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Observatory of the Ebro,

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The January Eclipse of the S
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The Face of the Sky for January.

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KNOWLEDGE & SCIENTIFIC NEWS.

V CONTENTS, v

Lightning Flaslies from Eartli to Cloud. By William

J. S. LrcKVER, M.A., Ph.D., F.R.A.S. (tiith illiislratioiis) i

Observatory of the Ebro {with iUiistraiions) .. .. 3

Lord Rosse s Smaller Telescope. By The Rev. J. T. W.

Cl.\riih,e, M a., F.R.A.S. (i:-it!i illustration and diagram) 5

A New Volcanic Island (..;7/i illiistrntio'is) .. .. .. 7

The January Eclipse of the Sun .. .. .. .. 9

A Perpetual Calendar. By Charles E. Benham .. 9

White Ants. By H. H. Scammell, F.C.I.S. {witli illustration) 10

The Pleiades .. .. .. .. .. .. 12

Photography: Pure and Applied. By Chap.man Jones,

F.I.C., FC.S., &c 12

—Astronomical. By Charles P. Bdtler, A.R.C.Sc.

(LoND.), F.R.P.S 13

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Botanical. By G. Massee

Chemical. By C. Ainsworth Mitchell, B.A. (O.xon.),
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Notes.

F.R.:

The Face of the Sky for January.
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VI.

KNOWLEDGE & SCIENTIFIC NEWS.

[January, 1907.

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Knowledgfe & Scientific News

A MONTHLY JOURNAL OF SCIENCE.

Conducted by MAJOR B. BADEN-POWELL, F.R.A.S., and E. S. GREW, M.A.

Vol. IV. No. i.

[new series.] JANUARY, 1907.

[stationers' Hall

.]

SIXPENCE NET.

CONTENTS.— See page V.

Lightning Flashes from Earth
to Cloud.

By William J. S. Lockver, M.A., Ph.D., F.R.A.S,

(Continued fyom page 601, Vol. III.)

The second photograph of an upward discharge, to
which mention above has been made, and which is here
illustrated in Fig. 5, was taken by Mr. James Craik
when he was at Heme Bay some years ago. Here we
see both the earth and cloud ends of the flashes, and
the ramifications are in both instances directed
upwards.

In this photograph we have a unique example, so far
as I am acquainted, of two upward flashes photo-
graphed on one plate. The third and last photograph,
which, 1 believe, represents an earth-to-cloud flash, is
that illustrated in Fig. 6. For this photograph I am
indebted to Mr. J. F. Xewman, who secured this fine
ramified flash at Berkhamsted in July, 1904. This dis-
charge has everv appearance of being directed upwards
for the intensities of the three ramifications diminish
rapidly in the upper portions of the illustration. If the
flash were a perspective effect, the branches would
most probably be relatively more intense than they are
in the photograph.

The above-mentioned photographs give us sufficient
evidence to indicate that it is extremely likely that
lightning flashes not only pass from the clouds to the
earth, but that they sometimes take the reverse direc-
tion. Certainly more photographs must be secured be-
fore this question can be considered settled once and
for all, and herein lies a piece of work that can be at-
tempted by anyone who has even a small camera at his
disposal.

.4nother point that requires investigation is this. It
has often been stated that a lightning flash is of an
oscillatory character; that is, is composed of a series of
discharges, which go back and forth from earth to
cloud and from cloud to earth a number of times along
the same track.

Thus, to take one instance, in an account of a pecu-
liar flash of lightning which Prof. Kayser, of Bonn,
Germany, described in \'ol. XL\TII. of the " Sitz. der
Kon. Preuss. .\kad. der Wissenschaften zu Berlin," he
wrote : —

"There remains a fourth and quite satisfactorv ex-
planation, that we have here to do with an oscillating
discharge, in which flashes in opposite directions take
place in very close proxitnily to each other. Thus the
first flash on its way from cloud to earth would leave
behind it a channel of heated air; the next discharge
from the earth to the cloud would use the same path
which would still be in existence, only moved slightly
by the wind, &:c. . . . That 'such oscillating
lightning discharges occur has been observed manv

Fig. 5. — Two earih-to-cloud discharges. Heme Bay.

^hoio by Mr. James CraiX*.

KNOWLEDGE & SCIENTIFIC NEWS.

[January, 1907.

times l)y iiii- ciiirinj^ violent tliiiiKU-rslornis. One, tlipii,
sees the lif^htnint; travel si"\('ral tiriu's I):n-k\\ aids aiul
lorwaids; the oseiilalions must, in consetiiieiice, he
somewhat slow, otherwise tiie eye could not cleteet them
in(li\ idiially. l'rohahl\- sueh disrharpes aceount for an
observation made hv Oove (i'oiji;. Ann. 35, pp. .'?7<)-3So,

Photo ly Mr, J. 1\ St-lvman,
Flir. 6.— An eartli-ta-cloud discharge. Berkhamsted, July, 11:04.

''^.kS). from which he contluded that such Hashes were
intermittent discharges. ' '

The above extract shows that Prof. Kayser not only
disag-rees with Prof. 'I'ait's subjecti\e origin of the
observation of the direction of flashes mentioned in a
previous paragraph, but appears quite convinced tiiat
oscillati.ry discharges take place. It may be remarked,
however, that Dove gave no indication of the direction
of travel of the discharges, but simply termed them
"intermittent," .so that the flash he observed might
have been compo.sed of either all cloud-to-earth or all
earth-to-cloud flashes.

So far as I am aware, the oscillatory nature of a
lightning flash has still to be proved.

1 his question of oscillation is, however, of great im-
portance, especially when lightning conductors are in
consideration. Thu.s we read (" Modern Lig-htning
Conductors," Killing-worth Hedges, 1905, p. 11) that
'■ although it has not been conclusively proved that
lig-hlning is oscillatory, it is easier to explain its action
on this supposition, and the reason whv ordinary con-
ductors are so frequently liable to lateral discharge, is
that they are constructed on the incorrect a.ssumption
that lig-htning obeys the same laws as a constant electric
current."

Again Mr. Alexander G. McAdie, in " Lightning and
the Electricity of the Air" (Bulletin No. 26, U.S.
Weather Bureau No. 197, p. 30, 1899), wrote: —

" In the past four years we have learned, through
I lie work of Hertz and others, that when an electric
current flows steadily in one direction in a cylindrical
wire its intensity is the same in all parts of the wire;
but if the current be of an oscillatory character, i.e., a
<-urrcnt which rapidly reverses its direction, the condi-
tion no longer holds, and if the alternations are very
rapid the interior of the w^ire may be almost free from
current. If lightning, then, be a discharge of an
oscillatory nature, it may happen that the current down
the hghtnmg rod would be only sitn deep."

These two extracts indicate' very forcibly that this
question of oscillation of the di.scharge is well worth
mquiring into,

It is, however, not proposed here to consider electri-
cal oscillations which have such small periods of about
the order of a millionth or so of a second of time, but
simply those whose p<ri()ds are about one hundredth of
a second.

In the first place it is important to draw attention to
the fact that we Icnow that what sometimes appears to
the eye as a single flash is in many cases a scries of
separate discharges. This fact has been clearly shown
to be the case by photographing such flashes with a
moving camera.

Now, what we wish to know is, are such discharges
oscillatory; that is, if the components Ix' photographed,
arc the flashes cloud-to earth and eartli to-cloucl dis-
charges alternately?

Here, again, I think the same method of investiga-
tion, namely, the moving camera, may help us, and we
may be enabled to detect whether this alternate reversal
of the direction of the current does or does not occur.

It has been indicated above that the ramifications of
a lightning flash branch off the main stream in the
direction of travel of the flash. If, therefore, flashes
oscillate, as stated above, then should not the separate
images of the ramifications from each individual main
flash (photographed on a moving plate) he directed
alternately downwards and upwards ?

Photo In, Hen Wall,!-.

Fig. 7.— A multiple lightninfr flash, showing the ramifications of the
separate discharges, all directed towards the eartn. Ham-
burg, May 30, 1902.

Now what do photographs taken in this manner
inform us? In every single case, and a whole host of
" multiple " flash photographs has been examined,
the ramifications are all turned towards the earth; that
is, all the individual flashes were cloud-to-earth dis-
charges.

January, 1907.]

KNOWLEDGE & SCIENTIFIC NEWS.

As an illustration of one of the photographs bring-
ing out this point very clearly, let me put before the
reader this reproduction (Fig. 7). For the use of this
photograph I am indebted to Herr Walter, of Ham-
Ijurg, who secured this most interesting " multiple "
flash photograph on the night of May 30, 1902. The
motion of the camera was directed horizontally by
means of a special mounting operated by clockwork.
In this case the first flash that fell on the plate was
that on the left, while those towards the right occurred
subsequently. As will be seen, this flash was really
composed of five individual flashes, althoug^h to the eye
it appeared single. The intervals of time between the
individual flashes, counting from left to right, were
o.oj6, 0.036, 0.028. and 0.144 seconds, and the total
duration of the discharge was 0.244 seconds, according
to Herr Walter's statement.

On examination it will be noticed that the first flash
was from cloud to earth, the ramifications being
directed downwards. In the second flash also the same
direction was maintained, and the branches, although
fewer in number, were also directed towards the earth.
It is worth while drawing the reader's attention to the
faintness of the fourth ramification from the top of the
first flash and to its great increase of intensity in the
second flash. This indicates in a striking manner not
only that the direction of the electric current remained
the same, but that even this subsidiary path already
made for it by the previous flash was more fully utilised
by the second.

As the cloud was being discharged, so the flashes be-
came weaker and weaker, and the ramifications fewer,
until the final flash is the least intense of the five, and
is devoid of all ramifications. In no case have any of
the branches an upward direction, so that in this in-
stance it must be acknowledged that all the flashes
were from cloud to earth.

It has been pointed out to me that it does not
necessarily follow that, because all the ramifications on
the individual images were directed towards the
ground, the discharge is not of an oscillatorj' nature.
The reason given was that the first discharge would so
" ionise " the atmosphere along the path it took in
going from earth to cloud, that the return flash to the
cloud would find the least resistance along the same
track, including even the ramifications. If this be
granted for a moment, an examination of the photo-
graph from many points of view suggests that this is
not the case.

Since the flash on the left in Fig. 7 was the first to
occur, this discharge is necessarilv a cloud-to-earth
flash, because the ramifications are directed downwards.
.\ssuming, then, that the second flash is a discharge
from earth-to-cloud, should not its bottom or earth end
l>e stronger than its cloud end, and also stronger than
the earth end of the first flash? The photograph does
not endorse this view.

Again, how can the strongest ramification of the
second flash l>e explained if the main flash be an earth-
to-cloud flash? It seems to me that the peculiarities
of this series of flashes are quite easily explained if the
assumption be made that the discharges are all in the
direction of cloud to earth.

It is quite possible, however, that the photographs
already examined were " multiple " flashes, but not of
an oscillatory character. It would, therefore, be of
great interest if those who photograph lightning flashes
would sometimes employ a moving camera to trv and
obtain records of "multiple" flashes, which exhibit
ramifications which are alternately directed to earth
and to cloud.

Having drawn attention to the occurrence of earth-
to-cloud lightning discharges, as exhibited in a few-
photographs which I have been fortunate enough to
secure, it is very probable that many more photographs
are in existence which are of a similar character. It
would be useful, therefore, if those who possess light-
ning-flash photographs would examine them critically
from this point of view, for it seems that such dis-
charges are of more common occurrence than was at
first believed.

Should such a search be the means of bringing to-
gether a greater number of specimens of earth-to-cloud
flashes, a great favour would be conferred on the writer
of this article if he could be informed, because it is onh
by the close study of many of such photographs thr.
valid conclusions can be drawn.

Observatory of the Ebro.

Notes of the 1905 Eclipse.

Many circumstances have combined to render the
foundation of a new Spanish obsen'atory of great inter-
est and importance. There is first the feelmg of not
unnatural surprise at such a happening in a country
which had for many years been regarded as non-pro-
gressive, and by some writers freely labelled decadent,
dying, effete, or some other equally uncomplimentary
epithet. Signs of revival are now- more numerous,
and a King on his own feet with an English Queen to
sympathise with his modern ideas bids fair to modily
many of the harsh criticisms passed of late years upon
his historic heritage. Yet the observatory is only in a
sense of Spanish growth. It is the latest branch of the
scientific activity of the powerful Society of Jesus,
whose labours at Kalocsa, at Hereny, at Stonyhurst, at
Georgetown, D.C., at Havana, at Manila, and many
other posts are landmarks in the domains of astronomy
and cosmical physics.

In succession to the late Father Juan, Father Cirera,
in charge of the magnetic department at the Philippine
Observatory, pursued the investigation of the periodic
variations of the magnetic elements until circumstances,
possibly not unconnected with the change of ownership
of those islands, which did not, however, involve any
immediate stoppage of the work, recalled him to Spain.
Loth to give up the investigation to which for more
than ten years his energies had been applied. Father
Cirera obtained the sanction of the Provincial Head of
his Order to the establishment of an observatory in
.\ragon, at which that work might be continued.

The question of funds had, of course, to be con-
sidered, in addition to the choice of situation and equip-
ment, and several years were devoted to preparation.
Most of the best known Furopean observatories were
visited in turn, and much time spent in picking up new
ideas at the Paris Exposition; in fact, a whole year
was spent in Paris, and ten months at Stonyhurst,
shorter visits being paid to Kew and Cireenwich, and
at the beginning of igoj a site was chosen which
possessed the strong recommendation, among others,
that it lay within the region of totality for the eclipse
of August 30, 1905, which incidentally fixed a date
before which the installation sln)uld be, if possible, com-
pleted.

Father Cirera had been struck with the poverty in
modern electrical and seismological equipment of the
observatories of England and France, and prtxeeded
to those of Belgium, IJermany, .\ustria-Hungary, and

KNOWLEDGE & SCIENTIFIC NEWS.

[January, 1907.

Italy to supply the dctkicncy. Enlistini,^ tlie poworlul
aid ol' a wealthy Spaniard residing in Paris, plans
were soon drawn up for the l)uildings to he erected on
the chosen site near Torlosa, on a small eminence in
the \allev of the llhro, inconveniently far frotn a town
for huildint; purposes, hut for that \ery reason tho hct-
ter suited for a maL;netic ohsorv atory. The interest
aroused in the Jesuits' "(ienera]." iollowini; on the rn-

Photosrraph of the Corona at Vinaroz]

thusiasm ol Senor Landerer, perhaps the best qualified
astronomer in -Spain, who assured the Superiors that if
they made haste their observatory would be the first of
its kind, in fact absolutely unique, caused them to
sanction the pursuance in its entirety of a scheme from
which, had they fully realised its financial magnitude,
they might well have shrunk.

Imagine the delight of a director given Cdrte blanche
or nearly so, and how he would revel in the very latest
devices for each of his departments. It is not surprising
that his long sojourn at Paris encouraged him to en-
trust the orders for apparatus very largely in that
centre; but wherever other nations had specialised, the
advantages of Paris were at once foregone, so we find
the new observatory equipped with an English magneto-
meter, Italian seismic instruments, and certain electri-
cal and meteorological contrivances of German make.
The Rowland grating also is not of Paris origin.

The new instruments were tested just where Father
Cirera thought the testing would be easiest or most
reliable, usually in the country of origin — the Dover
magnetometer at Kew, the dip instrument at Pots-
dam, the spectroscopic apparatus at Meudon, and so
on. Eschenhagen's dip apparatus found an ardent
admirer in Father Cirera, for whom it was difficult, if
not impossible, to understand why Greenwich feels
bound to adhere to the principle of continuity.

Whenever resources ran short, Providence, in Father
Cirera's pious narrative, found new patrons both in the
Spanish colony at Paris and also in Barcelona; and
when apparatus began to arrive many distinguished
scientists of the Jesuit confraternity .seemed to be avail-

at the new m-
n posts or just

able to lend their valuable assistance
stallation — just returning from foreij
preparing to take up work abroad.

^et, after all, things were not quite perkcl in time
foi tho eclipse. Many adjustments had to be post-
poned, as they would take too long, and the eclipse
must be considered lirst. I lie magnetic basement was
uncomfortably damp until time was found to isolate it
In means of a deep trench from ])ersistent infiltration on
one side. .\ second ccelostat was presented in time lor
the eclipse, but there was not time to alter the arrange-
ment by which the first one had to do duty for two
instruments. The spectroheliograph, again, was un-
satisfactory, and had to be returned to the makers, but
was meanwhile used for the eclipse. Other improve-
ments in lighting and re-arrangement of buildings have
taken place from time to time. There is a 4-horse
power Crossley dynamo-motor, and a set of accumula-
tors; also a large acetylene generating- station, so that
neither light nor power [e.g., for maintaining water
supply) is lacking in any part of the domain, about
which a few words of description are necessary.
Situated in N. latitude 40" 49' and slightly to the East
111 Greenwich, though less than two minutes from the
prime meridian, it lies about a mile from the right bank
of the Ebro and twelve from the sea, on the borders of
Catalonia and \'alencia, its local situation being on a
small elevation similar in height to Greenwich hill, but
not so steep. Communication is easy, for a few
minutes' walk brings one to the horse-tramway from
Roquetas to Tortosa, a station on the Barcelona Rail-
way, but there are no electric trams, no minerals, no
basalt formation, so that the place is very suitable for a
magnetic observatory.

Pliotograph of the Corona at Vinaroz.

Magnetism is, however, only a branch of the work,
which aims at the investigation of every effect of the
sun on the earth, and so includes, of necessity, not only
every branch of meteorology and atmospheric elec-
tricity, including even such special researches as the
ioni.sation of the atmosphere, but also an astrophysical
laboratory, in addition to the indis]>ensable astronomical
time service.

January, 1907.]

KNOWLEDGE & SCIENTIFIC NEWS.

The instrumental equipment includes a twin equa-
torial of 6i-inch aperture, the visual of 8 feet focus and
the photog-raphic of 7 feet, with an enlarger giving- an
8-inch image, an Evershed 2-slit spectroheliograph, a
spectrogoniometer, and a prominence spectroscope.
These, with a Grubb coelostat and a Rowland grating
practically complete one department.

