axis, H. H. Turner 98, 6og
Council note on resenrchfs in 1907 296
San-fipots and fuculie, et.'. : —
The ultra-violet region in auo-apot spectra, J. E vers lied , 13
Council noie on solar activity in 1907 , 293
CoQiicil note on researches on sun-spot spectra and spectroheliO'
graphic work in 1907 .,.♦ ....* ....*....... *.,.. 295
Ob>«rTatious of helinm Dj absorption in the neiglibonrhood of sun-
spote, Capt. R. A. U. Datmt (with note hy Rev. A. L. Cortie) 620
On possible periodic inequaliLiea in the epoch of the sun-spot
variation, H. H, Turner 656
San, temmrature of, and the solar constant, J. Scheiner ,. 662
Sydney Orwervatory, report of the procefdings of , 285
Sydney and Helboume Observatories, joint report on the measurement
of astrographic plates , ,.,...,,, 284
Tarlor, H. Dennis, notes on Dr, Wm. Loekyer'a pi^per on the pormanency
of some photo-visusl looses
Tcbbntt, John, report of his Obserratory ,. .,,
mcfisure.^ of southern binary stars in 1907 ,,.. ,...,
Tomkins, H. 0.. the lunar larigbt rays .... ...
Transit instrument, on an improved method of illuminating the field in,
SirW. H. M, and H. A. H, Christie ,.,
T ^-liner's acconnt for 1907
T*d. Charles, obituary notice of
Iriist funds
Tomer, H* H., note on the position of the Sun'a axis of rotation, as
deduced from Greenwich sun-spot measures, 1886- 1901.
Papers of the I.U.S.R. computing bureau, Ko. i
further note on the position of the Sun's axis of rota-
tion, as deduced from Greenwich sun-spot measures. 1874-85.
Papers of the I.U.S.R, computing bureau, No. 2,,
■ on posiible periodic inequalities in the epoch of the sun-
spot variation. Papers of the I.U.S.R. computing bureau,
No. 3..
on the relative numbers of star images photographed in
different parts of the plaU^s for the Oxfonl i>ortion of the Astro-
graphic Catalogue ; second pjiper
— note on the condkioD for the passage of the ^Tt\i
thwt^fli th0 plMJiB of BAtUTD's Ting „ , ,,„,
28
287
30
571
181
222
252
224
98
609
656
a6o
(lo) Index,
PAOB
Turner, H. H., note on tlie period of variation of Barnard's variable
nebula in Andromeda 481
corrections to his paper on the classification of long-
period variable stars, Rev. J. Stein 4S2
note on Fatlier Stein's paper (on Dr Roberts's nietliod
of determining the absolute dimensions of an Algol variable
star) 492
an empirical law of astronomical refraction 496
note on "the Spanner," Captain Gadsden's artificial
horizon for sextants 535
an ezumple of Professor Karl Pearson's calculation of
correlation in the case of the periodic inequalities of long-i>eriod
variables 544
corrections to the above ^)apcr 677
note on the period of <$ Serpeutis 560
Uranus, occultations of, by the Moon in 1908, A. M. W. Downing 127
Vogel, H. C, obitnary notice of 254
You te, J., on the orbit of 3 416 563
Whitelow, E. T., observations of the transit of Mercury, 1907 Novem-
ber 14 130
Wilson, W. E., report of hiH OV^servatory 279
Wolf, Max, the nebula H IV. 74 Cephei jo
photographsof Comet d 1907 (Daniel) 180
length of axes and position angles of 52 oval nebuls 626
PKINIKD BT NEILL A5D 00., LTD., l&Dl!SBi:&QH.
MONTHLY NOTICES
or THl
ROYAL ASTRONOMICAL SOCIETY.
Vol LXVIII,
November 8, 1907.
No. I
H. F. Nbwall, Esq., M.A.» F.R,S., President, in tbe Chflir,
H&rold A, H. Christie, M,A., Royal Oljservatory, Greenwich,
8.K ;
Bi»rtram Francis Eardley Keeling, Tbe Observatory, Ht^lwan,
iieftr Cftiro, Egypt ■ and
Frcdenck Alexybder Lindematin, Sidboira, Sidmoulh^ Devon,
were baUoted for and duly elected Feilows «*f tbe Society.
W.
w.
The followiiiij caudidates were projiosed for election as Fellows
of llie Society, tbe nainea of tbe proposers from personal knowledge
being appended : —
Henry Boade Austin, J. P., Government Buildings, Bioem
fonteio, Orange River Colony, South Africa (proposed by
R, T. A, Innes) ;
Geoffrey Dnffiold. Physical Laboratory, Manchester Uni-
vereity (proposed by Arthur Schuster) ;
. Earnahaw EUe!, B.S., LitUL,. M.S.M.F., Professor of
Science, Sfc Bernard^, Rochester, N,Y., U-S.A. (proposed
by WUlJam R. Brooks) ;
John M. Field, 1 Hart Street, Edinburgh (f>ropo8ed by William
Peck);
James D, Maddrill, Ph.D., Interaational Latitude Observatory,
Ukiahy California, U.S.A. (proposed by H» C; Pluuimer) ;
William Henry Reea, B.Sc, Mathematical Miister, County
School, Pontypridd, 2 Gmigeven Place, Pontypridd, South
Wales (prop»o8ed by Rit^hard Kerr) ;
Thomaa James Forrester Suiith, Newstead, Wavertree, near
Liverfiool (proposed by F, W. Longbottom) ; and
Captain James Weir, F.R.G.S., Examiner of Masters and
Mates in Navigation and Seamanship to the Board of
Tnde, 5 Clive Crescent, Penarth, Glamor^^an, Soutb "WaX^a
(pwpoaed bj Albert Taylor),
2 Mt, H. F. Newall, Observatmis of Cyanogen in ucvra. i»
One hundred and sixty- nine presents were announced as baring
been received since the last meeting, including, amongst others : —
W. W* Bryant, History of Astronomy ; S. W. Burnham,
General Catalogue of Double Stars (2 vols.) ; and Sir G. H. Darwin,
Scientific Papers, vol. i., presented by tbe authtirs ; Galileo, Opere,
Mizio nazionale, vol. iii. part 2 aod vol xix., presented by the
Italian Government ; Lady Huggins, Jlemoir of Agne^i and Ellen
Gierke, presi^nted by the author; Oxford Astrograpliic Catalogue,
voL iii. ; Observatoire de Paris, Atlas Photographique de la lune
(Loewy and Pniaeux), fasc. 9 ; and Perth Observatory, Western
Australia, Catalogue of 420 standard star.^» presented by the
Observatories ; Sir N. Lockyer, Report of the Eclii^ee Expedition
to Majorca, presented by the Solar Physics Committee.
Astrograijhic Chart ; 134 charts (Algiers, Bordeaux, Paris, and
San Fernando), presented by the French Government ; 23 charts,
presented by the Tacubaya Obt^ervatory, Mexico ; and 76 charts,
presented by the Royal Observatory, Greenwich.
Three transparencies of the moon from negatives of M. Puiseux,
presented by Mr Knot)ei ; 9 transparencies of the northern Milky
Way, presented by Professor Max Wolf.
Medal to commemorate the Benjamin Franklin bicentenary
(bronze), presented by the American Philosoiihical Society.
Spedrmcopic Observations of Cyanogen in the Solar Atmosphere
and in Int^rplamtary Space. By H, F. bewail, M.A., F.R.S.
The presence of cyanogen in the atmosphere of the Sun seems
to be indicated by the distinct appearance of the cyanogen
absorption bands at wave-length 3883 in the solar spectrum.
But, so far as I am aware, no definite observalions have been
directed to settle the possible doubt as to whether the cyanogen
is confined to the solar atmosphere. The possible alternatives
are that it may be in the Eartb/s atmosphere, or in space between
the Sun and the Earth,
[iVo^rr. Nov. II. — Professor Dyson has kindly called my
attention to evidences which had escaped niy memory and is \
conclusive as to the presence of cyanogen in the chromosphere.
Sir N. Lockyer found CX bands in the flash spectrum of the
chromosphere photographed in India in 1S98 (Fhi^. I'rans, R,S,^
vol. cxcvii. A,, p. 2q2, and Mem, E.A.S,^ vol. liv., App. p, [52]), and
Professor Dyson himself found them in his observations in Sumatra
in 1 90 1 (Phil. Trans., vol. ccvi. A., p. 438, and Mmn, H,A.S. Ivii,,
App, [36]). I have accordingly modified one or two of the
statements in the paper.]
During the past summer I have made some observations in
attempting to elucidate this point. The method adopted consisted
/n photographing side by side on one phoWgrai^hic ^late two solar
Nov. 1907. Solar AtmoBphere and in iTderplanetary Space. 3
spectra taken successively in the light comiBg from the east and
from the weal ends of tbe eqiiatorial iliameter of the 8im. Lines
of truly solar origin fihould show lelative displace men t in tli« two
spectra in consequence ot the difference of velocity in the Hue of
sight arising from the Sun's rotation. This is a form of the well-
known method of Cornu for distiiignishing between lines of solar
und lines of tellnnc origin.
In the result I tind that my photographs show displacement
ol the cyanogen bands similar to that exhibited by neighbouring
lines of iron and other vaix>ur8. There are, however, also
tfvideoces in the photographs that there is a trace of superpiised
cyanogen hands exhibiting displacements other than those
sitribn table to the Snn^s rotation. Thus tbe evidence so far
accumulated shows that there is cyanogen in the Sun s atmosphere
rotftting with the Sun, and there is also cyanogen between
tbe Earth's surface and the Sun showing spectroscopic displace-
ments that may be attributed to independent motion.
Before passing on to give the evidence collected, it miiy be
well to give some consisle rations which may be held to justify the
inquiry as to the seat of cyanogen absorption. I recognise the
highly speculative nature of some of them, but I beg leave to set
them forth, in company with the statement of several newly
observed facts, which go some way towards justifying speculation.
One of the most marked features of tlie spectrum of comets
is the bright bands of cyanogen iit 3883 first discovered by Sir W.
Huggins. It has generally been held that this incandescent
cyanogen and the other carbon compounds evidenced by cometary
spectra are emitted from the comet's head, driven out under the
iutluence of the Sun's radiation. On this view the observed fact
that periodic comets seldom display brilliant tails receives the
explanation that each successive retnrn of a comet to perihelion
reduces the quantity of vapour in the possession of tbe comet's
nucleus ; such vapours, then, are set free in interplanetary space
and seem to be spread out, mainly in the plane of the comet's
orbit, under the action of repulsive forces^ The old view that
lb© freed vapours are swept up by the gravitative attraction of the
planets and the Sun is now being replaced by tbe modern view
that radiation-pressure drives tbe larger aggregates of molecules
€>r ions outwards fmm the Suu* Schwarzschild^s work has shown
that things as small as molecules cannot, as such, he repelled by
radiation-pressure. It is generally held that molecules are of
linear dimensions of the order of 10"^ cms.^ whilst the wave-length
of green light is of the order 5 x lo*'^ cms. And Schwarzschild
has shown that things smaller thrin a tenth of tbe wave-length of
Ihe radiation are more attracted by gravitation to the Suu than
repetJed by the pressure of the Sun'.s radiation.
Bat it is held that a great deal of the display of comets* tails is
doe to iituminated dust as is shown both by tbe spectrum and a\etO
by the polari>*copic pheDomeim obseTved by PrazoumowalLl auA
oik£tm> Here Again the dimenajona of particles giving tbe p^\ma%-
4 Mr, H. F. Newcdl, Ohsmvaticns of Cymiogm in lxvul t,
tion effects afford some difificultiea ; but it might be held that the
gases, which the spectroscope shows to he present in the tail, are
carried oat by the repelled dust. Arrheniua, however, a^ far as I
understand his present views, is ready to regard the molecules of
gasee and vapours as grouped in aggregates large enough to bring
them under the sway of radiation-pressure.
The work of Deslandres and Bernard on the spectrum of
Daniel's comet 1907 (i (CM., cxlv. 445) shows that bands of some
gaseous substances were visible in the tail at 45 minutes of arc
from the nucleus in the middle of August; and I learn from a
letter from Mr. Evershed that, at Koilaikjinal, he and Mr«, Everahed
have succeeded iti photographing the same comet with a prismatic
camera, with the following results: — '*The hydrocarbon bauds
extend a long way up into the tail^ whilst tlie cyano>'en bands near
3883, ak bough the most brilliant rtidiatious in the comet spectrum,
are concentrated round the head,^*
Now, both in the case of the absorption bands of cyanogen seen
in the solar spectrum mvi in the emission bands of the same vapour
seen in the cornetary s[aectrura, a )>eculiar feature is that the ultra-
violet bands at 3883 are the most marked, and tlrat the blue and
violet bands are far more feebly seen than under certain conditions
attainable in the laboratory (Liveing and Dewar, Proc, R.S.j xxx.
494 )» Some years ago I made a series of observations on the
spectra of carbon ct^mpounds commonly present in vacuum tubes.
My observations {unpublished) related chiefly to phenomena in
©lectroileless discharges l>rought about by Professor J. J, Thomson's
electro-mngnHtic method (PhiL Mmj.y 1891^ vol. xxxii, p. 321,
and Proe, Roj/. Ind.^ xiw p. 243)* wherein a tube or bulb of
considerable diameter, rniiging from about 12 mm. to 100 mm., is
surrotiijded by a few coils of thick wire, the ends of which are
connected with two Leyden jars or plate condensers. The dis-
charge of such charge<l cundensers is accompanied by exceedingly
rapid electrical oscillations, which give rise to induced oscillations
(acoompftnied by luminosity) in the rarefied gas in the enclosed
tube. The method made it possible to produce brilliant luminosity
in the gas at much lower pressures than those then attainable in
ordinary vacnum tubes provided with electrodes. The pressures
measured were between o'6o mm. and 0005 ^^^' ^^ mercury,
I will refer here only to two of the results indicated by my
observations. One was that as the pressure was diminished the
bands of nitrogen and cyano^jen, which I specially studied, became
faint and disappeared at the red end of the spectrum, wlulat those
in the violet and ultra-violet were left distinct^ or even intensified.
I found no case which did not conform with the generalisation,
that as pressure is diminished the maximum intensity of the bamled
spectra is pushed towards the shorter wavedengths — the electrical
conditions being kept constant. The observations of Hasselberg and
of Dealandres support this view with respect to nitrogen ; and it
would not he difficult to devise a set of experiments to decide
whether my obaervaiions can b© reconcWftd N9\V\i \i\iOBa o( ^Mtting
Nov, 1907. Solar Aimmpfure and m Interjdumtary Spdce, 5
{Aftroph. J(mK, xx. 131 )t which, m far as they go on these line«,
m^m lo iiidiciite an opjiosite cuticlimion for the tuuch hight»r
pfeafturei* between t mm. and 21 mm, At any rate my own
(laboratory) experiments have led rae to the belief that in tfie solar
ftpectmm the evidence points to the conchisioE that cj^auogen is at
low pressure. It is oh^-ious that the pressure must he low in the
case ui' a comet^s tail extending several tbousanda (if not millions)
of milm from the nucleus.
The other obserratton to which I now wish to refer was that the
ipectra of hydrocarbons an*1 nitrocarboim were far the most easily
thcited m such tubes and bulbs, and that the proceBsea involved
m the production of luminosity in the vapours could be started
under conditions which proved instability, in the serise that the
^ was luminous in regions of the vacuum bulb where tlie electro-
motive intensity (KM.F, per c«i.) was zpfo.
Ihia observation suggesteij an alternative to the usually accepted
view of the origin of the cytinogen, *sUi.y in cometary spectra, aa
foUows: — Is It not po«*aible that the hydrocarbona, nitmcarbons,
01 c, which «eem to be evidenced by the spectra of all comets, are
alwmfs present in circumaolar space, and rendered incandescent by
some prucease^ coonected either with the motion of the solid parta
(including dust) of the head of tlie comet through the vapours, or
with the emission of sontt? iniluence from the comet head 7 Are
we to say that all comets, wherever they may come from in the
uniferse, and whatever their main material may be, always bring
with them the cyanogen and hydrocarbons which give them lumi-
noaity I Or is it not more rational to say that the spectra of all
comets are approximatt^ly similar, liecause they always find the
same vapoura spread in their path as they approach the Sun, and
can only elicit the spectra of these vapours 1
If we adopt this latter view, then, apart from the phenomena of
repulsion, we have only to explain the production of luminosity,
iind variations m the intensity of iL And out of the embarrassing
wealth of suggestions connected with the development of the
eorpuscntar theory of nmtter, there is no ililficulty in picking one
or two inodi^s of influence to which iocandeiicence mij^ht be
attributed, I will not dwell on this a!*|>ect, but will call attentiiiji
to another mode of producing luminosity — ^wherein there is no
obvious ^i^n of high temperature — I mean the luminosity of air
when it rui^hes thnuigh a small crack in the glass walls of a vacuum
tubc% o phenomenon that must be familiar to most of those who have
been engaged in experimental study of such tubes. Two or t!iree
times I have been able to recognise the bant is of nitrogen in the
•pectnim of the glow in such a crack. Now, such luminosity
cAonot be peculiar to nitrogen. If it is legitimate to assume that
hydrocarbons and cyanogen would behave similarly, it is not a
long 8tep to assume that it is as likely that luminosity will arise when
imail specks of cometary dust or solid particles are rushing through
th* gaa (fxjssibly in a sensitive state), as that luminosity should be pro-
daced when the gas ruah^ past the walls of a small crack into vacuum.
Mr. H, F. Newall, ObservatioTts of Cyanogen in LXVra. i.
However the lummosity may be produced, the absence of
hnlliaiit display in periodic comets might, on the hypothesis of the
constant existence of tlie vapours in interplanetary space, be
attributed to the gradual change in tbe surface of the solid parts
of the head of the cornet^ or to the exhaustion of the emitted
influence.
My present purpose is, however, not to elaborate views about
comets' tails, but siuiply to point out that if one accepta radiation-
pressure and the phenomena of tbe repulsion ^jf comets' tails^ one i«
driven to admit the existence of vapours and gases in circntuMi^lar
space, however diHieult it may he to give account of their
quantitative distribution in such space. The great extensions of the
corona (as was pointe<l out by Huggins in his Bakeriaa Lecture,
1S85), and tbe equally great extension of comets* tails, demand the
admission that at any rate temporarily gases and vapours must
exist in "free space.'* How long the clearing process lasts, which
depentls on the conflict between the pressure of radiation and the
gravitative attraction of the Sun and the planets, is another
matter.
It is difficult to devise crucial observations which would decide
the points raised by these views. For it is to be expected that
gases and vapours, if present at all, would be in such a turmoil of
rotation round the Sun that tbe inte^jrated effect of their absorption
could hardly give defined lines or bands of absorption, except in
the case of accidentally related motions in the vapours at different
distances from the 8un, The best way to proceed seemed to be to
make special observations of the cyanogen bands, and so learn
wliether there really are any peculiarities to be found in their
behaviour. Professor Hale has pointed out (Aitroph, Jour.y xxv,
310) that the cyanogen fluting at 3883 is very decidedly weakened
at the limb of the Sun relatively to the centre of the liisk,
Humphreys has shown {Astroph, Jour.^ xxvi. 28) that the lines of
tbe cyaiiOjjjen bands are not appreciably displaced in the spectrum
of the electric arc, even at the highest pressures used by him (100
atmospheres).
The inatrumentuscd for the observations of the cyanogen handa
is a new grating spectroscope made by the Cambridge Scientific
Instrument Company, and recently mounted for solar observation
at the Cambridge Observatory, It forms part uf the installation
which is in course of construction for solar work, Tbe general
form of the iuptallation has been indicated in a previous paper
communicated to the Society (Af.N., Ixvii. p. 161.) The
observatory is indebted for this efpiipment to the munificence
of the late Frank McClean, F.R.S,
The spectroscope is of Littrow type, *.e* one and the same tube
and object-glass serve both as collimator and camera, the slit and
photttgraphic plate being slightly separated in the focal plane of
the comniun object-glass. The lens has an aperture of 4 inches
|ioi mm,], and is of focal length 14 feet [4267 mm,]. A RowUnd
Nov, 1907. Solar Atmo$^?herf' aitd in InUf^^*
f lut If t Y-/"
plane grating, with ruled surface 5 >« 3J inches [127x89 mm.]
with 14,438 lines to the inch, is used to produce the spectrum. In
order to allow of the use of spectra of high order without the
troubled introduced by superposed spectra^ a priam of small angle
5' and of circular aperture 4 inchea [lot iuul] has been inserted,
with its refracting edge perpendicular to the rulings of the grating
between the grating and th»3 object-glass. Both object-glass and
prism are the work of Messrs Cooke & Sons of York, and are of
excellent performance. Provision is made for tilting the spindle
and frame, which hold the grating, about an axis parallel to the
refracting edge of the prism ; in this way any part of any spfctrum
is brought to the centre of the photographic plate, and the
dispersiou is such that the ordinarily superposed spectrum is
thrown above or below. Tlion, on turning the grating about its
axis of rotation, the succession of n]:ipearances in the field of view
is iuch that the blue end of the spectrum is seen at tbe bottom of
the field of view ; as we turn tuwanls the j^^reen, the spectrum
mounts to tbe middle of the field ; and on turning further, the red
is to be seen at the top of the field. By the tilting of the spindle
<_.—-—--' -'»* ^t"*^*
m
on which tlu' grating turns, any part of the spectrum can be
brought to the middle of the field,
'Ihe instrument, which is of very rigid conatruction and weighs
about 6 bund red wei^dit (300 kilogrammes), has been mounted hori-
zon tally on roller bearin^^s, \vhich allow of easy rotation of the
whole about a horizontal axis, ho that the slit can be turned into
any position angle. A position circle is provided, divided to half
degrees. The axis on which the instrument turns c<*incide8 with
the line joining the middle point of the slit to the middle point of
the object-glass. In this way a horizontal pencil of rays incident
from the proper direction on the centre of the alit always passes
thrimgh the centre of the colli matnr-ramera lens, whatever may be
the position anj^le of the .stit. The true optic axis passes through
the fo<^al plane at a point midway between the middle point of the
•iit and its imaj^e; this |M:*int thus describes a small circle round
the middle of the slit as the whole instrument is rotated on its
PiUor bearings. The mi^ldle pant of the photograpliic plate
ttmilarly describes a concentric circle of twice the radius.
Black opaque diaphragms of the proper size have been inserted
in the proper places between the slit and the ohject-glasSj in order
til prevent the light reflected from the surface of the lenses from
(ailing on the spectrum on tbe photographic [ilate.
8 Mr, H. F. Newall, Ohservudums of Cyanogen in LXViiL
A convenient device ha^ been added to limit the length of the
slit used, and to allow of the joxtaposition of spectra in successive
exf»08ure8 on one and the same photographic plate ; thus a spectrum
of the east limb of the Sun can be photographed between two
speetra of the west limb, or two spectra o! the east limb can be
alternated with two spectrin of the west limb.
In the preliminary work with the instrument great care had to
he exercised in overcoming the erratic performance nf the grating;
and in order to secure tht; defining power required for this work it
was found necessary to limit the area of the ruled surface by means
of diaphragms carefully placed. When all the ruled surface except
a strip 5 inches wide and about if inches high Wiw blocked out, it
was found that excellent detinition cuuld be attained with fulj
resolving power ; au«i the exposures needed for photographing the
cyanogen band at 3883 in the spectrum of the third order seldom
exceeded a minute, and in a bright sky an exposure of 30 second*
waa ample.
The photographs obtained with the instrument exhibit the
spectrum with very open scale, and many of the dose double lines
even in the cyanogen band are well i^een. The linear dispersion of
the negatives is such that we have about rag tenthmetres per
millimetre. And it should be remembered that the total exposure
of a plate in the instrument was completed generally in leas than
3 minutes.
Examination of the photographs obtained disclosed peculiar
features. It was at once evident that the spectrum of the east
hmb was nearly always less wetl defined than the sspectrum of the
west limb over a considerable region of the spectrum near the
cyanogen bands. The photographa dealt with may be divided into
two classes: hrstly, about 35 ** adjustment photographs" taken for
finding the be?^t adjuatuient of the instrument and for testing the
effects of some exaggerated maladjustments; and secondly, about
10 ** rotation photographs," each exhibiting two spectra of the east
limb alternating with two spectra of the west limb, all taken with
approved adjustment of the instrument.
A great deal of care and time have been devoted to the, critical
study of the evidence ; and though at firnt I was led to suspect that,
in spite of great care in ndjusting the instrument, and in making
sure that the optical beam was arranged exactly similarly both for
east limb and fur west Hmb, some unexpected error bad crept in,
I am now convinced that the right interpretation of 'he peculiar
effects lies in accepting them as real, and not instrumental.
The spectrum of the east limb was in nearly ^xery case less I
clearly defined than that of the west limb. Now, in a malfucuBded
photograph, one can, from the a[>pearance ^nesented by a aingle
isolated line, predict with considerable certainty what the appearance
t)f various groups of lines will Iw, But the appearances preaented
by the sfiectra of the east limb do not agree with prediction based
on study of isolated lines or edges. In particular, the cyanogen
hand itaeJf at the east limb shows in general a double edge, as if
Nov, 1907. Solar Atmosphere and in Interplanetari/ *b/j<w<?. 9
two similar buods are superposed, with slight relative liisjil a cements
which vary from day to day. The cyatioyen baud at tl»e west limb
abows in general a .-single slightly ioteosihed edge, as if there luight
be two bands »upeij>Oi*ed, with such slight displacement as not to
be measurable* There are many other minute differejices between
corr««ptnidinij lines in the spectra of the east and west limbs.
Three of the ** rotation photographs " were picked out a» show-
ing the best definition : namely
L. 32 1907 Sept. 15, 10.23 '*'^- O.M»T (civil).
L. 42 „ „ 12,20 „
The^e have been measured by my assietant, W, II. Manning,
under my dire<!tion. Six iron lines, two chromium lines, and five
cyanogen lines were chosen for measurement between wavelengths
3S71 and 3898- Each plate was measured twice in reversed
tiona on the Zeiss Comparator, The values of the displa^ementft
[oli). East- West, are given for each line in the following table;
the values are expressed in millimetres. Four of the five cyanogen
liot^s are really close double pairs, which were bisected hs single
lines. They are indicated in the talHe.
Wftfe^ength,
OrlgiiK
L. 32.
L, 4a,
U 42.
Meati.
3571-963?
Fe
0*0330
0-0344
0-0304
0*0326
Fe
73-065
CN
347
297
397
347
CN
73-903
Fe
336
316
3i2
32i
Fe
76*«15
F«
363
342
35 S
353
Ft*
•■)s
CN
329
3»7
334
S^7
CN
"-issi
CN
322
36S
359
349
CN
-tsi
CN
275
34S
2ik)
300
CN
"tiSI
CN
287
344
2S4
305
CN
«3-77«
Qt
255
267
301
274
Cr
«S'657
Ft
299
326
306
310
Fe
S6942
Cr
323
338
345
334
Cr
90-^
Fo
321
343
330
33 «
Fe
3^7596
Fe
301
32i
337
Meaa
320
0-0323
Fe
U will be seen that
mm.
6 iron
lines
give a mean displacement,
£ -W., 0
•0327
2 chromium
>i
^t
ti
0304
5 cyanogen
rt
ft
>»
0326
lo Mr* H. F, Newall^ Observations of Cyanogen in LXVili. i ,
It thus appears that the cyanogen lines give displacements (and]
oonaequeiitly alfto a solav rotation-perio^i) sensibly the same a»i
those given by irou lines of solar origin. These displacements of
lines relate to spectra taken from solar light gathered at the east
and west ends of the solar equator, within about 5" of solar latitude
from the equator, at points situated within the limb by about ^ of
the radius of the Son's apparent disc. I do not put them forward
as sati.'^ factory determinations of the equtitorial velocity of the Sun.
To deduce the velocities correspondmg to the dit*placements, we
must use a factor^ L/X » dK/dU^ which works out to be sensibly 100.
For the velocity per tenthmetre (L/X) is
77'49 km/sec at wave-length 3872
and 76-96 ,, „ 3898
whilst the linear dispersion is such that dkfdR is equal to
1^297 tenthmetres per milliroetre at 3872,
and to 1-299 „ „ „ 3898.
Thus the factor ranges from 100*6 to 99*8, and for our present
purposes we may take its value as 100 over the range of spectrum
measured, «
Ht?nce the displacements expressed as velocities are
for the 6 iron lines, 3*27 km/sec
2 chromium ,» 3*04
5 cyanogen „ 3-26,
The correapondiufij equatorial velocities are got by halving these
cumbers. It is seen that the uncorrected numbers are a little
lower than Dunc^r's and Halm*8,
The main point, however, is that for these three determinations
cyanogen is shown to be in the solar atmosphere in the same sense
that iron and chr(>minm are.
The wave- lengths of the cyanogen lines uaed in this determina
. tion iiave been also deduced with reference to three iron lines
standards. They are found to differ from Rowland^s value** by
less than one hundreth of a tenthmetre, as will be seen from the
accompanying table.
WAVfi'lcnjrth Adjiistmeiit
K.0
LAtlOD JTlftie
i.
Menu.
Oricii
(Rowland). Hatfl L. 20.
L.fB.
L.n.
L. 42.
3871-963? 3871 S87
*88i
•887
-S8r
^884
?
73*073 73072
'069
073
•069
•071
CN
73*903 Standard
...
(^903)
Pe
76-815 76813
■805
•8l2
•813
•Sil
Fe
8^' {3^} (^^6) 82-272
266
-271
•274
•271
CN
82*{|^^}(4S5) 82-483
•472
*479
•483
•479
CN
Not, 1907, Solar Adnosphere and in Interplanetary Spa^x. i r
tHovlaodX
AdJnstmeDt
Rotation Pl&tai.
Mean.
Qriglii
L,8i.
L, 41,
L,42.
^•{5in«*^o
82-682
-673
677
'679
'678
CN
«.-{g;}(S6o)
82-856
'850
•856
853
•S54
cir
5377s
83782
774
774
■772
775
Cr
85^57
Standaril
(^657)
Fe
se-^SH^
86-945
'949
•949
•95 »
•948
Cr
90-986
90-989
-984
'983
'988
^986
Fi?
97596
Standard
(■596)
Ft?
The apparent duplication of the edge or head of the CN band is,
as has already been stated, more marked at the east limb than at
the west. It is much more difficult to meftsure the di9pla<^ement of
edges than the displacement of lines in the hand. Nevertheless I
have made some measurement* of the diaph\cement ; and if these are
interpreted as indicating a Doppler effect, the results may be
summarised aa follows, the velocity of the east limb always being
toward*! Earth.
Pltfto.
I>at«.
£a«t Limb,
Weft Limb.
L. 6
1907.
Aug. 17.
h ro
5.27 p.m
1
kSjieetru »*iniilar.
No nioastirablc diaplace-
L. S
StfpL 6,
10.50 a. 11L
Velocity 16 km/sec
Displacement vl
L. 10
Sspt. 8,
10 ,,
,, I4^iii/se<'
9
1.14
M
3^55 P»m.
,, 12 kni/8ec
L.32
Sept 15
10.23 a.m.
„ 't 4 km/MC
L.41
M
11*54 ..
,, 1 5 Wmyaec
L.4^
V»
12.20 p.m*
, , f 5 kin/8«c
Thia progressive change of the dTiplication <>( the edge is seen to
go on for 9 days, and so can Imrdiy be connected with ordinary
disturlmncea of a local nature on the Sun's surface* The cyanogen
involved cannot be far from the Stin^ for otherwise it would be
detected in the 3[»ectra of iioth limbs. It is seen that nothing of
the order of cometary velocities is as yet detected.
I have spent some time in crmsidering the |)Ossible influeDce of
Daniel*** comet which reached perihelion 00 September 4, witli a
felocitjof 5g km/sec at a distance 0*5 12 ; the Earth passed closest
v* the pth of the comet on September 12, as was pointed out
l\nt£inger (Ait Nach.^ 4198)- The comet itself had passed the
|H uiL on July 27. But in the itolar spectrum no sign has been
^►V-r:te<i that can fairly he attributed to the presence of the comet
inarthe Sun,
Moch more evidence is required before the case can be com-
pletely elucidated, and this note most be regarded as of a pre*
^minary nature.
12
Mi\ John £lversh4d.
LxvnL I,
77* e Ultra- Violet Region in Sun-spot SpectrtL
By John Evershed,
It ia well known that th<^ mora conspicuous of the Knes whick
are intensified or otherwise atfected in the spectra of sun-spota are
found in the less refrangible region of the spectrum, those in the
red being by far the most easily seen, whilst in the ultra-violet the
lines ^if the same elements, although far more numeroni in this
region, »eem to be totally unaflTeoted.
A considerable number of phoiographa of sun-spot spectrai,
taken in the ordinary way, in the region more refrangible than G,
have from time to Lime been examined in detail by the writer, but,
excepting always tbe hydrogen lines and H and K, these have
always shown an entire absence of details which could be certainly
distinguished from the adjacent photosphere spectrum.
Recently^ however^ with improved apparatus and exceptionally
favourable atmospheric conditions, a series of spectra have been
obtained at this observatory showing a considerable namber of
affected lines in the region k 3990-4350.
Owing to the intrinsic darkness of the spot band in the ultra-
violet, a very long exposure is necessary, in photographing the
umbral spectrum^ to give a density equal to that of tbe spectnim
of the surrounding phutosphcTM. Thus I have found for the region
near K the umbra requires from ten to twelve times the exposure
needed fur the photosphere, and it is obvif>us that in long exposures
the diffuse light from the sky will impress the plate more or leas,
superposing the general solar spectrum on the true spot spectrum.
It is questionable, liovvever, whether this admixture of sl^light is
sufficient to explaiti the apparent poverty of detail in the ultra-
violet, as compared with the red and yellow regions of the spot
spectrum.
The photographs were t^ken in the fourth order of a Rowland
plane grating, having 14,438 lines to the inch and a ruled surface
of 3 inches. The collimator used is a visually corrected lens of
2 J inches aperture and 36 inches focus. The camera lens is a
plano-convex of 4-in. aperture and 7-ft. focus for H. The »lit
is provided with a sliding shutter, having a < -shaped apennre,
which enables its length to be varied within wide limits during an
expo^urt^ In photograi^ving a spot spectrum, the slit Is reduced
to a length equnl to abuut I w<j thirds or less of the diameter of tbe
umbral image. A long exposure is then given, after which the
slit is lengthened, and the exposure continued for a short interval
to impress the adjacent photosphere s^pectrum.
The spectrograph was erected in the spectroheliograph rooro»
using as image lens the iz-in. photo-visual lens usually employed
for the spectroheliograph. The exposures given on spot and photo-
sphere were as follows : —
Nov. 1907. The Ultra- Violet Megmi in Sun-spot Spectra . 13
PUU€ ttepotid 1907 Jntae 20. a 3900-4140.
TobaJ £xpo«ixr«.
135 fleeondA
205 1.
225
0.
Cmtin,
Photutfihere
«nd Umbra,
1
120 fiecotids
15 ^econcU
2
180 ..
«5 .,
3
205 ,,
20 „
i^laUi txpoaed^
1907 July 16.
1
20 secoii«lA
7 seconds
2
30 »,
5 ..
3
40 „
5 ..
^ 4090-4350.
27 seconds
35 ..
45 ..
The tirst set of three expuaurca represents the spectrum of the
Urge southern spot, which passed the central meridian on June 21.
The second series represents the same spot after a rotation of the
Sun, The latter was not obtained under nearly as favourable con-
ditions aJ9 the former, and probably many more affected lines will
be added to the list in subsequent photographs.
The two plates were examined and measured quite itide^
j«udeDtly ; and in the region wht-re they overlap, the agreement in
\be estimates of intensity was reniarkab]y good^ althongh, as Maa
to lie expected, fewer afleeted lines were noted on the July plate.
In the following table I give only those lines in the spot
%|>ectninj which can be quite certainly distinguished from the
jihotosphere spectrum by an increase or decrease of intensity, or by
liie absence of a line in the one spectrum which is present in the
olber. Since a considerable number of the lines visible in the
umbml fpectriun could not be traced on the ph^jtosplierp 8]iectrum,
ibe positions of these were measured with a micrometer with
rcipect to neighbouring known lines, from whi<:b the wave-lengths
ttre deduced. The measured wave lengths are given in the first
two columns to two places i»f decimals only, to distinguish them
from those lines which could be identified with solar lines by
iiitpection : to these Rowland's values of the wave-lengths are
pT«!ii. The third and fourth columns give the estimated intensities
;«here and umbra respectively, tlie former being from
table. In estimating intensities the spot line is com-
(^ed with one or more of the neighbouring solar lines having the
ami apparent intensity, and the intensities of these comparison
tmes are taken from Rowland^a table after comparison with Higgs'
map.
It is to be m>ted that, as in the visible region of the spectrum,
titanium and vanadium figure largely among the strengthened tinea,
rhtlst of the seven afiected iron hnes six are weakened in the spot.
The hydrogen lines y and 6 are notably weakened, both in width
ami intensity. Both are di.splaced relatively to the phot^isphere
tinAB, but, curiously enough, in opposite dirfcctions, y "05 towards
the rod on the July plate, S the same amount towards the Violet
I both platoft
14
Mr. John JEvershed,
LXVIII. I,
List of Lines affected in Sun-spot Spectra in the region betvfeen H( and Hy.
Senuurlu.
Plate
ExpoBe«l
June 20.
Plate
Exposed
July lb.
Intensity Intensity
in Photo- in Element.
Umbra.
sphere.
3911*316
391487
3930-022
3933-825 K
3960-422
3964-663
3996752
3968 625 H
4015-532
4017-925
4019-450
4023-834
4047*93
4048-224
4050-830
4054-69
4064-36
4095-423
4095633 4095*633
4097-61
409i>'335
4099-327
4101*921
4101-85 H5 4101-85
4102-31
4102*52
4102-71
4105-318
^105-98
4102-31
4102*55
4105-318
4105-92
41 in 54
o
o n
4
3
00
I n
2
I
o
o
000
5
00
2
40
2
000
I
3
<2
2
2
O
4
2
I
10
2
o
00
5
o
00
Nd
Fe
Ti
Ca
Fe
Fe
Ca
Ti
Co
Sc
Fe
Ti
Mn
V
Fe
Ti
Fe
H
The solar
3194*880.
line is at
Narrow bright line. Not
displaced with respect to tlie
t^hromosphere alworption line
K3.
Narrow bright line. Not
displaoeil with respect to the
chromosphere absorption line
H3.
Absent in photosphere.
Absent in umbra.
The solar line at 4054*591
is distinctly more refrangible
and gives the umbral line a
shading on the violet side.
Absent in spot
Probably the line at 4099*207,
intensity o, is included.
Much reduced in intensity
in umbra and displaced to
violet -05 A.U. in lK>th
fjpectrH.
Probably this is the yttrium
line at 4102*541, intensity o.
Mnl k\\\\o%\. c\A\t«ni.\Ad..
^^M
^^^j
Nov. 1907. The Ultra- Violet Region in Smi-spot Spaitra. 15 ^H
List <i( LintJf affected in Stin-itpoi 8pticlra^ etc, — contmued. ^^^
Ptau
EspoMd
Plate ]
KkpCUGd
July t6.
tnteuslty
•phert:.
Inteuatty
io
Umbra.
Element
Remarks. ^^M
A
4JI2'869
X
I
3
Ti
fl
4H36S
4»»3-69
ooon
\
Probablj it double line. ^^|
4114^
4114 j8
00
2
^H
4II7113
0
...
Absent in umbm. ^^M
4117*61
41177^
0
^H
412074
4123*664
4l2j'9tJ7
412074
5
1
5
r
xMti(
Dititinctly ]ti^s ri^fraDgible ^^H
than the solar line at ^^H
4120775. ^M
The iutensities u( theae two ^^M
lined seem exactly rever«ed lit ^^M
the umbra. ^^H
41255^
000
3
^1
412846
...
00
1
^H
412S-S94
4128-894
2
Absent in ymbra. ^^H
4129 10
...
2
Absent in pbotoaphere. ^^M
4i3t SO
4131-507
0
I
Cr
^^^^H
4*31^
...
0
.**
Absent tu photonphere. ^^|
4135915
4139*60
SfwotruTu
reds at
4140
4140*910
414678
4153*^
0
00
0
00
1
3
0
2
1
Zr
Cr
Pr^ibabty a double Uue. ^^M
AbsGUt ID photu»phBr«. ^^|
4159*805
0
I
Ti
^H
416318
1
^H
4252 '468
0
>t
Co
^H
4362 0S6
2
I
^H
4262-142
^H
4281-530
0
2
Ti
^H
4299803
2
3
Ti
^1
4300732
4340*31
5
0
4
Ti
Cr!
Rowland giv«a intensity 2, ^H
which seems too small. ^^M
4340-68
4341 "107
20
0
to
2
H
V
The liuH ia about '60 wide ^^H
in mn, and '35 in Hpot, where ^^M
it U displaced towards red, ^^M
05 unit. ^^B
I
Sp*ctniin
ends at
4350
1
_
B
^^^^J
l6 Mr, John Ever&h^d, LXVm, l^
The Spedrum of Comet 1907 d (Daniel). By John Evershed*
NotwitlistandiDg the yery uafavowmble conditions prevailing
here during the south-west monsoon, at temp La were made to
photograph tht) apectrum of this comet on several occasions in
August and September. Owing to the short intervals of time practi*
cally available for making expoanres on the comet (three-quarters of
an hour at most), it seemed necessary to use a spectrograj^h having
the greatest possible light-efticieiicy. I therefore determined to try
whether an objective prism 8pectrogra[.ih of short focal length could
be successfully employed. On account of the almost constant
presence of cloud, more or less thick, in the ea^iitern sky, the results
do not cnme up to cxpectrition, but are perhaps of sufficietit mterast
to place on record.
A prismatic camera was constructed with the two very perfect
60° priams, of j^pecially selected crown glass, which were successfully
used at niceiit eclipses, Tije prisma have an effective aperture of
42 m.nu, and the photograi'hically eorreclt^d lenn has a focal length
of ahout 600 ujm The instrument was attached to the 6-in.
Cooke equaturial in the south ilomo oi this observatory, the plane
of disf>ersion being made parjillel to a circle of dech'nation. For
guiding, a straight-edged bur was placed in the eyepiece of the
finder attached to the pquatorijil, and this was made parallel to
thti diurnal motion. In making an exposure, the comet's nucleus
was kept on the fd^e of the liar, and nearly in the centre of the
field (defined by a cross-wire), by means of the slow-motion bandies
of the equatorial.
In the course of several weeks, about the time of the comet's
maximum bngbttiess, only three fairly favourable opportumties
occurred. These were August 28, iSeptember 3, and September i 5,
The best result was obtained on the first-named date, with an* ex-
posure of half an hour. On September 3 the comet was obscured
by clond ftu- about half the available time before daylight, and
during this interval the opportunity was taken to photograph the
spectrum of Procyon on the same plate, the star being brought to
the edge of the bar in the eyepiece, but at a little distance from
the centre of the tield. In the plate exposed for twenty minutes on
September 15, under apparently favourable conditions, no trace of
the §pectrnm can he seen. This is probably due to the low
altitude of the coiMst, for the spectrum of Regulua, then about 5' N.
of the comet, ia only faintly impressed on the plate. Wratten's
"Drop Shutter** plates were used in all the trials.
In the ^*pectT^m of August 28 the most striking features shown
are a pair of extremely bright lines in the ultra-violet, corresponding
with the nucleus of the comet,* and a series of monochromatic
ime^es of the tail, havine the following approximate wave-lengths : —
^ 35^* 369, 37S, 401, 426, 455.
* Owing to A alight drift of the comet in E. A., the inimgea of the nucleus
fm. 1907. The Sptcirum of Comet 1907 d {Danul),
17
These radiations at© not specially bright in the comet'a nucleus,
they exteod from '5' to i"5* into the tail, whilst the above-
eiitiimed bright lines seem to be confined to the region of the
RUcleus. Altogfetber 1 2 lines or groups of lines have been measured
on this plate, and the wave-lengths determined graphically, using
the 12 hydrogen lines from 11/3 to Hv inclusive in the spectrum
of Procyon and of Sirius to obuin the dispeeaion curve. In the
ectrum ot September 3, with Procyun photographed on the same
ite, the pair of bright lines in the ultra-violet are seen to be a
iltle more refrangible than Hf (X5SS9); and as their distance
corregponda with about 1 1 untra in wavelength, there can
be no he^itation in ascribing them to the cyanogen lines at \ 3871*5
and X 5883*5. In this plate^ however, the images are too faint for
measurement.
In the table which follows are summarised the results of
measures of the spectrum of August 28* As most of the spectral
_es on this plate are broad and ill-defined, I give in the second
it» the approximate limits of wave-length of each line or hand ;
aod u\ the third column the mean wave-length, or the positions of
maximum brightness. In the fourth column is entered the length
of tail in degrees which can be traced in each radiation. I can
«s*ign no origin for the radiations, which seem characteristic of the
tail, except the band at k 455, which, according to Campbell, may
robably be due to cyanogen.* The continuous spectrum, which
\ faint throughout, ends at about X 490.
Ko.
Limits
357.
359 f
367 \
370 \
377.
380 I
3«63 \
3S85 (
Mean \ Le»«^^ ^^f '^*^1 Probable
iu Degret^s. IdentilicatioD.
35S±
6 3995 I
4034 I
3»73
38S4
4015
*3±
r6
Cyanogen T
Remarka.
Exceedingly faint
images of tail.
Cyanogen. Very int«»a« line» :
Cyanogen. 38S4 the strougest in
the whole Bpectrum.
S 4190*
4aoQ
4215
»..
Extremely faint traces
..«
of Uil. Campbell
giT» a faint tiiM
at 4126 in comet 6
of 1S93.
Cyanogea.
Kotaih Trac«oflin«B
Cyanogen.
at thew poaitioni.
• /W. j4if. Sae, Paeifi^^ rol, v. p. 209,
1 8 Ancient Solar Eclipses discussed by Mr, CotmlL LXVllL i>
No.
Limits
of A.
9 4239 (
42S2 i
„ LeiJCth of Tail
Prob&ble
I dt?uti fixation.
Remarks,
4260
4360
I '4
" 4523 »
45S4 f
12 4650 i
473^/
4553
461^2
A very faint line if
given by CAmpbell nt
X 426 in comet h of
1893.
.., Faint bright spot iu
con ti ri Quus speotru til*
A bri^cht line is given
by Campbell at \
4366 in com«t b of
1893.
Gyftno^eo ! Campbell giTea a band
near A. 455 in comet
c of 1893,
Blue banil Max. brigUtTi«sa esti-
of carbon, mated at A 4682.
Kodatkfinal (Haervat&ry.
Note Oil the Ancient Stdar Eclipses dhcussed by Mr. CotvelL
By A. C. 1), Cronimelin.
The reaultB derived fmm these eclipBea by Mr. Cowell are so
importatit and far-reaching that it ie tiesirahle to remove
imcertaiiitv aa to possible errors, especial I}' in view of the tsu&%
that Mr, Nevill piibli.slied some results purporting to be deduced
from the same formula, but 1 neon si stent with those given hy Mr.
Cowell himself ; I accordingly undertook an independent calculation
of the six ecUpses - 1062, -762, -602, *- 584, - 430 and + i97ij
which are the most important and best authenticated ones,
obtain results practically identical with ^Ir. Cowell, the discorilance*
in no caee exceeding 2', which i« an absolutely negligible quantity.
Several stnaller terms in latittide were tben introduced^ which
had some slight effect on the residuals^ but not enough to affect
the argument itj any way ; they f)o?flibly produce a small diminu-
tion in the relative acceleration of the Sun and the notle, but only
to the extent ul J" or less.
Two points suggest themselves as worthy of mention regarding
the eclipse of- 1062 ; viz. — (j) Mr, King's recently published book
gives a translation of the inscription in which it occurs, which is a
record of omens occurring in the city of Babylon {wiJd beast«
entering the streets, doga entering the temples, etc.) ; hence there
Nov, 1907* The Permanency of norm Photo-visual Zemes. 19
cah be do renfionable doubt that the extinction of the Sun, racorded
M ao omen, was likewise mtnessed from Babylon itself,
(2) The date of the phenomenon is faven as Sivan 26 ; dow^ ae
the months began with the tii^t observation of the Maoii, the 26th
of the month must be witliiii a day or two <if new moon : this
deddedJy increaBes the probabiUty that the recorded solar darken-
ing arose from an eclipse.
Both Profeasior Newcorab and Mr. Nevill have rejected the
tfnggeeted explanation of the ap[iEirent acceleration of the San aa
arising from a diminution of the Earth's rate of rotation. The point,
however, is such a simple one that it seems worth while to respite it
in other word*, in the hope that they may more definitely indicate
their reasons for dissenting; from it.
(l) A slowing of the Earth's rotation from tidal friction
neoeBsarily involves an increase in the Moon's distance, in order
that the moment of momentum of the Earth-Moon system may be
comer ved.
(t) A rough calculation was given showing that the lengthening
of the Moon's perii»d arising from this may be nearly as great as the
apparent shortening due to the increase in the length of the day*
(3) In the case of the Sun's period, the shortening due to the
latter cause would act unimpeded, so that an apparent acceleration
of the Sun comparable with that of the Moon would result.
Note on the Permanenq/ of gome Phnto-vuutd Lenses,
By William J. S. Lockyer, M.A.^PhJ). (Plates t, 2,3.)
The Solar Physics Dbservatory at South Kensington is in
sion of numerous photo-visual lenses which are employed in
oeraral instruments in frequent use. Ail these objectives have in
time developeii curiou» markings on one or more of their internal
surfaces. The object of the present note is to draw attention to,
and to give a brief description of these markings.
Each of the lenses in qtieation consists of a corabination of
three elements, the front and back lenses being double convex and
the middle double concave. The front snd middle lenses are
nearly in contact, but a small air-space sepamies the middle from
the back lens.
The material with which the lenses are made is as follows : —
The front lena is made of S''hott*s baryta light flint glass
/O 543), the negative or middle lens is of Schott's boro-silicate
(a variety of their O 1 64), while the third is made of a
ite crown (Schotfc's O 374).
The lenses to which reference will be made vary in aperture
from 3 to 12 inches, and have been left, as regards their inner
«urfac69y untouched in their respective instrnmenta for p^noAa
faixiAg from ij io Bj months.
^^M
r
■
n
^^^^^^H
^^M
I
^
^^1
■
wo
p
& Lockt^er, Note
on th€ LXVHL I^jJ
i
i
•5
"at ^
Is
3
s
^ i
i
{1
^1
1
tiil
■ss
0
^H
i
1
i
1
SI
-21.1.5
8" "I
o£ ".2
^111
as
in
•*- .ti **
5^ S
5T^ 0 S 1
^p 11 ■
II.. =11
ji-i s as
li
fl
f?
^
«
^
j^ ^ ■
J
i
t
i
1
^^^H
l|
00*
M
t*
«
" fl
i
a'
1
1 1 ■
ll
t
1
1
1 1
If
1
i
1
1 1 1
H
H
4
^
>A
^1
t
h
M
^
^
m
fov. 1907* Permanmey of some Fhoto-visiial Lenses, 21
The preceding table contains a summary in convenient form
Tir ^i the intervftla between the times of mounting and dis-
ru ■ ■ :^ the objectives, the conditious of their situation, and
bnef notes 00 the markings deve]oi>ed.
In or<ier, in the first instance, t<.i indicate the appearance of the
markings in que^ition, the following four selected photographs will
erve ns examples. It may, however, be first mentioned how these
liotographs were aecured.
The whole combination wm first removed from the instrument
in which it is employed and place<l in a Vahaped wooden stand in
front of a window. The cameni was placed about 2 feet away
from the lens and about 3 feet from the window, when the
markings were carefully focussed on the ground- glass. The
aystem of illumination of the lens under examination waa as
follows. The space between the lens and th« camera was first
covered in with black velvet. About a foot away from the lens,
llut on the opposite side of it to the camera, a large dull black
liece of cardboard was placed near the window in nearly a vertical
D^ition to serve as a black background. The lens itself was
Juminated by daylij^ht passing through the window and falling
bliquely on the back portion of the combination. Unfortunately
was found very difficult to eliminate the reflections of the window
3m appearing on the lens, but they are not sufficient to detract
frum the main object for which the photographs were taken. The
photographs show, therefore, tlie peculiar markings on one or
more of the inner 8urfac€»s of the len86«| as white on a dark
background.
Fig. I (Plate i) represents the 3-in. objective which has
been employed in an instrument for 83 months. The markings,
it will be noticed, are small, and near the middle give the lens a
diettnct mottled appearance. Nearer the edges their structure
becomes more pronounced, and there la a greater distance between
them.
Fig, 2 (Plate i) representa the markings on another 3-in.
lena which forms the camera objective of the same instrument.
Thia lens was mounted and dismounted at exactly the same time as
that shown in fig. r (Plat^ i), and during this interval of
S3 montlis it was situated within a foot of the other lens.
The different structure and number of the markings h very
striking, and can be judged best by closely examining the
photographs.
In fig. I (Plate 2) we have another example of quite a different
ftpf^earance. This lens has an apertiire of 3*5 inches, and has been
in oae as an objective to a small telescope for 40 months. The
Qsridngs in this case are of a much finer type than those
previously mentioned, and are far more elaborate in their structure.
Thia lens exhibits, in addition, a second set of markings, which
fippe«j« on another of the interior surfaces of the combination^ but
which could not be photographed under the same illumination biH^
diManc^ Mud therefore mnnoi be seen in fig. i (Plate a^. B^
22 Dr. William J. S. Loehyer^ Note on the LXvni, I,
reverBiDg the combination in the V-ehaped mount, refocussing the
camera and varying the direction of the daylight illtiminatiou,
a very snccessfid negative was secured, a reproduction of a
positive from which is seen in fig. 2 (Plat« 2). Around the
centre of the lens will be obser\ted a great nmnbet of small white
spots which represent the markings in question. These are quite
different in form and character from any of those which have been
previously described.
In the case of two 4-tn. lenses a recent examination has
shown that after an interval of 35 months they are just
beginning to show signs of development of markings.
In this initial stage one has observed, with the help of a
wfttchmaker*3 glass only, that the m&rkingr^ t-ake the form of very
small single streaks, more or less homogeneously scattered over the
whole lens, but a little more sparse nearer the edges than aboat^
the centre.
The large 12-in. objective has developed those markings at
much greater rate. After an interval of only 23 months very fine
markings, of simple structure, but fairly closely pai-ked together,
extend over the whole surf nee of the lens, and, as before, their ^
Btmcture becomes more complex as the edge of the lens
approached.
So far, no mecition has been made as to the particular surface
of the combination on which the markings are to be found. As a
matter of fact, although it is quite simple to take to jiieces any of
the lenses which have been examined^ it is not easy to replace them
properly centred in their cells. For this reason, therefore, only
one of the above-mentioned lenses has been thorotigbly examined
by separating the component lenses forming the combination. The
particular objective thus treated was that of 3*5 inches aperture,
and it exhibited both kinds of markings to a very great degree.
When markings were first noticed to develop on one of the
inside surfaces of the combination it was thought that they might
be due to the possible lack of jjermanency of the boro-silicate flint
glass, since there seemed more doubt connected with the per-
manency of this naaterial *" than with those used for the other
lenBes. It was therefore found, with some surprise, that when
the 3*5-in, objective was taken to pieces^ both surfaces of the
negative lens were perfectly clean and unmarked, and therefore
not deteriorated in any respect. This result was highly satisfactory
from the point of view of the lasting power of the boro-silicate
tlint glass, and showed that, as mounted between the two other
lenses, 40 months' use had not affected it. It was the inner
surface of the back lens, of light silicate crown glass, which was
affected to the greatest extent, and on which the markings illustrated
in the above figures were scattered. This surface, it will be
remembered, is separated from the back surface of the negative lens
by a small air-space. It may be mentioned that no balsam or like
• Especially where sulphuretted hydrogen or sulphuric acid abounds, as
In n town Atmoaphtre,
Nov. 1907. Permanency of some Fhvto-visual Lenses.
23
i
m
matorial is etu ployed in this comblDation to cement tbe lenses
tcigetber, bat the earfaces are kept separate bj thin washera.
In order to investigate more thoroughly the nature of the two
different kinds of markinf,^8, namely, those which appeared on tbe
ifuier surfaces of the back and front lenses of the 3"5-iii. objective,
tbe combination wad taken to pieces and the markings micro-
scopically examined.
This inquiry was facilitated by tbe kindness of Professor J, B.
armer, D,Sc., F,R.S., of the Royal College of Science, who not
iy allowed me to use one of bis mici'oscopes in his own room,
Hit also examined the markings with me. It was at once
obvious that we were not here dealing with any form of
vegetable growth, as seemed at (irst probable by the general
appearance of the markings, but that both kinds were of a
crystalline nature.
In the case of the back lens the crystallisation seemed to have
taken place on the surface of tbe lens, and bad the appearance of a
depoeat on tbe surface. Each fungus-like figure seemed to have
originated from a small area, m»t a single point, and developed
radially in numerous directions, throwing out rami fi cations aa the
growth frum this area progressed. nmjej> the microscope it was
found that the mar ki tigs were really crystals, forming at first about
the small area, and then gradually growing outwards, crystal by
irystal, until they formed chains of cryatak, giving the fangUB-like
owth described above. There seemed little doubt that if
process were allowed to continue, the individual groups of
crystals would all eventually unite, and seriously interfere with tbe
transparency of the combiiiatTon. In the lens under examination
aeveral of these groups have already becunie interlaced and instances
of thin can be seen in the centre portion of the lens illustrated in
% I (Plate 2).
In the case of the markings on the back surface of the front
wns, tbe form of cryatallisation is quite different. Here, under the
Icroscope, the markivigs (seen in fig. a, Plate 2, as white dots
ttered about the centre of the lens) are composed each of a little
gular group of crystals, formed one above the other, and pro-
ting from the surface of the lens, not embedded in it. There ia
app»farance of lateral growth to the extent described in the case
marking's on the back lens. ScatU^red over the surface of this
axe also small single crystals, which suggest the first stage in
ie building up of these heaps. In this case also it is probable
lat if this process of crystal I isition were allowed to continue, more
igle crystals would be formed, the single ones already existing
»uld each develop into a small pile of crystals, and the lens
uld gradually become less transparent.
By the kindness of Mr. W, H. Merrett, A.R.S.M., the Instructor
Assaying io tbe Koyal College of Science, I was permitted
m use of the photomicroscope set up in the metallurgical laboratory
iif that institution. With the help of this instmment aivd w\^\k
hia assistance I was able to take hrgB icale photograplia ot tW
ttlei
fth©]
24
Dr. William J, 8. Lockyer^ NoU on the Lxvin.
crystalline formations on each of the two lenses, and some of these
are reproiiucixi on Plate 3. ^H
Figs, It 2» 3 show three of the individual small groups oii^l
crystals formed on the hack surface of the front lens, to which '
reference has just been made. The magnifii'atiDn eru ployed for
these photographs was 700. It will be seen tlmt the formation is
quite irregular^ and, fis a rule, there does not seem to be a point of
ori«:in, as if their existence %va8 due in the Hrst instance to the
j^resence of a speck of dust. On the surface of this lens there
appear^ also single crystals which are totally different from those
just described. They do not show the lateral growth, as is here
illustrated in tigs, i, 2, 3, but they are very much more raised
from the surface on which tbey are formed.
The raarkings on tlie inner surface of the back lens of the
combination are illustrated in (iga. 4, 5; and 6 of Plate 3,
Fig. 4 givf*^ a geueral idea of the middle portion of one of the
groups under a magnification of 45 diameters- It will be noticed
that there does not seem to be a distinct sinijle jKiint of origin,
but that the group seems to s[>ring from a sujall area. An int»-rest^
ing }>oint to which attention may be called is the fact that none
of the lines of crystals cross each other : this r.an be observed
in several instances in fig. 4 (Plate 3) where these lines approach
each other. Further, the extremity of each line, where the
crystallisation can proceed unhindered, is nearly always capped by
a complete crvstaL
Fig. 5 (Plate 3) is a more highly magnified (150 diameters)
portion of lig. 4, and for identiheation purposes similar portions
in figs. 4 and 5 have been lettered A, li, C, In this figure the
building up of the lines by successive deposits of crystals can be 1
more clearly seen. ^|
Fig, 6 (Plate 3) is a portion of another group altogether. Tb^B
magnification here is 700 diameters. It shows perhaps more
clearly not only the individual crystals which help to build up the
linea which compose the groupings previously meat ion etl, but the
complete form of the last crystal deposited at their extremities.
Attention may here l>e drawn to the mottled appearance which *
can he seen in fig. 4 (Plate 3) in those parts of the iens where
the crystals have not been formed. These markings, or ** giobules^"
as they are termed, evidently represent the stage previous to the
actual crystal formation, and must have covered the whf>le surface
of the lens before the crystals themselves were developed. As
crystallisation set in they disappeared in the neighbourhood of each
crystal, as if the crystals themselves required this material for their
formation. The existence and behaviour of these globules are well
known in crystallography, as I have since been informed by Professor
J, W. Jtidd, of the Royal College of Science, South Kensington The
whole phenomenon is clearly described and illustrated by Professor
O. Lehmann in his magnificent work entitled Flmnge Kri^alle
(Wtlhelm Engelmann, Leipsig, 1904). In this conuection Professor
Lehmann writes (p. 112), ** Das die Globuliten io der Nahe von
J&v. 1907. Permanencjf of some Pkoto-viaual lj«n»t.
85
Lristaljen verschwindeii, so dass um diuse ein Hot enstebt, erklart
lich vor alien dadurch» dass liberkiililte Schmelzen leichtt-r loalich
ijjd aU die kristallimech enstarrte 8ul>stanz, in einzelnen Fallen
ell durch Stroratmgen, welcbe teiis durch Dichte-DiflFereiizen,
(teiU, speziell bei Pmparateii ohne Deckglas, durcli die Oberflacheu-
(kaonang veranlasst werden."
Although the microphotographa reproduced with this paper
iidicate in a general way the structure and crystalline nature of
tie markings, some difficylty was met with in attempting to
satisfactory photographs with high powers, that ia^ with
nifications of 150 diameters or more.
The thickneis of the crystals and their deposition on a curved
Burfaee rendered it iinpoBsihle to focus the object's in their entirety
in a satisfactory manner, so that one bad to l;»e contented with
the fiomewhat blurred images when these magnifications were
employed.
In order to test whether the markings on the two surfaces of
the objective were responsible for any absorption of light passing
through the combination, the objective was set up on the V-ataud
atantioned previously and photographed. On this occasion the
round used was white instead of black, and light was only
to enter the lens by redections from thia surface. If the
arkings absorbed light, it was ex[)ected that the resulting photo-
Aph should give one the picture of the lens with the markings
irk instead of light, aa was shown in the previous illustrations
(Plates 1 and 2). This is exactly what occurred, and both sets of
narkings were faithfully recutdeil. Those on the back len», which
[jvered the larger ai'eji, were not, fortunately however, so opaque as
boae on the front lens, but still a considerable absorption of light
Iwaa indicated, a quantity qnite sufhcient to detract from the
trticiency of the combination.
Inquiry was next made into the probable causes of the deposi-
tion of the crystals^ The weathering of glass surfaces, on account
of the dust, water-vapour, etc. in our atmosphere, has received
:>ri8iderable attention in Germany, and quite a mass of literature
[now exists on the subject. A very convenient summary of such
ations will be found in Dr. H. Hovestadt's book on Je7iu
and its gcientific and iudindiud applu-ations^ an English
on of which appeared in 1902 (Mac mi 11a n & Co.).
In cliapter x, of this volume the chemical behaviour of glass
96 is dealt with, and attention is cliieHy confined to glasses
are most closely related to the work of the Jena glaas-
iting laboratory. Hince the |dioto-visnal lenses here diacusaed
u% made from material supplied from Jena, the information given
is therefore specially servictmble on the present occasion. There
•eema little doubt that it i^ c^hietly the moisture in the atmosphere,
and not dust particles, which is responsible for the actions which
oocoroD the surfaces of the lenses here described, for the surfaces
iitUcked are all inside, and although protected to a gieal eiX^iiV
Atom duBt, ihBy ^re still liable possibly to action by watei-^a.^VLt,
36
Dr, William J, S. Lockyer^ Note on the LXVni, I,
It has been shown tbat the darabilitj of glass depends chiefly on
its power of resisting attack by water. Glass being hygroscopic,
absorbs moisture to a varying degree, and this moiature enters into
cbemical combinatitm wilh its surface. As a re«u]t of thia
abaorption, the alkftline components of the glass are gradually set
free, and an opportunity is at once afforded for the carbonic acid of
tbe air to combine with the alkalies and form carbonates, which
are deposited in the form of crystals.
l)r. E. Zflcliimmer* made in 1901 an analysis of about 200
pieces of ghiss with polished plane surfaces, whicb bad been stored,
witli a view of subsequent testings in a dry place in Jena for
several years, but so protected that they were only imperfectly
excluded from air. He found that the behaviour of siiicatea
without lead depended almost entindy on tbe amount ol alki
contained in them. If the amount was as bmaii as 10 per cent.,
daat particles initiated a depoeit which he termed ** dusty dis-
integration'*; over 10 per cent., a '^liomogeneuus decomposition"
set in which attacked the glass uniformly. When the amount of
alkali reached 20 per cent, the deposit became visible to the naked
eye, and the greater the proportion of alkali, the coarser the pheno-
mena, t>. the formation of drops and the crystal! isati on of car-
bonates, The acticm of lieliquescent carbonate of potash is ta
cover the surface with more or less minute drops, while carbonata.
of soda, l>eing only slightly hygroscupic, covers it with assemblages
of cry 8 tab.
In the case of the lenses dealt with in this paper, the formation
of the single crystals took place on the baryta light flint glase,
while the assemblages of crystals occurred on the light silicate
crown.
In order to find out the actual compositi^m of tbe latter glass^
Messrs. Scliott and Genossen of Jena were communicated with, and
asked whetber ibey wouM be good engii^^b to supply this informa-
tion. Needless to say, the requisite data were soon forthcoming,
and I should like to take this opportunity of expressing to them
my best thanks for so willingly sending me tbe facts desired. Th©
following is an abstract of their rejdy, dated S2th April 1907,
which tbey have kiiidly allowed me ti) publish:—
** We beg to say that the glass in question of our type 0 574
constitutes a crown glass holding a high percentage of alkali, wo
had niatle at some previous time, of a similar composition as
French glass. Owing, however, to its being wanting in permanency,
we discontinued later on the manufacture, and hence this glass
does not appear on our present catalogue.
" Its chemical composition is the following : —
1
B,Og 3%, K,0 17%. Na^O 5%, CO 3
Jb,0, 0-4%. SiOj 69-8%,"
'i. PbO 1%.
With these facts before us^ one is led to conclude that the
* Cfumiker Ztitunq^ igoi, 2$, 'So. ^,
Nov. 1907. Pe/inaTiency of some Fhoio^mml Zensis.
2;
excess af the alkali baa acted Id the way suggested by Br. Zschimmer,
and produced the assemblages of crystals described above.
It may be here remarked that these aisseiiiblages of crystals are
very similar in growth to those formed by the cry stall igation of
potassiam permanganate, as descnbed and illustrated by Profesaor
Lehmannon page 124 of the volume on Flus^ige Krisiaile to which
reference has previously been made.
In order to try and reproduce the forms of cryBtaHisation
I deposited on the lenaes, a series of experiments was made with
partial Buccess.
As pmt&^itUD (17%) was the chief ingredient next to silicon
(69-8%) in the composition of the glass, solutions of pure potash
with distilled water were made and poured on to the cleaned
Burfaces of several cover-glass lantern plates, and then drained off.
The moistened sides were then covered with another cover-glass,
bot separated by means of small wootien diaphragms in order to
mllow a slight circulation of atr. The glasses were kept in an
upright position in a cupboard, which was frequently opened.
In a similar way, several other glasses with solutions of
potash and caustic soda, mixed in the proportion of 3 to i, were
also [prepared and treated in the same way.
After 10 or 15 days crystallisation in most cases began to set
in, and the plates were examined and occasionally photograiihed.
It was most interesting to observe, not only the different forms
f crystallisation on the various plates^ but also the different forms
on the same plate.
In the few attempts made, the form of crystallisation shown in
Plate 2, fig. I, wjis not exactly reproduced, although in some
instances a close approximation was reached.
In conclusion, it may be remarked that th^ deposit of cryat^ds
the several lenses to wliich reference has here been made has
in no instance been removed at the observatory. The objectives
were always sent away to be cleaned, and the method of getting rid
of the deposit was to rub the surfaces with material boaked in
dilote aaJphuric acid. It is, however, satisfactory to know that
Measrs. Schott and Genossen no longer manufacture the particular
kind of glass which has caused this trouble, and have erai?ed it from
their catalogues. The more recently made photo-visual lenses
ihotild not» therefore, in future be hampered with this defect.
Before submitting this paper to the Society, I sent it to Mr.
H. Dennis Taylor, whose investigations on the theory and practice
of photo-Tisnal lenses are bo well known. He has kindly %VTitten
an "Addendum," which is here attached, and which will be found
& valuable contribution to the subject of the present paper»
28
/
Dt, William J. S, Zockyer, Note on the LXVlll. i ,
Addendum by H. Dennis Taylor,
Notes on Dr, Wra. Lockyer*s paper on the FermaTiency of bowb
Ffhoto-cisucd Lenses.
Dr Lockyer kindly eubmitted to me hia paper before [lublicatiou,
with a view to my adding any remarks of my own on this infcerest-
iog question.
In the firet place, I would like to point out that the dates of
mountinjT the iustmnient given by Dr, Lockyer are not the dates
on which the objectives were put together, so that, correctly, at
least 12 montha should be added to the periods given, on the
average.
Dr. Lockyer says that he had not been able to notice any
deterioration of the optical performance of any of these objectives
after being cleaned up, but that no apecial test^ were eiu ployed. ^|
But after cleaning at Me.ssrs, T. Cooke & Sons* works^ th#H
objectives were earefnlly examined and tested for optical deteriora-
tion and none whatever was noticed. One would have thoiight
that the crystallising out of some of the alkaline constituents of the
glsBS would hfive leift a network of channels in the glass surfaces,
and for the presence of such small inequalities, tests by reflected light
should be more af>propriatej bnt we could not see anything. Of
course, it is quite ijoasible that the repetition over many years i»f
such crystallisation, supposing it does repeat itself, might deteriorate
the surfaces of the lenses sntliciently to c^use optical mischief, but
so far it has not been apparent.
With regard to the small bundles <>f glistening crystals forming
upon the inner surface of the front lens of baryta Hght flint, and
shown in hg. 2, Plate 2, and figs, i, 2, and 3, Plate 3* I would
tike to observe that these never seem to be at all fast to the
surfaces, and can always either bt: blown off or brushed off
with a delicate camel dial r brush ; and after so brushing them off,
the surfaces are just as clean as before, eicepting for a little dust
that may have found its way in.
As regards the much more noticeable crystallisation on the
inner surface of the back lens, I have never had any difficulty in
rubbing it off with a soft rag dipped tn very weak sulphuric acid,
%vhich, after thorough washing off, leaves the surface just like new*
The amount of this crystallisation is largely dependent on the
dampness or dryness of the situation in which the objective is used,
and it would most probably never form at all could we keep the
objective always in a dry atmosphere. Moreover, it depends also
npon the particular tyjje of crown glass used. I must here point
out that the crown glass with a larger amount of alkali than usual,
referred to by Br« Lockyer as O 374, was employed in the i24n.
aperture, 3I aperture, and one of the two 34n. aperture O* G/s,
while the other two, of 4-1 n. aperture, were made out of a boro-
silicate crown glass, type O 599, ot 'ti^'ax%. Bdiott's catalogue,
Monthly Notices of RAS.
VoLrLXVIH Plati
Monthly Notices o^ R A.S.
Vol. LKVin. Plate 2
k
Ttt f(tc0 pa^e 39.
Monthly Notices of R.A.S.
Vol. LXVllL Plat
fov» 1907. Ptrmanency o/Bom^ Photo-visual Letises, 39
rhicli latter glass is no more likely to develop hjgroscopic crystal-
tban is the ordinary crown glass used for older type double
4ve.
Te ha^e occasionally had cases, however, where ordinary
able objectives that have been used in dam[> climate& have
1 the same crystallisation on the ioterior surface of the
iDiit^edf )n damp tropical climates such os that 0! Calcutta the
rstnlhBation which so frequently develops on the interior surfaces
iiy crown glass lenses is found, if left t*>o long a time
viping ofi* to leave an actual corrosion of the surface in
form of a fine grey veil. Tlie appearance is just like that
by an imperfectly polished surface, in which the fine pittings
by the last emeries still survive.
lessrs, Cooke & Sons do not now employ the crown glass
574, ;is it wants cleaning more often than is desirable, and use
silicate crown of ty}>e O 599, or else a variety of it recently
luied by Messrs. Schott. As regards freedom from
Liy -]t?rtrum, it is difficult to detect any difference between
livfca liiide of these two difiercrit crow^n glasses.
DESCRIPTION OF PLATES.
Platb I.
fig!, t had 2, PhotO|^raphs of two 3-111. lensea after S3 moDthii* n^ in
il»b0f«lory spfctroscoiw. Fig, r, colli mating lens ; fig. 2» cameru kna,
Platk 2.
Fig. I. Photoigruph of 5'5-in. Icna after 40 moDths^ use as a fisder to a
[-ft f«rtactor.
Fig. 2 t^ a reproit action of a photngrapii of the «ame lena^ but taken so as
■b>7w the niarkiijgB (white dota n^ar centre) on another aurface of the
Pt.ATE 3.
Fi^« I, 2* and 3. Enlarged vicwa (700 diameters) of »ome of the white
"i»g)i illustrated in Plate 2, fi^;, 2,
_ Wig^ 4v S, and 6. Enlarged views (45, 150, 700 diameters respectively) of
fen« Qf one of the groups of crystal* shown uu Plate 2, fig. i.
30 Dr. Max Wolf, The Nebula E IV 74 Cephei. LXvm, i,
Tiie Nebula H IV 14 Gephei. By Dr. Max Wolf. (Plate 4,)
I have pointed out elsewhere that, as a rule, the nebulse in th
Milky Way are encircled l*y a ring which is void of faint stars,
and that this lacuna is the end of a long starless hole, apparently
abowing the direction of some unknown cosmic motion, I have
given a number of examples of this,* the best specimen being the
nebula 2 degrees south of ir^ Cygni.
On photographing the Nebuk H IV 74 Cephei (=N.G,
7023 : a=2i^ o^ 30' S^ +67"* 46''2 (iqoo'o)) with the 284g
reflector ol the Kimigstuhl Aetrophysical Observatory, I
surprised to find a striking epecimen of this phenomenon, thi
nebula being surrounded by a lacuna absolutely empty of faint
stars. In spite of the small field of the reflector-plate, there w««
evidence that the cavity was the end of a channel entering the
picture almost exactly from the south.
This nebula was pbotoj^raphed by the late Dr» Eoberta (yoL
plate 24). He says: ** The nebula appears in a region almost voi
of stars "(p. 157).
I then endeavoured to photograph the channel with the larj
field of my i6-iiich camt-ras. But the weather was very ua-
fdvourable durinjyj this sprinj^ and summer, and the sky always so
hazy, that three nights were lost in these attempts. The last of
these trials, on July 7 (exposure 3 hours 22 minutes), gave
relatively the best picture, a reproduction of which is given on
Plate 4, fig, I. The scale is about 70 mm.f for i degree. As may
be seen, the channel is directed in its first part almost exactly from
south to north. At a distance of about i degree from the centre
of the nebula the channel is divided into two branches. The
eastern branch is perhaps shorter, and the western longer, ending
at a distance of about i| degreea from the nebulti by becomi
gradually filled up with stars. The somewhat round cavi
encircling the nebula has a «iiameter of about half a degree.
We have therefore a further example of the rule that a nebula
is encircled by a lacuna void of stars, which lacuna is the end of
an empty channel.
The nebula itself it* a very remarkable object. In man^
respects it resembles in form the ^ Cygui nebula. On the oth
Land, the faint bands of nebulosity parallel with the brighter
hands are very much like those in the Orion nebula. This
parallelism gives an indication of some kind of wave formation
in the nebulous material. These are especially visible at the
north-west side, three parallel waves, each nearly half the bright-
ness of the inner preceding wave. I am especially struck by the
gradual fading of the light of the nebulous matter from the centre,
produciug the Impression that nebulous matter is spread all oTer
• Astron, Nachr., 3848 ; M.N,, KA.S., Iziv., No. 9 ; Public. Astrophjfi,
Imt, K&nigMtuhl, ffeidelberg, vols. i. aud li., etc.
f In the rBprod ncihn 48 mm, = l*.
ne
i
la
of
MoHTHLY Notices of R.A.S.
Vol, LXVIII Plate i
I
lov. 1907. Mr. Walter Heath, OccuHation of the Hyades. 3 1
the lacuna, but has id sufficient Itimii^osity to be visible, I do not
know any nebula in the sky wbit-h ehows this more clearly.
I al*;o give a somewhat enlarged reprodijctiop of a jiicture of
the nebula itself, taken with the iS-inch reflector {Plate 4, fig. 2).
The photograph wa« taken April 18, I907, with an exposure ui
40 minutes. The scale on the reproduction ia about i Turn, to
2 1 seconds of arc*
I may perhaps meation two peculiarities common to this nebula,
In the T^ Cygiii nebula, and to perhapt* all other similarly sur*
roQUfied by lacunit^ P'irst ; the long channels are all nearly
straight and clean in the vicinity of the nebula, and becume carved
and partly filled up with stars at a greater distance from it.
Secondly : the channel is simple at the end nearest the nebula,
and divided into two or three complicated arms at the end further
removed.
* h\ the reproduction i in id. = about 30" '6,
BMtXbtfrg^ Astrophyaical Observatory :
1907 July 27.
OccuUniion of the Hyade$. By Walter Heath, M,A,
^1 £M
^P In order to determine the longitude of my observatory I have
^^reeently compared twenty three occultation observations made by
me with the corresponding Greenwich observations, and 1 find a
di^kcordance in the case of the reappearance of two atars of the
Hyadea on 19th iSeptember 1905. I have therefore compared the
resiilta with same observations publii^ih^jd in A.N,, 4088 ; the
following are the particulars. The results in brackets are derived
from observations at the bright limb.
1905 Sept
18
Utrecht
/Tauri
'95Aft+'4iA5=(ro"2o)
,.
ft
u
M
•99 », +-27m = 8*44
f»
**
Jfillft
«1
95 n +'39.. = 8-26
M
'9
1*
7 Taqri
'42m ^-'95.. = (S7S>
f*
»♦
*.
M
■84 r, -'57*. = 3'97
M
»
Grtenwich
«i riiuri
•94». -'-■37^. = 171
1
.,
D.M, 15",
633
•94. » --35.* = 1*36
1
Cobliam
<», Tftun
•94,1 ^-'38,. = 5'i2
f J
,,
.♦
D.M. IS"
633
95 n - '35 ,. ^ 6*22
Nok.-^foT Coblitm tlie longitude assmned was 23' 6" W., latitude
T'l^* 39*» height above sea 180 feut. The sidKrfjal times observed were
4* 27m 22»'49 and 4*" 45*° 2**02 after oorreotion.
Vptamd§, Cobh^m, Surrei/:
1907 Qeiob$r 18*
32
Disappmranee of Satum^s Rin^ Sy8it7iu Lxviu. t.
Duappearanee of Satiirn*8 Ring Syatemj 1907 Ocfobef\
' Bj R. T. A. Innes,
Thanks to tbe assistance of Sir David Gill and the Witwatersrand
Coijncil of Education {Mr. Th, Reuneit, chairman), I have \vithin
the \&&t few days erectiid a gin. refractor by Grubh.
The disappearance of Saturn's rings was watched with this
instrument on the 3rd October 1907. An exact copy of the notes
made reads as follows :
1907 Oct. J, 6.45 p.m. twiliL^ht (4.45 p.m. G.M,T,)* Saturn's
ring distinctly seen by myself and several visitors. It was very
fftittt and only seemed to be about half of its usual length. Detini-
tioD medium, planet low.
8.45 pjii. (6.45 p.m. G.M,T.). The ring is invisible. The
bright equatorial band was crossed by a sharp dark litie wliich
just lay to tbe N. of Saturn's equator. This tlark line had been
seen on precepting nights, but on this occasion it seemed to be
sharper and darker. Two satellites, about 2* or j" apart, followed
Saturn.
9.30 p.m. (G.M.T. 7,5a p.m.). Ring distinctly seen, but like
a gho6t, Care taken to eliminate subjective efiects. Definition
very good.
10 p.m. (8.0 G.M.T) Ring still glimpsed. Preceding part
of ring nioditit^d by two beads, one twice as large a« the other
(Eoceladus and Mimas). My son's description is **King visible
on both aides, extending about tbr^^ivquttrttTB diameter of p^lanet.
Nearer and brighter satellite is half way along ring and touches the
northern suie. Fainter satellite prec*"des end of ring." — (E. A. L)
U.45 p.m. (9*45 G.M.T.), Quite doubtful if ring really se«*n.
Mimas and Enceladus very clu«e lo;^ether. My son, however, wa
quite certain that he held the ring steadily. His words are ** Rio
very faint, but ended uff sharply. Fainter satellite is preceding. "^
(E. A* L) Detinition perfect.
12.30 p.m* (10.30 G.M.T.). No suspicion of ring; only on«
eateUite seen prec. ** Ring not seen with any certainty* The fir«t
of the satellites following Satum getting too close. "^ — (K A. 1.)
Definition very good.
Thus at 3 Oct. 1907
4.45 G.M,T.
7 3^ ,*
8.0 ,,
9-45
10.30
Ring quite easy.
Ring diflictilt but distinct
Ring still seen.
Ring still glim|»sed.
Ring invieiible.
So that, as seen in a 9-1 n. refractor nnder circumstances of good
definition, the ring system became invisible soon after 9.45 and
before 10*30 G.M.T. As the ring vvas easy to see at 4,45, and got
difficult as quickly, the Earth must have pasa«d through its plane
soon after invisibility.
Nov, 1907, OhB^rcations of the SatdlUe 0/ Neptune,
33
Oboerviitions during the period that the dark sides of tbe rings
Are expOfied to the Earth answer the question as to whether the
lings are composed of solid particles or of vaporous matter. If
the Utter, the edges at (eaat of the rings would be i^een.
Johannesburg^
1907 (iktobrr 5.
ObiiCTvattirTu^ of ths Sat ell tie of Neptune, from pkotofjraphs tafcen at
tli^ Royal OhservatOTt/^ Greenwich^ between 1906 Dfcember 27
and 1907 April 24.
[CttrnmnnicaUd hy the AUiwyomet M»^,}
The following measures of position-angle and distance of
Neptune's satellite were made from photographs taken with the
26'in, refractor of the Thompsoii equatorial* The occulting
abutter was used as in previous years. The photographs were
taken by Messrs. Davidson, Ediiey, or Melotte, and were measured
in a position micrometer in direct and reversed position by MessrM.
Davidson and Melotte. The tabular poBitiona with which com-
piarison ia made were computed from the data given in the Con-
naisMnee des Temps^ based on Dr. Hermann Struve's elements,
Ihe eccentricity of the orbit being neglected.
A discussion of these residuals gives the following differences
hxmi Dr. Hermann 8truve*s elements in the sense Tabular -
ObeertrKl:
du= - i'*03 dN^ -o"'98 r7I= ^o°'i8 da=^ - "'ooS
giTing for ih«j epoch 1907 2
a=i6'''279 N = 188''68 I=ji6"-69.
Neptum anrf Satellite,
fMUfM^imgU and DMunce^ftom pfiotof^raphs taktn with ike 2^in, Eefractor,
Ottto jmd Q.<.
DiiteQoe.
1906,
d
ec. 27
h m 6
lo 57 45
Ob«.
305^13
Tub.
30507
T-0.
-0*06
Obe.
"4^53
1472
T-o:
+0*19
1907.
m, 17
«o M 43
105-43
io6'ii
+ 0-68
16^44
16-47
+0-03
17
10 42 ft
104 '02
105-30
+ 1-23
i6'54
i6'52
-0*02
17
It 7 30
102 '39
104'57
+ 2*18
167s
i6"57
-o'i8
30
ID 30 31
44*20
45 "99
+ 179
f2-69
12'So
+ o*it
30
to 56 6
43'iiJ
4476
+ 1-58
l2'6o
12*70
+ 010
P
If 22 51 {a)
43^40
4r43
+ 0*03
12*84
12-59
-0-2S
34
Observations of the Satellite of Neptune. LXVIIL i,
Pimtion-angle and DiJtonce— eontinned.
Podtioii-uigle.
Dittuioe.
D«te
and G.M.T.
h m 8
12 46 . 8
1907.
d
Feb. I
ObB.
269-00
Tab.
269-10
T-0.
+ 0*^10
ObB.
16^^82
Tab.
1673
T-O.
-0-09
7
10 34 23 (d)
26696
267-77
+0-8I
16-53
16-65
+ 0-I2
21
II 2 29
"5-59
117-16
+ 1-57
15-71
15-30
-0-4I
28
823 33
7027
7294
+2-67
15-39
15-42
+ 0-03
28
8 54 19
7173
71-93
-f-0*20
15-53
15-32
-0-2I
28
9 29 47 (0
69-48
7075
+ 1*27
14*96
15-20
+ 0-24
Mar. I
9 4041
356-64
357-01
+0-37
10-92
10-99
+ 0-07
I
10 3 48
35477
355*52
+0-75
1073
11*01
+ 0-28
I
10 25 37
352-86
35413
+ 1*27
10-98
11*04
+ 0-06
I
10 44 18
352-63
352-94
«fo-3i
11*10
11-06
-0-04
23
9 fi 19 W
9373
93-30
-0-43
16-09
16-43
+ 0-34
23
9 36 54 (a)
9143
92-44
+ 1*01
16*68
16-42
-0-26
23
10 6 38(a)
90-23
91*61
+ 1-38
1640
16-42
+ 0"02
25
9 26 39(flr)
316*61
318-15
+ 1-54
12*88
ia-79
-0-09
27
9 I 44
2i8-o8
218-66
+0*58
12*01
11*97
-0*04
27
925 8
216-54
21743
+ 0-89
12-10
11*89
-0-2I
27
9 56 16
214-39
21576
+ 1-37
II -81
11*95
+ 0-I4
27
10 23 35(«)
214-27
214*26
-0*OI
1 1 74
11-69
-005
28
85837
133-22
135-42
+ 2*20
1311
13-02
-0*09
28
9 33 48(7)
134-36
13388
-0*48
13-01
13-16
+ 0*15
Apr. 6
9 5047
30144
302*67
+ 123
14-24
14*25
+ 0-0I
24
9 32 40
283-83
28605
+ 2*22
15-51
15-69
+ 0*18
(a) Satellite faint and diffused.
lb) Satellite very taint and diflused.
(c) Photographic speck on Satellite.
(d) Very mint.
{c) Satellite diif used
(/) ^ery diffused. On fringe of secondary spectrum.
Hoyul Observatory f Oreenwich :
1907 November 7.
uv, 1907- Obt«rvations of Minor Planets.
35
vatiom of Minor Planets^ from photograplis taken mih tlis
30'i*«. RejieHor of tfte Thompson Equatorial at the Royal
Oh^ervatory^ Grtenunek^ during ike year 1906,
{OimniunicaUd by the Aatr^nomer RoffaJ,)
Tb© following positioDS of minor planota were obtained from
L»tographs taken with the jo-in. reflector during the year
The plates were measured with the astrographic micrameter.
reference stars were, aa a rule, measured with the planet, their
Bitions being derived when possible from the Catalogues of tlid
lironomiscbe Gesellschatt, or from the Radclitfe Catalogue, 1890.
The po«itiona given are not corrected for Parallax,
Log Parallax Correction = log Parallax Factor— log A.
Date wd aU.T..
tg»6.
d h in H
App»rcirt B.A,
b m «
Appftreut Dec.
LoK Parallax Factor.
EA. I>flc.
1
(324) Bui
wberga.
pr. 14 IX I 14
12 39 36 '97
-17 13 A&'l
-8*223
+ 0-912
19 It 39 H
12 35 28*10
16 51 3-6
^S-943
0-909
H 10 33 53
12 30 54 16
16 22 5o'6
4-S-397
0*910
26 10 53 3
12 30 10-98
i6 tS 47
+ S-500
0909
{278) Paulina.
tpr. 25 10 13 s8
13 29 30*55
- 1 0 7^1
-9*004
+ 0'g42
36 11 24 4$
13 28 39'43
0 59 32^3
+ 8*283
0842
, 27 10 JO 3S
«3 27 51*53
0 59 S*2
-S770
0-S42
(191) Kolgft.
*pf. iS n 08 T4 21 35*91 + o 27 lo'i -8*955 ^-o**^33
(146) Lticioik
M' 28 u 42 9 14 22 38*29 + 3 16 50*5 -8*408 +0'8i5
(443) Photographic*.
% 24 10 31 24 14 29 S'52 - 8 17 i8*3 +8162 +0*879
Ji 10 9 23 14 24 55* 15 7 58 8*0 +8*463 0878
(65) Cybele.
' 24 tl t6 15 14 45 18*23 - II o 58*8 +8778 +0*890
31 to 37 31 14 41 19*64
10 45 10*0 +8*687
.%
^ M 5' 33
(148) Gallia.
fj / 27'jp/ i-iS 46 528
0*889
+ 8*971 +0*67^
36
Observations of Minor Planets from LXVIIL i.
DitouidO.M.T
1906.
d h m
■
Apparant B.A. Apparent Dae.
Log Flumliaz Factor.
K.A. Dec.
(504) Cora.
M.y 31
II 16
57
15 35 50*38 - 4 25 21 X)
(92) Undine.
+8-381
+0-86I
May 31
II 49
17
15 46 36-07 - 9 52 12-8
(487) Valletta.
+ 8776
+ 0-885
June 26
II 0
51
17 29 23-80 15 39 33-1
(374) Rur^ndia.
-8-299
+ 0907
June 22
26
II 47 58
" 33 56
18 3 21-22 -II 55 20-9
17 59 52*17 II 47 156
-8-359
-8-167
+0-894
0894
(409) As|»asia.
June 22
22
25
25
26
12 18
12 51
II 0
11 28
12 I
7
59
28
31
21
18 35 22-41 - 12 42 26-5
18 35 21 17 12 42 18-9
18 32 34*52 12 30 22-0
18 32 33*44 12 30 i8-i
18 31 34*61 12 26 19-1
(28) Bellona.
-8360
+ 8-515
-9*103
-8-918
-8-294
+ 0-897
0-897
0S93
0895
0898
Jane 22
22
25
25
26
12 18
12 51
II 6
11 28
12 I
7
59
2
31
21
18 33 loio - 12 44 233
18 33 896 12 44 23-9
18 30 37*38 12 50 4-3
18 30 36-50 12 50 5-5
18 29 43-15 12 52 13-3
-8-418
+ 8-469
-9*065
-8-901
-8-360
+0-897
0-897
0-S95
0896
0-896
June 26 12 33 45
June 26 13 26 8
July 28 12 27 29
31 12 44 57
Aug. 14 II 52 22
21 10 50 II
12 JO 2$ 22
(122) Oerda.
18 34 2904 -20 52 29-8
(51) Nemausa.
18 47 10-66 - 6 16 13-3
(7) Iris.
20 33 18-57 -II 26 56-1
20 30 10-29 II 31 25-5
(378) Holmia.
20 34 43*o6 - 7 18 36-7
7 45 2*2
7 48 55*8
20 29 29-86
20 28 49-23
+ 8*437 +0-922
+ 8-950 +0-869
+ 8-442 +0*892
+ 8-908 0-891
+ 8-885 +0-874
+ 8-462 0-877
-7-509 0-877
■1
■
n
^M
Nov. 1907. Photog^^apJu taken at Greenwich,
1906.
n H
1906.
d li m f
AppATcnt R.A. Apftorent Dec.
h m B if
(434) HuiigariA*
^1
July 25
13 3 36
21 31
I9'97 +173048*3
-8-428
+0689 ^1
Aug. 7
" 57 33
21 22
6-04 14 37 43*9
-8-839
^H
H
12 55 0
21 16
23*60 12 20 247
+ 9-033
0746 ^
15
12 56 5
21 15 35-25 11 58 45 -8
4-9*080
0750 1
21
II 9 14
21 [I
0-89 9 41 8'5
(480) HanBft.
-7-812
0766 ^1
Aug, 14
12 24 42
21 14
576 +J8 43 19*0
+ 8-838
^1
^S
12 34 9
21 13
13-47 is 40 177
+ 8'963
0^680 ^1
21
11 44 56
21 8
979 18 16 2o'i
+ 8756
0-682 ^
22
10 46 34
21 7
22-50 18 It 33*0
-8-526
0-681 ^J
Sept, 7
9 18 9
20 56
11*42 16 20 30-8
(136) Austria.
-8751
^1
Aiig. IS
13 *2 59
21 50 47 '37 - 0 25 40-9
+ 8*947
+0-838 1
2t
12 z 51
21 45
54 '03 I 21 5ri
+ 8-349
0-844 1
31
M 24 4S
21 45
6*31 t 31 37*3
(386) Siegena.
-S*4«2
o'845 ^J
Aug. 7
11 SI 38
22 I
iS*45 + 0 57 40-8
- 9*023
+0-841 ^H
14
«3 39 13
ti 56
44'93 - 0 14 O'o
+ 9-059
H
»5
13 32 2
21 56
4'35 - 0 24 54*9
+ 9-042
^1
2]
12 31 41
21 51
5619 - 1 33 5»*5
+ 8-770
H
22
12 6 4
21 51
14*90 - I 45 44^3
(308) Poljxo,
+ 8*407
0-846 ^
Aug. 22
12 27 8
22 7
8-88 - 7 39 407
+ 8-549
+0-876 ^^k
2S
11 39 3^
22 2
25-18 8 IS 29*6
(42) Isia,
+ 7*509
H
AQg. 28
14 46 31
23 44
I "69 -20 22 56-9
(26) Proserpinm.
+ 9'i6S
^1
Amg. 29
14 0 16
23 25 51-28 - 9 7 47*0
+ 9-010
+0-881 ^H
(478) Terjceatfl,
H
Stpt II
10 7 45
23 3
2ro6 4-12 44 57*6
-9-184
+0746
2S
11 40 33
22 53 3571 u JO 17*6
+ 9006
0756
26
11 39 i2
22 52 58-04 It 2 52*4
+ 9*025
0757
«7
II 21 1
22 52
21-54 «o 55 297
+ 8-924
0-7S7
Oct. 10
10 2^ 36
22 4S 43'SS 9 16 l6n
+ S-953
on I
38
Observations of Minor Planets.
LXVIU. I,
Date and G.H.T.
J906;
d b m ■
Apparent B.A. Apparent Dec.
b m ■ • . «
Log Parallax Factor.
R.A. Dec.
(108) Hecaba.
Sept. 26
12 16 15
0 29 18-35 + 4 50 59*4
+ 7-983
+ 0-804
27
II 46 27
0 28 35-36 4 47 22-2
-8-483
0-804
Oct 16
12 0 41
0 15 *'30 3 36 I9'3
(47) AgUia.
+ 9-119
0-816
Sept 26
27
12 42 44
12 6 35
0 58 33*13 + 7 21 2C
0 57 44-66 7 18 25
299
0-786
Oct 16
12 19 46
0 41 33'92 6 i6 6
+ 9-084
0796
23
10 20 58
03617-53 5 54 4I-&
(175) Andromaohe.
-8-206
0796
Sept .26
13 22 52
I 18 13-42 + 7 14 39*6
+ 8-586
+ 0-786
27
12 21 8
I 17 32-63 7 II 39-4
-8-724
0787
Oct. 23
10 41 27
0 57 44-73 5 42 55-6'
(153) Hilda.
-8-247
0797
Oct 16
12 52 59
I 19 45-76 +13 15 40-6
+9-065
+ O73S
23
II 48 14
I 15 32-48 12 40 20-3
(5CX)) Selinur.
+ 8-803
0740
Dec. 6
10 38 13
5 14 52-34 +31 53 24-5
-9-240
+ 0-500
1907.
Jan. 2
8 51 22
4 47 56-08 29 14 39*5
(19) For tuna.
-9-107
0-535
1906.
Dec 14
II 24 9
5 41 7-53 +21 6 39-2
-8-894
+0-649
Royal OhservcUary, Oreenmkh :
1907 November 8.
Nov. 1907, AHeromeiir Metimres 0/ Ihuble Stars,
39
BsmdiB of Micrometer Mmmres of Double Stars mcuh with the
2S-inch Refractor at the Royal Ohiterratort/, Greenwich, in the
year 1906.
{Cofnmunimted by th4 Astrotimner Itayal.)
The measured were made with a bifitar position micrometer on
the 28-inch refractor, focal length 28 feet. The power generally
em^plojed wa« 6'j(^, When bright stars were observed a blue glass
U -^^ . ^ - pmnloved to cUmiuieh the light and irradiation.
? made in variouslj colimred fi^dds or in a
dATlc fieiu -jjated wires. The itiitiak in the last column
are those of the *^ vers, vii, t^
L. Mr. lie wis
W. B. Mr. Bowyer
B. Mr. Bryant
H. F, !klr. Furner
The main portion of the meaRures ate of pafra discovered by
Hough, which usually consist of a bright star with a faint com-
panion* The remaining measures are of stars selected from the.
catalogues of W. dtruve, Otto Struve, Burnham, Hussey, and
Aitken.
In general the present list of measures is confined to stars of
which the separation i« under 4" or which show orbital motion.
The following stars, which are not included in the list of
■ureSf have also been observed.
Bmtgh Start.
20
it6
J23
387
446 AC
501
573
26
117
3^7
394
448
519
576 AC
2$
'3'
337 AB
400
452 AB
523
586
39
204
337 AO
406 AB
452 AC
534
597
30
236
343
406 AC
460
539
603
3t
240
347
412
465
543
604
3^
259
348
416
473
548
606
3«
269
349
423
475 AC
550
611
39
2St
362 AB
42s
476
551
613
45
297
362 AC
426
477
552
615
64
302
365
433
478
553
616
91
105 AB
37«
434
486
557
617
»"S
30s AC
377
440
Struifc Stars,
4S7
570
9n
«934
2185 AB
2476 AC 2690 AB
zSiBB.
f»^
1965
2/Ss AC
^SSs AC
2690 AD
aSM
1
^^^^H
^^^^1
g
1
1
■
C
z
40 Micrometer Measures qf D&iiUe Stars made at
4
Lxvm. I, 1
Micrometric (Jhservations of Double
Stfirs at the
J
RotjaJ Ohserraiory^ Gr^enmch.
■
m*r't Fame.
R.A
PoiltlOD
Dl.t. of ^^'
Bpodi
1906.
■-m
b m
* .
.
*
^1093
0 16
79 3J
73"t
0*29
I
7'3 8*2
•882
B.
5 779
0 23
66 55
257*1
078
1
8'S 90
•882
B.
Ho 212
0 3'
94 5
244*4
0*24
1
6*0 d-o
•882
B,
Hu 411
0 33
67 so
^793
0*67
3
8*5 8-5
•884
W.B.
Ho 306
043
64 56
1^5*3
1^21
3
8*5 8*8
8S4
W. B.
273
0 50
66 52
281
o*97
3
6*2 6*8
*86o
B.
27-9
0*99
3
...
*879
W.B,
Ho 307
0 52
58 17
88-8
3-01
t
9*5 97
-928
W. B.
2 113
' 15
91 0
357^5
r56
1
6*2 7 "2
•S82
B.
Ho 310
I 2t
61 55
359*0
1*52
2
9*0 90
'882
W. B.
Ho 9
I 24
6845
972
3 12
2
9*0 11*0
•909
' 2138
I 31
82 50
387
r62
2
7*3 73
904
5 185 AB
I 50
61 39
359*1
036
2
75 8-2
•904
a
AO
...
162*9
5*19
2
7*5 87
*904
B.
21S6
I 51
8S37
36-8
0*68
t
7-2 7-2
*8S2
B.
Ho 12
J 57
55 46
97*2
375
I
8*0 107
•068
H. F.
H031S
2 34
9> S8
3597
^'3^
2
8-0 8*2
'454
B,
2305
2 42
7f I
315-0
y5<>
2
7*3 8-2
»9oi
W. B.
W. B^
...
...
3H"4
2*88
f
•925
Ho 317
2 52
73 7
304-5
3*36
2
8*1 II'O
•456
Ho 318
2 S4
73 19
27-6
3*22
2
9*1 9*1
•454
B.
2367
3 9
8937
209-0
0-49
I
8*0 8-0
-882
B.
Ho 320
3 16
89 9
169*2
2*08
1
S-o lo's
*025
B.
AilkeE 979
3 20
59 35
274-0
1*45
I
9*2 10*0
*89o
W. B.
Ho 14
328
62 I
20 ro
1*88
f
8*2 87
*ot9
L.
Ho 324
3 44
75 18
162-8
0*68
I
8*1 8-3
•019
^m
3 1232
4 4
61 3
4*5
0*48
I
8 '4 9*3
-019
'-^
Ho 328
4 12
70 33
2451
0*47
1
70 7'o
•068
H. F. 1
Ho 15
4 19
60 5
323-4
0*79
2
8-0 8*0
•041
W, B^J
Hu 304
4 19
80 44
389
0*31
I
5*9 59
*025
4
Ho 332
438
69 31
1271
1-32
1
9-0 9-0
*02S
B.H
Ho 333
438
69 55
i6o-8
2*55
1
9*2 9*3
025
B.*
Ho 17
4 54
59 7
56-2
4*11
2
8*0 10*0
*o65
W. B.
Ho 223
4 54
5833
223*1
2-n
I
77 10*5
*022
W. R
Ho 224 AB
4 59
61 34
297-2
1*46
2
9*0 107
•137
H.F.
^^ Ho 334
5 12
67 16
1S37
2*12
2
8*1 10*2
-055
w. a
^^^^^" X7^ ««r
5 17
■
77 25
itS'S
0*51
2
■
8-0 8*1
•100
w. a
^n
Nov, 1907,
the Boyal OUtrvcUory, Greenwich, m
1906.
H
sur t Hmm,
1910.
K,p.a
1910.
PoiltlOQ
AiUCle.
0Ut, of ^^'
Epocb
1906.
^H
M0Z26 IlB
h 01
5 21
62 28
239*0
o'62
70 7-0
•074
^M
z
...
27y6
23^57
7*0 io*5
-0S7
^M
Hi. 355
5 »7
63 17
1141
3^9
9*0 10 "5
*o86
^M
2749
5 3>
63 6
169-3
o*8i
7-0 7-1
-255
^H
HtiS25
5 34
54 3
339'5
0-30
7-8 8-0
•255
^1
Ho 510
S 39
56 19
241-2
1-31
9-0 9'2
'255
^1
HujS
5 40
67 S
i3S'o
077
8-6 8-8
•255
^1
Hn39
5 4^
68 10
^5-5
0*43
8-4 8-5
255
^1
Hu40
546
69 53
8'o
3-29
8-5 9*5
•255
^1
Ho2x$
6 t
77 30
270*2
2-38
8*0 11*0
•064
^M
Ho 22
6 S
79 43
198*1
0-72
8-0 S-o
-140
^H
Ho 230
614
76 11
60 '0
1-89
8-3 10-5
-085
^1
Ho 232
6 17
75 '7
3565
2*58
9*5 i*^
'068
^M
Ho 233
6 iS
7326
3S-3
2-24
8-2 11 -0
•041
^H
Hn 702
6 19
55 33
318-3
o*93
8-5 9-0
'273
^M
02 141
62s
72 2
1396
2-12
7*9 9*6
"130
^M
2945
634
48 54
269-9
075
7-1 8-0
•255
^1
3t3"7
6 36
80 10
94-2
0-66
S'9 9'4
•019
^1
2 3ii»
637
80 5
1743
2-97
9-0 9-5
Xiiq
^H
Ho 23ii
641
71 41
iSa^
0-49
^•3 8*3
■155
^1
} 02 156
642
71 42
298-1
0*56
6-5 70
ISO
^H
Ho 239
64s
75 12
139^9
0-59
8-3 8-3
^145
^H
Ho 27
6 50
69 47
1257
3'27
9*0 9-0
*041
^M
Ho 342
6 5S
7646
84*9
1-02
8-0 8-8
•141
^H
8051S
7 5
S9 29
143*6
2-97
8-0 ro'o
-141
^M
2 f 037 AB
7 7
62 37
297*9
0*60
7*1 7*1
•192
^H
AC
111-5
17-24
7*J i2-o
-192
^H
Ho 33
7 J5
67 40
3245
269
9-0 12-0
099
^M
Hoa43
7 17
60 34
i66'4
2 29
9*3 95
'164
^^
Ho 345 AB
7 »7
67 45
2840
116
9-0 lo-o
236
^M
Ho 346
7 21
71 40
60*2
13*18
7-0 n-S
■221
^M
So 34
7 26
6iJ44
lO'S
2-45
9*5 9"5
-078
^H
Ho 707
7 29
68 It
27*2
223
2
8-6 12-0 -221
^M
Uil 457
7 35
6633
M3'6
2-30
8'5 12-3
-192
^M
Ho 247
7 41
6839
106-9
0-54
7*5 8*0
-140
^M
Ho 36
7 42
64 19
123-1
065
2
8-5 8-5
-267
^M
Ho 250
7 5*
6847
168-3
0-52
2
7-0 9'o
24S
^M
18 ;Si 4?AC
2
J 7 59
77 2$
igr^
446
2
m
8'0 ii-o *2i7
^1
42 Micronigter Measures of DatMe Stars made at lxviil i ,
Btar*! Nuna.
Ho 351
2 I187
2 1196 AB
AC
BC
Ho 524
HU626
HU855
Ho 525
Hu 714
Ait. 551
HU627
HU717
HU858
Ho 354
Ho 355
21273 AC
Ho 360
Ho 41
Ho 42
23121
Ho 43
Ho 364
21348
21355
Ho 366
21356
Ho 367
Hu 1 128
Ho 253
HU631
B.A.
1910.
h m
8 2
N.P.D.
19 10.
68 51
57 31
72 4
8 II
8 14
8 17
8 18
8 21
8 24
825
8 27
833
837
8 38
842
855
8 59
9 9
9 13
9 M
9 20
9 22
9 23
9 23
9 28
9 30
9 43
9 59
71 2
57 23
76 33
69 42
57 30
92 13
55 10
57 14
77 43
63 37
92 22
83 15
67 II
92 2
56 4
61 2
9 14 68 48
66 42
83 15
83 21
58 8
8034
61 14
53 47
79 30
56 55
PodUon
Angle.
228*9
43*3
348-3
347 -o
346-1
111*2
108 -9
109-3
I20*0
122*6
337-1
155-3
225*0
334'4
344*3
56-5
268*1
527
171*6
177-6
185*4
236*0
149-9
71-4
6*8
2i6'8
211*7
298*7
288*9
334-8
318-5
335'!
J4*8
Ii4'4
257-9
36-8
293*6
271*0
272*2
Niunbor tfaa-.!
2*32
2-22
103
1*04
1-09
519
515
536
6*18
6*22
4'io
2*88
1*42
0*49
0-53
0-24
0-75
0-45
0*91
0*97
0*36
285
3 60
4*08
1*41
0*42
0-57
0-39
0*27
3*97
1*76
2-45
0-69
0*76
3218
5-40
1*13
073
o*74
NighU.
I
2
I
2
2
I
2
2
I
2
2
I
I
I
I
I
I
2
2
2
I
I
4
2
3
2
2
I
I
2
2
2
2
2
2
I
2
I
2
^5Sf obT.
7-0 117
7*1 8*o
5"o 57
5-0 5-5
57 5*5
8*0 ii*o
80 12*0
9*2 10*8
8*5 8*5
8*6 9*2
7*4 7-5
9*o 10 'o
8*8 9*0
9*1 9*8
8-2 8*2
8*0 8*0
33 7-8
8'o 12-0
9*0 10*0
9-5 9-5
7*5 7*8
8*0 85
8*2 11*2
75 7-6
72 7*2
8-5 8*7
6*2 7*0
6*2 1 1*0
5*5 14*0
7*0 12*0
7-0 8-6
•236
•261
•loi
•233
•251
•lOI
•233
•251
'lOI
*25I
•203
•315
*268
•268
-268
•312
•315
•307
*248
•307
•312
•270
•243
217
•228
•251
'284
•315
•345
•171
•274
*284
•326
'284
•214
•345
•226
"3"
•326
H. r.
W. B.
B.
H. r.
W. B.
B.
H.F.
w. a
B.
W. B.
W. B.
W. B.
L.
L.
L.
B.
W. B.
L.
H. F.
L.
B.
W. B.
W. B.
B.
W. B.
W. B.
B.
W. B.
L.
W. B.
W. B.
W. B.
L.
B.
W. B.
L.
W. B.
B.
L.
906.
H
Nov. 1907,
/Ae Royal OhervcUory, Grnenwich, in I
' SteUKsBe.
1910.
Position
Angle.
Number «--*.!
NIgtiti. *^^«*'
^^1
Htt654
Il ID
10 II
56 24
161*3
1*69
8'4 9'8
'233
^1
Hn«75
10 13
52 2
623
0*96
7'o 9*8
'307
^1
716
0*93
315
^1
Ho 879
10 23
52 SO
*54*6
0*42
4*0 6*5
•312
^H
2 1439
10 25
6844
II2-S
r86
8-0 8*5
•275
^1
HnSSo
10 26
52 33
124-9
o-8o
90 97
312
^1
Ho 636
10 27
56 4i
204*1
f86
9'o 10*5
•260
^1
Ho 374
10 45
66 41
27 ro
371
S'4 12*0
•220
^M
Ho 576
10 48
66 19
2i8'4
3'17
8*8 lo-o
•195
^1
1 H04S
ro 59
66 22
87
1*93
8*0 11-2
•2S8
^H
31536
TI 19
7858
5i'9
239
39 7*1
•255
^1
Host
11 27
81 s^
1762
2*47
7*0 I2X)
*3i8
^1
HqSSS
u 38
68 25
142*2
0^64
8*4 8*9
•266
^H
LamU
II 54
59 2
92
0-84
7-0 11*5
'545
^H
Ha 890
II 57
78 10
64-2
r38
9*0 10*0
•261
^H
H«535
u 58
67 44
139*6
2*18
8'0 I2'0
'267
^1
Ho S3
12 19
75 35
296-4
2*11
8-0 117
*33o
^H
ai6i9
12 20
63 55
357 "i
037
67 79
'370
^1
^1643
12 23
62 23
39*1
2-29
87 9*2
'268
^1
311647
12 26
79 47
223-9
1-59
7*5 7'8
■268
^1
2242
J -45
'303
^M
Ho 54 BC
12 37
79 37
1427
2*14
7'o lo-o
*3i8
^^
BD
...
«««
64-6
10*44
10*0 13*5
•318
^^k
H11892
12 38
74 59
1607
07S
9'3 9-3
-2S4
^H
Hn 893
12 43
77 13
33-8
1*50
91 9*1
*2S4
^1
HU894
12 49
76 20
1447
1-08
91 9*1
*2S4
^1
Ho 257
U '
63 17
154'6
175
8*8 8*9
-297
w. ^H
OS 261
13 8
57 a6
344-8
I 37
6*9 7*4
•427
^H
Ho 360
13 19
60 S
321*2
070
8*3 8*5
*37i
^H
02269
13 29
5438
217*3
037
6*5 7*0
■427
^H
Ho 645
t3 35
68 5
30-4
0*88
9*2 9*6
•34s
^1
O337S
■4 9
45 M
76-4
0'28
7'5 77
•427
^1
HoS4i
14 16
77 H
91*6
2*12
9'3 10*2
•377
^1
31S34
14 i7
41 5
2*2
0-14
7*1 7*2
•427
^H
Altkea 1105
14^3
5858
185-6
l*OI
9*1 9*4
•417
^H
Ha 542
1423
6859
2527
0*53
6-8 8-8
*37o
^1
2 106s
U 37
75 54
145 '9
0*47
3*5 3*9
•401
^1
02 2S5
14 42
47 14
126']
0^31
7*1 7'6
•427
^1
H036J
14 4¥
^S J^
WV
JX>7
2
■
7'0 loxs
467
\^.B. ^1
44 Mi^
Tometer
Measur
^tsofD
aubki
3tan
$ tnoi
deat
Lxvm. I,
start NAine.
1 910.
N.P.D.
1910.
FMiUOD
Angle.
Diit. or *g^-
Spoch
X906.
Obir.
Ho 389
h m
14 48
69 20
951
0
I-5I
3
7-0
9*3
•372
w.a
02287
1448
44 42
321-6
I-04
I
7-5
7-6
.427
a
02288
14 49
73 56
1887
I -61
2
6-4
7-1
•362
W.R
21909
15 I
41 57
244-6
4-60
2
5*2
6-1
701
L.
Ho 60
15 10
54 47
35-9
0-41
2
7'5
7-6
•467
w.a
Z 1926
15 II
51 22
2499
0-94
I
6-1
8-4
•671
L.
23091
15 II
94 33
25-5
0-25
I
77
77
•465
a
Ho 547
15 12
72 52
297-1
5*55
2
7-9
12-0
•458
w.a
21934
15 14
45 56
277
7-35
2
8-5
8-5
701
L.
21944
15 23
8336
325*3
1-22
2
7'5
8-1
•418
w.a
02296
15 23
45 41
302-4
1-58
2
7-0
8-6
•701
L.
Lewis
15 24
43 32
334-9
306
2
9-5
9-8
•701
L.
S1954
15 30
79 9
186-2
3-30
2
32
4-1
•458
w.a
Ho 63
15 32
61 19
304-5
1-53
I
9-0
9-2
•312
a
...
...
307-6
1-24
2
..
..
-437
W.B.
02 298
IS 33
49 54
13-0
1-29
I
70
7*3
•671
L.
HU580
15 38
70 2
69-5
0-20
2
5-0
5-0
.446
a
Ho 399
1552
60 12
1198
2-97
3
7-5
lO'O
•448
w.a
02303
15 57
76 28
144-9
o-8i
3
7*4
7-9
.446
W.a
21998
15 59
loi 8
358-0
0-35
I
4'9
5-2
•465
B.
2 2021
16 9
76 14
3362
4-o8
2
67
6-9
•408
w.a
2 2022
16 9
63 6
141 -0
2-56
I
6-2
9-8
-460
L.
02309
16 16
48 7
69-8
0-49
I
7-5
7-8
•427
B.
22049
16 24
63 50
205-2
1-33
I
6-5
7*5
-460
L.
23105
16 27
96 50
307
0-35
I
7 '7
77
-465
a
22084
16 38
58 14
174-4
I -01
2
30
6-5
•446
a
175-4
1-09
2
-546
L.
1786
I -21
2
•563
w.a
2 2091
16 39
48 38
125-6
103
2
7-5
8-0
-701
Lu
22097
16 41
54 5
86-0
2-04
I
8-5
87
•441
L.
De 15
16 41
46 21
294-6
0-60
2
8-2
8-6
701
L.
2 2101
16 42
54 "
53-3
4-56
I
6-3
90
•441
L.
22106
16 47
80 26
300-9
0-35
I
67
8-4
•482
W.B.
22107
16 48
61 II
3588
o-8o
I
6-5
8-0
•460
L.
Ho 409
16 52
66 30
I9'5
8*19
2
8-1
130
-447
W.a
22118
16 56
24 50
85-9
0-35
I
6-4
6-9
•427
B.
2 21 14
16 57
81 25
161 '4
1-36
I
6-2
7 4
•482
W.B.
Ho 411
16 59
66 ID
2626
209
2
8-3
12-0
•451
L.
17 4
80 3
63-4
o-6i
I
9-5
9-8
•460
L.
^^1
Not, 1907
Wte Eoyal Ohsefvatory^ Oreenwich'^ in I
906.
fl
dtftr*t BTanic.
E.A.
lOtO.
PrwitU.n
Night.. '^**~-
1906.
^H
ll tl)
tf
^^1
...
62-9
0-63
1
...
•482
W. B. ^H
Hii 170
17 s
So 8
274*5
r4S
I
8'5 10-8
■460
^1
.*.
274*0
1-93
I
•48a
^H
Ho 414
17 19
63 50
95*2
072
2
8*4 8-8
■555
^1
Ho 415
17 19
64 10
329*3
130
2
8'o 87
•555
^1
3 2i;i
17 M
99 56
75^6
1-51
1
7*5 7"^
•SSo
^1
2 2173
'7 25
90 59
3187
0-55
2
6-1 63
•5S9
^1
Htt 179
17 27
7843
50-3
2*24
2
8-8 8*9
•555
^1
ZZ20S
17 40
72 IS
303*3
211
2
8^3 87
•467
^1
1 221s
17 4i
72 16
292 0
077
2
5*9 7*9
■467
^1
Ho 432
17 48
95 IS
20 '8
0*58
8-2 9^0
•580
^H
Ho 424
'7 54
61 44
2lO'2
1*44
8*0 iro
•460
^1
2 2272
iS 1
57 28
170*6
232
11
4*5 60
•595
^1
^22^^
18 s
83 52
87*0
0-82
7*2 77
•580
.fl
Hii 314
IS 5
71 23
i42'5
0-38
8^3 8^5
•631
^1
Hujis
iS 5
66 27
547
0*52
9'3 9-3
•627
^1
Hq 316
iS 6
71 45
isro
172
90 10*1
•620
^1
Hu 317
tS 7
72 48
20-6
kS8
8-5 %'S
■620
^1
Hm 196
iS 10
81 3
345 '3
0-45
9"o 9*2
663
^1
Ha 319
iS 13
67 13
79'6
0*25
9^2 9 '6
'627
^1
H11238
18 18
So 6
344-9
146
8 6 9*2
•663
^1
Ho 83
18 20
62 32
274*5
0*61
8'S S'S
'631
^^
H0S4
iS 21
62 37
316*6
3*88
9*o iro
73*
^1
22315
iS 21
62 40
199*3
0-31
7'0 80
731
^1
B^S^l
iS 26
76 16
307*5
oSo
90 9-5
•663
^^
Ha 245
fS 29
78 17
2329
2*24
8 "2 9-2
•663
^1
Hn247
«8 33
79 49
42-4
0-51
9-0 9-3
'663
^H
H1124S
i« 35
80 56
295-0
2*00
9*5 9'6
663
RR ^1
2 2567 AB
18 37
59 49
254*4
0*40
7'o 7'S
•S08
H
2
195*9
1413
70 S-2
-808
^1
H0437AB
18 37
58 27
297*6
0*44
8-3 8-5
•S08
^1
AC
291*3
2272
8*3 13-0
'808
. ^1
Dd
344 9
381
\v'2 117
•808
1^1
EI12S4
18 46
Si 59
16S7
103
8-9 13-5
736
^1
Hti256
18 46
81 24
186*4
3*78
2
8*5 12-8
700
^1
Ktt 25S
1849
78 30
213*8
2*58
3
8'9 9*4
•629
^1
22422
1854
64 1
957
o'88
2
7*6 77
'680
^1
Hii 13^
18 5S
70 Ji
317
077
2
■
9'0 9*3
700
^1
46 Micrometer Measures of Double Stars made at LXViiL i,
1910. Angle. ^'^ NiSiti. ^^ ^^aS. ""*
77 54 363*1 3*04 3 8-0 lO'S -651 W. B.
Star*! Name.
HU678
Ho 92
22437
Ho 443
1910.
h m
18 56
18 57
18 58
19 6
57 37 34*0 I "33
9«o 9*1 '808
fi 1204 AB 19 7
2 2476 —AC
Ho 445
Ho 446 AB
Ho 447
Ho 576 AB
Ho 105
Hu339
Ho 451
22525
Hu 340
22536
Ho 274
Ho no
Ho 112
Hu 1 195
Hu 346
19 9
19 9
19 13
19 16
19 18
19 21
19 23
19 23
19 24
19 28
19 31
19 35
19 37
19 39
19 44
A.G.C. II AB 19 45
22596
Ho 583
Ho 584
Ho 118
Ho 591
Ho 457
Ho 130
Ho 131
22690BC
jB 151
Ho 458
Ho 144
Ho 150
Ho 151
19 50
19 55
19 57
19 59
20 14
20 21
20 23
20 24
20 27
20 33
20 35
20 48
21 4
21 6
21 9
70 58 58-1
70 44 117-6
117-9
87 32 87
65 34
65 35
62 14
83 21
73 31
71 32
62 18
62 51
71 43
72 25
73 45
71 31
71 35
76 31
73 7
71 6
74 58
68 8
64 3
56 35
62 23
60 55
53 6
71 32
79 3
75 43
61 10
70 13
71 31
86 31
74 24
0-89
3*04
277
0-32
7-8 8-0
95 95
77 85
244-8
291'!
173*2
181-2
187*5
47 "o
297-0
310-2
120*9
79*5
74-1
78-9
79*4
322-5
1844
145*3
320-6
252-6
228-7
26-7
292*1
60-8
106-3
326-1
234-5
100-3
279*8
1677
T35*i
192*0
i57*S
5*18
2*92
2-05
3*59
2-56
0-50
4-14
0-66
0-85
178
375
2*50
2-65
2*42
0*62
0-18
2-12
1*59
2-05
2-73
2-14
2-21
2-51
4-82
0-27
015
1*98
0*42
2*69
1*78
0-2S
2
I
I
I
3
2
2
I
2
I
3
2
3
I
I
I
I
I
I
I
I
2
I
2
I
2
2
I
2
I
2
9-3 IO-2
8*0 13*5
9*5 9*5
7-0 10-7
8-5 lo-o
8-6 8-6
9-3 ii-o
7-4 7*6
9*o 9*3
8-0 II -o
8-3 ii-o
9*5 9*5
9-0 9'o
87 14*5
8*8 9-5
57 6-2
7-2 8-6
9-0 10-7
6*5 12-0
9-1 II'O
9-5 lo-o
8-1 81
8-5 8-7
7*8 11*2
7*5 7*5
47 6-1
9-0 9-1
7-0 7-0
9-0 1 1 -5
8-5 8-5
70 7-0
■681 W.B.
-700 H. F.
•665 W. R
753 B.
213-7 31-08 2 6-2 ii-o -753
-660
•736
-665
736
•600
•659
•660
•682
•659
736
-680
-660
-600
736
•736
*8io
•813
•682
723
723
•813
-601
-652
-641
-810
791
791
•723
•693
-616
791
w a
H.F.
w.a
H.F.
W. B.
W.B.
W.B.
W.a
W.B.
H.F.
W.B.
W.a
W.B.
H.F.
aF.
B.
W.B.
W.B.
W.B.
W.B.
W.B.
W.a
L.
W.B.
B.
B.
W.a
w.a
w.a
W.B.
a
3Hi
Nov. 1907
. th€.
Soyai Observatory, Greemoidi, in i
906.
fl
Stain 3C4mft.
1910.
Anglis.
Nighto, *^'****
Epoch
1906.
Ob«r. ^H
02535
b m
21 10
So 24
212*2
0*16
3
41 4'I
773
^1
230-8
o*i6
2
.i*
791
^1
,.-
,.,
2277
0*24
2
*827
^1
Ho 2g4
ai 12
74 M
89 VD
3 '57
90 9'3
703
^H
Ho IS4
21 14
59 4S
2oS'6
3*6'
7'S 11*0
*9i5
^1
Ho 155
21 16
37 8
35-8
2*37
8*0 9 '5
772
W.B. ^H
H«» 157
21 19
58 22
23'I
3-8o
77 77
77a
^H
Attkea fai9
21 21
60 S
124*3
»*33
9*3 9'4
775
^H
Hu 276
21 24'
82 40
267
0-85
9'3 97
■843
^1
2^799
2t 24
79 21
iiS^o
1*66
6-6 6-6
*843
^1
52804
21 29
69 41
rSSH
2*97
7'3 80
*S72
^1
Ho 161
at aS
50 20
359^5
2*50
7"o no
•9' 5
^H
HU371
21 31
65 57
169*9
0-22
7*0 7*5
•810
^H
Ho 164
21 37
55 20
66-6
375
SH3 S'J
•915
^1
Ho 166
21 40
62 34
73'9
71-1
031
0-31
7*5 7'S
*76o
*862
^1
^1
3282a
21 40
61 39
1241
2*22
4'o 5-0
*6i6
^1
fl989
21 41
6446
104*5
027
3*9 4*4
714
^1
io7'tt
0*19
*S2I
^H
loS-i
0*49
736
^1
...
...
107-9
0-27
791
^1
Hd6o&
21 43
63 7
1195
a '64
8*2 97
862
^1
Hm66
21 44
55 3a
1447
r6i
S7 9'2
•915
^1
Ho 467
21 46
68 lo
i86'2
'45
8*0 10*2
•689
^1
Ho 173
21 51
7> 44
S2'0
1*17
8*0 lo'o
*843
^1
Ho 609
21 SI
60 4
1767
3'20
9-5 9*8
794
^H
Ho6io
21 5^
63 35
231 "O
o'66
9*0 9-2
•S62
^1
^ HjlgjS
22 8
76 32
22«'6
o*6is
S'5 90
•819
^H
^ Ho 17^
22 9
60 14
251-0
0*65
8*0 9-0
-S19
^1
^ Bm82
22 19
72 54
128*3
t*43
S-S 8*5
*8o9
^1
H01S3
22 21
67 S3
2i6'3
2-51
8*2 u'6
•843
^1
; «M75Ji^B
22 29
64 3
3i7*<5
0*89
8*o 8-2
•827
^1
' flo^4
22 33
63 2
62-9
2*10
8*0 lo'o
*8i9
^1
Hu296
t2 36
75 56
68*5
0-32
5^5 5'5
'S46
^H
^ Bi> 190
22 45
62 28
1537
2-03
9^2 9*2
•822
W. B. ^H
. H.4S1
22 47
64 5
73*0
0*14
6*8 6*8
*8S2
^1
^ Bm&4
22 54
69 44
ioS'5
y^9
S-o 12 0
*8o5
^1
. H«jji
22 55
60 24
297
1*82
8*5 8-5
•874
^1
1
22 58
7J S3
3^3 *S
0'37
■
87 9*0
*805
^1
48
Prapcr Moiioiis 0/ 1 1 86 Varrington Stan* LXVm. i ,
star's Name.
B.A,
19^0.
h ID
23 10
N.P.D.
Posltioti
Angle.
Dl*t, of *J?f^*'
Epooh
1906.
Oben
Ho 299
66 15
77 »o
1-48
I
8*0 10-2
'835
W.H,
Ho 19S
23 U
7338
337
2-26
4
8'0 9'o
'856
W, B.
Ho 300
23 19
78 II
304-1
0-15
S'o 50
882
B.
Ho 301
23 20
76 I
3597
ro9
72 II'O
835
W. B,
Ho 489
23 22
62 47
240*0
0-42
7'S 7-8
•835
W. B.
Ho 201
n 33
55 51
340'9
4-n
80 93
'915
H. F.
Ho 303
23 3<5
70 S
187*4
J -15
S'o iro
'862
L
Ha 300
23 41
§4 1
1 20 3
129
87 9'o
•882
B.
Ho 206
23 54
56 u
184-4
2'II
8'o lo'o
928
W. B
Ii<njal Observatory, Qreemoieh:
1907 Novtvibtr 6.
Proper moiions of 1 186 Camngian Stars from a direct comparison
hetioeeii Oar7*in'jton'i Catalogue for 1855 and the Greenwfrh
Secojifi Nine-i/ear Caivdogue for 1900.
{Ciymmnniatird bij the Asirowymsr Royai,)
The proper motions of tlu* following stars, which have been
observed with the transit circle at Green wicb during the jears
1897-1905, for the purpt^so of determining their places for use a^
reference stars on the astrographic plates, hav« be^^n derived from
a direct coni[>ari&on with Garrington's Circunii»olar Catalogue for
1855, For thii? purpose the platiKS in Garrington's Catalogue have
been reduced to the epoch 1900 by the ordiimry trigonoinetricsal
foTmula with the Struve- Peters' constants, aod in addition the
syatematic correctionti given on p. 321 of Monthly Notices^ Ixvi. 5,
have been applied.
Fall details will be published in the Introduction to the
Greenwich Kine-year Catalogue, 1900. The proper motions for
botli R.A. and N.P.D. are given in arc, and arranged in Zones of
N.P,D. ; the magnitudeij are taken from the Harvard Photometry
(marked *) and the Bonn Durchmustemng.
ZONB
Lon^^H
Oitr.
No,
Mag.
Approx.
Pmp«r Motlous»
Cart.
No.
Mag
1900.
Proper Moilonfl
unit'ooi. ^~
B.A, N.P.D,
h m
+ - -1-
- i
h ID
+
- + -
101
9*2
145
... 0 7
h
8-9
"35
25 ... 13
303
9'0
232
„. 3 -
22
i
8-S
1242
20 2 . .
b
8 '8
319
». 3 -'
40
1
90
1351
3
.., 7
538
9'2
428
... iS ...
4
t
9-3
1529
5 3«
d
9' I
639
... 27 ...
4
r
9 '3
^5 55
10
9
«
9'i
830
... 17 ..
22
n
87
16 9
22
... 7
g
9-0
11 0
... 83 ...
3'
3601
9^0
23 It
2
9
^^^SHH
^ars. 49 ^H
Nov. 1907. Proper Motions of
1186 Carrin^ton I
ZOKB 1%
H
*kT ^
^^T
Proper
Unit
Motloni.
^rr-
Prof>er Motions ^^|
J90X
B.A-
N.P.D.
i9i».
JUi. K.P.D. ^H
b m
+ -
+
^
h m
<f - + ' ^H
ij S>8
0 16
.,. 8
2
1951 87
12 S2
■
117 65*
056
68 ...
3*
1972 8*0
13 4
^M
f 137 9 a
I 0
... 24
9
2048 8*5
1327
^M
183 80
I t8
24 „,
t8
.».
2068 9 '2
1327
28 ^H
l8i 2 I'
1 2Z
36 ...
...
0
2333 8*0
*5 5
16 ... ... 24 1
251 8*2
t 50
36 ...
13
*..
2494 9-0
j6 6
20 2 ^J
^ 263 8-8
156
51 ...
3<
2639 8 '8
17 6
^1
284 8*0
214
»- 23
33
2740 90
1732
7 ■
^30$ 8-8
217
... 175
*,.
35
2762 9'o
•7 42 .
.- 14 ... 43 B
^psp
235
0 ,.,
29
...
2793 8-5
1752
* ^M
^^ 347 8*5
242
5 ".
38
*.*
2770 8*0
1754
^H
I 375 ^7
252
25 ...
35
...
2942 &*$
1849
.. 9 ^1
^K 412 90
3 5
0
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Proper Motions 0/ 1 186 Carrington Stars.
LX¥m!^H
Zone 2'-
-continued.
■
Approi. Proper MotioiiA.
kA. Unit '001.
Sit, *"•«*
Arams. Prooer Mutiooi,
lUL Unit "\x,i.
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Stars. 5 1
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• 1907. Ft'oper Moiitms of 11 S6 Carritigton
ZoN« 3* — continued.
Proper MoUoni*
E.A. H.PJ),
1494
h m +
$-8 to 10 ...
44
+ -
2 ,..
h m
2484 90 16 20
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12 ... ... 30
1519
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24
2
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4 26
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43
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... 18 30 ...
1633
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S
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2579 9'4 1659
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32
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1669
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1683
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2
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52
Proper Motions of 1 186 Carrington S^rs. LZVm. i.
ZoN's 4* — continued.
Carr.
No.
Mi^/s:!?"
Proper MoUont.
Unit "001.
Cur.
No.
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+
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1
|H
Nov, 1907. Proper Motions of
1 186 Carrmgton
Siars.
1
Zone 4*^
-continued.
H
Miff
"Tt
Proper
Uolt
Motions.
"'cot.
'S^: «•«•
Approz.
La.
Prt
per Motions. ^^H
[J<'ooi. ^^1
t9«».
E.A.
N.P,0.
tODO.
B.A.
N.P.D. ^m
b m
+
-
+ -
h m
+
_
+ ^H
2423
7-1-
'5 57
...
60
... 65
3141 S'o
20 27
58
34 -. H
2S4S
87
1650
39
... 44
3200 S'o
20 50
40
...
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2619
9*4
1719
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24
n ...
3218 8-8
20 59 247
■
a6S4
92
1746
64
13 ..^
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21 7
13
^1
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9'3
1756
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21 23
13
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3751
75-
18 7
2
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3360 8*5
21 51
24
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8-7
1828
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28
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13
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32
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4
r Motions of 11B6 Carrinffton Stars, LXVni.
3
^^L
Zone
5'-
cmdinued.
m
m
^^^H^- ««»•'
.gprox.
Proper Motioua.
Uiilt''*ooi.
1900.
Proper Motioiis. |
Unit" 001. 1
S9OO,
B,A. I*\P.D.
ItA.
N-P.I>. 1
^^1
li m
+ - +
-
h m
+ -
+
-
H 971 9'3
649
,„ 22 IS
1965 8'S 13 10
13 .-
0
...
^H IOI2 9*3
7 6
... 3 7
1975 9-0 13 II
16 .»
...
It
^1 1029 8*0
714
... 3 55
1995 8'5 1317
... 16
...
22
^H 1065 9'o
728
.., 45 .,.
20
2006 S'o 13 20
... 96
37
^H 1096 9*0
740
19 ... 0
...
2014 8'8 1323
... 62
6
^H 1098 8 '9
742
... 10 59
...
2093 S'S 1353
... 10
...
20
H ztt5 7'S
746
,,. 19 II
2165 8*0 14 22
... 10
...
4
H 1^37 6*3*
7 53
.- 42 26
...
2187 9*0 1430
... 19
45
H 1 153 ^'S
8 2
^ 22 13
2196 8*6 1433
6 ...
26
^1 1 184 8*9
8 14
... 19 ...
26
2223 9'o 14 42
,.. 22
9
H 1 1 88 S*3
8 IS
... 10 28
...
2271 7'i* 15 2
... 19
11
^V 1233 8*0
835
... 127 103
..-
2283 8-4 15 7
13 ..
0
...
^1 1278 9'o
853
... 26 9
2288 8*9 IS 8
19 ...
73
■ I2$6 63*
855
6 ... ..
20
2342 8*3 1529
16 ...
20
^H 1296 8-6
857
•• 23 4
2354 9-0 1533
37 .»
»5
H 1547
9 IS
10 ... 18
...
2373 8*8 15 40 107 ,..
50
H 1379 ^'5
924
10 ... 44
...
2426 8*4 i6 0
... 66
116
H 1393 8*3
931
... 22 22
2491 8*7 1629
6 ...
...
28
H 1399 87
932
... 16 2
...
2498 8*5 16 30
16 ...
*5
H 1397 8-8
9 3^
6
31
2515 S'S "641
13 ..,
2
...
^H 1402 8*7
932
29 ... II
2558 9*0 1657
... 13
7
^H 1410 8*0
9 35
... 16 7
...
2565 8*5 1659
.- 37
0
... .
H HH
9 37
16
26
2571 9"3 17 I
... 3
...
19
^M 1442 8*8
948
... 29 ...
2
259S 8-2 17 12
.- 3
^
H 1451
9 53
6
13
2642 7*7 1729
35 -.
3*
^1 1468 8-9
10 0
... 3 2
...
265s 8*8 1734
... 10
18
.,.
H
lois
... 104 38
...
2668 8*6 1741
... 16
...
7
■ 1529 8*5
10 17
... 68 40
...
2679 87 1744
13 ..-
II
...
■ IS40
10 21
3
56
2693 8'9 1749
29 ...
...
IS
H 1569 9*2
10 31
... 42 ...
29
2698 9-2 17 51
6 ...
...
4
^M 160S 8*6
1047
... 10 ...
4
2743 9'o 18 6
32 ...
50
^H 1702 S'li
II 25
... 24 ...
13
2746 8-2 18 7
32 ...
28
^H 1709 8*6
II 26
... 107 4
2744 8 '4 tS 7
22 ...
M
...
^1 1740 9'o
n 36
... 40 20
»,.
277S 9'o 18 ao
... 48
2
^1 181S 8*1*
12 9
... 10 ...
II
2782 S'S 1821
23 ...
9
^^ 1829 8 '5
1214
... 48 2
...
2790 7V 1825
10 ...
7
■ 1843 S'5
12 19
,,, 22 ...
2
2810 8'5 1S32
26 ...
80
^H 1856 8*7
1223
... 10 ...
4
2817 8*5 1834
16 ...
9
...
■ tS82 7*3*
1238
„. 220 ...
20
2824 8*8 1836
... 16
1
■ 1945 ^'^
U I
... 16 133
2859 8*6 18 47
37 ...
^^ 1956 8*6
13 5
... 45 20
3895 9*2 19 I
22 ...
44
1
^
^
^pov
r
. 1907. Fivper Motions 0^ 1(86 Carnngton
Stars,
"J
^^Ht
ZONB 5"-
continued.
H
^mCmrr.
M**^'"
Unit "*ooi.
GMT, ^^
Approz. Fr^per Motloui. ^^^|
R.A. Unit "-cot. ^^M
1900.
E.A. rf.P.D.
1900. ILA. N.P,D. ^^1
b m
-h - + -
h m + - +
^^M
9-2 19 2J
35 24
3262 9'3
21 20 ... 3 32
^^1
I 1964
9-0 19 26
32 .» 0 ..,
3285 9-0
31 27 ... 22 50
^H
29S3
S? 1934
13 22
3382 9*0
22 0 ... 29 0
^H
1 3019
9'3 »9 49
«9 33
3422 8*0
22 14 39
H
3034
8'5 1954
35 9
3436 7*5*
22 21 .., 13 7
^H
W3
8-5 J9 57
«8 57
345S 7-2'
2227 45
^H
1068
8*8 20 5
35 -. «8 ..*
3509 71*
2250 92 ... 35
.^H
' 3091
6*6* 20 f4
10 „, 64 ...
3520 62'
225} 35
^H
1 V20
8*5 20 23
20 , 22
3519 S'o
2253 53
15 '^^H
1 3»23
7-2* 20 24
45 60
3634 87
2334 42 .„ 4
.., ^^^H
^Ji28
7*l* 2025
... 81 0 ...
3646 9-0
2338 13 ,., 20
■*■ ^^^^^^^^1
Hsi88
9*3 2047
,., 19 *5 ••
3647 8-2
2339 .» 26 30
^H
Hpos
S'4 2053
3 .^^ 48 ...
3653 90
2341 .. 3 18
^H
B323;
1 ^
9*3 21 9
... 10 4 „.
ZoN
366J S'l
E 6".
2344 3 .' -
ij ^^^H
S'S 0 4
58... 2 ...
485 8-2
323 9 - 18
... ^^H
10
910 0 7
156 ... 28 ...
504 7*5'
3 34 .^^ 3 16
... ^^^1
60
8'3 028
22 ... ... 17
530 90
3 43 ." 0 24
*** ^^^^^^^^1
7^
91 034
78 n
.532 87
3 44 ... 3 7
^H
109
5 '6* 045
63 ... 28 ...
565 8^8
358 ... 22 ...
^1
liS
9-1 048
49 "
571 87
4 I ... 19 .-
^m
h*?'
9'2 I 9
15 .-^ ... 2
SiJo 5V
4 5 3
^M
■^179
9*3 I !i
219 4
593 57"
4 8 ... 49 .,,
^H
206
89 124
22 4
596 87
4 12 19 .„ 26
^1
233
89 1 37
... 85 ... 2
618 7V
422 0 ... 54
.. ^^^1
*43
87 I 39
3» 9
633 8-9
428 ... 3 44
... ^^^1
255
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26 II
647 9-0
4 34 .- 7 "
^3 ^^M
157
ro 1 44
^.. 7 13 -
64S 8-5
4 34 22 ... 33
^H
299
69* 2 I
49 • 38 '-
654 8'5
4 37 '.. 27 ...
^1
^Hjia
8'9 2 to
11 . , 18 ..,
657 8-8
438 ... 19 9
^H
1^352
8-0 2 20
... 19 .., II
669 8'5
442 12 ... 18
^H
r^342
9*0 2 23
... 26 . 2
691 9'o
450 .. 19 ..^
^^M
^■354
9*0 2 28
... 56 ... 37
725 87
5 5 Q -. 50
^H
^Vl^l
9*0 231
... 22 7 ...
726 90
5 5 » •
^1
1^^"
92 2 51
51 28
732 9*0
5 9 ." 48 24
^1
^^437
92 2 57
"9 4
738 7-3*
5 12 „. 15 0
^H
^■fl0
7-5 3 8
IS ... 15 ...
747 9'o
5^5 3
^1
^Pl57
9'o 3 9
... 29 ... 9
776 87
530 22 ... 19
^H
4S8
8-2 3 9
41 .^ 46 ...
9 2g 1
S36 9'2
5 55 -' It ..
^1
477
8-8 J so
S49 9 "2
6 1 15 ... 26
^A
■1
I
P
^^^^^^^B
■i
pe
r Motions of 11S6 CarringUm SUnn,
Lxvm. I,
56
Pro,
Zonk 6" — coniinued.
m
Ifo.
MAg.
*ffr-
pEwer Motions
^: M...
•er
1900*
R.A. K.F.a
igooi.
E.A.
ir.p.D. 1
b m
-f
- + -
h m
+
-
4-
1
852
9'
6 S
7 11 .*.
1581 9'5
1036
T2
...
" 1
866
8'9
6 10
,,.
7 32 ...
15S3 8-6
1038
...
7
4 I
908
9'3
6»5
...
12 9 .. '
1619 8*5
1052
...
31
...
*^m
950
9'0
6 40
...
12 ... 13
1641 8-2
to 59
...
87
20
... ■
953
8-5
64J
13
... 24s .-.
1643 88
It 0
...
97
33
...
974
9^0
648
12
24
1665 9*0
u 9
...
44
...
«s
979
8-9
650
.«*
7 24 ...«
166S 8^4
11 ti
...
22
25
—
990
9-0
653
3
... 4 ".
1704 8*8
u 25
...
34
4
• 1000
8-2
659
19 22 ...
1746 8*4
11 38
...
15
4
... ^^
1066
8-0
726
12
13 -*.
1761 80
II 45
...
15
IS
-m
io?4
92
729
63
41
1763 9*0
1148
93
20
\
1109
9*4
742
»*»
12 37 .»
1766 9-0
II 48
...
10
...
^ 1
1159
8-2
8 4
56 57 ...
1771 8*5
11 52
49
...
37
- J
1177
93
8 10
*t.
7 55 ...
1780 87
n 54
34
2
J
1207
9*2
823
60 96 ...
1781 8*8
1154
o
33
"-■
'235
9*2
83s
♦ .t
IS ..* 7
1790 8'4
II 58
'5
...
15™
1254
7r
842
...
3 .- 2
1831 9*0
1215
10
...
6
1262
7i*
845
15
17
1S33 87
12 16
...
26
...
9
1272
8'S
849
3 4 ...
1836 8-I'
12 17
7
...
..*
»5
1289
9X>
854
...
15 2 ..,
1841 8*4
12 19
63
...
7
1298
9-0
857
...
26 ... 17
ii>47 7'9
12 21
12
...
4
...
1297
90
857
...
19 -^* 4
1852 8 '6
12 21
15
...
2
f3»6
9-2
9 3
71 SI .^*
1913 6*0*
12 48
27
49
13W
9*5
9 7
...
3 ." 13
1914 5*1
12 48
27
43
1339
9 5
9 12
*.i
15 2Q ,..
1916 85
1249
15
..»
ir
1369
7'i*
9 20
4.»
12 11 ...
1 92 1 7*2*
1^53
26
...
...
35
J 407
S'o
9 33
...
37 .. 4
J925 8-8
1253
15
...
6
1408
8'3
9 33
.♦,
0 ... 4
1937 9-0
1259
...
41
2
1419
88
9 37
12 ... 11
1938 8'3
1259
...
27
0
1427
8*8
940
7
0 ,,.
1970 87
13 II
.♦.
12
29
*»•
1434
8*5
9 43
15 26 ..
1969 8*9
13 n
7
6
...
»435
8-0
9 44
139 115 ..
2022 8*5
1326
,♦♦
22
...
17
T441
r 1470
90
9 47
IS ..^ 13
2023 7*3*
1327
29
...
9lM
8-9
9 59
...
7 9 ^..
2080 6-1*
1345
46
...
44
J^
1 1475
85
10 0
.«.
22 24 ...
2105 9*2
13 S«
...
36
...
49
1503
6^^
10 12
15
... II ...
2137 8*9
14 9
...
22
20
...
1 1518
8*6
10 15
3
20
2141 9*0
14 10
...
19
...
30
iS^3
9-0
10 15
26
... 4 ...
2177 8-5
1427
...
12
4
11 «537
8-4
10 iS
7 26 ...
2207 8-6
1436
,.»
75
9
^53S
sv
10 19
.*.
65 •' 33
22C6 8-5
143^
...
26
93
iS6t
0*0
■
t0 2S
■
41 0 ...
2244 9"o
h.
1448
22
■
■
■
II
■^^^^^^1
1
1
Nov, 1907. Proper Motions oj
■ 1 1 86 Carringtmi
Stars.
Zone 6 -
-continued.
■
I90D.
CTnU
R A.
Motions.
"'C0>t.
.JJ.P.D.
Proper Bfotlont. ^^|
Unit "*aDi. ^^M
K.A. N.V.D. ^H
mSi «8 15 7
12
—
4
h m
2935 9 J 19 i«
63 ...
+ - ^H
... 13 ^M
J2S6 9*0 15 8
48
0
2965 6*4* 19 28
37 •
■
2291 8'5 IS 12
22
...
II .,.
2971 9'o 1930
31 -•
... 4 ^1
2296 S-S 15 12
...
77
.»^ 43
3005 9-0 1945
26 ...
^M
23St S'S 1546
3
...
-• 35
3004 ^^i 1946
3 ".
^^1
25^7 89 15 47
19
0 ...
3071 9*0 20 6
44 -'
^M
2401 8*4 IS 53
..,
44
... 48
3072 8-6 to 8
61 ...
^H
a4<>4 7'3 «5 54
26
2 ...
3073 8 "6 20 8
34 ^^^
^M
2416 85 IS 59
19
... 26
3077 8*5 20 JO
31 ..
^H
24tS 8-5 16 0
.,.
3
... 46
3103 8*5 20 18
31
^^M
2424 77 16 I
12
«..
18 .,.
3132 9*0 2027
IS ...
^H
2448 8*2 16 12
3
...
.,. 9
3163 6*2* 20 39
38 ...
^1
2501 7 J 1634
3
... 13
3202 8-8 20 54
12 ...
... 5 ^M
2524 8*3 16 46
26
...
4
3216 77 2059
43 ..*
^M
2557 9» 1658
12
... II
3264 7-1*2122
41 ...
13 •*. ^M
2599 8*8 1715
0
.,, 17
im S'S 2131
37 ."
^M
2631 87 1727
7
13 ...
3309 8-6 2135
19 ...
^^M
2633 9x> 1728
7
...
2 ...
3318 8-4 2140
41 ..-
^^M
2632 90 17 28
41
...
... 30
3334 «'S 21 46
... 12
^^M
^647 83 1732
19
... ti
3337 8 '9 21 47
401 ...
• 43 ^M
^M 7*5* >7 33
88
...
... 103
3346 7:0* 21 so
102 ...
^^M
2729 8*8 18 2
.•»
7
". 35
3367 90 21 55
41 ...
^H
2747 77 »S 9
15
... 4
3386 8-2 22 2
7 ...
^^M
2779 7 '8 i8ai
*■*
9
31 "
3395 9'0 22 4
... 12
^H
2786 8*2 18 25
15
...
2
3416 9*0 22 12
3 .•
... 24 ^H
2788 9-0 1826
...
15
... 7
341S 8'5i 22 12
46 ...
^M
2796 S^ 1828
27
...
0 ...
3438 8*3 2222
298 ...
... 5 ^B
2802 8-5 18 30
...
3
... 27
3469 9*3 2236
44 ...
^H
2X20 7*3* 1836
19
... 38
3505 8-0 2249
... 151
^M
2S22 6 2* 18 37
'9
28 ,..
3525 5*o* " 55
129 .„
.» 29 ^H
2i>7o 8-8 18 53
%l
...
44 ...
3573 8"o 23 »3
41 .>.
.. 13 ^H
2876 ^% 1S54
22
*..
20 ...
3628 9'2 2333
J94 ...
^^M
21884 «*S 1856
34
...
... It
3630 9-0 2333
60 ...
37 ... ^M
9908 6-8* 19 4
31
...
24 ...
ZON
3656 9'i 2342
56 ...
^M
7 8-9 07
57
...
... 20
108 5 "6* 045
14 ...
^H
^^L 16 910 0 10
4
... 16
116 8*s» 049
4 ...
^1
^H 17 8'S 0 10
35
JS ...
119 8*4 050
98 ...
Z09 ... ^H
^H 22 816 0 12
31
...
... 18
138 8'8* 055
61 ...
^H
^^ 61 9*1 028
22
■
■
27 f
ISS ro I I
0 ...
^H
S8 Proper Moiwm 0/ 1 1 86 Carrimgion Siars. Lxvnt r.
Cwr.
Wo.
MiW.
1900.
Xfnit
Mmg,
19D0,
E^ H.P.D.
h m
+
-
+
-
li m
+
_
+
_
189
9"o
I 15
iS
..,
II
1078
9-0
730
4
•■4
0
...
203
8-8
I 23
43
...
*.»
i3
iioS
9'3
741
..,
4
-i^
21
205
8-6
123
0
z
...
1125
91
749
*••
4
«..
9
248
8-8
I 40
SJ
.*»
9
...
1144
S3
7 55
...
61
7
..
274
8-4
ISO
0
...
...
II
1165
6-2*
8 S
18
.^.
2S
310
9-2
2 7
.,,
S
...
2
1 197
87
81$
...
4
^3
.«.
333
87
2 ao
47
35
...
III I
S's
823
...
"4
7
344
92
223
8
...
...
31
1315
9'S
S24
.1.
14
.,.
li
359
9*2
230
82
II
12^
87
827
*»*
22
24
'"
423
80
254
43
...
r..
7
1222
67*
S28
...
8
7
438
9-0
3 0
3i
..*«
42
...
12S7
9-1
S41
...
a
38
..,
44S
94
3 4
4
...
18
1274
92
849
4
.*-
7
*m^
459
9-3
3>"
22
...
7
1318
8S
9 4
...
25
38
...
521
8-4
3 39
...
18
13
I34I
8-5
911
25
...
58
...
541
90
346
8
...
27
1342
8-5
912
...
0
...
13
556
9-0
3 54
14
II
1360
87
917
...
25
36
601
93
4 12
18
...
4
1377
8-9
922
0
...
41
609
9*3
416
...
14
II
1387
7V
9 26
8
*
^,-1
614
8-6
418
18
13
1392
8-8
929
...
53
18
- -
687
8-6
448
43
4
1404
8-5
931
...
53
...
2
695
90
450
14
...
27
1424
9*2
9 39
...
8
...
2
711
92
4 57
...
8
46
1432
9-0
942
57
16
742
8-9
512
8
...
2
1474
7-6'
10 0
22
...
29
— ••
745
9*2
5 14
51
2
1500
9-0
10 9
...
59
...
4
774
9-0
528
22
...
...
7
1524
81
10 15
...
49
22
802
9*2
540
4
18
I52I
90
10 15
4
4
-■'
800
7-6
540
49
42
1545
90
10 21
14
^0
820
S7
5 47
18
22
1547
8-9
10 21
78
29
'"
879
8-5
614
4
13
1556
8-2
1024
14
...
7
880
90
614
14
...
44
1562
77
1028
...
39
34
'"
898
9-0
6 20
69
...
137
1567
9-0
10 29
53
27
..-
910
6-4*
623
8
28
I57S
8-9
1033
10
...
^ga
909
8-8
624
18
24
1623
8-8
1052
14
...
...
%e
944
87
637
31
44
1628
8-5
1053
57
II
-"
954
87
640
25
2
1650
9-0
II 2
18
^0
972
90
646
0
2
165 1
7i-
II 2
120
168
.—
992
80
655
14
...
4
1657
S-6
II 5
...
25
IX
1017
9-0
7 5
35
2
1693
8-3
II 23
76
...
41
.»•
1027
5-0*
710
27
36
..
>73i
8-0
II 33
18
...
24
---
1040
8S
715
...
4
4
1742
8-6
II 37
...
53
720
22
35
1747
77
II 38
22
...
...
9
1
ifoY. 1907. Projfytr Motions of
1 1 86 Carrington
Stars.
Zone 7*^ —
^'ontinued.
■
4900.
Proper Motions,
1900.
TroptT Mottom. ^^H
Unit "oor. ^^H
R,A. N.P.D. ^B
b m
1^6$ 8'S M 4S
+ -
18 ,..
+ -
14 ...
li m
2451 9-0 t6 14
25 ...
176S B3 ,14s
... 49
... 23
2461 8*5 16 19
25 ...
9 ... ^H
I77J ^*^ ' » 53
... 14
,. 9
2475 87 1623
0 ...
^M
1791 7-^ 1 1 58
4 ...
... 7
2479 8"o 1624
... 8
^M
1807 6*3- 12 7
... 14
7 .^.
2502 8'S 1636
0
^H
iSio S-^ 12 7
22 ...
... 38
2537 S*5 T652
10 ♦..
^H
tS54 »"9 1223
18 ...
»3 -'
2542 8-3 1654
10 ...
.- 3S H
iSS^ 8'o 1225
.,. 67
... 16
2550 4 V 16 56
... 10
^^M
1869 8*^ 1231
18 ...
.. 63
2552 9'o 1657
31 -..
^M
1902 ^'S 1245
14 ...
2
2575 9'o 17 6
8 ...
^H
1912 S*6 12 47
4 »..
.. 24
2587 S'j 17 10
c ,,,
^H
192J 8'S 12 53
... 86
31
2592 9'o 17 13
8 ...
^H
i97» ^7 13 t2
- 39
2 ...
2595 9*o 17 IS
22 ...
^M
1982 S5 1315
.. 63
7 ...
2624 8*5 17 26
31 ...
^M
19S3 99 13 «6
4 •
... 20
2638 8 '5 17 29
18 ...
^M
1987 8*4 13 17
. . 63
... 18
2650 9-0 1734
... 18
.-. 44 ^H
2009 S5 1322
14
9
2651 9-1 1736
8 ...
9 .* ^H
20J6 8*6 1332
... 14
25 ...
2662 9*0 17 39
61 ...
^H
2052 8g 13 38
., 8
2
2713 9-0 1758
31 .-
^M
2066 910 1342
... 4
... 13
2717 8-8 17 59
0 ...
^H
2103 87 1357
.., 29
... If
2741 8-3 18 9
43 '..
4 ..* ^M
21 tl $*2 1359
... 4
24 ...
2772 87 1820
31 ...
^M
2132 8'5 14 9
10 .,
0 „♦
2780 7y 1823
22 ...
... 20 ^H
2152 9'o 14 t8
10 ,..
4 ...
2792 8*4 1828
22 ...
^H
i»57 8'5 14*9
20 ...
36 ...
2795 S'5 1S30
... 45
^^M
2186 9*0 14 31
*** 22
... n
2800 8*5 18 31
... 4
^H
2193 «7 1433
... 29
... 82
2813 8*0 1835
... 10
^H
2222 85 J4 43
14 *.*
20 ...
2S65 8*5 1853
25 ...
^M
2232 910 14 46
... 2S
22 ...
2903 6'8* 19 5
25 ...
^M
2261 57* 14 57
153 ".
232
2920 77 19 12
10 ...
^H
2263 9-1 14 59
... 4
. ■ 9
2937 9-2 1921
8 ...
^M
2289 SB 15 tl
8 ...
'. 33
2940 93 19 21
31 ".
^^M
2328 8-8 J5 26
..* 39
.. 7
2985 8*5 1937
18 ...
^M
2143 ^'2 iSl^^i -
... 25
3006 9'3 1947
8 ...
^M
2j6o 6*9* 1538
47 . .
18 „.
3036 9-3 1957
0 „,
^H
2^6 85 1544
. 43
... 51
3041 7 '6 1959
to ...
^H
2399 9ni 1553
25 ...
-. 44
3081 8 '5 20 13
■ 35
-. 79 ^H
2406 8*2 1555
49
... 9
3133 8^1* 2029
18 ,..
H
2410 $-6 15 58
... 22
0
3134 8*5 2029
10 ...
^^M
2437 9"0 J6 6
14 ...
... 132
3152 6 '8" 2034
14 -
^M
2442 8-6 16 7
84 ..
34 ..
3186 8-6 20 48
39 ".
^M
^^^^^^^^^^^^H
r
1
^^^■H
^■^^^H
^^^^1
^^^^H
r
nH
^^^^^H
■i
■^^1
60
Proper Motions of 11
56 Carriiigi
Oil Stars,
Lxvia r, J
ZOKB 7'-
-corUinued.
m
Omt,
MAg.
A^x.
Proper
Unit
Apptoz. Frop«r Motioot. 1
K-A. Unit " OOI. 1
1900,
ft.A.
ir.p.D,
)90o. E.A.
K.P.0. 1
h m
+
+ -
h m +
-
+
-
3189
57*
2050
55 *-
... 29
3527 8-5
2257 22
...
.*.
7
3^95
9*a
2053
... 4
25 ...
3552 8-1
23 7 3«
...
25
3225
S'5
31 5
27
2
3564 9-2
23 11 ...
49
It
3266
7-8-
21 23
49 •
... ICX>
3574 9"o
23 13 43
...
11
5*83
80
2128
10 ...
11 ...
357^ 9t)
23 14 31
...
.«
5
3291
8*6
2t 30
22 ...
2 ...
3575 87
23 14 "
53
34
3301
88
21 32
... 10
2 ...
3584 8.-S
23 16 27
...
...
34
3323
9-0
2142
... 14
39 *-
3625 90
2331 ••
14
16
3343
85
2149
22 ...
... 9
3629 77*
2333 18
7
33^3
87
21 55
0 ..»
2 ...
3639 9*0
2337 14
2
33S7
7 '5
22 2
,.. 120
27 ...
3641 85
2337 -
4
14
33S9
8'o
22 2
" <33
9 ...
3652 8 '2
2341 ...
4
...
16
3408
77
22 9
49 ".
... 27
3659 8*8
2344 157
...
7
...
3433
9'2
22 21
43 ••
9 ...
3662 8*5
2345 '8
...
...
2
3437
9-0
22 22
184 ...
... 36
3673 9*0
2347 22
...
7
3490
8-0
2244
31 ...
... 14
3681 6-6*
23 52 49
2S5
3502
S'o*
2248
S3 ".
... 36
ZON
3700 7*J
B 8'.
23 58 .^^
4
...
i
24
9'5
014
49 ."
... 4
338 9"o
2 21 0
20
.. ^
76
6V
032
.-. 100
... 91
346 8^4
2 23 20
...
...
•.J
83
8*6*
035
... 9
16 ...
367 9'4
233 4
...
0
..^•
92
9-2
040
60 „.
... 29
3«7 8-6
240 9
...
...
2m ^
9«
7-6*
042
29
... 4
392 8-S
241 60
...
20
t.,^ j
130
7*5
053
9 ".
... 9
429 5-9»
256 ...
75
...
136
8^5*
OS5
-. 17s
66 ...
453 7'3'
3 7 20
...
2
.- -
141
8*6
055
... 60
... '3 1
474 8 '4
318 ...
16
...
1 -^
144
7r
056
20 ...
... 13
4S0 9^3
321 16
.•»
...
2^Bm
161
8*6*
" 3
24 ...
... 1 1
4S4 8*8
322 16
IS
.^ <
ao7
9^0
124
... 9
7 ...
5JI 7'9
336 16
...
I ^
219
&'S
I 30
40 ...
16 ...
526 9*0
341 ..
69
...
^^
229
87
134
36 ...
... 22
528 9-0
341 .>>
49
...
^^
^34
9-0
136
4 ".
15 ..
539 7*8
3 45 80
67
. —
245
8-6
138
20 ...
16 ... 1
543 7*8
346 ..,
24
33
. --
256
7*2*
t 44
44 ."
... 4
577 7 '3^
420
...
...
ja
272
8-9
I 49
4 ...
... 7
581 8-3
4 3 33
»wm
20
. — -
277
9'o
152
9 ...
... 20
584 7*9
4 4 t6
...
»5
282
8-9
I 54
44 ^^
... 31
621 8*8
420 ...
4
...
^A
^m 320
8-8
2 15
0 ...
... 4
659 8-9
4 37 33
...
•»«
♦ «
^^^
9-0
2 IS
49 ...
... 67
665 8-5
4 39 .^
9
n
.-•
^^^^
9'o
■
2 19
64 „,
24 .-.
675 5*3*
442 ...
16
■
■
4^
(^^^^^Bi^^l
^0% 1907, Proper Motions qJ
1186 CarringtQn
Stars. 61 ^H
Zone 8'-
-continued.
H
▲pprox.
Proper Motions.
Untt'-ooi.
<^- «... *rr
Proper Motions. ^^|
1900.
a.A. fr.p.D.
"*^ i9«>.
K.A. N.P.I>. ^H
h m
+
- + -
h m
^H
6$i S*4
444
.«.
4 -^ 9
1421 9*0 9 37
... 20 ... ^H
68s 9':^
4 47
9
... 125
1430 9 3 941
^H
730 9-a
4 59
40
0 ...
1485 9 '2 10 3
... ... 44 ^M
72J 8-7
5 0
4
... 4 .-
1491 91 10 5
... 13 ^H
750 «^
SH
102
... 134 ..
1525 8-6 10 15
- 40 27 ... ^M
762 s-^
Sao
t#»
4 ... 18
1536 7 '9 10 17
24 .. 9 ... ^H
790 s-s
S35
...
4 ... 31
155S 6-6* 1026
... 24 2 ... ^H
798 ax»
538
11
,.. 27 .,.
. 1577 8-4 1032
... 60 ... ^H
819 9*3
546
t6
... 9 .
1 1622 S'^ 10 51
... II 4 ^M
^M S'8
5 5<^
«*•
S3 347 »..
1637 S'2 10 57
... 206 62 . ■
S44 R*7
5 59
20
2 .*.
1652 8*2 II 3
- 40 7 ... ^M
854 9'o
6 4
0
... ... 35
i66;j 9-0 11 7
... 33 ^H
858 8*9
6 4
53
• 44
1671 8*3 11 II
..^ 40 27 ... ^H
892 9"Q
616
104
„. ... 127
1691 90 II JO
.. ... ^H
928 8*4
629
0
7
1698 8'o n 23
47 ^M
955 8-8
639
,,.
II 13 -
1707 6^i^ n 25
^M
976 9'o
648
24
.,, 9 ...
17*7 90 II 28
.^. 5 .- H
980 8-9
649
.*,
24 io ...
1719 9-0 n 29
4 ^M
1008 7 '8
7 3
«»«
II 88 ...
1721 9'o 11 29
'.- 133 73 ... B
1018 9'2
7 5
.«*
4-... 4
1728 90 ti 32
H
^ loaj 6-2'
7 6
9
... 26 ...
1732 90 II 34
- 44 ^M
B l(»4 9X>
7 8
.*«
24 ^1 ...
1741 8'5 11 36
40 7 ^M
1045 6'5*
7 16
,.*
9 n
1769 8'9 1150
... 7 ■
10T7 7-6*
728
.-,
9 0 ...
1772 8-8 n 53
2 ... ^H
1J0$ fx^
7 39
...
24 26 ...
1774 S-o n 53
... 71 50 ... ^H
itiS «7
750
,-t
9 26 ...
1784 6-4* II 55
-.r)75 32 ... ^1
"il 9*2
751
4 ... 13
1838 8-8 12 17
40 ... ^H
«I4J 8-j
7 54
20 ... 9
1845 S'S 1220
.> 24 ... 9 ^M
1J09 9*5
S22
9 7 ...
1866 8-1 12 30
^H
J*l9 8-9
S3I
44 .^. 11
1889 6"3* 1242
. 35 ^M
1261 76
843
...
4 ... 32
1915 9'2 1249
- 55 ^^1
!2ds S-6
844
...
20 7 ...
1936 7*3* 1*59
... 69 ... ^^1
lagi 7-9
853
«**
31 43 -
196S 6*3* 13 12
... ... ^H
J295 8'4
853
20
... 26 ...
1988 9*0 13 17
138 46 ... ^H
Ijoi 6*5*
856
..*
20 24 ...
1997 8-8 1320
... 4 ■
nu 87
9 '
.».
H 9 ■'
2025 8-5 13 28
... 4 ... ^H
ip5 90
9 6
20
... 24 ...
2061 85 r3 4i
29 ... .., ^^1
J3S« 90
9 M
20
... 460 ..
2064 9*0 13 42
9 '.. ^1
1165 9'>
919
24 16 ...
2073 8-9 1344
13 ^H
I3»i 4'6*
9^3
...
29 ... 2
2088 6-8* 1352
^H
'194 8'9
929
49 .. ^9
2JOS 9*2 13 58
... 44 0 ^H
r
p
1
[
^^^^^^^^^^^1
^H
~j^M
■
■^^H
62
n^r Motimis of ii%6 CarringUm Stars, Lxvm. T»
Zone 8" — continued.
CWT.
ii»*jpr-
1
tfnlt "oot.
proper Motlo&i.
Unit "*ooi.
A*ll.
00.
B.A. N.P.IK
RJl. N.P.D.
m
+
- -!- -
h m
+ ' + -
2135
S-8 M
10
16
2
2911 9*2 19 8
,., 36 18 ...
2 17 1
8-6 lA
^27
64 ... 22
2923 87 19 13
... 20 ... 29
2176
g-o M
^28
♦ ..
4 ... 3t
2934 8*3 1930
20 n
2188
7-1* H
^33
.,,
95 137 "^
2947 7 "9 ^924
67 .« .., 43
2194
87 M
^34
...
24 0 ...
2948 8'o 1924
20 ... ... 18
2200
8-8 14
35
..*
16 ... 2
2960 %'% 19 27
20 _ 5
220S
87 H
^3S
«».
36 ." 49
2962 8-0* 1929
11 ... ... 11
2230
8-9 M
^46
49
00
2969 8*3 1930
59 .« 87 ...
2252
8-6 1.1
t53
4
.« 42 .*-
2980 9'o 1936
0 ... 20 ...
2256
7-2* 14
^55
24 .. 27
2995 8-8 1944
... 20 14 ...
23<^3
8-9 i;
i 17
...
t6 ... 22
3031 77 1956
31 ... ... 70
2324
87 ij
► 26
...
36 ... 58
3049 8*6 20 3
44 ..- .. SE2
2327
7-8 15
27
4
.- ... 9J
3054 8*9 20 4
16 27
235^
7X>* .5
36
0
... *.. 34
30S6 8*6 20 16
16 ... .. mj
2358
8-S '5
*39
4
... 4 -*
30S7 7*4* 20 16
31 ... ... -•«
2361
q-Q 15
39
4
... 4 -
3140 6-9* 2033
47 ^ ^^
2392
8-4 15
51
..*
80 ... 74
3149 5 -6* 2035
31 ... ... :■*
2393
7'4 «5
5*
...
16 7 ...
3161 8-S 2039
0 ... ,.. a6
2421
80 U
» 3
29 ... 7
3162 9*0 2039
4 ... ... 9
2447
g-o i(
1 12
29 ... 86
3166 f'2* 2042
71 ... ... -4»
2458
8-2 le
» 18
29
..» 18 ...
3203 8*9 20 56
16 ... 18
2478
8'2 It
►25
24
4
3217 S'O 21 I
20 ... .^ 14
2505
9-2 le
>39
...
4 . . 33
3235 8-8 21 II
SI 3»
25S4
87 If
iSS
•»■
0 ... 24
3236 87 21 II
16 ... 5 -
2569
8-s I,
S
...
0 ... 13
3261 7^8 21 22
4 ...^... 3«
2568
67" 17
5
36
29
3263 7 '9 2123
24 ...' 7 ^"
2581
g-o ij
9
11 ... 38
3290 8*0 21 31
260 ... ... ^
2591
8-3 I?
^14
...
0 ... 69
3304 9'2 21 34
4 7
2629
8-6 17
29
20
29
3324 9-2 2143
36 .« ... 0
2641
8-8 t;
3«
36
20
3326 9'2 21 43
36 7
2725
8-9 IS
2
0
... ... 94
3383 9*2 22 2
20 ti
2726
87 js
S 3
24
... 9 -
3426 8*9 22 17
9 ^
2730
8-9 IS
I S
29
32
' 3440 7*0* 22 24
84 ... ... 7^
27S7
8-s i{
f'S
44
3>
3459 8'5 2229
16 ... 2 -*•
2768
87 18
1 19
36
>.. 5 "-
3472 S-S 2237
... 4 2 •-
277S
7-5* 'f
S22
33
18
34S3 77 2243
0 ... 2 --'
2S08
9-2 iS
1 36
24
... 40 -*■
3486 80 2243
36 ^
2840
9-2 18
us
0
... 14 . .
3489 9'0 2244
-.^ 24 7 '*'
2854
g'l iS
50
4
18
3503 9'5 2248
... 4 0 •*
2863
8-2 t8
I 54
9
... 27 ...
3504 8-9 2249
... b ... 5
2868
9-0 l«
55
■
16
■
a ...
3507 9-0 2250
.., 20 27 *•'
1 907. BtjPif Motions of
1 186 Carrtngton
Stars,
fl
ZONS 8**=
-continued.
t
^
Appfox.
Proper
tfalt
Moilotis^
J900.
proper Arotlona. ^^^H
tJnH "coi. ^^^H
1900.
a.A.
K.P.D.
E,A.
^^H
h m
+ -
+ -
h m
+ -
+ ' ^^1
l-o
2254
36 ..
9 "
3579 8*8 23 16
II ...
14 ... ^^H
^'S
23 %
.*. II
27 .„
35S0 8^1 23 16
II ...
7 '.* ^H
57
n 8
20 ...
18 .
3587 8*5 2318
0 ...
^H
\'l
33 9
109 ...
4 -..
3637 8*3 2337
••, 16
^^^1
V^
23 ro
95 -..
... 90
3668 9'o 2346
124 ...
... 7 ^H
^
2311
5» .-
... 9
ZON
3674 8-0 2347
K9-.
20 ...
^^^1
14
811
5 ••
7
2029 8*9 13 30
9 ...
^1
>'3
8 It
17 ...
9 ...
2039 8-9 1332
... 5
^^1
Kio
833
.,. 21
15 ...
2050 87 1337
... 69
^H
1-3
835
,-. 21
43- ■•'
2065 7 '2* 1342
5 ."
^^^1
5'6
912
9 .*^
... 9
2115 9'2 14 I
... 26
^^H
^5
9 20
'- 5
«3
2169 9*0 14 25
0
^^^1
>T0
924
17 ...
7 ...
2197 8'5 1435
5 -'
^^H
J'l*
946
... 5
... 7
2199 8-5 1435
12 ...
^^M
1*4
94s
... 64
56 ...
2214 S»9 1440
... 21
- 13 ^H
l7*
'033
21 ..,
...• ri
2312 87 15 2J
17 ...
^H
II x>
1038
5 ."
4 ... '
2326 8*6 15 a6
s ..^
^^1
J'9
1045
... 21
7 .*.
2348 6*5* 1534
.-* J99
^H
Is
1046
21 ,.,
... 45
235Q 83 1535
... 190
^^1
t'8
10 50
... 38
17 ...
2370 7*0* 1542
... 47
^H
J-6
II 0
... 64
... 22
2415 87 16 I
.., 9
^H
i'o
"33
,-, 3»
5 -
2438 7*6* 16 7
... 31
^^M
B*4
12 It
5 ..
10 ,..
2452 8*5 16 15
... 17
^H
B3
12 II
0 ...
■ - 9
24S9 8'5 16 29
21 ...
^^^1
J^O
12 16
-. 43
9 ...
2644 S's 1733
21 ...
^H
r4'
12 3J
... Ill
9
2695 8^9 17 S3
... 5
^H
7^
1246
.., 12
23 ...
2716 90 iS 0
0 .,
^H
9X3
1
U30
I
". 73
32
J
64 ^rof. Hale, Opportunities for Astronomical LXViu, r,
t
SOME OPPORTUNITIES FOR ASTRONOMICAL WORK
WITH INEXPENSIVE APPARATUS.
A Lecture delivered by Profesaor George K Hale^ Director of the
Mount Wd/ion JSolar Observatory of the Carnegie In^ituti&n
of Woffhington^ at tJw ItfyycU Astronomical iiodety^ Burlington
Houite, London f W., on Wednesday evefiing^ June 26, 1907.
(Plate 5,)
I bftve sometimes hearil it said tliat the great cost of modem
obaervutories tends to discourage workers with j^mdl instrumeota —
observers who are uo less ititereated in the pursuit of astronomical
research than the ustroiiumera in the large iustitutiotif:. It seems
to me that if there is any serious discouragement, due to this cause,
of men who are en^ag;ed in uriginal reseiirch with smull telescopes
imd inex|»en8ive apparatus, it is a question whether large obsevva-
torierf should be established. For at any period in the progress of
obaervational astronomy there are two most important subjects
for consideration. One relates to tbe accomplishment of a great
amount of routine observation and the discussion of reault^, and
the other relates to the introduction of new ideas and to the
beginnings of the new methoila which will make the astronomy of
tbe future. I think we will all admit that the introductioo of
new ideas ia quite as important as the prosecution of routine r^
search • and thai if any cause whatsoever tends to discourage the
men from whom the new ideas might be likely to proceed, that
cause of discouragement should be set aside if possible. And
therefore 1 say, with all seriousness, that it is a fair queetion
wliether large observatories, with [lowerfut instrumental equipment^
should be established if they tend to keep back the man who in
pursuing the subject with less expensive apfdiances, and is intio-
ducing, through his careful consideration of the possibilities of
research, the new methods which in the [iroceas of time will take
the place of the old ones. I think it can be shown, however, that
tVie large observatories should be a help rather than a hindmuce^
at least by suggesting new possibilities of research, in which most
valuable resnlts can be obtained by simple meaos.
I am talking to-night, in purpose at least, to the amateur ; 1
my detinition of the amateur is perhaps a broader one than
generally accepted. According to my view, the amateur is
man who works in tistronomy because he cannot help it, beeai
he would rather do such work than anything else in the world,
and who therefore cares little for hampering traditions or for
difhcuities of any kind, Tbe ** amateur,'* then, is the person to
wlioin 1 wish to address my remarks, whether he be connected
with a small observatory in the capacity of profes«ional astrououier,
or working by hiuiself with very simple instrumental means. B'
in speaking to the amateur I do not wish to deal with work tl
shaU be fiatref&ctory merely from the standpoint of instruction of
»OT. 1907. Work with Ineotpeimm Apparatus,
«s
Amaaement. That ii^* not my purp«»se. If it is poaaible to carry
IOD research by simple means that ehall really be important and
uaeful, it is my hope to |>uint out some such possibiHties. But I
do not wish to speak of any work except that of the hrst class,
fjior to recommend that any investigations should be undertaken
^'ith simple instruments that are not quite as iinporUnt as other
investigations which can be better undertaken with more exfjensive
instruments.
The problem then becomes one of this character — to determine
the relative advantages of large and small telescopes for difTerent
daaaes of research, and the po^tsibility of constructing really
powerful instruments at moderate expense* I caniiut pret*?nd to
US8 all phases of this lar^^e problem ; I shall mention only a
few of them, and approach it from a single direction. But before
ing up the detads of this discussion, perhaps I may be permitled
to say that the conception that is sometimes formed of the newer
observatories, the idea that vast sums of money are expended,
perha|)s without the fuUe.st sense of economy^ is not always well-
foumled, » For 1 am quite sure that if you would vi^it us (to take
a sin^^le concrete case) m Califtrrnii), you would agree that we have
nsidered the economical side of the question, that we have
rhaps in some instances gone almost too far in our desire to save
loney for instruments of research, and to economise in certain
tions where money can be saved. For example, yon would
ft;i4 that our offices, our building's, are of the simplest and least
expensive character, while out instruments and machinery are as
effective as we can make them. The great expense of such an
baervtttory as the Solar Observat*»ry on Blount Wilson does not
jHind in large degree on the cost of the instruments used for
ivestigations of the Sun, but in surmounting the difficulties en-
untered in utilising a mountain site, deprived of the ordinary
of transportation, and in the construction of large equatorial
^Wftctiug telescopes for stellar work, wiiich cannot be built cheaply
if Aey are to be really etficient.
I wish now to come to the question before us, and to illustrate
1 acme uf the advantages and some of the disadvantages of large and
I amall instruments. Ptrhaps you will permit me, in showing the
^^■jirst slide on the screen^ to say that 1 have some right to undertake
^n discussion of this sort, because I have viewed the subject from
Nthe stamJ point of the man using small and inexpensive af>paratus.
In my first spectroscopic work, which was done in a room in my
plber^s bouse, the instruments were of the simplest character, and
argely of ray own c4>nstruction. Later, a small building was
constructed for a concave grating of 10 feet focal length, and the
iparatTis, although powerful, was not expensive. Subsequently
tower and dome were added, and a 1 2-inch telescope was erected
!or photographic work upon the Sun. After the preliminary ex-
penmen ts had been completed, and the spectroheliograpb had
begun to take form, the possibility that its results could be greatly
iroved through the use of a hrger telescope suggested ilftfeVi,aii4
s
66
Prof, Rale, Opporiuniiies for Asiivrwmical LXViiL l^
for this reason I made many efforts to acquire a lar^e. instrument
for tbest? solar in vest i gat ions. The result^ through the generositfj
of Mr, Yerkes, wiis the 40-inch Yerkea telescope, which proved
be very useful far the exterision of the spectroheliograph wark.1
The next slide shows the instrumetit, which you will see is a lai^
and expensive machine. The question, then, comes right down
this f joint : Whafr are the advantages of such a telescope compared"
with, let us say, a 6 -inch equatorial or poseibly a 4- inch equatorial 1
la it possible with a 6-inch eqnatoriai to do work comparable in
importance with the work that can be done with a 40 -inch
equatorial?
The next slide will ahow that there wtis an advantage in
passing from the Kenwood 12-inch to the Yerkes 4a4nch, at least
for the ph<^towraphy of the Sun. Very minute details of the
flocculi were brought out which had not previously been known.
Bat it may easily be shown that the advantages of the 40-inch
telescope for most classes nf solar work are due more particularly
to its great focal length than tu its large aperture,*
Let us take another il lustra Lion, Here we have a picture of
the Moon made by Professor Ritchey with the 1 2-iuch Kenwood
telescope. You will notice that near the terminator is the crater
Tbeophilns, xvhich you will see again in the next slide o^ phot«»-
graphed with the 40-inch telescope. This photograph taken by
Proft^ssor Kitchey is probably as gfjod a photograph of the Moon's
surf II CO as has yet been made, and in this case the advantage of
the 4a-inch telescope is apparent. + But if we take another case,
as illustrated in the next slide, it becomes obvious enough that for
certain classes of work the Yerkes telescope is not well suited,
Hei*o is a picture made with the 40-inch of the Andromeda Nebula.
You see how little it shows, since a long-focus telescope, unless of
very great aperture, i^ not well adapted for the photography of
faint iiebulie. When we compare this picture with the next one,
made by Profcsi^or Ritchey, w itb the 24oot refl*^ctor (of 8 feet focal
length), we appreciate immediately that the 40-inch, in spiti- of its
great advantages for certain classes of work, is wholly unadapted
for other investigations. As you know, a refractor of much
smaller aperture and of shorter focal letigth would also give a
pbntc^grapb of the Andromeda Nebula far superior to anything
that could he taken with the 40-inch,
If we look at the next slide, which shows Professor Barnard's
lO'inch Bruco telescope when it was mounted on Mount Wilson,
where he was using it to photograph the Milky Way, you will see
an instrument that is very small and inexpensive as compared with
the Yerkes telescope. It has a to-inch Brashear lens of 50 inches
* So far at resolving power is ooacertied, &11 aperture of S inchoi would
bfl feulficieiil to permit the tanallest kaowu details of the tlocculi to be
photographed.
t Here, a^hiu, the full visnnl Tee^jlviog power h not utOiaed, but th«
groat ai»ertnre is of AdvantAge in permittitig the large image to be photo^
grmphm with yery short exposures.
Nov. 1907* IVoi'k with Inexpensive Apparatus,
67
foea! length and certain smaller cameras attached to the side of the
uJ '\ With such an instrument as this, superb photographs of
tfi' Milky Way, like the one illustrated in the next slide, can be
taken, which are indiejjen sable for investigations on the distribution
of slara io this part of ihe heavens. Excellent work can also be
done with a much tnialler lens, provided with a very simple
mounting.* A Hne instance of systematic work with a portrait-
lens i» afforded by Mr. Franklin- Adams's photographic map of the
northern and southern heavens.
It is hardly necessary to recall the fact that the 40-inch could
not do this work at all. If we attempt^^il to photograph the Milky
Way with it, we might get a very small region on a very great
-acale, but to give ua any notion a» to the general distribution of
atiir:* in the Milky Way the 40 -inch would be a total failure.
However, if it were a question of studying some star cluster like
the one shown in this slitie, which would occupy a very small
region indeed of the Milky Way, the 40-inch wouid enable us to
pick out the separate stars, to study tlieir individual phenomena,
their changes in light and position, while such work could not Ije
done on photographs taken with a portrait- lens.
I have shown these miscellaneous illustrations for the purpoae
of emphasising, what is perfectly well known to all of you, that
«ach instrument has its particular fields of work, in which it can
.lecomplish, or permit to be accomplislied, various investigations
which are not within the reach of other kinds of telescopes. But
I now wish to discuss the question somewhat more specifically,
and in doing so 1 shall confine myself almost entirely to observe-
" !(> of the Sun, although one might attack the subject from many
Mthcr directions. The first point is this. Suppose one has a small
telescope of 4 inches or 6 incbes aperture and wishes to observe
the Sun with it; and let us assume at the outset that he has no
attachments whatever in the form of spectroscopes, but that he
wiabes simply to make direct observations of the Sun : Is there
work for such an instrument at the present timel If you will
examine the literature of thf» sulg'ect you may perhaps be surprised
ill find that many years have elapsed since very careful and
extensive investigations have been made similar to those of Ltmgley,
which mny be almost forgotten by many a^^tronomer^, but certainly
are not forgotten by those of us who follow the Sun and arw
accTiatome<l to the appearance of the siiots when the definition is
good. The next slide shows the well-known drawing of Langley's
typical sun-^pot. You will remember, if you have systematically
observed the Hun, that every time the conditions become extremely
)7o<^d, the structure of sun-spots more and more closely resembles
tliJH drawing. This is a typical drawing; it doe^ not represent
any particular spot ; it brings together observations of various
; but in general the details of a suu-spot look very much
• Profetsor B&rnard has illaMtnited in the Awtraphtisival Journal some
of tbe idmirable results be hm liimtelf obtaiued with a choAp '' Uutem lent '*
belottginS to an ordinary atereoptiix^a.
6S Prof. Hale, Opportunities for Adronomical LXVUi. i,
indeftd like that drawing when tbe ilefinitioii is good enougli to
show them properly* Thia subject has been greatly neglected far
a long timt*, and it would well repay obgervera with large or small
instruments to observe sun-spots, and to study many of the details
of their etrnctnre which still remain obscure and difficult to under-
stand.* Of course the question of the resuming power of the
instrument must then be considered, A 4-inch telescope, ca[»able
of separating objects one second of utc apart, would not do for the
very finest details in a sun-spot According to I^ngley, the
penumbral hlitments sometimes exhibit structure considerably
smaller than such a telescope would iihow; but a lo-ineh or 12-iDch
telescope would ^how everything thai has ever bei^n recorded in a
sun-spot, and there are many instruments of that size available for
auch observations.! Even a much smaller telescope, if carefully
and systematically used, would contribute* largely to our knowledge
of Bun-apota and of the structure of the solar surface. One might
enlarge upon this subject, but time is hardly sufficient to permit
me to do so.
Now let us consider the case of the prominences. If we bare
available a small J^pectroscope like that admirable little instrametit
designed by Everahed, or the one made by Thurp,+ or a still
simpler home-made instrtiment, and attach i*uch a spectroscope to
a 4-ineb or 6-inch telescope, we have an almost ideal equipment
for th« observation of the solar |>rominence8. As a matter of fact,
an instrument like the 40-inch is wholly unsuited for work of this
kitid. You will easily see why. If you wish in observe the eniiie
prominence, it.s image in the focal plane of the 40- inch telescope
is usually so large that the slit cauriot be opened wide enough to
include the prominence without admitting too much light of the
sky, Thereft^re, for a study of the general characteristics of
prominenceej the small instrument has a great advantage over the
large one. It was practically out of the question with tbe 40-tnch
for ut? to do systematic visual work on prominences. When the
eonditious were i)eculiarly tine we could study the structure of
certain prominences, Qud I never saw anything more remarkable
than such details when they came out under the best seeing. But
with the spectroscope available, and under ordinary atmospheric
conditions, we could not make records of the general form and
distribution of prominences that woidd compare in value with the
records obtainable with small telescopes,
• For t]umple» it would be of great iutcreat to study the utructuro of
the umbra, as m^-n through a minute piu-hole in the focal plane of a positive
Qj«picoe, as Dawes did niHDy yi-ars Hgo.
t It must uot be forgotten that photofjraphy is still &r behind vii^ual
obsetyatioBB iu revealing the minute strortur* of 8un -spots. It can hardly
be d<mbted, bowevvr, that if only the umlim and penumbra were permitted
to fall ou ttif piste, aud the exposuri} properly rc^dated, new aua mluable
re»iultft woidd be ohtiiint'd. The anmtenr will readily find uiacy opportunitiea
for work in this field*
X I wixh to call special attentiou to the solar Kpectroscopea and other
inexpensive iufltrumeiit» mtide by Mr. Thomas Thorp of Manchester. 0ns of
thesef a polAfiBing helioscope} bus dont i:iLc«Ueut serVice on Mocmt Wilson.
Nov. 1907. JVork with Inexpensive Apparcttas,
69
It has reniaiaed for certain amateurs here in England very
recentty to show that objects upon the surface of the Sun which
escaped many of iho earlier s^lar observers can be observed at any
time when the conditions are favourable with a very small instru-
ment indeed. For example, Mr, Buss and Captain Daunt, and^
1 believe^ some others, have been observing the Sun with such
ioatruments, and have been able to see upon the disk dark regions
iu which the Dg line h strengthened, which I think have never
b«eD recorded before iu a systematic way, Obaervationa of the
dark D^ line upon the fatie of the Sun were formerly mentioned
as unusual and rather remarkable phenomena, and certainly, m far
as I have ever seen in the literature of the subject, the dark
•I fiocculi were never recognised upon the Sun by the earlier
tpists; but they are seen, at times at leaf«t, l»y those
gtutlijmen to whom I have referred. This I can make quite
certain from my own knowledge, because on one occasion, when
Mr, Bu*J!* had described one of the very peculiar dark hydrogen
flocculi — flocculi of this type appear very much darker than the
ordinary uoea photographed daily with the spectroheliograph — I
looked up our photographs of that date, and there was the image
recorded by the spectrohelio^^'raph precisely as it had been described.
So that if I had previously been a little doubtful as to the
poastbtiity of seeing these objects with such au equipment, I gave
op all doubt after having made that comparison;* One might say
that it would hardly be practicable to observe such phenomena in
any satisfactory way with a large telescope. A small one is very
much more advantageous for work of this kind« As soon as
possible we are going to set up a small equatorial for the purpose
of seeing these objects and cum pairing them with our photographs,
after having derived the knowledge of the possibility of observing
lliem from the work done by these men in England* lint we will
Dot undertake systematic work in this field, as I hope the valuable
observations now in progress here will be continued. No records
are made with the spectroheliogmph of the D3 image of the Sun
at present We have tried experiments, but so far they have not
been successful We ou^ht to be able to photograph the Sun
ikroogh the Dg line, but we have not done it yet. The only
ejcltting records are those made by the members of the British
Aalronomical Association. These observations should be made in
conjunction with other solar observations, as in fact is being done
at the present time. The characteristics of the hydrogen lines are
being ubserved at the same time that these D^ images are being
ncoided, so that any relationship between the two may be dis-
corered* I cannot dwell upon this very interesting subject.
There is a great opportunity here for further work of high
ijnporiance,
I must now pass to the question of sun-spot spectra. I need
Imrdlj tell those who are present that observations of sun-spot
* As I undprstind thci matter, only the move c<?nsplcuous datk &oce\)l\.
can be obierved Wtfuil/jv
70 ^^of. Halt, OppoTttinities for Adronomiml LXVUl. I,
spectra made viaually are BometimeB far more valuable than those
which can be maiie by photograijhic methods. Take, for example,
the lines in the greeo region f>f the apectruni. This photograph
will suffice to show them. Hsr© is the b group in the spectrum
of a Bun-spot ami alao in the spectrum of the photosphere* W©
see in the spot a large number oi Hut* lines, long ago observed by
Young ami Maunder, iuid now being studied with great care. All
of these hne lines shown by a powerful instrument photographic
cally can bti seen visually with a small 8pectl08cop^? attached to a
6-inch or jirobably a 4-inch telescope, an«J many other phenomena
which cannot be photographed at all can be seen with a similar
equipment. There is a certem advantage in observing such spectra
with a larger telescope, provided that the spot under consideration
is a small one. Cut if the ^pot is a fairly large one (and hitherto
no one has bad time to observe the spectra of small ^ptji^ syste^
matically), I think there is no advantage whatever in having a
large telescope to form the image i»f tlie Sun on the slit of the
spectroscope ; it is merely a question uf having an image of
moderate dimensions upon the sHt, and after that the spectrijscope
does tbe work. So that, so far as the spots actually under obeerva-
tion are concerned, a small telescope is quite as satisfactory as a
large one for visual work on tlieir spectra,
I will return in a moment to the question of the relative ad-
vantages of the photographic and the visual method of observing
spot spectra ; but I want to point out in paasing tliat the 40- inch
telescope has certain very definite advantages for work on the Sun,
If one wishes to observe the spectrum of the chromosphere, for
example, the advantages of irreat focal length immediately become
apparent. The w^idth •>! the spectrttacope slit is essentially constant j
the clirontospherie arc must have a certain linear width on the slit
in order to permit the base of the chromosphere to l>e observed;
and consequently the 8[»ectrum ot the chromosphere, as se«n with
the 40-incli telescope, is a remarkable sight, showing thousands of
Hliea which do not come out wnth a smuU focal image of the Sun,
Here we have, then, an iHustration of the advantages for
certain purja^^es of considerable focal length. 1 think it is not so
much a question of the telescope's aperture here, because we must
not forget, in thinking of tbe optics of tliis question, that the
brigbtnei^s of the spectrum (for con*«tant purity) is quite independ-
ent of the linear or the angular aperture of the object-gIa«s that
forms the image of the Sun on the slit of the spectiosooi^,*
Perhaps it is well to V>ear in mind that the brightest solar spectrum
one can get is obtained without any telescope whatevef to form an
* Wben th*3 focal length of the collimator is limited (as is naually the
CAM tn a spectioflcop attached to an eqtiatnriBl te!eS4 ops), no jnct^wss in tho
angular B per turo ot tlit- telescope penitits the liii^iir a|ii^rtiire of the BpeotfO'
scope, and con-^t^queutly the reflnlviu^? )>ovier aad the bHuhtnesft of the
spectrum, to be iucieasea up to a limit BxckI ly the sue nf the grating avail-
ahle. With a co?lodtAt teleaco|M% however^ the same condilioijs do not
obtain, since the aperture of tb« Rpectms^jope o*n bo increased by merely
mmwmug the focaA length of the co\uvnat«>T*
1907* Work with Ine^penMve Apparatus,
7^
image oq the slit, but merely with a coll inm tor of suitable angular
aperture. But a large solar image is freqtieiitlj advant^ageous, and
an equatorial telescope of great focul length is necessarily an
expensive instrument. The aperture in the case Just mentioned
18 less important than the focal length ; bnt even if the aperture
were only 6 inches and the focal length unchanged, the tuhe must
•till be 64 feet long, and the mounting would coAt no less than
the mounting of the Yerkes telescojie. So if we wish to have an
tostrument of great focal length, and yet keep down the expense
to a reasonable figure^ we must use a telescope of a (iifferent type.
There are mntiy otlier reasons why we ehould wish to use a fixed
telescope for certain kinds of srdiir w^ork, although I should he the
last to admit that the 40-inch telescope is not an almost perfectly
iatisfaeiory machine of its kind. It has, as we have seen, in con*
veniences and diead vantages for some classes of work, but in otlier
fialda ite superior qualities become m4>ro and more striking day
afler day ^ the observer learns to appreciate them. I only wish
we could atlord to have such a telescope (or even a much smaller
equatorial refractor) on Mount Wilson, as it would be of great
Mprvice for many purposes.
^B Now let us consider some of the possibilities of the fixe^l tele*
itIdop© ; and let me show, for purposes of comparison, \k picture on
the screen of the 8now teleafioj)© which is now employed at Mount
Wilson. Here is a crrlostat, with mirror 30 inches in diameter.
After passing to a second mirror the light is reflected to a concave
mirror uf 60 feet focal length, which sends it back and forms a
large image of the Sun within a laboratory. This is a very simple
iBatniment indeed. The hrst ccelostat we set up on Mount Wilson
^^pm a small one used by the Yerkes Observatory jtarty at the
^Hlipee of J 900, and it wa^ not originally arranged for work of
^^sis kind ; so we simply built a wooilen support for a second
mirror, and with the aid of a 6-inch objective of 60 feet focal
B^h we ma^le a telescope which served admirably for our solar
[»rk until this one was put up on the mountain.
The next photograph shows the spectroj^niph used with the
E>w telescope. It is of the Littrow or au to- colli matin l^' typi
slit and [ikte-holder at one eml of a Ion;? tube and lens and
:il the other. Light from the sular image, after passing
the sUt, falls on the lens f S feet (its focal length) distant.
ys, thus rendered parallel, then strike the grating and are
irned to the len», which forms an image of the spectrum on the
ot-'^gniphic plate, just above the slit (the grating being tipped
ck a little). Such an outfit (fixed telescope and spectrograph)
^an extremely simple thing to build in inexpensive form, Oeltv
statSf for example, are common nowadays for eclipse work. One
iQtgbt have a ctsloatat with a mirror only 6 inches in diameter and
% seeond mirror about 4 incites in diameter, and then perhaps a
telescope leua of 4 inches aperture and 40 feet focal lejjgth. 8uch
an instriinient as that, which could be very cheaply built mde^»
would give a Inrge soUr image, adapted for many kinds of solar ^otk.
72 Prof. Male, OpportufiUies for Astronomical Lxvra.
Let me show you in the next slide how we build our spectro-
graphs in actual practice. This is the most powerful spectrograph
in use in the laboratories of the Solar Observatory. Here h a
little slit I bought from Hilger, the last time I was in London, for
a few ahiilinga. All other parts of the spectrograph, except a lena
and grating, are of wood, built in a few hours by a caipenter*
The wooden support for slit and plate-holder stand on a concrete
pier, and close an opening through a parti don which forms one
end of a narrow dark room. Eighteen feet from the slit, within
the dark room, is another (concrete pier. A sliding wooden support,
carrying a lens, and a simple wooden moimting for the grating,
stand on this pier, and complete the spectro^'raph. Owing to the
Acarcity of gratingn, we are fort una to in being able to use one
loaned by Professor Ames, of Johns Hopklna University. If we
had no reflecting grating, we could buy a replica very cheaply from
Thorp, or Wallace, or Ives,! which would give quite as good
photographs as we obtain now (though the exposures would be
longer, because of the smaller aperture). They might even be
better, because our photographs of s|)ot-spectra (made with the
similar spectrograph of the Snow^ telescope) are not what they
ought to be, or what I hope they will Bobaequently become- They
wouhl not stand comparison for a moment^ so far as perf**ctioD
of definition is concerned, with those magnificent photograplis of
the solar spectrum made by Mr. Higga in tlie centre of Liverpool,
under conditions which would ordinarily be called very bad even
for a crowded city, with tram-cars cousiantly passing in front ui
the house. With a spectragraph of his own construction (except
the grating), Higgs made the fineist plioto^TJiphs of the solar
spectrum ever produced ; superior, as Rowland would have said,
to the best photographs made by himself at the Johns Hopkins
University. It is obvious that something other than an expensive
instmment is required to make a good photograph- Mr. Higgs has
the ability, which others may acquire, to obtain superb definition
and exquisite photogra[>hs with very simple apparatus in<leed.
With a spectrograph of i inch aperture and lo feet focal lengthp
used with a fixed telescope of 4 inches aperture and 40 feet focal
length, one would be in a position to make good photographs of
the spectra of sun-spots.
What, then, are the relative advantages of visual and of photo-
graphic worki The next slide shows some photographs. The
upper one is the spectrum of the 8un and thi^ lower one is that of
a spot. These photo;j;rapbs are better than visual observations for
the determination uf the wave-lengths of unknown line^ in spot
apectra, sintply because you ciin measure the position of a line OD
* Except the pkto- bolder, which la of a ntandard niJike.
t As these are not reflecting gratings, the auto-eoUuiiating epectrograpb
mi^ht iu thiacasB give way to uu© iu which a *eiKarati* c»miem lens ia used.
With the angular aperture here cuisideied, well-made >*iinple leii»ea would
obviously serve |>crfoctly wt'll fur collimator and r^arnera, the pbotograpbk
phte litftng aet at the angle required to bring a su^cietit range of nijectram
I Ihi
It
iov, 1907, Work mUh IinxpensivB Apj^anUms, 73
pliotograph to much better advantage than you can do it
lUaliy at the telescope. They are also better for tlie d e terra ina-
_ 11 of the relative ki tensities of the lines, esj^cciftlly the fainter
ones. But when you have said that, you have »aid almost every-
thing that can be said for the photo^^raphs, and you have left out
nocount toaiiy of the very important advantages of visual ob-
Tvation. Theae photographs represent the integrated spot
gpectrum, as it were. Even with a la r|^e image of the spot on the
alit of the spectrograph (and you realise here that the principal
poiat of our great focal length is to have a large image of the spot
on the slit), we catjnot as y«t satisfactorily record minute dilTerencea
iu the spectrum corresponding to small details in the »pot. If we
wiah to study these very important diti'erences in the spot, we must
do BO, at present at any rate, by visual means. For example, Mr.
Newall, your President, told me the other day that he had found
the spectnim of the outer edge of the |:ien umbra u( a spot to have
;he same characteristic strengthening of the lines thai is observed
in the umbra, which is a very dilticult thing to explain from the
atandftoiut of the hypothesis I have been favourin;^ of late, viz.
that the principal cause of the change of the relative inten cities of
lines in a spot is reduced temi_>emture of the vapours in the umbra.
I knew nothing about that; I had not been observing the spot
•pectnim visually for many years, and in our photogra[>h3 this
phenomenon is not recorded. You see, then, m such a c^ise the
decided advantage of visual observationg. 1 might go on to speak
other advant^ea. For i^xamph/, suppose th^re were a sudden
ange in the spectrum due to an eruption ; the chancer? that one
^OTild get a photograph just at that time are small, whereas visual
ivlr^rvations neee^sarily occupy a considerable period of tinje, during
which eruptions might be detected.* Even a few results might be
^of extreme importance, and would probably be wholly missed in
^Hiic photographs. Again, the extension of certain lint^s outside of
^^Bie spot u^ton the photo.««phfre is not recorded at ait in our
^Hlhutograplis, because of the method we usually employ of excluding
^^%om the plate all light except that whifh comes from the umbra,
and perhaps part of the penumbra. We ordinarily get no trace of
these extensions, but perbaj)8 the conclusions drawn from the study
of such phenomena may have much to do with the final views as
to the nature of the spots themselves.
To mention only one other thing, the reversals of spot lines which
have been seen by some observers have not been photographed with
our pre*ef»t apparatus. Whether they can be photographed in the
future remains Ui be seen. But, without going into this subject of
i»pot spectra any more in detail, you will certainly agree that the
visual observer has a superb opportunity, which the photographic
Qbierver cannot by any (.lossibilily take away from him.
* It ta, of coQr«e, desinibli* to titke phniographs as ofct'ii us possible, sinoe a
I^MltogHiybtc r^conl of « miirked rhmige in tb« sp^ctntm, if fortmi&telY
^liinidi m%y be mticb more vjiluiiblt.* uum tJie reaults of a few v\s\\&\ o^«
r
74 Prof, Male, OppoTtuniiies for Astronomical LXVIII.
I eow wish to apeak rather more particularly of another
phenoiiieiion mentioned her«3 the other night, which is peculiarly
adapted for investigation with a .small solar inmge. I refer to tht>
cJiiferences betw^^en the spectrum of the centra of the Sun and the ■
spectrum of tlio Sun^s disk near the hmb, as shown in the next
p ho t< 'graph. Here is the spectrum of the ceiit»*c of the Sun, and
here i« the spectrum of the Sun at a point a short distance inside of
the limb. You will see at once the remarkable chiinges that tak»
place. The broad H, and Kj lines (or bands) ai"e greatly reduced
in width; and the same thing occurs. I think, in the case of all linejj
that are accompanied by win^s. In thi» region of the ultra-violet
many of these lines h»ive wing??, which are lost or greatly reduced
near the ed^e of the Sun. This causes a remarkable change in thu
appea ranee of the spectrum. Several other curious thingis occur.
Not only do these wings change in intewRity very much, but the
central i>art of the line, which eeenis tn be sharply distinguiahed
from the winga, tinder^oes a de^'ided change of intensity also, »0
that we find from a preliminary examination of the plates that the
lines that are strengthened in smi-8|tots are generally strengthened
near the edge of the Sun, wlii!e the lines that are weakened in sun-
apot8 are tr^ne rally weakened near the ecJge of the Sun, This is
true, I think, in the great majority of cases. Again, we find
another cynous thing : almost all of the lines derived from points
near tlie 8tm*a limb are shifted t«:)wai'ds the red in the spectrum
with reference to Hnea from the centre of the disk; Bnt there are
some striking exceptions, and one of them is most aignilicant: tho
lines in tliis tinting of cyanogen are not appreciably displaced. As
we know from iiihoratory experiments that flu tings are not displaced
by preasure, whereas lines are thus displaced, we seem to have an
interesting confirmation of the conclusion previously reached by
Halm from his visual observations of two lines in the red — that the
tlisplacement of these lines is to l>e ascribed to pressure.*
This investigation is a iininy-Hided one, with applications to both
Bolar and stellar phenomeaa. There is room here for many iuveeti*
gators, who can obtain resulta quite equal, and very likely superior,
in value to any w© can get at Montr t Wilson. A large image of
the Sun is not required, becau.%e the effect is very appreciable at
some diistance from, the limk It is also a matter of no imf>ortatica
whether the definition of the solar image be gtXHl or bad. The one
essential point is that the spectrograph be fairly powerful, and this
ia a very i^imple thing to realise at moderate expense. I hope to
see this snbject taken \\\\ by several observers, who will detonniiie
the shifts and the relative intensities of the Fraunhofer lines, seek
for evidence of periodic changes, and work out an explanation of
these remdrkuble phenomena which will harmonise with some
• This oonclasion is furtliiT conSrmed by the fact that lines of a given
element, which exhibit unsiiuiil disphioeinenta at a certain preMure in th^
laboratory, in gerteral show cwrreapomiing diH|«laeemeit!8 near ili© Sun's limb.
Jt remains to be m«o, however, whether some other hy|xitbeais miiy not be
eijitAlIy cApsbie of accounting for the. oha«tv«d YAmuomen**
Nov, 1907, TF&rJc wUh Inexptnsim Apparatm.
75'
expUnatioD of the relative mteDBitie» of the eame lines in aun*6pot6
and in the spectra of stare,
I may now touch upon aeother field of solar research, and
consider the possibility of doing useful new work with the spectro-
heliograpb, which is by no means so expensive and formidable an
inatrument as one might suppose. The slide shows the first
spectroheliograph used on Mount Wilson, before we built the more
permanent one now employed ; and since the fact that we did
substilute a permanent instrument for the temporary oi^e might
lead to the inference that tlie former did not give good results, I
may add that the photos^raphs made with the wooden instrument
are even better than the later ones. They show only narrow zones
of the eolar surface, but for sharpness they have never been sur-
passed.'*' In the illustration the sp(?ctro,heliograph is partly bidden
under thb spectrograph, and you win only get a rouf^^h notion of it.
There is a rectangular wooden platform here mounted on a pier.
y^? .._.._..t
f -1,
At each corner of thw plntform was screwed a stnal! c-aat-iron block^
in which a V-shaped i^Toove liatl been planed. In each groove was
a steel ball. A moving platform, also built of wood, carrietl the
optical parts of the spectroheliograph and rested on these balls, so
ihat it could he moved across the image of the Sun (formed by a
ooelostat telescope). The motion was produced by a small electric
motor, belted with a piece of tiahdine to this large wooden pulley,
which drove a screw passing through a leatl nut fastetved to the
movable platform. The screw was cut on a foot lathe and the nut
ca^Ft on it. This simple mechanism provided the means of pro-
ducing a slow uidform motion of this upper platform across the
image of the Sun» The arr^ingement of the optical parts was
predaelj the same as in the Rumford spectroheli'^graidi.
Looking at the instrument in plan, we have a slit here (a)
ihrongh which the light passes. A very simple slit will do. This
WAS an old one ; I think it came from a portion of the old Kenwood
• Id the 5 -foot spectrohelioj^aph now em ploy fd^ the disper^itm ia «reat
tnou^h tor photography with the hydrogen as wt-ll at the c»lcium lirwai,
Vnt this rcjuon the exposures lire longer^ anil the defimkioti botiif^what 1«$9
ptrfeot, though qait^ aatiafftctory for practical purpose.
^6 Prof, Hale, OpportunUies for Astronomical LXViXL I,
spectroheliograph. The light passed tLrongh thia slit and M\ on
a coUimating lens (7/), wliicli may be an ordinary uncorrected
if the focal length is authcient. \Ye happened to have same a
mftties which we iij^cd, but tbey were no better than a simple letis
would be. The parail*il rays fell on a plane mirror here (c), and
were reflected to these prisms (rf, d). We used two prisms, bat
one will do perfectly well^ unless hydrogen as well as calcium
flocciili are to be phoiugraphed. These prisms had been discarded ;
they were originally made for the Bruce spectrograph, but they
were so poor they could not be advantageously used, so we
borrowed them from the Yerkes Observatory and put them in
here. The two prisms, with the mirror, gave a total deviation of
1 80'. The light then f>asaed through the canicra lens (e) — here,
also, a simple lens will serve very well — which formed an Imige
of the spectrum on a second slit (/), close to the fixed photographic
plate (g). By setting this slit on the H^ line of calcium^ and
moving the instrument slowly across the solar image with the
motor, excellent photographs of the calcium flocculi were obtained.
The next slide shows some [jhotographs taken with the pei-
roanent instrnment. Such phottjgrapha as these, made with the
calcium and hydrogen Kries, open np for investigation a large field,
which anyone can enter with jnst such an equipment as I have
described — a very simple instrument, with small prisms and lenses^
and built almost entirely of wood.
I will show you in the next photograph some pictures obtained
with the wooden instrument. You will notice that in this case the
motion was not absolutely uniform; yon can detect the slight
irregularity of motion, but it did Jiot atfect the usefulne«ia of
negatives. This is a direct idiotograph of the Sun ; this is
with the 11^ line of ciilcium, and this is the same region as photo
graphed with the H., line of calcium. If somebody would go to
work with such an instrument and let us know exactly what such
photographs as these mean^ they would at least confer a very great
favour upon me, becam^e hitheito I have been unable to determine
with certainty the relative parts played by the ctmiinuous spectrum
of the t'acuhe and the light of the Hj line of calcium in producing
the p}iotogra|:ha« That question is still open, and many investiga*
tions will be required to settle it beyond doubt.
In this Hj, photograpli we probably have a picture of the
calcium vapour at a higher level than the level represent-ed by the
Hj plates. You see, for example^ this bridge of ciilcium vapour
across the spot, which is not shown by Hj. Many investigations
of great interest could be carried on with such a spectroheliograph
B6 I have descrihed. I wish I had time to go into them ; there is
only one I may mention, and that is the comimrison of the calcium
and the hydrogen images. Mr, Butler has asked me to explain
to-tiight a point which I unfortunately failed to make clear in my
talk here at the last meeting of the Society. In speaking of the
relative level of the calcium and hydrogen flocculi, I said we found
that the dark hydrogen tloccuU are shifted somewhat towards the
slight ,
»f tlj^H
*OHTMLY Notice*; of R A S
Vol. LXVrtl. Plate 5-
1
^
8l(t and plate-holder end of sinnpfe wooden Spectrograph of Littrow or auto-
colhmatmg type (^ feet focal length), used in the spectroscopic Caboratory on Mt.
Witfton [not the instriinnent referred to in the lecture, hut a similar one, suitable
for utc in an open room).
