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Se Hehe 4 “" Woy 1 be Rod Got dade eto deteseerh de iowa TPNH He aedefe to eeleew ‘ Fe OH OE NLS Nee ted rtd ao ’ : La Lom etme ed eed ee ‘ ' 0B 8 Ee Od ow og . in ie Mer gee ee on i ee oe 4 2 were Chai ary . we ee ea Cie Peek + ed ae Rete 0 try hy Ae ele Le q Pe LL eee Egat « Ma A a eR He Braise merase tyre her F i “ La . d 4 ue spree Stas aie Math tiki Pa Ne hs Bn oe oe Sa th Gh oh 4 WS Selentey dat * (3 ris “Se Rah: setae oe ae eh dow an AAS eaten a pce ak . ; pray eaters Aare Soe Alder ils ahs re Scheaternce S$) OGed aon nt Ne oe ae A ape at Oe Mehanem torpedo Rema witeed rae it ius beat at Coa bony Hee deh Sat wert Wede tM te ¥ or Wis Batra Ns 5 eed eae Ae bohm bed _ Path Mabustatle terk-bi. th tutta eco Aon eke C oF ee : A RT he he ert dy eye Wet ine alte oe ON ee OE HL Ve dee me fod + 2iher 4 ard © eta twee eG ~ Ogee A AW OE ete 4 aaa aa “Re Otte a ce ges wah pink te ° © ened. nw w 6h Cee & o 4a ae tot an Ween ee «eee ere y q sa i A . ‘ a: wivie aa Hs Mn ti het SE EWA ete Wee a Ee Me Ried ew degiaedidl he Ey ace ie, he Sede tet on een & * Sea wnt A ar ow Ee Ged deagiadee Ai Cee ede. te A oe ted 1 pled ‘ 2 ° SR Yt OW rw Pew dee ead OMe 8 Gee we dade DAME A ALB ae ete dow ou ing a& ~ 4 i r ; + a PEE ED oH eh rth Bee a He Gee AE ite La Heath ard Sateucrraatca as 4s Feria a8 WG Frys we i He He * TO A Ee He tlle ko ed eH Hg: Fagen eo eaten min WRENS Ee dw WES A Fone ed Ga & 7 WAP bah bl To Lat Lived é He EEE Sheth aoe Boo ete Th the See Ree eng Hert lp Me eee Ami esha gh Woy whet Cad eee ao ocnceee TW TOA A ne Y TAHA SH AW «nang AoW gaa WAN Ag Wee dae Ae LE i + Ueto. nA ae athe a AA PRP HOR th IL aa Pate tte stats Nes vet : 6 bald Weep fhe Howe ert te aoe LAL oe AW He AM age ge Wit ot eh Me hk: Neha W (Asis Hit bey oe Fete te oe de Sh a i ha a we , A 2 ay ei Oi erg 269 On the Solar Protuberances. By M. Janssen. In a Letter to Warren De Me RE iin a aS es an tye S abn a eich iE AE? cia maitre «Sis aon ges ising Ree 276 On the Structure and Development of the Skull of the Common Fowl Gaius domesticus), By W. Kitchen Parker, F.R.S.. 00.0.2 cece es 277 Determinations of the Dip at some of the principal Observatories in Europe by the use of an Instrument’ borrowed from the Kew Observatory. By faens. Wlacim, Imperial Russian Navy..,....:-¢s6+000es040 Apnert net 280 « V1 On a New Class of Organo-metallic Bodies containing Sodium. By J. Alfred Wanklyn, Professor of Chemistry in the London Institution .... On the Temperature of the Human Body in Health. By Sydney Ringer, M.D. (Lond.), Professor of Materia Medica in University College, Lon- don, and the Late Andrew Patrick Stuart ....... rR os Preliminary Note of Researches on Gaseous Spectra in relation to the Physical Constitution of the Sun. By Edward Frankland, F.R.S., and J. Norman: Lockyer, F.RvA. Ss 10:0: 0%. 070% 700s 50 4700 tel ele eto aa eee ees On the Structure of Rubies, Sapphires, Diamonds, and some other Minerals. By H.C. Sorby, F.R.S., and P. J. Butler’ 00 cee en: ete Note on a Method of viewing the Solar Prominences without an Liclipse. By (William Ebugping, ERS. 5) ais5 aie'et arate: ots tvie inal acleale (anes eee Additional Observations of Southern Nebule. In a Letter to Professor Stokes, Sec. R.S., by Lieut. J. Herschel, RoW. . aes -ee eee Note on the Separation of the Isomeric Amylic Alcohols formed by Fer- mentation. By Ernest T. Chapman and Miles H. Smith ............ Note on the Heat of the Stars. By William Huggins, F.R.S. .. eee On the Fracture of Brittle and Viscous Solids by “ Shearing.” By Sir W. WMhomson, FURS. ose ca ec ec obs vc cane Sahn ne a ee Note by Professor Cayley on his Memoir “ On the Conditions for the Ex- istence of Three Equal Roots, or of Two Pairs of Equal Roots, of a Binary Quartic or Quintic” o. 0k. eas wae na 0 0 0 ons Oe sie nee Appendix to the Description of the Great Melbourne Telescope. By T. R. ‘Robinson, D.D., F.R.S i) 8&6... 60.6 i. ew 0 ale a cheere te neler Note on the Formation and Phenomena of Clouds. By John Tyndall, 1 BOBS BAe! 0 5 ie Maen IAA Go Uke ‘. On the Behaviour of Thermometers in a Vacuum. By Beniamin Loewy, RASS. ceca sca ite volte wilale dues ose elulel fle intel ona tease a rete Account of the Building in progress of erection at Melbourne for the Great Telescope. In a Letter addressed to the President of the Royal Society by Mr. R. J. Ellery, of the Observatory, Melbourne... anne eee: Contributions to the Fossil Flora of North Greenland, being a Description vi the Plants collected by Mr. Edward Whymper during the Summer of 1867. By Prof. Oswald Heer, of Zurich 14... ieee On the Specific Heat and other physical properties of Aqueous Mixtures and Solutions. By A. Dupré, Ph.D., Lecturer on Chemistry at the West- minster Hospital, and’ F. J. M. Page ,.,;, 20% ...sas one Be Researches into the Chemical Constitution of Narcotine, and of its Products of Decomposition.—Part HI. By A. Matthiessen, F.R.S., Lecturer on Chemistry in St. Bartholomew’s espa oly neo'e s. 6 pile Rae eet eee ae Researches into the Chemical Constitution of Narcotine, and of its Products Page 286 287 288 291 302 305 308 309 vil Page _of Decomposition — Part IV. By Augustus Matthiessen, F.R.S., Lec- turer on Chemistry in St. Bartholomew’s Hospital, and C. R. A. Wright, es LTE ELT Ly See ere ere cre eM 340 On the Corrections of Bouyard’s Elements of Jupiter and Saturn (Paris, 1821). By Hugh Breen, formerly of the Royal Observatory, Green- sa ed ERE Sa arrearage ar arr rearrange are 344 On the Structure of the Red Blood-corpuscles of Oviparous Vertebrata. By eri Ee. ai re eee eo gw nts pan a 2 db Sle wee ca selW adn ope 346 Spectroscopic Observations of the Sun.—No. III. By J. Norman Lockyer, 6 (ke P| 9 Sei RAIS IES SSB eae nar mar earirarerararrarirerarar aarti Note on the Blood-vessel-system of the Retina of the Hedgehog (being a fourth Contribution to the Anatomy of the Retina). By J. W. Hulke, F.R.S., Assistant-Surgeon to the Middlesex Hospital and the Royal Lon- Oe TEE G55 )5) 00 SP eae 507 On the Measurement of the Luminous Intensity of Light. By William RUM OGC ed Pa elec sierigc eset cease tees cee enemas Hae Cie Addendum to description of Photometer. By W. Crookes, F.R.S. ...... 369 Preliminary Notice on the Mineral Constituents of the Breitenbach Mete- meme ley Erotessor N. Story Maskelyne, M.A.......0....0ceaerensees 370 On the Derivatives of Propane (Hydride of Propyl). By C. Schorlemmer 372 Researches in Animal Electricity. By Charles Bland Radcliffe, M.D. .... 377 On the Source of Free Hydrochloric Acid in the Gastric Juice. By Professor etter Cambridce, US. A, oo. cence e ites ben aees Bol Contributions to the History of Explosive Agents. By F. A. Abel, F.R.S., EELS. Sep USE rear ae tr Ga ra are aa rea 395 Results of Magnetical Observations made at Ascension Island, Latitude 7° 55’ 20" South, Longitude 14° 25’ 30” West, from July 1863 to March eeemeer tet, Evokepy; RM ce ce aes kee ce ween eb evadans 397 Description of Parkeria and Loftusia, two gigantic Types of Arenaceous Foraminifera. By Dr. Carpenter, V.P.R.S., and H. B. Brady, F.L.S. .. 