Most of the meteorological registers are obtained
with Richard instruments, but there are other forms of
apparatus — for measuring the total number of ions per
volume of atmosphere (Gerdien), the relative num-
bers of positive and negative ions (Elster and Geitel),
Hertzian waves (Branly), and electrical potential (Mas-
cart). An Arago actinometer with black and bright
bulbs in vacuo is employed, and an Angstrom pyrohelio-
meter, as recommended by the Solar Union, whose
Oxford meeting Father Cirera attended. In addition
to the Besson nephoscope is another with a wide angle
lens in the roof of a sort of kiosk, which produces an
image of the sky and clouds on a table below, some-
thing after the manner of a camera obscura, rendering
measurement very simple.

One interesting feature of the photographic magneto-
graphs is the use, instead of " hour " breaks, of an
extra lamp onlv lighted at the hours, causing a black
line across the trace instead of a white one, and en-
abling the adjustment of the "hour" light for any
period from i to 80 seconds as required.

Time presses, and we must leave many interesting
details, only noting that a daylight time signal being
insufficiently conspicuous, owing ,to distance from the
centres of activity, where it would be of value, a night
signal with white and green lights has been substi-
tuted, ending at g p.m. The neighbouring Jesuit
college for advanced students, to which, in a sense, the
observatory is an annexe, provides some assistance,
and demands some training and lectures, and there are
also regular days and hours for visitors.

For the eclipse, preparations on a special scale were
made. - Jesuits from all parts of the world were freely
invited to Spain, and though many well-known
scientists declined, owing to press of other work, yet
quite a large number accepted, and arrangements were
made to spread out along the .Spanish totality track
such of the visitors as brought their own equipment,
leaving those totally unequipped to assist either at the
new observatory or elsewhere, in order not to risk loss
through too great concentration.

Briefly, the local programme comprised visual ob-
servations of times of contact and chords, photographic
observations of internal contacts, spectroscopy, polarisa-
tion, photography and drawings of the Corona, photo-
metric observations, shadow-bands, atmospheric ionisa-
tion and electric potential, Hertzian waves, and solar
radiation; also atmospheric temperature and humidity,
observations of plants and animals, variation of
magnetic elements, and earth currents.

It was unfortunate that light clouds in great measure
interfered with the more delicate spectroscopic part of
the programme, and to a less extent with other por-
tions, but the truly comprehensive nature of the pro-
gramme gives a good indication of the scope and possi-
bilities of the new observatory, while in some direc-
tions, notably in the magnetic observations, so strongly
insisted on by the editor of Terrestrial Magne/ism, a
distinct success appears to have been achieved. The
smaller expeditions to other places in the zone, in-
cluding that under Father Cortie at \'inaroz, and of the
German Jesuits at Burgos, were more or less successful,
but do not .so conspicuously belong to our present
subject. Illustrations from " Memoires de L'Observa-
toire de L'Ebro." No. i.

Lord R.osse's Smsiller Telescope.

By THE Rev. J. T. W. Claridge, M.A., F.R.A.S.

The knowledge of the existence of the far-famed Lord
Rosse's 6 ft. Reflector and its achievements comes to the
vast majority of the public from magazine sketches and
photographs ; but few, comparatively speaking, are
aware even of the existence, or of the important and
delicate work accomplished by the 3 ft. Reflector, as seen
in the photograph which we here exhibit. These won-
derful instruments may be mentally pictured and con-
jectures entertained as to their actual appearance and
situation, but those who have never seen these great and
powerful searchers of the heavens can form no idea of
the quietude and loveliness of their surroundings. On
one side is a large lake bordered with trees and covered
with water-lilies, its still surface only disturbed by
numerous wild-duck and other water-fowl. On the other
is the majestic castle with its lawns and terraces, merely
a stone's throw from the world-renowned telescopes.
The builder of these, \Mlliam Parsons, third Earl of
Rosse, and father of the present Earl, was born at York,
June 17th, 1800. He succeeded to the title and estates in
1S41. It was as far back as 1827 that his scientific mind
encouraged him to experiment on the improvement of the
reflecting telescope (for he had no experience whatever in
the construction of the refractor), and to this object the
whole of his attention was directed.

Sir \Vm. Herschel was the first to construct a reflector
on a large scale, but he was not altogether so very
successful, though he made specula — one of 18 m.
diameter, and one of 4 fest — for his 40 feet telescope. Un-
fortunately he never left any written account of his
methods. Consequently Lord Rosse had very little as-
sistance to guide him onwards to the goal of success which
he ultimately reached. To grind a speculum of only 6
or 8 inches in diameter in those bygone days was a work
of no ordinary labour and skill, and such a one was then
considered of great size. A gentleman of the name of
Ramage possessed a reflector of 15 in. diameter, and a
focal length of 25 feet, and this was for a long time the
largest actually in use, for, although Sir \\'. Herschel's
was much larger, it appears that he very seldom used it.
Notwithstanding the difficulties that confronted him,
added to the apparently sinall successes of his pre-
decessors, the indefatigable nobleman, endowed as he was
with such remarkable mechanical and mathematical skill,
untiring patience, and a dogged perseverance, set about his
arduous work with a zeal that by-and-by crowned all
his efforts with triumph. After many trials as to what
combination of metals was the most advantageous for
specula, as regards their whiteness, porosity, and hard-
ness, he discovered that copper and tin when united in
their atomic proportions — viz., copper I26-4 parts to tin
58-9 parts — was the best. This compound is of a brilliant
lustre and hardness, yet very brittle, and with a specific
gravity of 8 8 was found to be freer from pores than any
other with which he was acquainted. Having thus
ascertained the desired proportions, he set about casting
the speculum. The difficulties attending this process
were such that, instead of having the reflector, which was
to be 3 feet in diameter, in one piece (which was sub-
sequently done), he tried the expedient of casting it in 16
separate portions. When cast, these pieces were fixed on
a bed of zinc and copper, mixed in the proportion of 2-75
of the latter to i of the former, a species of brass which
readily expanded in the same degree as the speculum
metal. The several pieces were then ground as one body
to a true surface, and when soldered and polished were

KNOWLEDGE & SCIENTIFIC NEWS.

[January, 1907.

considered highly satisfac-
tory. Great difliculties were
experienced in the casting in
the !-and, and extreme care
in the cooling period of 6
days was retjuired. .\s it
was, several large castings
were cracked. However, by
using hoop iron at the bottom
of the mould he was enabled
by this to allow the gas
developed to escape, thereby
freeing the <;peculum from
pores and air-bubbles. After
the 6 days' cooling the disc
was ready for further develop-
ment. It was about 3^; inches
thick, and weighed 13 cwts.
The metal for it was placed
in 2 cast-iron crucibles and
melted by turf fires, as these
were considered steadier than
those produced by coke.
Before the speculum was
polished it was worked to a
spherical figure by the grind-
ing procefs. A steam engine
of 3-horse power was the one
employed for this purpose.
The grinder was made of
cast-iron, with grooves cut
lengthwise, across, and circu-
larly on its face. These
grooves were one-quarter of
an inch wide, and half-an-inch
deep. The polisher and the
speculum have a mutual action
on each other. The polisher
was further coated with pitch,
and on this was spread
either oxide of tin, as used
by Newton, or oxide of
iron (" crocus " as it was
then called), as used
by Lord Rosse. It
was necessary that
this pitch coating,
as well as the emery.

The Machinery of the Telescope with the 3 ft. Speculum as it appeared in 1839.

which was also employed, should be evenly distri-
buted,and that its lateral expansion in the grinding process
should be the same. At length the telescope was com-
pleted in September, 1839. Lord Rosse, in a paper read
by him before the Royal Society in London, in June, 1840,
describing the construction and building of the telescope,
said that from " September to Christmas, 1839, all op-
portunities for observing were taken advantage of. A
considerable number of Sir John Herschel's test objects
were examined, and as to double stars, perhaps the most
striking contrast between its action and that of other
instruments was the extreme brilliancy of the minute
companions of large stars — e.g, the companion of Polaris,
which, with a power of 600, was very like Polaris
itself in a 44-inch achromatic with a 2^-inch objective.
The companion of Alpha Lyrae and Rigel were brilliant
objects." He was very confident that as to the Nebula^
' the present instrument will add something to our present

knowledge." " I
think I may say," he
continued, "that the
Nebulffi 27 Messier,
the Annular in Lyra,
and, what, perhaps,
is more curious, the
edge of the great
Andromeda, have
shown evident
symptoms of resolv-
ability. Clusters
were examined and
drawings were made.
My friends were de-
lighted when they
examined the Crab
Nebula." The
powers used were
600, 800, and 1,000.
The instrument

%

January, 1907

KNOWLEDGE & SCIENTIFIC NEWS.

acted very powerfully on the lunar surface, and showed
a variety of details not marked in Beer and Madler's
map.

The accompanying sketch which is a copy of the one
made by Dr. Woods, a physician, 60 years ago at Parsons-
town (now called Birr), shows the original instrument
with its machinery. The tube is 26 feet long, and the
whole is supported on 4 wheels running on the iron circle.
The pivot on which it turns, the wheel and axle for rais-
ing or lowering the instrument, the counterpoises, and the
observer's gallery will be easily recognized. It certainly
was then regarded as the finest instrument in the world,
until it was surpassed and thrown into comparative in-
significance by the mighty 6 feet speculum, erected close
by, and which remains to this day the largest of its kind.
This was completed in 1842. It was very pleasing to
note that the whole of the machinery, buildings, and
everything connected with both of these instruments was
done by local artisans and under the immediate superin-
tendence of the great astronomer, who died October 31st,
1867. Looking at the original and the modern 3 feet tele-
scope, we see that many alterations and improvements
have been made. Under the present Earl it wears an
entirely different aspect to that which it wore in that
memorable month of September, 1839. Of late years it
has been employed very largely for planetary observations.
From i8Si to 1886 the planet Jupiter especially was the
object upon which a great amount of attention was be-
stowed. When it was first completed it was mounted as
a Newtonian on an altazimuth stand, but as that was not
altogether suitable for observations requiring absolute
accuracy, it was afterwards mounted equatorially, which
renders it adapted for photographic and spectroscopic
work. Here it may be observed that a most important
achievement in astronomical science was made by
means of this 3 feet reflector. It was for a long
time a debated question among scientists, "Does
the earth receive any heat from the Moon? ' It
was at last decisively settled by the aid of this
instrument that lunar heat does enter our atmo-
sphere, though the amount is extremely small, being
about one twenty-thousandth part of a degree (Fahr.),
and to the labours and observations of the present
holder of the title this addition to our scientific knowledge
is due. These lunar heat observations are still being
pursued.

Such is a brief account of the history of this remark-
able instrument, and though not to be compared with its
powerful 6 feet neighbour, still it has rendered, and will do
so under the present skilful management and direction,
ever-increasing help in research into the vast domains
of the Universe.

Who's Who (or 1907.— We have received a copy of TF/io's
IVhii for 1907 (.\. and C. Black ; los. 6d.), which has been
revised, corrected, and considerably aup^mcntcd. It is so
entirely trustworthy and complete a book of reference thai
it inspires one with a feeling of wonder as to what the
world's workers did without it in the years prior to its
publication. It now numbers 2,000 pages and more than
ten times that number of biotjr.'iphies. \o praise roiild be
too hijijh for its thorouf^^hncss and completeness.

Who's Who Year Book, pulili^hcd by tlie saiiie publishers
at tlie price of .-i shillintf, supplements the larger volume
witli a valuable collection, in tabular form, of scientific,
official Parliamentary, social, university, ;uid nrtistic in-
formation. It is a compressed directory.

A New Volcanic Island.

The Third Bogoslof.

Some weeks after the Californian earthquake, the
officers and crew of the U.S. Fish Commission Steamer
Albatross, while on their way, under Captain L. \l.
Garrett, to investigate, with Professor Charles H.
Gilbert, the fisheries of Japan, passed the group of
islands known as the Bogosiofs, and to their astonish-
ment, perceived that a third island had been added to
the other two. Professor Gilbert, in a personal letter
concerning the first sight of the island, on May 28,
writes : —

When I saw the Bogosiofs in 1890 there were really two
small islands about I5 miles apart, one of them steaming
and the other cooled off. [.As will presently appear, all three
of the islands were of volcanic origin, one having arisen
more than a centur)-, and the other twenty-three years, ago.]
This has been the condition for a number of years, so the
hot one had received the name of Fire Island, the cold one.
Castle Island. When they came in sight yesterday, we were
astonished to find that Fire Island was no longer smoking,
and that a very large third island had arisen half-way be-
tween the other two. It was made of jagged, rugged lava,
and was giving off clouds of steam and smoke from any
number of little craters scattered all over it. .\round these
craters, the rocks were all crusted with yellow sulphur.

In a later letter, written from ^'okohama. Dr. Gilbert
said : —

I wrote you a full account of Bogoslof, but the letter
seems to have miscarried. Our discovery seems to have
been corroborated later by some revenue cutter, but if the
newspaper report agrees with their findings, very extensive
changes took place in the interval between the two visits.
When seen by us, the new cone, occupying much of the
space between the two older ones, was somewhat higher
than either, but was certainly far from qoo feet high — 300
feet would be an extreme figure. There was no evidence of
a central crater. The steam and fumes were given off
most abundantly from cracks and fumaroles on the slopes.
.About these were heavy incrustations of sulphur. We saw
no indications of boiling water, nor did we believe that
landing would be impossible.

.As we have said in parenthe,sis, all three of the Bogo-
siofs, which are about uo miles south of the PribvlofT
Seal Islands, have risen from the sea. hot and steaming,
in historic times. The Pribyloff Islands, as Professor
Starr Jordan remarks in an article on the Bogosiofs, in
the Popular Science Monthly (New York), had an origin
similar to that of the Bogosiofs. That thev are of
volcanic origin, their composition leaves no room for
doubt. Of the older Bogosiofs, one of which has for
twenty years been known as New Bogoslof, Dr. Grove
Gilbert, writing seven years ago, and noting the rapid
disintegration of the islands, predicted that in this
century the name Bogoslof would. attach onlv to a reef
or shoal, were it not for the possibility of new orup-
tion.s.

It may be noted as a curious example of scientific
prescience that Dr. Gilliert went on to say : — " The
pulse of the volcano is so slow that we have noted only
two beats in more than a century, but such sluggish-
ness must not be taken as a symptom of death, or even
decline, for volcanic organisms are characteristically
spasmodic in their activity. I-ong liefore the sea has
established its perfect sway the arteries of the mountain
may again be opened and a new and larger island put
forth to contest its supremacy." The pulse of the
volcano has certainly quickened, and the floor of the
Behring Sea in this region s«vms tn l>e still unsettled,

KNOWLEDGE & SCIENTIFIC NEWS.

[January, 1907.

Old BoKoslof, or Castle Island.

(From "Tin- F.^l-i'l''! Sdcitu- Monthly." AVk' Yoih\)

Bogoslof of May, 1906. From New Bogoslof, or Fire Island.

(From " Flic Popular Science Monthly," Netv Yorli )

The Three Bogoslofs, May, 1906

(From "The Popular Science Monthly," .Vcr;' York.)

SO that astonishing changes may be looked
for at any time.

Tiic oldest Hogoslol, now called Castle
Island, rose from the sea in 1796; and
Rotzcbiic describes the first glimp.se of it,
as .socn by a trader, named Krinkof, who
had Im'cii forcecl lo seek refuge from a storm
in a iiciglibouring island. The birth of the
\()lcanic islet was accoin])aniod by an carth-
C|ii;ike which shook the island where the
traders had t:d<en refuge, and by an out-
burst of lire with thunderous explosions.
The island was said to emit fire for months
afterwards, and for eight years afterwards
the water round it was warm and its ashes
unbearably hot. The eruption of 1883, in
w hich the .second Hogoslof, called Fire
Island, wa.s born, had no witnesses ; but in
September of that year great volumes of
steam and smoke, accompanied by showers
of ashes, were thrown out from the summit
and through fissures in the sides and base,
the bright reflections from the heated
interior being visible at night. At the time
of this eruption a .severe earthquake was
fi'lt in the .sea off Cape Mendocino, appar-
ently in the line of the Portola-Tomales rift,
of April, 1906.

The islands were visited in 1884 by the
officers of the U.S. Revenue Cutter Corwin,
and Lieutenant J. C. Cantwell and Surgeon
H. \\'. Remans made the ascent of New
Bogoslof. Lieutenant Cantwell thus de-
scribes his experience in the '' Cruise of the
Corwin " : —

The sides of New Bogoslof rise with a gentle
slope to the crater. The ascent at first appears
easy, but a thin layer of ashes, formed into a
crust by the action of rain and moisture, is not
strong enough to sustain a man's weight. At
every step my feet crushed through the outer
covering and I sank at lirst anfcle deep, and
later on knee deep, into a soft, almost impalp-
able dust, which arose in clouds and nearly
suffocated me. As the summit was reached the
heat of the ashes became unbearable. . . On
all sides of the cone there are openings through
which steam escaped with more or less energy.

Seven years after that, Drs. Merriam and
Mendenhall, of the Behring Sea Seal Com-
mission, found the newer island still smok-
ing, steaming, and occasionally roaring like
a giant steam escape. The older island had
quite cooled, and had become a sheer cliff
or hill of cold ashes, and was, and is, the
home of countless sea birds, as well as of a
small herd of sea lions. Captain Cook, in
the eighteenth century, had passed by the
neighbourhood of this island. Tliis was
eighteen years, however, before it was born,
and he named a pillar of ash or rock which
he foimd there Ship Rock. Ship Rock fell
in ruins fi\e vears after the birth of Fire
Island.

The question which naturally arises is
whether the rise of the newest Bogoslof was
directly connected with the Californian
earthquake. The possibility, remark Pro-
fessor Starr Jordan and Mr. Archibald
Clark, in the article from which we have
quoted, " is heightened bv the fact that the

January, 1907.]