Oratine And lent *upport» for modern Spectrosraph (18 feet focal lengthV u*ed \n
1,1 O f^iCi' frtfj"* 7^
r
1 907. Work with Itiexpmsim Apparatus
77
limb of the Sun as compared with the corre^pouding bright c&Icium
floccnU. The natural conclusion to which I came waa that the
hydrogen absorption shown "m this phott»graph is proiluced at a
someTmat higher Jevel» amounting to eoinethinjj; like 1500 miles,
ibiii the cttlcium radiation which ^ives us thiB photograph, Mr,
Butler pointed out to me that the photographs of ilie J^ash spectrum
*ihow the calcium vapour to riae to a higher level than the hydrogen
gu^ and that the difft?rence is about 1500 miles. There is no
queetion about the validity of this result, and the point ia to show
that it is compatible with my conclusion. 1 think the reason ia
simple enough , and lies in this fact : the flocculi photographed with
the Hj line do not represent the highest calcium vapour, but a
level cooaiderably below thtit ; whereas the absorjftion phenomena
known m hydrogen flocenli apparently represent the upper
hydrogen in the chronioaptjere, or in some cases the prominences
Ihemselves, The level of the hydrogen absorption seems to be
about 1500 miles higher than the region from which the Hg light
of calcium proceeds. If, as occasionally happens, the highest
calcium vai>our in the chromosphere ia recorded photographically,
it acts as liydrogen does, and gives dark absorption phenomena,
due to the high level H^ line, and not to be confnsed with the
bright ealciam flocculi due to H^. This point is perhaps a minor
one, but it illastrates some of the results that can be obtained with
A spectroheliograph,
I see that I must rapidly draw to a close. I might mention
trious other methods of employing spectroheliographB, and if
jrone present should be interested at some future time to take
em up I shall be delighted to discuss them in detail 1 may
remark in passing that with a Littrow spectrograph, or any long
BUS spectrograph, and a fixed solar irtjage, one can undertake
"her work of various kinds, such as a determination of the solar
dtion, along some such plan as Duult or Halm followed, but
ag different linea in the spectruns, and benetitiug from the
ntagee of photographic methods. In all such work, co-operation
^h other investigators is greatly to be desired, because it might
otherwise frequently happen that two men would be doing the
aame thing, whereas it would be just as easy for them to supplement
each others work instead of duplicating it.
One other phase of the subject which I should like to have
time to dis4-U8s, but cannot, is that of stellar apectroscopy^ You
will see that for stellar spectroscopy a large telescope in general
does have an advantage. The more light one can coOect and
concentrate in a stellar image the more dispersion can be employed
in the spectroscope, and the users of large apertures therefore do
have an advantage in stellar spectroacopic work. But the fact
remains that small instruments can he used to very great etlect in
this field also, provided that one intelligently plans hie iirvestiga-
tiooa. I know of no better example of this than one which I am
permitted, by the kindness of Father Sidgreaves, to illuaUaXfc,
"~ ia a photc^isplr 0/ the spectrum of o Ceti, made w\t\i a
78 PTof, Hale^ Oppm*tuniiu^ f&r AstronomiccU XiXVilI. i»
refractor of 4 inches aperture, with a priBui of 22 J* anpjle pUc^
over the object-glass. The focal length of the telescope is 4 feet.
The nlide sbows the Rpectrum of Omicron Celi ou the 291)1
Kovember 1905 and on the lat December 1906, and brings out
with great cleaniesa the remarkable cliatiges which occuiTed duritij:
that period. If this Bpeetruni had l;>een photographed with such
au instrument, let us say, as the Bruce spectrograph of the Verkes
Observatory attaclied to the 40-inch telescope^ there w^uuld have
been some adv^utages, but there would also have been Rome dis-
advantages, l>ecauae the entire region covered by the photographs
made witji that instrument (when three prisms are used) is a
ilmited one here in the bine. All of these remarkable flutings m
the less refrangible region would not have appeared in the photo-
graphs, and nothing would have beeit known, if one bad been con-
fined with such an instrument to a short I'egion of the spectrum,
about the very interesting changes shown in this particular case.
The next slide shows another photograph taken by Father
Sidgreaves, in this case with a somewhat different instnimental
Hrrangernent— a direct vision prism at the focus of a 15-inch
ecjuatoriah But you will sec the great range of spectrum included
on the plate^ and remember again that almost all the spectrum,
except a very small region, would l>e missing on photographs
taken with s^ch instruments as the Bruce or Mills spectrographs^
or other three-prism instraraents employed for the investigation
of stellfir motions in the line of sight. You will notice the re-
markably interesting and important fact that the He line of
hydrogen is absent from the picture, probably^ as Mr. NewaJl
suggested, cut out by the absorption of the H line of calcium — the
broad H^ band ; jierhaps in another star lying nearer to us than
the star which gives the bright Uiikb of hydrogen. This serves to
ilUistrate the great importance of the work that can be done with
an instrument of very small size indeed, even in this field of stellar
spectroscopy, which seems peculiarly to belong to telescopes of
large aperture. As I said before, in general the investigator with
a telescope of large aperture does have an advantage in stellar
apectroscopic w^ork ; but there are various investigations of this
sort — and of the kind Professor Pickering has taken up in his very
extensive survey* of tlie whole sky with objective prisms — which
are of extreme impurtmce, and which cnnnot be replaced by work
done with large instruments*
I might go on to speak of the possibilities of work on variable
star"^, bnt they are familiar to most of you. The observation of
many wide double Btare^ my friend Burnham tells me, has been
neglected since the time of Herachel, because the Urge instrumeute,
and even the small ones, have been devoted to closer objects, ao
that in revising his great catalogue Burnham had to measure with
the 40-inch a great many wide doubles which had not been looked
at perhaps since Herachel discovered them more than a century
before. Important doublestar work is always open to men with
small nistvumentSj if a micrometer is available.
JJ"ov. 1907. Work with Inexpennm Apparatus,
Then I might go on io tbe case where h tiiaii ha^ iiq ieh^scope
mX &U, and still wants to luakt^ coiitributioii8 to astrophjjsics. I do
oot now dpe«k of such splendid work aa Aud^i^on dtd when he
4iftcoTered Nova Per^ei with llii' nakud e>'e ; but if one Here con-
rineed that the overcast sky ot London would never open again,
lie could atill work in his Ialrt>ratt>ry and make important contiibu-
iions bj identifying lines and bamls iti spot spectru, as Prnfessor
i^owler hoa been doing of late, or by reaearched in a acore of < »ther
6eld9.
I will close with a few praetica] suggeetions. One reference
to the matter of atmosphere. Perhaps some of xm ftel that if we
could uu ly anceiid into the upper regions we could ^et results very
much better than are obtainable in London, But if we stop to
think of the men who work in London and what they have done,
we must recognise the fact that even here the condititms are not
ao bad as we sometimes imagine, I have often been strongly im-
ptetsed (flince my work in Chicago) with the belief that a ^moky
mtmoephere haa some advantages in astronomical work, for it
«««in8 that the seeing is frequently improved in solar observations
when the sky is smoky. Here is a line chance to test that question,
and 1 think it haa been tested at Greenwich, and that some of the
photagTiiphs taken there (both solar and stellar) f»rove that London
eou>ke dues not prevent excellent defmitioti, I examiiied rather
carefally some plates there yesterday, and the star inniges are
flur|irisingly good in many instances. It seema to me that detini-
tioik hj night as well as by day at Greenwich must be of an order
am^ higher than one might suppose when one thinks of Green-
Wteli as being within the biundariesof London. But it is |>eTfectly
possible to get gaoA results anywhere, pro? it led sudicient care is
Ukcn. One must consider, for example, the best time of day for
*t»liir work. It usually happens that the best delinition of llie Sun
oeeurs in the early morning and the late iifternonn. Mr. Xewall
teUs me that this is as true at Cambridge as it is at Mount Wilson,
Thi* ia worth looking into if one takes up work on the Sun.
Further, one must have a definite pUn of work. This is of ju-ime
ixn|»ortanc«. Devote your entire attention to a single investigation,
involving, if possible, two or three parallel series of observations,
so devised as to throw light on one another. Frequt^ntlj the value
of a given series of ohsen'alions may be enormously enhanced if
other observations are available to aid in their interpretation. For
example, in studying the spectra of sun-spot^, the character of the
dpata, their motions, and changes of form, and the distribution of
the flocculi in their neighbourhood, may be vital factors in inter-
preiiug tl»e spectroscopic phenomena. Then, again, there is the
great p<j6Mibility that new methods and new instruments can be
itpplied. Up to the present time I think the interferometers of
eldon or of Perot and Fabry have never been systematically
ijyed for work on the iSun : that admirable method which Fabry
u imng at the present time in the determination of absolute wave-
lengths wrmld perhaps be very useful indeed if applied to the
8o Errata in the Biti T, K H. Phillips's Paper. hXVXSt r-
meamremerit of the diFiilacement of solar liikea at the centre sad at
the limb, I also believe that the echelon gpectroecope has ntyer
been used for the observation of the narrow bright line^ in the
chromosphere* Furthermore, we are always confronted by the
possibility of perfecting our optical apparatus. I* have been trying
for years to get good [rrisrna of large size, but cannot get boiDO-
geneous glass, and therefore it now seems necessary to attack Xht
problem of tiuid prisms. If someone could take that question up
and show us how to make very large prisms that would bo essenti-
ally porfect, they would accomplish a gi-eat advance. Lord Rayleigh
told me the other day how he made some large fluid prisms tbat
gave nearly theoretical resolution* By an extension of the same
methods it FeemB likely that still larger prisms, suitable for the
exacting requirements of photographic work, could be obtiiined.
And so I nii^ht goon pointing out opportunities of various kinds,
but I should tire you if I ventured to »ia so. We must not forget,
however, thfit the pussihility always exists of getting s^onie entirely
new nietho'l that will be quite as important as any application of
the interferometer, or the i^chelon, or other instruments to which I
have calif d attention,
lu con eluding, I may add that we have made at the Solar
Obaervatoiy a few drawings of some of these simple wooden inslru-
raeuta, which I shall be very glad to place at the disposal of anyone
who might care to build instruments in a similar way.* They
mny serve a useful purpose by saving a certain amount of time.
I hopo I have shown thsit it is possible not merely to do work
of an inferior quality, but to do work of the first quality, with
small or inexpensive instruments ; work that cannot be duplicated
or will not be duplicated with large instruments ; in other words^
that there is a splendid field for any man who wishes to accompliBh
results, wherever he may be sitiiaUd, and however simple his meane
of research may be. I feel so strongly on this subject that I hope
the suggest ions I have niade will not be entirely without effect
We need the ideas of men from all parts of the wurld ; wq need
the contributions they can make ; and we need them eveu mor«
than we need larger instrumental meaujs than we now possess,
* At Mr, Maw's reqoest, a tmmber of blue priata will be Fcnt to tli« Boyil
Astronomical Society for ooaraDieat lefereiicG.
Errata in the Rev, T. E, R, PhiUips'g paper. Monthly
Notices, vol, Ixvii,
Page 524, line Sf/or 1895-6 read 1905-6.
Page 526, line 31, /or 1907 read 1906*
MONTHLY NOTICES
OF THE
ROYAL ASTRONOMICAL SOCIETY.
foL LXVIIL
December 13, 1907.
No. 2
H. F. Nkwall, Esq., M.A., F.R.S,, Prksidknt, in the Chair.
Bunlett Mason, Laronflouette, Bayonne, France ; and
Arthur William Meers, F.Ej'r*S.^ Lugano, Wickham Koad,
Beckenhaii],
were bitlloted for and duly elected Fellows of the Society.
The following candidates were proposfd for election as Fellows
f thi? Society, the names of the pro^MJ^era from personal knowledge
>emg appended :- —
Henry Hermann Grunin;;^, ^f.Sc.» Patent Agent and Engineer,
J Blftkesley Avenue, Killing, W. (prgpoaed by Rev. F. B.
AUisttn) ;
Jan B. Hubrecht, Chrifit's College, Cambridge (pro[>osed by
Bryan Cooksim) ;
Victor A. Lo winger, Trigonometrical Survey Department,
Taiping» Federated Malay States (proposed by Sir David
Gill);
^v. Maicoltn Parker Miller McLean, M.A., The Rectory,
We^t Raynliam, Norfolk {piopoHed by Henry T. Gerrans) ;
Alfred \\\ Porter, 1j,Sc.» Assistant Pn^fessur of Physica,
University College, London, W.C. (proposed by L, N. G.
Filon) ;
Harold Knor Shaw, B.A., Trinity College, Cambridge (pro-
posed by 8, A. Saunder) ;
<3apt. Eldred Weston White, Brockley Villa, Uptou RoBiii^
SoutUviUe, Bristol (proposed by K, Favvcett White).
82 Mr. A, K Hink$, ConsirmtUm of a Standard Lxvni, 2,
Mr. A. IL Coni-ady, Mr. R, Inwards, and Mr. G» J. New begin
were appointed auditors of the Treasurer's accounts for 1 906.
Eighty pre^sente were aunouneetl as having beau received since
the last ineetingi incktding, amongst others x —
Abbadia Observatory, Observations^ tome 5 ; and Bordeaux
Observatory, Catalogue pbotographique du citil, Co<>rdunn/*es
rectilignes, tome 2, presented by the Observatories ; Gronnigea
Astrogrupiiical Lal>oratory, Libratiun of the three inner large
satellitee of Jupiter (W. de Sitter), pre^enteil by the Laboratory ;
Zieiiler Polar Expedition, SLientihc results, presented by the
estate of Wul Ziegler.
Astrografihic Chart; 16 charts presented by the lii^yal Ob-
servatory, Gref!nwich ; and 19 charts presented by the French
Minister of Public Instruction,
Solar Parailax Papers. No, 6*
Const t*uct ion of a Standard Cattjioffue 0/ Phoiofjniphic Utar
Places. By Arlliur H. Hink.«, M.A.
1
g I. The construction of a standard catalogue of photographic
star places along the track of the [danel Eros was iiiidertakeu in
the first instance to provide for the reduction of tliose series of
photographs of the planet which, having a field aiiialler than 2*
»t[uare, could not be reduced directly with the etoiles de repere;
and also to provide exact places of the stars which had been used
in visnal micronietric comparii^ons with the planet.
It now seems probable that the statnlard cntalogiie may have an
extended use ; for^ as will be shown latf^r, it will be possible by its
aid to etfoct very simply the equivalent of a re- reduction of all the
published places of the planet to this new system of stars, lying
close to the track of the planet, and more nearly equal to it in
magnitude than are the ttoiles de rephre. This sliould provide a
powerful method of searching for aystematic errors in the phott>
graphic plat^es of the planet and the value of the Solar Parallax
derived friun them.
§ 2. The published material for the construction of the catalogue
was found in the Paris Eros Circulars, Nos. 10 and i r,* The
results of ail inter-conqiarison of the work of the difi^erent oliserva-
tor tea were published in Solar Parallax Papers Kos. 4 and 5 (Ji/. A'.,
vol Ixvi. p, 481, vol livii, p, 70, 1906 June and November). In
those papers may be found the foUnwiiirr conclusions : —
(i) That several series of photographic star places are affected
with a magnitude equation of serious amount.
{2) That other series ere affected by progressive discord ancea,
• Circular Ko. la appeared after the principid part of the work wm
^Dished, But aee later, §f n atid 12.
which are sometimes dependent on variatious in the adopted place®
of the fimdamental stars, stud soraetimea not,
(3) That, ill general^ the star places puhlished in the Paris
Circulars are by no means lionujgetieous,
(4) And that thc^ adopted furm of publication did not permit
of a complete? inquiry into tfee^e matters.
§ 3. Fn 1906 March I ventured to send to the iJirectors of the
obf^rvattiriee t:ont:erned a circular letter, submitting' for their con-
sidvratioQ the following proposals : —
That I should print and distribute a large number of Ibta of
the eioile^ de repere.
That they should kindly undertake to fill in upon those sheets,
in the spaces provided for i\w purpose, the deduced photographic
places of the rtperf stars, using a separate list for <mch plate, so
that the ra^ults from each intlividual plate were kept quite distinct.
That they should also fill in, upon other sheets to be provided
for the purpose, the lists for each separate plate of the deduced
]dac^^ of the Hoile^ (U eomparaison (given in Pans Circulars, Tableau
III., either in ledgers or as means^ without indication of the plate
ftom which each was derived)*
These proposals were very kindly received bj the Directors to
^bom they were addressed. The printed sheets were sent out in
1906 May, and -were quickly filled up and returned. My siocere
acknowledgments are due to the Directors of the Observatories of
Bordeaux, Helsingfors, Nortlilield, 8an Fernando, and Toulouse,
for the cordiality with which they unilert'>ok the troiiblegome task
' 'MlinginupOD the printed sheets all the desired information;
Ih? Astrotiomer Royal, who sent advance sheets of the Greenwich
01 lime containing equivalent information; to the Director of the
j'liikowa Observatory, who had previously given rae similar material
\n (ilvunce of publication; and to the Director of the Paris
<J>»^ervatory, who furnished advance proofs of the Pam original
itif: isnres.
The information thus obtained, added to that already published
in full in the Paris Circulai's for the eimles du carrtf de 20', gave
^ae the completely separated results from a very large number of
individual plates covering the path of the planet to 1900 December
^i. (The discussion of the material for 1901 is postponed to a
later date.)
§ 4, To make this considerable mass of material (about 60,000
«tftT positions) homogeneous, I bad first to find a way of reducing
^11 the scries to ooe fundamental system^* and to decide what this
system should be.
In paper No, 4 1 have given reasons for thinking that no one
erf those systems of fundamental star places based directly upon the
meridian observations is satisfactory for our purpose, I decided
to fc>rm a provisional system from photographic series which had
• 3m S*P.P, No. 4, I 4» f<»r the system to which each was origmaW^j
84 Mr, A. R, Hinks, Consirudian. of a St^mdard LXvni. 2,
been reduced to Loewy's nystem of meridian places. These series
are compared in S,P.P, No. 5» \k 8o^ Table VL It is tbere ftbowo
that the results from Greenwich and Paris are in excellent agree-
ment J that the Toulouse places are nearly accordant with them ;
but that the Catauia plaeej^ difter from Paris in a large and irregular
manner. I decided to omit the Catania results for the time, and
to base the provisional photographic system of rejtire stars on a
mean of Greenwich, Paris^ and Toulouse.
The three observatories were given equal weight. A photo-
graphic place depending on i or 2 plates was given weight i ; on
3 to 6 plates, weight 2 ; and on 7 or more, weight 5. There would
have been little advantage in adopting a more elaborate syatem of
weights, since the real ccimparative weight of a result from one and
from two plates depends very much upon the consideration whether
or not the two plates are upon the same centre, and reduced with
the same Belection of fundamental stars.
Wo will call this system the System P,Ph. (provisional photo-
graphic).
The r6le of system P. Ph. is temporary. It serves to detect and
eliminate systematic deviations between diflerent observat<3rie^. It
will be judged by the eventual degree of accordance between the
reduced results when they are brought together for formation of
the mean standard places. If this is satisfactory, we may consider
that the system P,Ph. has playeiJ its part, and it may be allowed
to disuppear. We need not give, therefore, in this paper, the
adopted [daces of the rep* re stars in the P.Ph, system, but may
proceed ki once to examine its use, and the eDects of its use.
§ 5. The system P. Ph. is usetl as follows : —
We take differences between the places of the mp^re stars de-
rimd from a m.ngh phde^ and their places in the system P.Ph,
The nii^an of these tlifferciices, in the sense P. Ph. — plat*:*, applied
as a correction to the plate places of the rejmre stard, m tikes them
conform on the average to the eystem P.PIi.
The same correctiofi applied to all other star places deduced
from til is plate should reduce them equally to the system P.Ph.^
provided that ther*^ is no systematic discontinuity between rept-r^
stars and other stars.
The application of tbis correction produces in a general kind
of way the same etTect upon the star places as a re-reduction of
the plate to the system P. Ph.; it leaves the results rougher in
detail than a complete re-reduction, but nearly without thoae
systematic errors which have been called Progressive discordances
in S,P.P. iS^i. 5, Tables VI. and YIl.
g 6. Corrections to be applied to individual plates were obtained
in this way for the whole of the plates made at Bordeaux,
Helsingfors, North field, San Fernando, and Toulouse. The
following summary will givG an idea of the size and distribution of
these corrections.
Dec 1907. Catalogue 0/ Photographic Sia7' Places,
8s
B.A.Oorr.
T<ibi6 I
q
Piute Correctiong.
Bord.
Heb.
North.
Sail Fern.
ord. as.
Toulouse.
ord. as.
»
ft
•
s
s
i
A
+ ■015
+ 027
+ 021
+ 035
+ *034
+ XH7
+ '017
- -oio
+ *002
-*oo5
-•017
- •014
-•009
- "021
+ *oo3
H^ *0I4
+ 007
+ '007
-f*tx)9
+ •001
+ *oqi
0
16
4
S
6
1
2
10
15
26
30
jS
4
7
3 J
5
<7
19
»5
S
22
2
0
0
7
2
6
7
0
0
0
r
0
a
I
-f -'is
+ •06
#41
+ *30 .
+ •30
^'*20
+ '10
if
•10
-08
- *I2
- -02
*'o6
-■06
-*U
h-04
- '01
'00
4-09
+ •07
+ •02
+ ^04
I
0
I
7
3
0
3
»3
I
8
41
23
5
10
17
33
27
17
H
10
25
2
2
n
0
t
I
I
0
0
0
0
0
0
0
"lietwveu -hXii^ JLQil + *oo6
+ 005 and * *005
- '006 and --015
Ictt than ' 015
Decl Oorr»
Drwt«6t
Hon
Iol gre»?er iimn -t 15
betwecti ^'15 and +06
- 05 and ^ 05
- '06 and - '15
Ifl» than - '1 5
The above figures show that the reduction to a syeteru P,Ph, is
by no nieaDs superfluous.
The fact that the mean correction for an entire series often
differs coadderably from zero may no doubt be attributed to
divergeoce in the lueihodi* of combining and weighting the
meridian results for the adopted repWe star places.
The variations from plate to plate must be di^e partly to these
dirergeoces, and partly to the roughness of the meridian places
compared with the smoothed system P. Ph.
Plate corrections fur Cidunia, (Greenwich, and Paris were not
derived, because the separated results for each plate were not at
the time available.* It scpms certain, however, that it would have
been duj:*6rflaous to apply the proee&s to tht^ Greenwich and Paris
aeriea, which agree exceedingly well, and have preponderating
weight in the formation of tlje system P.Pii, The absence of
pti^te corrections fur Catania ia to be regretted^ since largo diver-
g^QceA ocnur in this serieA\ (See S,P,P. No. 5, p. 84.)
§ 7. Correetiom for Magnitude 3^tiation in the San Fernando
imd Tftulou»e Series, — It was showt^ in S.P,P. No. 5, p. 78, that
ibe Toulouse results have a lar^^e and nearly linear magnitude
• Th* Reparatad results for the Greenwich platen liavif since been com^
mtiiiitat«d to me in proof, by tho kindness nf tlie Astraiiomer Royal.
1
86 Jfn A. A Hinks^ Constrttcimn of a Standard LX^
equation in declination (but none in right ascension). This rts
baa been confirmed by M. Baillaud, Director of tbe Touloij
Observatory, but he lias not succeeded in discovering the causa
it (For this information I am indebted to M, Baillaud.)
It was ghown in the same place that the San Fernando rig
ascensions and declinatioos were both affected by a consider
nonlinear magnitude *^quation* No further light has been throil
on the cause of tlds error. Corrections were obtained by plottil
the results for successive nuignitude groujjs (/or, eit.\ and drawif
the best possible smooth curves through them. The quantities
derived from theije curvei? were adjusted to allow for the fact that
a general mean correction for stars of all magnitudes resulted
from the application of the plate corrections of Table I. :
quantity o^'oj was subtracted from the Toulouse corrections,
©■^ooj, ©"'oS from the respective San Fernando corrections,
final mai;nitude currections applicable to Toulouse and
Fernando are given in condensed form in the folio wiug table :-
Table H.
Adopted Correclions for Magnitude Equation.
TouiouBe.
San Fernando.
Mar.
Decl,
E.A.
Dec].
7-0
-c
"23
s
-f 0*011
-0^21
7*5
-
15
•4-
6
- l^i
8'o
8
T"
2
^ 6]
s^s
0
1
2
4 2
9^0
+
S
2
^ 8
9'5
+
15
+
2
+ 12
lO'O
+
23
+
6
4 15
lo's
-t-
3J
+
12
+ 15
iro
+
38
+
18
-^ «5
u's
-f-
46
-f
24
-h 14
12'o
+
54
+
32
+ 10
3 8. Collection 0/ matencd for formation of eataiot/ue^^The
individual star places jmblished in Paris Circulirs 10-12, or
communicated to me hi manuscript upon the prmted forms sent oat
from Ca^mbridge, were entered on catalogue cards, differently
coloured for each ubservatorj* These will be referred to as "det
cards."
The plate corrections and tlie magnitude equation correctia
*.vere applied on the detail cards, and ** observatory means "
formed.
Whenever a star had been observed at more than one observa-
tory, a "summary card** was added to the card catalogue
which the observatory means were collected, and the final weigh!
mean taken.
I907- Catalogue of Photographic Star Places.
87
§ 9. lite System of Weights. — The summary cards shawed at
ftce that the observatories were not entitled to equal weight. At
mme time it wns not posjiiible to derive a rigorous system of
leights from a discussion of thi^ divergences between one observa*
ory and another, or between the indivi^Iual results of an observa-
ry. These Jivergences were necessarily much affected by the
ct that five or six separate determinations of a star place made at
ae obaen'atory would depend on the same set of repere atars, and
on the same part of the plate, wherea« the same star would be
Btermined elsewhere on a different centre.
After some trial it appea.red that substantial justice would be
[me if (treeiiwich and Paris were ^iven a weight double that uf
otb«r i>b«ervatorie^» and if the weight of each observatory's
ODtfibution, so far as it depended upon tli© rmml>er of obgerva-
Lins contributed by each, were on the i?anie scale as was used in
Eiking the system P. Ph. of §4.
Two Catania plates and one San Fernando were rejected for
I anex plained systematic discordance of large amount; a certain
iiimber of obvious misprints in the Circulars were corrected ^ and a
pw discordant observations, probably misprints, were excluded.
I Finally, stars whoae weiglvied mean had weight 4 or more
pure passed intt» a first cl&ss, aad these form the photographic
Bandard system discussed in what follows. In the region covered
ly the planet between 1900 Oct. i and Dec. 31 the catalogue
pout4itn6 1300 firt^t class stars. And in addition there are about
2500 stars in a second cla^, whose weight is less than 4, which
are not for the present included in the staoiiard system.
" §10. T^itt of the Statit/artt S}jde7n. — As a test of the homo-
eneity of the contributions which the dififerent observatories make
I the ntandard system, I have discnaaed the differences, Standard
biuus Individual contribution to it, from several points of view.
A. The ditfereiices, taken wjth regard to sign, have been
aup«)d (i) '^i magnitude «iroup8, to see if any residual magnitude
jaation renmiried ; and (2) in date groups, to see if there were
ay discontinuity along the path of the planet which might gradually
listort the standard systeuj, and damage an ultimate iletermi nation
' the mass of tlie Moon.
B. The differences, taken without regard to sign, have l>een
[rouped likewise (i) in magnitude groups, to see how far tbe inter-
eemeul of the photographic places is dependent on tnugnitude;
bd (2) in date grouj)a, to see if the same standard of internal
eenient is maintained along the whole system.
Tbe magnitude groups are those used iu S,P,P, No, 5,
iibl<^IIL, IV., andV,
The date groups are broader than those used in Table VTI.
Group L covers Sept, 15-Oct. 23
,, IL „ Oct 24-Nov* 24
„ ML „ Nov. 25-Dec. 15
,, 1\\ ., Dec, J 5- Dec. 31
88 Mr, A, E, Hinks, Covistruction of a Siafidard LXVUt 2,
There is no special sigui^cance in this particular divifiian, which
arose more or lees accidentally! and has been retained for con-
venience,
gii. Search for Mn<jniiud€ Equation in R,A, — The division
into magnitude groups of the ditferenees Standard minus Individual
contribution was made separately fur the tour date groups. Bul^;
there is no evidence in the results of any diiHnite change of
magnitude equation with the date; if any such change exists, it is
obscured by the accidental discordances. Consetjuently I give only
the mean results for the whole period Oct.-liec, except in the case
of San Fernando, to which a correLtion for magnitude etination
has been applied. The fieparate reaulta for each San Fernando
date group are given.
The figures in brackets are the numbers of observatory means
contributing to the mean discordances which follow*
Table m.
Comparison of Eight Aacendons in Magnitude Group«,
Standard System minus —
I
Bordeaux.
Catania.
Greenwich.
HelBingfom.
Northfield.
Mae.
■
e
1
ft
»
' 7*4
li4)-'007
(78) - -004
(32) •
000
<I2)+-OI5
(241 + xna
7*5- 8-4
(43)' i
(66)+ 3
(73)-
(57)+ 4
(59)+ J
8'S- 9^2
(99) 0
(55)+ 6
(I2S)-
(75)- 5
(89)- 4
9*3- 9"8
(48)- 3
(50)4- 8
(32) +
(89)- 3
(10)- ;|
9'9-io'5
{130- 2
(72)+ 7
(27)-
(117)- 8
io*6- ira
(53)- 4
(nSj-f 3
(5)-
(99)- 5
...
ir3-i2'i
(6)- 15
(167)+ 1
(3)-
s
(7)+ 6
...
12*2 -
(21)-. 4
...
Paris.
PuJkowa.
Toulonsa.
XTpaala,
MinneftpaUs.
- 7'4
{47)+ '003
a
(7)+ -002
(33)''
003
(i5) + *oi6
(8)+ 'on
7-5- 8-4
(70)- I
(22)+ 2
(124) +
3
(43)+ 6
(17)+ 3
8-s- 9-2
(70 0
(27)+ 1
(229) +
4
(iin+ i
(38)+ 2
9'3' 9*8
(60)^ 3
(5)+ 10
(99) +
3
(68)- 1
(38)- 13
9*9 - 10*5
(103)+ t
(179) +
5
(84)- 1
(49)- I
fO'6-ir2
(154)+ 2
(147) +
8
(33)- 6
(25)- 7
113- 12 I
(1931-^ 2
*
(49) +
7
(5)- 3
♦ 9)- 15
J2i-
(267)4^ 2
W' 16
s.
Farn. Group I.
S. F. 11
8. P. m
s. F. nr.
S. P. Mean.
' 7*4
(19)- 002
(16)- 012
i
(4)-*
002
(iS)-*oo8
(54)- -007
7*5- 8'4
(35)+ 3
(3»)+ 4
(9) +
9
(28)+ I
(103)+ 3
8S- 9'^
(67)+ 4
(72)+ 2
(42) +
4
(52)+ I
(233)+ f
9'3- 9*8
(21) -f- 11
(33)+ 2
(21)-
4
(14)+ s
(89)+ 4
9*9-10*5
(40)+ 3
(63)+ n
(29) +
S
(14)- t
{146)+ 6
io^-n'2
(46) 0
(79)- I
(12)-
3
(8)- 10
(14S)- »
irj- 12-1
(8)- 6
(40)+ 2
(3)- 13
(5«>- t
\^•^-
f?}-
(8)
1907. Caialoguc of Pholographu Star Places,
89
The results of this table confirm the coucJusion of S,P,P, Ko, 5,
.the photographic 6erie« which <nintrihute to the standard
. are free from relative magnitude equation, with the excep-
tion of San Fernando,
The latter observations have been corrected, and we can now
see how far this correction has been surces-tfuL The correctioii
applied was decidedly non-linear; the aimve uomparis^jn gives some
indication that a slight non-linear correction of opposite cur%^atiire
m now required : that is to aay, that tlie cnrvatnre of the original
determination was a little excessive. (The material used was not
altogether the same.) The magnitude equation results from the
separate date gronj>6 are not, however, accordant enough to make it
probable that any magnitude equation correction for 8an Fernando
is sharply determinable ; and we may conclude that the attempt
to correct th^e KA.'s has been as successfut slu the material
allows.
The Upsala and MinneapoHa results were not published in time
to be included in the first edition of the standard system. But
they show no ma*^nitude equation when compared with it, and
may therefore be included safely on a revision.
§ 12. Searrh for Maflnifitde EqwUion in Decfutaf ion. ^^Th^
eli]»ation3 have been treated exactly as the ri^bt ascensions,
io there is no trace of any definite change of magnitude equation
the date, and the general means are free from it. The cor-
ctions applied to tht< declinations of San Fernando and Toulouse
i to have been successful in eliminating the large errors originally
nd in them. Table IV. gives the results for the date groups
in which the elimination has been least successful, and for the
mean,
The lately published declinations of Upsala and Minneapolis
bow no magnitude equation relative to the standard system.
Table tV.
GomparisonB of Becll nations in Bfagnitnde Grottps.
Standard System minus —
t^
Bordeanx.
CAtania.
Greenwich.
Helsiiigrora.
Northfield,
fr^'
(14)+'^
(78)+'-o6
(32)+"-OI
(l2)+''o2
(23) -"03
Ti-Si
(43)- '
(67) 0
(73)- «
(571+ 5
(59)+ 1
t}' »■»
(99)+ «
(57)+ 4
(i*S)+ 2
(73)- I
(89) 0
E"'^
(48)+ 1
(SO)- 3
(32)+ 4
(89) 0
(10)- s
TJ-to's
(131) 0
(74)+ 2
(27)+ 3
(117)- 2
...
(0-6-,,.,
(53)- 4
(n8)+ 3
(5)- 3
(99)- 3
...
"1-i»r
(6)- 3
('77)- 6
<3) P
(7)- 6
..,
{^3}- n
90 Mr. A, B. Hinks, Construction of a Standard LXVili. 2,
Table IV.—continufd.
CJompariaonB of Deolinations in Uagnitude Groups.
Standard System miniu —
Paris.
Polkowa.
S. Fern. in. S. Fern. IV.
S.F. Mean.
- 7-4
(47) -"06
(7) -''02
(4) +'03 (15) + '07
(54) +'-05
7-5- 8-4
(70)- 3
(22)+ 2
(9)+ 6 (28)+ I
(103)+ 4
8-5- 9-2
(71)+ 4
(27) 0
(42^+ 10 (52)+ 5
(233)+ I
93- 9'8
(60)- 3
(5)- 5
(21)+ 8 (14)+ 9
(89)+ 2
9-9-IO-5
(103)- 2
...
(29)+ 5 (14)+ 8
(147)+ 3
IO*6- 1 1 -2
(123)- 3
(12)+ 37 (8)+ 19
(i46)-r 8
11-3 -I2-I
(193)- 2
(3)+ 24
(54)+ 4
12-2-
(267)+ I
(8)- 2
Toui. n.
Toui. m.
Tool. Mean. Upsala.
MinneapoliB.
- 74
(9) + '13
(9) + '-07
(33) +'-05 (i5)+'-o6
(8) -"05
7-5- 8-4
(40) - I
(i8)+ 3
(124)+ I (43)+ 3
(17)+ 9
8-5- 9-2
(70- I
(40- 9
(229)- 2 (in)+ 2
(38)- I
9-3- 9«
(30)+ 5
(19)- 7
(97)+ I (68)+ 6
(38)+ 3
9*9 -10-5
(76)+ I
(39)- I
(179)+ 2 (84)+ I
(48)+ 9
IO'6 - I 1*2
(50- 5
(20)- 17
(147)- 3 (33)+ I
(25}- 5
ir3-i2i
(17)- 9
(9)- 21
(49)- 7 (5)+ 4X
(9)- 9
12-2-
...
(2)+ 10
313. Conclusion as to Photographic Magnitude Equation, — As
the. result of our operations, we have a system of stars derived from '
photographs made at nine different observatories ; and the com- \
parison of each series with the mean shows no relative magnitude
equation.
Further, two additional series, not originally included, show no
magnitude equation relative to the system.
It is extremely unlikely tliat these, eleven series should be
affected by magnitude equation of like sign and amount.
I conclude that our photographic standard system is sensibly
free, not only from relative, but frum absolute magnitude equation.
§ 14. iSearch/or Progressive or Uniform Discordances irrespective
of MagnitwJp, — With the fear of magnitude equation removed, we
may examine the mean divergences in the date groups, to see if
there is any evidence of progressive or general discordance. The
tables which follow are self-explauatory.
Dec. 1907.
Caialogm oj
*
* Photographic Star PI
Table V.
(ices.
9t M
Oompikriion of Eight AscetiBiotiB, in Bate Groopii,
Standard Syatem niinxiA —
Bordeaux,
Catania. Greenwich.
HelBingfors.
Northfield.
, Sept 15-Oct. 23
(117) --004
(i76) + 'ooi (70)-'oo2
(76) - 'O03
(35)+'oo«
. Oct. 24-^^v- 24
(163}- 3
(290) -f 2 (104) 0
(154)" 4
(57)- I
;. KoT, as-Doc. t5
(421- 2
(100)+ 9 (52)^ I
(145)' 3
(36; 0
L Dees, i6-Dec. 31
(73- I
(60- t (71: 3
(S»)- 3
(54) + I
Mean
(395) - 2
(627)4- 3 <297)- I
(456)- 3
(tSl) Q
PariB.
Pulkowa.
San Fern. ToulotiBe.
Upeala. Minneapolis.
(243)+ '003
9 s
(243)-f*CX>2 (2l6)4-*002
(39)- 002
(42)- -004
i CJ90)
0 U4}+'tx>4
(334)+ 2 (295)+ 9
C149)- 3
(69)- 4
'. im)
0 (32)+ 4
(liK)-f 2 (156)+ 2
(97)+ IS
in)' 2
(i73) +
2 (15)^ 4
(135) I (194)-^ 2
(74)- 13
(42)- 4
Me«i (935)-^
I (61)+ 2
(830)4 2 (861)+ 4
*
Table TL
(359) + 1
(186)- 4
1
OompariBon of Declinationa, in Bute Groupe,
■
Standard Syatem minus—
Bordeaux.
Catania, Greenwich.
HelBingforB.
Northfield.
L Sept. iS-Oct. 23
(117) w
(176) ''05 (7o)+"oi
(74) -^-''oi
(35)+"-02
t^Oct, 24-No».a4
(163)- 2
(307)' 2 (104)+ I
(154)- 3
(57)+ I
, N01P. 25-Dec. 15
(42)+ I
(100)+ I (52)-*- 2
(145)- I
(35) 0
\ Dec i6-Do<!. 31
(73)+ 3
(60)+ 16 (71) 0
(Si)-f I
(54)- 2
Menn
(395) 0
(643) 0 (297)+ I
(454)- 1
ti8t) 0
Paris,
Fulkowa.
San Fern. Touloufle.
Upeala. Minneapolis, j
^m (243)--!
[>2 ,.,"
(243) +''03 (2i6)+'-oi
(39)H-''o9
U2)+"'o8
V (390)^
I (14)+ 'oi
(338)^ I (294)^ I
(149)- 1
(69)- 2
(129)-
2 (32) 0
(n8)4- II {155)- 6
(97)+ 3
(3*)-*- 6
tJ72)-
5 («5)- 3
(135)+ 6 (194)-^ 2
(74)+ 8
^AiH \
M«ao (934]-
1 (61) 0
{S34)-t^ 4 I8s9)- I
(359)+ 3
^^%^U •i
cvm^j
92 J/r. A, K Minks, Cmistruction oj a Statidard LXVUL
It h clear that uo series hfts now any sensible uniform discord*
ane« from the mean- And the results from the separate date
groups are nearly concordant, so that it seems out of the question
that the standard system has been seriouBly distorted in any part
by the inclusion of discordant niateriaL Tlie only marked caaes of
discordance are in Catania group III, and Toulouse group IL We
shall have occasion to examine these in a later paper,
§ 15. Effect of Hie app/iratum of Plate Corrediotis. — We may
look in the above table for the effect of the application of the
plate correctiuijs of § 6. The largest corrections were found for
Helsingfors, Northtield, and San Fernauiio plates.
The Helsiuj^fors plates received on the average corrections of
4''**oi4, -"'oi (derived from repere stars); the results, including
all stars, are now discordant from the standard system by - "'ooj,
Tbe Northfield plates received on the average corrections of
-|-*'oo7, ''oo ; the results are now discordant from the standard
system by "'ooo, "'oo.
The San Fernando plates received on the average corrections of
+ ■•008, + "*o8 ; they are now discordant from the standard system
by +»-oo2, +"*Q4,
In these cases the application of plate corrections haa very
much reduced the genital discordance.
For Bu rdeaux and Toulouse the mean plate correction waa
small, and the mean dbcordance from the standard system remains
small.
The discordances of the series to which no plate corrections
were applied are also, foTtuiiately, small We may conclude that
the application of the plate corrections has been successful in
eliminating such mean discordances between the different series as
were sensible,
§ 16. Influence of Magnitude an tJie Accuracy of the Photo-
tjrapkic Star Places,
Many of the star images measured upon these plates are at
tbe limit of measurability ; and in many cases, by reason of thick
skies or unduly short exposures, the images of the planet also are
only just measurable. It is therefore very necessary to determine
whether tlie accuracy of the photographic places is seriously im-
paired when the images are very faint. ^M
To examine this poiut I have tabulated the average disco^P
ances (without regard to sign) of each observatory's series from
the stimdard system. Since the mean discordances are very smalli
the average discordances will give a fuir idea of the relative accuracy
of the star places for different magnitudes and for different aeries.
^^SI^^^F^V
Dec 1907. CiUahtpie of Ph^ographk Sfar Places,
'i
Table Vn.
■
Avenge Dtacordanoe of Eight Aie«ziflioiis, in
Magnitude Gronpe. ^^|
Standard System minns^
^
Bo^deanx.
CaUnia.
Greenwich.
Helsingfors.
Korthfield.
M«i^
1
■
t
•
t
- 7*4
C14) '014
C78) -026
izz) -on
(12) -019
(24) -021
7'S- »'4
(43) 1^
(66) 16
(73) 9
(57) IS
(59) 13
85- 9-2
(99) n
(55) 22
Ct2s) 7
(75) 17
(89) 14
rs' 98
(4«) 9
(5«) 17
(32) «
(89) 16
(10) 2S
9^-105
(131) 13
(72) 23
(27) 7
(iJ7) 23
tQ'6 - J 1 *2
(53' 9
(118) 21
(5) 6
(99) 23
m
11-5- 121
(6) 15
(167) 23
(3) s
(7) 27
... ■
J2 2-
{21) 22
'' ■
P^liM.
Pnlkowa.
San Fernando.
Toulouse,
Upsala.
Minneapolis.
(47) *oia
(7) 010
■
(54) '015
in) ^015
a
(IS) *O30
(8) *03o
(70) 9
(«) 14
(1031 17
(124) 18
(43) IS
(17) 26
(70 9
(^) n
(233) 15
(229) 16
(ill) 17
(38) 21
(6o> 9
(5) n
(89) 21
(99) «4
(68) 20
m 19
(103) S
(146) 24
(179) IS
(84) 21
(49) 21
(1*4) I^
.,
(145) 26
(147) 18
(33) 27
(2S) 22
(193) 12
...
(52) 24
(49) 19
(5) 27
(9) 34
(367) 11
...
(8) 19
t..
(2) 16
Table VIII.
■
Average Discordance of Bectinations, in Magnitude Qroupe ^^M
Standard System minus—
^
Bordeaux,
Catania.
Greenwich.
Helsingfofft.
Northfield,
Mm9.
H
u
' 7 A
(14) '17
(7S) '-27
(32) -09
^12) 'I9
(23) *21
7-S- 84
(43) 10
(67) 22
(73) 8
(57) <9
(59) «o
S'S- 9-i
(99) 9
(57) 21
(125) 7
(73) 16
(89) U
91- 98
(4«) to
(5«» «7
(32) 6
(89) 12
(lo) 16
9^-105
(»3I) ii
(74) 20
{^7) 8
(117) 16
• ^
10^- lt*2
(53) "
(liS) IS
(5) 3
(99) 20
■
ir3-i2*j
(6) 9
{177) 20
(3) 9
(7) 29
... m
12**-
...
(22) 27
...
... ■
FadiL
Putkowa.
San Fernando.
Toulouse.
Upsala.
Minneapolis.
(4J> *^
(7) *07
(54) '^7
(33) '21
(15) "iS
(8) -33
(70) 10
(22) 9
{103) 14
(124) 16
(43) 13
(17) J9
(71) 10
(27) S
(a3J) IS
(229) 16
(III) 13
(38) 20
(60) 10
(5) »7
(89) '7
(97) 14
(6.S) 17
(3S) 17
(lOi) 9
♦».
(147) 22
(179) iS
(84) 19
(48) 21
(123) 10
(m6) 27
(M7) 19
(33) 21
(25) 22
(I93> '2
(54) 24
(49) 22
(5) 45
(9) 22
(a67> »-^
(S) 17
^
^m
(2) 22
(rm.9
94 Mr. A. R Hinks, Cofistriiciion of a Stwitdard Lxvm.
In cum paring these results we musl remember that Greenwich
and Paris have received double weight, and that they will natural] j
therefore diverge less fronj the mean than the others* We mu
also remember that the falDter stfirs have on the average fev
obserTaiions than those of moderate brightness ; and no accoti
has been taken of the number of observations for each star at
observatory io making the above comparisooa. Nevertheless, t^
apparent svocaracy of the fainter stars falla off very little^ except ;
the case of Helsingfors and San Fernando. The latter series
measured in one orientation ooly, which may account f»ir muG
A mon- (lelaile«i (iii*nu.ssion of th*' Hel^ingfors serie« will be givi
in a later pa;H'r, which may help to explain thia result.
The general ctinclusion, that the accuracy of the very faint *tar
places is liitle inferior tt> that of the brighter, is as welcome aa it
is uiiexp4'Cted,
§ 17. Comparative and Abitolute Accuracy of the r^sultt fn
iiifferent Oh^ermhtries. — Since it has been shown in the la
paragraph that magnitude has small infl^ience on accuracy, we ma
combine the material into date groups without Inquiring cloa '
whether the mean magnituile u the same in each group, and mi
thus discover whether the ^^ame accuracy was achieved at differeu
dates, in diHerent part*! of the plant^t's path. And we may further
examine whether the rough system of weights adopted fairly
represents the relative nmrits of the results from different
observatories.
Table IX
Average Discordance of Bight Ascensions, in Date Gronps,
Standard System minus —
^^^P
Bordeaux.
Catania.
Greenwich.
Helfiingfon
•CfQItp
«
■
1
a
1. Hept,
iS-Oct. 23
(117) 'OIO
(176)
*020
(70)
•007
(76) -025
IL Oct.
24 'Nov. 24
(163) 13
(390)
23
(ICH)
7
(154) ^5
TH. Nov.
25' Dec. 15
(42) 12
(100)
22
(52)
S
(145) H
IV. Dec.
16-Dik'. 31
(73) 10
(61)
in
(70
10
(Si) 16
(395) "
(627)
22
im)
S
(4S6) 10
^
Paris.
Pnlkowa.
San Fern.
Toulonae.
UptaU.
I.
t
(243) •<»9
«
(»43)
I
*oi9
(216)
^015
(39) 4
II.
(390) "
(14) -on
(334)
22
(295)
21
(149) 1
lit
(129) 13
(32) 15
(n8)
21
(156)
16
(97) J
IV.
(173) 'o
(15) 12
035)
16
(>94)
»3
(74) 1
3feMQ
(93$) "
(61) 13
t»30l
20
{^i\
i?
(359) m
Dec 1907. Vatahgue cf PIvotograpkic Star Places.
95
Table X.
« Average Duoordftnoe of Dec linn tioii«, in Dat«
GroapB,
Standard System miima—
•
ii|ti5-0t. 23
Bordeaux.
Catania,
Greenwich.
HelAingfors.
Northfleid.
(117) ''«o
(176) '-23
(70) '*o7
(74) '-lii
(35) -n
Oet a4-Nov. 24
(163) 12
(307) 18
ri04) 8
(154) 19
(57) 12
Nor, 25- Dec. 15
(42) n
(100) '21
(52) 6
('45) U
(35) J 4
Ber, 16-Dec. 31
(73) 10
(60) '27
(7») 8
(81) 18
(54) 14
M«iii
(395 J t*
(643) 21
(297) 8
(454) 17
(iSO 13
Pam
Fulkowa.
San Fern.
ToulouBe.
Upaala. MinneapoliA,
(345) "10
*'
U43) '•'7
(216) '-16
(39) ''19
(42) '-20
(390) 10
(14) "06
(33S) 20
(294) 18
{149) 16
(69) 18
(1291 15
(32) H
(118) 21
('55) 19
(97) 18
(32) 20
H tt
(rS) 9
(135) 18
(194) 16
(74) IS
(42) 25
pRfi 1934) n
161} 9
(834) 19
C859) 17
(359) i?
(185) 21
We may draw the following coiicluBions from these tablen : —
The concordance of the observations is fairly uniform along the
path of the jtlaiiet, though tbere iire coositlerftble exceptions in the
K.A/8 f?r»n) Heliingfiirs, MiimeJifkolis, Toulouse, and UpBalu,
The Greenwich and Pam places were fully entitled 10 the
finable weight which they received.
The Bordeaux (>Ia<'eR might also have received double wei^'ht.
ITse Northfield and Pulkowa places might have been given some
extra weight. But as they are chiefly w#5ll -observed repere stars,
Ibe effect upon the stoiidard system would have been small in any
Judged by their avernge lE'^cordance, the Catania and 8an
Famando places are barely entitled to the unit weight which they
rt'ceived. Attention has already l>een called to very large and
irregular dificordauce^ in the fi»rmer series {S,P,P* No. 5, p. 84).
The San Fernando plates have g<^nerally only a single expoeure,
menfluied in a single orientation, w^hereas other observatories usually
Ikftve three or four exposures, measuretl in at leaat two orientations.
A second of time is equivalent to ten fteconda of arc in declina-
tion 48^, which is close to the mean declination of the stars in
our standard system. A comparison of the figures in the above
table shovvK that the right ascensions and declinations are very
elnenly <»f the same average accuracy.
§ tZ, ProhaMe Error of the Statu lard System, — To obtain from
ibe ttlncive discussed di.scordances an exact estimate of the probable
errt^r of a star place in our standard system would be very laborious,
if not inj practicable, and the labour is not warranted in the present
ftage of the work*
96 Mr. A, R. Hinks^ Construction of a Standard LXvm. 2,
We may, however, estimate the probable error rough I j» as
follows : —
The average discordance uf the contributions to which unit
weight has l>feen given is wc?ll under 0**20. A luajoiity of these
depend upon one or two observatioua, and have received weight i.
The probable error of a contribution of weight i is likely to be not
greater than o'^^aOj probtibly lens. And a star is not admitted to
the standard system unless its weight is at least 4, while the
average wei;4ht i:^i 7 or 8. The prtibable error of a standard place
in each co-ordinate will therefore l>e well under o^'io, but how
much under it is itii possible to say at present.
§ 19. The me 0/ the Htandard System. — Th*5 standard system
provides fairly completely for the reductiou of the Crossley Reflector
plates, funtishitig from 3 to 12 comparison stars along a good part
of the plauet^s path. These sttir places have been already^ com-
municateii to Professor Perrine. There are thin places in the
catalogue, due to bad weather in Europe while it was tine at Mount
Hamilton ; these must be filled up if possible. By the kindneas of
the Astronomer Royal, a considemble part of the material required
has been already supplied from special measures made on Green-
wich plates, which are not included in the above discussion.
The catalogue also provides for the complete reduction of the
Cambridge, Oxford, and Tashkend series, and any others that may
be outstanding.
Further, I propose to try the effect gf making the equivalent of
a re-reduction of the published f>hotographic pkces, in tbe following
way :— 1
The programme of Monsieur Lr^ewy included the meaauremoO^H
of all stars in a sqimre of 20', liavrng the [>lanet at its centre ; thetV
were reduced and published se[>arately for each plate. The ** cariy
de vingt minutes*' genemlly contains six or eight of our standard
system stars, sometimes as many as twenty, and we can compare
the individual plato places with those in the standard system* If
anything abnormal has happened to the plate, either in making or
in reduction, the effect upon the mean of a group of stars scattered
over the square w^ould be very nearly the same as upon the planet
at its centre. And if we apply to the plauet^s place a correction
derived from the mean difference Standard System minus Stars of
the Square, it seems that we ought to get rid of any troublea of a
systematic nature in a very simple way.
Suppose, for example, that one telescope htis an optical distortion
that di.^pJaces the centre of the plate with respect to its edges ;
that another has an optical distortion that skews the plate and
makes the scale value in x and }j sensibly different, so that there is
a large and systematic difference between a six constant and a four
constant linear reduction j suppose that a third observatory has
used a quite wrong expression in calculating the second order
refraction corrections ; and thut itj the work of a fourth the errors in
the solution of the plate are undesirably common, ^ — and these sup-
positions are not eo extravagjanl aa lUey may a^ipear, — the simple
Dea 1907. Catalogue of Photographic Star Places.
97
|i7oeefl8 of reduction to the standard system by means of the stars
10 the 20' aquare will avoid the ayatematic effects of all these un-
toward circumstance;?, and will give a result equivalent to, tbough
not so smooth as, a complete re-reduction.
The standard system will also be indispensable for the reduotian
fif the micrometric comparisons of the planet. In Paris Circulars
8 und 9 Monsieur Loewy published a list of stars used in these
compahsons, and desired that they should be measured on the
photographs whenever possible. As a result 4jf this, the standard
catalogue contains good places of a very large majority of these
stars, and provides almost completely for the reluction of most of
the micrometer series. The only serious difficulty may be fo\ind
ia reducing the observations made at Washington and Y^rkes
Oboeryatories, where they used some stars so faint that they are
not found on the ordinary photographs. These stars wer*j all
marked on charts sent to Professor Perrine for use in selecting his
oomparison stars, and he has succeeded in finding and measuring a
large part of them on the Crossley plates.
We have therefore reason to hope that this standard photo-
graphic system of stars may provide, directly or indirectly, for
the complete reduction of the Eros observations of 1900 on a
homogeneous system.
The extension of the system lo the early mouths of 1901 is
mmking excellent progress.
§ 20. As b^^fore, the additional assistance required in this work
haa been provided by a grant from the Government Grant Fund of
the Boyal Society.
Acknowledgments are also due to Miss Julia Bell, Qirton
Collegei who has continued to perform a great part of the computa*
tions ; and to S. E. Bowd, who has made the card catalogue and
aMi8U«d efficiently in all parts of the work.
Cambridge Obstrcatorf/ ,
1907 Noiytmbir 19.
98 Prof, Turner, Positimi of Sun's AjHs of Rotaiwn, LXTin. 2,
/■
We Q^i the Position of the Stm^s Axis of Hotation^ as deduced
fnjffi Greenwich Stm-spof Meiistires 1886-1901. Ptipers of
the LU,S.K Computing Bnreau^ No. I. By H. H. Turner,
D.Sc, F,R.8.» Sftviliau Professor.
1. The f>reaent note is to be regarded rather a» a statement
of problems than as a solution of tlieiu. A discussion of the
Green wich sun- spot measures was begun a few years ago, as a
necessary preliminary to computations in connection with the
International Union for Solar Research ; and it ia being continued
as the work of the Computing Bureau^ of which the writer vrnsf^
asked to take charge. But the resources of this Bureau are at
present very slender, and the time of the Director is much
occupied with the printing of the Astrographic Catalogue, so that
it may be some time before a definitive discussion is completed. •
Meanwhile the following provisional statement may be of interest ;
it has been drawn up in response to one or two inquiries for
information. Another note will shortly be preaente'l» dealing wiiti
the velocity of rotation*
2. The material used is taken from the Greenwich sun-^pot
ledgers, 1886-1901 inclusive. Later publications, especially the
welcome volume of " photoheliographic results, 1874-1885/' which
has just been issued^ will allow of a cunsidenible extension of the
discussion ; but thc^se were not available when the following
computations were commenced. The di»cuj^sion was confined to
spot groups which were seen for a period of ten days at least ;
and no notice ia taken in what follows of the identity of recurring
groups. The longitude and latitude on each day were compared
with the mean values given in the ledgers; and the differences
were tabulated under each 10' of distance from central meridian,
so as to show the motions in latitude and longitude. The spots
were further grouped acconling to their latitudes, in groups o*
to 10°, 10'' to 15*, 15* to 20", 20° to 25', and over 25', N. and
S. latitudes being kept separate,
3. When we have a set of mean residuals for each 10' of
longitude, various methods may be proposed for deducing the
mean drift from the series- Take, for instance, the following series
of mean residuals in latitude for spots in N. latitudes 0° to 10*
in the month of October (all years combined).
Dec. 1907. fnyoi Greenunch Sun-spot Mmmres 1 886-1901. 99
Dist. trow
Oentral Merld.
Mean
itesiil.
- 90 to - So
>0'50
- So to - 70
+ 3&\
-70 to -60
^ 73 +0*40
- 60 to ^50
^ 20;
- 50 to ^ 40
4 27\
-40 to '30
+ '23 -+ '22
-30 to -30
4. nej
-30 to - 10
- 10 to 0
^ ''n^o6
- '04)
DUt. from
CetJtnil Merid.
Mean
aeild.
+ 90 to -fSo
•
+ 80 to +70
-0-381
+ 70 to +60
•34-
+ 60 to +50
- •44J
4- 50 to +4a
- -33)
+ 40 to + 30
-•04 -
+ 30 to +20
- -34]
-f 20 to + 10
4 to to 0
^ •3n_
^is
•24
Differences of metliod would turn chiefly upon the relative
weights to be assigned to the outer and inner residuak* The
outer give better intervals for measuring the motion ; but, on the
other hand, they are affected by larger errors, owing to fore-
abortening, and ix)s.sibly to optical distortion. We shall do no
hM-m by making two separate deterniiiiations of drift from outer
and inner groups and comparing the results. If we reject tb«
outermost groups (80' to 90') as too much foreshortened, and
take the mean of the next three, we get results for +65'' and
- 65', a difference of 130" in longitude. The next three groups
will give us mean values for +35* and -35*, a diiference of 70'.
4. A drift in longitude may be taken to increase steadily with
the time, and hence the differences for ±65' should be to those
for ±35' in the ratio of 13 to 7. Thus, if the aWve figures had
related to longitudes, the mean drift per 10" would have been
(-o'-jS • o' 40)/i3= - o'-o6o from the outer groups and
( - 0**24 ^ o''22)/7 = - o°'o66 from the inner groups.
5* The same might be true of a drift iti latitude if it were a
(ihysical drift; but if it is an apparent drift, dtje to a faulty
determination of the Sun^s axis, these formula? will not apply. The
error due to a wrongly assumed aiis is of the form k sin (^4- 65") -
Ar sin (^- 6V)= 2A;co8 ^ sin 65^ in one case, and (similarly) 2k
c»>B ^ sin 35 in the other. The ratio is thus sin 65'/Bin 35* = I'sS
instead of 65/35 ~ ^'^^•
6, To take the latitude tirst : if we have adopted a wrong axis,
Ibe effect will be a spurious latitude drift, varying in amount as we
go round the Sun during the year. The drift will in fact be, rfmghly,
#imilar to the Sun's drift in declination, if for a moment we regard
the equator as an erroneous determination of the ecliptic : it will be
northwards at one time of year and southwards fcix months later,
with no drift midway. Hence, if we arrange the results according
to th© tinie of year» they will form a cycle. The resnlia for latitude
were accordingly collected in monthi^, each spot being assigned to
the calendar month in which it appeared on the central meridian ;
and the mean drifts between the meridians above 6|iecitied ar«i ^v^u
in Tabled L and IL, which require no ftirther explanatioTi,
i'^^i
lOO Prof, Turner, Position of Sun*8 Axis of Rotation^ lxvul 2,
Table I.
LatUudt
drift between +
65' ami
-65'tn
each month {of the years
1886-1901).
Latitude.
25- -
20^ -
15' -
lo' 0'
+ io' +1$'* +20' +
25-
Jan. +78
-94
-77
-25
-23
-85
-87
-33
1 -32
Feb. +71
-67
-13
-7
-29
-7
+ 1
+ 30
-118
-
Mar. -67
-15
- 20
-39
-37
43
-33
-76
' +25
+ 1.
Apr. - 28
-
+ 17
+ 14
-4
-19
-3
+ 22
+ 13
-
May +15
+ 76
-54
+ 3'
+ 77
-5
0
+ 2
-29
-
June —
+ 5
-54
-17
+ 74
-20
-17
- 2
+ 33
+ 1
July +115
-18
+ 42
-75
4-18
-19
-25
+ 93
: "'^5
■r2
Auk. -43
-27
- 12
-37
+ 6
+ 90
-41
-59
'. +16
-
Sept. +115
-29
-53
-13
-28
-33
-43
+ 13
1 +50
-
Oct. -113
-115
-7
- 16
-3
-78
-75
-115
-188
-
Nov. - 15
-159
-52
+ 33
-41
-59
-124
-116
1 -.48
Der. -82
-66
-57
- 112
-22
-13
0
-57
-119
-29
+ 70
-f 1
Mean —
—
-28
-28
-47
-22
—
—
The unit in the table is o^'oi, and the figures are differences
between the mean residual at +65" and that at - 65 \ The row
of figures at the top represents solar latitude.
Tablk II.
Latitude drift heixoeen + 35' and - 35" in each mmUh (of the years 1886- 1901).
Latitude. -25** -20- -15" -10' o** -r 10"* +I5' +20" +25*
Jan.
+ 30
+ 5 '
+ 20
-18
-42
-39
-48
-25
+ 87
-5
Feb.
+ 32
-30 '
-8
-16
-6
-26
+ 12
+ 22
-65
-f
Mar.
-35
-3
-9
-26
-19
-23
- 20
-28
+ 30
^
Apr.
-22
+ 107
+ 3
+ 9
-°
- 15
-4
-15
+ 3
-
May
+ 28
- 21
- 50
+ 5
+22
+ 34
+ 25
+ 45
-42
-
June.
-85
-27
-25
-30
+ 58
+ 4
-6
+ 6
+ 49
a.
July
+ 25
+ 15
+ 38
-6
-5
-29
-18
+ 50
-lOI
+ 1
Aug.
+ 22
-25
- 12
-57
-6
+ 30
-39
-25
+ 15
+
Sept.
+ 118
-5
-40
-9
+ 28
- I
- 10
-y!
^IZ
+
Get
+ 50
-30
-55
-5
+ 7
-46
-38
-19
-193
-f
Nov.
+ 55
-54
-42
+ 53
-zi
-16
-61
-86
-85
Dec.
-98
+ 10
-25
-57
-48
-67
-32
-29
-43
+
Mean —
17
»3
16
- 12 —
Multiplying the coeHicients A and B by h cosec 65* for Table
/., and ^ cosec 35° for Table II., v:e get the error of the Sun's axi^
)ec. 1907, fnmi Gr^nwich Sun-spot Measuff-es 1 886- 1 90 1 . 101
hich we may tjow exiiress (aa Carringt<iii does) in miiiEtes of arc.
The separate determinations are given in Table III,
Excluding, at any rate in the first instance, the outside groups
(for latitudes above 20*), we can now analyse the remaining 6
columns in each table harmonically, to find an expression of the
form — '
A sin ^ + B cos ^ + C,
where ^ ^ 0 for the middle of January,
Tablk 111.
lA««tldtst, -20' -15' -10' O* +IO* +1S* +20* Mean.
+ 2'9
+ 37
4 6*6
+ 4^
+ '4'5
+ 12*1
+ 7*3
+ 7*1
-0-8
+ 6*5
+ 57
+ 12'I
+ 14'5
+ 75
-5*8
- ro
-11-6
- J2*0
-9'S
-97
-8*3
+ 0-3
+ "■3
-167
-137
"4-9
- 10*6
-7-2
I from TMr I,
M „ II.
B from Table L
k ■
^H Inspection of Table IIT, suggests the following conclusions : —
^^ (a) The determinations from meridians ±65* and ±35* are
^itisfaetorily accordtint. Thus the Sun's disc may be treated as
free from distortion for the |»urpose in view.
(b) The adopted axis is sensibly in error for the period under
ssion,
r) The different zones give sensibly different values for the
, zones - 20^^ to -15* find —15" to -10* being specially
nt. But the results seem really to fall into three groups :
-40* lO - to' - lO* to +10* + 10" ttl +30"
A +3''2 +5-8 +13-3
B -1-3 -i3'5 -3^7
The conclusion (e) was not altogether unexpected, for an
ection of Carrington'a material had indicated something of the
The material is given on pp. 240-242 of his volume
hservatiom of Solar Spots (published in 1863 by Williams &
ToTgate) : and if it is divide 1 into four groups according to the
le of the spots, we get approximately for his X and Y —
Latttades.
X
y
>4ir
- 3-8
+ 12*9
+ l$*tao\
- 9'4
h 10*2
O*t0 ' 1
5^
- 4-1
-15"4
^-ir
-lyo
+ 9*0
Mma - 8'1
+ 4*^
2 Prof. Turner, Position of Sun's Axis o/BokUion^ LXYIIL 2,
It thus seems doubtful what precise meauing can be attached
» the mean of such discordant values. On forming groupa cone-
ponding to those used in this paper there are still 'clear dia-
^rdances; but the whole question must be reserved for farthev'
3zamination.
Nothing has yet been said of the constant C indicated by th^
mean values of the columns. It will be seen that it is persistently
negative, the mean value from Table I. being - o**'25, and frooca
Table II. -o'*'i3. These values are consistent^ and indicate ca.
steady drift of -o^-qiq or - i''i4 for every lo* of advance acr
the disc. Carrington found a phenomenon of this kind, an 4
thought its reality so improbable that he set it down to some erro^i^
in reduction. His value was i'*5 for 30' of rotation, or 18' fo~-^v
a whole rotation ; and his direction was towards the North FoL^sm,
i.e. in the direction opposite to that here found. It thus beconk^^.;«
important to examine whether this general drift shows any cIo^^ku*
indication of change during our period (i 886-1 901). For tb.'S.s
purpose the material must be rearranged in consecutive years, T'^fT
in Table IV.
Tablk IV.
Drift in LcUilude between +65* and - 6$'' from centrcU meridian.
ear.
- 2$' - 20'
• -I
s- -
10* 0'
+ 10" + I
S** +20' +:^5*
1^86
-
—
-4j.
-137
+ 8u
-I4d
+ 27a
-579
—
887
—
—
—
-701
+ 29,0
-44
-653
—
—
388
—
—
—
-1282
-102^
+ 110,
-I45i
—
-
J89
-22
+ 301
-60,
—
-66,
+ 25,
—
—
— ""
J90
—
-68,
—
—
-21,
—
—
+ 65,
-33, ^^
591
+ 5la
+ 984
-279
+ 35i
—
-
+ 1%
-I2„
-4.U ^^
592
+ 2lO
-"4,a
-30,3
-26,
+ 573
-3511
-55«
+ 6,0
+ 5. ^'
593
+ 61,
-43n
-47'2n
-24j«
+ 2Ii,
-i6,„
-i9»s
-4l7
-836 '
594
+ 475
-25i
-40i«
-50-^
+ 3l7
-"a
-65,9
-7lB
+ 44
^5
—
+ 634
-49io
-5o,s
-3I14
-68,
-48«
-37,4
-26,
^
—
-425
-4io
-161C
+ 164
-955
-1273
- 122,
-»5i
^7
—
—
-5s
+ 33«
- 24ii.
-77i4
-79..
-
—
i9^
—
—
—
+ 3p
-261,
-i09«
-lOOrt
—
—
m
—
—
—
+ 20;
+ 40,
-232
-
-
~
XXJ
—
—
-
+ 6o.
-22,
+ 5-2
-
-
—
—
-—
—
A-\Ti
—
—
—
Dec 1907. from Greenwich Sun-spot Measures 1 886-1 901. 103
The anit in fcho table is o*"oi : tho subscript figures reprfisent
tbe number of spots included in the mean.
The mean values of tbe drift^ weighting all spots equally, are as
follows \- —
Ta^le V,
Ywr.
M«aa Drift.
No. Spots,
Vmt,
MeABDrflt.
Vo. 8p6ti.
1886
-0'04
37
1894
*24
ti8
it^j
•00
18
1895
- 40
94
1888
- -90
10
1896
- -39
49
1889
•34
lO
1897
•39
44
1890
*o3
6
1S98
- "47
32
1891
•02
S7
1899
+ -21
14
1893
- '30
107
1900
- -07
9
1893
' 19
135
1901
+ 'SO
3
There are some mdications of cbauf^e^ but the Bmall number of
c>li«ervatioiia in the terminal y«ara makes it difficult t«i pronounce
'^ilh certainty. The reduction of the material recently made
^-^^^ilable should ^o far to settle the point. Meanwhile we may
rn up the indications by taking means for four years as follows,
rrington's result being rendered comparable and added \ —
J^;'^'
^18'
Mean drift during a whoU rotaHon,
1886-1889 189&-1895 i894-tS97 [898-1901
♦ *♦ -30' -32' -56' ^30'
[^OTB, added December 28, — A provisional redui-tion of the
^"^Siilta for 1874-1885 shows that tbe drift is distinctly positive in
^o«e years, being smaller at the ends and large in the middle. An
'^^cillation of about 26 years' period with maximum northerly drift
^Wit 1S54, 1880, 1906, and maximum southerly alxmt 1867, 1893,
^oulil roaghly ht the facts ob^syrved hitherto.]
IC4
M)\ A. & EMin^ton^
LXVIll. 2,
Ow ike Mean Distances of the Groonibridge Stare.
By A, S. Eddington, B,A. M,Sc.
In a forraer paper * I have given some calculation & as to tW
mean distance of tlie atare of Groombridge^s catalogue for the pi
po»e of comparing the dietances of the two star-drifts, with which'
that paper dealt. The results obtained were, I believe, sufficient
to show that the two drifU must be at, roughlj, the same mean
distance from us, but there seemed no means of judging how
closely the actual numerical results cottld be relied on. Some
further reflection has, however, shown that the method haj; advan-
tages (as regards freedom from systematic error) which were not
at thai time noticed ; it also iticidentally furnishes an additional
teat of the two-drift hypothesis. I have accordingly developed the
resolts more precisely in this paper.
The principle of the method of determining the mean parallax
of a large group of stars is well known. It depends on determining
the apparent angular diaplacemetit corresponding to a known linear
displacement. For example, in Professor Kapteyn's researches
the parallactic motion has l^een mainly used as the known linear
displacement; if that is assumed to be the same for all the differ-
ent groups of stars discussed, the corresponding anL,'ulftr motion
IB proportional to the mean parallax of the group. In the present
case the mean peculiar speed (Le. the mean ifidividual motion,
irrespective of direction, which remains after all drift or ^parallactic
motion has been abstracted) is taken fur a similar purpose. If its
linear amount is assumed to be the same in all parts of the heaven?,
the angular amount ivill be proportional to the mean parallax of
the stars. We must, of course, be prepared for the possibility that
neither the parallactic motion nor the mean peculiar speed is
atrictly constant in different parts of the sky or for different
classes of stars. The determmations of ** hY" (or the ratio of the
drift motion to the mean peculiar speed) made in the previoog
paper throw some light on this question ; they appear to favour
the assumption of constant mean peculiar speed, but the teat is at
present a father rough one.
As the proper motions of the stars include not only thei
peculiar motions but also the drift-motions, the mean peculiar
motion cannot be found without mathematical investigation. The
theory developed in the previous pap«r enabled this to be done*
There are two stages in the calculation r — (i) The constants of the
drifts must be determined from the numbers of stars moving in
the different directions (without regard to the magnitudes of
their proper motions) ; and (2) from these constants the theoretical
relation between the mean peculiar motion and the whole mean
motion can he found.
For example, consider that division of the sky which I have
^^onihitf AVoti'ees^ voh Ixvii. p. 34, referred to liei«afler as * ' Synt^rfnii
^ " The portion especially denliii^* with mean difitanoes is pp. 55-5^
ir 1
klled Kegion B. In tig. i» A is for this region the theoretical
scurre of the kind conttidered in the former paper, in which the
liua vector is proportional tti the 7mrnl/er of s^tara moving in the
5orrf«[Jonding direction ; Ij is I he theoretical cnrve in which the
liQs vector is proportional to tlie mean proper moUmi of the etard
rcftving in the corresponding direction. The two curves are rather
licoilar; the bi-lobed character of B is readily recognised, although
elongations and minima are much less pronounced than in A.
Flo. I, — Diagrama for RegioTi B.
A and C — ^tbeoretic&l and observed curves, Bhowiug total number of prop^-r
Qtotioui in iliifercnt dir«ctioii4.
B iir»d D — theoretical and obacrvdd curved^ ahowing njean proper motion
in difrer«nt direirtiona.
It shouhl be mentioned that in drawing B the two drifts have been
iAsumeti to be at the &ame mean distance ; as the two lohes of the
curves corrcj^pond respectively to stars of the two drifts, it is clear
that if one of the drifts is nearer than the other, this will be shown
by the lobe of the curve B, which corresponds to that drift, being
exaggerated in si«e compared with the other. It is in this way
that the mean distancee of the drifts can he compared. The
(sunres C and D are those derived from observaliou, and are to be
eomymred reispectively with the theoretical curves A and B,
Althoogli our main purpose in this investigation is to diacu^fe U\^
diat&nce of the stars of the two drifts, attention may h^ caWiai to
io6
Mr, A, S, Bddvfigton,
Lxvm. 2,
the clear way in which, in this and in other regianSi the mean
proper rantinns aujiport the twodrift hyfMnhesfs. The evidence of
tlie ol'.'iervt'ii curves C and D respectively in favour of that
hypothesis must be reki^arded as, at least to a large exteoU
independent; it could hardly be expected, a jyriorif that the mean
[jroper motions would bo greatest in the two directiana in which
the iotal number of proper motions is {greatest It may be noticed
that the two drifts are slightly more prominent in the observed
curve D than in the theoreticiil curve B ; acme of the other regions
considered show this rather more strongly, and it appears to be a
general result. I have not been able to arrive at any satia factory
explanation of it.
For the other regions, referejice must be made to Table I. In it
will 1x3 found, for each of the seven rej^nons covered by the Groom-
bridge catalogue, the mean proper motion of stars moving in each
of twelve directions at intervals of 30°. (For forming the mean
proper motion in any direction, stors moving in directions within
15° on either side of it were used ; thus each direction correaponds
to a 30° sector.) Curves similar to D in fig. i could readily be
constructed from these data, and we should find that they are
clearly bilobed, indicating two drifts. Region D constitutes an
exception; for, since it contains the apex of Drift II., that drift is
not very apparent in it. The same thing may be seen by inspecting
th^* numbers iti the table : in each column there are two maxima
and two minima well indicated, and a comparison with the Tables
II » to VIL in ^' Sifstefnatii^ Motions** shows that they correspond with
the maxima and minima in the numbers of stars moving in the
different directions.
Table I
Direction e.
rajt Prt
*/xrr Moiii>m (rejecting highest eighth).
Eegloufl
Auid CDEF
B fttitl G
A
B
c
0
E
F
0
S iS
5-65
4-64
275
y^^
4'*2a
2*99
2'^
35 45
3*99
3'37
4*22
3*54
3*S5
472
2*11
65 75
roo
240
3-So
472
5 "24
676
,.6^
95 105
274
25»
261
5-04
472
3'49
2-93
125 135
311
2-57
VIA
yu
5-86
3*20
287
155 165
3*35
2 '90
2*82
376
6-42
294
209
185 195
332
2*54
274
3'«5
6 90
4*47
170
215 225
4-28
2*2 1
1*53
2*10
4-95
5^94
1*94
245 255
3 '50
2-14
I "94
271
4'35
4^8
2*92
275 285
249
I '54
r6i
2-07
206
4*39
353
30s
31S 3'8o
1*46
1*32
335 345 4'S4 3-60 2*50 376
277
5*49
3-8i
4-40
3*98 2-81
In calculnting these means, it is necessary to adopt some rule
for rejecting excessive proper mictions. The difficulty is to find
a limit wliieh will affect the two drifts equally. The rule which
Dea 1907. Mean Distance of the Groombridge Stars, 107
I bttT6 adopted, which seema to meet this, haa been to reject the
/utast eighth moving in each direction. That is to sav, if there
ire n proper motions in one of the twelve 30° Fee tors, I pick out
And reject the n/S high eat of these* and take the mean of the
mmainder. The net result must be nearly the sftrae a.s if the iie^re^t
»lar8 of each drift, to the number of ratbur more than one-eighth of
the whole, were reje(:ted. This means a much more ilrastic rejection
of high proper motions than is usually resorted to ; but some 8ucb
plan ^eems necessary if the more distant stars are not to he
dtogether outweightcd,
Each of the mean propter motions providas us with an equation
iavolviug linearly the unknown mean paralkxea of the two drifts
(tee ** Sifsteniatir. Motinng^'' p. 56, equation (i)). Thus for each
regioQ twelve equations were formi-d^ involvini^^ these two un-
knowns ; these were propt.^rly weighted and solved by least ^uarea.
T»bl© XL contains the results, ** d^" and
' (/g '* denote the distancea
wf the drifts. For the meaning of ** h ^' reference must be made to
the mathematical analysis of the former paper ; it is connected with
the mean peculiar speed of the stars. It is, however, the relative
mth«T than the absolute values of the distance that are of interesti
M that the precise unit used is not of great importance; but,
iwcepting Campbell's provisional value (20 k.m. jier sec.) for the
•peel of the solar motion, and my own determinations of the drift-
fiOQatanta, the actual mean parallaxes may be obtained by dividing
thenambers in Table 11. by 500, (It must, however, be retnembered
tfcatt great many near stars have been rejected, as explained above,
totliit the mean parallax has a rather artiBcial significance.)
Takle II,
Mian Pmr(Ulaj»!t.
(Ths qitantitids £-j and ^y tabulated ana the mtjan parallaxes miiltiplitid
^tfietor whote value is probably about 50a )
Rf^n
NJ\D.
R.A.
hdi
hd.2
h h
" It
A
0-20
0-24
2 96 ±'07
1*4 1 ±''3
B
20-52
22- 2
2-45i:^07
2^40db*ii
C
M
2" 6
2*39±*o8
2*6si*i2
D
0
6-10
3'35i*i2
3 "23 ±21
B
♦ ♦
Io~i4
3-65±'i4
4 78 ±'29
f
t*
14-18
374±'23
4 I5±-3I
0»
M
18-22
277db'i6
2S5±'iS
The eqiialilj of distance of the two drifts is evidently continned.
^- -rn £ is the only one in which there is any indication of a
l.-rable diflference between their distances. The proVmble
rrri^r- are of interest, not only as indicating the rehability of the
* The featricted region G (excluding auhdivision 7) was used ; £tje SyiUern-
elic MotUmSt p. 52.
io8 Mtan Distances of the Grooinbridgc Stars. LXTIIL 2,
results foundr but as a measare of the accordance between theory
and obBervation, for they are derived from the dbcordance of the
calculated and obserred mean proper mi>tioiid in the twelve
dire4!tioD8. Region B, which was represented in tig. i, ahows the
best agreement between theory and observation ; but it may be
remarked that, where the figreement is not so good, that is always due
to the phenomenon mentioned above — that the mean proper motioni
show the e0ect of the two tlrift-mutions more prominently than
calculation leads us to expect
Before we can rely on the valuea of the probable error giyeo in
Table IL, it is nece^^sary to consider whether a poasible systematic
error in the catalogue, from which the proper motions are derived^
may not lead to errors of imjtortance not included in the theoreti-
cal probable error. The conchisioii is rather unexpected; a
systematic error in the proper motions does not invalidate these
results. The reason m this : a systematic error affects the mean
proper niotion, and al-^o thy total number of proper motiona, in a
particular directiou ; owin^' to the latter error, we arrive at in-
correct values of the constants of the drifts; but it is not difficult
to see that, if these iucorrect values of the drift-constants are used
in forming the equations of condition, tliia will compensate for
using incorrect values of the mean proper motions. Looked at in
tioother way, the nnalyaiw was dest^^neU lo extricate the mean
peculiar motion from the systematic drift -mtaions with which it is
involved ; it at the same time eKlricates it from any j^Kiasible
systematic error which is hardly distinguishable in its efft^t
from systematic drift or parallactic motion. In 01-der that this
elimmatirm of error may tiike place, it ia necessary to use drift-
constants derived from the observed proper motions in the
particular rejjfiim considered, not those determined from an
examination of the whole s*ky ; this has been attended to.
Assuming that the two drifts are actually at the same mean
distance, and accordingly combining their parallaxes given in
Table II. with weights inversely proportional to the squares of
their probaljle errors, we have the following table of mean
parallaxes (multiplied by a factor) of the Groombridge stars in
different parts of the sky.
Taplk 111.
Variation ^ftht Mean Parallax u*ith Qfifariit Latilfide,
mj,^ti»t Metn Mean ParaUM
"**'^"- GaliMstfc LnWtude, (muHlplied by » «kotar)v
B
- 12
»-43
0
- 2
247
a
+ 8
2-67
▲
+ 27
3-06
D
+ 32
3*32
F
4^46
3-88
E
+ 66
V&l
Dec, 1907. Mr, P. H. Cowell, On Aticie^it Eclipses.
109
The mean parallax steadily increases with the distance from
the galaxy^ a result which ts in accordance with t!ie generally
ftoeepted ideas of tho distribution of stars, viz. that the increui^ed
niimber of stare in the low galactic latitude** is due to additional
otore distant aiars being visible, and not to any crowding among the
nearer statB. The table apparently indicates a gradual change in
the mean distance ; but^ as the regions are rather extensive in
Area, it 18 not definitely incompatible with the hypothesis thfit the
differences are caused by a belt of distant stars almost limited to
the galaxy.
On An^emf Edipm. By P. H, Cowell, M.A,, F.R.S.
I am much obliged to Mr. Crommelin for repeating my calcula-
tiODS in the case of six solar eclipses, and so setting the question of
Iheir accuracy beyond doubt.
The fact that emerges from the discussion of the eclipses is that
ikere is an unexpected rate of change in what may be termed the
*' nodical year,*' or period of revolution of the Sun relatively to the
Mian's node.
This abnormal rate of change may arise from secular changes
ill the motion of the Moon's node (other than that arising from the
ckaoge of the eccentricity of the Earth^s orliit round the Sun), or
from secular changes in the motion of the Sun, or, of course, fiom
a combination of both byptttheses.
The motion of the node, as found from observation, differs very
•lightly from the formula given for it by Professor Brown in
M,Nrt Ixiv, p. 532, This formula is differentiated and the secular
acceleration of the node obtained ou the supposition that the
eccentricity and inclination of the Moon's orbit are constatrt. We
know no reason why these (|uaiilities should vary, atid observation
Hhows that if they do vary, the variations do not exceed certain
hmits. It happens, however^ that these limits are snl:Bciently large
to admit of a considerable part of the unexpected change in the
nodical year being attributed to the motion of the node (at least
a» an alternative hypothesis), thus diminishing the part to be
ascribed to the 8un.
The formula +4"(T - 18*25)^ - i"'0 takes numerical values
4*i"'oin 1755 and 1895, and - i"'o in 1825, with lesser values
namerically at intermediate dates, A second of arc is not an
impossibly large quantity to attribute to systematic errors, or even
to unknown long- period tt'rma, and it is clear from Professor
XewoomVs table {Ast Qomd.^ p. 22) that residuals of over 1" can-
Diyt h^ avoided by any formulae.
Hence it must be understood that a possible change in tK^
eocttntricity and inclination of the Moo/j's orbit is put forward as
no
Mr, P. If. Cowell, (hi Ancient Eclipses LXVlli. 2,
au alternative suggestion. There are no modem obserTatiouH
capal)le of discnminatiog between various bypotheees, and, con-
versely, it is unnecessary to discriminate before approaching questions
of chronology. All that is necessary in that case is to verify that
certain empirical form u las fit the records in a way that canaot
reasonably be considered accidental.
It is a curious reflection that Oppolzer's formulie should hate
been put aside merely because they contain impossible niewi
motions. Because they are based on so much coincidence Jiod
because Uppolzer*8 numerical accuracy is beyond reproach^ there
must be some solid foundation beneath the superficial blemithes uf
impossible mean motions. If we discard Oppofzer's position of
the lunar perigee as not sensibly affecting the general agreement
with the eclipse records, and if, wherever a mean motion needs eor-
rection, we apply to Oppolzer's formulse some multiple of aoT + T*,
a quantity that vanishes twenty centuries ago, we get to results
doaely resembling miiie ; and I attribute the small differences to
the fact that Oppolzer nowhere claims to have satisfied but merely
to have imjiroveii the ^olar eclipses, and, I believe, he obtained
his formuke from the lunar eclipses.
Let the supposed variation of tlie principal elliptic term in th^
Moon's longitude be + a^'^j- in a century (i.e.^ x parts in 10,000) ;
and let the supposed variation of the principal term in the Moon'?
latitude be + i"*% in a century (i.e., y parts in 10,000), and let
z* be the (sidfreal) secular acceleration of the Sun's longitude, then
+ 6"'2^-2''%-h/' = 3"*6±o"-5 . _ , . , (i),
the right-hand ^iA^, being determined by the eclipses, and modflro
observations indicating that ;:i: is less than 0*2 and ^ less than (yy
In this way the solar eclij^^^ses are compatible with a secular
acceleration of 2" for the Sun,
If the underlying cause be tidal friction, there ia nothing
improbable in the suggestion that slow changes are caused in th«
eccentricity and inclination of thts Mounts orbit.
The present tables would expose on an average about one-teulh
part of the Sun^s diameter, and these 200" are reduceil to leas than
50" by a single empirical term in a large number of cases. The
suggestion that this is mere chance appears to me un tenable.
When the observations of the eighteenth century present a diflScuUy
of one second, what is one second against two hundred f The om
second may be evidence that a particular hypothesis requires
modification, but that is aih I believe equation (i) exhausts every
geometrical possibility.
igo/.
The Perturbatiam of Halle t/s Comet in tJie Pa^t. — First Paper,
The peri oti 1301 to 1531.
B7 P. H. Cowell, M.A,, F.R.S,, and A. C. D. Cn.mmelio, B.A.
We commence this paper by expresaiiig our great indi'btedneaa
to I>r, Smart, F,R.A.S. ; to Mr. R R. Cripps, of 22 Horusey Rise
Gfttdeos, N. ; and to Mr. Thomas Wright^ of 39 Cringle Road,
LsTenshaJmef Mancli ester ; who are really eti titled to he considered
■4 joint ttutbors, aiuce tliey have carried out hy far the larger
ponioo of the mechanical (|uadratiircs, the results of which are
given below. Without their co-operation the completion of the
jcalculatioiis would have been indefinitely delayeil ; and they are
"^ gain offering their help in carrying them back to a still more
dig taut dale.
The calculation of the perturbations of thia comet haa already
been carried back to 153 1 by de Pontecmilant : the identity of the
two apparitiona before that (those of 1456 and 1 3 78) h univermlly
admitted; before that date Dr. Hind has given (M.N,, x. p, 51) a
liat of conjectured identifications, some fairly certain, like those of
4S*f 7^^» '*45i others admitteilly vague and uncertain. It
occurred to ua that new light might be thrown on the nuestion by
carryitig back the calculation of tht? perturbations as far as
posaible, and seeing whether a syfficiently accurate correspondence
exxsied between the conjectured and calculated dates» It is fairly
eTidetit that, to bring the labour of computing a large number of
revolutions of the comet within reasonable limits, some abbrevia-
liooH must be introduced, and the following was the plan adopted.
(i) For the purpose of computing the perturbatioos, the comet
in e%ch revolution was assumed to move in an ellipse of constant
©ccentricity (experience having ahown that the perturbations in
f^ocentricity are always small), and with a major axis corresponding
Ui the o I served period.
(2) The perihelion and node were supposed to change
uniformly from revolution to revolution, the rates of change being
deiiuced from the accepted elements of the comet from 1531 to
fgio: subsequently these rates were moditied by the use of M,
Laugier's discussion (CM., vol xxiii,) of the apparitions of 451
and 760, for which fairly definite statements of position are found
m the Chinese annals. M. Laugier has been able to represent these
ohBerYationa exactly by elements differing but little from those at
the present time. Curiously enough, he does not print his
nts, but he gives the longitudes and latitudes calculated from
ii, and the elements must be very approximately as foUovra —
r 12
Messrs, Cowell and Crommelin,
LXV^I
(the old system of comet elementa is here employed^ mb iz^
convenieat for our {jurpose) : —
T = 45» July3'5
T=76o
June i
CJ = a84-
n = 289'^
a =32 5 -Eh^ 45>
«=36 5
Eq\ ;
i = i6
»-i7
^=o*6o
^=o'6o
The following are the collected values of nj, JJ, t, reduo
the Equinox of igto:^ —
ST a *
45>
304-8
53-3
16
760
305-0
S2'5
17
1378
306^9
54'67
17 9
1456
305-26
50*08
17 '62
1531
306*47
S077
17-00
1607
'3oS'4i
52*66
17 14
£6S2
305-09
S4'35
1776
1759
305*27
55*92
1762
1835
30555
56*19
1776
1910
303*64
57-18
1778
ABsnmed change per re* \ .^
volution of tha aomet^ /
•06
+0*15
The secular variabioii of i haa been ueglecbed altogether in t>l
period tkivv under diacusaion, as it appears to be too smaU ^
detiuce with certainty, considering the roughnesa of the elemeS|^
for till the apparitions before 1681. ^M
(3) The co'Ordi nates of the planets referred to the corneal
axes are assumed to repeat themselves at unifnrm ititervala, "W
the hiterval for jt\ tj la taken slightly different from that for t.h
allow for the adopted motions of the perihelion and the Dode.
Period for of, jf\
Perioa for /,
d
Venus
2247005
2247023
Eartli
365*5544
3652614
Jupiter
4332*47
4332*86
Saturn
10758*6
107607
Uranus
30681-3
30700*6
Neptune
60167
60338
In consequence of the change in the period and major
the comet's orbit, it is more convenient to use the ordii
Deo, 1907, Ferturbatiom of ffallet/s Coymt in i/te PasU 1 1 3
astrooomioal unit of length aod the mean solar day aa tbe unit of
time. In our previous pai>er8 ou the perturbations by Jupiter and
Saturn 1835-1910 (M.N., Ixvii. pp. 386, 511) every quantity
tabulated wus of zero diineusiuns in sp^ce and lime.
(4) In the case of Jupiter and Saturn, the method of mechanical
qttiidratures ia used for values of u (the comet 'h eccentric anomaly)
6t>m o* to 90*, and from 270** to 360°, For the outer half oi the
orbit the definite integral method described in the above paper
(P* 39') ^^ employed; since the eccentricity of the comet^s orbit
is treated as constant, all the values on p. 409 can be used unchanged
except those relating to the position and motion of the perturbing
planet ; it may be noted that — , iL —^ — ? » - -?- vary as - »
a a na (it na dt a
The portion of the perturbations in the outer half of the orbit
that we have denoted by V . (p. 391) is neglected altogether ; this
uiay make an error of a few aays in the calcukted period, but nut
au^oient to cause &nj doubt as to the identity of aa obseived
comet.
The intervals of u for which the calculation a are made are 4 J'
ht Jupiter and Saturn, 9" for Uranus, 18° for Neptune (the
calcalatioua for these two planets being made throughout the
whole orbit), i' for the Earth and Yeiius (the calculations for
fiiese two planets being made from the values of M o" to 30', 330*
*--» 360').
(5) We have omitted the discussion of the perturbation of
^^ Q, t, havLnt; merely found the quantities that come directly
Ic^t^ th« periodic time. '"^^1
The foDowiug are the assumed co-ordinates of Venus and Earth,
'^^^erred to the axes of the comet*8 orbit ; they are deduced by a
**^«^3ple transformation from those given by Stratford in the Supple-
*^^9int to the Nautical Almanac for 1839, and are in units of the
5 *xl decimal ; —
-»alkol>fty.
Vonti*.
Eni-th.
X'
y"
z
X
y'
r
2391492
-54S
-452
4-122
^^9
-053
-296
94
569
419
134
966
087
299
96
SS9
386
146
961
121
302
98
606
3S2
158
955
154
304
1500
624
317
169
948
187
305
02
658
279
179
941
220
306
04
650
242
189
932
^53
307
q6
660
204
199
922
2S6
308
08
668
165
ao8
910
3i8
308
10
674
125
216
89S
349
308
it
678
085
224
S85
380
30S
14
679
045
23 »
S71
4i'
307
2191516
-679
-004
+ 237
+ 856
-442
-3C6
8
u
Mes
9n CouH
MandC
frommd^
i»,
LXyiE
Julian Dij.
Vmui.
■utti.
^" 2f
?
f-
»'
■ ^ '
t .
2391518
-676
+036
+242
+840
-472
-304
20
671
075
247
822
501
302
22
663
"5
250
804
530
300
24
654
155
253
785
558
298
26
643
194
255
765
586
295
28
631
233
257
744
613
292
30
615
270
257
723
639
288
32
597
307
256
700
664
284
34
578
343
255
677
689
280
36
557
378
253
653
713
276
38
534
412
250
628
736
271
40
509
444
247
602
758
266
42
483
475
242
576
779
261
44
456
504
237
550
799
255
46
427
532
232
522
819
249
48
397
558
226
493
838
244
50
36s
582
218
464
855
236
52
331
604
209
435
871
229
54
297
624
201
405
886
222
56
263
643
192
375
901
214
58
227
660
182
344
914
207
60
191
674
172
312
927
199
62
154
686
161
281
938
191
64
116
696
149
249
948
182
66
078
704
137
217
957
173
68
040
711
124
185
965
164
70
-002
714
III
152
972
155
72
+037
715
098
119
977
146
74
075
714
085
086
981
137
76
113
712
071
052
983
127
78
150
706
057
+ 019
986
117
80
187
698
042
-014
987
107
82
223
688
028
047
987
097
84
259
676
+ 015
080
985
087
86
294
662
OCX)
114
982
077
88
329
646
-014
»47
978
067
90
362
628
029
179
972
057
92
394
608
044
211
966
046
94
424
586
058
243
958
036
^391596
+453
+ 56*
-072
-275
-949
-025
BI^^^^H
^^1
^
■T'^j
Dec 1907,
PerturbaiioTis
ofHalley*s
Cornet
in ths Past, 1 1 5
1
3391598
VenttB.
Emh
■
+482
+ 537
t
-086
it
-306
y'
•939
H i6cx>
509
510
099
337
928
-004
^^M
H 02
S34
481
112
3^
916
4-007
^H
H
557
45 1
124
400
903
017
^^M
B
578
419
^37
430
sss
028
^^M
1
598
386
149
459
S72
038
^^M
H
616
35^
161
488
855
049
^^M
^1
632
317
172
515
838
059
^^M
H
646
281
183
543
819
070
^^M
1
658
244
»93
570
799
080
^^M
1
668
207
202
596
778
090
^^M
^1
677
169
211
621
756
TOO
^^M
^1
683
130
219
646
734
no
^^M
1
687
090
226
670
711
120
^^M
H
688
050
233
693
6S7
130
^^M
K ^
688
+ 010
239
715
662
140
^^M
^^ft ^
686
-030
244
736
636
t49
^^M
^H ^
682
069
249
757
609
iS8
^^M
^^P 34
675
108
253
777
5S1
167
^^M
^^ 3fi
666
147
256
796
552
176
^^M
■
655
1S6
258
813
5^3
184
^^M
■
643
224
260
829
493
192 !
^^M
1
628
262
360
844
463
200
^^M
^^^ 44
611
299
260
858
432
208
^^M
^B^
593
335
259
871
401
2x6
^^M
^^^ 4B
573
369
257
884
369
223
^^M
■
551
403
254
895
337
230
^^M
■ s^
5*7
435
250
905
304
237
^^M
1
502
466
246
914
271
243
^^M
■
475
495
242
922
237
249
^^M
■
446
523
237
929
203
255
^^M
■ 60
416
550
231
934
169
260
^^M
1
3SS
574
224
938
'35
26s
^H
^^64
353
597
2l6
941
100
270
^^M
^^K 66
3«9
618
20S
943
065
275
^^M
■
^85
63$
199
944
-030
279
^^M
■
250
655
189
943
+ 004
283
^^M
1
214
670
179
942
039
286
^^M
1
177
6S3
168
940
074
2S9
^^M
Kj,9i676
-K J4D
'694
-1S7
-936
+ 108
+ 2^2
1
Ii6
Mestn, CowM and Crommelin,
UVIIL2.
JnliuiDay.
Venus.
Eartb.
«*
y
t
' 71
V
t^
3391678
+ 103
-703
-145
-931
+ 142
+ 295
80
065
709
133
925
176
297
82
+037
713
120
917
aio
298
84
-on
715
107
909
244
299
86
049
715
094
899
278
300
88
087
713
080
888
3"
300
90
125
709
066
876
344
300
92
162
702
052
863
376
300
94
199
693
038
849
408
300
96
236
682
023
835
439
299
98
271
669
-009
819
470
298
1700
305
653
+006
802
500
296
02
339
635
020
784
530
294
04
372
616
034
765
559
292
06
403
595
048
745
588
289
08
433
572
062
724
615
2S6
10
462
547
076
702
642
283
12
489
520
090
680
668
279
14
514
492
103
657
693
275
16
538
462
116
633
717
270
18
-561
-431
+ 129
608
741
265
20
...
...
...
582
764
260
22
556
786
255
24
...
...
529
806
249
26
...
502
826
243
28
...
474
845
ni
30
...
...
445
863
230
32
416
880
223
34
...
386
896
216
36
...
356
911
209
38
...
...
326
924
201
40
...
...
295
936
193
42
...
264
948
185
44
...
...
...
232
959
177
46
...
200
968
169
48
...
...
168
976
160
50
...
...
...
136
983
151
52
...
...
...
103
989
142
54
...
...
071
994
»33
2391756
...
...
-o-i^
•V^T
+ 124
)ec, 1907. PeHwhaiiom of Ealley's Comet in the Pasi. 1 1 J
60
62
64
66
68
70
74
76
78
So
82
84
S6
8S
94
96
98
02
04
06
oS
10
12
H
16
18
20
22
28
30
3^
34
"3391^3^
Vcnu*,
Earth.
jT
V
t
-005
+ 1000
+ 114
+ 028
1001
104
061
lOOI
094
094
1000
084
127
998
074
159
994
064
191
989
054
223
983
044
355
977
034
987
969
033
318
960
«3
34«
949
+00 J
379
938
-008
409
926
018
438
913
029
467
899
039
496
883
049
524
866
059
Sl^
848
069
S77
839
079
603
810
089
629
790
099
654
769
109
678
747
119
701
724
t2S
ni
700
137
745
676
146
766
651
155
786
62s
164
804
598
173
831
571
181
S38
543
189
854
515
197
870
485
205
885
455
213
898
425
220
910
394
227
921
363
334
931
332
^^
+940
+ 300
-046
tl8
AftfSfra Cowdl and Cr&mmdin,
LXtia 2,
JutUo Day.
Vonui,
£utli.
«r
V' t 1^
M'
f
3391838
+ 94»
^^26S
-2S2
40
955
235
^58
42
961
2iy%
264
44
966
169
269
46
969
136
274
48
972
IQ2
279
50
973
069
283
52
974
035
2S7
54
973
+ 002
290
5<5
971
-031
293
S8
968
066
296
60
964
099
299
2391862
+958
'I32
-302
The co-ofdinatea of the comet itself are found from the table
{MM,^ livii, \u 387) by multiplying -, ^ by a, ofting the apecial
value for each revolution, aod the number of days from |>erihelioa
to each value of w by multiplying ni by ^^" ^^" ^ ^ •
0*203'"
The co-ordinates of Jupiter are found from the table {M,N.^
Ixvii. p. 394) by multiplying "l, ^, - by 177. The foUowiag
a a a
tMv gives the Julian days corresponding to certain values of g' : —
45
90
'35
tSo
JialUn t)Aj.
2390645
11S6
1728
2269
2811
225
270
315
36a
JulUa Day.
2393353
3894
4436
4977
The values for intermediate degrees may be found with
sufficient accuracy by reckoning 12*^ per degree from the nearest
table valuB. The co-ordinates of Saturn ar« found from the similar
table, referred to (but not printed in detail), A/.iV., Ixvii. p. 512.
As the forniulce on whith the table is bas^d are given there, the
table is not printed here.
As the perturbations by Uranus ami Neptune are always t<mall,
approximate co-ortli nates suffice ; those of Uranus are taken from
de Pontt^coulant (Menvdre sur ie caleid dm perturbations de la
eomkie de Hallet/^ 1829, pp. 37, 38, 48), They are as foUowap in
units of tht? first decimal '. —
■^^^^^B
^^1
Dec 1907.
Perturbations of ffalkys Comet
in thi
J Past.
^1
JiilUo D^.
JI55S00O
+ i87 +26 -55
Jalliin Dfty.
2369400
7f
-90
'171
+07 ^H
300
188 IS 57
700
100
165
^H
6cn
1S9 +04 58
2370000
109
158
^1
9QO
189 -08 59
300
117
151
^1
2359200
188 20 60
600
125
143
^H
Soo
187 31 61
900
132
ns
^1
Sop
185 42 62
2371200
140
126
^1
2360100
fSi 53 62
SCO
147
116
^1
400
179 64 63
800
153
106
^1
700
^n 74 63
2372100
15S
9^
^1
2361000
171 84 63
400
162
86
^1
300
t66 94 62
700
j66
75
^H
6dD
160 104 62
2373000
170
64
^1
90D
154 113 61
300
i73
52
^1
2563300
147 122 60
600
J7S
40
^H
500
140 131 59
900
^7S
29
^1
800
2363100
13^ 139 58
124 147 56
2374200
500
176
176
17
-05
^1
^1
400
116 155 54
800
175
+08
^1
700
107 t6i 53
2375100
174
20
■
300
98 167 51
89 J 73 49
400
700
172
169
32
. 44
^1
^1
600
79 178 46
2376000
165
56
1
900
69 183 43
300
160
67
H
2365200
500
59 iS7 41
48 190 38
600
9CO
154
148
78
89
^1
800
3366100
400
700
37 193 35
26 195 32
15 196 28
+04 196 25
2377200
500
Soo
2378100
141
133
125
iiS
99
108
tl8
127
1
^1
2367000
- 07 196 22
400
109
13^
^1
300
tS 195 rS
700
too
144
^1
600
29 194 14
2379000
91
151
^1
900
40 [92 t I
300
Si
157
^1
23682C0
500
SO 189 07
60 186-04
600
900
71
60
163
169
^1
800
70 182 00
2380200
49
nS
■
2369100
'80 'S^T ^oj 1 23S0500
-37
+ \7^
"rW ^M
120
Messrs, C&uM and CrommeUH,
LxvnL 2,
Jnllan Dbj.
238o8cx>
-25
+179
+30
Julian Daj.
2385000
9f
+ 124
y
+ 142
.22
2381 100
14
181
27
300
133
13s
25
400
700
-02
+09
183
184
24
20
600
900
141
148
127
119
29
32
2382000
21
184
17
2386200
155
no
35
300
32
183
13
500
161
100
38
600
900
43
55
181
178
09
05
800
2387100
167
172
90
80
41
43
2383200
66
175
+ 01
400
176
70
46
500
77
172
-03
700
180
59
49
800
2384100
87
97
167
162
07
II
2388000
300
183
185
48
37
51
53
400
106
156
14
600
187
26
55
23S4700
+ 115
+ 149
-18
2388900
+ 189
+ 15
-57
The perturbations prodaced by Neptune are still smaller than
those of Uranus, and, the eccentricity of its orbit being small, it
has been considered to move in a circle. The following are its
co-ordinates at intervals of 6° of longitude, or 1003 days, in anits of
the first decimal : —
rnlianDay.
If
y
t
Julian Day.
7i
y
t
24I1217
-134
-269
00
2427265
-240
+ 155
+94
2220
160
254
+ 10
8268
222
180
92
3223
184
237
20
9271
• 202
204
90
4226
206
217
29
30274
179
226
86
5229
226
194
38
1277
'54
245
82
6232
244
169
47
2280
128
261
76
7235
259
143
56
3283
100
275
70
8238
271
115
63
4286
071
285
63
9241
280
85
70
2435289
42
293
56
20244
286
55
76
6292
- 12
297
47
1247
288
- 24
82
7295
+ 18
298
38
2250
2S8
+ 07
86
8298
48
295
29
3253
284
38
90
9301
78
290
20
4256
278
68
92
2440304
107
281
+ 10
5259
268
98
94
1307
134
269
00
2426262
-256
+ 127
+95
2442310
+ 160
+254
-10
The co-ordinates recur with reversed signs after 30090 days.
Dec. 1907. PeriurbcUio'iis of ff alley' 8 Comet in the FasL 121
The diiteB of perihBlion passage in 1578, 1456 were already
known with ocoaracy from the obaervationa ; for that of 1301
Hind's value was taken aa a working hypothesis, to be tested by
the result ; the Julian days of the various passages are given here
for convenience of reference :—
FerUwiion Fuuge.
Jallan Dfty.
tjof
Oct. 227
219^^54370
I37«
Nov. 877
222468477
1456
Jiioe $21
2253021 "21
1531
Aug. 25-8
228049280
1607
Oct. 26*87
2308303 "87
t6S2
Sept. 14-81
2335655*81
1759
Mar, i2*S7
23^53592 57
1835
Nov, 15-94
239^598*94
1910
May 6*3
2418798-30
Intervml.
28 141 '07
1-2578
28336*44
1*2598
27471 '59
1*2508
2781 1 07
12544
27351 '94
1-2496
2793676
12557
2800637
1-2564
27199-36
1-2480
The last value is uncertain by several days ; the value given
»a8 that employed in our Jtipiter and Saturn work,
The following are the assumed co-ordinates of Jupiter and
^luru at the times given :—
Jupiter,
Saturn.
tpt
1378
1456
t53i
tl
' ^
y*
■z'
V
o'
-4*03
-3-07
-7*07
+ 5-25
90
+ 4-88
+ 0-28
+ 5'37
+ 8*43
270
-0-48
-4'95
+ 9-05
+ 3-63
0
+ 3*46
+ 3*97
+3'49
-8 '36
90
-5-02
+ 0*58
-8-33
-2-49
270
+ 1-19
+ 5-25
-7'44
+ 4<55
0
-4*58
-209
+ 5*36
-»-8'44
90
+ 479
'0-42
+ 8-51
-3*53
270
+ 270
-3-92
+6 '29
-6-55
0
+0-28
+ 5*37
"6-60
-5 '92
^ The method pursued has been identical with that used by de
^>ntecoulant in the memoir quoted above.
found for each value of u: then
;r - JT, y - y were
^^ - ^)' + {y - y)2 + 2^5! = p2^ where p is the distance between the
^l-ftnet and comet.
Then X, Y, the perturbing forces parallel to the axes, are pro-
«*^ltiotjal to
^ "Z
z y -u y
p'
122
Messrs, Coiodl mid Cromnielin^
hXvULi.
dUf the alteration in the mean motioD, is equal to X ain u -
Y cos u ^l - e^ rauitiplied hy a reducing factor, which is not
introduced till after the summation ; each value of tin b multiplied
hy the number of days to elapse before the neit perihelion pasaaga.
The following quantities are then formed for each value of ui- —
:rY - ?/X, rX, r{xX + //Y). In taking the sums of the colunins, only
.half of the term at the top and bottom of each colunm is taken ;
the reason is obvioua from the geometry of mechanical quadratures.
The factor for reducing f dn to seconds of arc is ■ ^ ^ a^m'du.
J 36S'256
The same factor multiplies the sum of dn x No. of days to
next perihelion passage, and gives a quantity which we call A.
The factor to multiply
{xY - |/X) sin u - JT^^j '"X is — — ;
tbe result is jdTj,
The factor to multiply I r(j'X + //Y) is 2 m*dti ; thia gives
quantity which we call C<
Then jd^ = A - Ut^ J'T^ - C,
And period in days is given by the expression
1296000- jdl
n at he^mning of rtivolution
du is the selected interval of u expressed in seconds ol arc ; thu
for interval —
I* rf«=5 36oo, for 4^* du^ 16200, for 9* du = ^2 400 ^ for 18* du = 64S
log = 3'5563 Iog-4-2095 log = 4*5^o5 log = 4'a J
The following are the assumed values of logm' for the different
planets : —
9 4-3^931®+ I>4*478i» ¥6-9799. b6'4558, 9 5*6408, 14)5-7122; »1
L
^i -e- = *254o, i.o. e--9672, log - = 0-0145,
log-— ^ =^8-7127.
365-256
The following tables exhibit the calculated ijuan titles : —
Dec 1907, Perturbaiiom 0/ Scdley's Cartiet in Vie Past. 123
Rew}luiion 1456 to 1531.
limlteofii. Jdn. A. \^d^.
K
Ve&os
lUnh
Jofrtter
•«
UnuioB
o- 30
330-360
o- 30
330-360
90-270
270-360
o- 90
90-270
270-360
0-360
Keptaoe 0*560
+ *oo7
+ 040
- -006
+ -oo?
-f ro7o
-J- '209
- '943
- '043
+ 050
^ -oiS
*ooo
+ '002
+ 2009
+ i'3
- 164*2
-h 0*6
+ 29020 '
- 1 105'
- 1096*
+
j6'6
O'l
28-9
- 0*4
+ •l'9
- o'8
- 0*4
+ 653'9
- S534
- 06
+ 490
^12Ji'9
- 9*4
- 4'0
+ 6'o
ri
•o
+ 7
+ •&
' 591 '4
- 1290*8
+ 76-9
42*6
14-8
254
4- 202-I
-f- 08
- 1647
O'l
^^ 29445*5
+ 2241-
+ l86'0
- 1185-4
4- 790*2
+ 8-4
- 137
+ 2*0
Smms
^375
+ ia'9
+ 3'5i3'
Hence for this reToIution we have the equation
129 oao -3i5t3 =27471*50, the observed period in days,
nat 1456 ■ ' ^^ ^ ^
Hence n at 1456 = 46*029
1531 = 46*029 + V375 = 46" '404.
Tile last result is in good accortl with de Pontt^coulant, who gives
(CJ., Iviii. p. 708) 46'''4lo for the valne of n in 1531 ; as he
hM computed the perturbatiofis by Jupiter and Saturn only for the
WTolutions 1531 to 1607, 1607 to 1682, his value is obviously not
^ W relied on beyond the first decimal.
Bevolution 1378 to 1456,
It
UmitBof u.
I'
dn.
Soms
0- 30
+ -0147
330-360
-'OOI9
0- 30
+ 0148
330-360
-I--0003
0- 90
' -1320
ga-270
-•1S2
27t>-36o
+ '6725
0- 90
+ -0593
90-270
- 'OU
270-360
- '0240
0-360
-'0013
0-360
-*D036
+ 4187
- 0-9
+ 417*3
- 0*9
-4065*5
+ 636-5
+ 1553*2
74'5
17*1
11*2
I^
1*4
I '5
rz
22
611 "O
16*4
3807
95*3
72-8
85*6
1-3
io'5
C.
**
- I*t
- '4
' I '4
■ "3
-187 -3
1-841*1
'112*1
^ 53*4
- 1-6
-J53'0
;«■
+ 420*2
en
-f 419-0
O'O
-3722-
4-2991*
' 108*3
-f 1689*5
+ 1586'
-4- 0*8
-H 19*0
+ 167 'i
-^'4068
HOI '5
+ 1^S^'\
124 Messrs. CatoeU and Orommdin, LXvnL 2,
Heuce for this revolution we have the eqaation —
1296000''- 345 2"'3
n at 1378
: 28336*44, the observed period in days.
Hence n at 1378 = 45*614
1456 = 45*614 + ''0*407 « 46**02 1.
There are now two independent determinations of n at 1456,
which are satisfactorily near each other, considering the nmf
abbreviations that we have introduced ; we are justified in wiop^g
their meau, viz. 46"'o25. The corresponding values for 1378^
1 531 are 45"'6i8, 46"*4oo respectively; the close accord of tiie
latter value with that of de Pont<icoulant is satisfactory.
Revdution 1301 to 1378.
Planet.
Limits of u
• J*'-
A.
Id..
C.
J-^
Venus
0 0
0- 30
+ W23
M
- 2*0
• ••
+ 6y^
»»
330-360
+ *0020
...
- 1*0
...
o-o
Earth
0- 30
+ -0121
...
- 1*7
...
+ 357'^
*i
330-360
+ *oo74
...
+ 2-4
•
+ 0'^
J a pi tor
0- 90
+ 1*115
+30905-
+6ir2
- 721 '2
+31471-
>i
90-270
+ -1983
-263-6
...
+ 1303'
,,
270-360
- -5980
- 1230-
-418*8
- 1303-3
+ !&•
Saturn
0- 90
+ -0295
+ 776*4
- I4'6
- 59-8
+ 839*^
»»
90-270
- -040
...
-106-4
...
- 6o6-»
,,
270-360
+ -0367
+ 8o*9
+ 51 '6
+ 767
- i'S
Uranus
0-360
- '0017
77
+ i-o
- 6-9
- v%
Neptune
0-360
- 'OOOI
+ r
+ 8*6
+ 28*3
- 23'
Sums
+ 763
- '33 '4
+33576-3
We now proceed as follows: n at 1301 = 45"'6i8 -o"763
= 44" -855-
Then theoretical period in days = "^6000'^- 33576^ j
44'-855
= 28144^*5.
This only differs 3** '5 from the value obtained by using
/dentification of the comet of 1301, viz. 28 14 1^*07. 1
Hind's
The dia-
Dec 1907, Ferturbations of Hallm/& Comd tn the Fast, 125
cordftnce is do small that we are juatified in acceptiDg Hind's result
with a^tsolute confidence. The long discussion as to the ideotity
of the comet of 1301 is thus happily ended. Dr. Galle, iu his
Comftenbahneri, p. 155, s^ays of the comet of 1378, *^Die erste als
aichier zu betrachtende Erscheinung des Halley'achen Cometen,"
We may now claim to have brought the ** richer" returns one
Involution further back, and to have thus obtained a firm starting-
point for further investigations^ which have, in fact, already been
commenced^
It will be remembered that Pingre, using the European observa-
tions alone, obtained elements quite unlike those of Halley;
mibflequently Laugier, using a combination of European and
Chinese observations, obtained elements resembling those of Halley,
except the pttsition of the node, which was 90* ^^reater. Finally,
Hind rejected the European observations entirely, and showed that
Jttie Chinese ones could be well represented by the Halley elements.
Testilt indicates that he was jiistilied in this course ; it is rather
k curious reversal of the present relations of European and Chinese
ilronomy. Many of Dr Hind's older identifications rest on
■^^Klttese obdervations, and it is satisfactory to find that the accuracy
oithe latter in 137B and 1301 is folly vindicated.
Having once satisfied ourselves of the identity of the comet of
^JQi, we may rewrite the last equation in the form —
y ^ r3357 — 3=^ 28i4ro7, the observed period in days.
n at 1301 ^ ' * ^
Henee 71 at 1301 =44*861
1378 = 44-861 +o*''763 = 45"'624.
T»kmg the mean of this and the previously adopted value for 13 78,
y*t 45'**6i8, we obtain 44"'85S, 45"*620 for the adjusted values
^ '301, 1378. It ia advisable to make these successive adjust-
Biefttft m order to diminish cumulative error through qimntities
4»t we have neglected.
Observations of Comet d 1907,
126
OlBej-vations 0/ Comet d 1907, /ram photoffraphs tc^kett wUh \
30'i«. Refledor of the TlnmipiKm Equatmol arid th^ Ai
graphic i yin, B^radofr at the Royal Oheervatory^ Greenwich
(Oommtmiaded by ihs At^vnomer BofoL)
The following positio&B of Comet d 1907 were obtained
photographs Jtaken with the jo^in. reflector and the astro^^raii
[3-10, refractor, with exposures of from 20 seconds to 5 minutei
The plates were measared in the aatrograpbic micrometer. Six
reference stars were, as a rule^ measured with the cornet^ their
positions being derived from the Catalogues of the Astronomische
Gefte]lschaft.
The positioDS i^iveu are not corrected for Parallax.
Log Parallax Correction = log Parallax Factor - log A ,
DKteimdG.M.T.
Apparent ILA.
Apparent ]>ec
Log PanUUx F^i^^r
30-111.
Kvflector,
^
d
h m 1
h m »
V f «r
June 19
14 3 1
0 16 32*60
+ I 14 ro'8
-9*525
+ 0-833
July 4
14 15 I
1 14 23-48
5 49 547
9516
0-817
4
14 18 47
I 14 2423
5 49 57-5
9Si2
0'Si7
16
14 11 38
2 22 8*84
10 28 tri
9-540
0805
24
14 14 19
3 22 19-51
13 42 07
9*562
O'802
JO
14 47 n
4 15 i5'97
15 44 I9'6
9-564
0792
31
M 34 8
4 24 26-04
16 0 37*8
9*573
0799
Aug. t
H 59 5
4 3S 56^0
16 Id 0*5
9'565
0790
6
14 57 39
5 21 17-16
17 8 57-3
9*579
oSoo
[Q
15 »2 37
5 58 53'i5
17 22 59*5
9581
q'8o3
11
15 18 16
6 8 5-99
17 22 427
9-581
0'8Q3
la
15 18 36
6 17 io'8o
17 20 S87
9*582
o'Sos
15
15 32 32
6 43 45^84
17 7 56*9
9-581
0-805
18
'5 37 17
7 9 6-29
+ 16 44 44^8
-9582
+o-8n
Astrographic 13-iD. Refractor.
20 15 46 44 7 25 2077 +j6 24 19-4
- 9-581
Jiojfal Obanfmtory^ Qrtmwich :
tgo^ Ikcember 12.
Dec, T907. Photographs ofPhc&he, — Occuliations of Uraims. 1 27
Note <m Photoijraplts 0/ Plmbf^ taken at the Buyal Ohiervatory^
Greenwich,
[fitmmmnieaied by the Aiir&mmur Eoyml)
Photographs of Phtebe have been obtained with the 30 in,
lector on 16 nightaj vix. —
Aug, to
Kxp,
105
1907
Oct.
2
Exp. 90
II
133
4
r2o
18
143
S
53
•9
120
12
90
19
93
30
100
Sept 2
53
Dec.
3
120
9
107
5
120
10
70
6
90
The photograph on October 30 was at or very near elongation,
Ukd will thus be of special value for & determination of the masta
of Saturn, for which this satellite is pecuiiariy UBeful, its distance
«l elongation being about 28' — thr«e times that of lapetus,
iipyiQ^ Ob$ervatory, Greenwich:^
1907 Def^mher 13.
Otit^iatitm$ of Uranui by the Mofm m 1908^ pinble at British
Obsermtariei. By A. M, W. Downing, D.Sc, F.RS.
It is hoped that the publication of the following particulars will
•'^le astronomers who are favourably situated to observe some
•t laaH of these intereating phenomena, noting any peculiarities
^ appearance of the planet at the time of occullation that may
strike them.
JS PU^.
BUadord
..f 1'
\f eao Tlm«
AtiKle from North
Point.
InirnenioTi.
EmerAtoti.
Immttni&n.
Emenlon.
b tn
b m
m
0
frti 12 A<leiftide
• 10 53
11 46
106
266
„ 5lelb<iurne
. II 25
12 20
106
266
,, Sydney
It 20
12 iS
88
284
,, WflUugt^^n
13 10
14 18
Si
zS^
^1 19 Naul
. 8 44
9 29
64,
30S
% n Perth, W. A.
5 41
635
99
275
>, Ad«Uide ,.. ,
7 19
8 19
7S
296
«, Mtilboarnu ...
7 57
S 59
79
293
„ Sydney
^ 3
i^57
58
315
H Wellington
10 ti
n 19
62
299
^% 9 Cap© of Good Hope,.
. 10 4
10 55
37
321
^t' 3 Wdlangton
12 20
13 7
ss
287
'^ DmoUnr 6.
128 The Trarmt of Mermry, 1907 Nmmnber 14. Lxviaa,
Th6 Transit of Mef'cnry^ 1907 Nofsember 14
{Coinmunicaled bjf R T. A, Jnn^,l
At Johannesburg, at ingress, thin clouds obscured the San ftnci
made obaervatiou dilficult ; at egress the San waa cloudless except
for a few momente just before external contact.
At Pretoria the Surveyor-General organised a party, but clouds
prevented any useful observations.
The observatioTifl made here are tabulated below. The indi-
vidual observers^ reports are as follows : —
Mr. R. T, A. Innes, using a 9-111. lefractor by Grubb, with a
suu-diagonal eyepiece : —
When I looked at the Sun at 15^ 46"" 4' aid* (clock) T,
Mercury was already about J on. At the time of internal contact
rather thick clouds were passing, but the planet was never inviaible.
Internal contact took place, as nearly as I could estimate, at 15^
47" 48*, but it was possibly a few seconds later. Heavy clouds
passed for a few seconds, making confusnd definition. At 15**
48"^ J* the sky cleared, but contact was passed and the planet clear
of the limb by | part or so. Before egress the planet was care-
fully scrutinised ; it was a mere circular black dot, without any
shading; dehnition was perfect, the Sun's limb being without a
trace of serration* Second internal contact was at 19** 8™ 56* and
was good ; last contact at 19^ 11"* 36* was fair, as some thin clouds
were passing.
Mr, W. M. Worsscll, M.B.A.A., took part in the observations
with his 3-in. refractor and a direct-vision eyepiece : —
Ingress ; definition was vrry bad, a decided line was seen at
15^ 47°* 59' sid. T, Egress : suspected black drop at 19^ S" 4S*,
certain black tlrop at 19^' S^ 51"; contact passed at 19** 9*** c/,
external contact at 19^ 11°* 27*. Detinitioo mediuni.
Mr, J. Innes, 3-in, refractor, direct-vision : —
Dark glass split during observations, observations unceri
Internal contact at egress 3^ 46"* 41'S* stand, clock T,, e;^
3^ 49™ l.5^ One -quarter weight has been given to these
observations.
Mr, H. E. Wood, M.Sc. 2 J-in. refractor (Kheinfelder & Hertel),
direct-vision i —
Good definition, image small ; internal contact at egress good,
igb gm 2^a gi(i^ T^^ i^gt contact at 19'* 11^ 25" more uncertaiK.
For the timing arrangements, electrical sounders, connected with
tbe sidereal clock, were placed near the observers. The clock had
;;rii^
Doc, 1907. The Transit of Mercwry^ 1907 November 14* 129
laeeu rated by star observations with a transit instrument for five
vreAs preceding the 14th November, and had a steady rate of
o"28 seconds per day losing. Its correction at t6 hours S. T, on
^ inber 13 was +0*56 seconds. Cloaciy weather prevented the
rvation of time stare on the 14th ami 15 th, but from the clock
rate the corrections at the times of observations of the transit on
the 14th are 4*0*84 seconds at ingress, 4-0'88 seconiia at egress.
The mean time clock was rated by comparisons with the sidereal
clock, and its corrections are - 1*3 seconds at ingress, - i'2 seconds
lit egress. When the corrections are applied to the above times,
redaction to Greenwich mean time made, and the following
reductions to the centre of the Earth applied, ingress internal
contact 4- 3*4', egress internal contact +30*9», external contact
-*- 31 2% we have : —
ObMrrer.
TeleKOpe.
PlkAa«.
Oeocentiio Oweawfoh
Mejiu Time.
Ii
tn i
R, T, A, Itjnes .
9'ili.
11.
22
26 4*8
W. M. Wor8«€ll ..
3-in.
11
22
26 1 5 '8
R. T. A Innw .
9iu,
IIL
47 7 '5
W. M. Worwell ,
3-in.
III.
47 7'o
J. lanes
3-in.
Ill
47 n*i ^ weight
H, E. Wood
2^'in-
III.
47 7*5
B. T, A. Innei?
9>in.
IV.
49 47*3
W. M. Worsaell ..
3i»^
IV.
49 38-4
J. Iiinet» ...
3'iQ-
IV.
49 3< "5 k w^iglit
H. K. Wood
2i-in.
IV.
49 36 '4
N.A. O-C.
Ks»uU« of Johannesburg observations : —
Hov, 1907
Obs.
latertial couUct at inpiTe^ 2
, , egress 4
Kateroil .* ,1 ,, 4
The direct-vision observers uaitig the 3-in. telescope had six
iim-gLftises either blistered or cracked >iitring tbeir observations,
^ Mean of " certain bkck drop '^ and '* contfict paaied."
d
ti m ■ '
•
1
13
22 26 10*3
18
-77
H
I 47 7^6
17
-9-4
H
I 49 40-0
58
-iS-o
1907 November 15.
130 The Transit of Mercury, I907 Niyvemher 14, LXvm. 2,
Oh^fvcdiom of the Trandt of Mercury^ 1907 November 14
By E. T. Wliit^low,
Made at Birkdale, Lancashire.
Long. W, 3' 1' 37".
Lat N* 53' 26' 48'.
Keither ingress nor egress was observed, owing to clouds.
A. Direet Observations yfere made with 7j-in. refractor, stopp
down to 4-in* A Thorp's pol ami ng eyepiece : power 150. At jah.
15m* G*M.T., Mercury showed a clean cut, round disc, with 00
indicatum of halo or bright spots. The duration of observation
was half a minute or so of bright sunshine, and intermittent observa-
tions of a few seconds at a lime when the Sun was slightly obscured
by cloud, perhaps 2 minutes in all.
At 2b. 20m. there was a sudden burst of bright snnsliine in a
patch of clear blue sky. I put the edge of the Sun just outside
the held of the eyepiece, uncrossed tho prisms of the eyepiece so a^
to get the maximum light, and found Mercury in the field. It had
much the appearam^e of Yenns when in inferior conjunction, vit a
very thin c^irved line of light extendiBg about 120* round the
planet. There was no trace of this on the side away from the Sun,
nor could I see wiy trace of the dark portion of Mercury contrasted
against the sky.
B. Spedroscopir" Ohservaiion, i2h. 48nL G,M.T.
Instrument sj-in. refnictor, Brashesi; gratings 15,500 lines per
inch J 1 8t order. Power 120 and 180,
The planet was observed on the Sun's disc only, with the slit
parallel to the direction of diurual rotation. Along the centre of
the cpectrum was seen a shaded band, consisting of a dark cen
band B, bordered by elightly lighter margins A, A*. Each \ _
about \ the width of the central darker band when Mercury was
bisected by the slit. To make sure these were not due to dust lines,
I pulled the clock slow-motion cord to and fro, and found these
margins travelled with Mercury alonjz the sht, I also slightly
increased the opening of the slit, to clear it of any possible effect
from dust lines. When 1 n^oved the telescope up or down in
Dec. J 907, Passage de Mercure 14 Nav, 1907,
131
lieclinatioo, the central dark baod B became relatively narrower
tban the margins A, A^ Fraunhofer lines in A, A' exactly corre^
sponcled with those on the Sun^s surface outside these margins.
They wor^i, however, very faint, or hazy, and difficult to focus,
although Unas on the 8un'8 surface were |jcrfettly dclined, I could
not efcay they were wide, and the dilticulty ^»f foi!tii?sing seemed to
be due to lack of «jufticient conti-ast as Been on the margins A, AK
The t<3tal duration of the Spectroscopic observations was about
t^ tninutes of brilliant sunshine and about 2 nnnutes of haze.
KoTB — November iS, 1907. — The foregoing observations having
been BUbmitted to Father Cortie, he suggested that the failure to
«ee a lighter ring when Mercury was on the Sun's disc while making
the observation A might be due to the polarised Held of the Thorp
eyepiece being then too dark to permit it to be seen — E. T. W.
Obteroaiion du Pasmge de Mercure sur le Soleil le 14 Nov. 1907.
Par Robert Jonckheere, Observatoire de Roubaix.
U^torii
La situation de robservatoire est approximativement a 50' 40'
de hititude et a 3*^ 19* de longitude Est du nicridien de Paris.
LHnstrument utilise^ pour les observations est nne lunette equa-
ble de 2 20 mm. diapbrHgrnte a 150 mm. La distance focale
i de 2*" '50. l>e pied est faible et les tn/pidations rendent
difHciJea les raeaures micromi^triques, Le micromf'tre eat bifilaire.
Toutes 1p« mesures ont tte prist^s a Faide d'un grossissement de 150,
mais |>ouT les observations visuelles des grossisaements divers,
▼ariant de 70 Ji 600, ont e^tu employt's.
L'atmo^phere pendant touto la duree du passage de la plane te
arait le zenith com pit' tern eut dc'gagt' de nuages mais I'hori^on ^tait
hmmeox. Le soleil e tan t a une hauteur de 30'^ en moyenue diirant
robftervation 11 a ^^te par instants masquo de nuageSi et c'est la
ruison pour laqueUe le premier contact intrdeur seul a pu utre observe.
L'^tat atmosph^rique n a pas pei mis ^le chercher k constater la
prince de la pianete avant son entre sur le dis^que du solLnh
Le I** contact exterieur n'a pu etre observe et la plan^te n'a M
aper^e que lorsque la moitie de sou disque decoupait le bord
solaire,
Aucune deformation des cornes n'a ^t^ constat^e bien que
Timage se presen**ut a ce moment avec une grande nettetr^.
Aucun ligament ni pont n'a eti^ remarque au i''^ contact in-
tiTieur.
La plan^te etait beaucoup pins noire que les taches solalres qui,
en comparaison, paraiasaient bleues. La corde tracee par Mercure
^iail trop boreal e jKJur occuUer aucune de cea taches.
Attcun point obscur pouvant etre consider^ comme satellite ii%
•^tc ab^ervc*.
132 M, Robert Joiukhmre, Oh&ermtiofi du Passage Lxnn. 2,
Deierminaiion du Dinmlire et de PAplatis^emeni.
Afin de rtnluire le plus pussiVtle \es errears personnel lea, lefi
meflnres microm^triques i>nt ^ie prices en placant roeil horizooUle-
meiit puis verticalenient. La niicrora^tre n*a pas ei6 fix«i a uu
angle determine il & f^te constamment maintenu h i'une des dim
poBitiona verticale ou horizontale.
Memre du Diam^tre Horizontal,
De 1 1 K I
Moyfinnes
De 12) & I heures
Moyentiei
llMuia
.s"3 sro S'S 50-4
;83 50-9 92 5ri
(8-2 50-5 S-o 51*2
8*27 9'20 867 ' 9'io
Moyenne g^iiMfale 8" '63,
16-5 m
59 '6 50'^
3^9 no
790
*8"2 50*6 87 51*3
-tS*o 50*4 8*8 50 '8
'8*3 510 8-4 51-9
8-17 rSS S-63 8-67
4^3 3i"7
32*4 42*i
7*4 «S-^
9-40
Moyeone g^0^r»le 8* '84.
Moyenne pour le» d^ux series do mesurea 8*73.
Memre du Diarmtre VerticaL
Vastl piae^ horissantaUm^nL
Dei2^in2i*' -I
Moyenneu
Vlii
V|»a
r.
]teiure«
]>lff4rentleU««
*U
i*
r
'
9-J>
49'0
9-6
510
33 5
-J :'
9-3
50*2
9.9
51 0
31*4
210
9'8
505
9'4
51-6
347
44'6
9-63
ro*io
963
8 'So
lO'lU
Moyonue gen^Tile 9* •65.
L*asU place veriicakment.
Dt I* 1^ i^ 25™ J 9^0
50*0
508
90
93
50-6
11*9 ji 0
55-1 r'y
Moyentioa 9*23
502
9-67
9*1
915
507
9^23
307 4^^
913
Moyemie general© 9*'2S.
MoyeuTic pour les deux Reries 9*'4]6»
Pour reosemUe de to^\*ft \e* m«aurea 9**ia
Dec, 1907. de Mercuye sur te Soleil U 14 Nov, 1907. 133
Uexistence des anneaux n'a paa ^t^ constatde, maia un l(5ger
df^fatat de mise an point donnR une image faisant croire a une apj>ar-
ence d'atmosph^re et ressemblant eDtii^remeot aux dessins de
Scbroeter de 1 799. La nuance de ce halo est alors identique k oelle
de la pejiombre des tacbes solaires.
J'ai encore remarqu^ que les facules et granulations dii Boleil
aomblaient plus dii; tine tea anx environs de la plan/^te : probablement
re0iit du contTaste produit par le dts^j^ue noir.
Aucune apparence lumineme n'a ete aper^ue, Le disque s'est
tottjours pr^ent^ uniforaniTnent noir.
Les demiers contacta allatent m produlre lorsque le disque
aolaire disparut derriere les nuajjes : une tjclaircie ee produisit et il
fui possible d^obberver la plan^te alora qu'elle »^cbancrait 1© bord
^'♦laire de la moiti^ de son diatnkre.
P. 5.— 5 minutes et 6 secondes apr^a le premier contact
mterieur, uo petit point noir a pass^ tr^'s rapidement eii face du
^oleil, de rOueflt a TEst a environ 20° de diclinaiaon bor*5ale :
vraisemblablement une etoile filante.
KoTRS* — Le ph^nomene daiiBSA marche reguliere n*a donnt5 lieu
ianotme observation autoriaant Thyf^otb^ae de Texistence d'une at-
Dosph^e, [II ^me trt^a faible,
L'exameo des uesures microm^trlques montre une difference
«ntre lee diamitrea vertical et horizemtal de la plan^te.
La moyenne pourle diatniHre borizontal est de 8"73 et pmir le
^liiiiD^tre vertical g"'46. Cette difference de o'''73 est surprenante.
n ne pent etre question d*une erreiir peraunnelle cm inatrnmentale.
La valeur verticale 9 ''46 eat celle qui approche le plus du
<iiafti^tre generalement adopte et eels se con9oit car les phases de
^ercure ne permetteiit babituellement que les meaurea de ce
^^iamttre.
II me semble ^galeoient intt-ressant de faire remarquer que pour
** premiere e^rie des mesures du diaimetre horizontal, la luoyenne
■^^s iv^ultats est plus faible que pour la seconde : alors que pour les
**^^etire5 du diametre vertical, c'est I'inveree qui se produit. Les
***«taree ©flFectuees avec Tceil dan» la position horizon tale ayant ete
'^ ^-MQ eu premier lieu, lo mouvement iJinrne pent expliquer cette
■rence etant donnt^ le deplacement horaire de la planete dana
* ^^tervalle des premieres aux d emigres mesures,
Dans le cours de mes observations visuelle^, j'avaia remarqu6
*J*»< bgt^re deformation du diique dont Taxe ♦'tait k 20' a gauche
^*^ la vwrticale, mais j'avais pri^* mon aide de ne paa noter cette
r*%Tticulariti? qui me paraissait inv raise mbl able. Cependant, aprfes
""^'^'MT pns la inoyenne des mesures, je m'aperijus que ce n*<Sfcait pas
' illofiion puisque les chiffres confirmaient ra[>parence que j'avais
^u»uitee.
DWpr^ cea observations I'on serait done conduit k devoir
^cepter que La planete Men-ure a une deformation tres seusible, et^
^eii qu'eUe paraisae trop grande pour ne pas avoir *iti<i a\)et«:i\x«i
J^u*ici, on pent admettre qu'elle ait i^chappo aux oWeiv&lewta^
dli^
134
Lututr NoffieticlAt'ii^t,
LXVriL 2,
car ils onfc bien rarement Toccasion de prendre lea mesurM du
diaque entier de cettc planete.
Cette dt^formatiori pourrait servir a ju^tifier Thypoth^ fl'un
mouvemBiit de rotation dont Taxe coiriciiterait avec Torbite de U
planete, niais il serait pent ^tre plus simple d'admettre qu^elle n'eat
pas le rdsultat d*uii mouveraent de rotation rapid e, mm d*
i'attractiori dii soleil II faudrait aJora reconnaitre avec M.
Schiaperelli que cette plant' te n'eifectue qu*une seule rotation
durant sa fL^voIutioti autoar du soleil.
Ruuhaixi .
h 19 Novembr* 1907.
LUNAR NOMENCLATURE.
I, At a met^ing of the Internalional Aeaociatiou o( Acaderaiea
in Vieiiua in May 1907, a Uoniniittee was appointed to consider
and report upon Lunar Nomenclature, with a view to securing
consistency ami uniformity. The Committee consisted ongiDaUj
of Loewy (Chairman), Franz, Newcomb, Sannder, Turner, Weiai,
The names of W. H, Pickering and Puiseux have since been
added, and it was hoped that un eminent German astronomer
might have also joined the Committee, but ht* felt unable to do so.
A heavy blow bas fallen on the Committee in the sudden death
of its Chairjnan, M. Loewy.
By request of the Chairman, the undersigned undertook the
duties of Secretary to the Committee ; and he has aecordiogly
received several suggestions from individual members. From the«e
it becomes clear that it will be necessary to take a preliminary
decision of the first importance : — viz. shall an essentially new
system of nonieuclature be propounded, or do astTonoraers prefer
to retain simply the traditi^mal system, with necessary corrections
and possible modihcatiuns r
To propose a new system requires some courage and may only
increase confusion. On the other hand^ no more favourable moment
than the present is likely to occur for crnif^idering such a proposal ;
for if the Committee succeeds in correcting and improving the
preaeot Bystem, it will naturally be rendered more tenacious of
life. Finally, the propositi for a new system need not mtan the
abditioQ of the old. In the case of minor planets we have already
a double system of nomenclature — ^names and numbers ; and there
may be advantages in having a dual system also for the Moon.
But such a nesv departure calls for very careful coDsideration ;
and it would he of great help to the Cummittee to know whether
it were likely to meet with ap{>roval. The circumstances sug^l
tliat if the Royal Astronomical Society will publish in the MoiUhlij
Notices the sketch-proposals themaelveSj so that brief comment*
upon them may be invited, ^h^ Committee might be greatly
Slated in deciding whether to put forward some such scheiue
le finitely or Qot.
Accordingly^ the present document is submitted to them for
publication, containing the proposals of Dr. Franz, and the counter-
propnaals of M. Puiseui {to whi»!h our late Chairm;in had given
a general approval) and of Professor \W H, Piclveri ug, Tlie
Committee will welcome any comments made upon tliem by
astronomers interested ; and would specially appreciate replies tc>
the following questions : —
(i) Do you approve the proposal of some mechanical or
numerical system of nomenclature in place of the old?
(2) Do you approve the proposal of some such system in
(uldiiion to the old 1
(3) If euch a system is to he adopted, which of the three
proposed below seems* on the whole, preferable 1
(4) Are your comments and replies intended solely for the
Canimittee, or may they he published if thought desirable 1
H. H- TUIINKR,
Secretary to the C&tnmitU^
Oniverifity OhnervatOTy^ Qjcford :
1907 November ao*
on Lunar Nom^nelatHre,
Dr. Franz*s Proposals,
Breslau, le 13 Aout 1907,
Monsieur, — Invit<^ k pn^^senter dea propositions pour la nomen-
clature system ati"]ne de la lune, je pense qu'il n'est pas trop tard
pour rt*former entii^^rement les dL^nominations. Car la niesure
d'un grand nombre d'ohjets n'a t-to faite que depuia 1900, M,
Saundar a publie les aiennes pour une grande par tie saiia nom, et
lea mesures de Br«slau, qui sont aussi de plus de mEle, ne sont pas
encore [lublii^^es et portent dmm les Diaimscnta des donomiaationa
provisoirea. La commission ne pent se passer de publior une carte
de la lune avec une nomenclature systt^matique, et alors dans les
I." ea et siecles a venir on aura rareraent beaoin de recuurir aujc
riptioDs de Madler^ qui ue »e vendeut plus chez les librairea,
ou a eel lee de Nelson, qui en sont un rti^umL^
Je m'occupe aujourd'hui seulemeut des crat^res principaux
-■le Mbstingi et je laisae de c6te les cratc^rea sec^ndaires comme
uig .-I. Les noma des astronomes, que RiccioU a introduits,
n out aucune relation avec les cratere^, et» a de tres rares exceptions^
jamaij^ an astronome n'a vu le cratere qui porte son nom,
. Poar avoir une denomination systematique il faut :
(1) que les noms accusent directement la position du cratere,
(a) qoe lea noms soient courts^ afin qne leurs inscriptions sur
les cartes ne couvrent et ne cachent pas trop de d«^ta\\ft,
(3) que les noms soient aonores et faciles il prouoncer,
136 Lunar Ncytmnclaiwre. LXViii. 2,
Void, ce que je propo&e :
On d^signe les longitudes (dans Timage invera«, que la lunette
montre, de gauche k droite^ comme un ecrit) de 10 ^ 10 degrt^s par le&
'.'otwomtej? : longitude plus de -f 70* -h 60"^ + 50* + 40" + 30* + 20'
par b cli d f g k
-I- to' +0* -o* - 10* - 20' - 30* -40* -50* -60" - 70'* *
Imnpr s twxzj
On dt^signe \m Icditvdes (de baut en bas, comine on ecrit) par
dee voyelles. Latitude pluF de
-70^
'60'^ -50''
^^d'
par
Aa
Ae
Ai
Ao
-30-
-20' -10*
- 0'
Ea
£«
£i
Bo
+ 0"
+ 10" + 20*
+30^
U
le
li
lo
+ 40'
+ 50" 4-60'
+70°
Ott
Oe
Oi
Oo
On met la etmsonne entre le$ deux voyelks.
Si datia un carr^ 11 y a plusicure crat^res a d^uominer, on les'
ordoniie |nir ordre d© longitude et on ajoute les consonnes 1, m, n,
p, r, 8, . . . z, b , . . k, dout ka premieres, les plus souveui
employeei*, sunt appelees denii-voyelles par les lingiiisteset se pronon-
cent facilement. Si jamais rinterpoltititm d'un nom nouveau devenait
iiece^s*aire, la eommissitjn pourrait fucileinent dim net une regie
d'interpolBtion (par exomple I'addition d'une vojelle} et jen'ai pas
besoiu de m^^ccuper laaiii tenant de cette question spt^ciale.
Pour moiilrer cet usage, j'ai joint une liate de tons* les crat^iea
d^^nomiiu's par Neiaon, quoique je croie, que la commisaion jugera ^
un moiiidre nombre necessaire, de mSme qu'oii pr^f^re n'avoir p&s
trop d« c<instelkiti(>u8 dans le cieL
♦Fai aussi joint im tableau des carr(is.
On n'objectera pas, que les noms nouveaux eont difficilea a «e
rappeler,
II y aura purtout des asaoetations d'ideea, qui aident La
m<^moire, et qui ue sout pas plus etraug^res k Fobjet que lea
ancieus noms d^astionomes.
Par exemple Apol (Tycho) rappelJe ApoUen, trainees divergentes,
etc.
Au sujet des crat^res secondaires camiut; Mostiug A ouEnom
A je vous enverrai une troisi^me lettre.
* J^ai oiiiis h^ parce qnt; ks Fratiyaia ue pmnauo^tit pas cdtt« coosomie.
J'ai onus q, [.nirLts^ue coite coiiaonDe u'a pas de son pixipre.
J*ai omis v» parcequ'ou [iroLionc^j cetto ct»n80une de nieiiie que i ou w.
J'at place oh ati lieu de c, paroeque cse proaoDce conimc k ou comme z.
^lais je fais toutus lea ooDoeaaions d^fiirlea ; |iar exemple on peat mettr« v
au li(?u do w (ce eerait plus ooan) et le prouoncer coiiiine w (comme en
France).
La voyelle e dmt etre prononc^e eu France comme e. Les Fran^fais
peureat ocrire ^, slla vtulent.
J<j [>ense «jui*on n'aiira jaDuiis lj*e-vOtn d*ep<?ler \m lettrea.
Je ue craitis pas, que la coiumis^iuii trouve uiie diBouIt^ ea oe que Jcb
Anglais pronoiicttni le^ royellos muiiiB ^otioie^ que lea italiena et les Autr«»8
natious. On n'a pas be^oiu 4'ime desiguation i>our le& longitudes et lea
latitudes iiui aurpassent 80'. L'aire entre 70" et 90*" est plua petite que oell«
entre 60* et jo" dans la projectiou oTthogtaphlque*
I
F™
13; ■
Dec. 1907.
i«mar NoviencliUure,
AgF^z^ MotiBieur et cber Coll^gae^ rassurunL'tf do
consideration,
ma haute ^^|
JULIUB H. G.
Franz. ^H
BoguilAWitkj
= afa
PontOCoaJaut — achi
FabritiuH
^^1
ScboDibf^ger
= «kft
Biela = ttdi
Lockyer
= ago ^^1
Simpelins
= oU
Hiigecius ^ ati
Kicolai
= ako ^^^
MftU(»feri
= ana
Rosen b«rger - afil
B&rociuA
^1
Short
- iLnal
Vlacij = agi
ilaurolycua
alot ^1
Kewtan
= ipA
Keareb '=^ agil
Clairant
alam ^^^
Oibetui
= a»
Hommel = agim
Co vie r
amo ^^B
Kkprotb
^ &ral
Piti*cU8 = agiu
Faraday
^^1
C&ntufi
= itsa
Tannei'UH ~ aki
St^fler
amom ^^|
LeG«&til
= *ZA
Baeon = all
Licetua
^^1
BousmiigaaU
^ iide
Kinau =: alU
Naflireddiii
ano ^^H
Motus
= age
Jacobi - alim
Sauasure
^^1
Manxiiitis
= ake
Llliiis = aiui
Pictet
= anotn ^^^
= de
Zaith = ami)
Street
apo ^1
Fr&tUad
= tUI
Delnc ^ ani
Tycho
^H
Cmtiiia
= ame
Jklaginuii — anil
Hainains
apom ^^1
C7»tB9
= wie
Clairiua = apt
Wilhelni i
apun ^^1
Moretiu
== and
Rost = aat
LoTigomontaiiua= aro ^^|
GTueinberger
= ape
Bayer = aail
Hbiiuzel
= aao ^^1
Blancoiius
= are
Weigel = asim
Drebbel
^H
B^tmnei
= arel
Schiller = anin
Schickiiaid
uwo ^^1
U*ibott
= ase
Segoer = ati
Wargentin
ajto ^^1
B«ttiniis
= asel
Phocylidtfs = awi
1 11 gill rami
azo ^^1
Ivirchet
= aaem
Pingr^ = aii
MariiiUH
^1
ZmihtiiB
= aaeii
Oken = abu
Adao^a
^1
Bmmj
= ajuj
Vega = aclio
Fumerius
■
BauMD
= A2e
Steinbeil == afo
Fraunbofer
^H
Hjuino
= dbi
JauBseti = afo]
Steviniu
* Only ft part of thew aie printtsd.
1
M. Puiseux'b Phoposals.
1
^li^ /<i proposition de M. Fra?tz, mncemant Veiablissement (Tune ^H
nouvelle nomenclature lunaire, ^^|
LI ne Ctitit pujt se difisimuler qu'uii8 nomencJattire euti^rement ^H
no\ivelle sera difficilement accept^. 11 demiiurera iK^cessaire ^H
d'i*c^n»-rir an certaiu degre de familiarity avec rauciemie pout ^^|
j^rofiur dee travaujr descnptifs hits jusqu'k ce jour, ©t quv 11% ^|
t38
Lunar Nomendatmr.
LXVUI. 2,
|H)urront ^tre lemplace^t ou traduits dans le nouveau nyatozDe
qu*apres im temps aasez long.
Si l*on se resoiit u ctablir un syHterae entierement nouveau, il
doit presenter Telasticitt^ necessaire pour 8*dtendre par deu^res a des
objets plus petits et moips bien dt^li mites que ceux qui aoroDt re^u
des noms en premier lieu. II est int^ntable que les etudes futures
afu^neront a cansidpier de tels objets.
On lie peut pas adopter un aystome pour les formations quali-
fiees princi pales, uu autre pour les formations qualifiees secoDdaixea,
k moiaa que la premi<''re calegorie ne soit exlremement restreinte,
et compoftee aeulement d^objeta familiers a tons les selenographes.
Pour les mers, les golfes, lea grands massifs de montagnes, il
est k peu pres inevitable que les denominations actucUes, d'origine
gt^^ograpliique, se oiaiutiendront en usage concurremmenf avec le«
noma nouveaux que Ton peut souhaiter de voir adopter. Ce«
objetg so lit peu nombreux, leur nom evoque aisenienfc le souveair
de leur positicm sur la Lune, ils nlmpliquent nulle prt'tention k la
roHgemblaiice ou a rr'quitu, eniin ils correspondent k des habitade*
dej^i enracint-eB.
Pour les ji^ands cirques^ il faut s*atteiidre h voir survivre, quoi
que Foil fasse, Platon, Aristute, Ei^atoath^ne, Archimede, Ptolemi^
TycbOj Copernic, Kepler, Tous les objets sunt bien connus, tria
faciles a retrouver. Les noms qui leur sont donnas rappellent deo
illustrations incontestables, et assez anciennes pour nL^veiller
uucuiie jalousie, Aristarque, Eudoxe, Pliiie, Posidonias, Euclide,*
H^siode, Manilius^ Proclus, se reeouimandent par les memes
raiaons, si ce n'**st qu'ils rappellent des persounages moins celebres
on de moindrci* contributions h TAjitronoraie.
Lefl noms de savants moil ernes et ct^iix de savants anciens
donm^s k des objets peu apparenta serotit beaucoup plus facilemeni
abaudoniid^a, et pr(59entent des iDcoiiv^nients gent^ralement ressentia.
Leur TL-partition n'est pas confoniif* h Tequiti^*. tine repartition
nouvelle ne le serait pas non plus^ ou cesserait, apr^s peu d'annees,
de para! t re telle, Le nombre des cirques decor^^s de noms d'astro-
nomes est deja nne cbarge pour la nieraoire, lout en restant trus
au dessotia des exigences de la topograph ie. lieaucoup de cirques
portent deux noras d liferents dans les ouv rages les plus rt-pandus,
ceux de 8chmidt et de Neison. Assez souvent le uoni du meme
astronome u t'te applique k deux cinjue^ diff^reEts. Un change-
meiit total, en ce qui concerne les noms des cirques, a done des
chances d'tHre adoptt-, n'il est rationnel dans son princii^e et fadle
dans son application.
La projiositioo du Dr. Franz rev lent en aomoie k affecter une
combinaison de troia lettres, facile a prononcer, k obaque rectangle
de dix degrua de cote, taut en longitude qu'en latitude. Une
quatrieme lettre est ajoutee s'il est ut'ces&iire.
On renmrquera que la dt^signation du rectangle peut ^tre laiie
au moyen dc deux lettres setilement. Adoptant les memes dlTisioDS
que M, Franz, ou aura i6 fuseaux en longitude, i6 baudee ea
latitude. On leui atfecteta \e.& \6 ^T«v\u^r«« lettree de Tiilphabet
Dec 1907.
Lmiar Notiicriclature.
139
latiii, respectivement majtisculea et iDmuscules. On aura ainsi le
tableau I, dont le rt^tablisaement n'exigera, pour aiuai dire, aucun
effort de m(?raoire.
La d*'sigiiation de ces couples de lettres sera moins d<'ii!itui^e
par lea prouonciations ilivereea que celle dea mots de trois lettrea.
BIU« ^TeiUerd moiaa sou vent di^s associations d'id^es btzArren qu
trivialesy et i\ sera plus ai^u de la rctablir sans avoir le tableau
sous les yeux.
II s'agit main tenant de subdiviser lea rectangles, Le iJr, Franz
9e aert a cet efFet de bandes mmdiennes, de largeur indtitermini^t?,
A cbacune de ces bandes eat affectoe une consonne, dan a un ordre
qui n'est pas Tordre alphaUHique. D'oii nc^cessiU'^ de demand er un
effort nouveau a la memoire ou de recourir au tableau.
n me sembte prt^fenible de faire suivre le couple de lettree d'un
couple de cbiffres. Ces deux cbit!res indiciueraient le nombre de
degn^a comptt^s de rorigine du carro, respectivetuent en kjtigitade
et en latitude^ josqu'au centre de la formation, Ainsi le nom de
Proclui? pourra <"itre nimplace par le signe I)g, 66» celui d'Hyginus
par le signe Hb, 68.
Daas le voiaioage des bords^ on pouvrait ^tre ament* a intro-
duirey au lieu du couple final de chiffres, deux coaplea de deux
chiffrea. Pour eviter cette complieatioUj il vaudra mieux adopter
uniformt^ment lo"" eomme largeur de tons tes fuseaux de longitude
et de toutes les bandes do latitude. Cela conduit h introduire
seulenient deux lettres de plus, com me le raontre le Tableau IL
Le signe de Proolua devient alors Eb,, 66, celui d'Hyginus li, 68.
II sera superflu d'inacrire sur le^ <artea le couple de lettres k
c6t<^ de cbacune des formations comprises daus un mSme rectangle
de 10*, II suffira que cette indication figure une fois vers le centre
du rectangle, \k oii se trouvera une place libre. L'inscnpti«>u des
chlSrea sur les forinationa sera remplac^e avec a vantage par une
petite cbifiTraison de i ^ 9, le long des parallel es et des meridiena.
Les 6ig:aes proposes jusqu'ici correspondent aux points
d'tateniection d'un r^seau dlvisanb la surface de la Lune en
rectangles de 1* de c6t^- La plupart des objets qui radritent
des noma, raesurant un degrci carrif^ ou davautage en surface, se
rtooTeront ainsi .suffisamment desigm's. On pourrait encore
cODVenir de souligner le couple de cbiffres, inf^rieurement s'il
a'^it d'un cirque, sup^rieurement a^il s^agit d'nne montagne isolee.
On eviterait ainsi d'avoir k specifier si Von a entendu nommer
one B^li© ou une dt'pression.
Le cas oh plusieurs points ^i designer ae pr<5senteraient dans un
oercle de 0^,5 de rayon, ayant pour centre un aommet du ruseau
sera exceptionnel. On pent cepenJant le pr^voir. I*e cercle en
question pouvra etre divist* en 12 secteurs de 30*, dt'sigru^^ chacun
par une des douze [iremieres lettres de Talpbabet grec, o, /3, , . . . v.
L'ordre alpbabetique suivra celui des secteurs, du Nord vers I'Est,
d Apr^ la convention adoptee pour les angles de position. On fera,
djuis oe cas, suivre le symbole precedemment adopte de \a \ftlVt%
grecque cunvenabje. AinBi L] 68 y sera un petit cratke 8vt\it 4auft
un rayon de i" environ a u tour d'Hyginus, 1 'origin e de Tangle de
position rtant non paa le centre d'Hyginiis, luais le sommet vomn
du r/'seau.
Four lea fieaurea la poiition du centre eat trop aujette k
discnsf^ion. Od pouvrait se contenter des num^ros du catalogue
de 8chinidt» precedes de la seuJe lettre S. Ainsi S 31 sem la
ji^nde fisiture d'Ariadseus. Je recommanderais, sans Tim poser, de
faire suivre ce symbole de Tangle de poaitioo moyen, exprim^ en
degr^s et mis entre parentheBes. Mais je serais d'avis de ne reporter
stir los cartes qtxe les fissures qui peuvent etre tra€^ mna incerti-
tudea au inoyen des photographies.
En r^'sume je propoae :
i'^ de nenen changer 4 Tusage actuel pour lea mera, lea golles,
les massifs de montagnes^ et pour seize grands cirriues dont j'ai
donne la liste; cette liste pouvant etre, si on le desire, un peu
etendue.
2** de diviaer Fh^misphfere visible par dea m^ridiena et des
paralleles en rectangles de i' de cdte, et de represeuter cbaque
sommet de ce rectangle par un symbole (deux lettres et deux
chitfre^), facile k retrouver ^ tout instant aaua Faide dWcun
document.
3" d'affecter tiux cirques, aux moutagnes ieolties, aux tachea,
le ftynibole du sommet du reseau qui torn be le plus pr^^ de lear
centre de gravite aji parent.
4*' d'indiquer par uu trait, quand eel a gembiera utile, e'il s^aifit
d'une formation a centre sailbnt ou si centre deprime,
5'' de garder Iti nomenclature de Schmidt pour les Assures,
<)n peut facilement pmisser la division de la surface plus loin
par lemploi de douze lettres gtecqnes, on TtHendre en longitrv
jiisqu-aux muridieuN +100'' et -100* par I'emploi des lett
acceutut'es A' et K, II est peu probable que Ton ait jamais
recourir k ces exptitlients, qui d'ailleurs ne demanderaient nu ^
derogation aux conventions pr^c^dentes et imposeraient pen
d'eifort k la rae moire.
Les tableaux suivanta (I et II) donnent la signification dei
symbol ea littt^raux, suivant que Ton adopt e le mode de division da
Dr. Franz on le mien, Le tableau III doane, dans la seconde
hy pothtee, les syra boles qui repondent aux points du premier
ordre, Les courdonnees adopti'es sont celles de Neison. II y
auTftit lieu, si ma propositi^ju est adopt^^e, de revoir ce tableau en
ayant egard aux determinations plus recentea.
P. Puisiux
1907 Nov4mhtr 16.
^B
^H
1Cteai907.
Ztmar Nomenclature,
^H
^ Tarl
RAIT I.
LAtltUflti.
Tableau 11.
- ■
Longitude. L«tiiudi».
■ SoU
So U
+ 90' +90'
^^^1
80 A So '
^^^^1
■ 7aj
'°J.
70 "^ 70
^^H
■ 60
b
60
60 C 60 ^
^^H
H
c
D a
^^^^^H
H
y a
20 50
^^^^^^H
^^^
E ^ e
^^^^^^H
^^B 40
40
40 40 ^
^^^^^^H
^^H
e
F ,^ f
^^^^^^H
^^■^ 30
3** r
30 30
^^^^^^H
^m
f
fi K
^^^^^^H
^m 20 '
ao
20 20 ^
^^^^^^H
H
g
fl b
^^^^^^1
^1 -fto ^
+ 10 :
+ 10 410
^^^^^^^H
■
h
I „ i
j^^^^^H
H
0 .
0 0
^^^^^^H
H
1
. J . J
^^^^^^H
H -10
- 10
- 10 - to ^
^^^^^^H
H
J
K k
^^^^^^H
H ^
^ t
20 20
^^^^^^H
H.
k
L I
^^^^^^H
^^_ JO
30 1
30 *" 30
I^^^^^^H
^^H
1
M ^ «i
^^^^^^H
^^B 40
40
40 40
^^^^^^H
^^^
m
N , 0
^^^^^^H
^^ so
50
SO 50
^^^^^^H
■ 60 "^
ti
60
eio ^ 60 ^
^^H
H
0
p p
^^^^^^H
■
70
70 * 70 ^
^^^^H
b:}'
So ^ 80 ^
^^^^M
R r
^^^^H
-90 -90
,^^1
■
Tableau IIL
'^H
IV HI.
04
Burg
Ge, 8s
Oaasendi
Nk, 07 H
l^gBios Ik,
41
Byrgius, A.
PI, 44
GoclflDlUA
^ICt 40 ^1
toiiM, A. Jk,
33
Campatian
L), 78
Grimaldi, A.
<^i 15 H
mm Id,
48
CAp€ik
Mj. 58
Giierike, C,
H
■k. A. Jg.
7S
Carlini
Lnj, 43
Hainzel, A.
Lri, ^M
■• Kg.
73
CftBslQij A*
In, 40
H»lley
H
B
14
Ceusorinus
Fj. 20
Hansen, A.
43 ■
Be. 6d,
47
C^phie, A.
Ee, 61
Harding
13 H
Ks. Uk,
75
Clavius, C.
Kij, 57
Harpalua
Nd, 42 H
■
72
CleomMe. A.
Dg, 4^
Hell
Jm, 82 ^M
■
04
CoDoa
Ig, 21
H<5raolidc
M^ 41 H
^W
02
Coffertiic
Lu og
Hercule
Fe, 86 ■
^^B
37
Criiger
f% 77
Hereclit'l
H
^H
19
Cyrillc
Gk, 34
H^aiode, B
■
^^H
39
Del&mbre
Hj. 72
Hipparque, C.
87 ■
^^Ba.
97
Flamsteed
Nj, 45
Htpl>arqiie, L.
H
^H Mg.
61
Furtjorius, A.
Cm, 8j
Horrockfi
■
^^*
20
■
Gamhart, A.
Ki, 9r
HorteiiBiu*
u, ^ H
142
Lunai' Nomenchture.
Lxmi 2.
Tablkau IIL— <»ii/i*i«i^.
E^pler
Mi,
S8
Morttus
K
70
Lahire
Kg.
57
Most in f?
Jj.
61
Lal&nde
rh
94
Moating, A.
Jj.
53
Lauddberg
Lf,
6o
Murchison, A.
\h
14
LftUtlaberg, A.
Mi,
10
Mtitus
Gp,
93
L&ngreDii«
^^'h
iS
Olbers
Qi.
S8
La Peyrouse, A*
Bj.
49
Pany, A.
Kj,
69
Laplace, A.
Le,
73
Pctanos
Dl,
95
Lb Motmier. A.
Og.
96
rhocjlides, E.
Oo.
65,
LichtatitwTg
Pf.
7f
Picard
Db,
44
Lmdermu
Gm.
42
Piooolomini
Fl,
29
LiuijL^
Hk.
28
Picon
Je,
95
Madler
Gk,
91
PitisGUs
Fo.
00
MagiuuB
Jo,
70
Pline
Gb,
35
MaiiiliuH
Ih,
94
roaidoaius, A.
Of,
92
Mariufl
Ok.
02
Proclus
Eh,
76,
Mftskelyne
Mi,
03
Ptol^mcP, A.
Jj.
19
MaiirolycuH,
Hn,
43
Pytbttgore
Pc.
^3
Mnyer
Lb,
96
Pytht-as
Lg,
10
Menelaus
Hh,
66
Raoisdeti
Mm,
22
MifBHit;!
Ej.
72
Rein hold
Li,
33
Milichius
Mh,
00
Romer
Roaae
Sacrobo«co
Scbeiuer. A,
Schobert, A.
SeleiU'Ub
Struve, B.
Taruntiua
Tbales
Tbebit, A.
Theopbde
Timocbam,
Tycbo
Ukert
Vega, A.
Vifete, A.
Vitello
Vitruvc
Werner
Wicbmann
WoUaston
Fk, 4
HI ^
Bi. 64
Tl» 61
Gk» 6t
Kg, 37
Kik, 2|
li \%
Cn. 95:
Om, 71
Mm* 70
Fb. iS
11^ 3«
Mj, at
Nf. 7^
PllOPBSSOR W. H. PlCKKRINO'a PROPOSALS.
It does not seem to the writer practicable to abolish the systen*
of names at present applied iu the chief lunar craters* A supple-
mentary system of uomeuclature for designating the minor points,
however, seems to him very deairable. He would therefore make
the following sijg^estionR to the Committee on Nomenclature.
A series of photographs should be taken, or, if practicable,
negatives already taken should be used. These should be enlarged
through a reticule to a uniform scale of 400 nmu to the Moon's
diameter. The positives should be on platea measuring 20 x 25 cm.
The enlargements should be made througli a reticule of squares.,
each square measuring 20 mm. on a side. These positives would
form a set of standards which should be safely stored From them
negatives should he printed which could be furnished to engravers,
photographers, or the public. The reticule should be oriented
parallel to the Moon's axis.
Since it is desirable to get all the detail possible, and since the
maximnm detail is shown only near the terminator^ it is prop
Dec. 1907.
Lunar Nomenclature,
Hi
Ui ttse pbatogtaphs taken at eight diJfertfiit ages of the Moon, one
set representing the northern hemisphere and the other the
southero. This will give us sixteen diderent photographs. Each
of these should be .selected in fis favourable a lib ration as possible.
Besides the lunar detaO which sbowa near the terminator, there
i^ an entirely ditferent kind of detail, consisting of bright and dark
surfaces, and of bright puints which ishow ordy wbun reniote from
the t*^rminator. Six plates should be taken to show this detail,
three for each hemisphere. These would be taken wlien the
terminator is distant, but not uet^essarily at full moon. This
\rould give us a class of detail which has not been so carefully
smditnl as that at the terminator, and for thii^ reason is of all the
mort< importance.
We thus have in all twenty 4wo stamlard platea. While it
would V>e de?^irable to have an atlas engraved from them which
P E F C N I K L M N
leOT^^^T
I^^S^^^^^ll
SSl»9s^Sh^yf%3bs^SF^^^I^
covild be issued to the public, this would not be necessary, since a
j-^rolographic edition of the whole twenty-two would not be very
V oMve, It should be possible for those interested to buy
pbofcogniph* of a single region.
The positive standards should be lettered in capitals running
frofm the western to the ea^^tern limb, and in small letters running
from north to 8<»uth, Twenty-four letters shuidd be nse«i» j and w
being omitted. Around the selected region nf each standard a
hetvy black line shouhl be drawn, as shown in the figure, and the
regions outside of thin should not be used. The selectt^d regions
shiKild overlap slightly on the diiferent platen, which the use of
lwi;nty-four letters will permit. Otherwise only twenty letters
would be needed. Beginning at the western limb, two capitals
nhanld be assigned to the first plate, three to the second, and thie^
to the Ihird, Four capitals wlU be assfgned to the fourth p\ate, aa
144 LuTi^T Nomendalure, LXVin* 2,
shown in the sketch, and the aiime ftrrangemeni will apply to the
other quadrants.
Any area of the Moon's surface can now be indicated by two
letters. Thus Kq will be found on only a single sheet of the
atlas» and its exact area will be there clearly shown. The six
sheets taken away from the terminator, under high illunaination,
could be iudicated by the use of Greek letters.
The sides of the squares may be divided to tenths by the eye^
and the position of any point within the square indicated thas,
** Kq 63," indicating that the point measures *6 way from the «ide
between J and K, and '3 way from the bottom of the square.
Should still greuter accuracy of designation be required, a milli-
metre scale could be used, and the point designated thus, ** Kq 65,
37," The aqn&refi measure approximately 100" on a side, so that
this system should give us all the accuracy needed,
A double catalogue would go with the atlas, one part giving the
old nomenclature of every point hitherto named in terms of the
new, and the other giving the new iu terms of the old. It is not
intended that this nomenclature should supersede the older one ;
the idea is simply to furnish one which shall be purely supple-
mentary, and absolutely free from ambiguity. It could be made
readily accessible to all, so that for purely scientific work anyone
could use it who chose to do so ; and since the older nomenclature
would also be given in the catalogue^ no one need feel compelled
to use the supplementary system who did not like it.
William H. Pickering.
1907 No^^eniber 8.
Mr. Bau»dbr*8 Proposals.
I
I have already expressed my views as to the best method o^
dealing with the problem presented by the present condition c>C
Lunar Nomenohiture in M.A.S, Monthly Notices, Ixvi, p. 41^ a.xi<i
in a note printed in view of the submission of the <juestion to tl^^
Vienna Congress. It might, however, be convenient if I auraraarx^^
them here.
I am not in favour of any radical change. So much work <**
permanent value has been published in terms of the old noni^'O'
clature that it can never be entirely superseded, and 10 cr&^^
another, to be used concurrently with it, would» in mj opinioOi
only increase the confusion.
The present nomenclature, however, does require careful revisi^^
in order to ensure that —
(i) No two formations should have the same name,
(2) No formation should have more than one name.
In assigning tiauies for future use I would suggest the
general rules —
([) That Madler's principal names be retained.
e foUo^iv^L
Doc. 1907.
Lmmr Kormnclaiure,
14s
^(a) Tlittt where Miidler has not given princi[)al names, as little
eration as possible be made in immes now generally accepted,
ese rules should not prevent the Comtnittee from rejectiog a
u»rae alto^'ether where none aeems required, or from introducing a
I new one where one would be advantageuus.
t(5) For minor formations only two alphabets should be used ;
e capital Roman to denote craters, depressions, and dark areas ;
B amall Greek to denote peaks and bright spots,
(4) Such rills as are in Schmidts catalogue might be denoted
r their catalogue numbers, others by a short reference to their
i»ition.
I have always thought that the best method of publishing
e decisions of the Committee would be to embody them in an
accurate map, which must be specially prepared. Bi»t the practical
difficulties appeared so great that I j^uggested the use of j>hotograph8,
very much as Professor W, H. Pickering now does, though I had
not thought out the arrangement in so much detail
Dr, Franz has, however, in a recent letter, suggested thfj con-
straction of an atlas giving accurate outlines and positions of all
the more prominent features, but not presenting the minute detail.
The different parts of the surface would be represented in a series
of maps, and he has offered to be responsilde lor the limb regions
if I would undertake the central parts. Br. Franz has made a
special study of the limb, and has accumulat^^d a large number of
mipublishetl measures. His maps woukl be constructed under
favourable librations of 10". \ have a large imniber of measures
of the central regions besides those already publishetl; and as Mr,
^ H, Wesley has kindly placetl his great skill as a draiightsman
the disposal of the Conimittee for the delineation nl these parts,
1 Ui rne that the construction of such a map is now quite
bie* The maps of the central regions wnul<l be under mean
libmtion.
^_^ I believe that witii the data now available a map might be
^Hnii»tructed In which the positions of all objects shown would be
^KcurBt^ to within Jess than l" of arc (geocentric), conesponding
^^B less than one mile on the surface of the ^loon for the central
^^ftrt« whilst the measured points are so thickly distributed that an
^^Bijeci not represented in tlic map, but whose position cuold he
^Seated by cross bearings from points that are represented, could
^|fe¥e ita co-ordinafes read off to very nearly this degree of
' iccurftcy.
I With such a map it would be possible to refer to unnamed
^Armiitions by means of their selenographical co-ordinates, and I
^Hnlieve this to be the best solution of the problem that has yet
Wq suggested^
S. A. Saundeb.
la
MONTHLY NOTICES
OF THB
ROYAL ASTRONOMICAL SOCIETY.
oi, LXVril.
January ro, 1908.
No. 3
[B. F. Nbwall, Esq., M.A., F.E.S., Presidbnt, in the Chair.
^KHenry Boase Austin, J,R, GovcTnmeat Buildings, Bloemfoutein,
^K Oraii^e liiver Colony, South Africa ;
W. Geoffrey Duffield, Physifal Laboratory, Manchester ;
Win. Eamshaw Etzel, B.S., Litt.L., M.S.M.F., Professor of
Sciences, St Bernard's, Rochester, N.Y,, U»S.A. ;
^ John M. Field, i Hart Street, Edinburgh ;
^LJames D. Maddrill, Ph.D., International Latitude Obsarvatory,
^ Ukiah, Calif ornia* U.S. A,;
William Henry Rees, B.Sc», County School, Pontypridd, and
2 Craigwen Place, Pontypridd, South Wales;
iTboiuas James Forrester Smith, Neweleati, Wavertree,
Liverpool ; and
I Captain James Weir, F.R.G.S., Examiner of Maaters and
Mates in Navigation and Seamanship to the Board of Trade,
5 ClivB Terrace, Penarth, South Wales,
! biUloted for and duly elected FeUows of the Society.
fThe following candidateei were proposed for election as Fellows
lie Society, the names of the proposers from personal knowledge
Qg appended : —
Frederic Hermann Albert Alfred Buss, 2 Lansdowne Terrace,
Grosvenor Square, Asbton-on-Mersey, near Manchester
(prupof^d by A. Fowler) ;
Arthur da Pr^ Denning, M.Sc, Ph.D,, Lecturer in Physics,
Birmingham University, iS Lightwoods Hill, Birminghaoi
proposed by William Brigge);
II
148
Prof* Ernmt W, Brawn^ On the
LXYIILJ,
Herbert Shaw, Royal College of Science, South Kensington, S.W,
(proposed by A« Fowler) ; and
James Henry Worthington, Student in the Umversity of Oxford^
Biiidon, Wellington, Someraot (proposed by H. H. Turner).
Sixty presents were announced as having been received since the
last meeting, induding, amiaigat others : —
E. T, ^Vhittaker, The Theory of Optical Instruments, presented
Viy the authr^r; framed photograph of 14th century clock restoreil
by J. J, Hall, presented by Mr. Hall ; Caletidrier Perpctuel, pre-
sented by M. Bosson.
^ ^ Seven transparencies of Sun-spots, Comet, Planets, and Nebula,
from negatives tak«n at the Royal Observatory, Greenwich, pre-
sented by the Astronomer Royal.
J, C. Kapteyti, On the number of atars of determined magni-
tude and determined galactic latitude (Pub. Aetron, Li^borator>',
Groningen, No. 18), presented by Professor Kapteyn.
On the Lunar Itm/ualifies dite to Planeiary Action.
By Ernest W. Brown, D.Sc, RR.S.
I, I Imve lately tiniahed the computation of the terms in tie
Moon's motion due to the actions — direct and indirect — of the
planets^ and it is of interest to compare the results with those of
previous investigators. There are two extensive lists in print :
one given by Radau * in 1S92, and the other by Newcombt
a few months ago. Both of tliese give only the terms in U>ngitude»
and 1 shiill therefore limit the results set forth here for disouBsion
to these terms, reserving the complete list for a memoir, containing
also my methods and the details, which I hope to present to the
Society at a later date. I have also omitted here the seeular terms
and those which depend solely on the lunar arguments, since the
results for them are not in doubt, and since tbey will ultimately be
combined with terms arising from the figure of the Earth, Further,
I only consider quantities of the first order relative to the planetary
masses, while New comb has included the mutual perturbations
in his values for the direct action. But the latter do not affect
any of the terms except one or two of long period, mentioned in
No. 10 below.
The great majority {about 400) of the terms are of short period^
* ** Reoherches oonoemant lea In^galit^s pUn^tdres dn mouvenumt de U
LnD«,*' Paris Obn. Ann, (Jtf<^)i.), vol xii.
t " InvflstigatioD of Inequalities in the motion af th« Moon prodtioed by
the Acthn of the planets/' Carn^i* Iwil. PnAC, 72.
Jan. 1908. Lunar Ine^MUies due to Planetary Action. 149
mad are most convenieQtly added to the true longitude. The terms
o( very long period are best added to the njean longitude, aod
they are ao set down here ; but thu changes in tLe other elements
for these long period terras are not given, since they can be ex-
hibited as simple ratios to the mean loogitudo portions. Kadau
adds these long period terms to the true longittidei and I have
therefore dropped the corresponding short period terms which he
gives.
In his final results, Xewcomb drops coeftlcients less than
o''oo3. I have done the same in traiiscribiug from my manu-
Bcript^, except occasionally where a smaller cotdhcient comes in the
middle of a Jong series, or where Kewcomb or Radau give 0
coefficient greater than o''oo2. All my coethcients have been
computed to o"*ooi except those of a few long period terms in ^j ;
tbeae exceptions are noted hy a comma placed before the zero,
which is set down as the last figure in order not to break the
continuity of the representation.
2, The notation for the arguments of the tables is as follows : —
f,2D,F,the mean anomaly, the argument of the
" variation " and the principal argument
of the latitude of the Moon.
V *, the Moon's true longitude.
Wj , the Moon's mean longitude.
Q , V , T , M , J , 8 , the mean longitudes of Mercury, Venus, the
Earth, Mars, Jupiter, and Saturn,
, ft=D- F + T, the mean longitude of the Moon's node.
The results are arranged in six columns. The first pair, headed
i^B, contains the coefficient and angle as computed by myself' ; the
ond pair^ headed N, those of Newcomb ; the third pair, headed
""R, those of Radau, The coefficients are given in units of ©"'ooi.
The angle has, except in Stt?j, been divided into four parts for
ooovenience: ^ contains the lunar arguments T^D, F^/j; a, the
constant part of the angle so taken that the coefficients are all
ftitive; y,/ the multiples of T- P and T (or j ,f the multiples
^if P— T and P) so that/ (or/') represents the order of the term
with reference to the eccentricities and inclination of tlie Earth and
planets. The values of/ (or/) and <^, one*? given, are understood
to be the same for every following term until new valuea are set
down. The differences betweeo the results of Newcomb and
iDjself are marked with the letters Ej , E^ , Eg , U whenever thej
eocceed o"'02o, and they are considered in No. S below.
* An italic capiul to difltlnguish from tho mean longitnde of Venas«
ISO
Prof. JSmed W. Bmon, On the
« F- + o'-ooi C Bin {^ +y(T - V) +/T + a} , V«
^«o
B
N
J f
c
«
c
«
C
I O
822
0
o-o
882
•
O'l
860
2
307
179-8
401
179*3
283
3
42
359*3
37
1-6
65
4
46
0
5
33
0
6
24
0
7
17
0
8
12
0
9
8
0
lO
6
0
II
21
4
5
0
0
-2 I
10
254
-I
16
84
14
85
42
82
55
81-5
34«
272-9
354
2762
348
176
2717
197
272*2
181
2
82
4
271
6
272
4
272
-I 2
3
5
27
25
3
33
5
34
92
199-0
82
208 -0
80
26
204
9
17
4
207
5 3
26
114
23
112
"^'^1^. 1908. Lo'iKir lae>inid'ii\i:!i, due. to riaiutary Action. 153
} r
C
a
C
a
c
«
3 2
14
210
23
201
0
4
4
205
5
3
19
6
16
198
5 -2
3
161
4
4
336
22
336
3
15
331
5 3
4
"5
5
"5
5 -3
4
65
5
65
aD-l
10 0
3
180
9
6
180
8
8
180
7
13
180
6
22
180
5
38
180
4
83
i8o-o
3
658
i8o-o
646
179-8
681
?8o
2
137
o-o
142
O'O
192
0
I
13
180
25
180
42
180
I
133
O'O
146
O'O
143
0
2
157
179-6
174
1800
172
180
3
14
178
14
i8o
18
180
4
3
180
iS
ri
0.
12
0
2 I
3
259
I
3
270
2
65
271-4
71
269-5
70
270
3
49
271-9
53
2737
50
270
4
5
90
20
126
273 "o
140
272
152
Frof, Ernest W. Brown, On the
LXVIIL 3.
2D
B
V
B
i
f
c
a
C
a
C
«
3
2
II
199
26
1997
»
3
202
4
20
-2
6
162
'5
342
35
339-8
3
7
15
4
151
I
0
4
180
5
180
-
6
180
6
180
8
180
6
180
10
180
61
o*o
71
0-6
129
iSo'o
149
i8o-o
66
180
E,
152
O'O
166
o-o
80
0
48
i8o-o
93
180
E,
127
180 -o
8
0
138
180
E,
II
180
21
30
0
56
0
I
4
258
I
79
4
80
8
75
3
80
46
271
82
273-1
^
40
272
41
271-8
5
272
4
92
23
6
272
12
273
-I
32
268
37
267-0
46
264
80
266-5
9
104
3
100
3
102
4
280
2
7
282
3
7
280
1. 1908. Lunar Inequalities dtis to Planetary Action, 155
9i
B
N
J f
C
a
•
C
a
•
2 0
5
0
X
10
180
I
10
0
2
6
180
3
9
180
2 I
3
273
2 -1
3
267
rf-aD
2 0
7
0
9
0
X
5
180
7
180
2
3
180
8
180
3
73
i8o-o
72
180*0
4
3
0
4 I
4
92
-20-1
7
267
' 3
3
268
- 2
3
268
3
261
6 2
6a
17-4
62
i7*5
-♦tJ-l
I 0
6
180
2
7
0
3/^aD
3 0
3
180
3
180
6 2
5
18
3
26
»* -4D
3 0
8
0
-4D
3 0
7
0
-D
3 I
5
273
*.D
3 I
II
273
^+aD
2 0
0
3
0
75
63
180
17
3« 914
48 91-4
156
Prof. Envut W. Broum, On the
Lxvm. 3,
h
B
i /
C
a
- 5 -2
3
255'
■ 4
9
255
3
i6
75
2
5
75
A+2F
2 -3
3
75
16 256
0^= +o''*ooi C sin (^ + a).
I3T-8V
237
313-9
247
316-1
250
3187
Z+I6T-I8V
1449,0
151 "O
1477.0
1 50- 1
1442,0
150
/ + 3T-10V
35,0
33
Z + 29T-26V
108
II2-0
no
121
2F-2D + 6T-5V
54
270-0
60
269
3Z-2D + 24(T-V)
10
0
12
0
D + /-F+17T- 18V
8
75
F + 24T-23V
3
285
8
0
D+12T-15V
13
262
16
261
D + 25T-23V
13
190
19
X94*5
3D -2F+18T-18V
2
272
8
0
tD-2F-Z-22T + 23V
<I0
4
284
D-2/-20T + 21V
0
3
288
8i(/i= +o'''ooi C sin (^ + a), Mercury.
Q-4T
3
239
2D-Z-3Q+T
75
105
2D-i-4Q + 5T
3
113
/-aF + 4Q-3T
3
"3
57 150
6 105
7 105
Jan. igoS. LwMir InequalUies due to Planetary Action, 157
8F« + o'-ooi G sin {^ +i(M - T) +/M + o}, Man.
♦-0
B
V
B
r
C
«
C
«
C
«
0
II
180*
II
174
14
180*
195
180*2
224
180
228
180
B|
14
357
14
0
16
0
5
349
I
6
260
0
30
82
U
3*7
224*4
373
229*2
422
229
Bi
38
212-4
42
213-6
53
213
48
212-5
47
212*9
55
212
10
331
2
93
244-8
95
2498
112
247
ao
245
30
120
U
14
244
6
62
3
16
277
13
276
6
275
3
94
0
5
0
6
0
16
0
4
180
44
181
50
180 -o
59
180
5
0
' J
t
^3
6
224
212
52
225*0
30
224
E,
8
3
214
37
28
214
E,
158
Prof. Ernest W. Brawn, On the
Lxvm. 3,
sD
B
N
J r
C
a
C
a
5 -I
3
149'
•
3
I
327
5
333
2
3
328
I
23
317
58
316-8
3
3
280
2 2
5
244
3
4
244
4
4
246
315
297
I
3 0
3
180
3
180
2
38
0
43
0*0
I
4
0
4
0
I
5
180
4.
180
2
43
180
48
180
3
3
0
3
0
4
3
180
0 I
0
3
80
I
73
2233
55
219-9
2
xo
2x2
9
215
3
'3
213
10
215
5
8
198
3 -I
9
330
10
324
2
8
327
9
324
I
74
306-3
55
318-9
0
0
3
99
2 2
17
245
'7
244
3
5
245
4
3
244
6
6
63
4 -2
3
296
3
5
295
2
18
295
17
296
26
0
35
230
36 310
306
Jan. igoS. Lunar InequaUUes du$ to IHaniiary Adiim. 159
aD-l
B
K
&
i r
c
«
C
«
c
•
5 0
3
180*
e
•
4
90
i8a
19
180
3
5
0
6
0
a
13
0
17
0
34
0
I
3
0
4
0
7
0
I
8
180
5
180
9
180
3
61
181
66
180-0
73
180
3
5
353
3
0
I I
31
320
41
226*4
47
223
2
II.
212
9
215
3
14
214
13
«5
4
3
27
6 -I
3
149
5
43
162
42
148
4
3
329
3
3
327
5
333
2
6
328
6
324
I
35
320
43
316-9
51
317
3
4
280
2 2
II
244
9
244
3
6
244
4
5
245
6 -2
33
298
3
3
296
2
14
297
II
294
aD+<
2 0
6
180
4
0
I I
3
82
I -I
3
93
tI
2 0
3
0
2
3
180
I I
3
232
I -I
3
308
i6o
Prof. Hmest W, Brovm^ On the
LZvnL 3,
2/-2D
B
} r
C
a
c
■ 2 0
4
0
0
4
5 I
17
209
6 2
x8
244
17 212
8w,= +o"-ooi C sin (<^ + a), Mars.
SM-4T
3
3x0
9M-5T
8
305
IIM-6T
6
335
I3M-7T
6
19
I5M-8T
26
43
I7M - 9T
4
63
4D-3Z+25M-23T
4,0
67
/t + 2M-T
17
165
D-/-4M + 3T
<IO
19
3
164
153
87= +o''ooi C sin {<^+y(J-T)+7-J + a}, Jupiter.
j r
c
B
a
C
a
]
0
a
I 0
643
178-8
741
178-8
646
18^
Bi
2
187
359'6
242
359-8
196
0
Kv
3
10
7
9
6
12
0
3 '
6
257
6
80
■ 2
18
274
16
275
0
87
289-9
1S3
283*0
139
279
\3
I
165
241-5
193
2427
172
242
^
2
52
352-0
42
777
49
352
T3
3
4
355
I 2
10
250
0
5
324
I
25
23^
24
«3
2
6
344
I i
3
230
an. 1908. * lAima/r Ineqiuilities due to Planetary Action. 16
2D
B
N
1
^\
3 0
C
4
a
0
0
C
18
i
C
a
0
E2
2
70
180*0
18
0
54
180
E,
I
33
I'l
16
0
45
0
I
167
178-5
168
177-9
175
180
2
85
359*2
92
359-3
88
0
3
7
13
74
2*3
U
0 I
27
349
36
350*5
32
350
X
35
2365
89
237-4
39
238
E,
2
«5
352
42
354*5
E,
-2-1
30
8
7
9
E.
- 1
6
313
15
3"
0
33
184
40
181 -o
38
189
2
9
273
38
2720
Ei
3
6
102
19
105
' 2
5
3
236
345
10
240
- 2
3
6
200
no
0
1
170
4
180
36
180
45
180
12
180
144
I'O
140
1-6
36
0
158
179*0
163
178-6
48
180
190
i8o-o
64
O'O
165
180
E,
5
21
3
0-0
6
274
6
270
62
282-3
38
7*5
El
39
242
36
268-4
96
352-5
10
351
65
353
E,
1 62
Prof. EmM W. Brwm, On the
LXVIII. 3,
I
B
K
B
i r
c
a
C
a
C
ft
•2-1
7
18^
10
.89
-I
35
298
32
278-6
O
63
2572
38
172-5
2
6
373
6
270
3
8
286
O 2
7
326
I
5
238
3
206
2
4
343
I -2
5
302
3
334
o
7
214
2D-«
■4 o
4
180
■3
22
182
18
0
2
II37
180-3
1 140
180 '2
881
180
■I
51
0-9
64
O'O
lOI
0
X
211
178-4
230
179-0
220
180
2
89
359*2
98
07
89
0
3
6
14
30
x"9
3 X
5
261
2
13
310
18
294
O
96
5 '5
60
353-4
60
351
I
46
237-0
48
2387
49
236
2
20
352
21
353
3 -X
6
187
2
436
7-5
445
7'5
316
7
■I
18
296
19
3"
25
304
o
60
174-2
62
182-2
63
184
2
16
273
18
276
3
7
102
I 2
6
237
4
237
2
3
344
2 -2
5
19
9
16
I
3
291
Jan. I ^08. Lwnar InegiualUies due to Planetary Action, 163
«D+.*
B
IT
i r-
c
a
c
a
-2 0
.80*
e
-I
I
I
21
178
II
0
2
359
6
180
0 I
353
I
237
2
352
0 - 1
182
2
273
af
-2 0
180
-I
II
2
I
12
178
2
10
180
0 I
293
I
239
-« -1
301
0
247
^-.t>
-^ 0
180
4
180
-I
II
2
II
0
I
0
2
240
179-9
256
i8o-o
° I
0
4
350
' I
284
172-5
258
172-3
-'^ X
2
302
3
298
^- ^
2
186
4
189
' ^
163
4D-^
^
180
358
179
^^ 1
7
2""*^
^
180
10
180
* 1
172
15
257
u
206 180
194 173 u
2 164
12
i64
Prof. Ernest W. Brtyum, On ths
LX
2«-4D
B
C
a
2 O
9
e
O
2 I
7
173
h
O I
4
Si
0 -2
o •
4
II
75
277
87= +o"-ooi C sin {«^+y(S-T)+/'S + a}, Saturn
♦=o
]
[i
N
i J"
C
a
c
a
c
I o
42
179-6
40
180 'O
38
2
8
0
8
0
O I
21
273
51
278-9
I
13
257
II
255
0 2
3
297
3D
I 0
lO
i8o
2
5
o
O I
4
270
I
3
257
O - I
4
255
I
I o
6
0
8
0
I
lO
180
8
180
2
3
180
0 I
12
263
4
275
I
3
257
I - 1
3
283
o
12
277
4
265
2D-1
■2 O
19
180
I
14
180
2
4
0
O I
6
271
I
3
257
-2 - I
5
271
O
6
267
180
Jan, 1908. Lmmr InequcUitus due to Planetary Action, 165
5. In order that the discusaion of the various differences may be
miide cleur, it is necessary to stnt© certain facts in the theory of
tbe^G inequalities which have considerable effect oa the titial results^
and nti the methods of obtainiiig them.
The disturbing function R is of the form —
K= 2{ Ao cos Q + Ai cos (/ + Q) + A^ cos (2D - Z + Q)
+ Ag cos {2D + ^ + Q) + A^ cos (2D + Q)
+ A5COs(2l)^2/ + Q)+ ..,,},
where Q here and throughout thb diacu-^sion is an angle depending
only on the solar and planetairy arguments, and where the suinma-
lion sign refers to the d life rent arguments Q.
Let Wy be the Moon's mean longitude, and e any one of the other
live lunar elements. \Vhen the value of R baa been substituted in
the equations of variations and the latter solved we obtain —
Ic.
= 2|q
" cos COS
[■
f/je term in 3c being ft sine or cosine according as r ie or is not an
*ogular element.
The values of the variations of the elements liave to be
«ix>)etituted in—
dV \^^_ . dV^
Now V consists of a non-periodic term Wj and periodic terms,
r= »r, + Vj^ sin / + t^o sin (2D - 0 + ''3 ^i" (2D + ^) + . * , . »
5[:J^cl from this we obtain easily the values of the deviatives of K
'■ ^K terniii which arise from the substitution of the variations of the
^i^sments in BV may therefore be divided into two classes. The
^*"^lof these, which I have called elsewhere* the priTnaiy terms,
^*^«i*bts of those terms in 5 V which arise from the variation of the
'^*^«j-periodic term ; the jiec(?w/an/ terms are those arising from the
^^ V^tiintion in the remaining, that is, the penodir t^^rms of V. Thus
*"^ i*alue$ of Sw^ constitute the primary terms, and all the other
F*^>*'tions of 8 V the sfiomdartj terni^.
Now the primary terms have the same arguments as the terms
*^ i, that is, the arguments
Q,/ + Q,2D-/-|-Q, . _ .,
^^*^ile the secondary terms have the argunietita
Q±(0.Q±(2D^/),Q±(2D + 0, • . . .
* fhfi ImMquaKim in ih» median qf ih$ rrwrn due ^ IHa direct action 0/ tK&
' »«f#, Pitt I*w«8, O^mhridge, igoj^
i66
Prof, Ernest JT. Broiim, On ih^
Lxvui. 3,
the argumenta arising from the iJerivatiyefi of V being enclosed in
brackets. It is therefore obvious that the arguments Q,/ + Q,
.... whicli are present iu the primary terms ^ill also appear
aujoiigst the aecomlary term a ; they are due to the separalion of
a product of a sine and a cosine into the sum or differeQce d
two sines,
4. The first result to be noted is the fact that thB sum of tkt
secondartea with arg^uinenh / + Q-(/),2DW + Q-(2D-/), . . ..
that is, those having the argument y» is verf/ iftfiall eanipared wUh
the f^oefficieftt of the primanj with argument Q.* In many cases
these secondaries are of the same order of magnitude as the
primary of tlie biime argument, the chief of them in general being
those arising from the two arguments just written down. This
theorem is a consequence of tlie method of the variation of arbitrary
constants. If we had adopted the straightforward method of
integrating the original equations for the M<Jon's motion with tJie
additional value of R due to planetary action, the terms inde-
pendent of ^ in the coordinates arising from the terms in R
which contain l^ and which therefore have the factor e (the lunar
eccentricity), would have jiossessed the factor e^, while the principal
terms due to R = A^ cos Q would not have this factor ; the former
terms muat tlierefor^ bp quite small.
This fact constitutes a useful test of the general accuracy of
a large portion of the work^ and it was satisfied in all cases as
closely as could be expected. It is illustrated in the following
table for a few terms of the indirect action uf Venus in longitude*
The first column gives the arguments of the primaries (that ia» of
the terms in R), and in line with them are the resulting secondaries
for the values of ^ which stand at the head of each column. The
last line but one gives the mxm% of these secondaries, and the last
line the coefficients of the primaries. The sums of these two tinea
constitute the complete coefficients for the indirect action. The
constant angle to be added to each argument is omitted, as it is
(in these and in most cases) very nearly the same for each of the
numbers in a given column.
5F=^o%
30 1 C sin
(* + **
),« = *T-
-i'V, Venus.
Values of C
primary.
T-V
T-SV
2T-2V
aT-2V
8T-SV
iT.av
BT-JT
^ + /
- 47
- 7
- 92
+ 18
-13
+ 21
+ 5
4»^l
^ 8
...
+ 21
+ 7
^ A
- 3
^ 7
^ + 2D-/
+ 42
+ 6
+ 70
- 20
+ 9
^ 18
- «;
^'2D+i
+ 18
+ 3
- 8
..i
- 3
^4^21-20
+ I
...
+ 1
0-2/+ 2D
+ 2
,.*
+ 2
Sums
+ 8
- I
+ 4
- 3
+ 1
- 3
0
^
-3S2
-14
-507
^-275
-51
+ «5S
^m
* Thi§ result Wiis not noticed until the conijwtiitions had been praoticallf
completed, when the approximate vanishing of the sums of the ^econdariti
in All oases pointed to a g^n«ml t\L«(OTencEi,
JsJL 1908. Lunar InequaiUu& due to Planetary/ AdioiL 167
5* At first sight it would appear that the argiamente of the two
formed, for example, from autijs «f producU like siu (/-f-Q)
(zD-/), that i% Z + Q±(2D-/), would have coethcients in
\ of the same order of niagDitude, It is not so whenever the
aents in R and V contain J, unlesii the arg^iment in R is of
long period (greater than a score or so of years). This fact
fht have been predicted from considerations of the same nature
Ihose in the previous paragraph. For example, an argument
f+ Q + (0 = Q + 3^ would not be expected from a direct method
of treatment to have a coefBcient nearly so Itirge as thai of 2/ + Q
^U^) = Q + /. The latter is frequently sensible, while there are
^B terms with the former arj^mment.
^H This arises, again, from the peculiarities of the method of the
PHriation of arbitrary constants. In the volume referred to above
I have shown directly from the method that if a term qfR contaiiis
its arguvmit (1^ i, 2, 3, ,..) and V a term i'l(i^ i, 2, 3, ..,),
(he geeondanj arising from the mm 0/ these argitmmti^ is
lys mnj smcdl compareit imtfi that arising from the difference^
(he period of tht primary is very long. This result was
ftved by inserting the terms due to Si, 5e, as given by the
eauations of variations, in 5 F. It enabled me to abbreviate the
tputations by some twenty or more per cent*^ siiice it rendered
separate computation of Se unnecessary except in a few easily
.^..^gniaed cases.
^^ 6, One other fact should bo not-ed. Although the coefficient
^Bthe evection (arg. 2D-/) is of order ^(1/13) comparetl with
^Kt of the principal elliptic term (arg. i), the numerical factors
^Bich it contains are so large that in certain functions of the
i|Bar co-ordinates it becomes equal to or of more importance than
Ihe principal elliptic term. It is therefore never safe to neglect
^tt former terms unless we know that the latter are quite insensible.
^B|9 shows most strongly in the arguments f + <^ in R for the
Tmirect action. The terms which multiply 8 V* (the portion of
the Earth's longitude due to the action of the planets) are chiefly
those due to the evection, while those which multiply hr {the
iaetary portion of the Earth's radius vector) are due to the evec-
l and the principal elliptic term. Yet the former portions in
ftral CHses are larger than the latter.
7. 77j^ differences B - R. Each of Radau's coefficients depend -
on the action of Venus is to be diminished by 1/5 1 of its
>aiit *^n account of ihe difference between the value for the mass
Venus adopted by him and that adopted by Newcorab and
fn3rMlf. Each coefficient due to Mercury is to be diminished by
7/60 of its amount for my adopter I value of the mass of that planet.
The equations of variations used by Radau appear bo require
orrection which would increase each coefficient in the ratio
95, Rjs I have shown in the volume previously referred to,
IS confirmed by Newcomb's results, for he obtains values for
t principai terms the same as those which I found in ih^ voWm^
bted.
i68
Prof, JSrnest W, Brown, On tlu
L3CV11L 3,
lit the priraary terma with arguoneiitB independent of the lunar
angles, Radau omits the portions due to the term of R whicU
dependa on r^ cos 2(F-T). These portions constitute about one*
eighth of the principal portions for the indirect action, and his
coefficients for this portion should therefore be diminished in the
ratio 7:8, The correspond! nj^ correction for the direct actiou is
smaller, and its amount depends on the particular term under coq-
sideration.
In the short period terma of the disturbing function for the in-
direct action of the form / + <^ he omits the portions multiplied by
hV*. These, as stated in No. 6 above, constitute a considerable
fraction of the whole. The terms proporfionatehj most affected are
those with this argument, hut the differences for the terms of
argument / -f <^ - (/) ai'e much larger, for the latter (secondary) terma
are about three times the tormer (primary) terms.
The discovery of the causes of divergence between the results of
Radau and myself was rendered difficult owing to the fact that,
although his secoinlary inequalities for the Venus terms of argument
1^ are given separately, and are in several cases quite large when
the theorem of No. 4 above shows that they ought to be qnite small,
yet his final coefficients very nearly agreed with mine. As a matter
of fact» 1 have founds from an examination of the separate portionh
of my results, that these corrections very nearly balance ope another
in the cixse of Venus, though they do not do sn with the other
planets, mir do they in the case of Venus with arguments other
than 4^.
I have compared mtist of Radau's individual results with mine,
and find a close agreement for nearly all those portions which he ha^
computed. For the direct action this agreement waa particnlarh
useful, since my coefficienta are obtained from formulae and metbod.^
radically di Cerent from his, though reducible to them by algebraicftl
processes.
Two other differences should be noticed, namely, those in the
terms with arguments - D 4- 4T - 3V and ^ - D + 4T - 3V, llie«
arise from the fact that the indirect action is a little greater and of
the opposite sign to the direct action ; Radau only takes the latter
into account.
8, 'fJie differences B-N, These have been marked with the
letters £,, E^, E, (explained), and U (unexplained), whenever tbej
exceed o '*b20.
Those marked
the variations of
three terma
E^ are due to the fact that Kewcomb substitutes
the elements in the value of V limited to
I -f- 26 sin / -f fe^ sin 2/,
th^J
instead of taking the complete value; he adds that *' in nearly or
quite all cases we may drop terms of the second order in eJ*
This third term of V in reality only produces a few* second ariei
with coefficitmts greater than o"o2o, and these arise in the form
2D - 2/ -f 0 + (j^j = 2I) + <t> ; ^>vv\. iVte ate many greater thac
lit 1908. Lunar fnequalities due to Planetary Adimi, 169
o"'oo3, the adopted Uralt below which coefficiente were dropiied.
The latter arise aUo in the forma / + ^ - (2?) and 2D - / + <^ + (2/).
A much more extended and larger mi of differences arises,
biiwever, from the n^lect of the ejection in the expression for V.
The majority of the differences Ej due to this cause will be found
in the combinations —
last being of importance only when 2/-2D'f<^ is of long
nod of the order of ten years, and the first quite rarely. Hence
be final coefficients of terms with arguments ^, 2D + 0 will be
chiefly affected, and a very few in those with arguments t + <^, from
this cauae. Ay those differences which may be nearly or altogether
explained by tne neglect of this and other terms in V are marked
Ej. I assume that the terms not present in Newcomb's list have
not been computed.
In order to examine the difTerences E^ a closer inspection is
necessary. On referring to Newcomb's tables for the variations of
the elements (p. 1 54 of his work), I End that under the argument
2D he has only the terms containing (Y-T) and 2(V-T) for
Venus, There are, however, several other arguments with coeffi-
ciienta of the same order of magnitude as these, and the same fact
appears to a smaller extent with the other planets. All differences
«^x plained by this cause have been marked E.^.
The small difference Eg in the great long period term due to
Venus scarcely needs explanatiijii* Newcomb has included the
portion (less than o"'io) due to the mutual perturbations of Venus
and the Earth, and he states that his method indicates a possible
error of the order o"'io. I exclude the former part, but the
maximiun error by my method should be leas than o'''o5.
Of the differences U there are two in Mai-s, eight in Jupiter,
and one in Saturn, The most impt^rtant is that in Jupiter with
argument J ; I have compared the several portions of any value
for the primary with that of Hadau, and the results (after the
' tions noted in No, 7 above have been made) agree for the
, ot action, but I have been unable to obtain his result for the
dif^ct action from the algebraical formulsB which he gives. The
cauiftes for the remaining differences I have not been able to trace,
and must leave the values of those coefficients an open question^
9. In working out the terms produced by planetary action, the
valuable memoir of M. Badau has been available for comparison of
results at almost every stage, and has materially assisted in the
priTention of errors made during the course of a piece of work of
great complexity, though not of great difficulty when once the
theory had been put into final shape. The woik oi Pt^Aftaaot
Newcomb only tippeHred when I had finished the peatet ^aiXi oi
170 fAvnar Inequalities dm t6 Flmietary Action, Lxvm. 3,
the computations, and would in any case not have been available
for detailed comparison without much labour, owing to the complete
diiference between his methml and mine. He combinesi the direct
and indirect actions at the earliest opportunity. I have kept
them separate until each wae fully completed. The comparison
between hie results and mine revealed one error in my work which
affected the primaries due to the terms with argument ^ in B by
about 5 per cent, and a few of the small eecoudaries from these
terms about twenty per cent. ; an error in the equations of varia-
tiona had almost no eflect. These errors have, of course, been
corrected in the results given above.
10. Like Professor Newcomb, I have also made an examination
of the inequalities of the second order relative to the planetary
masses, ami have so far found nothing that could sensibly affect the
motion of the Moon. I have found an additional portion to the
term with argument / + 3T - loV of the order of o"*2, but the period
of this term ia so long that it would scarcely aftect jhe observationB
within the degree of accuracy at present obtainable. The motion
iif the node of Venus also affects the term with argument
/+i6T-i8y by a quantity of the same order of magnitude.
The terms of the second order in the Sun's motion, as given in
New comb's Tables of the Sun,
,5F'= -o*'^265co8(4Mj- 7T, + 3Vi)-o"-o2iain(4M^ -yT^-f 3V^)
+ 3*76 cos (jJ^ - 8M^ + 4T1) + 5;i8 sin (3 J^ - 8M^ H- 4T1)
(where the sufhx denotes the mean anomalies of the planets instead
of the mean motions), or
+ 0^*266 sin ( I °*I90^ + 31**8) (period 300 years)
+ 6"'4o sin (o''202< + 231 "'2) (period 1 780 years) ,
will produce inequalities with the same arguments due to indirect
action having the approximate coefficients
- o*'04 and - 0**9
respectively. These results are Bulhciently accurate for tabular
purposes, but I shall give a more complete computation, with an
examination of the whole eftecfc of the terms of the second oilier.
1907 November 26.
Postscript, — Since this paper was sent in» I have computed the
terms due to the motiun of the ecliptic and have discovered a few
new inequalities containing the arguments of the planets. The
most im[)ortaut is one with a coetticient ©"'21 due to Jupiter, and
having a period of 280 years,
igoS Jamtartf lo.
Jan, 1908, Sir A Bcdl^ Note on the Single Eqitaiion^ etc, 171
Note tm the Single Equation which comprises the Theifrt/ 0/ the
Futtdamental Instrument a of the Obsercaiory. By Sir Robert
B%1J, LL.D., F.R.S.
We may conceive a generalised afitronomieal iustrument of
which the e^ential parts are as follows :• —
There is a fuDtlamental axis, which we shall diatinguish as axis
I* It 18 capable of rotatian iii tixed beariugs, and to it is attached
an index which pointH to a reading E on a fixed graduated circle A.
Axis I passes through the centre of A, and is normal to the plane
of A.
Axis II is capable of rotation in bearings fixed on axis I. A
second graduated circle B is attached to axis II which passes
through the centre of E, and is nomiul to its plane. The rrmding
of B is R', as shown by an index rigidly attached to I. it may be
obsenred that an index parallel to tiie intersections of the planes of
A and B will serve for reading both circles, and the geometry of
the question is simplified by employing this index.
It is necessary to distinguish between the two poles on the
celestial sphere which are defined by the plane of a gradnixted
circle. From one of these poles the y;raduation would appear to
increase clockwise. From the other pole the gradiiation would
appear to increase an ti- clock wise. It is the latter pole which we
shall here employ. The angle between I and 11 is the angle
(^ iSo°) between the poles of A and B. We shall express it by
90 - q.
The telescope is rigidly attached to axis 11, and when the
optical axis of the telescope is directed to a star, the arc {'^ 180')
from that star to the pole of B is also a constant of the instrument.
We shall denote it by 90* + r.
The seraiplane thmugh axis II and that half of the telescope
which contains the objective, cuts B at the ^'radtiation we shall
term A,
Let Ej, Rj' and R*^ R^' be the readings of the instrunjeiit when
directed successively to etars Sj and S^,, with celestial co-urdinates
a^» &j and Oj, ^, These co-ordinates may be altitude and azimuth,
or right ascension and declinatinn, or latitude and longitude, or any
system in which the fundamental rirclea are rectanguUi. T\\«u
the equation we desire is obtained by equating two dVffexft^V
172 Sir R, Ball, Nate on the Single £quationy etc.
expressions for the cosine of the arc between S| and S^* and it is
as follows : —
sin Sj sin B.j + cos Sj cos S^ cos (a^ - a„)
= +siirgsin-/'
+ cos^ q sin* r cos (R^ - R^)
+ cos* ^coa^ rain (R/ - A)8iii(Eo'- A)
+ cob2 r COS (Ri - Ka) cos ( R, ' - A ) coa ( K./ - A) (i)
+ ain- <7Coa- rcos (Ri - R,) sin (R/ - A) sin (Rj' - A)
+ cos* r sin ^ sin (El - R2)sin(R,' -U^)
+ cos g sin r cos r sin (Rj - R^) {cos (Rg' - A) - cos (R/ - A) }
+ singco8y8inrcoar(co8(Ri-R2)- i} {Hin(Rj'-A)
4- sin (R^'- A)}
By assigning suitable values to q and r, this formula can be
inadu to apply to tlie following astronomical instninients : — the
altazimuth, the meridian circle^ the prime vertical instrument, the
eqnatorial, and the almncantar. For the meridian circle q and r
should be each as near zero as possible, and for the alinucantar q
is the latitEde and r quite arbitrary. The following general proof
will show that tlie complete theory of each of the instruments
named must he included in this one formula.
From any such iustrument we demand no more than that the
two readings R and R' obtained hy directing the instrument to any
particular star shall enable lis to calculate the coordinated o^ S of
that star free from all instrumental errors.
Let Sj, Sg, Sjj he three standard stars of which the co-ordinates
are known, and let each of these stars he observed with the
g^ieralised instrument with results R^ R/ ; R^, R./ ; Rj, Rj
reapectively. Substituting for each of the three pairs (Sj Sj),
(Sg Sg), (Sg S^) in the typical formula (i), we obtain three in-
dependent equations. From these equations, 9, r, and A can be
found. Nor will there be any indeliniteness in the solution, for in
each case we may re^^ard these quantities as approximately known,
BO that to obtain the accnrate values of q, r, and A we shall ha^e
to solve only linear equations. We may thus regard (i) as an
equation connecting a^ Sj, a^ K,, Rj, R/, R^, Rj', and known
quantities.
Let S he the star whose co-ordinates o, S are sought. We
write the equation (i) for the pair (S S|), and mibstitnte their
numerical values for aj, 5^, Rj, 11^*. We thus have an equation
connecting the co-ordinates a, B of any star with its corresponding
R, R' and known numerical quantities. Wlien we substitute for
R and R' the values observed for S, the fornmla reduces to ft
numerical relation between the a and S of the particular star 8.
From the pair (S S.,) we hnd in like manner another quite in-
dependent numerical equation itividving a, 8. As, however, Uie
equations are not generally sufficient to determine a, 8 witheut
indefiniteness, we obtain a iVud ^t\\mt\vm from (S Sg), T\\U
Jait 1908. PcriurhiUiom of ffalUi^'s Comet in the Past 173
equ&tioii IB not independent of the others, but if we make x = siu S,
jfi^ccm S cos a, ; — CO8 8 sin a, we shall obtain three line&r equatioQM
in X, y, z which can be solved, and thua a and S are fotind without
any ambiguity whatever
All the ordinary formnlae aeed in connection with the different
instruments named can be deduced aa particular caset of the
general equation (i).
In general, there are no real valwes of H and R' when tbe
instnunent 13 directed to the pole of circle A. In such a case R
would have to be set on one of the itnaginory circular points, at
infinity.
2nd Januartf IQoS.
Th$ Pmiurbaticns of Halley*« Cotmt in the Pmt, Secoipf Paper^
The Apparition of 1222, By R H, Cowell, M,A., F.R.Sm
and A. C. D. Crommelin, B.A.
In the first paper of this series we identified the comet of
October 1301 with HalleyX and found the value 44"S58 for the
mean daily motion at that epoch We have now completed (with
the aid of ilr. F. E. CrippR) the calcuktion of the perturbations by
Jupiter and Saturn for the preceding revolution. As a first
approximation, Hind's date (mid-July 1223) was assumed for the
preceding perihelion passage, and on this assumption the results
were as follows : —
PtaMC
limit c»ftt.
dn.
dxD.
d^^
Jnpttor
0* 90
-"*2a6i
-357"
-6550
M
90*270
-•0S23
' 35
+ 6001
♦ ♦
370-360
+•5624
-183
- 353
Saturn
0- 90
-*o6i9
+ 12
'I784
M
90-270
+ •0636
- 39
+ 1602
♦♦
270-360
-'241 1
+ IS
+ 41
Sttin
+ '0146
-S87
-1043
Hence mean motion in
I a 23 = 44 '-858
'o"*ois
« 44 '^843
and calculated
period =
1296000"+ I
343 ' _
28934 days.