400 On Remains of a large extinct Lama (Palauchenia magna, Owen) from Quaternary deposits in the Valley of Mexico. By Professor Owen, eR corte chars ra ersten eet as Deere ead bead vet 405 Cn the Proof of the Law of Errors of Observations. By M. W. Crofton, PEM cA eae se oe ac 6 CaM a eS PN thera eons re whee Rae Gs 406 On a certain Excretion of Carbonic Acid by Living Plants. By J. Brough- ton, B.Sc., F.C.S., Chemist to the Cinchona Plantations of the Madras Government Be ee ie a hi alae S SAS COS Ee Po Re Pe Cerin ek 408 On the Causes of the Loss of the Iron-built Sailing-ship ‘ Glenorchy.’ EBy, rebar memith, Hsq., M.A; LL.D., PRS... 8 Seo cs Sue 408 Spectroscopic Observations of the Sun.—No. IV. By J. Norman Lockyer, 2a. Be ee stalish sha Wiehe seamen Pe Miche As wise eles Sra 415 Vill Page On some of the minor Fluctuations in the Tenperature of the Human Body when at rest, and their Cause. By A. H. Garrod, St. John’s College, Cambridge ....5. 002000000 sss 2s040s 09s Nie 5 oie eee. Observations of the Absolute Direction and Intensity of Terrestrial Mag- netism at Bombay. By Charles Chambers, Superintendent of the Colaba Observatory 0.0.20 0c ce cone e weve veg = vews ns yanp 00a anc tr On the Uneliminated Instrumental Error in the Observations of Magnetic Dip. By Charles Chambers, Superintendent of the Government Observa- tory, Bombay . 2.6.5 +.0+++cne + 10s % +s oy Eee ene ter On the Laws and Principles concerned in the Aggregation of Blood-cor- puscles both within and without the vessels. By Richard Norris, M.D., Professor of Physiology, Queen’s College, Birmingham .............. Researches on Turacine, an Animal Pigment containing Copper. By A. W. Church, M.A. Oxon., Professor of Chemistry in the Royal Agricul- tural College, Cirencester ...... Pe Ae ee On the Radiation of Heat from the Moon. By the Earl of Rosse, F.R.S... On a new arrangement of Binocular Spectrum Microscope. By William Crookes, FVR.S. ke. 0005000000) eases et ee On some Optical Phenomena of Opals. By William Crookes, F.R.S. &ec., Researches on Gaseous Spectra in relation to the Physical Constitution of the Sun, Stars, and Nebule.—Second Note. By E. Frankland, F.R.S., and J. N. Lockyer, | Sl 8 PP : On the Molar Teeth, lower Jaw, of Macrauchenia patachonica, Ow. By Professor Owen, E.R... 250.0 cess cease 0 > vis «2 ne ee - Researches into the Chemical Constitution of the Opium Bases.—Part I. On the Action of Hydrochloric Acid on Morphia. By Augustus Matthies- sen, F.R.S., Lecturer on Chemistry in St. Bartholomew’s Hospital, and CG, R.A. Wright, Bie. 2.0... oes oa = cle bee 2 a 45 Researches into the Constitution of the Opium Bases.—Part II. On the Action of Hydrochloric Acid on Codeia. By Augustus Matthiessen, F.R.S., Lecturer on Chemistry in St. Bartholomew’s Hospital, and C. R. A.W, right, BSG. isc eae see cee eon eas b= eis Smly eget eer A Preliminary Investigation into the Laws regulating the Peaks and Hol- lows, as exhibited in the Kew Magnetic Curves for the first two years of their production. By Balfour Stewart, LL.D., F.R.S., Superintendent of the d ind |at etiary hN 1042 ,, Ku CROW OGCUID Sccc iced neo ela He ts een el ee 106°5 <7) ase ISA STOTT a eR ns RIOR TN a | RYE Ao 108 3) ee Tin aia}e/alelalojets|e/clelslofeinjalsieraielelavel]/ iiiiale Ono0bG06. jf) Goodnoode 1 18 i) Sn LOPLI atte tak eee ee ete Om, oe 119 apn al COTTE I AS ET heel oe OA nares 120 a AE UI OI OU eas mtn tais| hee aaa |S RUC? 2 122.5 pe ee Taye Lae ane ia hs aN a oN 8:716 125:95 127 5 eee Me dlmrinuny hele saan oes 8-913 128-80 129 57 eS CSUR Fries ong ee 133 ae: J OL IOH OC EC THES ine ABs: Rey Aas e7/ oe SLOVO IOH COR ARORA) HER RS os i Ryness 137-6 = ee: ATBOMIG OE Aescises.ccoss: 10-6 153-18 150°, «Ze DUNGSUCH Meets ant iencss |e eoeteeees | |e tee eet 184 ee) GO errno sales ee o0| py teeeaaeucn Uhlan Serene 196°6 «30a eee DETOUR eid eae ee ANY ae eh che Nl am ont ae 197-2 ” Ir TEM ASW ODHU DS cos Gee eR RD | Peete ate: (oN Oy lect 1972. 