KNOWLEDGE & SCIENTIFIC NEWS.

great earthquake rift, which extends through the coast
range of CaHfornia, for a distance of 200 miles, follows
a direction, which, if produced northward to Behring
Sea, would pass near the islands of Bogoslof. Again,
this earthquake rift was largest, and its effects more
violent, where it entered the sea in Mendocino County
than at any other point throughout its course, the ex-
tent of the lateral movement along the crack increasing
from about two feet in Monterey County, to about i6i
feet at Point Arena, where it finally enters the sea.

" In opposition to this view may be placed the im-
probability that an earthquake rift or fault would ex-
tend so far as from the centre of California to Behring
Sea, a distance of more than 2,000 miles, and through
such depths of water as intervene between Point Arena
and Bogoslof. It is also stated that the evidence of the
seismograph, so far as understood, favours the idea
that the great earthquake was confined to California,
although its centre of disturbance was clearly in the
sea in a westerly direction from Cape Mendocino.

" It is evident, also, that the ri.se of the third Bogoslof
was attended by little, if any, disturbance in the im-
mediate vicinity. The advent of each of the other two
islands was marked by earthquake shocks, the fall of
volcanic ashes, and displays of fire, observed and felt
by the people of Iliuliuk, on Unalaska Island. The
people of this village in 1906 were unaware of the
presence of the new island until the news was brought
in by vessels touching at the harbour."

On the whole, the weight of evidence at present
seems to favour the idea that the Bogoslof disturbance
of igo6 was local in character, and the coincidence in
date with the California earthquake involves no actual
relation between the two phenomena.

The January Eclipse of the Sun.

It is truly unfortunate that the tot:d eclipse of 1907
January 13-14, whose totality track has the rare advan-
tage of being entirely on land, should fail so lament-
ably in other ways as to be practically disregarded in
this country. The reasons, or some of them, are not
far to seek, for the track commences not far from the
Northern extremity of the Caspian Sea, and, curving
in the familiar manner of eclipse tracks through E.S.E.,
E., and E.N.E., finally reaches a point among the south-
etistern head waters of the Lena Basin, not far from
the Gulf of Okhotsk. Even in mid-summer, a consider-
able portion of the track over the " roof of the world,"
is considered inaccessible, but in mid-winter, the oc-
cupation of more than a few of the most favourable
points is unthinkable. In Western Turkestan, where
the line of totality goes nearly a thousand miles further
south than London, there would ;ippear to be the best
chance of reasonable conditions, but most of the land
lies so high in Central -Vsia that bitter cold is almost
a certainty, though in a few sheltered valleys it will
be less rigorous. Communication is better than it
was a few years ago, for there is direct railway con-
nection with Europe via Moscow and Orenburg to
Tiishkent, .ind between that Ob.servatory and
Sainarcand are several stations not far from the
central line, of which, |)erhaps, Jizak is the most access-
ible. Tsairosu, in Mongolia, is the only station
further East than Turkestan that has been suggested
for occupation, hut the princip.il expeditions will bo
Russian, and of these M. Hansky's is sure to be well

to the fore. There are expeditions planned from Ger-
many, under the auspices of Dr. Schorr, of Hamburg,
and from France, equipped by the Bureau des
Longitudes. Many will remember the success that at-
tended the Russians and others at the ill-fated eclipse
of 1896, but that was in August. We can only hope
that the results on the present occasion will be com-
mensurate with the zeal of those who are braving the
unpromising conditions. Doubtless, had an official
expedition been .sent from England, several enthusiastic
amateurs would have been prepared to accompany it
if possible, the more so that the chances of success in
January 1907, though perhaps not encouraging, are
quite as good as, and in many ways better than, those
of any other eclipse in the next five years, which will
be singularly barren in that respect.

The present eclipse belongs to a series (recurring at
the well-known period of 18 years 11 days"), whose
first member was the celebrated Siege of Paris eclipse
of December 1870, when Janssen escaped from Paris
in a balloon in order to observe the eclipse in Algiers,
and saw nothing of it owing to cloud.

A Perpetual Calendar.

By Charles E. Benham.

The practical utility of a simple method whereby, with-
out pencil, paper, or reference table, one is enabled
to tell almost in a moment the day of the week for any
given date is so great that anyone who has been at the
small pains necessary to master the process will never
repent of having done so. On the contrary, he will
only wonder that a formula so simple and so advan-
tageous is not made a part of the regular curriculum of
every elementary school.

At a first glance the system prescribed may seem a
little complicated, but with very little practice it be-
comes perfectly easy and simple, while anyone with a
natural talent for mental arithmetic may speedily ac-
quire ability to perform the process with such rapidity
that his powers seem, to the uninitiated, little short of
magical.

The method depends primarily upon a system of
casting out the sevens, that is, dividing by seven and
taking only the remainder. Thus, 24, when the sevens
are cast out yields 3; 21, o; 40, 5; and so on.

Bearing tliis in mind, the process for a perpetual
calendar is simply to add together four numbers, repre-
senting respectively century, year, month, and day of
month, casting the sevens out as the addition proceeds.
Thus, if those four numbers were o, 23, 6, 14, we
should add together o, 2, 6, and 0 = 8, or, casting out
the sevens, i, which would mean that the date in ques-
tion was on the first day of the week, or Sunday.

But what we have to arrive at is how to ascertain
the four appropriate numljers for a given century, year,
month, ajid day.

The rule is as follows : —

(i) For the Century Numbers. — These must be
memorised, 2 for the century 1800-99, o for 1900-99,
and 6 for 2000-99 These are thus fixed for con-
venience, because the system Ix^ing calculated on this
basis, the o for tiie present century, which is most
likelv to be wanted, will sa\e calculation. Tliis ar-
rangement is a modification, by Mr. Robert Cook, of
Chelmsford, of Howard's Per|>etual Calendar, in which
the o was fixed for the previous century.

10

KNOWLEDGE & SCIENTIFIC NEWS.

[January, 1907.

(2) For the Year. — Cast out the sevens from the last
two figures of the year and add the quotient of the
same fiijures divided by four, nci^locting fraclions.
Thus, for i860, the number is 4 + 15 = 19. o''- ^'asling
out the sevens, 5. For 1906 it is o, for i8^o it is
5 + 10, or, casting out the sevens, i.

(3) For the Month Nuinbeis. — These must be
memorised ;is follows: —

Jan.

Feb.

Mar.

.Vpril

May

June

I

4

4

0

2

5

July
0

Aug.
3

Sept.
6

Oct.

1

Nov.
■1

Dec.

0

r*"or leap years, januaiy is o, l'"el3ruary ,^, llu- others
being unaltered.

(4) For the Day Number. — This is simply the num-
ber of the day of the month, casting out the sevens if
neoe.ssary. Thus, the 3rd is 3, the J^tli is 4, the 31st
is 3, and the j8th is o.

Fxamples of the application of these rules : — ■
Given such a date as .April 15, i860.
The century number is ... 2
The year number is ... ... 5

Casting out tiie .sevens ... ... o

The month number is ... ... o

The day number (casting out 7's) i

Total ... I
The day is, therefore, .Sunday.

Januar\' 13, 1904.

Century number ... o

Year number ... ... 5

Month number (leap year) o

Day number, 13 (casting • ,

out the sevens) ... 1

Total ... II or casting out the
.sevens, 4.
The day is, therefore, Wednesday.

VVhen the process is carried out mentally, it will
be immediately seen in practice that the casting out
the sevens as the addition proceeds, does not encumber,
but simplifies the operation, as it reduces the addition
to small numbers, and the calculation is soon per-
formed with surprising rapidity.

\\'ith regard to leap year, it must be borne in mind
that at the even centuries there is no leap year unless
divisible by 400. Thus, 1900 is not leap year, nor 1800,
but 2000 is.

THE SUGGESTED BOOK CLUB.

So very few applications ha\e been received for mem-
Ijership of the proposed Scientific Book Club, that we
much regret to say it will be impossible to proceed with
It. Had only a few hundred applied we might have
started the library, even at a loss, but, as "it is, the
numbers are such as to show that there is practically no
demand for such an institution. The books alreadv
purcha.sed will be sold off, and a priced list of them wi'l
appear in our next issue.

White Ants.

Bv F. H. ScAMMEi.i., F.C.I.S.

riiiiki-; has Inin considerable diversity of opinion as to
what distinct family the insects commonly known as
White Ants, otherwise Termites, belong. In some re-
spects thev restinble one of the principal insect divi-
sions, and in other respects a second. Recently, how-
ever, they have been placed by some authorities by
themselves in an order known as " Isoptera." The
name " White Ants " is somewhat misleading and in-
correct, for they differ widely from true ants, and only
in some cases are they white. At present there are some
300 distinct species known to entomologists, though
there are probably many more. They are found only
in warm climates, and, with very few exceptions, are
entirely vegetarian in their diet. The basis of their
food is wo<Kly matter. Certain varieties, however,
cultivate, in their termitaria or nests, a peculiar form
of fungus upon which they feed; others for the same
purpose cut and store up grasses. Termites are par-
ticularly cleanly, and consume their dead and any other
objectionahle matter which is in their way. They also
themselves prepare a peculiar kind of food, of earth,
grass, and a salivic deposit from their own bodies.
Their chief diet, however, is wood. They usually pre-
fer soft woods such as European deal, but there is
scarcely any wood which can be regarded as entirely
proof against their voracity. Even the well-known
West Australian jarrah is attacked by them, although
they prefer other kinds of timber. It may be here noted
that the comparative immunity jarrah enjoys largely
depends upon the ground upon which it is grown, that
grown in the ironstone ranges being more immune
than the same wood from other parts of the State.

Termites are gregarious insects. They live in fami-
lies or colonies and appear to be governed by laws and
to work systematically. Different varieties construct
totally ditTerent kinds of dwellings. Some take up their
abode in trunks of trees, while others construct mounds,
rising in some cases as high as 18 feet, a third variety
dwelling in subterranean passages, burrowed in the
ground, or simply living in decayed pieces of wood.
The number of individuals in a colony may run from a
few hundreds to hundreds of thousands. In most
varieties the inhabitants of a colony are usually confined
to the offspring of one Royal pair, although in nearly
all nests there are to be found complementary and sup-
plementary royal individuals. Unlike other social
insects vvfiere there is a marked difference between the
males and females, and where the workers are of the
female sex, as is the case in bees, in Termites the males
and females are closely similar, and. the castes are in no
way correlative with sex. The following kinds of
adults are usually present in a colony, viz : —

1. Workers.

2. .Soldiers.

3. Winged individuals, known as imagos or
nymphs, ready to leave the nest.

4. King and Queen.

5. Complementary and .Supplementary Royal in-
dividuals.

These, according to their relative condition of de-
velopment, may be further divided until as many as
eleven or more distinct varieties are found in one colony.

The workers, which are usually blind, have no trace
of wings except in some instances where there are
slight stumps. As their name indicates, they are
generally the food-winners, and their duties comprise the

January, 1907.

KNOWLEDGE & SCIENTIFIC NEWS

li

building of the nests, tending- the eggs of the queen,
and providing nourishment for the young larvae. In
some species they are also effective combatants, though
they possess no special structures for this purpose.

The second class, the soldiers, which includes both
sexes, forms from one to twenty per cent, of the inhabi-
tants of a colony, and is, perhaps, the most remarkable
feature of termitid biology. As a rule a marked differ-
ence exists between those of the various species, which,
consequently, can be distinguished by their soldiers
more readily than in any other way. There are two
very distinct kinds, those having enormous flat heads
and very large mandibles, and those whose heads are of
a more natural size, but are armed with a kind of horn
between where the eyes should be. These latter,
from their appearance, may be termed a sort of unicorn
variety. .Apparently there is no species with both these
characteristics. The soldiers in nearly every instance
are totally blind and wingless. The large-headed
variety, at the approach of danger, engage in a threat-
ening display in order to frighten their enemies, making
a rhythmic noise by hammering the ground with their
heads. They also attack vigorously. The unicorn
emits a kind of viscous fluid from his horn with which
he dabs his adversary.

The winged termites or n\mphs, which can see, are
attracted by artificial light when the swarming season is
on, as is well-known to all who live in tropical countries.
In more temperate climates, such as Southern Europe,
the winged forms appear in early summer, while in
equatorial regions they emerge for the most part in
simultaneous swarms at favourable seasons, although
in some species they seem to be constantly produced in
small numbers all the year round. The object of this
swarming appears to be propagation. It has been
noted that all those going from a nest at one time are of
one sex. The wings are so constructed that they can
be shed at any moment. These winged termites are the
favourite food of many insects, such as the common
ant. Birds also and a large number of smaller animals
eat them ravenously. In some cases, notably in parts
of India and \\'est .Africa, they are used for human
food, and it is stated that they are digestible and
delicate in flavour.

.Although millions of these insects fly abroad during
the swarming season, few survive the attacks which are
made upon them by their enemies. When a couple
pair off they shed their wings and then start to make
a new colony, becoming the King and Queen, or
they may be taken possession of by an orphaned colony
and elected to the vacant throne. The position of the
Royal pair is not always an enviable one, for, although
in some instances they appear to have their entire
liberty and can come and go as they please, in others
they are prisoners for life, their cell being usually about
the centre of the termitarium or in a part of the nest
least open to attack. They are waited on by the
workers, who are most careful to attend to their wants.
The sole duty of the Queen, who is nearly always found
in a gravid condition, appears to be the laying of many
thousands of eggs in the course of a season. .As she
lays them they are taken hold of by the workers and
carried to a more or less distant part of the nest. It has
been stated by some that the difference in the various
castes and classes can Ix distinguished in the eggs, but
more recent authorities have affirmed that this is not
so, and that probably the workers and soldiers, as well
a.s some of the other varieties are kept in a state of
arrested development by differential feeding.

In the event of accident to the King or Queen, a

complementary or, failing any of this variety, a supple-
mentary Royal individual is raised to the throne. In
some cases several of the required sex may be promoted.
These neoteinic forms, while never becoming true
kings or queens, are yet able to produce eggs and so to
continue the race. The difference between the King
and Queen and their offspring is in most cases so
marked that it appears strange that the latter should
have come from the eggs of this one pair.

The termitaria in which certain varieties of these
creatures dwell are built up of carefully-digested por-
tions of earth and vegetable matter coated with a
liquid, emitted by the workers, which forms a hard
cement, so that it is possible to walk over these mounds
as though they were solid.

-All termites require a certain amount of moisture,
some more and some less, as without this they die very
quickly. Certain species bore into growuig trees,
others again make their nests upon the branches, using
the living wood as food, but the majority of those who
do not build termitaria take up their abode in decayed
pieces of wood or that which has been cut down for
some time, and which, while not exactly wet, contains
sufficient moisture for their purpose.

If white ants confined their attention to decayed or
rotten wood there would be little need to take steps
towards preventing their encroachments, but, unfor-
tunately, they also attack the woodwork of buildings,
and when once inside it is difficult and in some cases
impossible, to dislodge them.

Their method is insidious, for they make merely a
slight puncture in the outside of the wood, while they
entirely eat out the interior, leaving only a thin crust.
Joists which were apparently sound, and floors which
appeared to be quite intact, have been known to
suddenly give way, to say nothing of the breaking-up
of tables and chairs owing to the attacks of these
insects.

\'arious attempts have been made from time to time
to deal with this scourge of the tropics, with, however,
only partial success. The immunity which some woods
enjoy seems to depend largely • upon the variety of
termite to whose depredations they happen to be ex-
posed. Most kinds prefer soft piney woods, while
some others again seem to dislike them, though they
will readily attack other timljers. It has been found to
be quite useless to paint or cover wood with even a
poisonous admixture, as termites are able to even pene-
trate iron, glass, or mortar to get at the wood under-
neath. This is usually accomplished by the emission
of the viscid secretion used by the workers for cement-
ing the walls of their termitaria or subterranean pass-
ages, this secretion acting as a corrosive.

Recent researches into the methods and habits of
these insects have proved most conclusively that the
only way to prevent the destruction of timber is by
thorough impregnation with some objectionable or
poisonous substance, and this view is the more em-
phasised as the opinion held by travellers and some
residents in tropical countries that if the Queen could
be discovered and killed the workers would disperse,
has now been found to be a fallacy, owing to the pre-
sence in the colony of neoteinic forms, which, after a
short time are able to take the place of the deceased
Royal individuals.

Creosote and similar mineral oils have been tried,
but these, while successful up to a certain point, are
on account of their smell and for other reasons, among
which may be mentioned their high inflammability, use-
less for the timbers of dwelling-houses or for furniture.

12

KNOWLEDGE & SCIENTIFIC NEWS.

[January, 1907.

After a larg-c luiiiibcr of experiments, the Powell
Wood Process Syndicate, Ltd., of 28, Fleet Street,
London, K.C, claim to have at last solved the problem.
By the Powell process the wood is boiled in a
saccharine solution to which is added certain substances
obnoxious to terniiles, though the_v are otherwise per-
fectly inodorous and innocuous. ' In the subsequent
coolintj the solution is absorbed by the tissues of the
wood, with the result th;it the "wood is not only
strengtht-nod .ind iinpnned in c|u:ility, owing to the [jre-

sence of saccharine matter, but is also proof against
both insects and fungoid growth. Wood thus treated
has been buried in ants' nests and placed in various
positions open to attack, but in every case it has en-
joyed complete immunity, while untreated pieces of the
same wood, either attached to the processed specimens
or placed around it, have been consumed.

The news of this discovery will be received with
acclamation in many parts of the world, as it will enable
local timbers to be employed for constructional and
other work, especially as the process will effectually
season the wood within a few days of its being cut
down.

The Pleiades.

This photograph, taken by Prof. Max Wolf in 1902,
show s the arrangement of stars in the Pleiades with the
curious light inner nebula?. The discovery of the
nebulous formation, which seems to extend to the whole
group, 'ranks" (according to Miss Gierke) "among
the most imjiortant achievements of celestial photo-
graphy."