This indicated 1222 Augtiat 15 as the datw of the preceding
perihidion paaaage, or 1 1 months earlier than Hind's dale. T\\\% \&
too large a diaconhinoa to he possible, so Hind's identlfvcatvm ol
174
Messrs, Cowell a/td Crommdm,
Lxvm. 3
the comet of July 1223 with Halley's is erroneous. There w;
however, a much more remarkable comet which appeared at ttre
exact epoch iTidicated by the calculation ; and examination aho-^^-s
tbat the greater part uf the statements made concerning it "fciy
contemporary writers are quite consistent with its being Halley^'*^
00 that the identity is placed beyond reasonable doubt
The error of the first assumption is so great that it is necessaft.^17
to recompute the perturbations ; this hng as yet only been dc^Tie
approximately, the resulting date being 1 day earlier, or Augmzaat
14; the j?mall <1iflfevence between this and the preceding resolu vb
an illustration of the geneml proposition that the date of the m-^^n
remote perihelion passiitge need only be very roughly known b
order to obtain the periodic time correctly.
Pingre'B description of thifi comet is as follows ; " En Atitom. ^le,
c'est k-dire aux moie d'AoQt et de Septenibre, on vit une etoile dfl
premiere grandeur, fort rouge, et accompagnee d*une grande qu ^Ue
qu'elle utendait vers le haut du ciel, en forme d'un cone extremem ^nt
aigu : elle paraissait fort pres de la Terre : on To beer va (d^aborti)
vers le lieu oil le soleil se couche au mois de Decembre, L& J|
Aolit, jour de la premiere apparition de cette com^te (petit-etrei
Milan) la Luiie (nt comme raorte ; ello n^avait plus d*^clat, et elk
joignit la con^6te> Od vit eosoite cette com fete h I'occident, e*
m^me vera le nord, avant la fin du mois d'Aofit. En Chine on
Tobserva le 10 Septembre, entre-la constellation Kang (les pieds de
la Vierge, = t, k, X, ^ Virginis), Arcturus et la cbevelure de Berenice :
elle disparut le 8 Octobre. Le Pi^^re de Mailla dit qoe Im
Cbinois Tirent une com^te k Touest en 1222, a la premiere luoe:
c'est sans doute une erreur da copiste, il fawt lire a la hnitiime
lune."
The words in parentheses are not part of the original documentei
and Pingre's interpolation '^d^abord'' appears to be erroneous; it
is the place where the comet was last seen, not first seen* Wben
the comet extended its tail towards the zenith it must have been
nearly vertically above the Sun.
The following is the description in Williams* Chinese Obiervor
Hons of Comet b: — '*ln the reign of Ning Tsung, the 15th year of
the ef>och Kea Tiiig^ the 8th moon, day Kea Woo (=i:'3
September 15), a comet appeared in Yew She Te (17, r, v Bobtis).
Its luminous envelope was 30 cubits long. Its body was smaU, like
the planet Jupiter. 1 1 was seen for two months. It paaaed through
Te (a, ^, y^ i Librte), Fang (/?, S, tt Scorpii), and Sing {Antares, et^.),
and then disappeared/* (Williams, in this and other places,
erroneously gives v Bootis instead of v as one of the components oi
Yew She Te,)
Most of the above statements are satisfied by the following
orbit, in which the longitude of perihelion is that actually derived
from the perturbations^ and the date of perihelion passage ia S days
later than that indicated above; a perihelion distance somewhat
greater than the present value has been used. Hind found that
thia WOB also indicated m t\ie Tfttom oi \o66.
Jan. 1 908, Perturbations of Halleys Comet in the Past. 175
ElemenU in old System of Elements,
T = 1222. Aujfust 22.
SJ = 296*^5 I
Q ' 42 > Equinox of 1222.
' = 165 )
Motion retroi^rade.
W« have had to adsunie that the date when the comet was first
•^©n in China (in the region 1^, t, v Bootis) should be one lunar
'^onlh earlier than that given* or August 1 7 instead of September
' 5 - Our reasons are : (t) it is distinctly stated that tlie comet was
*^en for two^ months in Chioa, the final date bein^ Octah«r 8, the
position then being in Scorpio ; (2) we cannot make this a month
^t^r, for in November Scorpio was invisible ; (3) further, we are
*listinetly told that tlie comet was a splendid object in Europe in
'Xiiti. August, 80 tiiat it is moet improbnble that the Chinese should
^^^ire misaed it till a month later j (4) further, its geocentric motion
^^8 it that time 00 rapid that had it been in Bootes in mid-September
^t, ^ouM have been a morning-star on August 15, which it apparently
^«A not.
Another difficulty that we have to surmount is the phrase " La
Lune joignit la comete;" It was doubth^ss this phrase that led
E*ingre to the conclusion that the motion was from south to north,
^bich is in opposition to the Chinese account. Considering the
^^gueness of all European com^tary observations at that epoch,
^vu^e may look on the phrase as sufficiently satisfied by the fact that
tYx*i Moon (at her first quarter) and comet were ^*?ymmetn rally
placed above the western horizon an hour after sunset, though
s^pftrated by some 70*, There is one more point to notice* The
CO met is said to have been near An tares when last seen (October
S), Our chart showa that it was then in Libra, but the head wss
^00 near the Sun to be seen ; the tail would point to Antares, and,
coniidering its length, it may well have reached that star. It will
^ seen that we have given the European observations most weight
for dates, the Chinese most weight for the track among the stars,
This conclusion is in agreement with that re-ached in the case of
<>ther comets, including that of 1301. We have thus shown that
•*^ observations are satisfied witli no further alteration than they
^^ttld in any c^se require to render them t^elf-consistent, and the
®*Act coincidence of date leaves scarcely any room for doubt as to
J?* identity. Pingrc was prevented from making this ideotifica-
u^ by not knowing the wide range through which the period 01
MlJ^Y can alter, and doubtless his inference that the comet
*^^v^d at first from south to north put Hind off the track.
^ J t is of iiitereat to point out that the revolution 1222-1301 is
• longest on record, being 79 years 2 months-
It just exceeds
from 1066 to 1145, which was hitherto looked ot\ as \.\v^
^^«L The round now being accomplished is the Bhotteal ow
thx^
176
Me$$rs. Cfnmll m^d VTotnmdin^
MVIIL3,
Jan. 1908, FeHurhatiojis of JlalUy's Cornet in the Fasi. i jy
reeord, bstiiig only 74 years 5J montlis, a differeace of nearly
5 years.
Tbough the comprntatioiis for tbe revolutions io66-ii45»
1145-1222, are still incomplete, enou^^^li has been doue to make it
extremely prol:>able that Hindis identification is correct in each
CABe, though his elements of the apparition of 1066 clearly need
modification. They >liffer more widely from the }»re8ent elements
than perturbationsi will acconnt for However, the positiooa are
»o Tagnely recorded that larj^e alterations in them are possible.
l^Note otldetl January 2S. — Since writing this paper we have
done further work on the revolution 1 145-1222, the result of
which tends to the conclusion that the date of perihelion passage
in 1222 WHS in September rather than August, We are there-
fore gomewhat doubtful whether the date September 15 for the
comet being in Yew She Te may not be right after all ; if so, the
European dates require alteration. We shall return to this point
in a subsequent paper. It does not weaken the conclusion a^ to
the identity of the comet of 1222 with Halley's.]
Tables have now beeji couetructed giving the values of the
dctinite integrals for Jupiter and Saturn for the outer half of the
orbit. To use them, we have first to find the number of days from
perihelion to the extremities of the minor axis, which is done by
multiplying the period in days by the ntjmber whose log is 8*9825.
Henee we find Julian days of passing the points ^ = 90*, u = 270"",
and then find g for Jupiter and Saturn by the formuhe —
(Julian Bay - 2390645) 360*
V " ^3^85 ' '
_ (Julian Bay - 2388249) 360*
h 107607
Then the tables give the values of Jeln, J^fci, Jrf^, corresponding
to the values of g at first and third quadrant. The algebraical
gtun of the quantities has to be taken and added to that deduced
from the mechanical quadraturea.
The numbers from the tables should he moilified as follows : —
Multiply \dH by the number whose log is 4 [I'^S^S - log a],
the other columns by the number whose log ia [1*2585 -log a],
where a is given its value for the revolution under consideration.
Thi» does not apply to the constant part of \dts^ Jr/^ which ia
independent of a.
Messrs. Cowell and Crommelin,
Lxvni3,
Table of the definite integrals ^dn^ ^dts, \dl^f(yr Jupiter and Saturn l>^^
the naiues 90* and 2 70' 0/ u, the mmets eccentric anQrnaly,
Jiipit
ATtM =
90*.
JupiUr, u = »7q'.
>■ J*
J..
W
J*.
J..
J..
0 +*332o
10 +-3476
20 +'3595
^30^
-253
-191
+ 5434
+ 5955
+ 6237
+ "0932
+-0986
+ 0959
+ 23
+ 94
+ 161
•I2S
-121
*U3
30 -f36i6
40 +'3559
50 -^'3426
-124
' 53
+ 19
+6306
-f6i48
+ 5775
+ ^0852
+ •0673
4- '0426
+ 222
4-275
4-316
-104
- 85
- 67
60 +-3333
70 +-2976
80 +-26«i
+ 90
+ 156
+ 216
+ 5224
+ 4492
+ 3649
+ •0133
- -0210
-•0573
+ 347
+ 367
+ 374
- 45
- 24
I
90 +^235 1
100 -h '200 1
I to +*i63S
+ 26S
+ 310
+ 343
+ 27C4
+ 1700
+ 656
-•0953
-^t33«
- '1704
+ 36S
+ 352
+ 326
4- 20
+ 41
+ 59
120 4- '1271
130 +^3919
140 +-0581
+ 367
+ 3S2
- 39S
^1406
-23S6
-'2057
- '2379
-•2667
-K291
+ 250
4-201
+ 77
+ 98
+ 105
150 +*0267
160 - 10016
170 -0261
+ 374
+ 356
+ 329
-3290
-4106
-4815
-^2913
- *3n6
- -3267
+ 14S
+ 91
+ 32
4-116
4-122
4*128
180 - '0462
190 - '0619
200 - "0724
4-294
+ 252
+ 204
-5396
- S«52
-6159
- 33^4
-•3409
-'3400
' 26
- 84
-141
4-129
4-126
+ 121
210 -'0774
220 - ^0769
230 - *o7io
+ 149
-f 89
+ 27
-^6308
-6299
- 1334
- '3213
-^3046
-195
-244
-287
+ 113
+ 103
4- 88
240 -*0SS3
250 - 0401
260 - '0164
- 36
- 99
-161
-5776
-5258
-4582
--2817
' '2545
' '2234
-321
"349
-366
+ 70
+ 51
+ 31
270 +'0120
280 +'0453
290 +^0819
-220
-273
-319
-3765
-2817
-1766
-•1890
-1517
-1131
-375
-371
-356
+ 9
- U
- 36
300 4-M2IO
310 4^-1617
320 +*2023
-355
-380
'392
- 646
+ 523
+ 1691
- -0740
- '0359
+ ■0003
-329
^291
-242
- 57
' 78
- 94
330 -^241 1
340 +-2766
350 -I-3074
-390
-376
'347
+ 2740
+ 3833
+ 4722
+ '0323
+ *o594
4--oSoo
-184
-118
- 49
-109
-tig
-124
jdn jdx3 jdi
4-*o8o8 +38 4-1143"
+ '0743 +51 + 959
4- '0670 +63 4- 742
+ 'C^SS 4-72 -f SOI
+ *o498 4- 78 4- 246
-H'0406 4-81 - 14
S*ttir«k« HI
J-
^--0319 4-82
+ ^0238 + 80
+ "0160 +75
' 27r
- 510
- 729
4- 0092 4- 68 - 924
+ •0033 +60 - 1092
'0014 4-50 -1224
■0048 4-39 -1 32 1
^0070 +27 * 1382
- 0080 + 14 ' 1409
- *oo79 -f I - 1404
-•0066 -n -1365
- '0040 - 23 - 1280
^•0003 -35 -1179
4- 0044 - 46 - 1042
+ ^0100 - 56 - S79
+ 0165 -64 - 692
+ "0236 -71 - 485
4- 0312 - 76 - 267
4- -0394 -80 - 29
4-0478 -81 4-207
+ 1D558 -So + 442
+ •0638 -76 4- 668
-f 0710 -70 4* 877
4-0773 '61 4-1052
4-'0S27 -51 4- 121 1
4-0865 -39 4^1322
-(-•oSgi -25 4-1391
4- *o897 - 10 4- 1406
+ •0885 4» 6 +1370
- X»2S^^
--03S^i^
-1047^^
-•05&.-3
-*o6^^«
-■08 ^»c
-•oS
-*o8-
'•or
- 'O^
-'Ot
4-*o*:
4^*0«^
+ -«^^?
+
4-'oc:^
-00:^
4-'o855 4-23 4-1260 -'of^^
ConBUot iJArt of jdm (U be udded to tabular qiitutitiea) JupitiT - ^ *
Saturn - 24", Total - 136".
Oonfltant part of [(i((lo be add^ed Xct t&Wla? c^nautitiea) Japiter 4- z7*
Saturn 4- 765'', Totft\ -V- 34€>s"
Jan, 1908. PertMrbcdions of Halley*$ Comet in the Past 179
Aft an exam (lie of the use of these lahhs we may deduce the
Yatoes already obtained for the revolution 1835-1910 (Jf.A^., vol,
IxviL pp. 4T0j 4H, 519, 520). For Jupiter the values of /
ai t*==90*, «s=270*, are 296*"44, 3 2 2' 24, for Saturn i99**52,
Hence we obtain —
I-
J-.
h
2^ 90'
V'ro68
0
-343
-losit
». 270"*
+ '0074
-229
- 97
h 90^
+ •0097
' 55
- 887
M 270*
-'0190
T 71
+ 3
Sum 2(
+ ■1141
-S72
-"53
•0093
-126
- S84
Now log a for this revolution = 1*2480, whence we have to
multiply jdn by number whose log is '0262, J<to, jdl by number
whose log is '0105,
Perform ing the multiplication and adding the constants we
obtain —
?^
+ ■1213
- W99
698"
-153
+ 1519'
- 141
Efltaltft preTioui
obtained
»iy|
+ 1219
- *0I0I
^698
-153
+ 1532
- 142
A more complete investigation of the average motion of the
comet's perihelion has been made^ uain^ the results of all the
f •^volutions far which the perturbations have now been com|Hited.
It appear;? that the perihelion hiis a direct motion in lonijitude at
oriifjy the same rate a* the node, so that the periods of the various
planets for co-ordinates x y may be taken the same as those given
far z\ |), 112, The valuf> of ST for 19 10 should be 305'''64, not
jC3*'64 as printed on p, 112.
IS
i8o
Ph4>iographs of Comet d igoj {Daniel), lxvul 3,
PImiographB of Comet d 1907 {Daniel). By Dr, Max Wolf.
(Plate 6.)
Comet Daniel has been photographed at the 01 •
Konigatubl, Heidelberg, on the following nights, with tiie :
instruments : —
iHb. &*fii. (a) C-in. {b) t6-ln. («) i64u. (6) i&-\n.
1 t
I I
2
4
2
I I 4
I t 2
2
D»t«.
iH«
1907
Jaly 2t
22
1
Aug. 2
4
I
7
f
8
,..
9
...
It
...
14
t
27
*»*
• jon,
Six of these platen were taken hy Mr, Scheifele, 12 by Dr.
Kopff, and 23 by myseJf ; 9 are stereos.
Besides these photographs I have made six drawings with the
28'io. refb'L'tor, viz. on August 4, 7, 8, 9^ 11, and 14*
The most sinking result appears to me the difference bet^
the visual and the photograph appearances. All the drawings aho
a minimum of luminous radiation in or around the axis of the 1
in the region turned away from the Sun. All the photographs sha
the brightest taOa near the axis, exactly in the parts whei
there was a minimum of brightness.. This very curious
which was leniarked several years before in other comeu
graphed here, eeenis to be placed beyond doubt by the photogr
taken with the reflector.
Besides this, it ih very interesting, and perhaps in oppoail
with accepted theories, that the short aruis of the tails furik^
outside the axis are nearly all curved,
The following eight specimens are presented to the Society :-
I. Flat© Di44t
Reflector, i
Ii ni
907 Aug. 2 ; 14 44 '6 K
onigBtubl M.T,
2. If
Di47»
M
i» 4; 14 35'i
tt ••
3- M
DiS2,
i*
M 7 ; 14 5^'i
ft r»
4- t.
D155.
M
8; 14 42'2
11 ■*>
5. 11
D(6i,
'1
.1 9M4 59*6
t» ti
6. ff
D167,
}j
M n ; 15 s'2
tl II
7. ,»
I>J73»
11
>* 14; 15 S'2
J ! ♦!
8. ,,
A4850
, il-in
Unii,
i»
,, \i,\\% O'l
,, tl
Notices o*^ R AS
Vol. LXVin Plate 6.
Jan. 1908. JiiivmiiicUing the Field in a Transit Instr^iment 181
The lantern slides are a little eolarged from the origioal
negatives* On the slides from the re Hectnr-plates i degree equals
86 mm., aud 00 the slide of the i^in, lens 1 degree equals 4 mm.*
It is interesting to compare photographs 7 and 8, which were
taken at the same time> hut with very different optical means —
2S'in. ond ij in.
The tail on No. 8 is somewhat over 1 2 degpeea long, while the
small field of the reieotor gives the head and its neighltnurhood
only. The bright star near the heaii of the comet on No. 8 is
y Cieminorum.
* In the reproduction on Pkte 6 one degree ob the reflector plttte=79mm.|
mod oited«gree on the i^-in, lens plate =37 mm.
Htifklhtr^ (Kmigittihl),
1907 Zkcember lo.
i/fi an improved method of illmnhiaiing the field in a Transit
Insiru7ne7i(, and its effect o?i the discordance in rerersed
pjHitioiut of the instrument. By Sir W, H* M. Cliristie,
K.aB., F*a8., and H, A, H. Christie, B,A, (Plates 7, 8.)
It is known that with a reversible transit instrument observu-
tions made in the two positions of the instrument generally show
discordant restilts for clock error for stars reduced with the same
eoUimation error for the two positions. This discordance has
been attributed to what is called lateral flexure, and a correction
depending on cos Z.D. has sometimes been applied^ but at
Greenwich we never felt satistied that there was any real ground
for this assumption. We have suspected sometimes that it was
line to looseness in the mounting of the object-glass, and in the
Paris-Oreenwich longitude determination of 1888 this wns found
MO be the case with both the portable transits. But though tlus
was remedied by an improvement in the mounting of the < object-
glass, thia puzzling diacordantie still remained in subsequent
longitude determinations. Whilst there is in each series of
obsenrations a general tendency in one direction^ there are con-
siderable variations in the discordance between the mean clo^k
errors for each night in the two positions of the ins tin men t, as
wiU be seen from Tables L, IL, III., IV,, V., VIL, and VIII.
3Ir* Hollis, on thinking over the matter in connection with the
obserrations for longitude of Killorglin in 18 98 and of Paris in
1902, bad come to the conclusion that to obtain the correct
clock-error from the mean of results in reversed positions it was
neoeesary to keep the focus of the eyepiece absolutely fixed, and
tliat to secure this it was expedient to keep the diagonal eye-tube
which was used for the observations, and was liable to aag, t\v;\<iX"3
attached to the iuhe of the iiiBtrumenL In the Parifi Von^tai^
1 82 Sir IK H. M. and Mr. H. A. H, CkrMu, LXVIIL
5*
observatioas id 1902 special atientioa was paid to tliis, the ere-
piei^e bemg adjtistad to focas at the beginning of the evening,
and not altered afterwards. The di&cordance^ however, waa not
altogether got rid of, and on aome nights it exceeded 0**2 or 0**5.
There waa the further difficulty that, aa will presently be explained,
the observer^B eye is liable to change of focus when the bright star
comes into the field.
In 1906 and 1907 Mr. Harold Chriatie waa working with two
of the portable transits (B and C) previously used in the Paris
longitude determinations of 1888 and 1902, with a view to other
longitude determinations, and the large discordances in his results
lor the two positions again called attention to the question. He
noticed that if the eyepiece was adjusted for distinct vision of the
wires in an illuminated field a fresh adjustment was required when
the star appeared, the eyepiece having to be pulled out further
from the object-glass owing to change in the focus of the eye, the
wires being, by an unconscious mental procesai naturally referred to
a finite distance (say 2 or 3 feet), and the star, when it came in,
to an infinite distance. This change of focus still took place when
the other eye was covered up. He farther noticed (on March 1,
1907) that while adjusting the eyepiece for focus on a alow-moving
polar star the star seemed to cross the wire from one side to the
other as the eyepiece was moved in or out, the apparent movement
of the wire being as much as 20*. A similtir etfect hud been pre-
viously noticed on the meridian mark (a bright point) seen in an
illuminated field. It was at first thought that this might be due
to the wires not being exactly in the focus of the object-glass, but
readjustment of the focus failed to get rid of the effect. On trying
the same experiment on Polaris by daylight next day it waa found
that no apparent movement of the wires could be got by move-
ment of the eyepiece in or out. This indicated that the elfect wai
due to iUuminafiQn of the field. It was further noted that the
movement was less apparent with a strong illumination than with
a reduced light. It may here be ex [plained that the illumination
of the field is giveu by a gilt annular reflector in the transit axis,
the inclination of which can be varied from a minimum of 45* to
a greater angle with the axis so as to reduce the light.
Afterwards observations of stars were made with the eyepiece
inside the focus^ at the best focus, and outside focus. The resulta
were that the discordance W^ — E waa positive and large ( + t**5)
with the eyepiece far in, and negative (about -0**6 or -o'7) with
the eyepiece far out.
It is to be observed that the mean of the results W and £ ii
wnaibly unaffected by the discordance, aa will be seen from the
laal column.
Jan. 1908* Illuminating the Field in a Trmmi Instmmtni. 183
TremtU €, — An%u^€nf Ulnminatimi ExperimtnU \mth Eifepieee foeui.
By Mr. H. Chnatie.
DiM.
1907.
JdarcLj 19
MftTch 20
Poaitjijii of
Eyepfeoe,
Good ftHSUs
Inaiilt foofut
OatKide frxsus
No, of Stan.
W- E.
2 f 2
It 2
2, 2
W-B.
+ 015
-073
Mis&n,
Clook flow.
-f S9H«
59'66
59 45
Good fociiA 3,2 + 0*58 59*9^
I u side focus 2,2 +i'40 59*91
Outftide footii 3»3 -0*55 59-96
"".-B.— Th« **gooil focus'' po!^it ion wag the ordiimry one for atfti ob^ervi*
ons ; the eyepiece was di9{>lAGcd from thii positbu utiiil obaerv&tion wah
ikly jufit t>c}s«tble.
These experiments eeemed to tdearly establish the coimectiou
between the discordance and eyepiece focus, and they further
suggested that the annular reflector wa^ in fault.
It is to be noted thut the wires at nij^'ht are not seen by their
Awn light, but as dark shadows cutting off the light of the ilium i-
tiated field* and thus the illuminating surface, which ciiete the
ehadow of the wii'e, has an iaiportaut influence on it% appearance
with the annular reflector, Wlien the wire is out of focuB the
shadow of ench point of the wire ia an annulua, and the super-
position of these will give two dark lines parallel to the wire with
A compuratively slight base between, the two sidea of the annulua
being more effective in forming the shadow images than the top
lUid bottom, a« will be seen from the accompanying figure, which
shows the portions* of the annul uh at the sides and at the top and
bottom respectively, which are effective in forming the correspond-
ing shadow images of a vertical wire. Thus two fairly clear and
•eparated images are formed one on each eide of the true position
of the wire,^ Now if one side of the annulns is more distinctly
• On examination of the wires by dnyli^jht ilhiminatioa from the object -
frlawt ^t ^*s fonnd that when the eyepiece was out of focuH, iivHle&d ot t^Q
iniffa a single imit^ was neen, with bntids on each side.
Sir W, H. M. and Mt\ H. A. H. Chridu, lxvul 3»
lighted than the other, and the whole illumination of the field is
not very bright, the eye will lose one of the two images of the
wire, and only see a single image, which will appear fairly clear, and
wiil he displaced by an amount depending on the diameter of the
on t-of- focus annular ring.
On investigation this proved to be the case. When the annular
reflector was at an angle of 45° to the axis (giviog a maximum
of illumination) it was fairly evenly illuminated, but when the
inclination was increased, in order to reduce the light to a
convenient amount for star - observing, one side of the gilt rv-
tlector became considerably brighter than the other. This
was the actual position always ufied in practice, as the full
illumination was too strong for observing stars. Also, it was
found that tlie side of the retlector which gave most light wa»
the one which would, by the above theory, cause the clock
error micr. W to be greater than the clock error raicr. E, as the
fetar-observations showed to be the case. In order further to test
this, Mr H. Christie made observations on April 5, 6, and 10
with the rertector kept at 45' to the axis (a rheostat licing us^pd to
reduce the light from the electric lamp), and obtainetl better
results*
It had long been felt that illuminatioD by means of an annular
reflector in the transit axis was not satisfactoryj as the image
formed at the eye- ring from the illumination of the field was an
annulus outside the circle formed by a star, and there was risk of
ihe eyt^ failing to receive the wkulw of tlie rays on both sides
coming from the reflector.
Illumination by rays coming centrally within the cone of ray»
from tlie object-glass would l)e preferable in this respect, but there
are objections to the way in which tins has usually been carried
out* In rSyo, Sir G, B. Airy succesB fully apphed central illumina-
tion to the Water Telescope which he planneil^ mounting a piece
of iookitig-gla.ss at an angle of 45' in front of the object-gla^s to
receive the light from a gas fiaiae, without any condensing lena.
In this way the Hght was well diflbsed over the field, the gas
flame as well as the mirror being well out of focus at the plane of
the wires.
But in other forms which have been used since, a condensing
lens with a small electric lamp in it« focus has been introduced,
which, in combination with a small reflecting prism or other
specular reflector fixed in front of the object-glass, forms a magni-
fiod image of the source of light in the plane of the wires, exaggerat-
ing its defects, and making it difficult to get tolerable uoifonnity
of illumination of the field and sharp definition of the wires.
In planning the New Altadmuth, a sketch arrangement WM
propoaed in 1S96 January for central illumination by light reflected
from the axis lamp inside the telescope tube to a matt Hurface
gilt reflector attached centrally to the inside surface of the object-
glass ; butj owing to practical difticulties, this plan was not carried
out, and the ordinary annuViT retlector in the axis was at first
JaiL 1908. Illuminating the Field in a TraiisU hidrurmtit. iSj
used. In 1897 September ceiitr4 illumioations by the usual method
of small reflecting prmm (J-irich square) cemented on the outside of
the object'glaas and culliuiatiug lens with a small electric lamp in
its focus was arranged for, and was subsequently brou^^ht into use.
There wasj difficulty^ however, with the illunjiuation, owing to the
tUaintmts of the lamp forniiiig an enlarged iniage in the focus, and
the wires were badly defined, owing, as afterwards appeared, to
diflfraction effectn from the small aperture of the iUum mating
pencil Further, with such a «maU pencil, dust on the field lens
of the eyepiece would be iseusibly in focus with the wires.
Attention being again called to the question* it seemed that
t^X> much importance bad been given to simply getting enough
light witliout sutlicient consideration of the optical conditions
required in the arrangement for central illumination of the held.
Tlieee conditions are :■ —
(1) That a unifomi ilhimination shall be i^ecured over the
field, without such defects as are due to the source of
light coming to a focus near the plane of the wires.
(2) That the illuminating pencil should have a surticient
aperture to minimij?e diflTraction effects on the wires,
giving rise to shadow-bands.
The condition (i) can be secured by substituting a matt surface,
such as. opal glass (finely ground) or plaster of Paris, for the
Bcular reHector, the condensing lens with electric iamp in its
focus being retained. The parallel rays which fall on the matt
surface from each point uf the source of light in the focus of the
coiideiiaing leas are scattered uniformly in directions slightly
inclined to the axis of the telescope, and after passing through the
bjectnglasa, converge respectively to each point of the field, mi that
ch point is illuminated by a pencil iiuiformly distributed over
the whole of the opal re dec ttng surface.
As regards condition (2), it is to be borne iu mind that in
transit ob^rvations sharp definition of the wires is as important as
sharp definition of stars ; and that, as the wires are see 1 as shadows
ihrown by the illuminated tield, the aperture of the illuminating
pencil determines the sharpness of the wires. With the small
pencils which hav^e coninuitdy boflu used even on large instruments,
there are necessarily large difiFracti(m effects which are serious with
the relativply very high powers employed. At the same time it is to
bi? noted that comparatively little loss of light, and practically no
load of definition for a star, is entailed by cutting out a circle of, say,
ooe-fourth of the aperture at the centre of the object-glass.*
After some preliminary experiments with central ilhunination
for the portable transit, the following arrangement was adopted on
1907 May 8 to secure the two conditions stated above. An
elliptical finely ground opal glass was useil a** the reflector, and
mounteil in a brass tube which was attached to the outer surface of
the object-glass by shellac. The illuminating source wag a BmaU
* The loss ot light would in thiu ai89 only be one-aixt«entK
iS6
Sir W, H, M, and Mr, H. A. K ChriMie, LXTin. 3»
electric lamp in the focus of a condensing lens, throwing a parallel
beam of light on the opal reHector. The brightnees of the
electric lamp wa8 controlled by a rheostat, and a very satisfactory
illumination of the fi*'ld, with the wires sharply defined, Wi^M
obtained. The diameter of the pennil of rays from the refleetol^H
wa« J-inch, which was adopted as suitable ft>r the 3 -inch object-glata. '
The results given for Transit C, in Table IX. — central illumination
— ^were all obtained with this arrangement. It was found, however,
that the shellac was nofc w secure fastening for snob an instrument
as a portable transit, as any jar was apt to dislodge the arrangpraent,
HO a more secure form of support was adopted later on, Rnd applied
first to transit B in July 1907. This consisted of an opal retiector
as before, fixed to the dew t-ap by three pieces of watch-spring, and
IB s-hown in Plate 7. This arrangement was found satisfactory,
and so was attached to the other inatrumenta (transits B and D)
«a well No triiuble has been caused hy diffraction etfecta. The
observations obtained are, on the whole, satisfactory, although two
nights (September 10 and 11) with transit B give discordances
W — E of over o"" i . There was prohably some other cause at work
on theHe nights, as the collimatiou determined from the nadir gave
a sudden jump of about 2* in the Ofypodte direction to the error
shown by the stars (Tables VI., IX-, ami X.)<
As the application of the imjiroved central illumination to the
small transits proved so successful, it wa« applied to the New
Altazimuth on 1907 June 5, the mode of attaching the reflector to
the object-glass beinjr slightly modified from the original plan with
shellac cement. In order to secure a firmer attachment, a plain glass
plate, worked slightly concave on the outside to fit the curvature
of the outer surface of the object-glass, was burnished into the end
of the tube carrying the opal reflector, and cemented on to
object-gla^s with Canada balsam. In thia w*ay the obstruction
light due to the attachment is reduced to a minimum, viz. the
thickness of the brass tube. The general arrangement is shown in
Plate 8. The aperture of the illuminating pencil adopted for the
3-inch object-glass was i| inches, which was found to give greatly
improved definition of the wires, which had been very nnsatis-
factoty with the |-inch pencil formerly in use. At the same time
the troublesome marking:^ previously seen in the ilhiminated field
were got rid of, and a satisfactory uniform illumination sub-
stituted.
It is proposed to apply a similar method of illumination to the
Greenwich transit-circle as soon aa the necessary electrical coo-
nftctiona can be made.
The tables show the diflference between the mean clock error
determined with the instrument micrometer West and micrometer
East respectively. They are corrected for clock rate and reduced
with a collimation error determined from nadir observations only.
The weights given depend on the number of reversals of the instru-
ment, a weight of i corresponding to a single reversal, while a
weight of 2 corresponds to two ot moi^.
end^i
m {0 u
ncES OF R.A.S,
Vol LXVm Plate S.
Altazimuth- Illumination of Field.
OPAL GLASS
jj..^ MATT SURFACE
PLAm GLASS--* tl
LCNGITUDtNAL SeCTION.
L
VERSE SeCT»ON
^1
Tun. 1908. lUurninaiin^ the Fiddin a TraamZ LiMruvufU.
^1
■ Tablr I. Table IL
^1
^^1
H^ ^nniitor IHumination.
^^H
BK- W— E* Obifcrver,
Date. VV-E. No. of Start. \
^^1
J'iM as +0**16 H
■
Not. 23 +o*37 7, 7
^^1
'«'r a +0*26 H
D0C. 2 +o"40 4, 5
^^1
8 +0M4 H
4 -o'o2 4, 5
^^1
16 +0*2$ H
10 +o'2o 7, 6
^^1
^- 2 +0*39 H
10 +o'2S 4» 5
^^H
g» 3 +0^30 H -
16 +034 6. 5
^^1
P ai" +0-S2 H
16 +o'4J S» 4
^^1
23* +0*69 H
1909.
^^H
23 +0*1 6 fl
Jan. 25 +0-32 5. 5
^^1
23 +o'i9 D
28 +0*38 4, 6
^^1
26 -1 o*3S H
Feb. 10 +o'49 5, 5
^H
^ 26 +0*37 D
II +o-oS 6, 6
" Maan + 0*340
Moan + 0*293
Ou Dec. 10 the powtion of
illuiuinatitig lump was alti^red
purposely niiide un symmetrica
appftreiitly had ai raugt^inent.
^U Sept. 20 tbe object' glass was
^U otit, e»imitie<3, and replacedp
Hamsdeti eyepUc« with priam
i^^ for tkeae obaorTations tnstaad
^iagoDitl eyepieei}.
1 Table IIL
^^1
H Ttaimt S, -^Ohstrvtr, Mr, Dyson^
^^H
AnniUar Ilhimination,
^^^1
^tfc W-K. Ka of Stan. Wt.
D»te. W-E, Niv, of Start.
1903. !L]e&ni. W. E.
Greenwich.
^^H
f|r. ts -0143 6, s I
Apr. 6 -0-036 5, 5
^^^1
1 (9 -0065 19, 12 2
8 +0*046 14, J 5
^^^H
23 +0*002 11. 17 2
10 -h 0-137 10, 8
^^^1
25 +o'i40 12, 19 2
12 +0*066 n, 9
^^^H
28 ' 0*047 t^i »3 1
13 +0107 18, 21
17 -0*005 J^» J^
r8 +0*076 j8, 18
^^^H
^^^H
^^^H
Mean - 0*005
20 +0-034 7, 8
^^^H
22 +0*030 15, 16
^^^H
23 4-o'ioS 22, 21
^^^^1
24 +0134 «t, 18
^^^H
Mean +o*o66
l88 . Sir W. H. M. and Mr. H. A. H. Chridie, .Lxvra. 3,
Table llL'-ixmiinued,
.
Date.
1903.
W-K.
Heani.
No. of sun.
W. B.
Wt.
Data.
1902.
W— B.
Meana.
No. of Stan
W. B.
^V^t,-
Paris.
Palis.
Apr. 28
+0*088
13, 20
2
Oct
6
+ 0-068
10,
7
K
May I
+ 0-059
20, 17
2
7
+ 0'I27
12.
16
2»
3
+ 0*024
18. 17
2
8
+ 0-029
6.
10
X
Mean
+ 0-057
9
10
-o-oo6
+ 0-047
9.
17,
9
17
13
+0-113
12,
7
s
14
+0*080
20,
20
^
16
+ 0-076
15,
17
2
17
+0*073
21,
19
2
21
+0*051
19,
15
^
Greenwich
Sept. 21
8
+ 0-015
3, 2
I
22
Mean
+0-024
16.
15
2
+ 0-064
22
+ 0-099
18, 19
2
Greenwich
23
-0-004
«. 5
I
Oct.
26
+ 0-149
9,
2
X
24
+ 0-158
19. 18
2
27
+ 0-212
II,
II
X
25
+ 0-087
8, 10
I
29
+0-048
18,
19
2
26
+ 0-127
17, 16
2
Nov
30
I
+ 0-005
+ 0*107
21,
9.
10
8
X
Mean
+ 0-096
X
2
+ 0*040
%
8
1
3
+0-1 14
6,
9
1
4
Mean
+ 0-IOI
24,
23
2
+ 0-093
Table IV.
Transit Z». — Observations by Mr, Storey and Mr. WUchtU,
Annular Ilium ination.
Date.
1906.
\V— E.
Means.
No. of Stars
NV. E.
Obsr.
Date.
1906.
W-E.
Means.
No. of Stan
W. E.
OtP^'
an. 22
s
+ 0-07
6,
6
J. S.
Jan. 30
8
+ 0-15
4>
J S>
23
+ 0-06
4,
2
W.
Feb. 3
+ 0-03
4,
J.S-
24
+ 0-13
7,
6
J. S.
April 4
+ 0-04
4,
j.s.
26
+ 0-09
7,
6
J. s.
9
+ 0-17
4,
v^.
29
+ 0-15
4,
4
w.
19
Mean
+ 0-12
+ 0-IOI
5,
w.
1908. Illumitiating the Field in a Transit Instnimtnl, 189
>u some other nights individual stars are verj discordant ;
le case there ib a range of one second of time.
Table V. Table VI.
Tramit B^-^Obseivcr, Mr, R, ChrutU.
Annular Uluminatwn,
Central lUumifuUioiU
:
Ko.ol8Un. Wt.
Date.
1907.
W-E.
Me&ni.
No. of 8Urt.
Wt,
16
40*081
2»
6 t
July 30
40*053
3.
4
t
iS
40-369
4»
S ^
Sept 7
40-091
7.
8
2
ao
40*868
5.
9
40*089
8,
8
2
n
40480
3i
10*
40109
8,
7
2
u
40-584
7,
n*
40IJI
1*
7
2
n
40-972
15*
15
-0*030
4.
4
t
3«
40-368
S,
19
40-038
5.
6
2
7
40703
7i
24
-0-023
9.
12
2
10
40-093
3»
25
-0052
7,
7
2
«S
40744
S*
26
-0*034
15,
»S
2
38
40 521
4 1 "057
40409
4»
2,
2 t
9 I
2 I
Oct. 4
Mean
40*004
8,
8
2
9
n
40*036
27
+ 0725
40 '088
40455
40558
2,
2,
4.
3 I
3 *
3 I
Obaenwr, Captain Monro, ilf,A
Sept. 16 40^042 4, 3
17 -0*052 6, 6
1
2
■fec^— The obterratioas in Table VL (Central Illumination) were aU
^oed with the Aame coUimatiou error thioughout ; there appears t« bare
^ a alow change of colliniatioD, wliich waa alao shown hy th» nadir
^TTattODs. No correction haa been apfiHed for inequality of the pivots,
* in^D of u number of determinations made by the striding level in
||k when the pivots were hibt reground^ wa5o''-oo.
On September 10 and 11 the nadir re&dinge for colliraation are very dis-
^^Ant, dirfering by about i" from the Tuean. The clock stars appear to be
1 alao, but with the opposite sign.
190 Sir W. H. M. and Mr. E. A. B. Chridie, LXvni. 3,
Table VII.
Transit C.
—Observer, Mr, Hollis.
Anm
liar Illuminaliotu
Date.
1932.
W-E.
Menus.
No. of Start
W. B.
Wt.
Date.
W-E.
Meani.
No. of sun.
W. B.
y^r\
Greenwich
8
Parii
.
■
M&r. 17
+ 0*128
15.
12
2
Sept
21
+ 0-204
15.
II
2
19
+ o-io6
17,
17
2
22
+ 0*I20
i6,
16
^
20
+0056
10,
12
I
24
+ 0I2I
17,
14
^
21
+ 0-086
+ 0-066
+ 0'II1
10,
14.
7
II
8
I
I
I
26
Mean
+ 0*118
16.
18
a
22
23
+ 0*141
25
+ 0-260
16,
18
2
Greenwich
27
+ 0*416
13.
10
1
Sept.
29
+0*133
14,
H
a
28
+ 0-070
14,
5
2
Ckt
2
8
+0*032
+0-079
16.
20.
16
19
2
Mean
-5-0143
2
9
+0*077
10,
7
I
Paris.
10
-0*019
19,
20
2
Apr. 7
-^ 0*303
10,
8
1
12
+0*057
12.
8
I
8
+ 0-316
9,
2
'
14
+0005
19.
20
2
9
+ 0-067
10,
15
'
15
+0*087
14,
10
X
II
+ 0-095
9,
11
I
16
+0*081
20.
18
2
13
+0-267
16,
iS
2
17
+0*033
16.
17
^
17
+ 0*217
17,
16
2
18
+0-138
17,
14
^
18
+ 0*22I
17.
16
2
21
+ ox>4i
20,
20
j^
20
+ 0-162
iS,
II
2
22
+0-199
15,
iS
^^
21
23
+ OI66
+ 0-260
16,
9,
16
15
2
I
Mean
+0*072
24
+0*137
17,
19
2
Paris
.
Mean
+0*199
Oct.
25
27
-oxx)3
+0*058
14,
10,
13
8
^
Greenwich
28
+ 0*061
7,
'3
^
Apr. 27
+ 0*052
9,
14
1
29
+ 0*158
16,
17
j^
28
+ o-o6o
IS.
17
2
31
+0*172
16.
17
^
.May I
+ 0-064
16,
12
2
Nov.
2
+ 0*157
17.
II
:;r
2
+ 0-070
10.
14
I
3
+ 0*187
20,
17
-^
3
+ 0-007
17,
17
2
4
Mean
+0*234
+ 0*138
20,
19
-^
Mean
+ 0*048
h
, Ulumhmiing the Field in a Tmnsit Instrument. 1 9 1
ABLK VIIL Table IX.
TmmU C— Observer, Mr, H, Christie,
* Illumination t
Central lUnminatimt.
Ko. of Stan,
W. E.
wt.
7.
7
I
a.
7
I
6.
4
t
M,
8
2
3.
3
I
4,
5
t
u,
10
2
3,
3
I
9
t
7
2
3
I
6
t
J7i
i3
2
»5»
»7
2
S
2
2
t
S
2
6
2
5
I
May 8
10
27
June 2
ro"
17
19
July 16
17
W-E.
- 0'029
+ 0'04I
-0'023
-O'OOl
-0*045
+0046
+ 0'047
+ 0-055
No, (it Surt. Wt.
W E.
16, 15
I. 6
7. 5
12, It
n, 5
15. 14
7» 7
2* 2
Mean +0*003
* Obftervwr, Mr. Hollli.
l^Ko correction for inequality of tlie jnvotfl has been applied. The
t" ' jrrainationB of the apparent inequality hcive been made with th«
DlW.
AS^?^l IWieordjMico W-E
s
1^ The
1902
March-May
+ 005
+0-0I6
1902
Sflpt. -Nor,
-0*09
-0*029
1906
Nov, ^Dec*
-0*09
-0*022
1907
Jan. -March
-0-I2
- 0*029
1907
April -June
-0*07
-0*017
The pivots b»r» not been re^grotihd aitice 1901,
-:?—
Table X.
Transit D.
— Ccn/f (»; /Z^umijwtii^m,
OhteroeTj Captuin
M(mro, E,N,
O&wrwr, Zvwi.
Gtbmm, M.N', |
D&te.
1907.
Ko, ofsun.
wt
Date.
1907*
No. of St«n.
i?ri>^
Sept 18
A
-o'i37
3i
3
I
Sept, 27
•
-0 149
3>
3
I
19
+ o'o{>5
8,
10
2
Oct 2
+ 0'0I9
7.
7
2 1
23
+ 0*030
10|
8
4
+ 0*096
8i
8
2
24
+0009
12»
10
7
-0089
6p
4
H
30
+ 0008
-o'oi4
5,
8,
8
6
S
Meat]
-0*020
5.
8
i
1
Oct. 2
-0-006
4
+ o'i50
9»
9
7
-0"052
8,
6
s
t '
+ 0*021
8.
8
1
i
Mean
+ o'oao
Ofl «/ie 0?-6i^ of the Binaru Star P 80.
By T. J. J, See, A.M., PkD (BeroL).
This mtercistiiig and raiJidly revolving syatem was discovered by
Burnliam with his celebrated 64nch telescope at Chicago in 1874.
It was measured by Dembowski the following year, and has since
been followed regularly by the most active observers of close paita.
At first the motion was very slight, bacanae the companioD was
near apastron, with a long radius vector and revolving slowly,
But in the last ten years the motion has become very ra^nd both
in angle and distance. The apparent orbit quite well represents
the observations, as shown by the accompanying diagram. The
material used is the complete measures given by Bun* ham in his
General Catalogue of Double Stars, just publish»^d by the Carnegie
Inntitution. The place of /?8o for the epoch ol 1880 ia a = 23^
12"^ 45'; 8 = + 4 45'; mags. 8-2, 91.
The elements are as follows ; —
P = 63*5 years a = loy'-S
T= 1905^30 4= i7*'6
e^o'726 X= io"7
a^o'"626
h%^^ I9o8« . Orbit of the Biimry Star /8 So. igfj
^ppareot orbit : —
Length of major axis ^ i"*25
Length of minor axis =o"*79
Angle of majoT axis — uj"-^
Angle of periastrofi = i ly'^S
Distance of star from centre ^o"*45a
^o previous orbit for this star has been worked out. Some
astronomers have expressed the opinion that the period could not
^ '^ftduced until the companion returned to apparent apastron,
"^' it will be seen that the observations fix the apaatron with
singular accuracy.
1888^5
1892-97
190065
"901-83
'903 '76
•9CH73
Comparuan 0/ computed itrWt> observed pktctufor & 80.
A. 5-
LM, 1.
iS. 4 ; Lv, 5,
Sp, 3.
Lvp I ; W, 3,
Lewiii, 1,
^, J ; Bow, I ; A, 4.
Bry. 4.
Doo, 2 ; A, 2.
Brj , 4 ; Don, 2.
Br\% I ; Lewis, I.
A, 2 ; Brj, 2.
A, 2.
A, 2.
A»2.
300-4
300-9
-0^5
ro7
1*07
0*00
306- 1
302^4
+ 37
r24
I -07
+ 0*17
^l2'l
308-6
+ 3-6
0-91
1*02
-on
3161
3167
-06
0-84
0*92
-0"o8
3»9'S
319*8
-0*3
0*88
087
+0*01
3^25
325-5
-3*0
0*69
0*78
-0*09
327-2
329-0
-r8
0*60
074
-o"i4
328*5
330*5
-2*0
0*83
071
+ 0'I2
^tyi
334'4
-9'3
0-63
066
"0-03
340*3
3360
+ 4*3
o'59
0-64
-0*05
346*0
3387
+ 7'3
0-45
0*61
-0*16
i5S-6
3516
+ 7-0
0*42
0*47
-0*05
13-8
12*4
+ r4
0*30
o'33
-003
24*3
29*8
-5-5
0*37
0*26
+011
55 '3
53*4
+ 1-9
0-22
0*21
4-001
916
90*2
-fi'4
0'l6
o-i8
- 0*02
J3^'4
134-8
-1-1^
0*17
0 17
0*00
163*8
172-4
-S*6
o*iS
o"i9
-001
Epkemeris,
19087
209*0
028
19097
222*5
0*33
19107
i33'3
0'39
19II7
241 '3
0-45
19127
247 '2
0*50
19137
252*4
0*56
19147
256-4
o*6o
19157
260 "2
0*65
19167
263-0
0-69
19177
2657
072
19187
268*2
0*76
Dembowski measured the position here laid down on five
^hts in 1875 It happens that hia obaervations both in angle
^^ in distance are perfectly represented by this ellipse whic-k
*^^i«fie« the law of areas, Thus both ends and a fuW s\ie ol
194
On the Orbit of the Biv4i7y Star fi 80. Lxrin. 3,
the apparent ellipse have already been described, and the oht&t*
vations of Aitken in 1905 tmd 1906, beyoud peria^tron, show
that the other side of the ellipse is almost identical with thnt
already described. The elements are thus Bxed with unusual
accuracy. It seems likely that the period is uot uocertaiu by more
than one or two years, and that the eccentricity cannot depart
from the value here given by more than ± coj*
ido*
This orbit illustrates the value of good observations advantage-
ously placed. An ephemeris for the next ten years is added for
the convenience of observers. This system deserves careful
attention for some time, because the motion will be rapid both iu
angle and distance, and observations will be valuable in verifying
the orbit
As Burnham's General Catalogue gires all the measures used,
it suffices to give a calculated comparison with the annual means
as plotted in the diagram, which embraces all the best material.
U.S. Naval Observatonf^
Mare hland, California^
1907 Dccemhtr 4,
1908. On the Orbit 0/^513 - 48 Cassiopeia',
195
On the Orbit 0/ /9 5 1 3 = 48 Cmdope%(B.
Bj T. J. J. See, A.M., Ph,I). (Berol).
Thm remarkable binary was discovered by Buriihuia with the
iSJ-inch refractor at Chicago in 1S78, Its place for the epoch
1 880 is a=^ T*" 52™ 7*; 3= +70* 19'; and the miigiiitudes of the
Bomponeats are 5*0 and 7*0. The star is always cloaej and presents
the same dfficulty in dividing the components as the systems 99
Uercolisy 85 Pegasi, and t Cygni, which can be well separated only
by powerful inatraments in good seeing. The inef*fiiire« of such
anequal pairs are often vitiated by sensible Hystematic errors, so
;bat the computer encounters difficulty in reconciling the observa-
tions to any orbit.
The orbit herewith presented gives the general character of
ihe motion with essential accuracy, and will be useful to observers
br the next ten or tlftaen years, while the companion is again
■eceding towards apastron.
The two ends and one side of the apparent ellipse have been
leecribed. The principle of areas shows that the orbit has a ratber
imall eccentricity, and that it is not highly inclined. I am indebted
o Ptofefisor Eric Doohttle, of the Flower Observatory of tlie Uni-
rersity of Pennsylvania, for tbe last measure, which falls exactly
\n the orbit here laid down. His note on the measure was, " 1 am
lOrtain this is real ; a perfect night."
CompariBon of computed tcith observed places for ^513,
I
187870
1879*40
1881^7
18SJ78
188577
188603
188870
1889-52
1890-62
1891 "^t
189299
1893*47
1896-09
1898*92
189972
190076
19134*00
1906*32
264-5
265-0
271*9
269*7
284*9
270*1
2981
304*4
308*6
3'3*S
3«7*2
322*2
333*7
ir6
^9 3
652
97H
265*1
267*2
273*6
280*2
286*6
2876
297*4
300*9
305 *«
310*6
316*4
321*2
340-2
16*3
28*2
673
9S'5
«<,-<•.
- 0-6
- 2*2
- 17
-ro'5
17
-17*5
-K 07
3*5
2-S
2*9
0*8
1*0
6*5
1*4
47
2*1
1*9
Po-f*r ObiflSTor, Nl^htt,
1*05
o*9S
076
1*07
i'03
083
0-76
0*55
0*58
o'S±
0-65
o-5±
0*36
0*42
0*38
0-40
o*37
0'82
082
O'Si
079
076
075
0*70
0*67
o 64
0*62
0*58
0-56
0*48
0'42
o'4i
0*40
0"40
039
+ 0*23
+0*13
-0*05
+0-28
+ 0*28
+ 0*13
-{-0*09
-0*09
-004
-o'o8
+ 0-09
+ 0*02
-o*o6
4-0*01
-0*02
±0*00
-0*02
1907*93 ir8'8 115-9 4- 2^ <o'4 o'39 ^-o-ox
A, I ; ^, 3.
02, 1 ; 3» 2,
^, u
En., 5.
H2, I.
T,. 4-
0,4-
iS, 3
^,4-
3.4.
Sp., I.
Sp., I.
A., 3.
A., 3-2.
A., I.
A,» 2.
A., 2.
H
196
Dr. T, J. J. See, On the
LXVHL -:
[1908. Orbit q/'j8 513 = 48 Camopeue,
197
EphemerU,
^^■p
124-3
0-38
! 914*60
193 '4
o'47
p^&
1171
0-38
1915-60
201 "2
0*50
■910*^
150-5
039
i9i6'6o
208-2
0*54
■9^*60
1650
0'40
1917-60
2t4'2
o"57
K9i2'6o
174*4
042
1918-60
219-8
0*60
nu'^
184-3
o'44
tU the observations are ^iven in Burnham's General Catalogys
huhle Stars recently published by the Camegie luafcitution.
•ufficieut, therefore, to add a comparison of the compnted with
observed places upon which the apparent orbit was based.
lie elements of /? 5 13 are as follows : —
P = 52 '95 years
T - 1905 60
a = 8r-4
^ = o;347
K = 6''2
a = 0 '610
Lppareot orbit : —
Length of major axi!
1 Length of minor axi
H Angle of iDajor axis
^m Angle of periastron
^m Distance of star fron
1 centre
= r'-2i4
= o"'963
= 84;7
= 86" '7
= o''2I,
por several years to come ^8513 will deserve careful attention
I observers with powerful telescopes. The motion will be
id for some ten years, after which the syetein will widen out,
" Rt observation will he much easier than at present*
V.S. Naval Obscrtatory,
1907 Dtccmber 10.
1 98
Dr, T. J, J, See, On tfU
On the Orbit of p^^i ^ ii Orianis,
By T. J. J. See, A,M., Ph.D. (Berol).
This interesting binary was discovered \\j Burn ham with the
i8J-inch refractor at Chicago in 1877, but it had been pr^Tiooalj
suapected with the 6-inch in 1874 as ** possibly a close pair.** The
place for the epoch 1S80 is a-j^^ 45"* 4*; 5= +13* 27'; and
the magnitudes are 7*0 and io*o. It is therefore an exceedingly
difficult objecti and can be well seen only in the most powerful
telescopes, under good conditions. On two favourable nights in
T892 Burnham coulii not see it with the 36-mch refractor of th&
Lick Observatory. Profeaeor Hermann Struve, with the 30-inch
refractor at Pulkowa, had auep^cted felie companion on the opposite
side in 1886^ when the distance was only o""2i ; hut as his angk
corresponds to the true place at the time, I have reversed it, on
the supposition that the point of the diffraction fringe noted wa«
produced by the companion, which was then too close for separa-
tion, but might easily produce an opposite image resembling a
real companion.
This system is highly inclined upon our visual ray. The com-
ponents being so unequal, the observations are somewhat discor-
dant. After a careful study of the movement, I have deduced the
following eiementu :- —
P ^ 56*0 years
T - 1887-0
e - 0-345
a = o'''528
Apparent orbit ; —
Length of major axis
Length of minor axis
Angle of major axis
Angle of periaatron
Distance of star from centre
a = 4'i
i = 56^*7
A = 9o*'2
= o"-59
= \^
= 94'"4
=■ o 'lO
Comparison of computed with observed placee for
^553 = 1 1 Orionis.
1874 '95 340*i 34^*6 - 8 '6 o's± 0-51
1877-97 36o^i 3S9*S + 0*5 o'8± 0-49
1886-19 85-0! 74-5 +10-5 o*5i o-ai
i889'»9 1447 141-3 + ri o*35± 0*25
1890*96 1567 161-4 - 47 0*33 0-34
1891*13 153*8 162-8 - 9'o 0*33 o'34
j8^'o6
169-3
0*38
-o-oii: 0.
+ 0*31 i 3. ».
+ o*29± H 2» I
+ o*ioi Sp., I.
-001 3,3,
-o-oi Sp,. 8.
Ob«enr«r, Nigbts.
angle 18 hers 1
36-iiicl
Dpareatly
Jan. 1908.
OrbU
0/fi
552 =
: u Orimm, 199
^
*e
•«-^e
Arl
fc
p.i-p^
0)>terver, Nl«liti.
•«7
J<i5'3
»75*S
- tO*'3
0'35:fc
0-42
-0*07
Sp., I.
•IS
1782
1811
- 2-9
0-38
o*4S
-007
Sp.» 2.
*8S
177-0
1843
' 7'3
0*40
o*47
-0*07
Bax., 3.
•II
179*9
188*8
- 8-9
o'35
0-49
-012
8p..7.
86
187*0
192*1
' 5*2
0*42
0*50
-008
Hu., i; A,,3'
^3
<93'5
194-9
' '4
037
0*50
-o-is
Si>., A.» 5; Hu., 3.
hoi
189*9
>97 7
- 7*8
045
0*50
-0*05
L«wi«t 2«
>'43
1981
197-8
+ OH
044
051
-0*07
A., 6.
176
ao2-5
303*0
-f 0-5
o*45
051
-0*06
See, I ; A,, 4,
r-8s
2073
302 '8
■^ rs
042
051
-0*09
Lewi«, 3,
r?!
»4"3
2059
" 1-6
0*45
o'5i
-o'o6
A . 3 ; 1>oOm 3*
t-85
»H*6
2tO'I
- 5'5
0*49
o'so
-o*oi
A., 3 ; Doo,, 3.
»74
M9'3
3|2'6
+ 167
032
0*50
-o'i8
0» I*
166
3t8*9
316 8
+ 2'I
0*46
0-49
-0*03
A., 4 ; Bieebfoock, 3.
1-90
227-9
225-9
-f 2^0
0-46
0*46
io'oo
A, 2.
"93
2587
235 »
+ 3-^
OSS
o'44
+ 0'|I
Doo., 3,
EphemerU,
1907*0
1908*0
1909*0
1910^
1911*0
191210
230*9
2355
340's
245*6
350*6
256*3
0*45
0*44
o*43
0*42
o'4i
0*40
1913-0
1914*0
1915*0
1916*0
1917-0
1918*0
262-3
268*4
274 '5
2806
286*5
292*4
0'39
0^39
039
039
0-39
0*40
The accompanying table shows the companaou of the computed
with the observed places. Considering the discordance of the
meafiuren, the repreaantation in angle is good. The di stances
oould be slightly improved by reducing the major axia ; but as
the scale of distaooe is still somewhat uncertain, I have not
thnnght it worth while to do this. It t^eema certavn that theee
elements give the essential character of the motion, which is
readered very peculiar by the high inclination, k'iving a nearly
stationary phase at each end of the apparent orbit. The orbit of
^552 has some resemblance to that of y Coron® Horealis, the
componentB of which are correspondingly unequal and difficult
Ui measure.
It is clear that the periastron was swept over about 1887*0,
and ihut the period is about fifty-six years. The eceentiidt^ TCiay
be higher than thai givetj here, but an increase in ttiVa e\^mfeTkl
20O
On the Orbit of ft $$2 = II Orionis. LXl
would hardly be warranted by the existing observations.
ephemeriB will be useful to observers, and it is to be hopec
160*
7905-9
270*
/57#
y3552
0-
they will continue to follow this interesting object for a n
of years, till the orbit can be adequately confirmed.
l\S. Xavtil Obsfrvaton/,
Mare Inhn^f^ Cdlifomitij
1907 Dn-embtr 12.
'
JatL 1908. CamparcUive Eccentricities of Binary Stars. 201
Ao^« on the Cmnparative Eccentricities of Vlmal ami Spectroscopic
Binary Stars. By T. J. J, See, A.M., Ph.D. (Beral).
Fur some tlmd the writer has heen occupied with a critical
MCftmiimtiua of the comparative eccentricities of visual and spectro-
Aoofjic binary stars, in the hope of obtaining an observational
criterion that will throw light on the evolution of these systems,
it is Qow clear that the investigation will afford the criterion
soiaght; and as he receBtly had occasion to mention the general
re«milt in letters to some friends abroad, it seenia likely that a
px'^liminary notice of this work may be of interest to the Society,
If we exclude from consideration all binaries telescopically
's^^jlvable in modern instruments, there remain ubout 30 orbits of
P'^^r^ly spectroscopic binaries, which iiave been worked out from
*P*^ctrograms taken chiedy at the Lick, Yerkes, and Potsdam
^ tMBdrvutories. The eccentricity is well determined, and the average
'^^^Ime for these 30 systems ia about 0^22, In the case of very
f^-I^id binaries, with periods often much less tban a day, the orbits
^^ practically circular Dr. A. W, Roberts and Professor G. W.
T^^^ers have investigated the light changes of certain variables^ and
^'^^^WQ that they are composed of two stars in the process of
^^ J^^fation, and therefore revolving in orbits which are without
®p«i«il>le eccentricity.
The average eccentricity of visual binary stars remains about
®* S <J, as indicated in the work RemarcJms on ike Evolutmi of ike
^^^^/flfr St/stentSf vol. i., pul>lislied in 1896. The subject has,
"^fever, been sa much extended and improved during the past
•^en years that it has seemed advisable to re-examine each orbit
y^_^#. There are about 80 orbits in which the eccentricity may be
^*^*^ly well determined. I hope to have the tinal result of this
!^^inination ready for presentation to the Society in a short time.
.**^ work is already so far advanced that we may confidently
T^Ue that ike average ecceiitrinty ajnong msual bttmrieii is cmi-
J^^^rnhhj tfujre than twice that ajnoufj the spectroscopic Hnaries.
^^mi latter are stellar systems, with componentiS so close together,
^^^"iiig to the small size of their orbits, or so far removed from us in
^^ce, that we cannot resolve them even in the greatest of modern
^
^ssoopes. In some cases they are closer sub-systems of known
tml binary stars. Among such systems we may mention i Ursae
"'^^^ofis* *c Pegasi, a Gemiiioruni, etc,» whi^^h are s[>ectro8copically
f^'^^divided in exact analogy to the many double stars which have
^*=sn resolved into triple stars by increase of modern telescopic
r^^i^er; but where the spectrostopic binaries stand alone, we can
i^ r^r ^be averse size of their orbits only from the generalised form
^^ Xepler's law,
. For a large number of systems we are justified in assuming that
^^ ivcrnge mass will be the same among the spectroscopic as
^*^*^ong the visual binary stars. And as the periods oi l\ie a^^cUo-
»<^OH>ic binaries are much shortei thsin those of the visvial binatv^a/vi
202 Eev, 1\ K Espin, Micrometriml MBosures of
follows also that their mean tliatances «ire correapondirigly I
This concluBion might imleed fail here and there in par tic uL
butf as applied generally to these two dajsaes of bodies, ia e&tl
valid.
Accordingly, we see that iu the uniTerse generally ai
eccentricity is connected with the smaU mean distance, and <
versa. This confirius^ from an observational standpoint^ the thi
of the development of these systems long ago inferred from d
considerations {ef. the writer's Inaugural Di»»ertatio7i, Berlin, iS
Heretofore j^carcely anyone has dared to hope that a direct col
matioQ of this theory would ever be poaatble; but, unless I
reasoning is entirely at fault, such a positive confirmation is nei
hand, and is due to the notable advance in our knowledge of
stars arising from the discovery and investigation of spectroM
binaries, chiefly during the past ten years. '
U.S. Naval ObKrvatory,
Mare Ulawi^ California :
1907 November 3a
\MicrQnietrical Measures of Double Stars (Fifth Series), By
Rev. T. E, Espin, M.A.
In the early part of 1907 very few known double stars
measured, pending the arrival of Burnham's General Catall
The latter part of the year has been devoted to the completi/
measures of new pairs, and to the measurement of such star* 1
John HerscheFg as have not been remeasured since his ohservati
them. The places are those of the General Catalogue {1880I
in several cases, as explained in the notes, corr^ections to Hd|
places have been made.
1009
ti m
0 9*6
880. Ded.
+ 47 5^
267
16*77
9'o, 9*1
NIgliti,
2 1907
140*9
3615
117
2
1029
25 9
44 16
279*9
11-85
8*8,
tO*4
3
198s
28-4
48 11
143'3
1 7 '97
100,
10*2
' i
1049
38*0
50 6
303*1
»5*32
9*2,
iro
3 1
1050
3Si
44 23
185*1
13-97
97,
107
^ 1
1058
51 -0
49 34
2837
1170
IO'2,
103
3 1
1060
52^0
44 16
293 I
948
9 '5.
107
^ 1
3013
59^2
44 8
247*0
23-22
8-5.
11-5
* I
2031
I 9-6
43 49
260*6
20*15
8-5.
J27
' ■
^
34^^
^\h'^
K^
V^
^ ■
^fl
i9o8.
DauUe Stars { Fifth Series).
KM iBSo, D«cl.
h ID
1 107 +44 O
P.
2952
Magi.
%\i, 9"6
Nights. D*t«. ^^1
1907*903 ^^
2 25*0
48 20
259 '4
26 '22
^-^^ 9*5
2
'880 ^H
4 23 4
47 2
325*3
13*42
8-8, lo'S
2
•924 ^H
361
47 36
123-0
I5'90
9*i| ir6
2
^H
39 4
45 58
162*2
13*52
9*5, 10s
2
^H
58-2
47 11
333 •»
14-92
8-8, iro
2
^H
S 1*1
47 21
97 -2
14*20
8*8, 9*4
2
^H
[ 217
47 49
1258
570
8-4» 9 '5
2
^H
1 6 0*2
*
28 s8
257*2
12*27
9*0, 9*0
2
^H
\ V3
31 17
117*3
9*85
70. irs
t
^H
> 8 4S'3
28 43
3337
43*72
7*5, «»'o
2
^H
567
28 4
9*4
1 1 *62
9*2, 11-5
2
^H
9 12^
35 46
135*2
15*81
Il'O, U'O
2
^^1
' 19 7*0
4J 35
«77"5
14*40
8*0v 13*5
I
^H
2IO'9
36*60
12*0
I
^H
53^
46 28
87*2
6-87
9*9i n'o
2
*S35 ^H
55'9
45 29
313*1
10*20
9*S, n*s
3
^H
^ 1*8
49 3
7-2
17-40
10*0, 10- 1
2
*842 BC ^H
88 -o
27-62
A= 97
2
'842 AB ^H
45*6
4738
224*0
375
9'0, lo'o
2
^H
S0*4
47 6
48-6
878
9*o, lo'i
4
^^1
S6t
4843
«35'5
25*67
10*2, II'O
2
'82s ^1
21 245
47 38
230*0
io'95
9 4, 1 01
2
^H
28
47 54
S€e Note
^H
35*«
46 39
135*0
29'22
8 '4. 97
2
^^H
35^
47 52
109-9
7*35
90, 9*1
2
^^1
42-0
46 39
249*6
11*75
lo-s, 11*5
3
^H
44*9
46 43
325*6
7*62
9-i» I2'0
3
^H
46 '9
46 3*
195*3
tl*42
97, 107
2
^H
49'8
46 29
37*6
3*07
J 1-9, 13*5
2
^H
syz
48 8
1767
9*30
9'4» 9*5
3
^1
^^ rs
45 53
178*9
9*57
10*6, ii7
2
^H
.s-s
47 4«
S8-4
1470
9*7, 137
2
^H
■
354*9
i8'35
A= 9*1
2
^1
L
49 4i
26$ '2
JJ*32
9*0, lo-i
2
-%q6 ^^I
204 ^^^* ^' ^* Sspiuy Mici'ometrical Measures of lx
h.
R,A. i8do. Decl.
h m
P,
D.
M««»,
KlgllU
Date.
1772
M 23 5
+ 45 32
103*5
6-05
9'6, 10-2
2
1907 910
1793
33i
46 25
291-5
13*95
iox>, 117
2
*9ia
1794
332
46 22
PS'o
21 -So
9*4t no
2
*9to
1795
33*3
46 43
213-8
12-07
107. 11 '5
2
'910 Bj
209*8
id*io
A== 10-2
2
•9x0 jl!
«797
34*6
49 30
125-4
14-io
97. *«'o
2
■951
1 8 14
44 'I
47 57
76-1
M'lo
9-o» IO'2
2
782
1863
23 I0'4
48 21
Si'i
8-57
11*5, 12-S
3
-813
1S78
21 3
49 46
2682
8-87
10*5. 107
2
•858
1883
21*9
45 44
'45*4
18-55
9'h 9 '6
2
•903
1893
292
46 SO
247 "o
4*47
8-6, 87
3
795
1917
487
45 6
76-2
12 92
8*9, 12-2
2
•935
1923
54'3
50 3
2776
1077
II '5, irs
2
-918
1927
570
44 28
76*6
HIS
8*6, 8-9
2
'95 J
»93«
58*0
49 18
113*1
21-90
.810, 107
2
759
Notm,
h 1009 is BD + 47", 4O1 C not given by h.
h 1029 is BD + 44*, 1 10, h*B pkce one min. too small in R.A, j
h 1985 is BD + 48*,i72.
h 2013 is BD + 44^232, /i*8 angle 256**0.
/i 2249 a Bniall star at P 306*, D 119" is double and is No.
of the li«t of new pairs.
h 2S57 the nearer mmea is not in h.
^1460 22'*2 jf? 43" 7 N of Bl)-f-46"'» 2817.
h 1657 It aajfl ** 10' + 10" ± in a cluster/* I have looked forfcli ^
on several niglits, but have failed to find any each pal ^
The unly pair that beara any resemblance ia one ^
P 16* '3D 101'' from BD + 47'j 3439 (Ailken 77c
which I have measuri-d as follows : —
I' 39'" 7* I> 7**001 maga. 9-5, 10-7, 2 nts, 1907*884,
k 1705 Thia is i3'-6/ 2$ ^ of BI)4-46*, 3480, and if ideutie
with h 1705 //*a place is t min. too great. IL-i
observation is "P 80*^4, D ^k\ mags. 11-12, ^M
difficult." I could not find any other pair here, V
h 1762 Star C not jj:iveu by h,
h 1795 h says, **Hf a 4th star." No such star seen on eltj
night, save a distant brighter one n.p.
h 1863 h reversed an^le and says ** difficult to measure/*
/* 1893 This 18 BD + 46', 4082, and h'% place requires a correction
in Dec!, of 4- 30'. His angle is the mean of 250*16
and 252**6. The star BD -f 46*^ 4083, is in the fieW^
8*" 8 / 7;^" '4$ ^ 'il ^^^ Mv^V^ of '^i''6.
• 11
it™
1
Ja.zi. 1908.
Double Sta/rs (Fifth Series),
205
Various Stan-.
^im^.
R.A, 1B86. D«cL
1) IP
P.
D.
Mag».
NlghU. D»ti.
qCUMsioipei».,,
0 4i7
+ 57 »i
236*4
236 T
5'67
572
2
a
1907-043
•990
£»I>ii»44 ..
49*8
56 SI
250 I
7'40
8*3,
12*0
3
'341
^ Gmmfifi^,..
1 12*5
57 36
264-8
41*54
7-0,
II'O
2
* 107 CD
23ri
132*93
A =
50
2
'107AC
A- G^ (Bonn)...
517
50 I
355*2
13*62
9'o,
91
2
774
A,0,(BoDiiJ ...
3 '7'3
4636
3^50
10-67
8-5,
9 '2
2
'957
^pin 57 -^
4 47'4
47 27
175*9
2 '27
9'5»
9'9
3
^942AB
61^3
16' 52
0^
i4'o
2
•940AC
^ 1316
5 S4'5
30 0
i8ro
4 '68
S-5t
117
3
121
Kui^br4 *
6 I2'8
^9 43
273'2
550
9'o.
9-2
a
•J15
«e«*Dcri ...
7 56-8
28 8
187*5
60 '06
S^o,
12-0
3
•232AB
8ro
78-63
C^
1 1 'O
2
•232 AC
2 ^3ti ...
9 6'4
S3 J3
66-5
iS-82
2
*202AB
2827
28-44
C =
14-0
2
*202AC
^*i*^er 40
11 426
34 22
182*6
3*12
8'9>
9'2
2
'216
»^ Own« .,.
12 16-5
26 31
54-0
3491
4-Si
irs
3
•240AB
167-5
64*66
C =
S-o
2
■235AC
^«-(BQun)..
I« 547
47 2
229*0
2^37
8'3.
8^4
3
-846
^^"«^»32 .,.
ig 56-1
29 36
128-0
3'*7
9 -8*
10*0
3
724
A^«.39(Eipin
ao 387
48 50
II32
9*67
8-2.
8-6
3
778AB
92)
125*1
30*98
C =
la-o
4
7I4BC
232*0
33'47
D =
140
2
•893 BD
^ ^8*.3995
23 ns
4S 16
23 r6
49 10
7'3*
8-8
2
799
^
Notes.
C^assiopeifc CD may be the pair meaauxed by H aa 27 i' "8.
0. Ill, 17*3, l*he note in Bonn Observations **Dupl. 3'' med."
may refer to S 371, 7 min. p.
*^ ^316. Detected and measured before Professor Aitken's results
reached me. He calls the comes 14*2 mag,
^U^ker 4. This is BD + 29', 1 181, 6' N of Riiniker's pkce.
^ Oancri. A star mentioned in "Celestial Objects" as having two
comite» detected by BirmiDgham.
^321. The minute comes was first seen 1901 Jan. 22,
i^ Comte. The nearer cames previously seen by Bumham.
2
ii»]
"^9 32, This ia BD -h 29*, 3849.
g, 39. After charting all the available measures, I find a motion
for B of o'''2i6 towards 22 1°'%, C, measured by Biirnham» is
almost at right angles to tlie line of motion. I have added
the still fainter star D, as being nearly in the dvTeGlioxi ol
tnotioa.
.Jt^
206
Bev. T. E. JBtpin,
ijcyin.3,
New Double Stars,
By
the Rev. T.
E. Espin,
M.A.
No.
B.D.
JLA. 1900. Ded.
p.
D.
MMgi. Nighti. DOe.
I*
h m
e
,
0
n
1907.
443
+ 48,5
0 0-8
+ 49
10
32-9
427
87
9-9
2
740
444
+ 44,126
314
44 57
192-5
2-93
91
9*6
3
-968
445
+ 44,X30
32-6
44 54
3497
332
9-0
ii-o
3
•968
446
+ 49,182
40-2
49
18
256*1
10-12
8-4
9-0
2
•867
447
+ 49,186
411
49 43
2779
5-60
8-5
117
2
-836
448
...
591
50
2
81-3
250
95
97
2
774
449
+ 49.352
I 138
49
58
212*8
11-20
8-5
9-1
3
•876
450
+47,414
217
47 37
1474
9-52
8-0
13-5
2
759 Al
2689
20'10
C =
13-0
2
759 i.^
451
+49,386
21-8
49 57
65-1
1-97
9-1
9-2
3
•886
452
+ 49.420
317
50
8
176-2
2-62
9-4
"•3
2
-881
453
+44.387
48-9
44 50
259-0
4-45
8-5
1 1 -2
2
•994
454
+49,514
53-2
50
7
132-2
8-65
8-5
lo-o
3
786
455
+ 49.637
2 14-0
49 41
135-6
4-54
9-2
13-0
2
•850
456
+ 49.665
21 'O
50
2
2698
3-28
9-1
1 1-4
3
-821
457
+ 49,671
22*2
49
14
67
680
77
II-5
2
759
458
+48,701
28-1
4858
3168
530
9-1
99
3
-886 A.
243-9
24-58
C =
13-5
3
-886A
459
+ 48,708
29*9
48 56
1427
3*35
8-9
10-2
4
-888
460
+ i8.7ii
30-9
48
13
316-8
2-68
9-1
9-3
3
•894 A.
336-8
18-85
C =
13-5
I
-909 A
461
+ 48,756
40-2
48
40
3427
8-22
8-5
9-6
3
-900
462
3 7*9
49 23
1729
2*55
97
10-4
2
-896
463
+ 49,891
95
49
21
257-3
4*95
9*3
117
2
•896
464
+ 47,806
14-2
47
21
65-8
715
9-1
9-2
2
-817
465
+ 49,1015
3«-6
50
7
2511
7-37
87
9-2
2
-896
466
+ 49.1092
567
49
32
57*1
3 95
8-5
1 10
2
•S96A
123*4
14-22
C =
12-0
2
-896 A
467
5 2-4
47
25
98-2
1-52
ii-o
11-3
2
•940
468
+ 30,3021
17 30-3
30
3
11-5
2-28
9-2
lo-o
4
•613
469
+ 28,2829
42-8
28
I
140-9
4'4i
lo-o
130
3
•650 a<
267-5
48-12
A =
8-5
2
-658 Al
470
+ 27.2943
59-3
27
51
206-5
717
8-6
9-8
3
•658
471
+ 27,2948
18 07
27
6
271-4
18-23
7-0
14-0
3
•676 ab
44*1
30-35
C =
lo-o
2
-671 AC
472
-1-27,2980
9 '9
27
57
^'S
3-o8
9-1
9-6
2
•655
473
+ 42,3026
lO'O
42 49
158-0
9-63
8-5
lO-Q
3
•703 BC
loo-j)
Tfi-n%
iL =
8-5
3
•703 AB
^^^^^^^H
■
1
I
I
1
'
— a
M
207
^
I^^H
■
Jm 1908.
New Double Stars,
J^A B.D,
R.A. 1900, Becl.
P.
D,
Mi<t.
Eiighta. DAte.
H
•
ta m
* 1
0
* ^
1907,
^H
474 -^ 44.3054
tS ]6'8
+ 44 55
34*5
3-68
9*2
12-3
3
725
^H
475 + 27,3032
24*0
27 2
222-9
972
8*8
9-8
2
•671
^H
47^ -»- 27,3041
267
28 0
347-6
2-52
9'5
lo-i
3
*666
^^H
477 -*• 36,3298
30-9
36 56
233'*
776
8-9
11-5
3
•677
^^H
478 -1- 42,3»44
405
42 30
182*3
8-22
87
9*2
2
•699
^^H
479 -♦- 37»32o8
57*9
27 9
1393
8-05
86
9-8
2
•603
^H
4S0 -4- 27,3218
58-9
47 33
304-2
2-45
9'i
101
2
*637
^H
481 -«- 37,3261
19 6*2
27 41
136*0
432
9*0
127
3
'650
^1
482 -•'35,3756
97
25 36
167^4
4-27
8*9
U*2
2
'609
^1
483 -^'35.3803
17^5
25 23
358-3
12*62
7 "2
I2'0
4
•634
^H
4S4 -^ 28,3322
20-8
2844
332*6
7*30
8*5
I4"0
3
•692 AB
^H
335*6
22*60
C =
9*0
3
'692 AC
^H
4^5 '^^ 37,3419
27 '5
27 55
343*4
217
92
105
2
*655
^H
4^ -has,387o
28*6
25 13
287-9
8-35
9*o
14*0
3
•656 BC
^1
18*2
45*24
A =
8-8
2
■633 AB
^1
L||far*'''^'^^'
298
27 10
336*4
3-87
9-1
11*5
2
*7oS
^1
■ «•»••♦- 27,3434
39*9
27 16
50*5
213
9*1
9 "2
2
•708
^H
^ -^27.3438
3i'4
37 41
243*2
15*40
8*2
10*8
3
714 AB
^H
205-5
20 32
C =
II '2
3
714 AC
^H
*^ ^43»3305
334
43 14
1668
350
9*0
10*2
2
740 BC
^H
2297
16*38
a —
I3*0
3
7SS Ah
^H
223*8
61*70
A =
8*9
2
740 AB
^H
491 -4-47,2874
33'5
47 54
577
9-67
9'i
9'6
2
720 AB
^1
251-0
l8*20
C =
24x3
I
735 AC
^H
*^^ +25,3902
342
25 28
1581
542
9*2
9-3
2
•632
^H
^^ +43,3311
34*5
43 H
3160
4*20
9*3
9*5
3
758
^H
^ "*- 370549
49*6
27 49
190-1
365
8*9
10 "2
2
725 AB
^H
309-0
t6'35
C =
12*0
1
739 AC
^H
495 -1-38,3553
54 3
28 43
310-5
4'ii
iro
ir8
3
•657 BC
^H
245 '5
39-87
A =
8-0
2
-688 AB
^H
496 -♦-38,3594
58-5
2843
279-2
2*22
S'9
10 -o
2
688
^H
497 •*- 39,3886
20 I'l
30 4
200 '3
5 '28
9*1
10*8
3
•658
^H
498 -i- 29.3889
17
30 6
241-3
9-38
8*3
11*2
3
*6S8
^H
^99 +45,3080
7-S
45 18
339 '8
14-35
8*0
12*0
3
784 AB
^1
77 '3
26 '20
0 =
13-0
I
756 AC
^H
^ ^49.3218
8*8
49 35
35 1 '6
6-45
S*&
9*2
3
891
^H
5°' +45.3093
9*o
45 17
125-3
r32
9-1
10'2
2
715
^H
^ +4^.3059
10 '9
4«53
223-2
11-25
77
10 -Q
4
-897
^H
n
i6'5
47 48
353 •!
4*57
92
9*5
3
734
^H
^ +28,3760
24-1
28 40
87^2
6*02
9-2
10*2
2
1^1
I
^^^^20S
r
■
^^^^^^H
■
■
■
1
B
I
■
1
1
a
F
Rev, T. E. Espin, Ifew DoMe Stars.
H
LXTTItJ,]
^^^H
B.D,
R.A. 190c
. DecJ,
P.
D.
MJ191. NlghU. D««|^|
«
b to
» t
•
tt
1907^^1
^^H 505
...
20 26-5
+ 30 9
13-0
1*92
9-8
lO'O
2
78l^H
^H
+ 28,3779
27-1
2835
303 -i
6-57
87
1 1 '2
2
*654^|
^^^^^507
+ 28,3790
28-9
28 31
295*5
7-30
85
ii-o
'603 ^^
3402
3273
C ;=
8*6
•603 AC
224'3
3652
D =
9-1
603 AD
^^M
+ 28,3^47
36-9
29 4
230U
225
8*6
lO'O
783 AB
22r*9
18*07
C =
to-o
783 AC
^^H
+ 48,3187
371
48 39
283-6
7-22
8-8
12-0
723
^^H
+ 27,3871
43'9
27 31
235 *»
611
105
107
704 BC
343 3
43*45
A =
8*0
704'fl|
^^V Sn
+ 26,4026
50^9
26 42
5«-5
7-42
9-0
97
640H
^^H 512
+ 46,3201
21 iS
46 52
18'3
1 3 '27
7*0
12*3
7toH
^^H 513
+ 45.3474
12*3
45 59
522
7-05
90
«3*5
•847 ^
^^H 5H
+ 46,3246
123
46 54
^95*9
3-85
8*9
9^3
'695
^^H
+ 25^4504
14*0
25 49
302-5
3 ■50
9'2
127
721
+ 48,3376
21*4
4853
161 5
1916
6'S
12-0
•709
^H 516
...
267
46 51
140 s
3*31
9*4
iro
•844
^^H ^^^
+ 28,4122
28*4
29 4
239^4
2-05
9-2
9*9
781
^^B
+ 45.3589
30*6
46 3
n-9
455
92
123
-666
^^H
+ 47,3476
30 "6
47 42
304^3
7-62
95
97
'801
^^H
+ 27,4125
34-6
27 59
38*3
7 19
9*4
9*9
714
^^H 521
+ 28,4171
39*9
28 19
2697
14*25
7*6
140
*628
^^H
+ 44,3972
487
44 46
1747
4*35
9'o
ii-o
-^m
^^H
+ 26,4294
49-1
26 33
94 '9
6'i9
9-1
92
764
^^H 524
+ 48»3536
49*6
48 52
ys
5*87
ii-S
m
776 B€
18S7
2037
A ~
90
711 ab
^^M
+ 48,3544
50-9
48 48
I49'i
382
8-6
lo's
711 1
^H 526
+ 25,4650
52*0
25 44
lo8*4
7 34
8'4
I2'5
77.^
^^H 527
+ 27,4230
568
27 21
207-4
3-05
97
9*9
2
6749
^H 53S
+ 46,3546
58^
46 44
74*5
2-47
9*1
117
2
720
^^H
+ 46,3555
59 '4
46 17
7r6
575
8"S
tro
2
70s
^^H 530
+ 47.3677
S9'5
48 II
igo-9
8'i7
8*0
9*5
2
703
^^H 531
+47,3680
22 0'2
48 10
225-1
255
9*2
irS
3
706
^^H 532
+ 46,3580
2'4
46 47
245*6
9 82
9-0
9*t
2
7« —
73aa
^^H 533
+ 45*3848
10*8
45 ^3
321 5
4*25
9*0
12-0
2
+48,3665
135
4839
292*4
21*22
70
12-0
2
755
^^H 534
+ 48^3673
14*4
49 >o
104'S
6*02
9-0
9*3
2
7«9BC
2487
9*37
a =
I2'0
2
789 A»
68-0
48-97
A ^
8*5
2
7S9iB
H S3S
+ 25.4724
20'0
2S 39
501-9
8*33
9*3
to*8
3
■
J
JaiL 1908, Ring-txteitsimi mi dua^jpmrmice of Saturn's Einff. 209
No.
B.D.
R.A. 1900. t>eci.
P.
D.
Ma««. Night«
. D9lt«.
516
h m
22 20*4
+ 26 54
270*1
2-97
IO'2
10 -2
2
1907.
*673
Si7
+ 49p3^5S
232
5<^ 9
197
227
92
9*4
2
^806
S38
*f 46,3716
247
46 24
66-8
3-40
9-1
IO-5
2
*SS9
$39
+ 42,4437
2S'3
42 36
2877
6'io
91
iro
3
'836
540
+ 4^,3762
287
48 26
281-5
r3o
9*1
9*9
3
709
S4I
+ 25,4787
35 '9
26 13
220'3
6*61
8-0
12*4
4
75i
54a
+ 49.3968
48-9
49 29
2826
5-05
87
105
3
710 AB
83*9
57*88
C ==
8^8
2
708 AC
543
+ 46,3945
233'S
46 58
22 'O
3-^7
92
10^5
2
783
544
+ 49.4054
4*2
49 22
245*6
2-30
9*5
97
2
*95i
+ 25*4927
i7'5
25 22
264'4
19-95
67
13-0
2
713
545
^48.40^
18-9
48 44
3»97
970
8-1
[20
3
755
S46
+ 26,4623
20'I
26 24
162*2
217
9*1
to-8
3
'683
547
+ 46,4096
31*9
4646
237^1
6vj5
8-5
12*0
2
795
54S
+ 46.4139
39-8
46 54
315-9
14 '37
8*5
88
2
835
S49
+ 47.4264
40*0
47 57
517
S-io
8-5
137
2
704 AB
23S7
16^07
C =
9-0
2
704 AC
SSo
+ 45i4323
4rS
46 7
167*2
1735
8-6
8-9
2
•814
S5»
+ 47,43^3 23 49'5
47 41
31 1 '6
472
117
127
2
'834 BC
11*4
24*60
a =
10-5
1
^865 Aa
88' I
3090
A =
8*6
2
*834AB
Appearance of Ring-extensiarh during the disappearance of
Saturfi^g Ring^ Oct-Nof\ 1907, By R. T, A. Innee.
A$ Professor CampbelFa observation of the appearance of
^^mnS rii^g will give rise to some discoseiou, I do uot delay
*^^ifliDg the notes I have made so far. The teleHC0|M? used is
J^^ 9-iiicb Grubb refractor menticmsd in an earlier note. Sir
^o-ward Grubb has supplied it with a double concave eyepiece of
J^^i magnifying power, which transmits at least twice aa much
^lii as an ordiuary eyepiece. Tbia negative eyepiece gives an
^^■^^^rt image; its ouly drawback is an excessively small field.
On several occasions Mr. R. N. Kotsie, my son and myself
?^%iced the beaded appearances referred to by Professor Campbell,
__^t we assumed that they were caused by either Mimas or
^'^ooladuB, and our curiosity did not lead us further.
I now gire, without further comment, the exact notes made by
^yBelf at the telescope : —
1907 Oct* 16. Ring seen at minnenta.
1 7. Ring idl but held steadily,
not full hiigth.
It is very faint and
210 Bmg^eaoimswnondisappmranceo/Satuim*^ LXvhi, 3,
1907 Oct 21. Extension of ritJg clearly seen on f. side; no! so
distinct on p. mde, but Titan and other
sate Hi tea near.
Although I refer to the appearance as the
**Ring" on the i6th and 17 th, this word might
convey a wrong impression. What is seen is a
ghost-like extension where the ring was. It
taperp oGf sharply ^ and is perhaps shorter than
the ring.
22. to Novr. 20. Between these dates this ghost-like
ring was seen on ail occasions that the planet
was looked at.
Nov. 21, Planet jnst past meridian. Ring-extension seen
to full length on each side. It is brightest
close to the planet, and then it is diacoo-
tinuons. Two cloud-bands on each side of
equator. Shadow of ring on planet is a
dt3ep brown, and there is a suspicion, but
nothing more than a suspicion, of its being
divided into two lines. (On Nov. 6 it was
noticed that the shadow of Titan was much
darker than the ring-shadow.)
25, Ring - extension decidedly discontinuous, and
doubtful if full length. The satellites no
longer bead the ring-extension, but pass N
or S of it.
A rough sketch will give an idea of the relative
darkness of the sky, the ring-shadow, cloud-
bands, and of the discontinuity of the ring-
extension about the dates Nov. 22-25.
Professor CampbelUs message reached here on
the 28 th inst-
Dec. I. Ghost-like extension, including discontinuities,
is about half the diameter of Saturn on each
side, and is dtBcontinuous. It leaves the ^
disc on the south side of the ring-shadow.
J6kann$timrg :
1907 December 2.
Jan, 1908. Observations 0/ Satuni*s Ninth Satellite, 21 1
Ohmreaiwn* of Saturtt'i Ninth Satellite, PIioebe,/rom PhotograpJu
taken tttth the ^o-incJt Reflector at the Royal Observatory^
(jheenuneh, in 1907.
{CrnnmuiiieaUd hy the AiiroTumwr Eo^al,\
Phcebe has been under observation during the recent opjKJsi-
tion of Saturn with the 30-inch reflector, photographs having been*
obtained whenever possible. In all 16 photographs have been
secured on 16 nights, between August 10 and December 6.
From one to two hours' expoauro was necessary on account of the
faiDtness of the satellite and its low altitude (5° south of the equator).
The positions of the satellite have been measured on the
photographs taken with the reflector with reference to three or
four faint comparison stars (of eleventh or twelfth magnitude),
symmetrically distributed about the satellite. Tlie positions of
these faint comparison stars were then measured rektively to the
reference stars (of eighth to ninth magnitude) in the Astrono-
miBche Geselischaft Catalogue on photogra|>hs (with 30*" and 40*"
exposure) taken with the Astrographic 13-inch refractor. The field,
lensibly free from distortion, being much larger with this telescope
than with the reflector, from 16 to 20 reference stars were
atailabie on each plate.
As Saturn moved slowly, it was possible to make one reference
5pUte serve for several photographs which were each referred to it
*Rit constants were determined in the usual manner, all the stars
ou the plate given in the A,G. Catalogues being used for this
purptwe. Right Ascensions and Declinations of Plioebe were then
'wtermined and compared w*ith the tabular positions of Saturn
*^ter applying to the tabular places the corrections
liA, -l-'-osi Dec.+o'*48
■« determined below.
Ob$trvaH9n9 qf Phahc.
^^.
to
If
IS
2
9
1
A
S
6
<3 55 35
■* 39 47
la 39 10
'^ 53 50
*' 4 59
10 56 II
»i 45 IS
« > 47 30
10 36 20
*o 52 26
»0 4428
^3344
^ 34 27
^ 35 9
^ 45 38
^pptfent B.A.
Apfkftrent Deo.
aaturn
D€0.
Eip.
h m s
*
«n s
J It
m
23 50 53 '23
-3 34 297
-0 27-3»
-4 320
10$
50 41 *oS
36 o'6
0 2871
4 295
<33
49 784
47 44-6
0 38-25
5 39*8^
U3
A» 53'36
3 49 32'2
0 39*62
5 50 I
120
46 19*31
4 S 47
0 52 53
7 22 "6
93
45 12 25
15 54'4
0 57 so
7 55-9
54
43 9*46
30 1-9
I 5*68
853-6
107
42 5r6S
4 3-^ 2*2
I 674
9 0'2
70
36 21 70
5 M 3^*1
I 27-68
It [6*t
90
35 47-97
18 77
t 29*11
II 247
120
34 42-92
24 srt
I ^I'H
It 40*2
53
33 41 '9*}
31 1-8
I 34*22
n 52'4
90
29 55''8
52 45 '3
I 40*62
12 18*1
100
28 4 '66
56 56*9
1 33'oo
10 45*9
121
28 12 86
55 35 -S
I 31*77
10 l^'l
\TO
23 3$ J^'6p
5 S4 497
-I 3r'04
-10 ^0
SP
15
212
ObservaiioTts of Saturn! & Ninth ScUdlite. LXvnL 3,
Errors of Tabular Place of Saturn,
The positions of Fhrnbe giveD aboye depend on the posttionn
of certain stars taken from two catalogues of the Astronomische
Greseilachaft, and will be affected by tlie mean error in the places
of these stars. To eliminate this it is necessary to determine the
position of Saturn referred to the same stars.
For this purpose a series of photographs of Saturn was taken
with the Thompson 2 6 -inch refractor, using the occulting shutter.
With a rather slow plate an exposure of 2 niiiuites was given to the
stars in the field, Saturn being exposed for about riiT*'* second
ev«ry alternate second. In this way a good measurable disc* of
Saturn was obtainetl, whilntt giving nutficient exposure for the start.
The field of the 26-inch refractor on a 16 cm. plate being only
I * S(|uare, or a quarter the area of the Astrographic plate, only
three or four stars were usually available on each plate, but tht>
positions of these were deduced from mea>^ures made on the
Astrographic reference plates for Phoibe» using all the stars. The
mean systematic error of these three or four stars will therefore
be the same as if all the stars had been used, and the position of
Saturn deduced will be affected by the same error, and will thtn
be coinparnble with the deduced places of Phcebe.
Eleven photographs were selected for measurement. From two
to four images of Saturn, and of each of the stars, were measured oQ
each plate in the Astrographic micrometer, and the following are
the results obtained. The observed R.A. and Dec. of Saturn wor^
computed to o" 001 nnd o"'oi respectively ; but as the tabular plac%
in the N.A. is only given to o*'Of and o"'i respectively, tlio
errors are only given to that order of accuracy.
Srront^N.A,
Tabular Phet of Saium.
Tab,^-0l»9.
I
July
24
■ it
-♦-■oi -0-3
Aug.
18
-06 '5
19
•05 -5
If
•06 -t
Sept.
9
•09 '6
23
^ ^5
Oct
2
•07 -4
4
'04 "3
Id
•05 7
,
«5
•05 '6
30
ean
-^2 -o-S
M
-••051 ^o"*48
1908 Jwmaerif S*
214 Observations of OccuUaJtions of Stars hy the LXVliL 3,
g w « «; «; ® «; f «; «; 14 i^* w J 00 j4 05 d
I -4 ^ pf pS: ^ tf ^ ^" &:' <i K 00 ^ -i Q <-; ed
o
III = - = = = = -='- = = - ll
I
m »n Q ^n Q Q *n Q
e« e« N NOOMO
§8
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2i6 Dr. A. M. W. Downing, Ephenurts of flora LXVUL 3
Ephemeris uf Flora near the time of Opposition in 1908. Bj
A. M. W. Downing, D.Sc., F.R.S.
This ephemeris is computed from Briinnow's Tafdn der Flora,
ill combination with the corrected continuation of certain of the
tables published in Monthly Notices, vol. Ixiv., No. 6.
Berlin
Midiiiaht
Apparent
LogDIitance
from
JllUIIl|l|IIIiy
K.A.
Dec.
Earth.
May I
h m H
15 56 4446
12 5 29-7
O-19103
2
55 49-64
2 26-6
•18968
3
54 5370
II 59 245
•18840
4
53 5671
56 23-6
-18720
5
52 5873
53 24-0
•18607
6
51 59-82
50 259
•18500
7
51 0-05
47 296
-18400
8
49 59*53
44 35-2
•18308
9
4« 58-30
41 42-9
•18223
10
47 56-45
38 52-9
•18146
II
46 54-07
36 5 '5
•18077
12
45 51-23
33 21 0
-18015
13
44 47 96
30 39-6
•17961
M
43 44*29
28 1*5
•17915
15
42 40-27
25 27-0
•17876
16
41 35-98
22 56*2
•17845
17
40 31-51
20 29-3
•17822
18
39 2695
18 6*4
•17S06
19
38 22-39
15 48-0
•17798
20
57 17-92
13 34*2
-17798
21
36 13*61
II 25*1
-17806
22
t35 9*50
9 20-8
•17821
23
34 5*68
7 21-8
^17844
24
33 2-25
5 28 -2
-17875
25
31 59-24
3 40-2
•17914
26
30 56*74
I 58-0
-17960
27
29 5478
11 0 21*8
-18014
2ii
28 53*47
10 58 51-8
-18075
29
27 52*91
57 28-2
•18143
30
26 5313
56 11-2
-18219
31
15 2S SV19
- VQ SS o'8
-18302
Fan. 1908. newr ihe time of Opposition in 1908.
.217
BeriiB
Arouent
LoRDIftuioe
ftrom
Earth.
0*18392
Jone I
R.A.
h m •
15 24 56-11
Deo.
10 53 57-0
23 59^
53 03
•18489
23 2-97
52 109
-18592
22 8*05
51 28-9
•18702
21 14-27
50 54*2
•18819
6
20 21*64
50 26 9
•18942
7
19 30-25
50 7-1
•19071
8
18 40*18
49 55-0
•19206
9
17 51*47
49 507
. -19347
10
17 4-13
49 54-1
•19493
II
16 i8'i7
50 5-2
•19645
12
15 33 62
5024-0
19802
13
14 50-56
50 50-6
•19964
M
14 9'03
51 252
-201 3 1
'5
15 13 29-07
10 52 77
0*20304
Magnitude at ojipositioii, May i8 = 9*7.
MONTHLY NOTICES
OP THE
ROYAL ASTRONOMICAL SOCIETY.
;. LXVIIL
FfiBfiUARY 14, 1908.
No. 4
ANNUAL GENERAL MEETING.
. F, New ALL, Esq., M.A., F.R.S., pREaiDBNT, in the Cbair.
'he Ref»ort of the Auditors of the Treasurer's accounts for
ear 1907 was read, and is given on p. 224,
'he Aunaal Report of the CoanciJ waa partly read ; see
21 to 510.
'he Address was delivered by the President, after which the
Medal waa handed to Sir David Gill, to whom it had heen
rded ** For hin Contributions to the Aatronomy of the Southern
lidphere, and his other Astronomical Work" (see pp. 317 to
pertain alterations to the Byo Laws which had been re-
it;nded by the Cuuucil, and of which due notice had been
^M to the Fellows, were put to the Meeting and adopted. [A
* of the Bye Laws as revised is seat to all Fellows of the
he President having appointed the Scrutineers, the Society
«Hi to the ballot for Othcers and Council for the ensuing
The ntimes of those elected are given on p. 331*
*he thanks of the Meeting; were given to the retiring Members
buncil, and also to the Avid i tors of the Treaaurer'a accounts
to the Scrutineers of the ballot*
[enry Ilennann Grnning, M.Sc, A, M.Inst. C,E., 3 Blakealey
Avenue, Ealing, W, ;
an B&tiliaan Hubrecht, B. A., Ph.D,, Christ's College, Catabtvd^'&v
16
220
Meport of the Council to the
Lxvin. 4,
Victor A. Lowiuger, Trigonometrical Survey Department,
Taiping, Federated Malay States ;
Hev, Malcolm Parker Miller McLean, M.A., The Rectoryj^
West Rayiibam, Norfolk ;
Alfred William Porter, B.Sc, Assistant Profeflsor of Physic
University College, London, W,C. ;
Harold Knux Shaw, B,A., Trinity College, Cambridge ; and
Capt. Eidred Weston White, Brockley Villa, Upton Road,
8outhvillfc, Bristol,
were baHoted for and duly elet'ted FeJlows of the Society.
The following can did li tea were proposed for election as Fellowa
of the Society, the names of the proixiBers from pefAinal knowledge
being appended : —
John Bullock, M.A., 78 Airedale Avenue, C his wick, W. (pro-
posed by J, IL McClure) j
Arthur Brunei Cbatwood, B.Sc, A.M.Inst.CE,, Astronomer to
H,H. the Nizam, Hyderabad, Dec can, India (proposed by
H, H. Turner) ;
F, R. Cripps, 22 Horneey Riae Gardens, N» (propoaed by
A. C, I). Croramelin) :
Henry Zouch Darrah, C.S.L, Indian Civil Service^ Junior
Cailton Club, Pall Mall, S.W. (proposeti by Sir R. 8. Ball) ;
Charles Cask ell Falkiier, M,A., I re ton Biink, Htisholme,
Manchester (proposed by Sir Andrew Noble) ;
Henry William Moore, B.A., 64 Curzon Street, Mayfair, W.,
and New University Club, St, Jameses Street^ 8,W. (pro-
posed by J. J. Atkinson); and
Harold Morris- A irey, M.Sc, Lecturer in Physics, Armatrong
College, Newcaatle-upon-Tyne (proposed by Thomas Thorp).
^ebi.igoS. Mighiy^hth Annual General Meeting. 221
KVORT 09 THl COUNOIL TO THE ElGHTT-EIOHTH AvWAh
General Meeting of the Sogibtt.
The following table shows the progress and present state of
the Society : —
1
II
SI
FbUowi
1
'
1
c n
a s
1906 December 31 ' i
3
260
+ 4
409
+21
48
+ 1
721
1 Since elected ...
...
! Deceased
-I
-8
-6
-5
...
Besigoed
...
...
-3
*•'•
Rf'moTala
...
+ 3
-3
...
...
Expelled ^ ; ...
-I
...
...
1907 December 31 i
2
259
4."7
44
723
222
Etpmi of tks ComicU to ilu
ijcvur.4.
Mqjar Hiiy Aetount m Trmmirer of the HctycU
RECEIVED.
Bftlanoetii 1906 December 31 : —
At Bankers*, as per Pass-book „.
Id hand of AiaiBtant Secretarj on Account of
Turnor and Horrox Fund
In hand of AjisisUnt Secretary on Petty Casli
Account
Dividends : —
£1,250 Metropolitan j-iier-cent. Stock
£1,964 12 7 Swansea Corporation 3|-peT*eent.
Stock
£3,4cx> EitMt Indian Railway 3-p«r-ceDt. De*
bentnre Stock
£3,200 Loudon and North- Western Railway
3-|>eroent Debenture Stock
£4,000 Mnlland Railway 2^-per'Cent Deben-
ture Stock ... ... .,,
£500 Lancashire and Yorkshire Railway 3-per-
cent CouBolidated Pr«* fere nee Stock
£1,860 Gas Light and Coke Co. 3-per-c«aL
Debenture Stock
£1,650 Commercial Gas Co. 3-per-cent, Deben-
ture Stock ,
Received on aeconnt of Snbacriptiona : —
Arrears ... ,. „
Annual Contributions for 1907
,, ,, in advance
Admisaion Foes .«
First Contribution a
Composition Fees ,
Sales of Publications, ic* :~
At Williams & Norgate's, 1906
At Society's Rooms^ 1906
Sales of Photographs, 1907
Income Tax refunded by Commiaaionera of Inland
Revenue ... ,^
Examined and fomnd 1
£ s.
d.
' -^i
14 I
0
J
4 6
0
J
0 17
5
19 4 1
3S 12
8
J
65 6
6
■
96 IS
0
n
91 4
0
95 0
0
14 5
0
53 0
3
47 0
6
49$ 0 10
129 3
573 6
8 8
0
0
0
52 10
3^ tS
0
0
800 i «»
175 7 «
44 IS
io« 5
1
3
54 17
0
20S 0 3
26 14 n
£
U727 15 5
1
Richard iNWjjtDu
G. J. NKWBBQnL 1
A. K CONEADY. 1
JFeU 1908. Eighty-eighth Annual GettercU Meeting. 225
iMirotiomic^il Society, from 1907 January i t^ December 51,
PAID.
AMtat&Dt Secretary : Salirj
«, „ Editine Soci«ty*s PublicAtioDfl
Cl«rk'a Salary
HooM Duty ,..
Fii« and Servants' Insurance
Printinc;. 4c.: —
Monthly Na£i€e» ( Spottiswoode k Co,) . , ,
„ (NeUl k Co.)
Appendix to Menunrs (Harriaon k Sons)
Liat of Fellows (Neitl & CoO
MiseellaneoQ^ (Spottiiiwoode & Co.) ,
Phoio-EoKTaving for MonUhly Noiiceit (A. E.
Denl4tCo.) .,.
Tor
Tnmor and Horrox Fund, purchase of books for
" Library
ding booka in Libmfy
Reproduction of Fhotogrnphs (Hiiiton & Co.)
Catftlogiiitig Astronomical Literature for the Inier-
national Cataloguo of Scientific Literature
Expenaea of Meetings
Lantt-m expenses .,. ,„
Time Signal : rental of wire ... «
Poatage and Telej^ranis
Carriage of Parc*«ls
Stationery and Office px pauses ...
„ (Spottiswoode & Co.) ...
Album for Photographs of Associates
Houae exftenses : Allowance and aotidry expenses
Coftl and Gas ...
Slectric Ligh t expensejt
Itispatring Council -room Chairs (Shoolbred h Co.)
Bnndry Fittings and Repairs
Sundries
Gold Metials (A. Wyon)
Chequa-book and bankfrs' charges on cheques
Balams, 1907 December 31 :—
At Banki'rR', as per Pass-book
Cbaqnea not credited till 1 90S ...
In hand of Assistant Secretary on account of
Tumor & Horrojc Fund ... 626
band of Assistant Secretary on Petty Cash
Ac<.-ount ,., 811
£ 4.
d.
£ s.
d.
250 0
0
50 0
0
7S 0
0
375 0
0
3 12
6
9 12
6
12 5
n
U
41 12
3
327 14
I
2t fO
0
15 16
0
16 7
6
ij 5
I
456 4
tl
2J 3
6
3« 17
4
62 0
10
41 16
4
30 0
0
20 7
II
6 5
2
5 0
0
31 n
1
94 2
10
2 0
4
1
—
joS to
I
2 10
0
59 0
9
44 19
7
19 tl
n
9 15
0
l\l
4
t
146 18
8
5^ 12
6
0 10
9
3«6 7
%
27 2
0
- 427 '3 3
£1.727 15 5
224
Btpori of the Council to the
LIVTTL4;
Bepart of the Andit^jra,
We have examined the Treasurer's account of receipts and
expenditure for the year 1907, and have found and certified the
same to be correct. The cash in hand on December 31, 1907,
including the balance at the bankers', etc., amounted to
JE427, I3«. ^d.
The funded property of the Society is the same as at the end of
the previous year, but we are glail to report an improvement in the
financial position of the Society, as shown by the balance on
December 31, which exceeds that of January 1, 1907, by more
than £400.
We have examined the Stock Certificates and the Bank of
England verification of the Inscribed Stock standing in the name
of the Society.
The books, iiistroments, and other effects in the possejjsion of
the Society have been examined, and they appear to be in a
satisfactory condition.
We have laid 00 the table a list of the names of those Fellows
who are in arrear for sums due at the last Annual General
Meeting of the Society, with the amount due against each
Fellow's name.
(Si^ne^i) Richard Ikwardg. _
G, J, Newbrgin.
A. K Con R ADV.
Bequesig U the General FuncU of the Soeietij,
The Camngton Bequest (1876) : A sum of £2,000 Consolt.
Sohl in 1899, and stands now in X 1,881 148, London and
North- Western Railway 3-per-cent. Debenture Stock.
Jlie McClean Bequest (1905) : A sum of £2,000* Invested ia
Swansea Corporation 3|-per-cent. Stock.
The Farrm* Beipiej?t (1^06) : A sum of£ioo. Invested in Swanaeft
Corporation 3j-per-cent, Stock,
The cost of reportiog Professor Hale's lecturt at the special evaning meetiiig
on Jqiio 26, 1907, woB defrayed by Mr. Fran kl in* Ad Am s.
Trust Fundi,
The Tumor Fund: A aum of £464 18#. East Indian Railway
3-per-cent Debenture Stock; the intei'est to be used in the
purchase of books for the Library.
Tfte Horror Meinorial Fund \ A sum of £103 6s. East Indian
Railway 5- per cent. Debenture Stock ; the interest to be ueed
in ike purchase of books for the Library.
Feb. 1908. Eighty-eighth Annual General Meeting.
225
THb Lee and Janson Fundi A aum of X334 loa. qd. East
Indian Railway j-per-ceDt, r>ebent\ire Stock ; the interest to
be given by the Council to the widow or orphan of any
deceased Fellow of the Society who may stand in need of it
The HannaJi Jackson {nee Omit) Fund : A sum of £309 iS*, 6d,
East Indian Railway j-per-cent. Debentnre Stock ; the in-
terest to be given in medale or other awards, in accordance
with the terms of the Trust
Aiseit and Present Property of the Society, 1908 January i.
£
386
27
8 I
Sfi 8
0
63 0
0
75 "
0
193 4
0
12S 2
0
6 6
0
qi6 12
0
8 8
0
BalaaoeB, 1907 Decembar 31 : —
At Bankers*, ai per pAS9-l>ook ...
Country cheques not credit«d till 1908
In hand of Assbtant Secretary oll account of
Tariior and Horror Fund ...
In hand of Atsistant Secretary on Petty Caah
Aocctitjt
Due on acooimt of Subscriptions t —
4 Contribqtioiia of 6 years' atandiiig
^ r- 5 »• »»
9 .. 4 .► M
46 .. 2 .,
61 „ I
OtksrsttiDs
Less Subscriptioiis paid in advance
Due for Fhoto^rapba sold ...
Doe from WilUoma & Norgatc for Publicmtious sold in 1907 ..,
£3,400 East Indian Railway 3 -per* cent, Di-bentnre Sto^^'k, in-
cluding tha Tnrnor Fund, dir Hfirrox Weniorinl Fund, the
hte nud Janson Fund, aud ttiu Hannah J&ckBon {n^e Qwilt)
Fund.
£3,200 London and North-Weateni Rail way 3-iHjrcent, Deben-
ture Stock (including the Carrington Bequest),
£4,000 Midland Railway 2i^per*ceiit, Debt:nture Stock,
£500 I^ncashire and Yorkshire Railway 3*per-cent Gonaolidated
Prefepsncc Stcwk*
£1,860 Gas Light and (Joke Co, 3-per'Cent. Delicnturc Stock*
£1,650 Commercial Gas Co. 3-|»er-eent Debenture Stock.
£l,2$o Metropolitan 3-t>er^ent, Stock.
£1,964 12 7 SwaiiB4ea Corporation 3^-p«r-cent. Stock (the
McUiean and Farrar Bequests).
Aktronomii^al and other ManuiicrtptK, Books, Prints, Fhoto-
graplia, and Instmuienti.
^Fttmitnre, Ac,
toek of Publications of the Society.
^ Four Gold Hedals,
rf.
427 13 S
508 4 o
200
23 o 9
^^r 3i^H^9
^B^ 226 Beport of the Council to the hXVlXL 4,
^^^B Cdeitial Photographs
m
^^^" The following is a list of reproductions of Celestial Photograplift
^V published by the Royeii Astronomical Society for sale to the
^^ Fellows :^ ^
^^H &«f. Subject
^^^H 1 Total Solar Eclipse, 1889 January i
Photofrraphed b^ ^|
W, H. Pickering ^|
^^^H i Total SoUr Eriipfe, 1893 April r6
J. M. Schaeberle H
^^^H 3 Total SoUr Et lipse, i|S6 August 29
A. Sch'uater ^|
^^^^H 4 Nebulise iti the rhimiet
laaac Rtibertu ^^^B
^^^M 5 Nebultt Al 74 Piseium (KGX. 628)
Isaao Roberts ^^^^
^^^H 6 Qrtat Nebuk in Orion
Isaac Roberts ^^^^|
^^^M 7 Milkj Way near M 1 1
E. K. BariiArd ^^^|
^^^^B 8 iiilky Way near Cluster iu Fenett9
K E. Barnard ^^H
^^^B 9 Comet c 1S93 IV. (HrcK»ks), 1893 October 21
£. K Barnard ^H
^^H 10 Garnet a 1892 L (Swift), 1892 April 7
K E. Barnard ^H
^ 1 1 Kebula about if A ryux
David GiU H
^^^^ 13 Porliou of Moon (Hygiuus-Albategnius)
Loewy and Puiseox ^M
^^^P 13 Comet € 1893 IV* (Brooks), 1893 Ckstober 22
£. £. Bamani ^M
^^^^ 14 Comet c 1893 IV. (Brooks), 1S93 October 20
E. E. Barnanl ^H
^H 15 Comet c 1893 IV» (Brooks), 1893 November 10
E. E. Baniard ^|
^1 16 Comet a 1892 I, (Swift), 1892 April 26
E. K. Buruard ^M
^H 17 Cotiiet/i892nL (Holmeji), 1S92 November 10
> E. E. Barnard ^M
^^L tS Comet a 1892 L (8wift). 1892 April 18
£. K Barnaxd ^|
^^^H t9 Portion of Moon (A1|>h, ApoDniues, &c.)
Loewy and Puiaetu ^H
^^^^H 20 Nebula iu Andrtxitrda
Isaac Rai>erts ^H
^^^H 21 Jupiter f tSgi September 26
Lick Observatory ^H
^^^1 23 Clniter U [3 HermliB (N*G.C. 6305)
W. £. Wilson H
^^H 23 Total Solar EcHpso, 1893 April 16 (5 sec.)
J. Kearney ^^^M
^^H 24 Total Solar Edipne, 1893 April 16 (20 eec.)
J* Keuaey ^^^^|
^^^H 25 The Moon (Age 7"^ 3^)
Lkk Ottaervatory ^H
^^H 26 The Uo<m (Age t2'i 6|^)
Lick Obserrmtory^^^^l
^^H 27 Tbe Moon (Age 16^ 18^)
Lick Obiarvatory^^^l
^^H 28 TbeMooti(Ag«23<^gb)
Ltck Obeerratort ^|
^^^1 29 Tha8uu, 1892 February 13
Roy. Oba,, Grvenwielt H
^^^H 30 The Sun, 1892 July S
Roy. Obs,, Gr««tiwicK ^M
^^^^H 31 Portion of Moon (Region of Magitiiia)
Loewy aud Puiaeux ^M
^^^"^ 32 The Moon (Age 14*^ I*')
Lick ObaeiTAtory ^M
^H 33 Portion of Moou (Ptolemffius, kc, )
Lick Observatory ^^^H
^^^H 34 Portioti of Moon (Mare S«reuitatia)
Lick Observatory ^^^^1
^^^™^ J5 Portion of Moon (C\aTm%, licfttna, kc^
Lick Obaervatery^^^li
^^^^^^^■^B
Feb. 1908. Eighty-eighth Annual General Meeting. 227 ^|
B.AM.
^H
Phot<^raphed bj ^^H
36 Portion of Moon (RtigiomonUDiii, Ac)
Lick Observatory ^^|
37 Portioii of Moon (Tyclio, Th«bit, Ac.)
Lick Observatory ^^M
38 Portion of Mooii (Theophilus, &c.)
Lick Obaervatory ^^H
39 ToUl SoUr Eclip«i«, 1S96 August 9 (3 see.)
S. Kostiusky ^|
40 Total Solar Bclipae, 1^96 Augint 9 (26 see.)
A. Hansky ^|
41 Cluster M 56 Lyrm (N.G.C. 6779)
^1
42 NebiU« M 81, Si UracB Majorui (K.G.C. 3031
' 3034) ^M
43 CUwter M 56 LyruB (N.G.C. 6779) (enlarged)
^^H
44 Sokr Corouft, ]S7t December 12, Buikul
H. DavU ^^H
4S SoUr Corona, 1S75 Aptil 6, 8iam
Loekyer and Scbuater ^^|
46 SoUr Corona, 1878 July 29, Wyonihig
W. Harknes9 ^M
47 SoUr Cotouji, 1&82 May 17, Eijyi»t
Abney and Sebuster ^^M
4» SoUr Corona, 1883 May 6, Cariiline I>.laiid
Lavvrance and Wooda ^^M
49 Sotar Corona, 1885 Sept. 9, Wdliiigton, N.Z-
Radford ^H
^0 Solar Corona, 1886 August 29, Grenada, W.I.
A. Scbuater ^H
^' Solar Corona, 1S87 August 19, Japjiii
M. Sugi>ama ^^M
^-^ Solar Corona, 18S9 January l» California
W. H. Pickering ^M
^J SoUr Coronu, 1889 December 22^ Cayenne
J. M. Sehaeberle ^|
Si SolarCorona, 1S93 ApriU6, Fiiudiiini
J, Kearney ^^|
5S &Ur Corona, 1893 Aprij 16, Brazil
A. Taylor ^H
56 Creat Nebula in Orion
VV. £. Wil»on H
S7 Dumb-b«1l NebnU, Vulpeeuht (N.G.C. 6853)
W. K Wihon ^^1
58 €|»iraJ Nebula, Catu^ FewiHci (N.G.C. 5 194- 5 J
W. E. Wikon ^1
S9 Ditto (en)argetl) (N.aC. 5 194)
W. E. WOsOD ^M
^ -Annalar Nehula, Ipra (N,G,a 6720)
W. E. Wilson ^M
^' ^ei^or Trail and Comet Brooks, 1S93 Nov. 13
E. E. Bornanl ^|
^ Toul Solar Eclips*, 1898 January 22 (5 sec)
W, H. M. ChriEtte ^M
^3 I'^^Ul Solar Eclipse, 1898 January 22 (20 sgv% )
W. H. M. Christie ^M
H Soli^f (Corona, 1896 August 9, Novaya Zemly*
0. Baden Powell ^|
5 Soliy. Corona, 1S98 January 22, Pnlgjioii, India
E. H. Hills ^M
^ ^«Uiila in AndrometLi
Roy. Obs.. Qreenwieh ^H
^ ®|>ectrum of Sun*fl Limb, 1898 January 22
E. U. Hills ^1
^ ^ntmaX Nebnla, Ltfr^i (N.O.C. 6720)
Lick Obaervatory ^H
^ I>iimb*bell KebnU. Vulpeada (N.O.C. 6853)
Li<!k Obsorvatory ^H
^ ^Inml Nebula, Onui VetuUki {S .Q.Q. ^l^-^) Lick Obaervatory ^^
^* Spinal Nebula, tArw ifa/'or (N.G.C. S457)
Lick Obserratory ^^|
^^ '^rifid Nebula, Sa^^Uarhta (N.GX. 6514)
Lick Observatory ^^1
^^ CJreat NebuU in Orion
Lick Observatory J
'* ^lu»t*r U 13 fffrculit (N.G.C, 6205)
Lick ObuerTStory ^^^
^^^ ^Ur SurfftOrt with Facole, iSgs Augtiat 7
G. K HaW ^^H
SM
Report of thi Cauiynl to the
MM, Subject.
No.
76 FiictiliB ind PromtQouce,^ 1892 Jane 25
77 ToUl Solar EkJlipae, 1898 Jan. 22 (§ sec.)
78 Nebula H V, 14 Cyrjni (N.G.C. 6992)
79 Portion of Moon {Thf'ophihw, fitc)
80 ToUl Solar Eclipse, I9(X} Ma^ 2$ (30 tec)
8t Comet 1901 I., 1901 May 4
82 Comet 1901 I., 1901 May 6
83 Comet 1901 I., 1 901 Ma J 9
84 Solar Surfaee with Faculie, 1895 Attgiint 18
85 Solar From men tea, 1894 April tt
86 Nebula about Nova Prrsei, 1901 Sept. 20
87 Nebiilzi about Nova Prrsei^ 1901 Nov. 13
88 Total Solar Eclipse, 1901 May 18 (xo mc)
89 Total Solar Eclipse, 1901 May i8{40»ec.)
90 Comet b 1902 IIL (Pcfriiio), 1902 Sept. 29
91 Portion of Mo<m (Mare Serenitalifl, kc.)
92 Portion of Moon (Rongli Crater Rfjj;ion»
Mare Nubuim)
93 Portion of Moon (Tycho, Theopbilus, kc.)
94 Portion of Moon ( BulUaldna to Copernicus)
95 PurtioD of Moon (C^pernicns, enlarged)
96 Great Nebu*4 in Orioji
97 Great Nebula in Ori(m (Central portion)
98 Nebula in Andromeda
99 Nebula in 6>f/MH» (N.G.C. 6960)
100 Nebubi in Cypma (N.G.C. 6992)
101 Cluster M 13 Hereutu (N.G.C. 6205)
102 Cluat<?r M IS Pegasi (N.G.C. 707S)
103 Soliir Surface with Facoloe, 1903 April 37
104 Tlie Mood, i9Cx> April 5
105 The Moon, 1902 November 13
106 The Moon» 1903 Febrtiary 6
107 Tba Moon^ 1903 September 12
108 Nebulosity about 15 Monoeti-^is
109 Milky Way about 0 Cygni
no Ntibiilo-sity near « C^fpmt
111 Milky Way near x^9^^^
112 S tar CI oil d i n SagiUarim
113 Wilky Way in Cepheus
1 14 Milky Wfty about M %
led by ^H
Photographed by
0. £. Hale
\V. H. M. Christie
W. E. Wilaon
Yerkei Observatory
E. E. Barnaitl
Roy, Obs.»Cap»ofG. a
Boy. Ob«i.,C^pe ofO.fi.
Perth Oba., W. Auttrftlia
H. Dealandraa
H. Deslandrea
G. W. Bitchey
G. W. Bitchey
F. W. Dyaon
F. W. Dyson
Roy, Oba., Groan wiol
Yerkea Obserratory
Yerkes Obserratoiy
York<*H Observatory
Yerkei Observatory
Yerkes Obnervatory
Yorkca Observatory
Yerkes Observatory
Yerkes ObseiTatory
Yvrkea Observatory
Yerkes Obaervatoiy
Yerkf s Observatory
Yurkes Observatory
Yerkaa Observatory
P. Pniaeux
P. Puiseux
P. Putaeux
P. Puiaeux
E. E. Barnard
E. E. Barnard
£. E. Barnard
E. E. Barnard
E. E. Barnard
E. E. Barnard
K, E. BarnaTrl
I
EI^^^B^^H
1908. Eujhty-Hghih Annual General Meeting. 229 ^^|
Subject,
Hilky Way about B OphiitrM
£. G. Barnard ^^|
llilky Way nearN.G.C. 6475
K. E. Barnard ^H
preM Kebulu near p Ophiuchi
E. K. Barnard ^H
llilky Way about 58 Ophiudii
E. E. Bp^ruiirti ^H
llilky Way near Otm^ nebula
E. E« Barnard ^H
BtAf Clond in Sagittarius
E. E. Barnard ^H
lebtila about ^ Scorpii
E. E. Barnard ^H
|iitt« 1905 Janaary 30
Roy. Obs., Grflenwich ^^|
Jun-«pot, 1905 January 30
Roy, Obs,, Greanvrich ^^|
ltiQ« 1905 January 31
|tiii'ai»ot, 1905 Jauuary 31
Roy. Oba., Gr»enwicli ^^|
Ro}\ Oba.^ Qieeitwieli ^^|
iniU 1905 February 2
Roy, ObfiM Greenwich ^^|
Itta-spot, 1905 February 2
Roy. ObA.p Greenwich ^^H
Inn, 1905 February 3
Roy. Oba., Groenwich ^^^
Juii-«pot, 1905 February 3
Roy. Obs., Ureeuwicli ^^^
Bun, 1905 Fe>>ruary 5
Roy. Obs., Greeuwieb ^^|
^-8]H>t, 1995 February 5
Hoy. ObB.» Green wkb ^^|
\an, 190S February 8
Boy. Oba., Greeuwich ^H
Jon spot, 1905 F«l>ruary 8
Roy. Oba. , Greenwtcb ^H
Jebttla near ^ Endani^ 1905 Janaary 8
^H
lebnla M 33 TriangtaH^i. G,0, 598)
Uuac Roberts ^^^|
HtbnU in Perseus (N.G,C. 1499)
Hebula in Mowtcero^ (N,G.C. 2237-^)
Isaac Roberta ^^H
Isaac Roberts ^^H
r«bu)« V V. 24 Comas (N,0.0. 4565)
Isaac Roberta ^^H
lebak* ^ \, 42, kc, Cam^ (N.aC. 4631)
Lsiiao Roberta ^^B
!lebul« Itl V, 37 Q/jmt(K.aC. 7000?)
Isaac Roberts ^^|
ITebuIa Index Cat. 405 PifrvH
att8ter« In /^wim (N.G.a 869, 8S4)
Isaac Rot»erta ^^|
:!luster 4 VI. 30 CaMfiopHit (N.GX. 7789)
laaae Robert! ^^H
Wipsc, 1905 August 30 (5 »M.)
W. H. M. Christie ^H
tfilipse, 1905 August 30 (20 nee.)
W. 11. M. Christie ^H
Bclipse, 1905 August 30(7 aec)
W\ H. M. Christie ^H
|klip«e, 1905 August 30 (20 aoc.)
W. H. M. Christie ^H
feclipM, 1905 August 30 (Portion)
W. H. M. CbriHtii^ ^H
■fafgjon of N«bubi p Ophiuchi
E. E. Barnard ^H
Mebola p (^hiuchi («nW«fd)
K E. Barnard ^H
fc^ion of $ Ophimhi
E. E. Halyard ^H
Breat Rift n<*ar 0 O/^^iu^At
E. E. Barnard ^H
Br«at,Star Cloud in Sagitttirim
E. E, Barnard ^H
■mall Star Cloud in Si^fUimrius
E. E. Baruaid ^|
230
M^xni of th^ Council to ths
LXTIIL 4,
Ref.
156
158
159
Region or Cluster M ] I
Sun-spots, 1906 July 6
Sun-spot » 1906 July 31
Suu«pot, 1906 AnguHt 30
Kclipse, 1905 AuguJit 3 (large prominence)
Photois^pbed bj
E» E. Barnmrd
Royt Obs., Greenwieb
Hoy* Obs,, Greenwich
Roy, Obe., Gr«fnwicK
De la Ban me Plufinel
N08. 44-55, ^*^®- ^4' ^5' ^^^^ ^^^ M7 f<*"« * series of corona
|)}iotographfi, oriented and reducf^d to the same scale.
The above photographs are now od sale to Fellows as prints,
either platinotype or arisUitype, mounted on sunk cut-out moimtfi,
measuring 13 int^hes hy 10 inches; idso unmuunted, and as lantern
glides. No3. 44-55 and Nos. 64 and 65 are also supplied as
tranaparencie^j 6| inches square.
Pince of prints^ mcnmied is. 6d, each, unmounted 1$. each;
lantern elides, is, each ; packing and postage extra*
Transparencies, 6 J inches square (Xo«. 44-55 and Nos. 64 and
^SK 3*- ^''' each.
Oi'ders tu he atldre*sed to W, H, Wesley, Burlingtt^n House,
London, W, lu ordering prints or sliiles the R.A.S, Reference
No. only need be quoted, but in the case of prints it should be
stated whether platinotypos or aristotypes are required, and
whether mounted or unmounted.
The Gold Medid.
t
The Council have awarded the Gold Medal of the SoeietjT to
Sir David (Hll, K.C.B., for hia Contributions to the Astronomy of
the Southern Hemisphere and his other Astronomical Work. Tli»
President, in his Address to the Society, gives the gr«>imds upon
which the award has been founded.
Publkaiinm of the Society,
During the past year vol Ixvii. of the Monthly Noticm htt
been issued.
The following jMiper, reprinted from the Philosophicai Trama^
iioTig of the Royal Society, haa been issued as an appendix U> tht
Jih'mofrs i —
F, W. Dyson, Deteirni nation of Wave-length from Spectra
obtained at the total solar ecU^aes of iQoo, 1901^ 1905.
Pek 1908. KvjMy-eigkth Annual General Meeting. 231
Obituary,
The Council regret that they have to record the loss by deatb
the following Fellows and Associates during the past yeai : —
^Honorary Member : — Agnes Mary Gierke.*
Fellows : — Alexander .Stewart Herschel,
Willittin Jtjhnstuo.*
Zufur Jimg.
Lord Kelvin.
David Juseph Kennelly.
Peter Matthews.
Thomas Perkins.
James Geurge Petrie,
E'lward Power,
George William Read.
Thomas Robson.
Edward John Routh.
Henry Chamberlain Russell .
William Sinims,*
AasoGiates : — Asaph HalL
Jules Janssen.
Maurice Loewy.
Charles Tr^pied.
Her run on Carl VogeL
An obituary notice is also given of James Kennedy Esdaile,
mrho died in January 1908.
Jaues Kknnbdt EsDAiLK, the eldest son of the kt© Edward
Esdaile, of Ockly, Surrey, was born in 1S40. He was educated
at Charterhouse, and afterwards at Feterbonse, Cambridge, taking
hia M.A- degree in 1871. In 1876 he married Florence, only
daughter of the late George Crawshay, of Houghton Castle,
Tyneside, North urn berlanii. Until 1889 he lived at Saint Hill,
near East Grinstead, where he had a small private observatory and
occupit^d himself in obsarvatitm of aiin-spots. More recently he
lived at Horsted Keynes, where be died, 1908 January 6. He
waa a Magistrate and Deputy -Lieu tenant for Sussex^ and in
1881 was High Sheriff for the county*
He was elected a Fellow of the Society 1872 February 9.
/.
Alhxander Stkwart Hbrbcbbl was the second son of Sir John
Herachel, and the fifth of twelve children. He was bom at the
Cape of Good Hope in 1856, during the historic astro uomx^'A
* Obititar/ ia Aminal Report for t^ol*
2^2
Bipo7't of the Council to tfte
ULTni.4»
expedition of hia father. He went (1851-55) to the famoua
Clapham Grammur School^ where the Rev. C. Pritchard wm doing
pioneer work in the way of a scientific education for boys ; and
thence to Trinity College, Camhridge (1855-59), and to the lioyal
School of Mines (1861-5). He was then (1866) appointed Pie-
feasor of Mechanical and Experimental Physica in the University
of Glasgow, a ponition which be resigned in 1871 in favour i*f t
corresponding ProfessorFihip at Durham ; and from this he retired
in 1 886. FrnDi 1 888 till hia death in 1907 he lived with brother
and aistera at Observatory Houae, Sloughy the former residence of
his grandfather.
Alexander Herachel was best known for his work on luminoM
meteors. He was himself a diligent observer, spending long hours
in the open in the watch for metenrs. His post of astronomical
observation at Slough was necessarily different from that of his
grandfather, for durinj^ the half -century following the death of
Sir William trees had grown up in the garden where his great
telescope used to stand ; and when four of his grandchild reji
retnrned to Observatory House in 1888 (after half a century uf
occupation by strangers) they found a plea^santly shaded garden,
but no horizon visible. Over the wall, however, in the kitchen-
garden, where Sir WiJliam's forges and optical works used to be,
there were no trees ; and there Alexander Herschel would lie on
his back and watch the broad sky for meteors. His observations
are contained in a long series of small note-bookSf and every
observation ia numbered, starting each new year with unity again.
The last observation is dated 1907 February 13. A hasty glance
at these books with unskilled eyes snggi^ste that probably there is
a great deal of valuable material of which no use has yet been made.
But a proper estimate of the value of his work in this field can
only be given by a meteor observer, and Mr. W. F, Denning has
very kindly written the following 00 te^: —
** Professor Herschel 's meteoric work was characterised by it»
remarkiible accuracy, its comprehensive detail ami large amount^
extendinj4 over something like half a century. It not only embraced
his personal obaervntions^ but comprised the comparison and
reduction of a great number of materials sent in to him by variolic
other observers in England and abroad. Diiring a long series ef
years he collected as many descriptions as possible of the £re^balU
which appeared from time to time, and calculated their real pathi
in the atmosphere.
** As a result of long practice, he acquired great precision to noting
the Bights of individual meteors amongat the stars, and could
reproduce them on his charts wilh unusual fidelity. He observed
the great meteoric showers of 1866, 1872^ and 1885, and coUectad
together the different values for ihe positions uf radiation, and
obtained their mean places. It was from bis averaged radiant for
the November Leonids of 1866 that Professor Schiaparelli wai
fluccessfully enabled to deduce his conciusions on the virtual identitj
of the orbits of thia meteoric stream and Tempers comet of 1866,
1908. Eighty-eighth Annual General Meeting,
233
An important paper by Profe^aor Her^cliel appeared id the
7iiy Notices for 1S72, in whick Ite called attention to certain
ahower^ presumably connected with Biela's penodical comet, and lie
pointed out tbe probability of a recurrence of the shower at the end
of November 1872, advioing observers to maintain a watch of the
fiky at thia particular period. }1\a anticipations were realised in a
very notable manner by the occurrence, on November 27^ of one of
the graodest meteoric exhtbi lions of modern times, which fully
substantiaiad the theory of close association existing between comets
and meteors, and certainly demonstrated that the slow meteors
returning at intervals at the end of November really represented
the cUbris of the lost comet of Biela.
«• Valuable work was accomplished by Professor Hers ch el in the
calculation of the radiant points of comets, A complete list of bis
reaulta, forming a valuable summary for reference and comparison, was
published in the British Association Report, 1S75, aad in the same
volume and also in Monthly Notices, vol. xxxviii, p. 369, he gave
lUta of known accordances between eometary and observed meteor
tfbovreiB, In collaboration with Mr, R. F, Greg, he formed several
catalogQea of the radiant points of meteors observed by the British
Association members, including one giving 88 positions in 1868,
And another of 63 positions in J875 (British Association Reports,
186&. 1872, 1875)/'
But though the work on meteor.^ engrossed the greater part of
lus scientific activity, Alexander Herschel had many other interests.
One of the chief of these was photitgraphy. His father was a keen
and original photographer — the first man^ tt will be remembered, to
ose glass as a support for a photographic film (and the first picture
he took in this way was of his father's great telesco^>e}. Alex-
ander's devotion to photography was thus hereditary ; and here,
again, he not only worked assiduously himself, but stimulated
actiTity in others. In 1893 his portrait was presented to the
South Kensington Museum by the Amateur Photographic Associa-
tion, and among his treasured possessions was a beautiful album of
|>hotographs presented to him by the Newcastle-on-Tyne and
Northern Counties Photographic Association (of which he was
Freaident, 1885-7) as a ** slight acknowledgment of services
ceDdered."
His brother^ Colonel J. Herschel, has remarked on his extra-
onlinary vitality; he nearly always ran^ rather than walked, to his
miscellaneous occupations, and his mental activities had two
unfortunate results: he shunned the interruptions of society so
far S8 to become practically a reclu^e^ taking .ill his meals alone,
and he became impatient of his bodily needs until the neglect of
them shattered his health. He died on June 18, 1907^ at the
age of seventy-one, and on June 22 was buried in the grave at St.
LaareDce^s Church at Uptc»n^ where his famous grandfather had
be^n laid eighty-five years before.
He was elected a Fellow of the Society 1867 March 8.
234
Report of the Comwil to the
LXVll
William Thomson, Babon Kklvin of Largs, was horn at 1
me 24f 1834. He was the second son of James Tbomstn
deacciided from a small farmer in the north of Ireland, in 1851
became Professor of Mathematics in the Univergity of Glasgwir.
The James Thomson who in 1871 suweeiled Hankine as Professor
of Engineering at Glasgow wus Lord Keivitj's elder brother. la
1834 he becanii* a matriculated member of the University, and at
the age of 15^ during a foritiight*s visit to Germany, he read
Fourier's treatise tti Buch pnrjwse that soon after bis return he
wrote a serips of papers in which bo successfnllj defended Fourier
from a charge of unaonndness brought against him, through some
misconception, by a vtry competent mathematician. In 1841 be
proceeded to Pelerlioime, Cambridge ; he was very yotithfiil-Jookin|
and waa known as ** the pretty boy," but, despite his youth, be
won the Oolquhonn Sculls in 1843, which, it is interesting to note,
had been won the previous year by the Hon. G, (afterwards Mr.
Justice) Denman. He whs also one of five Peterhouse men whu
founded the University Musical Society, the only survivor being
Bishop Cridge of Victoria, B.C., who is now 86. While still mi
undergraduate he publisheii paf>er8 in ti»e Cavihricfffe Math^maiirol
Jourtiaf on the Motion of Heat, and the Mathematical Tbeonea i»f
Electricity and Attractions. In 1845 he gmdual^d iia Second
Wrangler and first Smith's prizeman ; be was almost immedinti'ly
elected ii Fellow of his Cttllege, and then he spent a short time in
RegnauH*rt laboratory in Paris. The next year he was appointed
to the Chair of Natural Philc»aopby at Glasgow, which he continued
to bold for fifty-three yi^srs ; on resigning the Professorship he
applied to be appoint-ed hs a research student ; and in 1904 he was
inst ailed as Chaueellor of the University.
To give even the titles of the papers he published on various
branches of mathematics and physics, and the names of the instro-
ments he invented, would re<|uire more apace than could be allot lid
to this notice. Hta great strength lay in the wonderful faculty be
possessed for directly applying the resulta of the most nbHtniH
mathematical investigations to the solution of prHctical problem^l
and in the mechanical ingenuity which enabled him to inve(^|
instrument after instrument which satisfied, almost to perfectio!^|
the requirements indicated by the most refined analyi^is. It 'w^f
Professt^r Newcomb whof^aidjon the occasion of Lonl Kelvin »jnbil^|
in 1896 : ^' It has been the ^^eneral^ — I do not know but that it l4^|
^jeen the almost universal— rule that ibe men who have by thi^|
Indies and thought promoted our knowledge of nature, have otfH
been those who have applied that knowledge to the direct IjeweSt
of mankind. I am not sure but that Lord Kelvin is the aingK
kolitaiy exception to this rule." ^M
W His direct cnntributions to Astronomy were not nnmerodH
compared with the rest of his work, but he has told ns thai h*
learnt from Stokes before the end of 1851 that the trxist^nce nl
the B line in the solar spectrum proved the presence uf sodiuto in
the iSuDj and from that daW he regularly taught this fact in hi»
Feb. 1908. Fu/h4i/-eif/htk Annual General Meetifitf,
235
lectures ; XtrchoiTs work was not published imtil 1S59. In 1S62
he presented a paper to the Royal Society of Edinburgh in which
he showed fiom the o<]Uation8 representing the candiiction of heat
]Q a solid tliHt the pret^ent distribwtioii of undergrnuud temperature
necessarily implied a finite limit to the age of the Earth, and he fixed
the date of its consolidatian at between twenty and four hundred
I millions uf y^ars ago. An uddii^^s on Ger^logical Time, given tu the
Beological Society of Glasgow in 1868, led to a lively controveray
pith Htixley, in which he maintained that the fact that the
Bblatene^is of the it^rth eorregporida with the present length of the
lay shows that the Earth could not have been rotating with much
greater velocity when it soliditied, and that the retardation due to
tidal friction therefore enables ua to assign a limit to the time
within which this must have happened. He also endeavoured, by
means of the conservation of energy, to fix a limit to the time
during which the Sun could, by its radiation, have ke{)t the Earth
at a temperature at which organic life is po^ible. It tthould^
however, be mentioned, with regard to the argument from the
figure of the Earth, that Sir Creorge Darwin believes the Earth to
luiTe a sreater power of adjusting its figure to its rate of rotation
than Lord Kelvin thought possible. It was juat after the con-
clusiun of this controversy that Huxley introduced 8ir William
ThooiBon (as he then was) a.^ his successor in the Presidency of
the British Asaociation with the wordsj ** gentler knight never
broke lance." Returning to the same subject thirty years later,
with a more complete knowledge of underground temperature, Lord
Kelvin placed the date of solidification at "more than twenty and
less tlian forty millions of years ago, and pr.ibably much nearer
twenty than forty." The discovery of the pro|W5rties of radium has,
however, diminished the force of these argnments, whether derived
from the conduction of heat in the interior of the Earth, or from
the age of the Sun's heat
These investigations, as well as the principle of the dissipation
of energy, which was stated in a paper presented to the Royal
Society of Edinburgh in 1852, ami in the Philomphkal Magcuine
for the same year, have a direct bearing on cosmical physics and on
the eTolution of stelhir systems.
Lord Kelvin also gave much attention to the rigidity of the
Earth, as evidenced by the phenomena of precession and the tides*
Ha took np the former problem where it was left by Hopkins,
and, by amending his argument, he showed that it led to the
eonclusion that either the glohe is solid throughout, or else the
crust yield?* with nearly the same freedom to external forces as
if it were liqu'd. He then compared the heights of oceanic
tides on a perfectly rigid globe witli those on globes possessing
the rigidities of glass and si eel respectively, and, from tlie best
data available, concluded that the average stilTness of the Earth
is greater than that of glass, but perhap>s not greater than that
of iiiech His work on the Tides in general and the construction
of his **Tide Predictor" afford a very good iUualraliou ol \i\%
17
236
Report of tJu CaitncU to tht
LXniL4,
[tower of fir«t dealiug with theory and then translating it ialo
[jFiictice,
He efiFected many improveniente in navigation. He pn>>lisheda
set of tables for facilitating the use of Sumner's method for det«r-
mining \Xw |Kj«ition of a ship. In 1876 li»f patented a cornpaas in
whicl* the single, large, strongly magnetised needle formerly ust*d
is replaced hy eight small parallel mugneta of comparatively fe«)»lH
intensity ; he was thus ahle to secure lightness and long vihn
period, giving greater steadiness to the compass ; the short n^
allowed the correction to be accurate on all courses of the ship, lor
the place where the adjustment was made, and the anmll ntagnetic
moment allowed the correction of the quadrantai error to reoiain
acciimte for all parts of the world. As an illustration of his
attention to minute details, it may lie noted that 32 radial slits
were given to the card to prevent warping. This compajs^s is now
in almost universal use» as is also the deep-sea sounding apparatus,
which ia frequently the only means liy which a sailor can determine
his posititm when neither land nor sky is visible.
On& of the greatest of the indirect benefits which I^ord Kelvin
conferred upon Astronomy was through ocean telegraphy, which
has rendered possible the accurate determination of lonjjitndesL
To this achievement be contributed more than any other person,
whether by demonstrating its theoretical possibility in opposition
to Sir George Airy, by showing that the shortness of the life of the
brat Atlantic cable of 1858 \vasdne to the intensity of the currenta
used in signalling, or by his invention of the mirror galvanometer
and siphon recorder, which i-cnderod pussible the use of compara-
tively feeble currents.
He was knighted in t866 as a recognition of his aervicea in
connection with the first Atlantic cables of 1858, 1865, und i
He had been elected a Fellow of the Royal Society in 1851 ;
subsequently received a Eoyal ami a Copley medal, and was el
Freaident in 1890. lie was President of the Itoyal Society _
Edinburgh 1887-90, and again from 1895 to the time of his death,
and President of the British Association at the Edinburgh meeting
in 1871. In 1S92 be wa.s created a Peer, taking bis title from the
small stream at the foot of the bill on which the Univererty of
Glasgow stands, lie was one of the Hrst recijuents of the Order
of Merit at its ci-e^tion in 1902, and he became a Privy Couuoillor
in the same year.
Nothing could show more clearly the estimation in which F^opd
Kelvin was held, both at home and abroad, tban the celeViration of
the jubilee of his professoriate at Glasgow in 1896, Delegates
from all parts of the world presented addresses ; those from the
Institute of France: brought the Arago medal, which had been be-
stowed upon only three previous recipients. Congratulations wcru
received from the Queen and the Prince of Wales, and telegrama
from EnrapCj Asia, Africa^ Aui erica, and Australasia,
Lord Kelvin was twice married : first to Margaret, daughter of
Mr. Waiter Or urn, of Thovnliebauk ; and secondly, to Frances Ann*,
^ in
m
daaghter of Mr. Charles R. Blandly, of Madeira. Tbere waa no
issue of either tuarniige. He died at NetherhalJ, Largs, on
Decemher 17, and was laid to rest in Westminster Ahbe}^ ou
J^eceniber 23 ; his grave is by the side of that of Sir I^^aac Newton.
He was elected a Fellow ol' the Society 1868 November 13.
s. A. 8.
A
David Joskph Kennelly was born nt Cork, Ireland, on
'October I, 1831, and was the son of David Nngeiit Mouutjoy
Kennelly and Zaida Teresa de hi Honmnu Kennel ly, itee
ilarquesa de la Rtimana, of Las Palmns, Minorca* He went to sea
midshi|>tnan in 1846, and was rafiidly prtnnoted in the service
the Royal East India Comj»any*H Navy. He was made second
ling-mjister of H.M.S. Meteor in 1849^ and, m master uf the
irigate Fertxn^ m 1853 conveyed the lotii Lancers fionj Gannnore
to Suez, ou their way to the Crimea. In the same ye^ir he served
on board the frigate Akhar ou a«i expedition to the Persian Gulf
and the Euphrates, bringing to Bombay Layard's Nintiveh sLihs
now in tlte British Mnaeum. He wus accustnmed to compute the
djiily longitudes as well as latitudes mentally, with the aid of
•the regular tables, but without iiencil or paper* The science of
astronomy especially interested him in rehitiun to navigation.
At the outbreak of the Indian IMutiny in 1857 Captain
Keonelly was Naval A.D.C, to the Governor of Ronibay. He was
mediately sent, as master of a frigate, with despatches to the
neral commatiding at the Capti of Good Hope, calling for such
troops 4ta South Africa could spare. He brought back to India
H.M. 89th regiment uf infantry, and landed them into action at
' le Gulf of Cam bay. Returriing to Bombay, he assisted in the
?iarmainent of three mutinous sepoy regiments. He was twice
mentioned in despatches in recognition nf services.
After the hidian Mutiny, Captain Kennelly was appointed a
Roint Commissioner of Bomlmy, and master-attendant in churge of
M, dockyard at that port. He held this appninlment until he
ired from Indian service in 1S68 and returned to Great Britain,
©studied law in London from 1872 to 1876, and was admitted
to the bar at ths Inner Temple, pleading for some years in the
Admiralty Court at Westminster, Later he became a barrister of
the Supreme Court of Nova Hcotia, and w^a^^ appointed a K.l\ of the
pr«:tvinee of Cape Breton. He matie his home in Louiaburg, Cape
llnaun, and was for many years connected with the eoal-mining
induatriea of that province.
C^ptaiti Kennelly received a diploma from the University of
Bombay, and was at the time of his death the senior lionorary
corresponding member of the Royal Geographical Society, whose
<iiploma he received for Orit^ntal geographical research. He died at
Sydney, Cape Breton, on August 27, 1907, bequeathing a fuud
for the maintenance and preservation of a {lortion of the old French
<'iUdel at Louisbiirg, Cape Breton, and for the protection of its
kbtorical relics. He had already presented the land tot V\im ^ut-
238
Report of the Council to the
hXYlU, 4,
pose to the town of LowiBburg, He is survived by ten cljilrlren.
He waa elected a Fellow of the Society 1 864 January 8,
The Kev. Thomas Perkins was educated at Blundell'8 School,
Tiverton, and at Christ's College, Cambridge. He took hia degree
in 1865, when be was bracketed 20th h rangier, Lord Rayleigh
being the senior wrangler that year. He waa ordained Deacon in
1868 and Priest in the followin^^ year by the Bishop of Dnrhani»
and after holding mathematical masterships at Durham and
Heading Schools he was in 187S appointed Headmaster of the
Shaftesbury Grammar «School. In 1893 he was presented by the
Bishop of Salisbury to the living of Tumworth, Dorsetshire,
which he held uiitil his death on March 21, in the 65th year of
his age. He took great interest in architecture, and waa the author
of A Handbook to Gothic Arekitedure and of several volumes
in "BelFs Cathedral SiTies." At the time of his death he had
just completed a book 00 Romsey Abbey Church, and waa engaged
in editing, and partly writing, a book to Ix? entitled Memoirs of
Old Dorset, He was an enthusiastic photographer, and enjoyed a
well-earned reputHtion for the artistic merit of Ida work.
Mr. Perkins was elected a Fellow of the Society 1885 Juna iz,
James George Fetrie was a native of Kirkcaldy, Fifeshire. He
came to London at an early age and engaged in financial journalism.
He soon made himself highly respected in the City, and for the last
sixteen years had been chief of the reporting staff of the Finaneial
Times, He was for a time President of the Shorthand Society in
London. He waa an ardent volunteer, and on coming to London)
joined the London Scottish ; he left that regiment as a non»
commissioned officer to take a commission as second lieutenant in
the 2i8t ^Middlesex, from which he retired quite recently aa a
major. He received tlte V,D. for long service, and waa one o{ the
moat popular officers in the battalion. He was an original member
of the British Astronomical Association, served on the Council
1892-1894, and was Secretary from 1894 until his death, which
occurred on September 22, after a long illueea. He waa in his
60th year. He was twice married, and leaves a widow with four
children.
Mr. Fetrie was elected a Fellow of the Society 1889 May 10.
Thomas Robson was born at Lisburn, Co, Antrim, on 19th June
1 868. He served as a pupil teacher at the Spring Grove Board School,
Huddersfield, from rSSj to 1887, as assistant master at Rastriek
Grammar School from 1887 to 1889, and at the Ulster Provincial
School, Lisburn, from 1890 to 1892. In 1893 he took his B.A.
degree at London University, and the next year he returned to bis
previous post at t!ie Ulster Provincial School, Here he remained
until 1897, when lie again came to London as a student at the
Royal College of Science. He passed the intermediate examination
fot the USc. in 1899, aud Ike next year he was appointed Soienee
Bb, 1908. EiglUy-eighth Anmial General Meetifig,
239
/th
ftstor at Doncaster Grammar School, a post he held until his
atb, which uccurred 011 April 5.
He married Kliia Williams, of Randairs Mills, Co. Wexford,
August 1904, but leaves no family.
H*j was elected a Fellow of the Society 1903 November ij*
Edward John Routh was born at Qiiehec in 1831, and was
the 8011 of Sir Ranilolph Isham lioutli. K.C.B., Commissfiry-General
to the British Forces from 1826 to his death in 1858, by his second
wife ^larie Louise, sister of Cardinal Taachereau, Archbishop of
i^Kiebec. The boy came to Lowdou at the ag^ of ti, and waa
**ducAted, firH at University College School^ and later at the
College itself ^ under De Morgan. He matriculated at Loudon
University in 1847, and won two eiholarships ami a gold medal.
He went up to Petevhouj^, Cambridge, in 1850; wai^ Senior
Wrangler iu 1854 (CiiMk Maxwell being second, and the two
being bracketted for the Smith's Prizes); was elected a Fellow of
Peterhouse, ap[>ointed Lecturer, and ultimately became a most
successful firivat^ tutor. In 1S64 he married Hilda, eldest daughter
of Mr, (afterwards Sir) G* B. Airy, Astronomer Koyal, and hy the
statutes of the time he thus vacated his fellowship, hut in 1883
he was elected to the first honorary fellowship at Peterhouse. He
^ gave up private tuition in 18S8, though be continued to lecture.
iMHis heilth broke clown about the beginning of 1907, and on Friday,
^^KUie 7, he pasi^d peacefully away*
^^1 It may not be ej?sy for future generations to understand the
P^Dsition Eouth occupied in Citmbridge life, or the debt Cambridge
owe"* to htm.
There are, roughly speaking, two ways of giving instruction, one
by lectures to large audiences, the other by personal interviews
with small groups or individuals. The private tutor was called
into 6xi:*tence in Cambridge hy the failure of the Colleges
HMud of the University to give any teaching b*^yond lectures,
^H&d sometimes very inadequate lectures. The importance of
«uch "coiohing" had been rendered manifest by the success of
those who were able to pay for it, and it was *e.aay to
recognise tbat some coaches were better than others by conj-
pariiig the achievements of their pupils. Routh was practically
the *Huc,ce^or of a great coach, William Hopkins, with whom, he
had hiuHelf read, ami who was able in 1849 to say that iu twenty-
one years he haJ had among hi:* pupils nearly 200 wranglers, 17 of
them senior wranglers. Routh's own success was even greater,
fi>r between 1858 and 18S8 he had between 600 and 650 pupils,
including 27 senior wtanglers. In fact, in the twenty-live years
1861-85 he claimed the senior wrangler in every year but one,
Hia sTicces* was so great that at one time more than a (quarter of
ilte undergraduates stt) dying mathematics were pi actio ally learning
all their mathematics from him. His pu]»ils w&th naturally divided
into lour "years" by their time of entering the Univetsily -, Mni
mjeh "year^' was subdivjdeef iato three or four classes^, fto t\iaX \u^
240
Report of tht CmmcU to the
LxvnL4.
had perhaps a dozen classes going at ones ; and to each class he
would talk without hesitation for the allotted hour, rarely forgetting
to begin just where he had left otf, and seldom waking even a
slip in working on the bkckbnard. When it is remembered that
he was thus covering the whole range of subjects for the Tri[)oa,
including ultimately the matheniafcical physics which had so rapidly
developed dnriiig his own lifetime, one cannot but marvel at the
aatonishing memory which retaitied such a mass of facts in so
orderly an arrangement. If at any time in bis career all living
senior wranglers could have been induced to compete in au
01ymy)ic Tripos, Routh would surely have been easily first of them
all. Some of the lessorts hv gave were doubtless old and had been
repeated many times, but many were new, for Routh kept fully
abreast of the tinies^ reading, digesting, and reducing to the form
of **s little manuscript, which you had better copy out in the other
room/' such memoirs as were appearing from day to day. He was
teaching almost uninterruptedly from 7 or 8 a.m, till 2 p.m. ; after
which he took a walk for two or three hours with the utmost
regularity, devoting the evening to eetting or looking overeiamina*
tion papers fi>r Ids pu|)ib. This busy life went on throuj^h July
and August (the *^ I^oug Vacation "} as well as through the regulsr
terms ; but immediately he was free, he got away with his family
abroiid, or to some complete change of scene. How he managed t<>
find time to write hi.n compri'hensive treatises on Statics and
Dynamics, and to win the Adams Prize in 1877 by a masterly essay
on the ** Stability of Motion/' niUKt remain a my*«tery to most of us.
Looking to-day at Routh*s notes on Ai*tronomy, one finds
little to modify ; indeed they have been consulted many time*
during a dozen years of teaching, and always with profit. The
detuils of a transit circle have become more familiar to his former
pupil than they were when Routh sketched his diagram on the
board and briefly enumerated the chief ]Kiints, but years of added
experience do not .«rnggest any essentiyl improvement on Routh^s
description, which has often Ijeen rcptMited almost verbatim. His
<|uaint little touches of htimour are often the quickest route to aa
explanation. ** There is a wheel with sixty teeth,'* he would say
in describing the chronograph, "hut one is removed, so there ore
only tiftynine/* After explaining the method used for planetary
abermtioii by antedating the oWrvation — ** Why cannot thi*
method he used for a star? "—he would ask, and then reply^
"Because light may take a thousand years to reach u* from ths
star, and duriuj^^ that time the path of the earth is sensibly curved. '*
Those who looked up from their notes at this woidd catch the
little twinkle which imjiressed the point permanently on their
memory. There were ijuaint expressions in othtT departments ijf
mathematics which suocesaive generations of pupils learnt to look
for. Ail floating tiodies were called ships: **Let ns now consider
the case if a ftplierical ship," he would say. His pupils did not .«»?«•
much of him (mtsidc the class- roiim until they had taken their
degrees, but some of t\iftm v?«itft \\^«vv \itv«"\\^%<!!d to form lifelong
Feb. 1908. EigJUy-eighth Anmml Oeneral Meeting,
241
friendships with fcheir fortner tutor, T<» accompany him on one
of his daily waJkn was to realise a new pleasure in walking, ft h
p&rha|>s worth recordinj^s though a trivial malter, that he seldom
failed to drjtw iitteiition, when opportanity offered, to the transit-
circle mark on Granfcchester steeple, pointing ont Id his companion
bow it had been placed so as to minimise unsightliuesa.
When he gave up private tuition m 1888 his former pupib
asked permission to have his pr>rtrait painted by Herkoincr as a
present for Mr^*, Houth. Mr, Justice Stirling made the presentatioti
in the company of a large number ut the subtjcribers, including 13
aetuor wrani^lere.
Dr, Kouth was elected a Fellow of the Royal Society in 1872,
aod served un its Council, 188S-90.
He was elected a Fellow of the Society on 1866 April 13.
I.
H. H, T,
By the death of Mr. Hknrv CHAMnaRLAiN RuasKLL, C.M.G.^
A., F.R,S** the State of New Suuth Wales has lost its former
Government A^trouomer and ^ft-teorologist, and Australia one of
its most eminent sons. Mr. RnsRell ivas the son of the Hon.
Bourn Russell, and was lK)rn in West Maitland in 1836. He
graduated at Sidney University in 1858, and obtained the Deas^
Thomson Scholarship for t^hysics and Chemistry* Immediately
on leaving the university he was ai^jiointed assistant to Mr, Scotr,
the Oo%^ernment Astronomer. At the aj:e of 25 he teinporarily
htld this latter f:»ost after the ileath of >rr Scott, and before Mr.
Smalley was appr»inted. On the dtath of the hitter in 1870, Mr.
Hussall succeeded to the post and held it for thirty five years. He
at once set aljout re-organ isitig und re-furnishing the observatory, so
thiit within seven years he had added seven new rooms and a
dome, and had replaced the old instruments by modern ones, and
throughout his hmg tenure he kept the okHervatory in an etiicient
-te. He also turned his attention tu meteorology. In 1870 there
re 12 nieteiU'olugical oliservin;^' stations in the whole State of New
uth VVate-H, and the Government covild not aHbrd any large con-
tribution towards an increase, Mr. Russtdl, by his activity, per-
atiasion, and intkience, induced the squatters and ftirmers to make
observations nf rainfjill and evapnration ; and by his mechanical
ingenuity furnished the stations with the necessary apparatus, with
the smallest possible outlay. Thf result was Uiat when he resigned
his post in 1903 there were 1800 stations, and over 90 per cent,
were voluntary.
Mr, Russell was chief organiser of the Australian observei^ of
^^e transit uf Venus in 1874. Five Au.stralian observatories took
^Bsrt, and Mr. Russell furnislied the report to the Itoyal Astronomical
^^%ociety.
I By 1876 he had collected all the observatinns of rainfall and
f ' -sed them, with the result that he believed tliere was a perio*
In 1878 he bad a large number of retums (torn \i\v^
oljeerving atalioue, and after careful analysis was eua\}\e«\ lo ^orcv*
^ou
242
Report of the Council ia the
LXVIH. 4.
mence tlie publication of weather maps in the imfjera. Ixi 1887,
in corjjunctioD with Sir Charleii Todd of South Australia and Mr.
Ellery of Victoria, he succeeded in establishing a system of weather
forecast, the weather chaoges occurring with an amount of regu-
larity which permits of 82 per cent, of the forecasts being correct,
Mr* Russell was greatly interested in the project of charting the
heavens by means of phoUif^raphy, and attended the first meeting af
the Congress in Paris. The zone -54' to - 6^*, requiring 1400
plates, wa» allotted him.
Such are the chief landmarks in two branches of scientific work,
and they convey but a poor idea of I^Ir, Russeirs genius and general
activity. Tbe picture may he filled in from the following general
remarks.
Considering him aa an inventor and mechanic, we find a b'st
of 23 instrimieutw deaif^^ned and in great part made by him, gener-
ally witi» the object of ensiinu<: success in his meteorological
endeavours. We can mention only a few ; —
A self- record iuLC Anemometer and Pluviometer.
A self-recording Tide Gauge,
An e hi! c trie Barograph.
Various self-recording Pluviometers.
An Anemometer in which the motion of the vane and cui*s is
conveyed 75 feet vertically to the recording parts, and which ald«^
permits rain to drop 65 feet down the centre of a larj^^e tub« and
he recorded on the namo sheet aa the wind.
A Ggvernur fur driving clocks — the governor floating in mercurf.
The application or comhioation of the two pendulums to pro*
duce uniform rotary motioji.
An Ki|uatorinl Stand fur the 1 li-iiich refractor.
Tilt' Etpiaturifd nujurjLmg for the 15-inch reflector.
We find that he contributed 130 papers to varif>iia societies;
and a general iViea of the breadth of his interest- may be j^atbered
from a selection of his astroiiouiical papers contributed to oor
Society. To the Afemom he contributed —
** Reijort of the Transit of Venuft/' 1874, vol. xlvir, '* MeasurM
of Double Stars/* in Sir J. Herschel's Cape Cabibgue, tog)etl]er
with a list of 351 new double titers, vol. xlvii. "McasuPea of
Double Stars made at the Sydney Olmervatory in the vears 1882-
1 889," vol. 1.
And to the Month ft/ Noticm —
**0n the Australian Eclipne Ex|iedition 1871," vol xx«i.
** Note on the Nehtila surrounding rj Argus/' vol. xxxii. **0b«^
vations of Comet Brorsen/' vol. xxix. ** Ohservation» of the
Great Southern Coniet of 1880/' vol. xl. **Sanie Celestial Photo-
graphs taken at the Sydney Observatory." ** An Electric C^ontrol
for a Driving Clock/* vul. ii., "Tranaitsof Mercury 1881 and 1894,''
vols, xlii., Iv.
Mr. Russell took a very active part in initiating techiii«I
education, and served «s a member of the Board c»f Te<dimcal
Ecfucatfon, his servkea \>evu^ te^io^mfted when in 1891 he wu
Feb, t908« Jii^hiy -eighth Annual Oeneral Meeting,
243
made Yice-GhaueeUor of the University of Sydney. He was for
seyeral years President of the K'oyal Society of New Soutli Wales,
mud we may mention that be was the only graduate of Sydney ever
elected to the Royal Society, of whicli be hecame a Fellow in 1 886,
In 1891 Mr Hiiaseli wae made Com|iainon of the Ordf»r of St,
Micha^-1 and St- Gi^orge. lu I903 he had a severe illness, from
which he wa« scaitely exfiected to recover, and ever since he had
ChttfTered from indiiferent health ; tinally be fiucciimhed, in his yist
Sreur, on 1907 February 22. He leaves a widow^ with one ^on and
four daughters.
He was elected a Fellow of the Society 1871 February 10.
I Asaph Hall was born at Goshen, Connecticut, on the 15th of
October 1829. At one time wealthy* the family bad become ]ioor,
and A^aph Hall was apprenticed to u caqjenten Intending, how-
ever, to bectmiw an architect, be stiidit^d mathematics in his spare
time. Finally, in 1856, he entered the Univen*ity of Michigan
And studied {iMtronomy under Dr. Briinnow. Leavirii^ ^fichisifan, he
became an as^iat^int at Harvard Observatory, under Bond, where he
imained until \\u transfer to the Naval rJhaervntory at Washington
l862» Tn the following year In^ was made Protessor of Mathe-
tica. He was amongst the earliest astroooniers to appreciate the
lue of observations of Mnrs for detennuiiuj^ tbt* |>ar3dlax of the
8un ; his investigations, in 1862^ of the solur parallax l»y tins meane
\» his first ])aper of note. Fiotn observations made at Up?ala,
Santiago, and Washington, he deduced the value of 8 "84 for the
lar i>araltax. In these early years at Washington he also
blisbed A Cataltyjue of 151 Stars in the rhiMef iff PrstMpt^
and A Sfwty 0/ iomeis Fatje and Wmneeke^ allowing tlmt there
wsia no retaalation due to a resistirrg medium. In 1870 be
ptibtisbtd in the AmeHtuin Jotirnftl of Scv'ncf an interesting
jiajer on the ** Secular Perturbations of the Plaiiets/* An important
per on the ** Determination of Longitudes by Moon Culmina-
Aonn** appears in v(»h xxxiii, of our Monthhj Sotirei'. About this
time he was givitig great attention to minor |»Ianets both by
observation and computation. Thus in the AsfronomiMrhe Nach-
rtehiefif 1S75, will be foiuul a discussion of the Washington observa-
tinuB of Flora, and in the same publication fur 1874 a determination
of the orbit of Alcesle. Throughout this? period, too, be contributed
oumcnms mathematical pft^)er8 to the American Journal of Science
ftnd the Afetf»enijrr nf Mathentftti^'s.
in 1875 he took chfirge of the 26-inch Washington n^fractor,
and made nunterous ineasures of double-stars, diameters of
planets and distances an<l positions of satetlites, which, with
ilia dravvingB of Mars and 8aturn, appear itr the volumes of
Wiuhingian Oij^nratians. Sir W. Herschel in 1794 found the
rotation period of Saturn to be 10*^ 16", and from that time to
1.S76 no one appears to have made an attempt to verify this time,
•rofcwior Hall set this down as one of hi.«! tasks, and on D^emb^x
244
Xeport of the Cimncil to the
LXVIU. 4,
7, 1S76, he wiia fortimate enough to find near Saturn *a equ&tor
a bright spot, Thia he followed for sixty rotations, and w«*
enaltkd to fix its period of rotation as lo** 14°* 24% a value
which has subsequently bi»eii found by other obiervers. It will
thim be seen that Asaph Hall uas an exi!ellent obsenrer, and fully
alive to the needs of ustrononiy. It ia not Burprising, therefore^
that^ beini^* equipped with so pow»^rful an instrument as tho 26-
inch Washington refractor^ he should decide in 1877 to begin a
systemtitic search for possible satellites of Mars. On August ii^
the second day of his work^ he discovered an object which ht
&«8pet-ted to he a satellite. Ba<i weather intervening, he did not
obtain another chance till August 16, when his suspicions were
conhruied ; on the fLjIlowini^ night, while watching for the satellite,
he fouuii a second moon nearer to !Mats, The quick njovernent*
of this inner satellite were perplexing, and, to quote Professor Hair^
wortia, '* it would appear on different sides of the planet un tlie
same niL,fht ; and at first I thought that there were two or three
inner moons, since it seemed to rne at th«t time very improbable
that a satellite should revolve around its primary in less time than
that in which the primary rotates,** His observations of Augt»ts_^
20 and 21, however, satisfied him that there was but one inil<?r
moon. In 1878 he published the orbital elements of these
sntellites. showinj^ that Deimos completed its revolution in 30''
17*° 54"» **f**^i Phoboa in 7*^ 39^ 14'. For his discoveries he
recjeived in 1878 the Lalande Prize of the Paris Academy of
Srieuces. In 1879 Lord Lindsay, iis President, presented him
with the Gold Alodai of our Society for "his discovery and
observations of the satellites of Mar?*, and for his determination of
their orbits/* In the same year lie received the degree of LL,D*
from Yale Colloge.
In 1882 Nyn^n gave reasons for supposing Struve^s cionst^int of
aberration should he increased from 20*'*445 to 2o'''492, which,
. i;oT»d>i(ied with Newcomh's determination of the velocity of light,
^ive 8" 794 as the solnr pandlax. Loewy, in 1S91, had made in-
'TestigatiouK tending to show tliat Struve's value shoidd be retained*
and lit tliis juncture Profe8s<»r Hall, from observations of a Lyra
since 1862, had found the value 2o'''454, upholding Struve, and
making the corresponding parallax S^'Si.
Professor Hall devoted much time to the measurement of double-
stars ; his measures of the companion of Sirius from 1872 to t888
form a fine aeries, and give tli« |daee of the satellite till its depani-
tion from Sirius was only 5"*3. The whole of his doublensUr
measures are [mblished in two volnme^, one containing his work
during the years 1875-1880, the other 1881-91. This work led U^
investigations of the pimdlax of a Lyrte and of 61 Cygni. He alio
gave special attention to measuring the diameters of the van'oua
planets, and of the distances and positions i»f their satellites, and,
as was the cane with all his observations, he followed up the measure!
with investigations of elements, particularly of Mimas, Enceleda*^,
Tethjs, Dionc, Rhea, and T\\;an, ^\i\t\i ^x^ \tv A.^\»endix i. of tie
General
W -'■'?t Ohservatums, 1S83; of Oberon and Tituiiia, the outet
s oi Uraims, in i8Sr, Ajjpemlix i» : while in Appendix iL
he gives a determination of the orbit of the 84UolIite of Neptune,
and <iedacas the mass of NeptutiP^ Finding that most of the
meAsnrea of Hyperion had been made near one elongrtlion, he
Iaade measures in 1875 and 1876 with the 26-incb, and computed
b orbits His mathfr-matical pafiers were numerous, and covered
Boat aslTononn'cal investigations.
I Professor Hull had taken ^^a^t in several observational expedi-
lons, such aa — the solar eclipse of 1869 (Behring Straits), of 187a
Biciiy), and of 1878 (Colorado) ; the trunsit of Venus of 1874
VJadivostock) and of 1SS2 (Texas), In 1891 he retired from the
^avy» and m 1896 he was elected to one of the Professori^hips of
Astronomy at Harvard. Hi.'* death occurred on 1907 November 22,
He was elected an Associate of the Society 1S79 Jan. jo. T. L.
/
PlERRB JULRS C^AR JanssjBX Was born at Paris on the 22nd of
February 1824, He was descended from a family which originally
dwelt at Lii'ge. His father was a well-known musician, and his
mother the daughter of an architect of some celebrity in Paris,
unfortunate aci'ident when youngs through the ciirelessnesa of
nurse* rendered him lame for life. The boy seems to have been
dowed with considerable tabnt, which he at first excrrised in
wing and paintin^^'. At the iv^e of sixteen be entered into
10*^8^ as a clerk at a bank, in which he remained for seven or
;lii year?, but during this period he devoted his spare time to
te study iit mathematics, which no absorbed liim that he deter-
iued to quit bufe»ines8 and to study science. He entered the
Colletj^e Bonaparte, and about 1850 took hia deijree as Bachelier-^s-
Sciences. Subsequently at the Sorbonne he attended the lectures
of Cliaslej!^, Cauchy, Lefohure, Le Verrier, aiid Sturm^ and in 1852
received the ilegree of Licentiate of Mathematical Science, and
later nci that of Physical Science,
At llie early part, of Le Verriei'a direction of the Paris
rvatory, Janssen was with him as a computer; but the oceu-
tion not being very congenial to him, he did not lon^ remain at
le observatory, and for the next two years he became Assistant
ofessor of Mathematics at the Lyct'e Charlemagne.
In 1856 he made a U^m in Turkey, Asia Mint>r» and Egypt, and
1857-58 he uutlertouk a scientihi- expedition to Peru to investigate
id_ determine the jjOMtion of thi^ magnetic equator. In this he
isted by his ptipiln p^rnesi and Alfred Grandidier. Un-
y he was f=eized with serious illness, from which he nearly
led, and which compelled him to abandon the enterprise, and
sail for Europe to recover his health.
Soon after his return to France he commenced those researches
t have made the name of Janssen illustrious in the domain of
lar Physicp.
His first published scientitic paper appeared in th^ Complua
idus for i860, under the title ^'Sur i'absorption da \a e\i^\^\xt
246
Report of the CouncU to the
Lxvin. 4,
riyoonftnte ol^scure daiia lea milieux de reeil/* in whicli Le showed
the relative proportion of heat rays wbich are al>sor\ied by th«
coruea, the aqueous humour, ttie crystaUine lena^ and the vitreoQi
)iumi)ur, and ]iroired tiiat only a small percentage of aucb ray»
reach the retina.
At this time the brilliant researches of Kirch off and BonseD
had strongly attracted the attention of phyaicii^ts, and Janssen
determined to devote himself to some of the problems that had
been iDdicatpd by Kper.trum analysis. In i860 Brewster and
filadstone had demonstrated the existence of atraoiphcric banda
in the ^cilar :'pectriim. But so far back as 1852 the former bad
found that certain dark lines which were invisible with a high ^ttD
became conspicuous an it approached the horizon; and in 1856
Crookes had called attention to the fact that the atmosphere
absorbed a j^reat part of the more refrangible rays.
In 1S62 Janssen established an observatory at Montmartre far
the purpose of inve^itigating tlie absorptive influence of tha
atmosphere. By means of a powerful apectrovsct^pe composed of
five prisms he succeeded in revolving thft dark bands into fine line*,
which he found to vary in intensity directly as the altitude of the
Sun^ being daikest at sunrise and sunset. This established their
atmospheric origin, and danssen accordingly named them *' telluric
lines.*' The results were pubHsht*d in tlie Compter ftetpius for 1862*
In order to confirm tliese iruport.int observations he determined
in 1 864 to make experiments from the summifc of the Faulhom, when
he ^vas able to convince himself that the telluric lines were faint«r
there than at sea leveL Subst»<jnently, at Geneva, on examtmn^
with the spectrosco|ie the light of a bonfire at Xyon> a distance of
thirteen miles^ lie at once perceived several of the telluric lin^
whicli he and others had oliserved in the spectrum of a low sun.
Further researches on this point in 1866 enaV4ed him to establish
the fact that moat of these absorption lines are pntdoceil by
aqueous vapour.
In 1867 Janssen was sent by the Bureau des Longitude* to
Italy to observe the annular eclipse of the Sun^ his object being t<>
make careful comparison of the spectra of the limb and centre of
the Sun. As the light of the limb has to pass through a greater
thickness of the solar atmosphere, it was ex|>et^t<?d that the abaor(>tioii
nes there wouhl be strengtiiened, but the results obtaitied wore
arely negative*
In iS63 he was delegated by the Acadrmie des Sciences and
the Bureau des Longitudes to proceed to India to observe the total
solar eclif^se of August i8 in that year.
He was provided with four telescopes of 6 inches af»ertarc
with sjjectroscopes of different optical power, and he established
his oljservatory at (iunt^or. On mounting his instrnments lie
found that the case of spectroscopes had been carried off by
mistake and could not be available for the eel ipse, but bi*
foresight had provided one supplementary s()ectrosco|>e, which ww
all he had at his diisposal o\\ ihe critical day.
Feb, 1908. Eighty-eighth Annuul Getieral Meeling,
247
Seveml expeditiuns had been organised for this eclipse, for the
purpose of iiniking 8pt?ctro8cypic observations of the sokr promi-
nences. All were successful in observing bright lines in the
prominence spectra, and thtLs establishing their gaseous nature.
In his report on the eclif^se, Jansst^n wrote: "Pendant
l*obscnrite totaleje fus eitr^mement frappt- du vif L^clat ties raies
pro tube ran tielletj ; la pensf^e me vint aussit6t qtiil serait pnsaibre de '
Jes voir en dehors de^ eclipses," Pursuing this idea On August 19,
the day following the ecHpse, he succeed eil in making those
mvniomble and historic observations which gave astronomers the
new method of oljaervin*:? the solar prominences ^vithout the aid of
an eclipse. With the slit of the spectrost^ope placed radially, partly
on the Sun's disc and partly beyond, he swept a portion of the
limb, observing the C line. His words are: *M'utais depuia peu
de temps a n'tudier la region protuberantielle du bord occidental
quan*l j'nper^us totit k coup nne petite raie rouge, brilliante de i a
2 minutes de hauteur, formant le prolongement rigouretix de h\ nde
obscure C du spectre Sohiire. En fair^ant mouvoir la fente dti
»pectrosco[>e de manicre k balayer methodirjuement la rt-gion que
j'explorais, cette Jigne persistait^ mais elle se mofliliait dans sa
longueur et dans J'^clat de ses di verses parties, accusant ainsi une
gi-ande variabilite, dans la hauteur et le pouvoir Inmineux des
diverses rt^gioos de la protiibt'mnce.'*
Writing on Septeinber 6, 1868, he says: *'c*est le 19 aoUt
que j'tti fait cette decouvertc, aussi la veriiabU edipse a eu lieu
poar moi le 19 et non le 18. Depuis j'ai pu tracer jour par jour la
tigure, la place, la composition des protubi-rances du Soleil visibles
ii*eulenient jusqu'ici pendant les r'clijises, Je lis dans un livre
iernie jusqu'ici pour tons."
Janssen'ifi report, dated September 19, was read at the meeting
of the Academic des Sciencea on October 26, 1868, and immedi-
ately following it was read a communication from the present Sir
Norman Lockyer announcing his independent successful discovery
of the same njethod of viewing solar prominences without an
eclipse as that made by Janssen. The Acadeniie des Sciences
struck a medal in honour of the discovery, bearing the eriigie^ of
both ;istroDomera, and the eloquent words of M. Fayo on the
occasion may be fitly quoted : ** Mais an lieu de chercher a partager,
tt par conmjuent a aliaiblir le mi' rite de la drcouverte, ne vaut-il
pa« mieux en attribuer indistinctement Thonneur entier k ces deux
hoiDIXLes de science qui out eu si^pareuinrit, k plusieurs milliers de
liioea de distance, le bonheur d^aborder rintangible et Finvisible par
Itt Toie la plus ^tonnante peut-^tre que le genie de robservatiou ait
jamais con<,'ue t "
The new field thus o[wne<l for the study of Solar Physics at
once led the French Gt^vernment to consider the question of
e«tabJiahing a suitable physical obai^rvatory for Janssen. The
rjMH^tiuij was seriously dehiyed by the war, and it was not till
t 1874 that the Acad/nnie des Sciences could report on
the ^.j j^ct. A provisional « observatory was lirat esilab\\»\\ed nX
248
Eepori of th^ CaunifU ia the
LXTnL4,
Montmartre, but 4?veiitutilly it was decided tu utilise the Chiiteaudfl
Meudoii, where Jaiussen touk uj> lua residence in October 1S76,
111 tlie meantime Janasen had undertaken several solar eclipse
expeditions, in 1870, during the siege of Paris, he made his
memorable escape in a ballo^m to observe tLe eclipse of December 22
at Oran, where the weulher, however, prevented all observatioDs. In
iSyi he went to India and established himself in the Neilgbeiry
HtilR. He employed a specially constructed reflecting telescope,
tlie mirror of which was 15 inches diameter, and had a fo<:*al leDg:th
of on!y 56 inches, A direct vision s]>ectroscope of ten prisms wa*
employed. With the brilliant spectrum 8ucli an instrutnent gave
ho observeil some of the Fraunhofer lines in the continuous spec-
triim of the corona^ ami w«ts also able to determine that tho green
1 474 line in the curona was not visible in the spectrum of the
prominences. He alsti went to India to observe the eclipse of
1875 Api"!' 6,
In 1S74 he undertook an expedition to Japan to observe the
transit of Venus.
In order to secure a photograph of the actual geometrical cootaiei
he invented the "Revolver Photograpbique," an instrument which
takes a series of photographs at short intervals of time precisely on
the principle of the cinematograjdj, of which it is indeed the
forerunner.
It is from this period that those researches of Jansaen^s in
alar photography date which have culminrited in the remarkiiUe
^* Atlas dc Photographies Solaires," publisshed in 1903. At the
commencement of work at the Meudon Observatory, Janasen
erected a special instrument for photographing the solar surface.
It consisted of a telescope of 5 inches a pert tire, with a suitable
enlarging lens which allowed him to obtiuri an image of the Sun
from 12 to 18 inches diameter. In the optical construction of it
he titilised tlie fact that there exists in the spectrum* near the
Fraunhofer line G* a narrow band of rays which possess a photo-
graphic activity upon the salts of silver much more inten.se than
that of any other |>orti<^n of the Bpectrum ; no that if tbe exposure
be very short and properly regulated, the ellect is practically th€
same as if the sunlight were monochromatic, consisting of these
rays alone, and any defect in the correction for chromatic abernitiou
in the lens is rendered almost hsirmless. With this telesc4»pe, and
with exp«jsures so small a^ from yjuVir ^ n oa 0 ^* ^ second and even
less, Janssen obtained that marvellous delineation of the mht
surface which is so well known from the published results. He .
described all his methods in a very complete paper on tbe sabj>ct
in the Anmtaire du Buremi des Lomjifitiles for iSjg^ The Hint
significant diwcovery he was able to announce was that of tin
** Kcseau Photospherique/^ by wliich term he designated c^tda
hazy, smudg) patches in the granular surface of the photnii[i -^
which, in his opinion, showed continual agitation and ch^np' r
solar atmosphere. Employing this apparatus in phot<>
partm] eclipse of the Sun, he showed that not tbe slightest
Feb, 1908. Eitjhiy-eUjhth Annwil Gmurai Meeiituj,
249
iQ the solar jjratmles couKl be detected up to the limb of the Moon,
and by this most delicate test any evidence of the existence of a
lunar atmosphere was com|»hteIy negatived.
Though the Chateau de Meudon bad been in a great mea'sure
destroyed by the niege of Pari^, yet tl*e stables, nearly 100 inetrea
' iij, remained ihtiict, and wore formed by Jutjssen into a very
, ible laborattjry for the study of absorption spectra, the divisions
uf the stalls forming excellent supports to the lerigtf»y tubes he
employed.
Jules Jansaen was endowed wilh great energy, I'onrage, and
determiuatii)!^ which in no ca>4e are shown more c«)n>picuously
than in the ascents he made of Mount Blanc for the purpose of
m;iking spectroscopic observations in the in'gbpr strata of the
atmosphere. He made two ascents, in 1893 and 1S95. His
lameness prev4*nted him from walking, and consequently he was
carrieti by jKirterH from Cbamounix to the summit^ — a quite unique
performance. But this enabled \\\m to arrive at that high altitude
with a raind and body onweuried hy physical exertion, and thus
able to devote himself under the most favourable circumstances
to the observations he propoaed to make, and also to plan out an
observatory on the summit One of Ids principal ohj*icts was to
determine the presence or not of oxygen in thn Sun, He ac-'ordingly
made his a^^cent in winter, bo that the inlkience of aqueous vapour
in the atmosphere might be at a minimum. His observiitians
negatived the existence of oxygen in the solar atmosphere, though
recent observations ai-e of a niore fiositive character.
His unwearied activity throughout his life is shown by the
oameroQs contributions to the Compter Rendim^ the Annul e& de
Chimf^, and many other scienlidc publications.
In 1873 Jans'^en wms elected a member of the Academie des
♦Sci'^noes and the Bureau dea Longitudes. In 1875 he became
a Foreign Member of the Royal Society, who in 1877 gavp him
the Rumford MedaL The Academies <d Rome, St Petersburg,
Edinburgh, Brussels, and Washington did honour to him by electing
him as one of their corresponding members.
A cold cAUght last I>ecami>er developed into congestion of the
lungs, from which he died on the 23rd of that mouthy leaving a
devoted wife and daughter to mourn the loss of one who will
always rank as one of the most eminent scientific men of hts
country. He was elected an Associate 1872 Nov, 8. e. b. k.
Maukick Loewy was born of Jewish paretita at Vienna on
April 15, 1833. He was educated at the Polytechnic School
and at the University of Vienna, and received his astronomical
training «t the Imperial Obse^vat^l^y under the directorship of von
ijUrnw, Hbi first contribution t^ astronomical literature is in the
herichle of the Vienna Academy for April 16, 1S57, and
of a determination of the elements of the niintir planet
i«isda then just lUscovered. Oth+^r computations of a flimilar
.eluding one of the elements of Don^itV^ *iom^\.
2S0
Report of the CauncU to tht
LXTIJL4t
In August tS6o li« accepted an invitation of Lo Verriei^s to
the Paris Observatory, ivnd m the volume of Paris obaer^ations for
1861 the initials M. L. are frequently found against the observa-
tions made with the nieridmn circles, the circle of Gamhey, and
the equatorials. In 1S64 he became nataralised, and in 1870
served hk adopted ecu o try on the ramparts of Paiis.
His interest in minor planets and comets continued. In
particular he made several inventigatioDB of the orbit of Eugenia,
alluwin^s' fur the perturbations. In 1872 he published & theciretied
paper for simplify tug and expediting the computation of orbits^ with
a number ot subsidiary tables.
M. Loewy*s attention, as was to be expected in «o skilful an
observer, was attracted to the details of the meridian circle* Bf
means of an optical apparatus in the central cube be devised %
methoil of determining the tleiure of the telescope at various zenith
distance^t. With the same apparatus he was able to investigate
the errors of the pivots, Jle also developed a method of oboervation
of cIo.se polar stars at various points in their circular paths, which
he applied to various problems of fundamental astronomy, such as
the determination of latitude without using the declinations of
fundamental stars^ and the determinatiou of right ascensions with.
out relying on the right ascensions of the circumpolar at^rs. This
interet»t in the details of meridian work continued to the eud of hi^
life, a paper which he passed for press shortly before his death
being an account of a new method he hod devised for determiaiiig
the errors of a divided circle.
In 187 1 M. Loewy prepared his new form of equatorial, to
which the name of *' Eijuatc^rial Coudc " was given* Delaunay^ who
was at th.'it time Director of the obftervatory* was much impn?ssM?d
by the possibililies of this form of instrument, but owing to his
ileath the project of constructing; one was not carried out. The
tirst instrument of this type was completed in 1882, and bad an
objectr-ghiaa of 10 J inches. This form of mounting is uow so welJ
known that it is not necessary to say more than that by reflection
at two plane mirrors light from any part of the *ky is directed into
a fixed direction— that of the polar axis. The inconveniences whieh
an observer with an etiuatorial must put up with are avoided. The
observer can direct the instrument to any object without roovtsg
from his chair, and his observations are made under the nio»t
favourable conditions for his own comfort, similar to those unrfcr
which the microscope is used by the student of natural history.*
The p«jftsible drawbacks of this form of mounting are the loss of
li^ht at the two reflections and the possible flexure of the mirrors.
The latter was avoided by making the mirrors tliicker than vras
usual at that time. The performance of the cou.le in the separation
of douide stars, and still more in the beautiful aeries of photograpb*
of the Moon taken by Lo<*wy and I*uiseux, shows that the definitioo
does not siifTiT sppreeiably by the two reflections.
• See Address -iBlivifrf'tl by the Presidnnt, Mr. W, H. M. Chtutie, o"
presenting thp Gold Medal oC the Society to U. L««wy, M.N,, vol, fXix* p. U^*
Feb. 1908. Mighty-eighik Amnuil General Meeting.
251
M. Loewy'a method of determining the coostant of aberration is
developed in a series of pfij^er^ to the Acadeniy of Sciences Id the
year» 18S6 and 1887. The peculiar liability of this constant
to be affected by systematic error in the observation 8 makes the
dtlTerential method devised l>y ^f. Loewy of special value. By
the ingenious device of a double mirror formed by silvering two
faces of a prium placed in front of the object4,dai*8, and capable of
rotatioQ about the axis of the telescope, be wa«i able to view
simultaneously two stars in widely dilfereut jjarts of tbe sky. The
dietaiice between two simh stars is affected by aberration, and by
olKserving this distance when the stars are at ihe same altitude^ and
ftgain, three months later, when they are in the same position, a
determination of the couHtant is obtained. The advantages of the
method are that a comparatively large coefficient is involved^ that
errors *lue to precession and nutation are absolutely eliniinated,
and those due to refraction reduced to a niiiHmum. By varying
ibe conditions the stime method of observation can be applied to
determine the refraction, and it was for this purpcise the instni-
m<*nt was oiiginnlly const ructecL The coaipleLe theory of the
' »strument, including the effect of temperdture, change in the
sition of the axis round wluch the double mirror turne^ the most
nitable anu'le of the prisfu, and the choice of stars, are all carefully
alt with by M, Loewy, His theoretieal conclusions as to the
edom of the instrument from Bystematic error were justified by
tperience ; and though tbe results wliicb were anticipated have not
Ben realised as yet, the metliod constituted a new departure of
eat viilue. In this instrument, as well as in the er|uatonal coud^,
Li>ewy bos placed at our disposal method» of observation based
entirely new principles, and calculated to give astronomers
improved and quite independent means uf attacking several of the
itt important problems in our.science.*
M. Loewy waa elected a member of tbe Academy of 8cien<!e8 in
J73, succeeding Delaunay. In the previrnis year b*^ had been
appcuMted a member of the Bureau of Longitudes. With Admiral
'[oucbez he instituted the Observatory of tbe Bureau of Lnngitudea
the Park Montsouris for the instruction of sailors and exftlorers.
be deterMUnation of the difference of biugitude between Puna and
be cities of Bedin, Vienna, Algiers, and Marseilles are his own
|i«onal contributions to tieodetic Astronorav. For thirty years he
_ iited the Connav<^ance des Tern pa and tlie astronomical jiartof the
AnnwUTP cfu Bureau dm Iym<ji(udf*s.
In 1878, when Admiral Mouchez became Director of the obser-
atory, M. Loewy was made Assistant Director, and he held the same
sition under Tisserand whom he succeeded ag r>irect<:ir in 1896,
Paring this time the project for the International Phr»tngraphic
Chart and Catalogue of the Heavetis totik shape, a project to which
the Paria Observatory contributed the optical ?*kdl of the brothers
Henry and the omanising abdity of Admiral Mouchea;. M. Loewy
• See Address d^livotvd by the President, Mr, W. H, lit, CVvmXxt, (ja
XWiimfiin; tin Gold Medal of the Society to M, Loewy, MM.^ vo\. xV\x. v-M"^^
252
Report of the CmcncU to tlie
interested himself in tbjB details of this work from tbe start, and
conducted researches on the l>e8t methods of measurement of the
plates, and the derivation from the measures of the accurate posi-
tions of the stars. He also concerned himself with the reproduc-
tion of the chart pktes, and inaugurated the pubHcation on papier
of enlarged copies of the original negatives. In his later years
the two pieces of work to which he devoted greatest attention
were the photographic atlas of the Moon, and the organisation and
execution of the observations of Eros for the determination of the
solar parallax. The photographs of the Moon, taken in collabora-
tion with M. Puiseux, are of the greatest beauty and value. The
coudb telescope being of long focus, gave an image of the Moon on
a large scale, and this was subsequently further enlarged. An
immense amount of care and labour was required to obtain photo-
gmphs with such fine definition, not above one plate in ten, though
taken in apptirently good atmospheric conditions, being considered
by the critical authors as sufficiently good for puhlication. This
atlas gives a permanent record of the minutest details of the Moon
at the present epoch ; and should any changes occur, they wil) be
detticted by comparison of photographs taken in the future with
those contained in the atlas of Loewy and Pniseux, "
The Eros campaign, which was decided upon by the Asi
graphic Conference which met at Paris in 1900, brought a large
amount of work, which he did not in the least shirk, upon M,
Loewy. He undertook and carried out the preparation of epheme-
rides, the selection of reference stars, and the collection and
publication of the results obtained at the different observatories.
At the same time he obtained results of the highest degree of
accuracy from the photographs taken at tlie observatory which he
directed. He made extensive inyestigations of the precision which
could be obtained by repeating the measures under different
conditions ; and if he erred at all, it was in having the plates
measured with more care rather than with less than they required,
M Loewy was a corresponding member of the Academies of
St Petersburg, Vienna^ Berlin, Eome, and Washington, He re-
ceived the Gold Medal of the Roynl Astronomical Society in 1S89
for his invention of the equatorial coude and his method of
determining the constant of aberration. Tbe conferences at Paris
brought him in contact with astronomers from all countries. All
who met him were impressed by his kindly disposition and his
zeal for his work,
M. Loewy died suddenly on October 1 5 while speaking at »»
meeting of the Council of the French Observatories, He leaves a
widow, two sons and four daughters. He waa elected an Associate
of the Society 1S86 November 12, F, w, o.
M* Charlks Tri&pied, Director of the Algiers Observatory, diotJ
fluddenly on 1907 June lo^ a few days after hia return from the
Confirence IniernaHonale des Mtude» Solaimn held at Meudon in
M&y last On eclipse expeditions, at the successive meetings 1
leb. 1908. Eighiy-cighth Annual Geiural Meeting.
253
1 hs
, cull
ke international conferetices for tlie execuiton of the Astrogtaphic
Jhiirt and Catalogue, aud at the reroiit Meudon conference?, be
had made many friends among Ejiglisli astronomers, who would
fWish to join in the tribute paid by the late Monsieur Loewy to
the high qualities of heart and mind which gained him *'leB
sympathies de tnus ceux qtii avaient eu Tocca^ion de I'approcher,
chaude ami tie de tons cenx qui avaient eu le |}rivik'ge de vivre
ans «oii intimity/*
Born in 1 844^ M, Tr^pied was associated early in hia acieatitic
<;ftreer with the Bureau de^ Longitudes and its observatory at
Montsouris, and he was nominnted a member of the Bureau in
1877. About this time the French Government was activ^ely
«rijija^ed in the orgunisation and equipment of the six ObHervatoires
asironomiques d& province^ and in 1880 they confided to M. Trepied
lie directorship of the Algiers Observatory, with the task of
^»!-creating it upon a new site. The annual reports to the Ministry
of Public Instruction fri»m 1880 ti> 1896 give a very interesting
account of the enterprise, Starting with inadequate instruments
and a small budget which allowed only one assistant, M. Trepied
I devoted himself at first to the observation of the places of the Moon
I and of moon-culminating stars, and to solar spectroscopy. In
^« ^882 be travelled to Egypt to observe at 8ohag the total eclipse of
^Mhort duration in wliicli *Mes astronomer anglais, it^aliens, et fran^^ais
^bvaient reaolus de partager fraternellement les op«5 rat ions.*'
^H In 1885 the Algiers Observatory was transferred to Bouzareah
^^on a height overlooking the city, and in the course of a few years it
was equipped with a new meridian circle, equatorial coude, and
I astrographic telescope. The volumes of the CompfeA Eendus bear
continual testimony to the activity of the observatt»ry 00 many
sides: its most conspicuous enterprises include a zone of the
Southern A.G. Catalogue, a zone of the Astrographic Chart and
Catalogue, and a very considerable share in the pliotographic
obeervations of Eros.
In 1900, when the line of totality passed over his observatory,
and again in 1905, when it passed over Guelma, M. Trepied earned
the gratitude of several Britisli eclipse observers by his whole-
: liearted devotion to their help. And the same kindly qualities
rhich were so conspicuous on tlicBc occasions iiiade him the man
whom was naturally thrust the burden fpf acting as 8et:retary
r«Tery meeting of the Astrographic Conference ; to the Conference
Directors of National Ephenierides which met at Paris in 1896 ;
the Meudon Conference of 1907 ; and to many others. In this
sition he was able on many occasions to exercise his power of
olite but acute criticism* ** La regie est prt'cise ; cependant il est
»e de voir que la precision est t-oute dans les termes, non dans le
^TOud/* was his verdict upon the resolution which bound the
obaenratories to get fourteenth magnitude stars upon their charts
at a date when there was even less possibility of defining exactly
the fourteenth photographic magnitude than there is now,
LA like elegance distinguished hia mathematical luv^V\^'al\0tL^
Report of the Council to tht
LXVII14,
hi geodeny, where be extended Legend re's theorems on the trett
meut of large spherical triangles ; in celestial dynamics j and
especirtlly in the theory of precise celestial photography, to which be
contributed formulse of great generality, and at the same time j
convenience.
The tintimely deatli cif M. Tropied i^ one of the heaviest of
great misfortunes which have robbed France within the last fe
years of nearly all the men who bore so distinguished a part in tl
inception ami development of the great enterprises in whid
French astronomy ha» been involved.
He wa8 elected an ARsoeiate of the Society 1901 November 8.
A. K. H.
/
Hermakn Carl Vogel, the anuonncement of who&e death
August 13, T907, was everywhere received with profound re^trr
will always occupy a high pi nee in the history of aetronomy a^ oil
of the fHoneers in the new fields of inquiry opened up by it
application of the spectroscope to the study of the heavenly bodia
He was born at Leipzig on April 3, 1841, and, while yet a stude
at the university, was appointed as assistant at the ohserratory J
that city in 1865. During the preceding three years a gn
inipctna was given to spectroscopic astronomy by the strikio
results which had been obtained by Kutlierfurd in America, Seccbi
in Italy, and Hnggins in England, and there can be little donbt that
at this tiuie Vogel was especially attracted by the great possibilitit^tj
which thf work of these observers suggested. He was probably still
further inHuenced at a little later stage by the discovery of the
melhod of ohi^erviug solar prominences witliout an eclipse whifi
was made by Lockyer and Jansien in 1868, and by the till
researches of Huggins on the movements of stars in the lin«^-of-sigli
At all events, after taking his degree in 1867, we find him to hull
been actively engaged \y\t\\ Zollner in 1869 in the observatinn i
Bolar proiiiincm ts, and from this time to his death hts energies W6
chiefly directed along astro (vhysical lines of research.
The rect>rd of Vogel's work at the private* observatory found
by von lUilow at iSothkamp, of which he was in charge from 1S7
to 1874, is the best possible testimony to his great skill and iiidusU
in tln^ earlier part of his careor, Fr^m the well known pulJication
of thn obi^ervjitory during this period we see that his outlook
already a wide one ; tlie sf*ectra of the Aurora, the Zodiacal Li^
and lightnihg received his careful attention, no less than those <
the Snn, etars^ star clusten*, nebulie, comets, and pl»net8. For tlid
observations he employed a spectroscope which he had speeidlj
designed to secure the stability which is essential to useful work \
the motions of the stars, and for the determination of wave-lengtl
with reasonable accuracy. The results of some of these observatio
have naturally been superseded by otliers which have since
made with more powerful instruments, but they were of the highei
order for the period, and A^ogel was himself always among the firt
to devise and employ impto^sid m^lhcdR of observation^
Feb. 1908. Eigldy-eighth Annual General Meeting.
25s
V Among tlie more notable of VogeFs achievements at Bothkamp
were the spectroscopic deterioination of the San's rotalicm, and his
elai^ical work ou the appctra of planets. Emplo3'inf^ a *^ reversion
spectroscope'* of the form des^igned by Zullner, he indeeil obtained
the first spectroscopic proof of the vSun's rotation bj the o pi jo site dis*
placement of the .solar hnes at the east and west limbs, and at the
same time estahliah^^d the tmth of the Doppler principle «»n which
the determination of velocities is based.
The BUccessful work at Bothkamp, in conjunction with that of
Spdrer, was chiefly instrumental in seen ring the foundation by the
Prussian Government of the present Aatroiihysical Observatury at
Potsdam, the erection of which was commenced in 1874. Vogel
w^as immediately appointed a.*? an observer^ and, in 1882, on the
observatory passing from the control of the commission at first in
charge of the work, he was promoted to the responsible post of
Diref'tor. It i.s generally acknowledged that his administration of
this important observatory^ intended for the advanct^ment of what
was practically a new science, and bound by no traditions, has
been completely successful in establishing and maintaining a high
fndard ol accuracy in all its tiimiyrona undertaking*;.
Vogel early recognised the importance of preparing a spectro-
scopic catalogue of the stars on a more extensive scale than bad
been previously attempted, and, with the assiKtanceof I Jr. Mlillcr, in
the years 1880 to 1882, be catalogued the spectra of all the stars
down to magnitude 75 in the zone - i' tcj + 20", the total number
amounting to 4051* The classification adopted was that proposed
by Vogel in 1874, being an extension of Seccbt's system, and
definitely introducing ZollnerV idea that the difl'erent spectra
exhibited by the stars depend upon the temperatures which they
have reached in a general evolutionary process. In 1895 this
classification was further extended ro as to take account of the
additional features revealed by |>hotographic spectra; and though
oot universally adopted in detail, lU leading principle is embodied
in other classifications w*hich have been put forward.
^Xo material advance in the investigation of stellar motions Ava*<
de until the introduction of the pliotogmphic method by Vogel
at Potsdam in 1887. The varion.s sources of error which were
liable to influence the minute displacements of the lines were
thoroughly investigated, and during the next lliree years the
labours of Vogel and *Scheiner set this department of astrophysics
on a firm foundation. The results were cooaistent and accurate
to an unexpected degree^ as was shown by the agrr»enient between
the displacements found in the sfiectra of the Sun and Venus with
tho9e resulting from direct calculation. The velocities of 51
aiars thus determined were published in 1892 (see M.N,, vol lii,
pp, 87 and 541), und an important deduction was that the average
line -of -sight velocity — 1 6*5 kilometres per second — was much
imaller than had been previously supposed.
Two res^ults (if special interest followed from tW ft\ifte\.xci*
ipbic work during this period, namely, the we\Wi\QN«JTi eoiv-
256
Rep(fri of the ComicU to the
Lxvm.
er MF
firnLation of Gocidricke's explanation of the variability of Algol\
periodic eclipses produced by a revolving dark com pinion, and tbe
discovery that Spiiia is a similar system in which the plane of
revolution does not pass through the Sun, The interesting fact*
relating to the dimensions and masses of these systems have passed
into the general literature of astronomy and need no further
comment, except to lecall that, accuniing to Campbell, no less than
one in seven of the stars which have been sufficiently observed
have since been found to be similarly accompanied by relatively
dark bodies. The provision for such investigations at Potsdam wa*
greatly augmented in 1S99 by the erection of a telescope of 31J-
inclies aperture ; and though VogePs health failed in the
following, the work has been energetically carried on with ma
success.
Dr. VogeFfi name is associated with other piecps of work of 1
inaj4ni tilde which have been carrried out at Potsdam under
superintendence. He took an importarit part in the initiation of
the International Chart of the Heavens in 1S87, and undertook
the zone +31* to +40' as the Potsdam contribution to this great
work. He did not live to see the completion of this task, but all
the necessiiry photographs have been secured and four volumes of
reitulta have been published.
Another notahle undertaking at Potsdam was the precise
photometric determination of the brightnesses of all the stars not
recorded as fainter than magnitude 75 in Argelander's Durc}\r
jntt^fernnfj. In the cBi>able hands of l)t)ctors Midler and Kempf
this has been brought to a successful conelu.sion, and is characterised
throughout by the extreme care which has been Uikeu to secure the
greatest possible accuracy. The General (Catalogue, issued in 1907,
refers to no les,'* than 14,199 stars.
Dr. Vogel also made valuaVile contributions to our knowledge
by his careful studies of ** New Stars/' and by his investigations of
the absorption of the solar atmosphere for light of diflferent wave-
lengths, Mi.'ution may also be made of an important series of
observations of the positions of nebulffi and clusters which he made
at Leipzig, with a special view to their future use in the inves-
tigation of possible changes.
No less than nineteen learned societies in various parts of the
world showed their appreciation of Dr, Vogel's services to science by
electing him as ]H»noniry member, and, in addition, he wasawanled
the Gold Medal ttf the iJaiiiah Academy in 1874, the Vali Prhe
of the Paris Academy in 1891, the Henry Draper Gold Medal of
the U.S. National Academy of Sciences in 1S92, the Gold Medal
of the Royal Astronomical Society in 1893, and the Bruce Gold
Medal of the Astronomical Society of the Pacitic in 1905. In
1895 he received the honour of the Prussian Order of Merit,
was nominated Privy Councillor of Germany four years later.
This brief notice of a great career cannot be more fittingly
closed than by quoting some of the conchiding remarks made by
Mr, Knobel on the preaenl&lion o^ l\i^'^w"\^\.Y%^Q>Vi Medal to Dn
Febi 1908. Eighty-eighth Annual Oeneral Meeting. 257
Vogel in 1893: "It is a record of unwearyiog perseverance to
acoomplish great work ; moreover it is the chronicle of a masterly
attainment of snccess. .. . . Not only is astronomy enriched by a
seriaa of iuyestigations of the greatest value, but a distinct, and
indeed marvellous^ advance b made in our knowledge and concep-
tion of the stellar universe."
He was elected an Associate of the Society 1882 November 10.
A. p.
258
Report of the CouncU t& the
LXV1IL4,
PhoCEEDINOS op 0BSB»VATOaiS8«
Royal Ob$ervaiortf, Greenwich.
{Director^ Sir William Christie^ K,C.B.^ Astronomer Rot/al^)
Transit'Ctrde^ — During the year 8648 observations of transita
and 7877 of Tneridiaii zenith distance* have been ubtaioed. The
Sun has been obnerved 167 times and the Mnon 107 tiniea. The
lunar crater Masting A has also been observed 55 times. There
have alwo been observe^l 262 reflexion observalions of stars.
The reductions for the Second Nine Year Catahigue for 1900
are nearly completed and the copy for press ib nearly ready,
AlicLzimuth, — This instrument has been used, as before, as a
meridian transit instrument during the second and third quarteit
of the lunation, for the ubservntion of the Sun^ Moon, planets, and
the stars in Newcomh's Furtdii mental Catalogue, The instrument
is reversed every Xwn months, altBniately by reversing in its Ya,
and by turning the instrument through 180* of azimuth.
The total number of nieridian transits obtained during the
year is 1192, including 77 of the Moon's limbs and 45 of the
lunar crater Moisting A. The number of extra-meridian obaer^i*
tions of the Moon obtained during her first and kat quarters is 27.
A new method of illuminating the field was introduced in June*
The small prism cemented to the centre of the object-glass reflecting
the light of an electrie Ump placed at one side of the glass wft«
replaced by an ellipticiil re Hector with a matt surface of opal gla^*
cemented in the same position, making an angle of 45* with the
object-f(liiS3 ; the minor axis i>f the ellipse is i'5 inches, the major
axis J 2 times this. This gives uniform illumination over tbi
held, and the wires are much better defined, the small pencil of
light from the prism having given rise to diffraction effects.
Kt^flfi^r zeiiitJi tube. — During the year 1638 double observationi
and 37 single observations have been obtained, y Draconis wm
observed on 80 days^ 0 Draconis on 57 days, and t^Cygni on 48
days.
It is proiK^sed to discuss the observations of the year 190J to
1907 together, for detenni nation of the mean places of the stars
and the variation of latitude,
Occultations, — During the year 28 disappearances and 2 re-
appearances of stars occulted by the Moon have been observed by
one or more observers. The results have already been com-
municated to the Society.
3S'i7irJi li^/ractor. — The working catalogue of doulile stars vt%s
that brought into use in 1906. This catalogue contains ail the
G. W. Hough atiirs, about 500, within the working zone, and a
Hum her of miscellaneoviR paiira.
Feb. 1908, Eighty -eighth Annual General Meeting,
259
Aa analysis of the observations gives —
r;. IK Hough Stan,
18 under 0*5 separation
20 between 0*5 and i"*o
90 over 2 'o separation -
Miscellafieous Stars.
56 under 0*5 se|iaration
52 between 0*5 and i^'o
54 ,» 1*0 „ 2'o
91 over 2'o separation
Of the 500 Hough stars within the limit of decllDation, 325 have
been measured in 1906 and 1907.
K TB!gM was observed on 15 nights, S E^^uuki on 15 nights, and
70 Opbiuchi on 1 6 nights in 1907.
The eqaatorial and polar diameters of Jtipiter were measured on
13 nights with the bi-Mlar micrometer, and also with the dotible-
imaf^e micro meter.
lliompmn EquatoriaL — With the 26inch refractor the follow-
ing photographs have been obtained : —
Keptane and Satellite, 42 photographs on
Jnpiter for position, 11 ,,
Saturn ,, 27 „
Mars ,, 8
18 nights,
5 ».
With the 50-inch reflector the following photographs have been
obtAined : —
photographs on 13 nights.
/ vi. Opposition,
1906-
-7»
25
in 1907,
8
J mi. „
1906-
-7t
7
in 1907,
3
Haturn ix, Phosht^
16
Comet d 1906,
I
g 1906,
I
d 1907,
15
e 1907,
1 2
6
11
4
3
16
I
I
13
8
In addition to the pbotographa of Comet d 1907 mentioned
above, 17 photographs with k>ng exposure for the tail were taken^
several of which are of ^reat interest.
104 photographs of 38 minur planets were also obtained. These
photographs were all taken for determination of position.
Bet* ides these, 3 long exposnrefi were made in an an successful
aearch for Halley'a Comet, and a few others for m&\it\iiaftii\aX
adjm^tments.
^m m
26o
Bq^art of the Council to the
LXTrn.4,
A3 regards the meaBurement of photographs and r&dnction% —
The pbotogra^hs ef Keptune and Satellite are measured and
discussed as fur hb the end of the last oppnBitioUt and the ret^ults
published. The photographs of J vi, and J viL for the opposition
1906-7 ; Saturn ix. Pkwhe 1907 ; the photographs of Jupiter and
Saturn fnr |io»itions ; Cometis d 1906, e 1906, (j 1906, d 1907,
and the minor planets photographed in 1905 and 1906, have
all been measured and publiBhed. The measures of minor planito
photographed in 1907 are in band,
A$trographic Equatoricd,—V^ otk with this in^ttrunient bu^
still mainly been confined to replacing chart plates, which, though
satisfactory in other respects, are» owing to slight photographic
defects, unsuitable for production of enlarged prints* iJuring the
yaar, 164 chart plates^ 7 catalogue plate?, 5 of the field round
Saturn, 3 of the Pleiades, 8 of minor i>lanets, and 4 of Comet 1/
1907 were taken. K)l the chart plates, 72 were rejected, jj of them
because the exposure waa interrupted by cloud, or because tbej
did not come up to the standard in showing faint stars; the large
nimiber of other rejections is due partly to an accident to the
TL'seau printing frame, on aceoynt of which the reseau lines were
printed askew on the plates.
Apart from the long exposure plates, the main work of the
branch during the year has been the comi>utation of constants for
the plates which form the catalogue. IStandard co-ordinatea deduced
from the places of the reference stars in the Greenwich Second
Nine Year Catalogue 1900, now in course of preparation, have been
compiittid for the plates of the zones declination 72' to 75" tnd
81* to 86 ^ The scale value and orientation having been coinpuk^
for these [>lates, and a menn *icale value adi>i>ted for the whule
series, iinal adopted constants were computed for all the plat4!«of
the zones 72' to the pole» 645 in all.
These constants are included in the Introduction to volume «•
of the Greenwich Astrogruphic Catalugue, which has been prepar^i
during the year and is in type* Thii* volume will be distributed
shortly. The recomputation of the constants of the plates io
volumes i., with standard co-ortliuates deduced from the final plac«*
of the reference stars in the Greenwich Catalogut^ above mentioned,
has been begun. The computtition of scale value and orientatiofl
ol the ao4 plates in zones 69* to 71' is completed.