5) =aat OST AG ear oe OSE Fee oA SE LN oe been 199 59 20S GI ag ae ne om, Cec Al manner A |. Sheen. 204.5 Gy 8! FOTO BAS igs is Soe an ORR Os re (BiGe ccnp Mae ES 207 3 ebb 1 BYU OAL MAME ih MA eas Moles it ene Baran] BEEP Reet 210 =) <7 ee. | Recess, Whether present in the sun’s atmo- sphere or not. present. present. present. not. present. present. present. present. not. doubtful. not. not. not. not. not. not. not. not. not. present. not. not. not. not. * [The position of vanadium has been altered from that assigned to it in the MS. of this memoir, in accordance with Roscoe’s recent investigations regarding this sub- stance. Ifthe vapour-density of vanadium be ever determined, it is presumable that its molecular mass will prove to be 2V, 2. ¢. 102°4, in analogy to those of phosphorus and arsenic, in which case its position in the Table will need to be altered again,—Sep- tember 1868. | x 1868. ] Constitution of the Sun and Stars. 17 Section IIl.—Of the Outer Atmosphere of the Sun. 27. Such, then, is the order in which we should expect to find that those of the elements which exist in the sun’s atmosphere succeed one another,—the atmosphere of hydrogen far overlapping all the rest; then, - at a profound depth, sodium and magnesium, reaching nearly to the same height, smce the masses of their molecules are nearly equal; next, at a great distance further down, calcium; then, in a group reaching nearly to the same height, chromium, manganese, iron, nickel, and cobalt; then, within a moderate distance of these, copper and zinc; and lastly, after a vast interval, barium. These are all the elements as yet known to exist in the sun’s atmosphere. Let us now compare with the observations this anticipation founded on the molecular constitution of the elements, bear- ing in mind that the order is likely to be in some few cases incorrect, owing to our having occasionally erred in assigning the foregoing masses to the yapour-molecules. To make this comparison most effectually, Table II., opposite to p. 32, of the intensities of the solar lines observed by Kirchhoff will be of use. In this Table the lines of each known constituent of the solar atmosphere are placed in the order in which they occur in the parts of the spectrum mapped by Kirchhoff, which extend between wave-lengths 43 and 77 eighth-metres, that is from the indigo about G to the extreme crimson beyond A*. Each spectral line is represented by a number, * The reader should have by him Kirchhoff’s maps of the solar spectrum in illustra- tion of this paper. They have been published in a separate form by Messrs. M*‘Millan and Co. It will make a reference to these exquisite maps much easier, not only for the purposes of this memoir, but also for many other purposes, to mark with pencil-dots upon Kirchhoff’s arbitrary scale each of the following positions of an absolute scale, founded upon Angstroms determinations of the wave-lengths of 70 lines (see Poggen- dorff’s ‘ Annalen,’ 1864, vol. iii., or Phil. Mag. 1865, vol. i.). Positions upon Kirchhoff’s scale of the principal points of a scale which expresses the lengths of the light-waves in air. (N.B. Those positions which have a note of interrogation after them are doubtful, as they are too distant from rays measured by Angstrém to admit of a safe interpolation.) Wave-lengths || Wave-lengths in in eighth-metres, Kirchhoff’s eighth-metres Kirchhoff’s 2. €. metres di- arbitrary 2. é. metres di- arbitrary vided by 10°. scale. | vided by 10°. scale. 