Tlie photograph was taken with the 16-inch Bruce
telescope at Heidelberg, with an exposure of five hours.
It has been enlarged from the original negative 3j
times, and has not been re-touched.

Next month will be commenced a series of articles on
" Aerodynamics and the Theory of the Aeroplane," by
Major Baden-Powell, which should prove of interest at
the present time.

SCIENCE YEAR BOOK.

0.\E of the star maps in the first issue of the Science
Year Book was wrongly printed, the blue portion not
corresponding with the black. In the later edition this
has been rectified, but any purchaser having a copy
with the inaccurate chart, and who will apply to the
office, will be supplied with a fresh page to replace it.

Photography.

Pure and Applied.

By Chapman Joni;s, I'.LC, F.C.S., &c.

Ti... i»j *i ^''" 'I'l'' ^^i'cn known for about a hundred
I he Induction , , -r r , , ■

Period years that il ;i moist nuxture of chlorme

and hydrogen is exposed to light the
two gases combine to form hydrochloric acid, ex-
plosnely If ilu' liylH is very bright, such as sunshine,
or quiolly .-ind gradually if the light is more subdued.
It is just about fifty years ago that Bun.sen
and Roscoc used such a mixture of gases to discoxcr
1h)w the amount of chemical change produced in it
was affected by variations in the acting light. i?ut
when light falls upon such a mixture, the change docs
not start at once, and it may be a few seconds up to
even a few hours Ijefore the maximum rate of change
that a given light can produce is attained. Or, in other
words, the mixture of gases appears at first to be
quite insensitive, and when the action begins, it grad-
ually increases its sensitiveness. This " induction
period " has been ascribed to a resistance to combina-
tion inherent in one or both of the gases, or in some
other way to a change that must precede combination
to make it possible. It has been suggested that this
change might be either of a chemical or of a merely
physical character.

Recent investigation by Messrs. C. H. Burgess and
D. L. Chapman shows that this "induction period"
is sometimes, and probably always, due to some im-
purity that the chlorine acts upon more readily than
upon the hydrogen, or that in some other way prevents
the combination of the chlorine and hydrogen. These
investigators state that " no evidence can be obtained
of a period of photo-chemical induction with a moist
mixture of chlorine and hydrogen in the absence of
impurities. . . ." Therefore it appears that all
arguments founded on the supposed existence of this
"induction period," and the analogies that have been
drawn from it, fall to the ground. It would be possible
to found certain arguments on its non-existence as to
the nature of the developable image, but I do not think
that they would have any value, as there is no proof
that the two cases are analogous.

The Mechanical

Action of

Light.

The British Journal of Flwtograpliy
(p. 970) gives an account of a paper by
F. -Alefeld, in the Clieinikcr Zcituitg, in
which he describes how he has obtained
results that appear tO' indicate that when solutions of
certain substances are evaporated so as to form a film,
dried at 100° C. for 15 to 30 minutes, and then exposed
under a negative for about half an hour to bright sun-
shine, the substance so moves about that it accumulates
where subjected to light at the expense of those parts
that are shielded from the light. The thio-resinates are
generally used in an appropriate solvent (water solu-
tions will not work soi well), choosing one that leaves
on ignition an oxide that will colour glass. The ex-
posed film is then heated sufficiently to cause the oxide
to combine with the glass. Sharp pictures are so pro-
duced, but the whites are never pure, i.e., the substance
never completely leaves the parts shielded from light.
A second exposure under another negative does not
obliterate the effect of the first exposure, perhaps

January, 1907.]

KNOWLEDGE & SCIENTIFIC NEWS.

13

Talbot's Law.

because the film has become more dry or set, or the
light may cause a chemical change in the material and so
tend to retard the further migration of the compound.
To confirm the results, a compound of silver was used,
applying it to gelatine films which were then shielded in
alternate strips and exposed. The silver was estimated
in the exposed and unexposed strips, and the former
contained sometimes twice as much as the latter.

The moving about of a substance that is free to move
is very familiar in crystallisation; the spaces between
the crystals being ne;irly, if not quite, free from the sub-
stance, while at first it was evenly distributed through
the solution or space it occupied. It has often been
observed that light appears to facilitate or encourage
the deposition of a solid, though it has been stated,
without, perhaps, sufficient evidence, that the effect is
due to the shaded part being of slightly higher tempera-
ture than the other. The experiments referred to above
appear to support the idea that light itself is really
effective.

The rotating disc with differently coloured
sectors is so often used in colour photo-
metry for photographic purposes, that the accuracy of
this method of work is a matter of prime importance.
So far as visual work in concerned, it depends upon
Talbot's law, which states that " if any part of the
retina be excited by intermittent light recurring regu-
larly in the same way, then, if the period be sufficiently
short, a continuous impression will result, which is the
same as that which would be produced if the total
light were distributed uniformly throughout the whole
period." It is satisfactory to know, that investigations
by Mr. E. P. Hyde, which he described before the
American Physical Society last .April, show that this
law is correct for white, red, green, and blue light for
angular openings from 10° to 288°, within a possible
error of .3 per cent., though the deviations from the law
may be a little greater in the case of the coloured lights
than white light. Therefore the doubts that have from
time to time been cast upon the accuracy of this method
appear to be without foundation.

I use the word '' still " here as the
1^*'" t anthithesis of " rocked," the developing
■ solution not being moved over the sur-
face of the plate. This method of development
has recently been described and eulogised as
if it were new, but it is really quite old and the effect
of it has long been well known. It may be car-
ried out in more ways than one. The plate may be
allowed to lie at the bottom of the developer, which
is preferably made rather weaker than usual, though
not too weak, or the mixing of the various parts of the
solution by diffusion will defeat the very object of the
method; or as soon as the plate has absorbed a suitable
quantity of the developer it may be removed from the
dish so that the only developer that is available is either
in the film or on its surface. It is clear that by such
treatment the developer available on the most exposed
parts will be more quickly exhausted than that on the
less exposed parts, and that therefore the growth of
the image will slacken most where the exposure effect
has been greatest, and the result will be a flatter (or,
to use a more complimentary term, a " more har-
monious ") negative. AV'here there is a tendency to
hardness, as from under exposure, this method may be
useful, but generally it is far better to keep the de-
veloper moving so that it may have an equal energy
over the whole plate, and the extent of its action may
be governed only by the exposure effect.

ASTRONOMICAL.

By Charles P. Butler, A.R.C.Sc. (Lend.), F.R.P.S.

Photog:raphic Photometry of Coloured
Stars.

Mr. R. J. Wallace, at the Verkes Observatory, has been
making further investigations into the suitability of em-
ploying colour screens for stellar photography. In the pre-
sent paper his remarks are more particularly directed to
photography with a reflector, so that the chromatic aberra-
tion of the instrument itself may be neglected. It is well
known that with almost all kinds of photographic plates
there are certain portions of the spectrum to which the plates
are less sensitive than others. So long as the star groups
being photographed are all of the same type of spectrum,
then any kind of plate will give a true rendering of their
relative brightnesses. In reality, we know that in any star
field there are many types of stars, and to obtain a true
photographic record of their magnitude we must adapt a
colour screen in front of the photographic plate which will
reduce the intensity of that kind of transmitted light to
which the plate is specially sensitive, so that it may record
the true colour values of the object. The dyes Tartrazine,
.\uramine O, Metanil Yellow S, and Xitrosodimethylanilin
were found to be most suitable, and the requisite amounts
were incorporated in gelatine solutions and flowed on pre-
pared glass plates. In the case of compound filters, it was
found preferable to coat several plates with only one colour
each, and then to bind the plates together. The perform-
ance of the filter is accurately examined by means of a
delicate spectrophotometer, and alterations made until it is
exactly adapted to the photographic plate to be employed.
Reproductions are shown of photographs of the region sur-
rounding the coloured star U Cygni (which is classified by
Chandler in his colour scale as 9.3, where 0= white), first on
ordinary Seed 27 plates, and then on Cramer isochromatic
provided with the proper colour filter. The difference is
very great, and emphasises the danger of determining any
star magnitudes from photographic records unless there has
been such control over the colour selection of the plate. —
(Astrophysical Journal 24, November, igoli.)

Tnunderstorms and Sunspot Frequency.

.•\ considerable amount of discussion has been published
in the endeavour to prove the existence of direct correspond-
ence between the occurrence of large thunderstorms and
the state of the solar activity as evidenced by the epoch of
sunspot frequency. Quite recently Dr. A. S. Steen
examined the data from a large number of stations in
Norway, Sweden, and Denmark obtained during the period
1873-1903. He concludes that the epochs of maxima and
minima of thunderstorms occur at or near the epochs of
maxima or minima of sunspot frequency. In addition to
the main period of eleven years, a subsidiary period of
about 5.5 years is also indicated. — {Hanii-Band dcr Mcfcmo-
lof]ischeii Zdtschrift.)

Dealing with the same subject, Mr. .\. Mutt announced
at a meeting of the British .-Xstronomical .Vssociation that
on almost every occasion in his experience on which there
had been a thunderstorm, a new spot had broken out on
the sun on that or the next day, or that one of the already
existing spots h.ad greatly increased in magnitude. .\n in-

stance of this occurred on Mav

1906. — (Journal Brit.

Ast. Assoc. 17, November 22, uioCt.)

Echo of the Valparaiso Earthquake.

The seismograph records ol llie ^l.ltions along ilu- Pacific
Coast of the Asiatic Continent are of special interest when
they occur in connection with the convulsions along the

u

KNOWLEDGE & SCIENTIFIC NEWS.

rjANUARY, 1907.

western mountain ranges in North and South America.
From a China Weather Service Circular issued from the
Zi-Ka-Wei Observatory, near Shanj;;hai, we learn that ihe
Valparaiso earthquake was rej^islered quite distinctly. Ihe
first movements or prelimin.iry liemors of the instrument
began on the Friday morning at Xh. ii)m. 24s. a.m., China
Coast lime. .\s N'alparaiso, at the mouth of .Santiago
Chile river, is nearly at the .\ntipodes of Shanghai, the
distance in a straight line across the earth is about 1^,715
kilometres, (jiving to the vibrations an estimated velocity
of ten kilometres per second, the e.uthquake must have
begun 2ini. 12s. sooner at the place of the disaster, viz., at
"h. 58ni. 12s. a.m. on the 17th, China Coast time, or at
6h. s8m. p.m. on Thursday i6th, i.e., i,^ hours sooner, by
the time of the 7 hours zone west of (ireenwieh. There
may be some dilTerence in this estimate if the zone time is
not employed in Chile. As an indication of the severity of
the shock it may be noted that the w.ives registered at
Zi-Ka-V\'ei, almost at the other end of the earth's diameter,
exceeded 2.7 mm. in amplitude. The end of the disturbance
took jil.ice .-It iih. Kjm. a.m.

Chromospheric and Sunspot Spectra.

Observing with the l;irgc spiel niscopr and telescope ;il
Princeton, "U.S.A., \V. .M. .Milchell has been able to obt;iin
a new series of determinations of the lines characteristic of
sunspots and of the chromo-.phere. Comparing these with
his first series, it was found that the selections of widt-m-d
lines of the spot spectra during the two periods were so
similar that it was unnecessary to publish a new list. In
the cases of reversed and weakened lines, however, this
constancy does not hold, many new lines of both classes
being detected, and a list of these is given, as well as a
table of the lines seen bright in the spectrum of the sun's
limb, between the wave-lengths 4876.59 and 688^.33,
showing their origins and intensities. Considering these
facts in relation to phenomena which have been observed
in experimental laboratory research, it is pointed out that
the presence of hydrogen in the chromosphere may cause
certain lines to be suppressed to such an extent that they
become invisible against the background of the sky. This
is in agreement with the observations of Fowler, that the
high-level chromospheric lines are enhanced lines, since it is
probable that the proportion of hydrogen is greatest high up
in the chromospheric stratum. Lower down in the re-
versing layer other lines gradually make their appearance.
In these high-level gases the emission co-efficient would be
greater than that of the lines caused by gases at the lower
levels; therefore, the absorption of the lines would be less,
and, in consequence, across the dark umbra of the sunspot
such lines would have an enfeebled or weakened intensity. —
(Astrophysical Jmirnal 24, pp. 78-94, September, 1906.)

Brilliancy of Mira Ceti.

The well-known variable star 0 Ceti, or Mira, as
it is usually called, is now a very prominent object in the
scuth-eastern sky at sunset. Attention has been drawn to its
appearance this maximum in that it has attained to con-
siderably greater brightness than is usual. It is to be
hoped that all w-ho have spectroscopic means of observation
will obtain records as often as possible. The spectrum of
the star is very interesting, and to some extent peculiar; it
resembles a Orionis (Betelgeuse) with respect to the dark
lines and bands or flutings, but, in addition, there are
bright hydrogen lines, which appear to fade out as the star
becomes fainter. There is no direct resemblance to the
spectra of new stars, so that in this case the eclipse theory
is supposed to be a likely explanation of the phenomenon,
but the chief difflculty in the way of accepting this is that
the lines, both bright and dark, do not show any ap-
preciable evidence of motion.

Peculiar Phenomena of Sunspot
Penumbrae.

M. S. Chevalier, writing from the Zo-.Sai Observatory in
China, calls attention to a peculiar appearance sometimes
noticed on the inner edge of the penumbras of sunspots.
This takes the form of a ring of increased brightness im-
mediately surrounding the umbra. It is evident that the
phenomenon is not characteristic of all spots, as it has often
not been seen when specially looked for. In the paper the
author gives a series of photographs of spots showing the

bright ring at various stages. In the case of a spot show-
ing this feature it does not appear to vary as the spot
crosses the disc, but observations show th.it the first ap-
pearance of it comes out on the north and south of the
nucleus, while the spot is entering on the visible hemisphere,
then on the east, and finally on the west side. When the
spot is approaching the w<'st limb the tlisappe.-ir.irue begins
with the east side, then the west, :md fin.'dlv the north and
south. It is probable th.it sunspots h.'iving a regul.ir out-
line present the phinomenon with the more marked
biilliaiuy. ( .l.s7i()/'/i i/.s/ni/ ./(.i/c/ii// 24, Ncivcmlicr, igo6.)

Calorific Emission of the Sun.

MM. Fery .-md Milloch.iu, coiUiiuiing tlu'ir observations
with the eyepiece thermopile, give further v.-ilues of the
prob.ible absolute temperature of Ihe sol.ar disc. These are
5,888" and 5,963", with a possible error of ± 15". Experiments
were also undertaken to determine the variation of emission
of .several substances at high temperatures, including nickel
oxide, magnesia, and platinum. — (Comptes liendus 143,
November 12, 1906.)

BOTANICAL.

By G. MASsicii.

Origrin of Elementary Species.

I'koi-kssor Hugo de ViJiiis, whose name is well known in
connection with what has been termed " nuitation," or the
sudden appearance of elementary species in the vegetable
kingdom, has recently (rreic. Amer. Vhil. Hoc.) expressed his
views in general terms. Darwin's principal conception as
to the origin of species was that their gradual evolution de-
pended on the same laws as those that underlie the evolu-
tion of races and varieties under culture. This implied time,
coupled with much uncertainty, and did not afford the
necessary evidence for founding a satisfactory theory. Until
quite recently the method adopted for producing new strains
was by the slow process of gradual elimination, until the
desired strain was obtained in a pure and permanent form.
De \'ries, on the other hand, maintains that species are not
changed into one another, but are permanent, giving ofT
from time to time, sideways as it were, aberrant individuals.
Such individuals constitute his mutants or new species, and
experiments have proved that, in the main, their characters
are constant and hereditary from their first appearance. This
is, briefly, De Vries' unit-characters idea, which is the basis
of his theory of the origin of species by mutation, which, in
turn, leads to the acceptation of saltatory changes, com-
monly known as sports, as the most probable way em-
ployed by Nature to produce new forms. Most of our
ordinary agricultural crops are composed of elementary
species, and, again, each cultural variety contains numerous
sharply-defined types. These types are distinct in botanical
characters, and in those properties which decided for or
against their utility. By careful searching, the proper type
for each special requirement may be perpetuated. The
modern method of perpetuating a desirable strain, say, of
a cereal, is as follows : — In each thousand plants there are
a few phenomenal yielders, and the method of single-seed
planting makes it possible to secure these plants, from
which new varieties can be made. If these selected plants
had been only extreme varietal fluctuations, they would
have shown variability and retrogression to mediocrity. As
this did not prove to be the case in the experiment quoted,
De Vries considers that these phenomenal yielders were, in
reality, elementary species, which had remained hidden until
rescued by the process of single-seed planting, or, in other
words, commencing from the seed of a single individual.

The older, and what may be termed the rule-of-thumb,
process for obtaining an improved strain consisted in select-
ing a number of ears of exceptional size, or possessing in
some degree the qualities desired. These were mixed to-
gether and sown, and it was only by a long process of
elimination, year by year, that the desired result was ob-
tained. The explanation of this is that in all probabilitv
several elementary species were included in the first selection
of ears, hence the necessarily long period required for
eliminating all except the very best elementarv species,
which, when once obtained, remains permanent. The

January, 1907.]

KNOWLEDGE & SCIENTIFIC NEWS.

IS

method of starting from a single seed obviates the diffi-
culties stated above.

This old-fashioned elimination process of plant breeding
has been always considered as the most valuable argument
in favour of natural selection ; in fact, of late, it was its last
remaining botanical support. By means of the modern
method of starting with a single factor — single-seed plant-
ing— instead of with a quantity of seed, probably containing
several elementary and fixed species, all of which but one
had to be eliminated, it is considered that this support has
now been broken down, and that selection as applied in
agriculture is no longer an argument against the conception
of an origin of species by saltatory changes.

Vegetation of the Antarctic Sea.