Enlarged reproductions of 206 chart plates have been made
during the year. The total reproduced to December 31 is 744f
the ten zones 65^ to 74* being complete, and more than a qnarter
of the foi^r zones 75* to 78',
P'AofoAe^ioi^mp/^^Phofcographs of the Sun have been taken oe
214 days during the year 1907, the Thompson photoheliofjnrb
of 9 inches aperture having been used alone on 206 day^ the
Dallmeyer photoheliograph of 4 inches aperture alone on 5 dapt
and both instruments on 5 days. Of the jihotographs taken, 4S6
have been selected lor preser\'ation, including 16 with double imigc*
0/ the Sun for determiivat'uvn o( the zero of poaition of the wir««»
F^lx 1908, Eighty-eighth Annttal General Meeting.
261
Fl^otographs have been received through the Solar Physics Com-
mittee from Dehra Dun, India, up to 1907 December 25, and these
have been further suppltjmeDted by photo;^rapbs from the Observa-
tory at Kodaikanal, India, and fri>m the Royal Alfred Observatory,
Mauritiufi, The daily rect>rd thus made up is complete, for the
ye&r 1907, up to 1907 December 25, the date of the last pbotogmph
received from Dehra Dfm. The last photograph received from
KcKinikanal is dated 1907 August 12^ and the last from Mauritius
1907 January 26. The photographs taken at Greenwich have
l>eeii measured up to 1907 May 21, those from Dehra Dfm up to
the end of May, those from Kotlaikjftnal anil from Mauritius as
fir as they have yet been received.
The atdar activity throughout 1907 has shown no diminution
*^ compared with the previous yetir, the months of Jauuary and
February being indeed two of the most ailive during the whole of
the present maximum. The work of measuremeBt and reduction,
therefore^ stiiJ continues to be very heavy.
The copy for press of the photoheliographic results for 1906
^ Complete for the daily record, and is in the hands of the printer
** far as the end of June, The t^opy fur press of the sun-npot
^wlger 18 oearly ready.
During the past year the volume of supplementary photo-
neliograi>hic results, 1874 to 1885^ has l>een complet^^d and
ptthlished. The ledgers of the 8pot-groui>s, and the computation
of the areas of spots and facuitt! as *^ projected,*' as well as corrected
w foreshortening^ are therefore now complete from the beginning
of the (Greenwich photogmphic record of the state of the solar
mrface.
Printing, — The copies of the volume of Greenwich Obaervatiotis
tot 1^05 were distributed in July 1907. The Heliographic Results
'^74 to J8S5 have been prinledi and will be distributed with the
wooud volume of the Astrographic Catalogue and the Measures of
PHotographs of Eros for determination of tlie Solar Parallax, which
[ite just on the point of completion. The printing of the 1906
Oiiawvaiions is in progress.
At the request of the Hydrographer, Captain Monro, B.N., and
Ueuuinatit Gibson^ R.N., were attached to the observatory from
^"^Jtember t6 to October 14 to practise observattona with one of
^^ portable transits, in view of a determination of the longitude
"f the Island of Ascension, and indirectly of the Cape Observatory,
^ He made in February.
Royal Observatory^ Cape of Good Hope,
{Director, Mr. S. & Hough, H.M, Adronomm\)
After twenty-eight years' service as H3L Astronomer, Sir
^^ Qill retired from the observatory on February 20, and
*** succeeded by Mr, S. S. Hough, Chief ^Issistant. The vaGQ.iic^
^ ttie staff thus created was subsequently filled by the appomtmftTvX,
262
Report of the Council to the
unmt^
of Dr. J, K. K llalm, of the Royal Observatory, Edinburgh, to
the post of Chief AssiaUnt, who arrived at the Cape on July i.
'I ramit-Cirdes, — The new reversible transit-circle bas been tn
use throughout the year, principally in observations of the list of
fundamental stars commenced in January 1905. To this list were
added n number of circumiiolar stars^ and throughout the winter
months consecutive transits of the ktter* above and belo^v pol«^
were observed as frequently as circumatancea permitted. The
nietliod of ob swerving employed has been the Repaold-Struve method,
with travelliii;; wire driven by hand.
The discussion of the observations of circumpolars in conjunction
with the observations for azimuth determination iu the preceding
years, while exhibiting unmistakable evidence of the stabdity of
the as^iiiiuth marks, indicated a significant and app^^rently tncreaaiiig
discordance between the jizitnnth di^tf»rrai nations made with OUmp
East and those mudt^ with Clamp West. Attempts to account for
these discordances led to the detection of a slight mechanical dt?fect
in the endheariug of the micrometer-screw, which has noi^ b««n
rectified, 8inca SeptemlMir 13, observations have been directe«i ta
the further testing of the instrument under its altered condilioii,
and to the iletermination of the personality of obeervers in obaerriag
elow-movinv; circum polar atars^ Theae observations appear to
itidicale tlnit thti defects previously shown have now been completeff
Filmed led. Regular nbservation of the Sim and minor planetehifo
been made throughout the year.
The idd trausiMircle lias been employed in observing mii-
cellaueous sUrs u«ed in conn<^ctioii with the Geodetic Survey rf
S. Africa, those of which occuUations have been observed, or of
which pliices were required for various purposes.
Tlip total number of observaliona secured with both inatnimenta
was as follows: —
Observations of Right Ascension: —
Number of observations ^ ^
\ night
ColHiuation by collimators , » 70
», reflexion and reversal 36
Level ,.,.,. 807
N. Azimuth Mark . , . 973
S. Azimuth Mark . . . * 1 006
R«veT«ibloT,a S-in T.a
726
. 5226 1788
52
121
Observations of Zenith Distance: —
Number of observations I .Vi.
1 night
Zenith Distiince of N, Mark
S.
Runs . . , . .
Nadir , . , . ,
Flexure , . ^ .
726
4155
1023
214
214
716
81
80
51
M
Feb, 1908. Eighiy-eightk Annual General MeeMmj,
263
Id each case the day observations include observations of the
Bun taken on 1 16 days, obiiervatit»ria i)f Yenus on 89 dnys^ and of
3tlercury on 55 day». The lunar crater Mosting A htis been
/observed on 13 nights with the old transit-circle and on 31 nights
with the new transit-circle.
Hdiometer. — The systematic observation of the major planets
the time of apposition Inu been continued and the following
oltterTations secured : —
Op^oaitton of Neptune {1907)
40 obs. on 5
„ Mars
50 n 7
„ Uranus ,
44 » 7
H 11 Saturn .
45 i» 6
P „ Neptune (1908)* .
11 H 2
In connection with the triani^ulation of the compurison stars
U8ed fi»r the planetary obaervations, 478 measures of distance have
beeo marie during the year, and the following zodiaca] areas have
now been completely triangulated 1 —
K«crie of TrifttiguUtion.
Jupiter 1904 . . . , .
•^cpiier 1905
%tti»e 1S97-1908, Jupiter 1906 .
^Tsi899
^^ 1901 . .
%ttr 1898, Mtrs 1903
JfypitCT 1899 .
***f* 1905
^fiiuis 1898-1907, Sutuni [
1^92^1901^ Jupiter 1900, i9ot |
^•*»«ii 1902 . . . . ,
^tttrn 1903, 1904, Jupitar 1902 .
^'*piter 1903 .
JJmiU of R.A,
li III h III
I 28 to I 43
J 49
5 19
7 54
10 It
12 14
14 S
14 43
'5 47
19 40
20 24
23 10
4 10
7 4
5 22
10 41
12 45
14 23
15 15
19 8
19 55
21-34
23 30
LiniiU oT Di-
f 6 12 to -Mo 21
+ 17 54 +21 2
-f-20 15
+ 23 16
+ 13 7
- 2 8
-!2 55
-18 59
-25 7
-22 29
-21 14
- 7 30
+ 25 12
+ 25 49
4-17 15
+ I 6
-ri 13
-15 37
-18 13
r9 28
-14 42
- 4 30
During the transit of Mercury of November 14 a series of
^etsnwid of the diHtances of Meri^nry from the iSun's limba^
^ttilirising in all 48 pointing.^, were socureeJ, and in connection
^rewith observations of 5 standard pairs fur the determination of
''^trumental corrections were made ou 3 nights.
The VicUiria Telescope. — ^'I'his instrument has been almost
*»clusively used throughout the year in the photography of stellar
t
• Still UDder observation*
a64 Report of the Council to the Lxvni4,
spectra for the determination of radial velocities and the solw
parallax. The instrument was in use on 103 nighta, and ly
plates of the spectra of iS stars were secnred. 246 stellar apectra
have been measured, mainly in connection with the determination
of solar parallax.
The mdial velocities of the following atara, specially aelectcd fof
the determination of solar parallax, are completely reduced aud
await final discussion : —
25 plates covering 3 quadrature&
ji 3 »»
11 5 ft
» 3 i»
it S I*
»i 5 If
>» 4 »
A considerable number of experimental platea for the examiDi-
tioD of the focal adjustments have also been secured and carefullj
measured. A discussion of these plates baa resulted in a di^tiaet
improvement in the focal adjustroentSj while their permanence lus
b<»en further secured by an improved arrangement for circnlattnu
the air surrounding the prism boi. Whereas formerly a practicaUy
perfect temperature and focal control was secured no long, but onjy
so long, as the instrument remained undisturbed in one position,
under the improved circulatory system no appreciable change in
focus occurs us the result of moving the instrument from one
position to another,
A^mgraphic Telescope, — This instrument has l>een chiefly used
in the photography of selected regions, in accordance with the plan
proposed by Professor Kapteyn. The number of platea second
is as follows : —
a Tauri
, 25 plat
a Ononis
• 35
a Can. Min. ,
• 34 *
fS Ge mi nor urn
' 14 ,1
a Bootis
. 46 „
do Cen tauri
• 44 »
a Scorpii
• 39 1
n€»ciiptioti of Plate.
Kapteyn areas, pi-oper motion plates
Kapteyn areas, parallax plates (ist max.)
„ T, (and max.)
Parallax pilot plates . . , .
•Catalogue plates . . • . .
Adjustment plates . . , .
Comet Metcalf region , . ♦ .
No. of
No. r»t
DanHmtif
Flmtes.
Ejiptwirea.
J£llNM«|Cl.
56
112
30^30^
184
I 84
3o«
24
48
30^, J0«
7
♦ * .
various
9
27
6» 3»,:o*
8
*..
various
1
I
40-
During the year 199 Catalogue plates, containing 101,136 it4TS,
including 2282 standard Rtai-s, have been measured, botli in direcl
and reversed positions of each piate. The total number of pUtes
now measured is 1285, containing about 700,000 8tAr4iiMigei»
corresponding to nearly 300,000 different stars.
^- 1908. Eighty-eighth Annual General Meeting.
265
The actual state of the work on December 31 waa as follows ; —
M«Mui«i of Coordinntes.
No, of Plutes.
Ei'ctAiiKUlQr Courd!imt«s
computed and eicainincil.
No- of Plutcft.
Completed. OatBtnncling.
Completed.
OiiUUndlog.
-41"
144
144
...
4a
144
144
...
43
144
144
...
44
132 12
132
12
45
H3 ^
143
I
46
142 2
141
3
S
144
144
143
80
I
64,
49
ti8 3
I
119'
s*».
30 90
* 3
«»7
-5»
0 120
0
120
12$^
227
107s
437
i*late constants have been derived for plates in zones -41*,
|2*, and - 43*, and a]>plied to all rectangular co-ordinates in
— 41*, and to 1 12 plates in zone - 42",
')cculiaiions. — Twenty-four separate phenomena of oocultation
ksre been observed^ viz. —
■ Disappearances at dark limb . . -19
Reappearances „ y, ... 5
the observations up to November 14 liave been completely reduced
mA rmults communicated in advance to Professor Newcomb,
^■Tra/mi of Mercury. — On the occasion of the transit of Mercury
P^ovember 14, in addition to observations with the transit-circb
md heliometer, the times of ingre^ts and egress were observed by
lix different observers with the various eqiiatorials.
ComeU. — Comet 1907 a was observed with the Victoria tele-
icope on 6 nights, and the results have been communicated to the
d^ronoifmche Nachrichtefh The results of observations of Comet
PiaUj (d 1906) and Metcalf (b 1906), made during 1906, have
likftwise been comnmnicated to the Ast, Nach.^ and published
Eig tlie year
h^blicationB : —
^o\. ii. part 5 of the Cape Annals, c'ontaining ** Meridian
nrations of the Sun, Mercury, and Venus during the years
1884-1892," and vol ii. part 6, containing ** Results of Occulta-
ttoiis observed during the years 1896-1906," have been passed
through the press and issued during the year.
Vol. viii. part i, containing *' Heliometer Observations of the
Major Planets during the years 1897-1904/^ has been passed
through the press and will shortly be issued.
The Cape Catalogue 1905-6. based on meridian observations
made with the S-in. transit-circle during the year^ i905-6» and
radticed to the equinox 1900, has been printed and isBUed.
266
Report of the Council to the
LSJUIA,
The Cape day -numbers for 1910 have Irwen printed, and copies
received at the obsenratory for distribution.
Mr. hunt has contributed a note to the Royal Astrunoroictl
Society on "The preBence of Tin in Stelhir Atmospheres/*
Meteor* logical ohser cations^ comprising daily records of air-
temperature, prea.^urej wind, rainfalb etc., have been continued
throufrliout ihe yenr, and the resulta, as in previous years^ for-
ward^^d to the Meteorological Commisiaion, Cape Town.
Seiitmofjraph, — The recoi*ds of the sfiismograph have been for*
warded to Professor Milne, while a duplicate copy, at the requwt
of the German Govern me nt, is forwarded to the Consub General for
Germany in Cape Town, for iranainissioi) to the central station for
the investigation of eartht|uakes at Stra**burg.
Loiujitiuie operations.— ]b connection with a proposed tele-
graphic determination of tlie longitude of the Island of Ascension,
both from Greenwich and the Cape of Good Hope, during the viait
of ILM.S. *'Mutine" to Ascension in February 1908, Mr. Petl,
after leave of absence In England and before his return to the
Cape, ]»roceeded to Greenwich and ubserveU on 11 nighta for
coiufjariijon of his persotml equation, both with the Gre*»nwich
observers and with Captain Monro, R./N., who will conduct the
field operations at Ascension.
Geofhiic Surt^fj 0/ South Africa. — The fiel<l data of the
trill nj^mlati on connecling the northern end of the 30th raeridiiU
arc in the Transvaal with the ejcistin^^ tr]any;ulation in Rhodeeie,
executed by Captain Gonlon, UK,, between October 1906 ind
January T907, were received early in the year. The work }m
been completely reduced at the observatory, and the results for-
warded to 8ir D. Gill for publicatinn.
Tlie belli work in Nnrthein Khodetsia, after being carried as far
as ilpan^^e, S. lat, 9' 41', or about 73 miles south of Lake Tift-
gaiiyika, was abandoned in Xieceniber 1906, and all fit-Id boob
contmininif the gec^detic duta were forwarded to the observatory for
reduction purposes. The horizontal and vertical angles throuijbuiit
the chain have been reduced and adjusted so far as is poesible
until a definitive length of the base measured in the Loangira
valley ia arrived at.
The mea,Murements of this base, as contained in the fifld \wiki%
have been completely reduced and discussed, and the length of
the base has been derived in relation to that of the Kusdan
standard bur used in the niea.HuremHntR ; this bar has been fo^
waided to the ''Bureau International " for standardisation* and ihf
derivation of the actual length of the base is deferred until th«
results of tJiis cnmimrison are available.
The reductiiin of the astronomical observations, c?om prising
latitude observations at 18 sUitions and astronomical azimuths a(
2 stations, is well in hand, the field book data having been cooi*
pletely reduced and all star corrections cnmputed. The discuanoft
of the places of the 581 stars involved is now procee<iing, but it*
completiou awaits the re-observation of several of the stars with
Feb. 1 90S. Eight y'fighth Annual General Meeting,
267
the tranfit-circle, which will be secured during the early months of
the current year.
Hit
r QUI
Royal Observatorif, Edinbunjh.
(Director, Prof. F, W. Difmn^ A$tronomer Hoijal fur Scotland.)
The r«c»jtrditjg microm*jter referred to in last year*» report as
haviri;^ b«e« applied to the transit-circle has worked very aatis-
factorily, and the screw shows rio ap[>r<^cialjle wear The observa-
tion of zodiacal fitarji hns been pushed on vigornualy, more than
4000 oi>Rt'r vat ions being made in the year. It ha« bwn found
necessary lo leave out of the observiii^r list a number of stars of
low declination which cro88 the meridian before miilnight in the
abort suuimer evenings. With these omisssions only about 200
more ob»ervaliou» art? required. As regards the computations,
the observations as far as September 30 are reduced to mean
place, and to apparent place as far as October 31.
Spectroiicopic observations of the rotation of the Sun have been
continued un the same linen aa in previous years. From July the
observations have been made photographically irsstead of vij^ually.
Sanciion has been given f*jr tlie |mrchaae of a lar^^er objective, and
a 9-iuch object-glass of 36 feet focal length is being constructed.
Forty photographs of nebulae have been taken with the 24-inch
.feflector. Difficulties have been exi>erienced with this inatrunieut
ing to the shifting of the mirror, which have not aa yet been
quite overcome,
Sei^mographic oViservaiions have been carried 00 continuously,
and the results communicated to the Comtoittee of the Dritisfi
A«6t*ciatton.
Meteorological observations have been regularly made. Two
platinum resistantfe thermometers have been obtained and placed,
one horijon tally, the other vertically, in the rock at a depth of
5 ft. 9 in, The cracks in the rock allow of percolation of water,
and experiments with two tberm<imeters at the same depth was
adviaed by Professor Callendar befoie i>roceeding Uj place ther-
mometers at varying depthn. Observations have been made daily
since November 15.
Arrangements have been made to assist the Perth (Western
Australia) Observatory in the measurement of the Astrographic
platea. A micrometer has been obtained, and 100 plates have
been received from Mr. Ctx»ke»
The observatory has lost the services of Dr. Malm, who was
appointed Chief Assistant at the Ca[>e Oliservatory, and left
Edinburgh in May. Mr. Clark was promoted to succeed him.
The assiatunts' pouts at the observatory liave been placed on a more
**ti&fact<)ry footing, having been made permanent Civil Service
appointmenUt, a poaition formerly only occupied by Mn Heath,
the Fiffeft AHsistant
ig
268
Report of the Council to the
LXvni4,
Cambridge Ohservatortf, (Director, Sir R. S, Balk)
1, Meridian Cirde, — The Symiics of the Univensity Press
have undertaken the printing of the large volume of nieridiftti
circle results 1 872-1 900 meiitianed in the last report, and the
work is making good progri^ss. At tlie end of the ye^r priutijig
waa completed up to 11. A. 2^ 3C>".
Ailvtince t*tipiea of the residtB of the re-observation and ezaminii-
tion of all the single observation stars of the Cambridge A.G.
Zone Catalogue (t<) which reference waa made last yeur) have l»een
communicated to Dr. Ristenpart for incorporation in the Geschiehii
iies Fixslernhimmeli^. All points of interest which an>8e have
been th« "roughly examined, and it is believed that very f«w
discordances remain outstanding'.
Observation of (^iirs Zodiacal Stars has made good progrefls
during the y*^ar, 1532 stars having been observetl on 50 Jagiit*,
with the necessary observations of fundamental stars and ins^tru-
mental errors. The reductioii>< lo apparent place have been much
interrupteil by th^ work mentioned above, but are coiupleU^ m
K.A, to 1907 March 19^ and in l>ecb to 1907 September 10; anJ
the redortioDft to mean place are complete to 1907 February 7.
Mr. llartl<?y iias been in charge of the meridian circle, and \i^
carried out the greater part of all the above work during the year.
The meridian circle clock, by Hardy, which has been iti con-
tinual use since 1828, was thoroughly overhauled in 1907 January;
with the exception of sbght wear on one of the spring pallets,
which should not affect the time-keeping, the clock is in perlect
condition.
2. Sheepshatikg EquatoriuL — Two hundred and ihirty-eight
plates, etich containing four or more exposures, have been takfn
hy Mr. Hink^* durin^ the year, in continuation of the seriea for the
determination of Btellar [»arallax begun in 1904. On Deceml^r 31
sixty held 8 were on the working list as partly observed, und
thirteen bad just been removed as completely observed at four or
more epochs.
Sixiy plates taken at Cambridge, which had been lent to AJr. H.
N. Russell, of Princeton, U.S.A., were returned in 1907 April-
Further consigiuuenta were sent to him of 28 plates in 1907 April
and 13 plates in 1907 October, completing the series untinisbed
on his leaving Cambridge which he has undertaken to meaatire iQd
reduce.
The new form of crdour screen for bright stars has VH?en in iwe
since earJy in the year and appears to be quite satisfactory.
In preparation for tlie tmnsit of Mercury on 1907 November
14, temporary alterations were madw in the rectangular slides of
the hreech-piere, so that it became [>Dssible to lake a series ii( 64
photographs of a segment of the Suns limb at intervals of 3 or 4
secondB upon one plate. The sky was completely oveitaat OQ the
day of the transit.
Feb. 1908. Eighty-eighth Atmual Getisral Meeting,
269
Mr. Stratton ha« finished his investigation of proper motions
of faint stars iu the Pleiades from phites taken tit Greenwich,
Oxfor*!, and Cambfidge; the reaults were contributed to the
Society in 1908 January.
Mr. li. Knox Shaw (Trinity College : Sheepshanks Exhibitioner
1^07) became a student at the observatory in 1907 October, and
has begun work with the Sheepshanks telescope.
A new meaisuring nutchine, lo lake plates up to 10x8 inches,
•constructed by tbe Cambridge Scieiitilic Instrumeijt Company, has
been brought into use during the year. It is a Bimplihed form
of the original Cambridge machine constructed by the same
-company in 1900^ which has ^'iven complete satisfaction during
its seven years of uHt\
3, Reduction of Eros photographs, — The firat part (to 1900
Dec**raber 31) of the photographic standard system of cojuparisou
stars is now carapietf, and is diHcussed in Sotar Paraliax Papers^
No. 6 (in J/.iV',, 1907 December.) The second part is approaching
4:0m pie tion. The sy litem responda well to the tests which have
been made upon it, and seems to he well adapted for use in the
definitive reduction of the parallax plate*.
Definitive places of most of the Croasley reflector comparison
stars have been furnish ei I to I'ro lessor Perrioe. For a certain
BUniher the puhliRhed photographic mutenal wa-^ unsatisfactory,
and many of these stars were too faint to be measured on Cambridge
plates. The Astronomer Royal kindly undertook to meaatire these
stars at Greenwich ; he baa already communicated the places of a
first list of 48 stars, and a second list is under observation at the
•clooe of the year. The places of 33 very faint comparisnn stars
usefi iu ndcroraeter observations of the planet have been measured
on the Crossley reflector meridian series, and communicated by
-Professor Perrine,
Systematic correction8 have been derived for most of the pub-
lished series of pbotograpbic places of the planet, to reduce them to
the new standard system. Printed forms Imvo been prepared for the
formation of the equations of condition in tbe final general solution,
and a good ded of the preparatory formation of coefficients is done,
A preliminary collection of the micrometric observations has also
i>een made in order to see how far these may be used to strengthen
the weak places in the phuto^^rnphic series.
The completion of the standard system of comparison stars
foade it possible to resume the measurement of the Cambridge
photogrsphs tif the planet. Tfiirty-two plates, containing in all
3S1 images of the planet^ have been measttred during the year; the
number of comparison star?! meai^ured on e:ich exposure was about
nine. The reduction of ther^e measures is nearly complete. A
number of star places required for the completion ui the standard
system were also derivtHl from these plates,
Mr. Hink?* has beeti aided in this work throughout the year by
Miss Julia Bcdl ; and Mr, S. E. Bowd has been engaged on V\i^
-card catalogue and misceJiaweoun computing. The expense ol l\\v&
2/0
Bepo^i o/tfu Council to iht
UCTHLd
*8«siance has been defrayed by a grant from the Governmei
Grant Fund of the Royal Society.
^, Floating Zenith Telemccpe, — As noted in laat je&T^s report^
Mr. C<x>k80n has foubd it necessary to extend the observations with
his zenith telescope uv«r tw») years: enough material has now been
gathertji], the last photo|^'rapli having been taken in July. The
number of photographs available lor determining ihe constant of
aberTutiim is 120. All of these plates have been measured in one
position of the phttc in the ninTometer : about half have also
been measured in the reversed position. The rest are now beiwg
measured. The reduction of all the measurements is in hand and
is being carried out with the asai^tance of Mr, A. D. Campbell.
5. Reiluction 0/ Lunar ObservatioftB. — Mr. Stratton has am
tinned his new reductiijn of Schliiter^s observations of the Moon for
comparison with Hnyn'^a determination uf the eunstunt^ of the
Moon's libra tion and of the selt^iiographical co-ordinates of Mcisting
A» and the work is making steady progress,
6. Courses of instruction in practical astrouoiny, and in Eeld
astrtuiomy and trigonometrical survey, have been given by Mr.
Hinks during the year.
Thfi NmncUl Telemjpe^ Cambridge Observatort/,
(Mr, H.F. NewalL)
4
The 2 5 inch equatorial was used in the early part of the yetP
1907^ with the four-prism s]jectrograph, in photographiiig the red
end of the ispectra of the bri«L:bter stars. Special attention was paid
to the spec t mm of a Orion is in its relation to the spectrum of sun-
ipots. A note on some of the results was communicated to the
Society in May {M,N., Ixvii, 482).
Experiments have been made and are being continued in photo-
graphing filar spectra witli a dillraction grating, in order to decide
whether the lines t if the telluric E group can he satisfactorily utiliseJ
for determinations of stelhir velocities.
Meitsurenient and reduction of stellar spectra waa carried on
chiefly in the earlier part of the year,
Tlie solar work has been carried on with the Littrow spectroscope
and with temporary aiTangementa t>f coelostat and image lenses.
Meanwhile the permanent mounting for the cadoatat has been con-
structed, and was dcdivered at the observatory in December* It is
expected that th« new image lens of long focus which is to be used
for the solar observations will be completed in time for the work
in the spring or early summer.
T!je Littrow spectroscope has been used fur the study of the
cyanogen absorption -bands at wave-length 3883 in the lolar
spectrum. A note on some of the results was communicated to the
Society in November {M.N.^ Ixviiii. 2). The instrument has been
found very convenient to handle.
The same inauum^nt ba& been used by Mr. Hubrecbt
^^.
'eb. 1908. Eighty'eigkth Annual General Meeting. 2Ji
preliminary work on the determination of the rotation of the Sim
)Y the 8pectroscoj>ic method.
A good deal of work has been devoted to the study uf tlie
spectrum of the electric arc under varied conditions in the Iftboratory.
IDunsink Ohserratory,
{DkrtdcT, Prof. E, T, WfMaker, Royal Astronajmr af h-eland.)
The staff consists, as at the close of the previous year, of the
)irector and Mr. C* JLirttn, assistant; the ins^truments in regular
ise are the Pistor and Martins ujeridian circle and the Roberta
photographic ru Hector,
^^ The reduction of the meridiau observations of tlie red atara in
^Blie working-list prepared by the late Director, Professor Joly, haa
^^peeu completed during the year. A new working-liyt for the
^^nieridian circle has been prepared, forming an extension of the
^■previous lint, and consistin;^' of staris of a similar character and
variable stars ; observations of these stans are now in progress.
The time service to Dublin lias been continued as in previous
joara*
In the course of the muridiim observations it was sm^pected that
3 roe of the red sUtrs which have not hitherto been recognised as
rariables are such. Accordingly, th^ Roberts photographic reflector
now being employed in a dti termination of the photogmphic
[lagiutudes of tlie red slars which are not known to be variables,
rith a view to the detection of variability.
The obiter vatory library bus beeji catfiloguad during the year.
The (irofesBorial lioursps of lectures delivered in iJutilin by the
>irector have been entitled "Theory of Energy and Radiation*^
id ** Thet»retical Spectro.'^copy/' Detnonst rations in practical
astronomy art? given at the observatory by the Assistant Astronomer,
f>d the south equatorial has been enipb»yed on tlie tii-si Saturday
each month in showing objects *jf interest to visitors, The
j>b*ervati»ry was visited in -July hy His Excellency tiitj Lord
itenant of Ireland.
pia
f
Durham Olwervatonj. (Director^ Pm/e^sot' R. A. Sampson.)
The greater part of the yeur haa been given to the theory and
bles of Jupiter*s satelbtHS. A new theory has been developed,
ied upon the constants derived from the llarvnrd eclipses : it is
b«>ped that this theory will prove of interest for its own sake ; it
has been much advanced in all its details during the year. The
plan for the tables has been laid down, and some jiarts of them have
i?n computed.
Observations with the Almucantar have l>een cotJtintied as here*
fore ! 602 stars were observed upon 40 nighta.
272
Report of the Council to the
Gloftgow Ohsertmtary, {Diredor^ Professor L, Becker.)
Good progress has been made with the reductions of obsBrvatiti
obtained in former years. The observing work baa been coutinui
with t ran a it-circle and spectrograph, but though all favourable
occaaioiis were utilised, the output is small owing to the few clear
nights. The Univertiity authoritiea have under oonaideraiion s
scheme which proposes to erect an observing station at some dia-
tance from this largt^ manufacturing district.
The time service and the meteorological observations have been
carried on as in former years.
Liverpool Observtdory, {Dii-tciorr Mr, IV. E, Plummer.)
During the past year there has been little cfiange iu the inat rumen
tal equipment, the staff, or the work of the observatory. The merid*
ian instrument** and chronogrnph are l;ept at work regularly in ord«r
to ensure the distribution of correct time to the port of Liverpool).
The apparatus for signalling has worked without failure throughoui
the year. As in past years, the equatorial has been devoted to tlw
observation of comets, measures being made tis long as the comet is
bright enough to be seen. Measures of the jiosition of the com-
ponents of a few binary systems are made with regularity, The«e
observations are con fined to tho^'e stars that have long bfen
observed, and for which the aperture of the telescope is suitable.
In some cases the measures have be on u^^^ed to detertniiie the orbits
of binaries, empluyieg as far as possible orily those measures that
have been made with instnmients of similar size. It was hoped
that more accordant results might be obtained if the influence of
aperture were eliminated, but the accidental errors appurently mask
any systematic dcacrepancii?s which might arise from this caufte<
Some slight additions have been made to the instruments
the meteorological d*^partment, and the observations for climatoloj
etc, are continued as lieretufore. 1 he record of unfelt earthquake
with tht) Milne aeismngraph is regtilarly maintained. The results
are freely commuTucated to all who are interested iu these inquirieSj
The tei<ting and rating of chronometera and the examination
other apparatus form part of the routine work of the observatorji
Lectures in connection with the University of Liverpool are
regularly given,
Haddiffe Ohservafort/^ Oxford,
(Director J Dr, A. A. Eambaui^ RmlcUffe Obserrer.)
iJuring 1907 the work of this observatory has been continued
on the same lines as in recent years, but its effective strength has
been reduced by death and otlier causes. On January 21 Mr. E.
E* McClellan, who bad held the post of third assistant sinco tS^inJ
died rather suddenly. Mr. H, IJarrett, late computer at the Roj
I
ask
I
Eighty-eighth Anmml General Meethig,
2;3
rvatory, Greenwich, was appointed to succeed him on June i.
wards the end uf January, Mr. Reuben Harris, why had been
ployed as computer at the observatory since March 1903,
[igued.
The investigation of stellar parallax has been carried on as
usly as the weather would permit, but although no oppor-
luity has been lost of photo*itap]nng l^rofessor Kapteyn's selected
regions — the particulars of which were published in last year's
report^ — cloud and fog in the early niorniuL^s have mudi intei'fered
with the completion of this work. There still remaiii hve plutes of
the region around Nova Persei, hve plates of liD. +I5^ 651
(Hyades), and two plates of B.B. +31°, 1684, which ref|uire for
their completion a third seasun^s exposure. It is hoped that these
exposures may be successfully carried nut by the time this report
appears. Five plates of the region surrounding Laiande 5761 have
been sent to Professor Kapt-eyn at Groningen, and there measured
and reduced under his direction, with satisfactory results.
Photographs of Daniel's Cornet 1907 d were obtained on August
1$, 20, and 26: and in prepiiratiou for the tTausit of Mercury on
November 13-14 the 24-inch telescope was fitted with a short
cX|K>sure shutter, and |di olograph a of the Sun were taken in the
principal focus. Clouds prevented any phott>graph being taken
durinj? the transit.
The 18-inch visual refractor was employed in examining the
bility of Saturn's rings on September 24, November 6, 26, 28,
•ccember 5, 6 and 14,
In the autumn of 1906 the heliometer, w^hich has long been
out of use, was dismounted, and the io4nch Barclay equatorial
erected in its |ikice in Fehmary 1907. To this instrun»ent has
been adapted the Grubb hifihir micrometer made for the iS-incli,
Thiis oombinatton proves very convenient for observations of double
stars and comets. Micrometer measures of the pusition of Daniers
Comet have beeii made with it on .luly 30, August 11, 13, i8» 20,
26, September 8 and 11. Other miscellaneous observations made
with this iuiitrunient include^ —
( j) Ubserviitions of Mellish*s Comet 1907 e^ on Oct«iber r8, with
ring-micrometer.
(2) Comp'irlsons of the ma^^'nitude and colour of Mira Ceti and
Cell.
(3) Spectroscopic observations of solar prominences, especially
of the great otitburst of November 15, an account of which was
published in Nature, No, 1986, vol Ixxvii.
(4) Transit of Mercury, seen for a few moments throujih elowds.
(5) Examination of Saturn and its fni^ii on October 4 and
November 23.
Naked-eye obaervations of Mira Ceti and comparison stars were
made on January 2, 3, 6, ti, 17, 18, 22, 23, 29. 31, February
2, 10, 13. and 16. The results of the whole series of observations,
continued from last year, were commnnicaled to the Society, and
published in the Monthly NoticeSt A]>ril 1907.
ec
«
274
Beport of ths Council to the
LXVIIL \
The computing strength t»f the establishment has this year been
maifil V ilirected to the ryductioti of the meteLirological observatimie^
but work in this department baa been much interrupti?d,
A considerable amount of time towanls the end of the year hi*
been de looted to the exkimination of the original records and rtKlue-
tiona of the observations made with the transit-t'irclc under the
direction of Main, 1862-76, with a view to elucidating a long list
of discordaiiees fijund by Ilerr Osten between the places publisbi "
in the annual volumes and those of the A.G, Oafalo^u^. Tf
work was undertaken, at Dr. HiBtenpart^a request, for the Gej^chu'l
fte Fix^fernhimimh, The result of the examination has been
account for most of the diacordance« by errors in reduction, proper
raotir»n, or other causes.
Meteorological and Eiirth temperature observatioDS have been
made regularly an heretofore. It is intended to discontinue the
latter (which have been Ocuxied on without interruption since 1898
^oveniber t) at tbe end nf 1909.
Unhmrniy Oh$erfHitory^ Oxford.
(Director, Professor H. H, Turner.)
Volume ii. of the Oxford AHtrographic Catalogue was tsatj^
early in the year. \^3lume iii* (160 plates, centres 4-29': 62713
star images) wan (►assed for press on July 10, and a few co|>ie§
have been distributed, \-oiume iv. (160 plates, centres 4-28*;
65^808 star images) m completely prmt,ed except the Introduction,
so that tha rate of two volumes per year is being maintained, thanks
to the stfiady and devoted work of Mr. IMlainy and Mr, Plummer,
and to the important as si stance rendered by the Government Gwnt
Committee of tln^ lloyal Suciety.
During the concluiling months wi the year the Kquntorial was
diamountetl for various re[>airs, rendrred necessary by its long and
contintious service. The alterations iind cleaning have been carried
imt under tlie superintendence' of Mr. A. B. Chatwood» B.Sc.,
A,MJ.G.E., wlio accepted a nioiiestand temf»orary post at the Oh»er
vntory while awaiting confirmation of bis appointment as Astronomer
to 11. H. the Niaiam of Hyderabad. Special thinks are due to Mr.
Chat wood for the ;^reRt etierjs^y with which he has worked during
thefe few mt>nths» and tlio number uf suggestions for improvemenU
in the instrunient^ which will remove varioun discomforts experieni
in the past. He has also dt)ne work of a similar kind in otl
departments of the observatory,
Mr. H. C, Plummer applied, with the sanction of the Direci
for a one year*s Fellowslii|> of the Lick Observatory, commenci
last SeptembHr. He will thus have an opportunity of ac<|airi]
famiharily with spectroscopic work, which has not yet been organi)
at this observatiiry,
The Variable Star observtitions of Pop»on and the It^ixendi
have been put into iW h?Luda of the Director with a view
list
II
Feb, 1908. Eightif'tighth Annual GcTieral Mee4inff,
VS
j«uhlication. Those of Pogson were pr«pared for press by Mr, C,
L Brook^ and are being printed in the ItA.S. Memoirs, a subsidy
v( one-third of tlae cost haviirg been generously y^romised by Mr.
Brook himself, and another third by the Indian Government
The observations of the elder Baxendell require much more work
than thoiie of Pogaon, owing to frequent iliHiipesof the comparison
tfiars; bnt, with tlie help <d uii^rudsing volunteer !al»onr on the
p*n of Miss M. A. Blai^^g, of Cheadle, Statfordsliire, considerable
progress baks been made with the arrangement in ledger form,
Here al»o the Government Grant Committee have aided the work
by a «raaU grant for the more median if-al copying.
The Director attendcil the meeting of the Intenmtional Union
for Solar Rfsearcb at Mendun^ May 21-25. ^^ ^^^ been asked
to undertake the I'ormntion of a Computing Bureau^ and, with a
small subsidy from a privute sonrcf*, a beginning has beei» made by
Hn investi •nation of the position of the SunV aiis from «unnpot
records, on which preliminary nott^ was published in the Mofiihhj
N<itie^» for December last
The Director aUo attended the meeting of the International
Adsociition of Academies at Vienna, ^Iny 28 to June i, as a dele-
gate of the Royal Society. He was nomiiiftted on the Committee
appointed by the As^iociation to cotis<ider the question of Lunar
Nomenclature, and, at the request of the Cbfiirm>in (the late JL
lA*ewy)^ i» aeting as Seeretary to the Committee
Temple Oh*^rvatonj^ Hu'jfuj, (Direetar, Mr, (?, M. Seabroke.)
Tbi« observatory was used during the pa«t year for leaching
boys the use of in^^truments, and attempting to give them some
tm^te for astronomy. Tho q^are time ha^j Ij^oq taken up with
meaaiiriiig double 8tara.
Solar i^kysicn i)h»t*rvatory^ South Kenmtgton.
{Director t Sir Norman Locktjer^ K.CB.)
Oh$ei*vationg 0/ Sun-spot Spectra. — The Snn was seen on 245
daya during 1907, and obs**rvations nf sun spot spectra were made
ati 107 days, permitting the «xanunatioii of 211 apota in the region
F-D. The records continue to indicate that the lines ati'ected are
dua to Vanadium, Titaniufu, Scandium, and Mngnesium, in the
presence of Hydrogen.
For the pbotographit' record, with large dispersion, of the spectra
of Bun-spots a special instrument has been erected. It €on«ist-s of
a 12 inch siderostat, feeding a 12-incb concave mirror of 72 feet
foeal length, combined with a spectroscope, which i» of Littrow fornit
using a 6- inch Cooke lens of 20 feet focal length, and, until a larger
grating becomes available, a small plane llowlauil grating with a
nilad surface I'gx 1*3 inches (4*8x j'j cms.), 14,4^^ Uue^ t.o t\v^
276
Bepof't of the Council to the
hXYULi
inch. The results already obtained are very proraisiug, though iu
fiituatioii near the traffic of the ail joining street exposes the instru-
ment to considerable distnrhanci^
Sun Fhotofjraphs. — Daily photograph » (glacis negatives) of ibe
Squ's disc are received from Dehra lu\n (India) and from Mauritius
the gaps in the Indian record heing filled up as far aa possihle hy
nei,^atives from Mauritius and Greenwich, The negatives are for-
warded to Gre*^nwich for measuremetft and reduction as they ar^
required. Positives on p.'i per are also received. These are mounts J
on cartridge paper and bound up into half-yearly volumes for rejwiy
reference. Since the beginning of 1906 enlargements of apectro
heliograms for the same dates have been mount^ alongside ihe
paper jirints for comparison,
JSpei'troh/'Uo(/raph,^'lLh& weather conditiona were distinctly
lesa satisfactory for the purposes of this instrument than during
1906, though tine enough 011 142 days to warrnnt altempta V^iug
made to obtain monochromatic photographs of the Sun in "K"^
light. The in«trimieut cannot be used very satisfactorily daring
tlte winter months on account of its position among high buildingH.
During the period January 3 to December ij, 1907, 351 negative
were secured, showing the distribution of ** K '* radiation on the
8uii*8 disc. With the addition ♦«! an occulting disc over the primAry
slit plate 62 negatives were obtained, showing the promineuces
round the solar limb.
By arrangenient with the Indian Government, photographt
taken with the spec t robe lirtgraph at S<^uth Kenbiogton and
Kodi^ikarial are exoiianged, bo that tlie records may \je as compIeUJ
as pos.^ible for the year. During the })eriod January i, i9o6t
to September 30^ 1907, 465 spectrobeliograms have been received
from Kodaikaualj while during the years 1906 and i907» m
positives, showing the 8un's Jiinb in " K ** light, have been for-
warded to Kodaikanah
Tlae merisurement of the apectroheliograms ia now proceeding'
Thuugit, for many reasons, the work is extremely difficult, th«'
consistency of the results, so far obtained, has been very kiii>-
factory.
Stellar Spectra, — The weather conditions for night observatiou*
have been less favourable than during 1906, Fifty-two photo-
graphs of fifteen ateilar spectra have >>een obtained with the 6-iiicli
Henry ])rismatic camera with two prisms, and eight stellar ap<»cUu
with the y-inrh |»risnfatic re Hector, The 2 -inch quart z-cakit«
prismatic camera has been employed in photographing twenty t«in»
of stellar spectra, under couditiona as nearly constant as possible,
for recording extcnt^ions of the spectra in relation to the posiliuu?
of the stars on tiie temperature curve tjf the Kensington classifi^
tion. The weather has been extremtdy unfavourable for
photography of faint «*bjecU with the 36-inch reflector. Exp
mental work with plates specially sensitised tor the green trpA^
fihov^ed a satisfactory advance. Among other photographs, a
jpectnim, in the green region, of the Orion nebula was obiainedJ
Feb. 1908. E%gkty-€ighth Annual General Meeting,
277
FuhlicaHoni. — Papers dealing with the pressure data of 73
selected stations over the Eartli's surface, the report of the eclipse
expedition to Palma, Majorca, Au^aiyt 1905, the presence of sulphur
in some of the hotter stars, the spectroscopic comparison of metals
preeent in certain celestial and terrestrial light sources^, observation*
of Sun and stars made in some British stone circles, prominence
and coronal structure, and a note on the pernjaoency of some
photO'Visual lenses, have been coropleted during the year, and others
on allied subjects are in course of preparation.
Royal College of Science ^ Smdh Kensington,
(Assidant Pru/einor A* Fowler.)
Observation a of the spectra of sun -spots have been continuetl
in accordance with the scheme of the International Union for
Solar Eeftearch. The spectra (4 the nnibrte showed no perceptible
difibreuces as comj^ared with those recorded in the precedin^^ year^
ajid dark D-j was verv frequently observed in the circunipenunibrul
regions. Solar prominences were also observed when time per-
mitted, and partictdar attention waa given to the bright line^
Tiaible in metallic eruptions.
Further investigations of terrestrial spectra have been made^
with special reference to the interpretation of solar and stellar
phenomena. A detailed account and table of waTe-leitgths of
the titanium oxide f lutings, which are characteristic of the Antarian
(third type) stars, has been published {Pror, Rotj, ^Of\^ vol. Ixxix.A
p, 509). An interesting result of the experimental work was the
identification of the welbknown sun-spot bands between E and F,
with the comp«:>neut lines of the tlutin^'^s of '* magnesium hydride/^
a preliminary acconnt of which was commuuicated to the Society
in June. The continued investi^^ation of this spectrum has shown
that many other spot-btiuds in the yellow, green, and blue are also
acociunled for by magneaium hydride.
Sionyhursi College Observatory^
(Director, Hei\ W. Sidgreams^ S.J.)
The solar surface has been observed as usual on all available
days; 19S drawings of spots wnd facnlse liave been made, and the
greater spots have been examined with the grating spectrometer and
the r 2 -prism spectroscope.
The ntiw heliostat, mentioned in our last report, and also a
6-inch portrait lens — the gift of Mr. Whitelow, F.H. A*8. — have been
mounted, but regular work with lioth instruments has been delayed
by impediments experienced in the running of the driving-clocks.
Sir Howaid Grubb is surmounting those of th« heliostat ; and the
Director, with the friendly help of Mr. Parkinson, a mechanician ot
Blackburn, has so far improved the equatorial clock gear atid lV«
278
Report of the Council ta the
LXVlIt4
adjiistments of the Whitelnw camera that prolmhljr no ftirtber
difficulty will be ejtperi<»iiced in a long and repeated ex^ure o(
the same photographic plate.
Thei*e and r)ttier mechanical improvements have occapied t
cousidorable part of the year, and many of the clear nights have
been tie voted to experimental wurk in connection with tliem.
Work with the stellar spectrographs has lieen practically dlt-
continued, pending an examination of the collection of pUte*
already made. But thia examination haa been rendered impoasiUe
during,' the past year by the very long and laborions work^ now
complete, of re-casting all the meteorological computations of thi!
last sixty year^*.
Some triala of Wratten and Wainwrif;ht*s pan-chromatic platei
on the brightest stars have been made with the Hilger corapaand
prism. These carry the spectrum to Prannhofer'a C, and with
them it is intended to complete the photographic records of tlw
stronger spectra in our collection*
WoUingJmm Ofmrvatory (Rev. 7\ E, Espin's)*
Micrometrical measures of new pairs and neglected double sUf»
htive been continued throughont the year, and the results presented
to the Society.
Mr, Franklin-Adam^^ Astrographic Labor aiory.
In order to push on with tlie '* Chart of the Heavens,'* all
other work has been su.tpended and a second aaatstant eo^j^ed.
Extra help has also occasionally been emphiyecL
At the turn of the year a week-end conference upon seycr»l
matters in abeyance was held at Merve! Hill with Sir David Gill,
Professor Kapteyn, and ^Ir, Eddinj^ton, in order to make the work
as useful as posiiihle in the investigations now being carried ou
by them.
Messrs. Trough ton iKj Sirams have delivered the enumeratil^
machine, and experiiuontnl investigations of numbers and m^
nitudes of star^ upon the 15-inch platen are in hand.
Preparatiiins for piibiicatton are in hand, but the scarcity <rf
nights with three hours' spells of brightness makes it impossible U>
foretell the date of conimtmcement.
A new workshop has been built for the production of t : Incli
positives.
L
Sir WiUiaw Hmjtjim' Ohservahrt/^ Upper TuUe Hill.
Photography of spectra, and experimenral work in mftnA
directions, are being carried on in the observatory and in tli
iabomtory.
Teh, 1908, EiglUy'Cifihih Annual General Meeting,
279
Sir Wilfffd Peek's Ohaervatorf/, Rnugdon, Lijrm Metjis, Devon,
{Mr, C. (wTomr^ Observer in chary e.)
The observatoTj and instruments are in gond working order
The very changeable and unHettled wtather of 1907 hiu^ been a
great hindrance to observations, which were oidj nmde on 136
Qigbt« ; ihia U l«ss than usual . AugdRt, September, and October
were the three beat months, with 47 fine 1 nights. The observations
of long-period Variable Stars have been continued witb the 6*4-inch
Merz equatorial refractor, and 368 magnitude detenninj^tions have
been made. Argelander's method has been foil i> wed, as in the
previous twenty-two yeara this work has been in [>rogresa, dnring
which a total of 10,075 magnitude determinations have been
reconled.
Transits of stars are taken as often as required for regulation
of th«^ sidereal clock, which Diaintaius u good ateady rate.
Tbfc» planet Mara was observed on T5 nights, and 13 drawings
of th*f disc were made between July I and August 9 ; the presenta-
tion of the disc was mucli the same ns in 1892, when a line ecries
of drawings were made by Professor Keeler, which apjiear in
vol. li. of the Memoirs ItA,S. Many of these well-known features
were well seen at the recant opiwaition^
Comet Daniel (d 1907) was observed on many nights between
July 2 and August 21, at which latter date the comnt was a fine
imke<l-eye object with a tail 14* in length — the brightest comet
which has been seen for several years. The diisap|>earance of
Sftturn's ring waa well seen* It was visible as a fine hair-line of
light on either side of the planet on October 2, aud the next
lOtght it had totally disappeared, no trace of it being seen with
^Bowers 80 to 310, On Ot:tober 12 the air was so clear that six
BCf the sAtellites were vi.sible, but no trace of the ring*
Mr, Saufid&r's Ohiermiory^ Orowthome^ Berks,
The principal work has been in contintiation of the meaanre-
ment and redaction of the two Yorkea negatives of the Moon*
The reductions of the plate date*l 1901 November are completed^
mud the resulting places of 1800 points copied on to the card
index. On that dated 1901 August about 800 points have now
been completely measured and reduced ; some 700 more are at
\l measured once only.
Dr, W, E, Wilg<m*s Ohmrvaiory^ Daramona, Co, Weiimealh,
During the last year practically nothing has been done with
|6 a-feel reflector. The weather atill remains remarkably cloudy.
Numerous experiments have been made witfi the radio-integrator^
and tbst instrument now gives excellent resulta.
Report of the Council to the
LXYIIL4,
Kodaikdnai awl Madras Of>»ervatQri&s,
(Acting IHrector^ Mr, J* Evershf^d)
The first five inotiths of the year were, as is usual at Kodaikiuu),
extremely favourable lor sokir observations. September AtJii
December were also favcnirable, but the remaining five mouths were
unfavourable.
PJmtoheliograms were taken on 339 daya, and it vras found
possible to send to Green wiuli all thts negatives required to till in
the gaps in the Greenwich and liehra l)iln mis of daily photographs.
Spots were observed on 352 days^ and their positions approxi-
mately determined by projection* A totid of 301 new groups wifi
recordt^d, antl the mean daily number of groups viaiblt* varied from
27 in Juue to 71 in February, the average for the year being 46.
Spectrogcopic work. — Prominences were observed and their
positions charted on 305 dayt*. Detailed oliservations were also
made of the bright linen in nietalh*; prominences. Spot spectra
were observed on 129 days, and a photogTa)diic investigation of
the spectra of some of the larger spots of tiie year was succeesfttUj
carried out, usin^ a parabolic and a plant; grating. Ph<ttograp1iB
were also obtained of the spectrum of Comet I>aniel with %
prismatic camera.
Spectrohelivgraph, — After the completion of the new sliding
roof covering the siderostatj work was started on February 1. In
April a new primary slit was iittt*d, and the design of the secoodKy
slit was considerably modified. It was also fitted with a device for
automatically reci^rdini^f the setting after each exposure. The iustna-
ment has since wt*rked quite satis fuc tori ly, and in the eleven mooths
from Febrnary i photographs of flocculi were taken on 300 dajs
and of pjrominences on 253 days. Altogether, 1840 phutogr^phi
were taken.
Puhlicatimut. — Bulletins Nos. viii. to xi. were published duriog
the year.
At Madras, astronomical observations were confined to those
necessary for the time service.
Perth Oherrafori/, Wedem Ausiralia.
(Di rector t Mr. W. Erned Cooke.)
This year has been a memorable one for all the Aostimliui
State ol)servatories» because it marks the delinite separation of tbf
two deparUnents of A^tronamy and Meteorology. Hitherto «»cli
observatory hits had complete charge of the meteori^logi^al work of
its State, hut a Central Ci>mmun wealth Weather Bureati htis now
been established, and from 190S January i each State Astrunomcr
will be able to devote the whole «jf his time to Astruntimy*
At the Perth Observatory the year 1907 has been marked bf
^considerable progress. Ml tbe Catalogue plates have now been
Feb. 1 90S. Eighty-eighth Annual General Meeting,
2S1
^keti, ami measuremeui has at last bueB conitneaced. In June
two ludj assistants were appomted for this purpose, and during
lh« latter half of the year they have mea.'^tired 62 plates, con-
tainin*; altogether 25,157 alars, eacb one having been measured in
duplicate.
In addition, Professor Dyson, Astronomer Royal for Scotland,
b&8 very kindly offered to assist in the meafiurement of the Perth
plates. Ariangenionta have accordingly been made to send liim a
re^Iar supply of plates and reference a tar positions from the most
southern portion of our region (40° )» whilst in Perth a start has
already been made from the other end (33°)*
It has been decided to measure only one image of each star, to
duplicate each measurement with pljile reveraed, to disallow and
repeat all raeasureinent^ which ditfVr in tlie two positions by 0*005
{l''"5)anil upwards, an^l to publish ivsults to three figures only* In
justice to Professor Dyson, it shouM be stated that he wished to tike
the mean of the two ima^^es as was done at Greenwit'h^ and the
Director acct^pta the responsibility of limiting the measuremputs to
the tirdt image only (6 minutes' exposure) He was guiiled in this
decision by Professor Turner's remarks in the Introdnction to the
Oxford A^ti-ographic Catalogue, vol. i., top of page 25, also page 54,
where it is shown that the effw^t of taking four instead of two
measures is to reduce the total probable error of place f loin ± o''*39
t*> ±0**38; and under the present circumstances the extra labour
does not appear to be justified.
In the determination of the positions of the reference stars
pr&ctically a new epoch has been inaugurated this year. The
Cibaervfttion of the 422 standard stars was completed in March «
&nd a Catalogue giving their po»iti««iis for 1905*0 was printed and
distributed a few months later. Thia is the first published <J!ata-
logue of the Perth Observatory, and it forms the basis of all subse-
quent work, in the manner therein descril>ed. At the end of March
reobservation of the reference stars in zone 33^-4', which had
be6n interrupted for a little over a year by the work of the Stan-
dard Catalogue, was renewed upon the fresh basis; that is to say,
that instead of determining clock error from Nautical Almanac
fltars, and N.P,D. from nadir point readings, both clock error and
equator point are now detpmiined from the catalo^'ued positions of
at least six of the standard stars situated within the zone of
obiervation.
The winter was, unfortunately, a phenomenally bad one, by far
tlie cloudiest and most continuously wet that has ever been ex-
perienced hei"e. But notwith standing this, the transit observers
made excellent progress, and succeeded in completing the zone
33*-4' on 1 90S January 2 ; and, hari there not been an exceptional
mah of mpteorolugical work in December, the reductions alao would
be up to date ; as it is, they are only almut a fortnight behind.
It has been considered advisable to apply corrections to the
tfansit results obtained in previous years {zonea 3r-2'', 39''4o',
and the first part of 53*-4*) in order to reduce them to th^ ^t^tw\»
282
jReport of the Council to the
LXVIIL4
adopted standard, viz. that of the fii*tit Perth Catalogue. These
corrections will he applied hefore the places are used to determine
the plate constants. Considerable progress has heen made with
zone 39*'-4o'' which is required for Professor Dyson, but it has not
been possible to touch the zone 3i'*-2", which is required for the
plates now being measured here.
One piece of astronomical field work was undertaken during
the year at the request of the Surveyor-General, viz. the determina-
tion of the longitude and latitude of Carnarvon, on the N.W. coast.
It may, perhaps, not be out of place to call attention to the results
obtaineil, as the method of observation (almucantar) is only just
now coming into favour. The instrument was a 12-inch theodolite
by Trough ton *fc Simms. The method of using it was described in
Monthh/ Notices^ E.A.S., vol. Ixiii. p. 156, with an essential
correction in vol. Ixiv. p. 70. The weather was very bad. A
strong gale was blowing all the time, whirling the sand and dust
about, and there was a considerable amount of cloud. An ordinary
chronometer was used, without electric attachment Transits were
much interrupted by the following causes: — inability to follow
chronometer ticks on account of the wind's howling, clonds,
nickering of the light, head being blown away from eyepiece by
gusts of wind, sand or insects being blown into observer's eye.
Time observations were taken on five nights and latitude on four,
with the following results : —
Diif. of long. 8™. 44"'o6, 44''i2, 44^*07, 44**03, 44**03.
Latitude 24' 53' g''Sy S"-% io"-i, g's-
The results for latitude depend on only three pairs of stars,
and for longitude on from six to ten pairs.
The following is a resume of the work during the year : —
Nights on which time was determined
Observations of zone stars in R.A.
inN.P.D. .
Observations of clock stars in R.A.
Colli mation error
Separate determinations of
Readings on meridian mark
Level error
Azimuth error
Nadir point
197
4240
4240
1230
II
224
71
Meteorological. — As already stated, this department has now
been handed over to the Federal (jovernment, but during 1907 the
work proceeded as usual.
Feb- 1908. Eighty-eighth Annual General Meeting,
283
M^boume Ol)$m'vatory. {Director^ Mr. P. Baracchi,)
The astronomical work done at this observatory during the
year 1907 was as follows : —
Meridian Obsei^vaiiom : —
Clock stare..
Azimuth «tftr»
Lifltttarff
Total
ObMr▼fttJo^a
in R.A.
'334
3234
OtMWdmUona
In N.P,a
59
>33t
1390
The list stars were selected from the Melbourne plates of the
Astrophotographic Catalogtie, to serve as fuiidamenta! poioU of
reference for the reduction of these plates. The total number of
this class of stars dow completely observed not less than three
times is 5965.
The Annual Catalogue for 1905 has been complete^!, and the
Anaual Catalogue for 1906 is nearly ready. The General Cata^
logue for 1900, incluciing all stai-s observed since 1B94, has been
farther advanced.
Adrophoiographic Operatiom. — The Director regrets to report
that the Assistant Observer, Mr. W. J. Wallace, who waa con-
aected with bhi^ work, died on 28th December last, after a long
pariod of ill-health, which extended over the greater part of the
year.
The following table shows the number of plates exposed during
the vear : —
Chart jilfttes with triple exposure of 30"^ each
Catalogue plates (duplioate seriei^)
Test pUtea oa South Polar regions „.
Plates for trails, adjnatment of centre, etc. ..,
Paiaedaa
iatiAfactor]r»
13
19
9
The state of the Astrographic work allotted to this observatory
in as follows : —
The first series of 1149 plates, covering twice the entire region
aoatb of Dec. -64*, and the series of chart plates with single
exposure of one hour, whose centres lie on the parallels of even
degrees of declination from 66* to the South Pole, were completed
some years ago. A duplicate Catalogue Series is in course, yf which
354 regions have been photograph li'd.
In the series of chart plates with three exposures of 30*" each,
having their centres on the parallels of odd degrees of declination,
532 plates have been taken, Thus^ the original programme, so far
as actual photographic operations are concerned, has been practi-
eally carried qui.
20
284
Report hy the Cofincil ta ths LXTITI, 4,
It is intended, however, to complete the second Catalogoa
Series, and to extend the triple exposure chart plates to the regiom
of even degreeii of decDnation, as the chart plates with aingle
exposure of one hour are not considered aatisfactory.
The me:i-surement of platea will be dealt with in a separate
report.
The following routine duties and other miscellaneous work wew
carried out for local public requirements as in former years: —
The Time Hervice, iucludiDg daily time signals, control of publie
clocks, and rattng of chronometers for the shipping.
The tcjsting of nautical, meteorological, and surveying instnir
mente.
The technical oi^r^ rations of the Bureau on Standard Weights
and Measurcis according to law.
The Weather Service, including the control of some 1000 re-
porting country statioTia.
Th« continuous registration of the variations of sea-level, atmoa-
phertc elements, »eismic disturbances, and the elements f>f terrestrial
magnetism, including the reduction of magnetic recorda of past
years.
An Australian Weather Bureau has been established by the
Federal Government witli headqiiartois in Melbourne, but not in
any way connected with this observatory. The new institution
assumed official contro! of the weather service of the various States
of the Commonwealth on lat January last, thus rt^lieviog the
existing Australian observatories of all their public duties in con-
nection with meteorology.
K
Joint Report of the Direct om of Hie Mellxmme and Si/dtiejf 0h$9t'
vaiories otf the Afeamremmit 0/ the Platen of the Astrophat/>-
fjraphic Catalntjue,
The Catalogue plates of the Sydney and Melbourne Zones,
covering the whole region aouth of -51*, are being measun^i at
the Melbourne Observatory by a special Bureau established for
this purpose towards the end of 1898, and ma in trained jointly hy
the Governments of New South Wales and Victoria.
The work of the Bureau during the year 1907 was carried on by
a staff of six ladies, under similar conditions, and using chiefly the
s'lme pair of Uepsold micrometric instruments as in former years.
The numbers of plates completely measured In the direct aad
I e versed positions, in the course of tlie year, are —
138 Sydney plates, containing 97,881 stars.
56 Melbourne plates, containing 15,870 stars.
The total aggregate numbers of plates measured up t<i ji^t
December 1907 are as follows: —
700 Sydney plates, containing 423,859 stara,
892 Melbouine plates, contalniDg 284,584 fitart.
Feb. 1908. Eighiy-ei^hth Annif^al Cftmral Meeting,
28s
Sydnef/ Obtervatory, ( Director ^ Mr, H, A. Lmelian,)
III the early part of the year it was atmounced that the Govern-
ment required the site of the observatory for other purposes, and
intended to remove the instrtiments to a new jKnition.
In May an Advisory Coniiiiittec was apijointed to act with the
Government Astronomer, and many sites suitable for an ol>servatory
were ms]>ected. The one finally selected was on or near the Cano-
bias moaotain, in the vicinity of the town of Orange, 130 miles
WBst from Sydney, where there is clearness of definition, freedom
from city lights, electrical diKtnrbances, and other troubles which
are encountt^red in the present position of the observatory*
ITothiug has yet been decided as to the future, and the observat-ory
is irtiU fixed in the original site* The report of the Advisory
Committee has not been acted upon*
The transit-circle piers and the graduated circles have been
cased in, to shield them from air- currents which caused expansion
and contraction. This was a very necessary work, and since it has
been completed the instrumental corrections have been more con-
stant. There has also been less tarnishing of the ^ratluated silvet
bands.
Other instruments have been in the hands of the mechanician
and placed in working order. A ^inch Grnbb equatorial tele-
acope in the north dome required many alterations to make it
effective. l*he alteration of the double pendulum escapement of
the cylinder chronograph to a rotary one was much appreciated by
the First As«i»tant. A new direction recording frame has been
made for the anemometer* During the year I908 a new sidereal
clock is to be placed in the baseiuent, where it will be free from
air-cnrrents and excessive changes of temperature. A isdncb
equatorial telescope is also to be ordered from Sir Howaid
OnibK
New magnets have been received from Kew Observatory to use
at the Red Hill branch, v* here the maj^netic work is carried out.
During December three members of the Astronomical Staff left to
join the McClean and Lick Observatory [»arties for solar eclipse
observations at Flint Island — two of them joining Mr. McClean.
Shoidd fine weather conditions prevail on the eventful day, they
will obtain experience that should be of use to Ihetn when they are
called upon to observe the solar eclipses in Tasmania in 19 10 and
in Australia in 1911.
Mr* Olden has qualified as an observer with the transit-circle,
and is of much assistance during the absence of the members of the
itfcC
Improvements have been made in the buildings at the Red Hill
Wuch* A large dark-room has been constructed for the develo^m^
^ Uie Astrographic plates, and a new pier erected tor tihe m^^weV
286
S^oi'i by the CcmTwU to the
Lxvni. —
The foUowmg observations have been made with the tnuiiil
circle : —
Number of R.A. observafeiona of stars . . .1986
N.p,a ,, „ ... 1665
„ RA, „ of Sun . . . 447
The 9 A.M. CoUimation, Nadir and Level readings . jo6
9 P.M. Level readings 108
„ Kadir determinations . ♦ . . loS
„ Azimuth determi nations . . .118
The computations are in a forward state ; the abeiract for 1906
will ehorUy be completed » and a portion of the 1907 work b well
in hand. The accumulated observations with the transit-circle for
years back are being prepared for printing and publishing. Visitors
were numeroua, thost^ in the daytime numbering 768, and dunug
the evenings for lectures, etc. 534,
Two comets, c and d 1907, were observed in July and
August, and photographs tjiiken. This to a certain extent interfered
with the Aatrographic work, and the preparations for the departure
of the party to observe the solar eclipse at Flint Island caused a
farther interruption towards the end of the year.
The readings of the magnetic declination at the Red Hill branch
ahowed 9* 2^^ 17" east, making for Sydney 9* 32* 17* east — practi-
cally a constant determination. The intensity, verticfid and
horizontal forces have also been determined.
Tidal registrations on the coast and harbours of New Sou
Wales have been continued.
The seismograph has been in use constantly during the year, afid
80 earth tremors have been recorded on the photographic band
These have all been measured and tabulated^ and the results for
warded to the Secretary of the Seismtilogical Committee, London
The hbrary has received about 750 books, pamphlets, etc^ whid
shows a falling off in the number received during the previous yes*
This is probably accounted for by the separation of the two braoches^s
of the observatory. Meteorological books which were previottfVj''
sent to this observatory may have been diverted to the Cectf^^
Bureau, Meteorological Department, Melbourne.
Lovedcde Obiervatorpj South Africa.
{Dr. Al&r. W. Bolrerti,)
The Director returned to South Africa in the end of March, ^^^
regular observations were carried on during the remaining ^^^^
months of the year.
The work done was, as heretofore, the observation d certa*
well -known southern vaiiaUft %VAt&.
S, Eighiy-eighih Anmml General Meeting.
287
Observations were made on 1 2 1 nighta during April to December,
d the following measures were secured : —
Algol variAbles (S atara)
Short period variables (23 stars)
Long period variables (69 stars)
k
952 observations,
2052 „
2408 ,,
5412 „
During the paat fifteen years the guiding aim of the work
tempted at Liovedale has been to secure such a continuous sories
observations of typical Algol and short period variable stars as
ight in the remote, or probably immediate, future give data for a
iterminatioit of the orbital movements or pliyaical conditions
hioh produce or modify stellar variations of the eclipse and short
^riod character.
It is hoped that this aim has to a certain extent been realised.
In the future t!ie work done at Lovedale will be the examination
suspected variables, and of sucii long period stars as indicate
cular variation in their light curves and periods.
During the year a determination was made of the value of the
nt of atmospheric absorption.
Mr, TebhuiVs Ohseruatori/, Windsor, New South Walm
feasures, several times repeated, of thirteen of the most
kiereeting binary stars of the southern hemispbere constitute the
alj astronomical work at this observatory for 1 907. The results
ill shortly be sent to the Society, l*aily observations of two
dn-gauges at different heigh tjs, and also observations of the
ifioua monthly maximum and minimum temperatures, have been
red during the year.
288
Jieport hjf tk§ Council to the
LXYII14,
NOTBS ON 80MB P0INT8 OONNBOTBD WITH THI PBOOBlflB
OF Astronomy dxtbing thb Past Ybajl
Planets and SateUitea.
The following 98 planets have been discoipered or first
announced during 1907. The year of discovery is 1907 oilen
otherwbe noted.
H
1
. :
0
n
1
1
1^
'\
i
1
Z$ 693
J«ii.
la
Li
YU
...
Apr. 4
K
UN*
'06 July 16
XM 6a4
Feb.
10
K
YV
...
4
K
UNb
'06 Jilyi6
XN 625
II
K
YW
5
E
ZT
...
July 19
XO 626
II
K
YX
632
5
E
ZU
...
Aug. 8
XP ...
8
M
UMa
'06 June 20
L,
ZV
...
8
XQ ...
8
M
UMb
'06 June 20
La
ZW
...
29
XR ...
La
VEft
'06
Sept. 22
La
ZX
Sept 8
XS 627
Mar.
K
VE^
'06
Sept. 22
La
ZY
...
8
XT 628
K
WT*
'06 Dec. 6
La
ZZ
...
XU 629
K
YY
...
Apr. 7
La
AA
...
XV ...
K
YZ
...
7
La
AB
...
XW 630
K
ZC
Mar. 20
M
AC
...
XX ...
M
ZD
...
Apr. 17
M
AD
XY ...
M
ZE
...
18
M
A£
...
YA ...
Feb.
15
M
ZF
II
M
AF
...
YB ...
Mar.
M
ZG
10
La
AG
...
YC ...
M
ZH
15
La
AH
...
YD ...
M
ZJ
May 9
E
AJ
..
Oot 4
YE ...
II
M
ZK
...
II
E
AE
...
YG ...
II
M
ZL
II
E
AL
...
YJ 631
21
K
ZM
633
12
E
AM
...
YM ...
Apr.
K
ZN
634
12
E
AN
...
YN ...
K
ZO
...
Apr. 5
Ls
AO
...
Nov. I
YO ...
K
ZP
...
May 4
M
AP
•.•
YR ...
K
ZQ
5
M
AR
...
YS ...
K
ZR
...
II
M
AS
...
YT ...
E
ZS
«35
June 9
L,
AT
...
We^^^ :MgoS. Eighty'tighth Annual Gin&ral Meeting, 389
ltj
1
1
Q
i.y
Nov.
P
i.^
K
\ ^''^
S
v^
s
■ ''
K
r 1^ ..
6
K
BA „,
BB .
BC .,
BD .
BE .,,
BF ...
Nov.
i
>■
s
w
w
w
M
M
BG ,.,
BH „.
BJ ...
BK ...
Nov. 10
Dae.
Nov.
Deo,
30
4
27
K
K
M
M
A pknet fouoJ on Greeuwieli plates txposed 1903 August 6,
ji, September i, has bfjeu desigiiat^^ii LX*, UW is identical with
66, UZ with 408, WO with 260. WQ with 167, XK with 129,
XLwith462» XZ with 469, YH wiih 236, YK with 411, YL
with 629, YP with 62, YQ with 450^ ZA with 510, ZB wiih 31,
615 with KK and KY, WK prohably with 34, 635 with TU, UT
probably with (^X, YA with YP\ AQ with 528, AX (probably)
with 518, BA (probably) with 566.
The following planets, not inuubered at the dat« of the last
report, have stuee received permunent numbers : TE 6o2» TJ 603,
TK 604, UU 605, VB 606, VC 607, VD 60S, VP 609, VK 610,
VL611, VN 612, VP 613, VQ 614, VR 615, VT 6i6, VY 617.
VZ 6i8» WC 619, WE 620, \VJ 621, WP 622.
The following have received naoi^^: 398 Admete^ 410 Chloris^
411 XmUke^ 414 LiriiJjte, 426 Hippo ^ 427 Gaiene^ 429 Lotu^ 430
ilybrisj 431 Nephele, 437 Rhodia^ 438 Zeuxo^ 441 Bathilde^ 453
TVa, 497 /tvi 506, Marioii, 508 Frincetonia, 517 KtlUh^ 518
ffaiatre^ 519 Sylvafna, 523 i4r/fl£. 533 i^ara, 534 AW«o<.'/a, 535
Montague, 537 Pauh/^ 583 ClutHihi, 588 Achiiles, 602 Manatma^
617 Pairodu^^ 620 Drahmia, 624 Hector.
The initials rei>reBtfut the fullowiLg : K = Herr Koplf, Heidel-
^»ig; Lj=Herr I>obnert, Heidelberg; L^^Prof. Lowell, FlagptaH,
Ariz.: L3=M. TJapiri, Piilkova; M = Dr. Metc^ilf, Taunton, Mass.;
P — Dr. Pidistt, Vienna; S = Iierr Hcheifele, Heidelberg; W = Dr.
Wolf, Heidelberg.
VY'' = 6i7 Patrochm and XM^624 Hector prove to have, like
TG = 588 A*:hilles, orbits with nearly or ijuite the same period as
^Tnpiter. exeinplifying more or leas clnsely Lagrange's proposition
of the stable motion of three bodies at the vertices ol ar» equilateral
tiiAngle. The longitude of VY Patroclus is less than that of
•Jupiter, that of the other two in greater. Both Achilles and Patro-
^iqa have been well observed at their second opposition, bo materials
mam «va-Uable for determining their orbits accurately. The question
of the friability of these orbits, both as regards the Jupiter per-
turbations and those of the remaining f>!anets, is an interesting
one, ant) has not yet been c^unplet^ly solved.
Dr, EoHs lias published new elements of Jupite.t*^ t^l^WvV^is^
VL and VH. Those of the former are based on th« eM\^ ipW/e*
290
Beport hf the CtnmcU to the
LXVIIL4,
secured from Harvard plates of 1894, 1899, as well as those smce
the discorery.
Elements referred to Earth's equator 1905*0 : —
SatelUte VL
SateUite Yll.
TS
268-82
114-22
Q
171-00
29>45
i
I
555
20 -oo
25-31
238-23
e
Sid. period
a for log A = 0*71 624
. °''55
25o**-6i8
3037"
0*207
26o«»-o6
3113"
VL
Annual increase of T3 on Earth's equator, i -493
Annual increase of V5 on Jupiter's orhit, i'373
Annual decrease of Q on Earth's equator, 4*358
Annual decrease of Q on Jupiter's orbit, 1-207
Inclination of orbit to Jupiter's orbit . 28*747
VII.
i>4
I "35
27-972
Dr. Ross also gives the principal perturbations, of some of which
the approximate values are given here (Delaunay's notation).
dL =
VI.
+ -3 sin (2D - 2I)
+ -3 (2D-2F)
+ -2 (2F-2O
- -4 /^
+ 5 2D
+ 2*3 (2D-/)
+ -3 (2D-/-/')
- '5 2F
-2-7 (2F-O
VII.
e
+ -5
+ '3
+ '3
- '4
+ -8
+ 3*2
+ -4
- -8
-3'4
r
VI.
+ *CX)7C08(2D)
+ •003 (2D + ;)
+ •018
+ '002
-•007
- '002
- -024
(2D-O
VII.
+ -0I4
+ -006
+ 024
(2D -/-/») + '003
2F - -oio
(2F + /) --004
(2F -;) 030
d»'.
VI.
VII.
•5bin(F-0 - •«
•4 (2D-F-Z) 4 <
- -5
- -6
- "3
+ -8
+ '5
+ -3
(F-2/)
iiV-l)
3F
(2D-F)
(2D+P-O
(2D + F)
A. C. D. C.
- "9
- 7
- '4
+ •3
+ 7
+ "4
The Comets of 1907.
Five comets have been discovered during the year, and the
order of discovery has followed that of perihelion passage.
Comet 1907 (a), discovered on March 9 at Nice by M. GiaooUni,
was carried rapidly towards the Sun, and observations soon ceased.
But late in the year the comet, though faint, was again in •
favourable position for observation, and was photographed by
Dr. Max Wolf on December 4, who estimated the brilliancy !•
that of the 14th mag. The elements, which are not yet defioiteiy
known, resemble those of Comet 1890 IV. ; and though the identity
Feb, 1908. Eighty-eighth Annual General Meeting.
291
of the two objects is impossible, they may have had a common
origin.
Comet 1907 (b) was first seen by Mr. Grigg, of Thames, New
Zealand, on April 9, but iutelligence of ita discovery waa iirst
circulated by Mr. Melliah of the Washburn ObserTatnry, who »aw
the comet on April 14. The trace of the comet was snbRequently
fout»d on a pkte t^iken on April i j by Professor Bamartl, while
searching for Giacobini's comet. The object was faint and the
observations were not numerous. The orbit is interesting, since
tb«s elements are similar to tliose of 1 742, a bright comet first seen
At the Cape of Good Hope, hut also observed in Europe.
Cumet 1907 (r), discovered on June 1 at Nice by M. (iiacobiui.
This was also a faint comet and was t»biierved for only a short time,
Vat it is not impossible that it may be re-observed in the
spring. There is no reason to think that the orbit differs from a
parabola.
Comet 1907 {(i), found by Mr. Daniel of the Princeton
Obeenratory on June 9, was the brightest comet of the year, and
U% the morning sky of August was quitt* as conspicuous as a star
of the serond magnitude. Nuiueroua observations and photo-
graplie were secured, the latter disclosing a tail of very complicated
•tructtire, extentiing at least 17' from the nucleus. There was also
aome eviilence of a rotatory motion of the comet about a line joining
the nncleua and Sun.
The p>erihelion passage took place on Septeml>er 3, and after
perihelion obaervationa were po-^ible, the comet being picked up
oti November 5 by Dr, Hart wig, who reported it as of the eighth
tna^itude.
Comet 1907 (e) was first observed by Mr. MelUab, of the
Wai^hburn Observatory, on October 13. For some weeks the
comet increased in brilliancy^ and was so favourably placed that it
conld be observed on the meridian. The brightnes.H faded very
quickly, however, Hfter the middle of Novembfir, diminishing more
rapidly than the ordinary accepted f annula would explain.
It will be noticed that no periodical comet * has returned during
the" year, and no new elliptic comet of short period has been
detected, r^enniiig'a Comet of 1881 V, unfortunately passed
through perihelion withotit V>eing perceived, A similar fiite over-
took the same comet in 1890 and 1899 ; anrl since the mean motion
f:ould not be determined with great aceuratry in 1 881, this object
moat he considered lost. Swift's Comet 1894 IV,, an object of
unusual interest on account of its aupposed identity with the loat
comet of De Vico, passed through its perihelion about the beginning
of July, but was not seen. The ciiances of recovering this comet
are very slender. Comet 1900 III. (Gtacobmi) alao passed un>
detected.
On the other hand, a« evidence of long continued visibility of
Encke^ft Comet was photographeil at Heiddlberg by Dr, Max Wolf on
ember 25, but the CGinotAry character w»a not recognised till January 3,
292
Report by the Coutwil to the
Lxvm
comets, attention may be drawn to the fact that obstrvation*
Comet 1905 IV, already extt*ii»\ over a perioil o( mor« than thret
and a half years^ and may be even further prol6nged. Ohservatii*nA
of Comet 1904 J, extend from 1905 May 14 to 1905 June 5,1
753 day*.
Spectrum 0/ Comet d 1907, — The position of tbia ccimet ^
the hky was not very favourable for spectrum observations,
MM. Deshmdres ant^ Bernard at Meudon, Dr. Elosenberg
Gottingen, and Mr. and Mrs. Evershed at Koiliiikanai have obtaUMd
valuable results.
In iiihlition to the details shown by the nucleus, wbicb exbihtt
the ordinary characteristics, including the cyanogen band at X jSS^
Erst seen by Iluggins* in the comet uf 18S1, the spectrum of the
tail has been photographed for a disJancf of at least 45' from tiie
head. The spectra of the head and tail do not rigorously coinciiie-
While some bright bands are entirely confirjed to the nucleiw,
fainter bands can he traced to a considerable distance in the tail;
and fur tiler, some faint bands in the nucleus, whose cbemical
origin is not yet clearly ascertaiiied, are not reproduced in the taiL
It has therefore been sug^^eated that the confttitution of th»
nucleus and that of the tail of the crmiet are not similar. In connec-
tion with the same subject, attention t^liould be called to a paper bv
Mr, H, F. Kewall, in which he htis described the alteration produced
in the a[«ctrnni of cyaiiotren under viiriuus conflititms of pressure.
In thiB same paper Mr. Newall, after pointing out that jLjases tnd
vaptmrs must exist in circumsolar space, a fact that ia sufficiently
indicated by the extenainn of the corona and the length of
comets' tails, offers an explanation of the presence of those feature*
of tiie spectrnm cc«nmon to all cinnets. He submits that it is
more [>robabIe that thn approximate similarity in the spectra of all
comets is doe to the fact that these objects come in contact wttii
the sfime vapours, spread in their path as they apj»roach the Bu)>,
and by st)me process elicit the spectra of these vapours, than that
comets starting from all parts of the universe shouhl bring with
them the cyanogen and hydrocarhons shown in their spectra.
The orbits of the following com eta bave been definitely d(«ti
mined dnring I he year : —
Comet.
1796
1819 n.
1822
[S26 n.
1905 V.
1906 1.
rhumctcr of
Orbit,
Pflrabolie
CalcuUtor. Pluce ofJ
H. A. Peck Afii, Joumai^ No. 5# j
593'
ft •• ♦» 59^
CowUy .nd Wbit«.id« { 5T'v \" ^ „
^ \ A St. A#irA. No* tj.
n 7^n». i Annali daJV Oh»,
li. /*appa ^ ^^^^ Rmn^^no, rol. it^
Terkan and Ctncey A9L Nach. No. 4JtS
Feb. 1908. Eighty-Eighth Annual General Meeting,
293
The return of Halley'a Comet iq 19 10 has attraete^j considerable
a.|t9iiUou. Tlie discrepancy bebweeu the time of perihelion ()as8^e
c^imputed hy Pont^Scoulant aud the time indicated by Angstrom's
carve, foutuled on twa supposed inequalities based on Hind's identi-
fieatioQ of ancient returnts suggested the uecesaity far fiatber eom-
imtaiious. Such a revision was the more neceaaary owing to the
detection of a so^spicious error in the value of the perihelion distance
assigned by Pontecoulant.
# Atteution wna first directed to thia subject by Mr. Crommelm,
but later Mr. Lowell has collaborated, with the result that the method
of Ciilculating the perturbations of long period comets has been
esantined and simph^ed^ and the necesk^ary formulae have been
pat iu a very practical form. The object of thu inquiry haw been
twofold. First, to determine with the necessary accuracy the date
of the cornet"!^ pc^rihelton; secondly, to trace backwards tbecour&eof
tbis fam<.tUB comet, and to identify its several returns. With regard
to the first part of the investigrvtion, the result baa been to confirm
the general accuracy of Ponuconlant'a prediction. He aaaigned
1910 May 2^ 88 the date of next perihelion passage j and MeBsrs.
Cowell and ( 'romnielin show that the period be has assigned requires
to be shortenf d by nine, and two days for the actions of Jupiter and
Saturn respectively. Further, the large value for the perihehi^n
distance given by Pontecoulant is clearly in error. The historical
re^searcb, -sii far as it has been carried, proves that the coniet re-
turned in 1 301, as suggested Hy Hind- The result is the more
ii« lis factory, as very considerable doubt attached to that particular
dal«i owing to the misdescription of the coniet^/* position by con-
tent porary observers. The certainty of identiii cation has been
Qiirrted one revolution further back, and it is understood that
ta(>re distant epochs will be investigated. w. a. p.
Solar Activity in 1907.
Sun-tpoigL — There has been a distinct mcrease in the spot-
activity of the Sun during 1907 as compared with the preceding?
ye&r, though the level of 1905 was not quite attained. The
nusnber of giant groups readily visible to the naked eye has been
doiibJe that recoiled in 1906, ami equal to that of 1905, no fewer
than 24 distinct groups larg«^ enough to he thus seen having been
observed during the year. The chief groups of this rank were on
the disc 1906 December 29-1907 January 9, Jantiary 2 S- February
7, February 6-19, June 13-25, July 11-23^ September 24-30,
October 15-25, November 9-22, and December 5-18. The
ocy, so marked ii» 1906, to develop long processions of
mpB following each other at short intervals alon^^, a parallel of
latitude has continued in 1907^ and on more than one occasion
ihe Sun, as set-n merely through a dtirk glass, presented a very fair
imitation of a Martian "canal,*' in the shape of a long, straight
294
Seport hy the Council to the
Lxvra. 4»
The first two months of the year wer« the most disturbed,
and it is not improbable that the crest of the wave may eventijally
be foimd to lie somewhere within their limits, unless the reTival^
evident in 1907, should be still further accentuated in 190S.
Facula? were most numerous in March, which was, so far, the
most prolific month for these bright markings during the wh
of the present maximum. Two days at the end of Novemf
showed the Sun free from spots. b» w. m.
ttie
[tath 1
Proininenres.^TUe daily frequency of prominences deduced
from apectroheliu'^ram!! taken on 40 days during the year 1907 was
somewhat jjreater than that deduced for the preceding vear, also
from photographs secured at the Solar Pfiysics Observatoiy, South
Kensington. The pictures jwere taken with the ** K
(calcium) of the solar a|>ectrum, and the lower limit for the be]_
of prominences accepted waa about 20". The phottjgraphsejtamined
svemed tn indicate that for the year 1907, unlike the pierioui
year, the activity was fairly equally divided between the two
heinispheres, the (igiires obtained for the last three years beifig
as follows :—
1905* 1906. 1
North liembphere . , , 3*4 3*9 3*5'
South bemiaphore . . j^o 2*6 3*9
Total daily froqucncy 6*4
6*5
The above figures for the total daily fre<|uency indicate a lag
the maximum promitience activity behind the mascimuin of spoU^
area which occurred late in 1905, though the spotted area of 1907
will probably diow an increase over 1906,
Activity a[q>arently in the neighbourhood of the solar pole^ waB
less marked than in 1906, while equatorial promiuencea were ml
iiirrei|uent
From July i5tli to the 20th the Sun appeared very acti'
showing many high and remarkable prominences ; fortumitely g"o<i
weather allowed a number of excellent photogmpha to be obtainwi-
The visual observation a of prominences made at Catania by A.
Rkco* indicate for the first six months of 1907 a consideraMe
increase over the mean frequency for 1906. The lower limit of
height of observed prominences was 30".
i4™
North htimiaphere
South hemisphere
Total daily frequency
1906*
1*56
1907 (hisr
The distribution in latitude shows for the activity tn »9
maKima at 36*-40* atid 51*— 55 in the north solar hemispM
and 1 5*- 1 9** and 40*-'44* in the south* w. j. »..
• Memoj'U delta Socw-t^l drgli Spc« >*o*'tfpi^i liuliani, diip. 1 j,
m 1908. Elghty-elyhth Annual General Mteting. 295
Solar Bts^areh.
Tfte International Solar Unum, — An important event in 1907
wa« the Third Confereoce t^f the Internalional Unioo im Co-
operation in Solar Reaeareh^ which was held at Mend on in May,
under the presidimcy of the fate Dr. Janssen. Reports of the work
of the committees on standard wave-lengthss, snn-spot Bpectra,
soldr radiation, and spectrobeliograph observations were preaented^
and uew committees were apprtinted to deal with solar rotation
problems, and the orgauisation of solar eclip8*i work.
The re-determination of the wave-length of the red line of
cadmiam ha.s been completed by ilessrs. Fabry and I'erot, and is
in such satisfactary agreement with the iiide()6ndent reJiults
obtained by Michelson and others that it was resolved to adopt it
as the ba&is of the new wave-length tables. The work on the
secondary statidards was also reported as well advancetj, and the
I wave-length committee was authorised to issue a definitive table
^thout waiting for its formal adoption,
I The next Conference will he held at Mount Wilson, California,
Di the autumn of 1910.
Suf^Bpot Spectra, — ^Investigations of the spectra of sun-spots
have made great progress during the yean The vianal observations
which have been so laboriousi in the past have now been greatly
simplified by the admirable photographic r^ap of the spot spectrum
which has been prepared at Mount Wilson, and, through the kind-
ness of Professor Hale, distributed among the observers in this
flection of the work of the International Solar Union. Some very
tine photographs have also been secured at Kodaikdnal, and the
photographic method is also bein<^ siKcessfully employed by Mr.
Newall at Cambridge, and by Father Coi tie at 8tony hurst. The
ret'ords of the phenomena are therefore now perfectly definite,
and ex[wrimental work tending to their elucidation is enormously
facilitated.
Hale and Adams have given an account of further investigations
I which they regard as supporting the view that the modifications of
Bie metallic lines in spot apectm are to he explained by reduction of
pmperatuxe, the fiame lines beiitg strengthened while the enhanced
hpaxk) lines are weakened. Further evidence in the same direction
|l also afforded by their very siitiafactory identification of the
^rouger flutings of titanium oxide in the spots, thosu having heads
at 7054*60, 7087-90, and 71 25*89 being very strongly marked
(Ap, /., xiv, 75-94}. The spot spectrum thus shows an approxi-
mation to the third type sUirf«» of which the titaiiiimi oxide
flutings aro characteristic. An interesting paper in this connection
has been published by Father Cortie (A p. J,, xxvi. 123), who
ints out that at the maximum of Mira Ceii in 1906 the flutings
ere macb less developed than at the maximum of 1S97, when
[uitude at maximum was lower. AsRummg t\i« ^t^sX^t
296
Report by the Cottficil to the
ijnnii4,
bngbtness to be associated witb a higbpr temp^mttire, the a|4>ear»
ance of the flutings in sun-spots points to the conclusion thai the
teinpera.ture of 8un-spot.% is lower than that of the photosphere.
Many of the numerous spot " band lines '* in tbe region E to f
have heei\ identified by Fowler with component* of the fltiting ol
** ma^'iiesium liydride," the head of which la at 5211*0 (if, iV., Ixni,
530), It is probablt that this will thr«>w niiicli light 00 the dis-
continuity of the dark background of the spot spectrum, which
gives rise to the appearance of bright lines and bands. There u
evtden€e that the abaorptioii of this substance is also shown fainllj
hi the normal solar apectruni. ^1
The weakened lines in spots have received special attention fro^H
Mr. Nagnraja of Kodaikitial, who has catalogued 167 of this cImB
between F and D. In accordance with the previous observ^iiions
of Fowler, and Hale and Adams, it is found that enhanced metsdlic
lines flj^re largely among the weakened lines, and that many of
them occur as hij^^h-level Hues in the chromosphere (Ap, /., iicvi. 143),
A remarkahle feature of the sun-spot spectrum is the tendency to
disap pear ance of characteristic features in the violet and ultra-violet,
the spectrum there i^radually approximating to that of tbe ordinarj-
disc. Hale and Adams have discussed this matter in the paper to
which reference has beeu made above; and though they have reached
no explanation whit^h they eonsider final, it is suggested that tb*^
effect may be largely due to solar light diifused over the spot artf^i.
At Kmlaik&nal, ** with improved apparatus and under exceptionally
favourable atmospheric conditions,** affected lines have been
photographed in the region 3990 to 4350, but Mr. Evershed
iltiestions whether the admixture of akylighr with the spot spectram
18 a sufficient explanation of the poverty of detail Titaniutn ami
vanadium account for many of the strengthened lines in t1
region as well as in the visible spectrum (M,N,, Ixviii, 12).
Closely associated with the study of sun-spot spectra is
important investigation of the spectrum of the Suns disc near
limh, which has been made at Mount Wilson (Ap, X, xxv. 300).
It i.H found that the " wings** of many lines disappear at the limh^
and that the relative intensities of nomerous lines are changr^ri^
Ijfenerally in the same direction as in spots, though tlie weakening
is relatively more marked than the strengthening of h'nes, Tbe
further diacussiun of these results, whicli is promised, will h^
awaited with great interest.
Useful notes on the conditiouB which accompany the api^earan^e
of bright Dg over the umhnr^, and of dark D^ in the neighbourhood
of spots, are given by Mr. Nagaraja and Capt. Daunt (OAwnw/wy,
214,249).
The ,Sun*s Rotaiitm. — The spertrographic method of observing
the Sun*e rotation has been employed by Mr, Newall in nnler to
determine whether the cyanognn band 3S83 in the solar Sf>ectrtlin
ia wholly of solar origin {M.N,^ Ixviii. 2)- In the observations inadi
during August and September the band generally showed a Aovt
head at the east limb, aja U iVie-tfe -st^t:^ two bands auperpoaed,
and ,
I Feb. 1908. Eighty-etghih Annual Gerteral Meeting,
297
at the went limb there was only a slight lutenMfication, without
measurable duplieatiim. It is suggested that some cyanogen having
indep*-'iident motion nitiBt have exiateil in interplanetary space
between the Earth and Sihjj and not far from the Sun, and the
pnssible connection with the deh^is of cometa is discnssed.
The results of the fii*st systematic investij^'atioa ^f the Sun's
rotation by the spec tro^n^p Lie method have been announced by W. S.
Adams {Ap, /., xxvi. 203). Granted an apparatus as powerful as that
b^pd at ^lounl Wilson, the many advantages of the photugrapbic
^H^liod are obvious, particularly as regards the numbcjr of lines
fWhich may l>e utilised. In this iuveatigatitm twenty lines of
TarioiiB origins were selected for measnremetii, and the gt^neral
.means give 24-46, 2479, 25*48, 26*43, 2763, 2873, 29 "^3» 30*25,
:atid 30*56 days as the rotation periods for heliographic latitudes
o, lo, 20, 3o» 40, 50, 60, 70, ami 80 degrees respectively* For the
lower latitudes the vj^^lues agree very closely with the rej<ults of
Dun^^r and Halm, and for the higher latitudes are intermediatt*
between the results of these observers* A fact of great interest is
that different lines ^ive slightly different rates of rotation, those of
carbon and lanthanum showing 0*1 less than the daily rate
\ indicated by the mean of all the lines, while two lines of manganese
giTB «ystematicaUy high results.
In connection with the Computing Bureau of the Solar Union,
Professor Turner has made a preliminary investigation of the position
I of the Stin's axis, as deduced from the Greenwich snnspot measures
(ATiV., IxviiL 98). A small and possibly peiiotiic dt^parture from
the axis deduced by Carringtoo is indicated,
I The Sp^ctinheliograph, — Hecords of the calcium flocculi are
bet tig regularly made at Mount Wilson, Kodaikdnal and other
I observatories. In addition, Hale has made in vest igat ions in wliieh
' lme0 affected in sun-spots have been adjusted to the position of the
ftecond slit. In the case of strengtiiened lines, the umbras and
- penumbrse of spots are relatively darkened and the areas are con-
(oiderably increased; and definite, though less marked, results have
L^Mfi obtabied with enhimced lines. Successive pictures of the
^Heium flocculi have also been prepared for use in the stereoscope,
rSEowing the sphericity of the Sun and the apjiarent eleTation of
the fiocculi* Features which escape notice in single photographs
are brought into prominence by this method of observation {Ap.J.f
«tV. 311). A. F.
The Mofjn*s Phytdeal Libration.
Between 1898 and 1900 I)r F- Hay 11 conducted with the
30 cm, refractor of the Leipzig Ohservatory a series uf measures
I in order to determine accurately the selenographic co-ordinates of
,i a number of points on the Moon*s surface. He intended to reduce
I these on the supposition that the rotation elements of the Moon
I and the position of Mooting Aj as given hy Franz's reduction of
Mtafaltiter'a observations, were substantially accurate, lu l\i^ aout«(s
29^
Report by the Council to the
Lxvni. 4,
of hk work he fotiiid reiuoD to doubt the truth of this assail] ption^
and accordingly he uodertook s oomplets revision of the aoalfsli oo
which the reduction is based. The aim he set before him^If wu
to include every term in Hansen's theory which could produce sa
eftect amounting to 2" in selenocentric or o"'i in geocentric are,
and to carry through the redactions to this degree of accuracy.
Since the first series of observations were planned for a different
purpoi^e, and were uot suitable for determiuing the position of
Moating At or the coeflScieuts of the [principal terms in the Physical
Libration, a freah series was under taken towards the end of 1903,
in which the distance and positiou-angle of ^loeting A weis
determined on ten evenings, sometimes from as many as ei^'htesQ
points on the limb. The measures were made with a filar oticnh
meter, and the distances were so great that oonsiderable relianct
had to be placed on the driving-cluck, but tha results seem ta
juBtify the confidence placed in its accuracy.
When ilie observations were reduced it' was felt that they did
not justify a definitive delcrmination of the rotation elements, and
it was decided to make a fr3sh reduction of the similar measuns
made by Hart wig betwseu 1B77 aud 1879 with the Strasshurg
heliometer. This work has now been accomplished, and the final
results are publisheil under the title of ** Selenographische Koordi*
nttten** in Bd. xxx, der AbhamL der Math, Piiy^- Klasse der k
Sachs. Gesdt, der Wi&i*^ the previous work Imving been publisHsd
in Bdn, xxvii. and xxix. of tlie same ^ariea. The principal points
in the reduction are that greater care is taken in tha integration
of the equations not to neglect terms which would affect the resolt
to the degree Rtated, and that account is taken of the departure ef
the suiiace of the Moon from that of a 8|»hera, the amount of thk
departure being determined from the observations themselves.
The priucipul results may be. stated as follows : —
If A, B, C are the Moon's i*rincipal moments of inertia, A
being that about the equatorial din meter through the zero merid-SDi
C about the axis of rotation,
I the mean inciinatiuii (»f the Moon's equator to the ecliptie,
X, P the Releiiographid longitude and latitude of Moating A,
h the radius to thin point,
h^ ^ the radius ati4«umed in the Nautic^ AlmafidC^ = I5'54*'*ii
f/ the Moon's mean anomaly,
g' the Sun s mean auomaly,
oj the departure i>f the Moon's perigee from the ascending node
of its orbit,
then Dr. Hayn finds^ —
/-
I =
A =
A =
C-B B^
C-A
A
i' 32' 6' ± is"
-5*'o'>3"± 15
■• o'7S ± 0*04
Feb. J 90S. Mghty-eighih Annual General Meeting. 299
which correiipond ta the rectangular co-orJiiiates
f- -'08998, ^= -'05552,
whikt tbe physical lib rations are
in longitude - 12" sin g + 59" ein / + 18" sin 2ci>
itj latitude - 144" ain w + i 1" sin (*; 4* <u).
Tbe coefficients of sin g and sin g' are about hall tho^e found
bj Dr. Franz, whilst tho libration in latitude takes a different
form. Dr. Fmnz*s value of/ was o'49.
The errors given are those of mean square.
Dr. Hayn also gives the co-ordinates of four points of the first
order. Those of fifteen other points of the second ord^r are
promise*! in a fourth memoir
The libration consider<*d is that due to the forced oscillations
wltose i>eriods are determined by the configuration of the system
SuD, Earth, Moon. A search was made for evidence of free
gecilIation>«, bu^ likft previous attempts, it showed only that the
amplitudes must be very small.
Tho Berliaet' Jahrbuch for 1909 contains an ephem^^ria for
Mosting A deduceil from these elements.
But even thowe now puhlishiiJ cannot be considered definitive :
the magnitudes of some of the results depend upon an arbitrary
system of weighting adopted for the conditional equation a, and
it is imperative that «oine of the other series of obeiT vat ions, of
which there are several in existence, should be re- reduced. The
work of reducii^g those mad© by Schliiter has already been com-
menced at Cambridge by Mr. Stratton.
I>r. Hayn also piit»lisLies a provisional talde ami contour map
showing the difference from mean level at every jioint of the aurface
which can come u[)ou the limb. In 1905 he published a table of
the same kiud in Ad. yach. 4009 ; this he now withdraws in favour
. of the new table^ depending on a more complete reduction of the
same obeervationa
Dr. Hayn is to be congratulated on having brought to a
successful termination a very laborious piece of work, in which he
deals with f|uantitiea that are near the limit of w!mt can be observed.
He ha-^ considerably improved our knowledge of the riktation
elements and the contour of the Moon, and has shown how a still
further improvement may be effected. s. a. a.
Action of th^ PlaneU on the 3fffon.
In 1892 M. Radau published hh researches on the planetary
inequalities in the movement of the Morui. The past year has been
Hiarked by the publication of investigations by Pruft'ssur Newcomb*
* lDT«wtt)catioTiH of lueqa^ilittes iu the motion of the Moon |}roduced b^
th« aettan of the pUneta,
300 Mtport by the CatmcU to the LXVllh 4^
anrl Professor Brown * dealing with the same subject. A compiin-
sori of the three meii>r>ira is given by the latter ia the MunlMy
Notkes of last January. The differences between any two of the
three tbeories only occaBionally rise to quantities that coo Id be
delected by a discussion of the ubservatiuns, Tbe two later
memoirs agree in increasing M. Radau^af cot-tficient of the Jupiter
evection i<^rra by a quarter of a second, and tijerti are iustances
wh<^n Professor Kewconib differs by a tenth of a second from llw
other two. Many of thesy discrepancies are traced to their aourco
by Professor Brown in the paper referred to a,bov«.
No new light ts thrown on the observed l^ng perioil inequalities
of the Moon. A fresh discovery could only have been hofied for
on the ftupposition that M, Kudau had made an oversight of
considerable niagnitudt*, and perhaps the deepest inipre^iMn made
by the two recent memoirs is the senee of tbe excellence of
M. Uadau's original research. J p. H. c.
Double Stan,
The abbreviations used are —
M^N, : Monthbj Notices.
A.J. : Adrfmomical Journal .
A.N. : Asifononmrhe Nnrhnrhten,
LAJJL : Lick Obmrvaiory Bullefin.
A number of n«vv double stans have been added during llii
year: — ^Thua in 3/,iV.» 1907 May and 190S January, the R«t.
T, K Espiu gives 148 new i>airs, of which 78 ar%* under 5'
separation and 70 over 5". These m»ike 551 discovered by Espifl.
In L.O.B. No» 109 are 250 new doubles by Aitken, of which
54% tire under i" separation and 200 more in L.O.B. 125, Mr
Aitken's discoveries now number 1700. Mr. Hussey bring* fei*
discoveries up to 1337 by the new pHir>* in L.O.B. 127.
Measures t»f known pairs have been much the same as ifl
previous yearrt, Tbe Greenwich measures made in 1906 are ifl
M.N, 1907 November, They con lain about 150 Hou;^ it stairs ind
about 250 miscellaneous pairs. The measures of Sou the rn duubln
made with the 26-ineh refractor of the M*^Cormick Ohser valor}'
are in A.N. 4166; and in Nos. 4180, 4193 are measure.* of
250 wide pairs made at tlie Urania Obrtervatory, Copeidrtgeit
Burnham'i* measures of 200 wide pairs with the 40-itteb Ysrk«»
refractor are in No. 4209. Lesj* numerous set^ will be fuund in
* The luetpialitit?« in the motion of ihe Mtxin due to ih* dittct mM«i
of the planeU,
i Ut O. W. HUl obtamed the ^ame coeflicieiit as M. Railau, but tiiW
carrecteii his result in A. J. No. 6oo»
:^ Recheiclies couuurnaut Ita Iiu-|i^lii^s plan^tnirts dn monv^meat i^l^
Lime, Piiria Obs. Ann, {Mim.\ vol, xxv
Feb. 1908. EufUy-eighth Annual Genei^al Meeting, 301
A,J, 591 of 55 pairs with tbe Kirkwoud 12-incli; in M.N.^ 1908
January, of 86 jjairs by Rpv. T. E. Ea[>ia ; and of 4.4 pairn at the
Morrbon Observatory. Tliu meaHures of 11 00 pairs liiade at tbe
OliservHtory of Chevreuet? by M. Fannan in the years 1904-1906
lire worth s(.Hfcial notice. The uieiisures were made with a 9 J -inch
OH»ke triplet.
The idea of M» Farrnan was to bring the Cutalogues of
Flammanoii and Wilsoii-Gledinll up to dat(% and hence he supple
mentii his measures by all tho^e made of these particular stars
since 1878, and it forms thus a fair-sized volutue.
Tliere have been two pa[«erH on the jiostitioiis of the i>oles «»f
Binary star orbits. One by Prnftissoi Turner and Mr. Lewis in
M,N,^ I907 June, wliere 59 orbits are iliscussed and the evidence
foaud to slightly favour tlie view that their poles lie near the
Gxilaxj. Tbe other [laper is by Karl Bohlin (Arkir for MfiimmHk^
Ashronomie och Ff/sik, Stockholm^ Band 3, No. ig), wherein, by
making choice of the alternative [>oles^ the opposite cunclusiun is
deduced.
The orbits cainput+^d are — ^ Scorpii, 2 2173^ ^ 3*^1, ^•
Herculis in A,N^ 4169-70, and of a Centauriln No* 4189* all by
Or. Doberck, and of ft 612 by Mr. I^. Seraeuow in Popular
A fironomt/^ 1907 Deceniher.
Herr Zeipal gives parallax of ^ 443 as +"•057 in A.N, 4188,
auii Chase, in A J. 593, gives -f "'291 for 61 Cygni,
The principal event of the year in double star astronomy is the
publication of liurnham^s General Catatogm of Douhh Stars,
This title includes two large volumes : (i.) the Catalogue proper ;
{iu) Notes on the Stars in volume i. The catalogue, consisting of
350 pagi*R, contains 13,665 double stars, arranged in order of R.A*
(epoch 1880), and with the naual data for a working catalogue.
foiume ii., consisting of 830 closely printed [^ages, gives a few
elected early measures of the gre^t majority of the stars contained
in volume i., and a number of recent measures of many pairs not
published elsewhere, together with notes snflicient to enable
anyone to m;ike out a workurg catalogue suitable to his geographi-
cal position and eipiipment, a« all stai-s from the N. Pole down
to 31* South Declination are included. At the same time u pernon
wiahing to make investigations is 8Ut>plicd with complete references
which will enable him to collect all the observations relating to each
particular pair. Obviously their inchision would have necessitated
untjther volume. When various catalogues of discoveries are thus
brought together ami the pairs arranged in order of ILA. in one
^nt^nil catalogue the discovery numbers do not run in any par-
ticular ord*^r, and it becomes ditiicult to hud a pair. Professor
Burnham has, in vol. i,, a compact table, very ingenionsly arranged.
which f^.oables easy reference to be made to any pair, either in vol.
L or vol. ii. Thus, on the left hand are numbers from one up-
wards, and in the succeeding columns, under the heading of the
diaeoverer, the reference number in the ** General Catalo^vie,"
8uppotte we wish to look up fi 151 — apposite 151, imdet BvituWm^
302
Report by the Omncil to tfh
LXVtlt 4.
is the reference. ThiR tiible is not described in the iiitrriductioDy and
nifty well be overlooked. It also gives at once the numVper of pmln
discovered by any observer. The catalogue baa been published
by the ('arnegie Institute and freely distiibuted, and Profeissor
Burn ham is to be congraiulaied on the completion of so grot
mid important a work. Reviews of the work aire in various
journals ; and an appeal is made for measurfts of the wider pair*
from the Astrographiu plates. T. L,
Varialfle Stars*
The rate of disLiovery of new variable stars is well maintained
in 1907, the last number allotted officially in the A,N. being iSo»
which repreaetita the number of announcements during the year.
As usual, Harvanl College Observatory shares very largely in
this wotk^ the principal notices being as foliowa : —
n.C.O. Nuuihcr of
Cifeutar. 5ew VAriAhki
127
14
139
J 5
130
71
131
...
132
»5
'33
<5
Remnrki.
Discoireri^d in purauance of a achtme reffrretl
to below. All €xcept oue aboYt io*« U
max, Mflps 3 and 6*
In maps 51 aud 62. All lo*" 01 abovf U
max. except one.
Ill maps 9t 12, 2t» 4$, and 51, All aboft
io"5'« at iiittx*
DetAik of a group of r«sd stars near 3Vi«
From AU exjfc mi nation of aUra witli p^aliar
jipectra. All aboTe 10*".
in ma-ps 15, iS, and 27,
Independently of the above, Harvurd Colleye Ubiteixatory
Annah^ ?oL Ix. part 4, refers to 1777 variables discovered in the
two Magellanic Clouds, some of which have been previoualj
aunounci-d. Part 5 gives particulars of jo new Algol type Tariablea^
all south of decl ~ i5\
H,C\0. Circular 127 desiriljes a practical method of search for
variables of moderate brightness by superposing a negative upoD a
contact print of a second negative, covering the same region of lit
sky, but taken at a different ilate frrmi the first. These phol^*
graphs are large ; tbat is, each covers a portion of the sky aboal
30' square, there being 55 maps for the whole sky. Alreaiiy a
considerable imuiber of new variables have been brought to lig^l^
as indicated above ; and a cotitinuation of the scheme will probaldj
result in approxiuiately sweeping up ail the known vsriables of i
" moderate " degree of brightness*
Much work lias recently been done at H.C.O, in ooniinuiei
photographic observations ot kuown variable stars*
Feb. 1908. Eighty-eighth Annual Getieral Meeting. 303
This observatory has issued a Second Catalogue of Variable
^foTf containing 1957 stars, including tbose in globular clusters.
If we add the 1791 variables fouud in the MagGlknic clouds, we
get a total of 3748 known variables, of which considerably more
than half have been found at Harvard. The full and accurate
details of each star, together with a series of interesting remarks^
critical and historical, render this undoubtedly the leading work
of reference on the subject.
Vol. Ivii, part i, AnifnU HJJM,, cnntains the observatjona
of 75 classical variables of long penod, made by the " method of
Argelander," during the yeais 1902-1905 inclusive. The resulta
of the observations are also given in the sbape of dates of maxima
and minima, as well as full details of the light curves, etc.
During the past year has been published series iv. of the
Atla^ Stellarum Vanafdlium by the Kev» Father J, G. Hagen, S.J.
This fine work represents the practical complelion of the at]as,
which must be the handbook for all observers of variables. It
»s on the same general lines as the preceding series, and contains
foo variables of various types, whose minima con be followed in
telescopes of moderate size. For each «tar there is a beautif idly
printed chart, quarto size^ giving the telescopic vicinity of the
Tariable, the lines of R,A. and Dee. being in red, and a separate
list of comparison stars, the magrdtudes of which have been deter-
mined with great care. It would take up too much space here
to do full justice to thin meritorious work, the publication of
which marks an ei*och in the history of variable star research. It
may be added that series v, of the Atlas, which ha;s not been
referred to in these notf?s, and which contains 49 stars whose
minimum is below 7'"^ was pul>lished in 1906.
In addition to the foregoiu*,', when account is taken of the
work done in this country and on the Continent in 1907, it is
plain that the department ol iStellur Variation continues to occupy
«n important position in astronomical work. E. £. M.
Stellar Didrihution,
A very noteworthy addition to our knowledge of the
[larallaxes of stars is contained in the Vale Ohaervatorg TninS"
actiofUy vol, ii, pt. i, ]mblished towards the end of 1906,
An extensive list of parallaxes, all determined on a uniform plan
and with approximately the same degree of trustworthiness, is
provided. The list consists of 163 stars, the observatious being
made by Dr. Chase, Mr. Smith, and Dr, Klkin^ using a heliometer.
Some idea of the magnitude of the undertaking may be gathered
from the fact that it had l>een in progress for thirteen years. With
m very few exceptions the stars selected were those having proper
iDOtiatis exceeding 40'' per century, and not hitherto observed for
parallax. It is noteworthy that not a single parallsx exceeding
o'-jo waB foand; the mean parallax was about 0**05, ^^^ ^fetv^iWV
304
Report hy the CowncU to the
I.XVIIL4,
the resiilta appear to conKmi Professor Kapteyn'd tables of the ni«an
parallax corres pot) {ling to ^iveD magnitude and proper motion.
The deiluced valuea of tlie linear velocities of the stars are on tli«
average considerably lusher than the ineao velointies of stuw
deduced fruiu Jiiie-of-sight determiuations with the spectToecopfi;
but it is pointed out that this is only to be expected^ seeing tfaat
the iitars were specially selected ou account of their large appftwnt
motions.
At the meeting of the British AasoGiation at Leicester, Sir
David (iill devoted a larjjje part of hm presidential address to the
subject of stellar digtribution aud the structure of the universe.
Besides giving; a Ljenerul survey of the subject, his address included
some unpublished results hy Professor Kapteyn as to the distribution
of »tai-8 in s]mce and their luminoAities, revising his earlier estimate^
though not changing th**ir gc^ncral character.
In Groningeu PuUkaiiom, No. 18, Professor Kapteyn collseU
and i-oni pares all the available data as to the numbers of stan (d
various magnitudes in different parts of the sky. The diificuityof
reducing the estimates of magnitude made by the different obierycrt
to a common standard, so as to rendi^r the enumerations of stars
strictly comparable, is naturally very great, but seems to have be«ii
snccesafully overcome. The principal result of the paper is ao
empirical formula exhibiting the number of stars per square de^Tfe
as a function of the roiignittide and galactic latitude. Prof«»or
Kapteyn concludes, moreover, that, excejit in the immediate neigb-
bouihood of the Milky Way, the distribntion i»f the stars doei u«A
vary to any great ext«^nt with the galactic kuigitude. This mustbp
taken to indicate that there is little im[H>rtant clustering of the st^n
except in the Milky Way.
In Mont hi 1/ Notiret^f 1907 December, the mean distances of ll**^
stara of Groom I bridge's Catalo^me are exiimined from the standpopt
of the hypothesis of two star-drifts. Further evidence is given to
show that the two drifts must be at sensibly the same mean disisi'ce
from us, and that accordingly they must permeate one another. I^
also appears that the mean distance of these stars increases contitm
ally as we proceed from the galactic pole to the galactic eqtrat^^r* Tb'*
IS in accordance with the view that the apparently closer aggregation
of stars in the t^akctic plane is not due to a clustering of thenwrer
stars, l)Ut to the fact that additional more distant stars are viiibW
in those directions.
Professor Comstock cojitiniiea his investigations on the flolitf
motion relative to the very faint stars in Aitwnomieaf Jimmai^^^^'
591. He has now available proper motions of 149 star?, for tlw
most part between the ninth and twelfth magnitudes, derived fn?nj
doubl«^-.star measures. From these he derives a position of the stjltf
apex, K>A, 20^ DeCt +54*. The most noteworthy feature* i* il^<
high declination of the apex. Other investigators hare tv
progressive increase of the declination as fainter stars are i
that this result, derived from stars fainter than had hitherto \3«^
Cpiiftidered* is not wex^^ected. The same author contributes a pi\^
Feb. 1908. Eifjhttj'tighth Annual. General Meeting.
305
on the '* Lnminosity of the Fixed Stars " to Asironomical^ Journal^
Na 597.
Dt. K» Schwa rzachiltl {Nachriehien der K, Gesell der Wisum,
' 'ftimfrtt^ '907) i*'*^ discussed the law of diBtribiitioii of the
us of the stars. He acw^it« the recent couclusicm that thera
Asv iwo gtrongly favoured directions* of molioti, which^ when
referred to the centre of gravity of the stars, must be directly
opposite to one anotln^r. On this basis he puts forward a frequency
law» which» whilo differing only slightly from that eniV»o<lied in the
two-^lrift hypothesis, is remaikiibly well adapted for math*'mati«ftl
ment aad calculation^ and, moreover, regards the universe a» a
le instead of a dual system. A r curding to Dr. Schwarzachild'a
w, the frequency of a velocity («, /\ n?) Is proportional to
f"*"*"*"*^*^*, where A<B. This strtiids in much the siime kind
^eati
of relation to the Maxwelliau law, e~
that a prolate
spheroid doe« to a sphere; tlii^ distribution may iit fact be derived
from the random distribution hy increasing all tlie component
velocities parallel tt) the axis of x in a certain ratio. This axis
fronds to the direction of relative motion of the two drifts on
her theory. A careful analysis of theGreeuwith-Groombridge
proper motiona on the i»ew theory shows a very gatisfactury
i r-'*rdaiice between theory and observation. No anggestion ia
in the paper as to a theoretical basis for the law proposed ;
^r,-.--kirnably ftome such diHtribntioo mi^ht arise if the universe (or
that part of it which is here concerned) h:id originally been in the
form of a very elongated ellipsoid. a. s. b.
A^trographie Cltart atid Catalogue,
Additions to the publishetl Astrotjrapfiic Caialoffue have been
made during the year by the folltivving observatories : — Catania,
Zone 51* N,, o** to 3"^ U,A. ; Potsdam, volume iv,, Zone 52' N. ;
i>xford Uidversity^ volume il, confining the whole of Zone 30',
and volume iii,, Zone 29* ; Paris, vf»lume ii., Zone 23* N, ; and
Bordeaux, volume ii., Zone 16* N,, — the word ** Zone" implying in
ail cases the plates whose centres are at the declinations named,
and the stars included thertiftire lie between declinations approxi-
mately I* less anti greater. The setond volume of the Greemckh
A^trographic Catalt*gtte^ whicli cmn|*leti'S the northern cap 65
to the fHt|p« allotted to th** ri<>yal Observatory, is on the eve of pol>-
lication, HO that substantial progrean is being made.
The above-named obsetTatories buvo all published previoas
volumes except Catania, whoso contribution, though entitled voK
V* jmrt \, is the tlr^t issued fn>m that observatory. The scheme
^-^f this work follows that of the HelBingfors (Catalogue, each plate
:: taken as a unit, and all the stars it contains measured. In
olumns *»f tht^ catalogue the.^e measures are ^dven, and with
, in parallel culumns, their values wlien corrected by upplica-
inm of the plate oonstiuitet. These corrected measttt^ w^ covv
3o6
Report hy the Council to the
ixxin. 4.
verted into Right Asreuaion aod DecUnatioD, and are given for
eacli star on every plate to thou^andtha of a second of R.A. and
huiidredtha \4 a se^^ond in Deelirmtion, This b a very complete
pro;^ramme, since it makes the results at once available for com-
l^mmon with other catalogues, Init eu tails much work, and publication
is therefore not rapid. Since tlie original resolution c»f the organ-
ising committee provided otily for tlie publication of rectiJineir
co-ordinates, mo^il of the co-opemting observatoriea prefer to fii^l
puhligh simply the measures, and to leave the equatorial co-ordinatea
for later volumes.
it ap[)ear3 fmm the reports of the Colonial obaervatories thai
the measureraent of the pktea of Zones 41* S. to the South Pole
is proceeding. The plates of Zones 24' to 40' S., divided between
Cordoba (S. Ainerieu) and P<!rth (W. Australia), are being taken,
and there is prospei'L that these will be measured soon. The work
both on the Chart and Catalogue is progressing actively at
Tacubaya {10" S. to 16* 8.).
Enlargements of the chart plates have been distributed dorifl^
the year hy the Directors of the Pitris^ Algiei^, Toulouse, Bordealli,
San Fernando, Tacubaya, and Greenwich Observatories. The I
number issued from these obaervatoriea is now —
Paris 296
San Fernando
»45
Algiers 2B1
Tacubaya
23
Toulouse 147
Greenwich
736
Bordeaux 65
It is understood that tlie Potsdam Obserratorj^ does not
pose to take the chart plates 32' to 39* N., htvt that these ron«i
will be undertaken by the Royal Observatory of Belgium.
It would be unfitting to close this note without making
reference to the loss thiit the work has snflered by the death d
M, Loewy, Director of the National Observatory^ Paris, who wtt
so much associated with the International Chart of the Hcaveoi^
Four French observatories are taking part in this undertakin
and within the last few years three of them — Algiers, Bordcaiu
and Paris — have lost their Director by death. M. Baillaud, vrbff'*
sMi'ceeda M. Loewy at Paris, is the only survivor of the fouf
French astronomers who superintended the work wheu it ww
l^egun. H. P. fl*
Stellar Spoetffmopy in 1907.
New *SYar.— In last year's report, reference was made to tbn
discovery of a star exhibiting the photometric peculiarities of »
Nova. Professor E. i\ Pickering announced it (//.CO, Circular
1 2 1) as Xova VeloriiUK The spectrum had not then been obserredf
but in II. CM, Circular 131 (Ast, NacK, 176^ 255) Profeswr
Pickenng anoouuces thai ^Iva, ¥Vfc\\\W^ has recently found that its
Feb. 1908. Eighiy'tighth Annual Genural Meeting,
307
spectrum exhibits bright lines which appear to csoincido with bright
lines in the later spectrum of Nova Persei }$o. 2 1901. Many
other interesting spectra nf red stars have been found in its neigh-
bourhood.
Professor Hartinann has succeeded in photographing th«
spectrum of Nova Pcrsei No. 2 (1901) with a specially constructed
Sipectrograph* Tlie star was fainter than the eleventh magnitude.
The spectrum was obtained with S] I loius' exposure, and was found
to resemble the spectrum of the Wfdf Raf/et star (Ast, Nach.,
177. P- iij)- ,
Studies of Special Stars, — o Cefi. — ^The bright maximum of this
star in December 1906 and January 1907 was well observed by
spectroscopiatiS, Father Sidgreaves (M.iV., Ixvii. 534) ascribes the
iiJioflUal intensity of tlie maximum to weakness of tlie absorption
bandii^ which usually form the main feature of the spectrum. He
also records peculiar behaviour of the hydrogen lines. Father
Cortie (Astroph. Jour,^ xx?i, 125) discusses the bearing of recent
observations of o CHi on the question of the temperature of eun-
spots* Mr, Slipher contributes two n<>te8 (Astroph, Joun, xiv. 66
and 2J5) on the spectrum of this hUlt. He f^oints out that the
hydrogen line Ha (C)i m well as Hf3, Hy» and HS^ apjveara bright on
his photo^^raphn, and that the ab.^orption lines of Vanadium are
very strongs a fact which is well brought out by a beautifui plate
illustrating the spectrum from A 4100 to A 7000 with comparison
^|>actra of Va, Fe, and Na. Mr. Plaskett {Jour, /?.. 4. N., Canada, i.
45, with plate) gives an account of his studies of the spectrum ; his
roeasurements ui the velocity in the line of sight are in good
agreement with those made by I'rofessor Campbell in 1898. '
a OHofiut, — Mr, Newall and Mr, Cookiion {ili.iY., Ixvii, 4S2)
have discovered three absoiptiun Hw tings in the extreme red end of
the spectrum of this star. They also give results of a comparison
of sun-spot lines with marked Hues in the green region of the
s]>ectrum of the star.
fi Orinnis, — tSir N. Lockyer (Prf/c, R.S,t 80, 50) has detected
Jine^ attributable to sulphur in the spectrum of jB Orionis,
€ <7apriV<7r/n'.— Mr, iSli^ther (Astroph, Jtmr,^ xxv, 285) finds
bright lines in the spectrum^ and regards the star as likely to prore
to be a binary.
a Seorjni.—^lw Lunt (J/.iV., IxviL 487) gives reason for suspect-
ing tlie presence of tin in the atmosphere of a Scorpii.
a Boiftis. — Mr. Lunt {Froc, R^S.^ 79, 118) has found several
lines attributable to Europiuin in the spectrum of a liootis, and
dieciisses the evidence afforded by the spectrum of the solar
chfomospht're for the presence of this element in the Bun.
These careful reaearches of Mr, Lunt, originating in the de-
tection of small abnormalities in velocity deduced for special stellar
lines, afford a good instance of the way in which our knowledge of
terrestrial spectra may be helped by studies of stellar spectra.
Two lists of stars, having peculiar spectra, have been issu^ b^
Professor Pickering. The Srst (HM,0, Circidar 124, av\^ A%t.
3o8
Heport by the Courunl to the
hrmiA,
Naeh,^ X74, 101) relates to 33 stars, of wliicli 18 have 1>eeii faniid
to be variable stars; the second {H.CO, Circular 132, and Ad,
NacKy 176, 258) relates to 23 stars, of which 15 are found to be
variable stars. The long-continued success of the Harvard CoU^
observers in connecting peculiar spectra with variable stars aenrei
to emphasise the view that typical spectra are evidences of special
states of equilibrium in stellar conditions.
Variable Radial Velocity, — Notes on variability of velocity tre
given for the following stars : —
RZ Cftssiopeife Terkes Observatory Astra^th, Jour., xxt. 59
XCygni ,, „ ,,
iSCeti ,, „ „
wLeonis ,, ,, ,,
85 Pegasi ,, M , .
i9T5Eridani „
SSTgEridani „ „
23 r Ononis ,, „ ,,
4 li Canis Majoris
e Cyi,'ni
I Cygni
0 Leonis
a Draconis
U Cephei
X Carina'
t Gruis
0 Tauri
/ Tauri
7 CameloiiaRlalis
A Boiitis
3 Coronre
^ Cygni
d Tauri
i Cephei
Orbits of Spertroscopic Binaries. — Orbits have been calculate"
for the following spectroscopic binaries : —
Kiistner
it
Zurhellen
Harper (Ottawa)
Slipher
Wright
Campbell and Moore
AsL Narh. , 175, 87
>> If
173, 353
Jour. E.A.S., Canada, I 237.
Astroph. Jour., xxt. 284
L.O.B., No. 123
a Andrornedae
Ludendorti*
Ast. Nach., 176, 327
0-4
K Cancri
Ichinohe
AstropK Jour. J xxv. 315
015
fi Arietis
Ludendorir
XXV. 320
0-88
ju Sagittarii
Ichinohe
xxvi. 157
0-44
a Cariiiu'
H. D. Curtis
L.O,B., No. 122
o-i8
a Pavoiiis
,,
♦» '>
OX)I
K Velorum
11
>> II
0-19
e Draconis
»i
»i »»
o-oi
u Dracoiiia
A. B. Turner
„ No. 123
©•oi
n Virginia
Ichinohe
Astroph, Jour,, xxvi. 282
0-2S
]
Mean eooentricity
0-2$
EigJity-eighth Animal General Meeting,
log
Dr. See {M^N.^ Ixviii., current volume, 201) statea that the
^^perage eccentricity atnoQg visual 1 binaries is considerably more
^^kan twice that among spectroscopic binuries, the average value for
^Bo of the latter systems being 022.
^f Dr, Zuiheilen {Ad. NacK, 175, 246) contributes remarks on
the analytir^al iletermiQatiou of orUita of spectro6ci>ptc binaries.
JJr, Knut Laves (Astroph, Jour.^ xxvi. 164) iJescnbes a simple
graphical method based on the use of the hodngraph.
^H Standards of Wave-length, — Messrs. Benoit, Fabry, and Perot
"^C^*, 144, 1082) have redetermined the number of wave-lengths of
the red cadmium ray ib a metre. The residting wave-length of tlm
idmium ray, viz, 6438 -4 702, has been" adopted by the Iiiter-
tional Union for Solar Research as the single prin>ary standard
for spectroscopic measurements. This value agrees with the previous
determination by Mithelson and Benoit within one ten millionth
HOI
Messrs. Fabry and Buisaon (6'/?., 143, 165^ and 144, 782)
have published wavedeiigths of 115 standard lines in the spectrum
of the iron arc, between the wave lengths A 2573 and A 6495. This
work is a coiitributii>o to the plan of co-operaiion in the determina-
tiou of wave-lengths of lines, whifh will be adapted as secondary
ndards, lines at intervals of 50 Angstrom units throughout the
"tpectriim : the wave-lengths being determined by the iTiterferometer
method, as far as possible with an accuracy of 0001 unit.
Herr Eversheim {A^iroph, Jtmr,^ xxvi, 172) describes bis
vestigations in determinatirjns of secondary standards. He
ints out that his wave-lengtlis seem to be nil slightly larger than
ose of FaV)ry and Buisson, and attitea that h« ia looking for the
in of this systematic difference.
The system of tertiary standards at intervals of from 5 to 10
mits will be chosen and determined when the secondary system is
mplete. The wave-lengths of the tertiary standards will be
fbtsiaed by interpolation between the eecDodary standards with
le help of large gratings.
l*r Kayser (Astroph, Jo«;%, xxvi. [90) regartis the question of
e constmcy of wave-lengths as decisively settled. I^resumbly his
tern en ts must be taken as referring to suspected displacemetita
luch larger than those attributable to small changes in pressure.
yetP Spedrngraphic InHallations.— In the publications of the
Lick Observatory, vob ix., parts 1-3, Mr. Wright gives an intro-
luctory account of the Mills Exfiedition to the Southern Hemi-
phere. A 36<inch pierced mirror is mounted at Cerro San
[Cristobal, near Santiago, The Oassej^raiu mounting has been
lopted, and a three-prism spectrograph is rigidly fixed at the
uk of the large mirror. Mr. H. D. Curtis, who, on Mr, Wright's
Blum to the United States in March 1906, was appointed to take
fcharge of the work, gives an account of recent changes (Pub, A,S,P,y
'xiT, 227), and describes (AifiropJi, Jour,^ xxvl 256) l\\^ m^'&o^
310
Report by the Couitcil, etc.
LXTm.4,
adopted for minimising the change of focQ8 of the sikerevi mirror
in the couiae of the night^s work. A refrigerator is applied two
hour* before sunset to reduce the temperature of tlie mirror by
5* or 6* C. By thia plan the changes of focus have been reduced
trom about 25 mm. to about 5 mm, in the course of the night.
At the Dominion Observ«tory, Ottawa, Canada, Dr. King has
put the spectroscopic work in the charge of Mr. Plaskett. Great
activity is shown both in the careful preparation of the instru-
mental appliances for giving the best results {AdropK Jour,, xxv.
195), and in measurement and reduction of photographed stellar
spectra {Joitr, E.A.S,^ Canada^ voL i.). The spectrograph ia
attached to an equatorial of 1 5 inches aperture.
Measurement and Uedudion of Ohiten-atw7is^ — Papers dealii
with deter mi nitions of orbits of spectroscopic binaries are refei
to above in the paragraph on binaries.
Mr, Moore {Pub, A.S.Pac, xix. i^) gives a resume of metb
of measurement and reduction of spectrograms.
Mr. Schlesinger {Pub.Allegiieny Obs,, vol* i,) describes a method
which he baa found useful for simplifying the reduction of measure*
ments. ^
Colours of Telmmpic Binarf/ Stars. — -Sir William and La^^B
Hoggins (Astroph, Jou)\, xxv. 65) rail attention to the corrobora-
tioQ which their view, expressed in 1897, receives from Mr. Lewis's
discussion of the relative masses of llie componeufc;^ of 18 bioary
stars : ** the apparent satellite is in fact the primary of the system "
{Mem, ItA.S,, 56, xx). 8ir W. Muggins had suggested in 1897
that the bluish component of a pair might have the greater m-
and for this reason be still at the earlier evolutionary stage.
Theoreiiea! Int^estpjations, — Professor SchwarzscliUd {Noel
K. Geselhck GoUin[fm, 1906, Heft i) has suggested a thii
alternative to isothermal and adiabatic equilibrium in radiating
stellar atmoHpherea. He calls it radiative equilibrium. The
problem hv be solved is as follows : If in the Sun'a atmosphere the
various strata are regarded as simultaneously radiating a
absorbings and if convective motious were to cease, what dlstribi
tiou of temperature would have to be reached in the various straf
ill order that the observed steady flow of energy should be tfaiifr
mitt«d without furtbt^r change of tem|>erature ^ He tinds a soIutioOj
proves that the equilibrium is stable, and proceeds to show that
radiative equilibrium under certain si mpli tied assumptions gives a
good account of the observed darkening of the Sun's limb, where**
adiabatic equilibrium fails. H. F. !?*
[097
.hiflH
ting
rhe
th«
%
l9o8. Liu of Public InstUution^ and of Persona, etc, 3 1 1
■ OF Public Institltions jnd op Pilksons who havb con-
tIBUTKD TO THE LIBRARY, ETC. SINCE THM LAST ANNlVBRilAHV.
HIb Majesty's GoTermuent m Australia..
His ^lajestj'a Government in India.
The Lords Commissioners of the Admiralt}*,
The French Goveriim€nt.
The Italian Govern men L
British Association for J he Advancement of Science.
British Astronomical Association.
British Horological Listitute,
British Weights and Measures Association.
Chemical Society.
Geological Society of London,
Institution of Electrical Engineers.
M e teorolog i e al Oti i ce ,
National Physiciil Laboratory.
Physical Soiiety of London,
Riiyal (ieu^^raphical Society.
Royal Institution of Great Britain.
Royal Meteorological Society.
Royal Observatory^ Greenwich.
Royal Photographic Society of Great Britain.
Royal Society of London.
Boyal United Service Institution.
Society of Arts.
Solar Physics (Observatory.
University College, Lojidon.
Belfast Natural History ami Philosophical Society.
Binninghain atid Midland Institute Scientific Society.
Birmingham ^'atural History and Philosophical Society,
Ca m b ridge O b.^^er vato ry .
Cambridge Philosopbical Society,
Card i AT, Astronomical Society of Wales.
Chatham, Roy id Engine era' Institute.
Dublin, Royal Irish Academy.
JJublm, Royal Society.
E<iinl(Urgh, Royal Observatory.
Edinburgh, Koyal Society.
Lanca8ler» Astront»mieal and Scientific Association.
I>eeds Astronomical Society,
Leeds Philosophical »ind Literary Society,
Liverpool Astrononiical Society.
Liverpool Literary and Philosophical Society.
Liverpool Observatory.
Lid of Fuhtic Itistit tit ions
LXVIU -,
Manchester Literary and Philosophic^al Society.
Maoche^ter, Municipal Hcbool of Techwalogy.
Oxford, University Observatory,
Ku;?by Sehoul Natural History Society,
Stonyhurst Oolle>*e Observatory,
South port, Feriiley ObBt*rvatory.
Truro, Royal Institution of Cornwall.
Abbadia Obnervatory.
Adelaide, Government Observatory.
Algiers (Observatory,
Alleghrriy ObaervaU»ry.
Amsterdam, Royal Academy of Sciences.
Antwerp A*itronotnical Society.
Areetri, Royal ObservHtory.
Bae^l University.
Basel, Society of Natiirahsts.
Ilalavia, Hoyal Magneticiil and Meteorological Ohservafj
Hataviu, Royal Society of Sciences.
Berlin, German Physical Society.
Berlin, Institute of Computatii»n of the Royal Observat
Berlin, Royal Pr<iB*ian Academy of Sciences.
Berne University.
Besanyon, National Observatory,
Bologna Observatory.
Bologna, Royul Academy of Sciences.
Bombay Branch of the Royal Asiatic Society.
Bonibrtv, ilovernnient Observatory.
Bi»rdeaux Observatory.
Bordeaux, Society uf Physical and Natural Sciences.
B<jaton, American Academy of Arts and Sciences.
Brazil, Sociedade Scienlifica de Sfio Paulo.
Brussels, Belgian Astronomical Society.
Brussels, Rnyal Academy of Sciences of Belgium,
Buda-Pesth, Hungarian Academy of Sci«nices,
Bada-Besth, Koyal Hungarian Institute fur MeteorolJ
and Tern^ii trial ^fagnetisni,
Calcutta, Asiatic Society of Bengal,
Canada, tieological Survey*
Canada, Royal Society.
Cape of Good H(>pe, Royal Observatory.
Cape Town, South Aftican Philosophical Society.
Cataniu, Italian Spectroncopic Society,
Catania^ R >yal ( Observatory ,
Cherbourg, Nutional Society of Sciences.
Colorado College Observatory.
Copenhagen, Royal Danish A<%idemy of Sciences,
Cracow, Academy of Sciences.
Dijon, Academy of Sciences.
Egjfit, Survey Department,
Geneva ObaeTvatot^\
i9o8.
and of Fersom, ett%
:^^5
Geneva, Sodetj of Physics and Njitural Histoiy.
GottingetJ, Royal Observutory,
Gnttingen, Royal Society of Sciences.
(Jranftda Observatory,
Groningen, Astronomical Laboratory.
Halle, Imperial Lepold-Garoline Academy.
Hamburg OVw?ervatory.
Harvard College Astronomical Observatory.
Heidelberg, Aatro|ihyaical Obaeivatory.
Heidelberg, Astronometriachea In^titut.
Helsingfors, Central Meteorological Institute,
IleUingfors, Finnish Society of Sciencea*
India, Survey Department,
International ]>urentL of Weights and Meaaurea.
Italian Geodetic dmi mission.
Kasan, Imperial University.
Kas^tif Uiiiveraity Observatory.
KodaikAnal Observatory.
Von Ktiffner Observatory,
La Plata Observatory.
Leiden Observatory.
Leipzig, Astronomical Society.
Leipzig, Prince Jablunowski Society.
Lei()zig, Boyal Society of Sciences of Saxony,
Lick dbservatory,
Lisbun, t Jeographical Society.
I^well Observatory.
Lund, Astirniomical Observatory,
Ma*] rid Observatory.
Ma lrid» Hnj^al Academy of Sciences.
Manila, Pkilippine Weather Bureau,
Mauritius, Royal Alfred Obaervatorj'.
MelViourne Observatory.
Mention, Physical Olx^ervatniy,
Mexico, Socieda Cientifica Autonio Alzate.
Milan, Royal Observatory.
Missouri University.
^loiicalieri Observatory,
Montpellier, Academy of Sciences,
Moscow, Imperial Society of Katuralists.
Moscow Observatory.
Mount Wilson, Solar Observatory,
Munich, Koyal Bavarian Academy of Sciences.
Munich, Royal Observatory.
Kapler Observatory,
Naples, Royal Academy of Sciences.
Natal Observatory.
I Nenchatel OI»servatory.
I Nova Scotian Institute of Science-
F Oporto, Polytechnic Academy,
314
Lid of FuUic InstUtUiom
LXVI
t )tt.awn, DoniiDirm Astronomical Observatory,
* >ttawi4, Literiiry tind Scieiitific Society.
Paris, Academy of Sciences.
Pari«, Astronomical Society of France*
Paris, Astro photographic Congress,
Paris, Bureau of Lortgitude,
Paris, ] )epot of Marine.
I^aris, EcoJe Polytecbnique.
Paris, Matheuiatical Society of France.
Paris Observatory.
Paris, Philomathic Society.
Pennsylvania, Lehigh University.
Perth Obs^ervatory, Western Australia.
Philadelphia, American Philosophical Society.
Pin 1 kid el ph in, Franklin Institute.
Pola, Injperial Hytlrographic Office.
PotB'iaru, Astro physical Observatory.
Potsdam, Central lnternatit>nal Geodetic Bureau.
Potsdnm, Royal Prussian Oeodetic Institute.
Pntgue^ Imperial Observatory.
Pulkowa Observiitory.
Tulkowa, Physical Observatory,
Queensland Geographical Journal.
Rio de Janeiro Observatoiy.
Home, Italian Society of Sciences.
Rome, Hoyal Academy ihi Lineei.
St Petorsbnrg, Imperial Academy of Sciences.
Sau FertiiiJido, Obt*ervftt.ory of Marine.
Siin Francisco, Astronomical Society of the Pacific,
S t<>c k b o I m 0 bs e r v atury -
Stockholm, Royal Swedish Aeademy of Sciences.
Tacubaya National Astronomical Observatory.
Toronlo, Royal Astronomical Si>ciety.
To ro n to U n i v era i ty .
TorJoaa, Observatory of the Ebro.
Toulouse, Academy of Sciences.
Totdouae, Meteorological CommisHion*
Ton louse Observatory.
Turin, Italian Astronomical St>ciety.
Turin, Royal Academy of Sciences.
Turin, Royal Observatory.
TJccle, Royal Observatory of Belgium.
United States Coast and Geodetic Survey,
Upsala Oliservatory.
Upsala, Roval Society of Sciencea
Vienna, Austrian International Gi^odetic CominiasioQ^
Vienna, Imperial Academy uf Sciences.
Vienna, Imperial Geodetic Bureau.
Vienna, Imperial Military Geograiihic Institute.
Wanganui Aatiutiomic^l Society.
i9o8.
itml of Fer^nSt etc.
31s
Warsaw, Observatory of the Ifnperial Uui-verHity.
Washburn Observfttory.
Wiusbington, Bureau of Standards.
"Washin^aun, Carnegie lustitutiotK
^Wiishington, Navy iJepartment,
Washington, Philosophical Society,,
WttshingtoD, Sinitlisopian Instituti«'U.
Washington, United States NavaJ Obst^rvatoi-y.
West Puint, \J,S, Military Acudemy,
Yerkes Olx^ervatory.
Zi Ka- W e i As tronoui ica 1 Obser v ato ry .
Ziirich, Centml Meteorological Institute oT Switzerland.
Ziiricb, Gewletic Commission of SwitzerlnntK
Ztiricb, Natural History Society.
Editors of the '■' American Journal of Mathematics."
led i tors of tbe ** American Journal of Science,"
liter of the ** AatTonomtcal Journab"
E'iitor of the '* Astronomiscbe Nacbrichten*'*
K*litor of the ** Astronumische^ Jahresbericht/'
Editors of the '* Astrophysical Journal/'
" iitor of the " Athenienm,"
Editors of tbe " Bulletin de.^ Sciences Matbcmatiquea/'
Editor of the *^ English Mechanic."
lEditor of ** Himmel nnd Erde/'
Alitor of " Indian Engineering."
Editor of ** Nature."
Editor of ** Naturwissenscbaftliche Ktmdscbau/'
Editors of "The Observatory/*
Editors of *' Popular Astronomy."
EdiUjTof **Sirius/'
I
Dr. L. de Ball.
Prof. E, E. Barnard.
Francis Bash forth, Esq.
Count de la Baume Phivitiel.
F. E, BaxandalJ, Esq.
Sr, BentHbol v Ureta.
F. A. Black, Esq.
Dr, Karl Bohlin.
M. Bosson
Prof, M. Brendeb
Herr Leo Brenner.
Messrs James Brown k Son.
W. W. Bryant, Est^,
8. W. Burnham, Esq,
Prof. C. V. L. Charber,
Padre R, Cirera,
J, C. Clancey, Esq.
Hugh Clements, Esq,
T. Colby, Esg,
II nugn
■ T. Col
Sir G* H. Darwin.
M. Henri Des land res.
P. E, Dow son, K'iq.
Herr A* Drescher.
Prof, N, C, Dmier.
Herr S. Enebo.
Fforr Erik Fa^erbolni,
M. Maurice Far to an.
A. T. Flagg, Esq,
M. Camille Fhimmarion*
Herr J. J, Fric.
Prof. R. Gantier,
H, B. Goodwin, Esq,
M, L, J. Gmey.
D. E. Hadden, Esq,
Prof. G. E. Hale.
Prof. Asaph Hall
MaxweU Hall, Esq.
Rav. R. Harley.
22
niaL.
I^^^H
ts and of Persons, etc, LXmt 4,
Lr
316 Lid of Public Indiluiiai
WM Prof, E. Hartwfg.
Prof, a Kewcoinb.
■ Hen- K, B. Hasa^lberg,
Prof. A. A. KyUnd.
■ W. Heath, Esq
Herr J. T. W. OLm-
■ Prof. F. E. Helmert
0. T. Olaen, Esq.
■ Prof. G. W. Hill.
J. A. Parkbarst, Eaq.
^H prof* S. Hiraynma.
Prof. E. C. Pickermg.
^H Lady HugginR.
Prof, W. H, Pickeriug.
^H M. K. Jarrj'Desloges.
M. P. Puiaeux.
^P Prof. J- C. Kapteyu,
Sig. A, Kioco.
m Dr. H. J. Klein.
Prof. J. M. Schaeberle.
^K Tin 0. K)otz«
Sr. D. Sanchez.
^1 E. B. Knobel, Esq.
M, L. de Sa assure.
V M. A, I^beuf.
Prof. G. V. ScliiapareUi.
H Prof. E. Lebon.
Prof. T. J. J. See.
^H 8ii Noromn Lockyer.
Prof. H. Seeliger,
■ Dr. W. J. S, Lockyer.
Dr G, F. H. Smith,
^H Prof. G, Lorenzoni.
M. P. Stroobant.
^1 Prof. Percival Lowell.
Prof. H. H. Turner,
^H M. Loizel.
Sr. Vives y Vich.
^H Edward LjncL, Esq.
R. J. Wallace, Esq.
■ W. T. Lynn, Esq.
Mrs. W, H. Waugb.
^B G. T* McCaw, Esq.
W. H. Wesley, Esq.
■ Mrs. McCleatu
Prof. E. T. Whittaker.
^1 Mrs. MaclachJati.
W. Willett, Esq.
^H 8igT* A. Mascart.
Prof, Max Wolf.
^H M. Jeati Ma^cart.
l^rof. A. WoUer.
^1 Arthur Mee, Esq.
Prof. C. V. ZeiJger.
^M Messrs. Methuen & Co.
Estate of William Ziegler.
317
I
ADDRESS
the President, Mr, H. F* Newall^ on presenting the
GM Medal of the Society to Sir Datnd QUI, K.CB., KKS.
For the aecond time in the biatory of our Society, your
re«ideDt is called upon to jiresent the Gold Medal to Sir David
ilL By thetr award in 1 882 the Council desired t-o recognise the
lue of hia work in determining the 5solar parallax from observa-
>n8 of Mars in Ascension ; and now, after a quarter of a century,
ey have awarded the Gold Medal to hini in recognition of liis
ntributions to the Astronomy of the Southern Hemisphere, and
B other astronomical work,
In fulfilling the task which it is my privilege to attempt this
bernoon, I would begin by assuring Sir David Gill of the pleaauro
[itch tt is to Mi to liave him at Lome again among us with his
fmr nnabated. We look forward to the prospect of our having
help in our counsels for many years to come.
The terms of the Couni'ira award are wide. They cover the
P|{e range of work which Sir David Gill has accomplished during
e twenty-eight years of strenuous activity which he has spent in hia
iJacity as His Majesty^^ Astronomer at the Observatory of the
^pe of Good Hope. It would be a difficult matter to decide
bether Sir iJavid Gill has contributed to the advance of astron-
tty in those years more by his own observational work or by the
ti?e performance nf his administrative duties. Fortunately it
i3ot part of my task to try to disentangle these two aspects of
work.
Broadly speaking, by his personal labours we have auch
* vements as hia two sets of heliometer determinations of the
*allaxe8 of certain southern stars, and his three determinations of
6t solar parallax. By his administrative activity the Cape
^*«ervatory has been equlpj^ed entirely anew with modern firsU
^«8 instniments ; a vast store of astronomical material ha« been
E^dered available for the use of astronomers ; not oidy are the last
Ctiaiuiiig observations of hia predecessors reduced and pubhahed,
"-t also the observational materials collected in Sir David Gill's
Sinie are reduced and published up to date.
And, as if these duties were not enough to occupy him, Sir
^vid Gill devoted himself to promoting a unified scheme of
^etic survey of South Africa. In his latest utterance about this
*rk in his Presidential Address to the British Association, Sir
ill speaks of the great African arc on the 30^1 m^\\^\aii«
'3'8
The Presidents Address.
Ui\
He says of it that it is the dream of bis life to see it conipletal
When I heard these words at Leicester, it t^eemed to me that
they represented GiU's general frame of mind. Whenever he set
his hand to any bit of work, it became the dream of his life to
see that particuhir bit of work completed in the most compr^
hemiive way that he could attain. This frame of mind doe8 not
always meet with sympathy ; it is liable at times to rouse ktcn
opposition. Bat Gill has seldom failed to infect others witK
aomethi ug of his own enthusiasm.
In diting honour to Gill's work, we shall not in the least detract
from it if we pay the sincerest tribute to the co-oj)eration which he
has been able to elicit from many workers in many lands. WV
must not forget the devotion of his staff at the Caj>e Obfiervatory.
We must remember the liberal support be has received from the
Lords Com mission era of the Admiralty, both for increased instru-
mental eqtii[>ment and for increased staff to deal with the expanded
scope of the work, We must pay a tribute to the memory of our
late Fellow^ Frank McClean, whose generous munificence provided
the astrophysical department at the observatory. We ftha!! not
forget the services rendered by Prufess(>r Kapteyn in the Ca^
Photographir Dnrchmti^ferun^, nor those of Dr. Elkin and Dr.
Auwers in their allotted tasks in the solar parallax work, nor yet
those of Sir W. Morris and many other officetii in the gei^etic
work.
Paying tributes in this wise is only a way of recognising GillV
power of inspiring others to take part in advancing the subject
wliich it is the object of our Society to encourage,
Hii^tory ami Traditions at the Cape, —It has bo en of great intercisl*
in preparing to write this address and in trying to attune myself tv
the nature of the surroundings in which Sir David Gill has worked,
to trace back through the prefaces of early volnmea of tvh^ervatiow
and through the annual reports something of the history snd
traditions of the Royal Observatory at the Cape of Good Hope
What an enthralling history it would make for us astronomers ifit
were written by someone wlio ha«l the power of pictureaqne preseoti'
tion. ™
We should see Fallows, the first astronomer at the Cape (i8*l
1831), awaiting for three and a half years the delayed plans of f
observatory, and filling up his spare moments by opening a sell
and teaching the children of neighbouring farmers — his fee for <
lesson a load of earth, which helped to make the foundation ofl
garden on the rocky liill cliosen for the site of the observati^
We should hear of his applying in vain for permission to me
an arc of meridian.
We shnuhl read how he struggled on, making the best of
portable instruments, till the observatory buildings were fini»l
and the permanent instruments were installed— seven years afl
his arrival at the Cape. Then, after a couple of years of vig
observations, his able assistant OiptaiTj Uonald fell «ick,
Faliows would have been left alone at the work but for
i9oa
Tht PrtBidmtB Address,
3*9
itaoce which hia wife learned to render by Ukiog the circle
MadingA whiUt he waja eitgagKl with the transit It was generous
oificial help that he needeil^ htit befofe it arrived fever had attacked
him and he died in the forty -third year of liis age. It ia a sad story
of Ik brave man i^truggliiig to implant new work in a distant land,
and it shouhl make us remember the debt of help that we at home
«we U> those who are working at a iliatance from headquarters,
Next we should read of Henderson, who went to the Cape in
I S3 2 and worked there assiduou^sly for thiil«en months before he
tittered that wati of de-spair al)Out the situation of the observatory
on Snake HilL He df^acribes it as ^'on the verge of an extt»nsive
saiidy desert, exf>o8ed to the iitmo^^t violence of the galea which
frequently blow, without the least protection from trees or other
^ objects to shelter from the wind or sun, some miles from markets,
■^ops, or the bal>itation of persons with whom those belonging to
^^ke observatory can associate/' It was in such surroundings that
Henderson, with the assistance of Lieut. Meiidows, achieved those
obaervations which htive madt* his name famous. He took most of
his material back to Edinburj^di, and year by year he foiinti time, in
the midst of hU duties as Astronomer Royal for iScotland, to reduce
it all. Dor Society had the honour of publish iug in its early memoirs
fifti^n contributiooa from him deahng with his Cape observations,
including his memorable determinatioti of the parallax of a Ocntauri.
Neit we shoilld find Maclear (1834-1870) boldly coming out,
at heart a true colonist, making roads, haineysing the wind to draw
a water-supply, carting earth, jdanting trees and ri>w8 of pine and
wattle to form shelter. By exchaoge and sale and purchase of land
he consolidated the observatory property, and succeeded in getting
convenient communication with the main road to Cape Town, Of
his scientific labours, it is enough to recall his measurement of an
arc of meriilian, his multitudinous meridian observations, ^partly
reduced under his own regime, and revised and pabliebed by his
attcceasors Stone and Gill in the form of four Cape Catalogues for
the equinoxes 1840^ 1350, i860, and 1865, which deal with a total
10,766 stars. In bis rpgime, too, two equatoriais were added to
Kjiiipment, and with these his observations of corner^, nebulae,
ble Htits, and occultations were made. A new transit-circle wan
tailed.
So, at the end of Sir Thomas Maclear's directorate in 1870, when
withdrew from the observatory to live for the reni:iining nine
of his life at Mowljray, within a mile of the seene of his
labours, we should see Stone {1870-79) coming out to the
Cape to find an established home and an observatory containing a
transit-circle the facsimile of that at Greenwich. Stone was at once
eiigniissed in completing two great objects, (i) the prepiinition of
Maclear's meridian olisorvations for press, and (ii) the re observation
of the stars which had been observed by I^icaille more than a cen-
Ej before. Ho completed the latter undertaking by the formation
the Gipe Catalogue for 1880, containing the places of 124441
them stars to the seventh magnitude. Dnting Hia 4\T^\^T^\fe
320
The Pr4sidefU*i Address.
LXVUI. 4,
he passed through the presa two Cape Catalogues for 1840 and
1860, based on Maciear's observations made duriog thirteen jear&
This is in briefest outline the history of the observatory at the
Cape of .Good Hope up to the year 1879, when Stone returned to
£ngland to take up his duties as Radclifl'e Observer at Oxford.
We have seen the traditions forming —
(i) The stelhir parallax tmdition^ implanted by Henderson in
bis studies of a Centauri, and fostered by M«clear»
(2) llie geodesy tradition, implanted first in African boLI hj
the Abbe Laeaille, in vain desired by Fallows, and firinly rooted
by Ma clear.
(3) The tradition of the Cape Catalogue, implanted by Fallon
in bis first catalogue of 273 stars, fostered by Airy in bis redaction
of Faliowfl* last observations, and firmly fixed by Maclear aiwl
Stooe, — in fact, the traditions of general astronomy.
Into all this goodly heritage of history and tradition Sir DaTid
Gill entered in 1879; and looking? back upon the records of his
directorate, we find he has fostered and extended each one of the
trad i Lions he found at the Cape, and has implanted as many mm
a§ be found.
Thus by the ace 11 inula ted labours of its Directors the Cape
Observatory has grown to be an observatory of the firftt raivk, of
whicli the nation may justly be proud.
Sieliar parallax, — First and foremost among the new traditions
we must put the heliometer tradition. GilFs masterly use of this
instrument has given us those refined determinations of stelkr
parallax and of solar parallax, those observations of planets and
satellites, and triangulations of stars, that are so honouwbfy
connected with his namn.
Let me first refer to the determinations of stellar parallaies,
one of his most notable contributions to the astronomy of the
southern hemjephere. He hsis made two sets of de terra in at iocs;
the first wore made with a 4'inch heliometer. This instrument ws?
an old friend^ for he bad used it in Lord Crawford's ex|
to ]^Iaurilius in 1S74, and had also made his observations us
with it at Ascension in 1877, Gill knew he could use it eflfectivety
in stellar parallax determinations, and he bad acquired it from
Lord Crawford for this purpose. Just before he left Europf U*
take up his duties at the Cape^ Gill was fortunate enough to fiud a
young and able astronomer eager to join him in the pamlbx wort
He invited him to come to the Cape as soon as he should hare
finiiihed his studies at Strassburg. Thus it was that Dr. EJkin
went, out to the Cape in 1881. For more than two years, a gwert
in GilFs house, he took his share in GilFs labours, and made it •
labour of love.
Their programme of parallax observations was an Interesting
one. First on the list of chosen stars was, of course, a Centfluri,
Hender6on*3 star, which still retains its place as the nc*arest star in
the whole sky. Altogether nine of the most interesting stars ia
the southern heav^ua w^to included on the ol>serving list, feu
Feb. 1908.
The President's Address,
32'
Ps
stars, including a Centauri, being chosen for historical asaociations
or for eoMspicuous brightness, and five others for large proper
motiou. These 8tars were judiciously divided between the two
observers, so thai each had six stars on his list The coniparisoa
stars were chosen with great care, and in the case of the three
stars common to the two lists each observer had his Bpecial
comparison ^tars, so that we must regard the determi nations aa
entirely independent. Each observer discussed his own observa-
tions, and the results were combined in the linal account of the
research published in the Alenioirs of our Society, vol xlviii. (1884)*
The results were valuable, both in their bearing on the exact
sdutton of the problem undertaken and by the effects produced by
their attainment, for immediately after the completion of the work
Sir David Gill repre-sented to the Adiuiralty that continued research
OB stellar parallax and a new determination of the solar parallax by
observations of minor pianola were much to be desired, if only they
cotdd ht* carried out with a larger instrument provided with certain
sfcruotural improvements which experience with the small helio*
meter had sug^jjested. The Lords Commissioners promptly sane-
tiemed the addition of a 7- inch he ho meter to the equipment of the
Cape Observatory.
Regular observing was begun with the new heliometer in Janu-
ary 1888, and in the next four years an astonishing programme of
oliervations was successfully completed. It included —
(i) The complete determination of the constants and errors of
the heliometer (scale vahie, errors of the micrometer screw and of
the scale divisions, etc., involving nine months' labour).
(2) Observations for parallax of twenty-two stars.
(3) Observations of the three minor planets, Iris, Victoria, and
Sappho, for the determination of solar parallax,
(4) Observations of Jupiter*s satellites.
Gill's expectations of the nevf heliometer were fully realised ; he
satished himself that one observation made with it was of the same
weight a>^ three observations with the old instrument^ and that one
«et of observations could be made in half the time that had been
previoualy required.
The tables which anmniarihe (in vob vii. of the Annals 0/ the
Vape Observatory) tlie results for stellar parallax contain details
relating to 12 hriffht stars and 10 stars of large proper motion \
and among the 32 distinct determinations the name of our Medallist
i*i attached to j8, Elkin's to 7, Fin lay's to 3, and de Sitter's to 4.
In several instances, by way of te^t. the parallax of the same star
was investigated with both instrnmeuts, with substantially the same
results. Gill conif>leteH bis exposition of the observations by a
discussion of the conclusions to be drawn from the results obtained.
So far a« so small a number of parallaxes as 22 can be utilised for
such a generalisation, the Cape results seem to support the view
which has gradually formeti in the last twenty years namely, that
large proper motion is a safer criterion of proximit;^ of a atax \a>
r system than brightness. We have learnt from t\ie vjotV ol
32a
Th€ FresideiU^s Address.
LXVULi
Stmnpe, Kapteyn, and Ne wen tub and others to reiibse how
emphasis is to be laid ou the probability that stars differ enormia
m actual lurainoaity.
The point i^ beautifully illuBtrated by the tables which GUI ]m
dr^wn up. It must be re me ni lie red, as he points out, that the
derived parallaxes are ditl'erential nr apparent, not absolute ; for
we are not at liberty to a^^uiue that the comparison stars are
infinitely remote. The only legitimate procedure is to deal with
limiting values, which can be obtained by adopting diifereni
hypotheses as to the absolute parallax of the coniparisoii staw
iiill accordingly gives tables exhibiting the variation of the total
light radiated hy each of his pa ml laic stars (In terms of the Sual|
light), with ditlerent bypotlietical parallaxes of the com]iaris
stars, ranging from o' "oo to 0*05. It is thus made clear that
southern stars whose apparent parallaxes have been determint
would differ in bri^^htneas by about 12-15 magnitudes if they
all removed to the same distauw^ from the Sun,
The further tables which Gill gives to convert the obser
proper motions of his parallax stars into absolute velocities in mi]
per eecond afford strong confirmation that the deductions ah
actual luminoHiity are legitimate. For the velocities deduced
nearly all within the limits which spectroscopic determinatio
hitve led na t<i expect among stars.
The beautiful phi?ti)graphic reproiluctions, given in the Tolutf
of results, of the specti-a of a., Centauri and the Sun show what 1
be ei pet: ted of the astro physical de|mrti!jent which Sir Parid '
has lahuured to develope at the Cape. I will m>t attempt to refl
in detail to this spectroscopic wttrk; for though the papers pubha
by the Cape Observatory hitherto have dealt with importaJit
I>oints, we are able to gather from references in the annual reporti
thai the main forcps Jire concentrated on yet another determination
of the woiar purulhix by the spectroscopic method. We can waT
imagine the interest with which Sir l>avid (rill is looking for
to the results ol the work.
Ca/>e Cutatogueg. — Before passing on to refer to G ill's work on
solar paralliix, 1 would advert to another of Ins large cuntribui
to the astron<»niy of the southern hemisphere, namely, hia fait
fostering of tlip Cape Catalogue tradition, Meridian work mti
necessarily form an important part of the work of a large nation
observatory. At the ('ape much of the energy of the staff
always lieen devoted to this branch, and the result is a series 1
catalogues of stfir jilaces which have a special v«hie.
When Gill took up hts duties at the Cape he found that,
8pite of the intiefatigable zeal of Mr, Stone, there were two item
(1849-52 and 1S61-70) of valuable observations of Sir Thau
Maclear which ^till remained to be reduced and publisbect Sti
had already Ijpgun the reduction of the observations of the
period, and CiJl made it one of bis first duties to complete and
revise the red'ictinn, and in 1884 ^^® Cape Catalogue of 4$lo stal*
for 1850 was* published. The last remaining perioii (1861-7^) d
Teb. 1908.
The Presidmit*E Address.
323
Haclear'a observatiuns was dealt witli by degrees, and in 1900 the
C^pe Cutalogtie of 1905 atara for i865'o was puhiislied. W© can
well iinder.'^tiitid with what satisfaction the completion of this work
was hailed. The preface contains the following remark: — *'The
publication of this catalogue marks an epoch in the biaiory of the
obeervatory. For the first time in tliat history the Director can
feel that the accumulated labours of his predeceasors are available
for the use of astronomers, and thut the work being done under
^18 oWD direction iii in a healthy and forward state of reduction
^^d publication/'
^B The hrst catalogue for which Sir David Gill ia solely responsible
^Ba catalogue of 1713 stars for 1885*0 publtHhed in 1894; the
^Hrt ia a catalogue of 5007 stars for 1890^0 published in 1898.
^K 1906 two more catalogues were published, un aehiHTement of
^TOich the meridian circle department might well be proud. One
ia a catalogue of 8560 astrographic standard stars for the equinox
1900, to serve for the Cape section of the Astrographic Catalogue.
iThe other is a catalogue of 4464 stars for the equinox 1900, based
^^observations made between igoo and 1904, and containing, intev
^tjioy the results of Cape observations of 2798 zodiacal stars which
' irore entered oa the list circulated by Sir David Gill, and adopted at
the Paris Conference in ! 896 as a list of stars suitable for reduction
^t heliometer observations of planets, etc. In this connection I
^uiy refer to another large undertaking. Since 1S97 all the
^■|>oaitioDs of major planets have been observed with the heliometer
flSthe Cape.
The transit-circle, which has been in use since 1856, was carefully
fe:)vated in 1885. The instrument is similar to that at Greenwich.
iah I conld have inchided in these remarks reference t<» a fifth
____dogue, which will deal with other observations, already on the
way to compk'tion at the time of Sir David Giirn leaving the Cape,
We ahall look forward to it with great interest, for it will contain
I tbe results of comj^iarison of the old and the new transit-circles at
H»Cape,
^H Gill has laboured to embody in the new transit-circlo, which was
^Kcted in 1901, many new features which were designed witli the
^H)ect of making it possible to detect or eliminate all asoertaimible
^Birces of error in observationrt of fundamental stard*
^^ In connection with his efforts to probe into these refinements
<A observational work, I would recall to your memory his careful
diacossion of the meridian observations made for the reduction of
hie heliometer measures of Mars at Ascension. He then definitely
discovered that curious variation of personal equation known as
, 4be magnitude equation. In virtue of this troublesome peculiarity »
^^ransit observer watching the passage of bright and faint stars
^Ber a wire records the transit a litLle later for a faint star than for
a bright star. The result is that the right ascension interval
Iween a faint and a bright star is a little too large when the
^ht star leads, and is a little too small when the faint star leads,
effeet is a small one, but is very tronbleaome in caa^^^Viftt^
The Presidents Address,
IXVin»4r
great refinement is needed in star places : the trouble is aU the
greater becaneiie the luagmtude of the effect varies appreciably among
diflerent obeerverg.
Sir David Gill has introduced in the Cape Catalogues, e.g. that ol
Astrographic Standard Stars for i90O'o» corrections for aiagnitu<i>>
e<juati«>n applied se pa lately for each obaerver. The latest conlri-
butioti to the experimental study of the efiect ia one made at tbe
Cape Oliaervator)', and coniniunieated lo our Society last April. The
authors, Sir David Gill and Mr. Hough, discusa therein the results
of a comparison of right RBcension differences measured in three
independent ways — (i) with the old transit method, (2) with ik
new tninsit and travelling wire, and (3) with the heliometer. The
results show that within the range of magnitudes (jA-Si) of the
stars observed, the nirtgnitudtj equation is barely appreciable with tbe
new tran»it-circle fitted with tbe travelling wire.
Cape PhotO(jraphic Durchmuiiterunt^, — I turn now to remind jou
of another great undertaking which we owe to the initiative of our
Medallist, viz, the Cape Photographic Durchmu^terung, There is
scarcely need for me to refer to it in any detail, for the histor)'
of it nnist be vivid in your memory from the account which
Dr Glaisher gave of it in presenting the Medal to Profeseor
Kttpteyn in 1902. The Cape Photographic Durchmttsfemng aro«
out of the success which Gill achieve" i in photographing the
comet of 1882 ; he saw the beauty of the many star-images thai
appeared on the photograph down to the 9th magnitu<le, and soon
afterwards he proved that large [>hotogmphic cfimeras could k
effectively employed for constructing photognqihic star maps. He
proceeded forthwith to secure the systematic photograph ical survey
of the southern skies, and gave us what may be briefly described
as an extension of the Bonn DurchmtHifertiJtg to the South Pole,
Ka[)teyn^s measurement and reduction of the plates remains a
splendid instance of scientitic devotion. It gives us, under tbe
title of the Cape PhotograpJw- Durchmusterung^ in three Isrgr
volumes of the AiinaU 0/ the Cape Ohnervatory^ the approximate
places and magnitudes of 454,875 stars, — in fact, a catalogut!
of all the stars down to the 9 J magnitude, and most of tboee
to the lotli magnitude between declination 19° S. and the
^outh Pole. This survey hsis not only served admirably for a
*itudy of stellar distribution in the sky, but by the industriow
co-operation of Professor Kapteyn at Groningen and Mr. Innes>t
the Cape it has also led to the discovery and study of many
variable stars, a fact which is attested by observations recorded in
the fourth volume, containing the details of the work of revision of
the CPM,
AeiTograpMc Chart and Catalogue, — The present year is llif
twenty 'first anniversary of the inception of the Adrographic Chari
and Caialogue. In the original initiation of this scheme fi
intfrnational co-operation Sir David Gill took a deep interest ftD^i
also ti large share. Admiral Mouchez, by whose tact and eneti:}
tbe iiiitiaL steps of promoting' the harmonious co-o{:ieratioD oi
Feb. 1908.
The President*^ Address.
325
eighteen observatories in different parta of the world were
auDcefisfuUjT oond acted, has testified to the fact that Criirs 8uccea»
in photographing the comet of 1882 opened the way to the Chart,
for it provetl that we had reached the point of beinf^j able io
construct tlie chart of the heavens by phfjtot;rnphy. The skiJl of the
Brothers Henry, not only in developing the construction of object-
glassea large enough and suitably achromatised for stellar photo-
graphy, but aUo in producing their superb photographic star charts^
was probably the decisive factor in the aecepUnce of the plan
agreed iij.Hm in 1887,
The Cape Observatory at once became one of the eighteen
contributories to the scheme ; the zone - 40** to ^ ^2'' was allotted
aj» its portion of the sky. The astrographic telescope made by
Sir H. Grubb arrived at the Cap»e in 1890, and after mme
alterations and experimental researches the work was begun in 1893
and has gone steadily forward » Bj the end of 1897 the required
1512 catalogue plates had all been oblnined and nearly half of the
chart plates. In the following year it was decided to re-photograph
the whole zone for the catalogue^ irj order to bring the epoch at
which the plates were taken nearer to that at which the comparison
«tars were observed on the nieridian. This plan also rendered it
pof^aibie to determine with sufficient accuracy the proper motions
of the reference stars in the numerous instances where no meridian
observations existed previous to the epoch of the latest Cape
observations.
In 1900 Sir David Gill undertook, in addition to the zone, to
photograph the area within 2° of the South l\iU\ oiigimdly allotted
to the Melbourne Observatory ; it will thereby be possible to
combine the photographic work with the Cape heliometer triangula-
tioQ of thin region, and w^ith the results of the Cape discussions of
all the nieridian observations of southern close circumptdar stars.
The measurement of the plates was well started in 1898, with
the aid of a new type of nieasuring apjmratus dojiigned by GUI
{M.N., lix. 61); a second measuring instrumeut of tlje same type
was afterwards added ; and at the time of Sir David Gdfs
retirement from the directorate in February 1907 he was able to
announce that 1086 out of the 15 12 catalogue plates had heea
measured. It is thus seen that the zone undertaken by the Cape
Obaervatory is well on the road to cora[detion.
Solar Parallax. — In these days, since the discovery of minor
planets with peculiar orbits like that of Eros^ it is not easy to apeak
of the older methods of determining the solar i parallax in such a
way as not to appear antitjuateiL Yet, in ti retrospect over the
griifcdual development of the methods, there are pointt^ of great
interest.
It ia just half a century since Airy summarised his views of the
relative values of available methods of determining the solar
parailax from observations of Venus and Mars. His summary
wad given by way of calling attention to approaching favourable
op[»oiitiona of Mars in i860, 1862, and 1877, and the t>^o lTTu:i&\\& ol
326
The Presklenfs Address. *
LX1
Venus in 1S74 and 1882- He preeaed on the atteniion of
astronomers the importance of observing Mars; io fact, he fmtnmed
up strongly in favour of the Mar« method, but at thi5 m^ma tim-
be urged that the future astronomical public wutdd not be ^tit>r
unle88 all practical use were nmde of the transits of Venu»
It is eas}' to criticise after events, hut looking baek, with 01
present knowledge as to where Miecess lies, we cannot fail to l*e
sitruck with the statesmanship which Airy showed in hioking fir
ahead and calmly reviewing beforehand the broad chanceu of
«iii'reiis in attemptH to utilise special opportunities for the setlV
ment of astronomical problems.
Airy's Rummary reads as if he had been trnly a seer of what
to be, but also as if he hardly had the courage to let so unconim<
an occurrence as a transit of Venue pass Vjy without making
observations. His view was tliat Mars, approaching within 04
unit of th« JCarth in favourable opposition, would give better
values of the Sun's parallax than Venus.
Gall«^ of Bieslau proposed in 1872 that instead of Mars oneot
the minor planets would be more suitable, on the j^ronnd that ihe
smaller <lisc of sncb ft phuiet would more than make up fur the
greater distiince from the Earth. Galie favoured obKervalicns in
both hemispheres. Airy seems rather to have thonght of oViscrta
tions to be made at a sin^jle <d)serTatory.
It was Gill's fortnne to liave learned at Dnnecht ObA^rval^n'
to appreciate the worth of the heliometer ;is an instrument of
preciftiou ; he yaw timt in apj'Iy the heliometer to observatiunjs for
solar parallax was the gr&at ojiening- Throufih many of the yetni
in the '70'a he worked at this problem. At Mauri tins, whither h*-
went in 1874 with Lord Lindsay to observe the transit of Vei)«>,
he made his heliometer measures of the minor planet Juno. At
Ascension, in 1877, he used the heliometer to observe Mars, and hifl
discnssion of the ribservations gave results of high importance^
Still (Sill was unsHtisfied : tlie size, colour, and phase of ^lars made
observations and discussion not perfectly satisfactory. The dreum
of his life would not be accomplished till lie could dekermifle
the 8olar parallax afresh from observations of mmor planets with a
large helionietbr.
He contributed a broad discussion of the other avatlibfe
methods in a series of papers communicate^ to Thr Ohgerratortf in
1877. He summed up in the sense that the minor planet ufethod
promised a completely satisfactory solution of the problem. TI
conviction was only deepened by the results of the helioroi
observations of stellar parallax to which I have already referred.
Lookiuj^^ forward to available 0 importunities. Gill found
Iris in i888 and Victoria and Sap[dio in 1S89 Avould be exceptJi
aily favourably placed ; and being assured of the co-operatiott
Elivin at Yale, the work was imdertaken. 1 have already all«'
to the prompt response of the Admiralty to Gill's request fi
7-inch heliometer for the execution of the project.
The employ meul ol t\\e diurnal method at the f^apo
rin0
Fek 1908.
The FreddentU Address.
32;
completely satisfactory, nor was the transport of the observer audi
in^trtitneiit to suiue equatorial station curapatible with Gill's other
riatits. The only course ojieti was to combine the southeni befio-
lueter observations with corresponding obftervaiions in the northern
hf misphere. Hence the co-operation of the directors of the obser-
vatoiies that pos^eg^eil heliometars — viz. Yale, Leipzig', (Jottingen,
Liaiuberj*, and Oxford (RadclilFe) — was invited and promj4ly
giveu»
Methixl^ were devised to meet the case of the enufbiynient of
beliometers in dillerent bemispberes. To tbis end the conipariaon
rs were aa far as possible selected so that when the planet was
ateil at the greate^it zenith distance at which good observationa*
ean be made (that is, when tlie parallax factor ia the greatest
attainable), the two comparison stars should be situated one above
one below the planet. In this way the determination of th»
^nllax is made to rest upon difft^rences ijf two nearly equal
distil ucea nieuKured by means of the beliometer.
SpeciaJ attention was directed tti the important point of
arranging matters so that the observations themselves fiirnisb the
matetriid for tlie determination and eliminatifm of the crT4>rs. The
method was to lie, so far as praeticrtble, **selfH;orrecling." Errors
of scale were eliminated by selt^'ting stars nearly equidistant from
the planet ; errors due to pHrsonal habit of the observer wore
inimised by the use of a re veiling prism inserted bt^tween the
epiece and the observer's^ eye, so as to bring the apparent
direction of sepamtion of Uie images always iuto the eime position
with reference to the vertical. The same t'omi>arison stars were
i»ed in both be mi spheres, and thus error's in the a rl opted positions
of the stars were tfliminatecb The cunning clioice of the comj»ari8on
fltan alon^ the course of rht* three pbuict^ is vv«^ll shown in the
charts given in the volumes vi, and vii. of the Annah of the Cape
Oh^t^nHiioTif, whi^h contain the full acconnt of the observations.
For the meridian observations of the sUirs the co-operation of
maiiy different observatories was asked for, and Sir David Gill
summed up the situation as follows:^
** The wide-felt scientific neeii of such an undertaking may be-
assumed tt> be demonstrated by the fact that almost every
astronomer who was appealed to entered with heart and soul
into bis allotted share of the work, and probably no similar
ftHtronondcal undertaking baa ever btdore received such universal
and powerful co-operation."
Twerjtytwo observatories co-operated. Altogether 9620 nbaer-*
vations of J15 ^tars were utilised ; they were tliscussed and
combined by Dr. Auwers, who a Wo visited the Cape and took part
in the observations of Victoria, From this able and thorough
-** -n^^ion of the meridian observations, coupled witb the helio^
t triangulations, the places of the comparison stari^ were
.i» nved witb unusual aecuracy. Dr. Auwers also reduced the
760 meridian observations of the planets and derived a value of th%
aohir paniUux, viz. 8"*8o6±o"'03, a value which agrees ^e\\ vrvXXv
328
The President's Address,
LXVnL4»
that derived from the beliometer observations, though it is of miu^b
smaller weight.
The resulting heliometer determi nations of the solar pAraUax
urere —
FiHjm Victoria, . . 8*8013 ±00061
„ Sappho, . 8-7981 ±0*0114
„ Iris, . . 8*8 1 20 ±0*0090
Mean,
8*8056 ± 0*0046
— three independeot determi nations which agree witbiu the limita
of their probable errors.
Geodesy. — At a meeting of th<; British Associaiion in Boath
Africa (Report B. A.^ 1 905) Sir David Gill gave an account of Tit
another eotirraoua piece of work which has been carried out under
the influence of his far-seeing initiative. He records how he fell
thut one of the duties laid on him by the traditions of the
observatory and the labours of his predecessors wa*? to interest
himaelf in the geodetic aurvej of the colony,
Lacaille had measured au arc of ij** northwards from
Town in 1 752. The result showed that this southern arc ind
u figure of the Earth un ay m metrical al>out the equator.
Nearly a century later (i 84 1-48) Maclear revised and extende'l
I^acaille's arc to 4^'. His result showed that the arc measured wa^
within narrow limits, t'onsistent with a hgure of the Earth that
eatbibited no ditference in the northern and aouthern hemisphe
Lacaille's contrary deduction was found to be mainly attribuub
to a large local disturbance of the direction of gravity at oue oft
termiDal Btntiun^.
Soon after his appointincjit as Aatnniomer at the Cape, Sir Daf
Gill laid before Sir Bartle Frere, then Governor of Cape Colon _
a proposal to create a system of jjeodetie triangles as a basis for ^^
future accurute survey of the colony. It was a fortunate con-
currence for the colonies and for geodesy that these tw^o men— lh«J
one with fiis experience of Icdiiu) iidministratit>n and hisknowledg
of the requirements of the coluny, and the other with his scien(i|
weight and practical enthusiasm — were able to deal with th
question. After many administrative diffieultiea bad been ov€^
come, the actual work was begun in 1883. Thus was iuauguraidd
a survey which must be an enduring benefit to the colonies, fof
alrt:ridy troubles and litigation were beginning to arise fruiu
incompatible surveys over small areas. The survey is founded
upon a complete principal triangulatian laid down with scientific
accuracy. Thia could hardly have been achieved but for ti»f
initiation of Sir David Gill and the splendid devotion of » '
Morris, RE. (now Sir William Morris), who was in charge >
field Wiirk, ably supported by Lieut. Laffan, R.E,, and other ofiicen,
Step by step the get^detic survey has btien extended, alwiyi
under the scientific direction of Sir David Gill. A» astronomers 1
may perhaps \^ aWoweA im tbe moment to loae sight of
Feb. 1908.
The Presidents Address.
329
prmctical advantages accruing to the colonioa^ and to coQcentrate
atteutiou 00 the geodetic tispect of this great work.
The surveys of Cape Colimy iiQ«i Nate) were completed in 1S96,
iadudiiig a rediscusaion of Matilear's triangulation [Geodeiic Survet^
0/ South Africa ^ vol. i.), and a new reduction of Bailey^s survey
1 85 9-^62 (vol. ii.). Rhodejsia was then begun in 1S97, and the
triangulation was carried from near Bulawayo (iat. 22"* S,) to
within 75 miles of the southern end of Tanganyika (8" 40' B-).
Next, io 1902, the principal triangulation of the Transvaal and
the Orange BiverColcmy was undertaken, under the superintendence
of Sir W. Morris, iUll being responsible for the initiation of the
work, and acting as scientific adviser. The field work was nearly
completed iu 1905, and tlie trained parties were just about Ui be
diaWuded. Sir David Gill realised that if this occurred there
wauld be a gap left between the Limpo]>o River and Bulawayo
in South HhodcHia^ with little likelibood of its being completed.
But his energetic persistence succeeded in securing support by
the intervention of Sir George Darwin, whereby the relatively
small link of lao miles in the chain was made good, ThuA the
triangulation is complete from the southern extremity of Africa
DAarly to the southern end of the German Protectorate, an arc
of 25* in ktitude.
It is to bt^ hoped that the German Government will be able to
continue the measurement of the arc along the eastern shore of
Lake Tanganyika on German territory ; all the more so Itecause, by
yet another instance of Sir David Gill's energy, the measur<?mtnt of
an arc of iV to the north of the Uerumn territory ia now bt'ing
carried out.
The delimitation of the Anglo-German boundary between
British Bechuanalaml and German South- West Africa along the
20th meridian gave rise to some temporary dirticultiea in 1896, Sir
David Gill was in England at the time, antl was consulteil by the
Colonial Ofhce. His knowledge of local conditions was invaluable ;
he received instructions to proceed to Berlin, and there he was able
to arrange an agreement satisfactory to both of the Governments
concerned, and the di recti* »n tif the work was placed in »Sir David
Gill's hands. Buaman*« longitude arc across Bechuanaland to the
20th meridian was connected at both east and west ends with the
geodetic circuit in Cape Colony.
This great system of triniigulution pervading South Africa will
eventually give geodetic results relating to three considerable ares
of meridian : —
First, the arc along the meridian of 19* E. longitude, with an
amplitude of 12^,
Second, the arc along the meridian of 26'' £. longitude, with an
amplitude of 8J*,
Third, the great arc along the 30th meridian, with an amplitude
of 25*.
As far as the reductions are completed, it would appear tkai
ibere is bat slight deviation from darkens elements oi OaQ ^^Mt«; <>l
330 The Presidency Address. . uqau. 4*
the &rtb on auy of these n^ridiaiis. But in the eecmid and ihiid
there seems to be evidence that the astronomical amplitude exceeds
the geodetic by a small fraction of a sectond of arc per degree.
From the north, preliminary operations hare already been began
by Captain Lyous of the Egyptian Survey tg connect Cairo with,
the southern triangulation.
Sir David GilPs dream will be realised when, by the junctkm
of Cairo round the east shores of the Mediterranean with Greece,
and so with Struve's arc, the North Cape in lat. 70" N. is connected
by triangulation with the southernmost point of Africa, lat 35* S.,
an arc of meridian 105** in length.
My task has been a difficult one. Wisely or unwisely, I have
attempted to set before you the broad lines along which Sir David
(jrill's achievements lie. In doing so, I have had, perforce, to leave
many points of interest and importance untouched, even at the risk
of seeming to fail in doing justice to his work.
I hope I have been able, however inadequately, to make clear to
you that the recognition of the Council has fallen upon wnik of
extraordinary scope, not only in administrative activity, but also in
investigations of high refinement and permanent value.
Sir David (Hll, — In presenting this medal to you, let me say that
we know tliat for yourself the successful achievement of your tasb
is the highest reward. But we could not deny ourselves the
satisfaction of recording our appreciation of the mark which your
labours in a distant land have made in the advance of astroDomy.
Let me convey to you the hope that your well-earned leisure may
be filled with continued study of the science which you love.
*eb. 1908. Election of Officers and GowncU. 33 1
The Meeting then proceeded to the election of the Officers and
k>uncii for the ensuing year, when the following Fellows were
lected : —
President,
H. F. Nbwall, Esq., M.A., F.R.S.
Vice-Presidents,
Sir David GIL^ K-CB., LL.D., D.Sc, F.R.S.
Major P. A. MacMahon, D.Sc, F.RS.
W. H. Maw, Esq.
H. H. TuRKBR, Esq., D.Sc, F.li.S., Savilian Professor of
Astronomy, Oxford.
Trecustire^;
Major E. H. Hills, C.M.G.
Secrefaries.
Thomas Lewih, Esq.
S. A. Saundkr, Esq., M.A.
Foreign Secretary,
Sir William Huogins, K.C.B., O.M., LL.D., D.C.L., F.K.S.
Council,
Sir W. H. M. Christii:, K.C.B., M.A., D.Sc, F.K.S.,
Astronomer Royal.
Bryan Cookson, Esq., M.A.
Rev. A. L. CoRTiB, S.J.
P. H. Cowell, Esq., M.A., F.li.S.
A. C. D. Crommelin, Esq., B.A.
A. S. Eddington, Esq., B.A., M.Sc
Alfred Fowler, Esq., AssisUmt Profesj^or of Physics, South
Kensinj^ton.
J. W. L. Uij^iSHER, Esq., M.A., ScD., F.R.S.
J. A. Hardcastle, l^q.
A. R. HiNKs, Esq., ^r.A.
Richard Inwakds, Esq.
K B. Knobel. Esq.
2?)
MONTHLY NOTICES
OV THH
BOYAL ASTRONOMICAL SOCIETY.
LXVm.
March 13, 1908.
No. 5
F. Nkwall^ Emi, M.A.. F.R.S., President, in the Ctiair
Frederic Herniann Albeit Alfred Buss^ 2 Lansdowrie Terrace,
Groftvtiiior Square, Ashtfrn-on-Mrrsey, near Manchester ;
frthtir d« Pr<^ Denning, M,Sc., Ph,D , Birmingham University,
and 18 Lijihtwoods Hill, Btrminghum ;
erbert Shaw, A.K.C,S , Royul College of Science, South
Keiisingtnti, and 6 Go wan Avenue, Fulham, S.W, ; and
iianief^ Henry Wortbingti>n, Student iji the University of Oxford^
Bindon, Wellinyti^n, Sunierset,
k balloted for and duly elected Fellows of the Society.
The following candidates were pro|>oaed for election as Fellowa
be Swiety* llje names of the pn^pust^rn from personal knowledge
; appendetl :—
[Captain Kichard Algernon Craigie Daunt, D.S.C, Lynalta,
Newtownarda, Co, Down, Ireland (prt^posed by Rev. A. L.
Cortie) ; and
figar OdwII Lovett, Ph.D., Professor of Astronomy, Princeton
UuiverHiity, New Jersey, U.S.A. (proposed by J, W. L.
Glaisiier).
)ne hundred an<l four presents were annoiiuee<l aa having beeo
^ve«i since the laat meeting, incln^iing, amongst others: —
!. Jarry^Desloge^, Observations des surfaces pi an^taires, fasc. 1,
ented by ib«* author ; K W. Mavinder, The Astronomy of the
Hie, prcsenti*d by the author ; C. H. F. Peters, Heliogra\Avwi
'^ona of Sun-apols, 1S60-1870, edited by Professor ¥toat., i^itei-
334 ^^- -^ ^' Knobd^ On the AticiefU Jewisfi LXvm. 5,
sented by the Carnegie Institution ; J. A, Re[>Buld, Gesehichte
fler Aatronomiflclien Meaawerkzcnge, presented by Mr. Franklin-
Adams ; E, B, H. Wade, Field method of determining longitude.*
by observtitionH of the Moon, presented by the Egyptian Sunrej
Bepajrtnient.
Afltrographic Chart; 32 charts, presented by the Boyal
Observatory, Greenwich ; 20 charts, frgm Algiers aiid Parw
Observatoriea, presented by the French Government ; ami
charts, presented by the San Fernando Observatory.
Series of 36 collotype reproductions of photographs of
Milky Way, etc., presented by Professor E. E, Barnard ; pbi
grapb ui the Nebula in Orimi (transparency) from negative taken
by Professor Perrine with the Crossley reflector, presented by %ht
Lick Observatory,
I
A mggetttd explanation of the ancient Jewish CcUmidar Data in
the Aramaic Papyri translated by Profesmr A. H. Sniftt
atid Mr, A, E. Cowley. By E. B. KnobeL
The Aramaic papyri discovered at Assuan, on the site of the
ancient Syene, wliich have b^?en recently translated and puJilijihed
by Professor Sayce and Mr. Cowley, are of unique interest iiid
importance owing to the duplicate dates j^iven to each documejiL
These documents cover a large part of the fifth century b,c,>
extending from b,c. 47 i, nine years only after the battle of Sakmj*,
to B.C. 410. The papyri all r*date to a Hebrew colon? establisbal
at that period at Syene, and deal with rights of property, cooveyatjc^!
of land and buildings, marriage poriious, and legal processes. Tbtj
are all deeds most carefully drawn, signed, sealed, and wituessf^it
and they are dated accordiriij to both the Egyptian and Hchi^»
calendars, in the regnal years of the kings of Persia,
The Egyptian year and calendar are well understood, They^r
was a vague solar year, and consisted of 365 days without int^r
calation nr correct Jon» consequently the Julian date of ihv com*
mencement nf the Egyptian year recedes one day evei-y four y«i«<
The year consisted ol twelve months?, each of thirty day^, and Hv<f
additional days, called epwjomenm^ were ailded after the last month-
There is consequently no diflictilty with this calendar in determiiiifig
the correspoiidiing Julian date.
Very little, however, is known of the Jewish calendar in uwt*
the period under consideration. The present reformed calendar
diti.es only from tht^ time of Hillel in the fourth century ap^.
though it was probalily not finally settled until after the fifU*
ceniury. It is known that in olden times the year was a Innif
year, and certain mouths, and ordinances connected with ^^
moil I lis and seasons, are mentioned in the Old Testament, Tbc^ri*
id no mention of an mleTeeX^t^ m^uNJcv \5x the Bible^ and it is 00*
Mar, 1908, Calendar Dates in ihe Aramaic Papyri.
335
^Blown whether the correction to the aoUr year was applied iii
ancient times by the additiim of one inonih in thn-e yeai's, or by
the adding of texi or elevea days at the end of each yt^ar. No
^Bformatioti appears to exist that there was anytliing like a settled
Jewish calendar 80 far back as the ht'ih ceittnry B.a
It is very generally stuted that pfior to the adoption of the
reformed calendar the Jews emphiyed the era of the Selencidw,
the jearn of which were Jtdian of 365 days, bnt this could not
liave been the case at the periud under discussion. BiirBaby*8
work on the Jewisli calendar gives little as^intance in the preijent
Ivestigalinn.
Mr. Miirgoliouth — a high autliority — writes: ** No lists of pre-
iirisiiiin Jewish dates reconciled with Egyptian or other dates
e 80 far available to throw light on the exact form of the calendar
QAed for the dating of the Aratnuic duciituenta publiished by
Profes^sor iSayce and Mr. Cowley. In the fifth century B,a the
Jewish calendar depended entirely on the observation of the Sun
and the Moim, particularly the latter. The decisions must have
been made by a central court, as was prictically the case down to
359 A,D., 80 that great uncertainty would be caused in distant parts
(such as Syene in Upper Ei^ypt^ tt> which the papyri belong) by
the delay in transmitting the announcements,
"It is aliio nncertain whether the Jewish lunar year was in
ancient times hannonised with ihe solar year by the addition of
oivi? month in three years, or by lengti^ening the bxst month in each
year. The difficulties connected witli the dates given in the recently
publi4»hed papyri may l^ossiblJ have to be ascribed to the un-
certainties mentioned/'
Professor Schiirer has discussed tlie subject in the ThmtogiseiiB
jUeraiurzeihmff fur Fehrnary 1907, in which he claims that the
[lyri confirm the fact that the Jews began their months with the
trance of the new moon, and further that they show llvit ** it
far from th<? cuse that any dehnile systHm had been adopted/^
I)r, Lidzbarski has also reviewed these papyri in the Detitdclte
lieratut-zeitufig for 1906, but his discuHsiiuj is more partiiularly
jlilologicdl, iind contributes little towards the question of the
licrent calendar of tlie Jews,
The object of the present paper is to inquire whether more
definite infornmtion on the subject cannot be derived from the
Arumaic ^lapyri themselves.
Tlie dates of each pafiyruB, as given by the translators, are as
^llowB. The figures in brackets iiidimte possible alternative
^kiea occ'trdiiig as a certain slanting nnirk in the wriiiug is cou-
Hjlered as forming [lart of the nurnerai or noL The present opinion
Hlkat it shouhl do so, an>l that the hiiilier number is the correct
^pe« which I have accordingly adopted.*
H. On the 17th {i8th?) of Elul, that in the 27th (sStht) day of
H Fachnns, the 14th (15th 1) year nf Xerxes the king . . , «
H * An exception m^y prohMy be tunde in the day of T\^otV\ vu'E,
336 Mr, E. B, Knohel, On the AnderU Jeiwisk lxyiil 5,
B. On the i8th (?) of Chisleu, that is the 6th (7th f) day of Thoth,
the 20th (2i8t7) year (of Xerxes), the beginning of the reigD
when Artaxerxes the king ascended his throne ....
C. Mutilated as to the dates.
D. On the 2i8t Chisleu, that is the ist of Mesore, the 6th year of
Artaxerxes the king ....
E. On the 3rd of Cbisleu, that is the loth day of the month
Mesore, the 19th year of Artaxerxes the king ....
F. On the 13th (14th?) of Ab, that is the 19th day of Pachoii8»
the 25th year of Artaxerxes the king ....
G. On the 26th (?) of Tishri .... the 6th (day) of the month
Epiphi [the 25th year of Artaxerxes the king] ....
H. In the month Elul, that is Payni, the 3rd (4th?) year of
Darius the king.
J. On the 3rd of Chisleu, the 7th (8th?) year, that is the nth
(i2th?) day of Thoth, the 7th (8th?) year of Darius the
king ....
K. On the 23rd (24th?) of Shebat, the 13th year, that \^ the
8th (9th?) day of Athyr, the 13th (14th?) year of Dariw
the king ....
The dates definitely adopted from the translation are as follows:—
A. 15th year of Xerxes, 28th Pachons = 1 8th Elul.
B. I St „ Artaxerxes, 6th Thoth = i8th Chisleu.
E. 19th „ „ loth Mesore = 3rd Chisleu.
F. 25 th „ ,, 19th Pachons = 14th Ab.
J. 8th „ Darius, 12th Thoth = 3rd Chisleu.
K. 14th „ „ 9th Athyr = 24th Shebat.
For the regnal years of the kings I have adopted the dates
given by Kicanl in his edition of Plutarch, thus: —
Cambysos, ist year B.C. 529
Smer'lis (7 months),* „ „ 522
Darius Hystaspes, „ ,, 521
Xerxes the Great, „ „ 485
Artabanus (7 months), „ „ 464
Artaxerxes Longiraanus, ,, „ 464
Xerxes II. (a month), „ „ 425
Sodgianus (7 months), „ „ 42.4
Darius II. (nothus) „ ,, 423
The order of the Egyptian and Hebrew months is as follows :—
Egyptian Months. Dnyg. Hebrew Months. Days.
Thoth. 30 Tishri. 30
Phaophi. 30 Marheshvan. 29 or 30
Athyr. 30 Chisleu. 30 or 29
Choiak. 30 Tebeth. 29
Tybi. 30 Shebat. 30
Mechir. 30 Adar. 29
Mar, 1908. Calendar Dates in the Ara^naic Papyri, 337
BgTpttftti Monthi.
Dftyi.
Hobr«w Monbhi,
Phamettoth.
30
Ve-Adar.
Pharmiithi
30
Nii^an.
Pachona,
30
lyyan
Pajni.
30
Si van.
EpiphL
30
Tammuz,
Mesore.
30
Ab.
5 Epiigomenffi.
Elul.
30
30
29
30
29
^ 29
lu the papyri the Julian dates correspotiding to the Egyptian
dates are all known, and the problem, in the absence of all iofor-
mation an the aubject, tp to coiiatruct a reaaoimble and probable
^I«wi!«h calendar which shall satisfy all the Jewish dates,
^H Fortunately the papyri E. and J. f^ffer Bome asaistance towards
^Ke solution of this difficult question. The Egyptian dates in
^nlian reckoning are as follows: —
^H E. E.C. 446 .,. lotb Meaore = November 17,
^V J, B,o. 416 *.- 12th Thoth — December 16,
but the Jewish date of both documents is the same, viz. jrd
Chisleii ; oonsequentlj the period B,c. 446 November 17 to b.c.
416 December 16 should bi^ an exm-t number of Jewish years.
It has been assumed by writers generally that the commeDcemenl
ol each month was determined by observation and announcemeDt,
^■bd this was no doubt ihe common practice in the ecclesiastical
^near, w)jich began with the ist Niaan. The Jewish civil year,
however, began unquestionably with the ist Tishri ; and with such
a practical business people as tbe tfewa, wh<), as we should infer
from the impyri under consideration, enjoyed at this period a high
^^ate of civilisation, it is almost inconceivable that they should not
^Hive bad in current use some calendar upon which they could base
^heir business negotiations.
The reformed Jewish calendar is based upon tbe Lunar cycle of
niuisteeu years — the so-called Metonic cycle — and it is not unreason-
able to assume that this cycle was in use with the Jews long before
■^e time of Hillel. With one exception, that of the French
^^Kvolution calendar, history does not record the creation of any
calendar, but only the correction, reformation, or amendment of pre-
^Misting calendars. Dr. Mahler pointed out in a paper read lo ihe
^Bbiental Congress of 1892 (" Das Kalenderwesen der Babylonier *^)
^hat the Lunar cycle was in use by the Jews at Babylon bt^fore it
^oraii adopted by the Greeks, and that it was r^lly of Babylonian
^jngin. In discusaing the order of the intercalary months, Al
^^tuni (a.d. 973-1048) {Tlie Chronology of Ancient Natiom)
^Bentions one particular order which he says is preferred by the
^Kws, because they attribute its invention to the Babylonians.^
^H III this attempt to explain the Jewish calendar dates in the
^™ • The period we are dealing with was only ahout sixty years after the
CZftptivitj, and it is reasonable to s^uppose that some of the coloniats b,\ %^9^X!A
Mnmy have migrated from Babylon^ a«) Professor Sayee parUcvAaiX^ \iL^e«i\je%
^abyloQiah names amon^ thwe mentioned in the documentft.
33^ Mr. E. B. Knobd, On the Ancient Jewish, UCVIU. 5,
papyri, it may therefore be justifiable to assume that the nineteen-
year Lunar cycle was in current use. I have accordingly adopted
the cycle with the same interciilations as are to be found in the
present Jewish calendar, ^hich is unchanged since the fourth
century a.d., and upon this basis I have constructed a table for the
whole period covered by the MSS., the intercalary months dispoMd
according to Scaliger's rule, '' ter, ter, bis, ter, ter, ter, bis." *
Normal Lunar
Cycle.
No of Year.
Days.
354
354
3 Emb.
384
354
355
6 Emb.
384
354
8 Emb.
384
9
354
10
355
II Emb.
384
12
354
13
354
14 Emb.
384
15
355
16
354
17 Emb.
384
18
354
19 Emb.
384
Applying this tentative calendar to the cases of papyri K, B.C.
446, and J., B.C. 416, it will be seen that there is only one potsiUe
position for those years in this Lunar cycle, and that b.c. 446 was
the 17th and B.a 416 the 9th year of that cycle, for this is the
only position in which twelve intercalary years can be brought into
a period of thirty years.
This gives coincidence between the number of days from B.C.
446 November 17 to B.C. 416 December 16, and the number of days
in thirty Jewish years beginning with cycle No. 17 and ending
with cycle No. 8 inclusive. On any other calculation there would
be a difference of a month, and both deeds could not be dated
in the same month Ciiisleu.
B.C. 446 Nov. 17 to B.C. 416 Dec. 15 inclusive =10,987 d»y«
30 Jewish years, cycle No. 1 7 to cycle No. 8 inclusive = 10,986 „
* In the old Chinese and Japanese calendar the intercalaiy monthBtre
disposed in this order.
9o8. CaUndar Dates in the Aramaic papyri.
339
It ahoald be mentioned in explanation that were Dr. Mahler's
Babylonian cycle employed, then bx% 446 would! be the 6th and
B.C. 416 the 17th year of that particiiW cycle. So agaia in the
cycle which A I Biruni says wa« preferred by the Jews, b,c. 446
would be the i4lh and B.a 416 the 6tb year.
The table appended to tluH paper of the i8t day of Tisbri from
B.a 523 to B,c, 406 has been constructed m the following manner : —
The Lunar cycle numbers are laid down for the whole period from
the numbers Hxed for B.C. 446 and d.c. 416, and the days of each
Jewish year appended. The Jewiah aatronoinical computation of
the length of a Liinar cycle is 6939 days 16 hours and 595
ch&lakim,^ Aa the table extends over tiix cycles, an empirical
currection had to be made mnking some cycles 6940 days, eo that
the mean length of the six cycles is 6939 days 16 hours, f
It waa then necevssary to find reliable data for determining the
t«t day of Tishri for any year, so that a calendar could be con-
stnieted eo far on a sound basis. Fortunately this was afforded
hy the most interesting discovery a few years ago by Father
Btraasmeier of a Babylonian tablet recording a partial lunar
eclipse at Babylon in the 7tli year of Cambyses. ^ This ctineiform
tablet has been fully translated and discussed by Oppert {Zeii-
9ehriftfur Asfyriologie, vol vi.). It has an entirely unique interest,
as it is an account of one of the eclipses recorded by Ptolemy in
the Almagest.
Ptolemy states that the eclipse occurred in the 7th year of
CambjseSy in the 235th year of Nabonassar, on the ni^^ht of the
17th and iStb of the Egyptian month Phamenoth, Strassmeier'e
Babylonian tablet gives the date as the 7tb year of Cambyses, on
the 14th day of the Jewish month Tamniuz. Tfie Julian date
of the eclipse is determined by Pingru and OpjK:ilzer as B.C. 523
July 16.
From this it is easy to calculate the date of the ist Tishri as
September 29 ; and aa the 7th year of Cambyses is well identified
as B.C. 523, the table appended is calculated entirely from this
date — from B.C. 523 to b.c, 406, It gives the Year b.c. — Julian
period — No, in Lunar cycle — ^Days in each year — Julian date
of Tst Thoth — Julian date of the ist Tishri ; and Greenwich
Mean Time of New Moon nearest to the ist Tishri taken
from Ginacers Haudbuch der Mathemaiischen und Tei'hnischen
Ckronolotpe,
In considering the coincidence of Julian and Jewish dates, it
Bhotild be reniembeied that the Jewish day is defined in Genesis :
•'And there was evening and there was morning, one day/' — that
is to say, the day begins at 6 o'clock in the evening and goes on
to 6 o'clock the next evenings consequently one Jewish date
extendi over part of two Julian days.
• ioSoohalakim efjunl I hour '
I have avoided complicating the question hy reference to the "regular,"
icieni/* and '* abuadaDt " years, &a L'xactitude is impouiye, and il seemed
Dt to aecuf« the correotnuss ol the mtsau Lunar cycle.
340 Mr. B. B, Knobel, On the Ancient Jewiah UYIIL 5,
Discusnon of Daies,
A.
15th year of Xerxes ... B.o. 471 ... ist Thoth ... Dec 19
28th Pachons ... Sept 12
ist Tishri ... Sept. 24
i8th £lul ... Sept 13
B.
ist year of Artaxerxes ... b.o. 464 ... ist Thoth ... Dec. 17
6th Thoth ... Dec. 22
ist Tishri ... Oct 6
1 8th Chisleu ... Dec 21
This papyrus is too much injured for the dates to he deciphered.
The authors state that it is written hy the same scribe as D.,
and that there is strong evidence for considering both C. and D. as
of the same date.
D.
The MS. states: **0n the 21st Chisleu, that is the ist Mesore,
the 6th year of Artaxerxes the king." By no possibility can these
dates — 2 ist Chisleu and ist Mesore — be harmonised. But there
is a crease in the papyrus just before the words " i Mesore," and
in this crease there is an indication of a character which cannot be
deciphered until the crease is flattened out It is probable that
the Egyptian date has not been correctly deciphered. Mesore is
the last month of the Egyptian year, and it is followed by the five
Epagomeiise, which were kept as feast days. The question may be
asked, whether in dating deeds such as those under consideration
the five Epagomense were not treated as continuous dates of the
previous month, Mesore? Dr. Budge informs me that he has 110
experience of such a case, but he sees no reason why it should not
be suggested. I venture to hazard the suggestion that the first
Epagomene was designated as the 31st Mesore. Upon this pare
assumption we should have, as the best that can be done for D.,—
B.G. 460
ist Thoth
31st Mesore
ist Tishri
2 1 St Chisleu
... Dec. 16
... Dec. 11
... Sept 21
... Dec. 9
E
. B.o. 446 •«•
ist Thoth
loth Mesore
ist Tishri
3rd Chisleu
... Dec. 13
... Nov. 17
... Sept 17
... Nov. 17
far. 1908, Calendar DcUes in the Aramaic Fapyru 341
F.
B.O. 440 ..
. I at Thoth .
19 th Pacbons ,
I St Tiahri .
14th Ab
„ Dec. 11
.. Aug. 26
.. Oct, 10
- Aug. 25
3 5ib year of Artaxerxes
The papyruB is very mutilated. The dates 26th Tiahri and
"6th Epiphi are fairly certain, but the regnal year of Artaxerxea is
conjecture. The authors state that the date of thia deed cannot
be earlier than 446, and hardly later than 440. We have to Hnd
coincidence between 6th Epiplii and 26th Tishri, The table gives
""be following dates : —
11, C, 44t}
445
443
442
441
440
6th Epiphi
From this it is probable that the year is B.c. 446, and this
anclusion ia supported by the fact that the scribe of G. is also
tie scribe of £,, which is clearly B.C. 446. The rt^giml year would
bus be the r9lb of Artaxerxes.
H
26tli Tiahri
.. Oct 12
13
,. 30
13
t, 19
»3
Not. 7
n
Oct. 28
12
0 16
12
Nov. 4
y^jroi states, '*in the month Elul, that is Payni, the
year of Darius.*'
3rd year of Dariui \ Payni began Sept. 2
B,o. 421 I Elul „ Sept II
4th year of Darius ( Payni began Sept. 2
B.C. 420 f Elul „ Aug. 3x
iy the 4th year of Darius, B.C. 420, suits the case best.
ended Oct.
1
„ Oct
9
ended Oct.
I
,/ Sept.
28
ist Thoth
1 2th Thoth
ist Tishri
3rd Cbisleu
Dec. 5
Dec. 16
Oct, 15
Dec. 15
ist Thoth
9 th Athyr
ist Tishri
.Dec, 4,. .B.C. 411
. Feb. 10 ... B.C. 410
Sept. 20 ... B.C. 411
24tb Shebat . , , Feb. S ., , ux» Ar\^
342 Mr, R B, Knobel, On the AncUnt Jewish LXVULj
The final results are as follows : —
JullAn Date
Cowptttod Dti&t
from Kgjplljm.
frotti Tia»1<r.
A.
Sept. 12
Sept, 12
B.
Dec. 22
Dec. 2 1
a
Mutilated.
B.
Uncertain.
Dfc. lit
Dec. 9 1
E.
Nov. 17
Nov, 17
F.
Aug. 26
Aug. 25
a
Oct 14
Oct, 12
H.
B.C. 420
J.
Dec, 16
Dec. 15
K.
Feb. 10
Feb. 8
The above results are too near coiucidence to be fortuitous, ati
so far as the civil year is concerned, tliey refute the opinion t
llie coiMinencemeut of the mouth was determined by the ap|
aiice of the new moon.
Two conclusions fmm the foregoing inveatigation may be »af«?l
haaariJecI : firat, tirat the Lunar cycle of 19 years waa in use in thi
Jewish calendar at this remote period, which, as Pntfeasor Sayfl
aaya, was little more than a centtiry afler the grandfathers ^m
);;reat-graiidfathera of the parties mentioned in the pupyri had flw
into Egypt with Jeremiah; and secondly, that the order of inf ^
calation at that time was not dissimilar to tlmt in use to*day.
In drawini^ any conchifiions, one may put aside poasible ci
of the scribe. It is hif^hly improbable that in the first line
original and important deeds like these fiapyri the scribe would
make such errors as would he common in copies.
These deductiuna do not harmonise with the views of the law
distinguished chronolojT^ist M. Oppert, It may be assumed tbut
what was curront with the Jews at Babylon during the Cnptiyit}
would have been continued by them in their subaequent niigi-atioi
M, 0|*p€rt states that the apjiarition of the crescent moon si^malii
the commencement of the month, and in a paper **Sur l*aDcieo
Calendrier Perse/'* he claims to have fjroved that the Babyloniau*
had no fixed «ystem for their calendar until after the year 6.0,367;
that prior to that period the 19-yeflr cycle was in use, but i^^
intercalary m^mtha were inserted without any order, anil si»lelyOO
astrological grounds ; and that it wai* the Greek influence wbM
gave to Babylon \\ fix^'d system, assigning to each year of the cy*
its particular character, whether common or embolismic, and
denies tht^ correctness t)f Dr. Mahler's cDiicInsions.
This view can hfirdly be sustained, for in making the Babyloni
date B.C. 523, 14th Taujmnz, the basis of the appended table, it
most improbable that we sshould arrive at such coincidence of
Egyptian and Jewish datee of the papyri if there had been
fixed system at all. The table connects in a systematic xnani
ioi»
Men
• Oriental Congress, 1S97,
1st day of Tiahn, B,c. 521^ as it
In this paper he catcalates October 6tli as 1
found in the present table.
^^^^Bh
J^l
Mar. 1908, Calendar Dates in
the Aramaie Paptfv
t.
345 ^H
BftbyloQtai) dates with tbe dates used by tli
e Jews at Syene over a ^^^^|
century
later;
and, notwitiistanding M.
Ofjpert's characteri&tic ^^^B
remarlc that ** on
fait I'histoire avec les livrea hiatoriques et
imi) pas ^H
ttvec le5
eclipses,'
* the rock upon
which this i uvea ligation
is built ^H
m the lunar eclipse at Babylon in
the 7th y
ear of Cambyses. ^^^B
" Ta^le of the ist
luhri J
rom B.C.
523/0 B.C.
^^M
TMrB.0.
jQllAn
Period
LunftT
Cycle.
Dayi.
lit Tlwth.
ui TUlirt.
O.M.T. New C, ^^^B
523
4191
[6
354
Jftii. I
Sept. 29
^^1
522
2.
17
384
Sei>t. iS
^^H
52t^
3
18
354
Dei!. 31
Oct, 6
^^H
520
4
19
384
Sept. 25
^^^1
5*9
5.
I
354
Oct. 14
^^H
5i«
6
2
354
Hct. 3
^^H
5*7 ii
7
3
3S4
Dec 30
S«pt 21
^^H
516
8
4
354
Oct, 10
^^^^1
51S
9
5
355
Sept. 29
^^^^H
S«4
4200
6
384
Sept. 19
^^^H
in$
I
7
354
D»^c. 29
Oct. 7
^^H
Sia
2
S
384
Sept 26
^^^H
5"
3
9
354
Oct. 15
^^^1
5 JO
4
10
355
Oct 4
^^H
509 a
5
11
3S4
D«c. 28
Sept 23
^^H
508
6
12
354
Oct 12
^^H
5«>7
7
'3
354
Oct I
^^H
S06
S
14
3S4
Sept 20
20*02 ^^^^1
505 ^
9
15
355
Deo. 27
0<t. 8
^^H
5<M
4210
16
354
Sept. 28
^^H
50J
I
«7
384
Sept 17
^^H
502
2
iS
354
Oct 6
^^M
5013
3
19
3S4
Dec. 26
Sept 24
^^^H
SCO
4
I
355
0<?t 13
^^^^1
499
5
2
354
Oct 3
^^H
49S
6
3
384
S«5pt 22
21 ^^^1
497 J8
7
4
354
Dec. 25
Oct. 10
^^^1
496
S
5
355
Sept 29
^^^1
495
9
6
384
S«pt 19
^^H
494
4220
7
354
Oct 8
^^H
4933
1
S
384
Dtc 24
Sept 26
^^^^1
49^
2
9
354
Oct IS
^^H
491
3
10
355
Oct 4
^^H
490
4
11
384
Stjpt 24
^^1
^4^^
5
12
354
Dec, 23
Oct 12
^^^H
■^
6
13
354
Oct 1
30'M ^^H
F487
7
14
384
Sept. 20
Ee^t.\^ia ^^^1
344
Mr. £. B. Knobel, On the AneierU Jmi$h ]
rMrB.0.
486
485 iB
484
483
482
481 iB
480
479
478
4773
476
475
474
4733
472
471
470
469/3
468
467
466
465/8
464
463
462
461/3
460
459
458
457/8
456
455
454
453/8
452
451
450
449/8
448
447
446
445/8
444
443
jQllan
Ftoriod.
Lonar
Cyole.
DW.
iilTliotti.
Bi^Tldiri. 0.
4228
15
355
Dec 23
Ocu 9 Se
9
X6
3S4
Deo. 22
Sept 28
4230
17
384
Sept. 17
I
18
354
Ot 6
2
19
384
Sept. as
3
I
355
Dec 21
Oct. 13
4
2
354
Oct. 3
5
3
384
S'pt. 22
6
4
354
Oct. ir
7
5
355
Dec 20
Srpt29
8
6
384
Sept 19
9
7
354
Oct 8
4240
8
384
Sept 27
I
9
354
Dec. 19
Oct 15
2
10
355
Oct 4
3
II
384
Sept 24
4
12
354
Oct 13
5
13
354
Dec. 18
Oct I
6
14
384
Sept 20
7
15
355
Oct 9
S
16
354
Sept 29
9
17
384
Dec. 17
Sept 17
4250
18
354
Oct 6
I
19
384
Sept 25
2
I
354
Out. 14
3
2
354
Dec. 16
Oct 2
4
3
384
Sept 21
5
4
354
Oct 10
6
5
355
Sept 29
7
6
384
Dec. 15
Sept 18
8
7
354
Oct 7
9
8
384
Sept 26
4260
9
354
Oct 15
I
10
355
Dec. 14
Oct 3
2
II
384
Sept 23
3
12
354
Oct 12
4
13
354
Oct I
5
14
384
Dec 13
Sept 19
6
15
355
Oct 8
7
16
354
Sept 28
8
17
384
Sept 17
9
18
354
Dec 12
Oct 5
4270
19
384
Sept 24
1
I
3SS
Oct 13 Se]
^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^rt
^H
^Kr. 1908. Calendar
ZJa^tfs m
the Aramaic Papyri, 345 ^^^H
^^TBC
Juli&n
Pertort.
Lnnar
Qycl*.
Dayi.
ifitXboih.
1st Tishrl.
^^^H
44^
4272
2
J54
Dec.
12
Oct. 3
Sept. ^^^H
44*^
3
3
384
Deo.
11
Sc^pt. 21
^^^^H
440
4
4
3S4
Occ. 10
^^^H
439
5
S
355
8rp;, 29
^^H
43S
6
6
384
Si' pi. 19
^^H
437 J3
7
7
354
Dec.
lO
Oct 7
^^^^1
A"
8
8
384
Sfpt. 26
^^H
P^s
9
9
354
Oci. IS
^^^1
434
42^
10
355
Oct. 4
^^H
433 i9
II
384
D«c.
9
Sept. 23
^^H
432
12
354
Got, 12
^^^H
^
»3
354
Oct. 1
^^^1
^
14
3S4
Sept. 20
^^H
429 ^
IS
355
De.5.
8
Oct. 8
^^H
42S
6
16
354
S.*pt, 28
^^m
427
7
17
3S4
Sept. 17
^^H
426
8
18
354
Oct. 6
^^H
425 ii
9
19
384
Dte,
7
Sept. 14
^^H
424
4290
I
355
Oct. 13
^^H
423
2
354
Oct, 3
^^H
422
3
384
S«pt. 22
^^^H
421^
4
354
Dec.
6
Oct. 10
^^^^1
410
5
355
S«*pt. 39
^^H
419
6
3S4
S«pt 19
^^^1
418
6
7
354
Oct, 8
^^H
4l7i8
7
8
384
Dec.
5
S«pt, 26
^^H
4l6
8
9
354
Oct 15
^^^^H
415
9
to
355
Oct, 4
^^H
414
4300
ti
384
S«<pt. 24
^^H
4133
12
354
DiK!,
4
Oct. 12
^^H
412
'3
354
Oct, I
^^H
4"
H
3S4
Supt. 20
^^^^1
410
«5
355
Oot. 9
^^^1
409^
16
354
Dec.
3
Sopt 28
^^H
408
17
3S4
S^-pt. 17
^^^^H
1407
7
18
354
Oct. 6
5^04 ^^H
■^
8
19
384
Sept. 25 ,
Sept. ^^^H
^^ 32 Tatnsi^k Square, Lojidan, W. C. :
^^^1
1
1908 March tl.
1
346 iVo/ K M Barnard, ObserviUiam of Saturn's LXVrit 5,
Observations 0/ Satum*s Ring at the time of its Vinappearance in
1907, made finth the 40-in. Refractor of the Yerkes Ob
iory^ By E. E. Barnard, i Plates 9, 10.)
The poBtlion of Satunt for abseriration of the phenomeiia con-
nected with the disaj)j>earaGce of the ring has b«en unuauAlly
favourable this year, though the south declination (5**) of the planet
was some what unfortiiiiate for northern observers.
At the reappearance of the ring in October 1891, Saturn rose
ouly about two hoiira before the Sun, and the reftulting low podtton
and the approach of daylij^ht iiiade it very unfavourable for the
ob -nervation of such a dehtiate thing as the ring when it is placed
edge on towards us. At that time, with the 364n. and la-in*
refractors of the Lick Observatory, and under such conditions, I
was unable to see the ring {MM, for April 1892, vol. lii, p. 419).
According to Professor Hermann Struve, thn following table re-
presents tlie dates of the present disappearances and reappearances
of the ring of Saturn.*
1907.
190S,
Apr, 17.
July 26.
0*it. 4.
Jan. 7,
Disappearance.
Reappearance,
DiBa|ipe&ranoe.
EeApjmarance.
The Earth id tha plan a of the ringa.
The Snn in the plane of the ringSk
The Earth in the plane of the ringp.
The Earth in the plane of the rings.
On account <if the position of Saturn in the direction of th#
Snn^ the disappe it ranee of the riug in April was invisible from the
Earth The reappearatice in January next will be favourable for
observation.
The present paper deals with the reappearance and disaj^jicar*
ance of the ring in July and October of this year (1907). The
times are central standard time, 6^ slow of G.M.T.
The unusually bad spring weather preventeil early observation
with the 40-in. telesco|ie. The planet was observed, however, m
frequently as the weather and other circumstances would jiermit
It was supposed thi* ** reappearance " of the ring, when the Sun
[tassed through its plane on or about July 26, would be a deficit*
phenomenon, and that the time .of this reappearance could ^
determined witli some jsort of precision. But the reapj^earance w«»
a reniarkalvly gradual ]>henonienon, antl there was no po^sible means
of telling when it occurred. The ring simply very slowly t.^
gi-adually gt>t bri«^hter, and f<»r several days it was impossible to
UAX that any change had taken place ; and then it became brig^'^
and almost linear. It was not, however, at this time that tl^*
greatest interest lay. It was sometime previous to the reappe«^
ance of the ring that the most imfmrtant phenomena were visible-
Wiien the planet was exatuioeil on July 2 the entire surlftccol
the ring was easily seen, though the f>un was not then shining
on its visible surface. Where it was projected on the sky, the v^%
* Publicatioiis of the Astrenomical Society of ibe Pacific, No. 114, J^o^
to, 1907.
Mar. 1908. Eing at the time of disappearance in 1907, 347
appeared as a greyish hazy or nebulous stripy which was not well
defined uiidtsr the ijei^t conditions. lb was aUout v^ times as
broad as the trace of the ring 00 the ball. Nothing could he seen
of the »mdit eilge of the rinj^, which iiiuat have been* too thin to
bo visible. There were two nebulous condensations of greater
brigiitness on the ring at each sitje of the planet. These were quite
conspicuous, but were ill defined and nebulous^ and of a pule grey
colour. The ring and condenHations were so pronounced tiiat they
were strongly visible at 15*^ 50*^ (56™ before sunrise), when the
approaching daylight was very bright. They were still visible as
late a^ 16^ 2*° (24'*' before sunrise), and, thungh faint, cmild have
been foUowed a little later yet. Hough measures were ni ide of the
dtfitances of these condensations on the preceding side uf the pknat
^^rom the preceilitig limb*
Tbs Centrt of the ruoit DiaUni Spot
(rona the Pr^ecfdJag Limb,
7'7(0[7"'6)
Tlie Centie of tbe Nearer Spijt
from tbe Preceding Limb.
2--9(i)t2*"8j
One setting was made for the extreme diameter of the ring, and
this gnve 4o"'9 [4o''*o] ; * whde two settings gave i8*'85 ^^^ ^^^
ijquatorial dian^eter of the platiet.
At 15'' 4™ a faint satellite (Enceladua) following was visible on
the SMUth side of the ring, close to the second conde nidation on that
side. The satellite and condensation were of the same brightness,
which wdl give some idea of the brightnesB of tlie ring and conden-
sations. The tiace of the ring acrosa tbe ball was not black. The
ing was not good ettou«ih to tell whether part of this trace was
ue to the shadow of the ring, which tn all pro^^ability at tliat time
did not reach to the ball. The width of this trace was measured
by setting the wires so that their outer edges were separated by the
dth of the trace — a correction afterwards being applied for the
ickness of the wires = o^'io. The width wa« o "62(1) at 14**
[o"*. The ring, as projected on the sky, seemed to be a little south
the trace.
Position of the trace of the ring on the ball at 15** 50°* : —
From South Limb.
8"-83(3KS"-63]
From North Limb.
lis trace was without any visible irregultirities,
Jnly 5. 15^ o™. The condensationn werp again visible. The
irer ci»!idensHtion8 were estimated to be i-^ times m bright as
be distant ones. One setting gav^o for the width of tlio truce of
be ring on the ball o"7o, I could see nothing of the suolit edge
of the ring.
The seeing was very poor» and t!ie sky clouded a few minutes
er aod did not again clear.
* The iM:}uare hracketfl; tbrou^liioot this pajj^r nioAti that the encloseil
%\u^n btvi! Ixwii rKihic«(l to the rjieuii diatsuMe ot Sat*o'n Umn tint Nun. T\aft
rii»erH in {mreutbe^i*!* nre tlif riuinl^r of settings i>f th*^ mViivo'oaftlftt mt***
b* times are ceutr«J ntaud&td times, 6* o»« alow of Gieenwi\!\i,
348 Prof, E, K Baifiard, Observatiom of ScUum'a LX%
July 6. i4'> 30"*, The riJig was rather faint— very mfl
fainter, apparently, than on July 2, and perhaps somewll
narrower.
Width gf trace on b&U o '62(2),
Position of the trace : —
Wrom Sooth Limb.
8"79(3)[8"-53]
From North Lfmt^.
S'-o2(3)[7''79]
brigbb
There wae a faint tJark belt south of the trace of the rii^
6**'6(i) from the south limb. The conUeneations on the
were visible as before. Nothing could be seen of the aimht i
of the rinj^,
July 12. 14^ 10™. The feebly luminous ring was visible (
thin nebulous etrip on ea.ch side of the planet. Seeing i?ery 1
There was a statellite preceding and another (Encoladus) foUowrn
the ring. When best seen, the ring was about midway in
ness between these satellites, it was very thin and of a
nebulous colour. The etmlit edge could not be seen. AalaK^
(57"' before sutirise) the ring was still dietinctly visible.
July 23. 13^ 50*". Sky thiek. Seeing very bad. The rii^
was dimly visible m a faint thin line. The aunlit edge could
be seen.
Jul V 24, Full moon. Seeing poor. 14** 20"*. The full ext««t
of the ring was visible a^ a narrow, almost thread-like strip,
was faint and nebulouj*, wiihfpiit any irregularities. A faint aatellii
(Encelttdue) was close following the following edge of the ring
when best seen, the ring was perhaps one niagiiitude lesa brigS
than thta satellite. Tliere was no appearance of direct sudUs
falling on the ring or it^ edi:^fi. The following an«i seemed to
the most distinct — perliaps a little brighter.
^S^SS""
July 25. Full nioon, 15'* lo*". The ring fairly well «een (
a faint nebulous strip, ij** 15*". There was a small satellili
(Enceladus) preceding the preceding end of the ring; it was l-
magnitudc* bri^djter than the ring, which was of a faint grey <-«>l<^^
Seeing fair. With an occulter in the eyepiece the ring was
easiily visible. There was no appearance of direct sunlight, howev
but the f^ame pal*^ illumination seen previously. There did
seeni to be any irrej^ularities on the ring, which was very narrow,
and quite distinct when beat seen. The trace of the ring on
ball was not black. At 15*^ 45™ (i** o^ before sunrise) the ria|
couM still be fairly well seen.
July 26. 15^ 0°*, Seeing fair. Slight haste. Bright luo
light. The ring was a little brighter^ but whether due to W
nuxjulij^ht or not, it was not i»os9il)le to tell. A small
(Enceladus) near and j^receding the preceding end of the 1
but little bri^diler than the ring, perhaps as much as
njngniiude,
15*" 15™, The ring w^as decidedly brighter than on the ajl^
This w^as perhaps due to the direct sunlight shining on It I*
wag verv tliin, A iaml s&l^Wilft (Telhys) followed the ball* 1
lar. 1908. Rimf at the time 0/ dimppmrance in igo/* 349
i fi Utile douth of the ring. It was but a little brighter than the
Tiug near it,
I Wiilth of trace of ring on ball = o"'45(4).
15** 30*"* Tlie BRiall satellite (Tethyg) following was much
brighter than the ring near it^perhaf>s one niugnitude brighter.
The ring i^n tiie eky was broader than the trace.
. A power of 700 was then ai^plied. Witii this the ring was pale
and nebulous. The iildmintitiim did not then look Hke dir«*ct
sunlight.
I Position of trace of ring on ball at 15** 45"" —
I »..„„.. ^.^^.
Ffom Hoath Utah,
8"'23{2) [r"72]
fthe
lie thickness of the trace was o''*52(4).
t r6*^ o"* (45"' bt^fore Kunrise). Th« ring was atill easily aeen.
■^ Wtti* but little less bri^'bt than tht^ satellite {Enceladus} prece<li5g.
^B j^h jm ^1^]^^^ j.jjjg ^^^ gijii faintly visible. The sky was white
^Kom daylight.
^K *July 28. 11** 4o'*'. The ring was bright, but much less bright
^Han the ball <d the i)IaTi«t. The illumiimtion looked like tme
pBnlight. The projection of the ring on the sky was south of the
projection on the ball.
14** 30"'. Thickness of trace on ball o":44(4). The illumina-
tion of the rin;4 dirl not look like direct sunlight. It was a pale
grey nebulous li^lit.
35"* The nuif cotdd not be traced up to the ball, but wa«
ioontinuou>4 for some few seconds.
45*". The following ansa seemed to be a little thicker than
the preceding. A very faint belt on the ball was seen north* The
I ring on the ^ky was about twii'w as thick as its trace on the ball,
August 6. 13^ 45*°. Ti-ai-e of ring on ball : —
^Heitsui
m Aui
From South Limb.
8'"68(3) t8''o4]
From NortJi Urob.
Bitsurea were very pool-
August II, 12*" 40"^
Fmm North Limb.
8"'25(J)[7'''59]
seeing very bad.
Position of trace : —
From Soutli Limb.
9''-37(3)[8"-63]
15*' o"*. The ring was much less bright thnn
the ball. It
Seeiog very
Jooked like a bar of light on each side of the planet
poor*
September i. ii** 5'". A faint bt'lt wsls visible on each side
of the trace of the ring.
.September 3, 13*^ o^\ The trace on ball seemed to be thinner
than u^uai, and did not seenj very distinct. When best seen the
ring was clean cut, like a bar sharply pointed at the ends* The
thickness of the ring on the sky was roughly o"'67(i)
September 8. 10** 45"
I tQickness (
Septen
The trace of the ring on tW W\^ ^«k&
3 so Prof. £, K Barnard, Observations ofScUum's Lxym. 5,
occasionally seen. It was very narrow. The ring was bright and
narrow.
September lo. 12^ 5™. The trace of the ring was very faint
and narrow. The planet was occasionally well seen, but the trace
on the ball could scarcely be made out.
October i. 11^ 6™. Seeing bad. The ring was of a pale
ashy colour and comparatively faint. It was not very thin, and
looked like a nebulous strip.
October 4. 8*^ 30™. The ring was entirely invisible, with
magnifying powers of 460 and 700.
8^ 40™. Feeble traces of the ring following the planet were
suspected, but not certain. The presence of Titan near interfered.
A satellite preceding the planet prevented any chance of seeing the
ring on that side. There was a faint satellite (Mimas) foUowini^
which seemed to be on the ring. Seeing poor.
9*^ 10™. With an occulter in the field, in the momeote of
best seeing, feeble traces of the ring were visible following.
9** 25°*. With occulter, the following part of the ring was
feebly glimpsed, but it was very difficult.
At 9^ 45*" a hexagonal diaphragm was put on over the 0 G.
This collected the stray light into six rays, leaving clearer sky
between. An occulter was used in the eyepiece. With this,
very feeble traces of the ring could be seen following, but not near
the planet. It could also be seen feebly once in a while preceding.
In moments of steadiness, the trace of the ring or shadow of the
rin^ on the globe could be seen. But this would have been easy
if the seeing had been good.
1 o*^ o"\ The seeing had got too bad to do anything with the
planet.
1 1^> 40''*. The diaphragm removed, occulter on. The seeing
very bad ; could see nothing of the ring in the steadiest momenta.
October 5. 10'' o°*. A few minutes' opportunity was offered
to observe Saturn with the 40-in. The seeing was fair, and 1
think better than on the 4th. The ring was faintly visible with
the occulter. It seemed to be decidedly brighter tlian on the 4th.
It was very slender and faint. A satellite was close preceding the
planet. The shadow of the ring on the ball wa« sharply marked,
but the seeing was not good enough to show it black. The ring was
much fainter than a faint satellite (Mimas) near its following end.
October 6. 9*^ 25'". The seeing was extremely bad, with a
very high wind.
jQh ^Qin Seeing very bad, but by glimpses with the occulter
the ring could be seen occasionally very feebly. Even with good
seeing the ring would have been faint.
JQh ^qui Ij^ moments of steadiness, fairly good gUuipsea of
the ring were had. It was certainly brighter than on the 4tK
and perhaps somewhat brighter than on the 5th. The shadow on
the ball could also be seen.
Tlie planet was examined later, but the seeing was too bad for
any observations oi va\\xfe.
Jfar* 1908. Hiiig ai tht time of disappearan^ in 1907. 351
October 8. 9^ o^. The ring cuuld oul}* be seen by occtiltation
the planet It was very faint and narrow. The Rontb belt
Tuss the pbinet was far more conspicuous than the north one,
liicb was rather diiticult*
Position of the shadow on the balL 9^' 10"^ : —
From South UmU Krom North Limb.
Very uncertain — the planet very faint in haze.
jjb ^m I could not &ee anything of the ring witii Saturn
acovered in the field, but with ocuulter I could see it at both
itfs of the planet very easily, though it wa^^ faint. It was straight
and very narrow, with no irregularities. A faint satellite at the
Jbiwing side interfered. The ring was easier than at the previous
servatiDus since its disappearance. The south belt was very
Tused to the south, while the north belt was ditlaaed to the north.
be equatorial space between these two belts was tbe brightest
;ion of the jdanet.
11** 25"'. Thickness of shadow on ball was o"'69(2). Dis-
ace of south belt from shadow = 2"'2o(2). A i*ateilite following
a way to end of ring was very much brighter than the ring.
October 13. 8** 25*", The ring could be seen with Saturn
acovered in tbe field. It was thin and rather faint. A satellite
follow^ing and another preceding,
^ Micrometer positions on tbe ball : —
th belt from south limb 677(2} South belt from north limb 1 0-94(2)
dow from south limb 8'$i(2) Shadow From uorth limb ^'25(2)
North b«lt from «oath limb I0'64(2) North belt from north limb 7 •30(2)
There was a faint broad si lading parallel to the equator in the
northern hemisphere. The aoutlieru edge of this was r3"'9(2)
m the S. limb, and 3"*8(2) from the N. limb. The seeing was
bad. This last marking was a very faint and diffused belt.
Though tbe ring was faint, it could be distinctly seen with 460
meters, with Saturn uncovered iti the fields wljile with the
ulter it was s^eou quite easily on both side.^.
o*^. Tiie ring was easily visible without oceiiltation of tlie
.net it was very thin, but by occultation it was quite con-
icuoua. There were two regionf^ t>f greater brightness on both
te preceding and foHoiving ansa [tlie condensations], Tbe seeing
good.
Thickness of the sbadow o"'28(2). The equatorial region was
ighter than any other part of the planet. The north belt was
ler than the south one.
October 28, 6^' 30"'. The ring was distinctly visible. The
•0 luminous spots were quite conspicuous on each ansa,
November 3. 6^ 30"*, The ring and condensations were
ily seen, The outer condensations were the bng\vl^x. 'Y\v^&jfe
ifw so distinct that they looked almost as defemt^ a& aw \\V
I port!
pi;
352 Prof. K E. Barnard, Observatiom of Saturn's lxvul $,
Hie nemrone.
3"'04(6)[2"*84l
The ncnr one.
I'^'SSis) [2-50]
denned s&tellite would be if projected on the ring. Measures were
made at 7'' 10*".
From the following limb ; —
Iti* dfsUDi one,
7"'88(7)[7'"34]
From the preceding limb : —
The dlftunt one.
S'"I4(5)[7"'S9]
Distance between the centres of the two following co»den*A-
tions : —
4-Ho(4>[4"*io]
Thicknests of the trace of ring on the ball : —
o"7iC4) [o'-ed]
The position of the cetitre of the trace was measured^ but tks
Beeing was so poor that the result was imceitain.
From North Limb. From Sotith Limb.
7^' 50"*. The inner condensation was a little the brighter i
each case. It looked as if it might be double, but the sefirtg
not good enough to decide. Between the two condensations
ring was almost discun tin nous. From the inner condensation
the ball the ring was easily seen to join up to the ball, and was 1
little less bright thnn the mljacent condensation. The otiter ones
aeeraed to be more bri^ditly cond*?nsed, or like very small biurr^i
stars. The inner condensation a were about as bright as the fain I
satellite (Ti'thys) preceding, and som^ewhat brighter than the distjujt
ones (condensations),
Aesumiog that these luminous places were symmetrical witK
respect to the ball, and taking the means of the measures, we fiu^
the distance of the nearest condensations from the limb WHa
2* 86 [2* '67]
Distance of the outer condensations from limb was
8"-oi [7"-46]
Noveniber 5. Very bad sky— thick, with misty cl<*ud5.
10^' i;*. In moments of steadiness and clearness the dintant
eoudensation in the preceding an^a looked like a small, ill
satellite. There was a faint satellite (Enceladus) close to it,
was not possible lv*nn their appearance to tell which was t^»
satellite. They were the same size, same form, and same brigh|j
ness — small hazy spots. The nearer condensation was thebrigbli
and at times it seemed to be double. The space between it
the ball was nearly as bright as the condensation. The rrt
between the distant and neiir condensations was faint and aliuo
discontinuous. The full extent of the ring was seen wil^t
diificulty because oi VW ^^oot %V^.
ipoS. Mmg cU the time of disappearance in 1907* 353
iqH 22*^ the following measures were made between the
preceding limb and the i-ondensations :
8-17(3) [7"-63]
^«»r condentattoD.
^H At 10** 31" the diptfint condeiisalion and the faint satellite
pV^>peared as one. On the following tilde the nearer candengation was
decidedly brighter than the distant one, say by half a magnitude
or more. The iimei' condensation was certainly double. Perhaps
a faint satellite was close to it. The trare of the ring on the hall
did not appear black, but th« s^einu; was too poor to be sure,
November 12. 5** 45"*. The condensationB were readily
visible. There were twu considerable ijatelhtes of equal bright-
ness, one near the preceding and the other near the lol lowing end
of the ring.
5** 50™. The condensations were bright and nearly equal.
The inner mies were bright up to the ball The space between
them was almost discontinuous,
6** 30**. Seeing v^ry poor. At this tinvt* tliere was a faint
satellite (Miraaij) between the hrii^ht eaLelhle on the followin*^ side
and the end of the ring. Tire outer condensations seemed to be
perhaps a little brighter than the inner one^, and posf^ibly a little
larger. They were all very conspicuous, Theonterone, following^
was at least two times as bright as Mtuias. The email satellite
itself (Mimas) was about the ^^ame brightn<?ss as the ring between
the two condensations. There was a faint satellite (Enceladus)
dose to the preceding end of the ring, which was nearly as bright
as the outer c*m dentation on that side. It was a little north,
following the condensation. Occasionally the full extent of the
^Bfeg was seen up to neur Mimas,
^^ yh ^m Yhe faint satellite (Enceladus) preceding and the
outer condensations were together at this time, and made quite a
large spot. Distimee between the two condensations on the
following ansa : —
= 5"'04C4)t4"761
flfoi
Highly, the length of the outer condensation was —
2"-io(4)[i--9S]
It was perhaps zj^ times as long as broad, and diifused rather
abruptly on each side, i should say thai the outer condensation
wits I as bright as the bright satellite fol lowing,
7^ 20*. The faint satellite (Mimas) following was going back
at this time, and was making a double bright s|.iot with the outer
concienaatton. The faint satellite (Knceladns) preceding was then
between the two preceding condensations and very slightly north
«£ the line between them. Could not make out anything on the
ball except the trace which was seen only once in a while, though
it was conspicuous enongh when seen. The inner cnndensalion
seemed to go up to the ball without much if any \o&% ol \\^X.
354 -P^'^- ^- ^' Barnard, Observations of Saturn's Lxvm. 5,
The seeing did not pennit any accurate measures from the limbfl^
but the following results were obtained.
Distance of preceding condensation from preceding limb—
7-66(6) [7-23]
The limb was only a blur, from bad seeing. With the planet
unobscured in the field, the condensations were quite conspicuous.
7^ 40*". At this time the faint satellite (Mimas) was between
the two condensations following, but nearer the distant one.
Distance from following limb to outer condensation —
7"72(8)[7-"29]
At the time of these measures the faint satellite (Mimu)
following was close preceding the outer condensation.
The outer and the inner condensations seemed to be of th«
same briglitness. It looked as if the preceding condensation oa
the preceding ansa was nut quite as bright as the one on the
following ansa, but the presence of the faint satellite (Mimas) near
the following one may have been the cause of this. A half moon,
with bad seeing, made the sky very bright.
The Comlensatiotis.
The following table contains the measures of the distances of
these condensations from the preceding and following limbs of
Saturn. They are reduced to the mean distance (9*5389) of Saturn
from the Sun, and are therefore comparable.
Measures of Vie CondenscUi(/iis.
Preceding.
Foil
Near.
lowing.
Near.
Distant.
Diftani.
1907 July 2
2-85
7-56
"
"
Xov. 3
250
7*59
2-S4
7*34
5
...
264
763
12
7-23
...
7-29
Mean 2*68 7-46 274 7*42
It is evident that the condensations are symmetrical with
respect to the centre of Saturn. The individual differences are
not large when we take account of the indefinite character of the
phenomenon.
I have at various times compared the brightness of these
condensations with that of Mima.s, Enceladus, and Tethys. The
following approximate values of the magnitudes of these satellites
reduced to the mean distance of Saturn have been supplied ne
^
ar. 1908, Hin^ at the time of disappmnmee in 1907. 355
by Mn Park hurst from his unreihiced measurea of tLe magnitudea
the satellites of Saturn : —
i2'3 miigmiude.
117
lO'2
^H Mimas
^^K EncoLidus
^B Tt:thya
^H Taking the iK»sittc>iig of the condensations from the measures,
^Hld eoniparing them with the dimensions of the rtng systeiri (from
^Bj own metistirei* in J/.Al, Ivi. p, 171), it i,s seen at once (Plate
' 10, fig. 2) thttt the outer condeiisatioiie are h^cat^^d on the suiter part
of the inner bright rin^, in a region that in the hrigliteHt of the entire
Saturn i an system. The inner i>nes apparently fall on the crape
^^Bg, These condensations, therefore, would aeern to be on the
^Kightest and the faintest parts of the system. As this light is
^Hiquestionably transmitted through the material of the rings, it
^B evident that the above facts are opposed to each other if we
^Msumu that the condensations are caused by the crapt? ring and
^Bke outer part of the inner bright ring, or the thinnest and densest
portions of the ring system. It is improbable that the two similar
phenomena nre produced by exactly opposite conditions. In the
crape ring there are so few particles* that th^^ sunlight would
readily pai*8 through with little or no scatt<iring effect or augmenta-
tion by additional reflection. It is known that a narrow portion
of the inner bright rint: is very much bri;^^hter than any other [>art
of the rings or ball. The explanation of tliis is tloubtless due to
a denser collection in this zone of the small bodies that form the
rings — just as the scarcity of them produces the duskiness of the
erape ring for the want of material to reflect light. It is i>rol>able,
therefore, if they are rn>t too iiensely crovvded to let the smdij^ht
shine through among tliejn, that when seen from the under side
they will appear brit^hter than the other portions of the ring l>y
repeatedly reflecting and scattering the trans niitted light. Looking
at the diagram, it woidd seem that the outer condensations are due
to the inner brigiit ring alone. It would appear most probable that
the outer bright part of the inner bright ring is responsible for
both ctjndensations. On this supposition, the innt^r condensations
are due to the two brighter portions t«f the iujier bright rin^' seen
in perspective. Just why there .^hnuld l>e a los^ af illumination
between the condensations is not qiiitite clear at present, iTnless it is
that the greater depth of the rings in perspective in 8ome way
militates against either the transmi.*sion or reflection — or both —
of the solar rays in that directioir.
lu the dt^scription, I have used the word * condensation * for these
luminous appearances, although I believe it to be miBleading.
Though these bright places look decidedly broader tlnin the thin
trace of the riitg on the sky, and apf>ear to be condensations on
the ring, I think it is simply a matter of contrast or irradiation,
and that they are not any broader in reality than the trace of the
where they *>ccur. I have come to this conclusion from the
ftwinga that I have made, and which are commutvic^ted mlVi V\v^
3S6 Frof, K K Barnard, Observations of Saturn's LXi
jiaper, where the ring has simply been darkened between the
points of greater brightness without chan^iing it8 orivjinal outU
The re8ult is that, when looked at from a distance, the bright pla
appear broader than the ring, ami look like the * condensatioi
as seen in the iky. I think, if the definition were perfect, it woi
be at once evident that this cxplaniition is the true one. Tl
they are not material cotideu.^ations is shown by the fact that tl
entirely disappear when the riug is edge on toward us, at whj
time they should be most conspicuous if they were masses on tlieri:
There is one fact that seems to have been brought out stron
at this disappearance of the rinj^^s. The sunlight can sift thnu
them just as it does in the case of the crai*e ring, only to a v
much less degree. The rings were visible when there was
direct sunlight shiuing upon the surface prpsented to us — the 81
being on the oppositi' side to that of the Karth. Thin phenomena
migl)t he eiplaineil by either of two snijpositious : that the rings
are self-lu ruinous, or that tlie sunlight sift8 tli rough among the
partich's com[>osing them and thuB umkes them vinible. Inasmuch
as the lings bnve been proved to consist of discrete particles, thei^j
teip(>erftture Citnuot he high, and they are therefore not likely tti b^H
selMuminoufi. The second siippoi?ition seems tu be a simple and
sufficient explanation. This is not im|irohable, for the rings ar*
extremely thin, ata no trace of the illuminated edge could lie
at any time whiU* they wore supposed to be invisible, Notwii
standing the fa^i that tlie Bun light may thus penetrate enti;
through even the bright rings, it does not do so with suthdi
intensity to illnmiuate a s<atellite when in their shadow ; for
although Japotiis wa.'* visible at, the eclipse of November r, 18
(i/.iV,, voL I. pp. 107-1 io)j through the entire shadow of the era]
ring, it was wholly inviailile in a 12-in, telescope when it woj<
the shadow of the bri^ilit rings. In fact, though the rings are
translucent^ they are not transparent.
1 have e.Xfhuled the idea that the iliumination is due to reflection
of the sunhght from the hall of Haturn, for the further part uf
the riug was visible- — the entire surface — which could not be so bv
reflection from Saturn.
F.S, — 1908 Mart'h 3.— In looking over my observations of 1907
July 2f I find a note which has a bearing on Professor Aitk^n'^
measures of two «;omlensatioiis at the plat-e of the inner ones. Thi
note, which is attached to the sketch of the inner condensation
|aret'i'dingj says : ** Possibly here there are two cundensntious/
It w^ill he seen, in my hiter notes, I also suspect the inner con
dentation of being double ; hut the seeing was never so gix>d tiiat
I Would be sure enough of it to make measures.
Previous Dimppearmces of the Bingi.
I have gathered the following facts from the Americao
Ephemeris and elsewhere about some previous disappearances of
tha rings : —
s ar«
seeiigi
witUB
tirdM
iciei^H
for
10; I
Mar* 1908. Bing at t/ie tinie 0/ disappearance in I goy. 357
In 1848 the Enffch passed the plans of the ring in April, going
«outh. On September 3 the Sun fuis^pd the plane, goin^' south.
On September 13 the Earih passed back nortb, and on January
19, 1849, the Earth once mure went south with the Sun. There-
for»i between Aprit 12 or 13 and Septt^mber 3 the Earth and Sun
were on opposite sides of the ring, Tbis was again the caae
between September 13 and January 19,
1861 November 21. The ring ilisappeared by the Karth
passing through its plane to the north — iIik Sun being some 2J*
^uth.
In 1862 it reappeared on January 31, the Earth passing through
the plane of tlie ring to thw south. On May 17 it disap[^eared by
the Sun passing through the plane to the north. It reapjjeared on
Atignst 12, thtj Earth passing to the north.
1878. The ring disappeared on February 6^ the Sun passing to
the floutli. It reappearcil March i by the Earth passing to the
«oath.
Ijo 1891 the ring disappeared, September 22, by the luirth
paaeing to the north. It reappeared, October 30, by the Sun
paasiiig to the north.
1892, about May 20, the Earth was less than J* north of the
plane of the rin*;;8, but it did not cume any nearer, and the ring did
not disappear
1907. The Ameriran Ephemem does not give the times of
disappearance and reap t^ert ranee, but one can deduce them from the
** Apparent Elements of Saturn's King,*' p. 515. I have already
given Profe-sst»r Struve valties of thest? quatitities for the present
U|ij>antion of the planet. For con»pleteness of thiis list 1 will rejieat
them here*
1907 April J 7* The ring dia^ippeared by the Eat th going south.
July i6. It reappeared by the Sun im^ising south.
October 4. The ring disii|>peared by the Earth pus.sing north.
1908 Jannary 7, It reappears, the Earth passing soutlj.
The following table, containing the mean times of meridian
transit and the dee lino t ions of Saturn at the critical times for the
phetKittiena of the disappearance and reappearance of the ring, may
J^e ol interest in connection with the present and for comparison
iw future diaappearancea of the ring. The last ^olunm indicates
the cau«© of the disappearance or reappearance.
I>ate.
M,T,.jfTTaii*it.
h tn
necllimtion.
f8|8 Apr.
21 21 24
I «7
®
going S.
Sept
3 12 A4
5 5
0
M S
•t
12-13* 12 6
5 22
e
„ N.
1S49 Jan.
19 3 36
-5 2a
®
.. s.
t86i Nov.
22 19 20
^5 '5
®
M N.
1S62 .Ian.
31 14 A^
+ 5 15
©
>» 8.
* Tlie tnendinn (saanagd and decliuAtion ai^ gi\*6lt foT the \it\v.
3S8 PrvJ\ E, K. Banmrd, Olmi^atiom oj :iaturiis tXVlU. S,
ig6« ftUy 17
Aug. J 2
1878 Feb. 6
-Mar. I
iS9t Sept. 22
Oct 30
t907 April 17
July j6
Oct. 4
1908 Jun. 7
7 30
2 S
2 15
o 54
21 1 1
21 54
15 40
10 47
4 30
+ 7 38
-6 14
-5 9
I 25
-448
-3 J2
-S 6
5 3
With r.
0 •
®
0
©
©
® *
0 '
© .
Frotti ati inspectioti nf iliis table it will be seen thrit Uie |ires€Ol
disappearance of Sttturn's ring has been an extremely favt»uniblf
one — the mor^t favourable in forty-five years — com pari ag in (hii
respect with the disappeArances of 184S-9,
In 1848-9 and t86i-i thero were two disrippearances ai
reappearances eath of the ring. In 1878 there wa» onij «jLf
disappearance, ami the corresponding reappearance, both vety nic
favourably situated. The rinj^ was invisible for abuat twentrAwd
days.
In 1891 there was only one disappeamnce and reappi^
The conditions were likewise very mifavonrable. The ring
invisible some thirty-eight days.
At the preHt'iit apparition of the planet there werv two
appearances and two rea[)pearnnces.
There is an important series of observations of 8atnm
with the 15-inch refractor of the Harvard College Obsi-rvalory llj
the Bondn at the disappearance of the ring in 1S48. Tbot
observations form part of volume ii. of the HarvartI (Jalit^
Observatory Anaah.
Some of the drawings? of Satuni given in the above volame
show the ring and condensations essentially as they have appeared
here in the past mn months.
The conditioos of the disappearances and reappearances of tW
ring in 1848 were almost identical with those we have just wittiewtfL
in all his observations Bond assumed that what be eaw «••
the sunlit edge of the ring. The explanation of its viAnitlitv u.r^
therefore an easy one. The ol^servalions of the j 1
appearances have shown j however, that it was not the ♦
we saw, bnt the very obHt|ue nndluminated surface n
The minor axis of the ring about the 1st of July was stv
Bond's explanation of the bright markings, conder
knots seen on the nog during its ** invisibility " waj; vers
but it depended upon the ed^B of the ring being seen 1 1
Cftssini division. The extremt^ thinness of the rin.
largeness of the condensations niake this explanation uum
irmm off the baH,anrf ring Myatcm of Saturn, showing the proiecVed pis*\V\^T>* *t\^
\irrtit* of Ih^ cortdmrtsAtiOfis.
mm A, S, B, A show where the cemire^ of thft condensalion^ IsiU. T^ts Ao^fe'^
9« m, * b, b, b, b, M, m Mhow the timits of tb« condensation*.
Ming at the tiim of disappearance in 1907. 359
It* Montldtj Notices for November 14, 1862, vol, xxiiL pp.
SS» there are some observations of Saiiirn at the time of the
disappearaucft of the rivt^^ in that year made at Greenwich and
Ehllkowa, In Iwth these there are distinct refereuces to lumtnntts
appendages^ which seem roughly to be tlie same seen at the
observations of this yeur^ — 1907. The deBcription^ ure not quite in
satisfactory accord with their appearance as seen to-day. The ring
was supposed to have disiippeared on May 17, 1862* by the Sun
going north, and to have remttiued invisible tuitil August 12. At
Pulkowa the descriptions soera to indicate only two apfjendages,
one on th*^ preceding^ the other on the following ansa. They did
rseera t(» have been perfectly styni metrical.
The Pulkowa obhervations are : —
** 1862 May 20. The aspeet of the luniimma appemlages ha« not
varied since last night, with this difference only — titat I estinjated
the length of the preceding side as 065 and the foHowiug as 0*5
of the planet** diameter,
" 1862 May 21. Inia;L(es good. Eatinjated extent of Inminous
appendaged : — Preceding side 0*6, foIlowin;ji side 0^4, of the |ilanet's
diameter; al^o the intensity of tlie liglit appears much more feeble
OQ the followin^^ side. The size of these appendages increased in
the neigh bourhuoil of the planet, givins^ them the form of sharp
wedges,
*' 1862 May 21. Images less favourable than yestei-day. Extent
of luminous appendages on preceding side 0*6 and on following
side 0*5 fif the planet's difmietei.
** 1862 June 3. linage very bad, yet the luminous appendages
are still distinctly visible. It a{>pears that the length of the
following ansa is a little the greater, but this ia not certain,*'
^_ The Greenwich observations are:^ —
^1 ** 1862 May 17, The rnig beyond the planet at times just
^raible on the left of the disk» but on the right only a amall faint
spot conld be seen in the plane of the ring, about ^ the diameter
©f the iiink from the planetV limb. 1 sbonld have 8UHpe<:tetl this
was a satellite but for its elongated shape. Sky very hazy,
1*' 1862 May 19, S>*turn very well seen. The ring di«tinetly
ible on the left of the disk, and fairly but not so distinctly
▼ifiible on the right. Where it crosses the disk, the under edge is
much sharper and better defined than the up|>er edi^e.
^** 1862 May 20. Satin n very well ,seen ; the ring {liatinetly
ble, ap|»eanng brighter than it did last night. Hie Greenwich
crvations were made by Mr, Carpenter,"
There are also some observations by ^Ir. Wray in the same
number of the Month! [/ Noiu'e^, m which ho saw somethinEj of
the kind in Deeerober of 1861 and January of 1862 with a 7-in.
refractor,
Ytrke^ fJb»ervattfru,
Williams Bay, Wis.
1907 November 25,
360 Prof. E, K Barnard, Addiiwmd Obsermtithts ijcvm. ;,
Additional ObmrvalionB of the Disappearance^ awl lltapimiraum
uj the Rimjs of Saturn in 1907 S, ma^Ie mth the 40 ^>wi
Refraetor of tJu^ Yerksa Obnervatarp, By E. E. Btirntir*!.
1907 Nov. 23 — with i2*iuch telescope, 6** 15™, power 150 + ,
I could see the two condensations on the preceding part ot tlxc
ring, Thiij were fairly distinct, but faint. Could scarcely se<s
thttni oil tijti following side.
yb ^qOj — luaitig a higher power The ring and condensations
were not so well seen, A satellite closing in following^ mixed its
light with the condensations on that side. With the low pi»irec
could see the two condejjsations on the preceding ansa very dis-
tinctly. They appeared tqual in brigbtneas. The inner ons
joined up to the planet with but little change of brightnew.
There was no ibmbt but that the following ansn and condensal-ionB
wore fainter than the pix^ceding. Tbe satellite interfered, however.
Ttje sky w^is elear and good, but the image wa.s linateady, Tho
trace on the ball was apparently dark and without irregularitie*,
Nov. 24, 5*^ 1 1™. The condennationR were easy. There were
two satellites, one preceding and one following, that interfenwi.
The condensations were of equal brightness, both preceding ftinl
following. The inner one preceding was bright to the Ixall. Thi
entire ring was visible with or witho*it the occulter. Seeing— 2
(on a scale of 5)* Lost in clouds,
8^' 46"*. Thinning down near Saturn. The follow inv aD*»
was i:ertainly the brigliter. There was a faiut satellite (Mima*)
following the fl^llowinJ4 end of tbe ring. The outer condensation
near it was twice ae briglit as the satellite. Seeing = i. The full
extent of the rrnj^' was quite conspicuous when best seen.
gb gm — ^vitii the i2dncb telescope. C'ould see tl»e eondensa*
tions. Biith Mr. Sullivan and I decided that the following side
was the brighter. Seeing poor with 12-JiKdi, (Back to 40-incbd
Tliere was no question but that the following ansii wiia the brighter
The ring between the condensations Wiis faint. Tbe outer con-
densation following was two times as bngbt as the faint satellite
following (Mimas). In each case tbe owter and inner condensations
were of equal brightness. Seeing very bad,
N o V . 25 . 4^' 55™. Tb e CO 1 1 d ensatio ns w ere of eq ual brigh tuesi.
The space between them was almost discontinuous.
^h 2^m Distance between the centres of the preceding
dentations —
4*^0 (6) [4**44]'
Distance between the centres of the following condetisftttons —
Seeing very poor. Went to tbe 1 2-inch telescope. Could faintly
see the rings and condensationa^very laint compared with tbe
view in tbe 40-inch,
Nov. 26. 5^55™. Seeing fair for moments. The condensatiooi
1
Mar. 1908. of the Mings 0/ Saturn in 1 907-8.
361
were very bright, but tlm ring lietween them was very faint, and
&U but iliBcontinuoUB.
6** 25™, The wraall satellite following wat* the same brightneg.^
Sft the inner condeusution, but ver}' sli^^btlj brighter tlian the outer
one. The following ansa was considerably brighter than the
preceding. I could see the ring beyond the outer condetisatioii
following,^! thiuk, all of it, but it was extremely faint. The
condtn Millions were about the thicknet-s of the dianietyr of the
bright satellitr« following. The inner condeusationa were a little
I brighter at their outer ends. Seeing = 3.
6** 45*". The bright satellite was half a magnitude brighter
! than the outer condensatiun,
[ 6^ 50^. The outer cDudeusation was exactly midway between
the satellite and the following limb. The following anm and
condensations were certainly brighter than the preceding. They
were all conspicuoas with the planet unoU^cured. When seen
^Aeet the condensatjons appeared to become narrower,
^K Nov, 28, 5^ 4™. Seeing very poor. The ring and con-
^Bensations were conspicuous.
^P 5*" 24*". There was a small eatellite (Tethys) just north of the
I ring, and abtuit midway between the condensations following. I
think the following ansa was the brighter.
j 6'' 49''*. There wns h .sniall satellitt^ between the two condensa-
tioiiii preceding, nearer tlje outer rnie. There was a bright satellite
close preceding the end of the ring in line witli it. There was a
I similar satellite at the preceding end of Ihe ring a little north.
These aatellite.** were half a magnitude brighter than the condensa-
ttoBs. I think the inner condensation following was slightly
brighter than the outer one.
6** 59"'. Seeing very poor. There was a very faint satellite
(EneeladusT) then visible at tiie preceding end of the ring, close
south following the brighter satellito. The seeing was very poor.
I could not make out any details on the ball.
8** 54™. The fcieeing better, though the planet wm low. The
following ansa wa^, I think, the brighter. The inner and outer
condensations were of the Bame brightness. The inner ones joined
up to the hall with almost full brightness. The space between them
looked to be a little hm than on some previous nights,
I Dec, 3. 7'* 42*^. The condensations were quite bright.
I Distance from preceding condensation to following limb —
27'-25 (8) [26-63].
From precediag limb to outer condensation —
7"-5S (8) [7-38].
The inner condensation was bright np to the planet. Could not
make much out of it on account of the blurring. I don^t think
there bad been any change in the condensations. They were
^hter that! the aoiall satellite (Tethys?) preceding.
362 Prof, E, E, Baninrd, AddUianal Obsei'vations LXna J,
Dec. 5. 5** 46*". The condensations were bright in momeoUof
steaditipss. The following ansa was the brighter,
6** II™. I went fiver to the 12-irich telescope. The seeing wm
very poor, I couM faintly see the following ansa, but could get
only feeble traces of part of the precevling ansa. I could not be
certain of seeing the condensations. Used low and high powen.
The trace of the ring on the ball, or the shadow, ivas fairly well
seen.
Back to 40-inch* The ansa© were conspicuous without oceulto,
as were also the eon den sat ions, though the **eein}j was very bad.
6^ 21™. In momenta of steadiness could see the ring cod-
tinuous between the two condensations.
Dec. 10, 7^ 50™ Tiirough clouds, seeing poor. The ring and
condensations were easy. A small satellite was ^''-4'* following
the fuliowing end of the ring. The outer condensation was brighter
than this satellite,
Dec. 1 2. 4** 38*", The definition was fair in inonieuU. Tbft
ring and condensations were quite easily seen.
4^ ggm Seeing ^ 3. Tfie ring was easily continuous bfr
tween the condensations. Could sf^e the ring beyond the oul«i
condensations as a slender thread of light. J
Distance from j^receding limb to outer condensation, 7*7^^ (b) [; 7j]
following „ „ ,, 7*S4(6)[779]
Length of outer condensation following, 2'30 (7) [a'sS]
Width of space between condensations following^ 2*32 (7) [i'p]
The ring and condensations following seemed to be brighter tb&n ihcm
preceding. Sometimes the central part of the outer condensation,
following, looked like an ill-defined satellite, A sketch showed it
to be 2 to 3 times as long as it was broad. The inner condensation
following was continuous up to the Imll, but there was a brigbl'?!*
place at its outer end. The outer and inner condensations seem*<i
to lie of equal brightness. The ring between them was 6 or 8
times a.s faint as the conden.sation aud looked much thinner. I
could not see anything t>f the shadow uf the ball.
5'* 45™. The seeing has been 3 all along. The thickness of
the outer condensation following was J or \ its length, A sketch
shows that close up t<i the ball the following inner condeDsatioa
was quite faint for a second or so,
7'* 6'". Dione was in conjunction close north with the outer
condensation following. A small satellite (Enceladus T) following
the following end of the ring was several times fainter than the
conden.satiQnM.
Dec 2 5. 4*^ 48'^^ The condensations, and the ring in general,
were easily visible, but they were much thinner than at the Ust
observation. Could see tlie full length of the ring. It was very
narrow and faint at the ©nds beyoud the outer condeoaation. Tit
ring on btjth sides could be .seen between the two condensatiuofl
though faint. I
E f908* oj the Rings of SeUum in 1 907-8.
363
inner condetisatiou was bright nearly np to the
Uy contrast, it was faint near the halL Seeing
= 3, The tra«;e of tlie ring *in the sky wa.H ubont on a line with
the south eiige of the shadow an the bnll. The seeing was not
quite good eiioygh to tell if tiie shadow of tlie ring was irregular.
It appeared clear and straight in moments of best seeing. A sketch
says that the following inner eondensalion wiis not continuous
cloi^e to the ball-
Estimated with the nncronieter wire. The thickness of the
condensations, or the ring at thei?e points^ was about i| times the
thickness of the wire, while the outer slender end of the ring was
perhaps A *Jr i the thickneijs of the wire [thickness of the wire
5^ 38™, A small satellite waa at this time exactly midway
between the condensations. It was about one diameter of itself
south of the line of the ring. The ritig at the following side was
not c*nitinnous up to the ball, but there was a faint place frxni the
ball out for, say, i". Qnestion if this was the shadow of tlie ball
ou the ring. I could not be certain of this effect at the preceding
side.
1908 Jan. 2. 5^* 30''*. The ring was very thin. There was a
aatellite at each etnl. The one following was very close to the
ring. There was a very faint satellite rlo^e north of the ring^ half
way out^ following. Seeing = 3. Without occultatjon tt was
almost imp(»ssibl0 to see any trace of the ring on the eky. The
condensations were feebly seen as slightly brighter parts of the
ring. The ring and condensations were slightly brighter than the
faint satellite, but were much less brigiit than the satellite at the
following end of tlie rii^g. .Same at 6** 30"*.
Jan. 5. 5** o™. The sky good. Seeing = 2. Not dark enough
to see the ring.
5*" 10°^. Could see the ring very faintly with the occiilter.
5*" 20"*. Tlie sky was not entirely durk, yet eonld see the ring
ntly, but not well.
40"*. lb© ring was very faint and quite tlnii. I thtnk
there was a feeble intensification of the ring at the places of the
condensationa ; that is, it was possibly very slightly brighter at
iho^ points, but not thicker. The shadow of the ring on the ball
wttfl black and strong. The ring was much more difficult than on
Jan. 2. I could not see anything of it without the occulter,
Jan. 6. 5** o*"* The sky too bright to see the ring. Seeing
very poor.
^
6^' o"
A close watch was kept until this time with occulter.
e seeing had st-eadied a little. During the heat momenta could
not see anything of the ring. Seeing at best = 2, There was
considerable glow from want of steadiness. Watched at both sides
cd the planet. It is possible that with better seeing I might have
^^eeo it, but it is dunbtfuL It must have been excessively faint.
^^H Then went to the 1 2-inch telescope, but the seeing was poor.
^Thied high and low powers, hut could nut see anyt\img ul \.\\ft m\^
364 P^'^f' £' ^' Barnard^ AddxtioTud Observations Lw 111.5,
Jan. 7. 5** 15"*. Seeing = 2. The ring was quite easilj
visible by occuliutiou. It was linear, but rtither faint on the
following side. On the preceding side couI<l *»ee it well IVre
was a bright satellite at the preceding end of the rin^*. The rioj;
must have been much brighter than oit the 6th, for 1 couid tm
it when the seeing was worse than it w^as at times on tbat diit^
—when I could not see it at aJL It looked haiy and ili-defind.
There were no traces of condensations. It was a straight Wr, it*
full extent perfectly nniformly lUuminated clear to the end. It
was of an ashy color, rather thickiah and fnzzy.
5^ 50*^, There was a faint satellite 6*' or 8* preceding the pr^
ceding end of the ring. It was just as hright as the ring. The»k)'
hazed over. Went to the 12 -inch telescope with Mr. Fox, He ^^"t
a glimpse of the planet in a clear place between the clouds, and atw
the ring. Thick sky prevented my seeing the ring with the
12-inch. Moonlight made the hazy sky too bright,
Jan. 8. 6** 15"*^ — with i2*inch telescope. The planet secJi
through break in clouds. Could see the ring faintly both foUowing
and preceding. Seeing poor — haze and clouds.
From these observations it would appear that the Earth wuit
have pajised the plane of the ring sometime between 1 908 January,
5 days 6** o^** and January 7 days 5^ 15™. Perhaps this oocurrol
not far from the time of the observation of January 6.
Tlie observation of January 7 w*ould seew to indicate that the
plane hud already been passed some hours before, from the diatmci-
iiesi* with which the ring could lie seen at that time.
The observation of January the 6th, though not under the beat
conditions, again showed how thin the ring must really be^ for it
was not visible with the light of the planet occulted.
I think, however, a more effective criterion of it« thinner
was offered at the various times when the ring was ohserfcd
with the Sun and Earth on opposite sides of it. At such tmit^,
though the very oblique surface of the ring was visible^, nothiDg
could be seen of the edge of the ring itself, which shouM have bceo
seen as a thin rim of light. This sunlit ^dge of tlut ring was doI
visible at any time, though it was always looked for carefiUly wben
the seeing wa« best.
As it may be important for the aid of others in any investigation
of the phenomena presented by the ring in 1907, I may ^
permitted to co[)y here my previous measures of the Saturai*ts
system ; to these I will add the measures of the condensation**
They are all reduced to the mean tlistance of Saturn from the Snn
= 9"53^9* {^^^ MM.^ vol. Ivi. p. 171.)
igoS. of the Rings of Saturn in 1907-8.
365
Table of Measures of the System of Saturn.
^uaiorial diaineUr ofSatorn .
Outer ili&meter of ouUt ring ,
luner diameter of outer ring .
Centre arCassini division
Out*r diameter of inner ring .
luDitr di&moter of inner ring .
Inner dta meter of crape ring .
Width of Cassini diridon
tnncr condensations from limb ,
17-800
40 '108
35-046
34-517
33-988
25*647
20*528
0*529
Kiidius S900
,. 20-054
*» '7*523
,. 17*258
„ 16994
o 12*823
,, 10*364
^'i.^^ ' from cmitre \ *\f,,^
Outer edge of inner condensations from limb
Inner edge of ontt^r coudenMtions , ^
Centre of outer condcnsaiions . », 7 "438
Outer edge of outer condensations , ,
12*900
15*200
16-338
17-480
hThe polar diameter of Siiturn was i6"'24i.
The raeaanres of Di^cember 12 made the length nf the outer
deiisatiotis »= [2 '•28]^ and the distance between their nearest
edges =[2"*3o]. From these and the tabulated jKisiliun of the
centre of the outer cnndensattons we have the values of the
positions of the ends of the cundensfttion^ ns given in the table,
' The observations show that the eondensaiions on the [>receding and
following ansae were perfectly symmetrical with respect to the
centre of Saturn.
If now we compare the full extent of the outer condensfttioua
with the Cassini division we have —
^^L Outer edge of outer condensation from centre
^^F Outer edge of the Cassini division
L Likewiae we have for the inner condensations
pibCa
Outer e^g^ of the inner con denization
Outer edge of the cr»pe ring
17-48
17*52
12 90
12-83
These would seem to connect the condensations directly with
Caj5»ini division and with the crape ring.
They are opposed to the siq^po.^ition that the bright ymrt of the
ner bright ring is responsible for the outer condensations, for
y show that the outer condensations extended beyond this ring.
1 believe it has been shown that the Cassini division must be
of particles, because of the disturbing action of certain of the
llites. If this were not bo, and the Cassini division were filled
particles as closely clustered as they are in the crape ring, a
factory explanation of the condensations would b^ l\\iiX X^ft^Kj
26
366 A few Observations of (he Plariet Saitim and LXVill. 5,
were simply due to tbe Bimlight gliiniug tbraugb and UlummittiRt: th^
particles in the cmpe dug for the iuner caudensatious*, and a >
effect of the Sun shining through the Ciissini division iUul
inating the particles in it would produce the outer coudei
The fact that the inner and outer condemations wert>
of the same intenaity would require that the particles sL
closely clustered in the Caseini division as they are in the ti..|
With the aesumption that particles do exist in the i
diyision, the above explanation of the condensations iroma
satisfactory.
In any attempt to connect the hmer condi i
crape ring, it may be important to state that i
have always appeared much brighter than the ciaj
appeared to me — even allowing for that ring beinj* « 1
between two bright regions, the inner bright ring anii the Imti
Saturn »
In conclusion, I am greatly indebted to Professor Froat f
extra time with the 40-inch to observe the phenomena of tli
appearances and the reappearances of the ring of Saturn, ar
the kind interest he has shown in the work,
Yerles Observatory,
WiUiaim Bay, IVU, ;
1908 Janicary to.
^
i
A few Oheerv€dums of ifie Plamt Saturn awi hi^ Ring« in thf Ttmg
1897-1904. By E. E. Barnard, (Plate it*)
In connection with the papers on the disappearance of tb- **«*'
of Saturn, I have thought it might be interesting to tnclnn
separate short paper some other notes on the planet*
I have a number of observations of Saturn made lier© la tte
past ten years. Some of these are perhaps worths
they bear on the appearance of the planet with the
when the rings were wide open, and I have collected u l^w ui Ut«&
for this paper.
1897 May 24. The north polar cap of Saturn w
dark colour — not well seen. It wa^ iMirdered by a Ii.
1897 July I- {With the 12 -in, telescofje.) The 1
ofiened so that their outer edges seemed to be exactly - --
with the polar limb of Saturn. It appeared perfectly mj v:
date, and also on June 29. The shadow of the ball oiv '^
seemed to be ** squarey ■' where it struck the Cassii.
The polar cap was dark grey and not large. It was bo
a light space, then a delicate dark narrow belt. Then
light equatorial zone.
I think this angular or '^squarey " form of the slmdo.
baU on the ring waa Bimi^\^ ^la-AMftA \i^ the shadow falling ^,4
|LY Notices of R AS,
Vol, LXVfll.
IQOS. hu Jiinffs in th^. Years 1897-1904,
367
Cdssini division and producing tbiw a kind of ** black drop" effect
* by the junction of tbe black shadow with the black space.
I189S February 26, The shadow of the ball uii the ring^ was
it a uniform curve, but of an anguhir outhn*?, iifi shown in the
Fo
Form of the
of the Udl on the King of Siturn, 1S98 Fehmary 26*
sketch. The north pole wa^ dark — not blacks The ball was
clearly seen through tho crape rin;^,
1898 March 6, The shadow of the ball on the rings preceding
seemed ''squarey." The north pole was dark,
1898 April 20. There was no detinite dark polar cap aucb as
was seen last year, but the polar regions were dark. The planet
was beautifully seen through the crape ring. Tho shadow of the
ball on the rings looked " sqnarey."
1898 July 7. The trace of the crape nn^ was hazy at both
edges, or rather the inner edge of the bri^^bt ring was ill deHned
where it crossed the ball^ but it was well defined on the aky
between the ring and the bull The crape ring was easily seen
ftnd well defined on the sky, but faint where it approacfied the ball.
Til*? two northern belts were more in contrast, or darker near the
limbs of the planet. The inner bright ring was brightest toward
the Caesini division, where the brightness was rather narrow,
I could not see with certainty nny division in the outer ring.
There seemed to be a dusky shading winjre the Encke division is
usually shown. The polar cs[> was darker than the darkest part
of the ball.
The definition was superb, I have never seen tho planet
better, nor have I seen so inut^h detail upon it before. The Ijelts,
as shown on the drawing (Plate 11), were seen with certainty.
The ball was easily visible through the crape ring.
1899 April 7. I6J^ A heavy diifused belt at the equator.
The north pole seemed dark. S*^eing poor
1899 April a 5. The north pole was not very dark. The
blacky welhdelined cap was not present. It was a little dusky at
the pole.
1 90 1 October 11. 17^ 50**, There was no polar cap. There
seemed to be a luminous appearance near the north pole, at a point
itiBide the following limb near the shadow ; seeing fair, but ]^lanet
very low.
368 Mt. J, M, Baldwin^ PhotomMrie Measurements Lxmi ?,
1904 June 17. There was a heaTy» diffused^ broad dark bell
north uf tlie equator.
1904 July 2, The north belt was very heavy aod diffused,
1904 July 4, The north bt^lt was heavy antl broad.
1904 July II. The north polar region was of a light yellowr
colour.
1904 August 27, The north polar region was light^colonred.
1904 December 5. Light at the equator, with hro»it defkr
region toward tlitj north, but all the noith region was lighter
I have purpOBcyly with fie Id (for another [»aper) the observatioQi
of Saturn in 1903, at the time of the appearance of the white spot
on the ball of the planet
Unless otherwise stated, all the observations in theee pap«ft
were made with the 40 inch tc^lescope.
Terke9 ObservtUory,
WilliamMBay, WUu;:^
i9o8*/a»iiMiry.
Photometrif' Mectsmwnmfs of Saturn^ Awjust to Deceruher 190;.
By J. M, Baldwin, M.A., 1851 Exhibition Scholar (Melbouruej,
{CmimunieaUd hy Sir David OilL}
During the recent opposition of Saturn, at the anggestioa rf
Professor Miiller, I undertook a series of photometric measures of
that planet This opposition has been of f»articular intereM, for,
owing to the small elevation of the Earth above the plane of the
ring, the reduction to ** ring invisible" is subject to very alight
uncertainty, and so the variation in the brightness of the spheroid
itself with pha^?e angle cm be obtained,
Seeliger* has theoreticiilly arrived at an expression for the
magnitude of Saturn, in which the mtignitude depends on two
quantities, the first of whicb^ expressing the light received from
the ring, shows a miirked variation with phase, while the second
expressing the light from the spheroid, is almost independent of
phase. Miiller,t on the other hand, has arrived at eropiri(«i
formulFB for the maj[^nitnde, in which the variation in maiiintud*'
is proportional to the change in phtise. In discussing \ih ol
tiona and those of Zullner, he remarks {Lc, p. 343), "es
also, als ob auch bei gjinzHch verschwundenem Ring ein ?
der Phase sich gpUeud mache"; and Pannekoek J has
emphasised this point, showing that the observed change? *'i
brightness with phase vrhen the elevation of the Earth above
tS88,
H. Seeliger, AhhandL drr Bayer, Akad^ der JFisaenfch*^ Bd. f6» |0J<
t G. Miillor, PubL des Astrophya, Ohserv. tu Potsdam $, 339 a. 341, t^t
t Ant, Pannekoekj Ail. i!^iiek. tfxk^ M. \&i^ ^63, 1905.
Mar. 1908. of Saturn^ August to December 1907.
369
Ihe plane of the ring was amall are greater than accounted far
"by Seeliger's tliftorjr, nnd bo rend^^ring it probabte that the spheroid
itself shows changes m briglitiie«;3 with tlie fihast*. Jhv object of
this series of measurements was therefore to determine which of
,ihie two formulae agreed best with observation*
In order to avoid bias, I was careful not to find out the
magnitudes of tlie variation in phase given by the formulD& ; and
furtber^ the observatioUtS were not reduced at all until after the
BIple series was comideted.
iThe instrument used throughout was the Zollner photometer
erred tn in the Potsdam ifuldications as C III^ the objective of
which is of 21*5 mm* npeitury and 137 mm. focal length. (For
description see Puhl. Adv. Obs. zu Potsdam, Bd, viii., p 17, 1891.)
In thia instrument the image of the planet diiTers but littl« from
that of a star. Unfortmiately there was no suitable comparison
5tar near Saturn ; a Aquila^^ distitnt some 60*, was chosen as the
most convenient and was nsed throughout. Its magnitude haa
been taken as 0*96 (I.e., p, 235), so that Saturn should be referred
to the game system as former planetary observations here have
been. For the extinction correction the mean values for Potsdam
have been used.
A typical set of observations and the method of reduction is
awn in Table L
^bow
N
^
Tablk I.
1
Potfdam
SJd.Tlmv.
QuadfiLnt,
MfAii L
LrjgBkj-l,
Z«iitih Extinction.
■
L
II.
iir
IV,
rflojf
Dlst.
O.itT-
AM
b m
291
24'9
294
3^*5
28^47
9-3566
+ 111
5f5
+ 199
+ 08
«7
ivg
26*0
2S7
28 '9
2887
9*3677
...
61 -o
...
...
jj, «9
294
24 1
3^*8
26'^
28' IS
9' 3475
...
61-3
...
...
1 "
2S-0
26*9
273
30*0
28-05
9*3446
+ 29
57*3
+ 229
+ •06
1 ''
30-9
27-0
32.8
27-6
29*57
9*3867
-428
57-3
+ 324
-•03
1 '
27^1
26' I
30*9
28-0
2So%
9*3439
...
627
...
...
1 ''
304
26-1
27^3
37*2
2775
9"336o
63^3
...
1 36
33-2
261
29 '0
29*0
2907
9*373^
-372
57-2
+ 372
•00
^^n ft few cases^ however, only eight readings for euch were taken,
and occasionally a Aquilae was observed first.
The resulta of the observations are given in Talde IL
370 Mr. J. M. Baldwin, Photometric Measurtmenls LXVHL S,
Tablb II.
O.M.T.
AM. Corr.
0-C. M^
d h m o a CO
I Aug. II lo 55 660 467 +0-22 --04 I-I4 377 -1*82
2
0-23 096 + '18 OTJU
14 II 4 63-8 48-1 +o'o8 '03 foi 3-52 174 0-27 0*95 +X)6 0^
3 16 10 30 667 463 +0-37 -03 1-30 3-34 1-69 0-30 095 +35 oji
4 2D 10 45 63*4 487 +008 -02 I -02 2*97 1*56 0*36 o"94 +t)8 o^jg
5 Sept. 4 10 30 599 53-1 +0*12 -oi roy 1*46 1-05 0*59 0-89 +'i8 oy
6 Sept. 10 II 2 57*3 59*9 +0*13 - 'oi i*o8 0*83 -0*83 -o*68 o'88 +•» o-ji
7
8
9
10
10 29 58*4 56*1 +o'o6 "OI I'oi 073 079 0*69 0*87 +'I4 ofi
12 10 20 58*6 55*6 -0'02 'Of o'93 0*63 076 071 0*87 +*o6 oy
'3 10 56 57*2 60 "8 +0-02 'Of o'97 0*53 072 072 0*87 fio o'^
18 10 31 57*3 6o'i -o'oi -OI o*94 0-28 o'53 o*8o o'86 +x)8 oiji
11 Sept. 22 10 7 578 59*o +o*02 -01 0*97 0*59 -0*39 -o'S6 0*89 +"08 0^
12 24 10 21 57*3 621 +0*03 *oi 0-98 080 0*32 0*89 0*90 +"08 oy
13 25 9 52 57*9 58*6 -0*09 -OI 0*86 0*90 0*28 0*90 0-90 -104 oy
14 27 10 5 57 "5 61 4 -0*04 -oi o'9i ^I'li o'2i o*93 0*92 -"01 0%
15 28 9 2 598 53*6 -0*04 'OI 0*91 1*21 0*17 o'95 0*92 -"01 o-jj
16 Sept. 29 9 29 58-3 57*6 -o-io -01 0*85 1*32 -0*14 -0*96 0*93 -"oS o*^
17 Oct. 2 9 27 580 58*8 +002 '01 o*97 1-63 0*04 I'OI o'95 +'02 0*93
18 3 9 17 58*2 58- 1 o oo '01 o*95 174 o'oo 1*02 0*95 xw 0^
19 8 9 27 577 62- 1 +0-13 '02 ro7 225 +o'i6 i-io 0*97 +'io 0^
20 II 8 51 582 58-8 -004 '02 0*90 2*55 025 1*14 0*98 -x)8 OTJI
21 Oct. 20 8 51 57*9 63*6 +0'i6
22 24 8 48 58'! 65*5 +0-0I
23 Nov. 3 8 23 58-5 67-4 +0-19
24
27 6 2 583 61 -o +0-20
25 Dec. I 4 57 597 54-3 +0-13
-03 I -09 3-39 +0-50 -1-27 i-oo +*09 o-jl
•03 094 374 0-59 1-33 roi --07 op
•05 no 4*51 077 1*48 1*04 +•06 o?i
•09 1*07 569 0*90 1*84 I'oS -01 oy
•09 i-oo 578 0-87 1*90 1-09 -"09 01*
2. Only eight observations of etcl".
I. Hazy near horizon.
3. Seeing good ; at times (!loiuly in ]>arls. Wt. -i.
10. Only eight obs.'rvations of each. Cloutled over suddenly. Wt. J.
11. Light cloud visihle near moon. 14. Slightly foggy. Wt i.
16. Cloud rising slowly below a Aquilio. Wt. ^.
18. Kight observations ; seeing below a Aquilie l)ad. Wt. ^.
21. Somewhat foggy ; cloud rising Iwlow a Aqnila'. Wt. J.
22. Seeing not good, espec\&U^' below a A(\uilie. Wt. i.
25. a Aquilae very unsteady.
\
far. 1908. of Sdtuni, August to December 1907. 371
In Table II., Z, and Z^ are the zenith distjinces of Saturn and
AqutlcB rB9p43ctively for the mean time of observatinn ; AM is the
fbaerved difference of nia^'nitode (Saturn — ^a Aquilfe) corrected for
extinction ; the next column CDUlains the cunection to mean
opposition, and M^^ is the nias^nitude for mean opposition ; a is
the jihriFe angle ; A the eleviition of the Eirtli ; A' that uf the Snn
above the plane of the ring; M^, and M^ are the magnitudes
calculated from the form n lie of Miiller and Heeliger, in each case
usiing Mull«r^ii values for the con^ttiiits {L*\^ pp, 339, 341, and 348) ;
and O — C are the Viluee uf M^ — M^, and M,^ — Sf. respectively.
On exaiiiiniiiij the column M^, it 18 neen thut the early observa-
tiona are irn'gidar ; this 13 probably dtie to a large extent to want
of practice wtth the iustrnmxint, thesB beiug the Hrwt obst^rvations
that I had m^ide with it, althout;li I had been nsing another
Zdlliier photometer (photometer D) for stellar work for aome
months. The irregularity may also ari^e partly from uncertainty
in the extinL-tion correction in the fiiHt four observations, where
the ditference in zenith distance is so large (15 to 20 degrees).
If the night were not very clear, the difference in extinction would
l>e greater than that given by thit Potsdam tables, the values of AM
would be diminished, and the observed values would agree better
with the computed* On account of this irregularity I give the
reenlts deduced
(i) from all the observations,
(2) from the observations after opposition (Nos. 10-25),
^■ihe conclusions for the latter being, in my opinion, more reliable
P* ibniii from the whole series.
1^ From Table XL it appears^
'^M ( 1 ) That if Seeliger's formula were true, the magnitude of Saturn
^■during the ol>servations would be almost constantj becoming very
^ffllightly brighter towards the end of the series. The observations,
Non the other hand, show tliat tlie brightness reduced to mean
opposition shows a decided decrease after opposition, and so
Peeliger's formula cannot hold. If Seeliger*s second formula
(ix-t p. 4S9), which aaaumea a different law for emanation, be used,
' the results obtained are almost the same, the difference being
^^1 flightly more marked.
^M (2) On the other band, although the earlier observations of the
^^Hperies do not agree well with tlie results deduced from Miiller's
^^Hormula, yet those after opposition show a very satisfactory agree-
^vfnent. From the column O — ^C, giving the weight i to certain
^^observations as indicated in the table, the mean error is
" It
(a) for all observations ±0*115 ^^S*
(b) for Nos. 10-25 ±0*069 *>
If the reduction to **ring invisible'^ is applied to the mean
opposition magnitude (tbis reduction is +*o8i ou Axv^xial \\^
372 Mr. R, 1\ InneSj R^appearatw^ of 6iUur7is Mm(/\ i.x%
•ooo on October 3, and -♦- '040 on November 27), and the resQlti
gubstituted in the formula
h = Iiq + oa,
the values for the constants h^ and a det^riuined by the method of
least squares are
(a) for all observations fe^^ = 0*967, a = '0300, mean error of h±*o^^
(b) N08. 10-25
''0 = o*9 1 6, a = *o3 1 3, mean error of h±'\
while Miiller'8valueaare/?g = 0*87 7, a= '0436.
As before stated, the second set of values for h^^ and a
probably much more reliable than the first set.
It appeara then from the observations that the spheroid
Saturn shows a change of brightness with phase^ aad the chai
in magnitude can be well represented by the formula ~
A = 0^877 + *0436a
already obtained by Millie r from his long series of obeervations.
Astrophysieal OhHrvaJUrrij, Poindam :
1908 J&ti, 24*
Reappearance of Sat mm' s Ring, Januart/ 1908. i|
By R, T. A. Innes.
The following observations of the ghost-ring and of the
appearance of tht* ring were made here with the 9 -inch refract^)r.
1907 Dijc. 25. Ghost-ring seen on both sides, but more dil
tinct on /'. aide. Shadow of ring quite its own breadth N,
equator and very black — no longer lirovvn.
Dec, 28, Ring-like extension very faint, is more distinct oa
/, side — 'is to S, of shadow.
Dec, 29 and 30. Ghost-ring still visible.
Dec, 31. Jtist glimpsed (ghost-rtng) — 4 satellites seen cluae
to 8aiurn.
1 90S Jan, 3. Ghost-ring invisible— Mimas or Encekdus at f.
elongation.
Jan, 4, No ghost-ring seen*
Jan. 5 No trac« of ring-system — one satellite about 4" aad
another about 10"/, Saturn— the nearer of these would be half i
along the ring had the latt*n' been visible,
Jan. 6. 5^ 30^^ to 6^ 5^ G.MX Ring shadow appreciaUj,
narrower — no trace of ring.
Jan. 7. 6** 20™ G.M,T. Bad definition through \msm
thunderclouds. No trace of ring^ — two satellites, much closer
than Titan, seen closely /, Ring shadow narrow.
Jan. 8. 5^' 35°° (t.'M.T, (daylight). Ring visible — it id veqrl
fine, and not unlike the ghost- ring of a mouth ago. From wfA
recollection of the disappearance in October 1907, the ring loofci-^
as though it had reappeared about six hours earlier. The ring »
brighter/, the planet — tkia was verified by using the erecting i
Mat. 1908, Discovery of a Moving Object neai' Jupiter, 373
piece referred to in a previous comrauiiication^ when, had the
appearance been stibJRctive, there would have been no reveri^al.
Observation was continued until it clouded over at 6'* i^^ G,M,1\
Three satellites p. and Tiian /.
. On the same date, at about 6^ G.M.T., Mr. II. E, Wood, MSc,
[ made the following note: — "Ring seen dii^tinctly as a sharp well-
I detined line on either side of the disc. I consider that it was
I brighter on the /. side. I did not see any points of increased
^^rightness in the trace of the ring.'^
|h Jan. 9. Ring brighter—/, part decidedly thicker than p, part.
r^ Jan. II. /. part of ring is the thicker, but with the erecting
eyepiece this is not so certain,
1908 Januanj 1 3.
Noie an the disccverif of a Moving Ohjert mar Jupiter
^ {1908 CM).
(Cammuniente<l hy P. B. Cowellf F^ M.S., for the Aatfonomer Royal.)
Whilst examining a photograph of Jupiter's satellites VI and
yil, taken on 1908 February 28 with the 30'inch reflector, a
nt object was noticed by Mr. Melotte not far from the sixth
teUite,
Photographs taken previously were then examined^ and the
object was identified and traced hack as far as January 27. In
all there are eight photographs taken on eight nights. The object
slightly brighter than J.. VII, and its motion relatively to
fmpiter during the niorith over which the ubservutiuns extend is
4-7o''5S in 11. A. and +11' 39"'2 in JJech At present the
material available is insnfhcient to show conclusively whether it is
a new satellite or a minor planet.
Provisional positions weie obtained by referring the image on
each plate to two stars chosen from the Adronmnucihe Geieilsehaft
^Catalogue,
^ft More accurate places will be determined in the course of the
^b^utton of the photographs of J. VI and YII.
^^^™ Observations of Mo Hug' Object fiear Jupiter.
(Jitject— Jupltar.
I all
1 UftUiind
^ O.M.T.
Ap^ojent
a 908.
d h in
^•11,27 12 44
h m s
8 45 5178
fct*- t '> 5^
43 20-49
■ 3 t^ 37
42 21 '99
"^ 22 10 57
33 35 48
»3 8 34
33 M-23
24 12 25
32 47-26
27 to 59
31 4299
28 II 29
31 2r67
Apparent
l>uc.
+ 18
19
5 3'2
17 357
22 25*2
548*9
7 36-6
9 5»'2
15 "7*9
J7 53
ExpOAUre.
64min»
1 1 1 min.
80 min,
100 min.
42 min,
SomtD.
70 min.
80 min.
ni
-o
I
+ 1
B.A.
8
832
2*01
6*47
48*45
50'S6
53'«>4
0*04
2*26
lice,
41 417
41 47
33 59 o
33 367
33 9*3
374 Obaervations of the Trarml of Mercury. LXvnL 5,
Observations of the Transit of Mercury at Mauritiws^
1907 November 14. By T. F. Claxton.
Oq the afternoon of the transit the weather was cloudy, but the
Sun emerged from behind clouds about one minute before the internal
contact at ingress, which occurred at 13* 22** 25"* 19* G.M.T.,
whereas the computed time from N. A.. data was 13^ 22'' 25*47'
G.M.T. The telescope used was a 6-inch equatorial by Cooke,
with a diagonal eyepiece, power 80.
The Sun's limb was boiling considerably ; the definition of the
limb was bad, but of the spots at the centre and near the limb
good.
Mercury appeared as a clear-cut black disc, perfectly circular,
with no white spot or fringe.
No flashing across of cusps was detected.
Almost immediately after internal contact at ingress the Son
became obscured, and was not visible again until about 15 minutee
before internal contact at egress. A careful watch was then made
for any distortion, white spot, or disc, but none could be detected
in the equatorial.
On examining the planet in the 2-inch telescope of the
theodolite, however, with an eyepiece of power 40, undoubted
distortion was noticed ; but on rotating the graduated coloured
glass it was found that the distortion rotated with it, indicating
that it was an effect of the glass. No white spot or disc wu
noticed.
Mr. W. P. Ebbels, who continued watching the planet with the
equatorial while I was observing with the theodolite, detected no
distortion, white spot, or fringe.
The observed times of egress were as follows : —
W. p. EbbclB
with equatorial.
T. F. Claxton
with theodolite.
Computed
from N. A. diU.
d h m 8
d h m 8
d h m B
Internal contact . 14 i 46 24 o.m.t.
14 1 46 31 O.M.T.
14 I 46400.II.T.
Bisected by Sun'a limb 47 37 ,,
47 39 M
External contact . 4^ 36 „
4834 „
14 I 49 21 p
Mr. A. Walter took 1 1 photographs of the Sun with the photo-
heliograph near the times of ingress and egress, copies of five of
which are presented to the Society.
I
i
Mar, 1908. Fej'turbaiiom of Halletjs Comet in the Past 375
Tfu Perturhatiom of Haiteijs Comet in the Past Third Paper,
The Period from 1066 to 1301. By P. H* Cowell and
A, C, D, Cromtneliti.
We have again to acknowledge the continued kind o^si^tanceof
Dr. Smart and Measra. F. R, Cnj>ps and Thug. Wright, who have
one a large [>C}rtion uf the niechanical qnad natures for this period.
We commence by irnliciiting some am all corrections t«> the
alne« of n at various retnrna wliich we gave ii» the fir^t paper;
bese arise chiefly from i\w introduction of thw definite inteynd fnr
Ten us and the Earth from the table on p. 3 86. The corrected values
me, 153 I 46"*359. i45^46"'o2i, 1378 4s"*622, 1301 44"-862.
We next give the full table of pertnrbationi* for the revolution
1222 to 1301, It will be seen that the efTect of the change of wand
the aclton of the miialler planets has an appreciable intliience on
our former result.
iievolution
1222 to
1301-
naact!
UaiiU of u.
J....
Jrfci,
I*.
VeniM
CH 30
+ •0069
H
+ 198*
It
30-330
- '0013
- 50
tt
330-360
- '0070
0
JmU)
0- 30
^^oo4S
...
+ 128
m
30-330
^0049
-*• 3«
It
330-360
+ •0089
.»,
0
Jupiter
0- 90
• *2444
-186
-7040
*i
90-270
- *Ol7S
-167
+ 7894
*♦
270-360
+ '5694
-186
- 343
Saturn
0- 90
- 'O590
+ 24
-155s
11
90-270
+ -0569
- 37
+ 1437
i«
270-360
-•2366
+ 16
+ IS
Uranus
0-360
" -0147
I
- 34
Nepttme
0-360
-f'OOlO
- 6
+ 2ig
Sums + *o6a2
'543
Hence n at 1222 = 44"'862 - "'062 = 44"-8oo.
Theoretical period in days- ' ^90QO^ - 9^^ ^ 28qo8'''o.
44*800
CalcnUted date of perifielion passage 1222 August 307 = Julian
day 21676357. This is 17 days later than our former provisional
calculated value, and 9 days later than the day we otlopted for the
fiertbelion passage. As the computations for the revolution
1145 - 1222 indicated a still later date for the perihelion \iasaa^^
In 1222^ we have reconsidered our interpret&tvon ot l\u5 o\3»i&T^«kr
376
Messrs, CowM and Crommdin^
LXVIDLSi
tions of that year and decided to abandon our conjecture that die
date of passage of Yew She Te should be mid-August instead of
mid-September, though we still think it prbbable that the comet
was seen in August by some of the CbiDese obsenrersf since we
cannot otherwise explain the statement that it was seen in China
for two months ending October 8.
We now put the perihelion passage on 1222 September 10, with
a probable error of several days ; the conditions were thus practically
the same as at the return of 1682, when the comet was circumpolar
in Ursa Major in mid- August; we suppose now that the phrase
'' La Lune joignit la comete " refers not to the date in mid-Augnst
when the comet was first seen, but to September 13, when the two
bodies were really close together.
A further advantage of the new date is that it puts the comet
considerably nearer Antares on October 8 than the former Taloe
did-; this accords with the Chinese account. We pass now to the
preceding revolution ; as before, we provisionally took Hind's valoe
of the perihelion passage, viz. 1145 April 19, for the purpose of
calculating the perturbations, and deduce the following quan-
tities : —
Revolution
1 1 45 to
1222.
Planet.
Limits of u.
dn.
Jdcx.
J«^-
Venus
• •
0- 30
+ 0091
M
+ 275'
n
30-330
+ •0063
...
+ 157
>>
330-360
- -0021
...
0
Earth
0- 30
-•gi09
...
- 290
,,
30-330
- -0006
...
+ 209
,,
330-360
+ •0064
...
0
Jupiter
0- 90
+ •8690
-181
+ 24797
))
90-270
-•0506
-277
- 3501
II
270-360
- 9932
+ 256
+ 153
Saturn
0- 90
+ 1276
- 89
+ 3661
n
90-270
- 0411
^ 56
+ 921
M
270 -360
+ •0158
- 72
- 38
Uranus
0-360
-•01 18
- 42
Neptune
0-360
- -0015
...
- 46
Sums
•0776
-307
+ 26256
Now allowing for the fact that the adopted perihelion passage in
1222 is II (lays later than that previously calculated, the adjusted
value of w at 1222 =44''*82o ; hence that at 1 145 is 44"*82o + "'078
= 44"-898. And calculated period in days = ii25222pi^«
44'o9o
Mar. igoS. PerturbcUiom of Halley'tt Gomet in the Fitst, 37;?
r ]
828o"6 ilaye. Now 1222 Septetub«r 10 = Julian day 2167646,
enre the calculated dale of the precedin^j passnge^ * 139365*4=^
HAS -April (V4. This is i2'6 days earlier than lliTnTa date, a
imntity unfficiently small to make it certfiin that Hind*H identifi-
tion of the comet of 1145 with Ilalley's is cornict. Hind'M
date may be a few days in error, tlie i>l>servatioiKS heing too vagae
to fix it with precision. We take the elements as follows (on tha
' "d system), m being comptited from the perturbations and Q from
T assumed uniform motion^
T^ 1145 April 19.
n = 294'*5 \
^ ^ 39*9 Equinox of U45.
i= 16 S !
q= o*6
MoHon reiTogrofic,
Fe now pass to the preceding revolutionj Hind's date of perihelion
passage in !o66 being provisionally adopted for the purpose of
puting the |iertiirbatLons.
eoai|]
Revolniion 1066 to 1145,
LimlU of It,
P
\^m. JdiT.
Earth
Jupiter
Sftturii
Uranus
3o-33<^
330-360
o- 30
30-330
330-3^
o^ 90
90-270
270-360
o- 90
90^270
270-360
0-360
+ -0013
- 0087
-0093
- -0167
+ »oo79
- '0096
- '0614
+ '0710
+ 2486
-t- '0264
- '0222
f 0096
- "0050
+ 250
-204
-401
- 8
- 102
+ 58
+ 39
- 57
o
- 479
+ 190
o
- 1845
+ 7655
- 68
+ 773
- 604
2
o
Sams
•2319
-407
+ 5602
Allowing for the fact that the ndopted j)erihrlion passi^ge in 1 145
12 days later than that previously calculaied, the adjusted value
of fi at tt45 is 44'''9i8. Hence that at 1066 is 44"*9i8-"*232
= 44" '686. And calculated period in days^ ^^^ °^^.L ^^ =-
378 Perturbations of Hallet/'s Comet in the Past. LXYIIL 5,
28877 o days. Now 1145 April 19 = Julian day 2139378. Hence
the calculated date of the preceding passage ia 2110501 = 1066
March 28. This is only 4 days earlier than Hind's date, so that
his identification of the famous comet that preceded the Norman
Conquest with Halley's comet is fully established. His elements,
however, require to be modified, and the following elements, in
which T3 is given its calculated value, and ^ its value by our
formula, satisfy the observations with sufficient accuracy, con-
sidering the vagueness of the descriptions.
T = 1066 March 27.
^ = 293"-3)
Q = 386 > Equinox of 1066.
i= 16-5)
q — o'6
According to these elements, the comet would be a morning
star, in longitude 343", latitude + 9*, near B Fiscium on April 2,
would pass to the evening side of the Sun on April 24, when it
would be in Gemini and extremely near the Earth ; finally, on
May 15 it would be in longitude 148', latitude - 10*, and would
then be nearly stationary, its place on May 30 being longitude
149', latitude -8*. These places accord well with the description
from Pingre : **Au jour Ki-ouey (Ap. 2) elle ^tait dans la con-
stellation Che (a, fi de Pi'gase). On le voyait le matin; sa
longueur etait 7'; elle alia fort vite ver Test .... le jour Siu-se
(Ap. 24) on conimen9a a la voir de soir; .... dans ce meme
temps on rohserva dans les Gemeaux .... La comete, en Chine
cessa de paraitre dans la constellation Tchang (entre le coeur de
THydre et la Coupe)."
The conditions in 1145 and 1066 were not unlike tbo?e
predicted for the return of 1910. in each case the comet was
discovered as a morning star, then lost in the Sun's rays; on its
emergence it was near the Earth and moved with great rapidity,
finally becoming stationary in the neighbourhood of Hydra, where
it was lost to view.
Erratumy — M.N.^ vol. Ixviii., No. 2, p. 123.
Resolution 1456 to 1531. Venus 33o''-36o° \dn^
for 4- "'040 read - "009. Sum of column to be altered accordingly.
[ FeriurhUimis of Halley's Comet, 1759-1910. 379
0 Perturbations of HaUei/s Cornet^ 1 759-1910,
By P. H» Cowell aud A. C. D. Crommeliin
tiirlmtions by Jupiter and Saturn from 1S35 to 1910
tig:it«'d in AI,N., wL Ixvti,, Nos* 6 and 8» Tlie present
istigates those produced by Venus, tlte Earth, and
ar the two perioda 17 59-1 835 and 1835-19 10.
perturbations by Veuus and tlic Enrtli at the beginning
od 1759-1835 have only a very tiiHing influence on the
le next teturn, de Ponteconlant*s results have been
ley are given in Cmm, des Tempn^ 1838, p. 118, and
tr le calad iles periurbatiof^s de la coniite de Halley^
\,
n of his values of dn lot Venus from valuea of u o^ to 20*
18*) ia +"'00315 in sexageginm! seconds. As he has
ed the direct action of Venus on the comet, we have
action of Venns on the Sun, wfdch is given below,
inatea of Venus and the Earth are taken throughout
talde, M,N., vol Ixviii,, ^o. 2, p. 113. Ji-e^ is
0*354. The Julian days of perihelion in 1759, 1835
2 '57, 239I59S-94-
<A^ ActUm of Fmws o» tlu Sun, 1759, for u = q* to lET,
-,i1nu*
-eVcoiti.
- '093
Denotes that the qutntttj h&s been divided by z.
>of(-;
jsinii-hp^ V ~^^ ^^* **
')-
i'6i%.
380 . Messrs. Cov)dl avid Crommelin, LXVin.5,
The reducing factor to reduce ^dn to seconds of arc
= ^^ aWdu (M,N.y Ixvii., 2, p. 122). The log of this for
365**56
Venus =7*2870.
Hence \dn (o* to 18', Sun action) =.-"•00325.
Hence total jdn (o* to i8')= +"'00315 -"'00325= -"'oooi.
The following is a computation of the direct and indirect action
of Venus from m = 1 9° to t* = 30°.
u
x'-x.
y-v.
r.
X^-X
xf
P5'
'-^
dm.
19-
- -22
-1-22
+ •26
-•108
-r66o
-•597
+ 726
+ •822
20
- -05
ri7
•25
-•029
1*480
•684
i"P5o
-908
21
+ -15
113
•24
+•095
1-236
713
I "343
•962
22
•39
rii
•21
•231
•908
•656
1-604
^58
23
•67
I'lO
•17
•305
•479
•500
1809
•84s
24
•96
I-I5
•12
•284
•053
•341
r88o
•640
25
1-27
1*23
+ •05
•230
+ -422
•222
1-847
•395
26
1-58
1-36
- '02
•174
•865
•150
I 680
+ •114
27
1-87
1*54
•09
•131
1-280
•108
1*380
-•185
28
2-13
178
•16
•099
1*590
•083
•935
•471
29
236
206
•21
•076
1*760
•067
+ •386
•715
30
+ 2-51
-2-38
-•25
+ •060
+ 1 760
-•057
-•259
-•447
* Denotes tliat the quantity has been divided by 2.
e^ cos n.
Suiu of dn= +3*826= +"-0074 after multiplication by factor
whose log is 7*2870. Hence total Uhi (o* to 30') = +"•0073.
For the direct action of the Earth on the comet from w = o* to
w = 3o* in 1759 we have used de Pontecoulant's figures, revising
his values between w= 13" and u= i8*^, where we detected an error.
Our revised values for dn are 13"^ -^''01330, i4*-''*02585,
i5« -^^-01581, 16'^ + ''06098, i7« + ^'*o2i72, i8« + '''oo996 (the
symbol '' denotes centesimal seconds). Further, his value of log
m for Earth should be reduced from 4*4820 to 4*4781. With
these corrections ^d/i (o" to 30*) = +"-02003 ^^ sexagesimal seconds.
To this we have added the action of the Earth on the Sun, the
investigation of which is given below.
[ar. 1908. Ferturbatiam offfalley's Comet, 1759-1910. 381
tt.
ST'.
y'.
-^rinu.
-^v....
o*
-•61
+ 74
•000
-095*
I
•59
76
+ •010
•195
2
•56
79
*020
•202
3
•53
•81
•028
•207
4
•49
•84
•034
•215
5
•44
•87
•038
•219
6
•39
•89
•041
•224
7
•35
•91
•043
•228
?
•30
•94
•042
•236
9
•25
•95
•039
•237
10
•19
•97
"O33
•239
II
'»3 .
•98
•025
•242
12
-•07
•99
+ •015
•241
13
•00
i-oo
•000
•242
14
+ •08
1*00
-•019
•241
15
•16
+ •99
•041
'2^S
16
•24
•98
•063
•231
17
•33
•95
•093
•223
18
•42
•92
•124
•214
19
•51
•87
•160
•202
20
•61
•81
•198
•183
21
70
73
•240
•165
22
77
•64
•274
'143
23
•86
•51
•321
•112
24
•92
•38
•358
•083
25
•56
•22
•385
•048
26
•97
+ •06
•407
-•014
27
•96
-13
•418
+ •029
28
•91
•31
•413
•067
29
•83
•47
•393
•102
30
+ 71
-•64
-•I75'
+ •069'
* Denotes that the
quantity has been divided by 2.
idn = sum of ( --73 sin W + -73 ^i -e^ costtj= + 1*135.
MultiplyiDg by
6w
:ahidu whose log is 7*3758 we obtain
365'256
[-'•00270. Hence total jdn (0° to 30**) = +"•02003 + '-00270
= +'-0227.
27
382
Messrs. CoweU and Orommdin,
LXVIII.5,
We next give the investigatioit of the perturbations of the
comet by Venus at the return o( 1835, including Ixtth the direct
and indirect portions, and dividing theai into the two periods
u = 330"* to 360* and 1* = o* to 30'. The column t gives the
number of days before or after perihelion passage.
u.
(.
X.
y.
«'.
y.
jr.
^-
330-
177-90
-«*835
-2*284
+ •595
-330
-•259
■f*0793
+«*544o
+ 0638
- -8560
33«
165-62
1*680
a-214
•446
*5a3
■237
•1048
i*t6io
•0834
i-36«»
33a
«53'95
1*529
2*144
256
*652
•191
•1404
•6700
•"74
1-7060
333
148*89
«*383
2*074
+•051
•711
*128
1841
■f •«343
•«753
il7»
334
>3a*43
1-243
2*002
-147
•705
-*o58
*aa3«
- 3894
•a644
1-8670
335
128*55
1*107
1*931
•324
•643
+•014
•2287
•86a8
•3761
i*7iao
336
11323
•976
1*858
•467
•54a
•079
*i8o5
1*2500
•4666
i-4Joe
337
X0443
•850
1*784
574
•411
*»37
0991
1*5410
•4930
1*IO|0
338
96-16
729
1*711
•643
•a«5
•>83
+ *o«76
1*7305
•4645
•7130
339
88-38
•614
x*637
•675
-•114
*ai8
-0167
i*8aoo
•4170
-•y»74
340
81*07
•503
1*562
*676
+ •034
-242
•0404
1-8230
•3726
+•0917
34»
74*21
*398
1*487
•650
169
*254
-0517
«*7530
'3400
•4557
342
67-78
•298
1*412
•605
•291
-256
•0574
1*6290
•3182
•7836
343
61-76
•203
>'336
*543
•398
•251
-0598
1*4600
3049
10700
344
56-11
•113
«*259
•472
*488
-240
*o6i6
1*2670
*a995
1-3100
345
50*84
--029
1*182
•395
*559
•225
•0635
1*0580
•3019
1*4970
346
45*91
+ '050
1*105
313
*6i4
•205
*o654
•8364
*3«o4
1*6410
347
41*29
124
I "028
*234
*657
•184
■0689
•6240
•3244
i75»
348
36*97
*192
*95o
•155
•686
•161
-0728
4125
•343«
1*8255
349
32-93
*25S
*872
•078
•704
*»37
•0788
•2070
•37»9
1-8690
350
29*13
•312
•793
--006
*7i3
*ii4
*o866
- *oi59
•4101
1-8880
351
25*56
•364
•715
+ •063
*7M
*o89
•0961
+ *i665
•4561
1*8870
352
22'20
•411
•636
*I27
*7io
066
*io87
*335a
•5156
1*8740
353
19*02
*4S2
■557
•186
•698
*o43
•1256
•4899
•59a6
1-8100
354
16-01
*487
"477
*240
*682
*022
•1481
•6308
•6952
i'79«5
355
13*13
•518
•398
*290
•663
+ *002
-1785
•7612
•*3o8
1*7405
356
10*36
*543
•318
•339
•641
- *oi9
*2i6o
'8886
x'oi54
1-6803
357
7*69
•562
•239
•382
-616
*038
*2587
1*0000
1*2763
1-6110
358
5*09
•576
•160
•422
*588
•057
•3427
«*«03S
1-6650
1*5370 •
359
2*53
*585
- *o8o
*459
*557
•075
•4504
11990
2-2765
1*4550
360
0*00
+ -587
*ooo
+ •495
+ •524
-092
-•584a
+ 1*2910
+33275
+1-3^ '
Indicatei that the qauitity has been dlTided bj 2,
Sum of fin = - 4-294 = - "-00827 after multiplication by factor
whose log is 7*2844.
^^^^^^^^^^^^^^^^^H
Mar. 1908
K Peiiurbations of Halley*& Comet ^ 1759
-1910. 383 ^1
Perturbations by Venus, 1835,
The values of t ami x, y are
with the sign of y changed) as tho
t* = 0* to 50". J
the same (in reverse order, and ^^
se in the last table. ^H
0*
+ •495
+ '5^4
-092
- •5842 +1-2910
y -y
^3*3275 +1
•3670
*248» ^W
1
-527
•489
•109
7450
13720
5*2510 I
*2740
t*044 ^1
2
558
*450
*I25
- '5700
1 *4520
9 iSoo I
•1710
2098 ^^^1
^^3
584
409
*14T
+ 2*0200
1*5180
i5'6ooo t
•0634
^^H
B«
•610
'364
•157
12*1000
r586o
+ 8*2900
*946o
^^^H
^5
■632
3'6
•172
io"5ooo
I 6400
-7-5250
•8200
^1
[ ^6
•652
•264
^iSS
4*6700
1*6920
6*0350
'6850
2-004 ^H
^Mf
*668
•208
'202
2*2500
1 7320
3*6300
•5390
rnj 1
^^
^6So
153
^216
l'2S00
r76io
2*3000
'3963
*6o9 ^^A
[9
•687
•080
•22S
7720
17790
1*5200
*2072
^^1
■ko
•688
+ 009
•239
•5120
1 7819
1*0700 +
-0233
+ ^H
St
•6S2
--067
•249
•3590
17664
7S90 -
1740
^1
12
'666
*I45
'256
'2605
17249
•6020
•3756
^1
13
^41
'229
•260
*i95o
1*6602
•4743
•5931
^j^B
14
^3
•315
•260
■1500
i'5<ii8
•3840
•8158
^^1
«5
•554
'399
254
-117S
1-4380
'3194 I
'O35O
^^H
16
■48S
^481
•244
•093S
1-2700
'2717 I
•2515
■
17
'40$
'559
•229
•0757
I 0558
'2357 \
•4570
■
fS
•307
•62s
•20s
'0622
*8o24
2094 1
•6337
H
UP
•192
678
*«73
■05 1 S
•5036
'1900 1
7780
^1
H»
+ 'c65
709
•133
•0440 -f
' -1711
1761 I
8660
^1
^Bi
-•074
714
•085
•0383 -
•1956
*i668 I
'8870
^1
^Bs
219
•687
^•030
•0346
•5811
*|626 i
•S23S
^1
^B3
•362
•622
+ •030
•0330
•9654
•1626 I
6590
+ 041 ^H
B^
491
^518
091
•0339
I '3 1 50
•1662 1
•3870
'266 ^1
^5
•596
372
•151
•0387
i*6ois
*>745
•9995
•50s J
a6
•66j
- M91
*202
•0492
17860
•1859 -
•5146
^m
27
'677
^*oi8
*240
•0676
1-8260
'1^7 +
•04SS
^1
28
•629
'236
•257
•0938
I "6950
*J989
•6358
I ^H
29
•511
•442
•247
•1198
J '3730
•J816 I
*l88o
t ^H
|o
-'3*9
+ •605
+ '208
+ -1298
•S79S
- *I447 +i
•6180
-^ ^1
* Indicates Uiat tlie qu&ntity h&s b«eii divided by 2,
■
^B Sum of (f n = - r 1 44
^Vrliosc log is 7*2844.
— -"'00220 aftei
* mulbiplicatton by factor ^|
384
Mess-fs. Cowell and Crominelin^
LXVIIL5,
The next two tables contain the perturbations by the Earth iu
1835, the values t^ x, y being the same as for Venus.
«.
«'.
y.
t.
V-v
dn.
330-
+ •442
+ •911 -
-•030
+ -038
+ •426
+ -053 ■
f -877
+ -187^
331
•611
•804
•092
•042
•585
•055
769
•421
332
748
•673
•147
•048
713
-059
642
•442
333
•848
•525
•194
•055
•806
•064
•499
•439
334
•920
•367
•233
•065
•875
•071
•349
-41S
335
•960
•208
•263
•078
•915
•080
•198
•381
336
•973
+ •053
•28S
•094
•929
•092
+ •051
•330
337
•964
-095
•299
•117
-923
•108
-091
•269
338
•937
•233
•306
•146
•901
•130
•224
-200
339
•894
•357
•308
•189
-864
-160
•345
*I23
340
•841
•470
•304
•247
•816
•201
•456
+ 039
341
778
•568
•297
•335
759
•261
•553
-057
342
710
•653
•286
•465
-697
•350
•641
•167
343
•639
•726
•273
•679
-630
•429
716
•307
344
•565
787
•259
I 047
•560
729
780
•501
345
•492
•839
•244
1734
•490
1*140
•835
•S05
346
•419
•879
•225
3-690
•418
2-259
•877
1*563
347
•349
•912
•208
6-368
•350
3 281
•914
2-390
348
•282
•938
•191
+ 9*594
•284
+ 1-279
•945
-2-487
349
•217
•957
'^72,
-4-989
-219
-II-I4S
•966
+ 3526
350
•155
•971
•156
6-871
•157
77S0
•985
2-918
351
•096
•9S0
•140
4-130
-098
4-083
•99S
1-432
352
+ •040
•984
•123
2-582
+ -041
2-427
I 003
•722
353
-•013
•987
•107
1766
-•013
1-629
1-007
•370
354
•062
•9S6
•092
1-285
•063
1*191
I 009
•174
355
•III
•982
•078
•986
•114
•914
1*007
+ -053
356
•157
•976
•064
7«7
-161
740
1*003
- -022
357
•199
•968
•050
-649
•205
622
•997
•072
358
•241
•959
•037
•547
•249
•536
•990
•105
359
•281
•947
•023
•471
-290
-472
•978
-125
360
- *320
-•934
- -oio
- -410
•331
- -422
- -967
- -069*
't
* Indicates that the quantity has been divided
I by 2.
Sum of dn= + 3-774 =
whose log is 7-3733.
+ "00891 after multiplication by factor
1-1910. 385 ^H
Mar. 1908
Perturhations of Eallei/s Comet, 1759
tts
x".
y.
f.
^H
P^
-•3w>
- -934
- 'OIO
-•410
-'331
- 422 -
•967
H
[ '
•360
*9i9
+ -004
^364
•374
*385
'953
^M
^^
•400
•903
•017
'325
*4»5
154
'937
^M
mz
•439
•883
T>ll
•295
'457
■330
•918
^H
4
•478
•861
•045
■269
•49S
•311
•897
^M
5
516
•S37
■059
•247
539
•296
•874
^M
6
•556
•809
•075
•228
•S»i
-281
*84S
^M
7
•595
77s
•090
•214
'623
•273
'815
^M
S
•63s
743
•106
•201
•665
•265
778
■
9
676
•70s
■I2J
MS9
709
•258
740
•040 ^^^
10
716
•661
*I40
'iSo
75"
'255
694
^H
II
756
•611
•157
•174
793
'255
■641
^^M
t2
795
•553
•176
'167
•S36
255
'582
^H
«i
•831
•489
•193
•163
■874
•259
•514
^M
14
•863
418
*2I2
'^59
•908
•265
•440
■
*S
*894
34*
'229
•«57
'940
276
359
■
16
•918
253
•246
'rs6
■966
•292
•266
^M
«7
'935
•157
•262
•154
981
•3»3
•16S
H
iS
*943
- -053
•276
•150
'9S7
•341 -
'055
■
19
•941
4- -059
*288
'I44
•983
379 +
•062
H
20
•925
•176
'297
*i3o
•964
•42S
*i83
^1
^l
^892
•300
*300
•101
•926
•488
•3"
■
22
•841
'425
'299
-•048
•869
*553
•439
^1
23
771
•550
•293
+ *o39
793
•601
'565
^1
24
*67S
■670
•279
'ISO
•691
•599
•6S3
^1
2S
•S63
780
•256
•249
•569
•52s
789
H
26
•425
•875
•225
•291
'426
•401
•S77
•605 ■
^7
267
'947
*l86
•274
•266
•277
•943
^1
2S
-^
991
•138
•227
-•oSS
•1S2
'975
^1
29
-f MOJ
IXXX)
•oSi
•177
+ 100
'121
'975
^1
30
+ •300
+ 965
-1- '019
+ '135
4- -290
-•083 >
'934
+ 'o8t* ^M
' Indicates that t1
le quantity
r haa been diyidrd by 2.
^1
L
Sum of dn = + ^
5-889=.
+ '•0139
t after multiplicatiou by factor ^|
■rb
om iug 18 7-3733
'
^H
In the above inveatigati
ons we liave restricted ourselves
to the ^H
determmutiou of tl
le jturturbatioij (
jf n, tbe
mfoiu da
ly motion, as ^H
the
examination of
aeVLTnl
revokitinns lias shown that the e
duct of ^^M
Venus and the Knfih on th
e other e
euients 4
Df tbe comet's
orbit h ^H
always negligible.
Jc/{ is fou&d with sufticieut accuracy by muki- ^^
ply
log jdn
from 0*
to jo' hy period
m days
^80.
A
386
Messrs, Ootoell and Crommelin,
LXVIIL5,
^dn from 330** to 360* does not give any sensible contribution
to d(. We have uniformly adopted 330' to 30* as the interval
over which the perturbations by Venus and ihe Elarth should be
determined hy mechanical quudralures. Beyond these limits we
use the definite integral method described M.N.^ v«)L kvil,
No. 6, p. 391, neglecting the quantity denoted by V^ as insensible.
The following tables have been constructed, enabling the valuex
of jdn, \dl^ to be taken out at sight. The argument is the Julian
day of the comet passing the positions 1^=30% 330*. Multiples
of 224^7023, 365**'26i4, for Venus and the Earth respectively,
must be added to the Julian day to bring it within the limits of
the tables. J^f for w = 330"* is always negligible. The tables have
been constructed for an average value of a, but they are sufficiently
accurate to use without modification for any revolution. The
tabular quantities are to be applied algebraically, with the signs of
the tables, to those deduced from the mechanical quadratures.
VenuB.
Bftrth.
Jul.
M = 3o
0
li = 33o'
Jul.
14=30
« = 33o'
Day.
239
jdn.
f..
\dn.
Day.
239
jdn.
'k
Jrf».
1492
+ •0069
+ 195'
- '0013
1494
+ -0002
+ s
+*oooS
1501
•0061
172
•0029
1509
•0016
45
•0018
1510
0051
144
•0041
1524
•0029
82
•0025
1519
•0040
"3
•0052
1539
•0043
121
•0029
1528
•0028
79
•0062
1554
•0054
152
•0028
1537
•0015
42
•0069
1569
0064
180
•0026
1546
+ •0003
-1- 8
•0073
1584
•0073
206
•0019
1555
•0008
- 23
•0074
1599
•0078
220
+ -000S
1564
•0019
54
•0071
1614
'OO79
223
-•0003
1573
•0025
70
•0065
1629
•0076
214
•ooiS
1582
•0028
79
•0056
1644
•0069
195
•0033
1591
•0030
«5
•0046
1659
•0060
169
0046
1600
•0027
76
•0033
1674
•0049
138
•0059
1609
•0022
62
•0020
1689
•0036
102
•0070
1618
•0014
39
-•cxx>8
1704
•0022
62
•0076
1627
- -0004
- II
+ •0004
1719
+ •0008
+ 23
•ooSo
1636
+ •0008
+ 23
•0016
1734
-•0003
- 8
•0079
1645
•0019
54
•0023
1749
•0012
34
•0074
1654
•0032
90
•0028
1764
•0022
62
•D06S
1663
•0044
124
•0032
1779
•0026
73
•0056
1672
•0055
155
0031
1794
•0027
76
•0045
1681
•0064
180
•0026
1809
•0026
7S
•0034
1690
•0069
195
•0019
' 1824
•0022
62
TX>20
1699
•0071
200
+ •0009
! 1839
•0012
34
-xxoS
1708
+ •0071
+ 200
-•OQO\
\ ^^s^
-'OOOI
- 3
+ •000$
Mar. 1908. Perturbations of Hcdley's Comet, 1759-1910. 387
Hence we obtain M^ 9 i759> 30 « + -0004
©1759, 30= +0035
91835, 330= +-0025
30 = - 0002
01835, ZZ^= -'0051
30= - 0025
These have to be added to the perturbations already obtained
by mechanical quadratures.
We next investigate the perturbations by Neptune for- the two
revolutions 1759-1835, 1835-1910. The co-ordinates of Neptune
are taken from the table, M,N,, Ixviii., No. 2, p. 120.
Bevohition 1 759-1835.
:VaterT»l
%ajemn.
X.
V.
r.
of.
y.
f.
af-x
9f
?5-
y-y
o-o + -6
00
•6
-28-0
+ 57
+ 9-1
- -00100
- 00103
+ ^00020
+ 00021
0-2 -
•3
+ 1*4
1*4
280
5-8
9-1
•00108
•00103
•00017
•00021
0-7
2-9
27
3*9
27*9
6-4
9-2
•001 28
00103
00019
•00024
2-0
6-9
37
7-8
27 '5
7-8
9-3
•00170
OOIOI
•00034
•00029
41
11-9
4'4
127
267
lOI
9*4
•00237
•00099
•00091
•00037
7*4
17*5
4-6
i8-i
251
13*5
95
- '00222
•00093
•00259
•00050
11-8
231
4*4
23-5
224
177
9*2
+ •00017
•00083
•00313
•00065
173
28-1
37
28-4
181
22-4
8-6
•00083
•00067
•00156
•00083
23 -7
32-1
27
32*3
12-2
26 4
7*5
•00062
•00045
•00073
•00097
309
347
+ 14
34-S
- 4-6
292
57
•00043
-•00017
•00039
•00108
38-3
35-6
O'O
35-6
+ 3*4
29*6
3*3
•00033
+ •00013
00025
•00109
45-8
347
-i'4
34-8
ii'S
27-8
+ 7
•00028
00042
•00018
•00103
53-0
321
27
32-3
182
23*9
-1-9
•00027
•00067
•00014
•00088
594
281
37
28-4
23-0
19*0
4-0
•00029
•00085
•00013
•00070
649
231
4 '4
235
26*2
13-6
5-8
•00034
•00097
•00012
•00050
693
17-5
4-6
i8-i
27-9
8-9
6-9
•00041
•00103
•00012
•00033
72-6
II-9
4*4
127
28-6
5*4
7-6
•00053
•00106
•00013
•00020
747
6-9
37
7-8
28-8
30
81
•00069
00106
•00013
•oooii
76*0
2-9
27
3*9
28-8
1-5
8-3
•00088
•00106
•00012
•00006
76s -
- '3
-1-4
1-4
288
0-9
8-4
•00104
•00106
•00008
00003
767 + '6 o-o '6 +28-8 + o^7 -8^4 + •001 1 1 + -00106 -voooo-j^ Jrwaw^-x^
388
Messrs. CowM and Crommdin,
Lxvm.5,
u.
dn.
dn X (Sir -nQ.
(xY-yX)tln«.
rX.
rXje,
rYy.
0*
•OOCXX)
•00000
•00000
+ •00001*
•COO
•000
i8
-OOOOI
- "00006
+ •00002
- 00007
•000
•000
36
*ocx)i4
•00087
•00048
•00097
+ •003
-•001
54
•00057
•00349
+ '00179
•00538
•037
+ •001
72
•00135
•00803
-00030
•OI7S3
•209
•030
90
- ^00129
- 00733
03064
- '02335
+ -408
•174
108
+ •00114
+ •00606
•05876
+ '02350
- -543
•257
126
•00132
•00643
- '02107
•04260
I '200
+ •077
144
•00058
•00252
+ 00283
•03456
I'llO
-•021
162
+ '00002
+ •00008
+ 00714
•02088
•725
-1034
180
-•00021
-00066
•00000
+ ^00712
- -253
XW)
198
- ^00017
- '00004
-'00903
-'00487
+ -169
+ •041
216
+ •00009
+00018
•01335
•01292
•415
•065
234
•00036
•00050
01126
•01590
•447
•060
252
•00057
•00055
•00571
01481
•342
•039
270
•00062
•00037
- '00082
•OII22
•196
•017
288
•00051
•00017
+ •00144
■00673
•080
+ •004
306
•00030
00005
•00122
•00289
•020
-•001
324
+ 'OOOIO
+ 'OOOOI
•00039
'OOO7O
+ •002
•000
342
•00000
'00000
+ ^00002
- '00003
•000
•000
360
•00000
•00000
•00000
+ •00001*
•000
•000
Sum +-00187 -'00356 -'13561 +-OII34 -1*503 +-708
• Indicates that the quantity has been divided by 2.
X denotes
X - X X
p3 ^.'3
Y denotes ^^ "^-^.
dn = X sin M - ^^i - e- Y cos ii, Ji - e^ is taken as 0*254.
The factor to convert Id7i into seconds of arc = — ahn\
J ^6s;'2t:6
67r
365*256
'du.
log /: .;~z""^'7i27, log a= 1*2564 for revolution 1759-1835,
= 1*2480 for revolution 1835-1910, log 7?^' = 5-7122, du = iS^ in
seconds of arc, log 0??^ = 4*8 11 6, log - = 0*0145.
Hence Idn— + "•00 13 7.
Mar. 1908. PeriwrbcUians 0/ HiaUe^s Comet, 1759-1910. 389
The factor to convert ldnx{2v-rU) into seconds of arc
=s ^a^mdu, giving - 1 1"'6 for the numerical value of the integral.
jdrs = '^^j{xY'-yX)BinudU''—JlT?jrXdu
--8"-4
jdl: - - jr^ jdrs - 2m'jr{xX + yY)du + jdn x {iw - ni)
= +2"i + s"-3-ii"-6=-4"-a.
Neptune, revdutum 1835-1910.
Intarral
X.
y.
r.
fi.
••
t.
af-9
7i'
^
»•
00 + -6
•0
•6 +28-8
+ 07
-8-4
+ -001 1 1
+ •00106
+ •00003
+ •00003
5
0-2 -
- -3
+ 1-4
1*4
288
+ 0-5
8-4
•cx)io5
'00106
-•00003
+ •00002
ft
09
2-8
27
3*9
28-8
- 0-3
8-5
•00089
*ooio6
•00008
-•ooooi
t
20
67
3-6
7-6
287
I '5
87
•00071
•00106
•0001 0
5
4-0
11-6
4*3
12-4
28-4
3-8
9-0
•00055
•00105
•0001 X
•00014
1
71
I7-I
4*5
177
277
7-2
9*2
•00043
•00102
•0001 1
•00027
\
11-4
22-6
4*3
23*0
25-9
12*0
95
•00034
•00096
•00012
•00044
i
168
27-5
3-6
27-8
22-8
17-2
9*3
•00030
•00084
•00012
•00063
1
231
31*4
27
31 '5
i8-o
22-5
8-6
•00028
•00066
•00014
•00083
s
30-0
33*9
+ 1-4
34-0
II-5
26-8
7-3
•00029
•00042
•00018
•00099
)
37*2
34-8
•0
34-8
+ 4-0
29*3
5-5
•00033
+ 00015
•00025
•00108
i
44*4
339
-1-4
34-0
- 4-1
29-6
3*1
•00043
- ^00015
•00040
•00109
>
51*3
31*4
27
31-5
11-5
27-8
-07
•00061
'00042
•00076
•00103
1
57-6
27-5
3-6
27-8
17-1
246
+ 1-4
•00080
•00063
•00162
•00091
1
63-0
22-6
4*3
23-0
21*5
207
3*3
+ 00023
X)oo79
•00348
•00076
3
673
17-1
45
177
244
16 '9
47
- '00210
00090
•00357
•00062
5
70-4
II-6
43
12-4
260
140
57
•00236
•00096
•00159
•00052
>
72-4
67
3-6
7-6
27*0
II-8
6-2
•00173
•ooioo
•00070
•00044
1
735
2-8
27
3*9
27 '4
10-6
6-5
•00130
•001 01
•00042
•00039
I
74-3 -
■ "3
-i'4
1-4
276
9.9
67
•00108
•00102
•00034
•ooo^l
>
74*4 + -6
•0
•6
-2r6
- 9-8
+ 67
•00098
- '00102
-•ooo-jA
, -•«»->!»
390 Messrs, Cowell and Crommelin, LXYUL 5,
u.
dn.
dnx
sinu.
rX.
rXaL
rYjf.
(»Y-ifX)
0(W«
tY,
o-
•00000
•ooooo
•OOOOO
+ -OOOOI*
•000
•000
XXXXX)
18
+ •00001
+ •00006
•OOOOO
-•OOOOI
•000
•000
+ •00003
7
36
-•00009
-•00056
+ •00038
'00066
+ -002
-•ooi
XXX>52
27
54
•00027
•00165
•00123
'00266
*oi8
-•001
•00089
- 3'
72
•00048
•00286
+ •00172
00620
•072
+ •002
+ xxx)56
+ 37
90
•00059
•00335
-•00009
•01044
•179
•013
•ooooo
283
108
•00056
•00298
•00434
•01426
•322
•032
+ •00141
735
126
•00036
•00175
•00975
•01 501
•413
•051
•00707
1418
144
-•00008
-■00035
•01 21 5
•01 197
•377
•059
•01677
2176
162
+ •00016
+ •00060
-•00845
- ^00442
+ -150
+•039
•02603
2754
180
+ •00021
+ 00066
•ooooo
+ •00626
- ^218
•000
•02889
2889
198
-OOOOI
-00003
+ 00701
•01972
•668
-•033
•02159
2347
216
•00055
•00107
+ •00335
•03244
1-020
-•023
+ •00462
+ 851
234
•00127
•00179
- ^01991
•03975
rioo
+ •071
-•01443
- 1975
252
- -00118
- '00113
•06266
+ ^02346
- ^530
•269
-•02034
6257
270
+ •00120
+ •00072
•04504
- ^02124
+ '3^3
•235
•ooooo
5217
288
•00I4I
•00047
-•00603
•01736
•201
•057
+ •00196
1327
306
•00063
•oooio
+ ^00072
•00555
•038
•007
-•00052
198
324
•00018
+ -OOOOI
•00041
•001 13
+ '003
+ •000
-00057
II
342
+ •00001
•ooooo
+ •00002
-•00008
-000
•000
-00006
-r 4
360
•00000
•OOOOO
•ooooo
+ -OOOOI*
-000
•000
+ •00001
•OOOOO
Sum -•00163 - '01 490 --15358 4-01069 -1-398 +-776 + -07443 --01556
■i/n- - "-001 18, J(2ir - iityin= - 46" '8.
* Indicates that the quantity has been divided by 2.
By the formulae given above / dvs = - 9"-3
\dt,= - 46"-8 + 2"^4 -h 4"^i = - 4o"-3
Again, | de = ^'-^^^^-^7^ / (•'Y - yX) cos n du + / rYdu
= + -0000043.
We have now completed the investigation of the perturbatioM
of the mean motion and perihelion by all the planets whose effect
is sensible, with the exception of Uranus. We have decided that
it would be waste of labour to repeat do Pontecoulant's work ou
this planet, seeing that (i) the whole effect on the time of the next
return is only 2 days, which is unlikely to be more than i day in
error ; (2) owing to the fact that the period of Uranus is not very
different from that ol t\\^ comet, the perturbations by this planet
W. I
knge
1 908. Perturbations of HalUi/s Comet, 1 7 59- 1 9 1 o. 39 1
nge in a fairly uniform progression from one revolution to
lotUer. We timi that tbis test 18 satiafiod by de Pont ik^ou hint's
|?anii8 perturbations for the three revolutions 1682-1759,
;'S<?-^^35» 1835-1910.
We had orij^inaily expected that we should only find it
cessary to investigate the revolution i835-i9io» with the single
ioeption of tlie perturbations by Neptune in the precediitg re vol u-
ki. Huw*»ver, on examruation w«^ found larj^e discordances in the
fferent deteruii nations of 71 in 1835. In paTtit:ular, tlie values of de
tuctiuUnt and li0.senber>;er dirler by 0^*05, implying a ditfereuce
entire month in the date of the next perihelion passage,
In view of tljis large discordance it se^mg necessary to re-
the Jupiter and Saturn perturbations tor the revnliition
9-1835 with the same rigour as the following revolution. We
fe as yet only made an ap|)roximate iuve>4tigation of these, uning
same abbreviations as we employed in the ancient revolutions,
^ refiult is decidedly in favour of the Kosenberger result us the
bre accurate ; in fact, it is on the opposite side of this from the
) Ponti^coulant result. We suspect that the canst; of the latter's
jpor is the manner in which he bas rectified the orbit in the
Brth quadraut; he baa made the eccentric anomaly proceed
kiiiterruptedly in the rectified orbit, which implies a want of
titiimity in the time.
|For example at u - 300K the time shifts abruptly froui 25376** to ^%2^'^
,. «=325« II ,1 It 267194 „ 26747**
i» « = 375«
^7563^ M 27545'*
27896** „ 27895^*
Id other words, portions of the Jupiter and Saturn perturbu-
are either omitted or reckoned twice ; this would have no
Ible eCTett on the dat^ of perihelion in 1835, but it would have
preciable effect on the mean motion at that eix>cb, and
juently on the date of perihelion in 1910,
ITe regard ilosenbergcr^s mean motion in 1835 aa presumably
the trnth^ but we do cot consider that it can be safely taken
Initive, since he only carried bis computations up to 296' of
ic anomaly, adopting Bamoiseau's results for the rest of the
Jiou; the shift can scarcely fail to have caused some breach
luity, in addition to which Damoiseau's dat^3 of perihelion
in J 835 was rii days too early, which implies appreciable
the Jupiter perturbations shortly before perihelion.
bnberger contemplated completing his computations as soon
ate of perihelion was known by observation, but we cannot
that he ever carried out his iiitention. Should anyone
Liter researches puhlisherl by him, we ahoidd be very
be supplied with the reference,
l»w collect our results in tabular form, with tho premise
ipiter and Saturn figures for the first revolution are not
live.
392
Messrs, CowM and Crommdin,
LXTIU.5,
Revolution 1 759-1835.
PUmet. Llmiteofu. dn. d^.
9 o- 30 (with def. integral) +'0077 + 215
330-360 „ „ -'0058 o
© o- 30 „ „ +-0262 + 731
330-360 „ „ +-0038 o
2t o- 90 + -0091 + 242
90-270 „ „ --2588 + 790
270-360 +'6870 - 108
fe o- 90 - -0072 - 176
90-270 „ „ +-0381 +2086
270-360 -'1150 + 23
9 0-360 +-0094 + 229
[^ 0-360 +0014 - 4
+ 4028
28006-37, the
Sums + '3959
Hence we have the equation ^^^^^-^^-'rl^^S;'^
nat 1759
observed period in days. Hence 71 1759 = 46"' 13 14
add 3959
7i 1835= 46-5273
The other determinations of 71 in 1835 are Rosenberger
46'''5o88, de Pontecoulant (latest value) 46"*4586, Damoiseau
46"*4994, Lehmann (evidently affected by some error) 46"*99i6.
Revolution, 183 5- 19 10.
FUnet
I.
.iinita of «.
dn.
dCT.
dC.
de.
9
o-''3o(
with ilof. int.)
- 0024
0
- 65
0
e
0- 30
M »»
+ •0114
0
+ 309
0
%
0-360
1' >»
+ •1465
+ 222
+ 31986
-•000097
h
0-360
II »»
+ •0084
- 52
21
-•000010
¥
0-360
+ '0105
- IS
+ 107
+ X)00004i
^^
0-360
- '0012
- 9
- 40
+ •0000043
Sums +'1732 +143 +32276 --000099
TT 1206000" - 32276" . J. 1
Hence — - - -- "^ — ' = period m days.
n at 1835
Using our provisional value of n 46''*5273
this gives 1910 Maich 29^*3 for next |)erilielion passage.
Using Rosenber^er's value of n 46" '5088
this gives 1910 April 8^*8 for next perihelion passage.
Using de Pont«M»oulant's value of n 46" '4586
t\i\>\ g>vft* \9\o Ma^' 7** 8 for next perihelion passage.
■
^H
e
^H
B. 1908. PeHurbaiioTis of Hallm/s Comet, 1759
-1910.
^1
VWe are inclined to take 19 xo
Ai.r. 8'<
D as the most probable ^^H
ifue, pending
the accurate re«ie termination of the
Jupiter and ^^|
liurn [iiertiirbationj* from 1759 to
i^lS-
^^H
I We have not yet examineil tlie
■ so we provigionally }i<io|>t de P
[»ertarbat
ions of the orbit
plane, ^^H
jntecoidant'ii valne
H of tlie node ^^H
id inclination
in 19:0 for the
L>uriJOse
[>f computing a search ^^^
^emeris.
,^^^H
■
T=:= 1 9 10 Apr. 8
•0
^^1
B
u7= III
32' )
^^H
■
^= 57
rjlO'O
^^H
^^^^^H
*= 162
13 )
^^^^
^^^^^B
e- 096729
^^H
^^^^^m
u = 46''*69
^^H
I^^^^P
Jog a= 1*2*
539
^^H
Emtftneous viiluc of period = 76*^
00
'
^^H
t
7 = 0*586 f>
^H
■ These give ]
rise to the equations for the <
actuator
^1
ft
it^r
9-9852
^in
(y+145'
'38')
^H
^^^^^L
y^r
9-9884
sin
('^+239
ti)
^^H
^^H
z = r
.9*5350
sin
(tj+iS8
55)
^1
^^
Smfxh Sphew^in /or EaiU^'*$
ComtU
H
Me.
Interval, R.A.
N. Dec.
logr.
log A.
^^^^1
il h m ■
^^^1
SOct 17
54-3 ^ ** *°
12 23
o'8i68
0-8154
31/ ■
Nov. as'o
50S ^ «s S«
u 31
07«S8
07217
313 I
)9 Jan. t4'S
468 5 38 52
II 49
07537
0'6Si7
315 ■
Mar, 2-6
43-4 S 7^'
13 10
07202
07047
317 1
Apr. is'o
400 5 10 0
14 52
0*6854
o73<7
^M
May 25^0
367 521 4
16 15
06489
07329
321 ^H
June 307
33-5 54.48
17 6
0*6 no
07045
323 ^W
Aug. 31
30s ^ »»°
17 29
0*5714
0*6472
325 I
Sept. 27
27-8 ^ '-» 5*
J7 31
03300
0*5629
327 I
Sept. 30-5
aso ^ '* 36
17 20
0-4868
o*4S53
329 I
Oct 25*5
M-5 5 58 M
17 2t
0-4416
0-3235
33' I
Nov. 17*0
«-2 5 » =*
17 4
0*3944
0*1885
333 ■
Difc- 7'2
.7-9 3 4a as
15 16
0-3452
0*0993
335 1
Dec. 25*1
2 t6 4
(1 46
0*2940
0-0987
^M
To these may be added the follo\niig :—
-
H
iS Jan. 3
h m a
6 28 10
10 i
^H
Feb. 2
6 ti 19
10 35
^^1
Mar. 3
601
n 23
^j
394
Messrs. CowM and Crommelin,
LXVIIL5,
These were computed for comparison with Dr. Wolfs object
BN ; as they show a distinctly different rate of acceleration, the
identity of the object with Halley's comet ^eems improbable.
From the beginning of 1910, Dr. Smart has kindly computed
an ephemeris at 4-day intervals. In view of the considerable un-
certainty in the date of perihelion, some abbreviations have been in-
troduced, the computed heliocentric co-ordinates of the comet in
1835 ^^i^g utilised.
It will be seen that the comet is an evening star till March 17,
and after May 11, being a morning star in the interim. The near
approach to the Earth on May 12 and the extremely rapid
geocentric motion at that time are noteworthy. It is also evideut
that at the time of greatest brightness, the conditions of observation
are much more favourable in the southern hemisphere than in the
northern. It may be worth while adding that the comet will
probably be near the Sun at the time of the total solar eclipse of
1910 May 8.
Qreenwich
Right
AMension.
DeelinaUon.
A
-i
Son*! Place.
Noon.
.A.
Dec
1910.
Jan. 2
h
I
ni 8
41 44
+ 9 30
'•33
I '00
h
18
m
49
-22
6
I
28 28
+ 8 54
1-37
I -00
19
6
-23
10
I
16 56
+ 8 17
1-42
I -00
19 24
-22
14
I
6 12
+ 7 46
1-46
i-oi
19 41
-21
18
0
57 12
+ 7 19
1-51
I '02
19
58
-21
22
0
49 0
+ 6 58
1*55
I -03
20
15
-20
26
0
41 40
+ 6 37
1-59
I -06
20
32
-19
30
0
35 16
4 6 22
1-64
I -09
20
49
-iS
Fob. 3
0
29 36
+ 6 9
1-68
1*13
21
5
-17
7
0
24 28
+ 6 I
172
ri8
21
21
-15
II
0
1948
+ 5 53
175
I 26
21
37
-14
15
0
1528
-1-5 46
177
1*35
21
53
-13
19
0
II 24
+ 5 41
179
1*47
22
8
-II
23
0
7 32
+ 5 37
I -81
I -61
22
24
-10
27
0
348
+ 5 34
1-82
r8o
22
39
• - 9
Mar. 3
0
0 0
+ 5 30
I -81
2-05
22
54
- 7
7
23
58 8
+ 5 26
I -80
2*37
23
9
- 6
II
52 24
H-5 22
I 79
274
23 23
- 4
15
48 20
+ 5 16
175
3-28
23
38
- 2
19
23 44 0
+ 5 8
171
396
23 53
- I
23
23 39 32
+ 458
1-65
4-83
0
7
+ I
27
34 A^
■V-^ AT
IS8
5*94
0
2a
+ 2
far. 1908. PerturbatioTis of HaUej/s Comet, 1759-1910. 395
PMnwiOa
Right
AacentioD.
DecUiULiioD.
A
Brightnen.
Son'! I
lace.
Nooo.
K.A.
Doo.
IQIOb
h m ■
• i
h m
•
Tar. 31
2330 8
+ 4 32
1-50
7-48
0 36
+ 4
pr. 4
2540
+4 14
140
8-95
051
+ 5
8
2321 24
+ 3 55
1-28
IO-86
I 6
+ 7
12
23 18 20
+ 3 35
lis
i3'o6
I 20
+ 8
16
16 0
+ 3 »6
1-02
l6'22
1 35
+ 10
20
15 24
+ 3 1
•87
19-50
1 50
+ 11
24
17 16
+ 2 46
•72
25*12
2 5
+ 13
2S
23 23 8
+ 237
•57
28-31
2 20
+ 14
by 2
23 35 44
+ 2 29
•41
5S-34
23s
+ 15
6
068
+ 237
•26
126-5
2 so
+ 16
10
2 2 40
+ 3 3
•08
1112*0
3 6
+ 17
14
7 21 40
+0 34
•10
6607
3 22
+ 18
18
9 9 44
-0 41
•25
94-19
3 37
+ 19
22
9 44 8
-I 9
•40
33*27
3 53
+ 20
26
9 59 48
-I 21
•55
15*49
4 9
+21
30
10 9 40
-I 29
70
8-59
426
+ 22
nnc 3
10 16 16
-I 37
•85
5-30
442
+ 22
7
10 21 4
-I 47
•99
3-51
458
+ 23
11
10 25 28
-I 56
1-15
2-42
5 15
+23
>5
10 29 4
-2 5
1-30
174
5 32
+ 23
19
10 32 48
-2 14
1-42
I '34
548
+ 23
23
10 35 36
-2 29
1-58
roo
6 5
+ 23
27
10 38 38
-2 41
171
79
6 22
+ 23
uly I
10 41 38
-2 53
1-85
•63
6 38
+ 23
5
10 44 32
-3 8
1-98
-52
655
+ 23
9
10 47 28
-3 23
2*IO
•42
7 II
+ 23
13
10 50 16
-3 3«
2*22
•35
7 27
+ 21
396 Measures of Southern Binary Stars in 1907. LxmL 5,
Measures of SotttJiem Binary Stars in 1907. By John Tebbutt.
I have pleasure in forwarding to the Society the results of a
series of measures which I liave made of the moat interesting
southern binary stars with the 8-inch equatorial, in the same
manner as described in my paper in Monthly Notices, vol. IxvL
On the evenings of August 23, 24, 25 and September 15, 16, I
attempted to measure the rapid binary Lacaille 7194, bat failed to
see the companion, although it was readily seen and measured
by me in 1902. See Monthly Notices for November 1903. The
non- visibility of the companion has been confirmed by observa^ons
subsequently made at my request at the Sydney Observatory.
Epoch.
Position
Aoglc.
Diitance.
No.ofB^
reningtfor
star.
PopiUon
Angle.
Diitance.
HO0
Angle
aCentauri
1907*410
213-8
20-67
6
6
E.
3416
•567
274-2
2-09
5
5
E.
7 Corona Aust.
•617
117-3
1-83
4
4
E.
7t 5014
•652
...
x-54
...
I
E.
)i
•660
240-3
...
3
...
E.
7 Centauri
•673
353-2
1-42
5
2
W.
fi M118C8B
•673
346-1
1-28
5
2
W.
T Lupi
704
84s
1-42
7
3
W.
/iLupi
737
153*3
1-83
6
3
W.
7 Oircini
•737
70-2
1-46
5
3
W.
d Luj)i
•812
I "4
...
2
...
W.
3 Phojiiicis
•875
12*2
1*55
5
3
E.
p Eridani
•907
216-6
S-23
3
4
E.
Laoaille 2145
•964
45-2
1-89
4
4
E.
The Observatory,
The Peninsula, Windsor, N.S. Wales:
1908 January 23.
Mar, 1908* Prof. Turner^ Star Images, etc.
397
On the relative numhera of Star Imager pktitoffraphed in different
pariti of the Plaits for tht Oxford poriioji of the Astrographte
Catalogue, Second Papei\ By H. H. Tamer, D.8c„ F.R.S,,
Saviliftn Professor.
H
I. Ill Monthly Notices, Ixii. p» 434, a prelirainary discuesioti was
iven of the counts of star images in ditiBreut parts of pktes taken
ft the Affirographic dUaiogue; and it was shown that, the star
density was greatest at a certain distance (r^) from the centre of
ibe plate and fell off rapidly outside this distance ; the vulue of r^
fordifFertjnt object-glaases being dttferent, — ejj, for Oxford rj^ = ^^\
for Paris r^^ 58', for Algiers ?•„ = 49', for Tonluuse r^^= 30'.
The natural inference is that the value of r^^ depends on the
position of the plate, increasing as the i>late is pushed further
within the focus.
Similar results were found for the Potsdam telesco|ie, with
T^= 2B' (Adron. Nachi'ichhM, No. 3S17); and for the Greenwich
telescope with 7*^ = 318' i^Gretmcich AstrograpMc Caiahgu^, vol. i,
pp. Ti and Yii), On the other hand, the late M. Loewy has
questioned the reality of the phenomenon in his annual report of
the Paris Observatory for 1905, in the following terms: —
"D*autres experiences ont eu pour objet de determiner jiiaqu*ifc
quel point une me me carte pourait etre conaid^ree comnit^ homog^ne
an point de vue des grandeurs* On sail que M- H. H. Turner a
^t^ coOiluit a penser qtie cette homogeneity laiasait a desirer, en
faisant^ pour uo grand nombr<^ d'epreuves publi<Se8, le relev^ des
nombres d'^trdles qui tombent dans les divers carr^s du rdseau.
Pour controler ce ri^^sultat par une antre voie, on a photographic un
groupe dV'toiles avec des poses, dt^croiasantes et de legera d^ place-
meats syst^^matiques, afin d'obtenir des images facilea k identifier,
et eu metue temps h la limite de visibilite. On a ensuite r«ipi^te
Topi^ration en imprimant tk la lunette d'antres d ^placements
syst^matiques de mani^re a donner le m^me temps de pose aux
m^mea e toiler da us di verses parties do la plaque. On a pu ainsi
ooDStater que la visilalit*.' des images relatives aux astrea les plus
faibles eat la meme dans toutes les regions du chump. Le defaut
signaU par M, Turner, et qni a pu se produire k la suite d^une mise
an foyer dofectueuse, ne semble done pas tr^s redoutable dans lea
circonstances actnelle^" (p, 10).
One possible interpretation of the discrepancy between
M, Loewy *8 conclusion and those above quoted ia that bis test was
not so delicate a one as the numerical test elsewhere applied. The
results obtained by counting star images are consistent and definite,
and clearly afford a satisfactory measure of aumething. The fact
that other methods fail to detect that something may therefore
only enhance the value of the method which reveala it: there are
almost certain to be uses to which a new tet^i can be applied, e^^tv
though they may not be foreseen at the moment, TV^ <;\\uiTA^^»^
2»
^^^B 398 Prof. Turrier, Star Ifna^ photographed LXrUL 5,
^^^^H measured lias reference to the fucal length of ihe instrument, aod
^^^H thereforu to the scale of the photograph ; and it b at any rate of
^^^H interest to Hee how far mch measures throw light oti variations of
^^^^1 focal length with time or with temperature ; or on the iaclinatioB
^^^^1 of the plate to the axis of thtr telescope (which may be regarded si
^^^H variation in focal length for different parts of the plate).
^^^H 2, Three volumes of the Oxford Astrographic Catalogue have now
^^^^ been published^ coiitaiuin;^' measures of 3 x 160 = 4^0 plates, with
^H centres ill zones +31*, 4-30", + tg*. Generous volunteer assistaiiCA
A
io
:»6
SO
8a
I9T
170
m6
990
:?98
36*
J7«»
>86
4to
44a
4SO
4«o
530
S38
6^
^.4
1
#
•
10
18
34
ss
90
130
178
334
36
34
50
74
Z06
146
170
194
3l8
350
314
554
?78
f74 ,
50
58
74
98
130
"74.
338
e«
V
to6
130
170
t63
»03
24*
»90
306
346
370
4fO
4*«
48»
530
586
53a
610
706
1Z2
I JO
.46
aoa
56*
650
74«S
«7t>
178
»Q4
374
350
?90
338
394'
4S8
610
666
69i
754
794
^^
«34
aSQ
306
««
394
45©
S*4
9QO
*9S
3*4
338
3f<»
4 J©
45a
57fi
6so
7M
730
..
914
9Sfc
to06
»S4
36*
370 3fi6
410
44a
4««i
53a
i%6
650
8o«
890
970
449
530
450
538
466
490
5"
56fl
61 D
666
730
Bos
890
BSa
S54
578
610
650
698
754
81S
970
«O50
6]ke
634
6sc
«74
706
746
m
850
9M
q86
11366
1154
Fk:. I,
rom Miss Riddle has enabled us to count the measures made on thea
latea on a systematic plan arranged so as to exhibit such variation
d focal length. It seemed desirable to discuss these measured ti
rder to decide whether to extend the work to the other iom
olumes as they appear; Rnd to give a brief summary of tJn
iscussion, in order to enable our colleagues to judge of U»<
xpediency of undertaking similar work elsewhere.
3, Each |ilate was divided into four quarters, which will bi
fcnoted by XY, ;cY, Xy^ xy. The capita! letters refer to Uigi
alues of X or y, — i.e. '^a.W^ exceeding 13^000; the small I^tt^
!
i
1
r
»
i
t
Mur. 1908. for Oxford portion of Adrographic CoUalogue. 399
to values less than i3'ooo. Ad atternative d«sigD&tibii would thus
be
Each quarter was then divided up into ten regions, the average
distances of which from the plate centre were in the ratios 1, 2,
3 . . . . 10, approximately, thw bouodariea of the regions following
the reaeau lines. The dividing lin«is for one of the quartern are
shown in fig. i, A repfesentu the plate centre aod D the corner of
the reaeau. Representing a side of the reseau by 2^ tht^ middle
fK)iQts of the reseau squares along A B will be at distances i, 3,
5 .... 25, It is readily seen that on this scale Ibe numbers
written in the squares represent r'^ = x^-^y^j where x aod y are the
co-ordinates of the centre of the ai^iiare referred to A as origin.
Now if we take ten regions at distances t^ 2t^ ^t . . , . 10^ from A
as centre, the value for the outermost will be looi* ; and a glance
at fig, I shows that we must put approximately 100^^=1100, or
t^ = about 1 1 .
Table I.
UUcrfor
No, of
Avfstage
Vulueofrtf.
t^.
rln
Sesgloii.
HqUAres,
MlutttDa of Arc.
a
3
71
7*3
7
h
5
28
7*0
13
e
14
76
8-4
22
d
fS
150
9'4
31
«
«3
248
9*9
39
/
23
363
lo-i
48
9
34
508
10*4
56
h
29
673
105
6S
i
IS
864
107
73
k
8
1090
io*9
82
The thick lines were drawn with this value of i^ in mind. The
4th and 5th columns of Table I. show that the grouping miglit have
been better, but this was not noticed until so much work had been
done that it seemed better to keep the system unaltered. It is not
DiB^ntial to have tbe distances in exact arithmetical progre-ssion.
4, The counts were then tretited a.s shown in the foil u wing
example : —
Table 11.
Total counts in th« regions f&r Phtic3 2034-2057, 2<me -i-ji\
Fa square* = 3
5
14
vs
23
23
34
29
15
8
169
Rf^ifion^a.
6.
e.
d.
e.
/
9>
h.
t.
it.
Total.
XY 25
30
lot
>37
222
276
372
297
132
64
1656
.rY 22
42
124
136
266
228
332
247
97
36
1530
Xy 2t
38
106
i"3
226
205
340
3»2
112
62
1535
jcy 22
38
89
120
193
208
3^5
236
89
35
*345
90 14S 420 506 907 917 1359 1092 430 V91 UJbki
400
Prof, Turner, Star Images photographed lxviil 5.
The tiuinbor of squares in a region varies conaidermbly, a^ sbowa
in the top line. The next procedure h to divide by this number^
so BE to get tbe average .star density in each region. Then to
reduce thia density to a uniform scale for dilTerent batches of plates^
the quotients are a^ain ilivrdi^d by 6066/4, the avemce toial
number of stars on a single cjuaTter-plate. The intermediate revolts
need not be given here; in Table III. are shown the final valttii
obtained for star density in the different regions.
%
Table
IIL
1
Star
Density ott a uni/arm wcaU tUducfd frmn
TahU II.
A.
b.
r.
d.
#.
/.
9*
h.
1.
t.
ToUl,
XY
55
40
4S
61
64
79
72
6S
58
53
59S
o^Y
48
56
59
60
77
65
65
56
43
3<5
559
X|^
46
50
SO
50
65
59
66
72
50
52
S6o
^
48
SO
42
53
56
60
61
54
39
^9
492
Mean
49
49 50 56 65 66 66 63
47
5. Now the characteristic feature <»! the variation in density i
the gradui*! rise up tn about / uud r; and the fall afterwarii
The maximum represeul^ the position of best focus, and it
important to note any vaviution-s in thiw position. For this purpt,
it is convenient to liavo a yingln number nf eiome kind rather ;ha
a system of 10, and the indicator adopted for a prelimii
investigation is
A = (c + tf -f e) - (j^ + /H- 1).
It will be seen that an increase in A means that the maximo
corner nearer a, — i,e. nearer the plate centre, — and presumably thil
the plate is further from the object-glass: a decrease in A correspund
to the [A\Ui being pushed in tiearer the O.G.
To get an idea of the pl»y*^ical meaning of A, let us take th»
theoretical formula for star density on a plate given in Mon, Nc/i
Ixii. p, 441, viz. —
Density = <i { i ^^^€{1^ - r*^) }
where r is the distance of the point on the plate from th« pla
centre ; r^ is the distance of the maximum from the centre \
c= io~* if r and r^ are expressed m minutes of arc. We on[
put T^ successively equal to the selected distances in Table Lj
and take a^66^ which i^ the mean maximum, on the systed
adopted in Table III. ; and we then get the densities aa in
Table IV.
Mar. 1908. f<yr Oxford poHym of AUrogra^hic Caialogns, 401
Table IV»
mnd eorrmpanding valuta of A mnd n.
ro-
a.
A.
e.
tL
t.
A
y.
A.
i\
Ar.
-i*
n.
r
66
65
63
60
56
51
45
38
31
22
-^6s
8039
<3
^5
66
64
61
57
52
46
39
32
23
+ 65
8202
22
63
64
66
63
59
54
48
41
34
25
+ 65
8508
31
60
61
63
66
62
57
51
44
37
28
+ 59
8883
39
56
57
59
62
66
61
55
48
41
32
+ 43
9263
48
51
52
54
57
61
66
60
53
46
37
+ 13
9508
56
45
46
48
51
55
60
66
59
52
43
-23
9526
65
38
39
41
44
48
53
59
66
59
50
-51
9071
73
31
3^
34
37
4'
46
52
59
66
57
-65
S2IO
83
23
n
25
28
32
37
43
50
57
66
-6s
6833
Ko. of 1
ttjumret J
14 15 23 23 34 29 fs
8
6, The vaUiefl of A are shown 111 the last colunui but one of
Table IV, Wlieti ?'^ ia smM or large, — Le. wUeu the best focus is
Tcry near the centre or the corner of the plate^ — A is constant,
because the distances represented hy e d * . * , i are all on one
ode of the maximum, and hence A = (c + 1^ + (?) - (j? + /i + 1") does not
cliange. Bat such cases do not occur in practice, the plate being
always focussed for some distance from tiie centre, and then A is
a convenient index to the [*osition of beat focus. In the last
column is given, «, the totul number of stars on the (|uarter-plate,
obtained by assuming tht^ density constant over each of the ri^gions
a, 6 .... A^ ; so that the number of stiirs in each region is the
product of the density by the number of squares in the region as
shown in the last line of the table. The values of n so found
imply the further assumption that the maximum density is the same
(viz. 66 per square) whatever be the position of the plate. This
ftflsumpiion is no doubt incorrect, but it may not he far from the
Iratb. The optical image of a star in focus near the axis of the
lens is almost certainly smaller than the best focussed image of a
atar near the edge of the field. Hence, if the number of stars
photographed depended on the size of best image alone, the
maximum density would fall off as we left the centre of the field,
and might fall off even ra]>idly, But other factors influence the
photographic star image — atmospheric tremor, errors of driving and
guiding, etc. — which are indei>endf?nt of the distance from the centre
of the field, and the maximum density may not diminish so rapidly
as might at first appear. It seems worth while to examine the
eonaequences of assuming it to be constant, at any rate in the hrst
instance. But we shall return to this point later. Our first busineBa
ia with the position of the maximum, as indicated by the quantity A.
7. We proceed to tabulate the values of A fot t\i& ioui: t^uM"^-?^,,
402
Frof, TwnvtT^ Star Imcbges photographed LXTIIL 5,
arranging all the plates of vols. I, ii., iii. of the Oxford Catalogue
in groups, an siiflSciently indicated by colnmns i, 2, 3, 4 in TMt
y. The detailed grouping was determined by considerations
which need not concern us here ; nor need we, in a preliminary
survey, pay much attention to the fact that one or two of the
individual groups are small either in number of plates or number
of stars.
Table V.
Mean Values
of A for Plat^
in vols.
i., ii.,
iii. of the Oxford
Astro^aphic CateUogue.
TnnA
Limiting
Not.
No. of
Plates.
No. of
SUrt.
Values of A.
Whole.
£ione.
xyT"
xY,
Xy.
«if.
29-
525- 542
16
8099
+ 48
+ 37
+ 42
+ 59
+ 46
29
700- 855
14
8589
+ 27
+ 34
+ 10
+28
+ 25
30
896- 921
15
4293
+ 25
+ 42
+ 51
+ 17
+ 34
29
937-1023
32
7300
+ 51
+ 49
+ 52
+ 15
+42
29
I 236-1486
ds and Means
18
7913
+ 52
+ 12
+ 23
+ 37
+ 31
Totf
95
36194
+ 41
+ 35
+ 36
+ 31
+36
30
I 564-1 585
II
12593
-28
- 5
-44
+ 15
-16
30
I 586- I 597
12
5933
-49
- 4
-34
+ 30
-14
31
1 598-1606
lis and Means
8
4877
-76
+ 7
-81
+ 3
-37
Toti
31
20
23403
6706
-51
- I
- I
+ 51
:53
-20
+ 16
+ 34
-22
29
1747-1843
+ 16
31
I 834- I 849
7
6245
-37
+ 3
-38
-21
-23
29
1850-1900
26
8860
4- 2
+ 37
-30
+ 34
+ 11
30
1865-1915
14
8178
- 6
+ 38
-30
+ 27
+ 7
30
1916-1943
ds and Means
26
93
5989
- I
+ 48
-22
+ 38
+ 16
Tou
35978
- 9
+ 35
-28
+ 22
+ 5
30
1946-2060
26
11217
-30
+ 32
-56
+ 8
-11
31
1973-1996
11
4006
-22
+ 30
-59
- II
-16
31
1997-2032
26
19984
-29
+ 37
-64
+ I
-14
31
2034-2057
24
6066
-25
+ 32
J2±3
- 3
~ 5
Totals and Means
^7 ~
41273
-27
+ 33
-50
- I
+ 42
-II
30
2061-2 1 01
26
7797
+ I
+ 12
-30
+ 6
31
2087-2155
15
4513
-39
+ 46
- 9
+ 34
+ 8
30
2102-21 1 1
10
2693
0
+ 29
-27
+ 17
+ 5
30
2 1 36-2 1 96
16
6726
-13
+ 25
-47
+ 26
- 2
31
2202-2234
15
4445
-14
+ 24
- I
+ 40
+ 12
30
2217-2482
4
1163
+ 12
-16
-28
+ 56
+ 6
31
2235-2271
26
6095
- 5
+ 47
-22
+ 29
+ 12
31
2274-2299
12
4871
-33
- 6
-41
+ 25
-14
Tot€
lis and Means
23 "-2349
124
18
38303
- II
+ 20
-26
+ 34
+ 4
31
4596
-f 2
+ 21
- 5
+ 43
+ 15
29
2450-2500
30
11874
-23
+ 25
-22
+ 23
+ I
Mar. 1908. for Or/ord portion of Asirographic CcUalogue. 405
8, The reasons for separation at the places indicated by the
boTizontal liDes are as fivUowa : —
(a) Between plate 1557 and 1558 (summer of 1900) the new
dome was erected. The objeut-giass was dismounted
and the eye end also.
(6) After plate 1606, the instrument was devoted to the Eroa
work. The eye end was taken off to study possible
in»tTumental adaptations.
(c) After plate 1 943 the O.G. was dismounted for cleaning.
(d) Some change seems to have taken place between 2057—
2061, or near this date, though nothing is recorded in
explanation.
(e) At plate 2300 the eye end was dismounted to study adapta-
tion to photographs of the Moon among the stars.
{/) After plate 2349 the O.G. waa dismounted and taken to
Egvpt for the eclipse of 1905,
There waa apparently a slight change of focal length at each of
these epochs, due to accidental causes. It is curious that, on the
whole, the vahie of A should show an increase from the second
group onwards, for this corresponds to the plate being further from
the O.G., and not nearer to it, as miglit have been explained by
the gradual wearing of the studs against winch it is pressed. No
change was made de!il>erately in the adjustment ot these until
after all the plates had been taken*
9. It is a reasonable a-Hsumption that un each occasion the focal
length was changed without disturbing the relation ship of the
quarters to each other. Hence we may subtract the value of A
for the whole plate (given in the kst column) from each quarter.
It will be sufficient here to give the means of groups.
Table VI.
Valtus of A /or each qnarUr relatim to mmn A /or PlaU,
linjltlnis Not. Wdght. XY, «Y. Xy. xp.
L 525-1486 S + S - I o - 5
IL
1564-1606
-29
+21
-31
+ 38
III.
1747-1943
-14
+30
-33
+ 17
IV.
1946-2057
-16
+44
-39
+ 10
V,
2061-2299
-^5
+ 16
-30
+ 30
VI.
2311-2349
-13
+ 6
-20
+ 28
eiL
245D-2500
2
-24
+ 24
-23
+ 22
There is a decided chan^^'e after the first group. In the firat group
the quarters XY and Xy are slightly positive, corresponding to the
X side of the plate (large R.A.s) being a little further from the
O.G. than Ihe x aide. In all the later groups the ibv^t%^ \?i \>i^
404 Prof. Tv/mer, Star Images pJiotographed LZym. 5,
case, and the relationship remains fairly constant. It is tine
there seems to be a slight diminution in xY and an increase in
X^; but the appearance is chiefly due to the last two groups, which
have small weight
ID. The changes in general focal length seem more striking
than any relative change. But it is possible to take another view
of these changes. Are they possibly seasonal! No deliberate
change in focus was made at any of the epochs above mentioned,
and at one of them no interference with the instrument is recorded.
1 1. Let us try the extreme assumption that they are all due to
temperature or other seasonal change. In the third column of
Table VII. is given the month in which the minority of the plates
in the group were taken. Arranging the groups according to these
months we have —
May. Jane. July. Aug. Sept. Oct. Kor. Dec
+ 12 -II +1 -16 -14 - 5
-16 -14-37 +11 +»5
-14 -23
There certainly seems to be something to be said for a seasonal
effect. The values of A from December to May are all positive
with one slight exception, and from June to November all negative.
If we express the effect as a simple harmonic term, with a constant
added, we should have figures something like those given below :—
Jan.
Feb.
Mar. Apr.
+ 6
+ 7
-2 +16
+ 8
+ 16
+ 5
+ 12
+ 6
Jan.
Feb.
Mar.
Apr.
May. June.
July.
Aug.
Sept.
Oct.
Not. D«c.
+ 4
+ 10
+ 12
+ 10
+ 4 -4
- 12
-18
-20
-18
-12 -4
Applying these as corrections with reversed sign to the individual
groups, we get the results of Table VII.
Table VII.
Possible seasonal change in A.
Uncorrected A. Month. Correction. Corrected A.
1564-1585 -16 Aug. +18 +2
1586-1597 -14 Sept. +20 + 6
1598-1606 -37 Sept. +20 -17
Mean -22 ... +19 - 3
1747-1843 +16 Apr. -10 +6
1834-1849 -23 Sept. +20 - 3
1850-1900 +11 Nov. +12 +23
1865-1915 + 7 Feb. - 10 - 3
1916-1943 +16 Apr. -10 +6
+5 +1 +6
Ma r. 1 908. for Oxford portion of Astrographic Catalogue. 405
Tablb Vlh^-^amLimt^
Possible stasmtuf ch^inye in A,
Uncorrected A. \JoDth, Correotlon. Corrected A,
15^6-2060 -II June +4 - 7
*973-»996 *t6 June +4 -12
1997-2052 -14 Aug. +18 +4
2034-2057 - 5 Not. +ia +7
-11
...
+ 10
' 2
206I-JIOI
+ e
Sm.
- 4
+ 2
2087-2155
-^ 8
Feb,
-10
- 2
3I02-2III
+ 5
Feb.
-10
- 5
2 1 36-2 196
- 2
Mar.
- 12
-14
2202-2334
+ 12
A(.n
- 10
+ 2
2217-2482
+ 6
Apr.
- ID
- 4
2235-2271
+ 12
May
- 4
+ 8
2274-2299
-14
J una
+ 4
*io
+ 4
...
- 7
- 3
2311-2349
2450-2500
+ 15
Dec.
July
+ 4
^12
+ 19
+ 13
1^
The figures can thus be explained either by a aeasonal change in.
focal length, or by a series of discontinrnties at tlie times when
either eye end or O.G. were dismounted.
Against the latter explanation there is the fact that no discon-
nuit'y was recorded about plate No. 2057, an that the seasonal
effect is somewhat more probable.
The first set of plates (Noa. 525-1486) throws no light on the
matter, for the must divergent groups in the last column of
Table IV* are the first two, which were both taken chiefly in
September, so that we must set down their diflFerence to accident.
Summarising the results so far, we find—
(a) That the focal position of the plate was essentially difiFerent
in the two periods before and after the erection of the new dome
in 1900.
(fi) In the first peririd the plate was further from the object-
glass (A = 4- ^6 for tlie mean of the four quarters), and satis-
factoriiy nonaa! to the line of coUimation (values of A nearly same
in alt quarters).
(y) In the second period the plate was nearer the O.G. (A ^ 0
or less), and the X side (large R.A.'s) much nearer than the x side
(small R,A,*s). The values of A for the two aides are about
A— - 25 and A^ -h 25 respectively.
Moreover, there are variations in the focal length which may
be seasonal, ranging from A= - 20 in Juue-Seylftm\>ft\ i^^Y^^^
4o6 Prof. Turner, Star Imagei photographed LZvnL 5,
nearer O.G.) to A= -f 12 in Deoember-April (plate farther from
O.G.), though these variations may he due to a series of dis-
continuities.
The result that the plate is further from the 0.0. in cold
weather and nearer in warm seems a little strange. The telescope
tuhe is no douht longer in the warm weather ; hut we are con-
cerned with a differential effect, depending partly on the ezpansion
of the tuhe and partly on that of the lenses^ which may alter their
focal length more than the tuhe alters, and so give an apparently
reversed effect. For this reason we cannot look for confirmation
(or otherwise) to the observed scale-value of the plate deduced
from measures of star images ; for this scale value depends on the
expansion of tube and plate, perhaps also on that of the reseau.
12. Let us now examine the effect of these differences on the
relative number of stars photographed in the different quarter-
plates. We find that we have in plates 1564-2500 a mass of
tolerably homogeneous material with one chief variable, the mean
value of A for the whole plate, which probably corresponds to
the mean distance of the plate from the O.G. Whether the
variations in A are due to a seasonal effect or to accidental dis-
continuities need not concern us if we take A itself as the in-
dependent variable.
Table VIII.
Total numhrr
of Stars
counted on
eadi Quarter- Plaie.
Mean A.
Plate Nos.
Zone.
XY.
xY.
Xy.
ay-
-37
1598-1606
31-
1320
1208
1269
1080
-23
1834-1849
31
1528
1571
1582
1564
-16
1564-15S5
30
3175
3332
3161
2925
-16
1973-1996
3»
1022
965_
1070
949
7045
7076
7082
6518
-14
1 586- 1 597
30
1582
1540
1462
1349
-14
1997-2032
31
5201
S075
5000
4708
-14
2274-2299
31
1289
1 187
1266
1129
-II
1946-2060
30
2951
2743
2901
2622
- 5
2034-2057
31
1656
1530
1535
1345
- 2
2 I 36-2 I 96
30
1820
1525
1813
1568
+ I
2450-2500
2061-2101
29
30
3247
301 1
2874
^^J742
17746
16611
16851
15463
+ 6
1972
1891
2019
i9»5
+ 5
2102-21 II
30
752
653
675
613
+ 6
2217-2482
30
314
293
298
258
+ 11
1850-1900
29
2308
2190
2250
210S
+ 7
1865-1915
30
2290
2023
2101
1764
+ 8
2087-2155
31
1193
1 174
1 130
1006
8829
8224
8473
7664
Har. 1908. for Oxford portiofi of Adrograpliic Caialogv^, 407
+ 12
I +16
TABts Wlh—conlinued,
Totnl number of Starx eountcfl tm mch Qitarier-Platr.
Flnto Kua,
Zone,
XV.
xY.
^tf-
^'
2235-2271
31''
1560
1494
1598
1443
2202-2234
31
1185
1103
1 147
lOlO
1747-1843
29
1679
1630
»755
1642
23"-3i49
31
11^
1194
1099
tuS
1916-1943
30
1647
1449
1527
1366
7259
6870
7126
6576
Reducing tbe 11 mn hers to pt^rceutages we ^nd for the means of
groups —
r i
^^^ +14
XY.
ior6
fo6'4
io6'4
104 '3
Table IX.
xV.
102 'I
997
99 •*
987
102 '2
ioi*r
102*O
102 '4
941
92*8
92 '3
94'5
Mt^ati
1047
99*9
101 '9
93*4
13, We brtve now to correct tlieae numbers for the changes
ID A. Tiiblo IV. f(ives in the last two coUimns the valoes of n
(the whole number of ?itars on a quart er-|)late) for different values
of A on certain asaumptioua specified in g 6« We may make a
EM table of the pertievtage correction to n as follows : —
A=+ 60+ 50+ 40+ 30-h 20+ 10 o- 10- 20- 30- 40- 50- 60
1 = 4.7'5-^4-3-f 2*s^^i-7 + o'94-o'34-o't o-o + o-i + 1*0 + 2*5 + 4^5 + 97
^ow the mean values of A for the groups of Table IX. and for
quarter-pkte, and the consequent corrections to percentage,
d be as follows i —
k
Taulk X.
Group
(T»li|e rx) -jy-
L ~4i
'II. ' 27
TIL - 5
IV. ' 4
Mean Value of A.
CorrcetSoM tt> Pert-«ntiiiee,
+ 9
+ 20
+ 24
+ 38
Xy. jy/ XV. xY. Xy,
-55 - 4 +27 +0'2 +7*1
-41 +13 4-07 +0*9 H 27
-26 +34 o'o +r2 +o'5
-14 +36 o'o +27 oo
Afean.
O'O +2*5
+ 0*4 +f2
+ 2*1 +09
+ 2-4 +1-3
^K Subtractinpr the mean si] own in the last column from the
Hkparate corrections for each quarter-plate (so a^ to keep the mean
for the whole-plate zero), the numbers of Table IX, corrected would
be as iu Table XL
408
Prof. Turner^ Star Images photot/raphed Lxvra. 5,
Taulk XI.
TM€ IX, eiorrecitd h uni/omt. A= * lo.
XY.
arY.
Xf.
<r. H
101*8
99-8
106-8
91-6 ^
105-9
99'4
1 02 '6
920
io5"5
99'4
]or6
93*5
102*9
loo-i
101*3
95*S
Mean
104*0
997
103*1
93*2
14. It is clear that we have liot removed the chief part of thr
differences shown in Table IX. by this process, aod we must look
to other cauaea for them. One auch cause is undoubtedly tUt of
the plate, of which no account has yet been taken in dealing '
tlie number of stars as distinct from the position of best focus.
That the tilt seriLiusly affects the number of stars can be seen froin
elementary geometrical considerations. Let KAOB (fig 2) r»_
present a section of the curved field and DABC a positioQ]
the plate normal tu the axi«,
Kow if the plate be tilted to the poBition S a B y, it is clear that
every portion of the half QC or Ry is brought clo^r to the carve
of good focus, and this aide of tlie pkte will thus contain more
stars all over. On the other aide, regarding the plate as fiisl
moved pamlJel to itself to cut the curve at a, and then tilted^ we
have in what precedes taken account of the movement of transla-
tion, but not of the tilt ; and the tilt clearly moves every part of
this other half- plate /wr//rer from the curve of good focus, so that
we lose stars all over iU The effect of tiit is thus greater than
that of translation, because by moving the plate parallel to itself
we gain in one part and lose in another, whereas by tilt we either
gain or lose all over the half-plate. We must qualify this state-
ment a little when we extend the argument to two dimensions, so
as to deal with a curved surface instead of the curved arc shown
in the figure. But the general nature of the phenomenon remains;
and we see that when a plate is til ted ^ the side nearer the 0,G.
gains at the expense of the side more remote,
15. We thus see how parts of the large differences of
Tables IX. and XI. probably arise. The quarter- plates XY mi
X|/, which have A negative^ are nearer the O.G, and gain atus
Mar, 1 908. for Oxford portion of Astrographic Catalogiie. 409
from their opposites xt/ aiid j'Y. But it is not ueiiessary to
proceed to a quaatitative estimation to see that we cannot in
thiA way explain t)ie whole of the differences. There must be
some other coDtributiii|;j cause which makes the Y quail rants
4 per cent, richer in stars than the y quadrants. The difference
between the mean A for iha Y quadrants and the y quadrants is
so slight that tilt cannot explain this considerahle excess; and,
while raserving the study of tilt for a future paper, we may
proceed here briefly to consider the possible causes of an excesa of
stars in the north half of a plate which cannot he explained (bo
far as can be seen at present) by the position of the plate,
16, The excess of stars in the N half of the plate may be due
to any combination of the following; causes : —
E(a) Optical performance of the O.G., including possible inclina-
tion to the line of coliiniation,
()3) Increased atmo.spherie absorption for S stars.
(y) Actual increase in number of stars as we ^o northwards.
When we combine all the plates in a zone, we eliminate
(to a large extent) variations of uniformity in R,A.,
but a change with declination may be persistent.
17, It is possible to estimate the approximate magnitude of
cause (/J). The formula for utniospheric almorption at Oxford of
visual rays is givpii in Mem, R.A.S.^ vol. xlvii., as o'l^ sec. Z,D.
We may put Z.D. = 25"*; and the variation of sec. Z,D. for i\
which is the di.^tancc between N and S hidves of the plate, is
about 0*01. The correction is thus about '0025 magnitude. Now
Newcomb gives {in hi a book, Thf^ Star^ : a Studtf of the Univerm^
p, 283) the number of stars of different magnitudes as in the
second column of Table XII., whence we get the totals of that
Eaagnitude and brighter as in the third cokirnn, from which we
Tadle XII.
Mif.
No, of Stan.
ToU!=N.
log N.
BIIT
6-5
2
2
0*30
^30
7-0
7*5
S-o
8-5
2
4
II
«5
4
8
19
34
0-60
O'go
1-28
i'53
25
•27
9*0
29
63
rSo
•18
9*5
33
96
r^98
'I5
10*0
39
135
2-13
*I7
lo's
64
199
2'30
*20
ii-o
115
314
2-50
form log N and its differences a^ in the 4th and 5th oolumjaa.
It appears that at magnitude r r, log N is iucTeamtig at \Xic^ t^\j&
4IO
Prof, Turner^ Star Images pliotagrapJied liyul 5,
of about *4 per magnitude, so that the iucreas© in log N for
'0025 majEf. would be about '00 1, This would iocreaa© 100 stttra
to ioo'23 (since loj^ 100*23=1*001), ao that a difference of
atmospheric jibsorptioti indicated hj viBual observationa would only
make a difference of ca^ per cent between the upper and lower
halves of a plate. Photographic absorption would need to be
twenty times as large to explain the observed diifere nee, which is
not likely. Sir W. Abney emphasises (Mon. Not, xlvii. p, 265) th*
necessity for knowing the *' spectrum value " of the plates employed
if we wish to determine the photographed absorption* but the
limits between which it varies are not likely to be wider than from
one to four times the visual absorption.
1 8. It occurred to me that we might get some indication of the
photographic absorption by compariog in some way the pUtei
taken at different hour-angles ; for instance, in the formula given
at the heading of each of our plates for determininf^ magniUHk
from measures of diameters,
mag. =a-b Jd,
the constant a would vary with the atmospheric absorption. But
a little examination showed that the differences of Z,D, between
plates Uken otherwise under the same conditions were too small W
afford a trustworthy indication of the phenomenon, which is
swanifrtid by a number 0! other larger variations. A single example
will serve to show this. In Table XIIL are shown in the fiwt
three cohirans the DecL and R.A. of the plate centre and the ho/af'
angle at the middle of the exposure ; io the fourth column ia
given the Z.D, of the centre ; and in the fifth the value of the
constant a of the alx>ve formula. If these values of a are arran^'^d
according to Z,I>, we find —
Mean Z.D.
Mean n
7
55-4
16 '43
6
41-0
1678
•I
i.e, the paradoxical result that fainter magnitudes (by 0*3^
magnitude) are shown on the plates of 6* greater Z,Jy. Suspicion
arose that the person who measured the plate might influence the
result ; and on collecting the results for the three measurers shown
in the sixth column, it was found that their mean values of a wuie
BO.
i6*84a
EG.
16-40^
16-50,
Mar. 1 908. for Oxford portion of Asiroffraphic Caialogtm.
Table XII L
Pkliu Udten, tni Ut€
ntj/^ of
1903 Mobcr 30,
DmI.
JLA.
HA.
Z.D.
a.
Measurer.
Corm.
^31'
331
r39E
28"
l6-2
EG
+ •2
,,
5*55
3'4i ,.
45
16'S
£G
+ •2
II
6*4
3-30 »
43
177
BG
-•2
_••
613
3*13. »
41
170
BG
-•a
1'
632
3' 3»»
39
m
BG
-•a
P..
6-58
3-10,.
40
16-3
S
■f- 1
U"
7' 7
3' 0.*
39
i6'9
S
+ •1
1
7*^5
^*57 -
3S
t6'6
KG
+ •2
r.
7 '34
^4' n
36
t6-8
BG
-•2
L*^
S* I
2*49 ».
37
16'4
BO
-'a
1
S28
^'SS M
38
i6-2
£0
+ *a
r
>i
8*46
2*39*1
36
16-3
S
+ 'i
II
S'SS
231 II
3S
X65
EG
+ *a
it on applying corrections hs in the luat column the i6"43 only
fiine 16*50 and the 16*78 became 1675, bo thut the anomaly
not remnved. It seems better to <ietermine tlie photographic
sl)Sorption by special obst^rvations rather than to seek it in the
%te& already taken, in which its effect was conacioUHly or ud-
DDscionsly minimised.
1 9, We may now turn to cause (y), the diatribution of stars in
the sky. That the density increases as we go northwards in the
Oxford zones is shown, for instance, in Argelander's Dutch-
mu^ierung* His numbers per square degree for zones -f 28% + 29',
+ 30*, +31", are 14^9, i6'2, i6-4, 16*4; so that, the diflterences per
©nt. between the north half and the south half of plates in zones
with centres +29'| +30*, +31*1 hero disciisse^l, would he 8*1, 1^3,
0*0 ; mean, 3*1. This is comparable with uur 4*0 per cent, and
^Uhe difference la what we might expect, considering that Argelander
^Bpnly goes to magnitude to. But it is unsatisfactory that the
^HlitlereDce is chiefly in one zone. We may put this down to
IHsccidental error, but the evidence is on)y suJlicient to state a case
for inquiry. In Monthly Notices, vol Ix., plattj 2 (opposite p. 16),
Mr. Bellamy has given a curve showing the approximate variation
in stellar density (for the Oxford zones) with Galactic latitude
aomewbat as follows : —
iplat
Beona
the
Ox
mu
P^wit
Tablk XIV.
&tLlM!k <f. to'. ao% 30*. 40'. 50** 6o\ 70', Bo\ 9j\
^Ko. ofttart 800 460 310 230 iSo 155 135 120 no 105
BmneM 340 150 80 50 25 20 15 jo 5
ogN 2*90 2*66 2*49 236 2*26 219 2*13 2'oS 2*04 roi.
DeraiieeM 0*36 0*17 0-13 0*10 o^>7 0*06 0*0^ cro^ Q*<;ix
M2
Prof, Turner, Star Images photographed lxvul \
20. There are two important points lying away from the cmrvs,
but we will neglect th^m in the folio winj^ brief an<i general remark*.
The Galaicy cuts the parallel of 30* Dec- about 5^** and i^J^-
(A) At these croHsing points the changes of stellar density
very large, but if (hey are ^ym metrical on opposite sidf« of
Galaxy thero fihould be a rou>,'h coupensation. On one side
N half of a plate will be richer, on the other the S half. We mi
be prepared, however, to find this compensation break down
Milky Way is ud symmetrical.
(B) In the neighbourhood of o** the Oxford z(»ned are
the Milky Way, south of it, and nearly parallel to it. Thus to
pass from the southern half of a plate to the north is to approach
the Milky Way, and consequently to find more stara. In these
R.A/8, thereft)re, we may expet-t to tirul the main contributions to
the dii>crepancy between N and S halves of a plate. What is the
maximum contribution we can expect from them? Suppose they
ran all the way from 20*' to 5*^ (9 hours of K.A. out of the 24),
parallel to the Milky Way and 15" from it. We see from
Table XIV. that h»g N increa^ea 017 in 10* of Galactic latitude
or 0*017 ^^ 1' J ^^ ^^^^ 10^ star« on the S half of a plate woulJ
become 104 <jn the N half, due to approach to the Galaxy, ThiM
is an [ticrease of 4 per cent., which is about what is required
but it b«eoine^ inadequate when we take 9/24 of it in order to
distribute it round the whole xone. This fraction 9/24 coiTespondi
to uniform diatrtbution in R.A., which is, of cour^e^ not in si\' ~
acconlauce with the facts ; but weighting each hour by
number of stars in it f^^ivea a nearly e<]ual fraction, since the rick
Galnctic portions are chiefly in the non-contributing RA.'a.
(C) For the remainder of the zone contributes nothing, or gott
the other way. We have spoken of the crossing points in (A)
above; from R,A, s^-^*', for instance, the increase northward* is
rapid for the first half hour» but is balanced by an equally rapid
diminution when the central line is crossed. Beserving for future
inva'ili'^atLon the effects of possible asymmetry, we may put aside
this crossing region as contributing nothings Proceeding to
greater K.A/s, we are now north of the Galaxy, and thus stars
decrease in number as we go north wards. The quantity N-S will
thus be negative. But the zone +30* is a small circle of the
sphere, and presently its sharper ctirvature brings it fjerpendiculjir
to the Galaxy^ when the difference K-S will be zero, and thea
positive again. It is positive for about an hour only (near i^**)
and then is negative again up to 19^ {^y)t when we get the other
creasing p^Jint (i9**-2o^').
21. These facts can, of course, be exprei^aed in tabular form,
and are given below in Table XV. ; but it seemed desirable to
attention to them alao in general terms, because general consid
tions seem to show that we cannot fairly expect, by impro
knowledge of the details, to ex ]) lain the whtde of the diffe
N-8 by actual distribution of the stars in Galactic latitude altM
The figures given below are only approximate : they could doul
ed;
r ia II
ndi I
m
rick }
Mar. 1908. for Oxford portion of Asirograpkic Catalogue, 415
less be improved, for instance, by using Professor Kapteyn'a results
j in No, 18 of bis publications, which have become available by his
j kindness in sending an advance copy since Table XV. wm con-
1 atructed, lint the change would not be i^reat. One of the moat
. important details left ont*?tanding is that of the flymiiietrj or want
of symmetry of the Galaxy on opposite sides; but Professor
Kapteyn's paper does not touch this point, since he has not yet
undertaken any discussion of distribution in Galactic longitude.
Table XV.
Gal. LbI.
-33'
-II
Calcd. N-S,
per cent.
+ 3
^J
+3
+3
+4
ObiOTTed (N-S> per cent.
31%
+ 8
+ 10
+ 8
+ 24
+ 8
+ 3
- 6
- 12
o
- 17
+ JO
+ 21
- 3
+ 13
+ 8
+ 18
+ 34
+ 24
M«&n.
O
-*- 4
+ 5
+ 8
+ 24
+ 16
+ 11
+ 23
+ 35
+48
+ 61
-a
o
o
o
o
+ 15
+ 9
+ 5
+ 5
- 4
- 3
- 3
- 5
+ 4
- 5
+ 9
' 4
+ 2
+ 2
o
+ 4
+74
+«6
+79
+ 53
+ 40
+ 28
+ 16
+ 4
o
4-1
o
o
o
- 1
- 1
- 2
+ 4
+ 4
o
- 4
+ 8
- 7
+ I
+ 7
+ 2
+ 10
- 5
+ 3
+ S
+ 11
+ 10
- I
+ 7
- 2
o
- 2
+ 6
- II
+ 22
+ 3
+ 3
+ 18
+ 4
o
o
+ 2
+ 3
+ 8
+ I
+ 6
+ 5
- 7
-16
-30
+ 3
+ 3
+ 3
+ 3
+ I
+ 11
+ 2
+ 15
+ <5
+ 4
+ 12
+ 11
+ J4
+ 9
+ 9
+ 8
+ 10
+ 8
+ 8
+ 11
22. Percent'! ges are given in Table XV. rather than total
numbera of stars* in order to avoid unilue influence frora the
, Galaxy. It will be seen that the ob-erved percentage is from
^^'$ to 23^'5 +9, and from 0^5 to 4*^*5 it is +8 ; the mean for
the whole 9 hours being +^'7, as against a theoretical -\-yi.
For the portion 6*' 5 to i8*»'5 the observed N-8 percenlage is
-+2'2, a« a>;ainst a theoretical -0^5. Hence the mean observed
' K-S is throughout in excess of the thcuretical; ov, \\i QVV^t
29
4»4
Prof, Turner, Star Images^ etc.
LXvnis,
WDrds, only a \iiiTl of it can be set down to star fiiBtributioii ; tie
rest mtiat be due either to atmospheric absorption or unsymrn*- trial
performance of the o^ject-giaae. But these latter causes «ln ihA
vary with the K.A. If we estimate their combined effect aa 3 «
3 per cent, (being guided by the figures for 6*^*5 to i8*'"5, whe^
the effect of stellar distribiiiion is small), we get 6 or 7 \*et cenl,
for the observed effect uf stellar distribution in R,A. 20*'*5 to
4^*5 instead of about 3. TlnH suggests that the rate of dimlnittiail
with Galactic latituile has been considerably underestimfited ill
those regions. A scrutiny of tl»e figures shows that thk is quile
pOHsibly the case^ tbe reason being that the rate of diminution
varies considerably in different Galactic longitudes. But a eon]-
plete discussion of this point cannot be given here.
Sunifnarf/.
§§ I, 2, Introductory.
§§ 5, 4. Method of measuring the average star desisity on vaA
quarter- plate, at different distances from the centre.
JJ5. Delinition of A, which indicates the distance of mftxitnuiu
density from the centre. Table ot values of star density and toUl
number of stars for different values of A.
,§ 7. List of observe" i values of A, in oixier of date of expoCQi^
of pLtlBs, in vo\% i., ii., and iii.
§§8-11, Variations of focal length indicated by changes of
mean A may be due to discontinuous disturbances of the [»liU,
but are more probably due to seasonal changevs in focal length.
But there is certuinly one discontinuity, at the erection of tJji
new dome in 1900* Befnre thii the [date was satisfactorily normil
to the telescope axisj aft-^rwards it was apparently tilted lu R.A-t
greater R.A.'s hein*; nearer the O.G.
§§ 12-14. I>^ consequence of tids tilt, the side of greater KA^is
richer in stars ; but the detailed study of the effect of tilt li
reserved for a separate invest igatitm.
§ 15. But there is an excess of sUrs in the N half of the plilfi^
which 13 4 per cent, richer than the S half, and this cannot be due
to tilt.
§§17, iS. Visual atmospheric absorption would give an eic«i
of o^^5 per cent* ui the N half: phot<jgraphic absorption may be
greater, but its value cannot be well determined from the Oxfocd
plates, which were taken at nearly constant Z,I>, A speciil
investij^^ation of it is denirable.
^19-21. The distribution of the stars in Galactic latitude
alone explains a part, but cannot explain the whole of tbfl
4 per cent, excess in the N half of the plates. The general tiatat»?
of the distribution in Galactic longitude is such as to expliui
another portion gf the excess, b^t quantitative esUmates cauoot
yet be made.
Mar. 1908. On tits CoirelcUmis of Stellar Characters, 415
nrfher Cormderatkms mi the Carrelaiiotis of Stellar duLradetn,
By Winifreci Gibsoij, B.Sc, formerly Jessel Scholar, Univurgity
College, Lijndou, ami K irl Pearson, F,R>S,, University College,
London, (Witli Six Diagrams.)
(i) Introdnrtory. — In a paper communicated to the Society last
JBAT (Monthly Not tree, vol Ixvi. p, 445), mod en 1 statistical methods
used for the first time t<> determine the numerical rtdatioriships
it ween various star character.*. Tin* objeiit of the prea«nt paper
to deduce further similar relaliom^iiipSj and to deal with some of
e .same relationships on the basis of widiT data. Tlie general
aracters with which we have to deal and whicli are more or less
;curately known for larger or smaller stellar populations, are (i)
gnitude, (2) colour, (3) spet tral class, {4) proper motion, (5)
rallax, (6) position. In any attempt to look upon the stellar uni-
rse as an ordiM-ly whole, the relationships hetweeu these characters
lELUst be of fundamental importauce. To determine their numerical
values is the lirst stage by whirh we pass from chaos to an orj^^aiiised
und locally differentiated cosmos. The aid which the atatisticiao
may venture to offer ttie trained astronomer in this respect may,
perhap}*, be illustrated by reference to some recent work. »Siiice
the publication of the first pa|>er above referred to, two memoirs,
both of considerable imp*»rtance, liave apj>eLired. The first is that
of Messrs, Glia^e, Smith, and Elkin (** Parallax Investigations on
6 J Stars, niainly of large Proper Motion," Tramactiontt, YcUe
^nu% Obmrvatv^ry^ vol. ii. pp. 1-207). .I'his memoir deals with
relationsbi|» of proper motion, magnitude, pamJlax, and speiitral
, among oiucb else of great value, hut^ not bearing on the topics
have at present in hand.
A second memoir of less scope but of considerable interest is
that of Mr. W. S, Franks (**The Relation between Star Colours
and Spectra," Monthhj NotifeSy vol Ixvii. pp, 539-42). Now,
I these memoirs more than suffice to show that the distribution of
star characters is not one of mere random association. The
characters occur in a coirelafed manner, and this in itself is
suggestive of the cosmos being a differentiated organ is? iti on. Even
twe at once admit that we might anticijiate that parallax wonid
I related to proper motion, or even to magnitude, or, again, that
lour and spectral group would he found in assficiation, it la loss
^vious that spectral class will bo found related to magnitude,
oper motion, and parallax.
Yet, even when we see these relationships indicated in the
anove and other memoirs, there appears to be S(imething lacking,
which it is, perhaps, possible for modem statistical naethods to
supply. It wouhl not be possible from the above type of
ciaasificatory work to determine the intensity of the relationship
between the characters under consideration. For example : Is
parallax more closely associated with magnitude 01: n«\V\x *^^^cXt^
€l886 1 Or, again : Is magmtude more closely telaled U> ^\gX/&\i<^
4i6
Miss Gibson and Prof. Pearson, On the LxniL j,
than to chemical composition ? To say that the latter is nearly
four times as itifliieritial as the former is to crystallise ai once our
general ideas oq magnitude.
Accordingly, it seems possible that modern statbtical meth
may be of some aid in deterraiiiinff the intensity of relationship
between various stelhir characters ; in appreciating what, to adopt i
term from biometry, may be spoken of as the organic correlationi
of the population. It is not suggested that, any more than in the
science referred to, the individual must be lost sight of in a clood
of averae;e relationships. But a knowledge of the extent to which
stellar characters are correlated may, if properly used, be helpfol m
indicating the directions of profitable further analysis,
(2) Determination of Corrdaiion. — It may not be out of place
her© to give a brief summary of tba constauta by aid of which co^^ell^
tion is determined in modern statiatical practice. This is the raor»
impi^rtant a^ it is desirable to indicate the limits of their proper
application in the case of stellar characters. The methods in im
are threefold : —
(i) Coff^icietit of Oorrelaticn, usually represented by r» This
can only be iismi effectively if both characters are quantitative ami
ctnally measured^ Let A and B be the two characters, m, and fn,
beir mean values, m^ + st, m^-^t/, the cliaracters in any pair of
'Individuals, o-j and o-^ the standard deviations (square roots of
mean square deviation? of either group of characters) ; then if i* b«
the size oT the sample taken of the population,
r^^='S{xi/)/{n(r^<T^) ,
V possesses the following properties : it lies between - i and
according to the intensity of the relatiunship; r^^frja-^ is the
of the best fitting straight line of the average values of A for ti
given value of B ; and r^2i^g/<r^ is the slope of the corresjionding line
for average values of B for given values of A. o-^ ^1 - r^^^ is iht
average standard deviation of arrays of A for given values of B,
and ^''2 V* ~ ^12" ^^ ^^^^ average deviation from the straight line of
arrays of B for given values of A. When the average values ot
one character for a given value of a second lie nearly on a straight
line the correlation is said to be linear, and in this case the vaui&b-
ing of r^2 ^^^ks the absolute independence of the two characteif^
r^2 ia always the same m n,*
All this is completely independent of the nature of the frequency
diatribution. Provided the characters are (quantitatively measur-
able and the correlation is approximately linear, the correbtion (
efficient r is pre-em intently the best suited to express the degree 1
interdependence of the two variables.
For example, it was used in the fir&t paper in determining tbi
relationship brtween proper motion in R.A* and in declination.
(ii) The Oorrelaiion Ratio^ usually represented by tj. If the
curve of mean vakiea of A for given values of B depart widely froa
straight line, tben the v&idshing of r does not necessarily mean I
Mar. 1 908. Correlations of Stellar Characters,
417
the characters A and B are utirelakd. It would only signify that
the best fitting straight line was horizontal In order to cover this
case the correlation ratio tj ban been introduced. Let 2j he the
standard deviution of tlie niearu^ of arrnya of A for given values of
112 = 5^1
(ii)
possesses the following characters: it lies between o and i, being
always zero if the characters are independent, and unity if they
are absolutely related or causal, i; always lies between r and i
and is equal to r when the correlation is linear, cr^ Ji — i^^j* is the
mean standard deviation of arrays of A f*jr a given B. ctj s/vi^ ^ '*ia*
is the mean square deviation of the curve of means from its best
fitting straight line, -jy^g is not necessarily equal to ly^r When the
correlation is approximately linear, we have i^i^ = i?*ji = f j^ v^ry
closely, and this relationship holds for a very wide range of
physical and organic variables.
-j;, the correlation ratio, will clearly be of service when one
variable, say B, is not quantitative, hut classifjcatory, because in this
case we can determine %^ and <Tj althoygh we have no quantitative
measures of B. We ought, however, to have fairly fine groupings of
B. Such cases are those of stellar spectra and stellar colon r» On
the other hand, iqy^ *^^^ Vn ^^y ^^® found in order to nieasnre the
degree of divergence of the curi'elation from linearity. As illustration
of this, we may consider magnitude. If we replace it by amount of
lightp this might poBsihly give a true quantitative scale; but not
4inly does the reduction involve some doubt, but it intro^luces ex-
tremely laborious calctilations compared to the simplicity of magni-
tude proper. Accordingly the tj method, classifying accord iog to
magnitude, seems a suitable method of approaching the problem.
(iii) Voefficimt of 7fiean square Omfingency^ usually represented
.,c,.
Let the arrangement of any table of two variables— p,^. Mr.
ranks' tables of colonr and spectral class — he purely classificatory.
Let the frequency of any class a of A in tiie jjopulation N be n.,
and of the class 6 of B be j/^ ; let the frequency of individuals
combining both classes be n,,^, then
L
♦'-M("-'-¥)'/¥'}r
(iii)
IS termed the mean square contingency, and it clearly vanishes if
.e distribntton of the two cbamcters be independent,
C|= J^y^li^ +^^) ^ termed the coefficient of mean square con-
ngency, and it raeaaures the deviation of the two characters from
independence. It approaches unity if the characters are causaJj
and is zero if they are independent.
The whole of the above brief resum^ of the usual statistical
methods of dealing with correlation is independent ot m\^ asaMTa^-
418
Miss GUboh and Prof. Pearson^ On the Lxvm j?
tion as to the dis^tri buttons of frequency following the narma)
Gttusaiati law of variation. Should they do so» however^ we hat^
r = « = C,
%
or all our three methods of determiiiing the inteQsity c»f corrdation
merge theoretically into a single value.
We siiy theoretically, because the truth of (iv) depeoda upon
our replacing auniniation by integralR, or it is the limit wif
autiieieritly line grouping. Ey actually testing (iv) on fail
GauAsiflo material it will be found that eveti moderately
claseiJicatious give ^ts quite close results. Deviations from (i
arise, not wholly, but rhit^fly through the characters dealt with
being nuu-Gauftsiau in distribution of variability. We venture
think that possibly astrtmomers have been too mady to assume ti
all types of variability follow the Gauasian law of distribution,
that the assuuiptiou that star characters follow it requires atatistii
justification. It is, perhaps, rather dangerous to start with
doctrine tbat they must, and then deduce rather sweeping conclti
sious from the fact that thoy do not. In the present inveatigatii
the correlation coefficient, Uie correhitiun ratio, and the coefficii
of menn B^|tiaie contiiigency will be used according to the nature
the statistics wilh which we have to deal.
The probable error of r is calculated from
I
aad of 1} from
p.e of 13 = ^67449(1 - if )/ VS.
values^
These values are not the absolutely con-ect
sufficitintly close for moat practical purposes.*
The probable error of C| is troublesome to calculate, t hut if
be two to three times greater than •67449/VNp this being
maximum value of the probable error, i.e, that when C^^o, it
unduubtedly be signihcant.
(3) Gorrdatiom wifh Stellar Colour,— (i) Colour afid Magnu
tuffe. — ^hi the earlier memoir stellar colour and magnitude were
correlated, using for this purpose the catalogue of star colours con*
tained in vol- ix. of the Annal» of the Cajie Obttervatort/, The start
included in that list range in nia^nitiide from 4 to 10, being 4 t<>9
for visual and 6 to 10 for photographic magnitude. The colours
ranged from yellow to red, and contained no blue or green
white. In ordt^r to include green and blue atars we used, at
suggestion of Mr. T. W, Backhouse, the star catalogue in toI li^
of the Harvat-d^ Annah, That list iucludes stars of photographic
magnitude - 1*5 to 7, and contains about 3*6 per cent, of blue
green stars. A table of contingency for magnitude and colour
* For probable errors of r And 17, see IVflrson, ** On the Central T1i«Jiy<
Skew Corrt'latioii/' pp. 19 and 2o» £h'af>ers* He^s^trch Meintnrs, Dulau k Ga>,j
t BliikimaM ami Pearfton* **0n the Probable Error of Mc'ao Square f
tingeiicy," BicnDHriko,, vol. v, v\k igi f^ srg.
I
M
m.
T. xgoS, (Jorrelaiwm of Siellar Cfutracters,
419
tile case of 2834 a tarn b given below (Table L). In grouping for
ecMitiDgency we reiluoed this to h 6 x 9-fnld table, but the means
W6re calctilateil on the basis of Table I. The results reached were
AS foUows : —
I
PreviotiB T»hl«,
Toh IxvL, p. 455,)
Mean magnitude ... 8*58 ± ^05
Standard deviation . , '835 ±'032
Coefficient, of contingency -304 ( ± '05)
Pt«tent T»bte,
5'«5 ±012
'906 ± *oo8
•271 (± *oi)
Thus while the two groups of stars differ very widely in mean
cliaracter, we s*»e that the dejiandenee of one churacter on the olher
is essentially the same in the two samples. The redaction of the
Table I.
lOoftHngency Table for Coionr and Phoiofp'aphk Magnitude,*
Colour.
Blii«. Green.
White. Yellow,
I
Orftiige. Red.
t
H oto*5
3
I
'
4
^^M
V *5toi
...
...
I
I
2
^H
1 to 1 5
.,.
3
2
2
7
^H
1 '5 ttf« 2
...
6
6
^H
2 to 2*S
1
11
12
r
25
^H
25 t« 3
i».
6
9
12
3
1
31
^H
3 »« 3*5
'
5
16
39
8
...
69
^1
3'S to 4
...
9
32
68
12
I2t
^H
4 t«> 4*S
t
>7
6t
121
27
227
^H
4S^S
4
15
112
191
54
8
384
^H
5 *«> 5 5
8
16
2dS
37<
in
9
723
^H
S'5to6
4
h
239
425
140
»3
S27
^H
6 ta6*5
5
1
is2
igi
77
S
362
^H
65 to 7
10
24
9
I
44
^H
7t«7'5
Totals
I
,-.
...
...
...
...
I
^H
26
76
791
1458
44S
37
2834
^M
• la the iiiagnitutle class, the group inc!uti<'*i the firat and oxcltidfta the
MOotid vMlttt! ^ven. TUutt all atnni Wuifi enumerated to one decimal in
Vaflkiluda, the f^Ton\\ 4 to 4-5 coiiUiiis 4-0, 4I, 42, 43 »"d 4*4 ^^^^ or
^mMtat 4'2. Th« blank hne» intiicate the mnguitiifle groups actually used
in 6tAndiig the ooDtiiigcmcy coefficient from a 6 x 9 fold tahk.
1
Jl
B^
A
J
420
Miss Gibson and Prof, Pearson, On the LXTIU. 5»
mean magnitude by three classes, the introduction of hlu**,
green, and while stars, has not esseiitially altered the nttmeri^^
relationship between mtignitude and colour There are seTenI
poiDts about this which deserve fuUer consideration^ ^Itgni-
tude is often taken aa a true variable. When dealing with
the rel»itioii»hip of magnitude to parallax in the former paper it
was shown that magnititde used as a numerical vari€Lte, imlesa we
convert it inro lii^ht unit^ doea not give very satisfactory reaollt,
and that, furth**r, the curves of mfana «uch as we find for stellur
charaufcers are generally widely different from straight lines. In the
present case we cannot calculate the correlation coefhcieut r, becaiise
there is no quantitative Rcale of colour ; we can, however, find the
correhition ratio 7} on the assumption that magnitude is a true
scalar quantity, which, of course, it is not. We find numerically
7^= '17 + •01, The results given on p, 4.56 of the former paper (for
visual magnitude) lead to t^ = ■ 1 3 ± 05. Thus, again, the two reanlti
are alike within the range of probable error. But we note at oiwe
that if mtigiiifcude be used as a tnie quantitative character we shill
not get results for Cj and 17 which are really comparable. Indeed,
a little thought will show that a mean magnitude is something
having little physical meaning, and the ratio of two mean majjiii-
tudes, which is the nature of ly, may often be deceptive.* We
must accordingly anticipate erratic results when magnitude is used
as a numerical variate, and we shall endeavour to adopt it onlyM
an index to classification.
Breaking, however, for a moment through this good rale we mvj
note that the mean magnitudes of the colour arrays are —
Colour,
Ked .
Orange
Yellow
Mag.
No.
37
445
145S
Coloar.
Green
Blue
White
Mag.
438
4*97
76
26
792
Whole series : Mag. 5' 15
No. 2834
We aee at once from this result that, within the limits of probable
error, the mean magnitude of the while starB la the mean magnitude
of the whole group of stars, or this group may be omitted when we
determine the influence of deviation frum mean colour on deviation
from mean magnitude. The presence or absence of white stirs
does not affect the contingency. In the accompanying Diagram Lt
a graph has been drawn of the variation of mean magnitude with
* The nifan niRffnitn^ie of two stars of magnitudes 5 nnd 10 is7*5, bot
the magoim^le of the gUr which haw their nieaii amount of light w 574*
Tlie m*'mn njagnitiule of two nUun of magnitude 14 Aiiij I ia mho 7 5, but tbe
magiiimdi' of tli« star with their mean amount of Jtght la 1 75. The ntio
of the means found in the hmt manner h uui ty, tii th« si>oontl maoiier matt
than 3. Yet we |if rpelually see men 11 magnitodea comfiared and the diflcrtac*
between theoj asserted 10 bo of aignificaiiae or iiou-aiguificatioe for th« clianct^er
^f steliiir groups.
t This diagram w&s taken oat of ita plnce in this paper and pabliabidf
without the data ou winch it is baaed, in a letter to Naiuref Oct, 17, 1907.
far. 1908. CorrekUions of Stellar Chairaeters,
421
<!cilour To obtain a reasoi sable scale of colour, we have used tbat of
the solar spectrum^ plotting first a curve of m&aii magnitude, and then
replacing it by a curve of star luminosity, the ecaltj of luminosity
being that in which the unit of luminosity is that of a siar of
magnitude 10. W«t have natunilty omitted the white stiirs. (If
the white stars be omitted fmm the Harvaril data the value of the
<x)Diiiigenc'y is '397, a value in absolute accordance witli that found
for the Cape stars in tlie earlier paper.) The graph shows at once
a somewhat striking r'i.sult, — the distributiuii of luminosity amoiig
the coloured stara gives a curve remarkahly similar to that of
luminosity m the solar s[>ectrum if we shift the solar curve towards
the violet end of the spectriini. How far is tlie Ufethod of deter-
niiDing magnitude influential in this matter? We have at present
500
S^
Ccfrt^e of bpectram
L am in Q^ity ^
Ct/n/e of
5far
Ly/nmQ^ity
i?e£^
CrS*,,y€iiaw
6r€en
Blue I ri^mf
iAO
tao -^
tao \
»o
60
Spimr
Sf>€.Qtruin
DlAORAM I.
in hand the Potsdam colour oliservatioiis, and hope shortly to
publish further results on this point.
(ii) Colour and Spectral Cims. — As far as we are aware, tio
claasifications of stellar colour according to parallax or proper
motitm liave yet bi-en made, Mr, Franks has recently published
three tables * giving the classification of colour according to spectral
class. The&e tables, as they stand* are actually contingency tables,
but the smallness of some of the groups and the extremely laborious
process of working out 7 x 12-fold contingency tables has led t»s
to coDcentrate the material in rather larger rolour groups, keeping,
however, the spectral classes the same« We have taken as our
colour groups (a) O, (h) YG^ Y^, OrY^ (practically the ** white *'
group), (r) Y\ (ei) QrY\ Or\ (e) Y\ OrY\ 0?-«, {/) OrR'\ R\ thus
making six colour groups or a 7 x 6-fold tablf\ We owe to Dr, A.
• Loc, ciL, pp. 539-54 ».
422 Miss Gibson and Prof. Pea/non, On the LZVUL 5,
Lee, of the Biometric Laboratory, University College, Loodon, tlw
calculation of the constants for Mr. Franks' three tables, with thft
following results : —
CorrdcUion of Colour and Spectral Class,
432 Southern Stars from - 25' to S. Pole . Ci = 71
928 Northern Stars from - 25' to N. Pole . Ci = 74
1360 combined results . . . . . Ci = 7i
These results are of much interest and in very close aocordanee.
There is no substantial difference between northern and southern
stars in the relationship of colour and spectrum, but, as we might
have anticipated, there is a very high relationship between the two
characters. The relationship is more than double that which we
have found between magnitude and colour. We shall see later
that spectral class is far more clearly associated with magnitude
than colour is.
Accordingly, we may sum up our first results on colour as
follows : — The colour of a star depends to some extent on its
magnitude, but in a far more marked manner on its spectral class.
It seems unnecessary to reproduce Mr. Franks' southern and
nortliern star tables. His total star table is given here, with the
groupings adopted, and in brackets the excess or defect of each
group from the independent probability expectation.
Tablb n.
Contingency of Colour and Spectral Clas^.
Helium stars 125 146 8 3 00 282
(+63-62) (4-42-95) (-36-37) (-3474) (-33'i8) (-2*28)
Hydrogen stars 168 195 14 o o ©377
( + 85-95) ( + 57-23) (-45*32) (-50-45) (-44*35) (-3*05)
a CarinsB 3 97 23 8 60 137
(-26-82) (+46-93) ( + 1*44) (-10-33) (--10-12) (-I-II)
Solar stars o 41 77 33 29 o i^
(-39-18) (-24-78) ( + 48-68) ( + 8-91) (4-7-82) (-1-46)
Arctiirus o 15 86 77 63 o 24>
( - 52-45) ( ly^i) (+48-08) (+44-75) (+34-65) (-1-95)
Aldcbaran o o 4 22 43 6 75
(-16-32) (27-41) (-7-80) ( + 11-96) ( + 34-18) ( + 5-39)
Betelgcuse o 3 2 39 19 5 68^
(-14*80) (-21-85) ( -8-70) (+29-9) ( + 11-00) (+4*45) _
Totals 296 497 214 182 160 II 1360
The great regularity of the cUffj-rences certainly speaks for the
excellence of the spectral and colour classes adopted by Mr. Franks.
(4) Correlations with Spectral Class. — We have seen in the pre-
KTk
igoS. CorrelcU'ions 0/ St^eltar Cliaracttrs,
423
»3
Stars,
12
i»
34
*»
29
ri
5
f»
5
It
eedJDg aectiou that the as^oeiatioD of spectral cla^^s and colour is
yurkedly bigh^ K^^^^^ the mean squiire contingeticy eoefiicieut
^K='7i. Data for the correlations of spectral class with magni-
^lae, proper motion, and parallax are given in the Yale UbntjiTatury
memoir already cited,* It ia true that the oumber of stars ia
small, but the total of 98 ig larger than we were a hie to deal with
when consiiiering parallax in the fir^t memoir. Furtherj some of
the spectral classes have so small a frei|uency that, for stitistical
purpofie&j it wiis al»8olutely needful to groap certain classti^s together.
The classfjQ actually used in the notation of the Draper Catalogue
^H class A
■ Cias8 E
^H ClaH8e« F and G
^^^^H Classes K and I
^^P Chi^ K
^^^^ Classes M and 1}
PBfeictically, no weight can be })Iaced on the last two results.
Xow f parallax and proper motion are true quantitative characters,
nod Tj is accordingly the proper constant to calculate in these
cases. It has also been found for magnitude. We again owe
the whole numericnl work to Dr. Lee. The revsults come out as
follows : —
Correlation Katio of Spectral Class and Parallax, »/ - '36 ± '06
^H „ „ „ Proper Motion, tj =» -39 ± *o6
^H „ „ „ Magnitude ij = '68 + '04
^^Htal these re.^ults are signiiicant compared with their probable
PHHHl| but before we discuss them it is well to a.^ceriain whether
the la«t result will be confirmed if w« drop the idea of magnitude
ia scalar quantity and proceed only by using it as an imlex to
Bai 6 cation. Table III. is a contingency table for magnitude
1 spectral class for these 98 stars : —
Mm
•5
TAnr.E III.
Contingency: Spectral Class ami Mugnitude Clw^,
Draper Ottiahgue.
Mjisnitude. A. E. F ikiid O. H ami I. E. M. And g. ToUli.
•5 to + '5 I ... I ... 1 J
•510 1*5. 2 ,.. I .., 3 6
,i'St<» 2'5 3 ,., ... ... ... 3
'%io 3's 1 ..* 2 ... 4 7
r5tr> 4*5
rSto 6'5 I 5
►•5 lo 8 5 6
Tot»ii» 13 12
»3
12
16
n
34
29
9*
LiK\ ctl,, sve Tnhle v, p. 204.
Miss Gibson and Prof, Pearson, On the lx\
In working this table we have grouped in magciituide - '5 1
1*5 and 1*5 to 3*5, or dealt only with a 6 x 5-fold table. ""
material h too sparse for finer cla^si6cation. This table givn I
C, — '69(± 07)* It accordingly fa lly confirms the value obtaia
by the rj method. It is, |>erl)ap8, worth noticing that it h in the
first place the K^ M, Q group, and then in the next place the F, Q
group, which contribute most to the value of the mean square con-
tingencj, i.e. these are the classes which have most markedly
differentiated magnitudes. We see that the relationship between
parallax and spectral class is only a little more than half tint
between magnitude and spectral class. Or we conclude tbat^ on
the basis of the Yale stars, the present chemical constitution of a
star is of considcrnhly greater importjince than ita distance in
dettTmining its magnitude.
It muatf however, be remembered thai 98 is rather a limited
number to base definite statements upon; and as the point is of
considerable interest, it is important to consider the matter from
, other aspects. Before the Yale memoir came to band we bad
already formed Table IV., giving the magnitudes and sf^ectnl
classes of over a thousand stars. It is baaed on the data provided
in vol. xxviii., Harvard Ob»ervaionj Annals, Pickering's 2i
spectral classes wonld give a contingency table of unworkable
magnitude^ and accordingly we have grouped his spectral classes ta
follows, making a 7 x 8-fold table : —
Tablk IV.
Contingenci/ of Magnitude and Spectral Class,
M&gultude.*
B«lon- !
1 to 2
2 to 3
3*0 4
4to5
5 to 6
6 ta 7
7 and above
Totali
X.
4
6
9
13
70
50
58
233
12
31
24
22
96
Spectrai Ctwa.
2
10
22
34
87
60
40
306
V.
4
S
62
153
69
40
18
U.
I
2
3
4
5
6
2
I
E
I
9
20
It
5
366
49
t6
Our Z = Pickering's groups i to 5; Y = 6; X = 7toii;V»«3
in 16; U - 1 7 to 20 ; W = 1 2 ; T = 2 1 (does not occur) ; S =« 22-
Tlie mean magnitudes determined from a -5 grouping of the
elaases arranged in order of mugnitude are as follows : —
* Magnitude 4 to 5, for example, contain a all start of 4tK and 1«» thM
5tl) niiigfjitiide.
Mar. 1908. Correlations 0/ ^llar Charncters.
425
M«an Miignltiiae.
No. of Stan
Class S
6*29
16
„ X
S'20
«33
.. Y
5'i6
96
.. z
5 -02
306
., V
4-7'
566
„ w
4-62
"49
„ u
4-57
48
Wliole aeries 4-95 ± '05
Slandftrd deviation of whole series = 1*49 ± *o:
1114
^.^
The coeffident of mean square contingency for this long serie*
was C| = *43 { ± '02). Thus, while it is not %& large us that found
the Dm per Catalogue starg given iu the Yale memoir, it still
uU to a fairly close relationshiiJ between spectral class and
mttgnitude. It will, of course, be obvious that the order of mean
magnitude of the Bpectral classes given aliove is nol that of
Pickerings cla8s numbers, so that it may be presumed that the
characters which led to his order of classification are not those
which Iea<i to order of niaguitudc. If wc attempt to place our
magnitudes in a continuous curve, we note that (i) more than one
pair might be iuterc hanged without aifecting the limits fixed by
the probable errors of random samplings and (ii) we have do
spectriil scale upon which to ph^t tht^ mugnitudes or luminosities.
The latter ilifficully may be overcome in a manner which has
proved of some service in other branches of stalistical inquiry,
namely, by assuming that the total spectral frequencies of each class
are portiim« of a normal cnrve of frequency, and then plotting oci
verticals through the means (as detluced from a well-known-
property of the Gaussian curve) of the coiTesponding areas*
Aataimng that the groups, being merely qualitative^ may be inter-
ehMi^ed in order, it rarely happens that more than one arrange-
meot gives a continuous curve. We have fonnd Diagram II, by
this method, filotting both magnitude and luminosity* curves. It
will be seen tbat fairly smooth curves are reached iu this manner;
they would pritbably have been better had the U stars had greater
frequency, and the V stars been di^alt with in smaller groups. The
diagram sug^^feata, withotit of course proving, the likelihood of an
ascent to a nmximnm luminosity from two different ends of a
spectral c I as^iti cation.
1% appeared probable that a classification of spectral characters
baaed more Silmtttedly on temperature considerations than th(»se of
either Secchi or Pickering would lead to a still high correlation ship
between magnitude and spectral character. Accordingly, appeal
was made to Sir Norman Lockyttr, who, with great kindness,
provided a key index linking Pickering*s chisses with his own
temperature classificHtion. On further consideration, however, it
* The lamtnOHity of the star of the lorli magnitude is taken «s the uavt
and Pog«oo% value of the coutttant adopted.
426
Miss Gribson and Prof. Pearson, On the Lxvitt 3.
- 3
s ?
SCALE OF LUMINOtlTY
$S29o20ooooooo§oooooooooo2
1—1
CO «M
I
=1^
« i/t <0 >;•
T'l I M a:
I !
S
8
- ; 5
! . I
4-^ 1
i I 5
5
— rJ K) <*■ lA «0 r-
SCALE OF MAGNITUDE
Mar. 1908. Coi-relaHom of Stellar Ghaixicttrs.
42;
eeemed prohftble that somewhat better results would be r«iiched by
working with Sir Norman Lockyert* own dassi^ed catalogue,*
although til is involved supplying from other »our<'f8 (Hurvard
Photometry, where possible) tlie nia*,'nitudes ol the recorded stara.
We have from this catalogue formed Table V., giving 8|>ectral class
id magnitude of 448 sttirs.
Tablb V,
Contingency: Stdlar Mag^iUwle and Specircd Class
(Loekyer^n Clamfieatimi).
^^K Clnw> ITridcr 1-5.
> 5-2*5-
»S-3'S.
r5-4*5-
^ '5-5*5.
5 5ftadover,
Tota]i,
Me«iL
^Hlrgouian
1
1
..,
...
2
^Klloitamian
...
4
I
2
1
...
8
(^•95^)
^^HD^cinn
5
»
31
6
3
52
27s
^HAehenii&n
1
1
t
S
7
...
iS
4X50
^^HTiiari&ii
\
t
i
«*•
5
(235?)
HftigoliAn
t.
I
12
'5
1
7
17
3-90
" Rigeliaii
1
1
I
...
3
1 ilarkiLMan
4
8
5
I
*i*
la
y\2
^^pCygnian
t
3
It
1
20
37
H
S
2
103
3"84
1 FoUriAU
5
2
6
13
3 "02
^^Ph>cyunlaQ
2
3
10
JO
5
I
41
3 '55
^Kldt-barian
S
27
16
I
*..
52
3 »4
^pArctunan
4
7
22
34
9
...
7^
3'40
AtltUlAIl
2
4
7
3
I
t*.
t?
27!
..,
• •
1
f
...
Totals 21
59 '46
153 53
16
448 3*39
Here t '5-3*5 signifies 1*5 and niiiicr 2*5. In finding the iue&D8, the grotip
I ** Quder I '5 " was hroken up into three groujis.
I The mean magnitude of the stars in this list was 3'39± 0*4, and
I their atandard deviation 1^158 ±'026, They are thus much
brighter and less variable than the stars of the two earlier series.
The contiDgency coefhcient for this grouping is
^ C,= S4(±03).
^M We see accordingly that the association of megnftude and
^Btpectral class has been sensibly increased by uning Bir Norman
^Bjjockyer's classification. The correlation is now about half way
^•between that provided by Pickering's date and the 98 Yale stars.
• Cai^tifvs 0/ 470 of the tiritjhter Stars clo.vtificd ticeordmij <o t^eir
i^k^tmiMry at the Solur Phync» Ohm-valory, S&atfi K$n9i'^Um.