.\ beginning has been made by C. Skottsberg, who ac-
companied the Swedish Antarctic Expedition of 1902, in the
Antarctic, to investigate the marine flora, in order to give
a true picture of its nature. Unfortunately, the most im-
portant collection of algje was lost with the ship. The places
visited belonging to the .\ntarctic proper were South Shet-
land Islands, coasts of Louis-Philippe Peninsula, Palmer
.\rchipelago, Ross Island, and the neighbourhood of Snow
Hill. The algal flora proved to be richer than was ex-
pected. The salinity and temperature of the sea are import-
ant factors, and exercise much influence on the development
of marine vegetation. In the .Arctic Sea the coast water of
Siberia mixes with a large amount of fresh water brought
down by the large rivers, and the poverty of the littoral
region is considered to be partly due to this fact. In the
-Antarctic Sea the conditions are different, no rivers are
known to exist, and the superfluous precipitation is dis-
charged in the form of icebergs. These are usually carried
some considerable distance to the north before they melt.
The salinity of Antarctic sea water slightly exceeds that of
the .Arctic Sea, the temperature of the two is about equal.
The temperature sinks and the salinity rises with increasing
depth. Ice also, to a great extent, determines the distribu-
tion, or even the presence of algae, which can only grow in
places where the beach is free from ice and snow during
the summer. During the winter a bank of ice and snow
reaches to high-water mark, and a continuation of this in
the form of an '' ice-foot " covers the greater portion of the
littoral region. Perennial algse live throughout the winter
in a frozen condition and deprived of light ; the calcareous
forms are especially able to endure in this condition through-
out the winter, but examples of the more delicate kinds were
also collected that had survived this treatment. In some
instances very thick ice remains unbroken for seven or eight
months in the Dundee .Strait, nevertheless, a rich vegetation
exists, proving that the Antarctic algse must possess the
power of living for months on the productions of the previ-
ous summer. Icebergs and drifting ice also prevent the
growth of algae ; in many places both littoral and sub-
littoral zones are quite polished by icefloes dashed against
the rocks by waves or tidal currents.

Owing to the loss of the greater part of the collection,
the regional distribution of the marine flora could not be
worked out, nevertheless, littoral, sub-littoral, and deep-
water zones were found to possess characteristic species.
Calcareous algse are conspicuous in the littoral zone, species
of Iriilca are also in abundance. Dcsmare.itia occurs in pro-
fusion in the sub-littoral zone, and is as characteristic of the
.\nlarctic as the Lamiitaria formation is for the .Arctic.
Florideae arc characteristic of the deep-water zone, gigantic
specimens of (rracilaria (Lcptosarca) simplex, and many other
species of smaller size. Srhizoneura qucrcifolia occurred in
plenty; this species is related to Delesseria sinnata, occurring
the Ihe .\rctic .Sea.

CHEMICAL.

By C. AiNsvvoRTH Mitchell, H.A. (Oxon.), F.I.C.

The Poison ivy.

The latest addition to oui- know liilgr of the chemistry of
this curious plant is that published by Messrs. .Acree and
Syme in a recent number of the American Chemical Journal.
The poison ivy or poison oak (lihus toricodcndron) grows in
many parts of the United States and in Canada, and in the

erect form reaches the height of about 40 inches. When in
the vicinity of trees or walls, however, it becomes parasitic,
and may then grow to a height of 30 feet or more. For
long this climbing variety was regarded as a separate
species, but the identity of the poison oak and poison ivy
has now been proved beyond question. Both produce small
green flowers and small white fruit, and contain a milky
juice which turns black on exposure to the air. The leaves
are employed commercially in the manufacture of a black
varnish stain for boots, being collected between May and
Julv while the plant is in bloom. Another curious property
of the juice is that it raises blisters when brought in con-
tact with the skin, while even the vapours given off by the
plant, especially by night, have the same effect upon certain
peculiarly susceptible people. For this reason the juice was
at one time a favoured remedy for certain skin complaints,
and is still used to some extent for the purpose in the
United States. The poison ivy was introduced into England
in 1640, but it was not until 1798 that it was tried as a
medicine in Europe, a doctor at Valenciennes being the first

The Poison Ivy iRhtis toxuoJir.dron).

to prescribe it to his patients. But long before then the
juice of the plant had been recommended as a marking ink.
Thus the .\bbe Mazeas, in a letter published in the 2'rn/i.s-
(ictions of the Boyal Society for 175S, describes his experi-
ments on this point, and states that characters written with
the juice upon his linen had remained quite black after
constant washing for live years. Incidentally it is men-
tioned that the plant was then growing in the gardens of
the Bishop of London's Palace at Fulham, but inquiries
made by the present writer show that it has long since
disappeared. Other writers have borne witness to the per-
manency of the stains produced by the juice upon linen.
The writing is quite proof against soap and water, dilute
acids, alkalies and bleaching powder, though it is easily
removed by ether. The juice is therefore still emploved in
the manufacture of marking inks in .\merica. Herbivorous
animals can e.it the poison ivy without ill effects*, but upon
dogs it acts as an irritant poison, producing convulsions
and death. There are also several cases on record of chil-
dren being poisoned through eating the berries. One of

•Maiscli and Stille, NalioMal Diif>enialory.

i6

KNOWLEDGE & SCIENTIFIC NEWS.

[January, 1907.

the earliest investigations iiiti> thr chemistry of the plant
was that made in 1858, by K. l.iUcl, who found that it con-
tained a tannin, giving a green coloration with iron salts.
Me attributed the poisonous action of the juice to the
presence of an alkaloid. Soon afterwards, Porcher dis-
covered that the exhalations given olT at night by the leaves
contained hydorcarbons, whicli would burn when ignited.
Then, in 1805, Dr. iMaisch found that the eni.mations had
an acid reaction, and that tht' leaves contained ammonia
but no alkaloid, lie isolated a volatile substance, which
combined with alkalies to form salts, and to this substance,
which he termed tuxicoilciidiif aciil, he attributed the
poisonous action of both the juice and the exhalations, for
whether in solution or in the form of vapour it produced
the same elTects upon the skin. This was confirmed in
1883 bv Mr. Pettigrew, who found that the acid resembled
formic acid in many of its properties. Messrs. Acree and
.Svme have now separated from the juice a poisonous wax-
like substance, which does not volatilize when heated with
alcohol vapour. They have also proved that all cases of
poisoning can be cined by the use of a solution of potassium
permanganate.

Spontaneous Igrnition of Carbon Bi-
sulphide.

Carbon bisulphide, a mobile, highly refractive liquid,
prepared bv passing sulphur vapour over hot carbon, is ex-
trenu'lv valuable as a solvent for fats, for killing weevils
in grain, and for many other purposes, but serious draw-
backs attend its use. The ordinary commercial product has
a particularly ofTensive smell, whicli is commonly attributed
to the presence of traces of impurities. Then the vapour
is very poisonous, and workmen who handle the liquid in
badlv ventilated factories are liable to suffer from de-
pression, coma, and loss of memory. The greatest risk,
however, is due to its being highly inflammable, igniting
at quite a low temperature, and burning with a blue flame
to form carbon dioxide and sulphur dioxide. So great is
the innammability of carbon bisulphide, that numerous in-
stances have been recorded where it has taken fire spon-
taneously. In a recent case described by M. Pape, the
chemical became ignited when being poured through a
metal funnel into a glass carboy, in the open air, and far
away from any source of flame. The day was very hot and
dry, and the immediate cause appears to have been an
electric discharge caused by the friction of the liquid falling
upon the iron funnel, which was isolated by the glass of
the carboy. Other cases of spontaneous ignition have taken
place while the bisulphide was being poured into iron drums.
An electric discharge has also been looked upon as the chief
cause of these accidents, though it has been suggested that
the heat produced by oxidation of iron sulphide may have
had a share in the process. The remedy proposed is to
expel the air from the drums by means of an inert gas, such
as carbon dioxide, before introducing the carbon bisulphide.

GEOLOGICAL.

By Edward A. Martin, F.G.S.

Phosphorescence in Calcite.

In the American Journal of Science, Mr. W. P. Headden
has been discussing the phosphorescence of certain calcites
from Fort Collins, Colo., and Joplin, Mo. They possess
the property of becoming phosphorescent on being insolated,
and retain this property, in some cases, for a period of
thirteen hours. Ordinary calcite under like conditions
phosphoresces for one-third of a second, and aragonite for
twenty seconds. Many other minerals become phos-
phorescent on being insolated, but the duration of this
phosphorescence is very brief.

The Missouri specimens, which show a stronger phos-
phorescence than those from Colorado, occur in two forms,
both in well-defined crystals. One is the well-known dogl
tooth spar, only slightly modified by a rhombohedron ; the
other is a combination of two scalenohedrons.

The length of the period of phosphorescence was as much
as thirteen hours, which was established by continuous ob-
servation. The duration, no doubt, actually exceeded this

lime, hut it w.is distinctly visible, in some specimens, for the
time given.

Mr. lleadden concludes by rem.arking th.il "the limit of
mv ])resent progress is the establishment of a probability
that these calcites owe their properly of becoming phos-
phorescent on insolation to the presence of some member of
the yttriimi group, which is represented liy 1 ^ |)arts in e.ach
100,000 parts of the calcite."

A Deep Borinfr at Lincoln.

.\ conmiimicalion was re, id ,it the meeting of the deulogi-
cal Society on December i,(, by Prof. iviKvard Hull, on
" The (ieological Conditions which h.ave contributed to the
Success of the Artesian Boring for Water at Lincoln."

The boring has its source of supply in strata which rise
to the west, but to the east dip down towards the North Sea.
There exists no information as to whether the eastern border
of the water-bearing formation thins out against a con-
cealed ridge of Pahco/oic rocks. The water-yielding
stratum is reddish soft, porous sand-rock, reached at a
depth of 1,561 feet and penetrated to a depth of 474 feet.
,'\bout one million gallons of water rise to the surface daily.
The sand-rock belongs to the New Red .Sandstone, which
crops out from York to Nottingham with a breadth of about
eight miles. The hydraulic pressure at the bottom of the
boring is that due to about 2,035 feet, and the friction of
the water in percolating the rock accounts for the fact that
the writer can be [)uniped down during the day but rises
again in the night. The formations penetrated are the
following : — Alluvium and Lower Lias 641 feet, Rha^tic Beds
52 feet. Red Marl and I^ower Keuper .Sandstone 868 feet,
Bunter Sandstone 454 feet. The quantity of water drawn
from the New Red .Sandstone, at and below the outcrop
defined, amounts to not less than 20 million gallons daily,
and the total available quantity of water percolating into the
.Sandstone amounts to about 300 millions.

Raised Beaches on the Chilian Coast.

Mr. O. IL Evans' paper on " Tlie Raised Beaches of
Taltal (Northern Chile) " proved extremely interesting. The
town of Taltal is situated partly on the dry bed of a broad
river and partly on a gently-inclined plain that fringes the
bays of the coastal ranges far to the northward, and runs up
the valleys to a considerable altitude and distance from the
coast. The formation is impregnated with salt, and there
protrude through it curiously-weathered remnants of former
stacks and islets. The plain rises in terraces, the highest
of which are somewhat obscure, and sometimes portions of
these higher terraces are preserved in the stacks and islets.
A second coastal shelf also occurs, marked by a line of
shallow caverns. The beds of shells in the gravel, contain-
ing occasionally whale-bones, give satisfactory evidence of
the marine origin of the terraces. Some of these shells are
replaced by crystallised brine, and calcium sulphate occurs
in some sections. Profound ravines (quebradas) occur in
the massive rocks bordering the plain, although the climate
is now so dry that rain-erosion is practically non-existent.
Mr. Evans exhibited specimens in illustration of his paper,
but he had, unfortunately, lost almost the whole of his
collection, as well as his notes, in the earthquake at Val-
paraiso, whilst such as the earthquake spared had since
either been burnt or blown up by dynamite.

ORNITHOLOGICAL.

By W. P. Pycraft, A.L.S., F.Z.S., M.B.O.U., &c.

The Range of the Arctic Tern.

The recent Scottish National Antarctic Expedition was em-
phatically successful, and especially so, perhaps, with regard
to the biological work achieved by its officers. Much has
already been published on this head, and Mr. Eagle Clarke
added thereto at the meeting of the British Ornithologists'
Club held on November 21. At this gathering he exhibited
specimens of the Arctic Tern, which had been taken in the
Weddell Sea and off the Antarctic Continent, where great
numbers were observed as far south as 74°. All were
typical Arctic Terns {Sterna macrura), and thus this bird has
proved to have a greater latitudinal range than that of any

January, 1907.]

KNOWLEDGE & SCIENTIFIC NEWS.

17

other bird, since this extends from 82° N. in summer to
74" S. or more in our winter.

Hoopoe in Orkney.

The Field, November 24, contains a record of a Hoopoe
which was picked up dead near the Loch of Harray, near
Stromness. It was in fcood plumage, but much emaciated,
and had apparently been either shot or struck by a hawl-:,
since blood was found upon the breast.

Spotted Crake in Co. Dublin.

.\ Spotted Crake (Fnr-ann ^[nrueHa) was shot on Novem-
ber 24 near Balbriggan, Co. Dublin, by Mr. G .B. Tunstall-
Moore, who records the fact in the Field of December i,
igo6. This bird is of rare occurrence in Ireland, and has
been obtained most frequently- in the autumn.

Siberian Chiff-Chaff in Suliskerry.

At the last meeting of the British Ornithologists' Club
(November 21) Mr. W. Eagle Clarke exhibited a Siberian
Chiff-Chaff (Phylloscopus tristis), which had been obtained in
Suliskerry, some 33 miles west of Orkney, on September 26,
1902.

Red-rumped Swraliow at Fair Isle.

At this meeting Mr. Eagle Clarke also exhibited a Red-
rumped Swallow (Hiriinda rufula) procured at Fair Isle on
June 2, 1906. During his stay at Fair Isle, where he was
engaged in studying migration, .Mr. Eagle Clarke obtained
many other rare birds, including fine specimens of Acanthis
hornemanni, 2Iuscicapa parca, PhyUiscopus superciliosus,
Ci/anecula suecica, Carpndacus erythrinus, Enuberiza pusilla,
E. horfulana, and Aerocephahts strcpcrus — a really remark-
able list, showing how much is yet to be done by careful
study of our migratory birds.

Harcourt's Petrel at Hythe.

Dr. N. F. Ticehurst at this meeting exhibited a female of
Harcourt's Stormy Petrel (Oceanodroma castro), which had
been shot near Hythe, Kent, on November 8, 1906. This
makes the second occurrence of this species in Great
Britain, the first having been killed near Littledale on
December 5, 1895.

Greyheaded Wag-tail Breeding at Lydd.

.V pair of tireyheaded wagtails {Motacilla borcalis), with
their nests, were taken by Mr. Bristow, of St. Leonards-
on-Sea, from a marsh between Rye and Lydd on June 20,
1906. These were exhibited at the November meeting of
the Club, and this is probably the first recorded instance of
the breeding of this bird in Great Britain, \^'e regret that
the birds were slaughtered, and are not overjoyed at re-
cording the taking of the eggs.

PHYSICAL.

By Alfred W. Porter, B.Sc.

The Writings of J. Willard Gibbs.

The publication of the collected papers of the late J. W.
Gibbs is drawing renewed attention to his important
theoretical work on the borderland of chemistry and
physics. .Most of these are now available to the En"-Iish
reader for the first time. His paper on the Equilibrium of
Heterogeneous Substances, first published in the Trans-
actions of the Connecticut Acadcmv in i«;8, has indeed
been transited into German bv Professor Ostwald 'and into
French by Professor Le Chatejier ; but not until now has it
been made generally accessible. This reticence is as re-
niarkablc as the paper itself is of importance in the study of
physical chemistry.

. ^,"^.?,[ "^^ earliest of his papers is on Graphical Methods
in the Ihermoclynamics of Fluids. Evervone is familiar with
the indicator-diagram of a steam-engine, the ordinates of
which represent the pressures of the steam at successive
instants, while the abscissa; represent the corresponding
volumes I he area enclosed by the diagram represents
the work done while the piston goes through a complete

cycle of positions. This is the only diagram which had
been in use up to his day. Gibbs discusses all the various
diagrams which might possibly be useful. One of these is
the diagram in which the entropy of the steam is plotted
against temperature. This diagram, which was independ-
ently suggested in Britain by J. MacFarlane Gray, is now
in general use in connection with engines. It is probably
not possible in this note to convej- to anyone unfamiliar
with entropy what is denoted by that term ; but the follow-
ing remarks may indicate how the usefulness of the notion of
entropy arises.

If we reckon the heat that flows into or out of the steam
during one complete cycle of changes (considering it as
positive or as negative, according as it enters or leaves the
steam respectively), the total amount is not usually zero, as
is evident from the law of the conser\-ation of energy. For,
as a rule, energy at the same time passes out of the steam
in the form of external work, and it is the total energy of all
kinds which comes back to its initial amount when the
steam is brought back to its original state. It is meaning-
less, therefore, to talk of the heat in a body. Heat passes
in, it is true, but a fraction of it is at once transformed into
work. If we spoke of the " heat in a body " as the algebraic
sum of the amounts that had flowed in or out, its value for
a pound of steam, for example at looo C, would depend
upon how many times it had been made to pass in any
inter\-al through a cyclic series of changes. But it was
shown by Clausius that if you divide each small amount of
heat which enters by the absolute temperature at which it
enters, the sum of these quantities is zero for any complete
cycle of changes in the steam (or other substance), provided
the changes are such that they could be made to take place
in a reverse way without making more than a minute
change in surrounding bodies. The meaning of the last
clause depends on the fact that heat will only flow from hot
bodies to cold ; hence, if the surroundings from which heat
has been drawn while the changes are taking place in the
direct way are at a much higher temperature than the
steam, it would be necessary- to make a considerable change
in their temperature before the steam could be made to give
up the heat to them again ; such a case is said to be an
irreversible one, and is to be excluded from the above state-
ment. The quantity thus obtained, which depends onlv
upon the state of the substances, is what is known as the
eniropy of the substance. If its value for each state be
plotted against the temperature, areas on the diagram so
obtained represent heat, and such a diagram is "now in
frequent use, especially in connection with turbines.