429
Misi CHbexyii and Ptvf, Pearson, On ths Lxvnt \
Looking at the column of meaus^ and rearranging it on Lockyeri
plan,
Argonian I
Alnitatnian 2*95 f
278 Cmcian
2'35? Taurian
r
t
3*02
271
Ki^elian
Cygaian
PoUrian
Aldebarian
Antartan
B
'Achernian
Atgoli&n
Markabian
Sirian
Procjonian
Arctunan
4*00
312
3*55
340
I I^Pisciau T
ire ftee that the average magnitudes are greater on the side
"Descending Tern jje rat ure»*' and leas on the side of "Aacendi
Teiiipernture," but the order of magnitude cannot b© said to fit
clost^ly the claBsification op<Jer. The order is chaotic on
" Ascending Tern pe rut lire'' side j and although^ with the excepi
of the Markabian class, it ia orderly on tlic ** Descending Tt*ni^
ture" Hide, the jtialifiL*atioM fur the order does not lie in niagnitm
When more material is available, it would seem that a specl
classification according to mi'tan magnitude mi^^bt be anggesti
All that we can venture to say at present is that magnitude ia tttj
far from being independent of spectral class, but that the reason
why certain specti-al clus^aes have differentiated magnitudes is not
evident in any of the classifications here dealt with.
(iii) Spedral Ciam vith Proper Motion and Parallax,
now turn to the relationship between spectral class and pro|
motion* In this case we have only dealt at present with the t«l
provided in the Yale memoir, but there exists plenty of furthi
data which we hope to work uji. The correlation ratio for specti
class and the proper motions of the 98 stars given in that caae is
'? = *39±'o6'
Spectral class' is thus shown to be definitely associated witli
proper motion. The association ie only about half that of colour^
and sensibly less than that of magnitude, still it is quite a consiJeJ
able relationship. We mighty a priori^ anticiftate that the aasocv
tion was an indirect effect of the currelation of spectral diaa
parallax, but it is easy to prove that this is at least only partlj
the case. The correlation ratio between parallax and spectfui du$
deduced from the same material is
= ■36 ±.06*
This, agaiUj is quite a considerable amount of relationship^
it ia not greater but practically equal to the relationship of apectrJ
class and proper moUou<
ir. 1908. CondcUiom of Stellar Charaeiers.
429
Now if we have three characters, i, 2^ and 3, and if r^^ be the
relation of the first and secoud without regard to the thirrl, then
Pvi
jTr^
-^s/i-r,,^
M8 ^* 'M
TS the *' partial** correlation coefficient of the first and second chatactflra
for a constant value of the third. In other words, if the relation-
ship between i and 2 be solely dne to the relationsliip uf both to
3, we should expect that within the aiTay of i and 2 corresponding
to a constant value of 3, the correlation would be zero between 1
and 2, or p^^ = o. This means that r^^ = r,y x r.,^ is the test for the
correlation of i and 2 being eolety due to their relBtionship to 3*
Applied to our particular case, if the correlation between spectral
elasH and proper motion be solely due to the relation between both
«nd parallax, we should expect the correlation co^fhcient of spectral
class and proper motion to be equal to the product of the co-
■^letents of parallax with spectral class and parallait with proper
^Hkition. Now we havi' seen that the relationship of spectral class
^rith proper motion and parallax is about equal. Accord iugly, we
I »Uoiild expect a relationship between proper motion and parallax
^^t very far from perfect, or the correlation coefficient about unity,
^^his is very for indeed from the case ; it does not exceed 3 to ^5.
^B follows, accordingly, that the relationship of spectral class to
^fhtper motion is not an indirect efi'tict of cliemical constitution being
a function of s|)atiai distribution. It is, of course, partly due to this
result, but, to judge from the Yale data, there is a sensible relation-
ship between chemical constitution and intensity of stellar motion
in space.
We may form some notion of the amount of this, as follows*
iging fr«>m the valutas of the correlation ratios, we may assume
correlation coefficients to be not very dilferent from '4 for
ctral class with proper motion or with parallax. The correlation
iwisen proper motion and pamlhix is also not far from '4 (see
S)* Hence we hnd for the value of th« partial correlation of
il class and proper motion for constant parallax —
Pn= -/--4^rT==^2= -2857 - '5. «ay,
Vt - (-4)- Vi - C4)^
Thus, in rough number.-t, on the data at present available, about
25 p.c. only of the relationship between sjiectral class and proper
|Hption is due to parallax. It is desirable to place in a tahle (Table
^BEl.} the mean magnitudes, proper motions, and parallaxes, as ji^iven
^%f ih€ Yale results grouped as dealt with here. It is prhaps nn-
f-— OBMiry to observe that far more extended frequencies are needful
ore the numbers given can be finally accepted.
While scarcely any weight at all is to be placed on the results
jar cimee K, M and Q, we still see that for the remainder, while
Ihe orders of spectral class for parallax and j^roper motion are more
dike than they are in either case to that for magnitude, they still
' considerably from each other.
430
Miss Gibson and Prof, Pearson^ On the LXVill'
Mat^iltiKle.
Tablk VI.
Characters antf Spectral Cl^us,
Pftrmlluc.
Ptopcr ]
MeAij,
6-35
6 30
459
395
2*54
E
H ftiid 1
F -aid G
A
M una Q
K
4-98
All claMiiC«!«
•057
1^
> be I
T'l 8iim up our results fur s^ctr&l class we may oooeludi
fiiglily probable —
Th:it there is a very considerable rt^lfttionship between magni-
tutle and BpectrjJ c)a8t*e,'', which wiU probably be found Ui
inteni»i(ieil if more ^aiisfticiory sj»ectral categories can ba deter
mined. This relationsliip, howevt^r, is at present setmibiy lo'
than tlie relationship lietween colour and existing spectral ch
which is very higli. Thei^are, further, fairly considerable relati
in part independ*nit, betweftt spettml claas and both parallax and
proper motion. It u thun probalde that tlie chemical coust»tutii
of a Htar is not only associated witb a certain colour and brilliai
but also with its spatial jiosition (as determined by its disi
from u.s), its imitioii in t^pai-e, and its size (so far as size as well
intensity is an attribute of ma^aiitude).
(5) Carre/ at itniii with AfaimiiwJe. — In the present paper w#
havt^ alre»iily seen that magnimidtj is related to bilh coloar
epeLtral clawB. We may note here that the relation of ma^nitai
to epectral chiss m not due lt> the relation of lx»th to colour,
'the other hand, the rekti inships between spectral class and I
-cohrjr and magnitude are so high compared with that betwi
magnitude **iid colour, that it is highly probable that the purti
correlation l>etwe«n colour and raa^niitude for a jjiveu spectntl cl
is nefj'iduf^. In other wimln, if the colour classes were
ill order of the averas^e magnitude of the stars cno tamed in lliei
then, if wo confined our att^-ntion to one spectral class only, ^]
the Arcturua ty|>e, the order ot magnitude for the colour cl
within thia spectrai cUsh wonld he reverseiL
(i) MatjnKwh and Parallax.^^ln the former paper ibis reltd<
ship was drdtict^d from 72 stars given for parallax by Newcomki
The deticiemy of material woa f^dly admitted, and the results U
to correliitiou cimld only he considered as preliniiuary. Th<*f ifl»»
dicated, however, (i) that we sliould not expect to find a ^^^
high aHsociaiion betweim magnitude and parallax ; (ii) tli*t
ci»rrelalion coefS^dont ditierini: widely from both the correlut'
rulio and the cuutiugency coeflicient, the distribution was fm fr«Ji
B
1908. Correlations of Stellar CImraders.
431
normal; and (iii) the line of means was not approximately straight,
but the purallax rose again with the fainter stars. The Yale memoir
provides far better material of more than doubly tire amount,
namely, 175 stars. It is desirable to discuss howr far this diverges
from the previous results. The Yale autbore have grouped their
arrays of parallax in somewhat irregular magnitude classes and get
following results (Table ii. p. 20 1^ loc. cit.) ; —
No of Stan.
10
29
33
34
31
36
■0950
'o666t
•0558
'0447
•016S
•0472
Tadlk VII,
RADf^e of Mugn I tude. U«ftD Magi) I tu d e .
O'Q-i'5 0*81
aa-4'9 375*
5 "0-6*3 5-65
63-7 -o 6 '68
7'i-7'9 7'S7
8-o-9'o 8*33
The mean magnitude fur the whole series is 6'id± "i i, with a
idard deviation of 2*06 ± '07. The mean magnitude of the New-
amb series was 4 03 + '22, with a stAodard deviation of 274! 15.
It containel on an average murh brighter stara^ but was a more
yariable sample in brightness. It will be seen that, as in the hrst
eample, parallax tends to increase again with the faintest stars.
^Working out iy for the arrays of parallax corresponding to the
Hubove magnitude ranges, we have
^KFhe relationnhip, therefore, of magnitude to parallax is about equal
Hilo its ndation to colour, and not more than half its relation to
1 spectral class.
We can, however, approach the subject from another stand*
point: we may inquire in^o the distribution of mtignitude for
given arrays of paralhix. We have the following table deduced
our »uthor*8 Table iii. (p. 202) : —
Table YIU.
of sun.
Range of FarAlLoz, Mejm P^mlUiu
Mean Mufni
7
-O'lj to -0*07
-01 10
734
^
-0-06 to -0*00
-0*025
6-36
66
4-0*00 to -f-o-oa
+0*031
676
44
4-007 to ■fo"l3
+0-097
6 10
17
+ 014 to +0*20
+OM59
6 '34
The mean parallax of the whole series is o*"046o±*'oo35, with
I standard deviation of o" o664± ''"0025. In the earlier series the
Eiean pamiUx was o"*i45 ±"'oi i^ with a standard deviation of
o"*i34±*oo7, indicating that we were dealing, on the whole, with
a D<*&rer set of stars, but with a greater variability in distance.
It is obvious that very little can be judged from the mean magni-
• 3748 ; the amthors have y%, f The ttuthw* Wve" *ci66*
43^
M Us Gibson and Prof, Pearson, On the LX^viii.!
tudea, especially if W6 eicluile th^ fir*<t two categories of negati
pamll&3tes.^ We hB%e included Uieni because the authors do,
it 18 not easy to see why the 7 .^tars witb the greatest n^gati|
pttrullnxeH are to he looked uj>od as a clase with a reaJly loi
quantitative parallax than those of the 29 group with a les^ ne
parallax. Sinee the parallax cannot be below zero, what the res
signify is that an average error of o"'i i was possible io the j
of 7, and one of o"*02 5, or al>ont a quarter of it, possible in 1
group of 29 stairs. Errors of obaervation being thus more lial
in the 7 group, it might even be reasonable to supposn members |j
this group to have, on the whole, higher true parallaxes than thfl
of the 29 group ; and the appearance of this group at (he top
the high magnitude 7 34 is somewhat misleading. LeavioL;
however, to form part of the seriesj we find
I? - -20 ± -05,
or we oonclnde that the determination of magnitude from
is considerably more inaccurate than that of parallax from magftr"
tude. The asaociation has indeed fallen below anything yet dealt
with in the present paper, Tbe inequality of the two values of 17
shows that our di?*tribution is very far from Gaussian. It is clBtf_
that in these circumstances contingency is the only method
which we call approach a unique measure of the relationship <
paraliax and magnitude, and accordingly the following contingent
table has been prepared ^'onnecting the two characters
gives UB
C, = '32 ( ± -05).
In the previous memoir for NewcomVs 72 stars we had
Ci = "4i (±-o8).
r
Table IX.
■
r
Ooutingenn/ .
Mmjnittule and Faralloj'.
1
Paraltojr,
1^
Uft^ltiiae.
-o'"i3 to
-o"*o6 to o''*ooto
o'-'oo. o"*o6.
o"*o7 10
6"* I 3.
Below J^95t
...
4 3
7
2 16
3-95 104-95
« 5
6
f 13
4*95 t" 5*95
4 S
4
4 ^
5*95 to 6 '95
2
9 >3
8
3 i5
6-95 to 7*95
3
6 21
[J
J 43
Above 7'9S:t
3
S 16
8
5 1^
Tot&Ia
i6i:
7 29 66 44 17
• We would i>liice considerable «tr*r«« on this, because much of the in
presaiv^ncss of the above table, both visuallv -*nd wlieti redoeed Duroefic»||^ I
Ilea on tbe place assigned to the group of largest negative p«nilUx*«v ^** 1
their in«nii raagriitn<itj 7 -34. Now this conMistft of only 7 iUra» and thtip***
aiiguitudc rniijr he Tnfr«rly indicitiive of greater arrorv ai'ising with bati^
in.
t With the cxreption of three ntars, 2*3 20, and 2*8, all w«re tbow l^g"
t All below 9, with tho exception of one star 9.
Mar. 1908. CorrclvUions of Stellar Characters.
433
Thus practically tb^ previous result and the present for the
^ntingoncy agree within the limits of the probable error of the
iffereuce. Ftirtber, the contiiig*»iicy and correhition riitio results
are also in close agreement, assuming we class by magnitude. Now
I the series we are considering at present is very different from the
bwlier series : that aeries contained 20 stars brighter than ma^mi-
pde 2, while the present contains none. It contained only 7 stars
kbove 7 '95, while the present series contains 36. It is perfectly
porrect that in both cases stars have been frequently selected
because they had large proper motions, and so may have Urge
parallaxes. But does this really affect the argument that there is
comparatively small relationship b^itween magnitude and parallax?
In order to do so, it must mean that the partial correlation is
much lower than tlie a hsohite correlation, and this can only hapj^i^n
if the correlation between magnitude and proper motion is very
I high. To this iKJint we now turn, because some criticism of the
bftflier paper has been made on this ground.
[ (ii) Magnitude and Proper Motion. — Any amount of material
IB fortbcomin^S of course, on ihis point, but it seemed advisable
to work with the best available proper motions. Accordingly w©
, used the Cafalofpte of 627 Frijiripal Sfan-ianf ^Stars, 1904, by Lewis
^^Boss. Omitting variables, we had 305 stars with positive, 317 with
^Biegative, proper mtitions in R.A> ^ There were 195 stars with
^Bpositive and 426 stars with negative proper motion in declinatiom
^n'here was no necessity to separate these groups, as we are dealing
[ only w'ith the size and not sign of ihe proper motions, but it was
I desirable to se^mrate into random groups in order to test the
steadiness of the coefficients, and the positive and negative groups
I served as well as any others.
Four tables of contingency were formed, given as X*, XI., XI T, and
XI 1 1, below. We owe the working of the contingency coefficients of
the first two tables to Mr. A. M. Prit chard, of the Hurtley Uni*
^■rersity College, JSouihampton, and the lust two to Dr. Alice Lee.
^f The statistical const^ints reached are hs follows : —
JlatoroorPru{i«r Mottan.
Mvah MagfilUde.
iti MftKiif tilde.
ConUngeticy.
PoMttveiQR.A.
3-63±-05
ri6±'03
■30(±*04)
Kegatiy*? in FLA,
379±04
I t2±"03
•38(^^04)
Positive in Deoliuntion
3*8S±-o6
i*t6±-04
•36(±'05)
■fugitive iu Dedination
3 72 i '04
ro8±*02
*23(=t'03)
i
The mean degree of relationship hetween proper motion and
tnagnitnde is accordingly '32.
In Diagrams HI. and IV. the means of arrays of magnitude for
given classes nf proper motii>n are plotted ; it wtll he seen at once
how little influence of an orderly kind a selection of stars by proper
motions would ha%'e on their magnitude.
One star out of the 621 noo'variables has been overlook^ vtv \»NJV«x^
le proper rootious iu R.A. Hlivsin group of maguitude ;^ $-vv
434
Miss Gibson and Prof, Pearson, On the LXmLJ,
S S ^ » 8 8 8
MAGNITUDE
S S
\
MAOHiTVJOl.
MAONITUOI
^^^^^W^^l
r 1908,
Corr$latio7is 0/ Stellar Characters, 435 ^^|
Boss, of course, deals only with a selecter! group of atarf^, but we ^^M
'test the result more or leas closfly uii tlie Yale oliserviitiona, ^^H
kh give total proper motioits for ma;4nituile clits^e.s, ami niagjti- ^^B
ks for tutiil proper motion classes. We owe to Dr. Lee the ^^M
|Blation ratios for the two cases ; they are respt*ctively — ^^H
Idalbn ratio : proper motions for magnitude classes, ^ = '43 ± 04 ^^M
li, ,, magnitudes for proper motioti classes, t^ == '22 ± ^05 ^^M
ffhe average relationship between the two charactera is thus ^^B
p about '33. Thus we may safuly conclude thut the deviation ^^M
L
1
Taulk
X.
- ■
' Mipjnitude and P
rfj^?^^" Mot
tVm m /?.J, (^ pontive), ^^M
Majjnlturle.
■
I^«th»n ^.^^^
1-4. 3st0 3>
3'5t0 4 4.
45tos-4- '^'vS:' Tow.. H
lo u
2 9
19
21
^H
io 24
2 3
8
23
^H
» 36
2
5
12
^1
|49
t 3
7
11
^1
P«
I 4
8
Ji
^1
M> 149
1 7
S
15
H
m*\ over
Totalt^
3 5
7
19
^1
10 33
62
132
J03 ^H
TMiLE
XI
I
Magnitiuie atid Pr
y/;er Motion in E.A. (ft negative), ^^H
]
Mftgnltudo.
^H
-*»f|'"^" r5tu.
♦ JSt«j'4.
JSt^^-t-*- 4
'X:^ Totnl,. H
i II
I 7
19
20
^H
^M
I
12
19
^H
• 36
2 3
12
10
^H
} 49
2
7
12
^1
t 99
2
H
29
^H
U49
I
5
15
^1
hd over
1 Totals
3 6
11
21
^1
6 32
So
126
^\i ^H
43^ Mi$8 Gibson and Prof. Fearton, On the LXvni 5,
Table XII.
Magniiwle and Proper Motion in DeeHnaiion (y! jwsUive),
Magnitade.
^,f^ ,5 to 2-4. a-5t0 3-4. 3-5 to 4-4. 4*5 to 54. *'*;S!" '^
oto 15 2 9 16 ao 7 • 7 . 61
16 to 29 ... I 7 15 to 4 37
30 to 49 ... 2 9 II 32^
50 to 99 ... ... 6 II 5 3 ^S
100 to 199 ... I 6 12 4 I 24
200 ami over 2 ... 4 II 3 I 21
Totals 4 13 48 80 32 18 195
Table XIII.
Mwinitude and Proper Motion in Declination (fi negatire).
Magnitude.
1.688 than
»'5.
1*5 to ?-4.
25 to 34.
rS t0 4*4.
45 to 5-4.
55 and
over.
Tot^
0 to
15
3
10
20
40
20
3
96
16 to
29
2
8
15
29
18
I
73
30 to
49
2
4
26
31
15
3
81
50 to
99
I
5
13
39
21
3
82
100 to
199
2
10
II
18
6
2
49
200 HIK
1 over 2
5
9
22
7
...
45
Totals 12 42 94 179 87 12 426
from irnlependent variation in the distribution of magnitude and
proper motion is not very far from -35. It is therefore possibly
slightly hi<^her than the value found for magnitude and parallax,
which is about -30. It will, we think, be evident that a selection
by pro])fr motions would have comparatively small effect in modi-
fying tho n»lation found between magnitude and parallax. Som»*
rough estimate of the order of the change can be formed by con-
sidering what would be the absolute coefficient of correlation ^^
sultini^ from a partial coefficient of '30 obtained by selecting stare
of a single proper motion only ; this will probably give an upper
limit. We have
p = ^12 ~ 35_^5-g^
■lar. 1
ar. 1908. Coi'relaiiowi 0/ Stellar Charad^n^
437
r^ is the cotreUtion between proper motion aori parallait,
Jn the former paper for the 72 stars this was found to be about 4
(p. 449); from the Yale data (see below) it is under "38. Assum-
ing it='3S, and putting fi^^—'io^ we deduce rj2 = '39, say. We
think, therefore, we may safely assert that the relationship Ijtjtween
parallax and magnitude, if no selection by proper motion-^ had taken
^kace^ is not likely to prove as great as '4, and probably lies oon-
HUerably nndor this valuo.
• We wouM fittL,^geat, fcherefcue, that the lowness of the magnitude
^wid parallax result obtained in the former paper is not due to any
^fcecial selection of parallax stars by their proper motions. This
^ould not largely influence the relationship of magiiitud© and
parallax I because proper motion is only moderately correlated with
parallax^ and still le^s with niagnittide.
(iii) Before we leave the subject of the correlation of magnitude
aod proper motion, it is worth while noting that it has also been
investigated in an entirely different manner. In the above
inquiry we have found the correlation ratio for the total jiroper
motion and the magnitude iti tbe case of the YaJe ^^tars ; we have
further calculated the contingency coefficients between two sets of
jpoups of magnitude aiul proper motion in R,A. and declination
^BBpectiifely from the Bnss Catalogue stars. But for other purposes
^de proper motion in declination, ^', and the piroper motion per-
pendicular to a declination circl<*» ^ cus S, bad been found and
^jkken out. Now we are concerned only with the size of the proper
^H|oti«>ns, and m>t their sense, at present. We divided, however, oiar
^SiLta intii two halves for the purpose uf checking resnlts. The
(itars from the equator to the North Pole, 29S in nundjer,* have
lieen taken in one group, and those from the equator to the South
Pole, ^2^ in number, in a second.
Further^ to avoid lengthy analysis, we dealt separately with
proper motion parallel to the decliimtion circle (fi!) and per-
pendicular to it (/x cos h). Thus we have four series to discuss.
^Tbe clflssihcations of ma^^nitude wore an follows: under i'5, J '5
^■id under 2*5, 2*5 and uivder 35,. . . 6*5 and over The propter
^botions are of such a wide niriL^e that no grouping was adopted,
but the means and standard deviations found by thi^ labonous
processes of adding and of squaring. No stars were omitted^
although one is sorely tem|>trd to omit thoee two or three of
^^norrnal proper motions, as undoubtedly abnormal on any proba-
^Blity tent. Any selection of this or tiny other kind rau.st, however,
^B for our present purpose dangerous, and accord tngiy we have
^■owed equal weight to all the available stars in Boss's listf
^H The following results were obtained : —
• 6 variable stars in Bosses CatAloguo wer« r>f necessity omitte<h
t It may he of inter&tt to n«>ti' thnt, working liy eorriflatinn methods on the
3oa«ftUiR I firul for the apei of the Sijo*m wny i{.A.-275*, B^+aS^^, but
%.h^ reqtiiait* condition;! for a random ilistri^mtiitn are hoptfleH&\>f \\ivlvx\^^vA.
*Xhe correlittions directly provide n o^eMiDd of nppro^ichVng t\sii '^vAA^ia. «sl
■3ialtiplt« <* rifts which I hope to deal with later. — K. P.
438 Miss Gibson and Prof. Pearson, On the LXVIIL 5,
Table XIV.
Northern Stars.
Magnitude.
No.
m'.
fioo«a.
Under i $
9
372-44
2f4'33
I'S to 2-4
25
71*08
80*00
2-5 to 34
61
7115
6459
3'5 to 44
137
103-35
76*85
4-5 to 5-4
54
9370
94*81
55 to 6-4
9
66*22
85*00
65 and over
3
55-33
50'33
AllsUra
298
0883
81*99
The complete constants for the whole of the 298 stars are—
Mean fi Standard deviation of /jl
98*83 ±7'73. 196*85 ±5*47.
Mean /x cos 8 Standard deviation of fi cos S
81*99 ±6*66. 170*40 ±4*71.
Table XV.
Southern Stars.
Magnitude. No. fi'. ticosi.
Under 1*5 7 44*29 48*86
1-5 to 2-4 30 7860 5593
2-5 to3'4 81 75-80 58-28
3*5 104-4 122 loi-ii 72*36
4*5 to 5-4 65 119-51 78*05
5*5 to 6-4 13 47*15 35*00
6*5 and over 5 22*40 17*20
All stai-s 323 9176 65-58
The com[)lete constants for tho whole of the 323 stars are —
Mean fx Standard deviation of fi
9r76±8-87. 236*33±6-27.
Mewn fjL cos 8 Standard deviation of ft cos 5
65-58 ± 605. 161 -31 ± 4'28.
At first sight it might appear tliat the northern group of stars
had a larger proper motion than, the southern, hut, considering
the probable errors, it is donbtful whether any stress can be laid
on this. Thus we have for southern and northern groups —
Difrerence of /x' = 7*07 ±11*77
Difference of /I cos 8 . . .= 16*41 ± 9*00
Difference of S. D.'s of / . = 38*48 ± 8*32
Dif[nrence ol Vn. \Yv. o\ \i,^!,c>^E = 9'i8± 6*36
atioTii J
Only m the third case is the difference more lbno twice its
probable erroiv atid it may ju«*t be that proj^er miflioris in
declination in the sontheru beniisphnre are miir« variable than in
the northern, but miieh larger numbers would have to b^ uaed
really to demonstrate this.
If, on the other hand, we compare the results for proper motion
along aud perpendicular to the declination circle^ we have —
Northern Stars :
lHff«rence of raean fjt! and mean fxcosS = 16*84 ± lo'ao
Difference of S. D. o( fi and S. D. of /i cos 5 — 27-36 ± 7*22
Southeni Starn :
Difference of mean fi and mean /acos S = 26t8± 1074
Did'erence of S. D. of f/ and 8. D. of /i. cos S= 75-02 ± 7*59
Three of these differences are more thim twice tbeir probable
errors; and looking at the values an a wbok% it seems not improbable
that prt»per motion in the declination circle is larger and more
variable than proper motion perpendicular to it The point
deserves fuller consideration, especially in its relation t-o the
position of the apex of the Sun's way. We shall return to the
matter later, from another RtaDdjmint
If we now examine the means of the magnitude arrays, we
notice at once some very remarkable points. Regarding the mean
values of both proper motion components, we note that, with one
exception to be discussed beiow^, the dei^iations from the mean
values of the means of the arrays are small as compared to the
corresponding variabilities, but these deviations are remarkably
regular.
Taking the southern stnrs aa typical, we find (Diagram V.}a con-
tinuous riae in projier nif^tion for both components until stars of
about 4*5 raa^itude, then the proper motion falls again and becomes
stilt an»aller for tbe faintest stars* The same rule is ap[mrent in the
northern stars also, except that in the group of exlrt-mely bright
stars we have a very largo proper motion, whicli agaiii» however,
when we remember aize of mean and 8, D., is not so big as it
appears. Stiil it is df^Bnitely Hignilicant^ and mark^ tbe group of
brigbtest northern stars as significiintiy different from the correspond-
ing group of southern stars. The Diagram V, will bring out the
remarkable charactt r of these magnitude and proper motion curves.
If the determtniitg link between magnitude and pniper motion
were parallax^ surely we might anticipate a uniformly decreasing
proper motion with increasing magiiitnde? Yet we see in all four
cases the same plienomenon— the lr>w value of proper mution for the
stars of 1*5 to 3*5 magnitndej its growth to a maximnm^ and then
its ultimate fall It is true the variations are small, but their
comparative regularity is very great It is difficult to see what
apecial selection of th^^se standard stars could have led to this
result It is one that will be tested on much larger masses of
material, but Boss's Gatolo^nm was selected on accounl ol \.\i^ Vx-^
440
Mi$8 Gibson and Prof. Pearson, On the ixvm, 5,
I -2
V
Jn
\
\
Z
f§
\
^
3
\
1
1^
1
0
••
\
1
!
k
i
flB
i\
CE
\
41
1 \
&
i
1 ' >
^
4
§
I.
. 3*
5r
r T
lar. 1908. Correlations of Stellar Characters.
44*
aicuracy of hiw results and the maiuigeable number of stars prorideil,
%Ve way look at the point from a second aspecL The lines of
means are curved, and accordifigly the coefBcieut of correliition is
not the proper measure of the association between magnitude and
proper motinn. It is provided by the correlation i-atio jj. We
have
Northern Stare :
Correlation ratio of magnitude and ft' 17 ^ '2$ ± 04
^co«S, T7 = 'i5±*04
Southern Stars :
Correlation ratio of magnitude and fjL tj- 'og ± ^04
,1 „ f, fi^cm^ i? = -o8±'04
It will thus bo seen that the amount of cnrrektton even for the
northern stars is only small. Working on the 173 Btars of the
Yale raemoir, we have found tlie correlation ratio for proper motion
iti arrays of limited magnitude ; it is :
Comidering that the Yalo stars are all northern stars, but that
this case the iotal proper motion has been taken, and not tbe
component proper motions, we see that the Eigrecment, notwithstand-
ing the wide diflerence of material, is excellent, — well witliin the
limits of the probable errors.
While the correlation is alight for the northern stars, it is practi-
cally of little or no service, as far as selection goes^ for the southern,
stars, or we must conclude tliat^ —
A selection of siara hy their proper motions m%^ have very little
influence intleed on tite relatioH Miceen magrntnde ami parallcu.
It will accordingly require some very stringent torm of iuvesti-
gation to demonstrate that the form of the parallax magnitude
curve can he sensibly influenced by a proper motion selection.
As far 88 the present data extends, we would venture to suggest,
therefore, that the criticism that the stars dealt with are specially
selected is not really a vatid one, for this selection would not largely
influence the relationship of magnitude and parallax. We must
conclude that the present results confirm the early ones, namely,'
~ ey show that magnitude is a quantity much more closely associated
ith chemical condition (spectral class) than with distance; indeed,
the association with colour is almost as great as the aaso^^iation
with distance.
(6) Correlations with Parallax. — We have alreatly dealt witli the
iation between parallax and magnitude, colour atid spectral class
422, 423, 42S, and 432). The remaining feature is proper
otion. This is provided by the Yale obserTations. Accepting the
authors' proper motion classes, the arrays of parallax give ub (Table L),
Correlation riitio, p&rall&zea for proper motiou classcSj* iy= •36d:'05
• Tlu» result 18 for totnl proper motion in a great circle, but whether we
Qse component proper njo lions in arcs or ngmin the valuaa in R,A, and ^
kes htit little difTercnce in the conetation values.
442
Mus Qihson and Prof. Pearson, On th€ LXTI
and again (Ttible IIL),
Corieljitiou ratia, proper motions for pursllax claase^ ^= '5Sdk*04
The previous work ou the 72 stara ^ave —
OorreUtion coeflident, proper motion in R,A> and pwralUx, r='44± c«
,, ,, ,^ in dtcliniktumainl {larallax, r='4idb"07
Considering the aize uf tlie prohablw errors, the present resulii
are reasniiably in accordance with the former, or we may take it
that the correl itiiJti between j^mrallax and prof^ter motioa is not far
from linear, and of magnitude about '40. Thua we have iLe
following scheme of relatiouship: —
Parallax and proper motion ♦ , . 38
Paniliiix ajid HjHaUral class .... 36
Parnliax and magnitude .... 'jo
Thus, while the ili&tJtnce of a star is seiiaibly relatpd to it^ proper'
motion, thi» relitionship u nnt really more significant than the
reJjition to specti^el class- and it is quite possible that if the sjicctfa
were aasorled according to paralhix, it would be fiosaible to furm
spectral cittegorit's which would ^ive a far higher associatioo
l>etweetj parullax and apr*ctral class th;m between the former nntl
pro[)er rnolion. The parallax stars have not yet been dealt with
as to colour.
We Imve seen that, on the basis of the Yale stars, the cotrelft*
thm between parallax and proper mntiuu is nearly linear. It
accordin^;ly of conaidtTable interest to obtain the line giving ll
njean [>ar^llax tt^ for a group of stars with a ^iven totaJ pro|
motion p in a great circle. Let tF be the mean pandlax. /' the
mean prii[Kjr motion, c^ the standard deviation in parallax, «r^ the
standard dfvtation in jumper motion of ilie whole gronp ai the
Yale stars. Then we have— ~
# == o"*o46o ± '0035 » ^1^ ^ 0*0664 ± *oo2 5
jJ = o"*6765±*o205, cr^ ==o*'j997±'0205
we may take r = 17^^ = •4006,
Thus ir«-# = ^^-(p-p),
or, in numbers, 7r„, = o'''ooio-«-o'o666p,
If we neglect the ywwj^" ^^ negligiblti in the case of paralli
we conclude that tlie mean parallax of an array of stars of gi**«Q
proper niMtiou is one- fifteenth of that prop^^r mtition.* This »
absolutely identical with the statement made by Neweomb, largely
on theoretical grounds : t
* The 70 odd ttam dealt with in the earlier mcmoiri if we i-ompare tottl
proper mi>titii* in a great ctrcli^ and pnr^llax, givo the correUlion of jiarallas
and prN|wr motion aM *58 and the r- greaaion uotllicieut iV* This la a« cloar to
^ as we couUI expect from the m^vieiial.
t The Attrotiojni'eat Journal J vol. xxii. p. 1 69, 190a.
1
[ar 1908. CarrelfUions of Stellar Characier$,
443
'That 18, if we measure the [mrallaxes of all the stare having a
given proper motion, we may expect the raean result to be about
^ of the proper mt^tion."
The interesting point of this reaalt is that the value whi€li was
tjiveu on theoretical grounds by a brilliant astronomer, and appears
tben to have passted unquestioned, should have met with disapproval
when actually found from observation.^ by the statistician. As we
have just indicated, Newcoinb's yY ^^ ^J^*^ HuIg more or less than our
statement that the correlation between proper motion and parallax
equals '4. Newcomb's
mean w = 0*064/^,
where /* = our p, is only a regression line without the constant term,
wliich in this case, if it be not actually zero» is certainly very small.
As far, then, as our reduction of the Yale data goes, it tends to
confirm Newcomb*a theory of stellar distribution ; it also shows that
i>ur values of the parallax and proper motion correlation and of
> the ptirallax and proper motion standard deviations were reasonable
L values,
■k We find froin the Yale data that the mean proper motion p^^
^nfor stars of a given parallax w is given by the regression hue
[ P^^ 03654 + 2^1 1 4^-
This does not agree with Newcomb*8 relation (loc. cit^ p, 168), and,
I of course, only applies to the range i^f stars in the Yale data. These,
however, do nut ap(»ear to satisfy Newcomb's equation,
(7) Parallactic Motion, — Still another method of approaching
I the parallax and proper motion correlation may be delluced from the
Sun's motion. Let v = the velocity of the Snn, p the distance of
a given star, and * =^ the index v/p. Then, if ir be the parallax, p
the proper motion of the star, and a the radius of the Earth's orbit,
""'■
rhere w and f may be measured in seconds of angle.
Since v/a is a constant, we have
or the correlation of parallax and proper motion is the same as the
correlation of this index and proper ujotion. Suppose that cr,
^rgMddents the standard deviation of any variable d*, then
¥
^ip^il<^p= - ^ T^jP-wt^p'
Now T^J<rj, = m is the slope of the best fittirsg line to the curve In
which the mean value of t is plotted to a given proper motion class
of stars.
The value of m has not been found at present because of the
444
Miss Gribson and Prof. Pearson, On the LXVin. 5,
labour of determining t for small groaps of proper motions, bat
some idea of its value for large groupings of proper motions can be
obtained from the papers by Oscar Stumpe* and by Messrs. Dyson
and Thackeray.t These give us —
Table XVI.
Dyson and Thackeratj,
Stumpe.
No. of
Stars.
Proper ^lotion.
Proper Motion.
Valae of i.
Group.
2885 o" -00 too" -05
800 o" 05 too" 10
316 0"'I0t0 0"'20
163 o" '20 and over o"-3i2 o"*25i
Presumed
Mean.
o"'025 o"oi7
o"o75 o"o45
o"i50 o"o84
Group.
Actual
Mean.
Value of.-. ^
o*'*i6too"'32 o"-23 o"'i40 551
o**32too"'64 o"*43 ©"•295 340
o''-64toi"-28 o"85 o"-6o8 105
i''-28audover 2"-39 2" "057 58
It will be seen that Stumpe worked with stars of far larger
propter motion than Messrs. Dyson and Thackeray. We have only
be»Mi able to give the presumed means in the case of the first set of
stars as the actual values of the total proper motion in a great circle
are not tabled. Assuming the means to approximate to the valaes
given, we find for the first series
and for the second series
w=7395
7^1= -8767
nsing the method of least squares to determine m = r<,,crj/a"p, — 1>.
the correlation process. It will be seen at once that the two sets of
observations give no close agreement ; the ranges of stars dealt with
are very difterent.| If we take m = '88 we find
o-ir
= •88"
* Astronomisrhe Kachrichten^ Bd. 125, ss. 385-426.
t Monthly Notices^ vol. Ixv. pp. 429.
t The graph of the Dysou-Thackeray and Stumpe data shows that their
first three points form a more or less continuous curve with his ft»ur points,
but that if t»ur estimation of the mean proper nmtioii of the stars above o'*ao
proj»er motion be at all correct, the fourth Dyson Thackeray point does not lie
on this continuous curve. This is possibly due to a considerable under-
estimation of the mean value of the ** over o '21 " group. If we omitted this
fourth point, wo shouUl get an initid slope mo to the regression curve of less
than '5, a value considerably nearer that required to reconcile the parallax
and Sun's motion observations discussed below. The actual regression Unes
*'« = 7395 P - o'''oo4 (Dyson -Thackeray)
t;,i = '8767^- o" '074 (Stumpe)
differ significantly. This is due to the fact that the regression Mrve is ftr
ft-om linear.
Mar 1908. Catrelatians of Stellar Charad&ta.
445
iNow if V be 16 miles per second rja -5*4 about, and accordingly
r,ri-— = *i6= about.
This is very different front the /,, wliicb lias been given in the
present int5moir nm\ by Kewconib. It may be said that this is
due tu the value found U*t tiie correliition of parallax and jiroper
motion being too flmall. We ran examine this as ftdlowB :- —
Evexy correlation coe^inient must be less tfian unity. Hence
1 w%f\\
60-^
^
With the al-Hjs^e values^ m\\^% be letis than unity. Now the varia-
bility of proper motion is fairly well known. We tind' it to be
o"*6 for Sturupe'rf 1054 titara. It \a o"'4 for tlie Yale stars, I-et
U9 put it 0" 5, then
I
t2cr*
and accordingly o-^ nmst be >jV or >'o85. The Yale resnltts
give rr^ = *o66* We thub reach an impressible value for the
I correlation of parallax and proper motion. We need o-^ to be
sbout o"'2 tt> get thi8 correlation a reasonable value. The curious
part «l>out this result is this : If *^ be the error in determining the
irue purallax tt', the uhsei ved parallax tt = ir' ± e, and accordingly
The
th«
iTn"
/-4-n-,^
bere cannot be a doubt that <t, is lar^e^ thus we should expect
iie Drue value of variability in parallax to be considerably le^ than
the observed value, owing to the liability of parallax to error.
The only suggestions that we note fur overcoming the difficulty
(i) That a much higher value must be attributed to the velocity
of the Sun thati is uauiilly adt»pted. Si>ectroBeopic determinations,
ihowever, indicate a lower value.
(li) w obsen-ed is largely a dilierential parallax =ir2 — irp say.
ence
*r»=' = «r^/-*-o-^j
2_ .
wltere 1*12 is the correlation lietween the component parallaxes.
If Ty^ were zero, then again xt„ is aenaibly larger than the true
value tr^.j or o-^, ; but if the component parallaxes were highly
correlated, *>. if the tw<j stars observed were about the same
distance from the Sun, notwith:standing their differences of magni-
tude or proper motion^ then we should have
rr.' possibly nearer {a^^.^ -o-^x)^ *^han to <r,ri ' + <rir,/ ;
in other worde the observed variability of parallax might be much
in defect* This is the only suggeBtion we can make to account for
(Tir being sensibly leas than the true value o! ftie ^.a^xw^X^, \V
446
MuB Oibton and Prof. P«armm, On ike lxviil 5,
\
\
\
\
\
\
\
\
\
\
\
\
\
o o
\
\
\
\
\
\
\
\
\
t:
-T 1 r-
X 5 2
o\
\>
-I — I I
2 22
"T 1 1 r-
*» *■ •! •»
6 4 o o
ValxK' of Index i.
1
Mar. 1908. Correlations of Stdlar Characters,
447
mYolY88 the assumption that near stars on which the diflferential
parallax has been worked are really near each other,
(iii) If we Btudy the graph (Diagram VI,) of the Dyson-
Thackeray and Stumpe observations, we see that the three points of
the former invefltigators and the first of the latter fall nearly on a
straight line of sloije about '5. If we were to give m its initial valne
— *45, say^ an increase of speed in the Sun to about 20 miles per
ftecond wonld render the two results aceordant. The assumption
here made is that the stars with a large proper motion belong
possibly to a different system to those with the smalleBt proper
motiDn?^ and ought not to be used to determine nu
(iv) Lastly, it is possible that among the stars used by Dyson
und Thackeray and by Oscar Btnmpe, there are many with con-
»iderably higher parallaxes than appear in the small samples for
which parallax has at pi^esent been determined^ and ttiat thus the
variability of parallax will ultimately be fonnd to exceed the values
so far determined. This must denote the existence of a comiderable
number of really lai^e 'parallaxes hitherto undiscovered, for we
I most not forget that the present values of parallax have, in all
probability, a considerably exaggerated variability due to obeerva-
L tional error.
^K From the statistical standpoint, therefore, the determination of
^H considerable numbers of additional paralliixes seems to be a rather
^V pressing problem. It is not uiireaj^onable tu suggest that there is
^m aomethitig that needs reconciling in the values determined for the
I index i and the value usually assumed for the Sun's motion in
^^Bpace.
^B (8) Ccm'^otkms with Proper Motion, — Sufficient material
^^exists for finding the association, if any, between proper motion
and colour, but we have not yet had the opportunity of dealing
with it. The fact that the correlation ratio for spectral classes is
as high as '39 would iiulicate that colour and proper motion may
weU be sensibly related. Magnitude and parallax ctirrelations
with pruper motion have been dealt with above. Accordingly, we
have approximately the following system : —
Proper Motion and Pai-allax
Proper Motion and 8pectral Cla^s
Proper Motion and Magnitude .
•39
•35
(9) Conclusions^ ^*y^hM^ wo are fully aware how badly the
mere statistician may stumble in dealing with astronomica.1 data,
we still think that the general relationships shown by the statistical
correlation constants may be of value t-o astronomers. They serve
to Indicate the directions in which closer relationships may be
found, and where, possibly, more effective classifications may bo
made. The values given in the accompanying general scheme are
certainly not fiiml, but we do not think that they give at all mis-
leading values, or valnes really far from the truth. There t%i3a«Lm%
much to be done, and the scheme indicates some ol t\i^ \ftX>Oka& ^\i\Ot\
448 On the. CarrekUians of Stellar CharaeUrs. LXvni. 5:
yet remain to be found. While parallax touches one element only
of position, direction as indicated by the usual stellar co-ordinates is
a second ; this " position " in the narrower sense has not been dis-
cussed in the present paper. We have purposely included it in the
table, to indicate that we have not overlooked those position co^
relation problems to which the astronomer is now turning, and to
which approach is possible from more than one direction. We
hope later to deal with the question of correlation of stellar
characters and position. Taken as a whole, we are, we think,
compelled to conclude that the associations between parallax,
proper motion, and magnitude are considerably leas than we should
anticipate if we hypothecated any approach to a uniform distribu-
tion of stars with a system of random velocities throughout space.
The oxistonce of correlations between colour and spectml daas, not
only with magnitude, but with parallax and proper motion, euggeste,
if it does not demonstrate, that chemical constitution and lumin-
osity are dependent in some manner not only on spatial distribution,
but on velocity in space.
Table XVII.
Correlation of Stellar Characferii.
Colimr. Spectral Class. Magnitude. Parallax. ^SSSa ^^**°*^
Colour
I -00
71
•30
?
? ?
Spectral class
71
roc
•69 (-43. •54*)
•36
•36 ?
Magnitude
•30
•69 (-43, -54*)
roc
•30
•35 ?
Parallax
?
•36
•30
I"00
•39 ?
Proper motion
?
•36
•35
*39
roo ?
Position
?
p
?
?
? ro
* According to Pickering's and Lockyer's classifieations respectively.
Kii'atum in Annual Report.
Vol. Ixviii. p. 298, line 5, for o"'i read o"'oi.
MONTHLY NOTICES
OF THE
ROYAL ASTRONOMICAL SOCIETY.
ToL. LXVlir.
April io. igo8.
No. 6
f
H. F. Newali^ Esq., PsiaiDENT, in the Chair.
John Bullock, M.A., 78 Airedale Avenue, Chiswkk, W* ;
Arthur Brunei Chatwootl, B^Sc, Assoc. M. I nsLC.E.^ Astronomer
to the Government of H.H. The Nizauj, Hyderabad, Deccan,
India ;
F. K. Cripps, Esq,, 22 Hornsey Riae Gardens, N. ;
Henry Zoiich Darrah, Eaq,, C,8.I, Allahabad, U.P., India;
Charles Gaskell Falkiier, Esq., M,A*, I re ton Bank, Rusholme,
Maiifhester ;
Harold I^Iorris-Airey, Esq., M,Sc., Armstroi^g College, New-
castle-uponTyn© ; and
Henry William Moore, B»A., New University Club, St. James's
Street, and 64 Curzon Street , May fair, W.,
irere balloted for and duly elected Fellows of the Society.
The following candidates were proposed for election as Fellows
)f the Society, the names of the propoaers from personal knowledge
aeing appended : —
Hugh Cameron Campbell, Science Department^ StirgeoDS* Hall,
Edinburgh {proposed by Alex. D. Eussell); and
Arthur Mackretb Deane, M. A., Canon of Chichester, Ferring
Vicarage, Worthing, 8ussei (proposed by B\ J, W. Crowe).
I
The following were proposed by the Council as Associatos of
he Society :—
Benjamin B-ullaud, Director of the Observatory, Paris;
C. V, L. Charlier, Director of the Observatory^ Luud, ^^^^^w \
450 Dt, E, W. Brawn, Lunar Inequalities due to Lxvm. 6,
£. B. Frost, Director of the Yerkes Observatory, Williams Bay,
Wisconsin, U.S.A. ;
The Rev. J. G. Hagen, S.J., Director of the Vatican Observa-
tory, Rome ; and
Johannes Franz Hartmann, Astrophysical Observatory, Potsdam,
Germany.
Seventy-one presents were announced as having been received
since the last meeting, including, amongst others : —
J. G. Bohn, die Kunst-Uhren auf der K.-K, Sternwarte zu Prag,
presented by the Prague Observatory ; The History of the
Geological Society of London, by H. B. Woodward, presented by
the Society.
— ;;^Sixteen charts of the Astrographic Chart of the heaven^
presented by the Royal Observatory, Greenwich.
On the Lunar Inequalities due to the Motion of the Ecliptic and the
i. Figure of the Earth. By Ernest W. Brown, Sc.D., F.R.S.
r^ I. The general disturbing function for the moti<m of the
ecliptic. — Let ^j, 0^, 0^ be the angular velocities of a set of
moving rectangular axes about themselves ; x, ij, z the co-ordinate? ;
w, r, to the velocities of a particle with respect to these axes ; and
let F be the force function divided by the mass of the particle.
Then the equations of motion are given by
du /I . /) cF
dt ^ ^ dx'
dv /) . /, aF
where
dw /) . /I 8F
Put
where
Apr* 1908. Motion of Ecliptic mid Figure of the Earth. 451
then, if we assume that ^^, 0^, $^ are independent of ar, y, 2, «» v,
f«?, we may write the equations of motion in the canonical form,
dt ~ a^ *
dr^ en
(ho 0H
If R be neglected, the etiuations become of the same form as
for fixed axes ; hence R is the diBturbiiig function for the motions
of the axe«. These motions are so small that w© can neglect
squares and higher products of the terms in R, and therefore can
treat K as a diaturbrng function of the same nature as that used
for ordinary planetary perturhations.
In order to obtain B^, 0^, 6^ we put t for the inclination of the
moving ecliptic (iri/ plane) to the fixed ecliptic (that of rSso'o),
T for the longitude of the node on the fixed ecii|Ttic, L for the
angle which the zjt plane makes with the plane containing the
poles of the fixed and moving ecliptics* Then, by Euler'a
equations,
&i = -- sin L - sm t cos L^r j
at at
2" 77 ^^^ L + 8tu t am L-y ,
fl dr . r/L
\!& Lb is at our disposal, we so take it that the distances of the
origins of reckoning cm the fixed and moving ecliptics from their
common node are the same, thiit is, so that L=90° — t. l*he
moving axis of x therefore passes through a " departure point/'
When we are given the values of 1', r in terms of the time^ we
ha?e the material necessary for the solution of the problem^
2* As a matter of fact, t", -- , -^ are so small that their squares
dt dt
Emay be neglected. We can therefore put
sin «" = »', cos f* = 1 , T =^ const. ^
^452 i'n E. W, Brown, Lunar* h%eqwdUi$s due to ixvni
Whence
E = -J^ < {wy - vs) cos r-f («3 - wx) «m t V ,
or.imoe u differs from ^ by a quantity of the same order as C, el
« dt" / / dz dy\ ( dz dx\ . I
dim
= j^Q. suppose.
The meth c^d of the variation of arbitrary constants permitB
to substitute in Q tht^ values of a?, //, 5, and of their derivatives in
terms of the arbitrary constants and the time as loutid in the
solation of the main problem of the lunar theory. These yalttes
can be obtained directly from the results which I have given in ray
papers in the Mem(drs of the Society on this subject,
3. The value of % is of the form
where jj is a constant and P a sum of periodic tfttms
arguments depen^l on tho.«^e of the motions of the Earth
planets. The latter torms have generally been neglected^ \
shall show that they give rise to a few terms which are not
insensible. At this sta^^e the question arises as to what movii
ecliptic we shall refer the motion of the Moon. We may refer it
the actual ecliptic, in which case I have found by calculation tl
P gives rise to a number of primary terms of short period and
few of long ymriod. Or we may refer it to the viean ecUptic^
put P = o in the above formulse ; but if we do so, it will
necessary to introduce the latitude of the Sun above this mean
ecliptic into F. With this latter method, I have found that dl
the primary short -period terms practically disappear and the long-
period terms have rather smaller coetiicients than with the former
plane of reference,
1 therefore adopt the mean ecliptic together with the one or t
Very minute terms which are of long period relative to that of
Moon's node, and which do not then give rise to any terms in tbe
Moon's co-ordinates. Hence, for the computation, we may
4. The principal part of the force function for the MooqII
motion under the influence of ^he Earth and Sun is
4
=^+
%{\^^y^-\i^^,^^^)\
where Xy y\ z aro Uve co-otdma-tea of the Sam
Lpr. 1908, Motion of Ecliptic ami Figure cf the Earth. 453
The main problem is solved with z = o. Hence the additiDual
^rtion due to 2' in, if we neglect squares of z\
With the notation and Hinii'itions of § 2^ 5 we have
z = t{y coa T - / ain t) .
Also, with this value for z and by means of the equations ---. = ;r—
etc., it is easy to show that
^B Hence, since r ta a constant, we obtain
;)"'"'}•
*^« Tt'
where for t we Bubstitute its periodic portions, omitting those
mentioned at the end of § 3.
5. It 13 of some interest to compare the two disturbing
fuacttons E^ Ra« lu general we have
^
//'■'
.•-'Q
^^'^i'^^-'i-^i-i^^-
IThua the effect of the rotation of the axes alont*^ apart from the
jHiotion of the Sun out of the fixed plane, is to introduce a term
Broi
-(rQ). From these expressions we may also prove the state-
en t0 mnde in § 3 ^"^^^ reference to the presence of long- and
lrort-p»*riod t»^rms, remembering the two forms which have been
given for *^. In fact, the terms of long period in Q are relatively
much larger than tliose in -^ owing Uy the presence of small
divisors ; for a term of very long period in K^, the [jortion arising
from — (*'Q) i* small compared with that arising from llj ,
6, The computation from the two functions R^ B.^^ as defined
in ^ 3j 4, give the results which follow. The valutas of Leverrier*
have been used for i\ r^ and the method in the same !i« that which
I have used for planetary in equal iiios in genend.
I put f<?j, w^, w^ for the mean longitudes of the Jfoon, of its
perigee and of its node; I, D, F, n, e, y are the ciuantities as
defined by Delaunay ; T^ V, J are the mean longitudes of the
* Ann, ObSf Parif (MM,), vol, iv, pp. I3-21.
4S4 ^' ^* ^ Brown, Lunar Inefualities diu to LXVIIL6,
Earthy Venua, and Jupiter, respectively; ^ = Wj+96'*2; 4^*-^^^]
Then the variations of the elements for the principal inequalitT.
argument <^, arising from Ki, are
Sw^=^ - o"*289sin^, S» = + o"*ooi4n co» ^ ,
gf/j^— 4- o'''S40 sin <^, $6= *ooo cos ^ ,
Sfi^i, =^ - 1 5"'S9 sin <j^ , ^ = + o'''698 cos ^ ,
rOinBl^H
These agree very closely with ih« vahiee found by Pr
Newcorab.* They differ a little more from those fouod by
Dr. Hill;t he, however, used a method with a literal develop-
ment, and the small ditferencefl are probably dne to slow con
verge nee.
The principal tenn in latitude, argument i^', baa a coefficient <)f
•}, The new terms arising from B^ are, if we omit terms '
coefficients leaa than o"*oio,
In Longitiiile. In Latitude.
+ o'''0!9 sin (^ + sT - 3V+ 119') + o''*o77 sin {^* + 5T - 3V + nij \
+ o"*oo3 sin (tfi + 2W0 - 2 J -I- 90") J + o"*o3o sin (<j^' - 5T + 3V - ii<^*'m
+ o"*035 Bin (<^' + 2 J + 72*)
+ o"'oi8 sin (ifi - 2 J - 72*),
The two terms in longitude are ** primary ** terms of k
period. The second one is of interest, since its period is that af
the empirical term which appears to represent best the long-period
difference between theory and observation, namely, about 280
years. Its coefficient is, however, too small to account for this
difference.! There is a t^rm with the same arjjument due to
the direct effect of the planets, but it« coefficient is also insensible.
The terms in latitude are '* secondary," and have periods approxi-
mating to a month,
8, Imquaii'tks arisimj from the figure of the EariK — ^TbeM
have been computed very fully by Dr. Hill§ who used the m-thod
of Delaunay, and there would be no reason for the mention of
them here if it were not that slight doubts have arisen concerning
their degrees of accuracy on account of slow convergence, I baV
used the equations of variations and the results of my lunar the
which allow the coefficients to be obtained easily within o*''C
This method is brief, and the computations occupied about eij
* Carzie^fl Institute, nnbK 72, p. 132. The differcDce in the vain* of I
is due to a differetjco in the detinitiun of tlii» variation.
t Jnuitfs 0/ Maih^t ^ol* i- P- 57- Coll. Works, vol. ii. p* 77.
t In a note on p« 170 of the iiresent volume, and in this paper M 1
before the SocietVt I pr«ve o'*'2i as the value of this coefficient, A tecaJ^
tion with the first form of R^ revealed an error in the foimer compntttioiLj
§ Amer^ Epk, Fapers, vol iii, pp. 201-344. Coll, Works, voL ii* f
181-320.
fpr, 1908. Motion a/ Ecliptu and Figure of the EartK 455
days. I put (^ - fi?g +
of the elements
tbe precession, and obtain for the variations
6w^= A- 7 '517 sill (^,
he^= - 2^*092 sin ij^,
arrjj = + 96" "69 sin ^ ,
Sn == - o"'oo9 cos ^ ,
The short-period terms add - o'^'oiy sin (i/r + F) to the latitude.
The priiicipai term in lonpfitudts is Ztt\^ and the principal elliptic
terms are + o''-5 1 9 sin (i/^ + /) + o"'5 1 5 sin (^ - /). Thi principal
term in latitude is - 8"'355 sin (iff-f F)^ and tiiat with argnmtsjit
^-F is +o"'338sin(i//- F), When Hiirs results are reduced
to the value of the ellii>ticity used above (1 296 3),* my coefficient
of the principal tenn in latitude agrees with his, and my coefficient
of the princi{>al term in lon^^itude is o''o30 less. The coefficients
for the term with argument i/^ - F also agree ; this fact furnishes a
useful tesit. since this coefficient is the ditrert^nce of two numbera
each nearly thirteen times as large as the coefficient. The two
principal elli[>tic terms are o"*o2i, o'^'oiy, resppctively, greater
than those of Hill An examination of Hill*s literal developments
for the coefficients shows that tht^ smali diilVreiices can all be
explained by alow convergence. .^*--
The complete results for the classtja of terms considered here
will \\^ given in the tifth (concluding) part of my Theory of (lie
Motion of the Moon, with the terms due to the action of the
planets and to perturbations not considered in the previous parts.
NtriT Sn r€ n , Con «.
1908 Fthrunry 1,
^ been exatnined and produce nothing sensible, Howevpr, in coDse-
quence of my attention being called by Dr. Hili to a doubt as to
whether ther« was a portion of the secular acceleration due to the
figure of the Eiirih terms being referred to a moving ecliptic, I made
i an actual computation of this second order perturbation and found
I that the greate.st effect could be exhibited in the form of a term of
» period about 15,000 years and coefficient o"' 15. This, equivalent
to a secular acceleration of o"oooi within historic times, is entirely
insensible. The compuUitiun will be given in chapter xiv/of my
memoir just mentioned.
* Corresponding to the reiult mitrk^d {0) in M,K»f vol. Ixiv, p, 531,
456 Newly Discovered Eighth Satellite of Jupiter, LXTin. 6,
Note on the newly discovered Eighth Satellite of Jupiter^
photographed at the Royal ObeertxUory, Greenwich.
{Gommunieated by the Astronomer Jtoyal,)
Since the date of the last commanication soccessfol photographs
have been obtained of this object on the following nights : — March
27, 31, and April 3. From these it would appear that the object
discovered is a satellite of Jupiter very much more distant from
the planet than the sixth or seventh satellites. The following an
the places deduced from photographs taken with the 30-inch
reflector.
8»t. Vin-Jupiter.
Date and O.M.T.
Exposure. Api>arent B.A.
Apparent Dec
R.A.
Dec
1908.
d
h m
min.
h m ■
0
,
Jan.
27
12 41-4
64
8 4551*86
+ 18
5 1-4
-0 829
-43 173
Feb.
I
II 521
III
43 20-67
17 36-3
+ 0 2-20
41 41-1
3
10 27-3
80
42 21*90
18
22 257
0 6-37
41 0
22
10 566
100
33 35-41
19
5 49-8
0 48-38
33 5«-J
23
833-8
42
33 13-98
7 37*6
0 50-31
33 357
24
12 24-9
80
32 47-37
9 51-3
0 53-^5
33 9-2
27
10 59-4
70
31 4289
15 181
0 59*94
31 597
28
II 28-6
80
31 2176
17 67
I 2-34
31 35*2
Mar.
27
8 54-3
43
26 32-33
47 53 '5
2 11-35
2059-9
3'
9 i6-5
165
26 40*24
49 »2-3
2 2155
,9381
Apr.
3
9 517
90
8 26 54-38
+ 19 49 38-8
+ 2 28-99
-18 40'2
The G.M.T. is the arithmetical mean of the times of beginning
and end of exposure.
Thevse places are defmitive, replacing those given in the previous
number, p. 373, which are provisional only.
The new satellite has also been photographed by Dr. Max Wolf
at Heidelberg on March 3, 23, and 24, and at the Lick Observatory
on March 8.
[A pht)tograph of Jupiter's Eighth Satellite, us well as of the
Sixth and Seventh Satellites, has since been obtained on April 24.]
Note by Mr. Melutte.
Throughout this and previous oppositions, in examining the
photographs of Jupiter's sixth and seventh satellites a good look-
out has been kei)t, with a view to detecting other satellites, should
any exist. In view of the large gap between the orbits of the
inner satellites and the sixth and seventh, the existence of others
would appear not unlikely. On several occasions previous to this,
suspected images had been noticed on the plates, and in wme
Apr. 1908, First approzimation to tlie orbU of J VIII =^ CJ. 457
(notably on four platen in 1905) images had been found on
plates taken a few days before or aftt^r, which might possibly
correspond. But the diffii-ulty of diatinguiahinj^ between photo-
gra|>hic defects and true imageB is natumlly very cunsideral>le^ and,
nntil the present occasion, it had never be on possible in any case
to obtain untticient evidence to decide whether the images were
real. A record of the positions of all suspected images is made
for future reference
Roffi^ Ob^rtKiUiry^ Great wich :
1908 April 10,
Fir$t approjeini(Ui*m to the i/rbit of J Vill^OJ.
By A. C. D. Crommelin, B.A.
The hypothesis of retrograde motion gives a much more reason-
able vajue of the disinnco of this object from Jnpitfr than the
hyj>othe«is of direct motion ; it haa therefore lieeri provisionally
adopted. Assuming tliat the diainnce of the object from Ju]nter
has remained sensibly constant during the period of observation
(thii assumption being justified by the uniformity of the rate of
Diotion, wh**n corrected fur the varying distance and direction of the
planet from the Karth), tt is possible to deduce this diskinee by the
currature of the apparent path (the greater part of this curvature
bein^ due to the Earth's motion)*
The result of several successive approximations gives the follow-
ing values : —
Distance from Jupiter at inferior geocentric ecmjiinction, 0*213
in astronomical units.
Date of this conjunction . . . 1908 Feb. ao'o
K.A. of N. pole of orbit [►lane . . 336' 25'
^* *iec. »i . *' ** • * 54^ 48
Inclination to Jupiter's orbit . , . 32'
Dady atigubr motion about Jupiter , 0**288
This satisfies all the observations within some 20" ; a closer
apprf»xiniation could doubtless be obtained, but it is hardly worth
while to do so till enough of the orbit has been described to make
m reliable estimate of the solar perl:urbations, which must be
extremely large. The rate of linear rnotiuu ap[»ears lo iiave dimin-
ished by I per cent, in the period March 3 - April 3 as compared
with Jan. 27 - March 3. This would be sidhciently explained by
the Variation causing the motion to b^^ most rapid at Kew and Full
Moon.
The daily angular motion in an undisturbed orbit at distance
02 i^ao^*2i^jdth which the value o''288 is in salisfactot^ •a.tii^^tsi^
458 Messrs. Cotoell and Crammdin, FerturbcUions of LXVUL 6,
especially aa the effect of the Variation both on the diatanoe and tlit
Telocity most be considerable. The sidereal period ia probably
between three and four years, the synodic period being about one
year shorter if the motion be retrograde.
The mean distance of satellite VII from Jupiter ia 0*0785, so
that the value of the distance found for the new body is about three
times as great.
Tabh giving approximate values of the perturbations of HaUeift
Comet by Jupitfir and Saturn in thA first and fourth quadraids
of the orba. By P. H. Cowell, M.A., F.R.S., and A. C. D.
Crommelin, B.A.
A sufficient number of revolutions of the comet have now been
computed to enable the perturbations to be tabulated as functions of
gf, the mean anomaly of the disturbing planet at the adjacent
perihelion passage. The formula for determining g^ was given in
M.N,, Ixviii. 3, p. 177. The table is not intended to supersede
calculation, but it serves —
(i) To form a good first approximation to the date of anv
perihelion passage, as a preliminary to more exact csl<
culation.
(2) To detect any serious errors of calculation.
(3) To readily correct computations made with an erroneous
assumed date of f)erihelion, by means of the rate of
chancre of the tabular quantities.
Jupiter
, i6t quad
Jupiter, 4th quad. |
Saturn,
istquad.
Saturn, 4^1 4
ff'
^dn
^dT:^
■j.<.
Jd»
frfro
J..
p.
J
its
><
>
>
0
M „
II
u
//
^
^
//
»*
^^
m
i
0
+ •85
- 210
+ 140
+ •26
-460
- 60
+ 19
0
4-
20
-03
* 10
10
•93
130
160
•32
450
90
•14
-
30
20
•06
0
20
•99
- 30
180
•37
430
120
•09
50
20
•10
0
30
I -OS
+ 100
200
•43
410
140
•07
60
20
•15
r 10
40
i-io
220
200
•48
380
ISO
•OS
50
10
•19
JO
50
113
340
190
'54
350
160
•04
30
10
•23
30
60
I-I4
450
170
•59
320
170
•03
20
10
•24
20
70
I-I3
560
140
•64
270
170
•02
-
10
10
•23
-!- 10
So
i-io
660
90
•67
200
160
•01
+
10
10
•21
- 10
90
•97
670
40
-^•38
-100
130
+ •01
20
JL.
10
•IS
30
100
71
610
+ 10
-•27
+ 130
no
•00
40
0
•'5
50
no
•39
470
- 30
•90
420
70
- -oi
SO
0
60
120
+ •03
330
70
I 20
620
- 30
•01
60
0
•10
70
130
-•18
210
no
I -28
710
+ 10
•02
60
0
•07
&>
1
'2A
100
120
> 1-2S
6^0
so
•03
60
0
•05
SD
Apr. 1908. HaUet^s Comet hy Jtvpiter and Saium,
459
J^Bqi»tte
r, iflqiu^
I.
Jupiter, 4th quad.
Satnni, xit quad.
SatniD, 4tii quad.
:/-
Jte
J^
/.»
dw
di
J-
JdCT
\^
[dm,
fto J.
^
«
m
u
, u
u
m
It
II
II
II
•«7
4- 20
130
V20
560
90
•04
50
- 10
•03
90
-»7
- 50
130
ri6
470
120
•04
40
10
-•02
80
•ay
120
130
1*12
370
140
•OS
30
10
•00
80 -
•«7
170
130
1-08
270
160
•06
20
20
+ •01
80
-96
220
120
1-03
180
170
•06
+ 10
20
•03
70
•«4
280
110
•97
+ 70
180
•06
- 10
10
•04
50
•«3
340
90
•90
- 30
190
•06
20
10
•05
40
-ai
390
80
•83
130
200
•05
40
- 10
•06
20
-X9
460
60
76
230
200
•04
50
0
•06
- 10
•x6
520
40
•68
320
190
•03
70
0
•06
+ 10
-xa
580
- 20
•58
420
180
-•02
80
0
•06
20
— -06
620
0
•48
510
160
•00
90
+ 10
•06
30
640
+ 20
•38
550
130
+ •02
90
20
•05
40
-»-x>7
640
40
•29
570
no
•04
100
20
•04
50
-16
630
60
•19
590
90
•07
90
30
•03
50
-«5
610
80
•II
600
70
•09
90
30
•02
60 -
-34
580
90
-•04
600
40
•12
90
30
+ 01
60
•4-4
530
100
+ •03
580
+ 10
•15
80
30
•CO
50
-54
470
1 10
•09
560
- 10
•19
60
30
•00
30
-^5
400
120
•14
540
30
•22
40
30
-01
+ 10
4- -75
-310
+ 130
+ •20
-510
- 40
+ •22
- 20
+ 30
-•02
0 +
To \di in the first quadrant must be added the corresponding value of
\dn X period in days.
The argument g' is the value of the planet's mean anomaly at the preceding
perihelion passage for the first quadrant, at the following passage
for the fourth quadrant.
460 Prof, Twmer, Condition for the passage of the, Lxvm. 6,
Note on the eondUion for the passage of the Earth through, (he
plane of Saturn's Ring. ByH. H. Turner, D.Sc, F.RS,
Saviliau Professor.
I. The interesting observations miids recently on the ring seen
edgewise have brought several inquiries as to the recurrence of this
beautiful phenomenon; and the following note, originally made
some years ago in consequence of an inquiry from Mr. C. T.
WhiDmell, may be of use to others. The latb Mr. R. A. Proctor
gives in his book Saturn awl his System a general account of the
maimer in which the Earth may pass through the plane of the ring^
either once or" three times, at each favourable opportunity. The
present note gives the explanation in more compact form.
Fio. I.
2. Let H be the Sun (fig. i), EOF, ABDC, the orbits of the
Earth and Saturn, supposed circular and in one plane. Let BD
and AC be two tan^i^ents to the Earth's orbit parallel to the plane
of Saturn's ring. Tiien if S be Saturn and E the Earth at a time
of passage through the ring, P2S must be parallel to BD or AC.
Hence Saturn must be either in the portion AB or DC of his orbit
Since his orbit is ten times the size of the Earth's, these favourable
opportunities are confined to limited periods which recur at long
intervals. AI> is about ^.- of the semi-orbit, and is described in
about a year, so that the Earth meanwhile makes a complete revolu-
tion. If, when Saturn is near A, the Earth is near F, then there
may be three passages through the ring.
3. To find the condition in exact terms, take HX parallel to
AC or \VD as axis of x. Let the radius of the Earth's orbit be unity,
and that of Saturn's orbit n-. The co-ordinates of the Earth may
be written
jc^=co8 ty^ (/^ = sin /,
Apr 1908. Earth thfrnigh the plane of Satm^*8 Riuff, 461
aod of Saturn (reraembering Kepler*« Third Law)
% ^ »2 cos- {i - a)jn^, y^ « «* ain {t - a)/n*f
where the unit of time is i/stt of a year and the origin of time ia
taken when the Earth lies ou HX, Saturn then beiuj^' an angle a/«*
behind it.
The coodiiioD for passage of the Earth through the ring is thus
Vi = ¥'1 *^r sin t ^ »* sin {t - a)/n*»
a transcendental equation^ whtch we can only solve by approxi-
mation.
4. Let ua draw the curves
(a) i/-sin^
(b) y^n^sih{t~ayn\
then the required values of t will be given by their intersections.
Now the curves are both aine curvea, differing only in |jeriod and
amphtude.
Fio. 2,
The Earth^s curve (a) alternates much more rapidly, as in
ABC (fig. 2). Saturn's curve (b) is a broad sweep, ABC, and we
■ee at once how the crossings of the two curves correspond to the
• favourable opi>OTtuoities of fig. i ; and further, that there may be a
aingle intersection as at A, or a triple intersection as at C There
muat always be an odd number of intersections ; whether there can
be five, seven, or more depends on the actual dimensions of the
corvea. If there is only one intersection, notice that the slopea of
the two curves are in opposite directions, i.e. the planets are on
opposite sides of the Sun ; so that Saturn will be near conjunctiott
with the Sun, and the phenomenon will not be so readily observable.
If there are three intersections, the middle one is near opposition
and the other two near quadratures.
5, In fig, 3, let ABODE be two consecutive waves of the
Earth's curve, and let FG, HK, LM r*^ present three possible
positions of a portion of Saturn's curve, each touching the Earth'a
curve in one point (F, K, L) and cutting it in another (G, H, M).
It is clear that if Saturn's eurve cuts the axis OX between Tand V
there will be only one intersection ; ii between V and W there
will be three. The separating cases are thus defined by the three
vmloes of a, OT = a^, OV = Oj, 0 W = a^ and it is easily seen that
462 Prof. Turner^ Condition for the passage of the Lxvm. 6^
6. 1
y and
6. To find the valae of 04, we have the conditions that botb
-^- must he the same for hoth cnrvea.
at
sin ^ = n' sin {t - a)/n*
whence
so that
and further sin
(<-«)/n«l
n* COS ^ = n* COS (< - a)/n' J
sin* ^ + n* cos*< = n* .
n« sin* {t - a)/»» + cos« (< - a)/n» - n«
cos* « = (n*-i)/(n«-i)
n \ n* + n*j
(3)
(4)
(3)
(6)
Since n^ is 29*46, the number of years in which Saturn revolves
round the Sun, n = 3*088, n* = 9*54, n* = 9i'o. Neglecting
quantities of the order n~^ in t,
t=-^ + l. + ^^, (t-a)=-n + ±--L
2 n 6n^ — —
2n 24n'
a= - --+W + —
L__5_
. . • • (7)
Z 271 2471^
Thus for Saturn-Karth a= 1*683, or 96" 25'. Or we can, of course,
obtain the numerical values of t and (t - a)/n^ directly from equa-
tions (5) and (6).
7. Hence a^ -■ 96", • a., = 264°, Og = 456**.
And in the long-run, since the period of Saturn is incommensurable
with that of the Earth, the values of a will be distributed
uniformly, so that in a long series of years the chance of three
intersections is
(«8 - <^)/36o° = 192/360 = -53,
and the chance of one intersection is
(a,^- a^)/36o' = 168/360= *47.
Apr. 1908. Earth fhrotigh the plane of Saturn's Ring. 463
SUrtiDg from any croasiug with a value o^ for o^ the next crossing
til the mmt direction will be at a poiot
1Z3=2^
or ^ = tt<j+ 29*46 X 27f
= Qq + 166' omitting 29 X 2r,
The internieiiiate crossing is in the opposite direction and at the
Op(.Hisitt? poiiu of the orbit« The eccentricity of Suturii's orljit is ao
large that the intermediate value of a cannot be inferred by ele-
mentary const deratioTis. There will be practically two separate
series of values of a referring to the two nodes, each increasing by
the difference 166% But this value 166* is only approximate, and
is modififd by the motion of the ring plane. It a[>peara from the
aubjomed table that at present the average value is abcjut 162'.
8. The dates when Stiturn crosses the line of nodes, or more
pioperly when his ring-plane pass+^s through the Sun, are given by
Mr Pructor on p. 223 (Table X.) of his book above mentioned
(Saturttr atid his Syetem). It will sulBce here to give a few of
them to the nearest day :—
Ynr.
I7S9
1803
1819
1848
1862
1878
1891
1907
Sun In
plune of
Ring.
Oct, 7
Juue 23
M»r. 23
Dec. 4
Sept. 3
May 18
Feb. 14
Oct 29
July 29
Earth's
Fa«aiige.
Sept. 13
Mar. 12
Sept. 14
Mar. 12
Sept. 14
Mftr. 12
Sept. 15
Mar. I J
Sept 16
FractiODi of
Vear.
Sat. Sarih.
764 '698
'473 ^192
*221 700
•923 *I92
•671 700
'375 "192
•120 703
•824 -195
•572 706
Dlffce.
... -281
'521 ...
... 731
'971 ..,
... '183
•417 ».
*629
•866 ...
M
187
349
ISO
3«2
263
66
226
Columns i and 2 above are from Mr, Proctor's book ; column 3 is
filled in from the Natitical Almanac by finding the date when the
Earth had the same hehocentric longitude as Saturn had on the
date given in the column b*ifore. The next two columns give these
datea in fractiouH of a year, and the differences are the values of
a in the unit adopted in J? 3, viz. iJ2w of a year, more conveniently
expressed in degrees in the next columns. The two series are kept
separate, and it will be seen that the common difierence is about
162* or 163'* If it were exactly 162*= 180*- 18*, the numbers
would repeat after twenty term a, and we should have the series as
follows : —
- 4
464 ^Tof, Tvrne7\ Condition for thepaasage, etc Lxyill.6,
First Serien,
Year 1789 1819 1848 1878 1907 1937 1966 1996 2035 ^55 ^^^
a 25" 187" 349" iSi" 313" "5' «77" 79* Mi" 43' 205' etc.
No intersect^*. 313x3133131
Second Series,
Year 1803 1832 1862 1891 1921 1950 1980 2009
a loi" 263" 65" 227* 29** 191*' 83' 245" etc.
NointereectM. i 3 3 i 3131
Under the actual -conditions, the series will slowly diverge from
these, just as the cycle of total solar eclipses on the Earth slowly
changes.
9. If the slope of Saturn's curve were less relatively to that of
the Earth, there might be five intersections. For obseiyers on
Venus or Mercury this might be the case. The limiting case
when five intersections are just possible is when a Saturn cnrrs
through the point Y (fig. 3), just touches both the adjacent curvet
near V and K, and then equations (2) are satisfied by a = ir.
.*. from equation (7) 71 = 5^-- - -L-^^ = ^'c^ approx.
2 2n 24W*
For values of 7i greater than 4-54 there will accordingly be three or
five intersections, and five will occur with greater frequency as «
increases.
Now Bode's Law gives for the successive relative values of n^
4 7 10 100 [38S]
^lor. Ven. Earth. Saturn. Neptune.
Thus for Saturn-Venus, 71^ = 14*3, w = 3.8
ff)r Saturn-Mercury, 7^^ = 25, 71=5*0
Hence Saturn's ring can disa])pear five times to Mercury, but not to
Venus. The value of n for Saturn-Neptune is too small for anj
but three intersections. It will readily be seen that the above pro-
cedure is applicable to the outer planets, the curves interchanging
character.
10. Although Saturn's ring is a special problem, there are
cases somewhat similar, e.(j. the changes in declination of another
planet. Times when the declination vanishes are times when the
planet passes through the Earth's equator, and thus would be in
the plane of its ring if it had one. The three intersections can
readily be tiaced in the tabulated declinations of (say) Venus.
Apr, 1908* VariahiHty of Nm{mis q/ Nehd^ N.G.C\ 7662, 465
The VariaUlity of th^ ^uclem^ of the Planetary Nebula
X.G.C, 7662. i86o'o, a 23** 19*° iP, 8 + 41" 46' *o.
By E. E. Barnard, (Plate 12.)
This remarka1>le nebtiUi (X.G,C. 7662) is situate*] in Andro-
me^la. In an ordinary telescope it lo^^kss like a siimll round disc
of a bluish-green colour. In tke 4- inch tindt^r of the 40-incli
telescope it is only distingaishablo froui au ordinary star of the
S™ or 8 J*** by a alight fuzziness of the image, lu tht? great
telescope, however, under good conditions, it is a beiiutifnl object
— a slightly elliptical disc wiih quite ^ sharply defined outlines,
Uugymmelricaily pla^^ed on thia is a roughly elliptical broken
ting of greater brightness. The interior of this ring is dark, but
not black, and in this, approximately central, is ordinarily a faiot
stellar nucleus, The broken ring (broken on its n^p. side, and
with a smaller break oppos-ite this) is of a bright bluish-green
colour, while the goneral disc of the nebula often has the appear-
ance ot a warm or faintly raildish tint. The tiortbern part of this
inner ring is the brightest part of tlie nebula. The nucleus, with
which I am going to deal specially, is somt-tinie^i of a bright
yellowish colour, though ordinarily it is faint and aj>parently
colourless. There is a ftdnt hUw of the 15*5 or 16 magnitude
exactly on the following edge of the guter disc.
Shortly after beghming to observe this nebula in 1897 I
suspected that the nucleus was variable {see Astrophyncal Journal,
jtiv. p, 155). Familiarity with the changing aspect of a star
involved in nebulosity, due to moonlight, bad seeing, etc., has
made me extremely cautious in this matter. I have, however,
for several years, establiahetl conclusively the fact that the nucleus
of 7662 is actually variable to an extent of upwards of three
magoitudej^. At times it Inis appeared as a bright yellowish
star of about the 12th magnitude; and at other times, equally
favourable, it has been either entirely invisible or excessively
laint» Though I have not deiinitely determined the period, the
light changes seem to cover al»out 28 days. The light curve is
still undetermined; the normal condition^ however^ j^eems to be
faint^ — the nucleus remaiinng bright for a few days only*
I have collected here the principal oliservatioiis of the brightness
of the nucleus, etc., obtained with the 40-inch telescope in the
past ten years.
On 1 904 August 6, among other objects, I showed this nebula
to Professor H. H. Turner. Though we both looked very carefully,
under fairly good conditions, we could not see any trace of the
nucleus. It must iiave been below the i6ih magnitude at that
time.
In all the observations of this nebula the eyepiece was adjusted
fur the nebula itaelf, the focus of whtclu as I have shown else-
where (M,N., Ix. pp, 255-257, and Adrophyskal Journal^ xiv.
jbout a quarter of an inch outside that for flt%\«c^
vh m
466 Prof. £. K Banuud, The VariabilU^ of t/ie LXVia6,
Following are t!»e observattons of the nucleus, takea from my
notes oil the nebula with the large telescope.
Obsen^ations of the hrifjhtneM of tfie Nucleus,
1897 Sept. 1 7, Julian day 4185, io*» o'^. The nucleus it 15*
or t6th niag]iitude*
Sept 28. 4196, 10^
iM^CQuni of poor seeitig.
Oct. 3. 4201, 8*^ o°*.
while. The Beeing is bad.
189S Sept 2o» 4553, 9*" 30™. The nucleus is either ahsrat
or eacceasively faint. I think I can occaaionally **ee faint traces d
it. From recollection alone, it seems this must be very miwi
fainter than it wus last yean The iletinitiou is lair.
Sept. 26. 4559, 12** 35°*. I thijik 1 can see the feeblest tiwe
of the nucleUBf but it must be excessively faint The seeing is liir*
30". The nucleus is seldom
The nucleus is seen only once
4
13"
Can eee it faintly with 700 diameters.
1899 July 31. 4867, 14*^ o*". The nucleus is very diffiealt
Aug. t, 4868, 13*' 30". The nucleus is very difficult Tht
inside of the inner ring is very slightly darker than the getieml
surface of thn nebula.
Aug. 14. 4881, 15*^ 10**. Can only catch the fe€>blest glimpiet
of the nucleus. It seems to me that it was brighter when tbe
former measures were made. The inner ring is bniken in tw
opposite places*
Aug. 26. 4893, ir*^ 40^. The nucleus is vtry haitl to •*<
The seeing is very bad.
Sept 3. 490 !, 9** 30"* Can once in a while see the oudeoi
The seeing is very bad.
Sept 25. 4923^ 15^ 20"
The nucleus is seen only feebly
1900 July 17, 5218, 14^ 30™. The nucleus is 12th ma^i*
iude, and is very eusv. It is yellowish.
July 28. 5229, 14** o'", I caoui>t see the nucleus ; possibly
could catch feeble glimpses of it It ought to be visible. I hiw
thought several times that the nucleus of this nebula is ViriaHle,
It looks strongly that way now.
Aug. 6. 5238, 14^* o"*. The nucleus is fairly di^inct
i« a ^SS"" ^^ '^"* ^^^ exactly on the north edge of
nehuk.
Sept 20. 5283, 10^ 10™, The nucleus is extremely I
The seeing is fairly gt>od,
190 1 Aug. 7. 5604, 12** 30*°, The nucleus i» readily seen.
It is yellowish, and of tlte 12th ma^'uitude.
Aug. 24, 5621, 16^ o*". Can feebly see the nucleus, but it
seems very faint. The sky is poor, but the nucleus ought \o bs
brighter ; the sky i« too poor to be certain. I have suspected tlifi
nucleus of being variable. Cannot see it well enough to meaini^
its positiou,
Apr. 1908. Nndem of the Planetary Nebula KG.C. 7662. 467
Dec 22. 5741, to^* o*". Can faintly see the nucleus, but
Dot distinctly enough to measure*
1904 Aug. 6. 6699, 13** o™. Prufessor Turner and I looked
for tbe nucleus. We criuld see no trace of it with 460 or 700
tiiarneters. The seeing was fair, so that we could see tbe details of
ihe nebula well The nuclenn must he Tar bt hie.
Aug» 8. 6701^ 14*' 20"^* Have just triml tlie focuBf etc* for
the nucleus. Can see nothing of it Tried eyepteoea 460 and
700. The seeing ]>art of the time wafi fair,
Aug. 13. 6706, 1 1 '^ 40'". Can seethe nucleus quite distinctly.
It is about the 14th ntngnitude and \% quite stellar. I think we
ought to have seen it on the 6th if it was as bright as now.
Seeing 3 to 3.
Aug, 15. 6708, 12** o™. Can faintly we the nucleus, though
the aky is thick.
Au^, 16. 6709, i4*» o"*. Can very faintly see the tiucleua;
eyepiece 700. I am not sure but that it may be fainter than laat
Ql^t, for the sky, though poor and thick^ is better than then.
Aug- 22. 6715, 10^ o'^ Can &ee the nucleus very plainly;
eyepiece 700, It is 13th or 14th magnitude. Very much plainer
than the central star in M 57. It is quite bright. Seeing 3-4.
Aug. 27. 6720, 13** 30™. Eyepiece 700. The nucleua is
well seen, about 12 J magnitude; the same briglitneas as Btar 6
(more carefully ; — It is decidedly brighter than h). It is about
midway between a and h in brightness and is very easy. Perhaps
plightly yeUr»wish»
Aug, 29. 6722, 14^ 10^. By glimpaes can see tbe nucleus.
Can just see '' *in account of poi^r seeing, so the nucleus is not
fainter than on tbe 2 7tb. Seeing very bad.
Sept. 3* 6727, 9** o"
Can see tbe nucleus^ but it ia not
clear. It ia about i4tb magnitude. Decidedly less noticeable than
the Btar L Eyepiece 700.
Sept, 6. 6729, 13** 40'". Cannot see the nucleus, or if it is
seen it is excessively faint I think in the moments of g<x>d seeing
I ought to see it. At such times h ts quite easy or rather con-
" leuous. Just in this directi<>n tlie sky seems fairly clear.
Sept. 10. 6734, 9^' 30"'. Can feebly catch glimpRes of tbe
nucleus^ but the sky is thick. I eau see tbe star 6, but not
very distinctly, on account uf thick sky. Eyepiece 700.
Sept. 12, 6736, 11'^ 45"'. The nucleua is very faint, 15th
magnitude. Seeing 3* Tbe star b i^ con!<ipieuous.
Sept. 16. 6740, io*»o™± (no record of time). The nucleus
it easy, aay 13I magnitude^ It is less than the star b.
Sept 24. 6748, 12^' 3o"\ Eyepiece 700. Can see tbe
nucleuB 8tea<iily. When best seen it is brighter than the star
K It is not less than T3th magnitude. It is perbap8 m bright
aa 12 or 12^ magnitude. Full moonli^dit. Looking more
earef^lly, it is <lecidedly brighter than b. It is not fainter than
lath magnitude* Seeing 3,
Oct I. 675;, 9^ 30*". The nucleus is seen occ^\Ci\va\Vg.
'468 Prof. K E. Barnard, The Vm^biiity oj the Lxvia6.
It is much fainter iban the star b, I should aa/ it ia 14th magm-
tude. Eyepiece 700. Seeing 2.
Oct. II, 6765, 9** 30*", The sky is thick. Cannot he stire
of the hrightnrss of the tiucleUB. It is faint, hut the inagnitaile
uncertain, say 14th or leaa. Seeing poor <= 2.
Oct, 15. 6769, 13^ 40". Cannot see the nucleus. Tht
star h is easy and conspicuous. I do not think the seeing h such
.aa to blot the nucleus out if as bright a^ it has sometimes been.
Eyepiece 700.
Oct. 17. 6771^ 7^ 35"*. CanHec the nucleus quite easily^ ijrli
or 14th magnitude. I am sure it is brigbter than on the i^ih. U
seems nearly as cnnspicuous as the star b. Seeing 2 or 3.
Oct. 22. 6776, f4*' 5'". I think I can see the uucleua occa-
sionally, bnt cftunot be certain. If it is seen it is about as bright
as the star 6, which in faint and not well seen, hut the fieeiug is
too pour to decide. The nebula is 5 hours west.
Oct. 29. 6783, 7** 30°*. I can Fee the nucleus. It is about
i4lh tuagnitude. By glimpses it is fairly well seen but I do not
think it is as bright as it has been, i^eeing 2^ Eyepiece 700.
Oct. 31. 6785, 7*^ 30'", The nucleus is fairly well si>en, about
I3i magnitude. . It is not as bright as the star k A little later :— I
see it better now. It is 13th niu|;nitude. Eyepiece 700.
Kov. 5. 6790, Jo^ 50*". Eyepiece 700. I can see the
nucleus occasionally* It is faint, perhaps 14th magnitude. The
star /m 8 quite easy and bright. I think the couditiona ara antb
that the nucleus ought to show up distinctly.
Nov, 12. 6797, 9** 2o"*. Eyepiece 700. I can see the
nucleus occasionally fairly well. Seeing pour, but by mcmebU of
steadintBs it must be as bright as i^tb magnitude* It ia naarly as
conspicuous as the star b.
Nov* 14. 6799, 6^ o***. Eyepiece 700. It is faints say
14th magnitude. I think it ought to be brighter if it is not
variable. Though 1 can see it, It does not appear as stellar ad it
has appeared at tiures. There is a half moon ahining^ wbich may
have something to do with it» Seeing = 3.
^'ov• 26. 6811, 9*^ 15**, Eyepiece 700. The nucJenft
is faint. It is not brighter than 14th magnitude. By moments
the seeing is t airly good. It is far less bright than star h. It ia
not well seen.
Dec. 5. 6820, 5** 30m. Eyepiece 700. I can see tie
nucleus^ but it is faint. It is between 13th and i4lh magnitude,
,and is much less conspicuous than the star b,
Dec. 10. 6825, 7^ o"^ The sky is too thick and the nebub
is dull. I can see the star h faintly^ but cannot see the nndeia
The sky is too thick, however, for this observation to count.
1905 Oct 28. 7147, 7** 30*"» The nucleus is steadily seeo
with both eyepieces, perhaps best with eyepiece 460. Jt i*
nearly as bright as the star b. Eyepieces 460-700. Seeing 3.
Kov. 26. 7176, S*' 35"*. The nucleus is very faint, TtiJ
much fainter iliau U\e ^Ut: 6. Seeing 3.
-Apr. 1908* N^idemofihe Piunetarif Nebtda N.G/J, 7662. 469
Nov. 28. 7178, 8*' 45°^ Eyepiece 700. Tbe nucleus is
very faint, but 1 cau see it in apite of the bad seeing. It is much
fainter than tlie t^tar h,
1906 Au^% 11, 7434^ 14** 40™. Eyepiece 460. The niacleua
isnfabotit the sanje briglitness as etar h. Its appearance is the-
game with eyepiece 700, It is not leisa briglit than the j^tar h.
Beeing pour,
Aug. 14, 7437i ii*'5o™. The nucleus is very faint I think
it is one maguituile les^ than the star Ik
Sept. 4, 7458, ij'^ 50^". Eyepiece 700. The nucleus is bright
and conspicuous^ of about the 12th magtiitude, and seems to be
yellowish. The seeing is not especially good; it comes and
goea.
Sept 8. 7462. 13'' 45'", Th*5 nucleus is easy. It is i magni-
tide less than the star Ik I think it is a little less bright than
~ftt the last observation. It is 13th magnitude.
Sept. ir. 7465, 13^ 50™. Eyt^piece 700. I can see the
nucleus occasionally veiy distinctly. It ih 13th magnitude. I da
not think it is any diflferent from the few hist observations. It is
much less bright than the star />-
Sept. 22. 7476, 13^ 20"^. Eyepiece 700. I can feebly see
the nucleus. I think it is faint to-night. It is 2 magnitudes or
more less thati the star //. I think there is no doubt of its
Tariability. The seeing is fuir, 2 or 3.
Oct. 13, 7497, (o*^ 55'". I can scarcely see tbe nucleus, and
then not distini^tly.
Eyepiece 700.
Oct. 30, 7514,
thing about the nucleus
It is several times fainter than the star h.
f 30"
The seeing is too poor to tell any-
Nov. 13, 7528, 9'' 5*". The nucleus is very faint. It is
I J magnitude les^ than the star h. If as bright as I have seen it
BO me times, it ought to be quite bright to-nigh t» Seeing 3^ fairly
good,
1907 July 2. 7759, 14^ 40™* Eyepiece 700. I can see the
nucleu?? fairly well, but the sky white from the moon. Nucleus is
13th magnitude. Seeing 3-
Aug. II. 7799, 12^ o™. Eyepieces 460 and 700. I can
feebly see the nucleus. It is very faint and pale, and cannot be
steadily. Cannot see it any better with eyepiece 460.
3
Atig. 13. 7801, 11^35"'. Eyepiece 700. I cm possibly see
traces of the nucleus. It is very faint. The seeing is poor, but the
nucleus ought tn be seen easily if as bright as it has appeared some-
times. Of course I always test for the best focus on this nebula.
"With eyepiece 460, with the best glimpses, the inside of the ring
is dark, and I can pi^rhaps feebly see the nucleus. Seeing 2.
Aug. 20. 7808, II*' o"». Eyepiece 700* Can faintly see
tbe nucleus. Perhaps it is somewhat brighter than at the last
obiiervatioD (f),
Sept, I. 7820, io*» $$^, Eyepiece 700. Cati %%& vV^e^
470 Pnj/; E. E, Bi%imard, TJu Variability a/ the LxniL(S^
DUclt^ufi quite eaaily. It may be 13th magnitude. I thiDk ixi»
brighter ihau usual. Seeing 2.
Sept 3. 7822, 13*^50*". Eyepiece 700. Can see the niideUB
diBtinetty, but it is famt, say 13} or 14 magnitude. Seemg
a or 3.
Septs. 7S27, 10*^30*". Eyepiece 7 oOt Caii eee the nucleus
once in a while, but it is very faint. Seeing 2.
Sept. 10. 7829, 13^ o"*. Eyepiece 700. Can see the nucleus
but it is faint : perhaps not so faint as previously. It is liai^i td
aee, aa the seeing varieH so. The sky h thickisb.
Oct, I. 7850, 10^ 40"*, Eyepiece 700. Can see the uuciea*
very faintly. Seeing 2.
Oct. 4, 7853, 8'* 30™, Eyepiece 700. Can ««ee the tiucleua
faintly. The seein}^ i« too bad to make much out of it,
Oct 13. 7862, 10** 10™. It isbnght, iithor I2thm8gnitiidt,
and yellowish. I do not think the good seeing is responsible fnr
the brightness of the nucleus. It is perhaps slightly brighter than
the star Ik With eyepiece 460 it is bnght arul yellow. It i» ^^
magnitude less than the star a. It is almost as bright as Uut itai^
perhaps just as bright. It is a conspicuous object, and could be
seen with almost thu worst seeing.
3. 7883, 9^0'
I can, however, see the 3 stars that are north, following ; tbt
fainter ones^ are just visible. A little later ; can see it faintly, but
this does not mean that it i* really faint. Eyepiece 460.
Nov. 12* 7892, lo** 5*". With both eyepieces, 460 and 700,
can see the nucleus. It ia not faint, about as bright as star c
through thin clouds. It would be easy on a good sky.
Nov. 25. 79051 6^ 40"". Eyepiece 460, Can see Ilia
nucleuH, but it is faint, Eyepiece 700. I can see it with thb
alH«% but it is faint. Sky clear. It must l>e li magnitude Icai
tlian when I observed it on the 1 2th. Seeing 2.
Nov. 26. 7906, S^' o"'. It is faint. It h just as it was lial
night.
No7* 28. 7908^ 5** 50"*. The nucleus is quite easy, tBott^B
not bright. I think it is certainly brii,'hter than on Nov. 26. The
seeins? is not any better than on that date. It is iioor. r^cca^ion-
ally the nucteiin conies out quit© distinctly, though much fftmt«r
than I have seen it at times previously. Later : — I can seo it qwt«
distinct and steady at times, and think it is decidedly brighler tlttu
on the 26th. Eyepiece 460. With eyepiece 700 I can ses if
fairly well^ bnt not so good. Seeing too poor,
Dec, 3. 7913, S^ 50™. Can see the nucleus, Imt it is very
faint. Eyepiece 460. I think it is fainter tlian at the last ob«r
vatroa It is fainter than any one of the stars follo^»'iog
Seeing 2.
Dec. 5. 791 5i 7^ o^v The nucleus is faint, but once w> *
while it is fairly dittinct. It is much less than any of ihs^t*''
north, folio win if. Eyepiece 460. With eyepiece 700 it m ^
faint and dfficiuVt.
Nov, %. 7883, 9^ o'**. The sky ia too thick to see the nucleus.
Apr. 1908. NueUm o/tfie Plandary Nehvia KOM, 7662. 471
Dec. 12. 792 1, 8** o'*\ The diau of the nebula ia sharply
outlined all round. It h a beautiful full ellipse* The outline is
faint oil account of moonlight, but distinct^ The faintest part of
Ihe dUc to the ed^e h at the aouth end of the major axia. Seeing
poor. Perhaps there is some haze.
The inner ring looks irre^'ular, and is more square than elliptical.
Tlie inside of this ring is dark, but not black. It is decidedly
darker than the general surface of the nebula outside the ring.
This innt-r ring is greetji^h-blue, and about i|" in thickness. There
b a .suggestion of warmth to the geneiiil dis<:.
The nucleus is faint, (Too nmch moonlight?) Seeing = 2,
It is rather hard Ui see, and is about the brighliiess of c or less.
The south preceding j of the inner ring is fiiiiit. It is hard to tell
ju«t how this axis lies, because of the break in the ring and from
bad seeiiig. Eyepiece 700, Seeing = 2,
Dec. 2;. 7935> 6^^ 20™, Nucleus fairly well seen. Seeing
= 3. It ii3 less bright than either of the three stars northt following.
There is a 14"* stiir in the direction of /i, whoBo estimated position
with reference to the nuileus is P. A. 48"±,dist. 87" ±. There
are neveral faint i» tars about T north, preceding Ihe nebula.
The nucleus is not nearly so bright :is 1 have seen it. The
break in th^ following part of the inner ring is exactly opposite the
break in the preceding side.
7** 20*" the nut' lens is quite bright and easy. Power 700, It
is about as bright jib h or c — perhaps less than these stars. It k
slightly yellowish. The same results with eyepiece 460. Can
feehly see the -^mail stwr in the north, following edge of the nebula.
I think the nucleus is less* than either h or r by, my, ^ magnitude.
It is well seen occasionally. Carefully examined about a. There
is no star n»farer to it than b. The magnitudes of the three stars
north, following, wer-e independently estimated,—
a« ia-6 magnitude.
The uebuia wns compared in tlie finder with ae?eral B.D. stars
near it for brightness. The results were 8-S°», 8 6*". 7'2»". Its ill-
detined condition makes estimates of its magnitude rather uncertain.
Tlie mean of these, 8" 2*", will not be fur out. This, of course, is on
the B.D. scale of magnitudes.
X90S Jan. 2. 7943, 7** o^. The nucleus fairly well seen. It
is leas than 0 by perhaps j magnitude. Seeing = 3.
The notes sometimes aeeni to be conflicting aa to the relative
brightness of the nucleus — where an estimate of its magnitude
would make it brighter than the comparison star, at the same time
a statement is ma«ie that it is Iciia than the star. This can only be
explained V)y the difficulty of making any definite estimate of the
magnitude of the nucleus, which is involved in a nebulous back*
ground, where the conditions of seeing, etc. afTect its appearance far
more than they do that of a star on the open sky.
47^ -' Trof. E. X. Barnard, The VaridSbHUy of ike 1X710.6
Focal Measures o/ the Nelnda and, the Nueleua
Following are the measures of the relative focus of the nebah
and a star. These are readings from* a scale of inches on the
focussing tube.
1899 Aug.
I. The nebula
A star
*S4
2.38
(3) inches
(3) »
Nebula— 4tar +
0-16
inch
Sept.
95. The nebula
Astar
239
2-20
(5) inches
(4) »
Nebula — star +
0*19
inch
Oct.
7. The nebula
Astar
a-49
2*29
(S) inches
(S) .
Nebula — star +
0-20
inch
Oct.
15. The nebula
A star
2 '60
(4) inches
(6) ,.
Nebula — star + 0*26 inch
1907 Oct. 13. The nebula 0*42 (6) inch
A star o'2o (5) „
Nebula — star + 0*22 inch
For a comparison of the nucleus with the nebula and the star
we have —
1899 Oct. 7. Nebula 2*49 (5) inches
Nucleus 2-43 {5) „
Nebula — nucleus + o'o6
inch
Nucleus 243
Star 2*29
Nucleus — star + 0*14
(5) inches
(5) »
inch
1907 Oct. 13. Nebula 0*42
Nucleus 0*30
(6) inch
(5) n
Nebula — nucleus + o'i2 inch
Nucleus 0*30 (5) inch
Star 0-20 (s) „
"^w^X^wa — ^«^w -V o'lo inch
Apr. 1908. Nuckm of ike Ptanctar^ Nehida N,GM. 7662. 473
These give the following final values, weighted by the number
^f measures ; —
Nebula — star
+ o'2i inch
Nebula — nucleua
+ 0^09 inch
Nucleus — star
+ 0*12 inch
The pluf Sign indictites an increaae of focus. From this w« see
that the foou8 of the nebula h o'2 1 inch outside of that for the
star, while it is only 0*09 inch outside of that for the iiuc1gu3»
The focus for the nucleus is 0'i2 inch outside of that for the star.
The ftr-adingg on 1907 Oct 13 were by a millimetre scale od
the eyepiece. They have been converted into inches* The
comparisons have been made with the star a.
The following measures were made of the dimensions of the
nebula and of the positions of tlie axes of the larger and smaller
©Uipsea.
^^^ 1897 Sept 17
fc
These last results are diecordant. It is difhcult, from the nature
of the inner ring, to measure its position aBgie.
Following are the measures of the three stars north, following
the nebula.
For the OnUr Elliptu
.A. MiiJ. Aicli,
Major DiJimeter.
}^niiLir niniiteter.
34 '9
30-64
2^08
3^-4
3i 5S
25-94
329
30*08
as-4i
35-4
2975
»5'83
34*9
30-50
25'Sr
■
Foi' Ihr Inner Ming,
P.A. M«|. AiLii.
Major DlAcneter.
Minor niiinieter
1^7 Sept 21
»♦.
13-58
iri6
28
43-0
..«
..,
907 Dec. 12
54H
15*10
11*32
487
I4'34
11-24
474 P^'of^ S. £. Barnard, The^ VariabUUy oftiu . LXvm.6,
The iSuehus and Siar a.
P.A.
Dbt.
1897 Sept. 17
62-48
5i'3i
from nucleiifc
20
6337
51-52
„ nacleus (?).
21
63-48
51-32
„ nacleus (?).
igcoJuly 17
63-07
51-24
„ nacleus. a=t2^±
1901 Aug. 7
6317
51-38
„ naclens.
1904 Sept. 24
63-20
51-34
,, nucleus.
1907 Dec. 25
63-55
51 26
,, nucleus.
Mean 63*19 5'*34
The Nucleus and Star b.
P.A. Dbt.
1897 Sept. 28
45*68
62-76
Oct. 3
46-33
63*01
1907 Dec. 25
4692
62*12
from centre of nebula.
, , centre of nebula ( f ). 6 = 15"' i.
,, nucleus.
Mean 46*3 1 62 "63
The Xucleus and Star c,
P.A. Dist.
[897 St'i»t. 28
14-81
68*68
Oct. 3
15-47
68*31
907 Dec. 25
14 '94
67*38
from centre of nebula.
,, centre of nebula (?). f = i4»"i
„ nacleus.
Mean 15*07 68*12
Ph(tto<jraplis of the Nebula.
JJuring the years 1899 and 1900 I made some experimental
photogia}>h8 of a few of the brighter planetary nebulae, using a
Cramer Crown plate, which was very sensitive, and a yellow colour-
screen, the same one that had been used in the regular star photo-
graphs. The results, though not entirely satisfactory, were very
gratifying. The great difficulty lay in the very long exposures
that were required. The planetary nebula in Draco, N.G.C. 6543,
could be secured in from twenty minutes to an hour, while the
others tried by ine required several hours, and were then under-
exposed. In the case of setreral of these nebalee remarkable
detailij were abowu \.\va^ \\^\^ wot visible to the eye in the great
Apr, igo8. Nitelem of the Plamtm^ Nebula N,G.C. 7662, 475
telescope, Ei»j>e<jially astonishing wei-e the photographs of I he
Draco Nebula, whi^jh showed it to have a delicate spiral structure*
Among the nebulje thus photographeil was N,G,C. 7662, I0
none of the photograplis of this object was the expoaure time long
enough to bring out all the faiuter ptirts c»f the nebula. The inner
ring ctime out very strong, ishowing the breaka just as I had seen
them ill the telescope and di'awn them. There were some thi^ad-
like line)* (which I have not seen visually) numing from the inside
of the ring to the nucleus. On tlufse photogrtiphs the nucleus
does not seeni tu bp central in this inner ring, but is perceptibly
displaced to the following side, Thtj ntain disc of the nebula is
decidedly uneven in brightness. The north preceding ponion
ia very f»iint» as \9 also the north following aide, but less ao, A
aection of the south following edge is very bright, while the
rcpposite side of the nebula is somewhat nmre luminous than the
[general surface, A section of the north [^receding outline of the
aebiila is lacking for want of lungi^r exposure, Tiieie is evidence
Hn the photographs of changes of brightness in the nucleus.
In all these photographs the plate was placed from J to J of an
[3ch outside the stellar focus, in conformity with my previous
observations, w^hich showed that the focus for the nehuhe is outside
(that for a star. See M.N.^ Ii., January 1900, fmA Antroplujmcal
Jouimal, xiv., for October 1901,
I hope soon to be able to take up this subject Again, with the
large telesco|t6^ with suitable screen and plates prepared hj Mr.
Wallace.
Following is a liat of the photographs,
1900 Aug. 18. Exposure o^' ^^^^, Exposure stopjicd by
atonn. Shows feeble traces of nucleus, inner ring and part of disc.
Aug. J I. Exposure i^' 18™. Sky i>oor. Seeing poor. Faint
traces of nucleus*. Shows iiujer ring and bright spot on s.f. edge.
Aug. 28. Exposure o*' 45'", ISad sky eniling in fog. Shows
nucleus feebly. Only inner ring feebly sho^vn,
Sept. 3, Exposure i*^ 5'". Sky poor,
Sept. 3 (same date). Exposure i** 30^, Seeing fine, sky
The last one is best. They are both strong and show
Hcfarly ail of the nebula. The nucleus is strong in both.
Se|»t. 20. Exposure 2*^ 35"', Sky very clear. Seeing poor.
Shows inner ring and part of entire disc.
Sir John Hfr8cheV« Ohtaermtio'iu,
In a paper containing observations of the nebidas made with
the 2o-feet reflector at Slough from 1825 to 1833, read by Sir
John Herschel before the Royal Society, November 21, 1833, the
following o Vise r vat ions of this nehuhi are recorded : —
** Sweep 183. A line planetary nebula. Diameter 12"; with
B40 beautifully defined, light, rather mottled, and the edges the
east in the world unshapetL It is not nebulovia, Wt VwiiVa ^a \V
476 ?W- ^' ^^ Barnard, Th^ VarCabiltt^ of the LKXllti
it liad a double outline, or like a star a little out of focu^
perfect circle. Has a star i^ear ; pos, 68' 'i, well measured ever tfa
centre of the uebula. See fig* 45.
** Sweep 180. «?B; R; bluish white; 8 or 10' diaui.
has no haze at thn edges, but 1 if it be not enveloped in an f 1
nebulosity (perhaps arising from ghire), and also the star 13
who»e po,**. IB 61*9 and A R A = 4**o. The light is a very littl
mottled, and »*ot ab'H>luteIy planetary. It is — a ^ 7 m. ( aVJ?.-
These BaJteiiiietn of planetary nebutii; ought to be especially atteodi
to,)
** Sweep 204. Diameter iu R A = 2*'o of time. The attemlaut
star is double A =^12 m ; Ii=i3 m., pos. of A — 58*-5; ABA
from centre = 4'*o. The nebula is not perfectly rounds light equil,
but a very little hazy at the ndges.
*'Swe*Ap 189. Kxat^tly 11; 2""^$ of tiiiie = diani. in E A. Has
a ♦ 13 m. pus, 69°'o ; dist, 30" ; the light of the disc is jjerfectlj
equable, and f quals a star 8 ni.
♦* Sweep 190. Exactly R; =a* 8 m; a* 13 m n f; posw = 65^*6
by microm, ; dist. === 30". [iV.J?. — The great discordance in the
measured positions of the satellite-star seemn to arise from the star
being (louble, and taken for a sitrgle one. Whenever this occur
it is a source of error, and shouKl be most carefully guarded agaioil
in all future uhser vat ions of thia interesting object.] "
I have carefnlly t^xarained, with the 40'inch telescope^ th
immediate vicinity of the Kt^ir a— the one referred to by Herschd
as hfing double. Thete are nu signs of duplicity, and there is nal
star nearer than 6. Tins i*trt tinmen t rests specially on observatioa
made 1907 Dec. 25 — ^a good night. From tlie recent meastir
there seerne to be no certain motion in any of the stars a, f*, and <
or the nucleus^
Ohsfi^Hitioni^ with the Rostse Telescope.
Id FhiL 7*ran^, for 1850, p* 513, the Rosse observers, umf
the great reflector, give the following account of their observation
of this nebula : —
"Oct. 31, 1848. Has a central 8|Hit, at moments very dark.
"Dec. 13, 1848. Nothing more, except perhaps that faint
external nnnulus extends further than had been seen before,
"Dec. 14, 1848, Note by Mr Jolmstone Stoney :*— * Thw^^
stars near it, somewhat in this fashion ; showed it to Sir Jamei
South.'
**Dt^c. 16, 1848. Sketches made by Lord Rosse and Mr|
Johnstojie Stoney.
**DeL\ 19, 1848- Drawing con Hrmed."
A drawing of the nebula is given, plate xxxviii, fig. 13. Thiij
es not show any central star.
In FhiL Trans, for 1861, plate xxx., another drawing appeaifi*
Bg, 40, which diffettt vety 'greatly from the first one. This shows
tpr, 1908. Nudem of the Plnndarf/ Ntbtda NJJ.C* 7662, 477
llie central star coHspicuouBly. The ftiilewiug additional no tea are
aUo given : —
"Since the publicatinii ia the Trajisactions for 1850* The
Kutlying pQttioDd in the published sketch ure parts of spiral
ranches. Fig* 40, plate xxx, represents it as seen uii a very fine
ight (Sept 16, 1B52), with a freshly jiolislieil speculum which
efined very sharply, Oct. 2, 1856, All the details iti Mr
fSt^jney's drawing very well seen. Oct, 16, 1S57 [J.D. 2, 399, 604].
The spiral arms and the '♦^ m centrts distinctly seen."
The drawing referred to shows a nearly round dhc with a
^brighter spiral arrangement commencing near the edge and ending
^kear the central star. This lit^ht spiral m outlined by a dark
^Bhading, or by a parallel dark spiral, I do not lind any reference
to previous observations of the nucleus by the Kosse observers,
though, from the last sentence <iuoted, they seemed to be fanultar
with the star.
I
Other Oliset^vations*
^ Professor Buriihanj (Pub, L.O., ii.) measured the central iittt
on two nights with the 36-inch telescope i
189078 .63'*9 5i"'84
rhe central star was 15th magnitude and a 15™. He also gives
ire« by 0, Struve :
1847-86 6r-3 s^-Ss
^u:h€
w
^P Struve could not see the central atar. His measures were,
"therefore, referred to the centre of the nebula. -
Volume 13, Annals of the Harvard College Observatory,
pp. 80-81, contains some observations of this nebula by Winlock
and Searle about 1866, Coiohining their various measures nf the
dimensions, etc. of the nebula we get — -
k
P,A. major axia of the nebula 47" ±
Diameter of the major axis 2'j"'4±
Diameter of the mioor axis 24''*4±
Some of the notei* in these observations are :^" Edges as
^definite as Jupiter's, Two other observers also considered the
olour to be green, much deeper under illumination tban uithout
Two edges seen . . , , as of a brighter nebula placed over
n dimmer one. The brighter and fainter ellipses have major axed
slightly differing in direction ; the brighter having the position
angle of its major axis 10' to 15" the larger (J. W. obs.)
20* to 30" according to a less careinl estimate by G, M, S,, to
whom the northern side apt>eanj brighter; appearance to J. W,
Ihat of a hollow cylinder with one end turned nearly towards the
robaetver/*
478 Frof. K £, Bavmird, The VatiahilUy of the txvial
Searie and Winli^k also measured the position angle arj
distance of t!ie star a on two nights in the last part of iS66»
P.A. 62*7 DUt 52" 14
The central atar was not aeeu at any time.
thef 1
m
The Pi'ohable Pmiod of Variaiiim,
An iuveetigation of the observations seems to gi^e a period
the variability of the nucleus, or central star, of about 2B da;
The observation t>f 1906 Sept 4, however^ does not seem to fit
with this period »
I give below some efforts to determine the period, utUising the
early Hosae and Lassell observations in connection with my own.
In general tii« results imply a period of 28 days. It is my
intention to ft>]bw the variations of the nuclena more closely, and
to determine accurately the |>enod and tht.^ light curve. I thiok
this is the fimt case in which the nucleus of a planetary or other
nebula has been shown to certainly vary in its light It is
my intention to follow up some of the other planetary nebulie,
there are one or more cases where I have suspected variability
the nuckns.
If we take the observation of 1907 Oct- 15 and combino it as
below we shall jj;et the following results i —
Takin'j; the *ibservation8 of 1900 July 17, with an interval of
94 periods, we shall have the period 28*1 days.
If we use the obsflrvation of 1901 Aug. 7, with an interval of
80 periods, we shall have for the period 27*9 days.
If we combine the observation of 1904 Aug. 27, with an
interval of 41 i^riod*?, the re^iult ia period, 27*9 days.
If we use the observation of 1904 Sept 24, with an interval
40 periods, we have period, 27*9 days.
Tlie observation of 1906 Sept 4, with an interval of
periods, ^vea a period of 28*9 days.
The ohservation of 1906 Aug. 11, gives, with an interval of
periods, 287 days,
In Memoirs of th** R.A.S., vuh xxjEvi. p» 51, Lassell, p
observations of this nebula with hia 4-foot reiiector at Afalta on
1862 Oct 23 (Julian day 2,401,437).
** Central point not stellMr, bat apparently a very miniit*
planetary disk of a blnisb colour The central point u
bright and conspicuous, not to be overlooked even in a curfory
examination.''
Assuming that the nucleus was at its maximum bri^jhtness it or
near this observation, by comparison with the observation of 1904
»Sept 24 (J,D. 2,416,748) when it was at or near maximum, we
liave an interval of 547 periods, which gives a period of 28*0 dajTf.
If we comparts ihva observation with that of 1906 Sept. 4 (J,D.
[pr, 1908. NucUitM o/the Plansiary Nebula KG.C. y662. 479
\
2»4i7,458), 579 periods would have elapaed, which would give a
period of 27*7 days.
Or taking tlie obBervadon of 1907 Oct. 13 (J,D- 2,417,862),
when it was eyidently close U) nmxitnnm, there will have elapsed
587 periods from which the period derived is 280 days.
For some reason all the com i^ari sous with 1906 Sept. 4 give
discordant results.
The Rosse observfttion of 1857 Oct. 16 (J.D. 2,399^604) was
undoubtedly at or ttear innximutn. Combining tlib with my
observation of 1907 Oct, 13, assuming an interval of 652 periods,
^e 8hall get a jFeriod of 28*0 days.
The accom]>ariyitig drawing of this planetary nebula (Plate 12)
was made mth the 40-inch refractor. I thmk it ia a fair repre-
sentation of the object,
In a paper read before tlie Royal Dublin Society ( Transaciiam,
voL ii. (Series ii.)) on Feb. i8^ 1878, the following additional
uotm from Lord Rosse are given : —
** 1848 Oct. 51. Has a central spot, at moments very dark.
Dec. 13. Nothing more, except perhaps that F external
t animlus extends farther than had heen aeeu before.
I D«c. 15, 3 St, near it. Showed it to Sir J. South.
^H T^ec, 16. Sketohes nmiie by Lord E. and myself,
^P D©c. 19. Drawing confirmed, [P.T., 1850, plate xxxvii,
IP^fig. 13.] This should be plate xxxviii.— (E. E. B.)
1852 Sept. 16. Very tine night, freshly polished speculum
urbich defines very .«iharply, Drawing made [P.T. i86i» plate xxx.
fig. 40], In the figure iu F.T., 1850, the outlying portions are
parts of spiral branches.
1856 Oct. 2. All the details of Mr. B, Stoney's drawing very
well men by Ixjrd K. and myst^lf,
1857 Oct* 16. The spiral arms and the star in centre
distinctly seen.
1872 Oct. 7. Modemtely well defined, an outer F atmosphere;
darker in the middle about the spiral.
11873 Aug. 20. Has a *i3 m in Pos. 244*'8. Dist. 46"*6.
Sej
Ft
Dii
Oc
Sept 28.
Na
Pos, 356-1
)i 309'!
61*2
Dist,
(4).
44*3-
From a to limbs, me^i 64 4
Distances measured by Lord K,
a to far limb
a tf) near limb
a to centre
67*2
40'5
5i'3
/?«y^ 16 m.
hy C [Dr Copeland].
64 "2
34*1
48.9
Oct. II. *8m. Pos. 8o'o (3).
3 St. near [y]. Pos, i4°-2. Dist
Certainly no conspicuous nucl. (xxxii. obs*).'^
Dist. 498" '9 (2). Faintest of
from lirabs 82''-i and 5i'''2,
48o Nucleus of the Planetary Nebula N.Q.C. 7662, txtm6,
The position angle 244*^8 is iSo"* too greats It sbould be 64**^
for the ujeasLires can only refer to the stav a. The distance is too
small*
A sketch accompanies the notes with the great refiectori p. 174*
This shows the nebula and three stars- a» j9,y, fbllowing it, I bm
identified these stacs with mine, as below ; —
y = €
I have computed, for comparison, the poaitiun angles and du-
tances a /3\ /3 y and a y from my measures, Tbev arc :—
K««tda*]aR-ri
alSiab) 3587
l^y{be) 309^2
ay(ac) 3267
35'59
5^*30
-2-6
-01
+ 55
I ilci not think thi^e large residuals ittdicate imy real chiknge
relative pusitions of the atar6« In this eai^e^ the position «uig)w
the large rellector seem to be fair^ but the distances ma»t be ~
with verj serious errors.
It will be seen tliat the presence and absence of
star, in the Rosse observations, ore strongly attesta*! ^
of 1857 Oct, 16, and 1873 Oct^ 11,
mgSrJ
1908 F^^ntary 6.
/VSV, 1908 April 21.— In relerence to the variability of ihl
nucleus of the nebula N.G.C, 7662, I hnve carefully gone over ill
the literature of the subject, and in no case has there beeo itjr
suggestion of variability (outside of my own suggestions), Theri
does not seem tu have been any suspicion, eveii^ of variabilitr.
Lv NoTrcEs or R A.S
The Planetary Nebula N.G.C. 7662.— Drawn by E, £. Barnard.
i^he lialF-tone is tcxj bar<ib. Thm causes the aetitral tlaikiiess to be n little too
J wktive to tbe ^'fiieral disi% It abu makts the bricht, inntr ring loo briglit.
touth |iortion of tlii^ rltj^ slioukl be uhadi:>d or ^^li^btly ilarkenedi sa the north
(a is iQniewhat Ibe bright^'st jian of the ring.— E. E. B^]
^
Apr, 1908. Note mi Variable Nebula in Avdromeda, 481
Note on ike Period of Vanation of Barnard'^ Variable Nebula
in Andromeda* By Professor H. H. Turner.
At Professor Barnard's request, I add the following note on the
period :^ —
Selecting the well-determined maxima showa m the first
column of the following' table, the intervals can be represented
by multiples of 27 J days, as shown in the next three columns*
Id the last columti is shown the approximate alteration of period
when the multiple La altered by one whole unit.
Epoch of
MaxliiiLuu.
Interval
Pfdoil.
Multlplf).
Dllt. far
2401437
(Uasell)
d
1833
1 378 1
_
d
27'36
27 "34
X
X
67
S04
d
0-4
0*05
241521$
5604
6720
386
—
27*57
X
f4
2'o
II 16
28
„
2722
2S
X
X
41
I
0-65
6748
7414
7458
7862
6S6
24 *
^
27 "44
24
X
X
25
I
I\>
404
i^
27*0
X
'5
2*0
2644 = 27^26
97
It is clear that the long interval of 13781 days is of little use
for defining the period at present ; but Barnard's observations and
the interval between Kosse and Lassell give about 37^ days.
But the last column shows that, since all the differencea are
approximate sub-multiples of 2 days, periods of ig'j or 25 '3 days
might suit the observations. Below are given the corresponding
figures : —
ittrvftj.
Hiiltipb.
Period.
Multiple.
Period,
1^33
=
62 X
29*57
=
72 X
25*46
386
-
13 X
29-69
=
15 X
2573
1 1 16
^
38 K
29-37
=
44 ^
25*36
686
:=
23 X
29-83
-
27 X
2541
404
—
14 X
28 '9
-
16 X
2S'2S
4425 = 150 X 29-50 ^ 174 X 25-44
The accordance for the 29 day period is, however, not good*
The periods 27 J and 25J days divide approximately into iSS^'^^>
482 Bev. J. Stein, Corrections to Prof. Tum§r^$ Paper lxvnL6,
80 that at the same time of year they ran together nearly jEor
several sacceediiig years.
Hence the observations do not readily discriminate betweea
them; but those at 2416820, 241 7 176, and 241 7 178, when the
nucleus was faint, seem to favour the 27^ day period, since th^
make the epochs 10 or 12 days away from maximum, while the
25^ day period makes them close to maximum* Professor Bamaid
proposes to make further observations to settle the question. :
Corrections to Professor Turner's Paper " On the Clastifieaium (/
Long-period Variable Stars, and a possible Physical Inter-
pretation." By the Rev. J. Stein, S.J., ScD.
{Communicated by Ftofesaor H, H. Turner, D.Sc, F.JLS.)
[My best thanks are due to Father Stein for pointing out ihe
corrections noted below. According to the general permission giveu
in the last sentence of his letter, I publish it at onc»». — H. H. T.]
Specola Vaticana, April 3, 1908.
Dear Professor Turner, — Lately I have studied your remarkable
article on the " Long-period Variable Stars " {M.X,, Ixvii. p. 332).
My interest was the greater as this is the first serious attempt
to bring the lonj^-period light-curves in close relationship to the
laws of sun-spot variation.
I take the opportunity for suggesting some ideas by which the
number of possible cases in your hypothesis may be still more
reduced.
i". Is there not a little oversight in your paper on page 345 1
There it is said —
"The mean (foreshortening) factor for the spot may be taken aa
JcosfrfZ- . . . ."
Should this not be
JcosiidZ
jdZ
Then "the total eifectiveness ** would be (top line 0/ page 346}—
8 = — (4/? cos € sin \ -h 4 cos /8 sin c cos X),
27r
and in the " polar view " —
djs8inX(as correctly stated on page 342, line 6; but not tf
incorrectly ou pa^e i^fiY
" On Lo-fig-pei-wd Variable Stars,* etc
483
\ tbe ** equatorial view '* —
t^m - DOS X (im^iead of 4 cm K on p, $4^)*
Thus J, = .%, for tan X = - , or
w
and X^ is defined itdthoui any amhiguity^ Buch aa is contemplated
on p. 348. Of course, if we take a broad belt of auo-spots instead
of an infinitesimal one, X^, will be slightly different from the given
▼alue. In. the extreme case, when the whole sphere is all over
coveTed with 8pot8> the mean foreshortening factor will be
(Disc)
-=v— ^ -r^ — ^. = A, and X( =X«)=*3o', The variation of X. being m
(Hemisphere) -« ^ t' *• t^ d
alight, we can practically put X^ = 30' for all cases.
2^ The brightness at maximum being from 40 to 100 times
that at minimum, it seems verj^ probable that at maxim nm the
wh*»le surface of the star is in activity and covered with facula.
This may be confirmed by what we know of the " polar type " of
the Sun's corona at maximum, when the streamers are numerous
in nearly all solar latitudes (i/..V., Ixiii. p, 482), in opposition
^ the "equatorial" L*r " wind vane type " at minimum. In this
Kpotbesis tht^ maxima of polar and ''equatorial view^' nmat
ficide, and tliis would seem a new argtiment for the more pre*
ferable ** hypothesis of superposing niaxima,"
If these remarks are right, it follows that the latitudes given
<>n P*g® 34^ for X^, = jo'* are the most probable.
Now, starting from the equation B = ^F, we can calculate F.
Subtracting the numbers of Table III. Group L (the " polar
view group") from unity, and multiplying by i"6, we get
Max, 3 ^ 4
l<Hg *i ? = r6o 1 '39 '99 ^3
lc^9iziA-97o 9*62 9*45 9'2S
Ifl^F =1-90 177 1-54
W^ = 79 59 35
Bin
567a
9
XO tl t«
•21 ^OQ no *4?
'96
ri2 133 1*44
13 9^19 9"5a 9-91
9^99
•00 9-99 9*93
9J
'35 ro8 o'Si 038 0*57 0*97 ri2 1-34 1*51
22 12 7 4 4 9 13 22 32
54^
u
'9^
79" ^2" 78* 58"
hypothptical law suggested by these numerical results can
ly be hfetter expressed than in the words used by the
ronomer Royal for characterising the sun-spot phenomena from
1S74 to 1902 (Af.iV., bciii, pp. 452-3). We have only to omit the
words between brackets: — . . . "The years of maximum s^howed
apots in practically every latitude [between 30* N and 30" S]. In
the years following the maximum a marked tendency was shown
for the 3[»ots to appear in lower latitudes . , . . about one or two
years before minimum no spot^ were seen outside the limit of iS"
m the equator. But immediately minimum was reached l\x^
484
Mr, James X, Hcott,
LXVI1J.6.
spots became iDore widely extended in latitiide, owing to tlie occur-
rence of outbreaks in high latitudes. Thas at minimum each hemi-
sphere, considered separately^ showed two clearly defined spot-zones
marked off from each other by a broad belt in which there were
no spota at all Of these tw^o spoUzones in eacli hemisphere,
the lower appears to correBpond to the series of spots of the
expiriDg cycle. During the periods of increase the equatorial bell
was almost wholly free from apot^, indicating possibly the com-
plete disappearance of the last membt^rs of the old cycle. At
maximum, however, the spots of the new cycle were most widely
spread, and were even seen in the near neighbourhood of tbe
equator . . * . '*
FiDally, I wish to tender you my sincere cougratulatioiw on
your original interpretation of the long-period variatioD, and lo
express the hope that n^y little remarks may contribute to enbaace
its evident pi sue i bill ty.
It goes without saying, that jou may dispose of these remarks
at your own pleaaure.^I am, very faithfully yours,
J, Stbik, SJ.
Measures of Southern Double Stars in 1907. By James L, Sco^
The following measures of southern double stars were made with
the same 5-in, refractor as those in M.N.^ vol. Ixiv, p. 52, bright wire
ilhimmation being used throughout. The weather during 1907
w«B, on the whole, distinctly poor, cloudy nights and bad definitioa
being the rule rather than the exception ; the number of sUn
measured was therefore smaller than usual
star'! Nftme.
2 3063
R.A.
h m
0 2
8. Beo.
5 6
2lS'0
Diatuce.
I'^S
Si 10
3 ^4^
0. StoDe 51
0 2
1454
28S'6
9 '88
9
9
W
& 3<^i t^i Sculptorift)
h 337S
0 3
029
2832
3532
270-8
1663
115
6-05
61
64
9
•m
0. Stone 3
047
23 9
267*2
2*10
H
91
"m
^3407
U 1662
048
053
2531
16 13
214-8
lyio
6'so
7
S
7i
H
h 2036
I IS
t5 20
lyi
r4«
7
n
w
T Sculptoria
I 32
3025
972
190
6
7
w
5 231 (66 Ceti)
H»s tings I
208
2 II
252
1S42
2320
3561
16*05
2'0l
5!
8
8J
SI
S Eridftni
254
4043
86*1
8*46
3i
41
•9S)
A 3750
516
2\ 20
279 '8
3*50
4l
9l
nU
A 3752
SiS
aAS2
1027
m
5i
71
^iH
^^^^^^m, . Measures of Southern Double Stars in
1907"
IP^
SUr't Nume,
JUA.
S. DM}.
PA.
DiitAiice.
Magi. Nlghy
^H
Ii m
602
25 i
295-0
474
8i
84
2
T907* ^^1
A38SS
622
34 59
316*6
375
7h
H
2
^1
h 393S
7 9
2242
249-2
19-50
7i
H
2
^1
2 1104
7^
U47
333*6
230
7
9
2
■
^ 3973
726
2040
38-4
8-90
8i
9
2
^M
0. Stone 18
« 5
26 50
261*2
3*32
8i
9
2
^M
Dunlop 63
S 6
4221
80 '9
5'SO
7
8
2
■
y Argua {A & B)
8 6
47 3
219*8
41 '52
2
6
2
^H
(A&C)
...
1487
62*11
2
8
2
^M
A 4093
823
3843
1227
8*03
7
7i
2
-260 ^1
Howe 23
9 3
31 J»
307^2
3'3«>
8i
9
2
^1
f* 4i93
9 12
2242
iiSS
3 "05
S
10
2
^^^H
H. a Wilson
9 16
23 3
36-9
130
7i
9l
3
^M
C, Antliff
9 26
3127
2I0'2
820
51
64
2
^H
A 4324
932
3047
ti7*3
7x>o
8
9
2
^1
C. G, a I3J22
9SS
1730
274-0
20*02
64
7J
t
^1
Howe 15
10 58
2658
338-2
Z'lO
75 9*3
3
^1
17 Crateris
11 27
28 43
209'3
8-88
5^
5h
2
■
A 4455
1132
33 1
244-0
3-80
6i
9k
2
■
a a c. 15,942
Ji 35
3730
95*8
16-50
7
9
t
^M
A44SI
u 5*
21 59
197 '»
330
8
8
2
■
A 4495
12 0
3223
316^8
^-60
64
9
2
■
CL o- a 16,612
12 4
34 6
202*5
375
64
9
2
H
Jacob 8
12 s
34 9
20-3
3-10
6i
9
2
^1
S634
12 6
j6 14
285-5
6-67
7
9
2
■
D CentAuri
12 9
45 10
242-4
3^8
5i
7
2
^1
A45i«
12 19
4050
207*6
to-10
6i
9
2
■
B Conri
1225
1558
214*3
24*45
3
84
1
^M
2 1669
1236
12 28
306*0
570
64
64
2
^H
y VirginiB
, 1237
054
326'S
6-01
3
3
3
^1
A 4556
'2 49
2725
80*0
, 6*50
7
^
2
^1
0. Stone 37
12 32
12 36
66-9
1*95
^
n
2
■
A 4563
125s
33 5
236x1
6*82
7i
Si
t
^M
h 4587
13 20
4232
86-3
5-20
8
8i
2
^H
0. A. 12,867
tj 21
2243
356-2
r6i
8-8
9
2
H
0iH
1329
8 6
143X)
1-50
8
8
2
H
A460K
1336
3328
177-5
4*60
8
81
J
^1
A 4617
13 45
2923
2608
505
7i
9h
2
^1
^343
1346
3^ 7
1180
1-03
6
7
3
■
K CenUuri
1346
32 30
109-5
8*17
a
^
\
^1
486 Mtasfwres of Southern DovhU Stars in tgoy. wnn 6,
Ster'iNftme.
R.A.
S.I>ec.
P.A,
DMuoe.
Mags. Higlili.DMta.
h m
• *
•
M
1997.
Howe 26
1349
3137
"5*9
6*40
7i
10
t
•4S5
A 4661
14 6
3«35
230-8
4-48
9
9
2
•48t
3I1B37
14 19
" 13
300-4
1-40
7
8-5
2
•4«2
Howe 29
14 31
37 6
«3'4
4-25
8
H
2
•4«5
A4690
14 31
4542
a3-6
19-50
5i
8
I
•501
54 Hydro
1440
25 2
130*2
8-71
Si
7i
2
4k
fiio6{Ak B)
1444
1344
341*4
I-60
Si
64
2
•4*5
P XIV., 212
1452
2057
2968
17-35
6
7i
2
•482
h4722
1453
30 18
340-4
8-65
7i
9
2
•501
6 239
M53
27 16
316-8
0-90
6
64
3
•485
h 4727
1457
27 26
2167
7-38
H
8J
2
•482
3 119
15 0
637
300-4
1-60
8
8i
4
*Soi
h 4743
15 I
3232
1969
11*19
71
71
2
•485
Howe 31
15 7
3652
468
6-50
71
71
2
•485
A 4776
1523
4134
228*6
552
7
84
2
•501
A 4783
1525
1948
2801
1 1 05
6f
84
2
•49S
Howe 37
1536
1428
907
5-43
8
8
2
-490
77 Lupi
J5 53
38 7
20-4
15-30
4
8
I
•490
Lai 29,720
16 13
1949
21 '2
13-18
8
81
I
•501
(T Scorpi
16 15
2521
2727
20*60
3
74
1
•5S3
h 4845
16 17
41 01
135-6
2*IO
8
84
2
•548
A 4848
16 17
3258
153-2
5*90
7
74
2
•501
h 4850
16 18
2928
350-8
630
6
64
2
•501
p Ophiuchi
16 20
23 13
355-2
3-40
51
61
2
•501
Skinner
1639
17 8
86 -o
3-50
8i
84
2
•605
P XVI., 236
16 51
1923
231-3
4-80
71
84
1
•583
2 2119
17 01
1348
192*2
2*20
8
8
2
•548
36 Ophiuchi
17 9
2627
187-8
4-18
51
54
2
.548
iB958
17 10
19 14
2138
1-55
84
9
3
•54*
38 Ophiuchi
17 II
26 31
337-6
5-68
6i
9
2
-548
)8 4i6
17 12
34 53
273-0
2-30
6
8
4
•559
fi 126
17 14
1739
262 '5
2*00
61
81
2
•559
2 2204
1740
13 16
24*3
1410
7
7-2
I
-583
^5003
1753
3015
104-8
5-25
6
7
2
•605
T Ophiuchi
1757
811
258*2
I 94
5i
6
3
-559
Howe 50
1759
3635
2-6
3-05
71
81
2
•583
70 Ophiuchi
18 0
233N
1647
2*61
4i
6
4
•559
6 245
18 4
3045
353-5
4-15
6
8
2
•643
VNI25
1823
25 6
I0I-6
3-01
7i
7f
2
<05
S715
1912
l^WJ
1^-6
8*30
71
74
2
^
Apr. 1908. Adopted co-ordinates ofBomhay Ohservatm^y. 487
dUri Nmme.
R.A.
S.Deo.
KA.
Diitanca.
Ma«i. Nlghti.
Dttta.
ti m
, ^
•
^t
1907.
A 1381
19 12
16 10
1957
4 95
8*1
8'3
2
•698
^142
19 22
12 21
343*6
I-60
8
8
•698
Ho, 462
2059
II29
218*5
255
9
9i
•832
A 5252
21 7
1525
318-2
3-02
8
8i
•83a
C G. C. 29,658
21 35
1853
660
5 TO
8
9*4
'846
19 Fiscia AuitraHa
2155
28 56
11 6 "3
174
6
64
'868
^470
22 5
M S
36-8
i'66
8
9
*868
B808
2a 19
20 52
151 -8
7'oo
7
81
797
53 Aquarii
22 21
17 15
310^8
6 -So
6i
6i
797
f AquiJii
2224
032
315-*
3-05
4-5 4-6
%2
*Nii7
2234
2852
64*3
3-04
n
84
'871
-y Pi&cia Australis
2247
3324
266 '4
3*56
4i
8i
'871
3300S
4319
9 1
235 '8
3'6o
74
H
'871
«s Aquarii
'3 41
19 14
i3>r^
S'90
5&
7
2
-928
B.A.a 830S
^3 49
2736
269*3
6*90
6^
74
2
•950
23046
23 51
1003
2527
3*18
m
9i
3
•950
Shanghai :
1907 2>r/rm&tfr 31
Note on the adopted co-ardinate^ of (lie Bombay (Colaba)
Observatory. By A, M. W. Downing^ D.Sc, F,R.S.
^" It may be desirable to point out that tbe relatively large change
10 the position of the Colaba Observatory^ aa given iti the Nautical
Alvianac for 1909 and following years, from that given in the
Nautieai Almanac for 1896- 190 8 inclusive, ariaee from the large
difference exiating in that purt of India between the geodetic and
astronomical co-ordmatca, I am indebted to the courtesy of the
Headquarters Staff of the Trigonometrical Branch of the 8urvey of
Itidia for the folio wiug particulars as to the position of the Colaba
Observatory : —
IAatroDomicah Geodetic
I Latitude, 18* 53' 36"i8 N. 18^ 53 46"'si N,
I ,_, ......... .........
It will thus be eeen that the quantities given in the Nautical
Inianaf for 1909 and onwards are the aatrnnomicjil latitude and
the geo«ietic longitude. On the other hand, n|> to ami including
the current year, the quantities given are the geodetic latitude and
the astronomical longitude ; the values of these co-ordinates given
above being later, and presumably more accurate, than those oora-
municated to me in 1892, and which appear in the Nautieai
Unana*^ for the years specified.
488
Mr,J.ff.B^ffuM8,l)uoripiiami(fa LZViiLti^
D^seripUon qf a 24-tiidk long-fociu OcBlodat Bffieetor.
By J. H. R^oldA.
The idea of moanting ai.long-fociiBiefleetor in ooiganctioii witk
B ceeloetat was mentioued by Dr. Common in 1900, and it has ben
aaccefisf ully carried oat at Mount Wilson with the Snow taleaoops
for spectroheliographic work. The present instrument is intendfld
for use with a speotroheliograph which is in cooxse of oonstmctioD,
bnt' it is also arranged for photographing the Moon and planets^ and
COELOSTAT
the brighter star clusters and nebulae. For several reasons it was
found advisable to keep the focal length within moderate limitB;
the concave mirror has therefore been made with a focal length of
38 ft., an enlarging lens being used when a greater scale is required.
The co8lostat is mounted in an octagonal wooden house, which
revolves so as to face the various azimuths required ; the roof
revolves separately, and has a large opening covered with hinged
shutters. The plane mirror, which is 28 in. in diameter, is furnished
with a slow motion at right angles to the polar axis ; this is vefy
useful for getting the object in the centre of thb field, and is pncti-
cally indispensable for lunar work.
[pr. 1908. 24-inch lony-focui Gcd^cU. Bejlector.
489
At the reqaired distance from the cceloslat house a circular rail
hag been fixed for carrying, the concave mirror. This rail runa
from east to south, and gives a range in declination of 37^^
This, of course, is a limited rauge, and is the main defect of this
funn of mounting, especially for stellar and nebular work.
The concave mirror is slightly tilted, so as to bring the focal
plane a little to one side of the i>lane mirror, thus forming a
Herschelian reflector : with the long focal ratio this does not
materially affect definition, and it would be quite possible to alter
the form to the Newtonian if found necessary* For stellar work
the following is done by means yf an eyepiece with double cross-
wires near the edge of the plate, and the plate-holder and screw
motions can be rotated to bring the star trails parallel with the
R-A. scr*^w motion.
For tlie Moon and planets a negative enlarging lens is employed,
and it has been found that with suitable air-conditiuna an equivalent
focal length of 120 feet can be employed with advantage. Although
the resultin^^ photograph is not usually so crisply defined as one
taken in the primary focus, there is an evident gain in detail, and
the disadvantage of '* grain" in the plate is not so obtrusive.
in order to eliminate as far as possible uneven motion in the
instrument, it is intended ^ when the enlarging lens is used^ to move
the plate-holder by means of an oil cylinder, instead of driving the
coelostat. By this means a smooth, continuous motion is possible,
and there is the additional advantage that the concave mirror need
not be moved in azimuth for the ditferent deciinations required, as
it is not necessary for the plane mirror to be parallel with the polar
axis. The instniment is also well adapted for large-scale photographs
of the solar surface.
It has be€n found desirable to cover in the space between the
ccelostat house and the concave mirror with a movable wooden
tube ; unless this is used, the ground air-currents interfere with
good definition.
490 I^v^ «/. Stein^ Dr. Roberts method of ddeimining lxviil6,
On Dr, Roberta vuthod of deiennining titje abaohde dunauum
of an Algol Variable JStar. By the Ber* J. Stein, S,J., ScD.
iCommmmkaUd by Fro/tuor B, B. SfWn^r.)
In an interesting article of the Januftry number, 19061 of the
M,N, (vol. Ixvi- p. 123), I Jr. Alex. Roberta starts from the hjpo-
thesis that the light-changes uf the Algol variables U Pegam and
BR Centauri are fairly well explained by two eclipsing stare moving
in ft circular orbit, and tries to reduce the residoals (O — €) by
applying some correctione to the theoretical light-curve. He sup-
poues that the orbit is passing through the line of sight, and puts—
F = Period of variable in minutes.
c (very small) ^ Eccentricity of Orbit.
k = Longitude of periastron^ reckoned from line of sight
0«True angular distance of eclipsing star from line of sight
at time r,
A«i = Change in magnitude per minute at time T,
l^Tlme (in minutes) that light takes to cross the demi-orbit
At - Correction to the assumed time of paaaing the prmctpal
minimum phase,
p = f ain X, q~€ cos X.
Then^ neglecting the second and higher powers of c, he proceed!
from the typical equation of cotidition —
Am cos 0 -^+ Amain 0 i 7 + Am Aj + A7n|co3 9U+ ... = (0— €),
n n
^^
where p, «/, A^, / are unknown quantities, n= -^ and | ooe 6 \ denal«M
the absolute value of cos 0,
According to the author, the three Erst terms are correetiooi
depending on eccentricity and variation of epoch ; the fourth t«rm
is the correction due to the fact that light takes an appreciable
interval of time to traverse the orbit. (Th« other corrections will
here be left out of consideration.) Kence^ resolving the equatiuD*
of condition after the method of least squares, Dr. Roberts finds k
and consequently the absolute dimensions of the orbit
It seems, however, that the point of departure of this method is
open to criticism. Indeed, the first member of the fundameotil
equation is not the adequate expression of the corrections due to
eccentricity^ variation of epoch, and aberration of light.
To show this, let ui take the most simple case^ — that the two
components are both spherical, and that the nearly circular leiatite
orbit is i)assing through the line of sight. In this case the apptitnt
brightness of the binary system is only depending on the appawat
di&tance p of Ibe cevittea of the two spheres^ as seen from our Son.
Apr, 1908. the dimensions of an Algol VartaUe Star. 49 1
Hence we may put —
Change in nifignitude 10 theoretical Iight-ciiT?e deduced from
circular orbit|
dm dp J V
Am =
dp at
For the purpose of determining the effect of eccentricity on p,
we may nej^lect the aberration of light. Thus, in the circular orbit
o have —
p«=7«eiu«i9 . . , . (2)
r denoting the co^Rtant radius- vector, and $ referring to the star
^1 eclipsing at principal minimum.
Consequently, from (1) and (2),
!^* = 4t/ttan^i- • . . , (3)
dp np
Putting Ap^ Ar, AS ^ the variations of p, r, ft at the time T by
sing from the circular orbit to the improved, eccentrical one,
re find —
^^^+coteA0
Ar
(4)
(s)
— = - f cod (^ - X) = -q COS $-p sin 0
Ad - 2€ sin ((9 - X) + const.
For 6^ = 0 we shall have {AB%-7iAt; consequently
A6 = 2€ sin (^ - X) + 2€ sin X-i-nAt- sq sin $
+ 22) ( I - cos ^) + n Ae (6)
Substituting (5) and (6) in (4),
^P = ,y coa B-p (' -."'^/^Vb cot 6 M . . (7)
p sm ^
Finally, according to (3) aud (7), the adequate variation of
magnitude at the time 7\ due to eccentricity and variation of
epi3ch, will be
k
dm
^ Ap^AniBmB Iq-AmiL^—^lp-^AmAt
dp n cm B n
(8)
Vice verga^ for determining the effect of aberration, we ma}'
neglect the eccentrifity of the orbit, and put —
a,, a^ = the semi axes of the circular orbita of the two compon-
ents tSj^ and S^ around the common centre of gravity,
p„ p2 = the a |i pa rent projections of the radii vectores on the
tangential plane of the celestial sphere at the time jT, this being
reckoned from the moment of principal minimum.
/^, l<^ <T = Time (in minuter) that light takea lo tio%& VV% %^mv
492 Tfte dimtnMiom of an Algol Variable Star, LXtoH
axoa of the orbits and the distance from thtij centre of grmrity to
the Sun,
Then the time taken by the light —
to pass from 5, to the San will be = cr- f^ cos n{T - o-)
„ ,1 S^ „ ,, = cr-f/, cos w<r-(r)
Consequently, putting n{ 7*'-*r) = $:
Pj = aj i sin {$ + n^i cos $) \
Po = flg 1 sin (^ ' «/j COB &) I
where cos $ is to be taken with its proper sign.
The quantities /j and L, being generally very slight, and sifl
P^Pi-\-p2 = a\Bin{B-^n{li-h) cos ^} | , (^
and consequently the correction for light-equation wiU be
Am(l^-i^) coB$ . . . (10)
Thna it would seem thi^ureticiillj impossible to ijctermine th
absolute dimensions of the orbit in this manner. If this stateme
is correct^ it follows tbat the numerical results of Dr, Rob
paper cannot have the interpretation wMch is given to them.
Sptcola Fatkanu: igoS March 19.
Note to Father Stein* i« pap€i\ Ev Professor H, H. Turner,
D.Bc, F.K8.
Thh following elementary geometrical considerations indicate th
reasons why the light-equation fails to give us expected infomii*
lion about the orbit. They were mentioned at the meeting of the
Society in communicating Fatber Stein^a paper, and are added here
as a note at the request of one of the Secretaries*
Consider the three cases— (a) when the mass of the bright body
is so small as to be negligible ; (b) when the mass of the dark
body is negligible; (c) when the two bodies are of equal mass.
And in each case let as suppose the orbit circular and in a plane
passing through the line of sight, and that light takes a time iT
to cross the orbit.
(a) In the first case (fig. i ) the dark liody is stationaiy at tht
centre O, and the bright body revolves round it, and is eclipsed
at A, the Earth being in the direction of the arrow. The ligbt
which snfTers eclipse re^aches O at a time T after th© actual eclipse,
(h) In the second case (fig. 2) the bright body is stationary at
the centre O, and the dark body revolves round it and eclipses it
when at B. Hut the light which suffers eclipse must leavt 0 ii
a time X bifovB the aoluiil «i<iV\^aG.
Apr. 1908. Prof, Tumwr, NoU to Father Stein's Paper, 493
Hence* referring events to the time at which light leaves O
(or more generally the line XOY), we see that iu case (a) the
apparent eclipse ia reianhd and in case (b) it is accelerated by a a
equal ainuunt. What happens in case {c) when the bodies are eqiml 1
- 00 -Y
FlQ. I
It is suggested that there is neither retardation nor acceleration,
f-e* that the apparent eclipse take^ place at the same time as the
true eclipaej and this ia actually the case. It was Professor Dyson
who called attention to this case after reading Father Stein*8 paper
at my request.
X—
— Y
(e) When the masses are equal, they both revolve round 0»
their common C»G, The position for true eclipse is, bright body
at A and dark at B y but the light which then leaves the bright
body does not suffer eclipse, since when it reaches B the dark
body will have moved away* Let aA, Aa, 6B, Bp WIqtqj ^ic^MaN.
494 -P^/ Twrner, Note to Father Stein's Paper, lxvul &
Boiall arci d^ribed by either body in time T which light tnkai
to orow the semi-orbit Then the aequenoe of events is as follows:
Brl^tBodj.
DtfkBody.
(I)
At a
Atft
At a
(2)
• At A
AtB
InXOY
(3)
At a
At 3
Atfi.
The eclipsed light must start before the bright body has reached
A, and is eclipsed by the dark body after it has left B, so that
the position for apparent eclipse is displaced from AB to a/3. Hot
we have no means of noting this displacement in space in the case
of Algol variables. All we could note would be a change in epoch,
and this is zero \ for we see that the eclipsed light leaves XOT at
the moment of true eclipse, when the bodies are at AB.
Hence, whatever the size of the orbit, when the masses an
equal there will be no change in epoch of eclipse due to light-
equation.
In other cases there will be a change of epoch, — a retardatios
if the dark body is larger, an acceleration if it is smaller. Bat
the change will be small unless the masses ar^ yery unequal ; and
it will depend not only upon the size of the orbit, but on the ratio
of the masses, which cannot be separately determined.
Errata,
In Professor Barnard's paper, page 357, line 27,
for Struve read Struve's.
In Mr. Baldwin's paper, page 369 (Table L), the headings of
the last four columns should be, respectively,
d log sin^ I ; Zenith diat. ; Extinction corr. ; AM ;
and the bracket over these columns omitted.
v..
MONTHLY NOTICES
or THB
ROYAL ASTRONOMICAL SOCIETY.
Vol LXVIII.
May 8, 1908,
No. 7
H. F. Newall, Esq., M.A., F.R.S., Pebsident, in the Chain
Captain Richard Algernon Craigie Daimt, D.S.O., Lynalta,
Newtown ards, Co. Down, Ireland,
and
Edgar Odell Lovett, Ph.D., Profenaor of Astronomy, Princeton
University, New Jersey, U.S.A.,
were balloted for and duly elected Fellows of the Society.
The foiiowiug candidates were proposed for election as Fellows
of the Society, the names of the projKrsers from personal knowledge
being appended : —
Warin Foster Bnahell The Hermitage, Harrow (proposed by
Col. G. L. Tnpmaii) ;
Charltja P. Butler, A.}i,aSo., F.R.P.S., Solar Physica Obser-
vatory, Sonth Kensington, S.W. (proposed by William J, S,
Lockyer) ;
William Doberck, Ph.D., lute Director, Houg Kong Observatory,
Kowloon, IClgin Koad, Sutton, Surrey (proposed by Sir
W. H. M, Christie) ;
James Nangle, Technical CtJlege, Sydney, N.S. Wales, Aus-
tralia, and Private Observatory, Tiipper Street, Stanmore^
near Sydney (pniposed by C. J. Merfield) ;
Charles W. Raffety, Wy nnstay, Woodcote Valley Road, Parley,
Surrey (proposed by Richard Kerr); and
K«v. T. J, Williams-Fisher, M.A., Rector of Norton, Atherstone
(proposed by Rev. D. H. Sparling).
Seventy-one presents were announced as having been received
since the last meeting, including amongst othets; — lAfe\i\.. k. ^*
496
Frof, H, U. TumtT^ Aji Etn.'pirkai LXV
Garrett, The Jaipur Observatory and iU bmlder, presented by tiie
author; Greenwich Astro^Taphic Catalogue, voL ii., i6 charts of
the Astrographic Chart of the heavens, and Observations nf tltie
planet Eros, 1 900-1 901, presented by the Royal Observatory, Grt^o*
wich ; I^ofofisor E. 8, Hoklen, Galileo, and other tracts, presented
by the author ; Oxford Astrographic Catalogue, vol iv., presented bj
the University Observatory, Oxford ; Pennsylvania University
Publications, Catalogue of 648 double stars discovered by Professor
Hough, presented by the University ; three lantern slides of the
Corona of {90S January 3, taken by Professor Campbell, preaentad
by the Lick Observatory.
An Empirical Law of Astronomical Refraction,
By H, H. Turner, D,Sc., F.R.S., Savilian Profeasor.
I. The following investigation was origin ally undertaken with the
view of substituting a 8imi>le proof of the law of refraction for
students who could not follow the more elaborate proof involving
the differential equation. But it was a aurprise to find how cloaelj
the observed refraction could be represented with so rough a sup*
position as that of three, or even two, homogeneous shells of atmo
sphere ; and the question was suggested whether, in the present state
of our knowledge, more elaborate hypotheses were really justified.
If a rough supposition tits the facts, clearly it is no proof of the
correctness of a more elaborate one that it also fits the fact*,
2* Moreover, suspitnon of the correctness of existing hypothe^^
was suggested from another direction. Meteorologists are finding
that the temperature of the atmosphere does not follow a smooth
gradient, ma is generally assumed in refraction hypotheses: at a
certain height a wholly unexpected state of things has been found
to exist. According to M, Teisserenc de Bort there is above 10 or
12 km., an "isothermal la3''er** in which the temperature cea-ses to
fall as we ascend ; and the conditions are similar over parts of the
world where the temperatures close to the surface differ widely. It
is difficult to reconcile these results of observation with the bypo-
theses usually adopted in constructing tables of refraction,* It i«»
however, not intended to examine at present the conseqaencaa of
taking M, Teisserenc de Bort^s work into account ; — merely to
show that it may not he difficult to do so when we have fuller
information, without, perhaps, dialocating existing refraction tablci,
3, First let us consider an atmosphere of one Lomogeneooi
spherical layer. Let C be the Earth^s centre ; CM a section of its
surface through C and the star ; LB the section of the boundary of
* I am mdobted to Mr. Saunder for a referenee to a {tap^r by PM>(e«Of
Bakhu^'zeo in Kmiink. Akad. ran Wden> te JmHterdam, I ^K)* J&noary 26;
see NcUiire^ 1907 April 4, \>. 558 ; iti which this discoriUnct* bctweeo obierTib««i
and the aasumptioii ubwalU^ woAft \a ^<t\a«i\aXT»^M bv a concrete fxample.
May 1908. Law of Astronomical Jtejradion,
497
the atmosphere ; ABO the direction of the star's light, refracted
once only at the boundary B. The star is thus seen in the
direction OBD, instead of in the direction BA.
If ^ABE = <^, ^OBC^iff, ^BOL = i:,
_then by the law of refraction
sm <!> = fji sin \j/ . . . (0
and from the triangle OBC
m
Bin f . , (2)
. , OC . ^ I
2 be the ratio uf the height of the atmoBphere to the
^^ radiua.
^H Hence sin (h= -J^ sin l
4, The similarity of equations (2) and (3) suggests a geomofcrical
coaatruction for the refraction which is obvious enough, but which
I do not remember to have seen in print.
With radius describe the circle MGK rouud C as centre
(5)
(fig. 4
Then
sin OGC
sin GOL CG "
C Hence OGC = <f>, just as OBC = i/^, and the refrar'tion is «^ - 1^ = GOB.
5, If now we take the case of two homogeneous sheik o( aXm^-
sphere, we see that tbe refractiou will be represenUA \iy ^^ «vasi
498
Prof. H. H» Turner y An Empirical LZYUL7,
of two angles OjCfii, GjCBj, with a gap between ; the ladii CG,,
CB^, etc. being of constant length, and the angle ZOG being {,
the apparent zenith distance, and generally, if there are n layen,
expressing all the angles of incidence and refraction in terms of l^
we have —
Fig. 3.
Ml
sin lir, = — ; — sin t = — j—\ — xsin t
Ml
sin </>j = -- sin i/^^
Ml
M2
I +
>,,(I +2i)
sin^
^°'^2=7Ti/"^^i=;i;(f^
M2
Ml
sin <^o = — s^in i/r.> = — 7-^--^ — v sin t
sin \l/„
sin <^,.
Ml
'M«(I+2«)
Ml
sin f
sin^
(4)
The notation is tolerably obvious : the radii of the successive sur-
faces of sepamtion are 1 + 2^, 1+22* ^ + 2J3 • • • • i + 2^ ; and the
refractive indices of the successive homogeneous shells are /tj,
fi^' ' ' ' fi-n' ^^ ^^^ '"'*^ ^® ^^® outermost, /x^^., = i.
May 1908, Law of AstronomiecU JUffradiofk
499
6, It will be seen tliat althougli B^ (fig. 5) lies on the boundary
of the first shelly B^ does not lie on the boundary of the second*
The radius CB4 is not 1 +s„ but - (i +z,) ; and if the refractive
2 . ^^ ^ */ ^
index decreases with the height, this i^ leas than i 4- s.j.
Recent meteorological experimeDt^s, howeveTi suggest that there
may be anomalies in the upper strata. If the refractive index for
the r**» layer should increase with height instead of decreasing^ then
CG, would be greater than CB„ and the angle G^CB^ would be
eubtractive.
7. It is of interest to consider whether there are always gaps
between the elements. If the angle B^CG^ vanishes, then <^2^'Ai»
or
/^i(*+^) = ^ti+«a)
(5)
In this case the refractions of the two assumed layers are
exactly equivalent, at all zenith distances, to that of a single
layer with outer radius GB^ = ^{i +z^)f and of refractive index
CGi !+«/
8. Condition (5) may he regarded as an equation determining
fly the refractive index of the shell surrounding the two inner
ones ; and hence we see that, given any ttco homo^jetiemiti spherical
shells of aivwqjhere with atiy refractive indices^ they may be re-
piaeed for purpo^^ej^ of aMrotminical refraction Iry a ein<jh hanuy-
geneous sfiell, provided the refractive index of tfte medium irr^
mediately eurr&umiing them has a certain valuer and in that case
only.
This case must he carefully distinguished from the one in
whicli a really homogeneous shell is arbitrarily treated as two by
an imaginary surface of separation, at which there is no refraction.
In this latter case one of the angles GjCBj or G^CBj wonld be
«ero ; not necessarily tiie gap BjCG.^
9. Attention is drawn to the possibility above italicised, because
it aeemed at first that it might afford the explanation of the curioiit
fact that the rough hypothesis of two or three homogeneous shells
of air can give so good an approximation to our observed refractions
aa below. If it is possible to replace two elements by a single one,
and to continue the process, there is nothing unreasonable in the
exact representation of a large number of elements by a simple
equivalent. But the numerical values obtained do not aiipport this
view, th»* ijaps being wide compared with the thickness of the shells.
10. W« now turn to numerical evaluation of the constants.
The law of refraction in simple enough at moderate zenith distances,
and we shall be chietly concerned with its form near the horizon.
In that case ^, \(f^ and f are all nearly 90*, and it is more con*
venient to deal with their complements, which are small angles.
Let us therefore write
{=9o'-A» ^ = 9o''-y, »|/ = 90*-X,
500 Prof, ff. H, Turner^ An Empirical LXYin.;,
Let a and p be the values of X and v for {"90* or A = o°. Then
from equations (2) and (3),
co8a = :^, cos^-^ . . . (6)
and equations (2) and (3) may now be written,
cosX = cosaco8A, cosv = co8/3co8A . . (7)
In fig. 2, -eiOCH = a and -eiOCK = i8: ^KCH = a-^. The re-
fraction i8r = 0-^ = X-K.
11. In terms of the method usually adopted, we should findonr
constants from what we could learn of fi and z. From the point of
view of this note, we are to determine a and p empirically from
observed refractions at two different zenith distances ; and the moit
convenient Z-D.'s to select are 45* and 90*. We shall confine
our attention to mean refractions ; and it is convenient to have the
horizontal refraction exactly 33', for a reason which will become
clear when we deal with three separate layers. The mean Pulkowa
refraction?, as shown in the second column of Table I., have there-
ore been multiplied by a constant. Hence one equation between
a and fi is
a -/5 = 33' = "00960 . . . (8)
12. At altitude 45'' the equations may be combined to obtain
the usual approximate law of tan Z.D. Subtracting one of
equations (8) from the other, we have
(cos V - cos X) = (cos P - cos a) cos A ,
or
• X — V / a \ A X + V
2 sin = (cos p - cos a) cos A coaec .
2 2
As a first approximation, we can neglect the differences between
X, V, and A on the right, and put ^ = A = 90* - { . If the re-
2
fraction be denoted by r, we have for moderate zenith distances
o • X — V
r = 2 sm .
2
. *. r = (cos P - cos a) tan £ .
So that (cos /i? - cos a) is the well-known "coefficient of refraction"
at moderate zenith distances: and when £ = 45*, tan£= i, and
cos/J-cosa = 55"*7o=*ooo2 70o . • (9/
Hence
2sm - " sm—^" = -0002700-
2 2
May 1 90S. Law of Astronomical Befrctctum,
5or
13. Substituting the vulue of a-/3 from equation (9), we Bud
and since J (a - ^) = 1630
I4« We can now estimate the error of the approximation above,
where A is substituted for — ^. At A — 45*
2
log cos v = log COS 45' - *oooi r8
log cos X = log cos 45* - '000236
/, v-45"-56", A -45'-!' 52".
These differences are found at odcg from a table of log cosines.
Hence
= 45 I 24
(li)
^^kd the accurate equation to replace equation (9) is
^^H co8^ -coa a =^'0002 700 X 1*00041
^m Mu + ^)=i-36'43"-hi'''9
H » 1-36^45^' Bay,
^p .% a=i"53'is" ^=1*20' 15"
^^ 15. If a table of logarithms of cosines to seconds of arc is not
available, we can throw the equation
cos X = cos a cos A
into the form
cos A — cos A. _ 1 - coa a
cos A + cos X I -h cue a'
or tan . tan = tan^ - .
2 3 2
,A — A p. .. . A4^A iX'-A
tan — ^-i-: tlien since — A +
22 22
Pi(Pi + 2 tan A) = 2 tan^ "'{i -p^ tan A).
Pi= -a± Ja^ -h 4^
4h
fi+ ^a^ + 46
only one t<» take ; where a = tan A sec^ - , h = tan-
2 2
2(1 -COStt)
^^ ~ tan A -f- 7tan« A + siu^a
, the upper sign being the
(12)
502 Prof, H, H, Turner, An JBmpirical LxmL 7,
When we neglect ein a in comparison with tan A, the denominator
becomes 2 tan A, and
Pi = (i - cos a) cot A.
Similarly,
P2 = (i -co8)8) cot A,
and r = pi - P2 = (cos j3 ~ cos a) cot A as before.
When sin a is small compared with tan A We have
p, = (l-C08a)c0tA[l-iJ^] . . (13)
and when A =45**
Pi = (i - cos a) (i - 1^ sin^ o)
2 4
= — - -^ to the second order in p^.
2 6
Similarly, pg = cL _ ^ • and to this order of approximation p^
2 6
and P2 are equal to their tangents. Hence the refraction is
p.-p, = (a-/?).^^[l-Ka»+)82)] . . (14)
Since a - ^ is the horizontal refraction we have
^^ Refraction at 45^ ^t±^\,. i(„2 + ^)1 . (,;)
Refraction at Horizon 2 L J
16. Lot us now consider what happens if we have n concentric
shells characterised by
(ai Pi\ (aoM ' • . (^» ^«)-
In each case the horizontal refraction is (a^-^Sr) ; so that the total
horizontal refraction is
(«i-^i) + («.2-^2) + K-ft)+ ..• +K-/3«) = 33'-
Now the division of our shells is somewhat arbitrary. We can
make them all of e(|ual thickness, for instance ; or we can choow
their relative thicknesses so that they have equal refractions at
some specified zenith distance. There is a convenience in making
their horizontal refractions all eqnaly so that
«l-A = <^2-/^2 = «3-i53= . • • =«n-/5n = -(33') • 0^)
n
Proceeding to the refraction at 45", it is
and hence substituting for c^. - jS^ we have
■1^1
■
■
■
■
503
j
■
■
May 1908, Law of
Agronomical Ref Taction.
where k denotes^ as in equation
(15), the ratio of refraction at 45*
^M
to that at the horizon.
1
^M
17, The numerical i
One ShdL
1
^M
-esults for one shell (with a = t
' 53 15"-
^M
/J= t" 20' 15", as in equation (
11)) are
shown
in the thii
■d column
^^M
of Table I., and the discordant
ios from the Piilkowa refractions in
^^M
the fourth cohimn. It
is clear that, tlioiigh th<
3 accoidHnce is close
^^M
as far as Z.D. 60*, the hypothesis does nut lit the facts at all. The
^^M
discordance at Z.I), 89"
ia Dearly 5', or 20 per cent.
^M
Table I.
^M
y ^ Pnlkowft Calculated
'^^ Kufractlon. one Shell.
0— c.
Ititier.
CAtcuUt«d Two Shell!
i.
1
Outer
Sum.
o-c.
H 45 557 557
0"0
9-S
46-2
557
o-o
^M
^V 60 96 2 96 2
O'O
16-3
79'9
962
o-o
^^M
H 70 151^9 152-4
- o's
26*0
1260
152*0
'0*I
^^M
■ 80 305^5 31 rS
- 6*3
53'5
2535
307-0
-i'5
^^M
81 337 '5 346*0
- 8^5
597
280
3397
- 22
^^M
82 376-5 3S8
- 11*5
66
312
37S
-2
^^M
83 4248 442
- 17
77
352
429
-4
^^M
84 486 1 512
- 24
89
402
49 i
-5
^^M
85 566*2 606
- 40
107
466
573
-7
^^M
86 674'2 738
- 64
133
549
6S2
-8
^^M
87 8257 935
-109
177
654
83t
-5
^^M
88 1049-0 1239
-190
260
792
1052
-3
^^M
89 1397-0 1678
-281
470
925
1395
+ 2 '
^^M
90 1980-0 [9S0
0
990
990
1980
0
^M
^H Id column for one shelly
^M
■
15"
logcosa-9'9997643
^H
^m p=i 20
15
log cos
/3 = 9-999881 7
^H
^M In columns for two shells,
^1
^K ai-o'' 41'
0''
lo^ COS oj = 9
^9999691
^H
^^H f^l = ^
3<>
l0gC03/^j = 9
-9999S90
^^M
^^^H
50
lox cos C4 = 9
■9994760
^H
^H 32
20
log COB /^2= 99995735
^M
TtDQ Sheik.
H
^P 18. With two shells we have at first sight
two more
disposable
^H
^^eooitants; really only one*
One of
them
i^ uft^d
V!C^ VTk \)Ck^
J
504
Prof. H. H, Twmr, An Envpiirieal Lznn.;,
aasumptioD that the horisontal lefractioos of the two iheUB m
eqiial, as in § i6. Our four constants o^ » )3j » 04 » /Sj are therafoR
to be determined by the equations
ai-j8i = a5-j8,-i6i' (18)
2A. = «-L±^[i-J(a,« + A«)]+?l±^ (,9)
and one more condition still to be imposed. Inspection of the dii-
cordances for one shell shown in Table I. suggests that we should
reduce the largest discordance to sero^ t.e. shoold satisfy the
observed refraction at 89**. This can only be done by '' trial and
error " methods. It was found useful to form tables of cos a oof A
for values of Ab i*, 2*", 3° . . . lo*" ; and for every minute of are
of a. By their use, successive approximations gave the values
ai = o'*4i' o" c4-2'48'3o"
)8i = o 24 30 /32 = a 32 o
as a close approximation; the horizontal refraction of 33' being
divided into two of 16^'.
19. We must now examine how far these values satisfy the
equation (19). They are close enough for substitution in the
8([uai'e terms. The following small table facilitates this substi-
tution : the unit is '00001.
Table II.
Value of i
»«.
10'.
20'.
30'.
40'.
50'.
60'
0-
I
I
2
3
6
10
1"
14
18
23
28
34
41
2'
48
56
64
73
82
91
3'
lOI
112
124
136
149
162
4"
176
190
205
221
237
254
5* 271 289 307 326 346 366
Equation (19) runs
3" 13' 25" = 32' 45" (i - -00005) + 2* 40' 15" (i - -00146)
= 3^ i3'o"-o"-i-i4"-o.
Hence our right-liand side is defective by 39". Throwing this on
to the second shell, which is less effective at small altitudes, ve
take ai> a trial
Qj = 041 o
/3^=o 24 30
a2 = 2 48 50
/)2=2 32 20
107 I9C>3» ^^^ ^f Astronomical Eefraction.
50s
With these values of the constants the refractions in columns 5 and
6 of Table L were calculated ; and it will be seen from column 8
that the error of their &Qm is small.
20. The question left oirtstandiiig is the choice of slightly
different constants which shall perhaps satisfy the observations at
(say) Z.D. 80-87° i^J^ther better, at the expense of Z.D/s SS^'-qo,
where observations are rare and [wssibly affected by errors of
several seconds. In Table ILL are given the effects of alt«rjng a^
and /ij by 10', and the similar effect;* of altering a.^ and (d., by 10'.
It will be seen that we can, by increasing the constants for one
layer, and diminishing those for the other by an exactly equal
amount, leave the moderate Z^D/s almost unaffected, and at the same
time introduce sensible modifications into the large Z.D.'s,
Table IlL
Chfinge for 10' AUtratwn 0/ ConstanU,
LD.
luucr
Sbetl.
OuUf
SheU.
Dltferonce.
Error
from Talilo I.
45
(3)
(3)
O'OIS
(d'O)
60
(5)
(s)
0x365
(o'O)
70
(8)
(8)
025
{0^0)
So
(16)
Us)
2*2
-i*5
St
^17)
(16)
2 '9
-2
$2
20
18
3
-2
83
33
20
5
-2
S4
26
22
4
-5
85
3*
^3
9
-7
S6
40
24
16
-S
«7
52
22
30
-5
SS
74
t8
56
• -3
89
100
7
93
^z
90
0
0
0
21. The first five differences in the fourth column of Table III.
were formed by a special method ^ as that used for the later ones is
unsuitable. We may for mi>derate Z,D/a simply differentiate the
equation
cos A ^ 00s a cos A*
Thu»
dk _ sill a cos A
da" {t- 008% CO8-A)*
(tan'-^A + sin^'a)*
The refraction due to a thin shell between a and a + 8a at altitude N.
506 Frof, H. H, Turner, An Empirical Lxvnt 7,
is -7. . Sou The change in this for a change Aa in a is .7^ . Sa . Aa:
oa ^ ' ao*
where
cPX tan^Acoitt
5fl?'"(sin«o + tan«A)* '
and when a is small compared with A
—3 = cot A [i - J(i + 3 cot^A) 8in*a].
da,
If we have two shells with characteristics a^ and a^ the difference
in effect will he proportional to
} cot A ( I + 3 cot*A) (sin'o, - sin'o^).
The value of the coefficient ^cotA + |cot?A is given in the
following small table.
Table IV,
Value of C = (icotA + f cot'A) and D=o" -007560.
Z.D.
Alt.
c.
D.
0
45
0
45
2*00
1*
0-015
60
30
8-6
0-065
70
20
326
0-25
80
10
286
2*2
81
9
380
29
82
8
545
4'l
83
7
813
6-1
84
6
1295
9-8
85
5
2240
16-9
The factor for the coefficient C iu our special case is
10' X arc of 16 J' X (siu^ 2° 40' - sin^ 0° 33') = o' -00756.
The vahies of D for Z.D. 82''-85'* are larger than those found
directly in Table III., probably because the approximation used in
Table IV. is ceasing to be accurate ; but the quantities are of th«
same order of magnitude.
22. Table 111. makes it clear that we cannot sensibly improve
the accordance at 85* without introducing a much larger error at
89**. Every 1" of alteration at 85* gives 10" at 89*. Hence we
may accept the constants used in Table I. as giving as good a
representation of the Pulkowa refractions as we can fairly get with
two shells of ^j(\\ia\ Uomontal refraction.
JJIay 1908* Law of ABironomical Bef radian.
507
Three Shells.
23. We divide the horizontal refraction equally into three of r 1',
It is an obvioua convenience to have whole rainiitea of arc, and for
this reason the horizontal refraction was taken as exactly 33' in the
first instance. We nii;;ht have taken 36', which divides by 2, 3,
and 4 ; but some work had already been <lone with 33' before it
was found that two sht^lls would give such a good approximation.
After some few trials, the following values were fouDd to be
near the truth : —
ai = 0 29 o
/3i-o 18 o
a^ = 1 24 o
0^ = 3 14 o
ft = 3 3 o
\
A(ai+/?i) = o 23 30 i(GL2-tp.^ = l 1830 J{a3 + /^3^)=3 830
Hence equation (17) becomes in this case
4 50' 8" = 23' 30" ( I - -00003) + 1* 1 8' 30" (1 - '00034) + 3* 8' 30"
(i - '00191)
= 4* 50' 30" -o"'o4 - i"*5 - 2i"*6
fibowing that the adjustment has been properly made.
*
Faulk V.
Threi' Homogeiiron$
Sh^lU.
Z.D.
lumoit
Shell.
Middle
Shell
OntDioet
Shell
Suiii=C,
o-c.
niir«rcn«e for 10*
Inmost.
MldtHe, Ottttno«t.
45
4*47
15-09
36-14
5570
O'OO
1-95
i'-85
f-85
60
7*67
2616
62-42
9625
0-00
3-56
3*i8
318
70
[2 21
41-34
9S-27
151*82
+ 0*1
5 '30
505
5-05
So
25*3
85-0
196 0
306-3
-0-8
ir3
I0'2
9-1
St
283
94^4
2I5S
338 '5
- i-o
I2'2
111
10*2
S2
317
io6*o
2397
377*4
-0-9
13'9
12*5
10 '9
S3
36-2
1207
269-0
425-9
- ri
l6*2
14-4
11-6
84
42*4
140-5
30SS
48S-4
-2'3
18-5
16-1
11-8
8S
51-0
167-0
350 "5
S68'5
-2'3
22-3
iS'6
12-5
86
635
205-5
4070
6760
-r8
277
21*8
13-2
87
85-0
264*0
477^5
826-5
-0-8
39 '0
28-5
11-5
8S
125*5
362 0
556-5
1044-0
+ 5*0
52-3
28-6
8-2
89
236 5
525-0
629-0
J 390 '5
+ 6-5
83-2
I9'5
2-3
90
660-0
660 X)
6600
igSo-o
00
o*o
O'O
00
34, The results of this hypothesis are shown in Table V., and
from the seventh column, O — C, it will be seen that there is
fair accordance with the Pidkowa refractions. This accordance
ight be improyed ; by use of the differences gweu m VV^ Xwiw
So8
Prof. H, H. TuTTier^ An Empirical LXTm 7,
three columns we could form linear equations to find small oonnec*
tions to the mean radii of the three shells. But the improvement
would be of the nature of a compromise, and would involve —
(a) A study of the accuracy of our knowledge of refractions at
small altitudes. We should have to settle, for instance, what
error at 89* Z.D. can be made to obtain an improvement of i" at
Z,D. 8o\
{h) A more accumte computation of the differences for 10'.
Those given above were found in the way made clear by the
following example : —
j«t
• dUT*
log cos 18' 1(^ cos 10° -^ 9*9933455 =log cos (10' + t6'o)
Jogcoa 39 log COB 10 =9'993336i =log cos (10 +41*3)
37 '7
log cos 40' log COS 10* ^ 9*9933^21 =log cos (10' + 79*0)
and
12-4
The first two lines are formed to find the refiraction due to the
inmost layer (with constants 18' and 29*) for altitude 10*, the
result being 2 5'' '3 as given in the 2nd column. By adding the
3rd line w« find that the refraction of a shell \nth constants 29*
and 40' (each 11' greater than the furmer) is zi'l J ^^ that this
difference lor 11' is I2'''4; and for 10' would be 11 '^'3, which is
given in the 7th column. But in forming differences of differencei
slight inaccuracies arc multiplied, an<l inspection of the figures
near the top of the last three columns shows thiit (since the numbers
are nearly equal for all tJiree shells) we aie really concerned with
ditferenrpjv of tliese again.
For the present^ no attempt will be made to improve the
approximation, and wc turn to some other points,
25. It is of some interest to deduce the heights and refractive
indices of the shells above found emjtirically.
Om SlielL
log ( I + j:) = log sec a = 0*0002357 ^ log i '000544
log ^ = log cos p - log COB a — o *ooo 1 1 74 = log I '0002 7 o»
The '* height of the homogeneous atmosphere '' is thus indicated u
4000 K '000544 miles, or 2*18 miles, which is a good deal smalW
than that assigned by total pressure.
This is not surprising, for in replacing a series of succcidsiyt
bounding; surfaces by a single surface, we should expect the eqiuva-
lent single surface to lie in the midst of the const! tnente. We can
imagine, for instance, a uniform graduation which would bring the
equivalent surface to the mean height, i.e. would give us a ** height
of the homogeneous atmosphere '' just half that assigned by calcu-
lating the total pressure ; and it would not be surprising to find
that the equwalenl svixl^kQi^ ^\o\3\^\ife \ws?«iT than this.
May 1908. Laxo of Adroiwmical lUfraetimi,
509
Two Shells,
Equations (4) of § 5 may be put in the form
Log,
log (i + «j) = log ft|//Jt| + log sec a| - 0*0000309
log Mi//*2 = log (' + ^i) + l^g *^08 /3^ = 00000 1 99
log (i ^Zj) =log ^i//t^ + log sec a,^= 0*0005439
log ^//tig = log ( I + Sjj) + log coa /?2 = o-oooi 1 74
If we put ftg= I, then /jt^ = i -000270, /jt,^= 1*000224.
Number.
1*00007 r
I 000046
rooi253
1*000270
The heights
of the bounding surfaces iu iiultis are z^ =0*28, 5<j = 5'oo.
Three Sheilg.
The method of formation of the quantities has been made clear
in the last case*
Log,
log (i +Sj)^o + log sec Oj = 0"ooooi54
For Jog /JLi/f4« add log cos /3j, o 0000094
Number*
I -000035
1*000022
1000321
I "000097
1*001689
1*000270
„ log(i+£i2) „ log sec aj, o'oooi39J
„ log fxJfA^ ,, log cos ^2, 0*0000412
„ log(i-f^g) „ Jog sec og, 0-0007331
„ log/Ai//A^ „ log coa /ij,, 0*0001175
If we put ft4 = i, we have /Ai= 1*0002 70, as in equation (9).
This gives a check on the work.
Further, /i^^ 1*000248, fig-roooi73» The heights of the
bounding surfaces are, in miles,
/Tj = 0*14, "j = I * 28, .?j — 6* 7 6.
It does not seem likely that these figures can have auy physical
interpretation. They merely emphasise the fact that a sjerious part
of the I'efraction takes place near the Earth, and not high in the
atmosphere. By comparing the columns for the separate shells
shown in Tallies 1. and V. it will be seen how rapid is the increase
in importance of the inner shells as we approach the horizon. In
Table v., for instance, the two inner shells together only give half
the effect of the outmont tit moderate ZJi.'s ; and they do not pro-
duce so great an effect as the outmost until we reach Z.I). SS', when
they surpass and ultimately double it iu the remaining 2' or 3*.
This suggests that any irrtliiencQ of meteorological j>henr>niena on
aatronomical refractions must be sought at large Z.D/s, which is in
accordance with experience. But discussion of such points in detail
cannot be undertaken at t>r6sent.
Summary,
§1 1-2. Introductory.
SS 3-6. A graphical representation of the refraction of a hooiQ-
geneous spherical shell of atmosphere and oi several a\xci\x ^^\\&.
5IO
Messrs, CowM and Crommdin^
hXvnLj,
^ 7-8. Condition that two or more such shellB should be rap]le^
able by an equivalent single shell.
§§ 10-15. Empirical determination of constants for a single
shell from observed refractions at Z.D. 45* and at the hozuon.
§ 16. Extension of formula to two or more shells.
§ 17. Numerical results for one shell The errors at 80*, 85*,
and 89* are respectively - 6", - 40", - 281". The hypoihesisetn-
not be said to tit the facts at all beyond Z.D. 60* or 70* at moit
See Table I.
§3 18-22. Numerical results for two shells. See Table I. The
errors at 80*, 85*, and 89* are reduced to - i"'5, — 7", and + 2**— t
very fair accordance for so obviously rough an assumption. .
^ 23-24. Numerical results for three shells : see Table V. The
improvement is not great, much less marked than before; and it
seems clear that the principal step was taken in passing from one
shell to two.
§ 25. Some numerical values for heights, etc
TJie Perturbations of Halley^s Comet in the Past. Fourth Paper.
TJie period 760 to 1066. By P. H. Cowell, M.A., F.R.S., and
A. C. D. Crommelin, B.A.
We have again to acknowledge the kind assistance of Pr. Smaxt
and Messrs. F. R. Cripps and Thos. Wright in these calculations.
In the last paper, M.N,, Ixviii. 5, p. 378, we found March 27
for the approximate date of perihelion passage in 1066, and
44''*686 for the value of n at that date. For the preceding passage
we used the date given by Hind (989 September 12) for the
purpose of computing the perturbations, and the following results
iudicate that this date is correct within a few days : —
Revolution 989-1066.
Planet.
Limits of u.
Jrfn.
\dts.
p.
Venus
0- 30
330-360
+ -019
- -0035
...
+ 532'
Earth
0- 30
330-360
+ '007
- -013
...
+ 196
Jupiter
0- 90
+ -4535
-531
+ 12S07
90-270
- -2780
-203
- 2905
,,
270-360
- 1 -2940
+ yoS
+ 22
Saturn
0- 90
- 0560
- 23
- 1578
,<
90-270
+ -0754
- 6
+ 1979
,.
270-360
- -2334
+ 7
+ 47
Urann.>
0-360
+ -0030
+ 55
^Mm^
- 1 '^200
"~- 48"~
+ 11155
41 ay 1 908, Pertnrbatiam of Halley*$ Comet in the Past, 511
For this and earlier revolutions we neglect the Neptune p^trtorba-
tions as trifling^ and take those for Venus, Earth, and Uranus from
cunress constTUcted from the results already calculated ; in the case
of Venus and the Kirth the«e curves are for the combined resulta
of the mechanical q a at 1 rat urea and the definite integral Needless
to eay, we do not claim that the results from these curves are
absolutely accurate, but such accuracy is uncalled for, since our
calculated Jupiter and Saturn results are liable to sensible errors
through the uncertainty attaching to our assumed position of the
comet's orbit plane, etc. The resulting value of n at 989 Ia
44' '686 + i"-320 = 46"*oo6, And calculated period in day8 =
- -' - -— ^ = 27928. Now 1 066 March 2 7 - J . D. 2110^00:
46-006 ^
hence the calculated J.D. of previous passage is 2082572 = 989
October 9. This is 27 days later than Hind's date^ a quantity
sufficiently small to confirm his identification. We can reduce the
discordance slightly l«y altering our a^^sumed dates of perihelion
passage, since the observations are not precise enough to fix the
exact day. If we take them as 989 September 15 and 1066 March
25, we obtain from the revolution 989-1066 the values of ?*» 989
45^*969, 1066 44' "649 ; from the following revolution we obtain
1066 44""688, 1 145 44'''920.
The mean value for 1066 is 44"'668, to which corresponds
45''-988 in 9S9.
Proceeding to the revolution 912-989 we first took Hindis date,
912 April I, and we give the perturbations deduced from this
assumption : —
Mevdution 912-989.
Planet.
Venus
ft
£&rth
Japiter
(•
Sattrm
Urums
Oiuiti of u.
CK 30'
330-3^
o- 30
330-360
o- go
90-270
170-360
o- 90
90-270
270-360
0-360
J'
dn.
J'«BX.
-{-'021
- "016
'*oo75
^ -0005
- ngos
•!'-ao64
+ •0966
+ *225I
- '0625
+ -0529
4- *0|02
+ 138
- 73
- 19
+ IS
- 30
-5503
4 7936
+ II
4^6402
+ 139
- 13
+ 148
Sums
+ '3362
-567
+ 949S
Taking 45" '9 88 as tb« value of n hi 989, that id 912 is
45**652, and calculated period in day8= ^^^^^~^^^= 28181,
This gives J.D. 2054367 for the pasaage in ^12*= 912 JxvVj ^a.
.= i&
5r2
Messrs* Cowdl and Crmnmelin^
Lxnn
Thi3 is nearly 4 months later than Hindis diit«, a larger «:[uantit|
than is likely to arise from error in our calculation, and it ib to bt
noticed that HinirB identili cation is antecedently very donblloL
being based only on observations on May 13, 15 : we conclude th«t
it is erroneous. There are vague references to other comets in 913,
but nothing sufficiently precise to serv^e for identification. Thi«
is the first passage, reckooiug back from the present time, thftt
cannot be certainly identified with an observed comet.
Taking the calculated date 912 July 20, we obtain the follow-
ing modified perturbationa, 913 to 989. The value of JrfCJ maybe
taken the same as before.
Ee volution 912-989 revised.
Flatlet.
LlenfU of u.
dn.
j^
Venus
0- JO
+ '0086
-¥ 240
?*
330-360
- -016
...
Earth
CH 30
-f- 003
+ «4
i»
330-360
+ "0005
...
Jupiter
0- 90
-'24AS
- 7026
ft
90-270
^ ^2284
+ 8576
M
270-360
+ •0966
+ 11
Saturn
0- 90
+ •2331
+ 6602
fli
90-270
-*o6S5
+ 69
t#
270-360
+ -0529
' n
Ur*nus
0-360
+ -0JO2
^ 148
SamH
+ '306
^8691
This gives for the calcdated period l^'l^J^^^^^^^l^* ^2S\^
45 682
days, practically the same as before.
Hence we take the date 912 July 19 as approximately correct
for the perihelion passage, this result being from caiculation aloae,
not from obi>ervatioD. As a check on its accuracy, we proceed Jo
the revolution 837-912; a preliminary calculation indicates S>;
February 28 for the preceding passage. It will be remembered
that there is some queation whether the numerous accounts of tha
Tjrilliant object (or objects) that appeared in the spring of thst
year relate to one or to two comets. The date of perihelion passagt
of the eiurlier one, as investigated by Pingrt^, is indicated with
tolerable precision as 837 March i, the agreement with our
calculated date being thus [jerfect. The otlier elements are also
accordant ex^iept the position of the nmle, and it is well knowo
that the indications of latitude in the Chinese accounts are S'm^
what vague, so that this is not a serious objection to the ideotTfici-
.tion, e&pednUy aa l\v^ ^om«ii vras near the ecliptic throughout lli«
^^^^^H
■
■-^^^^
^^^^H
i^^H
^^^^^^^^i^^^^^^^^^l
^^^^^^^^^H
May 1908.
Perturbations of Halhy
8 Comet in th€ Past 5 1 3 ^H
observations,
80 that a email error in
the observed
latitude would ^H
make a lar^e
ftrrnr in the
niide. Hind took the second comet (if ^H
there were really two) as
Halley's, finding 837 j^
Lpril 6 for the ^H
perihelion passage » hut wo
think that the date March i is more ^H
likely to be correct.
■
Hei'olution 837-
-912.
■
Planet,
Llniits of n.
dn.
Jds
■
Venus
0- 30
330-3^
+ '020
+ -0015
+ ^1
Earth
0- 30
33t>-36o
4- 023
- -003
630 ^H
Jnpiter
a- 90
+ '975
-H
+26S92 ^H
■ t
90-270
- 226
-493
^1
ft
270-360
-1-283
-1-707
■
Saturn
0- 90
- "038
+ so
- ro4o ^H
**
90-270
+ 044
'I32
■
IT
27<>-36o
- *oi8
+ 10
+ 8 H
Uranus
0-360
+ '0105
„.
+ ^M
^uma
- -494
•»- 58
^^1
Taking n in g
1 2 as 45"'682 as found above, n in 837
= 46"* 1 76, and ^H
period in days =■='96000-24425 =
27538, whie
ii brings us to ^H
J.V. 2026828
= 837 Feb. 2
y We adopt this result
r as the date of ^H
perihelion passage in 837.
^H
For the previoui passage we have
a fairly firm
standpoint, for ^H
the cornet of
760 was klentitied with
Haliey's by
Laut::ier, from ^^|
the orbit alt
)ne, helore
the intermediate passages had been ^H
determine sJ, h
is date of perihelion pa^tsage being
760 June 1 1 ^H
= J.I). 19988
[O,
^1
devolution 760-
837-
H
FlBni!t.
LtmtU of It,
j^
J do.
I
Veaus
0- 30
+ *ooi
»i*
^H
t»
330-360
-'015
.«*
^H
Earth
0- 30
-006
- 165 H
»»
330-360
-*oi3
.,,
^H
Joptter
0- 90
-•250
-254
^H
11
90-270
+ *oi7
+ 191
^H
»i
270-360
+ 2755
-274
^H
Saturn
o- 90
+ "071
- 90
+ 1995 ^M
«t
90-270
- *on
+ 8a
+ 1529 ^H
*♦
270-360
" -029
- 89
^H
Uranui
0-360
+ 'OHS
+ 360 ^1
Sums
+ 'oss
-434
^H
^_
n 760 = 46'
•176 • "'055
= 46"-t2t.
^^J
5 1 4 PertwrbtjUi9fM of HcdUy's Coma in tM Past, LXViii ;
Period in davs- '^5^^?^Zl4?3? = 28013, "^^^^^^ ^'^^^^^ ^* ^^
46*121
J.D. 1998S15 — 760 June 15, wliich is 5 days later than Laugi«r^f
date.
This confirma the identity both of the comet of 760 and tliat 4
S57 with HiiUey's comet, and ahow^ that we were right iu taking
the earlier date in 837 for the perihelion passage.
Now that the ideuti Heat ion of the comet has been carried bick
to 760, it i^ ii{ interest to quote the words of M. Ijaugier iii the
paper (CM., xv. p. 188) in which he identified the appsrilions of
451 and 760 from the observntious alone, and noticed that th«
average iwriodic time from 451 to 137S was decidedly lon^rer than
in the subsequent seven returns :— ** Le calcul des perturbation^
s'il litait faisahle pendant cet enorme intervalle de tempe. donner&it
peut-^tre rexplicatioii d'une variation aussi graiide dn temps
periodirjue ; mais, dans le cas uit il ferait d»>fa\it, on pourrait le
rappeler qu'une diminution analogue, quoique plus petite, a k^
ubservtk dans les ret ours de la com^te a courte periode."
He goes on to fpeak of the retardation of Encke's comet, Vki
of the suggestions that were put forward to account for this, nt
resisting medium, and Bess^Fs suggestion of the effect of loss of
matter from the comet wheii paijaing perihelion, to which we niiy
add the more recent theory of the effect of ligbt-prsa&ure on fioetf
divided matter.
The calculation of the perturbations to which M, L t«
has now been carried out^ not with absolute rigour, but ily
to reconcile theory and observation within a few days in each
revolution ; and we have found that the large chaogee in ibe
periodic time are explicable on gravitational grounds aLone. Oar
work does not justify us in asserting that the effect of the varioui
non-gravitational causes referred to above is absolutely inaenaUe;
but it suffices to show that their combined efiect docs not aiQuoffit
to more than a week per revolution^ and it is probably still Um
than this.
umi
May 190S.
Solar Prominences in 1907.
SIS
Solar Promimncm in 1907, oh^rvmi at the Kodaikdnat Ohser rotary ,
By John Evenshed.
The year has been oue of considerable activity as regards
prominences, notwithstanding a noticeable reduction in the mean
profile area, which araunnts to about 10 per cent, for all classes of
prominences.
At the KodftikAoal Observatory 78 prominences of 100" or
upwards have been recorded jihotographically and visually during
305 days of observation. The photographic records show also that
large eruptive prominences have not been infrequent, seven ot' this
class having been recorded ; the greatest elevation measured was
6 J inimites of arc in a transient eruption, pi jo tog ra plied on March 14
in solar latitude +52. A remarkable eruption was also photo-
graphed by Fox at the Yerkes Observatory on May 21 in &olar
latitude -68.
The general activity of the two hemispheres of the Sun compared
with the previous year may be inferred from the following figures,
de^iuced from the Kodaikj\nal results : —
Mean Daily Profile Areas of Prominertces,
1906. 1907.
North 2*51 square minutes, r92 square minutes.
South 2*17 „ •„ 2 '2 7 „ „
Total
4'68
4-t9
It is seen from the above that the general reduction of activity
in 1907 is confined to the northern hemisphere, the southern show-
ing a slight increase. In the latitude distribution a remarkable
difference is shown hetweeu the twu hemispheres, which are usually
more or lew symmetrical as regards the latitudes of the zones of
maxima and minima. From the beginning of the year the northern
polar prominences, which were strongly represented during i9o6»
practically ceased to exist, whilst the south polar region still con-
tinued active, the whole region between - 45" and the south pole
producing a very considerable number of large prominences* The
region from J at. - 10' to - 45"" has been tho most prolific, however,
in lhi>* beraisphere ; but no clearly marked zones of maxima are
shown. In the north, on the other hand, two well-defined maxima
occur in the zones -|- 25 ' to jo' and -f 50' to 55".
Metallic prominences were of frequent occurrence, 1 1 1 having
been recorded. Of these, 54 were confined to the northern spot
pne, and had a mean latitude of + i5'7° ; 50 were confined to the
southern s])ot zone» with a mean latitude of - 15*6* ; the remaining
7 were distributed in longitude in a narrow zone entirely outside
the spot regions, the mean latitude being - 72'. The oti\^ m<i\aJX\e.
5i6
Solar Prominences in 1907.
LXvnL 7,
elements observed in these high-latitude proniinences were Na, Mg,
and Fe, whilst some of the prominences in spot-latitudes gave in
addition the lines of Ba and Ca, together with a considerable
number of unidentified lines, probably including Ni, Mn, Cr, and Ti.
10
Heliographie Latitude,
0 0 0 3
30 40 SO 60
90
South— 2-27 Square Minutes Area per diem
Distribution Curve of the Promin*iiices for 1907.
The oniinates give the mean daily profile areas for each zone of 5*, obtained f*
observations on 296 days.
May 1908. llie Proper Motmi of Sinull Siars.
5^7
The Proper Motion of Small Stars, By S, W. Burnliain.
Small stars having any sensible proper motion which can be
detected by meridian or micrometric observations, so far jilaced on
record, are much rarer tbaii parallax stars taken from all magnitudes,
bright and otherwise. Very few examples have been detected down
to this time, although more or less searched for by nil double-star
observers and otbera using the micrometer for determining the
relative poi^itiona of stars. The small stars referred to may be
generally classed as below the limiting magnitude of the Durch-
masteriing^ or from the tenth magnitude to the fainteat stars which
have been accurately measured by lar^^'e instruments. Of conr^^e it
is to be expected that this apparent fixity in space would be found in
the great majority of iufltaiicea ; or that the motion would be so small
that it could not ^Kjssihly he separated from the noavoidahle errors
of oljservation in the niost careful measures by all astronomical in-
struments. Therefore these small stars furnish hy far the beat means
of determining any clmnge in the piisition of brighter stai-s when the
distance is within reach of the mieroineter, and give the proper
motion of the large «tar« more accurately than any number of
positiona with the meriilian circle from the beginning of such
observations, provided the interval of time covered hy the micro-
meter measures is sufticient to practically eliminate the smaller
errors of that instrument. So, when the prominent stars have been
cx)nnected hy meiisurtis with faint stars in the field hy the Struves
and other old observers, we have a value of the proper motions of
the large stars which is a safe and certain correction to that given
by meridian positions.
It is hardly necessary to say in this connection that the faint
stars referred to have nothing to do with a large and distinct class
of these objects which are nioviog in space with much brighter
stars, and at exactly or nearly the same rate, and in substantially
parallel directions. We have a large number of these attending
stars, some of them of the smallest magnitudes visible in the largest
refractors, and in brightness anywhere between that and the naked-
eye star. In many instances the moving stars are separated by
several minutes of arc. Whether tho^e constitute binary systems
in the ordinary sense of the term, or what common proper motion of
stars BO remote from each other implies, ia^ at this time» a matter of
speculation only, and must necessarily remain so until careful
observations have been made, extending over possibly several
hundreds of years. That these stars have something in common
seems to be at least hi*;hly probable. A large number of systems
of this class will be found in my General Catalofjue 0/ Do Me Stars,
indexed in Part I. under "Common Proper Motion,'* and *' Stars of
the 61 Cygoi type/'
One of the very few examples I have been abl^ lo laiv^^ ^\A
;i8
Mr. S. W. BumhAw^
LXYIIL7,
perhaps the only one worth mentioning, of an isolated small star
having a decided proper motion, is a faint star of about the twelfth
magnitude in a low-power field with 17 Lyrfx (2 2461). Tlu
observations of this star are snfl&ciant in point of time to show that
it has a remarkable movement, and one without any parallel in
180-
QTCr
Qcr
60"
M.:i
locr
I
i5(r
2ocr
Scale
17 Lkiffv,
stars of the lower magnitudes, so far as appears from reliable
observations of any kind.
The diagram shows the positions of this and other small stars
which have beun measured from 17 Lyrae,
The magnitudes of the three smaller stars have been measured
photometricaWy "by Mi. Y.C Joxdwi of the Yerkes Observatorr.
ay 1908. The Proper Motion of Small Stars.
519
le magnitncle of the large 1
star D, which is DM 31% 3325, is
mmed to be o'o.
C=
= i2'oo mag.
E
10-96
F
10-87
My measures of these stars with the 40-iiich are : —
A and G.
1905717
66-4
127-37
5720
66-4
127-73
5736
66-5
127*66
6906
66-1
1^9*53
6-964
66-1
129-46
7-258
66-1
130-01
7-271
66*2
13014
7-291
66*3
130-38
A and D.
1906*906
295'S
126*51
6964
295-6
126-51
7-258
295*7
12603
7-271
295-3
126-32
7-291
295-7
126*61
A and E.
1906*906
ii6*'*5
150-93
6*904
ii6*6
150-77
7-258
116-9
150-86
7*271
1167
150*85
A and F.
1906*906
3567
167-54
6*964
3568
167-47
7*271
357-2
16771
For the relation of A and C we
have the following earlier
sitious by Engelhard t : —
1887*81 72''-02
102-28
in Eng.
1894-85 69-23
112-31
2u Eng.
190572 66*40
127-59
311 &
1907-14 66-16
12990
5n &
These positions give for the most probable apparent annual
)tion of C : —
i"-542 in 45'*-9.
520 Mr. S. W. Bumham, Lxrin.;,
The large star, 1 7 Lyrce, has a small proper motion which u
given from meridian observations : —
0-112 ill 68'5 Aawen.
o'lai in 74*8 Newcomb.
A more accarate value of this movement can be found from the
measures of the other distant stars which it is certain hare no
sensible proper motion. These positions are : —
A and D.
188773
296'40
124-34
2n
Sng.
1894-85
296-00
125-32
2n
Eng.
190572
29570
126'12
in
fi
1907-14
295-56
126*40
Sn
fi
A and £.
1887-81
1 16*00
i52"-65
in
Eng.
1894-85
116-37
152-20
in
Eng.
190572
116-50
15075
m
»
1907-10
116-67
150-85
Sn
»
A aud F.
I8S773
357-77
I68-20
2n
Eng.
1894-85
357-50
168-11
211
Eng.
1907-05
356-90
167-57
3n
$
isures give for the
proper motion of 17 i
AD
R.A.-i-o'-'
1263 Decl. +ox>342
AE
o-
1260
0
-0224
AF
0-1307
0
-0402
Mean 0-1277 0-0323
Therefore the corrected proper motion is : —
o"i32 in 75''-8.
Applying' this to the apparent movement of C, we have for the
real proper motion of that star : —
i"-658 in 48'-2.
A photographic plate of this field was taken 1907-444 with the
40-inch. With a Wallace colour screen, and an exposure of about
fifteen minutes, the resulting negative was beautifully sharp and
well defined, and practically perfect for measuring the relative
positions ot tVie »^v^t«\ ^X^t^.
^
May 1908. The Proper Motion 0/ Small Stars.
S2t
AC =
= 130 "58
AD
126-40
AE
ISO "92
AF
16778
CE
121 72
As direct measurement of the jwaition-atigle cannot be made
with any instrument here, tlie measures af this plate were confined
r to distances. Tbe mean results of six sets ol measures by four
Kpb«erveT8 are as follows : —
^f A study uf the details of these measures seems to show that
they have about the same accuracy as those made under tbe best
conditions with the micrometer, and that the uncertainty of the
result is proliahly less, or not more^ than o"*2.
Whether a proper motion star of this magnitude is more likely
to have a parallax large enough for certain measurement, which
should be at least o"'3, l>y either or both methods, than a twelfth
magnitude star taken at random, is a matter to be determined
hereafter, but it wuuld not be unreasonable to presume that such a
star might be nearer our system.
There is one other example of proper motion in a small star,
but nearly three magnitudes brighter than the one already referred
I to, which was discovered by Dr. i^fax Wolf in hia photographic
researches (J,jY., 4101) by the change shown on plates made in
11892 and 1906. This is a gzm star, not given in the D,M,, the
[place (1900) of whicli is^
E,A. = lib 23™ 20^ I
DecL = 8* 6' I" /
There is a similar star, given by Wolf as 9'im, closely preced-
ing; and a tjm star more ilistant in tbe same quadrant. I have
made two sets of measures of these stars as follows : —
A md B, (97—97.)
1906*906 252*1
7^006 252*0
7*i02 252-1
7' 120 252*2
81 63
81 -SS
81*42
81-44
190703
252*
81*54
1908 'n8 253-2
*I56 253*1
^59 253-1
*192 253*0
80*92
So'6S
80-82
1908*15 253*1
80-^
522
The Proper Motion of Small Siars.
B and G. (i2*a)
LXVm. 7,
1906*906
275*9
155-17
7 '102
2755
154-48
7*120
2757
154-17
1907-04
2757
154-61
1908*118
275'9
154-90
•159
275-8
15470
•192
2757
154-50
I908I5 2758 154-70
As Dr. Wolf gives no measures of the relations of these stars
which can be utilised in this connection, I have measured aa care-
fully as possible their positions on the paper print for comparisoo
with the micrometer positions, with the following results : —
k and B.
1892*23
242*1
9 '"-47
Wolf.
1907*03
252*1
81-54
4n
B
1908-15
253-1
8088
B and C.
4n
fi
1892-23
275-9
154-94
Wolf.
1907-04
2757
154-61
3"
3
1908-15
275-8
15470
3n
3
It is evident that the comparison star B has no proper motion,
and that tlie change shown by the measures of AB is due wholly to
tlie proper motion of A. A comparisDn of the position in 1892
with a mean of tlie two later measures gives for the proper motion
of A :—
i"-225 in i90°-2.
The miniiniim distance of A and B of 72" will be reached in
about thirty years, after which they will slowly separate.
The 7*5/?/ star, DM 8°, 2512, which is 70* following and
iS5"-7 south, has a lyini companion not heretofore observed : —
1907-12
•14
285*0
286-3
18-37
18*37
I do not llnd any proper motion assigned to this star.
April 10.
■
1
■
■
^^^^^^vn
1
1
■
■
^9
May 1 90S,
Bev. T, E, Espin
, New DmiUe Stars,
S2j
^^1
B A^^ Double Starg,
By
the Kev. T,
E. Espiu,
MA
i.
H
H hjy
R,A.,
1900. Dec!.
p.
11.
Miga. NIgliU.
DAt«.
^^1
«
\i m
m
1908.
^^^1
I -«^5^.i43
0 47H
+ 56
41
SS-9
12*60
7-0 13-0
2
-015
^^^B
I +45i405
I 33'5
45
32
144J
5-15
8-8 • 9*2
3
-014
^^^1
4 -^42i549
a 27*4
42
32
249
5'8o
9'i 9*3
I
•099
^^^1
5 +41,501
32*0
41
46
323-9
9*62
8-5 IK5
2
•083
^^H
5 +41.543
42*2
42
0
3527
6-40
8'4 107
2
-073
^^^1
T +47»7i2
44*3
47
41
3i5*S
5*04
9-r 12-4
4
075
^^H
1 +4S.7IO
3 o-o
45
22
357*S
8-47
7-5 94
2
*082
^^^1
E^
6*8
43
54
250*6
3'i7
93 ''"2
2
-116
^^^1
0 +45.784
263
45
55
1 40 '8
8*60
8*4 lO'I
3
-091
^^^1
to'+45JS7
^4- 44,769
26-6
45
25
38-8
7'40
8-9 9 'I
2
•0S7
^^H
34'o
44
17
358 '4
2'9I
9'3 «i7
5
•066
^^H
3 +44.809
476
44
35
233
6-14
9*0 126
4
'0S2
^^H
4+42,876
567
42
30
115-3
2*29
8-9 93
4
-117
^^^1
W- 42,890
4 0*0
42
35
62-2
475
9'3 10-6
2
'090
^H
n-46.ssi
18-5
46
19
28r3
5*10
9*4 120
3
•106
H
■
150*2
1 1 *10
8*9 10-8
2
-097
AE _^M
I
14S0
27*15
2
•097
AC ^^1
■^44.945
187
45
[
128*9
7^97
8'S 9-4
3
•106
BC ^^H
■
351-8
36-32
A = 88
2
•097
^M
Bf 43*969
207
42
5»
304-3
5-07
77 120
2
*o83
^^H
^+44.967
24*5
44
43
195
772
9-0 12 8
3
*122
^^^1
0 +41.898
26*8
41
»5
1787
3*90
91 13^
I
'53
^^H
1+48,1146
39 9
49
3
59-9
3'35
91 9*2
2
-U3
'^^^1
^41966
41*9
41
28
93*
3-05
8-8 12*0
1
>53
^^H
H+43,I32S
5 94
42
33
1 22 '9
S-oi
8"o 105
3
•040
^^^B
^+47,1122
10-3
47
12
877
i±
97 10 '3
3
-loS
■
63*1
33*65
A = 9-4
3
•108
■
'5 +48,1264
16*9
48
16
353*6
r4'35
8*1 107
3
•113
^1
'6 +42,1274
172
42
3»
342-8
8-45
8*0 137
2
•015
H
■
2363
42-35
8*2
2
*oi5
H
■ -
17*3
47
17
^3-5
2-30
97 lis
2
•lot
^1
■+49,1403
40 '2
49
22
417
2-02
91 92
2
-131
^1
■ + 47,1249
6 i-o
47
26
US'3
6*57
8*5 it'o
2
•119
H
■
341-3
57 "OO
A - 83
2
'119
H
■+44,1380
4-0
44
45
226*3
6*85
9-0 9'4
3
-078
H
■
119-2
22*30
C = 12-0
I
0S2
AC ^^H
t -h 49. 1470
7*3
49
0
616
3*5
8-8 1 15
2
121
d^^H
^ +44*1492
294
44
10
301-9
6-18
9^6 12*3
3
-107
^^H
■
79-0
33-92
A = 9-3
3
•107
^^^B
■+44.1527
38-0
44
35
69-4
4*67
9-4 ^-^
^
J
524
Bev. T. E. E^n, New Double Stan. Lxvm. ;
No.
B.D.
&.A.
r9oa Deel.
P.
D.
Magi. mgfaU.
Dite.
^
h m
0
^
•
a
190&
584
+ 47.1353
43*9
47
21
3254
3-0O
94
io*o
2
•045
585
+ 45»M30
7 177
45
3
237-3
272
77
117
2
•138
586
+4i»i670
»3'3
41
49
i6'8
13-40
81
11-5
2
•189
587
+46,1307
39*3
46
9
807
4-8o
8-9
9-2
2
^3
588
40-1
47
33
3042
215
9*5
9-8
3
•078
589
+ 48.1576
41-2
48
I
1783
10-00
77
«37
4
•132
590
+43.1746
47-8
43
25
698
7-40
9X>
94
2
^5
591
+ 45.1536
8 o*s
45
30
482
1-62
9'4
9-6
2
-083
592
+ 41.1799
6-3
41
52
327-4
272
8-6
9-9
3
•308
593
+ 41,1810
100
41
12
208-2
470
9*4
9-6
2
•235 BC
230-2
19-82
A r
= 8-5
2
•235 AB
594
+ 43.1820
18-6
43
35
183-0
248
9-2
X2-0
3
•112
595
+48,1654
24-1
48
6
2349
775
8-5
13-2
2
-oSt
596
+ 46,1436
41-1
45
54
201-3
2-65
86
90
3
•095
597
+45.1640
42-8
45
48
2626
5-33
8-5
11-8
3
•091
598
+ 47,1630
55*2
47
45
261-0
7*20
8 6
10-5
2
•119
599
+ 41.1915
597
41
31
137-3
302
9-0
11-8
2
•152
600
+ 50.1673
9 355
49
49
71-6
3-65
9-0
13-5
2
•152
601
+ 46,1549
411
46
21
2875
3-47
9-0
9*2
2
•119
602
47-6
48
36
329
2-95
10-4
ii'i
3
•261
603
+ 48,1887
10 367
48
43
98-5
10-57
9-1
II -o
2
-260
604
+ 45,1865
407
45
43
527
1-82
10 -6
11*4
2
•249
+ 49,1900
49-2
48
40
158-4
47-00
80
87
2
292
605
+ 48,1953
II 27*0
48
II
64-5
4-17
8-9
ir7
2
•260
+ 43,2261
12 43*5
42
53
50-1
46-07
7-5
77
2
'3^3
606
+ 43.2293
568
42
58
284-9
8-53
8-5
12-0
3
•304
607
+ 43.2299
13 07
43
15
2249
610
9-0
11-5
I
•334
608
+ 48,2138
33 -o
48
45
271 -8
2-57
90
9*2
2
•2S9
609
+ 48,2224
M 33*2
48
14
12-3
4-65
9-0
107
2
•2S9
Notes.
559. -38* f. 50" S, OS 51.
574. — Measures of the close iwiir are unsatisfactory, and I had some doubts
about the star being really double. Professor Burnham has, how-
ever, kindly looked at it with the 40 in., and confirms its duplicity.
583. — A 14 mag. south.
6o2. — Found and measured in looking for A 2510.
■604. — The star is so faint that it is surprising that it is in th** B.D.
605. — Angle mean of 6i*-2, 67'* '8. This is a very diflBcult pair to measure,
from the faiutness of the eom^s,
i6o8.— In field south of A 2667.
Maj 1908, Micrometer Mcamires of Donhh Stars,
5^5
liesulh of Micrometer Mtamres of Double Stars nuufe mth the
2S4nch Refrctctor at the Royal Observatory, Qreetimch^ in (he
year 1907.
(Cammufiicaied by the Aitrononier KtjyaL)
Tbe measures were made witli a bifilar position-micrometer
on the 2S4ncli refractor, focal length 28 f©et. The power gener-
ally employed was 670. When bright stars were observed a
blue glass shade wjis usually employed to diminish the light and
irradiation. The itiifciala in the last column are those of the
obBerverft. viz. —
W
Mr. Lewis.
Mr. Br van t.
W.B.
H.F,
Mr. Bowyer.
Mr Furner.
i
The sttiTs have been observed from a working catalogue con-
taining all the G. W, Hough stains within the working zone» and
a number of niiscellaneotis stars showing motion, or for which
observations are required.
Some of these being wide pairs of no immediate iiiterest» the
present list of measures is confined to stars of which the separation
is under 4 ", or which show orbital motion.
Stan oUerved bid twt hieluded in
this List,
Strnre Stars.