Gibbs shows that diagrams can be obtained in which all
the standard lines for a perfect qas are straight. Thus, if
log P be plotted against log V the following lines are all
straight :— Lines of (i.) constant pressure ; (ii.) constant
volume; (iii.) constant temperature; (iv.) constant energ>- ;
and (v.) constant entropy. The first arc vertical, the second
horizontal, the third slope downwards from left to right at
450, and so do the fourth; the fifth slope downwards from
left to right at an angle whose tangent is 7 where 7 is the
ratio of the specific heats of a perfect gas.

Optical Properties of Carbon Films.

Pure carbon, which has often been regarded as " a per-
fectly black body," that is to .say, a perfect absorber of all
kinds of rays incident upon it, is, in reality, transparent in
sufficiently thin films. The transparency decreases, on the
whole, in the infra-red as the wave-length of the incident
radiation diminishes ; but it does not do so in a perfectiv
regular manner. R. W. Wood, experimenting on carbon
prisms, measured the refractive index for various lights,
and found that red rays are more retarded than the blue; in
other words, the prisms showed anomalous dispersion.
Greater retardation, it must be borne in mind, implies a
greater refractive index, and the law for normal dispersion
is that the greater index corresponds to the shorter wave-
length. This anomaly is what would result if there were a
strong absorption band in the yellow. In the case of lamp-
black a maximum of absorption was actually found by
Nichols at wave-length 520 ntJ., and in the case' of asphalle
a similar band is found, but somewhat nearer the red end.
A series of observations has recently been made bv H. .\.
Clark (Physical Pevicw, November", 1906), in which the

i8

KNOWLEDGE cS: SCIENTIFIC NEWS.

[January, 1907.

icni'diiifT, refractiiiff, and ahsorI)in(j proportics Iiavc all bccTi
measured on the .sanu' spccinion. The valuo of these pro-
perties are all theoretically connected with one another.
Films suitable for the purposes are obtained by usint;^ a
carbon cathode in a vacuum and placiuj;' slips of k'''"'^ >"
the path of the cathode discharije ; a lllm is gradually de-
posited on the j^lass. ICxperiments have also been made
upon the lilms deposited in incandescent lamps. The chief
conclusions come to are that lh<' properties of carbon fdnis
vary with the method of formin).j the deposit ; there is an
anomalous refractive index in the red (\ = 610 fitt); the re-
llection curves confirm this. .Scarcely any difference has
been detected, however, in the transmission curves of either
kind of film. 'I'he transmission of calhodic films decreases
.ilmost uniformly from extreme red to X -^ 226.6 /</< (i.e., in
the ultr.i-violel), beyond which the films are opaque.

ZOOLOGICAL.

I.Vni'KKICR.

Some Ncvtf Mammals.

.■\ CONSIDKRABLF. amount of interesting matter relating to
mammals has been published since my last communication.
Specially noteworthy is a paper by Mr. .\I. W. I.yon, published
in the I'roccediiirjs of the I'.S. National .Museum on a new
species of great anteater (.l/i/rHiiro/iAor/n nnfrnlis) from Cen-
tral .America, which differs from the typical M. jubata (or
tri(lacfylit) of Brazil in several important features of the
skull. That the last-named animal should range (as it has
hitherto been supposed to do) without marked local differ-
ences from tiuatemala to Brazil was in the highest degree
improbable. In another issue of the above-named serial the
same author has been enabled to demonstrate that the slow
lorises of the genus Kjicficchiia inhabiting the islands of
Borneo and Bauka differ from their more eastern relatives
in the conformation of the skull of the adult, and probablv
also in the number of front teeth.

.\ third paper on mammals to which reference may be
made is one by Dr. P. Matschie, of Berlin, on the forest-hog
of the Ituri Forest, published by the authorities of the Congo
Museum at Tervueren, near Brussels. The author is of
opinion that the Ituri animal is specificallv distinct from
the one inhabiting Mount Kenya and the Nandi district
[ Hiiliirkcrnix mrinertzhai]cni}, and he accordingly proposes
that it should be known as H. ifwrienais. It may be added
that an illustrated description of the former animal, by
Baron Maurice de Rothschild and Mr. H. Neuvllle, recently
appeared in the Paris Bulletin de la Socictc Philomatique.

Cavern Exploration.

In a paper recently contributed to the Irish Naturalist,
Mr. R. J. Ussher, the well-known authority on the birds of
Ireland, gives a preliminary account of the exploration of
certain caves near Donnerail, in County Cork. The most
interesting result of the investigation is' the addition of the
cavern race of the spotted hyaena of .Africa to the extinct
Irish fauna. The occurrence of a number of remains of
immature mammoths is also a matter of interest. On the
opposite side of the Atlantic the exploration of caverns in
California has been conducted with great energy, and with
results which may prove of great interest to the early
history of man in America. .An account of the exploration
of one of these storehouses — The Samwel Cave — is given by
.Mr. E. L. Furlong in the .September number of the Amcri-
rn-i Journal of .'Science. After a list of the mammalian
fauna, reference is made to certain objects discovered in
this and other caves which may be of human workmanship,
some of these objects being apparently contemporaneous
with the cave fauna. Apart from certain stone flukes, of
which the age is uncertain, the most important of these
objects are polished splinters and spikes of bones, occa-
sionally showing a perforation. These have been described
in \'ol. VIII. of the American Anfhrnpiiloijisf by Prof. F. W.
Putnam, who is strongly of opinion that they are the work
of man.

Hovtf the Whelk Bores Oyster Shells.

.More than halt a century ago the late Prof. T. II. Huxley
(in a paper publis'ied in the I'liil. Trans, for 1K53) announced,
.IS the result of his own dissections and observ.'ilions, that
Ihe whelk and other boring gastropeds perforated the shells
i>f molluscs by a kind of chain-saw action of their lingual
ribbon, or " radula," the s.ime action being continued
during Ihe process of licking out the soft contents of the
viclim in the case of univalve species. Subsequently this
ii|)inion was disputed by other observers, with the result
ih.il two divergent views have obl.iined with regard to Ihe
manner in which the boring is effected. On Ihe one view it
is assumed lh.it the radula is stationary in relation to its
supporting cartilage, and, consequently, that the rasping
.iclion is brought about by movements of the latter. Ac-
coriling to Ihe second view (that of Huxley) the radula
moves independently of its support, playing backwards and
forw.-irds over Ihe latler like a band over a pulley, so that
Ihe rasping action is due to the motion of the radula itself.
The question, it may be hoped, has been finally set at rest
by the careful investigations of Mr. J. C. Ilerrick on a
Large .American whelk (.S'l/'c'i//'!/.'! canaliculafus), the results
(if which are published in lh<' American Nafuralisf for
October last. These, in the main, confirm Huxley's con-
clusions, with the reservation that the rasping action of the
" cli,iin-saw " takes place only during the return pull.

The Attis Spider's Eyes.

We have received cuttings from the Hastirn Daili/ Mail
of October T,n and subsequent dates containing .an article by
Mr. \V. Strickland, of .Singapore, on the wonderful pheno-
menon exhibited by the eves of a spider of the Attis group.
.Ml the mendjers of the group have, in addition to numerous
smaller ones, a pair of large eyes which the author compares
to gig-lamps ; but in the particular species referred to these
eyes are of exceptionally large size. The one specimen which
the author has hitherto been able to obtain was captured at
Buitenzorg, Java. When captured, the " gig-lamp " eyes
were dark brown, like the body, but while Mr. .Strickland
was watching his prize, they suddenly changed to bright
grass-green. " In a few minutes the creature with the
same deliberation changed its eyes from grass-green to dark
brown, and repeated the operation, which was completely
under the control of its will, several times in succession. It
almost seemed as though it took a pride in showing off its
strange power ; at any rate it evidently enjoyed the proceed-
ing. It was as though a veil now of green now of dark
brown diffused itself from above downwards behind the
cornea." It is added that the colour of either one or both
eyes could thus be changed. I'nfortunatelv the creature
arrived at the museum in a dying condition, and the offer
of reward has failed to bring in other examples ; but the
same phenomenon was found to be exhibited bv a smaller
and commoner species. The phenomenon, according to
the author, is unknown not only among other spiders, but
in animals generally.

Papers Read.

.At the opening meeting of the Zoological Society for the
session 1906-7, held on November 13, a communication was
read from Prof. R. Burckhardt on an embryo of the okapi,
and a second by Mr. F. F. Laidlaw on a new turbellarian
worm from Tanganyika. Mammals from Western Austra-
lia formed the subject of a paper by Mr. O. Thomas ; while
that gentleman and Mr. H. Schwann contributed a joint
communication on Transvaal mammals. The last of a
series of papers by Messrs. Melvill and Standen on the
molluscs of the Persian Gulf and the Arabian Sea was
likewise communicated to the meeting. At the meeting of
November 27, Mr. P. A. Coward discussed certain habits of
the lesser horseshoe bat; Messrs. E. A. Smith and H. II.
Bloomer communicated observations on East .African
molluscs ; while Mr. W. Woodland offered suggestions with
regard to the origin of the renal portal system of blood-
vessels, and likewise described the anatomy of Centroplwrus
calceus. The skull and skeleton of an extinct crocodile,
froniopholi.i crassirlens, from the Wealden strata of the Isle
of \\'ight, formed the subject of a paper read by Mr. R. W.
Hooley at the meeting of the Geological .Society on Novem-
ber 21,

January, 1907.]

KNOWLEDGE & SCIENTIFIC NEWS.

19

CORRESPONDENCE.

Brakes.

To the Editors of " Knowledge & Scientific News."

Sirs,— In an article on brakes in the November number
of " Knowledge & Scientific News " I notice the sentence,
" This argument may serve as an illustration of the danger
attending arguments based on the doctrine of energy."

It seems to me that this stricture on the value of methods
based on the doctrine of energy is wholly unwarranted.
The fallacv lay in the illogical assumption that two quanti-
ties are necessarily greater than one.

Further, the action of a brake does not necessarily produce
sliding motion.

In the following analysis I use P lo represent the brake
couple produced bv friction at the brake itself and at the
axle, and O to represent the moment around the axis of
the frictional force called into play at the rail.

Then if P is greater than the maximum value of O, the
wheels will lock, and the retarding force of the rails is a
maximum.

If P is less than this value, the wheels will continue to
revolve and onlv such a force will be called into play at the
rails as to make O equal to P.

Hence we see that the greatest retarding force is called
into plav when the wheels are locked.

Further, since these couples P and Q are very large, and
the vis rira of the wheels small, we see that the motion is
(except for minute intervals of time) either pure rolling or
pure sliding, the sliding being the more effective.

If the lock is only just effective, and a rough portion of
the rail be reached, then the sliding might be converted into
rolling, which would continue until the roughness was
passed. Sliding would again intervene, but on a different
portion of the rim.

These interchanges of pure rolling and pure sliding might
be very frequent, and so prevent the formation of a " flat."

In this way only, then, can " mixed " rolling and sliding
be more effective than a complete " lock."

Yours trulv,

H. S. H.

[The wrong (but now discarded) conclusion, based on an energy
argument, is one which several of my friends came to as well as
myself ; that is the only reason I think such an argument to be
attended with danger. I am glad that " H. S. H." agrees with me
as to the source of error. I am equally glad that he has not
attempted to employ an argument from energy in the rest of his
letter. I am also in geneial agreement with him (though he does not
seem to think this) as to the suggested mode in which mixed
rolling and sliding occurs. Into the details of this I did not enter
in my note, which was probablv too short except to set others
thinking.] '_ A.W.P.

Basaltic Columns.

To the Editors of " Knowledge & Scientific News."
.Sirs, — Mr. Martin, in his interesting paper on the Giant's
Causeway, does not allude to a possible concrcfinnary origin
of the blocks. In a " Grotto " I once saw in Germany, but
cannot recall the place, the basaltic pillars were composed of
balls in vertical rows. The blocks had weathered into that
form. Mr. Martin alludes to the " cup and ball " joints.
If, as a hypothesis only, we assume centres of contraction,
due to a concretionary process, to arise along a vertical
line, such would account for hexagonal pillars with cup
and ball joints, the blocks being resolvable into balls by
weathering.

If one taps a thin biscuit in the middle on a table, it
almost invariably breaks along three lines approximately at
120° apart; so contraction round spheres in contact would
produce the hexagon, as equal spheres touch at six points on
the same plane.

Concretionary processes are, of course, extremely common.
Thus they used to be dredged ofT Felixstowe for making
Roman cement, being derived from the London clay.
Pisolitic limestone of the Oolites and botryoidal (magnesian)
limestone of the Permians are other instances. I have found
them in a metamorphic st.-ite in Jersey, so that they mav
equally well occur in basalt.

As to the caiises, I should much like to hear what present-
dav geologists have to say about the origin of concretions.
In the pisolite there is usually a fragment of some organism
in the middle, but why the molecules of carbonate of lime
a:e attracted to it, I do not know. In basalt and meta-
morphic rocks some other centres of attraction must exist.

In the basalt two causes would have to be discovered —
(1) Whv there should be centres of aggregation producing
contraction at all ; and (2) \\'hy they should lie on one and
the same vertical line.

There is a basaltic quarn,' a few miles from Coblentz on
the east side of the Rhine. Short pillars (about 6 inches
diameter) are extracted and used as posts to carr>- a chain
bv the side of the road running by the Rhine. In these it
looks as if the "centre-; of concretion " had become a strainhi
line, so that the basalt never broke up into blocks at all.

Faithfully yours,

Leamington. George Henslow.

Lightning Flashes from Earth to Cloud.'

To the Editors of " Knowledge I'i: .S< ientifk News."

Dear Sirs,- Apropos of Dr. Lockyer's interesting article
upon Lightning, I might mention that during the summer
of 1005 a short storm passed over the south-west of London
about mid-day.

While watching this from Clapham Common I saw a
flash which, apparentlv, started from earth, travelled verti-
callv upwards for a short distance, then turned at a right
angle and went due west, finally the streak " swelled out "
into a large ball of fire and vanished.

The thunder which followed in about 10 seconds was
quite consistent with the character of flash, viz., a short
peal, slight, momentary- modulation, a long peal ending in
a loud report like that of a heavy gun.
Yours faithfully,

66, Lillieshall Road, Herbert Wilkins, L.R.C.S.I.

Clapham Common, S.W.

REVIEWS OF BOOKS.

ASTRONOMY.
An Atlas of Hindu Astronomy with Key and Notes, by

Kalinath Mukherji, B..\., B.L. ; price 3 rupees; Popular
Hindu Astronomy, Part I., by the same author (Calcutta :
Han Press). — The author, a former undergraduate of
the Krishnagar College, was inspired among others to take
an interest in astronomy by Sir \V. J. Herschel, of the
Indian Judicature. The atlas supplies the native student
with maps modelled on those with which English readers
are familiar, but with the more or less conventional con-
stellation figures replaced either by the equivalent from
Indian mythology, or by difl^erent arrangements which ap-
pear to be commonly accepted in India. Some of the
changes are interesting, thus, the well-known square in
Pegasus becomes a sort of bedstead with turned legs, Orion
a deer transfixed with an arrow (the Belt), and Argo an
ineffective-looking paddle-steamer. There arc also dia-
grams of the planetary system, comets, and eclipses. The
letterpress being in Oriental character does not appeal to
English readers, only the names of constellations and bright
stars being translated. The other work, however, can be
used in conjunction with the maps, being to a great extent
in English, though bristling with quotations from Indian
epics. There are m.any interesting legends connecting the
stars with Indian mythology, but very little astronomv as
generally understood. As is only to be expected, there are
numerous typographical errors, more than a hundred of
which are given as errata at the beginning of the little
book, but the list is still incomplete. The Slilkv \Yav is
likened to a piece of white cloth, worn through in places,
twelve feet hroail. The author accepts the translation of
\'edic scholars, but not their interpretation, which he con-
siders is refuted by looking at the sky. We are not suflfi-
ciently familiar with Vedic literature to take sides on this
question. He also makes considerable use, for purposes of
parallelism, of the constellation studies of Mr. Robert Brown,
jun., to whom, as also to Professor Henry Stephen, he
owns his indebtedness as to the interpretations, other than
Indian, of the star names and figures. He uses numbers

20

KNOWLEDGE & SCIENTIFIC NEWS.

[January, 1907.

instcnd of GrccU letters for his constellation stars, and has
at times revised the order when he considers Bayer's system
not consistent, so that ideiilirnation is not always easy.

CiEOLOOY.

The History of Devonshire Scenery, by Arlluir \V. Clay-
den, M.A.; pp. 195 ami Index; 4;, photopjraphic illustra-
tions (Exeter : James G. Commin ; London : Chntto and W'in-
dus ; price los. 6d. net). — Princip.al (."layden's conlril)iilion to
the fjeolof^^y of Devonshire is one of those books which it is a
ple.-isure to read. It is complete in itself, is scientific in
everv way, and yet can be read with profit by even a br-
pinncr in the scientific study of scenery. Commencinfj with
the earliest rocks, and after a short discussion, dismissins.;
the terms " azoic " and " eozoic " in f.ivour of " pre-Cam-
brian," we are told th.-it the i^'recn and £jrey crystalline
rocks which make up the country by .Salcombe, and reach
from the Bolt Tail to beyond the Start, are believed by
some peolojjists to be of jire-Cambrian ajje. The Devonian
rocks are fully described, and a special chapter is fjiven on
the Culm measures. We should, of course, expect to find a
good deal about the Dartmoor ijranitcs and other volcanic
rocks, and we arc not disappointed. " The Salt Lake
Period " and " The Asjc of Reptiles "' are interesting; chap-
ters in the history of tlie evolution of the county, and then
with " The Return of the Sea," we have a chapter on the
" Chalk," and the problems as to the ancient coast lines
arc temperately and judiciously discussed. " The Bovey
Lake " calls to mind the ever-recurrinfj problem as to
whether the Bovey Tracey lijjnites and clays are Eocene or
Miocene, although now they are acceptably placed with the
Oligocenc beds of the Isle of Wight. If we want evidence
to show subsidence of the land, we have it in the fact that
the basin in which are these beds extends at least 400 feet
below the present sea level, as proved in a boring recentlv
made near Ileathficld station. The illustrations are excel-
lent in every w-ay, and by presenting actual photographs to
the reader they assist in preparing him for the appearance
which the various rocks reallv present in the field. And
W'here at all obscure, a key has been usefullv added on the
same page, showing clearlv the dividing lines to be looked
for. '^ E. A. l\r.

METEOROLOGY.

British Rainfall, 1905. (E. Stanford, London, 1906, Svo.,
359 pp. ; IDS.). — The title page of this (the forty-fifth) annual
volume has been somewhat altered, and now reads :
" British Rainfall, 1905. On the Distribution of Rain in
space and time over the British Isles during the vear 1905,
as recorded by more than 4,000 observers in Great Britain
and Ireland, and discussed with Articles upon various
branches of Rainfall work, by Hugh Robert Mill." The
late Mr. G. J. Symons, F.R.S., in i860, commenced the
collection of rainfall statistics, and published them in an
annual volume entitled " British Rainfall." This work,
which he continued up to the time of his death in 1900, is
now. ably carried on by Dr. H. R. Mill. These annual
volumes are rich storehouses of rainfall data, and they be-
come more valuable year by year. The growth of the num-
ber of observers has been as follows : —

I 86 I 472 I 89 I 2799

1871 1504 1901 3506

I 88 I 2145 1905 4096

The present volume contains in Part I. : — (i) A Report to
the Observers, without whose generous work " British
Rainfall " could not exist ; (2) Original .Articles, dealing
w-ith a remarkable publication of rainfall data in Germany,
and with the relation of evaporation to other meteorological
phenomena ; (3) Tables of the amount of evaporation at
II stations, of the duration of rainfall at 8 stations, and of
the complete daily observations of rainfall at 10 stations;
(4) .An account of the staff of observers and of changes in
the stations at work, together with a map showing those
parts of the country where new observers are most urgentlv
wanted; and (5) a long obituary list. In Part II. the con-
ditions of 1905 are exhaustively treated as to (6) Observers'
Notes on the rainfall and weather; (7) Heavy Falls of Rain,
their distribution over the country, and their relation to
atmospheric disturbances, with several maps ; (S) The dis-
tribution of rainfall in time, including the number of rain
days classified according to amount of fall, droughts, and

rain spells ; (9) The monthly and annual rainfall in relation
to the average; and (10) The (jenera! T.ible, giving the
names of all observers or responsible authorities, particulars
as to position and exposure of the r.iin gauges, the total
;innual rainf.all, and the number of r:iin d.ays. T.Mking the
year as a whole it appears that 1905, like 1904, was a dry
vear. The distribution of r.-iiiif.-dl over the British Isles
was : —

1005. Diflerencc from Average.

Engl.ind and Wales . . 28 So ins. - 5-62 ins. or - i6 percent.

Scotlruiil .. .. 4.i04 ,, -2-35 ,, ,, -5

Ireland 35'8o ,, -472 ,. .. -12 1.

The greatest r.ilnf.ill in 1905 was 176.60 ins. at Glaslyn,
Snowdon, ("arnarvonshire, :uul the least 14-57 ins. at .Shoe-
buryness, Essex.

PHOTOGRAPHY.

Collodion Emulsion, l>y Ihiiry Oscar Klein (London:
Penrose and Co., 109, I'";Mringdon Road, E.C., 1905; price
5s. net.)— This is a conip.iratively small volume of 95 pages,
and is written by a practical man for practicd workers. It
seems a pity that collodion emulsion processes should have
been almost driven out of existence by other methods. It
may be considered a debatable point as to whether it is a
case of the survival of the fittest, and, therefore, the author
does good service in presenting the subject with its modern
variations and applications in a convenient form. Of course,
the use of collodion CTiiulsions is a favourite topic with the
author, but he does not recommend them without discrimina-
tion, for he points out their disadvantages for very fine line
work. He describes the applications of emulsions to the
preparation of ferrotvpes, lantern slides, and transparencies,
photographing on wood, for photo-mechanical purposes, and
in three-colour work by various processes. The sensitising
of emulsions for colour is treated of at length. We wish
that the author had restricted himself to the practical aspects
of the subject for his few excursions into theoretical matters
are, to sav the least of them, unfortunate. If these parts
are to be retained in future editions they should be
thoroughlv revised.

SOCIOLOGY.

Sociological Papers, Vol LI. By Various Authors.
Published for the Sociological Society. (I^ondon : Mac-
miUan & Co., 1906; price, los. 6d.). — This volume com-
prises the papers read before the .Sociological Society during
1904-5, with the discussions that followed. Sociological pro-
blems are so complex and many-sided that from one point or
view or another they can scarcely fall to appeal to all thinking
people, and the volume contains much of universal interest
and importance. The editors have suggested a classification
of the predominant characteristics of the several papers ac-
cording to their methods of approaching the subject. Thus
the Historical Approach is illustrated by Mr. J. .S. Stuart-
Glennie's papers, " The Place of the Social Sciences in n
ClasMcaiion of Knouicdges," " The General Historical
LaxBS, the Anthropological Bases of a Science of Socialisa-
tion," and " 2'/ic Application of General Historical Laics to
Contcmporari/ Erents." The Ethical Approach by Professor
Hoffdlng with "On the Belation hetween Sociology and Ethics, '
and by Dr. Westermarck in " The InHiicncc of Magic on
Socicd lielations." The Psychical .Approach bv Professor
Sadler in " Tlie School in some of its lielations to Social
Organisation and to National Life." The Biological
.Approach by Mr. Francis Gallon in " Hestrictions in
Marriage," "Studies in National Eugenics," and "Euge-
nics as a Factor in Keligion." And the Geographical
.Approach in Professor Geddes's paper on " Civics: as
Applied Sociology." Mr. Gallon's paper on " Restrictions in
Marriage " is designed to meet the objections often urged
against Eugenics, that human nature would never brook
interference with the freedom of marriage. He takes as
examples the questions of monogamy, endogamy, exogamy,
the Australian system of marriages, taboo, prohibited de
grees, and celibacy to show how unquestioningly mankin I.
.•it all grades of civilisation, has submitted to marriag'^
restrictions, when these have been sanctioned or imposed by
custom, law or religion. The three papers of Mr. Gallon,
and the 30 pages of discussion to which no less than 26 well-
known workers contribute, demonstrate the author's claim
that " Eugenics is a virile creed, full of hopefulness, and
appealing to many of the noblest feelings of our nature." Dr.
Westermarck brings a wealth of illustration to prove the in-

January, 1907 ]

KNOWLEDGE & SCIENTIFIC NEWS.

21

Huence that magic has had on the notions of social rights
and duties. This is seen in the increase of the parents '
powers over their children, especially with regard to the im-
portance attached to the blessings or curses of a parent. It
is a fusion of magic and religion that has produced our con-
ceptions with regard to the duty of charity, " By niggard-
liness a person may e.xpose himself to supernatural dangers,
whereas liberality may entail supernatural reward." .Most
striking is the influence of magic in the treatment of the
stranger in early society, and his transformation from the
" hostis " to the honoured guest, .\lthough the rules of hos-
pitality are in the main based on egoistic considerations,
■ (" Be not forgetful to entertain strangers, for thereby some
have entertained angels unawares "), and although the
hospitality may be of short duration (as the S. Slavs tersely
express it, " A guest and a fish smell on the third day "), yet
the custom has been a most important factor in early society.
Professor Geddes urges the importance of concrete observa-
tion, " a first-hand experience, an impulse and message
from life and action ;" and a suggestive example of concrete
and applied sociology is given in the study of " Civics " (con-
tiimed from Volume I. "of the publications of the Society).
In the discussion that followed, .Mr. TomUins (of the Lon
don Trades CouncilJ sketched the advantages that would
accrue, '" if before any person was allowed to serve on our
different public bodies, he should be required to attend a
course of lectures such as those given by Professor Geddes
on Civics;" in the same way it would be well if all those
responsible for the disentangling of the educational problem
were to study Professor Sadler's paper on " The School in
some of its liclations to Social Organisation and to National
Life." Professor Sadler notes the three different influences
at work in English Educational policy, which, if pressed to
their logical conclusions, come in conflict. They are, briefly,
the belief in a unified school system ; the desire to develop
alert individualism and initiative ; and the belief in state-
encouraged groups of like-thinking people. He concludes :
" An educational system to be effective must be in harmony
with national sentiment, and English national sentiment
has for centuries shown a strong preference for allowing
great freedom in the utterance of personal conviction (and,
therefore, for permitting great freedom in imparting such
convictions through education), combined with an equally
strong preference for a sufficient measure of social order,
in order that the business of the nation may be effectively
carried on."

ZOOLOGY.
The Life of Animals: The Mammals, by E. Ingersoll ; pp.
vii. and 555, illustrated (New York : The Macmillan Co. ;
and London : Macmillan and Co., Ltd., 1906; price 8s. 6d.
net). — For those who do not care to be troubled with the
scientific names of the species and genera, this is, perhaps,
one of the best popular books on mammals that has ever
come under our notice ; the subject being treated in an at-
tractive and yet generally accurate style, with just enough
of description to enable the different species to be easily
recognised, even without the aid of the numerous illustra-
tions. As regards the latter, the author has been in the
main well served by his artists ; many of the attractive
coloured plates and of the photographs being excellent both
as works of art and as life-like portraits of the animals they
represent. While many of the illustrations are new, others
w'ill be recognised as old friends. In such a mixed series
all cannot be expected to be on the same platform of ex-
cellence ; and in one instance a cut does duty for an animal
for which it is obviously not intended, while a second omits
one of the most striking features of the species it is in-
tended to represent. In the text, amid the general excel-
lence of treatment, we may likewise recognise a few-
passages which might well be amended; as, for example, the
statement that the red .\merican lyn.x differs so slightly
from its Canadian cousin as not to be w'orthy of specific
distinction. In the main the work is thoroughly up-to-
date, including, for example, a summary of recent dis-
coveries relating to the ancestry of the elephant ; and the
accounts quoted ;ne mostly those of experts, either as field
or closet natunilists. The book may confidently be recom-
mended to all lovers of natural history — young or old. It
may be added that the scientific names of many species are
given in the index.

MISCELLANEOUS.

The Norwegian North Polar Expedition. Scientific Re-
sults. Edited by F. Nansen ; Xo\. V. (London : Longman's
Green, and Co. ; price 20s. net). — The contents of this
volume, which is as well illustrated and as handsomely got
up as its predecessors, includes three articles, forming Nos.
XIV. -XVI. of the entire series. We can but regret that limi-
tations of .space prevent our giving a notice of the first and
second (which are of the most general interest) adequate to
their importance; both being e.xcellent pieces of work,
which afford evidence of the many-sided nature of the re-
searches undertaken bv the savants of this memorable
ey.pedition. The first article, by Mr. O. B. B^ggild, is
devoted to the bottom-deposits of the Polar Sea. One
of the results of the expedition was to prove the existence
of a large, deep North Polar basin, the bottom of which
has been found to be covered with deposits of unexpectel
fineness. An inference from this is that the ice, which
generally drifts from Bering Strait towards the sea between
Greenland and Spitzbergen must be mainly sea-ice, with
a small proportion of coast or river ice from Siberia and
North America. \'ery interesting is the second article
by Mr. V. W. Ekman on " dead-water," a phenomenon
met with in the Norwegian and .Arctic Seas. It is
due to a layer of fresh-water above the salt-water of th-.;
sea ; and a vessel passing through it generates large waves
at the plane of division between the two liquids which offer
an unexpectedly high resistance to her progress. In the
third article the editor describes the Protozoa, or animal-
cules, to be met with on the ice-floes of the North Polar Sea.

Serials. — We have to acknowledge the receipt of Part 33
of the Transactions of the Y'orkshire Naturalists' Union,
which forms the concluding portion of the second edition of
"North Yorkshire; its Botany, Geology, Climate, and
Physical Geology," by J. G. Baker. The conclusion of the
account of the flowering' plants, together with lists of the
mosses and liverworts, constitute the contents of this fasci-
culus. We are indebted to the University of California for
a copy of a memoir by Mr. A. Hodlicka (published by the
University in its Archaeological and Ethnological serial) on
collections of skulls of the ancient and extinct natives of the
Californian peninsula. Excellent figures and elaborate
measurements are given ; so that the memoir should prove
of great value to anthropologists. Mr. H. R. Walkin has
favoured us with a copy of a paper on the " White winter
coat of certain creatures," in w-hich he refuses to accept the
view of Dr. Tronessart that the winter whitening of
mammalian hair is due to the action of phagocytes. In-
deed, he is somewhat sceptical in another way, seeing that
he is not assured that British park-cattle are semi-albinos.

.\lso to hand is a copy of the Report of the Colombo
Museum for 1905, published as Part IV. of Ceylon Ad-
ministration Reports. FVom this it is satisfactory to learn
that it has been resolved to enlarge the museum buildings,
provided that the Colonial (iovernment sees its way to sup-
ply the requisite funds. Dr. Willey, the Director reports
that the ^Iuseum continues to make satisfactory progress.
The Committee of the Bristol .Museum and .\rt Gallery has
l)ublished a fully-illustrated pamphlet of 75 pages, detailing
till- history and progress of that Institutie)n since its founda-
tion in 1772. The illustrations display the imposing pro-
portions of the buildings, and likewise give a clue to some
of their contents. It is .almost unnecessary to state that
both in the matter of natural history and of art the In-
stitution possesses a number of very valuable and interesting
specimens.

.\ Perpetual Calendar. — We have received from Messrs.

Philip and Son a specimen of their Universal Perpetual
Calendar, which is the most ingenious and complete ex-
ample of its kind that we have ever examined. It is the
work, evidently a labour of love, of the Rev. J. P. Wiles,
M..\., and we may congratulate him especially on the
simplified form to which he has reduced the calendar. Many
such devices require elaborate manipulation before they will
give the desired results, but this calendar can bo adjusted
with the greatest ease to any year between i a.d. and
2,000 A.D., and will, in addition, furnish the New Moons and
the date of Easter, Ijoth new and old stvle, for those years.

22

KNOWLEDGE & SCIENTIFIC NEWS.

[January, 1907.

Conducted by F. Shillington Scales, b.a., f.r.m.s.

Royal Microscopical Society..

.\u\ii.\iui;u Ji, Mr. A. .\. DLsnox , .M.A., 15. Sc, in llic
chair. The Curator described two old microscopes
which had been pre.scntcd to the Society's collection.
One was a Ciilpeper microscope of early 18th century
date, presented by Mr. Wynne 1'^ IJaxtcr; the other, of
late i8lh century date, was made by Dolland, after
Cull's model, and was presented bv Mr. C. Lees Curties.
Dr. Uebb exhibited a new porcelain filter, made by
Doulton and Co., suitable for laboratory work, and he
also exhibited for Mr. Taverncr a sm;dl filter bottle
for filtering micro mounting fluids. Mr. Conrad Beck
exhibited an optical bench for illumination with either
ordinary or monochromatic light, arranged to show
experimentally that A. pcUiicida could be resolved by
green light, when, under the same conditions, yellow-
light failed to resolve it. Messrs. Zeiss exhibited a
special microscope for photo-micrography of metallurgi-
cal specimens. Mr. J. W. Gordon gave a summary of
his paper, " On the Use of a Top Stop for Developing
Latent Powers of the Microscope," and exhibited his
ajiparatus, pointing out that a top stop admits of varia-
tion between the proportion of the refracted and un-
relracted light which passes the instrument, and thus
renders more conspicuous a particular feature of the
object. In illustration, he exhibited photographs taken
with an achromatic oil-immersion lens of N.A. i.o,
which were designed to show how, by means of a top
stop, an objective of this aperture might equal the per-
formance of an objective of much wider aperture. Mr.
Rheinberg contended that the use of a stop in the
Ramsden circle of a microscope was, from an optical
point of view, equivalent to the use of a stop in the
upper focal plane of the objective, and that the use of
a stop which puts out of use the central portion of an
objective deteriorates and falsifies the image. Mr.
Conrad Beck observed that if the course of the rays
were followed, it would be found that there was but one
]>oint through which all the rays passed symmetrically,
and that was in the Ramsden circle, so that this was the
best place for the insertion of a patch stop, and he con-
troverted Mr. Rheinberg's view that the jiutting of a
.stop in the posterior focus of the lens gave the .same
results. Mr. Conrady said Mr. Gordon had repeated
his idea that the well-known visibility of single minute
objects proved the accepted limits of resolution to be
wrong, and laid stress on the fact that mere visibility
and resolution were totally different things, the former
being merely a question of contrast, an object, however
small, beings seen if it contrasted sufficiently with its
background. Stars that were probably below ,,',„ of a
second in arc in apparent size were visible to the naked
eye, which had a limit of resolution of about 60 seconds,
and we had here visibility of objects measuring less
than 3000 part of the least distance at which two such
objects could be separated and resolved. He con-
sidered the delicate tracing on diatoms referred to by
Mr. Gordon to be spurious appearances of the
intercostal order. Mr. Gordon brieflv replied, agreein"-

with Mr. Rheinberg's statement that a top stop in the
Ramsden disc was equivalent to a stop placed in the
upper focal plane of the objectixe, subjict to Mr. Beck's
criticisms, and to the fact that the wave fronts were
plane in the former position and sj)herical in the latter.
Quekett Microscopical Club.