183 AC
2 1158 AB
2 13S4
21541
2 2185 AB
22524
1000
rrsS AC
1426 AC
1555 AC
2185 AC
2690 AB
uoo
1158 AD
1468
1585
2220
2704 AD
1158 AE
14S1 AB
1612
2434
2709
1196 AC
1481 AC
2 [40
2458
2725
■
1196 BC
J 507
1
G. W. HougH Stars.
0. 494
Flo. 337 AB
Ho. 3S7
Ho. 423 Ho. 274
Ho 597
495
21
547
269
115
604
8
28
406 AB
433
tl6
475 AC
II
29
552
434
586
476
316
523 AB
553
91
117
478
219
348
409
446
588 AB
191 AC
501
349
557
445
588 AC
302 BC
32s
38
416
448
593
204
3^7
259
419
450
»3>
508
543
561
45 i
145
E&yal Obierralory, Orcenmch:
1908 Mtsy 5.
5 26 Micrometer Measures of Double Stars nuuU at LX vm. 7,
Miennnetric 0
bserratio
mo/Do
uhU Sta\
rsatihi
' Boyt
it Observaioi
ry, OrftniciA,
start Name.
R.A.
1910.
N.P.D.
191&
Pod-
tion
Angle.
i2S; Of •
Ma«>.
".^ 0^
Hu. 405 ...
u 12
65 57
275-5
i'-i8
4
9-3 9*5
•902 W.R
jB 1093 • •
0 16
79 31
69-5
0-33
7-3 8-2
•827 B.
iB 779
0 23
6655
257-3
1-04
85 90
•827 B.
Ho. 212 ...
0 31
94 5
245-0
0-31
6-0 6*0
•827 B.
Hu. 411 ...
033
67 30
1027
0*65
8-5 8-5
•925 W.B.
Hu. 413 ...
042
67 15
2417
o'8o
8-0 9*2
•925 W.B.
Ho. 306 ...
043
64 56
1637
1-19
8-5 8-8
•044 W.B.
Ho. 4
0 46
5633
2004
I -57
9«o 9-0
•592 W.R
273
0 50
66 52
28-2
I-I3
6-2 6-8
-827 R
29-9
0-85
•
•864 W.B.
Ho. 307 ...
0 53
58 17
86-5
276
95 97
•044 W.B.
3113 ...
I 15
91 0
355-2
I '33
6-2 7*2
•827 B.
Ho. 9
I 24
6845
94-8
2-44
9X) lo-o
•592 w.a
2 13S
I 31
82 50
33*1
1-62
J
7-3 7-3
•827 a
2158
I 42
57 18
2577
1-90
8-3 8-8
•864 W.B.
2 183 AH...
1 1 50
61 39
1-6
0-45
7*5 8-2
•S27 B.
Hn. 1033 ...
1 1 50
54 6
234*4
0-85
8-5 8-8
•044 W.B.
2 1S6
I 51
8837
351
0*73
72 7-2
•827 B.
220S
I 59
64 31
91-2
0-48
6-2 8-4
•058 W.B.
78-6
0-58
•162 H.F.
Ait. 959 ...
2 13
59 9
3607
3*84
90 I2-0
•342 W.B
Ait. 962 ...
2 16
60 28
76-6
0*53
8-9 9-2
•162 H F.
2 305
2 42
71 I
3163
3-22
7 3 8*2
•104 H.F.
315-4
3*19
•673 W.B.
Ho. 317 ...
2 52
7Z 7
304*3
3-46
Si iro
•867 W.B.
Ho. 500 ...
3 6
54 15
222 I
0-68
8*5 9-0
•162 H.F.
Ho. 502 ...
3 9
54 36
19-5
077
8*5 9*o
•162 H.F.
Hu. 105S ...
3 19
50 6
1147
075
7-8 8-5
•192 H.F.
Ait. 979 ...
3 20
59 35
270-9
1-48
2
9-2 io*o
•482 w.n.
Ho. 322 ...
3 20
44 43
124-1
1-90
9-2 9-5
•222 H.F.
Ait. 983 ...
326
60 40
304*1
049
8-5 9-2
•162 H.F.
Ait 9S7 •••
3 37
60 30
7-6
I -09
9*6 97
•347 W.B.
Hu. 103 ...
3 39
40 25
203-1
I 01
8-1 8-4
•222 H.F.
Ho. 504 ...
3 39
54 26
188-3
098
7-8 8-0
•S93 W.B.
Hu. 815 ...
3 51
68 29
2047
2-45
8-0 1 1 -3
-324 W.B.
Ho. 505 ...
3 53
57 30
194-9
1*23
8-0 lo'o
•044 W.R
2 4^^3
358
50 43
223-6
0-53
8-0 9-5
•192 H.F.
3 1277 ...
4 0
61 $1
300-7
075
8*0 12*2
•227 L
I
■
^H
■
■
1
I90S.
the Royai Observatory ^ Grvte^ivmh, in I go/.
MimmeUr Measures of DoubU 5'^«rf— oontinued.
H
lauie.
R.A,
1910.
h m
N.P.D,
19*0.
Foil*
tlan
Angle
M»gt.
Epoch
^H
4 I
61 18
64-2
2-40
I
8'5 111
'189
^1
1 •'•
4 3
^1 3
188-3
0-43
2
8-4 9*3
•208
^1
^^^^^
4 3
SO 3
172^4
2*34
2
77 9'2
•192
^M
5 ...
4 4
61 35
1657
o'49
2
8^0 8^0
*208
fl
,..
4 10
58 32
197-8
0*38
7"5 7'5
•217
^1
4 19
60 5
150-8
0'76
S'o 8-0
492
^M
151-9
0-70
...
i6z
^M
...
4 35
73 39
219-8
0*66
9"0 li^o
189
^1
, ...
4 38
^9 55
164 '9
275
9 '2 9'3
'104
^M
fAB
4 S9
61 24
281 -5
170
9-0 107
•159
^M
H ...
4 59
60 30
349^5
0-80
S-i 8*9 1
*227
^M
1
355^9
0-56
•932
W.B. ^M
16 ...
4 59
60 9
38-4
i'o6
7*8 iro
'492
W.B. ^1
*..
S 0
70 19
327 '2
084
6 '6 7 '2
*i89
^1
|8..,
5 <
60 3
! 238 -6
0-45
8-5 9^1
■939
^M
f ...
5 M
54 42
2S9'o
o'6i
7-0 8-5
■192
^M
...
5 3*
63 8
170-0
0-78
7*0 7-1
•175
^M
172-7
0-97
-925
^M
p ...
5 39
58 44
130-8
074
8-2 9*3
•222
^M
BC
5 50
6644
110*5
^'^3
9*0 9 "2
-159
W.B. ^M
...
6 9
75 31
243 '9
274
8*2 12-0
159
^M
) ...
64s
75 12
130-7
0-51
8*3 8-3
•177
W.B. ^M
b ...
6 54
64 49
321*3
0*40
8-2 8-5
M51
WB. ^M
i9
657
SO 54
101 -8
2-04
9 '4 97
-230
^M
.t.
658
76 46
837
>'39
8"o 8-8
•159
W.B. ^M
...
7 7
62 37
2992
0-52
7-1 7"!
-241
^M
...
7 IS
67 40
326-4
2-95
9'o 12 '0
•236
^M
...
7 42
64 19
120*6
o'57
8^5 8*5 i
•159
W.B. ^M
f ...
7 52
68 48
*S3'i
0*54
7^0 9^0
-210
W.B. ^M
*,.
8 4
57 3t
41-9
223
7^1 8'o
•243
W.B. ^M
LB
8 7
72 4
340-3
1*21
5*0 57
'iSi
W.B. ^M
3417
119
*..
*222
^1
3 ...
8 9
S3 14
J5S7
036
8*5 8^8
•236
^M
' ...
8 14
57 23
1 53 '6
3 '39
8-0 12-0
•3S6
W.B. H
...
8 18
69 42
1507
0^55
8*5 8-5
•24*
W.B. H
f ...
825
55 10
2643
I 01
9"o 10*0
•356
W.B. ^M
IC
84a
83 12
241-8
3'07
3-8 7-8
•a6o
^M
843
S3 31
l60'2
170
■
9'o 9-2
ii
^ .%. ^M
528 Micrim^ier Mtamres of DoMe St(!a% made ai lztol;
Miero9MUr Measures of Double ^Stort—contmiied.
Start Nmte.
E.A.
1910.
h m
N.P.D.
X910.
Pnsi.
Uon
Angle.
Dl- No.
*"«'-Nrghta
Mags.
1907.
Hu.861 ...
853
75 25
209
0^
8-5 9-1
•241 W.R
Hu.718 ...
855
57 13
192*0
0-41
87 8-9
•299 W.R
23121
9 13
61 3
35-0
0-43
75 7-8
•242 w.a
Ho. 42 ...
9 9
56 4
7*9
1-62
9*5 9'5
•255 W.B.
2 1333 ••
9 13
54 15
47'4
1-60
6-6 6-9
•323 L
2 1334 ..•
9 13
5248
239-1
2-91
4*0 67
•323 ^
Ho. 43 .•
9 14
68 48
298-0
0-31
8-0 8-5
•230 W.B.
Ho. 364 ...
9 14
66 42
332-9
3-87
8-2 11-2
•219 W.B.
2 1348 ...
9 20
83 12
318-5
I -81
7-5 7-6
•225 W.R
2 1355 •••
9 22
83 19
329-2
2-24
7-2 7-2
•28« RF.
2 1372 •••
9 32
73 19
56-4
0-69
8-2 8-3
•282 H.F.
2 1374 ...
9 35
50 35
286-6
288-3
327
2-95
7t) 83
-296 W.R
•334 H.F.
Ho. 369 ...
9 46
53 5
275*5
o"37
77 7-8
•323 L
2 1389 ...
9 47
62 32
306-4
308-2
307-7
1-99
265
2-19
8-0 9-0
...
-277 W.B.
-260 H.F.
"323 L.
2 1406
10 0
58 26
228-3
0-98
8-0 87
•334 H.F.
2 1413 •••
10 7
73 9
96-0
97*6
218
1-90
8-9 89
-282 H.F.
•296 WB.
2 1420
10 13
50 24
327-5
2*24
8-2 9-9
•296 W.B.
Hu. 875 ...
10 13
52 2
64-1
1-05
7-0 9*8
-•356 W.B.
2 1423 ...
10 14
68 56 577
1-23
8-6 9*3
•304 H.F.
2 1426 AB
10 16
83 4 283-0
0-72
7*5 80
•282 H.F.
02218 ...
10 23
85 56 79-1
078
8-2 9-7
•282 H.F.
2 1439 ...
10 25
6844
113-0
1-94
8-0 8-5
•238 W.B.
114*0
183
...
•260 H.F.
2 1457 .-.
10 34
83 46 j 314-8
1-28
2
7-6 8-5
•282 H.F.
2 1476 ...
10 44
93 30 181 7
2-i8
2
7*2 8-0
•319 H.F.
2 I5CXD ...
10 55
92 56 308-1
1-24
2
7'6 8-2
•319 H.F.
21517 ...
II 9
69 19
87-1
034
2
73 7*3
•301 B.
84-0
0-45
2
-370 W.B.
2 1523 ...
II 13
57 54
131 -6
2-86
I
4*0 50
•296 W.B.
131*6
2-68
I
•334 H,F.
21525 ...
II 14
41 58
176-8
164
I
9-0 90
•392 H.F.
2 1536 ..
II 19
7858
49*2
2-21
2
3*9 71
•301 B.
2 1537 ...
II 20
68 52 1 3553
2*80
I
7-6 8-6
-219 W.B.
21555AB
, i^ ^^
6\ ^0
[ ^SVi
0-39
2
6-4 6-8
•301 R
1
H~
1
■
I^H*
^
■
■
fl
■
^^ay 1908.
tkf. Uoyal Ohservaior^, Crreemtnch, in i
907.
329
MtcroTMter Miomins of Vouide Start—cou^UGd.
^HftUr*! HftLVM.
R.A.
h m
K.P,D.
Angle.
Ml«i.
Epocli
1 c^->j.
ON.
^Bu. 8^8
ri 38
68 25
320'- 1
0-69
3
8-4 8-9
•301
W.B.
mm 1581
u 51
43 53
172-0
ro4
8*3 9'5
•392
H.F.
2 1SS9 ,..
i» 55
45 50
161*3
1-94
9-0 9*5
"392
H.F.
% 1606 ,..
12 6
49 33
3287
ro6
6-3 7-0
392
H.F.
2 1639 ...
12 20
^3 55
351*3
0-36
67 7*9
*30i
B.
a 1643 ..
t2 23
62 28
347
37-6
2*15
2-20
87 9*2
•348
■438
W.B.
2 1647 ...
la 26
79 47
224'4
146
7-5 7-8
308
W.B,
Hu, 892 .,,
12 38
74 59
163*8
101
93 9*3
•301
B.
Hu. 893 ...
12 43
77 13
33 '9
I'SS
91 91
■301
B.
Hu. 894 ^^.
13 49
76 20
1444
roa
9*1 ri
'301
B.
o;e 2s6 ...
12 52
90 24
76-6
o-6o
72 76
-301
B.
OS36t ..,
13 S
57 26
346-9
1-66
6-9 7 4
•301
B.
02 369 ...
13 29
54 38
215-6
o'35
6-5 7-0
'319
B.
02278 ...
14 9
45 24
825
0 24
7'S 77
*5i4
B.
Ho. 541 ...
t4 16
77 25
966
2-16
93 10-2
•388
W.B.
21S34
14 17
41 5
343*2
0-14
n 7*2
319
B.
Ho, 542 .
U 23
68 59
2649
0-58
8-8 8-8
301
B.
% iS6s ...
14 37
75 53
H5'9
043
3"5 3"9
339
B.
02 28s ...
14 42
47 14
110*6
032
71. 7*6
•463
B.
02 2S7 ...
»4 48
44 42
3217
079
7*5 7'6
463
B.
Ho, 3S9 ...
1448
69 20
98*3
1-46
7-0 9*3
■427
w.a
02 2S8 ...
14 49
73 56
188-0
179
6-4 7*«
340
W.B,
185^9
1-61
*,,
•400
L.
2 1932 ...
15 14
62 50
164-5
0-72
56 6-1
-400
L.
t «944 -.
tS 23
S3 36
324*0
1-25
7*5 8-1
•427
w.a
2 1954 ...
15 31
79 9
185-5
3-68
3-2 41
384
W.B.
02298 ...
15 33
49 54
'9i'5
rii
7-0 7*3
'607
B.
2 1967 ...
15 39
63 25
1133
063
4-0 7'o
■400
L.
02 303 „.
IS 57
76 28
145-2
0-84
7*4 7*9
■427
W.Bv
22021
16 9
76 14
336-6
3-84
67 69
384
W.B
2 2026
16 12
82 24
187-9
050
8'6 9'i
■496
L
tS9-4
o'49
...
'498
W,B.
02 309
f6 16
48 7
643
0-43
7'5 7*8
*502
B.
2 2049 ...
16 24
63 49
204-0
ri7
6*5 7*5
Hoo
L.
Lgiu. 4S5 ^■.
16 24
68 54
295'o
I 59
2
8*2 13-0
329
W.B.
^■20S2 ...
16 25
71 24
271-0
ri4
1
7*5 7*5
496
U
269-8
127
2
\ ... \-v>.
Ni.\i*
530 Micrometer Measures of DotMe Stars made at LmtLj,
Micrometer Measures o/DtnihU iStor»— continned.
Star't Name.
R.A.
191a
N.P.D.
1910.
Foti.
tion
Angle.
m-. No.
"^ of
Mag..
Bp«cl> obt.
1907.
2 20S5 ...
16 S
87 49
62*-4
1-27
7
40
6-1
•524 W.B.
IIu.487 ...
16 38
67 58
28-9
0-51
2
9-0
9-0
•559 B.
22084 ...
16 38
58 14
169-3
104
4
3-0
6-5
•554 B.
163-4
1-08
2
.
•419 L
168-5
1-31
3
.
•558 W.B.
22091
16 39
4838
120*9
0-89
2
7-5
8-0
•604 W.B.
02315 ••
16 46
8837
I52I
0-65
3
6-2
81
•544 W.B.
22106 ...
16 47
80 26
298-4
o'i9
I
67
8-4
-578 R
Ait I 142
16 53
75 8
3055
1-69
I
87
127
•630 L.
22114 ...
16 58
81 25
1607
ri8
3
6-2
7*4
•495 W.B
Hu. 1176 ...
17 5
53 57
III7
0-15
3
6-0
60
•686 a
22x32 ...
17 7
93 56
II2*0
1-43
I
8-3
90
•545 H.F.
Hu. 170 ...
17 8
80 8
278-4
1-88
I
8-5
10 -8
•575 W.R
Ho. 414 ...
17 19
63 50
88-5
o-6o
2
8-4
8-8
•723 W.B.
Ho. 415 ...
17 19
64 10
332-9
096
2
8-0
87
•723 W.B.
Hu. 1 179 ...
17 21
51 20
274-5
0*22
4
7-0
7-1
•655 B.
22171
17 24
99 55
67-9
1-69
3
7*5
7-6
•559 B.
22173 ...
17 25
90 59
312-3
0-49
3
6-0
6-3
•559 B.
Ho. 417 ..•
17 26
51 59
152-4
0-38
3
8-0
8-0
•635 B.
Hu. 179 ...
17 27
7843
55-4
201
I
8-8
8-9
•471 W.R
Ho. 420 ...
17 35
52 58
107-9
1-48
2
9-3
9-6
-626 B.
•
22205
17 40
72 14
306-3
2-01
4
8-0
87
•501 W.B.
22215 ...
17 41
72 15
2857
o-8i
3
5 '9
7*9
•511 W.B.
2 2220 liC
17 42
62 13
8o-i
114
2
95
10-5
-526 H.F.
= AC 7
79-6
I 28
I
..
•630 L
02 33« ••
1748
74 39
14-0
076
I
6-6
6-9
712 B.
Ho. 442 ...
17 48
95 18
94-7
3-6o
3
8-2
9-0
•566 W.B.
Ait. 235 ...
17 49
65 0
78-5
033
I
7*9
8-1
712 B.
$ 1299
17 52
79 0
154*2
0-42
I
8-5
8-5
712 B.
22262
17 5«
98 II
259-8
1-78
2
5*o
5*7
•526 H.F.
02 534 ..
iS I
68 34
2736
2-II
2
7*5
9*5
•549 B.
2 2272
18 I
87 28
164-5
262
16
4*5
60
•595 W.B.
02341 ...
iS 2
68 34
92-0
037
3
6-4
77
•565 B.
02524 ...
18 4
70 21
567
o'39
3
7-0
8-3
•600 W.B.
22283 ...
18 5
S3 52
82-2
090
4
7-2
7*7
•568 B.
Hu. 314 ...
18 5
71 23
152-1
056
3
8-3
8-5
•600 W.B.
Hu. 315 ...
IS 5
66 27
46-8
0-43
3
9*3
9*3
•675 W.B.
23289
, iS 6
l-hV-
U^^'^
ri5
4
6-0
7-1
•518 W\B.
■
■
■
z
^H
■
■
[ May 1908.
the Royal Observatory^ Gresnurich^ in i
907.
53«
Mieromei€r Meastinn of DoulfU ^£«r*— oontinued.
star's Niime.
KJ».D.
Hott
MasB.
Spocb
1907,
Obfl,
2 2294
jl ""9
«f9 SI
28 r 3
o*'S3
2
7*4 77
•526
H.F
Ho. 430 ...
iS iS
69 32
1947
293
8*5 9'o
■687
L.
Lewb 20 ...
t8 18
69 30
332*1
2*32
9-0 9-5
•687
L.
•
18 18
70 2
1380
377
io'5 n-o
*6S7
L.
Ho. sSi ...
tS 19
75 S
130-2
0-30
8*4 9-0
*654
B.
122*5
0-38
706
W.B.
^10.83
t8 20
62 32
268-2
0'6i
8-8 8-8
^583
W.B.
■
75*3
0*56
.♦,
*6S7
L,
32320
]8 24
65 25
47
I '54
7-1 9*0
'495
W.B.
02 3S4 ,.^
iS 38
83 17
1706
082
7*2 S'o
•580
W.B.
02 358 .»
18 32
73 6
191 '2
r86
6*8 7 -2
'533
W. 11
Htj. 19S ...
tS 34
81 15
1S9M
0-15
8-5 8-6
'657
W.B.
Ho. 437 AB
18 37
58 27
1 20 '2
o'43
8'3 8'5
739
W.B.
,.. CD
339*4
3*5S
11*2 117
73 »
WJ3.
Ho. 88 ..,
18 41
9938
21 r I
2*31
9'o 9'0
'578
B.
2 2375 .„
jS 41
8436
II2'5
232
6-2 6-6
•517
W.B.
2 2422
t8s4
64 2
927
0-67
76 77
■529
W,B.
0 64S ...
18 54
57 13
I79'0
0*42
^
6*0 9-5
-687
L.
182-2
0*51
..*
73»
W.B.
Hit. 330 ...
IS ss
70 31
28-4
077
2
90 9*3
742
W.B.
«
18 55
70 32
2930
2-42
I
9'5 io*S
•668
L.
n«. 678 ...
18 56
77 54
360-2
298
2
8*0 io'5
•507
W.B.
Ho; 92
r8 57
57 37
39*5
1*12
2
9-0 9-1
762
W.B.
2 2437
iS 58
70 58
58-5
o'8o
2
7'8 S^o
^507
W.B.
Ho. 93 ...
18 58
75 42
329*3
rt3
77 t20
711
W.B,
2 24S5 -'
19 3
67 58
68 '8
4"oo
7*2 8^3
•668
L.
^
724
373
■698
W.B.
P «
19 3
67 S
296*2
373
9*5 10*0
■668
L.
2917
4'03
"*
715
W. B,
Ho. 444 ...
19 S
63 14
767
1-36
8*4 100
620
W.B.
Ho. 98 .
19 5
63 3
146*2
0-31
80 80
719
W.B,
Ho. 442 .-
19 5
70 SS
947
360
9*0 10^5
*566
W.B.
.
19 5
62 27
875
2-95
9'0 9 '5 1
•668
L.
m '■
>9 5
62 27
78*5
3-08
9'o 10*0
•668
L,
^Ho. 447 ...
19 13
62 14
1 74 '4
1*93
9'5 9'S
•593
W.B.
Ho. 103 ...
19 14
93 37,
246-6
2*4S
g-l 92
•578
B.
Ho. 105 ...
19 iS
73 31
187 s
26S
8*5 lo-o
•S17
W.B.
HiL 339 -
19 21
7132
45 9
0*59
■
8*6 8*ei^'S^
^.^*
532 Micrometer Mectsures of Double Stars made at ulyulj,
Micrometer Measures ef Dmhls Stars — oontumed.
Star's Name.
Ho. 450 AB
22525
Hu. 340
Hu. 949
IIo. 108
Ha no
Hu. 953
Ho. 112
2 2576
AGC II
22596
2 2600
BD + 21''
3994 A15
lil) + 21*3996
i 2607 AB
---02 392
Ho. 5S3 .
Ho. 118 .
Ait. 1194 .
Ho. 122 .
Ho. 591 .
*
Ho. 126 .
Hu. 1198 .
Ho. 457 .
2 2690 nc
Ho. 133 .
Ho. 134 .
/3 151
Ho. 45s .
2 2710
Hu. 690 .
2 2723
Ho. 141
X.P.D.
1910.
R.A.
X910.
h ra . ,
19 23 51 22
19 23 64 52
19 24 71 43
19 30 57 5
19 30 56 43
1935
19 36
71 31
54 58
19 37 71 35
19 42 56 38
19 45 71 5
19 50 74 59
19 50 67 47
19 51 67 47
Po«i.
tion
Angle.
267*-6
305*2
119-9
103-0
47*9
8o-5
177-0
70-2
2879
140-4
322-0
81-8
564
^<^ Nights
19 55 68 II
19 55
19 55
19 59
20 o
20 II
20 14
20 16
20 16
20 20
20 21
20 27
20 2S
20 32
20 33
20 35
-o 37
20 41
20 42
20 4S
48 I
68 8
56 35
77 54
61 37
62 23
51 16
51 18
77 17
60 55
79 5
103 51
55 9
75 45
61 10
S^ 3
56 II
74 -i8
71 2
292*1
256*0
227
305*1
299*6
754
294*0
1986
»52-3
32-8
60 o
217*2
184-3
203-2
125-5
2790
497
290*1
103-4
291*0
097
0-67
087
0-69
0-54
2-67
108
272
2*45
0-19
2*02
3-12
3'09
19 54 68 6 2757 1*32
2778 1*33
0*65
1*21
274
062
0*80
I'lO
2-30
1*95
2-86
0-65
2-13
0*41
0*87
3*36
0*25
212
2-65
0-93
1-37
i-i6
298-9 1-94 3
HagL
^Kf^ out.
1907.
8-0
7 5
9-0
8 6
80
95
8-6
9-0
7-8
5*5
7-2
72
9*0
91
8-9
i 9-0
9*5
7*0
97
8-4
8-1
7*5
80
8-5
47
9-0
6-0
9*o
8-4
87
77
93
90
8-0
9*5
90
9-0
7-8
6-5
8-6
10-5 10-5
8-3 97
9*o 10-4
90 9-5
9-0
107
II 'O
9*0
97
lO'O
"*3
97
92
81
7 5
8*o
87
6-1 ]
9*1 I
8-2
92
8-0 I
10-8
-928
•558
•609
928
-928
-679
-762
•675
•762
705
-692
•657
•673
'92S
767
762
•750
•767
756
•655
-928
•928
•835
•692
731
750
•762
•730
^73
•835
•928
•692
-619
H.F.
w.a
W.R
H.P.
H.F.
W.B.
w.a
W.B.
W.B.
B.
W.B.
W.B.
w.a
713 W.B.
•928 H.P.
•694 w.a
H.F.
W.B.
WB.
B.
W.B.
W.B.
W.B.
H.F.
H.F.
H.F.
W.B.
B.
B.
W.B.
B.
W.B.
H.F.
H.F.
W.B.
W.B.
■
^H
■
■
90;.
533 ^^M
■
■
May 1908,
the Royal Ohennitory, Qrecnwich, in V
Micrameier Metmtrt^ of IkmbU St^rn-
-ogtitinuod.
^H
SUr*! Name
h m
NP,U>
1910,
Pnsl.
Angle.
Mmf..
Epoch
^H
Ho. 144 "
2Q 48
70 13
164-9
0*43
I
70 7*0
-657
^M
Ho. 146 „.
20 SI
55 7
$19
0-56
1
8*0 8*1
•928
n ^M
Hit. 764 ...
20 56
55 55
1902
0*48
I
7*5 87
928
^M
Ha. 282 ..
2t 0
44 30
359-0
0-28
I
7*0 7*0
'805
^^H
Hu. 767 „.
21 9
74 24
H37
0'i8
2
7-0 7-0
738
^^H
moai535 .
21 10
80 22
171*9
o'i6
I
4'5 5*0
•6S7
^1
^B
158-2
[o'i53
...
706 W.B.t ^1
^^^K
9S^o
0*13
.*.
718
K. ^m
^^^B
76S
o'i4
...
^848
' V
^B
136*0
O'll
...
•862
^M
Kq.2S4
21 12
74 24
902
373
90 97
'63^
^M
Hfo* 155 ...
11 14
5637
121 *i
078
8*0 9'o
'92S
^M
^■0.386 ...
2t 16
52 8
304 '9
0*16
6*0 6"o
764
n
^^ Z55 -
21 16
57 8
317
2*02
80 95
7S3
W.B
Blo^ tS7 -
21 19
5822
23*i
3-69
77 77
783
W.R. 1
^■Ul. f2i9 ...
2t 2t
60 8
120 '8
1*40
9*3 9*4
762
W.B.
Hh^it. 1220 ...
21 2J
5854
145-5
'73
8*5 9-0
762
W.B.
Ho. 160 ...
2! 25
47 29
178*9
172
83 9*0
'928
H.r.
Utt. 37t ..-
21 31
65 57
J62*I
0-22
70 75
742
R
Hu, 372 ...
21 34
66 48
I49'6
o"3o
9*0 9*0
742
B.
Hu. 280 ...
21 38
84 30
134-6
0-18
77 Si
742
B.
Hii, 374 ...
2t 39
66 32
32^8
0*33
9X) 9'o
742
B.
Ho. 605 ...
21 40
55 32
344-0
2*09
9-2 9*9
•942
L.
0^
21 41
6446
95 I
019
4'8 5'3
•806
W,B.
1^
93'r
o'o8
*687
L.
■
97*6
0*13
.-•
735
B.
^^Ho. 166 ...
21 46
^2 34 1
75 '3
034
75 7'5
782
WB.
Ho. 169 ... 1
21 4(^
54 19
1371
3'i8
8*o 12*0
•942
L
Ho. 467 .
2t 46
68 10
182*6
1*15
8*o lo-a
712
W.B,
Ho. 179 -
22 4
60 14
26rs
0*42
8'o 9*0
•8fo
W.B, '
Ho. 1S2 ...
22 19
72 54
128*9
1*46
8-5 8^5
719
W,B. '
1 2900 ...
22 19
69 39
175*8
1*4^
6-0 9*2
■942
h.
Ho. 475 ...
22 29
64 3
315*9
074
2
So 8*2
769
W.B.
Ho. 394 •'-
^ 35
63 2
58*1
2-03
2
8*0 10-0
763
W.B. '
Ha 480 *.
22 34
60 45
2287
0*69
1
8*0 9*1
*8to
W.K
B
t Distance estim&ted.
^^
534
Mierometer Meamres of DotMe SUmts. lxyulj,
MicromeUT Mtamra fjf DmMe iSSteri— oontiniied.
Starts Karne.
Ho. 296 ...
Ha. 7S0 ...
a ^34 ...
Hn. 781 ...
Ho. 481 ...
Ho. 190 ...
Ho. 482 ...
Ho. 987 ...
Ho. 192 ...
Ho. 193 ...
Ho. 196 ...
Ho. 198 ...
Ha. 400 ...
Ho. 489 ...
23012
23013 ..
Hu. 298 ...
«
Hu. 300 ...
Ho. 206 ...
1910.
h m
22 36
N.P.D.
191a
75 56
22 37 75 56
22 37
22 38
22 41
22 45
22 47
22 51
22 55
22 59
23 4
23 13
23 13
23 22
23 23
23 23
23 28
23 36
23 41
69 s
75 16
61 6
62 28
64 S
7442
60 24
6035
60 I
73 38
72 II
62 47
73 55
73 55
8325
70 8
84 I
23 55 56 14
PmI*
ticn
617
64*0
I3'9
5*3
134*3
3" '9
II4'I
153*9
56*5
243*8
252-4
30*4
1657
288-5
32-8
2294
245-0
189-9
273-8
76-1
128-2
1 19-0
II8-8
189*0
0*46
0-33
o*33
0-51
0-63
0-30
0-31
1-86
0*22
0-54
0-93
1*47
2*42
1-94
2-31
0-33
0-45
2-99
3*62
028
I -60
1*14
1-15
1*69
No.
of
VVito
3
2
3
I
I
I
3
I
5
3
I
2
I
I
3
3
2
I
I
2
I
3
I
I
Mag..
55
55
•.
9*2
9*4
8-2
9*2
8-5
9*5
8*3
8*3
9*2
9*2
6-8
6-8
8-6
8-8
8-5
9*5
7*2
II '2
80
II-O
8-0
9-0
7*4
8-8
7-8
7*8
87
8-8
7-8
9*3
6-8
7*4
80
II-O
87
9-0
8-0
IQ-O
Bpocn
Z907.
Oba.
742
B.
791
W.B.
742
B.
•942
U
•942
L.
•862
W.R
742
R
-810
W.R
772
R
780
R
•942
L.
•763
W.R
•871
W.R
•871
W.R
•860
W.R
7S0
R
-832
W.R
•942
L
•942
L.
757
R
•942
L.
780
R
•893
W.R
•810
W.R
Vol LXVill Pmttl
Gadsdm's Arlijicial Horizon fm^ Sextants, 535
^ote 07t ^Uhe SpanrnTt^* Captain fhidsdeii's Ariijieial Horizon for
iSej'tanis. By H. H. Turner, D.Sc., F,K.S., Savilian Professor.
(Plate 13.)
It &6dDis desinible that the existence of an instrument wfiii |j ha^
bpen fouml to work in practice, and whicb is useful to a sailor in
or at nightj should be njade wi<lely known, 1 venture to
fcmidjasise tlie fact that th^ instrument Las been found practically
F?ful ; for this point is essential Tliere have been many promif^ing
suiigestions for such an inatrument, wlucli have faded 011 actual
iriah
The apparatti.s is attHched to nii ordinary sextant, and is the
-invention of Captain H. A. Gmlsden, of 6 Binden Euad, Kaveus-
[court Park W., Londou, to whom I must ref^-r those interested for
itiiftljer details. Tha subjoined lignres (Plate 15) will explain its
Bral nature. The instrument was exhihited to the Society at
\x% April meeting.
Ao artificial horizun is provided, which consists of two bars that
[exactly span the periphery of the 8nn*8 image in the horizon glass,
v%iid are maintained in horizoutal [/owition by means of a pendulum
forming part of tbe attachment. Thi« is shown in detail in
Plate 13. At J is a pivott'd bjilnnee beam which carrier tbe
horizou bart^ B^ tiie latter extendiug through a slot in tbe casing.
The pendulum compriiies a fsair nt plates C, pivoteil to a block at
their upper ends, while their lower etids cnrry a h«nvy weight D.
I A plate E h secnrevl to the weight />, and Is formetl with an
jopening through which. axten<la a rod F, projecting from the
team A. The pendulum maintaints its vertic^-l |R»sition when the
iextant is held in the iiand, and by means of the rod F the
horizon bars are kept ai a projier horizontid level.
As the horizon l>jtrs are near the t?je <jf an oliserver^ tbe tele-
scope of a »extant cannot he uned. Obflervations are therefore
made with a simple tube^ longer than that usually supplied, so that
^ihe eye can be properly focussed on the bars.
If it is desired to Ui^e tln^ sextant in the ordinary way, the
apanner can be ''backed" out of »ight.
Captain Gadsden has also added to the sextant a stock of siinple
foT-m (resembling a gunstock), whicb is put against tbe shoulder
pipe to steady the instrument
536 *' On Dr, Roberts* method** etc. LXVin. 7.
Note on Father Stein* 8 paper ** Chi Dr, Roberts' method of deter-
mining the absolute dimensions of an Algol Variable Star"
By Alex. AV. Roberts, D.Sc.
Professor Turner has kindly sent me in advance the main con-
clusions Father Stein has arrived at in his paper in Jf.xV. (vol.
Ixviii. p. 490).
Through unaccountable error, I regarded the value of the light
ratio as a maximum when the difference between the masses of the
component stars was a minimum. It then, however, is zero.
Although in the case where the masses of the component btars
are eipial it is impossible to arrive at the absolute magnitude of a
binary systeu), this is not the case where tiiere is disparity between
ihe masses, and I still huve the hope that through careful deter-
mination of the quadrant points of a close binary orbit we may
advance our knjnvledge in tin's direction.
[yote hij H, H. Turner. — It should perhaps be made clear that
lli(^ above note wiks written before Dr. Roberts had actually seen
Father Stein's paper. On referring to his notes, he found at once
the unfortunate slip above stated, and hastened to admit the
correction without awaiting the paper itself. His proniptues^
makes it possible to include this note in the present number of the
iXotice^.']
MONTHLY NOTICES
OF THB
ROYAL ASTRONOMICAL SOCIETY,
Vol. LXVIII.
Junk 12, 1908.
No. 8
H. F. Nbwall^ Esq., M,A,, RR.S., Presiden't, in the Chair.
Hugh Cameron Campbell, Science Department, Surgeons' Hall^
Edinburgh,
and
The Rev. Arthur Mackretb Deane, M,A., Canon of Chicbeister,
Ferring Vicarage, Worth ing» Sussex,
were balloted for and duly elected Fellows of the Society,
Benjamin Buillaud, Director of the ObserTatory, Paris;
Carl Liidwijx Wit helm Cbarlier, Director of the Observatory,
Lund, Sweden ;
Edwin Brant Froat, Director of the Yerkes Observatory^
Williams Bay, Wisconsin, U.S.A. ;
Joljann Georg Hajs^en, S.J., Director of the Vatican Observatory^
Rome ; and
Johannes Franz Hartmann, A«trophysical Obaervatory, Potadaro,
Germany;
were balloted for and duly elected Associates of the Society.
The following candidate was proposed for election as a Fellow
of the Society, the name of the proposer from personal knowledge
being appended : —
Tiie Rev. Thoraaa Nicklin, M.A,» Assistant Master^ Rossall
School, Hescot, Rossall Beach, F'eetwooil, Lancashire (pro-
posed by S» A* Saunder).
Eighty-one presents were announced as having been received
since the laat meeting, including amongst othetft ;^Cai^ Cft,^«I\G^«i
of 1680 stars for equmox 1900*0, pretnented by t\ve 'R^'^fiX 0\jsfe\'^^»-
^9
538 Fro/. Sim(m Neipconib, Form and Arrangem LXVIIL8,
tory, Cape of Good Hope; G. £. Hale, The Study of Stellar
Evolation, presented by the author; five spectroheliognphB
(enlargements), showing hydrogen and calcium flocculi, presented
by the Mount Wilson Observatory ; lithograph from a drawing of
Donati'd Comet, by Miss Charlotte S. Cooper, Markree, presented
by Miss Cooper; i6 charts of the Astrographic Chari of the
heavens, presented by the Royal Obeervatory, Gieenwich.
Consideratiorw on the Form and Arrangement of New Tablet
of the Moon, By Simon Newcomb.
Hansen's Tables of the Moon, with some patching up, have
now been in use in the standard astronomical ephemerides for a
full half century. With every passing year the necessity of ^^
placing them by improved ones becomes more urgent. My own
investigations on the Moon's motion have always been carried on
with the view of ultimately constructing new tables, while experi-
enco in the use of Hansen's tables has from time to time formed a
basis for ii study uf the rel.itive merits of various forms of the
lunar tlieory for the purpose of tabulation. But, as the yeais have
passed, it has bec«jme increasingly apparent that I must leave to
other hands the execution of the desired work. I therefore
venture to summarise the suggestions which I have to make on tlie
whole subject.
§ I. General Form of Tables.
All my experience with Hansen's tables has led me to the cou-
clusion that if the problem were only that of enabling an ephemeris
of the Moon to be computed with the use of the fewest figures, it
would scarcely be possible to improve on Hansen's arguments and
system of tabulation. The Hansenian perturbations of the mean
anomaly are more rapidly convergent than those of any co-ordinate
that can be used, and therefore require fewest tables. The ex-
pression of the fundamental argument in terms of the time may
also have a certain advantage, though this is a point on which I
feel less confident, because the best unit is not a decimal of a day.
But the mental labour to be performed is not measured merely
by the number of figures taken out and written down. A
" straif^ht-ahead " computation has a decided advantage over one
in which it is necessary to form numbers from preceding tables, or
to introduce tables of lo<^'arithms, as we must when we pass from
Hansen's fundamental argument to the true longitude. Thi.^
remark is especially applicable to the reduction to the ecliptic.
The mental labour of forming arguments from numbers already
used and of combining results from various tables is intensified by
the care and attention which then have to be bestowed, and which
it is desirable to i^wd^t vsiWDL^c^eaar^*
Jtme 1908.
of New Tables of the Moon,
539
■ tab
The desired uaiformity in proceeding would be atUuned in the
highest degree by tabulating the pertiirbalions of the ecliptic
longitude and latitude in the lorni to which they are reduced by
Brown, using a uniform nystero of argunieiits for the tablea. But
the number of tablea then requisite would be so great that it is
doubtful whether they cuiVld be put into a single volume of
reasonable fiiae, say that of Hansen's tables as they now are. The
most troublesome and important terms w.mld he those arising
from the redaction to the ecliptic. It may l>e added tijat I have
never found Hanst^n'a system of constructing the double-entry
tables for intervals of 0*^*25 to offer a great advantage over the
le of 1 2-hour intervals, except when an isolated place is to be
mputed.
The Tnodificiitiou of the plan which I have to suggest will beat
^^^ Bt^en by starting with Hanseu^s fundamental argument After
^^pt is formed J two steps are ref|uired — ^the reduction from the iu-
^Bequalitv of mean longitude to that of true Ir^n^itude in orbit, and
^Hihe reduction to the ecliptic. When the reduictions are made in
" the general Jormuhp, tabukted, tm they will be if ecliptic co-
ordinatfts are taVmlated, each of these stajm adds a number of
I additional inequalities, hut I think those arising froiu the second
reduction exceed in number and magnitiido thofte arising from the
first. However this may be, it is certain that the lahularion of the
^^#rU6 longitude will require much more voluminous tables than will
^^wliat of the Hansenian mean lotigittide.
j^B What I would nugfi^eat is, therefore, the tahukti">n of the
^■longitude in orbit, that co-ordinate being defined as the distance
^^from the mean node to the circle of lutilude passing through the
Moon perpendicular to the ecliptic. More geometric symmetry
Twould be attained by taking as the fundamental plane the mean
moving orbit of the Moon, and referring the longttu<le and latitude
to that plane. But this would require a multiplication of the
quantities by certain factors in order to tmd the true longitude.
If the principal term of the latitude is computed with the true
I argument of latitude, the inequalities are fewer and smaller than
if the mean argument is used.
§ 2. Unit of Taltuiar Longitude^
In the case of the longitude, the next question is that of the
unit to be chosen. It is so importiint to avoid the use of larger
numbers than is necessary that this choice requires careful con-
aideratiom The tabulated unit of Hansen ^s fundamental argument
IB approximately o"*oo5. The smallness of tliis quantity makes
the interpolation laborious without really adding materially to the
accuracy of the result. To devise the best unit, we must first con-
sider the degree of precision to be reached by some arbitrarily
chosen unit, say o"'oi. Here some statements relating to the
accumulation of small accidental errors become necessary.
S40 Prof. Simon Newcomhy Form and Arrangement, lxyul 8,
§ 3. Errors accumulating from omitted decimals.
The theory of errors accumulating from omitted decimals is
not usually developed in a way that seems to me entirely satis-
factory. I therefore begin by stating some principles, definitious,
and results pertaining to the subject.
1. I use the term probable value of a doubtful quantity in
the sense introduced by Poincare, which is —
If Vl,V2»- • • •^'n
be all the essentially different possible values of a quantity r, and
if
Piii>2> • • • 'Pn
be the several probabilities of these values, then the probable
value of t; is that given by the equation
v=pif\+P2V2+ . . • . +PhV„.
That is, the probable value is the mean of all the possible values^
each weighted according to its probability.
2. I deal, in the case of each quantity, with the probable value
of the square of its deviation from the truth. The square root of
this square is generally designated in astronomy as the y/iean error,
Pearson has introduced the somewhat more appropriate term of
"standard deviation," which I abbreviate to S.D. We may there-
fore define this as the square root of the probable value of the
square of the deviation.
3. Let us consider the sum S of any number n of independent
quantities, 7^ , '/o , (/g fj,, •
Lot these ^'s be uncertain by the several standard deviations
If we put € for the S.D. of S we shall then have
€- = €i- + €.r + €3-+ .... +€/.
The advanta^t; of this equation is that it is independent of the
law of probability of an error as a function of its magnitude,
which is not in all cases the normal law. For example, the error
arising from the omission of a periodic term has a well-defined
absolute maximum equal to the coefficient of the term. Moreover,
its maximum value is more probable than any other. The
standard deviation arising from the omission of a periodic term
a sin 7nt is
a
€=± y- .
\'2
An examination of the coefficients of longitude found by Brown
and Hill shows that there are about 300 periodic terms whose
June 1908*
of New Tables of the Moon,
541
>
coeflicients lie between the limits o"'oi and o"*ooi. I take this
lower limit aa that bejond which it is unneceBsary to go* In
estimating the S.D. I take o''*oi as the unit. An approximate
estimate of the distribution of these coefficients in magnitude
shows that the square of the S.D. produced by omitting them is,
with sufhcient exactness,
€2 = 28.
There remain^ l»y a rou^^h estimate, about 300 terms exceeding the
limit o"*oi, nearly all of which 1 assume will be tabulated. I also
assume that the individual numbers of these tables will he formed
by carrying each number to o"'ooi, and that the last decimal will
be dropped in the final tabulated number^ which will b^ given
only to o"*oi. Making due allowance for all imperfections^ I find
that the at^amlard deviation of a number interpolated from a single
table thus formed will be ±o'26 if the number is written down to
one decimal beyond that of the tables. But if the nund>er is, as
usual, only wTitten to the tabular number of decimals^ the deviation
will be ±0*39.
I assume that not more than 120 tabular numbers will be
added to form the longitude* The contribution to (S.D.)* ariiiing
from the summation of these numbers is
I
120K 0*39-= 18*2 •
The imperfections of the arguments will also have their
influence. The deviation produced by them may be reiluced by
giving each argument to one decimal beyond that required by the
condition that the error arising from a unit error of the argument
shall always be less than that of the tabular unit. But, without
going beyond this role, the etlect of the errors of the argument
will not exceed that arising from the addition of thirty more
tabular numbers. We may thus have —
(S.D.)- from errors of arguments =4*5.
In some cases the effect of the imperfections of the correction
for the 8eci»nd difirerence<s may aild to the 8.D. I think that, with
a little skill and attention on the part of the computer, this S.D.
need not exceed ±o'2, giving 4*8 for its entire contribution to
(S.D.)^.
Summing np all the sources of accidental deviation of the
tabular results from theory we have —
From the omission of small terms
,, „ tabular decimals
„ errors of arguments .
,. i» of second diff.
In aU .
And for the sum,
18
5
5
(S.D.)a = 56
aD. = 7-5.
542 Pro/ Simon Netoeonib, Form and Arrangement lxviil 8,
We shall therefore have, in the case of e*ch compated longi*
tude, a S.D. of ±o'''075 and a prohable etror of o"*o5.
§ 4. Degree of predeion required.
Let us compare this with the degree of precision required in a
comparison with observatiob. My experience in the use and
examination of lunar observations leads me to the conclusion that
no single observation of any sort can be practically made withoat
a mean error exceeding ±o''*5, corresponding to a probable error
of ± o"*34. It is desirable that the mean error of a co-ordinate
found from the tables should be less than this. But all the results
obtained from lunar observations depend upon a great nnmt»er of
observations, which make the accidental errors unimportant io
comparison with the systematic ones. The practical advanta$;e of
a degree of precision above that just mentioned in the tabular
places is very small, and is practically evanescent if reduced below
± o"'4. This degree of precision will be surpassed by adopting as
the unit to be tabulated the 10"^ part of the circumference, or
o"oi296. Of course the unit o"*oi would answer our purpose if
deemed more conveuient in use. But the smaller the numbers
usiid, the easier the computer will find it to avoid small errors,
while the S.D. will still fall below ±o"*09.
There is, however, one point still to be considered in this
connection which may modify our conclusions. Granting an S.D.
of ±o"'io in the individual longitudes, we must expect that in
the course of a year there may he three or four of the 730
tabulated longitudes in error by three times the S.D., and possibly
one of four times this amount. But every error approaching such
a magnitude as this will be detected by differencing the 12-hour
ephemeris. A legitimate proceeding will then be to smooth oif the
ephemeris by such small corrections as shall reduce the higher, say
the fifth or sixth, difterences to a sufficiently smooth series. Etich
corrected tabular result may then, be regarded as the mean of two
or more n(MghV>ourin^' quantities, and the maximum error of the
ephemeris will be reduced nearly to the mean S.D. In a word, we
may fairly count on having an ephemeris in which all the errors
oxceedini^' some limit between o"*i2 and o"*3o will be eliminateii.
This limit is still within the errors of the best observations, and
the cases in which it is approached will be rare.
§ 5. Reduction to sexagesimal units.
The proposed unit^ will require the retluction of the final
longitudes to degrees, minutes, and seconds. The tables necessary
for this purpose will perhaps fill four pages, and the computation
will be equivalent to the entry of three additional tables.
If the unit o"-oi is deemed preferable, its use will still require
some study. It wa's* ?tvic^\^v^^ \\\ "^evt^^V Tables of the Moon,
J une 1908. of New Tables of tki Moon.
543
pablished in 1853. The tubular iiumboi*s were there expressed m
degrees und seconds, minutes being ignoi'ed. I found the use of
this system catnbroiiB, and shonld prefer to use seconds pure and
simple, subtracting 1,196,000" or its multiples when necessary.
The proposed circumferential unit does away with this Bubtraction.
Although it is a tittle easier to change the degrees into seconds and
minutes than it is tu change the circunifi^rential unit, I still think
the advantage to lie with th«) latter.
It may be of interest in this connection to note that if we
should baae the unit on the degree, tabtilating to 0**00001, the S.D,
of the individual longitudes would still be only ±o"'i8, and we
might be fairly confident that no error exceeding o"'4 would remain
in a smoothed -otl* aruiual ephemeris as often as once a year.
Of course all this presupposes that the computer is always
careful never to make a greater error than 0*5 in interpolating and
writing down his number. The question may arise whi?ther it is
not well to allow him a margin of one or two units, by adojjting
smaller units. My answer is that the labour of handling large
numbers involves more mental strain than that required in the
accurate^ haudHug of .small number^*, and that the assigned standard
of precision will be more easily reached by the direful use of the
smaller numbers than by the careless use of the larger ones.
§ 6. Epochs and Arguments.
For the practical work of computing places uf the Muon for
given dates, I tlo not think that any system more convenient than
the usual on© can be devised. The Hanattnian form, in which the
Gregorian and Julian calendatit are u.<3ed, is the most convenient of
all. But it ia always de^sirable to give the tables such a form that
the relation betw^een the tubular numbers and the original elements
aball be easily examined, and corrections to the theory readily
applied. This suggests a slight sacrifice of ease in computing an
S8( dated position, or an ephemeris, to the requirements of the
theoretical investirjator.
Simplicity in the other direction is reached by the use of days
of the Jtilian period. Thin was first employed, I believe, by Peirce,
and is now exienaiveiy used in astromuny, especially in Oppoker*8
works relating to eclipses. In using this system, a first and easy
step is the reduction of the ordinary calendar date to days of the
Julian period. Then absolute uniformity is reached in the con-
struction and use of the tablo».
The principal immediate drawback of this system is that, if
used unmodified, the period of 1000 days must take the place of
the year. The formation of the arguments of short pi-riod is
then inconvenient Many of the Iniiar arguments have |>eriods not
differing much from a month. From t2 to 15 multiples then
suffice when the year is used, but with the pi;si'iod of 1000 days
the number of multtples to be tabulated and subtracted will fre*
qaently be between 30 and 40, and some times more, Qt ^^Mt^ft^
544
Pwf. H. J?. Turner, A^i EmmpU lxvhl I
this difficulty can be lessened by taking 500 days instead of ic
as the m^coiid unit. But this will detract from simplicity of fonu.
A yet more serious drawback to the theoreti<ml investigator
that the fundamental epochs usmdly adopt 4id in at^troDomv,
for whit^h the elements must be found, do not correspond to ftaj
power of 10 in the days of the Julian period. A complete trau
formation of the elements is therefore required to form the numb
on which the tables are based. If, therefore, multiple* of 500 1
1000 days are used instead of years, I should prefer to count the^
back from 1900*0, thus gaining all the advantages of the Julia
period without any other diaadvantap^e than tliat of non-correaf^
ence with the eclipse and other tables of Oppolzer,
The reduction of such a system to the ordinary calendar may
be luaile a very simple matter, tt seems feo me, therefore, that the
maximum of advantage will be reached by giving the fandamental
argunmnt-s for cycles and periods based on multiples of 500 days
before and after the fundamental epoch 1900 Jan. o.
Probably the most convenient fundamental quantities to tabu-
latf^ yfiW be the longitude of tht; node, and the mean distancea of
the Moon and of its perigee from the, node, all expressed in circum-
terential units. Then, whatever form the tables may be throwij
into, we shall have the nearest approach to a simple, »t
ahead computation*
Finally, a serious problem is that of summing perhaps too
periodic terms with coefficients not differing greatly from o"*ot,
I have devised a machine for this purposie, the description of which
must form the subject of another publication.
An Example of Profegsor Earl Pearson's CcdculoHon 0/ *
Hon in the case of the Feriodic Inequedilies of Long-^
Variables, By H> H. Turner, D.Sc, RR.S., SaviliAU
Professor.
I* The following note is vvritten with a twofold purpoo^^
Firstly, it is lioped that an indication of some value has he6l^|
obtained with regard to the featun^s of '* long- period" variability^"
and secondly, the opportunity is taken to write out in ftill a simple
example of the calculation of ^^ correlation ** between quantities by
the methods of Professor Karl Pearson.
In the M.N, for March last (p. 416) Professor Pearson hi
ive an admirable summary of methods ; but he naturally did
repeat the elementary working which has become so familiar
hini, and has been given often before in other connections, Th
are doubtless inany to whom this working is alreiidy famili
but there are certainly many others who do not know it and t«
might use it if they had an astronomical example readily accessible*
In these busy days many people have not the leisure to search
for references m ftciewtitic liurature outside their own stibjecl*
June 1908 of Prof I Karl Pmrson^s Calculaiion, etc, 54 S
2» In support of my view that there is need for an example,
I may cite an illaRtrfttion shown rae by Professor E. C, Pickering
(see Ohgervaianj^ March 1905^ p. 153)*
Suppose we have the following observed Values of A and B : —
A .
.567
6 7 8
7 8 9
B .
,666
7 7 7
8 8 8
First group according to B» in sets of three for which B has
the same value.
Then when
Therefore
Mean
B = 6 7 S
A = 6 7 8
A = B.
Secondly, group according to A.
Then when A = 5 6 7 8 9
Mean l; = 6 61 7 7 J 8
Therefore (A- 7) -2(1^-7).
Now, neither Profeasor Pickering nor myself was prepared at
that time to deal with this situation hy a definite procejis ; and
yet this is just an elementary case of the kind which Professor
Pearson*8 methods were deviised to meet.
This example is worked oiit^helow, and it is shown that the
mumerical measure df the corrt^lation is
r=*oS±*22
or almost nothing at all : so that^ in spite of appearances to the
contrary, we are not entitled to assume any relationship between
A and B, Putting it in another way, one proposed relation
(A = B) is as good as another ( A - 7) = 2(B — 7).
3* A point of detail may be mentioned here. In much
statistical work, a large number of figures are need. Thus we get
such statements'* as
1262*51
2870 K 1*13637 X l'S2135
= 25445'
The probable error of r bein^; about ±*or, some of these ti£3[TireB
are superfluous; and in what follows fewer iigures are used*
This, however, represents a persontil view which is, I find, not
generally approved by other workers*
4- The particular example selected for treatment is the
discussion of the elementa of maximiim given by Chandler for
long-period variables. The following particulars are taken from
* Frequency Curvt^j^ and Corrtlation^ by W, P, Eldertou, p. ttg: an
excellent little book, from which much i» to b« learaed.
546
Prof, H. H. TWntfr, An BxaimpU lzviilS,
his ''Beyirian of Elements of Third Catalogue" (ilf6ioiioiiitea{
Journal, No. 553) :—
BUr.
B Androiu.
S Cassiop.
2400141
2401603
Poriod,
+ 410*3 E + 30 sin (ii* E + 90')
+ 610-5 E + 37 sin (15** E + 59')
and so ou. The mean period of S Cassiop. is 610*5 days; but
there is an inequality which displaces the maximum 37 days one
way, and la periods later (since 180715*= 12) the displacement
is 37 days in the other direction. At these times the period is
about the mean, but midway between such times it is longer and
shorter. In the "Revision" above mentioned, Chandler gives
such inequalities for 37 stars, as shown in Table I. We shall
for the present only consider the period P, the coefficient G, and
the argument A; thus for S Cassiop. P=6io"5, C = 37, and
A = 15''. The epoch 59'' does not concern us at present
Table I.
star's Xame.
No.
P
C
A
Phase.
.M - M
oP
R Androm.
112
410
30
12
21S
120
-170
S Cassiop.
432
610
37
15
148
280
- 50
S Pisoiuin
434
404
18
10
57
163
- 7S
K Arietis
7S2
187
7
5
292
92
- 3
0 Coti
806
332
18
5
...
125
- 82
U Persci
1222
210
15
8
224
96
- iS
H Aurigji;
1S55
459
19
12
320
235
-r II
R LyiK is
2478
379
14
15
249
1S6
- 7
R Gemin.
2528
370
35
6
121
121
-128
S Can. Mill.
26S4
330
20
12
120
164
- 2
R Cancri
2946
362
60
6
341
125
- 112
R Carina*
341^
310
25
9
289
136
- 3S
R Leo Min.
3477
371
20
10
II
165
- 41
R Urs. Maj.
3^525
302
i(
8
63
IIO
- 82
T Urs. JMaj.
451 1
257
20
9
203
108
- 4-
R Virgiiiis
4521
145
20
2
103
68
- 9
S Urs. Maj.
4557
226
35
5
309
108
- 10
S BootiB
5^57
270
60
4
87
132
- 6
R Camclop.
SU}0
270
65
4
244
. 142
+ 14
R Boiitis
S^^T
-r^i
9
9
251
102
- 20
June 1908. of Pf^f,KaH Pear9MsCaUndc^%m,etc. 547
Tablk l.—cimiiniud.
Stor's Name.
No.
V
c
A
Phase.
M-m
aP
S Serpentifl
5501
369
116
0
4
122
...
...
SCoronse
5504
361
8
12
81
120
- 121
RSerpentis
5677
357
35
4
109
151
- 55
R Hereulis
5770
318
17
10
29
...
...
W Hereulis
5950
280
26
13
288
128
- 24
S Hereulis
6044
308
35
9
239
152
- 4
T Hereulis
6512
165
id
5
152
79
- 7
R Sagittarii
6905
269
18
10
18
138
+ 7
S Sagittarii
6921
231
15
10
167
102
- 27
R Delphini
7261
284
26
9
266
130
- 24
U Capric
7455
203
20
5
67
...
...
T Aquarii
7468
203
8
7
357
88
- 27
R Vulpec.
7560
137
18
4
127
62
- 13
X Capric.
7577
218
20
10
98
117
+ 16
R Pegasi
S290
378
60
8
71
172
- 34
R Aquarii
8512
387
35
10
97
...
...
R Casaiop.
8600
432
32
9
233
182
- 68
5. The first two columns of Table I. give the star's name and
its number on Chandler's system. The third column, P, pjives the
period in days ; C is the coefficient of the periodic inequality in
dayp, and A the coefficient of E within the bracket. The explana-
tion of the last three columns will be given later.
6. Now the example selected to be given in full is that of the
relation between P and A. To determine whether there is such
a relation, we could, of course, proceed in the ordinary way to
group together stars with nearly the same P, and take the mean
values of .A for them. This would give us a fair indication, but no
notion of its probable error. Professor Pearson's procedure is not
much longer ; it includes the ordinary procedure, and it gives us
a definite measure of the probability of the relation being* real.
7. We first form a "correlation table" as in Table II.
^i^^K^^
S48
Prof. H. J7. Turm^y An Sxumfte LXTm.8
Tablv II.
Oorrdalion Table for P and A*
FlDdlTl. As
.'
3*
4'
5"
6"
f
r
9"
la*
11*
nT
'*'
H'
1,
Goi to 6S0
551 to 600
501 to 550
451 ta soo
401 to 450
—
I
,
0
0
0
C
0
0 !q
? •
t i 0
9 *
I
c
I
1 i 0 0
• — i^j
<
35* to 400
2 lo
2
0
1
0
2 ! 0 1 1 j 0 0
301 to 350
T-rr"
0
0 1
2
1 -^
10 100
1
251 to 300
3
^6
0
0
f —
1 «
ii 1
2
I 0 1 0 ,1 1 0
I .f s i J
4
30I to 250
__
jo I2 !o
I ] '
1
2 0 1 0 ! 0 0
i
_
151 td 200
'0 2 1 0 1 0 , 0
1 li la t* (1 1
loi to 150
I 0 , I , 0 , 0 ' 0 , 0
^ums
1
0
5
5 ^ 13
6
7 0 4 I 1 0 :
A
Sum.
Factor.
Product.
ProJluct.
P Sum.
Factor.
Product.
Product.
0.
2
I
■7
- 7
49
125
2
-4
- 8
32
3
0
-6
0
0
175
2
-3
- 6
18
4
5
-5
- 25
125
225
7
-2
-14
28
.S
S
-4
20
80
275
6
- I
- 6
6
6
2
- 3
6
18
325
6
0
0
0
Productt
7
I
-2
- 2
4
375
9
+ 1
+ 9
9
- 17"
8
3
- I
- 3
3
425
3
+ 2
+ 6
12
-i- 104 -
9
6
0
0
0
475
1
+ 3
+ 3
9
10
7
+ 1
+ 7
7
525
0
+ 4
0
0
37(--84(--3
II
0
+ 2
0
0
575
0
+ 5
0
0
Differtn
12
4
+ 3
+ 12
36
625
I
+ 6
+ 6
36
r =
13
I
+ 4
+ 4
16
Sums
37
...
- 10
150
=0*
14
0
+ 5
0
0
Mftans
(>'i
and i^q)
-•27
4-05
IS
2
+ 6
+ 12
72
j <rp--
= v'»'2-»'r=
= v^3-98 =
= 2'00
Sums
37
-28
410
1
Meanfl
(»'i'
lud 1^2)
-•84
+ 11 -08
^4 =
= V^9-»'l' =
Vio'37
= 322
[
Jiine 1908. 0/ Prof, Karl Pearsons, Calculation, etc.
549
8. This requires little expiatmtioiL We divide the periods into
groups of 50 dnys as shown in the first column, and the number of
pariods in each group la sliown in the Jinal column. For the
values of A no collection m groups is necessary, successive degree*
being shown in the top Hut*, and the number of con'espmjding
Cftaes in the bottom lioe. In the body of the table are given, in
large figures, the number of cases correaponding t<> a do tin it©
degree for each group of perimls. The small figures will be
referred U* presently.
9. The thick Hues indicate the groups which contain approxi-
mately the mean of each co-ordinate. They are chiefly for con*
venience in working (to keep the numb ers small), and if a wrong
group la taken no real harm is done.
10. Tht^ figures below the table represent the whole working*
We first form Vj and v., for each co-ordinate hj a process which is
tolerably clear to inspection. For A write down the (top line for
convenience only — not used in working ; and the) Witom Hne of
the table. Follow with a sequence of units, with o at the place of
theadoptetl mean» Multiply the two columns; and ii^^aiii multiply
the last two columns. We thus get «Vj and nvc, , where n is the
number of observationp, and v^ , v^ two quantities reqiiired.
Dividing by », we get Vj and v^ , and finally
[If greoter accuracy is required < we should subtract also
**Sheppard's correction" of j^^ from v^ before taking the square
root]
It. The same procedure with the columns gives us fT^=^ 2*00.
12. We now form the product S(AP). The number in each
box is to be multii>lied by the little number shown in the corner of
the box, which will be seen to be the product jri/^ where .r repre-
sents the number of boxes to the right, and y the number up» fnuu
the adopted mean» The products in the fuur main divisions of
the table are shown diagrammatic ally, and from them we get
S'(AP)-i42.
From this we subtract JiViV^\ where n is the number of observa-
tions, and Vj, v^^ have been found ; and thus
i^ii = 142-9 =
S{AP) = SXAP)
Then the ** correlation " r is
133
13. This is quite a respectable value for r— anything over 0*5
is worth serious attention. But to complete our information we
want the probable error of r, which is given by the fornnda
p.e = *67(i-^r^)/>.
which can be taken from the following small tabk (^T^H^WY^.
5 so Prof. H. H. Tufrntr, An Example LXTm.8,
For the present case we have !»■> 37, r » 0*56, anid thus probable
error = ± '08.
Tabls III.
Probable error 0/ r.
10
•208
•202
•193
•177
•158
•136
•107
•076
■041
20
•148
•143
•137
•125
•112
X)96
•076
•OS4
•029
30
•121
•117
•112
•102
•091
•079
•062
•044
tB4
40
•104
•lOI
•096
•088
•079
•068
•054
•038
•021
50
•093
•090
•086
•079
•070
•061
•048
034
•018
60
•085
•083
•079
•072
•064
•056
044
•031
•017
70
•079
076
•073.
•067
•059
•051
•040
•029
•015
80
•074
•072
•068
•063
•056
048
•038
X>27
•015
90
•069
•067
064
•059
•053
•04s
•036
•02s
•014
100
•066
•064
•061
•056
•050
•043
•034
'024
x)i3
14. Cuminj^ now to the relation between P and A, the mean
value of A in ^ot by adding v^ to our adopted mean, i.e. it is
9* — o°'84 = 8 *i6 ; and the mean value of P is 325 - 0-27 x 50 =
3 1 1 '5 days, thn unit adopted in the table being 50 days, by
which therefore we multiply vy
Assumin;,' u linear relation between A and P, there are two
a})propriate tonus for it, viz.
o-|.\ 50 / \ 50 / CTa
and those now to correlation methods will notice with surprise
that these are not convertible. To save repeating explanations
alieady i^iven in detail elsewhere, we need only remark that to
timl tile most probable value of A when P is given is not the
same as to tind the most probable value of P when A is given.
There is the same /.:hid of difference (the analogy must not be
tak<Mi t(M) s. riously) as between finding from the fact that a man
is 25 the dati' «»f his i)robable death, and finding from the date
of his deatii tin' i»robable date of his being 25 : the latter case is
clearly complic:it»Ml by the possibihty that he may never have
r«;ached 25 at all.
15. In astronomical examples it will frequently happen iLat
one of the variables is better determined than the other, and hence
one of the tw(> jilternative forms is indicated as preferable. Thus
in our case P is well known ; most of the periods are known within
a day or two, some perhaps to fractions of a day; and since our
unit in Table II. was 50 days, the precision is less than ont^tenih
of the unit, l^vvt A may be several degrees wrong, t.e, aeyeral
June 1908. of Prof. Karl PearwrCs CaUulation, etc. 551
whole units. Hence it is natural to determine A from P, and the
appropriate equation is
or A = 2"-6 + -oi8P,
P being now measured in days, and not in units of 50 days. The
most probable values of A corresponding to different periods are
thus:
For P=ioo^
A= 4-4
200"
6*'-2
300'*
8'-o
400**
9-8
500**
6oo*^
^3 4
16. This single example will suffice to show the method of
finding r in such cases. There are many other points to be
considered, e.g. how to deal with cases where the relation is not
linear, or where one of the quantities is not measured but only
described. But it seems probable that in astronomy the evalua-
tion of r by the above simple process will be the point most often
occurring.
17. But before leaving the more general topic of correlation
for the particular application of it we have in view, it is a matter
of some interest to return now to the simple example given in § 2,
and work it out as below.
Table IV.
The example given in § 2.
^*> '
7
8 ' 9
6 I I
t
^ 1
^.^^^1
_
' i_'-L
1
t
3
S '
I
I
I
1
- - — —
. -J
?1
i ' *
3
2 4
9
A
Sam.
Factor. I'l
y-i
I J Sum.
Factor.
n
»*a
!>
I
-2 -2
4
6 3
- I
-3
3
Product S'(AB)
6
2
-I -2
2
7 3
0
+ 3 , 0
7
3
2
0 ...
+ 1 +2
2
8 3
+ r
+ 3
3
0 1 +3
8
Sums 9
0
6
= 6
9
I
+ 2 +2
4
Sums
9
0
12
0'A =
^/i2 = 3-46
(r„ =
-J6 =
= 2-45
6
r =
9X ^12 X ^/6
r^~ = -08 .
552
Prof. K K Turner, An Example LXTIILS.
This is a very low value, and on referring to Table III. we «*
that tlie probable error is greater than 0*2 : 90 that the corteJaliufi
of the quantities A and B may be regarded as on sup port oil. And
yet at first dght there is a fair app<??irance of relationship. Thi5
ahows the advantage of having a numerical te^t.
18. Wt; proceed now to discuss the interpretation of this and
Bimikr reaulta. And in the iiret place it i8 an obvious so^ifcstton
to inquire whether C is also related to P. In a precisely aimiUr
manner, which need not be given in detail^ we tind the currelatioa
for C and I* to be
r-=-30±Mo,
and for the probable relationship
(C- 27*2)= 'o64(P- 311)
or C»7'3 + *o64Pp
where C and F are measured in days. But the value of r and ni
probable error show that the probability of a relation nhip ts bert
more doubtful. This is i^uite possibly due to the much j^^reater
uncertainty uf the values of C, which is more diHiculb to det^Tmint
than A. for reasons which those who have disciisaed Tarialile star
observations will readily appreciate.
With this formula the values of C would be :
p = 100^^
200'^
300^*
400**
Soo'^
600**
G= 14
20
26
33
39
46
19. Now, having obtained the suggestion of correlation and
two formulsQ for A ami C, I examined in detail some iudindnat
cases which had cume under notice and which are given below.
It will l>e seen that there is good coniimiatory evidence, so far is
it goes, of these relattonshipi).
3 Camopem (Ch. No. 432).
2C. In Mein, R,A,S,f Iv., p, Ixix, the Kousdon observationa an
compared with Chandler's formula in his 3rd Catalogue :
6io*5E+ 50 sin (10* E+ 50**) .
Froni observations E= 17 to 21 (about) a period of 630"7 days j
derived, ditfering sensibly from 6o6'2 given by the formu
It is remarked ; ** To obtain [6307 days] from the formula we nus
alter the periodic term in some w-ay, and espeeinlly we mus*
increase the coefficient, for with the coefficient 50 thr greatest
interval between two consecutive maxima is the greatest value of
6io'5 + 5o[sin ^-sin (fl+ 10*)] ,
which is 6io*5 + 100 sin 5' or 619-3 daya. But we cannot diacu
this point without reference to other observations. Chandler mtd'
maxima in 1&43 B^"a^ ^^^Ik-^Si ^^^ ^^7 ^^^ formula must thu*
June 1908. of Prof. Karl Pearmn'& CalcukUion, etc. 555
agree with the old one at these periods. Tentatively we may
suggest some such modificattoi} as
2401590 + 61 5E+ 75 sin (12* E + Qo')/*
Chandler's revision gives
6io'5E + 37 8in(is*E+59').
The value of the periodic term deduced from tlie period 610
days by the formulaB found is
47 sin (i3''6 K + ?).
The coefficient giiren by the formula is thua in accord witli
Chandler^a first thonyflit, and lies between his revised value and
the value sugjL(e9te(l very teutatively by the Ronsdoii oUsetvationH.
The mean of the three different suggested values, 75, 50, and 37, is
54; and the fact that the smallest of these, 37, was used in
deducing; the forraula accounts for inirt of the dilference between
the formula value 47 and this mean.
It is perhaps worth noting that if the suggeetioQ of 6=75
(made quite independently of the present invcatigatiou ) is
adopted instead of Chandler's C - 37, the value of r is raised from
•30 to -43.
The argument I3'*6 giyen by the formula is between the valne
si^ggested by the Rousdon observations and Chandler's reviston.
R UT$m Majoru (Ch. Ko. 3835).
21. In Mem. R.A.S., Iv,. p, Ixx^-i, the Kousdon observations
are compared with Chandler's 3rd Catalogue formula
302*iE+i5 sin {10° E+ 190').
It is shown that the Rousdon observations indicate an error of
150* in the periodic term : so that the coefficient of K should be
8' insteatl of ro*. Ghandler^s revision gives
3oi'iE-(-iT sin (8* E + 238').
PogBon's observations of this star have since been very carefully
diaeussed by Jliss Blas^g ; and the outcome of this entirely
independent discussior) (which will shortly be published in
MeiH. M.A.S.^ Iviii.j in the introdaction to Pogson*a observations)
was to indicate a periodic term
40 sin (S'E + I).
The formula gives for 302 days a term
27 sin (8" E + ]),
in which the coefficient is midway between Chandlei^i fovuloo
and the Pogson indication ; and the argument in good accordance
with both.
4P
554 P'Tof. H. H. Turner, An Example LX¥in.8,
T Ursa Majorls (Ch. No. 451 1).
22. In Mem. R.A.S,, Iv,, p. Ixxviii, the Rousdon observatioDS
are compared with Chandler's 3rd Catalogue formula
257-2E + 20 sin (9* E+qo'^,
with the conclusion that the agreement ' is good. Chandler's
revision gives no cbange. The correlation formulae give for a
period of 257 days a periodic term 24 sin (7* E + ^).
S Urate Majoi-is (Ch.'No. 4557).
23. On p. Ixxx the Rousdon observations are compared with
Chandler's 3rd Catalogue formula
226-iE + 43 sin (5*76 E+ iSi'^'s) ,
with the conclusion that " there is a fairly satisfkctory accordance,
though some correction to the formula would improve it."
Chandler's revision gives
226-5E + 35 sin (5^-4 £+194**) .
The correlation formulae give for a period of 2 26'5 ^*js a periodic
term 22 sin (6' "5 E + ?;, which suggests that Chandler's diniiDU-
tion of the coethcient has not been carried far enough, though in
the right direction.
*S Ci/gni (Ch. No. 7220).
24. On p. Ixxxix the Rousdon observations are compared with
Chandler's formula
322'8E+ 15 sin (12' E + 66'').
It is remarked that the ** periods at (the Rousdon) ej>och would
agree better if the coefiicient of E in the periodic term were
smaller, say 9° instead of 12*."
In Chandler's revision the periodic term is replaced by a
secular term
323E + 0-015E2.
The correLition formulae give for a period of 323 days
28 sin (8* E + ?),
so that the only suggestion made at the time of discussing the
Rousdon observations is in the direction of better accordance with
the form u he.
R J^agittx (Ch. No. 7257).
25. This star might have been included in Table I., but it was
decided to draw the line as regards "long-period variables" at 100
<iaya. The elements given in the revision are
']o*^C>Y.A-6<5^aiu (2*'2 5 +47*').
J line 1908, of Prof, Karl Fear$on*s Calculation^ etc.
555
Extrapolating our formulae, we get C = 12 and A = 3''9. But if we
decide tlmt this star may bt! regttidtid as a long-period variable,
we should include it in our table, and I ben tbe values of C and A
would be fuund closer to those observed, since the star would liave
f great weight. Indeed, the correlatiou for A and P ia raised to
I r = 0*64. ±'07, and the formula becomes
f 0:
or
(A-8-.,-.-o,C>-fS)
A^ i'-9 + *02o P,
which gives A = 3'*3 for P =s Jo,
Thn value of r for C and P is, however, not much improved,
being raised from '50 to *^2.
^H B CamopetG' (Cb, No. 8600).
^B 26. On p. xcii of the Rouadon Memoir, the observations are
^Roznpared with Chandler's 3rd Catalogue formula,
^B 429*5E -4- 25 sin (i 5" E -f o') ,
¥
id it is remarked : —
**The correctiofjs to period Bhown by the di^erent columns of
the Rousdon observations are so consistent that it is difficult to
believe tlmt the mean restdt can be so erroneous as the formula
would make it. If the formula were altered to
431E + 30 sin (12° E + 9')
\
certain improvement] ; but it is of course
the formula dehnitively without diacusaing
[there would be a
im]^K)ssibIe to alter
other observations."
Chandler's revision, which appeared after the above words were
iu type, gives
43r6E + 32 sin (9" E-i-60'*).
The correlation formulae give for the period 431 days a periodic
I term
b 35 sin (10^7 E+1),
II ♦.,.
owing that the improvements aug^ested by the Rousdon obaerva-
ions were in the right direction, though not sufficient in magni-
tude ; and that Chandler** revision is in good accord with the
formula.
S Delphini (Ch, No, 7431).
27, Chandler gives no indication of a periodic term in his
"revision," printing the period as 277 '5 days. In discussing
Baxendell's observulions (before the present correlation work had
been undertaken at all), Miss Blagg found clear indications of a
periodic term at which a preliminary guess of 9 sin (7 J" E+ T) was
e, the 9 being mere guess-work, but the 7^' b^\u^md\!i:tt.\fe^ WiXv
p
556
Prof, K H, TwnMir, An Example LXVin.8,
fair precision. The correlation formalflB give for a period » 77*5 days
A— 7**6, which ii eloae to the value guessed. For ti&e coefficisBt
C the formula gives 95 days, which is a good deal larger then
the guessed 9 ; hut on calculating the ooeffideut from the separate
oorrectioBs to epoch the coefficient came oat 38*3, which accords
well with the formula. Although the calculation is of a roa^^
kind, it seems worth while giving it here to show the kind of
accordance that is at present ohtainahle.
Tablv IY.
BazendeU*a^2Wl»lttii
».
B
ObMTTOd
to Epoch.
Aranment
(7^* E+coiut.)
8iii(Ai|>.
Pkodnet
I.
-I2d
- 26-
-•44
+ 53
II.
- 5
- 181
-•32
+ 116
III.
+ 3
- XI
-•19
- 0-6
IV.
- 5
- 3i
-•09
+ 05
V.
+ 11
+ 4
+ •07
+ 0*8
VI.
+ 20
+ Hi
+ •20
+ 0-4
VII.
+ 21
+ 19
+ •33
+ 6'9
VIII.
+ 6
+ 26i
+ •45
+ 27
IX.
0
+ 34
+ •56
o-o
X.
+ 23
+ 4ii
+ •66
+ 15^
XI.
+ 38
+ 49
+ I46i
+ 76
+ •55
+289
XXIV.
+ 5
+ 2-8
XXV.
+ 3
+ 154
+ .44
+ »'3
XXVI.
+ I
+ 1614
+ •32
+ oy
XXVII.
+ 9
+ 169
+ •19
+ 17
XXVIII.
+ 6
+ 1764
+ •09
+ 05
XXIX.
-19
+ 184
-07
+ 1*3
XXXII.
- 8
+ 206i
-•45
+ 3-6
XXXIII.
-27
+214
-•56
+ 151
XXXIV.
-13
+ 22IJ
-•66
+ S-6
XXXV.
-29
+ 229
-76
+ 22-0
Sum
118-9
28. The first column gives the sequence of periods observed by
Bazendell. There is a wide gap between XI. and XXIY. with no
observations, and it will be seen from columns 3 and 4 that it was
unfortunately just in this gap that the corrections to epoch would
have been largest, and given us an accurate value. StiU, the
periods when the correction vanishes are fairly woli determined,
which is somel\i\i\^. TVlq^ \^'7^ been assumed to lie midway
June 1908. 0/ Prof, Kwrl Pmrmn's Calculation, etc.
557
between IV, and Y.. and between XXVIIL and XXIX. This is
only a rough assumption, but the material does not warrant refine-
ments. The ** obBerved ci»rrectiou to epoch " given in the seoond
column had breu dinluced from the observations by Mks Bkgg^
using a purely numerical process,* before there was any idea of
applying them in this way. In the next three columns the
product by sin (arg) ia deduced, ami is almost uniformly positive.
Dividing the sum 1183 by 2sin-{arg)j which coraea out 41S, we
get as above mentioned
C=it8'3/4'i8 = i8-3.
S Sei-peiitu (Ch. No, 5501)-
29, For a different reason it h necessary to call attention to
the case of S Serpentis, period 369 days. Chandler gives C= i f6,
A = 4*', while our formulae indituite C^jo, A = 9", But it is
apparently possible to satisfy the obaervations in a ditferent way,
which assigns to C and A nearly the values of the formula. This
investigation is given in a ^parate note following this paper.
30. What are now wanted are better deterrainations of C and
A for stars with long and short periods. Too much depends
on S Gassiopeise {610 days) and U Yirginis (145 days)^ in the
present state of our knowledge of them. "^The dog is wagged by
the tail/' But it is the special value of an investigation of this
kind that attentior^ is directed to special uecda w^hich may guide
observers in selection. The following stars, for instance, seem
worth special attention from the northern observers: —
Short Fcrlodi.
Xame, No
Z Aquilffi 7260
p
127^
Long Periods.
S Caaaiop. 432
P
6io««
W Cygiu
7754
^i*
V Del phi ni
745ii
540
R Vulpec.
R Virginis
7560
4521
137
S Cephei
W Aquilie
7779
6900
4S6
480
S Aquilne
7242
147
V CyKiii
7299
461
V Capric.
T HerculiB
7571
6512
157
165
Z S&giitarii
K Ijeporis
6923
'771
452
436
RC«ti
HS
167
T Driit^o
6449
426
V Tauri
J717
170
R Cygni
7045
426
R Arietift
782
187
R Hydrre
4S26
42s
31* Returning now to Table L, in the seventh column la given
M - Wi the interval between maximum and the preceding minimum
according to Chandler's revision. For most variables thi^ is less
than half the period, so that the quantity
aP-2(M-m)-P
* Th" pruCfHs can readily be inferrrd from the dasoription ou pp. 66 to
68 of Jiem, Jl,A.S,, vol. Iv., though thia description is adapted ta «b
period, i.«. a dttforeuce ofepoohsf inat&od e£ to the «][)Oc\v UMi\t«
558
Prof, H, H, Turner^ An Emmjde LXVIir S,
shown in the last column h negative. The quantity a wait ufied
in M,N,, Ixvii. p. 350, in connection with the clasdification of
these variables according to their light curves, a»d it ia interedtint?
to see whether the type of light curve is Felat<3d to the quant itiei
C and A we have been discuasing. The value of r for C and aP
comes out 'oil, showing that there is complete independence. In
considering the type of light curve it was early noticed that it
seemed to be independent of the period ; and it is not surprising
therefore that C and A, which seem to depend on the perifhi,
should be independent of the type of curve. The relatjon between
A and aP, and those between a alone and C and A, might be
actufilly worked out, but it seems improbable that they will yield
any result of interest.
32. Column 6 of Table I., headed " Phase," represent* a much
more speculative investigation^ but one which it seemed jast
worth undertaking. It seemed quite possible that C and A, or al
any rate A, might be directly proportional to P. The limits of
possible error are such that there is nothing extravagant in this
suppositifm, which would be represented by the equation
rp
where
HO that
k^ 2_ = 1 32,
31 «
A = *oa64p.
We may compare the resulting values of A with those of J 15.
P=ioo'i
200"
500**
400''
5oo«
600*
A by old equation ^ 44 6'2 S'o 9*8 11*6
A by new equation = 2*6 5*2 7*8 10*4 15-0
33. Now what makes this hypothesis of special interest is Iks
fact that the cycle in which the term Csin (A* E-f const.) b
completed is 3 60/ A pericnls or 360P/A days, and if P/A Is constaat
we are confronted with the idea of a universal cycle controlling
all these stars I The notion seems injpo^ible, and yet there might
be a simple explanatirin of it — the cause might be rooted in na,
and not in the stars. It is difficult to see how any feature of the
Earth or of the solar system could affect diiferential comparisoas
of distant stars, but though difficult it may not be impoasihle.
The period indieuted is 36o/*o264 days or 37*4 years. If ther«
IS a phenomenon of thiis kind originating with the observer, it
might have the same phase for all stars, or at le^st the pba«o
might depend on the stars position. Hence the phases given by
Chandler were reduced to the common epoch 240 5000, and ai»
shown in the sixth column of Table L They certainly tend to
no one value more than another, and a few experiments on their
being relsteil to a stars position gave no encourage tueut,
34, AnotV\eT po\tvt ma.'^ \3«k xa5ssi.^\ai\«d* Whether there is
June 1908. 0/ Pfof. Karl Pearson's Calmlaiwn, aic.
5S9
actuallj a single periodicity or not, the cycle for the poricKlic term
la about of the name ortler for different stars. The value of
360P/A in yearii given by the e<|uatii>n of g 15 is
P=ioo'' 200^ 300'' 400*^ 500** 600*1
Cycle = 22?^ 32^ 37^ 40^ 43^^ 46'
Now if its coefficient also remains of the same order of uia^'nituiJe,
ihe maximum ijradient of thedi^tnrhiri;^ cause (whatever it may he)
may he nearly constant, Sujipose it constant for simplicity. Then
the displacement of maximum of a variable is due to the addition
to the term
f/l —/ COS 2ff//P
(which represents the ordinary variation near maximum) of a
term
where A- may be nearly the mm& for all &tar». The time of
maximum will now be when
Zirt
p +Ar,
oTi since t is small,
t=*
kr^
4^^/
Ktiw / represents the ranfje of variation, and is not very different
for the stars in Tahle L, being nsually about 5 magnitudes. For
some 8tar8 the range m as low as 3, and for others it m as ^reat as
7 ; and in a complete iiivestigation the influence of thia rang^ must
undoubtedly be considered. But for the present we will consider
/ constant. It follows that C, which is the maximum alteratioti
of epoch, would be proportioTial U* P" rather than to P. Hence it
is worth inquiring whether thw correlation of ^C with P la b*?tter
than that of C w^ith P. On working it out, the result came
r = o*34, which is indeed greater than the r = 0'30 previously
found, but not much. It would seem that for the present our
best work can be done in getting improved values of C and A for
individual stars, especially those above given, both by making
new otiservations and by collecting and carefully discussing those
already made.
SUJ^mARY.
^ I- 3. Inti-oductory.
^ 4^ 5, Tabulation of Chandler's periodic "inequalities.''
^6-17, An example of working out the *^ correlation " r
between two quantities A and P, The result found is r=o'56
io*o8, which is worth serious attention* The inference is that
the argument A" in Chandlers periodic inequalities can be deduced
from the periotl P days hy the following probable formula : —
I A=8''*2 + ^oi8P,
I § [3 includes a table (IIT.) for the probable etiot olr
560
Prof. H, ff. Turner,
IXfUkit
§ 1 8* For C (the coefficient of the periodic iiieqaalitiea) and
P we find r = 0*30 ±0*10, which ib uot no concluwve. Ther^tiaa
wotdd be
C-7'3+o64P.
§§ 19-29. Examination of S starn in detail^ for which special m*
formation was available. The result is favourable, Kemarlu OB
S Serpentis, which seems to be exceptional.
§ 50, List of stars Deeding special attentiou.
§31. The type of light curve seems to be indep^tdiuil of
Cand A.
§§ 3x-34« PoBsibititj of a single periodic cause affeciifig aQ
stars considered, but not supported.
Note on the Period of S Serpentiif. By H. H. Turner, D.Sc.,
RRS,, Savilian Professor.
1. The fornmta given for the maxima of S Serpeuus (No. 5501)
by Chandler in his lie vision of the 3rd Catalogue (A^J.^ ^€k 553) »
2388724 + 368-5 E-h 116 sin (4* K'f6z*).
The periodic term in this furmula atii-acted attention by co1lside^
able divergence from the value suggested by the preceding papr*
The coefficient 1 1 6 days is much too large, and the argument 4" K
is too small. With a view to seeing whether it was we]} esloHlished,
or whether perhaps some other formula would fit the ohscrvtt** '^^
inquiry was made of Professur Muller, of Fotsdauj, who very ►
sent a complete list of observed maxima, with full refereoceA,
adding a comparison with Chandler's furmula, tha remark that il
did liot fit more recent olksorvaticmii, and a suggestion of his own
for improving it, which modified both the coeflScient it6 aitd ibc
argument 4' E iu the ri^'ht direct it >n. But this suggest iem does
not fit the observation of Lulande, and reasons will be given below
why it is probably tt>o early to suggest a completely satisfactocj
formula, in »pite of the fact that Lalande's observation was madi
in 1794. Hence it seems uuuece9.4ary to reproduce here the full
details, which will doubtless appear in the ^♦reat work of referencf
for variable stars now being prepared by the German Committee
of which Dr, Muller is a member.
2. For our present |)ur|x»se the observations are su&cienUy
represented by the dates for every fifth maximum shown in ths
second colunHi of Table L The numeration in the first ccdumn is
that of Chandler. In the third column are given the intervals, and
we have to decide how U> interpret Lalaude's observation, which
may belong to any one of the epochs - 35, - 34, or - 33, Chandler
takes - 33 ; and tliis gives an average interval of 1876 day» for $
periods, extending over 7x5 periods iu all. Thid vras i\inte a
possible intcsi-ptetalVoTv Wox^ \>i<i \v^^W\i observations (represented
June 1908. Note on the Period of S Serpeniit.
S6i
by epoch 76) were made. Up to epock 71 the interval was in-
creasing, and might have gone on doing so. But later observations
have made this interpretation imposidble. The maximum interval
is clearly past at epoch 71. We have only a single entry in the
table to prove this, but the entry stands for 5 well-determined
maxima in which 5 separate observers were concerned : 3 of them
observed epoch 74, 2 of them epoch 75, and epochs 76, 77, 78 were
all observed. The mean errors of Chandler's formula are -20,
— 3 If - 27} -449 - 43 days ; and it seems clear that the formula
no longer holds.
Table I.
E.
Max.
Int.
A+36S-1 B.
•080 X
(B-t6)».
0-C,.
- 40 no.
aBi*).
O-C2.
-35
2376442
2376018
403
+ 21
-24
- 3
-34
7(1772)
383
392
-33
or 7(1824)
or 7(1876)
748
381
1
2389210
2389161
98
-49
+ 38
-II
6
II
16
—
3(1835)
—
—
—
—
2394714
'
2394638
32
+ 44
-24
+20
1813
21
6527
1807
6463
18
+ 46
-38
+ 8
26
8334
1798
8289
8
+ 37
-38
- I
31
2400132
1802
24OOII4
2
+ 16
-24
- 8
36
1934
1809
1940
0
- 6
0
- 6
41
3743
1818
3765
2
-24
+ 24
0
46
5561
1834
5591
8
-38
+ 38
0
51
7395
1853
7416
18
-39
+ 38
- I
56
9248
1874
9242
32
-26
+ 24
- 2
61
2411122
i860
24II067
50
+ 5
0
+ 5
66
2982
1873
2S93
72
+ 17
24
- 7
71
4855
1854
47 IS
98
+ 39
-38
+ I
76
6709
6544
128
+ 37
-38
- I
81
(to come)
8369
162
-24
86
( ,. )
2420195
200
0
Note on the Period cf
LXTin, 8,
On the other handi if we alter l^alaiide'H otK^ervation by oih
whole period, we get an average interval of 1824 days for 5 pmcxK
This means that a maximum interval occurs between epoch i utid
i6, where the average valine is 1835 days. But this maximum u
Tuuch Xam than that between epochs 6r and 76, urbere the avetjige
value 18 i86f> days.
3. The conclusion seems to be that we cannot sati&fy tha
observations by a single ineqtiality, however we chooee the Ct^
efficient and argument, if Lalande's observation la to be accepted
Bat this is, after all, no new thing. Chandler ^Wes several casta of
the kind, and otherii may be foiind in the futme. For inatance, he
givee for R Hydrse (No. 4826),
24ii93ro + 425'i5 £-0-36 £*+ 15 sin (7'*5 E-»-2ot*).
If we admit an additional term in E* (which means that the
period is changing steadily), we can fairly satisfy the obser\i»tiotiaL
The approximate value of the coefficient of E^ is indicated by the
fact just quoted, viz, that the average interval near the maximum 1%
epoch 9 is 1835 days (average period 367 days), while that at
epoch 6g is 1869 days (average period 374 days). Thus the
period changes 7 days in 60 periods, or the coefheient of E' IJ
about •06.
4. But anyone who haa had experience of such work knows
that such rough approiiiiiationK are ft^Howed by a series of
and errors '* ; and by experiment a better value for the cck t
was found to be '080, as indicated in the lifth column of Tnbie L
The accompanying value of the period (for £ = 36) is 365*1 day^;
and starting with an arbitrary epoch, this is represent^ in the
fourth column.
5* The values of O — C are shown in the sixth column, fhicn
which it is seen that an inequality of much shorter period ilmn
Cbmndler's will stiti^fy them approximately if Lalande s obscrvaiian
be referred, not to E= - 33 or even E= -34, but to E- - 35.
The numerical values assumed are
+ 40 sin (f'l E-f-aSr),
which are in much better agreement with the values assigned 1)J
the carrelation fonnulso of the preceding paper, viz.
+ 30 sin (9**0 E + ?).
than Chandler's expression,
116 sin (4** E-f 62*),
1
6, The final residuals are shown in the cohimn O — C^ We
must wait for confirtnation of the considerable assumption alreid)^
made ; atid to this end the maxima ensuing in the next few years
are predicted as—
June 1908.
On the Orbitof^ 416.
563
J.O.
79
241 7817
= 1907 Auk. 39
80
241 8186
1 90S Sept 1
81
34« 85SS
1909 Sept. S
Bt
^i S923
1910 Sept 8
H
241 9291
1911 SepL 11
«4
241 9659
1912 8t*pt. 13
8S
242 0027
i9i3St'pt 16
86
242 0395
1914 Si^pl. 19
7. The complete fot muU is thus—
2388796 -f 365-1 £4-^080 (E -36)- +4oaiu (7'*2E + 28i*)
= 2388900 + 359*3 E4-*o8o E2 + 40 nu lf'2 E + 2S1");
but the term '080 E^ is of a provisional character, and piohably
represents the present value of a terni of long perioiJ.
8, The main interest of thi=i inquiry is the result that even in
snch an exceptional ease as that of 8 Snrpentis it is found ptissible
to obtain fair aceordance with th« suggested formula by a simple
suppossition of a kind already familiar in other ca^ea ; while it
seems certain thai the discrepant fornstila is not correct. Poaaihly
in other cases of discordance similar f^xpla nations may he found*
On the Orbit 0/ ^ 416. By J, Voftte.
The periods calculated for this interesting binary differ
very muck The last, that of Doberck, with a period of forty-
six years, was based on the nieasuri^s up to 1903, and his
ephemeris gives, with the recent observations, nearly constant
negative differences. In the presf?nt instancy th« measures pub-
lished up to 1906 have been used. In the first place, all the posi-
tion-an-L,des and distances are brought up to the epoch 1910*0;
then 6 normal-places are formed with position-angles and dis-
tances. These normal-places are formed out of the groups marked
by square brackets. First a noimal-place is formed foi- evary year
with weights equal to the number of nights observed by the
different observers, and then the normal-place of a group with
weights equal to the number of years.
Normal
'placm.
1877*23
228*77
179
1898*14
305*37
i-85
t&S9fi9
129- I 9
098
1901 77
291 35
2-n
1895-80
322*14
''34
1905-60
2^-d&
^'2v
564
On the Orbit of 13 4i6.
'Lxyin.8,
The apparent orbit drawn throngh these normal-places gifei^
following the graphical niathod of Dr. Zwiers, the following
elements : —
P= 41*47 yean a= i"'86
T= 1891-45 a=i3x*-o
n= -8*682 1= 49** -o
e= 0*552 0= 64* -o
Motion retrograde.
Comparison of computed with oheerved pfacee.
Bumham
"1876*52
±239 ± 5-8
±0*05
Aitken
1900*49
295-5
-0*9
Cinciunati
77-53
222-4 - 59
0*00
Tebbutt
190042
298-9
+2-5
Ruasell
_ 77-64
2242 - 4*0
-0*03
Lunt
1900*53
298-9
+ 2*6
Burnbani
88*72
147-4 + 6*4
+0*69
DooliUle
190060
2941
-i'9
>»
"89-42
134-0 + 37
+ 0*12
Doberck
190176
291-3
-0-4
Pollock
89-63
131*8 + 1-8
-0*08
Innea | 1902-36
292*0
+ 2-4
Sellare
90*60
121-9 +12-8
+ 0*01
Aitken 1902-44
288-8
-0-5
Bumhani
91 -53
81-2 + 4*5
-0-05
Tebbutt ■■ 1902-49
289*9
-rO-S
,,
9^-3«
24-3 10*3
+ 0*05
Aitken 1903*56
286-1
+0*5
Scllars
93*55
348-2 - 6-9
-0-06
Doolittle 1903-62
2^yi
- \'\
Barnard
9456
334 '4 - I -I
+ 0*25
Srott ' 1903*66
287-1
r-1-9
Sellars
94*57
3317 - 37
--0-II
Aitken
"1904-63
2S2-S
-r ri
Comstock
9560
321-6 - o'9
-0-45
>>
1905-63
280*1
-r:
Sellars
9562
322-1 - 0-3
4-0-07
Tebbutt
1905*62
2793
-02
See
<)5*74
321-3 + o-i
-o*o8
Doberck
1905-66
281-5
+ 2-5
Aitkon
9044
3U7 - 1-6
-0-07
Aitken
1906-46
276*9
+0-5
Scott
90-46
315*3 09
+ 0*09
Tebbutt 1907-57
2742
^07
Sellars
96-59
315-7 + 0-4
+ 0-33
Scott 1907*56
2730
-05
Comstock
96*00
314-8 0-5
-0-25
See
97 39
306-9 - 3-2
-o-oi
Aitkeu
97 '46
309-0 0-7
+ 0*29
Scott
97*47
308-7 - 0-9
+ 0*09
Lehman
97 5^
310-1 i 08
+0-13
Aitken
9^^-35
99 \v^
3037 1*5
300-1 - 0-5
-fo-14
-0-12
Dooliltle
99*42
299-0 - 1-5
-o*i8
•,.-c.
Tiie tiii)l«» shows us that the differences ft>_,,, though small,
show some \k'Uvh\, W\ ;\ eo^x^cUou of the elements does not
June 1908. Orbital EUmenU of Double Stars, 565
improve them. Better material for correction may be obtained in
the next few years.
JEph/Bmsris,
1908-$ 270*3 a-2o 1912*5 256*4 a'oS
1909-5 267*0 2-i8 1913*5 252*6 2*04
1910-5 2636 2-15 1914*5 248-6 2-0O
1911-5 260-1 2-12 1915*5 244-4 »*96
Orbited Elements of Double Stars, By T. J. J. See, Ph.D.
The following orbits have been communicated by Dr. See»
The material on which they are based is for the most part to be
found .in Bumham's General Catalogue,
5 2.
R.A. o»»4°* Dec. +79** 10'
Discovered by W. Struve in 1828. Always a close pair, and
measures are therefore difficult with small or moderate a]:)erture8.
An orbit was found by Qlasenapp using measures to 1893. It
was again measured by Biesbroeck in 1904.
P = i66'o years Q = 168*3
T = 1894-50 I = 72 3
e = 0-40 \ = 0-0
n ss 0*65
)3 524 = 20 Persei.
R.A. 2^ 47°» Dec. + 37* 55'
The principal component of the wide pair 5 318. It was
discovered by Bumham in 1878 and is always difficult. It is
assumed that Bumham's angle in 1878 should be altered by 180*.
All the observations are represented except the distance o'''22 by
Lewis in 1896. It is not probable that the orbit given is more
than a good approximation.
P = 36 years Q indeterminate
T = 1897-0 I = o'o
e = 0*75 \ = 149*6 =Peria8tron
a s 0*16
566
Dr. T. J. J. See,
2483-
lxvulSi
Bee. +39' 14'
B.A. 3>» 57»
Discovered by W. Struve in 183a There are in all 20
measures down to 1904, and in 1906 it appeared single to BomhaH
in the 40-inch. Early observations are important as soon 11
separation occurs.
P = lassytm
T = 190775
f = 0786
a = 177
a = 23-1
< = 68-0
A = 213-4
B.A. 4** 46"
i8 883.
Dec +10" 54
Discovered by Burnham in 1879. A long series of measoRs
is available, and Professor Aitken has communicated those of
1907 and 1908.
P = 16*6 years
T = 1907-33
c = 0-47
a = 0*24
« = 335
« = 357
A = 197-3
RA. 8*» o'"
^3581 AB.
Dec. +12* 35'
The close pair of a triple system discovered by Burnham in
1878. The distance never exceeds o"-5, and the object is diflScult,
but the measures are numerous and good. A few have heen
rejected. The comes is now passing periastron, and measures,
though ditticult, will be valuable.
P = 41*2 years
T = i909'io
e = 0-53
a = o-6i
a = 1337
i = 631
A = 2781
R.A. 9»' 48"
AC 5 = 8 Sextantis.
Dec. - 7' 38'
Discovered by Alvan Clark in 1852. The angles given by
Dembowski, by the Ciuciunati observers in 1878, and by Hall in
1879 have beeu reversed. There is a systematic run of negative
, June 1908. Orbital Elements of Dmtble Stars, 567
residuals in angle in the second quadrant, but the available material
is not sufficient to justify a modification of the elements.
P = 6875 years Q indeterminate
T = i88a-o I = o*-o
e s: o'6o X = 240*6= Per iastron
a = 0-35
23123.
Dec, +69' 15'.
Discovered by W. Struve in 1831. The early measures are
few and not very accordant. The early angles have been altered
by 180*, as suggested by Lewis. With this proviso an arc of 300*
has been described since Struve's measures.
P = 103-3 years
Q
=
56-9
T - 1860-50
1
=
497
e = 0-49
X
=
79-1
a = 0-32
f Bootis - 2 1888.
R.A. 14*^47™ Dec. + 19* 31'
Discovered by Herschel in 1 780 and followed regularly. No
orbit given as yet represents all the observations. The measures
are given in Lewis' Memoir and in Burnham's General Catalogue,
P = 143-0 years
a
=
171-6
T = 1909-36
I
-
45-8
e = 0-546
X
=
34*1
5-02
Dembowski 15.
RA. i6*»;4i™ Dec. +43' 40'
Discovered by Dembowski in 1869. The measures are good,
and distributed over an arc of 192'.
P = 960 years Q = 1457
T = 1898-0 t = 66-05
c = 0-35 X = 16S-3
a = o-5>4
568
Mr. Walter Heath, The Badius of LXYlnS,
S 2438.
R A. 18^56™ Dea+58"s'
Discovered by Herschel in 178a, and re-examined ihe next
year. Re-measured by Sir John Herschel in 1830, and afterwaids
followed by several observers. As periastron was passed abcmt
25 years ago, it will be many years before the present elements can
be improved. The eccentricity is higher than that of any other
known double star except 2 2525.
P = 23.1*0 years Q indeterminate
233-0 yean
T = 1882*50
e = o'9i6
a = <?53
e
I = o*o
X =: 178*3 = Periastron
Secchi 2 :- 2 2481 BC.
R.A. ig^S^ Dec. +38** 36'
The companion of 2 2481, found tu be a close double by Seochi
in 1858. Measured by Otto Struve in 1866, and by Schiaparelli io
1876 ; there are no measures between 1881 and 1897, since which
time it has been followed by Aitken. Aitken's angles before
1 90 1 are altered by 180'.
P - 1 6 'o years
T = 190225
€ = 0-68
a = 039
a = 1097
» = 63-5
A = 2l8'3
7V/e Radius of the Moon for libratton - 4'*'5. By Walter Heath.
Di. L. Struve, in liis reduction of the occultations observtHl
during the lunar eclipses of 1884 and 1888 (Dorpat Observatory
Puhl icdtiom^ vol. xx.), made a table of tlie values of the radius of
the Moon's limb at different position-angles; a similar table was
publislied by me last year {A»t. Nach., 4206), including more
observations, the geocentric libration in longitude being within the
limits - 3''-3 and - 5''-3.
I have drawn the diagrams below in order to compare the
figures in tliis table with the results obtained by Dr. Hayn from
his micrometer measurements at the Leipzig Observatory {Selena-
graphisclie Kooi'iiinafen^ III Abhandlung, Leipzig, 1907). In tlie
dia^rrams the figures at the side are for measuring the radius,
and those at the bottom denote position-angles ; the dotted
line shows the values taken from Dr. Hayn's table, and the other
line indicates th(; occultation results. The zero from which the
occultation radius is measured is the Moon's centre as determined
June 1908. the Moon for Uhraiixm —4 "5.
569
^^
S70 The Radius of the Moon for Itbration — 4**'S. ucvin. 8,
June 1908.
The Lunar Bright Mays.
S7I
by Dr. Struve from the occultationa of 1884; and in order to
compare the curves, I Imve supposed this point to be the zero for
Dr. Hayn's measurements, and that the ** mean level ^' which he
adopts as a standard is at 15' 3 2""5 in the diagram*
The occultation curve is compounded of the curves representing
the groups of results for 1884 and 1S88 and some smaller groups.
If the declination of the Moonl'=i centre in respect of any group
is corrected, the curve for that group will be turned about the
east or west point of the limb; the east and west jjointa for the
eclipse of 1884 are at position-angles 114' and 294*, and those for
the eclipse of 1888 are at 73" and 253',
t/plands, Cohkuiiij Surrty :
1 90S June 7.
The Lunar Briglit Rays, By H. G. Tomkins.
It is with some hesitation that 1 venture to add to the numerous
theories which have at one time or another been put forward
regarding the lunar bright rays, and my excuse must be the close
analogy which exists between them and certiiiu terrestrial phenomena,
and the eiise with which it can be applied to the Moon.
The present explanation is base<i, firstly, on the assumption that
the configuration of the ray systems may be due to a cause separate
from tlieir albedo ; secondly, that similar confi^ju rations appear to
exist on the Earth; and thirdl), that a terrestrial analogy to the white
material of the rays is also available.
Taking the albedo tirst, I am hA to think that this can be
explained on the supposition that the white material consists of the
soluble saltsof sodium and other minerals contained in the lunar crust.
In the case of the Earth, these salts are brought to the surface by
evaporation in a great many parts of the globe. The salts originally
exist below the surface, either in the shape of lieds of solid salt or
salt -imprejjna ted atrata ; and when they come into contact with the
subsoil water, they riae to the surface in solution, and, on the drying
up of the water, are left as a white efflorescence. In arid parts such
as are found in North fndia and Ff^raia, the etllorescences are v^ery
abundant, and a map of the tracts in the countries named exhibits u
distinct tendency towards a radial formation, one of the strips ex-
tending about 800 miles towards Bengal from the Salt Rtinge, In
Grermany also, though, owing to a tempemte climate, etflorescences do
not occur on a large scale, the brine s[irings, indicating the presence
cif Ibe salts, have a distinctly radial canKguration- In these cases the
white material and the radial formations appear to occur together,
Thia, however, need not always happen, and, as a matter of fact,
in many countries the eiHorescencea do not seem Ui show any radial
tendency, and, on the other band, radial confi^mrations sometimes
appear without e6^orescences. This is easily explained when the
572
Mr, ff, G. Tomkim,
Lxvia 8s
r
oiigin of the radial configurationa on the Ekrth is cottaidered. Tbejf
are referred to by several geologists of note^ and in particaiar by
Judd in his work on vulcanoes, in which he qnotes the cafio of ihfl
Lipari Islands, and states that a similar arrangement can he tracijd
in many volcanic regions, especially those in which a great central
volcano has existed. They are due to intrusion of liquid mitler
from l>elow, which, by puBhing up a centre of volcanic activity,
causes the formation of radial tiasures, and upheaval* of strata round
it They are not always visible, however, on the surface*
Consequently, if such a system of upheavals occurred in ihe
neighbourhood of saline deposits, the saline strata would be pu&bed
upwards along with other strata^ and this would bring them wilUui
the reach of evai:K)ration at those places, and re^sult In ef!lore*ceBc«»
on the surface which would follow the direction of the uphe»valir
and a radial formation would thus occur. Judd also mentions tbt
presence of saline springs in some cases.
On the Moon, all the conditions of such a state of affaira exiii
Careful observation very quickly shows that the ray sj^tems dHht
greatly in ctjn figuration from one another^in fact, their promiiuot
centnd formations and their albedo are about the pnly real poiats of
resembltuice, aod this leads to the conclusion that their albedo xoMf
differ in origin from their configuration. As regards the latter^ thf
central formation, the radial configuration of the streament, th»
complex forms round Coperaicus, and the differences of the systesoi
between themselves, all point to an origin similar to that of volcanic
centres on the Earth. Experiments made by Nosmytb and Carpenter
and many others also testify to the probability of radial foruuUioQf
accompanying central npheavals or pressure.
Sir Georire Darwin has demonstrated the probability of theMd^^H
having once been a part of th^ Earth, and it is rea^ioriable, therefon^l^H
assume that it has a similar constitution ; in which case the existeoet
of the salts of sodium and otlier minerals would be ex|^»ertrd nn tb
Moon — more especially sodium, which spectroscopic evi" ri
to be present on the Sun and other heavenly bodies. r^
not exist in its free state on the lunar surface, but it is admitted Ihsi
there is no I'eason why water should nut have existed in ibe tsoU;
and with the lunar climate, there would therefore have been caiiai
for strong evaporation at some time, even if it does not itiU
continue.
Consequently, any aoluMe salts in the lunar crust would come to
the surface in the shape of efHorescences, and, owing to the abkencaof
clouds or rain which might temporarily operate to reverse the proc«»
of evaporation^ as on the Earth, the salts would rise more or I***
continuously, would remain permanently on the surface, and would
follow the configurations of the ground, as already explaineri. If oo
the Earth water and rain were to disappear frfjra the surface, i
similar state of things would inevitably ensue ; and in addition td
the countries now affected, the areas occupied by the ocean wuuld
also have to be taken into account, with the enormous quantities id
salts at present in solution.
June 1908.
The Lunar Bright Rays,
S73
Tht3 only objection of importance to the above explftiuition is the
obaiervi'it late appearaace of Ihe lunar rays at sunrise, and tlieir early
disiippeLirance at sunset, which has been regarded by some as indicat-
ing pliViiical change of the material of the rays. Such change would
not, of course, occur with the salts. The facts, however, that the rays
can easily be (^eeu during a tot^il eclipr^e of the Moon as well as on
the dark pan of the youog Moou, that there are aome excepuons to
the phenomena, and that, if the site of a ray is watched, sunrise can
be seen to extend to it exactly in the same manner as to other
formations, are evidence against any physical change, and indicate
that their invisibility is probably merely dne to the fact that there
is little or nothing except their aibedo to notify their presence to
the eye, and that they are there all the time, and only t^esm
to appejir wlien the illumination is authcient to produce a contrast
between the white material of which they are composed aud the
aurroundin^ country.
I may also aild that experiments made by me on this assumption
entirely agree with Professor W. H, Pickering's observatiiHis that
the app*>arance and disappearance of the rays take place when the
solar altitude is from 5 to 10 degrees.
For purposes of the explanation of the rays, therefore, these
phenomena can be put down to variations of illu mi nation, and
neglected.
CanUrhury :
1908 Jun9 3.
574 Observations of Daniels Comet (d 1907) at lx?iil 8,
a
s
o
'a
o
Soo : St:.ao : dS 00 ep oe K
bo boo
5« r 'P y^ !*"
; 00 GO : t^ t^ t>»
' I I • I I I
QO
o b
0000
r ^ r> .« p P
I I I I I I
:%
\r% \r\ xn
SCO O . w^ rsi 30 r^ ^
ir>\rk«/> \r% urt y\ %ft y%
0^0^0^ O^OiO^^O^
^ -c
c4
00 vO m ro «
Si.« ft
O O
I I
ro « r^ Cv Oi r^ t^
.'*' ."^ . rn « « It «
bob :bbobo
ill I . ' • I
r^ r^ O
yp xn p
V NO ^-
-, tJ- O VO
"*- .'-'
b o
N ^
W
m «
N 0
m
.-• «
0
^ 0
1 +
+
1 1
i^ IT) r^ C^
•^ m : m
« N ' -^ o
+ 1 I +
pn 3C 30 « -^
r* r* • ."^ .
O t^ f^ M^ ""
M m ^O tr> »A
r^ r^ 30 O^ Cv C* 3'
QO xn rr^ rn -^ 'J'N-
P 30 "^ ^ ;?■ C^ f^
u-> rt\ »^ »n ts.
r ? f^ 9 r
\n \r\ m t^ 1^
N CO ^ "^
S3P
g vo o £^ 0
^ fo fo o ►-
CN - r^ >: N -
M ^ ^ -iT
C 1
tc
a
N mt^rnw^^^^f^
_^^ir»iOiOO u^ii^u^u^O
00-
fcC
ro«^30 O OvOxao
. J une 1 908, the Raddiffc Observatory^ Oxford,
575
Observer's Remarks*
{a) (b) The nucleus or condensation of comet (magBitude 8»
and diameter 2* or 5") shows up on the preceding side of Coma, the
radius of which is about i\ For a long time after these observa'
tiona were taken the comet coji tinned to be easily men in strong
I twilight.
(c) Comet conspicuous to the naked eye, magnitude 2, Tail
precedes* 2* or 3* in length. In the 10 inch, the condensation,
though large and diffused, is not brighter than magnitude 6^5,
((I, e, /) To the naked eye the comet is nearly as bright as y
Geminorum, magoitude 2. The tail can be traced to a distance
approximately equal to that of Pollux from Castor, In the lo-inch
the condensation appears large, diffused, and somewhat triangular
in form, with a brightness much below that of the second comparison-
star^ magnitude 7*8 (AM,)^ but superior to that of the first, magni*
tude 9*0.
{ff) Condensation diffused and large, not brighter than the
eomparLson-star, magnitude 8. To the naked eye, tail appeared
7' or 8" long, and nearly reaching to y Geminorum*
(?i, i) Images very disused this morning, A nucleus occasion-
ally shows up, slightly south of the observed centre of condensation,
wliich spreads over many seconds of arc. The tail of the comet
extends to about midway between the nucleus and y Geminorum.
Altitude small; twilight coining on.
(j) Observed through haze in intervals of cloud. The comet's
tail is diiiitinctly visible to the naked eye, notwithstanding low
altitude, haze, moonlight, and twilight.
(k) Altitude of comet only 6".
(k, I) Condensation large and diffused.
{m, n) Comet very low. The ditTused condensation is sHghtly
brighter than the second comparison-star, 7 '2 magnitude, but much
fainter than the first, 6"o magnitude. The comet was juat visible
in the lo-inch at 17^ lo"* G,M,T.
On September 1 9, the comet was seen for a short interval at a
low altitude; magnitude in the lo-inch, 7*5. Observations were
prevented by the rapidly increasing twilight, and by the remoteness
of the only available comparison-star, which preceded the comet
S"™ 30" in liA.
\T
576 Messrs. Cowdl and Crommelin^ - lxyul 8,
Assumed Places of the Camparison'Stars.
lui.
Mean R.A.
1907*0.
Reduction
Mean
N.P.D.
1907-0.
^VL-sr
! Aathori^.
<a)(6)
h m 8
4 15 37'2i
8
+ 0-31
74 17 i6'8
+ 0-8
Kustner, Bonm Verof., No. 4,
P-97.
Berlin, A (-^.(?.) 1973
(c)
6 6 14*32
+ 011
72 36 47
+ 1-8
(rf.«)
6 28 53-94
+ 006
72 42 7-1
+ 1-8
Berlin, A (^.a.) 2231
if)
6 30 27-59
+ 005
72 43 282
+ 1-8
Berlin, A (A,G,) 2253
(9)
7 8 3176
+ 0-02
73 15 38-2
+ 1-8
Berlin, k{A.O,)2joi
W 0)
7 24 876
+ o*oi
73 38 39-6
+ 17
BerUn, A (^.(7.) 2862
U)
8 16 44-43
-005
74 56 81
+ 1-6
Berlin, A {A.G,) 3303
{k)
9 31 2911
-0*02
78 44 12-8
+ 1-2
Leipzig, I (A.G.) 3809
(0
9 33 46-34
-003
7848 2-5
+ I'I
LeipnSf l{A,G.)2;^io
(m)
10 2 5818
0"05
79 32 46-1
+ 1*0
Leiprig,I(^.fl'.)395«(P.M.'i
-o« -0082 and +o"x)38.
in)
9 58 36 74
-0*04
79 39 3*1
+ 1-0
Leipzig, I {A,G,) 3933
In the computation of the peirallaxes the adopted value of the
Sun's mean horizontal parallax is B'^'So, and the geocentric distances
A are taken from the Astronomische Naehrichten, Nos. 4191, 4194,
and 4196.
HaiicUffc Observatory, Oxford :
1908 May 30.
The Orbit of Jupiter's Eighth Satellite, By P. H. Cowell
and A. D. Crommelin.
In this paper tlie time is measured in units of 16 days from
1908 January i2'o Paris mean time. The astronomical unit of
length is used.
Paris mean time lias V)een used because the Connaissanc^ des
Temps j^ives both heliocentric and geocentric longitudes and lati-
tudes of Jupiter referred to the same equinox, the true equinox
of date.
With 16 days as the unit of time,
log mass of Sun = 8*87 943
„ Jupiter = 5 -85 934
It will be seen in the later parts of this paper that the Sun*s
disturbing force varies iluriiig the early part of 1908 between 10
and 6 per cent, of the attiactive force of Jupiter, and is therefore
by no means negligible. ^Moreover, if the att<3mpt were made to
express the co-ordinates of the satellite with the help of Delaunay's
algebraical lunar theory, it would be found that Delaunay's
quantities e, e and m take such large arithmetical values that
Delaunay's series are insufhcient for the purpose. Hence it is
June 1908. 77m> Orbit 0/ JjtpiUr's Eighth SatellUe.
i77
beet to calculate the orbit by qundrnttires^ discarding th& idea
of an ellipse.
Let the jrJvicentTic co-orilinates at time 7i + t referred to three
rectaai^ular directions be
then we have x^j^^ = 2jr„ - .r^_j + 2a^ + 2^<^ + aa^.
Again, given the co-orditiates at any time, tbe accelerations can
be calculated in accordance with Newton's law of gravitation. If
X denote ihe x acceleration at time » + ^,
X = 2aj H- 6a^i + i lajf^ + joaji,^ -k- 30^,^^'*.
Hence
and
'za^
A(^+i-2X^ + X^_i) = 2rt^4*5a^+ .
The left-hand side of this last equation may be described in words
fis one-twelfth of the second ditl'erence of X,,, and it wilt be denoted
for brevity by P,,
Hence we have rf-„+, = ^^ -H {x, - x^^i) 4- X^ + 1\
hjffith one error of yt^^ , which we shall aaaume to he negligible.
^» Now let us assume that ^„_j, ^„_i,*''„ have been caltiulated, and
X„^3, X„_i , X„, and therefore idso I*„_^, ,P„_]. We cannot at
present calculate P„, for thin requires a knowledge of X„^j, and
therefore of d\^^^ » ^v*v+i t^^+i \ ^*^t we may i^mess at the %'alue of F„
with the help of the vahies of P„„2 , P,^,i (or for the first few values of
«, where P^_j has not been calaulated, by trial and error); we then
obtain a provimonal value of ^^^.j (and similarly y,,^., ,^„+,) ; hence
wo calculate X„^i, and so obtain a revised vahie of P„ ; the correc-
tion AP„ is then added to r^^^^ and in practice it is found that
X^+j 1 Yrt^i, Z^^j are unaffected.
We give a numerical application of the above method, taken
from our calculations of a provisional orbit. In the illustration
it is assumed that the orbit lias already been calculated as far as
^=5 (AfiHl 1); it is required to extend it to ^ = 6 (April 17).
For the sake of clearnes^s^ qtiaiitities already calculated are written
without brack eta, q nan ti ties guessed at are written in round
brackets, and fresh quantities calculated accurately are enclosed in
i^UAre brjickets.
a%= +•0511 598 1/,,= -•1691 203 2j^= -'0173 0^^
I a*^ — jc^ = - *o 1 60 908 y^-y^^ - '0004 222 i^ - z^ = -h '0055 069
X^— - '0005 159 Y^= -f'ooso 967 z^= +*ooo2 300
(F5) = H- *oooo 027 (Q^) = + 'oooo 015 (R,J = ^ -OOOQ o^o
578
Messrs, Cowell and Crommdin,
LXVIXL S»
Hence by additioD,
•1674 445. (c^)= ' '0075 732,
Hence we calculate X^ » Yg , Z^ , and hence
[Pj] = + '0000 029 , [QJ = + 'ooo 014 , [R5] =^ - '0000 020.
Hence applying tbe Hcnall differenced between the true and
viaionftl values of P.
Qs* ^5*
[^J= + '0345 5^0 » M^ - '^674 444, [2j= - *oo75 7J2.
The foregoing sufficiently explains how to calculate the motaos
from assumed initial positions; we now deal with the problem how
to find an approximate orbit from the obijervations,
Ketatning the previous notation^ and interpolating a little among
the observaliotis, we shall assume as known the geocentric angukr
positions at three equidistant times n - t , n , and »-»- t.
Keaisoiiing exactly as before we have
x^^y. - 2x^ + x^^y ^ X^T* with an error of ^a^-r^.
If we t^ike the x direction at right an glen to the geocentric
directions of the sate] lit© at times n - t and « 4- t , then our ignoraiice
of the geocentric distances at th«so times produces no uncert*ifttf
in the numerical valuer of x^^j and j*^^^ ; we therefore h»ve o0w
unknown quantity only occurring, viz, the geocentric distance at
time n ; and the above equation, by trial and error, will detemsine
this quantity*
I'he corresponding equations for ;/ and 2 then determine tit
geocentric distances on the first and third occaaions.
We may then revise our solution so as to correct for tb«
residuals 20^ t'*, etc.
In practice it is iLot necessary to take the ^ axis at right aogke
to tbe first and third geocentric distances ; we shall then liw
to deal with three simultaneous equations for three unknown
geocentric distances. The idea of resolution perpendicular to the
outer geocentric distances is perhaps useful for forming a distinct
mental conception of tti© process.
We shall ni>t go into numerical details in connection with the
method just sketched. It may be anticipated, However, that tbfl
solution is a dual one, or that two orbits which may be diatingmshad
as direct ami retrograde can be found to satisfy three obeervatioftik
It unexpectedly turned out that the jovicentric distance on Fehroaty
28 was less on the supposition of a direct orbit than for a retrognwi*
orbit ; but a very large eccentricity resulted from the former brpo-
thesis. For this reason combined with the reasons stated in M.N.,
Ixviii. p. 457, the retrograde solution was chosen as the one to Iw
worked up. It will be seen that the corresponding orbit elosdj
follows the observations. Now the dual solution implies that thire
are two distinct ways of making the coefficients of the squaratof
the time agree with observation. Of these two solutions tht retro*
Igrtde abbllVviu xsmV^^ tW coefhcieuts of the third and fonrti
Jnne 190S. The Orhii of Jupiter's Eighth SatdlUe,
579
powers of the time alao agree with observation. Of course it
is not inconceivable that the direct j^ohilion init^lit also give cube
and fourth terms agreeing with observation, bat it is a jyrian
distinctly improbable. Wo have not, therefore, exjimined the direct
aolutiou (or the question of a possible phtnetarj aohition) with any
minuteness. However closely a direct solution was found to fit
the observations, it would be impossiVde at the present moment to
reject the jjo^ssibility that tlic retrograde solution was the rij^dit oiie.
The following table contains full details of our provisional orbits
The axes are drawn as ftdlows : — x towanis the first |K)int of Aries
for i9oS"o, f/ towards longitude 90", :: towards the pole of the ecliptic
-rf ^ a are the jovicentric co-ordinates of the satellite,
r:yz* „ „ „ Sun
X| Yi Zj are the accelerations of Jupiter od the satellite
X3Y2Z2 „ „ the Sua
^3 * « -^s
the 8 nil on Jupiter reversed
X Y Z are the sums of the three precedin:^ ijuantities.
P Q R are the twelfth parts i>f the second dilTeretices of X Y Z,
The values of I\ Q, li for April 1 7 are enclosed in brackets to
indicate that their values have been inferred, and not calculated :
the values of jf, j^, ,:; for May 3 are enclosed in brackets to indicate
that they depend upon the preceding values of 1*, Q^ R*
Tabis exhibitiufj Deiaih of CcUculcdion of provisioned Orbit of J. VIIT,
Fob. 39U Mw, 1 6.
f -0827044 4- '0672506
- '1664110 - '16S6981
- "0359985 - '0268150
f 3^882 +3-5797
-4-0065 -3'93iS
- 0*0635 " 0*0658
' *ooo882i - -0007863
+ ■1113290
- -1570880
- -0531070
-^ 3*2999
--4*149^
- 0*0587
- -ooioio;
+ '0014262
+ -0004821
+ -001 8109
- -0022675
-•0000032
-•0016771
+ '0021090
+ '0000298
- *DOo8769
+ ^0012677
+ x>0O5o87
Feb, rj.
+ -0974232
- -1624748
' -0447S27
■*- 3*3949
- 40791
-0*0611
- *ooo9553
+ -0015931
+ •0004391
+ '0018614
- -0022109
- '0000092
- -0017204
+ -0020670
+ •0000310
^ 0008 1 43
+ -0014492
+ •0004609
+ •0000013
+ 0000014
' -oooooio
-0017749
-0003839
'00 I 9080
0021515
'0000154
-00 J 7625
•0020243
•0000321
•0007366
-0016477
-0004006
•0000016
-0000014
-0000013
+ -0019724
+ -0003135
-f 0019507
- '020S99
- -0000217
- -0018036
+ 0019809
-h 0000332
- -0006392
+ •0018634
+ X)O03250
+ -0000022
+ •0000015
- -0000016
A.pr. I.
+ •0511598
- -1691203
- -01730SI
+3-6694
-3-855'
-o-o68r
- '0006613
+ -0021861
+ ^0002237
+ -0019889
- -0020262
- -0000279
-•0018435
- '0019368
+ -0000342
- '0005159
+ -0020967
+ -0002300
+ •0000029
+ •0000014
Apr, 17-
+ -0345560
- •J674444
- ^0075732
+ 3*7572
- 37764
+ 0-0704
- '0004987
+0024163
+ -0001093
+ -0020229
- '001961 1
- •0000341
- -0018823
+ •0018920
+ 0000353
- -0003581
+ "0023472
+ "oooi 105
(+ -0000036)
( + -0000014)
May 3.
( + •0175977
(--1634199
( + -002269^
+ 3^8433
-369^
^ 0-0727
58o
Messrs. Cowdl and Crommelin,
LXVIIL8,
From the co-ordinates x, y, zot the preceding table, the tabalar
differences of geocentric right ascension and declination between
the satellite and Jupiter were obtained. We exhibit also the
interpolation for every fourth day.
Table for Paris Mean Noorij giving excess of Satellite's iabtdar
R.A. and Decl. over that of Jupiter.
Date.
1908.
Jan. 28
R.A.
8
-729
Decl.
-25887
Date.
Mar. 20
R.A.
+ II27I
DecL
-1419^
Feb. I
+ i'i9
2511-9
24
122-83
1332-4
5
972
2430*4
28
132-99
1247*7
9
1834
2345*0
Apr.
I
'43*15
11657
13
27-07
2256-4
5
15327
10867
17
3596
2165-3
9
163-32
10107
21
45 -oi
2072-2
13
173-25
937-8
25
54-22
1977-8
17
183-02
868-0
29
63-60
1883-0
21
192 60
801-4
Mar. 4
73-15
17883
25
201 -95
737-8
8
82-85
1694-0
29
21 1 03
677-3
12
92-69
1 602 '3
May
3
+ 219-81
-619-7
16
+ 102-65
- 1509-3
The next table gives the dates of the observations reduced to
Paris time with the light times subtracted ; the place of observation,
and the observed geocentric distances in R.A. and declination of
the satellite from Jupiter; also the excess of the corresponding
calculated co-ordinates over the observed.
Cotn/Hirisoft of Prorisiohal Orhit with Ohsercation.
Date.
i90vS.
Jan. 27
Feb. I
3
22
23
24
27
28
Mar. 3
8
Hour.
h
I2'2
1 1 -4
lO'O
10-5
8-1
12'0
10-5
I I o
9'3
19*9
(»reeii\vi(;li
Observeii Calciilateti
R.A. minus
J. VllI— 2/. Observed.
S 8
Heidelberg
- 8-29
-h 2-20
6-37
48-38
50-31
53-15
59*94
62-34
71-72
-0*04
000
-0-04
-0-07
+ 0-07
-009
-002
-0*02
-0-03
01»8er>ed .Calculated
Decl
J. viii-y
-2597-3
2501-1
2464-2
203S-I
20157
19892
19197
1S952
1804 6
1674-4
minus
Observed.
-O^
-1*3
-f- I'O
-o'S
- 1*4
- 0-4
-0*4
-07
+ 1-8
-04
^
^
June 1908. Tlie Orbit of Jupiier's £iffhth Satdliie. 581
Comparison 0/ Proviswnaf. Orbit with Observatum — cuntinueiL
Date.
1908.
M&T. 23
Hoar,
h
7*1
.r
Heidelberg
Obacrvod
R,A.
s
121*12
Calculated
mlivns
01j«ervBd,
8
-0^07
Observed
Decl,
i347'r
CaltnjAted
mimut
Obterred,
! '^
8*4
Greenwich
131*35
-0 01
1259-9
-1*4
31
8-8
TJ
Mi'SS
-O'OI
1178-1
-o'4
Apr. I
r6-3
Lick
HS'oo
-013
>»537
^r6
1 3
9 3
Greenwich
149 '33
-0-I4
U20'2
4-2-0
^
9-2
11
201*03
-052
17457
-'7
} ^
16-3
Lick
+ 2130S
'O'SS
- 669-9
+ 2*6
^H It will be noticed tbat tb© accordance is exceedinglj close, cou-
^Hridering that this i^ a first ajipruximation to the orbit, and that
^"tiotliiiiK whatever has bet^ti done in the way of modifying the orl»it
tu produce a better uccor^lunce.
It remnins to modify the orbit, and then to carry it forward to
the end of the year, to asniat in picking up th« satellite at the next
opposition of Jupiter,
For general interest, from the first three lines of the firat table
of thie pa[jer tlie folbiwing jovicentric lougitudeB, latitudes, and
distanced are computed, also L th«; longitude in the orbit reckoned
from the ascending node on the ecliptic.
1908.
J&n. 28
30532
Lai.
' 'S'4i
L.
328-42
Dtstauct
•1997
Feb, 13
300-95
'I3 3»
333-iH
•1946
29
296 '43
- 10-96
338-17
•1893
Mar. 16
291-74
- 8*40
343 '45
•1S36
Apr. I
287*83
- 5*59
349-09
•1775
17
281 "66
- 2-54
355*09
■I7n
May 3
276' rs
+ 079
i'53
•1644
The inHtantaneous orbit is inclined 3i'*'i4 to the ecliptic, and
29° "84 to Jupiter's orbit, and the in&tojitaneous eccentricity has a
value alwut | ; the mean distance is about 0*1702, and the period
about two years and two months.
The longitude of ascending node is 27 7" '46,
582 Observations of Jupiter's Sixth, Seventh^ and urnn. 8,
ObMervaiions of Jupiier^s Sixih, Sevenihf and Eighth SateUites from
photographs taken with the yyinch Reflector at the Boyd
Observatory, Greenwich, in 1907-8.
(OommunieaUd hy the Atinmam/BT Bayal»)
The sixth, sevonth, and eighth satellites of Jupiter have heeD
under observation during,the recent opposition of Jupiter with the
30-inch reflector, photographs having been obtained whenever
possible. In all 38 photographs of Satellite VI, 21 photographs of
Satellite VII, and 13 photographs of Satellite VIII have been
secured between 1907 November 13 and 1908 April 24.
The positions of the satellites have been measured on the
photographs taken with the reflector with reference to faint eom-
parison stars (of eleventh or twelfth magnitude), symmetrically
distributed about the satellites. The positions of these faint
comparison stars were then measured relatively to the reference
stars (of eighth to ninth magnitude) on photographs (with two ex-
posures of 20™ or 30>°) taken with the Astrographic x 3-inch refractor.
The field, sensibly free from distortion, being much laiger with
this telesco[)e than with the reflector, from 24 to 39 reference atari
wero available on each plate. As Jupiter moved slowly, it was
possible to make one reference plate serve for several photographs,
which were each referred to it. The constants were determined
in the usual manner, all the stars on the plate given in the
Astronomische Gesellschaft catalogues being used for this purpose.
Right ascensions and declinations of the satellites were then
determined, and compared with tlie corrected tabular places of
Jupiter after applying the corrections
in R.A. 4- o"i 10, and Doc. + o"72
as determined below.
The G.M.T. is the arithmetical mean of the times of beginning
and end of exposure.
Date and fJ.M.T.
1907. d h in
Nov. 13 13 47-8
Exposure.
niin.
60
Satkllite VI.
Apparent K. A. Apparent Dec.
h m B 0 , w
8 59 54-16 +17 27 6*2
J*at. VI-Jnplt<r.
K.A.
in s
- 3 10-90
-i- j; 40-9
n 15
14
57 -9
70
9 0 11-88
17 24 54*3
3 18-89
^ 2 5:-2
Dec. 5
14
157
40
9 0 38*63
17 15 14-9
4 14-48
- 524^
., 5
16
17
140
9 0 38-31
17 IS 157
4 14-52
525-6
„ 10
15
7*3
66
9 0 2-87
17 16 17-9
4 21-25
7 34:
M 13
'3
14 S
13
8 59 34-29
17 17 341
4 23-S9
S 4g-o
.1 14
14
aS-9
120
8 S9 22-64
17 18 7-9
4 2444
9 1:'^
June 1908. Eighth Satellites at Greentmch. 1907-8. 583
Date and O.M.T.
1906. d h m
Jan. 3 13 1 1 -6
„ 9 12 41 9
„ II 13 IO-6
,, II 14 12*8
„ 27 12 41-4
Feb. I II 52*1
I 13 13*6
» 3 10 27*3
» 3 " 284
„ 6 II 35-4
», 12 8 16*8
., 12 9 25-1
„ 22 10 56*6
M 23 8 33-8
„ 24 12 24-9
„ 27 10 59-4
„ 28 10 29
„ 28 II 28-6
,, 29 9 398
Mar. 9 8 404
,. 9 10 13-8
9 10 55-6
„ 19 8 41-9
M 21 9 487
„ 23 8 59-0
n 27 8 54-3
„ 28 9 in
M 31 9 J6-4
Apr. 3 9 517
„ 20 9 21 -o
M 24 9 43'5
Satkllitb VI-
Bxposure. Apparent R.A.
min. * h m s
120 8 53 41*16
16 8 51 20*86
90 8 50 30*68
15 8 59 29*61
65 8 43 24-62
112 8 41 934
15 8 41 7 84
80 8 40 17*18
25 8 40 16*09
30 8 38 56*58
10 8 36 28*09
10 8 36 26*91
100 8 32 40*70
42 8 32 22*58
80 8 31 59-88
70 8 31 5-65
14 8 30 48-92
80 8 30 47*89
50 8 30 32-32
15 8 28 28-12
30 8 28 27*40
9 8 28 27*03
13 8 27 10*46
120 8 27 2 82
120 8 26 58-20
43 8 26 56-53
180 8 26 57-85
165 8 27 5*78
90 8 27 19*81
18 8 30 24*95
100 8 31 32*95
-continued.
Apparent Dec.
17 39 26*7
17 49 11*6
17 52 44*3
17 52 48*9
18 23 58-9
18 34 15-4
18 34 22*5
18 38 17*2
18 38 21*9
18 44 32*9
18 56 20*2
18 56 28*1
19 15 22*3
19 16 57*2
19 18 58*7
19 23 53*5
19 25 27*2
19 25 33*o
19 27 0*4
19 39 48*8
'9 39 54*o
19 39 56-0
19 50 43*5
19 52 29-2
19 54 1*4
19 56 38-1
19 57 12-5
19 58 36*7
19 59 38*9
19 58 4*9
+ 19 55 47*5
Sat. VI— Jupiter.
Dec.
K.A.
ma , „
4 7*05 17 29*6
3 5103 19 369
3 44*50 20 17-8
3 44*35 20 18*6
2 35*64 24 20 -6
2 9-24 25 2*8
2 8*92 25 3-1
I 58*46 25 13*3
I 58*18 25 14*2
I 41*12 25 26*0
I 6*66 25 29*5
I 6*39 25 27*2
o 6*44 24 26*3
-o 1*2 J 24 i6*8
+ 0 5*55 24 2*5
o 22*59 23 24*9
o 28*04 23 10*7
o 28*36 23 9*6
0 33*57 22 56*3
1 21-33 20 8*2
I 21-64 20 6*6
1 22*74 20 6*1
2 6-70 16 3*2
2 14-75 15 6*9
2 22-12 14 II-3
2 35*44 12 i6*o
2 3^*54 II 45 'o
2 46-9^; 10 14*5
2 54*31 - 8 40*7
3 12-34 + o 11*6
+ 3.10-54 + 2 11*3
584 Observations of Jupiter's Sixths Seventh, and umn. 8,
Satellite VII.
Date and O.M.T.
1907. d h ID
Exposure
lUiD.
. Apparent &. A.
h m 8
Apparent Deo.
SMt. Vn-Japit«r.
&.A. Dec.
m •
Dec.
5
16
17
140
9 I 56*44
+ 17 54 467
-2 5639
+34 5*3
i>
10
15
7-3
66
9 I 14*38
17 56 27-6
3 974
3235^
t>
14
14
48-9
120
9 0 28*40
17 58 247
3 18-68
30581J
1908.
Jan.
3
13
11-6
120
8 54 18-91
18 14 29*6
3 2930
17 331
»i
11
13
10-6
90
8 51 3-83
18 22 51-I
3 "-35
+ 9 49*0
il
27
12
41-4
65
8 44 9*55
18 40 54*4
I 5071
- 7 25*1
Feb.
I
II
521
112
8 42 3-27
18 46 46-4
1 15-31
12 31-8
,.
3
10
27*3
80
8 41 14*97
18 49 io'9
I 0-67
14 19'^
,,
3
II
28-4
25
8 41 13*65
18 49 12-2
- 1 o-6i
1423^
»»
22
10
56-6
100
8 34 13*10
19 13 367
+ 1 2596
26 11*9
»i
23
8
33-8
42
8 33 55*86
19 14 497
I 32-08
26243
t>
24
12
24*9
80
8 33 34*27
19 16 22*5
I 39*94
26387
i«
27
10
59'4
70
8 32 41-67
19 20 18*0
I 58-61
27 0-5
it
28
II
28-6
80
8 32 24-20
19 21 37-4
2 4*67
27 5*1
»>
29
9
39-8
50
8 32 8-79
19 22 509
2 10-04
27 57
Mar.
21
9
487
120
8 28 12-66
19 46 39*3
3 24*59
20568
,,
23
8
59*0
120
« 28 3-35
19 48 19-8
3 27*27
19 52-9
>>
27
8
54*3
43
8 27 51-66
19 51 12-5
3 30*57
1741-6
,,
28
9
in
180
8 27 5017
19 51 49*8
3 30-86
17 77
>>
31
9
i6-4
165
8 27 50-10
19 53 30*2
3 3' -30
15 209
Apr,
24
9
435
100
8 31 23-31
Satellite
4-19 53 8-3
yiii.
+ 3 0-90
- 029-4
Dat" »n<)
(J.M
.'1". 1
exposure.
Apiiarent R.A.
Apparent Dec.
Sat. VIII
-.Tupii«r.
R.A.
Dec.
190S.
d
h
111
mil).
h in 8
.
m B
Jau.
27
12
41-4
^5
8 45 51-86
+ 18 5 1-4
- 0 8-40
-43iS'i
Feb.
I
II
52-1
112
8 43 20-67
18 17 36*3
+ 0 2-08
41 41 -s
,,
3
10
27-3
80
8 42 21-90
18 22 25-7
0 6-26
41 4*9
»»
3
II
2S-4
25
8 42 20-52
18 22 347
0 6-26
41 1*3
,,
22
10
56-6
100
S 33 35*41
19 5 49*iJ
0 48-27
33S^-9
M
23
8
33-^
42
8 33 13-98
19 7 37-6
0 50 20
33 3^-4
)>
24
12
24*9
80
8 32 47 37
19 9 51-3
0 53 '04
33 9-9
I)
27
10
59*4
70
8 31 42-89
19 15 i8-i
0 59*83
32 0-4
l>
28
II
28-6
80
8 31 21-76
19 17 67
I 2-23
31 35*9
Mar.
27
8
54 '3
43
8 26 32-33
19 47 53*5
2 11*24
21 0-6
i>
31
9
1 6-4
165
8 26 40-24
19 49 12-3
2 21-44
19 3S-S
Apr.
3
9
517
90
8 26 5472
19 49 38-8
2 29-22
1840-9
»f
24
9
43*5
100
« 31 43*33
+ 19 41 8-9
+ 3 20-92
-liiS-S
June 1908, Eiyhth Satellites at Oreenwich^ 1907-8* 585
Error i of Tabular Place of Jupiter,
The positions of the aatellites ^ven above depend on the
positions of certain stars taken from catalogues of the A at ton o-
mische Geaellschaft, and will be afiected bj the mean error in the
places of theae stars. To eliminate this it is necessary lo determine
the position of Jupiter referred to the same stars.
For this [lurpose a number of photographs of Jupiter were
taken with the 26-inch refractor, using the occulting shutter. By
this means good measurable images of Jupiter were obtamed^
together with aafficieiitly exposed images of the reference stara.
The field of the 26-inch on a 16 cm. plate is one square degree,
and six comparison stars in this area were measured together with
Jupiter. The adopted pUces of these six sUrs were deduced from
measures made on the Astrographic reference plates, the constants
of the reference plates being, as mentioned above, derived from all
the available stars in the Astronomische Gesellscbaft catalogues.
The places of the six stars, and therefore the deduced place of
Jupiter, will be affected by the mean systematic error of all the
catalogue stars on the reference plates, and will thus be comparable
with the deduced places of the aatellitca,
Four photographs were selected for measurement. From two
to four images of Jupiter and of each of the stars were measured
on each plate in the Astrographic micrometer, and the following are
the results obtained : —
ErroTi of R.A, Tabular Place of Jupiter,
Tab.— Ob«,
R.A.
Dec.
Jan. 27
9
• --10
-0-6
Feb. 10
-H
-P'8
,, iS
- 12
-0*6
May 6
-08
-o'9
Mean -^iio -072
Corrections for these mean errors have been applied to the
tabular places of Jupiter, as already stated.
M&yal 0b8srvatf>ryt Grc£ntt?(eh :
1908 Jtiiiis 10.
586 Observations of the Satellite of Neptune, from lzyiil 8,
Observations of the Satellite of Neptune, from photographs taken
at the Royal Observatory, Greenwich^ between 1907 Deoemher
10 and 1908 March 19.
{ChmmvaUeaied by the Astronomer BoyaL)
The following measures of position -angle and distance of
Neptune's satellite were made from photographs taken with the
26-inch refractor of the Thompson equatorial The occolting shutter
was used as in previous years. The photographs were taken hj
Messrs. Davidson, Edney, or Melotte, and were meaaored in a
position-micrometer in direct and reversed positions by Messrs.
Davidson and Melotte. The tabular positions with which com-
parison is made were computed from data given in the Connaissanee
dee Temps, based on Dr. Hermann Struve's elements, the eccen-
tricity of the orbit being neglected. A discussion of these residuals
gives the following differences from Dr. Hermann Struve's elements
in the sense Tabular — Observed :
du^ -o°'69, c?N= -o''*54, (/!=« +o''ii, da^ -i-o"'244
giving for the epoch 1908 '2
a=i6"-027, N= IBS'* -38, I=ii6'-»4
Neptune and Satellite,
Position-angle arul Distance from photographs taken with
the 26'inch Refractor,
Position-angle. Distance.
Date and C
1907. d h
Dec. 10 13
.M.T.
ni
47
s
48
Obs.
24r-68
Tab.
243-09
T— 0.
+ I-4I
Obs.
it
13-82
Tab.
14-00
T-0.
-ho'iS
14
12
49
34
341 -21
339-80
-1-41
12-04
11*93
-0*11
1908.
Jan.
14
3
13
II
15
35
59
i8(n^)
338-86
217-90
338-36
215-22
-050
(-2-68)
11-88
ii-i6
1 2 '02
11-86
-rO-I4
(+070)
4
II
13
^^m
132-17
13464
4-2-47
13*35
13-97
+0-62
4
II
39
10
133-26
133-58
-fO'32
13-75
14-09
+0-34
9
II
5«
II
202 -98
203-38
+0-40
10-87
11-37
+0-50
II
II
27
45
82-99
83-75
+0-76
16-36
16-28
-o'oS
II
11
53
29
82-24
82-99
■fo-75
16-30
l6-22
-ooS
27
9
49
5
179-03
178-08
-0-95
10-70
II -20
+0-50
27
10
13
39
175-19
176-50
+ 1-31
11-34
11*23
-0*11
Feb.
3
9
15
21(0
io8-i8
108*29
4-0-II
16*25
16-42
+ o'i7
6
10
2
5('0
285-08
284-32
-0-76
16-23
16-62
+039
6
10
35
5^(0
282 -40
283-37
+ 0-97
16*29
1667
■fo-jS
10
10
0
?>^^c^
SVS^
sv^%
■VI-S7
13-08
13*35
+0-27
Juno 1908, Phoiograplis taken at Greenwich.
I Pmition-augle atkl />w/ance— continued.
587
V Date iLtid G.M.T
1^. J h m
Fwb. 10 lo 23
23
FoAltion-atigt
B.
DlBtAUce
Ob*.
0
52-81
53-S6
T-0.
+ 1*05
db..
/*
13*33
Tab,
1*
1 3 '25
T"0.
-0*08
, IQ
10
43
6
5»'44
sroo
+ i"56
lyi^
1317
4-0-OI
■ "
9
18
23
27S'S8
275*48
-0*40
16*50
1672
+ 0'22
■ '"
9
41
43
274*99
274*83
-0*16
16*66
1672
^0-06
K. "
10
5
24
272-87
274*15
+ 1-28
16-31
167J
+ 0-40
BtM*- 5
8
I
6
23*12
23*92
-Fo'80
n'2o
II 24
+ 0-04
■ 5
8
33
3^(/)
19 '93
21 -95
+ 2*02
irii
iriS
+ 0*07
■ .4
9
9
29(fc)
180-41
182 'Si
+ 2*40
1055
lO'gi
+ 0-36
■ "
9
49
10
I77-&6
18031
+ 2-45
1 0*6 1
10-93
+ 0-32
■ "
to
39
41
243-^4
245*23
+ i'39
1 3 "97
t4'21
+ 0-24
■ '9
II
4
17
243*49
244'2S
+ 079
i4'o6
I4'H
-1*0*05
(») Verv rxior photograph.
(fc) Verydiflaaed.
(c) Vory fttim.
id) Poor photogniph, iiateUita fbiut
(r) Satellitf! diffused,
(/) Satellite fftiiit
The tiatellita of Neptime has oow been regularly observed at
Greenwich iluring seven successive oppositions. Tiie differences
from Dr, Hermann S travels elements fornid from the observations
are as follows : —
Ep^.
No. of
litt.
rfir.
dL
llA.
n «. ifn Q.
a«.ooig
19021
51
-o'95
^0*42
-0-12
+ 0*087
+ •0005
- -0004
19031
63
0-67
-0-40
-0*30
+ 0092
+ '0005
+ '0016
1904-1
51
-083
-0-72
-0-20
+ 0*033
-*ooi7
+ -0002
19051
57
-0^82
-0*95
-0-37
+ 0*069
+ '0038
4- '0053
1906*1
59
-0*90
-1*17
-«-0'l2
+ 0-085
-*O043
- -0027
J907'2
29
- ro2
-0'93
-0'20
-o-ooS
+ •0024
+ *ooo9
1908*2
25
-0*64
' o"44
-fO'II
+0*244
- -Of 10
+ 0032
The very small eccentricity has been treatetl as a quantity to be
determined in these solutions ; accordingly the figures for Jm, r/N,
f/I, and da differ slightly from those published previously in the
MoiUhly Notktfiy in which the eccenti-icity is taken as o,
Moyal Ohtetvatoiy^ Oreenioich:
SSS
Mr, A, S, Eddingion, On the
umn. 8»
On the McUheviatical Theory of Two Star-dri/tt^ €tnd on the
Systematic MoUons of Zodiacal Stam,
By A. 8. Eddington, B.A., M.Sc,
In a former paper,* the distribution of the proper motions of
the stars was dis€usaed from the point of view of the hypothe^ifi
of two drifts of stars. The method of analysis consisted in fmdtDg
hy trial and error the constants of two drifts which wi>uld lead to
a diatribution of proper motions (as regards direcUoii) agreeing u
nearly as possible with the observed distribution. There ore
evident disadvantages in a method of this kind ; the d ifii col ty of
BimultaneoQsly adjusting five disposable constants, so as to obtain
the best agreement with ohservationj is considerable; there ia
room for bias m deciding what in the best agreement with obserrob-
tion ; and the method is inapplicable to the discti;ssiou of a series
of proper motions of stars sparsely distributed over a lat^e region
of the sky, such as the Bradley proper motions.
It is the object of the first part uf this paper {Maihemaikol
Theory) to obtain from the observational data direct equations to
determine tise constants of the drift*. In the second |iart ihe
theory is applied to the analysis of the proj^r motions of the
Catalogue of Zodiacal Stars (Astronomical Papers of th^ Ameriam
EphmnerUj vol viii,, part iii.); this is an example of a seri«t«if
proper motions which, while sufficieutly numerous to afford a goixi
determination of the velocities of the drifts, are much too sparseJj
distributed to be analysed by the method of trial and error.
Mathematieal TJieory,
I have defined a " drift ** to be a system of stars in which the
motions of the individual stars relative to the meau of the system
are hapliazard; the whole system has in tjeiieral a drift-motion
relative to the Sun. For the sake of precision, the distribution of
the haphazard or " peculiar motions '' in the ideal drift is taken to be
according to Maxwell's law.
In ** Systematic Motions," p. 36, the law of distribution of the
proper motions in the different directions was discussed for a
system of stars forming a drift thus defined ; the analysis may he
briefly recapitulated here.
A small region of the sky is considered^ and motions in the line
of sight are neglected, so that the problem is two-diroensionaU
Let the number of stars having component peculiar (linear)
velocities between the limits (u, v) and (u-f rfu, v-hdv) be
^e-'^'^'^dudv
. (i)
in accordance with Maxwell's law.
June 1908. Mailumatical Theory of Two Star-drifts, etc. 589
«i IS the total Eumber of stara of the drift
h a coaatant inversely pruportional to the mean peculiar speed
of tl^e stars.
Let f J he the velocity of the drift.
^j the inclination of the direction of this drift- velocity
to tli(^ axis of X,
r, $ the aiijomit and tlirection of the resultant Uiitar
velocity of a star {i.e. drift velocity and peculiar
velocity compouuded).
p dB the number of stars having proper Diotiona io
dimctiona inclined to Ox between 0 and $^dd>
Then u^ + 1;2 = r^ + v^^ - zv^r cos (B - 6^)
dudv = rdrdB
and hence pdB^^hlLdBi e-H'^'^^^'^^^i^'^)}rdr
'^ / o
By means of the substitution
x = hr — h 0, co« {B - $^
this expression can easily he reduced to
where t = hv^ coa (^ - ^j)
setting y*(T) = A + T€^^| er^dx
(f)
(3)
or
U)
The function/ was tabulated In ^^ Systematic Motions," p. 36 ; a
2
ctor ,- was, however, inserted in defining it there, which it has
en more convenieat to drop now.
Consider now a aeries of proper motions of stars belonging to
two drifts ; distinguishing tbe corresponding constants by fiuHizes
1 and 3, we shall have
'^(At., cos $ - B,) Ar^^-^'^Ahv^ cos B-B^) , (5)
If the observed proper motions are considered to correspond to
two drifts, a series of equations of condition will be obtained by
iviug various values to B in (5), the corresponding values of p
Biiig derived from observation. From these the six unknowns,
"»!, % i^i, v^ ^i, ^2 are to be derived ; theae^ lw>^^^<st^ xoa*^ \ife ^
590 • Mr. A. S, EddingUm, On the ixyiilS,
once reduced to five nnknowiia^ for fii+fi| is equal to the total
number of stars.
It is of course impossible, with non-linear equations of con-
dition such as these, rigorously to determine the values of the
constants which shall make the sum of the squares of the residualB
a minimum. In order to obtain what may serve, as it were, for
normal equations, I have expanded each side of equation (5) in a
Fourier series, and have equated the first few coefficients on each
side until sufiicient equations were thus formed. It is clear that,
at least if the observed distribution really does correspond to two
drifts, a good agreement between the observed and theoretical
distributions will have been obtained when the Fourier series
representing them agree as far as the coefficients of cosjtf and
sin 3^, and it is not likely that the agreement could be much further
improved. Discordances represented by differences in the eo-
efi^cients of higher harmonics are likely to be of an accidental and
unimportant character.
In practice, the process of equating Fourier coefficients is
equivalent to equating the sums 2 cos ^ , S sin 0 , 2 cos 30 , S sin 2^
etc., for the observed proper motions, to the corresponding integrals
for the theoretical distributions. These integrals are evaluated in
the note at the end of this paper. We find there that for a single
drift (n„ Vj, ^1),
J"p cos {6 - e^)de = n^ -^T//r^c-**-»' { ^Jii^h'^v^^) - Ji(# V) }
= ni|C(/tt?i)i say
|"p cos 2(6 - e,)de = v,{i - 4£?) = "1 1 ^('^^'i) I «^y
jy cos z{e - e,yW ^ n, fhv,e-^^^^^ I Jo(4'' V) - *'Ji(^WV)(i - ,^,)!
= ni|E(^t;,)| say
and evidently from the symmetry of the drift
ppsin(^-^i)cZ^= P'p8in2(^-^i)c/^=[%sin3(^-^i)tf^ = o . . (l
A table of the functions here introduced is given later (see
Table!.).
It is here convenient to introduce complex quantities into the
analysis, which will be denoted always by capital letters.
Let \\ = v^e^^
D, = D(/6Vi) = |I)(/it;i)|e-*iV . . . (8)
E,= E(//V,) = |E(/tt;i)|e3^^ij
irnoduW W^e «Xt^^^^ X^^Yi^^^xisAVsrj e<^jiations (6).
(6)
June 1908. MdthemcUical Theory of Two Star-drifU, etc. 591
Still considering one drift only
= e^ i^p cos (6 - e^)de + ie»«i r'p «in (6 - 0^
Thus l^pe^^de ^n^Q^
J o
Similarly jpe^'^dO = n^Dj
/:
(9)
Betam now to the consideration of two drifts. Knowing for
every star the apparent direction $ (measured from an arbitrary
initial line) of its observed motion, we can calculate 2 cos (9,
S sin 6, 2 cos 2^, etc. for all the stars.
Let L=i2;c*» = ifScos^ + tSsin^^
n n\ J
M= i2;««^= ifScosa^ + iSsina^")
N= iSe''*^ i(2;cos3^ + i2sin3^)
where n is the total number of stars discussed.
And let !5=J(i+a)
so that ^=i(i-a)
since
n-n^Ari
llie equation of the observed and theoretical values of 26'^
Se*"^, and S^^, in the case of two drifts, therefore leads to
2L=(l+a)Ci + (l-a)C2)
2M = (i+a)Di + (i-a)D2V . . . (10)
2N = (i+a)Ei + (l-a)Ej
To solve these equations write
C= fP \
D= fP2
E=ifP8
r
(II)
Since the arguments of Cp Dp and £^ are ^^ 2^^ and 3^^, £ and
y are real, and tiie argument of P^ is ^^. Futtlv^t, v^ \a IqvmA ^iJwa^.
592
Mr. A. 8. JBddtngtoH, On the
ixvin.8,
for the range of values of hY (up to about | AV | « i*8) oecurring in
the actual drifts, y may be assumed constant and equal to i'i63.
In Table I. are given the values of { and the moduli of C, D, E, 8E
and P for various values of ^ V. The values of SE » E --£P*
I 163
are given in order to show the accuracy of the approsdmatioa
made.
Tabli L
*v.
P.
f.
C.
D.
B.
n.
O'O
'0000
1-585
-0000
-OOGO
1000
O'L
•0566
1*573
-0884
•0050
-000
o-a
-II24
I '561
•1755
•0197
-0017
-000
0-3
•1680
1548
-2600
-0437
-0057
-■001
0-4
•a227
1-531
•3409
•0759
•0134
1001
0-5
-2762
1-510
-4171
•115a
*0253
-002
0-6
•3284
1-486
•4879
*i6o2
-0420
•003
07
•3789
1*459
•5528
•2094
1005
o'8
•427s
1*431
-61 15
-2614
-0901
-006
0-9
•4739
I -401
-6640
•3147
•007
I'D
•5179
I -371
•7103
•3679
'1558
•COS
I'l
•5595
1*342
7507
-4200
•008
1*2
•5984
1*313
7856
-4701
•2337
•008
1-3
•6345
1*285
-8156
•5175
•007
1*4
'6678
1-259
-8410
•5617
•3172
•005
1-5
•6984
1*235
•8626
-6024
•3590
-•003
1-6
7262
I-2I3
•8807
-6396
-4000
•030
17
75M
I -192
8959
•6732
+ •004
1-8
774a
I -174
-9087
•7035
•4774
•009
1-9
7946
1-157
•9194
•7305
•014
2*0
•8128
1-142
-9284
7546
•5468
+ -019
With this substitution, (10) becomes
2L=(i+a)fiPi + (i-a)f2P2; etc.
Now let (i+a){i = (i+^)A;)
(I -aK2 = (i -/?)*/
so that A; = i( I + a){i + i( l - a)^^ -
We obtain finally
2L/^ = (i+i8)P, + (i-^)Pj .
2M/A = (i+y8)P,s + (i-^)Pj2
(12)
('3)
(•4)
(15)
(16)
rune 1908. Maifiematical Thtoi'y of Two Star-driffSy etc, 593
It will be Keen from (13) that A' is a weighted mean between
If I and {,^, the weights being proportiui^al to the nnmiier of stars in
|lhe twi> drifts. Now looking at Table I. we see that f j and ^^ vary
within fairly narrow limits; actually the values of hv^ and hi\^ in
the different part-s of the sky are such that^ except in a few unusual
cases, k will lie between 1-35 and 1*45* P^or a tirst approximation,
we may either calculate a provisional value of k from the roughly
known speeds of the drifts, or we may assume for it the value
I *4o, which will certainly be not far from the truth, A second
approximation may afterwards be made if desired, using the value
of A- deduced from the resiilts of the hr^t approximation ; in
practice, liowever, this is usually quite unnecessary.
Thus k may be assumed to he known, and the solution of (14),
(15), and (16) is then easy. We find
|{Nyi-LM} = {i-/3')(P,-P,)«(P, + P.) . (,7)
. (r8)
• (»9)
. (20>
say
therefore Mz^ = P, + P=,K
I whence sulving (14) and (19) for P, uiid Pj
p.=k+(^-k)/^|
P.=K-{^-K)/y3J
niSitituting these values in (15) we easily find
We also find from (14) and (tS)
quationa {21 ) and (23) coostitute the solution of the problem.
The argument of Pj is ^^ and ht\ can be fuund from the
modulus by means of Table L Jj and ^„ can be tak«n from the
same table, and then a is found from the formula
14-a i+^S'ta*
(21)
(22)
594
Ut, a. S. Bddingion, On the
Lxvin
In tbe practical application of th^e formuhe a difficulty kxis^i
fpora the fact tbat^ whereas ft is by detinition a real quiiiitity, tbe
right-hand side of (2I), which ia derived from i^bservmUon, U in
general a complex quantity.
The reason is this: equations (14), (15), and (16) ppacticftUy
eon^titute six equations, for each of them ha^ a real and m
imaginary part, which muat be satisfied aeparaiely. But there art
only £ye unknowns. In the above solution the equations bate
been reconciled by introducing a wixtb fictitious unknown, vie, llii*
ImagiDary part of a. If, however, a and /3 ore to be purely real,
the six equations cannot be exactly satisfied. Now it is clear that,
just as we were justified in rejecting equations derired from a^ unit-
ing the higher harmonics, we should attach more wei^t to equations
(14) and (15) than to (16). It seems reasonable to satisfy ths
former exactly, and to throw the discordance entirely on (16). lo
other words, the observed and theoretical distributions will be mwAe
to agree exactly as regards coefficients of sin &, cos $, sin 2$, cos 2$^
in the corresponding Fourier series, the coefHcients of sin 5^ aud
cos 3^ will be made to agree as well as possible, and all higher
harmonics will, as before, be entirely disregarded. If this rule
seems rather arbitrary, it must be remembered that the whole
question is one of weighting the liquations of condition, that tlie
ideal system of weighting is impracticable, and that we are seeking
a practicable system which shall not unduly waste the matortal
afforded by observation.
As ( 16) is not to be exactly satisfied, our solution must be chosen
to make the sum of the squares of the two residuals (of the real
and imaginary parts of the equation) a minimum. Thi« Is equiva-
lent to making a minimum the modulus of the residual of the
complex equation. Or we may satisfy the equation exactly by
replacing X by N + ^N, where | SN | is to be a minimum.
Following this change through the solution previously given,
let the alteration in N change L- Kk to (L-K^)^; we see from
(rg) that if |^N| is a minimum,
I (L - K^) - (L - )s.k\ ! will be a minimum.
But (21) may be written
I
therefore if ^ is real, we must choose (L - Kk)^ so that its argument
is the same as, or differs by rSo"* from, that of ^>ii:— I/.
(The alternative arg (L - Kk)^^ = arg JUk - L*± 90* leads to \
value of /? greater than unity^ which must evidently be excluded^
The conditions are satisfied if (L - KA)„ is tbe projection of l'
vector L - Kk (in an Argand diagram) on the direction of
vector ± ^Mk - L- ; for this makes |L- E>-{L- KAr),, l
mmimum, axxbi^acl lo p \i«vxi% x^.
June 1908. Mathemaiieal Theory of Two Star-drifts, etc. 595
Therefore
|(L-K^)J = fL-ia|co8{arg(L-K^)-arg^M/.*^L^} (23)
and Pj and P^ are given by (2a) without modificatiati.
Thfi sign of /? in positive or net^ative according as (L - K/f)^ ia
of the same or opposite sign to JWc^h'K Either srioare root of
M/i' - L- may be taken, but the same root must he adhered to
throughout. It ia, howjver, desirable to choose the root whose
argument a>,Tee« roughly with the direction of tnotion of Drift 1
relative to Drift II, otherwise the suffixes of the constants will not
agree with the usual designations of the drifts.
The following example shows the practical application of the
method. It refers to Regioo C (K.A. 2^^-6^ KRD. 2o'-52') of
the Groorabridge proper motions.
tFrom the observed proper motions I find
Total number of stiirs n = ^12,
S008 ^=+73*o Ssin 0= +219*0
5coa2^=-42*3 S sitj 2i9= + 124*1
2 cDi36>= - 98-45 S^io 36^ = *+ 23*1
hence, dividing by «,
L= + -143 + -4281
M= -'083 -I- '242 t
N — - .192 + '045 t
and yN= - -223 + '052 t ('y=i'i6j)*
Assume provisionally k— i'40, we find
Ny^*-LM= - *i967 + '07374 = '2 100 expi* 159**5
MAr-L" ==+ 0466 + '21641=^22 14 expi 77^*9
therefore by division (equation (19))
L 2K= '948 expt 81" 6
^ K^s H--o69 + -469 t
^^H therefore h-Kk— + "046 -'2291,
^m ^ •234expi 28t'-4;
^ also Jyik - L- = 470 expi 39" *o.
If we continue the solution with L- KA- unmodified, equation
(21) gives
(i= --300- "442 t*
• Expi./'=t^.
596 Mr. A. S. EddingUm, On the
But modifying it in accordance with (23)
lxviilS,
and
(L - 0)0 = -234 cos (28i'-4 - 39"-o) expi 39' -o
= - -1083 expi 39'-o
(L-KA)o
= - 4-53»
whence
i8=-
lliis value of ^ must now he suhstitnted in (22),
y
i^= 1*244.
v;
^\A nAMA;"- U = *6io expi 39^0
= •474 + -384 1
and L=*i43 + '428t.
Sum = /fP, = '617 + -812 I,
= ro2o expi 52**8.
Therefore Pj = "729 expi 5 2° '8.
Similarly we find P2 = '174 expi 132*7.
The directions of the two drifts are accordingly
^, = 52°-8 ^2=132^
To find their velocities we make use of Table I., which gives
the corresponding values of | P | and hv.
hv^= I 'Si
also from Table I.,
but '—
^1=1*211
I + a I + iS f 2
^v2 = o'3i ;
^2= 1*547
^ 1-547
= r2i2,
whence a = - '096
l(i+a) = -452 *(»-«)=" '548. .
Thus 45 -2 per cent, of the stars belong to Drift I and 54'8 per
cent, to Drift II.
Finally, we can check the provisional value of k^
June 1908. Mathematical Theory of Two Star-drifts, etc, 597
agreeing with the adopted value 1*40, so that no further approxi-
mation is needed.
The results obtained by this method agree closely with those
previously obtained by the method of trial and error (*^SyateTiiatic
Motions, "p. 50), I give below a comparison of the constants deter-
mined in the two waya for four of the Groombridge llegions ; it
afltords some aort of indication of the r&liability of both methods.
Aoalytfcjil Mctliorl.
Trial and Error,
filift I.
Drift 11.
Drift I.
Drift u!
hv
<38
0*31
r6s
030
9
0"
157^
o*
I5S*
w*
525
47*5
48'S
51*5
hv
I '47
0*48
I'SS
0-45
$
12*^
"31°
lo'
130-
n
49-5
50*5
49'5
50-5
hv
i'6i
0*31
165
O'JO
9
53"
133"
55'
12^
n
45*2
548
41-5
S8S
Ar
0S6
077
1-20
0-45
B
226"
75"
225'
St."
n
63-0
• Percent*
37^0
46 S
535
R^on 0
Eegioa F
The weakest point in the solution m exemplified in the case of
Region F ; the determination of a (or fS) m not very satisfactory.
The difference in the two solutiuoa in the case of Region F depends
entirely nn the division of the stars between the two drifts ; if we
had adopted the same value of a in the two cases, the remaining
four constants found from (22) would have agreed almost exactly
with those found by trial and error. The weakness of the deter-
mination of P can be shown analytically.
Differentiating (31),
^= -iA»y{(MA-L»)+(L-Kfc)n-'
= -^(P,-Ps)-'.
Kow I Pj - P2 1 is generally about 07, but may be less, hence
-^ : is generally about 10, hut may be more.
Thus in a region containing 500 stars, a change of 2*5 in
2 cos 3^ or 2 sin ^0 would produce a change in N of '005, and
the corresponding' change in f3 or a might be + 05.
The question arises whether the weakness of the determination
of P is a defect of the method of analysis or is neceaaarily involved
in the nature of the observational data. I think there is little
doubt that the latter alternative is correct; I have examined
^various other methods of determining fi^ but all are rather insensi-
ive. In the case of Region F, h<3th the solutions given abov* are
found to agree with the observed distributions almoai ^iC^^-^ n^s^.
598
Mr, A. S. Eddingtony On the
Lxvin.8.
Thus it aeemg likely that even in an ideal »ohitioii we should ba?«
one equation very mncb weaker tbiin tlie other four (the weakneM
may be more pronounced for some regions of the iiky than Im
others). As the five cunatants depend on one another attd on tiin
fifth equtttion, they may all ibare in the uncertainty.
One or two considerations help to avoid this difficultjr to aomt
extent. We may he content to assume a=o, i.e. that the stara art
evenly divided between tba two drifts; all evidence seenos to io-
dicate that this is approximately true, and it is conceivable that
there may b*? some physical reason for it. Or, instead of adopting
the value of a found for the particular region, we may adopt ■
mean found from all the regions discussed; this will have a muck
smaller probable error. But the moat fortunate circumstunce i*
that we mat/ determine t}i£ rdatim maium of th^ two drifts aimoti
ifulepeifdentltj of a,
Kquation (r8) givet^
If j8 lies anywhere between - 0*3 and + 0*5, (i - ^)~* may be
put e^^ual to -98 with an error certainly less than 3 per cent.; bnt
this rant;© of fS includes all values likely to occur. Onlj in the
case of a very great disparity in the distribution between the two
drifts could a value outside these limits occur. Thus Pj - pj Is
nearly independent of /? or a. P is a sufficiently nearly Un^r
function of AV for A(Vj - Vj), to be also nearly independent of a.
Thus although adopting a = o may lead to some error in tbe
determinations of kY^ and h\^^ the error will nearly be eliminated
from the determination h(V^ - V^). This relative motion of th€
two drifts is the quantity which mo«t int-erests us, especially a^ a
systematic error in the proper motions does not affect its determiDa-
tion 80 adversely as it affects the determinations of ?iVj and //V-.
S^fdemaiie Motiona 0/ Zodiacal Stars.
I have applied the theory given above to the diBcussion of the
proper motions of the zodiacal stars. The proper motions w«^
taken from thfi Catalogue of Zodiacal Stars, Astrmiomi^al I*aptr$
qf the Amei^iran Ephemeris, vol viii., part iii Excluding the
stars of the Pleiades, this contains 1553 proper motions, I divided
the zodiac into sixteen regions^ each extending 22 J* in longifude
by about 16 in latitude: these are denoted successively by lo,
Ila, . , . Ylllri, I^ VIIB, the centre of region la beit^
at the first point ot Aries, As regiuns la and 16 are diametricailj
opposite to one tmcither^ the o)>served motions are in parallel pUnaSi
and the two regions may be treated together ; aimiiarly, the olb«r
regions can be treated together in pairs. Thus the number \i
regions is virtually reduced to eight, each containing from 150 t*i
250 stars.
The distribution of the proper motions as regards direction ic
the eight tegioiv^ \b ftVovju \u Tvihk TX Opposite ^ = o* in the
June 1908. Mathematical Theory of Two Star-drifts, etc, 599
first column is given the number of stars whose observed motions
are in directions between 0 = 355'' and d»5% and so on. The
numbers have not been smoothed. For stars in lo, IIo, etc.,
Oszo" is in the direction of increasing R.A., and ^ = 90** in the
direction of increasing Dec. For stars in 16, 115, etc., the reckon-
ing of 0 agrees with that in the opposite parallel planes la, IIo, etc.
Tablb II.
DiitribtUion of the Proper Motions in Direction,
Baglons.
$
I.
II.
III.
IV.
V.
VI.
VII.
viri:
o*
16
'4
9
5
7
2
I
2
10
II
8
3
8
0
0
5
4
ao
3
3
2
I
I
2
2
30
2
0
2
3
4
2
I
40
I
a
0
I
2
0
2
50
4
0
2
3
2
3
0
60
2
0
I
0
I
I
0
70
3
0
0
0
0
2
2
So
2
0
X
I
0
0
2
90
3
I
I
I
0
I
I
100
I
1
0
I
I
0
0
no
I
0
2
I
I
2
0
120
0
I
I
0
4
2
3
130
0
I
2
3
2
2
4
140
I
I
2
0
3
5
4
150
2
0
I
4
I
3
5
r6o
3
I
2
5
6
4
3
170
I
3
2
3
2
9
II
180
0
2
2
6
10
8
13
190
6
I
I
6
7
18
M
200
6
4
3
8
9
12
12
210
5
6
3
5
9
12
M
220
6
3
5
II
16
14
8
230
10
6
8
II
20
10
6
240
2
2
4
13
14
16
4
250
2
3
10
9
17
>3
4
260
1
6
7
9
9
9'
5
270
6
2
7
21
12
3
8
2S0
3
9
12
17
10
6
4
290
4
13
20
10
8
10
4
300
6
II
18
16
8
0
10
310
12
8
13
13
6
7
3
320
17
II
15
27
13
6
2
2
330
14
12
18
8
4
2
5
340
9
20
18
23
6
I
0
3
350
10
17
9
25 _
5
0
8
4
TdU]
175
183
156
240
221
198
v^
\^^
6oo
Mr. A, S, Eddington, On the
LXI^
It will be seen, by looking down the colunms of the Tabl#
that the two streams are plainly marked in Regions I, n^ III, and
VI IL In the other four regions their directions (projected on the
sky) are inclined at an acute angle, and the existence of the twij
streams is rather concealed. The success of the analysis in theis
four regions is on that account especially interesting. It xdaj be
noticed that this belt of the sky in not so faTourable as the Groom*
bridge region for showing conspicuously the separation into two
streams ; the centre of the latter region lies between the two aplcei^
80 that in it the streams are in nearly opposite directions.
Althuugli, in the main, pairs of regions such as I<^i and Jb wcw
treatei! tngether, I thought it safer to calculate J^ik - U and L
for la anil lb separately, and to take the mean afterwards. This
was in onler to avoid the possible ejects of systematic error, hy
ensuring that the differeoce of motion of the two drifts found from
the observations was a dilTerence of motion of intermingled systemi
of stars, and not the diilerence in the apparent motion of stars in
la from that of stars in lb. Actually, however, the precantioo
might have been omitted. I found that in every region very nearly
the same result was obtained whether the two halves were treated
separately or together.
For the solutions I used entirely the equations —
r did not calculate N, or attempt to find 0 from the observattoni.
The &nal resnlts given below depend, tiierefore, on the assomptioo
(based on previous experience) that the stars are evenly distributed
between the two drifts; but calculations are given which show
what extent the results obtained would need to be modified if th
assumption is incorrect.
As a preliminary I made two solutions, («) assumtii
n/;^^-
o and (h) assuming
V 1+0
1*1 : In both cases
k was assumed lo be i'4o. These correspond to assuming that
the stars belonging to Drift I are about (a) 55 per cent, {h) 50
per cent, of the whole.
The combined results from all the regions were —
yfbcityofDriftl {j«) ''^^ towardt Latitude
IW 174
Velocity of Drift L . ,
i(bj o-6o
Velocity of Drift I ({a) vS^
relative t^ Drift II I (b) 1 '90
-36%
-41%
-48-,
- 16-5.
Longituiie 105'
AK
\ 1 908. Mathematical Theory of Two Stm-drifts, etc, 60 1
The matual relative velocity of the two clrifti is thus determined
nearly independently of the a:*sunied division of the stars between
them, a result which has already heeti arrived at theoretically.
For a final solution, using {h) as a first approximation, I cal-
culated for each re^^ion values of k and fi^ assuming that the stars
I equally divideil between the drifts.
The valuea of h for the Regions I, 11, ... , VlIT were
ctively —
:
1
I '35* 135* I '36,
1*40, r
44?
1*44, I
'43»
'•58»
L
and of
yn
w
ri2j 112, IT r,
fog, 1"
o7t
I -07, 1
•08,
fio.
Ferforminj;^ the analysis with these values^ the constants of the
drifts in the eight regions were found as follows : —
Re^loiL
Lon^tude of Tentre.
0' , 180'
''57
Drtft I.
DHftn.
. I
0'46
244'*»
l«
aa4 , 202i
1-46
350*0
058
249*4
III
45 t 215
r86
330-0
0*63
252*2
IV
674 . *47i
r6S
323-5
o'st
271 -3
M
90 , 270
I'oS
3997
070
231 '2
■^vi
111^ , 2924
ro4
245 4
0*54
233 *S
VII
US 1 JiS
I -35
20S-8
0*40
275 '»
VIII
J57i * 3J74
1*49
189 '2
0*54
292 3
If we resolve these drilt*velocititia along and perpendicular to
the plane of the ecliptic, the coraponent^i perpendicular to the
ecliptic derived from each region should agroe.
The determinations of these components are —
f
T Drilt I, ' '97, ^ 77, - I -35, - rig, - '94, - i 'oo,
Drift 11, - -30. - '43, - -52, - -51, - '54, - '48.
*g6t - 76, Mean - "99
*37, - '39, Mean - -44
The accordance of these seems decidedly good when it is
remembered that they are derived from regions containing on an
average less than 200 stars.
The component drift- velocities in the ecliptic are more or less
foreshortened according to the longitude of the region ; I deter-
mioed the mean valuee by a least-squares solutioB.
The liual results are —
Vdocity of Drift I,
Velocity of Drift II,
Velodty of Drift I. rela-
tive to Drift U.
17S towards Latitude -33*'«, LongituJe 105**5
0*59 n t. -47''9. •• 303"7
j-l-94 »- .» -»6'> .. i^"'^
602
Jfn A. S, Bddingtini, (hi the
UtTOLg,
Tha slight difference between this Testilt and that of solution
(b) represents the effect of allowing for the varifttion of p and k
from region to region, instead of adopting a mean. The comparisoy
between solutions (a) and (b) serves to indicate how the resulti
would be changed if the star* were not evenly divide*! between the
drifts. Tlie constants most affected by such a change an? the speed
of Drift I and the direction of Drift II ; the other constaQia ar«
nearly independent of the assumption, and are therefore more reli-
ably determined.*
From an examination of residuals, I estimate that the probable
accidental error of the determiiiation of hV^ and /tV^ is about ± '06,
and the probable errors of the apices of Drifts I send II are re-
spectively about 2' and 6* of a great circle.
Converting latitude and longitude into H.A* aad Dec., the
positions of the antapices may be compared with previous deter-
minations as followH —
Drift I
Drift II.
Ka^eyti
R,A,
ss'^
D«c.
-ir
R,A.
260'
Decv
-^
Dyson ,
»»
94'
»i
- 7'
T»
240"
«'•
-74*
Groombridge st&rs
0
90'
I)
-19*
11
292*
ri
-jF
Zodiacal star a
»♦
103-
f
^ji'
M
330^
,,
-6*'
The great R.A. of the antapices of both drifts found in the present
discussion is rather hard to account for.
The veiocitieR of the two drifts At^i= 178, At?2 = 0*59 arc in
excellent agreement with those found from the Groombridge stan
kti^j =17, hv,, = o'^.
For the velocity of one drift relative to the other» the Zodiacal
stars give the value 1*94, From the Groombridge stars (by a leaist-
sqimres solution from tlie rasults of the separate regions) I have
found the value 1*90. The determinations of the point towardi_
which this relative velocity is directed (called hyProfeaaor Kapt
the true vertex) are
Kapteyn
. KA, 91' Dec, + 15'
From Groombridge stars
. 95' . + 3-
„ Zodiacal ^,
,» 109" „ 4- 6*
Professor Schwarzschild^s deteiniination of the line of symme
of motion may be added. This, although based on a rather differ
tbeoryj is directly comparable with the above. He found.
From Groombridge stars ,
R.A. 93''Dec» + 6'
• It Bhoold be understood that it ia not impossible ta determine a from
the observations, bnfr simply that when, as in the present caihj, a few itw*
are liisctifssod, the value ol a is liable to a greater uncertainty than aotuf »^
the other reaulta. Undoiabtcdly from the whole 1535 stan a fairly gi»J
meau value of a oould be detenuined ; but the taak of computing it for m^tta
regioDs separately t and takiiig the mean, would be laborious.
ae 1908. Mathematical Theory of Two Star •^driJU, etc, 603
Farther, from Profe.s*or Dyson's iiivestigation, an R.A. of about
92* for this [)oint may be inferred.
Thus thfl Rigbt Ascension given by tht? Zodiacal proper motions
is discordtmt as compared with the other determinations* The
number of staru here considered is fewer, and the proper motions
are perhaps not so well determmed^ but I do not think the dis-
cordance can he altogether attributed to this. Nor can it be traced
to a loodl anomaly, for it seems tn be indicated by the proper
motions all round the ecliptic. I have verified by calculation that
the Regions la to VIII^ agree with Regions 16 to VIII/^ in leading
to this high value of the Right ABcension.
Note on the emluatmi 0/ certain integrals required
in the anaiysis.
(1) To calculate n^Cj = I p cos (^ - $y)d$f for a single drift.
J o
We may choose the initial line, along the direction of the drift, so
that ^1 = o.
p= -^e
7r
\p'h*t^i
'^^^re^r e-''d.v\
Then
where t = //Tj coa $,
Now I J ^re^j e-'^dx \ coa ^ is au odd function of cos ^ and
PTEnisbes when integrated from o to 2;r.
Hence / '"p cos BdB = %-^*'^^'^ i '%r^ cos Me
Jr. TT 2 J ^
^n,hv,
m' n
C0S-^«*-Vcoii-^(f^^
Now
2 Jir
J o
= 27re*J(j(tic).
Whence differontiafciog with respect to #c,
2 j COB %« ^^^ '"^de = 27re*( Jjj(tif) - tJi(t«)),
Now write ic = |/t-y|- and aabstitnte above
6o4 Maih&maiical Theory (^ TvH) Star^hri/t^ hmSLS,
Tftbles of the Beaeel Fnnctioiis of an imftginaiy migmnenl tie
given in Brit, Assoc. Reports, 1893 and 1896, and hare been natd
in calculating Table I.
(2) To calculate ^i^i^* / pcos2tfrfft
We have p^^ T e-f>^**+^^-'^^^')rdr
V Jo
and identically
Jo ^ J Q J O
= ^re-*«('»+|'i''Wr[''e'«»W. . . . (i)
where z = zhH^r .
Hence r?i=^i'^*re-*'<'*+'^Vrfr.2irJo(t2:) . (2)
But from ( i )
f "p cos WdO = '*1^'" / "t-''^<''-+^v-Vc7r^, / ^\'^^^^de
Jo TT J o dZ-J o
TT J Q Ga"
by Bessel's dillurential e(iuation
Integrate by parts:
' 77 4/«^y, L Jo
+ 'h'}: } Cdri - 2h-r)e-'''-^"'2^J,{c:)
~"' + 2/rr,= 2/<V
(the integrated part vanishes for r = oo and reduces to -jjTje'* ''
-June 1908* TcMes of two hypm'gtomeiricai fimdions, etc, 605
At tlie lower limit ; the part remaining to be integrated it simpliiied
hj means of the ideTititf (2)),
/^w j'aff iitr
hence | p cos 2*^(i^ = 2 1 pcoi^dB - I pd$
Jo Jo J 6 '
*he integml I pcas^^tl^, and correeponding integrals for
any odd multiples of 61, can be found by a aimple extension of
the metbo'l employed for / pcos^/i^, Thia integrals for even
Jo
ultiples of ^ are more troublesome to evaluate, but the method
employed for i poos 2 Scfd always encceeda.
tb
■ Alt
TM^ of UiS two hypergeoTnetricc^ futiclioru, F ( 1/6, 5/6^ 2, sin* i- \
I and f( - 1/6, 7/6, 2, sin^i^Y l^Iween i}ie limiti iota equaU
I 90 and 180 fiegreeff. By C. J. Merfield.
In tbe metbod of Mr. R» T. A. Innes for the detenuination of
the secular perturbations,* there are two by pergeo metrical functions
to be deduced. In an appendix t to this i^aluable paper, tables of
the logaritliras of tliese functions are given witb the argument
iota for eacb degree 1 fur tlie firat quadrant.
Tables of tbeae functions facilitate tbe application of this
metbod in do small degree, and it aeemed desirable to extend
them, as in many future investigations it will be found that the
angle iota will much exceed a quadrant. Taking an example,
Eros g— Earth, it will he noted that the modular angle theta, the
argument to tbe tables of elliptical integrals, reacht^s tiie vahie 60',
eorreaponding to iota 138'' 18', and there will bo many other casde
in which it exceeds this value*
In the preparation of the tables here given the formulw || (/.c,
I
• ** Computation of Secular Perturl>»tioiw/' by R, T. A, Innes, AfonM^
^ofittit, vol. Ixvii, 4»7,
t Tables for tlie application of Mr, InoesV Method, by Ffank Robbiua.
Le., 444'
X The T&lneti of th«« functioofs for iota eqnaU o" have buen omittsd
in the tabuUtio^i by Mr. Robbms,
§ ** Secular Penurbationa of Erot," by C. J. M©rfield,^j^r.^flM;^„ 4178-79,
Band 175.
I The valaea of these functions may be c\edu<:ed tt^vm ^tSna, V'^'^t <^^«tt.
eoeBaitmts of twenty terms, Aitr, iVocJir., 41^5, B^wd vi^v^. ^*i^'
6o6
Mr. G.J. Merfidd, Tables of the ' IJCTIIL %,
442) of Mr. Innes have been adopted. Seven-figare logarithmi
have been used, and the Additions- und Suhtractions-Logarithmoi
by Zech where necessary, but the powers of the trigonometrical
ratios have been formed from the values of these functions
tabulated in Vega's ten-figure table, and the results used to seven
figures.
Taking
ij = 1 80 - 1
then
cos J = sm -
and the following relation holds,
¥(-116,,. sin«— ) F^i/6
f(i/6 ^^^^y) ^("'/^••
sin2i^ +
sm'
-i)= 216/35,
The logarithm of the right-hand member equals 0*29323583 ....
Writing in this formula the quantities taken from the tables,
then it will generally be found that the residual does not exceed
a unit in the seventh decimal place of the logarithm in any
porti(m of the tables. This formula might have been used in
calculating either function after one of them had been deduced
between the limits 90 and 180 degrees, combined with the values
tabul.'ited by Mr. Robbins, loco citato.
Sydney :
1908 Ffbruari/ 10.
Tablbs.
1
Log F (1/6 . . . .)
90^
0*0183800
91
0-0187832
92
0*0191904
93
0*0196014
94
0 0200 1 63
95
0*0204351
96
0*0208577
97
0*0212842
98
0*0217145
99
0*0221487
100
o'0225S66
Ai
A.2
LogF(-i/6. ..0
^1
•^
-3991
■\-4l
9-9738258
-5778
-62
4032
40
9-9732418
5840
62
4072
3^
9-9726516
5902
62
4110
39
9-9720552
5964
61
4149
39
99714527
6025
61
4188
38
9*9708441
6086
60
4226
39
9-9702295
6146
62
4265
38
9-9696087
620S
60
4303
39 .
9-9689819
6268
60
4342
37
9-9683491
6328
59
Ml^
•v-jn
\
^^c^n-l^^^
6387
-60
^^^\^
-^W
fun© 1908. two hj/pergeometrical functions, etc.
607
1^
LogF(i/6..,,)
Tor
0*0230282
102
0-0234734
JO3
0*0239222
104
0*0243745
«oS
0-0248304
106
0*0252897
to7
0-0257524
108
0*0262186
109
0-0266882
no
0^271611
III
0-0276373
112
O-02S1166
H3
0*0285991
114
0*0290847
115
0-0295733
^6
0-0300647
F
0-0305590
118
0 "03 10562
119
0*0315561
120
0*0320586
121
0-0325637
122
0-0330712
123
0-0335811
124
0*0340932
125
00346076
fs6
0*0351241
127
0-0356426
13$
0*0361630
129
0-0366852
130
0*0372090
131
0*0377343
132
0-03S2609
n^
0-0387888
IS4
0-0393178
135
0^398478
136
00403785
nr
00409099
138
0*0414418
139
0*0419741
140
0*0425064
M
Aa
Lo«F(-i/6....)
+ 4416
•f36
9*9670657
4452
36
9*9664152
4488
35
9*9657589
4523
36
9*9650969
4559
34
9*9644291
4593
34
9 '9637557
4627
35
9*9630767
4662
34
9-9623922
4696
33
9 '96 17021
4729
33
9-9610066
4762
3»
9*9603058
4793
32
9*9595997
4825
31
9-9588884
4856
4886
30
9*9581719
28
9 '9574504
4914
29
9-9567241
4943
29
9*9559929
4972
27
9*9552569
4999
26
9*9545*64
5025
26
9*9537713
5051
24
9'953o2i8
5075
24
9*9522679
5099
22
9-9515099
5121
23
9-9507478
5144
5165
21
9-94998 »8
20
9*9492121
5^85
19
9-9484388
5204
]8
9-9476621
5222
16
9*9468821
5238
»5
9*9460991
5253
13
9'9453»32
5266
U
9*9445247
5279
u
9-9437337
5290
10
9*9429403
5300
7
9*9421449
53*^7
7
9*9413478
5314
5
9*9405492
5319
-^^4
9 "9397493
5323
0
, 9-9389485
5323
-I
9*9S^mo
+ iJ22
^1
A9
6447
-58
6505
5S
6563
57
6620
58
6678
56
6734
56
6790
5S
6845
56
6901
54
6955
53
7008
53
7061
5»
7^3
52
7165
50
7215
48
7263
49
7312
48
7360
45
7405
46
745 J
44
7495
44
7539
41
7580
41
7621
39
7660
37
7697
36
7733
34
7767
33
7800
30
7830
29
7859
26
7885
25
7910
24
7934
20
7954
17
7971
15
79S6
13
7999
'9
8008
n
%c»\s
1
-^\%
J
6o8 Tables of two k^fergmikdnoti fwiuii^ lxviilS,
(
LogP(i/6....]
141
O'04y>386
142
0-0435704
M3
0x^41017
144
0-0446322
145
0'O45'6i7
146
0-0456900
147
0*0462167
148
0-0467415
149
0-0472642
150
0-0477844
^51
0*0483018
152
0-0488161
153
0-0493269
154
0-0498337
155
0*0503362
156
0-0508339
157
0*0513264
158
0*0518131
159
0*0522934
160
0*0527669
161
0*0532328
162
0*0536904
163
0*0541391
164
0*0545780
165
0*0550063
166
0-0554231
167
0-0558273
168
0-0562179
169
0-0565937
170
0-0569532
171
0-0572950
172
00576174
173
0-0579185
'74
0*0581958
175
0*0584468
176
0-0586684
177
0-0588566
178
0*0590063
179
0*0591098
180
0-0591 S^^
Ai
A3
LofP(-iA5....]
I M
A|
■5322
-4
9-9373452
-8018
0
5318
5
9*9365434
8018
+4
5313
8
9*9357420
8014
6
5305
10
9-9349412
8008
II
5295
12
9'934i4i5
7997
14
5283
16
9*9333432
7983
20
5267
19
9*9325469
7963
25
5248
21
9-93I753*
7938
30
5227
25
9-9309623
7908
34
5202
28
9*9301749
7874
40
5174
31
9*9293915
7834
45
5143
35
9*9286126
7789
52
5108
40
9*9278389
7737
55
5068
43
9*9270707
7682
65
5025
48
9*9263090
7617
73
4977
52
9-9255546
7544
79
4925
58
9*9248081
7465
^
4867
64
9-9240705
7376
96
4803
68
9*9233425
72S0
107
4735
76
9*9226252
7173
116
4659
83
9*9219195
7057
128
4576
89
9*9212266
6929
137
4487
98
9*9205474
6792
»5i
4389
106
9*9198833
6641
165
4283
115
9-9192357
6476
iSo
4168
126
9-9186061
6296
194
4042
136
9*9179959
6102
211
3906
148
9-9174068
5891
231
3758
163
9-9168408
5660
253
3595
177
9-9163001
5407
274
3418
194
9-9157868
5«33
300
3224
213
9*9153035
4833
331
301 1
238
9*9148533
4502
36J
2773
263
9-9144393
414^
403
2510
294
9-9140656
3737
44S
2216
334
9-9137367
3289
507
1S82
385
9-9134585
2782
581
1497
462
9-9132384
2201
687
1035
-607
9-9130870
1514
+890
•V^7&
^ <i-9l^0246
-624
June 1908. FosUion of ike Sun's Axis of Rotation,
609
Further Note on the Potdiion of the Sun's Axis of Rotation, a»
deduced from GremiwicJi Sun-spot Meamres 1874-1885,
Pafm*» of (he LU,SJt. Computing Bureau, No, IL Bj
H. H. Turner, D,8c,, RR.S., Savilian Proffssor.
I, This note gives for the period 1874-1885 ooiiiputationij
similar to those given for the period 1886-1901 in the December
No» (p, 98), The discuasion ia limited to sput-groups which live
for ten days. The tables are niimbereii to correspond with those
of the former note.
Tablr h
LaiUutU drift brlwecfi -t 65* and - 65* in each month [of tlic fears 1874-1S85).
lAUtude, -as" -ao^ -15' -lo** o" +10' +15' +20' +25"
J&tl«
+ 57
4-170
Feb.
-hiij
-41
Uaf,
-27
+ 145
Apr.
-5S
-hloo
M«y
'85
—
June
_
- 171
July
-23
—
Aug,
—
+ 15
S«pt.
+ 35
-90
t>ct.
^
-n
Nor.
_
'37
Dec.
-75
Hean
—
^
-64
-48
+ 15
+ 79
4-12
+43
'33
+ 35
-II
+ 18
-f6o
-19
-61
+ 45
+ 23
+ 39
+ 3"
-97
+ 28
-136
+ 57
^12
— -1-62 +240
-33
+ 62
+ 16
+ 34
+ 45
-50
-18
+ «7
+ 8
-38
-II
00
+ 25
-29
+ 30
+ 55 +^3
+ 5 +62
+ 50
+ 80
+ 70
+ 5
-34
+ 3<
-53
-X7
+ 33
-fi -f 10
-61
4-27
-55
-4
-52
-80
+ 2
-21
^16
+ 97
+ 6i
-22
+ 125 I
-116
+ 23
+ M
4-46
-7
2^54
+ n
+ 77
+ 118
+ 10
+ 73
' 2
+ 57
+ 38
+ 53
-83
-I
+ 5
+ 70
+ 5
4-1^5
4- 115
-5
o
+215
+ 14 +"4
The unit in the tables is o''oij and the figures are, iu Table X.,
differencee between the mean residual at +65° and -65* in
ZaiUude dr^ betuften 4- 3S* an<f
LAtitofle. -aj" -ao* -15"
Tavlis II.
- 35" iw each mofUk (t^th^ yr^rn 1874-1885).
lo* o' +IO* +15* +ao' 4-25*
Jan.
+48
+ 95
+»5
+ 12
-37
+ »5
-39
-53
—
+ «5
Mb.
+ 50
-6
-51
-30
4-20
+ 23
+ 3
-5
+ iO
+ 152
Mar.
+ 32
+ 71
-6
+ 3«
+ 23
+ 39
+ 70
-2
^
—
Avt.
-35
+80
+ 49
+ ti
-t
+7
+33
4-10
+98
—
May
-87
4-10
+ 24
+ 31
+ 36
-31
+ 3»
+ 68 '
+ 50
+88
JmiM
4-12
-70
4-10
+ 34
+ 61
+60
-23
+ 75
+43
+ «35
Inly
+ S»
-88
- 1
-16
+ 25
- 10
^ 10
-38
+ 12
+ 87
A11K.
+ 47
+ 15
-26
4-10
-63
+6
+ 90
+8
+ 15
Sept.
+ 2
-6
-M
•87
+ 26
-4
+ 3
+ 8
+ 4t
+ i«
Oct
—
+5
+9
4-25
+ 4
-»5
-15
+ 5
+ 10
— '
KOT.
—
-43
+ 74
+ 17
-t
^67
-15
+ 2
-58
—
Dec.
S5
—
+ 43
+ 137
+ 30
+ 59
-88
-'94
+ 22
+€i
— — ' +X4 +ia +1^
+ 1
•^ -^ ^
6 10 Prof , ff, S. Turner, Ftirther Jfote on the utvnLS.
Iqnf^tndti from tbe centre of the disc ; and hi Table IX, mmikt
differences for longitudes ±35' from tbe centre.
Excluiiing,* at any rata in the first instance, the oatBid«
groups (lor latitudes above 20°), we can now analyse the n-
mainiug 6 columns in each table harmonically, to End aa
expression of the form
A sin ^^Bcos ^ + C,
where ^ = o for the middle of January,
Multiplying tlie coefficients A and B by J cosec 65' for Table
I., and I cosec 35 for Table It, we get the error of the Suns
axisj which we may now express (as Carrington does) in minutes
of arc. The separate determinations are given in Table III.
Table IIL
Qn4tfUiii$t rt^frm$fiiin^ Uw Mrrora qf the Sun's ad4fpUd >
Latitudes. -20" -15* -lo'^ o' + lo' +15* ^^•Um,
A from Table I. -0^5 -o'l •f7'5 +S*o fi9*6 +8*0
A „ „ IL -3'3 +4'3 +3*9 +12*6 +15*5 +t2-a
ii r. If 1- -27 +14*3 ^">'2 -1*0 -^^9 -2'4
B „ „ 11. +28 +145 -8*8 HH98 -5'9 -52.3
Inspection of Table III, saggests the following conclusions
(a) The accordance between determiuations from meridians
±65" and ± 35" is not so marked as before ; but the discordances
are not systematic. We must remember that the former series was
based on 16 years' observations, and the present on less than n
years'.
(b) The mean error of the adopted axis in A is confinned
within very narrow limits, the mean value of A being -h7''3*s
against + 7 '^ ^^^ ^^o period 1 386-1901. But the mean value of
B for the same period was - 7**8, whereas the measures here
diRciiBsed give nearly zero. Can we ascribe this difference to
accidental error? It is possible that B is more liable to error
than A, owing to the fact that its coefficient is large in December
and June, and il gets the full effect of any difference between
summer and winter. If, for instance, there are f&wer good
photographs taken at Greenwich during the winter, there will be
more Indian used in tbe series ; and any differences between the
two would have maximum effect. Such points must be separately
examined. !Mean while, we may remark that the arithmetiail
sum of the differences between pairs of values of B from. Tables L
and IL in the present paper is 66** i as against 2^'"j for A j in
* In the toTtaw \v«^x V^t>«fcu\ttttftftft\svi*>aK^V»5*Ti. uiailver^ trail
posed. They we t©v^t»^ V^«tfi vo^ <^* «stwfcx w^«t .
June 1 90S. Positmi of the Suns Axis of Eotation,
6ir
the former paper these numbers were 2o''7 and 14'j ; bo that
there is aome reaaon for regarding A as better determined than B,
and abo for regarding the former results as entitled to greater
weight than the present. The best provisional determination of
the errors of Carrington'a axis, assuming that it remained fixed in
apace during the period 1874- 1901, would therefore be
A=+7'
B=-5'
giving double weight to the results of the former pajier.
(c) As regards the discordancQB between the diiferent zones, we
may compare the results of the former paper and the present as
follows :^
-20' to -lo' to +10* to -f ao*
1874-18S5 +o'i -fS^o +I3'S
1886-1901 +3"2 +5-Ji 'fi3'3
Weighted Menu +2 '2 +6*5 +13*5
B
-ao' to - 10' to +10' to -f ao*
+ 7*2 +0-3 -9*2
'1*3 -13"5 -S7
'5
-S'9 -S-9
double weight being given to the second series in taking the mean.
(//) We now come to the constant C, the mean value of which
is positive (m already remarked in a note on p. 103 of the Uat
paper), instead of negative && before. Rearranging the material In
oonaecutive years, as in the former paper, we get
f74
876
^77
I80
I81
tS2
B4
85
Table IV.
Drift in LalUude hcUcnen +65" aiid -65* /ram cenirai in&ri<iian,
-25' -20" -if - io* o'' -i-io* +15* +20' +25"
-70e 51 J -245,^
34n Oi +67.^
+ 3Ia
+ 40si
-27i
— +54j
- iO o
+ 63a -45*
+ 75a +874
+ 20i —
-6^
4-46j
61,
+ 57«
+ 90,
+ 5i
+ 45i - -
-171:1 +i9» +40,
+ 3Sj - 57 + H^a
- »4rt +S2iy +64,^
^^h +5i6 +S014
+ 45i +5'^ -lis
— — + lOOi,
+ 203i -35, -41,,
-3^ +33fi +»»i2
' 5217 cy - 5t6
+ 2423 -1% +4^v»
+ 35ia +i0i^ +Su
'4fj +49i3 +'3s
+ 22a +iSift +86^
+ 373 — ' -
6l2
FosUum (^ the Sun's Axis i^ JSHaii&n. uvmli
In Table V. the results of the former paper are repeated, so m
to show the annual results for the whole seriea of years.
Table V.
Year.
Mean Drift.
No. SpoU.
Year.
Mmui Drift.
NaSp
1874
-7
22
1888
-90
10
1875
+ 40
17
1889
-34
10
1876
-28
8
1890
-3
6
1877
+ 11
7
1891
-2
57
1S78
+ 32
3
1892
-30
107
1S79
-18
2
1893
-19
'135
1880
+ 17
40
1S94
-24
118
1881
+ 18
52
1895
-40
94
1882
+ 27
68
1896
-39
49
1883
-4
83
1897
-39
44
18S4
+ 16
91
1898
-47
32
18S5
+ 2
79
1899
T-2I
14
1 886
-4
37
1900
-7
9
18S7
0
18
1901
+ 50
3
The unit of the table is o'-oi, and the drift tabulateii takes place
in 130^ of longitude. The tigure« have not yet been corrected for
eiTor of the Sun's axis, so that the results for years with few spots
are subject to sensible corrections, depending on the particular
months in which the spots were visible.
But the main feature of the table seems to be an oscillation
from a drift of about +20, or +33' per rotation, in 1880 to an
opposite drift of - 25, or -40' per rotation in about 1893.
Now one possible explanation of these figures is that the Sun's
axis is not stationary, but is describing a cone in space, in a perio-J
which may be one of several.
(a) If the period were about 26 years, the effect wouki be
reversed in 13 years, but it is easily seen that the angular radius
of the cone would have to be too large to fit the facts.
{/3) If the period were nearly a submultiple of a year, say six
months, Tables I. and II. would show it. Analysis does not
yield a suitable result.
(y) It seems most likely that the period is nearly a year. If
it were exactly a year, and we had adopted a wrong axis so a« to
get an apparent drift in latitude, the error and its effects would
travel round with the Earth, so that we should get a spurious
constant drift. If the period differs from a year, the spurious
drift would slowly change, going through a complete cycle in the
L.C.^I. of tlie period and the year. For instance, if the cycle is
about 26 ^eais>, \Xi^ ^etvA q.1 \3cv^ ^<ibble of the Sun's axis must
differ irom owe '^'e>a.x>a^ ^vs>a^»Vill*»\s>ssvvSi^.
June ipoS. Mr, Inncs, Magnitude of*) Argus, 1908, 613
(S) The drift may, however, be a pliysical drift on the surface
of the Hnn ; and we can distinguish between these rival hypotheses
by exHmintng spots which return after diaappearing. If the drift
is physical, it will persist on the Bide of the Sua remote from the
Earth ; if due to the rotation of the axis, it will be reversed on
the other aide. Since the amount per rotation ia large near a
maximum {say 40' per rotation), even a cursory examination
ahould settle the point. Carrington's observations show no
tendency to physical drift, as may easily be s^een from the results
130 to 213, or the table pp. 213-219, or the summary on p, 230.
2^ or doea an examination of the spot returnH tabulated by Father
Corte {AMon, Not., voL Ix.) give much support to the hypothesis
of a physical drift.
On the whole, hypothesis (y) seems best worthy of further
atudy.
But before deducing detrnitiTe elements for the axis, we await
the results deduced from the mea^iiires of C. H, F, Peters, and
recently published by Professor Frost. These are nearly com-
pleted, and can probably be given in the next number of tho
Month I tj Notk£s,
Magfntwtf of iq Arfjuti^ 1908. By R» T, A. Innes.
Comparison star used, Gilliss 1332 of 7*6 mag., yellowish or
reddish, 4 on Chandler^s colour-scale. This star is 8' N,pr.
17 Argus.
1908.
Mag.
Colon
Apr, 2
7'S
5
7
7"S
13
77
6
Jane 2
77
6
Mean 775 57
A low-power held, with both stars in view, on the 9-incE
refractort
Johannesburg :
190S Jum 3>
b
PhotomeMe MBemsTmienis of Neptune^ Januartj to ApiH 1 908. Bjr
J. M* Baldwin^ M.A., 1851 Exhibition Scholar (Melbottme).
ICtmmnnicaUd by Sir David QiU, K^C^.^ F.B.S,\
1. The observutioiis which are recorded in Uiis paper weiv
nndertaken chieEj to ascertain whether it were possible to recognise
a short'i^eriod variation in the brightaess of Xeptune such as that
which Maxwell lliill believed he had found in 1883 and a^^iain in
1884,
The first annoiincenieDt of a variation was made in the MontMf
Notices (xliv. 257, 1884). The observatiana made by Mr. Hall wew
sdimaiiQWft generally in fourths of a magnitude, of the diffepeoce
between Neptune and a star in the same fields assumed as of
magnitude 8-5 (B.D.+ 15", 453, mag. 8-5), On the night of 1S85
November 29 Neptune seemed to him fainter than on the two
preceding evenings, being •*aa nearly aa possible" of the ssmt
brightness as the comparison star, but later in the evening
Neptune 11 pp eared aomewhat the brighter. From then till
December 14 the estimated magnitude v,aried between 7*5 and
8*5^ but during the uight8 of December 15, 16, and 18 no Tariatico
could be observed. From his observations he deduced a period of
7^92 hours. On December 27 and again on 1884 January 8
Neptune was compared with another star (B.D. 15 \ 446, mag. y'f),
but "no variation was noticed on either nighty yet Neptunt^ vaa
undoubtedly i>righti>r on January 8 than on December 27*
{Ob»ermiorij, vii. 73, 1884).
He observed Neptune again at the next opposition, and in a
fihort note in the Observatort/ (viii» 26, 1885) says : *' Careful photo-
metric measures gave November 29*^ 9^ 44"^ G.M.T. as an epoch
of maximum brilliancy, but tfie variation waa only 0*4 magtiituds
between max, and min. The period of 7^*92 observed Ult
year has been fully confirmed." I have unfortunately be^n
utmble to hud any information as to the observations beyond that
contained in this brief pEiragrapli.
2. A considerable number of measuremmts of Neptune with
the meridian photometer have been made at Harvard OolJege
Observatory,* almost all by K C. Pickering, X Ursa& Minoris
* Observatori/, viLl34j 1884, and viii. ill, 1885 ; Harvard AmuUs, rm*
p. 265 and ilvi^, part li., p. 203. In this ]*|^eT the ri ' ni. 4 »»
nimiber, of NeptuDo with Utaiitis, made by Z^lhier Ufdtr-
^tt4:hanfjen, p. 150) and the S Harvard compariagns v.\.'^ . ;^... „., ta t9fi
[Harvard Aunah, xL p. 224) have not been mide use of.
June 1908. Flmtometric MeamremejUs of Nepimi^,
61S
being used as standard. The numlier of obserrations and results
obtaiued are given in Table I.
Table I.
Year.
Obwrvatioiift
NighU.
Mean ^&g,
Mean Error.
1SS2-83
11
1 1
77»
db^ii
1883^84
5
5
777
±•09
1884-85
9
9
7-63
±11
1894
5
5
771
±•13
1895-96
5
5
7-50
±*IO
1896
5
S
763
zfc'02
1897-98
16
10
7*63
±•10
3. The observatrons of Miiller* at PoUdara are more numerous.
These are rneamremejits with the Zollner phoftometer of the
difference in magnitude betvv^eeu Neptune and a suitable comparison
star or stars, the «ame throughout any one o[>position. The mean
results, fitc. for the separate years will l>e fouiid later on in this
paper (Table IV)* The mean of ali the 138 observations is
7*66 on the scale used in Band viii, ; this is exactly the name as
the mean of Pickering^a 56 observations between iS8s aod iSgS.
4. In the observations given below, a Zollner photometer
attached to the Steinhf^il refractor (13*5 cm. aperture and 216 cm*
focal length, called photometer D in the Potsdam Publications)
was used throughout. Two comparison stam were chosen near
Neptune, namely R.D. -h 34 ^ 1457 and +22'', 1531, the magnitudes
given in the Potsdam General Catalogue being respectively 7*97
mnd 7*1 8. As usual, four readiugs were taken for each object, one
in e^ch i|uadrant of the intensity circle (whicli was always turned
in the same sense), the star being rei^pectively to the left of, above,
to the right of, below, the artificial star. The complete observa-
tion consisted in observing first one comparison star, then
Neptune, then the other comparison star. For the next observa-
tion the stars were taken in the reverse order, and so on through-
out the whole series. The complete results are given in Table 11.
* A,N., 2600, Bd. cix. 121, 1S84, or Ohsermtoty, vii. 2^, 1884 ; PoU, Pu^t,,
BfL viii. It ia to be noticed that tlie magDitudea aa givi^i) in the J,N, are not
referred to the same scale oa those in tho collected results in th« Pots, PtibU
[Table
6i6
Mr. J. M. BaUhinn,
LZYin.8.
Table XL
1006.
Jan.
G.M.T.
d h m
25 6 8
Z.D.
M,.
7-85
7.98
Mean.
792
Badao-
ttoo.
+ •01
Mo.
7 93
FhaM.
0-68
dial
-■06
7 6
43-5
8-00
7-93
7-97
7-98
-•01
9 46
30 '4
8 -02
7-85
7-94
7^5
-•04
Feb.
3
10 12
32*5
8-04
789
7-96
7*97
0-98
-•02
11 3
37-1
7-8o
7-93
7-86
+ ^)I
7-87
-•12
Feb.
9
II 18
41-9
7-96
7-96
796
•00
796
115
-•03
10
7 24
34*0
7*93
7-91
792
792
I-I7
-X7
8 5
31-3
7-88
8-OI
7 95
7-95
-•04
9 43
32-5
7-97
7*99
7-98
7-98
-101
14
7 22
329
7 93
8'o6
7 99
00
799
127
•00
Feb.
19
842
30-5
8-04
804
-•01
8-03
1-38
+ •0*
Mar.
2
9 52
41-9
8*10
8-II
8-1 1
-■02
809
1*3
+ 'I0
10 44
49-3
817
8-13
8-15
813
+•14
II 10
53 1
8-o6
8*02
8-04
-•02
8-02
+•03
16
9 7
43*4
S-23
8-12
817
-•03
8-14
I -82
+ -IS
Mar.
16
9 19
45*2
7-91
8-00
7-95
-•03
7*92
-•07
22
9 21
487
8-01
8x7
8-04
-04
8 -GO
1-87
+ *CI
9 55
537
8-oS
8-09
8 -08
8-04
+ 05
24 9 47
537
8-14
7*99
8-o6
802
189
-r-05
10 16
58-1
8-07
8-07
8-07
8-03
+ •04
Mar.
24
10 47
628
7 '99
8*04
8-01
7 '97
- -ci
25
9 2
47 7
8*01
8*02
8-01
7 '97
-•02
lu 25
(jO'I
8-05
7-98
8-OI
•
7 '97
- 102
10 48
63-6
8-09
8 -06
8-07
-•04
8-03
189
■r-a4
26
9 0
48-0
8 '02
8 '02
8 -02
-05
7*97
I 90
-•02
Mar.
, 26
10 21
tK)-I
7 94
8-03
7 99
7*94
-05
10 46
642
8 00
8-10
8-05
S-oo
-rOl
27
i^ 31
44-5
7 95
8-03
7 99
7*94
-•05
9 19
51-3
8-09
8-07
80S
-•05
8-03
1-90
-•04
Apr.
26
S 2S
613
8-22
8-o6
8-14
-•oS
S-o6
176
+ 'o:
A).r.
2S
7 3')
54-9
7-98
S'oo
7-99
791
174
-•Ob
S 19
01 0
8-15
8-07
8-II
-•08
8-03
-•04
Mean
7-990
Jan. 25. Slightly l<'ggy.
Feb. 14. ll.izy, but iio'clouds visible in bright moonlight.
Fob. 19. Cb'udfd over, weight ^.
M;ir. 2. Not very clear, liazy near horizon.
Mar. 16. Sky bad' and kd observations not reliable, weight 4.
Apr. 26. Cloud slowly n.-ring, but observations probably good.
±■059
June 1908. Photometric Mea^uTermnts of Neptune,
6iy
In this table the first two columns give the date aud G.M.T.
of observation, and the corresponding zenith distance of Neptunej
the next eolimms the observed niagnitodes (corrected for
atmospheric absorption) referrtid to the brighter and fainter
compariaoD stars respectively, and the mean* Each (observation
gave the difference in magnitude between the comparison stars;
from the whole series the mean was 0*83 mag., and bo the values
for the comparison stars are taken as 7*16 and 7*99 respectively.
In the sixth and aevorith columivs are given the correction to mean
opposition and the magnitude in mean opposition. The eighth
column gives the phase angle ; this remainn always so small that
it is not to be expected that any variation of magnitude with
phase angle can be recogoised with certainty. The last column
gives the difference, observed mag. - mean magnitude,
A glance at the column of residuals shows that the agreement
between the observations is extremely satisfactory, the mean error
of one obeervatioTi, giving a weight ^ to certain obeervations as
indicated, being only ± '059 mag.
5. Amongst the foregoing material there ai*© three series of
observations which are especially auited to detect a short period
variation in brightness such as that announced by Hall, the epoch
and amplitiide of which, owing to movement of the markings sup-
posed to give rise to the variation, may be gradually changing.
(i) Miilkr's 72 observations on 37 evenings between 1884 Aug.
24 and 1885 March lo.
(s) Pickering's 16 obaorvations on 10 evenings between 1897
Dec, 1 1 and 1 89S March 3.
(3) The above 32 observations on 15 evenings*
If these observations he exanilned it will be at once evident that
they show no trace of a short-period variation, the residuals being
just such as occur in pbotoraotric work, However, as a direct test,
the series have been iaken separately, the phase computed for a
period 7*92 hours and an arhitrary epoch, and the light curve
plotted. In the citso of Miiller'a longer series, this has been done
also for parts of the series. The result is in every case the same;
the observations furnish no evidence whatever of a variation of
period 7*92 hours. In particular, MfiJler a observations from 1885
Jan. 8 to Feb. 24 and those given in this paper are ebf»ecially
conclusive on this puint, as the observations are well distributed over
the curve. With regard to his observations from 1884 Aug. 24 to
1885 March 10, Midler says {Pots, PubL, viii, p. 352), "during the
whole period nf nearly 7 months not the slightest trace of a [leriodic
variation in light can he recognised. The magnitude in mean
opposition varies between 7'39 and 7 '8 1 , and such a difference can
be very well explained by uncertainty in the measurements if the
fact that these extreme values were obtained when the planet was
very low, and under unfavourable conditiims, be taken into account '* ;
and a little further on, **the observations of the following years
also, although not nearly so numerous^ are in direct opposition to
the hypothesis of a periodic variation in the Vv^t. lto\s\^t\X.\vEi&r
6i8
Mr. */. Jf. Baldwin^
LXvnL 8.
This latter remark may be extended to the whole of the photo-
metric observations of Neptune,
6. Looking now at the evidence which HaU gave as ahowin^
a periodic variation of brightness, it consists of —
(i) A senes of 25 esLimations of difference of magnitude.
(2) Some photometric observationB, of which particuiats are not
available.
If tiie first set of observations be plotted to ubtain the hghl
curve, it will be found that the assumption of variation practically
rests on 3 observations, for, apart from these, no residuaJ occurs
which could not be explained by the method of observing, the
greatest being 0*3 mag. from a mean 7*8. Of rhese three, two tn
the early obeervationa of Nov. 29 (mag. 8^5) and Dec. i (mag. Sji
and it waa not until after the first obeervation that a diagoou
prism was used to alter the relative positions of Neptune and the
comparison star; and the third, on Dec. 7 (mag. 8-3), requires ia
any case a correction of more than - 0-4 to bring it on to a cun^
through the other ob^^ervations.
From the second set a x^ariation of 0*4 mag., occurring aboat
1 88 s ^^'^* 29* ^^ deduced. In the absence of details it is
impossible to say what instrument was used, how many observations
were raaiie, or over what period they extend. Against the hypo-
thesis of variation, however, there is very conclusive evidence m
MiilJer's observations before and after this epoch, for there ar»*
continuous observations from Oct. 23 to Nov. 19, and again from J&o.
8 to Feb. 24, which efTectively include any assumption of varid^
tion during these periods, and observations ou Dec. i, 2, and 16,
which ^nve no evidence in favour of it.
It would a|>pear, then, in the highest degree probable thai the
"variation" announced is due to errors of observation, eepeditly
when account is Uiken of the small amplitude deduced.
7. The mean value of the brightness of Neptune in mean
opposition, as determined by the present series of obaervatioas, »
7*99i the mean error of one obr*ervation being ±'059, the system
to which the magnitude is referred being that of the Putfdaui
Ourchimmie ru7ig.
The coin[>ariann stars used by Miiller, the magnitude on the
system of bis Potsdiim planetary observations, and the magnitude
from the Potsdam Genonil Catalogue are given in Table ILL
htar
43
54
49
S6*
B.a
+ 13'. 41 '
+ IS'. 430
- 4^4376
+ l6^4S8
+ i6%43i
Tablr III.
Mag
7*25
6 29
541
695
7-96
7*52
6*68
5 '54
S-aj
+ •39
^*27
SI
* iMng ton oloricftl error, this oom()aridon star h&B hten printed
instead of 56 throiij^rhaat the observfttions of Kentune, and the diaouaioa W
the result o( lhe«6 ItL ^q\. xlvv. i^C tUe PotmUim Puhlicatimu^ Beyond ipntiug ^
for 55 no change tct^t^aV^'^^^^ft*
Jiine 1 90S, Photomdri^ MeamiremerUs of Ni^iwne,
Stars 34 and 56 are not contained in tbe General Catalogue,
but from Pots. PuU,^ Band viii. p. 253,
34-/3 Hercalis is 2-53 mag,
nnd 56 - fT Arietia is 2*51 inag«
Also from the General Catalogue,
j8 Herculia i« j*oi mag.
and (T Arietis is 573 mag.j
and bence the magnitudes given in Tahle Til are obtained.
Next» combining these results with the table given on j>. 354 of
M tiller's paper we get Table IV*
Table IV
Yew.
2raiiit»«r
of
Obiervft-
tlon.
MBg,
Frob. error of one
Ohierviitlan.
€omp«r!«on
Baduotlon.
K«duced
Mniml.
tude.
187S
U
770
±0-051
5^
+ •27
7*97
i88r-2
17
775
•071
52
+ ^27
S'oa
1883
6
775
•095
43
+ 19
8*14
1883
7
770
•085
34
+ 13
7-83
1884-5
72
7-62
-056
49 and 56
+ 33
795
1885-6
»5
7-69
'074
49 and 56
+ *33
8*oa
1886-7
7
7 -61
045
49 and 56
+ *33
7 '95
The mean magnitude on the system of the Potsdam JJurch-
mmierung is thus 7*97.
For the comparison with Pickering's observations^ the? difference
Potsdam - Pickering is given on p. 34, of the introduction to the
Potsdam Greneral Catalogue, as follows : —
Magnltade,
w
ow
7'50'7'99
+036
+ 0'29
8 -00-8 '49
io*37
4-0*30
If tbe colour of Neptune be assumed as between W and GW
the reduction +034 cannot be far from the truth, and this gives
8*00 as tbe reiiuced value of PJckerlng's mean result.
It is seen, then, that the results of tbe present series are in very
close agreement with the previous observations of M tiller and
Pickering,
8* The results arrived at from the present series of obgervationa
in conjunction with previous observations of Neptune may be
summarised as follows : —
(t) The variations of tbe estimated brightness of Neptune
announced by Hall are probably due to errtrs of observation, as
the measurements of other observers about the same time^ «k.ud ^W
620 CapL jB* a. C. Daunt, OlmrvtUioTis of helium ucvilU
at other oppo«ition8, giTe not the alighteat trace of any such varintioa
Consequently the time of rotation of 7*92 hours lieilaced by him
must be regarded as mjsup[>ortod by observation.
(2) The observed magnitude of Keptiine in mean oppoaition b
7 '99 on the system of ilie Pot^am Durchmuiierutfii, showing, tn
extremely satisfactory agreement with Muller's Vitlae 7*97, iir»d
Pickering 8 value S'oo*
In conclusion, I wish to record my thanks to Profeasor MiifJfr,
at w^hose BUggestiou these observations were made, for Uie iDtarsit
which he has shown throughout this work*
Adropkytical Obftervaioryt PoUd^m
1 90S JUM 6»
Observations of helium D^ absorption in the neighbourhood
Sun-spots in 1907* By Captain R. A, C. Daunt, D.S.O-
The foU owing observations of Dj absorption in the neighbour-
hood of sun-spots were made with a 3-incb equatorial refractor tad
a large Thorp, prism-grating spectroscope, 1 5|00o lines to the inch,
the eyepiece ordinarily employed being a Stein heil monocentrtc
20 m/m power 52, The identification of the aeveral groups
according to the Greenwich numeration will, it is hoped, be of
service for comparison with apectro-heliographic and cognite
studies of the same groups. Tn Table I. the numbers of the
various groups and the dates on which they were observed are
given, as well aa the type or phase in the life-history of the ^00 pf
at the time» of observatitiii^ acconiing to the classification of K
Cortio in his paper "On the Types of Sun-apot DisturbiiiL^
Astrnphysical Jounuiti xiii., 4tli May 1901.
In all the cases of iibeorptfon of D^ observed, the dArk line vfu
never seen over the umbrse or pen umbrae of the spots of any groufi.
but between thf* »pr>ts, or on the photosphere in their Deigfaboor*
hood» It would appear that some of thei^e groups showed D, in
absorption on certain days only, and not on others. This niaj be
real ; but as the appearance of Dg is very intermittent, it is more
likely to be due to the hour of observation ; and had I been able to
keep the groups under observation throughout the day, D^ woulJ
probably have been seen near the spots some time or other of the
day during the app^^irition, provided the groups remained actire
and agitated.
In Table II. are given the Qreenwioh numbers of those group
ill the neighbourhood of which D^ was not observed. For
leasou stated above, some of these groups may have shown
absorption effect of D, at some time, but it was nut obserrad* -
As^ however^ most of these spots were aniall, or of a regular t
quiescent nature, it is perhaps unlikely tlmt l>.^ was reversed.
A table follows showing the proportion ot the total numto d
freah gtoui^ Okbis^r?^ ^^^^ vc^<.mth with those that showed D^
m
June 1908. D^ absorption in neighbour?iood of Stm-spoU. 62 1
There would appear to be a discrepancy here, and the proportions as
shown by the Greenwich numbers appear to be higher. This is due
to a different system of numbering. For instance, the group con-
sisting of the Greenwich Nos. 6075, 6076, 6081, 6085 has for the
purposes of the table been counted as one group. This is, I think,
under the circumstances, more accurate, as by the Greenwich numbers
it would appear that four different groups showed D3 in absorption,
whereas these spots were obviously part of one disturbance, and
should only be counted as one disturbance for this purpose.
Tablk I.
Oroup in xohick D^ vxm observed as a dark line.
Ore«nwlch
No. of Dates of Observation.
Qroup.
1907
6059 Jail. 2, 3
Type of the Group.
• 66
» 3
IV
67
M 3
III
70
„ 3
I
75^
• 76
81
M 16
Illft
8sJ
94
„ 24
Illa
6099
„ 30, Feb. 4
iii„, m
6100
M 30. M
Illa.IVft
• 03
Feb. 4,5
III, IV5
04
„ 4, 5. II
I, IIU, III„
♦ 08
„ 9, 11, 13, 16, 17
V, IIIa,IIIa,V,V
• 36
Mar. 3.4
IV6, IVa
37
>. 4
III
39
» 5.6
IVft, IVft.IVa
• 40
» 5» 6, 14, 17
IV6,IV„
SO
„ 22
I
55
» 23
IV,
• 56
,. 30
I
58
Apr. 4
III. IV
59
Mar. 3«» Apr. 2, 4,9
IV, Ilia, III«,IV,.
68
Apr. 15, 16, 17
I. I, 11
72
„ 21, 23, 29
Ill.IVft.IVa
75
,. 26, 27
1,1
81
May 4.5,6
III, III, IVa
• 84
„ 4, 5. 6, 14
IV., IV., IV,, IV.
6185
>• 13, »4
Ilia, III
622 Capt. B. A. 0. Dauni, Observations o/hslium muL 8
Table L^-cimUnued.
No. of
Chroap.
DtttMOfObwrnOion.
TmoCftfaaORMp.
6187
1907
May 14. 16, 17
I, lie, in
6188
»f
14, 16
III, II
6230
Aug.
5
I
31
*l
5
I
36
It
18, 23, 24
III,IV»,IV»
• 38
11
24
IVa
39
»•
23
IVft
• 41
>»
30, Sept. 6
III«, III.
43
Sept
. 6
m
45
i>
'»»
I
47
tt
1*
m
55
f»
20, 21
1,1
56
n
22
IVa
59
n
20, 21, 22. 25.
26.
27,29
III5 IIU
60
»»
20, 21, 22, 26
IV«,IVd,IVrf,IVa
62
Sept
. 20, 21
IVa.IVe,
65
n
25, 26, 27, 29
Ilia ... . Illa
68
n
27,29
I.IVo
70
»»
29
I
75
Oct
9
I
76
»»
9, I3» H. 16
I, III .... IIU
77
i»
9. 13, 14, 16
I, Ilia .... nil
78
ti
I3» U
IIIa,III«
79
))
9. 14, 16
I, IV., IV;,
81
M
14, 16
IVclVft
82
11
14, 16, 19, 23,
24
IVe,,IV„IVb,IV,.IV,
* 83
if
14. 16, 19, 23,
24,
26, 27
Illa .... IV,, IV,
• 84
a
16, 19, 23, 24,
26,
27
IIL .... IV., IV,
85
M
19, 23, 24, 26,
27
Ilia .... IV,. IV.
* 89
,,
23, 26, 27, Nov. I
IV„,IVft,IVh, I
91
Nov.
. I
II.
6292
t%
t>
I
•6316
Dec.
2,3
IVft.IVft
18
i>
6, 7. 9
IV„,IV.,,IVa
* 19
»>
6, 7, 9, 12, 14
IVl V
20
f>
9
III
* 21
f>
9, 12
IV6,II.,
23
»»
14, 18
I.IIr
6324
ti
v^
IV
June 1908, 2?3 absorption in fieighbmirhood of Sun-spots. 623
An asterisk denotes that the group so marked was the return of a
former group. The appearance of the absorption-line in the cases
observed waa lumpy ^ patnby, broken, and thickened, aometimes
distorted towards the violet, as in groups 6259, 65^ 68, and once,
in groups 6283, 84, distorted towards the red. Group 6137, March
4th, 10*30 G.M.T., furnished the most remarkable ap|jearaiiees of D^
absorption observed since those of the big spot of July 1906. The
appearance of dark D^ as a fine continuous dark line has not been
recorded.
In every case of obsorvation of reversal of D^ the C line of
hydrogen was sympathetically affected, being twisted and lumpy,
distorted towards the red and the violet, accompanied by brilliant
reversals, sometimes over considerable areas in the neighbourhood
of spots, as ill the groups 62^^, 84J 85, Oct. 21, when, too, the
sodium lines Dj and D., were reverserL
Magnificent reversals were seen in group 6E03, Feb. 5th, when
a large prominence arising amongst scattered spots could be traced
across the disc and out beyond the limb. In group 6188 the line
was thick, with black lumps and bright reversals in the faculBD
snrroundiog the group, and in group 6247 violently disturbed,
greatly distorted to the red and violet, and veiy lumpy, with
briUtant reversals.
Tjlble IL
si of Sp0t'^roup$ in
t^hich the i?3 line inas
not ob»
Ordoijmich No.
Type.
Greeuwlch Ko,
Typ&.
6061
•61 E 3
IV, I
6z
• 15
1
6g
* 17
IV
* 74
18
III
77
IV.
»9
I
79
20
I
♦ 86
2t
I
• 87
IV^. I
* 23
IV
88
IV.
27
IV, 1
* 90
IV
28
I
93
29
I, III
97
31
I
•6098
IV, I
33
I
6101
IV, I
34
IV
02
35
1
• OS
38
I
C7
IVa
4S
I
09
46
I
11
52
1
•6112
•6153
\
'^4 OirLAA.G.l)amiiU,abmritatimi$^MIhtm VOmik
Tabls IL— «MiMmMi.
£ddi(f8poi'gmipti»wkMOmDgfki$t
Mf
MrdtamMil.
,
Qf6eii#iidi No.
T^pe.
GNiBVidlllllK
^tn^
•6154
•6246
... r- *■
♦ 61
IV
4^
6a
IV, I
6t
65
63
IV, I
7®
64
¥ * ' *
74
• 67
^6189
'
IV
69
I' ■ V ;
6230
IV
V
IV
23
72
I
25
,
•
• 73
IV
26
IV
• So
IV '
27
*6288
I
29
6317
32
IV
18
34
IV
22
37
25
6240
Table
6326
III.
Shmmng the propori
ion of Spot-groups which showed D, revtned.
lonth.
No. of Days Total No. of Xo. of Group tn ,
of Observation. Groups observed, which D, Dark. Percentactt.
Jan.
7
21
7
33*3
Feb.
9
18
3
167
Mar.
17
21
7
33*3
Apr.
12
«3
4
30-8
May
7
6
5
83-3
July
I
4
0
—
Aug.
5
14
6
42-9
Sept.
8
17
9
52-9
Oct.
II
18
7
38-9
Nov.
I
I
I
—
Dec.
9
II
5
43-6
Totals
87
144
-
54
Percentage on the Totsb
37'5
Co. Doiim, Irelaivd.
June 1908. /?jj ahsorpiion in mhjhhonthood 0/ Suit'Siwts. 625
[Note Oflded by Fathei* Vortie, '*^^*^-]
111 the above taMes 1 am res|)0iJ8ible for the coin runs h«aded
*'Type of thy (iroup/' using for the infi^riiisitiun therein contained,
with the kind penniHi?ion of Captain Danut, the materials in h\»
observing note- book, tlie Stony hurst fiun-sput drawings, and the
useful monthly ** Tables and Notes on Sun-jj^pots" cninpiled by
Mr Maunder for the Ol/serraionj. The object of tbeae coluiiins
ia to ascertain whether the phenofncnon of D^ absorption is
confined to, or gem^rally favours, any purtkular phase in the
life-history of sun-spot groups. The more active pjiases of sun*
spot development are represented by Type IL and Type IIL, and
39' 7 per cent, of the groups in whiL'h U^ was obBerved as a dark
line were of these types. In the lifv^-histories of spot-groups it is
generally the following ]mrt of the group which disappears first,
leaving a single spot, with accompanying small companions. This
phas*^, repre.'^eutcil by Type IV. with variovis suHixes^ is also
largely represented in Table L; and in his notes on the D^
reversals^ Captain Daunt freipiently records that the absorption
was observed between the two main spots of a gi"0up of Type IL
or Type IIL form, or in regions following the main spot, that ia,
in the earlier phases of Type IV, Therefore it folhiw^s that in
general the phenomenou i-i indicative of violent local action in
the earlier phases of the life- history of groups. However^ it is
not entirely confined to these phases, an it is recorded in groups
6256 and 6318, examines of round steady spots. But even in
these cases, 6256 had a divided nucleus and showed signs of
disruptive change, and group 6319 in the neighbourhood of
group 63 1 S was disturbed. The table giving the groups in which
D3 was not observed shows that the spots were in the last stages
of their life history, being in most cases either round steady spots
or scattered remnants of groups. But here again there are ex-
ceptions, as group 6118 was being developed, and group 6129
|>a8sed through an active stage, though on a small scale,
SUmyhuritt College (JhsenviKfry,
AiS
626 Dr, Max Wolf^ Lengths of Axes and LXVm. 8,
Lengths of Axes and Position Angles of 52 Oral NelmUe,
By Dr. Mwc Wolf.
Professor Turner has suggested the questiou whether there is
a relation between the apparent form and the sitaatiou of o?al
nebulse of the type of the Andromeda nebula, viz. Is the ratio of
the two axes of the ellipse, visible to us in projection, connected by
some rule with the position angle of the mijor axis f
I have made a first trial with the oval nebulse of my last
catalogue,* putting these together in the following list. The
lengths of the two «xes a and h are estimated on the plates by a
scale in the eye-piece of my microscope ; the position angles are
estimated with the aid of a cardboard circle at the same.
The visible dimensions of such diffused objects depend in a
high degree upon the exposure, the darkness of the plate, the
illumination, and the position on the plate, so that the lengths of
the axes are affected with some uncertainty. Notwithstanding,
there is no doubt that some simple rule, if it exists, must be
perceivable from these numbers.
The distribution of the position angles themselves has a
maximum at about 30", and a second fainter at about 160*,
Ksst. Littc
8.
Xo.
N.G.C.
No.
a 1875.
h m 8
X.P.D. 1875.
F08. Angle.
a
b
Ill
3935
II 45 55*2
56 54 0
1 10
45
20
130
new
47 13*9
56 32 0
40
20
15
132
47 15-6
60 3 3
105
45
20
138
47 22-5
55 56 12
130
60
30
154
47 497
56 26 35
160
45
12
173
45J 51 -5
56 9 34
160
20
6
177
48 57 -2
56 10 38
80
20
S
193
49 19*4
59 21 47
40
60
»5
213
49 537
57 52 5^
10
60
^5
216
49 562
57 15 55
135
45
15
232
39S6
50 17-2
57 17 0
IOC
100
20
255
new
51 21
58 13 6
165
30
12
257
>>
51 3-8
56 58 12
30
45
10
258
3991
51 5*2
56 57 55
»5
15
10
263
3994
51 IO-3
57 I 40
10
30
15
271
3995
51 17-2
57 0 37
(O30
90
30
303
4020
52 30-8
58 53 23
15
80
20
3i«
new
52 47 1
58 34 15
140
30
15
346
»•
53 42 -6
56 10 0
35
30
12
352
,,
" 53 507
58 4 44
45
40
15
Ki)i\ig»t.\Ovl Neb«X-L\?At'^^. '^^'^x&X, \\v.
June 1908. Position Angles of $2 Oval Nehdce,
627
Kgst. Litte
8.
No.
380
N.O.C.
No.
new
a 1875.
h m 8
11 54 39-0
N.P.D. 1875.
58 27 28
Pos. Angle.
60
a
30
6
20
391
ft
54 525
58 I 28
35
30
6
444
,,
55 465
58 21 II
' 15
20
6
452
>i
55 581
59 26 30
70
75
15
455
»>
56 1-2
59 50 6
60
45
20
483
>>
56 57-4
59 53 I
55
90
20
498
}>
57 25-8
59 35 23
150
60
15
502
M
57 32-6
58 II 44
10
45
IS
510
4062
57 40-2
57 24 25
100
180
60
529
new
58 IO-4
58 36 47
30
30
8
541
i»
58 21-9
58 841
160
20
12
545 .
>i
58 24-4
56 48 29
5
45
8
548
i(
58 26-4
57 2 30
30
45
(?)5
582
,,
59 26-2
59 14 18
60
30
15
584
))
59 281
58 15 27
170
20
8
593
M
59 34*9
57 57 22
45
22
7
607
>>
II 59 44-9
56 24 27
120
30
12
680
))
12 0 45 "O
58 14 36
30
30
15
682
>>
0 46-4
56 18 28
70
40
15
699
II
I 124
56 28 13
no
30
6
7"
?4I22
I 39-8
56 21 53
160
20
12
715
uew
I 46-3
55 47 52
5
30
IS
719
II
I 58 -2
56 42 39
175
30
12
725
»i
2 21-3
55 40 27
40
30
15
726
i»
2 21-8
57 7 59
80
30
15
737
4132
2 39*6
60 3 4
30
45
20
740
uew
2 44'4
54 59 56
175
30
12
741
4134
2 47-8
60 7 39
150
90
45
743
uew
2 50 '4
58 23 47
25
75
20
764
4150
4 12-8
5854 8
150
90
45
769
new
4 57*2
56 42 35
65
45
30
770
>»
12 5 44'4
56 34 10
150
45
30
Astrophya. Ohso'va^orn, KanigstitJU,
1900 Jul If 2.
Heidelberg,
[By the courtesy of the secretaries, the above very interesting
measures have been included in the present number, but there
was not time to prepare any discussion of them. A. N«t^ tq>\<^
628
ErrcUunu
lxtiilS.
preliminary analysis indicates that the measures lend some sappoii
to the hypothesis of a systematic orientation of axes parallel to
the Galaxy (see M,N,^ Ixvii. p. 333 and p. 498), but a complete
discussion must be deferred. — H. H. Turnxr.]
Erratum.
In Monthly Notices, vol. Ixvii. p. 321 (Baxendell's Obserri-
tions of U Geminorum),
for 1858 Nov. 14 read 1858 Nov. 15 (as on p. 324).
MONTHLY NOTICES
OF THK
ROYAL ASTRONOMICAL SOCIETY.
Vol. LXVIII. Supplementaky Number.
No. 9
On the Parallax and Proper Motion of the Double Star Krueger 60
(Bumham, Gen. Cat., 11 761). By E. E. Barnard. (Plate 14.)
TJie Huitory of Krueger 60.
Professor Krueger, in his catalogue of the Astronomische
(Jesellschaft, covering the zone +55' to +65*', noted with the
meridian instrument many stars which were double. He made a
rough estimate of the quadrant and distances of these stars and of
their magnitudes.
In 1890 Professor Burnham measured 67 stars from Krueger's
list with the 1 2-inch and 36-inch telescopes of the Lick Observatory
{Pub, L,0,, vol. ii.). The star No. 60 was among those measured.
Krueger's note on this object is : —
"Dupl. 12" pr. com. 9*3."
In measuring the principal star, Professor Burnham found that
it was a wide and unequal double.
1890788 Pos. 178-8 Dist. 2"32 (i n) 9*0- 12 AB
56-3 26-82 (in) 9*2 AC
Of these A C is the Krueger pair.
No other measures were made of these stars until 1898, when
Dr. Eric Doolittle remeasured them with the 18-inch Brashear
telescope of the Flower Observatory {A.J., vol. xxi. y, 4t'\\»
630 Prof, E. E. Barnard, Parallax and Proper LXTIIL9,
DoolitUe's measures showed that the pair AB had a strong proper
motion (o''93 in the direction 247^*9). ^^ measures ;
1898*446
140*66
5871
3"i9
34'39
91 - 105
94
AB
AC
h»
Subsequent measures fally confinned these results.
In il.y., vol. xxi. p. 64, 1 have given measures of these stars which
are in accord with the motion derived by Doolittle. (Id the
Krueger 60. 1903*6.
c
20' 40*
I ■ I
North.
Fig. I.
measures of A B in that paper there is a misprint of 2 ''•2 3 for
3''-23.) In A.J.^ vol. xxiii.* pp. 169-172, I have given more
observations, with a diagram showing the probable orbital motion
of A B. A few years' measures soon showed that this was really a
physical pair in rather rapid orbital motion. I also called attention
to the probable proximity of these stars to our solar system.
Acting on this last idea, 1 began in 1900 a series of measures, with
the 40-inch telescope, of A and C for the parallax of A.
• On p. 171 in that paper, the motion in right ascension should be - o*'io7
instead of- i»'*6o6, and on p. 172 the seconds in the ri^ht ascension should
be 328-00 instead of 328-69. In that paper I derived the proper motion
o"'9$i in tbe dueeViotv i^^jj'-j,.
5iipp, 1908* Motion 0/ the Double Star Kme^er 60.
631
In the Astrophysicid Journal ^ vol. xx. p. 128, for Sept. 1904,
Dr. Schleijinger published: hk results of the parallax of A derived
from pbotographs made with the 40-inch telescope- Dr. Sehlesinger
ifoimd a parallax of about J**, verifying the prediction of its nearneas
[to us, I will give, later on, his final value« for the parallax.
Additiorittl measures are given by Frofeaaor Burnham in
^PufdkaHom of the Terhes Obiervafarr/, vol ii,» 1903, p* 67.
This \9 britjfly the history of this remarkable stellar system.
In Jfay of 1 903 I measured the position of A with respect to
Hebingfors-Gotha A.G.C. 131 77- From the measures the place
of A is
i903'oa= 22^ 24*" 32''"09
Proper motion - o^'ioy - 0**382.
The star is Helaingfora-Gotha A.O.C. 131 70.
Deiermination 0/ the Parallax of A.
The |>refieut paper gives an investigation of the parallax of
the star A from the visual micrometer measures made, with the
40'inch telescope.
The micrometer screiv and the tube of the 40- inch are both of
steel, I have found from about ten years' experimental measures
in til e Pleiades (which are soon to be published) that the focun of
the 40'inch glass shortens from summer tu winter by an extreme
change of } inch. In the meaiititjie the steel tulje shortens i inch.
The temperature change in the micrometer Bcrew will correct .1 inch
of the total change of the focus of the objectglass. There remains
r uncorrected, therefore, J inch of the extreme focal change, The
I ex act amount of thii uncorrected chsm^e, from the measures of the
r^leiades referred to above, is 00032 inch (ooSi mm.) for each
[degree of temperature. This would cause an extreme enor in the
[measures of Kruegcr 60 for temperature of nut quite o"*or» and in
'the main it would not be appreciable. 1 have, therefore, not
thought it necessary to correct the observations for toujperature
changes. I have not felt sure that the correction would be
real The corrections for ahermtion, being insensible, have been
_ omitted.
All of the calculations for the parallax of this star were madci
mder my supervision, by my niece, Jfiss Mary Ross Calvert,
[who, through the courtesy of Mr. Andrew Carnegie, is at present
my assistant. They have been carefully checked throughout, and
seem to be free from errors. The observations, corrected for
refraction, were first freed from proper motion. The parallax
factors were then computed by BesseFs formulae, as given in
Chanveuety vol. i. p. 695, fifth edition, where the parallax factor is
Km cos (0 - M),
632 Prof. K £. Barnard, FaraUax and Proper LXYm.9,
in which R and © are the distance and longitade of the 81m; m
and M being derived from the formnkB
fn cos M » sin a Bin P + cos a sin S cos P
m sin M s ( ~ cos a sin P + sin a sin 8 cos P) COB 00 — cos 8 cob P sin «*
where P is the position^angle of the stars, a and 8 the
ascension and declination, and co the obliquity of the ecliptic
The formula
n + aar+ by +cp = o
was used for the equations of condition. In all, 'there were seventy-
six equations of condition. From these the normal equations wen
derived in the usual manner. The normal equations were solved
by the ordinary methods of elimination. As a check, they wen
also solved by Chauvenet's "second method, of computing the
weights of unknown quantities " (Chauvenet, vol ii., art. 35, p. 516),
from which the weights were also derived. From these last, the
probable errors were computed by the formulsB.
Probable error of parallax
P
where top is the weight of the parallax and
P=±o
w^,-
V being the residuals derived by substituting the known values of
Xy y, and p in the equations of condition. Similarly for the
probable errors of x and y, using for them the same value of P.
This method of determining the probable errors Avas kindly
communicated to me by Dr. Schle^inger.
The proper motion used in these calculations was derived by me
from a comparison with Professor Burnham's measures of AC
in 1890 and my measures in the last of 1905. This value was
o'''968 in the direction 246*'49.
The corrections for motion, to the observed distances, were
computed by the formulaB given on page 696, vol. i., of Chauveuet's
Theoretical and Practical Astronomy,
In Table I. are given the observations and their reduction to
T 90 1*0, the last column being the residuals from the mean of the
corrected distances. Table II. contains the equations of condition.
* We have found tbat this lust term is incorrectly given in Bessel's
original paper, A.N. 366, pp. 83-84, as -sin » cos P sin ».
The same error occurs in the second of the formuls for determining the
parallax froiu thevoavtvou-angle on the same page of A.N. , 366, the last term
of which ahouVd a\w> \» - c^c»^^ ^«&^ ^* •«
F
633 ^^B
Supp. 1908. Motmn of the Double Star Krueger 60,
^^^
Table I,
^H
^^^H
Medwii
lions to I90i'o.
^^1
^^^
Foft-Ang.
Dltt,
Corn (or
motion.
1901*0.
Reaid . trnm ^^|
, 1900-937
Dec. 8
59'27
36-88
+ 0*06 1
36-941
^1
B '940
9
59^5^
36-67
40-058
36728
^^1
H -945
II
5925
36-69
+ 0-053
36-743
^H
W '^
12
59-16
36-66
+ 0*050
36710
^^1
I90I729
Sept. 23
59-65
37*18
-0700
36-480
^H
^ 73.
24
59*84
37*20
- 0702
36^98
^^1
■
30
59-86
37 "30
-0719
36-581
-0063 ^^1
H
Oct. I
59-52
37-JS
-0722
36-428
+0-090 ^H
■
13
59*63
37*43
'O752
36-678
-0-160 ^H
■ -805
21
59-48
37*36
-0774
36-586
-0-068 ^1
~ -827
29
59'49
37 ■34
-079s
36-545
^^1
LJ902744
Sept. 29
5964
3S-29
-1-676
36*614
-Q-096 ^H
■1
Oct. 6
59*69
38-10
-1*695
36*405
^H
■ 766
7
5964
38*32
-1*697
36623
^^^H
" 786
14
59-60
3850
- 1-716
36784
- 0-266 ^^H
1903*380
May 19
59*55
38^61
- 2*287
36*323
+0-195 ^1
^ 196
25
59^57
3869
- 2302
36-388
^^
■
June 2
58Si9
38-84
-2323
36-517
+0001 ^^1
H
9
59 iS
3876
-2'342
36'4i8
+ 0'I0O ^H
H
15
59*35
3871
-235S
36-352
+o't66 ^^1
H
22
5959
3S74
-2*376
36364
^H
H
29
59*57
3874
-2394
36-346
^1
H
30
59'22
3871
-2-397
36 -3' 3
+0205 ^H
H
July 6
59'54
38*84
-2-413
36-427
+0-091 ^H
H
7
5970
3871
-2-416
36*294
+0-224 ^H
H
U
5967
3873
-2*43«
36-299
^H
■
i4
5950
38*78
-2 '434
36*346
^H
H
20
59-50
38-88
"2-449
36*431
+0-087 ^H
H
21
59-72
3876
- 2452
36-308
^^1
■
July 27
59*35
38*70
-2^468
36-232
^H
■ '590
Aug. 4
59*57
3872
-2-489
36-231
^^^H
■ *6o7
10
59*33
38-86
- 2*505
36-355
+0-163 ^^^1
H
17
59*61
38 -88
- 2*523
36-357
^^1
H Ms
24
59-84
39-02
-2-541
36*479
+0-039 ^H
■ ^4
31
5960
39*07
-2-560
36-510
+0-008 ^H
■ -667
Sept, I
5972
39-20
-2-563
36^37
^^1
H
22
59 "81
39*31
- 2-6i%
^hfif'h
^^k
634 -ft^« ^» ^' £arnard. Parallax and Proper ucrutg,
Tablb l.—M€dii^wm to 190110 — contmuecL
II
Pt* Ang.
J>lltv
Cnr'ii for
IdOt X3b
KesRmm
novioB.
♦ar** **•
mmm.
I90374I
Sept 28
60*02
39-20
-2'634
3^-566
-OXM8
757
Got 5
59^
39*37
-2-649
36721
-0-2^
78a
n
5974
39-37
-2-673
36^697
-0179
799
19
59-99
39*45
-2-689
36761
-0-243
*8i8
26
59-50
3938
-2708
36-672
-0154
•821
27
5971
3948
-2711
36769
-0-251
•827
Not. 2
5953
3941
-2-726
36-684
-0-I66
•897
24
5945
39-66
-2784
36876
-0-358
•974
Deo. 22
59-40
39-61
-2-858
36752
-0-234
1904-007
Jftn 3
59-05
3976
-2-889
36*871
-0353
•335
May 2
59-02
39-73
-3-205
36525
-ox>07
•338
3
5903
39-48
-3-207
36-273
+0-245
•374
16
5873
39-50
•3-242
36258
+0-260
•393
23
59*17
39*55
-3-260
36290
+0-228
•434
June 7
59-16
39*78
-3*300
36480
+0-038
•502
July 2
5891
3962
-3*365
36255
+0263
•521
9
59*34
3962
-3*383
36237
+0-281
•527
II
59-27
3973
-3*389
36-341
+ 0177
560
23
59*47
39*80
-3*421
36*379
+0-139
•570
27
59-41
39*78
-3*430
36350
+ 0-I68
•584
Aug. I
5974
39*74
-3*444
36296
+0-222
•598
6
59*51
39*69
-3-457
36233
+0-285
•603
8
59-64
39*76
-3*462
36-298
+0-220
•623
15
5930
39*85
-3*481
36369
+0-149
•642
22
59-60
4004
-3*499
36-541
-0-023
655
27
5969
40X)8
-3*512
36-568
-0050
•661
29
5977
39*95
-3-S18
36432
+ 0-086
•675
Sept. 3
5929
4003
-3*531
36499
+0*019
•680
5
59*57
40'12
-3-536
36584
-0066
732
24
5979
40- 10
-3*586
36-514
+0*004
751
Oct I
59*43
40*22
-3*604
36-616
-0098
790
15
59*87
40*25
-3*642
36608
-0x590
795
17
59*68
4019
-3*647
36543
-0-025
•828
29
5959
4025
-3-678
36-572
-0-054
•833
31
59*62
4040
-3*683
36717
-0*199
•866
Nov. 12
59-26
40*53
-3715
36-815
-0*297
1904905
26
59*33
4056
-3*752
36-808
-0-290
1905-904
^OV. 26
^91^
4^1-4^
-4*605
36-855
-0*337
•QIO
2%
WS^
^Vi%
- v^w
•^^1^
-0*251
^^H
Supp, 1908.
Motion
of the Double Star Krmgtr 60. 635 ^^B
EqutUion^ of Condition, ^^^H
^^^B 1900
Dec. 8.
- 0*423 + ^ ' 0*065 v + <^*939P = 0 ^^^1
9.
- 0210 + £ - o'o6o|/ + o'944p - 0 ^^^H
II.
- 0225 -^ X ' o'055^ + 0-951 /> = 0 ^^^H
12.
- 0 192 + X ' 0*0522^ + 0-966/1 ^ 0 ^^^1
^^^ 1901
Sept. 23.
+ o'ojS + X -^ 0729;/ - 0032/i — 0 ^^^H
24.
+ 0020 + X + 0731 y - O'OIX p s 0 ^^^H
30^
- 0-063 + ^ + 0748 y + 0*091 p = 0 ^^^H
Oct, r.
+ 0*090 + ^ + 0751 y + 0*102/1 - 0 ^^^H
13.
- o'i6o -f j: + 07831/ 4- 0*303/} = 0 ^^^H
21,
' 0*068 + a; -f 0*805^ + 0 427/7 = 0 ^^^H
29.
- 0*027 + X + 0*827 j^ + o'545P - 0 ^^^H
^m 1902
Sept. 29.
- 0096 + ^ -h 1 744j/ + 0*068/7 = 0 ^^^H
Oct. 6.
+ 0*113 + •i^ + 1764;/ + 0*184/) — Q ^^^H
7»
- 0*105 -^ X -\- i'j66y ^ 0*201 jj = 0 ^^^H
14*
- 0266 4* ^ + 17^6)^ + 0*314/} = 0 ^^^1
H 1905
Mfiy 19.
+ 0-J95 -t- SB -f 2*380 j/ - o'&26p = 0 ^_^^^^H
25-
+ 0130 + a$ + 3*396 y - 0 S$4p = 0 ^^^^^H
June 2.
+ 0*001 + a; + 2*4183/ - 0*936/) = 0 ^^^^H
9^
+ 0^100 ^ X ^ 2*437 y - 0-986/) = 0 ^^^1
IS^
+ o*r66 + 2; + 2*454 2/ - 0-997^ ^ 0 ^^^|
22,
+ 0*154 + ^ + 2'473y - I '006/) - 0 ^^^H
29.
+ 0*172 + .1; + 2"492y - 1*002 p = 0 ^^^1
30.
+ 0-205 + ^ -^ 2*495 s^ " I 010/) = 0 ^^^H
Jqly 6.
4- O'ogt ^ X + 2*511 y - 0*990/} = 0 ^^^H
7-
-h 0224 + at + 2*514 j/ - 0-983/) = 0 ^^^H
u.
4- 0-219 + ;b -f 3'53o^ - 0'952p - 0 ^^^H
1 '^
+ 0*172 + i- 4- 2*533!/ - 0*952/) = 0 ^^^1
1 .0
-h 0087 + s + 2*549 y - 0 914/i = 0 ^^^H
1 -
+ 0'2io + jc 4- 2*552^ ^ 0-902/7 s 0 ^^^H
27-
•f 0 286 -f « -f 2-569 y ' 0*858 p = 0 ^^^H
Aug. 4.
+ 0-287 -F J! + 2-590 y - 0775/) - 0 ^^^1
10.
+ 0163 + ;tr + 2607// - o*7t2p = 0 ^^^1
17-
4 0'l6l ■¥ X -¥ 2*626^ - 0*620/) ^ 0 ^^^H
M-
+ 0*039 + 3J 4- 2-645 y " 0*519^ ^ 0 ^^^^^H
3**
+ O'ooS 4- a? + 2-6641/ - 0*417/) = 0 ^^^^^H
Sept. t.
- 0*119 4- j* 4- 2-6673/ ' 0*400 ;> - 0 ^^^^^^1
22.
- 0*174 ^- ^ 4- 27251/ - o'o55p = 0 ^^^^^1
2S.
-- o"048 4- at 4* 2 74^ y + 0 o^op ^ 0 ^^^H
636
Table IL-^StnatUms of CbucKMoM— Jlv j&^«m
1903 Oct
Not.
Dee.
1904 Jan.
May
June
July
Aug.
Sept.
Oct.
Nov.
1905 Nov.
- o'2Q3 + • + a757ir + 0*164^ » o
- 0*179 + « + 37&l|r + O'^^p as o
- o'243 + « + a*799ir + 0*3941^ m o
- 0*154 + « + a'SiSy + o«495j» » o
- 0*351 +9 4* 3'Sai y 4* o*5xoj» s o
- o*i66 + « + 3*837 |r + 0*595 j» = o
84. - 0*358 + « + 3-897|r + o*839j» = o
23. - 0*334 + « + 2-974|f + 0-977 1^ = o
- 0*353 + « + 3*007 y + o*96oj» = o
- 0*007 + « + 3*335y - 0^3811 = o
+ 0*345 + » + 3*338ir - 0^51 j» = o
+ 0*360 + « + 3*374y - o*8oi|i = o
33, + 0*338 + « + 3*393y - 0*87911 = o
7. + 0-038 + « + 3*434y - 0*98011 = o
+ 0*263 + ic + 3*502 y - 1*003^ = o
+ o'28i + a? + 3*521 y - o-973|i = o
+ 0*177 + « + 3*527 y - 0*967^ = o
+ 0*139 + a: + 3*560 y - 0'886j» = o
+ 0'i68 + ar + 3'57oy - 0*855 j? = o
+ 0-222 + X + 3'S^y - o'799p = o
+ 0*285 + a; + 3-598y - 0*747;? = o
+ o*220 + X -T 3*603 y - o*733p = o
+ o 149 + aj H- 3*623 y - 0*640 j» = o
- 0*023 + a^ + 3*643 y - 0-511 J? = o
- 0*050 + ar + 3-655y - 0*467 j? = o
+ o*o86 + a? + 3*66i y - 0*434;? = o
+ 0*019 + X + 3*675 y - 0*364^ = o
- 0*066 ■¥ X + 3*68oy - o*326p = o
+ 0*004 + « + 3732 y - 0*007;? = o
- 0-098 + X + 3751 y + 0*105 ;> = o
- 0*090 + a; + 379oy + o'J42p - o
- 0025 + a? + 3795 y + 0373I' = o
- 0*054 -h X -¥ 3"828y + 0*548;? = o
- 0*199 + « + 3*833 y + 0*578;? = o
- 0*297 + 37 + 3*866 y + 0726;? = o
- 0*290 + a; + 3*905 y + 0*863;? = o
- 0337 + a; + 4'904y ■*■ 0*863;? = <>
- 0*251 + a; + 4*910 y + 0*875;? = O
5-
13-
19.
36.
27.
3.
3.
3.
3*
16.
2.
9.
II.
23.
27.
I.
6.
8.
15.
22.
27.
29.
3.
5.
34.
I.
15.
17.
29.
31-
12.
26.
26.
28.
_Supp, 1908. Motion of the Doitble ^iar Krueger 6o» 637
Corresponding equations were deduced for g and j«, the
Bsulting normal equations being
+ ootio4 76*000 .T + 304*0550^- 14^8040 2> = o
+ 2*2742 -H 204-053 a; + 642-2801 y ~ 52-9454;? = o
-8*5866- i4*8o4x- 52 "9454 y + 38*0005 p = o
The solution of these gives the following values : —
p— 4- 0*249 ±0-0105
y— +0^01 1 ±o"oo63
x= 4-0020 + 0*0182.
The value of the parallax of the star A is, therefore,
7r=^ +o''*249±o''*oio5.
Thie gives a distance of over 830,000 times that of the Sun
Light, therefore, requires 13- 1 years to come from Krueger 60.
Dr, Schlesinger has kimlly supplied m« with his final value for
the parallax of this star. He dotunuined tbt^ parallax by photog-
raphy (during his connection with the Yerkes Uhservatory) from
both right ai^censioti and decli nation. These were from 19 plates
tiiken with the 40-inch telescope from 1903 to 1906, Three
separate images were impressed on each plate. His resulta are —
From R.A. tt = 4-0*257 ±0*007
,, DecL w = -ho'338±o'oii.
It will be seen that the mean of these^
w = H-o''*248,
is essentially identical with ray value.
The results with the same instrument, by visual and photo-
graphic methods respectively, in the one case by p>ositiun-angl« and
distance, and in the other by right a-scension and declination,
should inspire con&dence in both method:^.
■ Irregularity in the Proper Motion 0/ A.
At present the «tai's A and B are moving almost directly away
from C. This iatter star, therefore, is a good one from which to
determine the motion.
If B has a considerable mass ratio to A, a large irregularity in
the proper motion of either star must occur because of the large
apparent distance between the two. If their masses should be
nearly equal, this deviation from uniformity at motion in either
6tar may amount to as much as i''*5. Th\a laat m«A& xuXa»'*s& t^^x*
638 Pro/ E. E, Bamard, Parallax and Proper Lxvmj
improbable, in view of the investigations of Mr. Lewis of
Greeowicli Observatory who found* that in some ca^es
apparently smaller star of a binary is really the more massive nf
the two. It is important, therefore, frequently to measure the
position of A with reference to C and other stars in the field* By
this means, in the course of time, its mass will hecome ace
known. For this reason I have kept the star on my oUservii
and have made frequent measures of it and the stars meii
Of my own work there are now some seven or eight years' «• i
tions. Of course, for various reasons^ where it ia possible, it g[
best to use the measures of one individuah
The knowu history of these stars perhaps covers too short an
interval for the observations to show any very decided irregularity
in the motion of A. To see if there was any such change, tb
measures were freed from parallax, and means of four or five Ukeu.
These were plotted on a Ittrge scale. A thread was then tightly
stretchetl over the measures and carefully a<djasted to give the best
representation. This straight line does not represent the obserw
tions with entire satisfaction. The be^it average, however, wa« fvb-
tained, and the deviatiuns read off. These differences are given in
connection with the mean measures. The ends of the thread would
represent the positions 1 900*943, distance 36**49, and 1908*302,
distance 43''*53.
As these lueasures tnay be of interest to others, they are giveo
below. The first cohimn alter the date^ is the measured distance
corrected for refraction, the next column gives the correction fp(
parallax, while the last is the distance affected only by molid
The means of these and their deviation from the straight Hue
also given,
DittaneiM (AC) corrteUd for pttralltix.
QbA. ditt
Cor ti for
True diit.
1900 Dec. 8
36'-88
-0-23
36-65
9
36-67
-0-23
36-44
ri
36-69
-0-24
36-45
12
36-66
-0-24
36-42
1900-943
36 49 - ot>J
1901 Sopt 23
37'i8
+ 0*0t
37*19
^4
37*20
O'OO
37-20
30
3730
-0-02
37 -aS
Oct J
37'iS
-0-03
3712
1901740
37*ao - 0104
190 1 Oct. 13
37*43
-o-o8
37-35
21
37*36
-O'lX
37**5
29
1901792
37 '34
-0*14
37*20
37*37 ' 002
M«tnt>vr!i R,A.S,,"s«\Ax\.^.
Supp. 1908. Motion of the Dovble Star Krueger 60.
Didanees (A C) corrected for /)ara/2aa^— continued.
639
Obs. dUt.
Cor'n for
pUx.
Truedlst.
1902 Sept 29
38-29
- o'-02
3^'-27
Oct. 6
38-10
-0-04
38-06
7
38-32
-0-05
38-27
14
38-50
-008
38-42
1902764
38-25 + 001
1903 Alay 19
38-61
+ 0-21
38-82
25
38-69
+ 0-22
38-91
June 2
38-84
+ 0-23
3907
9
3876
+ 0-25
39-01
1903-407
•
38-95 + o-»o
1903 June 15
3871
+ 0-25
38-96
22
3874
+ 0-25
3899
29
3874
+ 0*25
38-99
30
3871
+ 0*25
38-96
1903-480
38 97 + 0-05
1903 July 6
38-84
+ 0-25
39-09
7
3871
+ 0-24
38-95
13
3873
+ 0-24
3897
14
3878
+ 0-24
39-02
1903524
39-01 + 0-04
1903 July 20
38-88
+ 0-23
39-"
21
38-76
+ 0-22
38-98
27
38-70
+ 0-2I
38-91
Aug. 4
3872
+ 0-19
38-91
1903-568
38-98 o-oo
1903 Aug. 10
3886
+ 0-I8
39'04
17
38-88
+ 0.15
39-03
24
39*02
+ 0-13
39-15
31
39-07
+ 0-I0
39-17
1903-637
39 10 + 0-03
1903 Sept. I
39-20
+ 0-I0
39-30
22
39-3 »
+ o*oi
39-32
28
39-20
-O'OI
3919
Oct. 5
39-37
-0-04
39-33
1903725
39-29 -V o*\^
4
640 Prof, K B, Sumardf Parallax arid Proper LXVIil{
DitUmeu (AC) eomeM fitr
OlM.dirt.
c^*.
Tnm^UL
1903 Oct.
13
39-37
-0XJ7 .
39V
19
39-45
-©•lo
39-35
a6
39-38
-01a
39->6
a;
39-48
-013
39*35
1903804
39-31 + 0^
1903 Not.
2
3941
-o-is
39->6
%
24
39-66
-0*21
39-45
Dee.
22
39*61
-©•2S
39-3«
X904 Jan.
_i
39-76
-0-24
39-5*
I9q3-9a7
•
39-40 + 0x6
1904 May
2
39-73
+o*i6
39-89
3
39-48
+o-'i6
39-64
16
39-50
+ 0-20
39-70
J3
39-55
+ 0-22
3977
1904-360
3975 o-oo
1904 June
7
39-78
+ 0-24
40-02
July
2
39-62
+ 0-25
39-87
9
39-62
+ 0-24
39-86
II
39-73
+ 024
39*97
1904-497
39*93 + 0-04
1904 July
23
39-80
+ 0*22
40*02
27
39-78
+ 0-21
39*99
Aug.
I
39-74
+ 0-20
39*94
6
39*69
+ 0-19
39*88
1904*579
39-96 0*00
1904 Aug.
8
39-76
+ 0-18
39*94
'5
39-85
+ 0-16
40*01
22
40XH
+ 0-12
40-16
27
40-08
+ 0-I2
4020
1904-631
40-08 + 0-04
1904 Aug.
29
39-95
+ 0-II
40-06
Sept
3
40-03
+ 0-09
40 12
5
40*12
+ 008
4020
2/V
40-10
0-00
40-10
1904-6S6
ftjyv^ ^^0*06
Supp. 1908. Motion of the DouhU Star Krutger 60. 641
Distances (A C) corrected far
ObB. diit.
1904
Oct. I
29
jxtrcUlax— oontinaed.
Tnie diat.
Cor'n for
pllx.
40*22
40-25
40-19
40-25
-o'03
-o-o8
-0-09
-0-14
40-19
40-17
40*10
4011
1904790
40-14
0-00
1904 Oct. 31
40-40
-0-14
40-26
Nov. 12
4053
-0-18
40-35
26
40-56
-0-21
40-35
40-32 +
1904-869
009
1905 Nov. 26
41-46
-0-21
41-25
28
41-38
-0-22
41-16
1905-907
41-21 -
003
1906 June 28
41*45
+ 025
41-70
July 7
41-51
+ 024
41-75
10
41 54
-f-O-24
4178
24
41-76
+ 0-22
41-98
1906-523
41-80 -
003
1906 July 29
41-68
+ 0-21
41*89
Auj?. II
41-72
+ 0-17
41-89
H
41 63
+ o-i6
41-79
1906*602
41-86 -
0-20
1907-289 Apr. 16
42-52
+ 0-IO
42 62 +
o-io
1907 July 2
4273
+ 0-25
42-98
12
42-57
+ 0-24
42-81
28
4263
+ 0-21
42-84
30
4264
+ 0-21
42-85
42-87 +
1907 '544
0-04
1907 Aug. 6
4277
+ 0-19
42-96
8
42*62
+ o-i8
42-80
II
4253
+ 0-17
42-70
13
42-78
+ 0-17
4295
20
42-68
+ 0-14
42-82
42-85 -
1907-612
o-oi
1907-749 Oct I
42-91
-0-03
42-88 -
Oil
1908 Apr. 19
43 '40
+ 0-12
43*52
21
43-25
+0-12
43*37
1908-302
6,ytA - ^^^
642 Prof. S. B. Baifiard, Parallax and Proper LXVllLg^
o
CD
3
Si
3
O
O
c
,0
o
a
o
L.
Q.
Siipp. tQoS. Motion of the Double Star Krmger 60.
643
This iavestigatlon Jed tne to notice that the direction of motion
of A was regularly diminishing with the increase of time when
derived tri>m a comparison with thi- measures of iSgo'S. The
motion was also slightly increasing. To find out the canse of this
change I plotted the observations for t^ach year (fig, 2), correct-
ing the distances for parallax, and et^leeting the positions so that
there would be but little parallactic change in the angles. No
cortectioa for precession has been applied to the position-angles.
The extreme change due to this last cansa would be o^'oy. The
result shows that hetween the cpoclis 1 890*8 to r 90 r8 and 1901*8
to 1 907 "7 there has been a total change of some 8'' or 9^ in the
direction of motion. If we take the interval 1 901 '8-1 907*7 the
direction of jnotion is 239*1 ^^^^^ ^^e previous values were about
247*. A simple inspection of the diagram will show the change.
It is evident, therefore, that the motion of A is not rectilinear.
This change is undoubtedly due to the orhital motion of A about
the centre of gravity of the system. It is therefore not possible
to give a value of its proper motion that will be constant for any
considerable interval of time.
The following measures were used in constructing the diagram.
The distances A C are corrected for parallax.
AC.
.
Obnerver.
J8907S8
56*30
26*73
Burn ham.
IS^'446
5871
34*64
DooUctle.
1900737
59 '1 9
36*18
t >
ir/iA>'943
59*30
36-49
Barnard,
1 901 766
5962
37*23
M
1902764
59 '64
3«-25
It
1903765
5977
39 '30
>*
1904782
5955
40*19
M
1905907
59-63
41-21
M
1906*602
S9'54
4 1 "^6
,,
1907-680
59 '57
AB
42-87
11
^
Obiervcr.
18907S8
178*80
2-32
Burnham,
1898-446
140*66
3''9
Doolittle.
1900737
134*02
318
»i
1900-943
t33*U
325
Barnard*
1901767
13067
3-28
^,
1902765
127*05
336
• »
1903761
J 23-^9
3 '35
tt
1904791
120-30
yii
,,
1905-907
"5*34
3 '31
" 1
1906-601
na-27
334
• f
1907-676
107-00
3*27
y^
644 Jhrof. B. B. Barn^lTd, PamUm amd Pr^^ uvntft
Orbital Motion of Krueger 60.
Fig. 3.
The Micrometer Measures,
I have collected here for this paper all my published and un-
published measures of these stars, so that my work on the subject
up to the present may be presented as completely as possible. All
the distances have been corrected for refraction.
The diagram (fig. i) will show the relative positions of these
various stars.
The measures follow.
Measures of Knuger 60 and Comparison Stars.
AB.
1900-937 Dec.
8
13206
3'30 9*2
•940
9
133-19
325
•945
II
133-59
3*24
•94&
\^
nvi^
v^^
19«>'943
nv^^
•v^s ^•>^
105
ws
Supp. 1908. Motion of the Double Star Krueger 60.
A B — continued.
645
1901 729 Sept
23
13005
3*37
731
24
129-11
3*39
748
30
131 50
3*37
751 Oct
I
131-65
3-25
783
13
129-69
3-31
•805
21
130-59
326
•827
29
I30'59
322
1 901 768
130-45
3-31
mag.
95
9-2
9-3
mag.
IO-5
IO-5
IO-5
1902-744 Sept 29
127-25
333
•764 Oct. 6
128-17
3'43
•766 7
12673
3*35
785 14
126*06
3*35
1902-765
127-05
3 '37
1903-380 May
19
122-36
332
'418 June
2
122-34
3-42
•437
9
123-85
3-40
•454
15
12349
3*37
•473
22
123-47
3-33
•492
29
124-90
3-36
•495
30
125-96
3-26
-511 July
6
121-31
3*51
•514
7
123-18
3-30
645 Aug.
24
124-52
3-45
•664
31
122-91
3*35
-667 Sept.
I
121-98
3-37
725
22
124-54
3-27
741
28
123-54
3-45
•818 Oct
26
123-60
123-46
3-33
1903562
3-37
M
646 Prqf. B. B. Bamasrd, Paralhm mni Pnfut ijEfm 9
^904-335 May a
119-44
3*35
•338 3
119*46
3-35
•373 «6
119-92
3-40
•393 23
118-51
343
•434 June 7
118-82
3*37
*502 July 2
121-45
343
•5*1 9
121-28
3-35
•5*7 11
120-68
3-3«
•560 23
119-94
339
•570 27
117-99
3-35
•584 Aug. I
120-47
3-43
•598 6
119-24
3-4«
'642 22
120*96
3-42
•655 27
119-47
3-37
•675 Sept 3
119-50
341
•751 Oct. I
118-98
3"3X
•795 17
121-07
3-28
•828 29
12084
339
•905 Nov. 26
117-46
119-76
3-33
1904-578
.V38
1905 904 Nov. 26
1 16-04
330
•910 28
11464
3*31
1905-907
"5*34
3-31
1906 490 June 28
"363
3-28
•515 July 7
112-44
3-28
•523 10
109-72
3*34
•561 24
112-57
3*33
•575 29
112-71
331
•610 Aug. II
112-31
3*33
•619 14
111-78
3-38
1006^^6
\\^*\^
•j;!?.
3upp. 1908. Motion of the Doiible Star Knieger 60.
A B — continued.
647
1907 289 Apr.
16
io8-o6 .
3*14
•500 July
2
108-09
3-26
•528
12
106-31
3*29
•571
28
10659
3-28
•577
30
107-83
323
•596 Aug.
6
106*06
342
•601
8
107*92
3-28
•610
II
106-93
3-38
•615
13
107-47
320
•634
20
107-13
3'i7
706 S«pt.
15
105-34
3*37
749 Oct.
I
108 -06
3-36
1907-581
10715
3-28
1908-300 Apr.
19
105-65
2-97
•338 May
3
105-19
3-30
•376
17
103-99
321
•382
19
104-63
y^i
•390
22
104-18
3-26
•401
26
102-70
3-«3
1908373
104-39
3-18
mag.
mag.
AC
111 this table all the previous measures of A C — those used in
he determination of the parallax — have been omitted, because they
re given in Table I.
1906*490 June 28
59-01
41-45
-515 July 7
59-23
41-49
•523 10
5923
41*54
•561 24
5971
41-76
•575 29
59-55
41-68
'610 Aug. 1 1
5960
4172
*6i9 14
59-48
41-63
1906*556
5940
41*61
mag.
mag.
9*5
9'S
^
648 Prof. K £. Barnard, Parallax uTid Proper LxmL^
1907*289 Apr. 16
59'«*
4a-5a
"SooJoly a
5934
4*73
*538 la
59-55
4aS7
•571 a8
59-40
4a-63
'577 30
59'i9
42^
•596 Aug. 6
59-44
4277
•601 8
59-59
43*62
*6io XI
59-14
4253
•615 13
59-50
4278
•634 flo
59-55
4a«
749 Oct I
5971
42-91
1907-570
59-42
4a'67
1908*300 Apr. 19
59-33
43-41
•305 a«
5899
43-25
•338May 3
5876
43'5«
•357 10
59-15
4372
•376 17
5898
43-32
•382 19
5924
4352
•390 22
5898
43*57
'401 26
5919
4354
1908-356
59-08
43-48
AD.
1900*945 Dec. II
-948 12
i90&-iVS^
21*25
20 -86
»S^>^
ib*%n
>5
155
1900*947
21-05
21*30
15-3
1901-783 Oct 13
2356
21-54
15
•786 14
21*58
21-85
-805 21
23 '04
21-72
»5-3
•827 29
23-07
21*78
1901*800
22*81
21*72
15*1
1903*5" July 6
2468
22*75
•514 7
2409
2283
22-79
>5
1903-5"
24-39
15
1908*415 May 31
29-25
26*69
-467 June 19
29*51
26-99
•472 21
29-4«
2693
lupp. 1908. Motion of the Double Star Krvsger 60.
649
AE.
1900-937 Doc,
•940
•945
1900-941
98-85
99-06
99-00
9897
6^'o3
6779
6776
67-86
in«g.
mag.
12-5
13-5
lys
13-2
1901 -729 S«pt 23
9893
68-20
12
731 24
99*14
68-49
12-5
748 30
9906
68*64
•751 Oct I
9892
68-22
783 13
99-01
68-32
•805 21
98-91
68-39
II-3
•827 29
98-83
6864
I90I768
98-97
68-41
II-9
1903-437 June 9
97-89
69-17
13
•454 15
97-99
6937
•473 22
97-87
69-20
12
•495 30
97-96
6942
•511 July 6
98-07
69-47
•514 7
97-78
69-51
•530 13
9826
69-38
•533 14
98-18
6944
•549 20
98-09
69-55
-569 27
9801
69-47
-607 Aug. 10 .
97-64
69-44
•626 17
9784
69-64
•645 24
97*97
69-90
•664 31
97-86
697a
•667 Sept. I
97-93
6971
•725 22
98-02
70-12
-741 28
97-90
69-89
12
757 Oct. 5
97-86
69-93
782 13
97*59
70*11
•799 19
97-80
70-26
>3
*8i8 26
97-78
70-22
•821 27
9770
70-08
12-5
-837 Nov. 2
97-64
7011
la
•897 24
97*56
7026
12
•974 Dec. 22
9741
70-22
12
1904-007 Jan. 3
97-49
7047
12
1903-670
97-85
69-81
\v^
650 Pfof. E. JK Bamoyrd, ParaUm mid Fr^ptr ixmL%
1904-335 May a
97*14
70-10
12
•338 3
97-44
69-91
la
•527 July II
97-4a
70-38
la
•560 a3
97-53
7019
la
•570 a7
97'43
70-13
13
•584 Aug. I
97-64
7o'ai
13
•598 6
97-3a
7047
•603 8
97-89
7076
•623 15
.97-66
70-76
^642 aa
97-54
70-49
la
•655 a7
97-50
70-61
13
•661 a9
97-56
70-93
•675 Sept 3
97*44
70^61
12
•680 5
97-66
70-81
ia-5
751 Oct. I
97*53
70-80
12-5
790 15
97-54
71-00
12
•795 17
97-40
7077
12
•828 29
97-48
70-97
12-5
•833 31
9727
70-99
12-8
•866 Nov. 12
9723
71 06
•905 26
9729
70-94
12
1904-653
97*47
70-61
12-3
1905*910 No7. 28
9687
71-97
i9o6'6ioAug. II
97-08
7204
12-5
•619 14
96-61
9685
72-20
12-5
1906-6x5
7212
12-5
1907-596 Aug. 6
96-04
. 72-51
13
•601 ^ 8
95-96
72-66
•610 II
95-70
72-80
•615 13
96-29
72-80
•634 20
95*93
7259
•667 Sept. I
95*82
72-88
12-8
706 15
96-24
72-89
749 Oct I
9614
7280
19076^7
<^*Ci\
T^nN
12-9
■1^1
BH^I
0. 651 B
^^^^1
Ikipp. 1908. Motion
d/ /A« DoubU Star Kruet/er 6
A E—tOfUinued,
^M
1908-415 May 31
95*53
nam
73*05
^^H
'417 Jane I
95*39
lyoQ
^^M
•428 S
95 '47
7310
^^H
•467 19
95*41
73*14
^^1
»472 3,
9SS0
9546
73 -OS
73-07
I
190^*440
•
AR
1
1 901729 Sept 23
375*36
39-61
^^1
731 24
274 7«
39*53
^^1
751 Oct I
275-20
39-61
^^1
^K
275'33
39-52
^»
^^r *8o5
275*34
39*53
15 ■
W 'S27 29
275*53
39*57
■ 1901771
27526
39*56
•
I4'5
K i9<>3'473 JiiQi^ 22
277-24
38^47
13
K *492 29
277-59
13 ekyiidi.
^^
276-84
38-46
127
^^^1 *5ii Jaly 6
277^06
38-34
18
^H
277*09
3^^*51
^H
276*52
38*37
^H
276-34
3S-50
^^H *626 Aug. 17
27692
38*45
^H '<H5
276*49
38*11
^H -664
27670
38*21
^^1 725 Sept 32
27674
3S-16
^H
276*87
37 -So
n
^^H 782 Oct 13
277 x>6
3815
^H
277-14
3807
M"5
^H
277 Si
3S-80
^^F ^>'
277*36
3779
15*0
■ 'S97 Nov. 24
277*35
38-29
«41
1 1^03*652
276-98
3&-aa
^irn
652 Prof. JB. E. Barnard^ Parallax and Proper lxvul 9.
904-335^7 a
278*20
37-76
127
•393 23
W89
38-05
12-5
*$6oJii1y 23
27771
37-39
14
•570 27
277-64
37 -ea
•584 Aug. I
27736
37-3S
15
•598 6
277*01
37-90
•655 27
27774
37-15
14
•675 Sept 3
277-67
37-40
15
•751 Oct I
277-84
37-15
14-S
790 15
278-17
37-38
15
•795 17
277-64
36-83
145
•828 29
278-19
37-18
147
•833 31
277-87
37-34
MS
•905 Nov. 26
278-16
36-99
14-5
1904734
277*79
37-39
14-2
1907-667 Sept I
280*56
35-23
I4'5
•706 15
280-76
34-47
•749 Oct I
280-75
34-73
145
•782 13
281 -05
34-67
14
1907-726
28178
3477
H-3
1908-415 May 31
281-80
34*94
•417 June I
282-06
35-16
-428 5
282-13
35-15
-467 19
2S1-58
34-63
•472 21
281-40
34-78
1908440
281-94
CE.
34-93
1903-552 July 21
12971
40' 19
1907*634 Aug. 20
129-41
45-84
7Ji2 Oct 13
129-88
45-98
137
1907708
129 -6$
45-91
«37
Supp. 1908. Motion of the Double Star Krueget 60.
653
It will be seen from the measures that the distauce A B is be-
ginning to lessen, having attained a mnximnm about 1903 or 1904.
The pos^ition-angie AC seems to have reuched itn greateRt valae
about 1907 and is now .slowly diraitiishiug. Bolh changes are due
to the orbital luotiun of A* in th« system A II
The folio wmg estimates of the ma^^nitnde of C were made at the
time of the observations which have het^n included in Tabl© I.
1900 Dec. 8
9'5
1901 Sept. 24
9^5
Oct. 21
97
1902 Sept 29
9 9
At the observation of 1900 Dhc. 9 the following note occurs :^ —
** Both A and C are alightiy yellowish.'*
Two amall Double Stan Tiear Krueget 60.
During these meaaures two small doyble stars were found and
measured. Though they are not in any way connected with Krueger
60, their proximity to this star, and the general resemblance of one
of them to A B, wo aid aeem to warrant their insertion here.
No. K
(1855-0
a 22'' 191" 42«-8
t « + 57'
6'-3v)
m»g.
mmr.
1901 73 J SepL 24
34/-04
2'-99
9*5
12
■805 OcL
21
247*19
i'll
9
u*
1901 76S
247-11
3-05
9J
t*"5
1902766 Oct.
7
247 "23
2-67
9'5
ti
1903-454 Jin*
'S
24670
3'20
9'8
ti
•47S
22
24S79
3*09
•511 July
6
24762
3-04
•514
7
246-68
325
1903*488
247*45
3'M
9*8
u
1908*428 Jane
5
248-05
3 '04
•467
^9
245*08
3«
9'1
1 1 -2
1908*447
246-57
yn
9*i
v\*a
654 Prof. B. E. Barnard^ Parallax and Proper LXViu.9,
No. X
(1903-0 « aa^ 22» sa^-i, 1 ^sj* 13' ja*.)
1902744 Sept 29
a6o'i5
1-37
10
II
i903'454Jttn6 15
268*50
1-41
1907749001. 1
259«o5
«'37
1908*382 May 19
*40i 26
'467JQiie 19
1908417
261*32
260-95
a$9'95
26074
1-35
I '45
1-46
i-4«
10
9-S
II
IO-5
107
The FoUowing Camponenl of No. 2 and a Faini Siar North.
1908*382 May 19
*40i 26
1908-391
340*59
34056
340'57
87-67
8770
87-69
12
13*2
12-6
Additional measures of some of the stars have been inserted
since this paper was submitted to the R.A.S.
YsRKss Observatort :
1908 May 18.
I am very glad to be able to add to this paper the value of the
parallax of Krueger 60 determined by Dr. Henry Norris Russell
from photographs with the Cambridge (England) refractor. Dr.
Russell has kindly supplied me with his value since my paper was
put in type.
His result is : —
7r= +o"*258±o"*oi3
from measures of Aa. Nine comi>arison stars were used, and the
probable error for a single plate was ±o''-026.
The following, therefore, are all of the values of the parallax
of this star known to me : —
Si-hlesinger = + o"*248 ± o"-oo9
Barnard = +0 '24910 010
Monthly Notices of R.A.S.
Vol. LXVIIL Plate U.
Photograph contamin^ tKree eKpD»ure& of the double slar Krueger 60 A B
and th« comparison star C Taken with the 40-4 nch re Tractor of th«
Yerkes Qbiervatory, ]9€.8 Ju^y 10 (enlarged). Expoiures ]0 minutes each.
— E. E Barnard.
Supp. 1908. Motion of the Dmble Star Krueger 60.
65s
Additional Measure of Krueger 60.
AB.
1908 Aug. 30
10071
3-»4
Sept 4
103-10
3-17
6
105-13
3-15
15
104-69
3*^4
20
103-92
3*14
Oct. 4
1 02 '67
3-^1
103*37
3-i7
AC.
1908 Aug.
30
5962
43*93
Sept
4
59-69
43*94
6
59*55
43'9i
15
5938
44-19
20
5974
43*87
Oct
4
59*55
4408
59*59
43*99
I have also added a photograph of Krueger 60 (A B) and the
comparison star C, which I made on 1908 July 10 with the
40-inch refractor and a yellow colour screen, with Cramer Instan-
taneous Iso plate. There are three exposures of 10™ each.
1908 Oct, 5.
556 , Prof, Ttu-ner, Passible Periadk Inequalities LXTm.9,
'-ih/poe^ihle Periodie Inequalities in th4i Epodi of the Sun-spot Var^
/ ation. Papers of the LU,S,R. Compxtting Bureau, N&, IV^
^ By H. H. Turner, D.Sc, F.R,S., Savilian Professor.
i, Wh^ii any fwirit of iinportauco arises with regard to
stnrft, it ia Hittural to inquire whether it i» n?pre»eiited in
behaviour of the one star which we can observe to gpc^cial aJvantag
viz. our own Sun. Rejisons* have been given elsewhere* for
regarding the Sun, provisionally at any rale, as a long-pt^riod
variable with a period of 11^ years, but with a very small rang**
of Viiriatiou. Reason.'* have aUii been given t for regarding tiiK
oscillations of maxinnim of lun^'-period variables as systematic :
80 that when Chandler writes for the epochs of maximum aa
expression such as
€ + P.E-hCtiiij(A%E + a),
where P is the period in days, and E the number of perio
elapsed since the epach c, and {.\ A, a tliree constants, we ha
approximately
A.^2^'t^ 018 P.
Hence the questions arise, — Is there an osciUutioD of this kind
the Bun-^kpot maxima f and if so, how far does it fit in with the
fornmliE "? The period of the Sun (say 4060 days) is so very moell
ioniser than that of any of the stars u^ed in deriving the above
formulie that we may be prepared for ftonie error, even a consider
able error, in the extr>ipolr4ti<>ri ; but we may at least expect both
A and C to be larger than foi the stars, if the Sun falla into Ibe
at all.
2, Dr. Wolfer has given (on page 96 of the Aitron. MiU^lungm,
io, xciii.) a list of deviations of 26 minima and 26 oaaxima fn
I uniform arithmetical progression. These are shown in Table '
Table I.
11
ol/er^s
Mininui and
i/nniTUi
of
Sun-npoU
r.
+0-3
M&x.
-0%
Mfn.
-H-2
y
MilK
I'
-OS
IfAL
4-o'S
-27
-^'4
+ J 6
+oi
■fit
^2'9
+ 1*2
+ ro
+ 0*9
H-o>
4-0*6
-09
^ro
-0*6
<fO'H
^-0-9
-10
*J'l
-0*1
-o'6
'0-2
+ 1*0
^04
-02
-02
+ 3"5
O'O
-19
+ 04
-o'S
+ 2-1
+ 2*2
-2*1
-4*2
^ro
^1*4
^ro
-0*9
-4'I
-5^
+o'5
+0'S
-17
+ 0-5
1-6
4-0*4
(The unit is one yeftr.)
* S^je Mem. A'uL, \%\\\ \k 549 auJ Ixvii, p. 534,
Supp. i9o8^ in the Epoch of the Sun-apot Variation. 657
3. The problem 18 to find whether these residual s are affected
with a periodicity C sin (A°.E + u), of which both the coefficient
C and the argument A are unknown. In such a caae, Professor
Bchuster has in dated that we have no resource but tt> try all values
of A ; or rather a series of values separated hy smnll intervals, the
size uf the interval tlependin^ t>n the "resolving power" of the
available materia!. In the prifsent case, successive values of A
dilfering by 2" were trietl, and the resulting " periodogi am " ahows
that this interval ia siifficieDtij small. For each value of A
we form
I
i^b''^(^'^r,,BinX\'E)\(^^ry^cosA\Ey
being used by Chandler to denote the number of periods after a
given epochs and r^ being the corr<?3|>onding residua! in Table L
If we had exactly
len we should have
a = C cos a 2 sin^ AE + sin a^, si" AE cos AE
= JC cos a 2 (i - cos 2AE) + mtJ a2 ^^^ ^AE
«iC ^cosa ^2, cas(2AE + a)
where n ia the number of terms in the series — viz. 26 in our case.
Now the sum S cos (2AE4-a) is generally small compared with n*
It will be seen later that the smallest value of A which seriously
concerns u^ is about 20" ; so that as E increases from o to 26,
2AE tncreaaes from o* to 40' x 26 = 3 x 360'' nearly. Hence
cos (aAE + a) runs through its cycle nef»rly three times ; atid since
^^ each cycle the positive and negative terms cut one another out,
^Brhftt is left is small NeglectiBg it, we should have, 10 the
^Bleal caae^
But accidental errors will give a sensible value for a- 4-//- for any
v;ilue of A. We must look for values of A which give large values
of a^ + ^^ These values are tabulated in Table II., which was
calculated in the Computing Bureau of the LU.S.R.
a — JC n cos a and ^^ ^ JC w sin a
or i3C= Ja^ + ¥ .
^^^^p^p^
^^^I^^^^B
if. Turner, PossibU Perwdic JtiequalMes
LXVIU.9,
H 658
Pn
^■_
Tablb II.
^^^k
PeHwloifram
of Wolfef^g Heddtmi^,
^^^^^^A
Mln,
Max,
A
Mln.
Max.
A
Mi«.
Jilt,
^H
*00
•04
4S
i'o6
»'97
94
I^
[x>8
^M
X»I
•09
SO
1*0]
281
96
•9a
•9»
^^^^^^
•07
•16
52
J -05
3*52
98
75
^
^^^^^TB
•26
'39
54
'95
3 "34
100
'82
-S3
^V
•33
70
56
*66
298
102
72
^
^H
'45
99
58
'43
2 '57
104
*6d
'4*
^K^
•69
i"5i
60
'41
2 '39
fo6
te
52
^^H
1*27
1-80
63
•26
1-70
to8
•57
•Sf
^^H 18
ISS
216
64
27
130
tio
'44
77
^^^V 30
1 82
256
66
'J6
I 13
112
40
«l
^H
176
2-50
68
•46
95
114
*5S
72
^1
1-60
226
70
■45
^95
116
26
6t
H
r52
213
72
•47
78
tt8
27
40
H
ro7
1-59
74
2%
80
lao
*2Z
2S
B
078
I -04
76
•13
'48
122
17
-aH
■
1 52
*92
78
19
75
124
'19
m
34
■50
'56
80
29
'97
126
31
34
' 36
'46
43
83
'4S
r23
taS
*20
•4»
38
'SO
*4i
84
71
'93
Uo
le
•48
40
•56
•62
86
'85
rog
132
*H
'44
4a
77
'91
88
'98
VQ^
'34
*io
,^^i
44
'94
12%
90
'87
115
136
•10
-^H
46
•96
212
9a
ro8
ri2
13S
n
^\
Means
o'$6
llS
o-6o
i'S6
041
O'fO j
1 4'
We h
ave to
look for ca.^es where the vaJue
of aS
4^ AM
strikingly exceeds its
mean
value.
The mean value should, 1
loir^l
[ ever,
he taken from the undisturbed
portions of the periodogram, aaJ^^H
there
ia always a little doubt
/in the first instance which these
ar«i^H
The means of the col
unins 1]
ave been taken, and the mean of tht* ]
1 six ia o*8a.
The h
igliest
value reached, 3*52
, is only
4-4 Umei j
this mean ; hut if we exclud
e the column io w
hicb it
occurs
the J
mean
falls to "71, and the
iiighest
value, 3-52,
is very
ncarlv
Afl^
times this. There is
just a ]
possibility that this peak indicates a rei^B
fMjriodicity, though t
le pro
bability
is not high.
It will be
seeif^H
I that there in 1
1 slidvt rise in t
he column for miiuma near
the samt^l
value
of A {vm 52'),
thou^^h the rise is far too
slight to be worti^^l
^^ notice
independently
Still
, there
are obvious
reaaons why
tfa«V
^^^ minimuni may h^. out
so well determined as the
maximum.
\
tL
Thorvi \s flb\ao flk t\afe ^V k= a^*
, >X\CkX!L^ wit
. <iuite ao ma^^^J
Supp, 1908. in the Epoch of the Sun-spot Variation, 659
It is worth noticmg, however, that the accompanying rise in the
column for minima is greater, an«l that there are indications in
aoiin? t>f tiie variable stars of another term accompanying the main
inequality (see the case of S Serpentis in M.N.^ Ixviii, p. 563).
6, To Htate the aaae as favf>urably as possible for the existence
of a periodic itiequahty in the sun -8 pot period, we may exclude
from both colnmns the values
from A = 14* to A = 30*, and from A = 44* to A = 66\
Eiid then the mean value for the periodogriitn for minima becomes
0*46 ami for the maximum 0*62. The ratio of 3 '5 2 to its own
mean is thus nearly 6, anil to the mean fctr both mnximum and
minimum is neurly 7.
7, Recurring now to the quantities which give us the in-
equaJity» if it exists, we find for the formula& representing the
maxima, when A — 53* (which seems the best value),
^ r4 sin 53* E-o*2 co« 53" E,
and for the minima
- 07 sin 53* E - o'l cos 53" E.
But tlie epochs are not quite the 8ame. The minima begin with
1610*5, and the maxima witb 1616*3^ or 5*8 yearti later, which is
5*8/1 1' 13 = "52 of a period. The pha.'^e of the inequality is thus
advanced by 53*x*52 = 27" for the maxima, and to compare the
expressions we must write
- 1-4 sin (53* E- 27 ) -0-2 cos (53" E-27')
= - 1*3 siu 53" E + o*4 cos 53* E for maxima,
aod, &H before,
-o'7 sin 53° E-OT cos 53' E for the minima,
8, In Chandlers notation, the sun-spot ma at i ma would therefore
be given by some such formula aa
const + 4060 E + 490 sin (53' E + const),
and till? question now arises how far this formula for the Sue
accords with those found for the stars and quoted in g i. Putting
P = 4060'* in these formnl®, we have
C = 7*^:3 + o*''o64 X 4060 = 267** as against 490
A— 2*'6 + 0*018 X 4060 = 76' as against 53^.
There is, of coui^e, no n^ason why tkt-se formulae should be
strictly linear, so far as we know at prssent ; and if we remark
that the value of the coetlicient C obtained from the minima is
only aVjont half that obtained from the maxima (i,e. in sensible
iigreemeut with the star- formula), the accordauce is ^w^^dfti^Vg '^jisA
66o Prof. Turner f PomUe Periodic Inequalities Lxvui. 9,
to 8U(;ge8t further inquiry. One fact emerges from the discusaios,
viz. tliat from the available material it ia dit)icult to make sure of
the existence of an inequality similar to those ehown by the st^n.
W*» may take it that the coeflicieiit C ia of the right order of mag-
nitude to tit in with the star-formula : and our periodogratn ahowt
that in this case it is too small to stand out clearly from the
accidental inequalities. It will not be possible to afBrm or deny
thd existence of such a 11 inequality with confidence until the
material is improved by extending the series of observations, or
possibly by reducing the accidental errors of the older observatiaos
by iniprovtid discussions of tbem. One hope of reducing the
accidental errors proved vaiii. It was thought that, since thert are
two independent series of maxima and minimal they might be used
tu combiniition in some way, so that the effect of accidental errors
of one aeries might be reduced by the other. But apparently the
two series run together so closely that not much can be gained to
this way.
9. The value A = 20' gives a value of C not much amaljer than
that for A = 53* ; and from the muterial it is not easy to say which
of these two possible terms corresponds to the terms found for
viirifthle stars. Are there possibly tw<i terms in general \ The case
of S Serpentis has already been quoted, where the existence of a
long-period terra had masked the short* period term. In other cases
there may be long-period term% affecting the short- period term« to
a smaller extent^ and this may account for some of the large
deviations from the formula. And these two values A = 53" and
A =^ 20" for the Sun may help us, by suggestion, in petting at the
facts for the vftriahles. The scriea of observed maxima for the Sun
ia much longer and more continuous tban those for most of thfi
variables ; and it would not be surprising if we got suggestions from
it which would help in elucidating the shorter seriea
10. Aasnniin^' that the value A = 53"* corresponds to the terms
that have attracted attention for the variables, then the formula
A = 2'-6 + o''Oi8xP
does not hold for so large a valu« of P as P =:^ 4060 ; for which we
should get A = 75^ as remarked in g 7. Can this distant point on
the curve be used to improve the formula?
1 1. Firstly, let us examine the consequence of aaauming the
formula still linear, and let us determine a and h in the expreaaioii
A = «+AP
80 as to satisfy the Sun and the mean of the stars ; that is;, put
53" = a ^ 6 X 4060 (the Sun)
8*'i6 = a + &x 311 (mean of stars).
From these we get b = cT "ov^^ a= aj ■ w
Supp. 1908. in the Epoch of the Sim-spot Variation, 661
This new formula
differs from the former
A2 = 4'''4 + o 012 P
Ai = 2-6 + o'oi8 P
fuUowB, for different values of P : —
P- lOO'^
200'^
300*^
400'*
500*^
600^
As- 5 '6
6-8
8*0
g'z
ro'4
ir6
A|= 4*4
6-2
So
9-8
ir6
13*4
Ai= +1*2
+ 0-6
00
-0-6
- 1'2
'VS
f Old formula
^^t seems doubtful whether our present material is sufficient to
enable u« to di«iTiminiite between these two formula^, for most of
the stare huve periods betweeti 200 antl 400 days. But we may
notice one other ivuppositioii, viz, —
12, Secondly, let us adopt the suLrjjestion of a curve of some
kind rather than a straight line. The appropriate iadicea for A
and P will be suggested by finding m in the formnla
A'" = P
for the large values of A and P» i,e, for the case of the Sun. AYe
have
wi=log P/log A = log 4060/log 55
= 3-6i/r72 = 2^T.
This suggests some formula such as either
A2=.a<P+p)
or (A + a)2 = 6P.
1 3, Determining the constants from the two cases of the Sun
Qd mean of the stars, we find for the two suppositions
A'* = 073 {P-220)
{A4-9T = o-94P
)f these, the former gives impossible values of A for periods below
220 days, and is thus unsuitable. The latter gives values of A for
different values of P, as below.
100"
200** 300'^ 400*^ 500''
6oo**
Ag^ 07 47 7*8 to'4 127 14 S (new formula).
Aj== 5*6 6*8 S'o 9'2 io'4 1 1 *6 (linear formula).
A^-Aj«^4-9 -2-1 -o'3 + r2 +2*3 -1*3^2.
These differences are larger than the former, and it seems probable
that we can discriminate even oow in favout ol l^e on^ti^lortTK^^.
«6S
Dt, J. Scheimr^ Researches on the Solar LXXitL 9,
The suu^spot muxima (and mioima) occur on the avenige
intervals of 11*125 years. But the individual maxima (ao
minima) show discordances which have been tabulated for 26'
periods by Wolfer, Analysing these by the p«riodo>;Tam inetbcxi
of Professor Schuster^ there are indications of two periodicities, one
of which the phase advances 53* pt^r [leriiid of i i J yeara, the
other of which ^the phase advances only 20". The cycles are coa
pleted in about 75 and 200 years respectively. The amplitude
each inequality ia about a year, but the accidental errors are so
large that either or both of these inequalities may be spurious.
The quicker moving inequality (s^^) can be brought into ]
with aimilar inequalitit'S for the long-period variable«; the I
fonniila connecting A (advance of phase in degrees per period) with
P (the period in days) being the simple linear formula
A — 4°*4 + o°'oi2 P.
The slower moving inequality (20*) may quite possibly b*?
analogies in the star«, but as yet the material is not sufficient (
declare.
Researehes 07t tfte Solar Constant and tJie Ternperafure
0/ the Sun, By Br, J. Scheiner, Assoc, R. A.S.
, In No, 55 of the Publications of the Astrophysical Observator
Potsdam, I have published an extended paper on this subject,
I should like to give a short report of the results to the reaclers
the Monihhj Notices.
The measures of the Son's radiation were made with the.
Angstrom Electric Coinpeosation Pyrheliometer, to which I ha
given a modified exterior form and a parallactic motion with cIim:
work. On eleven days in June and July 1903 I made a long st^rii
of observations on the top of the Gorner Grat in Canton Wallf
(Switzerland), from which I could derive the radiation of the 80J1
outside our atmosphere. Thii^ i>ait of the problem is the ma
difficult one, and, acirording to my view, it cannot be solved frr>il
measurements of the aohir radiation alone. From such observation
a portion only of the real solar constant can be obtained, becaua
only that portion of the loss by absorption in our atmosphere can
be calcuhited which is based upon the continuous increase of abttorp
tion with growing thickness of the atmospheric layer traversed bj
the radiation. With carbon dioxide and water vapour there exist?
lb nearly sudd^w a.V>^tvt\<ixv vw the highest thin layer* of the atmo
sphere, wk\t\v mv\?»»\ "^ \x^^*w.^ ^ ^ t:«w&\.i6jci\. \» Xa^ '^ded to the
Supp. 1908. Constant and the Temperature of the Sun, 663
result from the ratliation-curvea. Therefore this latter result is not
the sf>lar constant as generally supfHised, and I have chtjaeu for it
the term " StrahlungsconstaDte " or *' Constant of Kadiation."
From my observations on the G^Jtner Grat it amounts to i"95~2'02
gr. cat The remaining constant, which must be added to it for
obtaining the Solar Constant, can he found only from experimental
researches in the laboratory. To tliia part of the problem I have
devoted much labour in measuring the abaorption of carbon dioxide
and superheated virater vapour with varying depth of layer.
This very complicated it^search cannot he described in a short
abstract, and I must therefore refer to the orij^inal paper* The
result is that for reducing the Radiation Constant to the Solar Con-
stant there must be added for carbon dioxide 1%, for water vapour
7%, and for the ultra violet absorption i|%, whence the Solar Con-
stant for the unit of distance is found to be 1*22-2*29 ^* ^^^
with a probable error of 2%.
The constant of the Stefan law, which is ueceasary for calculat-
ing the effective temperature of the Sun from the Solar Constant,
I have ascertained by d liferent methods, and with the same
pyrheHoujeter, thus eliminating the constant error of the apparatus
which caantit exceed i per cent. The ^* black radiatiou'* of known
temperature was measured from blfick platinum, rendered incandes-
cent by an electric current, from light fiames of different thicknesses,
and from the artificial ** black body/' The latter results were the
most exact and the effective temperature of the Sun based upon
them was found to be 6ig6*-6252*.
Further on, I have endeavoured to calculate the real temperature
of the so!ar photosphere frum the effective temperature by oraployini-j
the known data on the abaorption of the solar atmosphere. Of
course this research cannot be of the same exactness as the foregoing
one, especially because the photosphere has no definite tempera-
ture, consisting as it does of layers of very ilitferent temperature.
Neglecting thu errors arising from our igiiorance of the structure
of the photosphere, its average temperature comes out as 7o65\
664
The Total Sdar Eclipse of igio May 8. LXFHIj
The Total Solar Edip9e of 1910 May 8.
By A. M. W. Downing, D.Sc, F,R.S.
This eclipae is observable in Taaniania, though not under very
favourable conditions, owing to the Sun's low altitude at the lime
of lotdity.
The particulars for llobart are given on page 444 of th«
Nautical Ahtiamte for 19 10, It will be noticed that the Sun mU
before ih© ending of the partial phase of the eclipse.
Port Davey, in the south-west of Tasmania^ i8, howeverj
more favourable station from which to observe the total phaje
this eclipse, the duration of totality there beinj^ half a minute k
than tite duration at Hobart Some particulars of the eclipse 1
from Port Davey are given, as an example of eclipse calec
on page 590 of the Nautical Almanac for 1910. For the
venienc© of ob^sei-vera these are reproduced here, and some additi
particulars added.
Port Davey. Ijmg, 146' o' E, Lot. 43" 22' S.
Si<tfidard Mean Tinu (lo** EaM)*
i1 h m ft
May 9342
9 4 M 55
9 4 15 as
Saij seta 958
First contact
Total Eclipse |
Aiifrle from
Nurth Poiul.
247'
5«
267
Verui
ays
With the existing errors of the lunar tables, the predicted 1
for the phases of the eclipse given above will be several second«|
too late. It maj he useful, therefore, to add the intervals iti
time from the instant when the cusps subtend a given angle at
Sun's centre to the commencement of totality.
le of Cu»p<.
TimflL
lefore (Hirotneiu^iiicnt
90
42
60
16
45
9
30
4
15
I
The Sun's altitude at the time of totality is 8',
Supp. 1908* Ferturbatiofts of Halleys Coniei in the Fast, 665
k
The Pmiurhaliom of Halhy's Comet in the Past. Fifth Paper.
The period B.C. 240 to a.d. 760. By P. H. Co well and
A, C. D. Crommdiii.
We have once more to commence by acknowledgment of the
continued assistance that we liave received from Dr. 8mart and
Mr. Cripps in the calculation of the mechanical quadratures.
Thii fourth paper of this series (M.N., May 1908) traced the
comet back to a.d. 760 June 10 (Julian day 1998810)1 the cor-
rected value of w at that epoch )>Ring 46"' 11 3. Hindis date for
L the previous paa^age is 6S4 Oct. 18, though the observed positions
Httre too va^nie to fix the time of perihelion within severnl days.
^Bfr. Kriobel has shown that this comet was also observed in Japan
^KM,N,j lxvi,j 2, p. 72) the date of first apparition, 684 Sept. 7, being
I in good accord with the date Kept 6 of the Chinese records; he has,
however, l>y a slip, ^iven Hindis date of perihelion passage as Sept.
1 8 instead of Oct. 1 8.
Uur coniputatinns indicate that Hindis identification is correct,
the calculated ilate being 39 days later than hia, which is a reason-
able discordance fur that remote epoch.
Venus
Earth
It
Jupiter
>i
*•
Siturn
It
II
Uraiitis
LfmltB of u.
0-30
330-360
0-30
330-360
0-90
90-270
270-360
0-90
90-270
270-360
0-360
Eevolutwn 684-760.
jdn.
dm.
K
- '002
-•006
+ *oii
- *002
4-I-137
4-148
-983
+ '02t9
-•0312
+ •0381
+ *0I»
+ 560
-523
+ 48
+ 34
-129
+ 54
' 56
+ 308
+ 31720
+ 636
+ 170
+ 612
- 466
7
4- 2S0
r
' days --
SinnH
+ •344
+ 44
+ 33»97
3, n m 684 = 45"'769, and period in
2759T, which brings us to J.D. 1971219
Taking n in 760 as 46" "i i
1296000 - 33197
45769
= 684 Nov, 26.
The observations will scarcely permit so late a day as this for
the perihehon passage. If we take the mean of Hind's value (Oct.
18) and our value Nov. 26 as the actual date, we must ta.k^ u \».
684 aa 45*137'
666
Messrs. CowM and Orommdin^
Lxvm.9,
Proceeding k> the revolation before this, an approximate com-
putation quickly showed that Hind's date 608 Oct. 19 was aboat
x^ year too late. Dr. Angstrom had already deduct from his
empirical curve that *' Fapparition pour Tann^ 608, prisentant
r^art le plus grand, est probablement douteuse." Every alteration
to Hind's dates that we have found brings the results into closer
accord with Angstrom's curve, a fact which renders its failure for
the next return more surprising. We propose examining this
question further in a subsequent paper.
The observations of 607 are iu a decided tangle ; it seems dear
that they refer to, at least, two different comets (some say that no
less than four appeared in this year). Halley's comet seems to
have appeared in the spring, and the date March 20 was selected
for the purpose of computing the perturbations.
Revolutum 607-684.
PUnet
Llmiteotu.
l.^
Jdt3.
\K
Venus
0-30*
+ •001
"
+ "28
i»
330-360
-•005
...
...
Karth
0-30
330-360
-•C07
+ 003
...
- 196
Jupiter
0-90
-•189
-452
-5954
»»
90-270
-•126
...
+ 4S77
>»
270-360
+ •491
-157
- 122
Saturn
0-90
-•051
- 37
-1438
>)
90-270
+ •062
+ 2044
M
270-360
-•185
+ 30
Uranus
0-360
+ •006
+ 80
Sums
651
Taking n in 684 as 45"737^ ^ in 6o7 = 45''-737, and period in
day8= ^ 5 =28350 days. Subtracting this from 197 11 99
(the aiioptfd Julian day iu 684) we obtain J.D. 1942849 = 607
March 26.
At this point we have somewhat varied the foimer procedure :
owing to the difliculty of deciding from observation the exact day of
perihelion in 607, we took the well-established return of 451 July
3*5f=«^-l^- 1^85969-5 as a starting-point and assumed in a pre-
liminary computation that the subsequent passage occurred in 530
November, in accordance with Hind. The verification of the date
530 November makes the revolution 451-530 the longest on record ;
it is about iViree moiv.\i\\ft \o\\^vit NiXvaw \^^^-\\\t^ ^t 1122-1301,
Qipp. I908« Perturbations of Bailey s Comet in ike Past. 667
ch are very nearly equal in length. Tlie adopted date is 530
" No vembe r 1 5 — J . D . 1914959.
On this basis the |jerLnrbationa were carried ftirward to 607,
and it waa found that nearly the same date was arrived at as in
the previous backward n^ckoning. The value obtained for n m 607
differa somewhat, but this is easiily accounted for when we note
that in the three consecutive returns of 530, 607, 684 the observa-
tions are so vague that there is an uncertainty of a fortnight or so
io the date of perihelion in each case. It m sufficient to know that
Hur comet is correctly identified in each year, and we must he
content witli this email uncertainty in the dates.
I Perturbations for the two revolutions 451-530, 530-607.
net. Llmiti of ii>
Earth
Japiter
Saturn
o- 30
330-360
o- 30
330-360
o- 90
90-270
270-360
o- 90
90-270
270-360
0-360
+ '018
- -013
+ '003
+ '003
- '2455
- '0134
4- '6501
--0077
-^ '0248
- -0047
-*ooi
Revolution 451-530,
Revolution 530-607*
+ 504
I'"- J
dui.
-IS9
-240
+ S6
- tot
+ 4
+ 84
-7179
+ 7852
- 164
- 223
^ 49
+ 10
+ 17
+ 020
- 007
+ '014
- 'on
+ 1 106
4- -222
- 734
•f '196
- -073
-h -056
+ *002
560
*^633
-348
-295
- 20 -
+ 392
+ 30974
•f 1969
+ «93
^ 549S
- 237
10
^5
Sums +'425 -683 -f- 950 ' + 791 - 58 +39324
For the revolution 451-530 we have the eqEation
— 2 ^^ — 28000, the ohserved period in days. Hence n at
n at 45 1
45i=44''-672, 71 at 530 -45'''097^
* For the revolution 530-607 we have the equation
— z_ 393 :t = period in days =27866. Addinc this to J.D,
m 45*097
^R*9'4959 w® obtain J.D, 1942825 — 607 March 2, and n in 607 =
^B45'''097 +"791 =45'''S88* As the actual date of perilielion in 607
^f Was probably at the end of March, we should have to diminish n in
' 530, 607 by about o''*o5, which would make a difference of only
I o 'oq between the value of n in 607 fuund by forward reckoning,
^■mnd that already reached by backward reckoning.
I^B In carryinrj the research still further buck, we have changed
I our method at this point, and used only the upproxiniate tables
J^^given on p. 45S of the present volume, combined witli the de^nite
^HiutegrAl table on p» 17S. This method Ib le8s accurate than that
^^hitherto followed, and we niUBt be prepaied iox ^Ti^xa o\ V«^ ^^
668
Messrs^ Cowell and Croinmelin,
LXVIIL9,
three months in the computed periodic time, coireapondiog to o''i5
or o'''20 in the value of n j but this is near enough to test the
accuracy of Hind's dates, which may be taken aa presumably ligltl
if tbey fall within two months or so of the time indicated I
method ; and, as a matter of fact» the results establish the 1 _
of all Hind's datea from a,d, 451 buck to b.c, i2» which is a'
satisfactory conclusion* Tn his whole series there were only fo
errors, viz. a.i>. 1223 (eleven months too late), a,d, 912 (fo
months too early), aak S57 (one month too late), a.d, 608 (0
and a half years too late)»
The research has been carried beyond the limits of Hind's liij
and one fairly certain return has been added, that of B,a 87,
description in Wdliamr^ is, ^* Id the second year of the epoch Hti
Yuen (t,e, B»a 87), the seventh moon (Angust), there was a comd
in the east." Perihelion would be B.c. 87 August or Septemb
Calculation indicates b.c, 163 June fur the preceding paasag
but no dehnite observation can be found in this year ; Pin<,'r>r b
severkd vague references to comets about this epochs but ih^y 11
so Tvantin^ in precision that no use can be made of them. Goii
back another rovmcl, the date b.c* 239 January was found;
think it Tint unlikely that the comet observed in the spring of
240 was Halley^e.
The discordance from our date is not gi'eater than we mig]
reasonably expect when the approximate method is used witho
c^iieck for two revolutions, and the cfiMnicteristic^ of the comet of B.i
240 are very like those exhibited by Halley's comet when pcrf
heliou falls about April
Williams says, '' In the seventh year of the reign of Che Hwang
(b.c. 240) a comet first appeared in the east. It was ailerwania
seen in the fii»rth. In the fifth moon (May) it was seen for 16 data
in the west."
For the two preceding passages there are no comets in either
Pingru or Williams that could possibly be Halley's. Three re-
volutions earlier, there is the following in Williama: ** In the
second year of the Emperor Ching Ting Wang (B.a 467) a comel
was seen/* This is at about the time wben we should exi
Haliey's comet, but the identity caunot become more than a
eorgecture.
To sum up, we have carried the comet with fair certainty hacl
to B.C. 87, with some probability back to B.C. 240; at this point
we are brought to a standstill by the complete absence of earl
observational materiaL
The perturbations for the different rounds are given in the
following tables. In each revolution ^^-^-^^ — i_Z^
n at begummg of rev.
perirtd in days; an equation which gives n when the period
a^umed, or which gives the period when the value of n at the en
of the period \a a.%s\im^^^ ws\d \\i^ \^\wa at the beginning deducs
by applying l\i^ calcut\aXA^ ^^T\<\\x\ift.xXsi^ ^\ '<v.
Supp. 1908. Perturbations of Halley's Cornet in the Fast, 669
• («' pi
- f<
.^ ^ « « « g I «
S 8 S ^ IS
+ 1 < I + + +
I
i" ■ p, " * *
+ 1 I < + I
I
g
I
<
*. i^ 'v s ^ ^ sB **
^ ." .*' ." r P p
? 2
«+ + +< +
-I '■M'e :^ ^ s ^ % z ^
is ♦ ^ rx lo vo
« «
I 5 .«« c!^
! S «• "^ i
+
0 • cT »C
2 rr> M
,-§
♦
.^
?8
.?
0
m
•
+
1
1 1
+
1
1
rn
a^
-8.
8.
4? g.
a
^
ao
s
5
a
« II
1 'A.
» 0
a
g. »
8.
a
• ^ -
1 ^'^
u
U'^
i
=
J
-
'
i 1'
>■
1
W If!
^ II ^ 5 l! 2
^ + + + + ( i
B '1 I s a; ^ *=
■9 'F !* ^ P P P
'2S
ft «
% 5 ? * <^
r> -f <*
+ (
n ^a nv
Si a TS
1 -n <ft
' + 1+4-1 I
d ^r ^ £ ^ 8^ s,
,5 p' n n 0 0 o
' '+ I V + I +
•?'^.
r + + + -h +
en 00 0
>♦ ts. m
'§ S J SI ^ s
t
+
^ i
if) M
-^ +
1
1 1
+
1
1
t
4 1
♦
?
3- 0'*
8
0 0
J
i^''
+
1 +
1
• +
,
0 ^£
• a
g.
i &
c«
i.
§
0
•0 ^^-s
a
V II
1 ?^
• 0
8.
PI
8.
a.
1 ■->
h
1 rii
1
;
r
s
1 -'"
•n
<JS
y «
\
b
670
trbations of Ballet's Comet m the Past, Lxviii 9,
Bt of beg. KDa «id. of Ber.
B.a tfi3 May » ; B,a 87 Aug, .5
a.0. 14» M*J IS I B^C i«3 Mi|«
All tf^f0FM =
Wapltor
/ Satan]
t,
,i
53, »^ *s*
■
;-
J-..
J*
;<..
K
>K
Jiipitcr
•
«
- ©0
+ 'a«o
-6^
i-73»i
-■090
-i^il^
'^
IT
90
- »7«
-■3*^
- 63
-1361
+ ■^54
- 39
+ n^
•t
STO
* 369
+-<»S4
+ '5
- ISO
-o^j
-650
+ ^^
5«ttifii
0
' ^
^■060
+ IS
-ifigt
-*-t<H
* 71
* *SS9
,t
9^
^ 370
+*074
^ 66
+ua4
-049
+ S»
+ ?M
> *^
^7^
- 360
-174
+ i«
^^ » 1
+■01 i
- 7*
- **
ftDOW
- »SS
-%,
+s#ss
+ .!IOJ
-Ss6
+iioaii
The date ilc. 2 40 ^[By 15 waa deduced from observation^ mi
from calcuktiiiTj, Tlie ilritr ciilcalated is a a 2^9 J.in. If t.^
mipposeaii error ci two months in tha wne dixection in each of the
eakodatiOQB of the bit two revohitionB (which is quite probable),
the discordance would almost disappear. It appears worth while to
calculate the three revolutions b.c. i 2 to b.o. 240 by .more exact
methods, and we hope to undertake this at a later date.
The following table gives the values of n calculated from the
above results for the different revolutions, and also smoothed values
resulting from the combination of values from consecutive
revolutions.
Perihelion
Fiaasage.
A.D. 684
607
607
530
530
451
373
373
295
295
A.D. 218
457371
45747/
45 -888 1
45*097/
45-0971.
44-672 /
44*54 I
44-98 j
45*19 I
44-845/
44-617!
45*845/
Smoothed n.
45*742
45'8i8
45-085
44-604
45*095
44715
Perihelion
Passage.
A.D.
218
141
•^
A.D.
B.C.
66
12
12
87
B.C.
163
45-88 \
45-86 /
45*817 \
46-39 /
46-3981
46-47 /
46-497 \
46-19 /
46-185 \
46-34 /
Smoothed n.
45-862
45*835
46397
46-483
46-1S5
TV:- iVW YORK
UBRARY
tftOt^ roc MD*roMi
Monthly Notices of R.A.S.
Vol. LXVflL Pukim 15.
:t ii
tM
f :
/■
j
Monthly Notices op R A.3. Vol. LXV
^B
III. Plate 16. H
O 1
u
1
/I
2
II
'II*
"
' J a
if
CL G
= c
'""tS^fX j
— 2 < —
o 5 =
r
a
51
/ /l:;i.
51
-21
t / it
' 2°
% ^
JV It
^^
*m \ I
o|
' / /
c i
t^/ ^ /
5 1
p ^
T. / /
n
- !/ ^
6S
7 •
C
"^ /
i
' F
- X
• • /
■
£y '
E
*9
5
5
/ / *
«4
Mr
'^d M*
^I K*^t
/ /i*
•^
/ / «
1
J?
1
r,
■
o
1
Supp. 1908, Diagrants, 671
^tXcup'am showimj tJie pamiioTis of Jupiter's Satellites F/, K//, and
VII I J from photof/raphi^ taken at the lioi/al. ObiieTvator^,
C^reenmeh^ during the opposition of 1907-8. {Plate 15.)
{Comitkunieated by Itit Astronomer Mojfat,)
^M The diagram is a graphical representation of the observations
^foi Jupitprs Satellites Vt* VI I, m\A VIII, tvom pbotoj[:^raplis taken
at tJie Royal Observatory, Green wicli, with Ibe 30-intli reflector
during the opposition ul 1907-S, |>rinted in the Monilihj Notices,
vol. Ixviii. p. 582, In all, ;^S photographs of Satellite VI, 2} of
Satellite VTI^ and 13 of Satellite VIII Itave been obtained.
The positions plotted in the diagram are the means when two
or more photographs were taken on any iiiglit, and the curves are
drawn throngh theae points.
For eoniparison, tbe orbits of the four inner large satellites are
shown, the major axes being plotted to scde, but the minor axes
intentionally exaggerated.
The apparent convexity of the path of the eighth Satellite with
regard to Jupiter ia due to the Earth's motion during the period
over wliich tlie obaervations extend (about three months)^ and the
consequent change in the point of view.
1908 Srjftember 2^,
I Diagram shoming tfte pomtimm ofSfttwm's Ninth Satellite — Phehe^
frojn photngmjilm taken at the Roijnl Oh^ert'^atory^ Greenmeh,
durimj the opijodtvm of 1907, (Plate 16.)
{C&mmummted bj/ the Astronomer MoyaL
This diagram is a graphical representation of the observations of
Sutiirn^s ninth Satellite^Pho.be — from 16 photographs taken at the
Royal Observatory^ Clreeinvich, with the 30-inch re!le(*tor during
the opposition of 1907, printed in the Monthly Notices, vol Ixviii.
p. 211,
The observed position of Phoebe with recspect to Saturn on each
day of observation is plotted in the diagram, and the curve drawn
through these points.
For comparison, the orbits of the inner satellites are shown
plotted to scale.
It may here be noted that during the present opposition (1908)
23 photographs on 15 nights have tdready been obtained up to the
present time, the first being on July 31, some few days before
Phffibe readied eastern elongation.
Royal Ohserm^jory^ Or^nwieh :
1908 September 25,
672
J/r. W. 5. Fmnl%
LXVIIL9,
The Eelation between Star Colaun and Spectra.
By W. S* Franks.
In a former paper on this auhject {Monihly Notices, June 1907)
I gave the result t>f an investigation iDto the relation between the
colours and spectni of 1360 bright stars, in both hemiapherfls;
the colours depending on the observationa made by members of
the Briiish Astronomical Association in England and Austmlii.
The stars observed in this country, from the N* pole to 25* south
declination, amounteil to 928 of the total number. The recent
publication of the lietnsed^ Harvard Photometry, which contains
over 9000 stars down to 6 J magiutude, has enabled me to carry
this inquiry a stiige further, ^^aking use only of my own colour
observations, contained in a MS. synoptic catalogue of 4175 stars
(which includes all my previous work in this direction), I liave care-
fully compared this with the Harvard revised spectra. The number
of stars between the K. pole and - 25", common to both lists,
amounta to 3497 ; wbii^h is nearly four times greater than the
B.A.A. total, and it includes starn down to 6| magnitude. ^^^^1
the colour estimates in my earlier catalogues were not expreaae^H
by Kymbols, like the B.A.A. and my later observations, I have
used the old notation in this paper — tlividing the colours into seven
groups, as here shown : —
r. White
Stars— including bluii.h'vvhrte and green ish-whi to .
2. Yflllowiah White ,» — a» iiiiportftut and Wflbnmrked daaa . V
3. Pale Yellow ,, ^-including a few pal« orauge-yeljow Y*
4. Yellow ,, — (normal tint) ifjcladi tig oraugv yellow aud full ^tdlow V
5. Pale Orange ,, —a distinctive group . . . . .Of*
6. Orange ,, — (nornml tiot) inclnding aUo full orange Oi*
7. Oratige Bed ,, — ^induding all nt ddy tints . . OrR"
The foregoing colours are distributed aa follows :—
Catour.
I, White
Number.
1083
PffToeDtagte,
310
2. Yelluwiah White
729
20-8
3. Pftle Yellow
782
22-4
4, Yellow
413
irS
5, Pale Orange
271
77
6. Orange
7. Orange Red
195
24
5^
07
ToXA -^Afyi
I
^1
^^^H
HH
■
^^1
l^^l
^^3
1
Jupp. ]
■
[908, Eelatio
n hetwetn Star Colmtrs ami JSpt
c^m.
673
J
1
Analysu of Colours and iSp€dra.
■
■
1
Table L
■
r
Sp^drum Ttjpes.
■
|o.
Oe 0«5B B fiiA BaA B3A B4A Bs^
L BBA BqA a
Aj¥ A3F A4J' A5F
ABF ^^H
1 -
-.■ 5 23 9
22 SS ... 49
69 21 605
79
18 1
28
2 ^
re....
...438
10 n 1 17
13 10 254
41 :
20 ...
63
2 1
U, 1
I 1
1 ... ...
3 2 38
12
4 ■'
J3
I 1
... ^
2
led ..,
* '
... ... ..
... .
I
1 10 26 17
32 too I 66
85 33 897
132 42 t
104
5
r.
^jpMfmm IVp*^
t:
TiQ F5O F7G FBG
0 O^K asK O8K K SsM K5M
Ma Mt> Mc
Mcl
N ToUl.
4 7.-2
7
...
... 1083
lu 134
5 47 I «S
37 3 10 ...
17 ... ...
... .
.. ...
... 729
L no
19 51 I 36
102 15 S8 ...
260 2 10
S
3 -
,.. 782
8
I 4 ... 6
22 4 35 I
274 7 25
20
6 ...
-• 413 H
age ...
2 ... I
13 3 24 ..^
155 2 27
30 1
4 ...
-^ 271 ■
... .,- ».. ...
2 2 9 ..
84 3 33
45 12 1
I
3 195 ■
ted ..
2 ...
4 ... ...
6
1 ...
3
24 ■
«.
29 1 1 1 2 63
1S3 27 168 I
794 14 95 109 ,
j6 1
4
ti 3497 1
L
^^E Summari/ 0/ Analysis,
1
■p
^"
Table H.
H
roup.
Spectram Type,
TOte. ^Jjf •
^»« YeUow. ^
Or. *>^»n«»'
'ssr
ToUl. H
mdOe
Brigbt line spec
tra
2
...
...
^1
esB
iDterraediate
5 4
I
...
...
^1
to B5A
OrioE typt
191 50
I
.*»
...
H
,» A4F
Siriua ,,
793 338
59
...
***
1190 ■
» F3O
aCsrinaa ,,
78 204
U3 9
•*.
434 ■
^5G
Procyon , ,
7 47
51 4
2
...
III ^M
ioGm
GapelU
9 69
242 68
41
'3
2
444 H
K
Atcturua „
17
260 274
155
84
4
794 H
Uid K5M Aldubaran „
12 32
29
36
...
to9 ■
toMd
Botelgeuae ,,
...
It 26
44
59
JO
150 H
F
19 Fijoinm ,,
3
8
^1
L
Total
1083 729
782 An
Itl
^<VS
**.
-y^pn H
674
Mr. W. S. Franks,
Lxyiu.9,
Pereentcfje of Coioum in each Group.
Tabli III.
Qroup.
White.
Yeldi.
Wh.
Pale
Yel.
Tellow.
PideOr.
Orange.
Ojgp
ToCiL
OdandOe
...
100 'O
...
...
...
...
lOOT)
OesB
50-0
40*0
IO*0
...
...
..
lOOT)
BtoBsA
78-9
207
04
...
...
...
lOOV
BSA „ A4F
66-6
28-4
5-0
...
...
...
10010
ASF „ F2G
180
47-0
33*0
2X>
...
...
...
10010
F5G
6-3
423
46*0
3-6
1-8
...
...
100*0
F7G to G8K
2-0
155
54-5
15-3
9'3
3-0
0-5
lOQlO
K
...
2-1
32-8
34"5
19-5
10 -6
0-5
loot)
K2M and K5M
...
...
no
29*4
266
33-0
...
loot)
Ma to Md
7 '3
17-3
293
39-4
67
loot)
N
...
...
...
27 '3
727
loo-o
C/assificnfum of Spectra in Tables II, awi IIL
Photo. Spei'tra.
Oa to Oe — Bright line spectra . . . . =
Oe5B —All dark linos (intermediate between 0 and B) =
B to D5A — Ik'lium ,, Orion type B
Visual Spectn
V.
BSA to A3F — IlyUro^en,, Sirius ,, A
A5F to K2G — do. \ intensity u Carinto ,, F
F5G — (Intermediate) Procyon ,. F5G
KSGtoGijK — Solar lines Cai»ella ,, G
K — " K" line intense Arcturus,, K
K2M and K5M — (Intermediate) Aldebaran ,, K5M
Ma to M«l — Banded spectra Betelgeusc,, Ma
V-I.
= Iff.
= Ih.
= I-IIo.
= I-II6.
II.
= II-IIR
= II-III6.
= III.
X
do. (reversed) 19 Piscium „ N (ruddy stars) = IV.
The last class (N) would be considerably increased but for the
ditliculty of photographing objects near the red end of apectrum —
hence tliey fall short of the number that can be observed visually.
A number of red and orange stars of 6i magnitude, contained in
my catalogue, are, from this cause, entirely omitted from the Ha^
vard spectra reaviYla,
Siipp. 1908. Belatimi between Star Colottrs and S^ycctra, 675
DedudionM from preceding Tables.
— Mcaeimum in wliit©, gradually decru^smg to piUe yellow.
B— ,» I, ,, (practically 79 per evil t.). Th6 ivhiie^ slUn.
A — ,f also «| but less wh. and more yekh. wh» than B.
F— ,, p, yelsk white, but the pa le-yellow not fur behind
F5G — ,, between yelah. wli. ami y^le yel. — the latter slightly inexcoa^
G — ,, in pale yellow — very prouoancedl.
li — ^^ between pal« yel. and yellow — ^nearlj equal.
KaMand K5M ,1 pretty evenly distributed between yel., pale or.p and orange.
M— ,, in orange, bat \m,]e orange not Far behind*
^_ N — », orange red — very pronounced.
^f The sequence of rohurs corresponding to the sequence of the
r gpectra h thus immistakithly intlicated. But in the A chiss there is
' a defimte immher of p>ale yellow stars; thwir occurrence is too frequent
and regular to be accidental; ihey show an increase in frequency in
, the regions where coloured stars are predominairt. Likewise there
I is a still larger fraction of white stara in the F class — contrary to
the normal This serves to emphasise the fact that in some cases
two stars of exactly the same colour viriually are nf different spectral
1 types — some noteworthy examples of which have come to light
during the present investigation. Anil, conversely, some stars of
identical spectra differ very perceptibly m colour — whatever the
cause of such discrepancy may he. But perhaps these exceptions,
which after all are not very numerous, merely point the rule which
governs the relation between colour and spectrum in the great nm-
jority of cases. If I have succeeded in establishing this connection,
it miy he also a plea that star colour observations do possess some
value ; and I sluill consider that these thousands of independent
eatimatea, which have so long lain dormant, were not altogether
made in vain.
Uo^idQe: 1 908 August 12.
676
Note on T CephM.
Lxrm.
Note on Y Cephei, By Rev. J. G. Hagen, SJ.
{CimimunicaUd in a lei&er io the AMrmu>iner Ma^L)
**ThB advance prints of your Astrographic Plates 5619 ftn
6983, which you kindly sent nie for the examination of Y Cephe
and its surroundingB, have enabled m« tu measure the addiiionAlr
stars to tfie Atlas Chart of this variable which were invisible in tlie
I24nch refractor. TImy will be recorded in the Catalogue sheet
No, 188 of series vi.» witli due acknowledgment.
"Sinco the magnitudes of this series are all reduced to tli*"
Harvard scale, it in well to jiut the magnitudes of Y Cephei, ^
shown on your plates, on record for future corrections of the
elements of variation. The folhjwing extract from the Catalogue
will designate four comparison stars : —
No. 3.
Aa =
-0 20
AS-
'irs
H»P, 87
letUfTC
4.
t,
-^3 ^
M
-lai
M S-8
•♦ d
37*
f 1
0 0
M
- rs
M 127
», 9
40.
t.
+030
,,
10
M lyi
.. T
Your plates give the following estimates, which anyone
verify :—
PI 36i9»
1897 Sept. 9 :
c2Y4d,
Uj^a. 87 H.P.
M 69831
190S J»n, 12 :
MVit,
II U'o ..
**The provisional elements of variation give the foUowiii
corresponding epochs of maxima : — -
Max. 1897 Sept. 24 = Plate 3619 + IS days.
„ 1907 Nov. 26 = „ 6983 - 47 days.
*' The first plate agrees well with the computed maximum an«l
with the remark of Ceraski {AN^ 3644) that the brightness of
waH diminishing in October 1S97. The second plate, howeve
will probably demand a conection to the assvtmed elements (J.
3744 and V.J.S* 41, page 317), as it is unlikely that the ^fci
should have diminished in brightness by 4^ magnitudes in 47 days
Eomf: July 22, 1908.
Siipp. 1908.
Correeliom.
CorrecUom to PrqfeMor Tumer*$ paper on Corrdaiion^ —
(.l/.A% 1^551).
An unfortunate »lip on p. 551 has b«en kindly pointed out by
Mr. J. B. Dale.
Both €^J^ and trjj should have been divided by 5» the square
root of the nuiuber of observations ; bo that
and
r = *72 imiead of *o8.
The correlation between A and B is therefore by no means
negligible m stated on p, 552, antl again on p. 545.
The two " regression lines " are
(A.7) = r.^(B-7) and (B-7) = r,^(A-7)
or
(A-7) = a(B-7) and (B-7) = (A-7)
which are the two solutions mentioned on p» 545 obtained by
^'roupiog rtt!Cordiiig to B and to A respectively.
The example was subsidiary, and the 4*lip doea not aflfect the
main argument; but it la not easy to understand how so gross an
error passed undetected, H. H. T*
ErrcUa in Mr. J, J/. Baldmn*8 pa^mr on Neptune,
p. 6i$» line 26^ for include recul exclude,
p. 620, line 4, for showing in rectd showing an.
t^
LIST OF ADDITIONS
TO THE LIBRAKY
OF THE SOCIETY
JUNE 1907 TO JUNE 1908.
An att9Ti§k (*) indieaisi that th* ^gt^rk it aft *ice$rpt.
Abbadia^ ObBervatoire :
Olkservationa faiies au cerde meridian en 1905-6, Tonio
5» 6. PubJines par A. VerscbaiFeJ.
(Obgermiory.) 4to. Hen day e, 1907
Acta Mathematical Zeitscbrift, herausgegeben von G. Mittag-
Leffler Band 31, pt. 1-3,
(lunior and Horrox Fund.) 4to, Stockbolni, 1907-1908
•
Adelaide, Government Observatory :
MeteuroKigical Observations made at the Adelaide Observa-
tory and otbor |ila<-'e.s in Soutb AustraJia and the Nortliern
Territory (hiring the year 1905, under the direction of Sir
Charles Todd.
(ObsenHitortj,) fob Adelaide, 1907
Algiers, Observatolre :
— — : Carte pboi^jgraphique du Ciel Zone - i*, + i% «f 3", +4*.
(35 cbjirtB.)
(French Minister of Public Instrudion,)
Allegheny Observatory :
: ^^fi^cellaneouH scientific paperi? ; new serie^j No, 18-30.
By Fnink 8ehlesinger» Director.
(iJhmrvalory.) 8vo. Nt)rthtield, Minn., 1906-1907
; Publicatioiiijt. Vub i. No. 1-5,
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American Academy of Arts and Sciences : *ee Boston.
American Journal of Mathematics. Edited by T. Craig and
8. Newcomb. Publisbed under the auspices of the Jobna
Hopkins University. Vol 39, No, 3 — Vol. 30, No. 2,
{Editors,} 4I0. li%V<vmcit«i^ v^^^-x^^"^
[70]
LiH of Additiofu
American Journal of Science, Editor E. S. Dana [and otbeis}
Fourth series, Vol. 24, 25 (No. 139-150).
{Editoi'8,) SvQ. New Hiiven, t 07-1908
Amsterdam, Koninklijke Akademie van Wetenschappen :
; Verhaudeliugen (Eerste Sectie), Deei 9, No. 4.
{Academy.) 8vo. Amsterdam, 1907
: Verslagen van de gewone Vergaderin^eii der Wis- en
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: Proceedings of the aection of Sciences, VoL 9, [>t. i and z,
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: Jaarboek, 1906.
{Academy,) 8vo. Amsterdam, 1907
Antwerp, Soci^t^ d Astronomie :
*- — : iJazette Astrunojiiiqtie, Auiit^e i, No. i-^.
(Socieiij,) 4 to. Aijvers, 1908
; Deiixicme (et Troisieme) Rapport aur Texercice 1906, 1907
{Society, ) 8vo* An vers, 1907-1908
Arcetri, Reale Osservatorio :
Piibblicazioni del U, Istitnto di atTidi superiori pratici e di
ptjrfeziojiitmento, fasc. 23, 24,
{Ob&e}-vatory.) 4 to, Firenze, 1907
23. A. Abetti. Osservazioui nstroDomuobe fntte . . . i()o6.
24. B. Vinro. », „ ... 1905-6.
Archiv fur Optik. Inteniationales Organ fUr experimenteile,
theoretische und techntsche Optik » , . Herausgegeben wa
A* Gleichen, Bsind i, Heft i-6»
{Tumor and Horrox Fund.) 4to. Leipzig, 1907-1908
ArrheniuB (Svante) :
Worlds in the muking; the evolution of the univerw.
Translated by B, Borns.
{Library Fund.) 8vo. London & New York, 1908
Astronomical Herald (the). Published by the Astronomical
Society of J at ran [in Japanese], Vol 1, No, i, 2.
(Socuifi/,) 4 to. 1908
Astronomical Journal Founded by B. A, Gould [edited Hy
S. C. Chandler]. Vol 25, 26 (No. 595-601).
{Editor.) 4 to. Uoaton, 1907-1908
ABtronomische Mittheilungen,
heruuagegebeu von A. Wolfe r.
(E^iitor,)
Afitronomisohe Nachiichten.
maehi'i' : herftusgegebeu von
(No. 4i8^-^2SiV
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Gegriindet von Rudolf W»jlf :
No, 98.
8vo. Zttrich [1907]
Btj^'mtidet von II. C ScUu-
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<«i ."^xA^ \t^-^- 1
qoS j
to the Library^ 190 7- 1908
[71]
ABtronomische Nachrichten — continued :
: Astronomic he Abliandlungeti, als Erganzung^iliefte zu den
Astronomiachen Nachrichten, hefausgegeben von H. Kreutz-
No. 13-15^
(Editor.) 4 to. Kid, 1907-1908
13. DefinitiTe orbit of Comet 1S26 11. E. B. Cowley and L
Whitasid*;
14* Beatimtnung der B$hn des Kometen 1S25 L H. BoegehoM,
Detiuitive orbit of Comet 1886 111. CArolioe E, Furness^
etc.
15. Allgemeine Japiter- aud Satiini-St*3rungflri des Pknetan (447)
Valentine. Hans Ost€D«
Astro no misch© Bundachau HeraEsgegeben vcm der Maoora-
Sternwarte in Luss in piccolo {Oest«rreicli), unter der verant-
wortlichee Redaction von Leo Brenner, Band 9, io (Heft
87-96).
(Turnor and Horrox Fund.) 8vo, Triest, 1907-1908
Astronomisoher Jahreebericbt. Begriindet von W. F.
Wislicenn^ : mit Untersliitzung der ABtronomiAchen Gesell-
schaft herausgegeben yoti A. Berberich. Band 8, 9, enthalteud
die Literaturdee Jahres 1906, 1907.
(Editor.) 8vo. Berlin, 1907-1908
AstropbyBical Journal (the). An International Review of
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Hale [and others], VoL 25, No* 5^'Vol. 27, No, 4,
(Editorii.) Svo. Chicago, 1907-1908
Athenaeum (the). Journal of English and foreign literature,
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(Editor.) 4U), London, 1 907-1908
Basel, Naturforschende Ghesellschaft :
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{Societi/,)
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Jahresverzeiehniss der achweizeriscben Universitatascbriften,
1906-1907.
{Universit!/.) Svo, Basel, 1907
Batavia, Koninklijke Natnurkxandige Vereeniging in
Nederlandsch-Indie :
Natuurkiindig Tijdachrift voor Nederlandscb-Indit', Deel 66
(Serie lo^ Deel 10),
(Society,) %No,'^^^JK^\s^ ^^^"v
[7^]
Li^t of Addiiums
Batavia, Koyal Magnetical and Meteorological Obse
tory :
; Observations . . , published by order of tbe Govemme
of Netherlands India. Vol 28, 1905, and Appendix 1-5
(Oherifaiory.) 4 to. Batavia, 19Q
; Regenwatttnemingen in Nederlandsch- Indie, Jaarguog 3^
1906.
(Observatory.) Svo. Batavia, 19a
Berlin, Deutsche phyeikalieche Gesellechaft :
*-=— • IHe Forlschritt^ der Phyaik im Jahre 1906* Jafirgajig 61
dritte Abiiieiliing, enthaltend kosmiache Physik, n
von Richard ABsmann.
(Sort>hj.) 8vo. Braunschweig, 190^'
; Dia Foitschritte der Phyaik im Jahre 1907. Halbmoo*
atliclies Literutui-verzeichniBa, Jahrg. 6, No. 11-24.
(Sociehj,) 8vo. Braunschweig; 190;
: Verhandlungen, jahrgang 6, Heft 23-24 ; Jahrp. 7-9
Jahrg. 10, Heft 1-7.
{Society.) 8vo, Berlin, 1904-190$
^
Berlin. Koniglich AstronomiecheB Rechen-Institnt :
; Bcrhner Astrouomi.sclies Jahrbuch fiir 1909; mit Ang»b
fiir die Oppusitionen der Planeton {1M569) fiir 1907, herAU
gegeben . . , unter L«itung von J, lituschinger-
(Ina^tiinte.) 8vo. Berlin, 1;
: Ditto , , , fiir 1910, mit Angaben fiir die Oppositionen
Plaiieten {[)-(6oi) fiir 1908.
{Inatituit,} 8vo, Berlin, 190S
: YeroiTentlichuugen. No, 33, 34.
(Institute,) 4to, Berlin, r907-i9o&
33. J. Peters. Ni'Ue FundameutalkAtalog des Bcrli«er Astro
nomi^chen Jithrbachsi . , . 1S75 und 1900.
34. J. BuuBchingrr [etc.], G^uaherte QppoRitiotjs*fiph«xii6nU<o roa
32 klpiii«[i Planeteti, 1908.
Berlin, Koniglich Preussisobe Akademie der Wissen-
schaften :
: Abhandlungen, 1907.
(Acoilemy.) 4to. Berlin, 190^
: Sitzungsberichte, 1907, No. 23-53; i9oSf No. 1-22,
(Academy.) Byo, Berlin^ 1907-H
una »
Berlin, Vereinignng von Prennden der Astronomie un^
kosmischen Physik :
Mitthailungcn, Jahrgang 1 7^ Heft 5 — Jahrgang 1 8, Heft 4
{Turnar and Horrox Fund,) 8 vo. Berlin, 1907-190$
Bigelow (Prank Hagar):
*Stud\ea viViL iW iWtisnidYiiatiiics of the atmosphere.
(^Author,) ^X.Ci,^^^fiBMM^JC«^^ ^.qC
i
to th£ Lihrary^ 1907-1908.
[73]
Binmngham and Midland Institute Scientific Society :
Records t>f meteorological observatior^s taken at the Obser-
vatory, Edgbaston, 1907, by Alfred Cress welt
{Society.) 8vo, Birmingbara, 1908
Birmingham Natural History and Philosophical Society :
Proceeiiings, YoL 12, No, 2.
(Society,) 8vo. Biraiioglaam, 1907
Boddaert (D,) :
"•Misare tiiagitettche nei Dintonii di Torina
incliiiaziotie.
Declinazione e
{MoncaHeri OhservaioryJ)
4to. Torino, 1907
Bohlin (Karl) :
t^- — ^ : *0m tillaoipningeu af Laui bertha Lag inora den celesta
fotunietrien,
(Author.) 8vo. Stockbolm, 1900
: *Beobachtungeiic1erBi*»lidoa, 1904; nebst einerallgemeinen
Methode zur Bestimmung des Kadiunten wines Stemschnup-
penfalles.
(Author,) 4to. Uppsala & St'^okliolm, 1905
: *I)er zweite iSternhBufen im Hercideft, Messier 92,
^L (Author,) 4to. Uppsnia & Stockholm, 1906
^ : *Uber die gegenseitige Verteilung tier Pole der Doppel-
^B eternbabneii, der Milcbstrasse, des 8 oniiensy sterns^ sowie des
^^M Androiueda-Nebels.
^H (Author.) Svo. Uppsala k Stockholm, 1907
^B-^^ : *Ver8nch einer Bestimnnuig der Paralkxe des Aodromeda-
B Nebels.
^B (Author.) 4to» Uppsala tfe Stockholm, 1907
^B5hn (Josef G-eorg) :
I Die Kutjst-Ubren aiif der k. k. Stern warie zu Prag . , .
. herausgtgebeu von Professor Dr. Ladialaua Weinek,
] (Prwiue Ohsm^vatoTif,) 4 to. Prag, 1908
w
Bologna, Os^ervatorio della R. University :
: ^Osservflzioiri meteorologicbe delT annata 1906.
(Observatory.) 4to. Bologna, 1907
: *Sulle condizioni dell* Osservatorio . . . progetto di una
nnnva Specola, M, Rajna.
(Observatory.) Svo, Bologna, 1906
Bologna. Reale Accademia delle Scienze dell' latituto :
: Mernorie, Sezione delle scienze Jisiche e matemattche, Serie
6, Tonio 3.
(Arcfieiny.) 4to. Bologna, 1906
— : Rendiconto della seasioue 1903-1906. Nuo%''aSei'ie<»VoU \ci,
(Jmdemi/,) ?>^o* l^Vx^^ \<^^
L74]
Li§i of Additiom
Bombay Branch of the Royal Asiatic Society
8 TO. Bombaj, 190$
4 to, BonOi 1
Journal, Vol, 22, No. 62.
{Society.)
Bonn, K5nigliohe Stemwarte ;
Veroffuntlichungen . . * berauagegeben
Kiistiier. No. 10.
{pbdenxU&nj.)
F. K^itaer, K^Ulog von 10663 Stcraen.
Bordeaux, CommiBsion M^t^orologique dR la Girond©
Observations pluviozuutriqued et thermometrique« faiWi
, , . . de Jain 1906 ^ Mai 1907,
{Bm^deaux Obiervatonj,} Svo. Bordeaui^ 1901
Bordeaux Observatoire :
: Aiiiialas . . . publi^es par L, Picard, Tome 13.
(Ohservaioiy,) 4 to, Paris et Bordeaux, 1907,
: Carle photograpbique du CieL Zune + 16* (15 cbarts).
(Frendi Mirmter of Public Jn$iructum.)
: Cntalogue pb olograph ique du Ciel ; Goordonne^ss rectiiigne
Tome 2, faac, t, zone +15° a -¥ ii' i faac. 2, observations'
d'Eroa.
(ObserfcUory,) 4t^. Paria, 1907
Bordeaux, Soci^t4 des Sciences Physiques et Natorelles :
Proct^s-verbaux des acaiices, anuce 1 906-7,
(Societi/,) 8vo. Paris et Bordeaux, 1901
Boston. American Academy of Arts and Bciencee
; ^Memiiirs: Vol. 13, No. 5.
{ Academy,) 410. Cambridge, Mass., 190I
: Prooeediiigs. Vol. 42, N08. 27-29; Vol. 43, Nos. i-t6.
{Acoflemy,) 8vo. Boston, Mass., 1907-1 90S
Bouchet (Ulysse) :
HL^mt^rologie, Ott trait^ pratique complet des calcndrien
Julien, Givgorien, Israelite et Muaulman; avec lea regit
de Tancieii calendrier Egyptien.
{Lilrrary Fund,) Svo. P^ris* 186S'
Brisbane, Boyal Geographical Society of Australasia :
Queenaknd Geographical Juurnal (New Series), aesaion li
1 906- 1 90 7, Vol 22.
(Socwtrj,) 8vo. Briabane, 1907
British Association for the Advancement of Science : |
Repurt of the 77th meeting, held at Leicester, 1907
(AsftiKiaiion*) 8vo» London, 1908
Brousseaud et Nicollet
^Mcmoire sur la mean re d'un arc du parallMe mojen entre
1
to the Library^ 190 7- 1908.
[75]
Bro"WTi'9 Nautical Almanac, Harbour and dock giiide, and
" advertiser, aiid tide tables for 1908.
(lCdifo}\) 8vo. Glasgow, 1907
russelFi, Acad^mie Royale des Sciences, des IjBttres et
des Beaux- Arts de Belgique :
- — : BLillethi de la claaatj dea sciences; 1907, No. 2-12; 1908,
No, I, 2.
(Academy,) 8vo. BruxeUea, [907-1908
■ : Classe des Sciences! : M4moires (Collection in 4to). S^xie 2.
Tt»me I, frtsc. 3-5.
{Aewlemy.) fto. Bmxelles, 1906-1907
Aunimire, annuB 74,
(Acadejuij.) 8vo. Bruxelles, 1908
B6els, Soci6t6 Beige d'Astronomie :
Bulletin . - . Gomptes reiidus des stances mensuelles de la
Society, et revue des sciences d'observation : aatroiiomie,
ni^teorologte, geodesie et phyeique du globe. Annee 12,
No* 6-12 ; Aiiitee 13, No. 1-5*
(Society.) 8vo. BruxeUea, 1907-1908
Bryant (Walter William) :
A History of Astrouomy,
(Meihuen d& Co.)
8vo» London [1907]
Budapest, Kbnigl. Ungarische Reichsanatalt far Meteoro-
log^e und Erdmagnetismue :
Jahrbticker. Band 34, Tbeii 4; Band 35, Theil 1-3.
(Ifisiifuie.) 4U). Budajjeat, 1907
Budapest, Magyar Tudomdnyos Akad^mia :
: Alruaiiacb, 1907.
i Academy.) Svo, Budapest, 1907
■ Matbematikai os termteetttidomanyi Ertesito. Kotet 24,
{A*^ivhmjf.) Svo, Budapest, 1906-1907
: Matbematikai ^3 tenneszettudomanyi Koilemenyek. Kotet
29, I, 2.
r (Academy.) Svo. Budapest, 1906-1907
: Mathematiacbe und naturwisaenachaftliche Berichte sua
Ungarn. Band 23,
(Arademy.) Svo, Leipzig, 1906
: Rapi^ort aur les travaui de f Academtehongroieedes Sciences
en 1906, par G. HeioriclL
(Academy,) 8vo, Bud 0 peat, 1907
Biilletin A&tronomique. Fonde en 1884 par E. iMonchez et
F. Tis3erand. PublitS par rObservatoire de Paris. Tome 24,
No, 6-12 ; Tome 25, No. 1-5.
(Tumor and Horrox FutuI.) %^o, 'P^.m, x^^o'^-v^^
f76]
LiH of Additions
Bulletin des Sciences Math^matique^. Rc'digt^ par G
Darboiix et J. Tannery, 8ta-ie 2. Tmue 31^ No. 6-12 : Too
32, No. 1-4.
(Editor^,) 8vo, Pans, 1907-19
Bumbam (Sherburne Wesley):
A General Ciitalogue of Double Stars witbin lai" of the
nortb pi)le.
(Author,) 2 vols. 4to. Washington, 1906
Burrau (Cail):
Tafelti tier Finiktioueii Cosinus uiid SmuA ; mit den DaluHichi
acvwobl reellen als rein ima^^mareo Znbleii als Argoiui
(Kreia und Hyperbelfunctionen).
{Ttumor awl Honox Fund,) 8vo, Bt*rliii, 1907
Calcutta, Afiiatic Society of Bengal :
- — : Jouniftl and Proceedings, VoL 2, No. 10 j VoK 3, No. 1
(Soeieif/.) Svo, Calcutta, 1906-191
: Memoirs, VoL i, Supplement; Vol. 2, No. 1-4.
{Socieit/.) 4to, Calcutta, 1907
Cambridge Obeervatory :
Annual Report of tbe Observatory Syndicate, 1906-7.
{Observatory,) 4to. Cambridge^* 15
?o^
n
?^1
Cambridge Philosophical Society :
: Proceediugs, Vul, 14, pt. 2-4,
{SorieiyJ
TransactiouB, Vol. 20, pt. 13-16.
8vo. Cambridge, 1907-1^
{Society,)
8vo. Cambridgep 190 7-1 g
Canada, Department of Marine [etc.] ;
Report of tbe Meteorological Service of Canada, by K
8 tup art, Director. 1905.
{Department^) 4to. Ottawa, i^
Canada, Royal Society :
FroLeediiigs and Transactions,
{Soeieif/,)
Second series, VoL 12, 1906,
8vo. Ottawa [Montreal], 191
Cape of Good Hope, Royal Obeervatory :
-! r Anjials, Vol. 2, pt. 5, 6.
(Observatory.) 4to. Edmburgb, 1907
Vol. 2j pt, 5. Rtiinlts of .Meridian Ol^aarvationa . , . iSS|-*^^
,^ 2, jj 6, Occultations of Stars by the Alooh , • , 1^^96-1
: Catalogue of 1680 stars for the equinox 1900-0,
observations niaiie . . . during tbe years 1905- 1906, cm
the direction of Sir David Gill, . . . with introduction
(^Obaer calory,^ *^.'^Ax\j}:»\m<^1l, i9<
t
.07
to the Library ^ 1 907-1908,
[77]
Cape Town, South African PhiloBophical Society ;
Transactions, VoL 16, pt 4, 5; Vol 18, pt. 1-5.
{Societf/.) 8vo. Cape Town, 1906-1908
Cardiff, Astronomical Society of Wales :
The Cambrian Natural Observer. New series, VoL 9 ;
Vol. 10, No, I, 2,
(Society,) i6mo. CanUff, 1907- 1908
Catania, Reale Osservatorio ;
Catalogo Astrofoto^rnJico, 1900*0; Zona d\ Catania, fra le
decUnazioni + 46* e -f 55°* VoL 5^ pt. 1 .
(Obseruaforf/.) 4to, Catania, 1907
Catania, Society degli Spettroscopisti Italiani :
ili^morie . , . raccolte e pubblicate per cvira del Pjof. A»
Hiccu. Vol. 36, No. 6-12^ VoL 37, No* 1-5*
(Sttciehj,) 4to. Catania, 1907-1908
Ceraski {Wm) :
Un oculaire pour I'^tude d^tailliie des taches solaires.
{Auihoi\) 4to, Moscou, 1906
Charli^r (Carl Ludwig):
Die Mechauik des Hiiiimela : Vorlesungen. Band 2^ Abth. a.
{Turrmr and Hon'o?r FniuL) 8vo. Leipzig, 1907
Chatham, Royal Engineers' Institute :
The lioyal Engineers' Journal, Vol 6, 7.
(Indiiufe.) 8vo. CLathani, 1 907-1908
Cherbaurg, Soci^t^ Nationale des Sciences naturelles et
math^matiques :
Muinoires, Tome 35 (4me eiVie, tome 5).
(Societt/,) 8vo. Paris et Cherbourg, 1 905-1906
Ciel et Terr«. lievue populaire d'astronumie, tie meteorologie et
de physique du globe. Annue 28, No. 8 — Annt'e 29, Ko. 7.
{Twnor and Horrox Fund.) Sva Bnii^jlies, 190 7- 1908
Cirera (Bicardo) et M. Balcells :
— : ^Etjtndio de una recipivto perturbacitin cosmica registrada en
el Observatorio del Ebro,
(AiMont.) fol 1907
— : *Ke marques sur le rapport entro Tactivitc solaire et lea
perturbations maguetiques,
(Authurs,) 4lfs. I'arifl, 1907
— ■ : * Etudes den rapports entre 1* activity solaire et les vwiiiitiima
niagnrtiques et tdectriques enre^nstrees k Tortose (Espagne)*
(Authors) 4 to. Paris, 1907
Colorado College Observatory :
Semi-aniiUid Bulletin, Science Seriea. VoL 11, No. 51-53.
{Observatory,) 8vo, GoVQiaAft ^^Tvck^?^^ ^'^^^l
[781
Lid of AddiHam
Copenhagen, Kongelige Danske Videnskaberaes Selaiktib :
— ^ • Oversigt over det K. Dauske ViUeriskabemes SeUkabi For-
haiidliijger. 1907, No. 2-6; 1908, No. i.
{Society.) 8vo. KjbbenHavii, 190 7-1 90S
: Skrifter, iiaturvidensk. og matbematisk Afd. : 7te Bmkke,
Bd. 5, No, 2', Bd. 4, No, 1-4; Bd. 5» No. i.
(Society,) 4to. Kjobenhavn, 1907
Craco^w, Acad^mie des Sciences :
: Bulletiti Ititernational : Comptes rendus des st^itnces, 1907,
No. 4-10: 1908, No. 1-5.
(Acndeini/,) 8vo. Cracorie, i907-t9oSj
; CaUlo^nie of Fultsh Bcientidc literature, Tom. 6, No, 3, 4J
Tom. 7, No, i<
{Acculeiny,) 8vo, Ktukdw, 1906-1907
Darwin (Sir George Howard):
Scientilic Papers, Vol i,
( A u th or. ) 8 vo, Ch m bridge, 1 907
Oce«ino tides &nd luimr dUturbKiioc of gruTity.
De Sitter (William):
*0n the masses and elements of Ja|>iter*4 satellites, aud the
nmss of the sysitem. [2 papers,]
(Auihor.) Svo. Amsterdam^ 190S
Deslandree (Henri);
: "* Hecherclies sur ratniosphere solairft et appareils euregUtrenri
d^s cotif^hes de vapeura Buperpr»8<^s qui la ooiiipoaent,
(Author.) 8vo, Paris, 1905
: *Appftreils euregistreurs de ratmo«ph^re 8olaire.
(Author,) 4 to. Paria, 1 906
: * Hist I lire des idees et des recherches sur le soleil, njv^^latioo
lecento de ratmosphere de I'astre.
(Author,) 8vn, Paris, 1906
: ''*"MtHhodes pour la recherche des particules lumitieuaes
m^bje« aux gaz de la chrotnosphHre et des protuberances
solaires : appjtcation pendant Teclipaa de 1905,
(AutlLor.) 4ta Paris, 1 906
; ♦Methodes pour la recberche, en dehors des ech'psea, des
fimas de particiiles brillantes, in6k^es aux gas et vapeuradsus
la partie basse de Tatmosphore sokire.
(Author.) 4^0, Paris, 1906
: *Enregistrement de la surfaee et de ratmosph^re ftolaire I
robservatoire de Meudon.
(Author:) Svo, Paris^ 1907
: *litude dea variations du rayonnement solaire.
(Author,) 4^0. Paria, 1907
Deslaodres (Henri) et L, d'Azambuja:
♦Keclit!Tclics sur i'litmosplu're solaire ; vapeurs k raies noireact
( Author .> ^N^.^%xN^ vcv:,^
'.4
7
4
to the Library^ 1907-1908.
[79]
ealandres (Henri) et G. Blum:
*Pljotograpbies il#>8 protuburancea holaires nvBc dea ^crana
coluri'B Jans recli|)se du 30 aotit, 1905.
(Author,) 4to, Paris, 1906
Dictionary of National Bivgr&phj \ Index and Epitome*
Evlited by Sidiiej^ Lee. Second edition.
(Tuimor ami Horror Fumt) 8vt». London, 1906
Donitch (N,):
*Obsr«rvations de 1 'eclipse total du Soleil du 29-30 aoiit,
L 1905.
^H (Author,) 4tn. St Ptjtersbourg, 1907
^■Dublin, Royal Irish Academy :
^P Proceed nigs, third series (SectioD A), Vol. ay. No. 3-9.
(Acafhrnp.) 870, Dublin, 1907- 1908
Dublin, Royal Society :
: Scieiitilic Proceedings. New series. Vol. ]i,No, 16-20.
(Socuty.) Svo. Dublin, ^9^1
: ScientiHc TmnsactionB. Series IL Vol, g, pt. 6.
{Society.) 4k). Dublin, 1907
Dun^r (Nils Christian):
*Ul>er die Hotation der Sonne. Zweite Ablmndlnng.
(A uih tjr. ) 4to. U pjsala [ 1 906]
Edinburgh, Royal Observatory:
Ei^dittjeiith annual report of the Aatronomer Royal for Scot-
land, 1907-8.
(Obsermtory,) Svo, Glasgow, 1908
Edinburgh, Royal Society :
^- ■ : ProcHerUrige, VoJ. 27, pt. 3-5 ; VoL 28, pL 1-4.
(Societtj,) Svo. Edinburgb, 1907- 1908
: Transactions, Vol. 45, pt. 2-4; Vol 46, pt. i.
(Society,) 4to. Edinburgh, 1907- 1908
Bgyp-, Survey Department:
— — ' ; Meleuruln^ical Report for the year 1905, pt, i, 2,
(Department,) 4 to. Cairo, 1907
- : Survey Department papers, No. 5, 5.
{Department.) 8vd. Cairo, 1907
3. B. F. E. Keeling, Tbe Cliinste of AbbiRsi*. 1907
5. E* B. H, W*d(^, Field method of determining Lunj^itudei by
ol>servatiotiH of the Mooti. 1907
Gncyclopadi© der Mathematiechen Wissenschaften :
Band VI. i, Heft i, 2. Geodiisie und Geophysik. Band
VI. 2, Heft I, 2, Astronomie.
(Library Fund,) Svo. Leitf^ig, 1 905-1 90S
English Mechanic (the) and World of Science. Vol 85-
87 (No. 2204-2255).
{Editor,) lo\, l^titiAciTv, \^cii -Au^^^"^
f8o]
List of AddiiY>TU
Europe, Centralbureau der Internationalen Erdmessung;
VerhttDilltingeo der , , . fitiifzehnt^n allgemeiuen CoDfere
. . . 1906, Theil I.
(The Bur*iau.) 4to. Berlini ^9
Fa^erholm (Erik) :
: *Plit>tograpliic measurement of the prmcipal stars in tl
cluster of Coma Berenices and determmatian of their proj
Diotioiis.
{Cpsala Obsen-atori^J) 8vo* Uppsala and Stockholm, 190^*
: *Talcuti , , , observations made at Uppssila 1905,
{Vpealii Oltserratort/,) 8vo. Uppsala and Stockholm, 191
: Ueber tlen Sternhaufen Mesi^ier 67, Inaugural Digaertiiti*;
(Upmla Observatory.) 8vo, Uppoala, i
Fauth (Philip) :
The Moiin in modern astronomy : a Summary of twenty ya
*»el©nographic work, and a study of recent problems.
lated by Joseph McCabe, with an intro<3uction bl
Ellard Gore.
( IV, H. Wrdey,) 8vo. Lundon [1901
Flagg (Ambrose T.):
Primer of Kavigation,
(Author,) 8vo. London^ 1906,
Flammarion (Camille) :
Anntiaire Astronomique et Mdt^orologique pour 190S.
{Kdifxfr.) Svo. Paris [1907!
Galilei (Galileo) :
: Ope re . . . Edizirme Kazionale, sotto gli auspicii di Su
Mac>sta il Re d' Italia. Vol. 3, pt. 2; VoK 19.
{Italian Guvemmf^t.) 4*0. Firenze, 19a
: TrentVnni Ji studi GalOciani, per Antoido Favaro,
4to. Firenie^ 190I
Garrett (A. ffolliott) and Chandradhar Q-uleii :
The Jai[)ur Observatory and its builder.
{Limit, A, ff Gannett) 4to. Allahabad, 1902
Gautier (Raoul) :
llapport .<^ur le Concours de reglage de chrouuniHres, 1907.
{Author.) Svo* Gen^ve^ 1908
Geneva J Observatoire :
: ^Ruaiime mi^eoroiogique . . , pour Gen^v© et le Grand
Saint-Bernard, par R, Gautier, 1906.
{Observatorf/.) Svo. Getitsve, l<s
: * Observations mtjtt^orologiques faites aux fortifications
Saint-Maurice pendant Tanniie J906. Resume par
GwulieT.
{A utlior .> ^^^^ ^sswtx^, v^
to the Library^ 190 7- 1908,
[8,1
Gteneva^ Soci^t^ de physique et d'hiatoire naturelie :
Mt^moites^ Tome 35, fasc. 3-
(Sorkhj,) 4to. Geneve, 1907
^ttingen, Konigliche Stemwarte ;
Astrouomische Mittkeilnngeri, Theil j^,
(Observatory.) 4 to. Gbttingen, 1906
E. i^hwnrtzchild. Ueb^r die totale Sonne utinfiternis vom 30 Aug,
1905-
Iranada, Observatorio Astronomico, Geodinamico y
Meteorolo^co :
Bole tin Mensiial. Afio 5 (1907), No. 4-1 2v
{Observatory.) foL Granada, 1907
Eclipse total de Sol dtil 30 de Agosto de 1905 : observa-
Clones hechas en Carri<in de I08 Coudes ( Palencia), Fasc. 4- 7 .
(Ob^eri'atory.) 8vo. Granada, 1905
Estarllstica fotO'lieliogrifica. Alio 4, 1908,^0. i, 2.
(Ob8irtuiP*ry.) fol. 1908
ittingen, Konigliche Geeellschaft der WissenBchaffcen :
Nachrichten, niatbenaatisch- pliysikalische Klasse. 1907,
Heft 1-5.
(Society,) 8vo* GiDttingen, 1907-190B
Jray (G-eorge J.) :
X bibliograpihy of tbe works of Sir I>aac Newton ; togetber
witb a list of books illustrating his works. , , . Second
edition, ,
(Library Fund.) 4to. Cambridge, 1907
reenwich, Royal Observatory :
Astroiioniical and uiagnetical and ineteoiologica.1 observa-
tions made . . . 1905 under tbe direction of W. E. M.
Christie,
(Obserratory.) 4to, London, 1907
Appendices;
Results of Astronomical Observations, 1905.
Kesult-s of Magnelical aud Meteorological Observationi, 1905,
Photo lieliograpliic result'*, 1874- 1S85 . . . from photographs of the
Sun taken at Greenwich, at Harvard College, LI.S.A., at MeUwurne,
iu India, uad in Mauritius.
Obsirvatians of the planet Eros, 1900-1901^ for determination of the
Solar Parallax,
Re[tort of the ABironnuier Royal to the Board of Viaitors, 1907.
(Ubserratory,) 4to, London
Afitrograpbic Chart. Zone + 71"- 4-78" (304 cbait^).
{Ob$errafory.)
Astrographic Catalogue, i9oo'o, Greenwich Sectiou^ Dec.
4-64' to 4- 90". From photographs taken and measured . . .
under the direction of W. H, M. Gbmti**. Vol 2,
(Observatory.) 4to, Edinburgh , 1908
Meaiiurca of rectangular coordinates and diamtiters of tttar unagM^
Deo, -f 72° to 4-90",
(8.]
Liit of Additions
¥
i
Gronlngen, Astronomicai Laboratory :
Publications , . , edited by J, C. Kapteyn. No. 17, tS.
(Pro/. Kapteyn.) 4 to. Groningen, 1907-1908
17. W, d« Sitter. On the Ubmtion of the thre« iuuer Ufge sat«Uite«
of Juft^ler,
1 8, J, C. K^pteju. Od the number of stars of determined magni-
tude ftnd dotermincil galaetic latitude.
Hale (George EUery) :
The study of Stellar Evolutiou: an account of some re4!ent
methods of As trophy sic al research. (Chicago University
Decennjal Publications.)
(Author,) 8vo. Chtcsj70» 1908
HaU (MaxweU):
Third report on Eartliquakes in Jamaica, The great earll
quake uf Jan. 14, 1907.
(Author.) foL Jamaica, J 907
HaUe, Kaiserlicbe LeopoIdiniBch Carolinische Akademie
der Naturforscher :
Abliaudhuij^eD (Nova Acta). Band 73, 87,
{Acalevtij,) 4to. Halle, 190
Hamburg, Sternwarte :
: *'Jahreabencht . . . 1905-1906.
(Observaton/.) 8vo, Hamburgh 1906-1907
: Mittheiliingen, No. 1 1.
(Observatort/.) 8vo. Hamburg, 1907
K, Omit Uiiter^uchaug ties Licbtwechsela oiniger Ter^nderlicher
Sterne vom Algoltyims.
Harley (Robert) :
Brief Inographical sketch of Robert Rawaon.
(Authuf\) 8vo, Loudon, n^J^
Hartwig (Ernst) :
: *Epheuierideu vemnderlicher Sterne fiir 1908.
{ Author.) 8vo. Leipzig, 1908
: ^Ueher den Antalgolstern Ii»W. Draconis.
(Author.) 8vo. Bamberg [1908]
Harvard College Astronomical Observatory :
— : Anuala, Vol. 47, pt. i ; 49, pt. i ; 57, pt. i ; 59, No. 1 ;
60, No. 4-8; 62, pt. I.
(Observatort/,) 4to, Cambridge. Mass., 1907-1908
Vol. 47, pt. I. WilliAmin* P. Fleming. A photographic study of
Viinable Stars.
,, 49, ,, I. S. L Htiilev* PeruTiat) Mtfteorolojry, t^2^$.
It S7> .f 1' L. Camp bell. Observatit>n» of 75 \ ariables, 1902-5.
„ 59, No. I. E. S. King. 8t«n<lArd teets of photagra).thic (dMce.
«, 60| ,, 4 Henriettas. Leavitt. 177 Variables in like Magel*
Ifcwk Clouds.
t» 60, „ V V\ftiw\fiX'^ %. \jww\w \^'^'«\»k\ea of the Algol
to the Library f 1907-1908.
m
STTftrvard College Astronomical Observatory — conttntted :
VoK 60, No. 6. NebuUti dlscorered at H&rvard Coltegt Obsorvatory,
,, 60, ,^ 7. Double SUrs iouth of - 30'.
,» 60, ,, 8. 8. L Bailey. Catalogue of bright cluatew and
Tiebulfe.
,j 62, pt. I, A. 5earlc. Determination of cnnstatitB for I'dduction
of Zones observed with the Meridian Circle, 1888
: Circulftr, No. 130- 136,
(Observatory,) 4to. Cambridge, Mass., 1 90 7- 1908
: Sixty -second annual report of the Director . . . i^o?* By
^ K C. Pickering.
^H (Ohservaiory,) 8 to. Cambridge, Muss., 1908
J
W
Hasselberg (K. B.) •
♦Koliert Thalcri ; sa vie efc travaux,
(Author.)
8vo. Paris, 1907
I
H[axo] (G-eneral);
*M^moire sur le figure da terrain dans les cartes topo*
graph iques.
(Royal Society.) 8vo. Paris, 1822
Heidelberg, Groasherzogliche Sternwarte (Astrono-
rmieches Institut) :
— : Mittheiluiigen . . . herausgegebeu von W. Valentiner. No. 10
-12.
(Observatory.) 4to, Karlsruhe, 1907- 1908
No. to. Jahrfsberictit, 1906.
,, II. E. Przybyllok. Dj*s Profil der Rtindpartieti des moodes.
,, 12. G. AbeLti. Eio iiener Hippsiher Chronograph.
Heidelberg (Konigetuhl), Aetrophysikalisclies Obaervfu-
torium :
Publikationen . . . Band 5, No. 2, 3. Hcrauagegeben von
Mai Wulf.
(Oifsen^atory.) 4 to, Karlsruhe, 1907
Helmf^rt (Friedrich Robert) :
: Die niatlieniatbchen und phystkalischen Theorieen der
. hoberen Geodasie.
I (Library Fuf^d.) 2 vols. 8vo. Leipzig, 1880-84
: *Be8tinimun^ der Hohenlat^e der Insel Wangeroog durch
trigonometriijclje Measuugen im Jahre i883.
(Author.) 8vo. Berlin, 1907
Die AusgleiclmngsrechnQng naeh der Methode der kl^^inatpn
Quadrate ; mit Anwendunj^'en anf die Geodasie, die Physikj
und die Tbeorie der Messinstriimente. Zweite Aufloge.
(Turrwr and Hoirox Fund.) 8vo. Leipzig vnrd Berjiu, 1907
*'rngoiiomHtri8che UUhenmessung und Refraktiouskoeffi-
zienteii in der Nahe des Meeresspiegels.
{Author.) ^s<i, '^^^Kxxv^ ^^^^'^
Liit of AddUiom
Hill (aeorge WUU&m) :
♦Attraction of tUe hum<)geiit!uu8 sphericd segment.
(Author.) 4to. Baltimore, 1907
Himmel und Brde. Illustrierte naturwbs«tiachaftliche Monati.
schrift, berausgegeben voii tier Gt^*3ell*cliaft Urania; Kt ■ .
teur P. Scbwahn. Jabrgang 19, Heft 9 — .T^hrgang 20, H -
(Ediior.) 8vo. Berlin, 1907-190^
Holden (Edward Singleton):
: *Tlin c**n(iict of science and religion*
(Author,) 87#.
: ♦Galileo.
{Author.) 8vi>.
: "*"The measure of progreas.
{Auihm\) 8vo.
Horological Journal (the),
* {Brit. HoroK hmtitute.)
1904
1905
1906
VqI. 49, 50 (Nu. 5S7-595)-
8?o. London, 190 7-1 90S
HngginB {Margaret Lindsay) :
A^;iieM Mary Gierke and Ellen Mary Gierke. An Appreciation.
{Author.) 8?o, Loudon, 1907
India* Survey Department ;
: Account of the ujierationa of the Grent Trigonoroetnc
Survey of India. Vol. iS , . . prepared under th
direction of Major S, G. Burrard.
(H.M, Govt, in huUa.) 4 to* Dehra I>un, ir
: General report on the operations of the Survey of ludu
Department . . . during 1905-1906.
{H.M. Govt, in India,) fol. Calcutta^ 1907
: Exiracta from narrative reports of the survey of Indii for
, . . 1904-1905; 1905-1906.
\HM^ Govt, in India,) fol, Cdcutta^ 1907-1^
Indian Engineering, An illustrated weekly journal, edited by
Pat. Dnyle. Vol, 41, No. 21 — Vol, 43, No. 20.
{Editor.) fol. Calcutta, i907-i«
International Catn logne of Scientific Literature :
E. (Aatroiromy), 6th annital issue (March 1906-Aprjl 1907).
{Tumor and Ilorrox Fund,) 8vo. London, 1906- 1907 J
Italy, R, Commiseione Q^odetica Italiana :
: Biirereuza di longitudine fra gli Osaervuton di Padova e diJ
Bologna, determinata nel 1897. G. Lorenzoni e G. Ciacaloii]
{Padua Observatoiy,) 4^- Padara, 190J
: ♦DifTerenza di Longitudine fra Fadova . . , e Rouia . .
deletTOwmlBi Y^o^. O. CvBcato e A. Antoniaszi.
( P adua ObaerDaioT y :^ a?** "^ ^ewfe^va^ 1 9c
to the LiWary, 1907-1908.
[85]
Jarry Desloges (R,) :
ObBervations dm Burfacea planet&ires ; la lune, Mars, Jupiter,
Saturne, Mercure, Faec i. Aimce 1907,
(Author,) 8vo» Paris, 1908
Jonckheere (Robert) :
* Resultats dee mesurea dea diamt^^tres de Mercure durant eon
passage du 14 novembre 1907, #
(Author,) 4to, Paris, 1908
Jordan (Wilhelm) :
Opua Palatinum Sinus- ond Coaioue- Tafeln von lo'' zu lo^
^K (Library Fund,) 8vo. Hannover und Leipzig, 1897
F Kasan, Observatoire de VUniversit^ Imp^riale ;
^ : Publications, No. 1 6.
^^ (Observatory.) 4ta Kasan, 1907
^^m y. A* Baranof Determination of force of gmvltj (Umbi ftnd Volga).
^B-^^ : EJemente und EpheoieFide dea Pkneten (78) Diana ftir die
^H Opposition 1907.
^H (Obmrvoiwry.) fol, Kaaan, 1907
Kayser (Hj :
^Handbuch der Spectroscopies Band 4
{Librarti FujitL)
lein (Hermann X) :
Jahrbuch fur Aatronomie und Geophysik.
(1906-1907).
{Tumor and Horrox Fund.) 8?o. Leipzig, 1907-1 908
8vo. Leipzig, 1908
Jaiirgang 17, 18
P*
Knowledge and Illustrated Scientific News, VoL 4, No.
7^12 ; Vol 5, No. 1-6.
(Tumor and Horrox Fund.) 4to, London, 1906-1907
Kodaik4nal and Madras Observatories :
f: Bulletin, No. 9-12.
(Observatory.) 4 to. Madras, 1907-1908
: Annual Report of the Director for 1907*
(ObBervatory,) foL Madras, 1908
Kugler (Franz Xavier) :
^m SternkuiaJe uud Sterndienst in Babel Aasyriologische,
^H astronnmische und astralmytbolagiBche Untersucbungen.
^H L Entwicklung der babylotiischeii Planetenkunde von ihren
^H Aufangen bis auf Christ us.
^H {I'umor and Horrox Fund,) 8vo. Miinster, 1907
Lancaster Astronomical and Scientific Association ;
Animal Eeport, 1903-1908,
[86]
hist of AdditiofiS
La Plata, Obeervatorio Afitron6mioo :
ComuuicacioDea elevadas d la Universidail, con mot
_ viaje hecho h Earopa pur el Diiector, Dr, Francisco^
Ue Sooienzt.
(Obifervaiory,) foL La Plata y Buenoa Alrea, 1907
: Efemeriiles del sol y de la luwa para 1907.
{Observatory.) 4to. La Plata, 19
Lebeuf (A.) et R Chofardet : _
♦ Resmitats des obRervafciona faites pendant recHpsa totde i^
8oleil du 30 aoQt 1905.
{Authors,) 4to. Faria, 1907
Leeds Astronoinioal Society ;
Journal and Transactions, No. 14 (1906),
{Society, )
8vo. Leeds, 1907
Leeds PhilosopMcal and Literary Society :
86tli and Sjtb Annual Keports, 1905-7.
{Society,)
SfO. Lee^
^3^
Leipzig, Astronomische GeBellschaft :
: Yierteljahrsschrifi, Jabi-gaiig 42, Heft 2-4 ; JahrgaAg 43^
Heft 1.
(Society.) 8vo. Leipzig, 1907-1903
: Publication en, 22.
(Sonet y.) 4to. Leipzig, 1906
C. Bbrj^en. Logiritlimisoh-trigotiomptrische TafeL
: Bericbtigungeri mm Catalog der A»tronomiBchen Gesellschftft
Erste Abtheilungt Catalogo far 1875,
(Socidy.) 4to. Berlin, 1008
Leipzig, Ftirstlich JablonowBki'sche Geeeilschaft :
Jahresbericht, 1908.
(Society.) Svo- Leipzig, \go^
Leipzig, KonigUch SaohsiBche G^eaellschaft dor WieeeD-
sc haft en ;
: Abhaudlungen, mathematiscb-pbvsiscbe Classe. Band 30,
No. 1-3.
{Society.) Svo. Leipzig, 1907
— — : Berichte iiber die Verliaodlungen : matbematiscb'phrsi.*chf
Clas.se. Band 59, Heft 2-4; Band 60, Heft i, 2.
(Sonety,) Svo, Leipzig, 1907-1908
Lick Observatory, University of California :
: Bulletin, No, 11 5-130.
{Qhmrvaiory.) 4^0. 1907-190$
: Publications. Vol. 9, pt 1-3; vol 10.
(Obsermtory,) 4to. Sacramento, 1907
Vol* 9, "S^. \-'i. T^^^* ^^ 0. MilU expedition to the Soothfoi
to the Library, 1907-1908.
[87]
Liisbon, Sociedade de Gteographia :
Boletim, 1907, Ko. 7-12; 1908*^0. 1-2.
{Society,) 8vo, Liaboa, 1907-1908
iverpool Astronomical Society :
Annual Report, 1 907-1 908.
(Sodeti/.)
8vo. Liverpool, 1907
^Jjiverpool Literary and PMlosophical Society :
Proceedings . . . No. 59, 60 (1905-6; 1906-7)*
{Societfj.} 8vo, Liverp<K>l, 1906-1907
iverpool Observatory :
Report of the director of the observatory lo the Marine Com*
mittee, an«l meteorological results * . . 1906.
(Obiervatory,) 8vo. Liverpool, 1907
Lockyer (Sir Norman) :
*0n the oViservatioiis of stars made in some British Stone
Circles, 3rd note. The Aberdeenshire Circles.
(Author.) 8vo. London^ 1908
* On the presence of snlphur in some of the hotter stars.
(Author,) 8vo. London, 1907
3ckyer (William J. S.) :
* Prominence ami Coronal structure,
( Author.)
8vo* IjondoUj igo8
Loewy ( Maurice) :
: * Precautions a prendre dans le mode d'ex^ution de
certain es reclierches do la haute precision.
(Pariis Ohservatiiri/.) 4 to. Paris, 1905
*Nouvelle method© pour la determination directe de la
refraction k touie.s les hfiuteurs.
(Paris Obserratortf.) 4to. Paris, 1905
*Mutbo'Ie nouvelle et rapide pour la determination des
erreurs de division d'un cercle m4ridien.
(Paris f)h»ervaitjry.) 4to. Paris, 1906
ILoewy (Maurice) et P, Puiaeux i
1 Tliree memoirs referring to the Paris Photographic Atlas of
I the Moon.
I (J/. Puiteu^c,) 4to. Paris, 1903-1907
London, Britiah Astronomical Association :
^— — - : Journal, Vol 17, No. 8-ro ; Voh 18, No. 1-7.
(A»8oeiafion.) 8vo. London, 1907- 1908
List of members, 1907.
(Amoi'iatifm.) 8vo. London, 1907
London, Geological Society :
Quart*irly Jounial, Vol 63, 64 (No. 2 5 1-2 5 j).
{Society, ) &v o . l^vii^^cyQ., \ ^ci*\«^^d^
[88J List of Additione
London, Geological Society ^ — continued:
: Geological literature added to the . . . Library, 1907,
(Society.) 8vo. London, 190J
— ^ : The history of the Geological Society of London. By
Horace B. Woodward,
(Society,) 8vo. London, 1907
London, Meteorological Office ;
— — : Hourly readings obtained from the self-recording initru-
ments at tho four Obaerratories under the Meteorological
CouucU, 1906. (New Series, VoL 7,)
(The Office.) 4to, London, 1907
: Meteorological Observations at stations of the i>eooiid order
for tlie year 1 903.
(The Office.) 4UX London, 190S
: Observations at stations of the second order, and at Anemo-
grai^h stations^ 1908, Jan.-ApriL
(The Office.) 4to. London, 1908
; Weekly weather report, VoL 24, No. 35-52; Vol 25,
No, 1-22.
(The Office.) 4to. London, 1907-1908
: Second Report of the Meteorological Coramittee to the Lords
Commissioners of His Majesty's Treasury, for the year
ending 3iBt March 1907*
(The Office,) 8vo, London, 1907
London, Nautical Almanac and Astronomical Bphemdria
for the meridian of the Royal Observatory, Greenwich. 191!,
(Lordi ComTnisaioneTB of Admiralty,) 8vo, London, 1907
: Ditto, Part i ; containing such portions as are essential lor
navigation, 191 1.
(Lords Commissioneri of Admiralty,) 8vo. London, 1907
London, Physical Society :
Proceedings, VoL 20, pt. 5, 6; VoL 11, pt i.
(Society,) 8to. London, 190 7- 1908
London, Royal Astronomical Society :
Monthly Notices, VoL 68.
Svo. London, 1908
London, Boyal Institution of Great Britain :
Proceedingis, 1906. Vol i8, pt» a (No. 100).
(hi^titHtion,) Svo. London, 1907
London, Royal Meteorological Society :
: Quarterly Journal, VoL 33, 34 (No, 144^146),
(Society.) 8vo, London, 1907-1908
' : The Meteorological Record : Monthly results of observations
made at the stations of the Royal Meteorological Societyp
with iftmatkft on tl\e weather ... by W. ^larriott VoL
26-27 (^0. io^-\o(i'^.
(Society.) ^H^^Xja^^^x^Xv^-V-^^spS^
to ih€ Library^ 190 7*1908,
[89]
London, Royal Photographic Society :
The Photographic Journal ; including the Transactions of the
Royal Photographic Society, Vol 47, Xo. 6-11; Vol. 4S,
>fa 1-5.
(Society.) 8vo. London, 1907-1908
>ndon, Royal Society :
; Philosophical Transactions, Series A, Vol 207^ 20S (No.
419-432)^
(Societt/,) 4to, London, 190 7- 1908
: Pro€fte<Lling8, Series A, Vol 79, 80 (Xo. 531-541)^
(Societi/.)
: Year-book, 1908.
(Societi/.)
IliOndon, University CoHege :
Calendar, session 1907-1908
(Tlte CoUege.)
8vo. London, 1907- 1908
8vo. London, 1908
8vo. London, 1907
4tQ. 1907-1908
Lowell Observatory :
IBuIl*^tiii, No. 28^32.
I (Ferciual Lowell.)
Itiuizet (Michel) :
♦Sur Fi^toile variahle S Flkhe [ VY Cygne, fi Lyre, SU
i Cygrie]» 4 papers.
r 8vo. Paris, 1907
iLnnd, AstroMomiBka Observatorium :
t *Meddelaiideii . . . Series I, No. 29-32, 34-38.
f {Ohservaiory.) 8 vo, Uppsala <fe Stockholm, 1 906-1 908
Lynn {William Thynne) :
: Celestial Motions : a handy book of astronomy. Eleventh
edition,
(AuihorJ) 8vo. London, 1907
- : Remarkahle Eclipses; a sketch of the most interesting
^^ circnmstAtices connected with the observation of solar and
^H lunar eclipses hoth in ancient and modern times. Ninth
^H edition.
^B Author, Svo. London^ 1908
^bCadrld Obeervatorio Astron6niico :
^H Anuario, ano 1908.
^V ( Observatory, )
HMadrid, Heal Academia de Oiencias exactas, flsicas y
^ naturales:
: Anuario, 1908,
{Academy.) i6mo. Madrid
; Memoriae, Toiuo 25.
{Ac€ifiemy.) 4 to. Madrid, 1907
: Revista . . . Tomo 5, No, 5-12 ; Tomo 6, No. 1-9.
( A cademy, ) %x q , 'Si^j^xv^.k v^Cili-x%^'^
8vo, Madrid, 1907
[90]
List of Additions
Mancheater Literary and Philosophicsal Society :
Memoirs and Proceediuga, Vol. 51, pt. 3 ; Vol. 52, jjL i, 2.
(Soeititj,) 8vo, Mftneh ester, 1907-1908
MamlSi Philippine Weather Bureau :
: Monthly Bulletins, 1906 Nov.-Dec. ; 1907 Jan, -June,
(Bureau.) 4to. Manila, 1907
: Report of the Director, 1904, pt. 5 \ 1905, pt« j.
{Bureau,) 4ta Manila, 1907
— " : The rainfall in the Philippinea, By Rev. M. Saderra Miis6.
(Bureau,) 4to, Manilii^ 1907
Mascart (Jean) :
: *La question des Petites Flanetea.
{Tumor and Harrox Fumi.) 4 to. Paris [1906]
- — — ; ^Observations simultanees de la surface de Jupiter,
(Author) 8vo, Paris, 1907
— — ; L*henrft k Paris,
{ Author.) 8vo. Paris, 1907
Maunder (Edward Walter) :
The Astronomy of the Bible : an elementary commentary on
the astronomical references of Holy Scripture.
(Messi'H *Sealeij^ Clark tt Co,) Svo, London, 190S
Mauritius, Royal Alfred Observatory :
: Annual Report of the Director for the year 1906.
(Obi^ervalorf/} fol Mauri tiua, 1907
: Resuits of maguetical and meteorological observations made
. . • . in the year 1905 under the direction of T. F.
OJaxtoD.
{Observatort/,) 4to* Loudon^ 1907
Mae (Arthur B. P,) :
: The heavens at a glance, 1908 [Sheet Calendar]*
(Auihar,) Cardiff, 1907
: The story of Astrology.
(Author,) 8vo. PontypridcJ, 1907
Melbourne Observatory :
Fortiuth Repnrt of the Bcfard of Visitois, . , , together with
the report of the Government Astrouomer, 1905-1906.
(Observatoti/.) (61. Melbourne, 1907
Meudon, Observatoire d'Astronomie Physique de Pariaj
Annales, . , . . publieeB par J, Janssen, Tome 2 ; Tome \
fasc. 2.
(Observatory,) 4to. Paris, 1906-1907
Mexico, Socledad cientifica '' Antonio Alzate '' :
Memorias y Reviijta. Tomo 24, Xo. 1-12 ; 25, No. 1-3 ,
26, ^o. 1-^.
(Society. "i ^N^.^%i»m^^tyafc-v^\
to the Library y 190 7- 1 908,
[9>]
{pbseriHitory.)
I Milan, Reale Oaser^atorio di Brera
I Pubblicazioni, No. 40, parte 2 ; No. 43, 44.
r
M
4to. Milnno, 1907
40, pt, 2, AI-Battitiii sive Albateoii Opus astTonomicum , . . C. A.
43. Lfttitudine del li, Osaervatorio (U Brora. G. Forui
44. Latittidine dilla R, Dniremtik di Pa via. A, ViterbL
[issouri University, Laws Obeervatoiy :
Bulletin, No. 12-14.
4to. 1907-1908
^
Mitton (G. R):
The; children's book of stars.
{Library Fund,)
8vo. London, 1908
Moncalieri, Osservatorio Oentrale del Real OoHegio Carlo
1^ Alberto :
^ — — : Bollettino raisiisuale (Societa Meteorologica Italiana), Serie 5^
^H YoL 26, No. 3-t2.
^P (Observaiary.) 4to. Torino, 1907
^*^ : Bolletino Meteorologico e Geodinamico. Dicembre 1906-
[ Harzo 1908.
^m ( 0 hf rvatory 8 vo .
^ — : Riassurito delle OBservazioni meteorologiclie fatfce al Grand
^H H6tel du Mont Cerviu, 1906. C. Albera.
^P {Observatory^) 8vo. Perugia, 1907
Montpellier, Acad^mie des Boiencea et Lattres :
M^^moires de la section des sciences* 3 me %M% Tome 5»
No. 5-7.
{Acmhmy^) Svo, Montpellier, 1906-1907
looaer (Johannes) :
Theoretische Koanjogonie dea Sonnensyti tenia.
{Tumor and Horrox Fuml.) 8vo. St, GaMen, 1906
loscow, Socidt6 Imp^riale des Naturaliates ;
Boll e tin, amiee 1906, No. 3-4.
(Socidy,)
8vo. MoscotJ, 1907
lount W^llson, California, Solar Observatory :
: *Contributions , , . . No. 15-25*
{ Ca i^eg le InsHiut ion. ) 8 vo . Chicago, 1 90 7 - 1 9 08
: ^Annual Ke|Jort of the Director . , . 1907*
L {Cartieyie histituiion,) 8vo. Washiogton, D.C. [190S]
Milblemann (R) :
Enveloppen der Enter ^acben Geraden. Inangu ml- Dissertation.
{Berne University,) ^^ia, ^^tt^^ \^^\
[qs] List of AdditioTts
Mumch, Koniglich bayerische Akademie der WiBden-
scbatten :
: Abhandlungen der mathematisch-phyaikaliscUen Claaee.
Band 23, Ahth. i, 2 ; 24, Abth, i.
(Aeculenty.) 4to. Mdnchen, 1907
: Sitzun^sbericbte der mathematisch-pbjaikalischeti Cla^,
1907, Heft 2, 3,
{Ac€uiemy,) 8vo. Miincbeii, 1907-1903
Naples, Reale Osservatorio di CapodimoDte :
: *Yamzioni dolla dcclinazioue magnetica, 1905-1904. F*
Contarino.
(Observati/ry,) Svo, Napoli, 1906
: ^Osservazioni astronomiache, magnetiche et meteorologiche
eseguite nei giorni 28, 29, 30, 31, agosto e i settembre 1905
in occasions dell' ecliase aolare del 30 agoato, F. Coutarimi.
(Ohiierv(dort/,) Svo. Najx>li^ iqo6
: *Ria«sunto delle osservazii-ni meteorologische fatte .
neli* anno 1905-6, E. Gaerrieri.
(OfMen^aton/,) Svo, Najjoli, 1906-7
^-- — : ^iletorminazione assolute della incliuazione magnetica«
1 90 1 -1 906. F. Contarino,
(Obisr*rvaiory.) 8vo, Xapoli, 1906-1907
; ^Oescrvazioni meteoricbe fatte . . . neir anuo 1906.
(Observatory.) Svo. NapoU, 1907
Naples, Societk Reale (B. Accademia delle Soien^e) :
: Atti, 8tTie set-on da, Vol. 13,
{Acofiemy,) 4to. Napoli, 1908
: Ktiudicoiito delP Accademia delle scienze fisicbe e mateniA-
iiche : Serie 3 : Vcd. 13 (Anno 46), fasc, 3-12; YoL 14,
(Anno 47), faaa r» 3,
{Academy,) Svo. KapoH, 1907-1908
Natal Observatory:
Report of tiie Government Astronomer for the year 1907.
{Obmrvatory,) fol, Pietermaritzburg, 1908
Nature. A weekly illustrated journal of science. Vol. 76-78
(No. 1 964-20 1 5).
(Editor,} 4to, London, 1907-1908
Naturwiesenechaftliche Rundschau, Wochentlicber Bericht
liber die FortscbrUte atxf dem Gesammtgebiete der Natur-
wissenscliaften . . . herauftgegeben von W. Sklarek. Jabrgaog
22, No 24-52 ; Jabrgang 23^ No, 1-23.
{^Alitor,) 410. Braunschweig, 1907-190S
[NewaH, "augh 1?Ta»ti?«L\\
♦Frank UeC:\^B.u, \%i,^^\^^v
{Ut6 McCleaii.^ %^^-\jsti^^^^x^^
to the Library, 190 7-1 90S.
[93]
Newcomb (Simoo):
*A search for fluctuations in the suD^a thermal radiation
through their influeiice on terrestrial temperature.
(Auihor.) 4to, Philadelphia, 1908
Kewcomb (Simon) and Frank B. Ross :
Invt*istigrttiorj of inequalities in the motion of the moon pro-
duced by the action of the planets,
(Authors,) 4 to, Washington, 1907
KeucliS'tel, Obaervatoire Can to Dal :
liapport dn directeiir ... pour Tannc^e 1907^ suivi du rap-
I port special snr ie cunconrs dea chrouometres.
I (Observafory,) 8vo. La Chauxdt-Fonds, 1908
O]
ew York, Observatory of Columbia University :
CoMtriVmtiiinB, No. 9.
(Ob,*!^ rotor i/.) 8vo. New York, 1906
Rees, Jiicoby And Daris. Yariation of ktitude at New York City.
Ft. 2. Variation of latitude and constant oF nberratioti,
observatory (the). A monthly review of astronomy ; edited
by T, Lewis and H. P, Hollis. Vol. 30^ 31 (No. 385-397),
(EiUt'frs.) 8vo. London, 1907-1908
Olsen (Ol© Theodor) :
I The Fitiherman's Nautical
I 3 2 ml veir, 1908.
f {Author.}
Almanac and Tide Tables,
8vo, Grimsby, 1907
Oporto, Academia Polytechnica :
Armaes Scientificos. Vol. 2, No. 2-4; Vol, 3, No. 1.
{Academtj.) 8vo. Coirohra, 1907-1908
Oppliger (Alfred) :
Historisch-kritische ITntersnchnng Uber die
Kngelfunktionen. Inaugural-Dissertation.
Theorie der
{Berne Uniifersity,)
8vo. Btjrn, 1906
)ttawa, Dominion Astronomical Observatory :
Report of the Chief Astrom>mer , * . . for the year ending
June 30, 1905,
(Obsernitory.) Svo. Ottawa, 1906
|Ottawa, Literary and Scientific Society :
Transactions, No< 4. 1 906-1907.
(Society,)
Svo. Ottawa, 1907
[Oxford University Observatory :
Astrographic Catalogue, 1900*0: Oxford Section, Bee, + 24*
to +32', from photographs taken and measured . , . .
under the direction of H. H. Turner. Vol 3, 4, Measures
of rectangular co-ordinates, etc.
[94]
Lint of Additions
Padua, Oaeervatorio Adtronomico della B« Universitd :
*Contributi, 1906,
Sv^o. Vetiesia, igo^'
6. Loronsoni, 11 problem a doll a correxiooe di un' orbtu seoo&do il
Prof. BaUAchioger.
Paris, Acad^mie des Sciences :
Compter rendua hebdomadaires dee a^aneea. Tome 144,
No. 23 — Tome 146, No. 22.
{Acoulemi/,) 4*0. Paris, 1 907-1 90S
Paris, Bureau dee Longitudes :
: Annuairo pour Tan 1908; avec des notices »cieniifiqae&
(Burmu,) 1 6 mo. PariB [1907]
: Connaissance des Temps, ou des mouvemeDt^ c^lestea poi
le meddien de Paris, k 1' usage das astronomes et d
navigateurs, 1909.
(Bureau,) Bvo, Paris, 1907
— — : CfHinainsance des Tempa, Ex trait h, l*u«age tle« tcoli
d*Hydrographie et des marinsdu commerce, 1908
(Bureau,) 8vo, Paris, 1906
Paris, Bureau International des Poida et Mesures :
— : Proctss-verbaux des seauces [du comity] de 1907. jme
Siirie* Tome 4.
(Bureau.) 8vo. Pariit, 1907
: Travaux et M<^moires, Tome 13.
(Bureau,) 4to. Paris, 1907
Paris, Congr^s Astrophotographique International :
Go [I ft^ re net! aetropbotographique mterQatiouale de juill
1900^ Circiilaire, No. 12.
(Acadfsmie de% Sciences,) 4 to. Paris, 1907
Paris, D^p6t Q6n^ral de la Marine ;
Aniuiles bydro^niphiquea* 8crie 2,
(Depot of Marine,)
7]
u^
Aan^e 1906.
8vo, Paris, 1906
Paris, ]fecole Polytechnique :
Jouroal. Surie 2, Caiiier 11.
(£coIe Polijiechnique,) 4to. PariK, 1906
Paris, Observatoire :
: An Dales , . , publiciea sous la direction de M. Loewf!^
Observations, 1891, 1903.
(Observatonj,) 4to. Pari*, 1907
: Atlas photographique de hi lune .... execute par M.
Loewy et P. Ptiiseux. Fasc. 9.
(Minister of Public Instruction,)
foL (text in 4to), Paris, i90<S
' Cfttt^ p\\0\iO^lCB.^\!L\Qi^^ ^^ ^\i^. T*il\a-V 20\+2 2", + 24'
(34 c\\attRy
(Miniater 0/ Public bxatriMAvcm.^
to the Library^ 1 907-1 908.
[95]
: Catalogue photographitjue dn Oiel (Obaervatoire de PariB).
Coordonnt^es rectilignes. Tunie 2, zuae 4-22^ k +24"*
(MiniBter 0/ Pub fit: JjiMmetion,) 4 to. l^iris, 1907
: Rapport annuel sur I'etat de rObservaioire, 1906, par
M. Loewy.
{Observatory,) 4td. Paris, 1907
Paris, Soci^t^ Astrooomique de France :
Bulletin . . . et revue meiisuell« d'astronomie, de ra^tijoro-
lt»gie et de physique du globe. Aimee 21, No. 7-12 i
Aniline 22, No. 1-6. 8vo. Paris, 190 7-1 908
iSoeiety.)
f^arijB, Soci^t^ Matb^matique de France :
BtiUelin. Tome 35, fasc. 2-4 ; Tome 36, fane. i.
(Society.) 8vo. Paris, 1907-1908
Paris, Soci^t^ PhilomatMqu© :
Bulletin. 9me aerie. Tome 9, No. 3-6 j Tome 10, No. i, 2.
(Society,) 8vo. Paris, 1907-1908
Parkhurst (J. A.) and F, C. Jordan :
*An absolute scale of photographic magnitu^les of stars. The
photographic determination of star colours and their reliiiion
to spectral type. [2 papers.]
(Authorji.) 8vo, Chicago, 1907-8
iPernter (J. M,):
Meteorologische <)ptik. Abschnitt, 1-3.
Turmjr aiui Horrox Fund. Svo. Wieu und Leipzig, 1902-6
Perth Observatory, Western Australia :
11 A catalogue of 420 standard stars, mostly between 3I* and 41*'
[ South Declination, fnr the equinox 1905*0, from obi-ervatioos
I made at the Perth Observatory . . . under the direction of
f W, E. Cooke.
' {Otmrvaiory.) 4to. Perth, 1907
Peters (C. H. F.) :
I Helii>graphic positions of Sun-spots observed al Hamilton
I College from i86o to 1870. . , , Edited for publication by
\ Edwin B. Frost
I {Cameijie Instiiidion,) 4 to. Washington, 1907
Philadelphia, American Philosophical Society :
— — : Proceeding, Vol 46, No. 185-187.
(Society,) Svo, Phiiadelphia» 1907
^^- ; Transactions. New series. Vol. 21, pt. 4, 5,
^P (Society J) 4to. Philadelphia, 1 907-1 908
Philadelphia. PYanklin Institute :
Journal, year 81, 82. VoL 163, No, 6 — Vol 165, No, 5,
^L (Imtitute,) %vo* Wv\ai\^\vVm^ \<yi-\-v^^
[56] ^wf of Additions
Philadelphia, University of PennBylvania :
Publications. Vol 3^ pt 3.
(Ohservatory,) 4to. PbiUdelphi% i^
K, Doolittle. Ciitaln^fl and re-mea9Ui«nieut of the 648 double itirf '
discovered by Trof. Hough,
Philosophical Magazine :
The London, Edinburgh, and Dublin Philoaophical Mag
Series 6, Vol, 14, 15. (Xo. 79-90.)
(Tumor and Horrox Fund,) 870. London, 1907-190
Pola, Hydrographisches Amt der K, und K. KriQg»-
Marine :
Veruffentlicbuiigen, No. 23-25,
{ii ydrographk Office,) 4to, Pola, tgo;
Poor ( Charles Lane)
\\ii Solar System :
{Librartj Futid,) Svo. I^ndoti^ 190I
Tltij Solar System : a study of recent observations. ^^|
Popular Astronomy. Edited by W. W* Payne and R C
Wilson. Vol. 15, 16. (No. 147-156.)
{Editors,) Svo, Northfield, Minn., 1907-190$
Potsdam, AstrophyBikalisches Observatorium :
Ptiblicittioueii. Banit iS, Stiiek 2.
(Ohsermiory.) 4to. Potsdgim, 1907
G. Kberhurd, Untersu«*huttgeD Uber den Sp«ktri>gt»phen.
Potsdam, Oentralbureau der Internationalen Brdmesetmg:
VercitfentHchungen, Neue Folge, No. 15.
(The Bureau,) 4to. Berlin, 190S
Bencht Uber die Thiitigkeit dea Gentralbiireaufl, 1907.
Potsdam, K5nigL preussiQches Qeodatisches Institut i
VeroffeiUlicbuiig, Neue Folge, No. 33-35.
(The Institute.) 4to. and Svo. Berlin, 1907-190S
No. 33. Jahre'*beiiditdea Direktor*, 1906-7.
,, 34. L. ICruKer. Be^iiiigungsgleichuiigcn ftlr Linleiiiietir« nad
Pur Riicikwartseinschtittte.
„ 35. 0, He' ker. Seiamometrischf^ Beobaohtungen m Fotidim«
1907.
Prague, K.K. Sternwarte :
Magnetigche und meteorologische Beobacbtungen tm J&hre
1906. Jahrgang 67 . . . herausgegeben von L. Weinek,
(Obifervatorij.) 4to, Prag, 1907
Pmeenx (Pierre) :
La Terra et la Lune : forme ext^neure et structure interne.
(Library Fuuii.^ Svo. Paris, 190&
to the Ldhrary^ 1907-1908.
[97]
Pulkowa, Observatoir© Odntral Nicolas :
— : Mittheilungen, Baud 2, No. 1 6-^22.
{Oh»ervatory,) 4to. St-Peterabourg, 1 907-1 908
— : Publications . . . bous la direction de O. Backluiid. Serie
2. VoL 16, pt. I ; Vol 18, pt. 2.
{Ohmrvatory.) 4to* St-P<^tersbourg, 1907
YoL 16, pt. I* Observa ti on 8 fai tea au cercle vertical.
,, 18, ,, 2. Beobachtungeti am grossen ZvnitteletM»p.
Beineck (Aome) :
Die Verwandtfichaft zwiachen Kugelfunktionen und E«saelscheu
Funk ti onen. Inaugiiral-DisaertafcioTi.
(Berne Unive7*silt/.) 8vo, Halle a. S., 1907
RepBold (Joh€mn A.) :
Znr Geschichta der astrottomiaclien Messwerkzeuge von Parbach
bis Beicheebach, 1450 bis 1830.
{J. Franklin-Adams.) 4 to. Leipzig, 1908
Bicc6 (Annibale} :
^Anomalie della gravita e del magiietismo terrestre in Calabria
e Sicilia.
(Author.) 4to. Roma, 1907
, Biohmond, Surrey, National Physical Laboratory :
*BepoTt of the Obaerratory department for the year 1 907.
(La/joraton/^) Svo, Teddington^ 1908
Bio de Janeiro, Observatorio :
— — : Annuario . . . para o anoo de 1907,
(Obgervatori/,) 8vo. Rio de Janeiro, 1907
: Boletim mensal, 1906, No* 4-12 ; 1907, No. 1-3*
(Ob^rvaiory,) 4to. Rio de Janeiro, 1907
Bohr (Moritz von) :
Die Binokularen Instrumente,
{Tumor and Horrox Fund.)
8vo. Berlin^ 1907
Borne, Beale Accademia dei Lincei :
Atti . . . Anno 304, 305 (1907-1908)1 Serie qulnta. Rendi-
conti, Classe di scienze tisiche, mathematiche e naturali.
Vol. 16, semeatre i» faac. 11-12, semestre 2, fastx 1-12;
Vol 17, semeatre i, faac. i-io.
{Acaflef}iif.) 4to, Eonm, 1907-1908
I Bome» Beale Oaservatorio del Collegio RomaBo :
Memorie . . , pnbblicate per cura del DLrettore E. Milloaevich,
Sem 3, VoL 4, pt. i» 2.
(Observatory.) 4^0. Roma, 1 904-1907
Boine, Society Italiana delle Scienze :
Memorie di mateiwatica e di fisica. Serie terza. Tomo 14.
[98] Lifft of Addiiums
Rugby School Natural History Society :
Report . , . fur the year 1906,
(The School) 8vo, Rugby» 1907
San Fernando, Instituto y Obeervatorio de Marina :
: AlmauAqiie NAutico para el ano 1909.
{Observatory.) 4U1. San Femaodo, 1907
; Carta Foto^rutica del Cielo. Zone -9*. (40 charU.)
(French Minider of Public Imtmeiicn,)
San Francisco. Astronomical Society of the Pacific :
Publications, Vol. 19, 20 (No. 114-119).
(Society,) Svo. San Franciaco, 1907-1 90S
SSo Paulo, Sociedade Scientiflca :
Reviata, Vol. 2, No. 1-8.
(Society,) giro. Sfto Paulo, 1907
St. Petereburg, Acad^mie Imperials des Sciences :
Bulletin, Serie 5, Tome 22-24; S^rie 6. 1907, No. 10-18?
1908, No. 1-9.
(Acfvlemij.) 4to, Sb-P<^tersbourj;, 1905-1908
St, Petersburg, Obeervatoire Physique Central Nicolas:
Annales . . . Annee 1903, Supplement; Ann«$e 1904, pt. i^
pt. 2. fasc, I, 2.
(Oh»m-mtfjTy.) 410. Irkoutsk & St-Pt*tersboai^, 1906
Schaeberle (John Martin) r
*The diatances of the fixed stars.
{Anthor.) 8 to. 1907
Scheiner (Julius) :
Populiire Astrophysik.
{Library Fund,) 8vo. Leipzig und Berlin, 190$
Schiaparelli (Giovanni Virginio) :
^ConiLi Bi possa giustificare riiso della media aritDietica nel
calcolo dei risultati d'osservazioiie.
(Author,) 8vo. Milao, 1907
Science Abstracts. Section A. (PLysica). Vol. 10, pt. 6-1 j ;
Vol. 1 J, pt. 1-5.
(Instiiutiou of Electrical Engineers,) 8vo. London, 1907-1908
See (Thomas J. J,) ;
: ♦The new theory of earthquakes and mountain formation,
as illudtmied by processea now at work In the depths of
the sea.
(AuthQv,) 8vo. Philadelphia, 1907
: On l\ve leu^i^W^Vax^, ^^^3^3ax ttst^toai^ «ai^ ^«ofec^<Lt.iofi of the
(Author.^ ^x^,^\v^ssA^.^vK v^^
to the Library, 1907-1908,
[99]
Birius. Zeitschrift fiir popuJare Aalronomie ; PtedakteuT H* J.
L Klein. Band 40, Heft 6-12 ; Band 41, Heft 1-5.
r (E*iitor,} 8vo, I^ipzig, 1907-1908
Sophia, University :
■ Aniiuaire, 2, 1905-6 [in Bulgarian J,
r (Unii'erifitt/.)
8vo, Sophia, 1906
J South Kensington, Solar Physics Observatory :
Report tirade to tlie Solar Phyeics Comtuittee by Sir
Norman Lnckyer, 1907,
(Of'servatort/.) 8vo. London, 1908
R*iport of the Solar E':lipse Expedition to Pal ma, Majorca,
August 50, 1905, Prepared under the direction of Sir
Norman Lnckyer.
(Sofar Phi/iic^ Committee,) 4to. London, 1 907
Joothport, Feniley Observatory :
Report and results of [meteorological] observations for the
year 1907, by J. Baxendell.
(Author.) 4tOi Southpart^ 1908
f Bpitzbergen :
Missiona sctentifiquea ponr la mesiire d^un arc de Meridien an
Spitzber^, entrepriaes en 1899-1 90 1» arms les auspices des
Gouvernemeuts Rusae et Su^dois. Mission Kusse. Tome i,
Geod^^sie, Section 5 A a ; Tome 2, Physique Tcneatre,
section 9 B.
(Pulkowa Observatory.) 4to. St-P^tersbourg, 1907
Itabbins (Joel) :
Photometric Observations of Double Stars. (Publications of
the University of lilinois Observatory.)
(Unwermti/,) 4to. Urbana, 1907
Btookbolm, Kongliga Sveneka Vetenskaps Akademie :
: Arkiv for matheniatik, astronomi och fyaik. Band 3,
Heft 2-4.
' (Acafiemfj.) 8 vo, Uppsala & Stockholm, 1907
: Arsbok f^ir &r 1907.
{Academij,) 8vo. Stockholm, 1907
:
Stockholm, Observatorium :
Astronomii^ka lakttagelser och Undersoknlngar .
af Karl Buhlin. Bandet 8, No. 3-6.
{Observatory,) 8vo. Stockholm 1906-1907
ntgivna
Stonyhurst College Observatory :
Kesultd of meteorological and magnetical observations, with
report and not^s of the director, Rev. W. Sidgreave**, 1907.
( Obmrmtory.) ^^o. CiV\^)a&i^^^ ^^^^
^loo]
Lift of AdditioTts
Stroobant (Paul) :
; ^*T«9 progr^s de la photographie astronomique,
{Author.) 8vo, Brnxelles^ J907
; *La distribution des etoilea par rapport a la Voie Ijiclie,
d'apr^s la carte et le catalogue p}i olograph iques da del.
(Author.) 4to. Bruzelles^ 190S
Switzerland, Schweizerische Gheod^tische K^oniraiaaion ;
Das Schweizerische Dreiecknetx. Baud 10. Kelative Liiib-
weichungen.
(The Com m Man.) ^.to. ZorJcb, 1907
Tacubaya, Observatorio Astron6mico Nacional :
: Auuario , , . para el ailo de 190S, F. Valle. Alio 2$.
{Ohmrvatory^ Svo. M^xico» 1907
: Carta fotogratica del cielo, zone - i6% (25 charts,)
{Ob9eTvtii;tory.)
: Obaervaciones meteorolugicas practicadas en I08 Obeem>
torioa de Tacubaya y Cuajimalpa . . . 1904.
{Observatory,) 4to. Af^xico, 1907
Toronto, Royal Astronomical Society of Canada :
Journal, Vol i, No. 3-6; Vol. 2, No. i, 2,
(Society.) Svo, Toronto^ 1907-1 908
Toronto University :
Studies, Physical Bcieoce Series ; papers from the Chemical
Lakinitories, No. 54-58, 60-72 ; from the Physical Laboru-
tories, No. 18, 19,
(University,) 8vo, Toronto, 1906-1907
Toulouse, Aoad^mie des Sciences, Inscriptions et Bellee-
lettres :
Meiuoires .... lome s^rie. Tome 6.
(Acoflemy.) Svo. Toulouse, 1906
Toulouse, Conamission M^ttorologique de la Haat^
0aronne :
Bulletin Tome i, fasc 5* 1905.
(Touloitse OhBerratory,) 4to, Tooiotme, l^J
Toulouse, Observatoire Astronomique, Magn^tique et
m^t^orologique :
: Carte photographique du Ciel : Zones +5", +7*, +9*. <n
chartB.)
(French Minister of Public Instructum.)
: Annales , . . . Tome 7 . . . bous la direction de B, Bailli
(OhgervaifYry,) 410. Toulouse et Paris^ 1
Tramer (Moritz) :
Die Entdeckung und Begriiwduiig der Differential- und Intcj
rechtiung durch Leibniz im Zusammenhange mit aeinea
Aaschauiingen im Logik aud Erkenntnistbeorie. Inaugurtl-
io the Library, 1907-1908,
[•°«]
8vo. Torino, 1907
4to. Tcirino, 1907
8vo, Torino, 190S
8vo. Torino, 1907
Turing Reale Acoademia delle Scienze :
■: Atti, VoL 42, No. 7-15.
' — ^ ; Memorie, Serie seconda, Tomo 57.
(Academy,)
Turin, Reaie Osservatorio :
: Annuario astronomico, pel 1908.
{Ohservato}!/,)
: O^sservazioni Meteorologicbe, 1906,
( Ob$ervaton/, )
Turin, Society AetronoBiica Italiana :
Revbta di Astronomia e scienze aliini. Anno i, No. 5-12 ;
Anno 2, No. 1-4.
(Sonet p.) 8vo. Torino, 1 907-1 908
Tocle, Observatoire Hoyal de Belgique :
Annaks . . . Xouvelle serie; Annales Astronomiques,
Tome 10; Tome 11, fasc. i.
(ObservcUonj.) 4to. Bruxellea, 1907
■ Annales . . . Nouvelle serie : Physique dn Globe,
Tome 3, fasc, 3. Travaux publics par ies aoins de
G. Lecointe.
(Observaionj.) 4to. Bnixelles, 1J07
; Annuaire astronomique, 1908.
Annuaire met^orologique, 1907.
(Observatorij.) 16 mo, Brnxelles, 1907
: Lea Obaervatoirea Aatronomiques et lea Aatronomes, Par
P. Stroobant [etc.].
{Observatory,) 8vo. Bruxelles, 1907
Waited States Coast and Geodetic Survey :
Report of the Saperintendetit . . . showing the progress
of the work during the year 1906-7,
(Surveij Office,) 4io, Waakington, 1907
Tpsala, Kongliga Vetenskaps Societet :
Nova Acta Regime Societatia Scieatiaruin Upsaliensis,
Series 4, VoL i, faac. 2.
(Socteij/.) 8vo. Upsalia*, 1906-1907
Talentiner (Wilhekn) :
Katalog der Sterne zwiBchen dem Aquator und dem 8 Grad
siidlicher Deklinittion 1855, ^^^ '^^^ ^ GrossenklasBe fiir daa
Aquinoktium 1890.
{Tumor and Hctrrox Fund.) 4to. Karlsruhe, 1903
Tienna, Kaiserliche AJcademie der Wieaenschafben :
Sitzungsberichte . . . Maihematisch-naturwisiienschaftliche
Clasae. Abtheilung ILa., Mathematik^ Astronomio, Physik,
Meteorologie, Mechaoik. Band 115, Heft i-io,
(Academif.) 8vo, Wv^e^i^^ \c^^'^
[joa] Lint of AddUiom
Wallace (Alfred Russell) :
Is Mars Habitable? A critical examination of Profeicor
Percival Loweirs book^ '*Mars and its Canmla," with aa
alternative explanation.
{W, H. Wesley.) 8vo. London, 1907
Wallace (Robert James) ;
*5 papers on photography.
(i4u//ior.) Svo* Chicago [etc.], 1907-^
The aatorhroni pUt« : B«Iation of Astronomiciil Kfcoodaiy cegattf
to ttieir origin&ls : Studies in •ensitometry, H. : The fttnctton «f
A col or -filter aod isochromatic t)lat« in AHtronoiRical pb olograph j ;
Seu»itiveness of photographic pfatea at difiTerent tempermtaret.
Wanganui Astronomical Society ;
Annual Meeting • , , 1907.
(JSociety,) 8vo. Wanganui, N.Z^ 190^
Washington, Navy Department :
: The American Ephemerisand Nautical Almanac, 1910, 1911.
( A me ncafi Ephsmeru Office, ) 8 vo, Waah ingtan , 1 906-1 90 7
: Astronomical papers prepared for the uee of the Amerieim
Ephemeris and Nautical Almanac, Vol, 8, pt 3.
(ilwimcara Epkemeris Office*) 4to, Washington 1 905
H. 6. Hedrick, Catalogue of Zodiacal Stan for 1900 and igjo^
reduceii to an abskjlnte system,
Washington, Philosophical Society :
Bulletin. VoL 15, pp. 27-74*
{Soeieti/,) 8vo, Waahington, 1907
Washington, Smithsonian Institution :
: Annual Report of the Board of Regents, . . . 1906:
Report of the U.S. National Mnaeum, 1907.
{htMitutiwu) 8vo. Wasbiti^^n, 1907
; Smithsonian ContributionB to Knowledge, No. 1692^ '7 1^1
{Inditution,) 4to. Washington, 1907
: Smithsonian MiBcellaneoup Collections. No, r7i7» 1710,
1721 (Vol 49); No, 1708, 1725, 1772, 1780 (VoL 50);
1791 (Vol 51),
' : Annals of the Astropbysical Observatory of the Smithaooian
Institution. VoL 2, By C. G, Abbot, Director*
{InsHtution,) 8vo, Waahtngton, 190S
Washington, United States Naval Observatoiy :
Synopsis of the Report . » . for the jear ending June jc^ 1907.
{Ohservaiori/,) 8vo. Waahingtcio, 19CSS
West Point, \3mte^ ^^^.^e. MiUtary Academy :
The CentevvmaV qI \^^l^ V \v\\.S'A 'Sva^Jfc^^^i;\^iax^ K^tak&swas.^,
(AeademlJ.^ ^X^Ssa. ^\ft.^^fl^fc£iSi!J^*«w^x^%,^
to the Library^ 1907-1908.
['03]
Whittaker (Bdmund Taylor) :
f The theory of Optical lodtruments (Camtiridge tracte 10
I mathematics and mathematical pbysics. No. 7).
{AxUhcfr.) 8vo, Cambridge, 1907
^W^olfer (A.):
*tJber ©iiien neuen Measapparat fur photographische Flatten,
i^AuthiiT,) 4to. Berlin, 1907
Ziegler Polar Expedition (the), 1903^1905 :
Scientific results, obtained under the direction of William J.
Petew . . , edited by John A Fleming.
{Estate of Wm, Ziegien) 410. Washington, D.C., 1907
Zeitsohrift fur Iiistnimenteiikiinde. Organ f iir MittheiJungen
aus dem gesararateu Gebiete der wissenechaftlichen T^chnik.
Jfthrgang 27, Heft 6-12 ; Jahrg, 28, Heft 1-5.
(Tumor and Ilorrox Fund,) 4to, Berliri, 1907-1908
j^Zi-ka*wei Observatoire Astronomique de Z6 Se :
Annale^, Tome i, fasc. i.
(Ob^ervatorij.) 4 to. Chang-Hai, 1907
[Ziirich^ Naturforschende Oesellschaft :
Viijrleljahrssciirift, Jahrgang 52, Heft 1-4.
{Socidy,) 8vo. Ziirich, 1 907-1 908
[Ziuich, Schweizerisohe meteorologische Centralanstalt :
AoDalen, 1 906, Jahrgang 43.
{Imiituie.) 4to. Zurich, 1908
PHOTOGRAPHS, Etc, PRESENTED TO THE SOCIETY.
American Philosophical Society— Bronze medal commemor-
ating the Benjamin Franklin bi-centenary.
I Barnard (H. B.)^Colkitype reproductions of photographs of the
^lilky Way, etc. (36 plates),
[ Cooper (Miss) — Framed lithograph of landscape showing Donati's
Cumet, from a drawing by Miss Charlotte S. Cooper^ Markree
Observatory,
II Dolmi^e (C. Q, J.) — Photographs of Minor Pknets, etc,, by
■ Prof* Max Wolf, Heidelberg (6 prints).
Pranks (W. S.) — Photographs of the Great Nebula in Orion and
Nebula in Cygniis (lantern slides).
B JohnBon (R, O.) — Photograph of Comet Daniel, d 1907 (print).
Knobel (B. Bj—Phutographs of the Moon from negatives by
^m >L Piiiseux, Paris Observatory (3 trans parendea\.
[i04] Lid of AdddHom to the Library^ 1907-1908.
look Observatory — Photograph of the Great Nebula in Orion,
taken with the Croaeley Reflector by G. D. Perrine (trans-
parency), and photographs of the total solar eclipse, 1908
January 3, taken by the Crocker Eclipse Expedition to Flint
Island (3 lantern sUdes).
MaoMahon (P.A.)— Portrait of Dmitri MendeljefF.
Royal Observatory, Greenwich. — Photogrfetphs of sun-spots,
nebulsB, comet d 1907, Jupiter's satellites YI and YII, and
Saturn's satellite IX (7 transparencies).
Mount WilBon. — Speetroheliographs
and calcium flocculi (5 bromide enlarge-
Ek>lar Observatory,
showing hydrogen
ments).
Wolf (Max). — Photographs of the northern Hilky Way and of
Comet d 1907 (18 transparencies).
I
A*^.!^ 1 7 1938
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