.\o\enilici' i(). A p.ipei 1)\ Mr. 1'. I'. .Smilli, on
" The Classification of the British .Spiders ol the genus
l.ycoso," was taken as read. Mr. ]''. P. .Smith gave a
lecture on "Vagabond .Spidirs. " He said that the
more highly specialised forms of sjjiders fell pretty
n.ituiallv into two groujis, the first — probably deriva-
tives ol the genus Fac/iygiiatlia — including all those
species which made either orbicular, " saucer," or
" tangle," snares, and second, those which constructed
no snare at all. The three principal groups of vaga-
bond (wimdering) spiders were represented by the
typical families Lycosid;e, Thomisidie, and Salticidae.
The females of the genus Lycosa carry the egg-sac about
attached to the spinners, and the young, w hen hatt-hed,
live for some time upon the back of the mother.
Spiders of the genus Piraia are al)le to- run u]Km the
surface of water, and Dolomcdcs constructs a raft and
makes considerable voyages. The Crab-spiders (Thomi-
sid;e) have a peculiar articulation of tlie legs which
enables them to travel forwards, sideways, or back-
wards with equal facility. A short description was
given of the more striking characteristics and habits of
the Salticida;, of which there are some 33 British species
at present known. The lecture was illustrated with a
number of especially interesting lantern slides, some of
" face " views of spiders, producing not only a striking
effect, but demonstrating clearly the arrangement of
the eyes, and was concluded w ith a series of five photo-
graphs showing the attack upon, and capture of, a
house fly by JMarpcssa iniiscosa.

Microscope Slidos.

Mr. H. W. H. Darlaston, of 20, Freer Road, Birch-
field, Birmingham, has sent me particulars of a some-
what novel method of circulating slides. Briefly the
arrangement is that for a subscription of two guineas,
600 slides will be sent, post paid, in 12 monthly parcels
of 50 slides each. From each monthly parcel five
slides, 60 in all, may be selected and retained by the
subscriber free, and he may also select further slides at
an all-round price of 6d. each. For a subscription of
one guinea, 25 slides per month will be sent, and two
per month retained, whilst for half a guinea twelve
slides per month are sent, and one per month retained.
Of the slides sent me as specimens I can speak highly;
they are beautiful examples Oif the mounter's art, and
in no way inferior to slides sold at double the price.
Microscope Material.

By the kindness ol Mr. lirnest Heath, of Cardiff, I
am able to offer for distribution to my readers a con-
siderable quantity of anchor mud and dredger sand
from the Adriatic. Mr. Heath says : " I made these
gatherings myself, and a friend sent me a great many.
They extend over a fairly wide area on the eastern
coast from Trieste to Spalato. Your readers will, I
think, find them very rich in I'^oraminifcra and MoDusca,
but the diatoms I expect I have pretty well washed out
in getting my own floatings. There is a very wide
range of L'oraminifera and abundant beautiful speci-
mens of PcHcroplis planalns. I have also had some very
curious and abnormal specimens of Polymorphina. The
Adriatic is one of the richest seas in Foraminifera. I
was bathing from the shore on one of the Brioni Islands,
and as I walked into the sea the sand rose up and
floated around my legs in clouds, just the same as one

January, 1907.]

KNOWLEDGE & SCIENTIFIC NEWS.

23

sees it when washing and floating the gfatherings. I
should think that 50 or (So per cent, of the sand is com-
posed of the empty shells." In a further letter, Mr.
Heath says : " With reference to pro<-uring supplies of
dredging-s and ocean ooze, one of the best plans I
know of is to get in with an ofBcer of one of the cable-
laying steamers, which take soundings in great depths.
I have so far failed myself to get to know one, but hope
some day I may do so. I have had a lot of very ex-
cellent rnaterial, however, from the steam trawlers that
work out from Cardiff. I wrote to a member of one
firm asking him if he would kindly allow me to board
his trawlers when they arrived in, to .scrape the sand
from the crevices of the trawls, and he most kindly
gave his superintendent instructions that I was to have
everv facility, so that I collected from the different
trawls from prettv nearlv all the grounds they visited,
including off 'the Smalls'; off 'The Wolf; the
Atlantic^ 150 miles west of I.undy; off the Basketts
(Cape Clear, S.W. Irish coast); 30 miles S. of Kinsale
Head; off Ushant, Finisterre, &c. I also had some
very fine material collected by an officer on H.M.S.
Euryahis when on the Australian station. These in-
clude Broken Bay, Hawkesbury River, N.S.W., 7
fathoms; Largs Bay, S.A., 6 fathoms; Auckland, N.Z.,
6 fathoms; Port Lincoln, S.A. (poor), q fathoms; Hob-
son's Bay, Melbourne (verv poor), 5J fathoms; Sydney
Harbour, X..S.\V. (verv rich), 8i fathoms; off Ceylon,
Indian Ocean, 35 fathoms; Colombo Harbour, 7
fathoms; Suez (Egypt), and Port Said, 28 fathoms.
He also had some from .Aden, but said it putrified and
stunk his cabin out so he had to commit it to the deep
ag^ain. This officer is now in home waters, and has
offered verv kindlv to collect for me more material
when the opportunity occurs. The Adriatic anchor
mud, &c., with the exception of five, which I got my-
self, were sent me by an officer in the .Austrian Xavy,
and were taken from a torpedo-boat, on which he was
cruising-. One of them was actually taken from a dis-
charged and recovered torpedo, which should have had
a very g^ood sample as it would be running along the
bottom for some little distance when slowing down.
This officer I had interested very much when I was over
there last year, showing^ him with a pocket lens of 20
diameters the lovely little shells. He has also promised
to send me more when he has an opportunity. " I
wish I could reproduce more of Mr. Heath's very inter-
esting letters, which show how an enthusiastic collector
may enlist the help of others for his hobby. Those of
my readers who would like .some of this sand must
send me a stamped addressed envelope, a small tin box,
and the coupon to be found in the advertisement
columns of this issue. May I add that the number of
applicants is generally so great that I cannot pay any
attention to applications which do not carry out all of
these simple conditions. It would be amusing- were I
to detail some of my experiences in distributing material
of this nature.

Notes and Queries.

C. E. G. {f^hanijhai). — Vour Ittlir inler^■^tf■d me verv much,
and I feel sympathy for anyone working- under vour condi-
tions. I think you rannot do bftlcr than devote vour atten-
tion to mites, an<i I woidd refer you to an article on the
subject contributed by Mr. C. W'arburton to these columns,
and published in May and June, 1904. Mr. Warburton is
one of the authorities on the subject, and in his article tjives
notes as to collecting-, &c. If you decide to take up the
matter definitely I shall be glad to put you into communica-
tion with him, or with others who are likewise interested
in the subject. With regard to the photographs, yeast is

ver\- difficult on account of its want of contrast, and I shall,
therefore, not be too critical about it. The others are good
attempts for a beginner, and their most serious fault is that
the slides themselves are not satisfacton,'. In making
mounts of insects you cannot be too painstaking in the
initial stag^es of preparation. If you begin by treating with
caustic potash, the whole process must be carefully watched,
and the turpentine stage must be equally closely watched,
but a section that is not transparent, or one that is not
uniform, is useless for photography. In the photograph of
the flea, for instance, the legs are so pale as to have no
contrast, whilst the bodv is almost opaque. A similar
criticism applies to the head of the mosquito, and to the
beetle's head. You have also a tendency to get an illu-
minated disc that is not quite uniform, which spoils the ap-
pearance of the photograph, the remedy being careful
centring^ and adjustment of all the optical arrangements,
especially the condensers, as laid down in my articles on
photo-micrography in this journal (November, 1905, to June,
1906). .Some of the photographs are not precisely focussed,
and in others there is a tendency to stop down the condenser
too much. Ordinan,' low-power objectives are not satisfac-
tor\- for photo-micrography, and it is well worth purchasing
one or more of the piano-lenses made by various opticians.
W. Watson and Sons make a good series under the name of
" Holostigmatic " at /^^ each, of which the most generally
useful are the 3-in. and 33-in. Reichert also makes a good
series, of which the most useful are a 3-in. at 50s. and a
4-in. at 60s. Zeiss' Micro-planars are excellent, but thev
cost ;C.6. -All these are used without eyepiece. Watson's
Variable Magnifier is unsuitable for photography, being de-
signed as a hand or dissecting lens. Achromatic lenses per-
form fairly well without eyepiece, but the image is
sharpened by using a projection ocular, the lower in power
the better.

IF. M. H. (Winchester). — There are several methods of
reproducing drawings, whether from illustrations in books
or not, but the simplest way is to photograph them direct.
For this any ordinan,- photographic camera is suitable, pro-
vided it has a camera extension which will allow it to photo-
graph at quite a short distance. For my own work I use a
^vS .Ss. |-plate " Kodak," which has a camera extension
which enables me to focus an illustration set up about 17
inches away, the lens being a good one and fairly flat in the
field. By a little ingenuity an ordinary- photographic lens
could be fitted for this purpose at the end of a photo-micro-
graphic camera. It is then only necessar\- to set the page
to be photographed opposite to the lens, making sure that it
is vertical, at right angles, and that the whole page is flat,
to illuminate it with as strong a light as possible, and to
photograph as usual. .A suitable wooden stand is easily
made. In making the negative it is important to get sharp
definition and a clean ground, any fogginess spoiling the
slide for lantern purposes. By using :J-plates it is easy to
print ordinary 31-inch square lantern slides by direct con-
tact with the negative thus m.ade, the two plates beinsj
printed in an ordinary frame, the lantern slide taking the
place of the ordinary printing paper, and exposed to litrht
in the same way. I have had excellent results with Ed-
wards' " Kristal " plates, full instructions for development,
&c., being sold with each packet. It is best to take the
negatives on a J-plate if possible, as otherwise thev have
to be reduced in size, which is a nuisance. I assume that
you are familiar with ordinary photographic methods, in
which case the above hints will, I hope, serve your purpose.

Orran Ooze anil Diafomarrmis Earth. — Mr. G. E. O.
Mullins, of Bristol, will be grateful if any reader can tell him
where he can procure ocean ooze. He .says he has watcheil
the advertisements in the scientific journ.als for some time.
He would also be glad to know where he can obtain the
diatomaceous " mountain llour " of Norway. With regard
to the former inquiry, Mr. Mullins will probably read with
interest the rem.arks accompanying Mr. Heath's olTer of
dredgings from the .Adriatic in another part of these
columns. Mr. Heath very kindly offers to allow him to
select from the material mentioned.

[Communications and inquiries on Microscopical matters should he
addressed to F. Shillinolon Scales. " Jirsey." St. Bamalyas Road.
Cambridge. Ccrresf>ondtHts are requested not to send specimens to be
named.]

^4

KNOWLEDGE & SCIENTIFIC NEWS.

[January, 1907.

The Face of the Sky for January.

By W. Shackleton, F.R.A.S,

The Si'N. — On the ist the Sun rises at 8.8 and sets at
3.50; on the 31st he rises at 7.44 and sets at 4.44.

The earth is nearest the Sun on the 2nc1, when the
Sun attains his ma.ximum apparent diameter of 32' 35".

Sun-spots are not very numerous, thou<;li an occasional
group may be obferved on the solar disc.

There will be a total eclipse of the Sun on the 14th,
invisible in this country, but visible in Central Asia as a
total eclipse, and in India as a partial one.

The positions of the Sun's axis and of the centre of
the disc are given below : —

Dale.

Axis inclined
from N. point.

Centre of disc

S. of Sun's

Equator.

Heliographic

Longitude of

Centre of Disc.

Jan. I

f> ..

,. 16 ..

, . 26 . .
Feb. 5 ..

2° i6'E
0° lo'W
4° 58 'W
9° 32'W
13° 41 'W

3° 7'
f 41'
4° 44'
5° 37'
6° 20'

137° 56'

72° 5'

300° 24'

168° 45'

37° 5'

The Moo.m

—

Date.

Phases.

H.

M.

Jan. 7 .

.. 14 ••
,, 21 ..

., 19 ••

•
0

Last Quarter
New Moon
First Quarter
Full Moon

2

5
8
I

48 p.m.
57 am.
42 a m.
45 P-m-

There will be an eclipse of the Moon on the 2gth, but
it is invisible in this country.

OCCULTATIONS :

Date.

Star's

3

Disappearance.

Reappearance.

Moon's

Angle

Angle

Age.

s

Mean

from N.

Mean

from N.

Time.

point.

Time.

point.

p. m.

p. m.

d. h.

]

in. 21 f^Ceti

4*3

9 7

94°

10 12

224°

7 15

,, 26 u Geminorum ..

4-1

6 40

112°

7 45

231°

12 13

., 27 I56 Geminorum ..

5 0

7 39

38°

827

317°

13 14

,, 27 i3i Geminorum ..

5-7

10 30

m"

II 52

282°

13 17

V

/ Leonis . .

5'3

9 19

61"

10 5

333°

17 15

The Planets. — Mercury (Jan. i, R.A. 17'' 25"";
Dec. S. 22° 50' ; Jan. 31, R.A. 20'' 48m ; Dec. S. 20° 2')
is a morning star in Scorpio during the early part of the
month. The planet is not well placed for observation,
and towards the end of the month is out of range, as he
is approaching superior conjunction with the Sun.

Venus (Jan. i, R.A. 16'' 3"> ; Dec. S. 16° 21';
Jan. 31, R.A. 17'' 35'"; Dec. S. 19° 17') is a morning
star in Scorpio rising at 4.40 a.m. on the 4th ; on this
date the planet is at greaicst hriUiaitcy. The telescope
appearance is a thin crescent, 0-35 of the disc being
illuminated en the 15th.

Mars (Jan. I, R.A. 14'' 28"; Dec. S. 13° 33'; Jan. 31,
R.A. 15'' 40"; Dec. S. 18" 41') is a morning star, in
Libra, rising at 2.47 a.m. on the 15th. The apparent
diameter of the planet is increasing, being about 5"\5 ;
this, however, is still too small for useful observation
with telescopes of moderate power.

Jupiter (Jan. i, R.A. 6'' 24™ ; Dec. N. 23° 15'; Jan. 31,
R.A. 6^ 9™ ; Dec. N. 23° 25') is very favourably placed
for observation in the evening, rising at 2.23 p.m. on
the 15th, and being due South at 10.39 p.m.

The bright moons can be seen in very small telescopes,
or even in a pair of binoculars magnifyirg 6 or 8 times.

On the evening of the 2r)th the Moon will appear near
the planet.

The equatorial diameter of the planet on the 16th is
45"'9. whilst the polar diameter is 3"-o smaller.

The following table gives the satellite phenomena
visible between 8 p.m. and midnight: —

e

c

u

u

y.

B

4J

,5

a

P.M.'s

4>

2

u

P.M.'s

£

2

P.M.'s.

i/i

a.

11. M.

a

in

B<

II. M.

a

m

0.

H. M.

Ian.

Ian.

J.-in.

4

11.

V.C. R.

" 3

'3

Tr. I.

9 52 2.|

IV.

Ec. D.

II 10

.5

1.

Oc. D.

10 50

-Sh. I.

10 17

=■;

III.

Ec. R.

II 48

b

1.

Tr. I.

8 8

I)

Kg. R.

9 42

27

II.

Tr. I.

8 58

i.

-Sh. I.

8 22

20

11.

Tr. E.

9 29

II.

Sh. I.

ID 26

1.

Tr. E.

10 25

II.

Sh. E.

10 3q

II.

Tr. E.

II 48

1.

.Sh. v..

10 30

Tr. I.

II 37

28

I.

Oc. D.

ID 32

7

III.

Tr. I.

0 5fi

21

Oc. D.

8 46

29

II.

Ec. R.

8 5

III.

.Sh. I.

10 50

Ec. R.

" 37

I.

Sh. I.

8 34

II

II.

Oc. 1).

10 7

22

Tr. E.

8 20

I.

Tr. E.

lo 6

13

11.

Sh. IC.

8 2

.Sh. E.

8 57

30

I.
I.

Sh. E.
Ec. R.

10 52
8 I

Oc. D." denotes the disappearance of the Satellite behind the disc, and
" Oc. R." its reappearance ; "Tr. I." the ingress of a transit across the disc,
and "Tr. E." its ef^ress ; " Sh. I." the ingress of a transit of the sliadow across
tile disc, and " Sh. E." its egress; " Ec. D." denotes disappearance of Satellite
by Kclipsf. and " 1-x. R." its reappearance.

Saturn (Jan. i, R.A. -2.2'^ 511"; Dec. S. 9° 25';
Jan. 31, R.A. 23I1 im ; Dec. S. 8" 17') is getting more
to the west, and observations are only possible in the
early evening. On the 15th, the planet is due south at
3.20 p.m. and sets at 8. 38 p.m. The ring, which can
be seen in small telescopes with moderate powers,
appears to be gradually closing up ; we are looking on
the northern surface at an angle of only 5".

Uranus (Jan. 16, R.A. 18'' 42™ ; Dec. S. 23° 25')
was in conjunction with the Sun on the 31st of last
month, and hence is unobservable.

Neptune (Jan. 16, R.A. 6" 47""; Dec. N. 22° 6') being
in opposition to the Sun at the early part of the month,
is on the meridian at midnight. The planet is situated
in Gemini, not far from the star 36 Geminorum.

Meteor Showers: —

Date.

Radiant.

Name.

R A.

Dec.

Jan. 2-3
,, 17

h. m.
XV. 20
XIX. 40

+53°
+53°

Quadranlids.
B Cygnids.

Minima of Algol may be observed on the 17th at
1 1. 31 p.m., the 20th at 8.20 p.m., and the 23rd at 5.9 p.m.

0 Ceti (Mim) is unusually bright at this maximum, being
equal in magnitude to a Arietis (2-1), nearly a fortnight
before the computed date of maximum. Observations
should be continued to determine the date of maximum
and rate of diminution in brightness.

Telescopic Objects : —

Nebula. — Orion Nebula, situated in the sword of
Orion, and surrounding the multiple star e, is the finest
of all nebulrc ; with a 3 or 4 inch telescope, it is best
observed when low powers are employed.

Double Stars. — ^ Orionis (Rigel), mags, i and g,
separation 9". On account of the brightness of the
principal star, this double is a fair test for a good object-
glass of about 3-inch aperture.

5 Orionis, mags. 2 and 7, separation 35"; easy double.

i' Orionis, triple, mags. 3, 6, and 10, separation 2"*5
and 56"; rather difficult in a 3-inch telescope.

X Orionis, mags. 4 and 6, separation 4"-5 ; pretty
double.

0- Orionis, triple, mags. 4, 8, and 7, separation i2"-5
and 42".

January, 1907.]

KNOWLEDGE & SCIENTIFIC NEWS.

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