43 corresponds to 2873°1 | 44°30 vs 2651°5 43:10 3 28550 | 45 = 2553°2 ? 43:20 - 2837-0 46 ms 2422-0? 43°30 : 2819-0 | 47 F 2299:5 ? 43°40 -- 2801-1 | 48 35 2164-0? 43°50 os 2783°4 | 48°50 Ss 2099°8 43-60 fe 2766-0 | 48-60 5 2086°7 43°70 = 27488 leer 48-70 me 2073°7 43:80 Be 27320 48°80 " 2060°8 43-90 5 2715°7 | 48:90 7 2047-9 44 Me 2699°6 : 49 . 2035°2 44-10 ¥ 2683-7 49-10 2 2022°6 44-20 s 2667°6 49°20 - 2010°2 VOL. XVII. C 18 Mr.G. J. Stoney on the Physical [ Recess, 1, 2, 3, 4, 5 or 6, which also indicates its strength in the solar spectrum, 6 meaning the darkest and 1 the faintest recorded by Kirchhoff. 28. The study of this Table is particularly instructive. It will be con- venient to begin by studying the iron lines, since they are numerous, - extend over a great range of the spectrum, and above all because there appear to be no bright lines in the iron spectrum to which dark lines in the solar spectrum do not correspond. This was invariably the case with those observed by Kirchhoff, who has mapped upwards of 70 of them TABLE (continued). Wave-lengths Wave-lengths in in eighth-metres, Kirchhoft’s eighth-metres, Kirchhoff’s @. e. metres di- arbitrary z.é. metres di- arbitrary vided by 108. scale. vided by 108. scale. 49°30 corresponds to 1998-0 55 corresponds to, 1309-0 49-40 - 1986:1 55°70 ~ 43 1248-4 49-50 7 1974-3 55°80 5 1240-2 49-60 : 1962°5 55°90 5 1232-0 49°70 3 1950°8 56 a 1223°8 50 # 1913:0? 56°10 : 1215.6 51 ,, 1762:0? 56°20° 5 1207-4 51:60 te 1673-0 56°30 Pe 1199°3 51-70 i 1658°3 57 “: 1144-0? 51:80 % 16443 58 a 1070-0? 51:90 $5 1630°8 58°90 59 1009°7 52 a 16175 59 3 1003-0 52°10 . 16043 60 oe 948-0? 52:20 3 1591:2 61 #3 897-2 52°30 Z 15783 61:10 55 891-9 52°40 53 1565°5 61-20 5 886°6 52°50 03 1552°8 61:30 3 881°3 52°60 5 1540-2 61:40 fi 8761 52°70 39 1527-9 61°50 : 8709 52-80 33 1516-1 61-60 5 865°7 52-90 3 1504-8 61-70 2 860°6 53 : 1494-1 61-80 43 855°5 53°10 3 1483°8 61-90 55 850°5 53°20 3 1473-7 | 62 s 845°5 53°30 : 1464-0 63 . 800-0 ? 53°40 > 1454-4 64 is 758°5 ? 53°50 5; 14456 | 65 - 719-1? 53°60 y 1436-1 66 e 682:3 53:70 0 1426°6 67 ” 648°3 ? 53°80 . 1417-2 68 = 615°9 ? 53°90 - 1407-7 69 is 5848 54 :; 1398°3 70 = 555°8 ? 54:10 + 1389:0 71 5 528-4? 54-20 o 1379-7 72 is 502°4? 54-30 . 13705 ~ 73 ee ATT 2 54-40 == 1361-2 (Se: + 453'8 ? 54:50 ~ 3 1352:1 7) et 430°3 ? 54°60 ya 1343°3 76 29 406-9 54:70 y 13384:7 | 17 9 3836? The following Table contains the original determinations expressed in metrical mea- sures on the supposition that a Paris inch=27-07 millimetres. The sign + is added where the omitted decimals lay between -0016' and ‘005, and— where they lay between ‘005 1868. | Constitution of the Sun and Stars. 19 between G. and C. Kirchhoff used a Ruhmkorff’s coil to produce the iron lines; but Angstrom has lately compared the solar spectrum with and 0083’: + is accordingly to be read plus one-third of a Xth-metre, and—, minus one-third of a Xth-metre. This goes to about the same amount of approximation as - the numbers given by Angstrim. Wave-lengths of 68 rays of the solar spectrum in VILIIth-metres, reduced from Angstrim’s determinations. ; oI | Ser : w m2 cog 8S a = ab Ages Bek: Se 5 25 of g o 5 Bg a0 & Fro ap 9 Remarks Beep oo a2 pbigeeie =e SSS i se a ce =) 22 | 25 | a, | 280% 5 mee See no & ar .9 os 5 o 4 4 Sea aa ees B 8 4 2 RG Hoka = = = o = H, 39°36 | od ery oe eae am eee Ca. 1a ieee SO— | - siehivvs | skteetnes Ca. A AQ | oc candys. fp cbattcen Unknown ; strong. ete | eukatvos | ctibe sod Fe; strong. 66 Sa een, Acree Rela ss ee Fe; strong. (ti at Nr a Reece, AC abate ch Fe; strong. h 2S Sy eee ee H; very strong. lately ascer- tained to be a fourth Hydrogen line. ‘47 Soe thon stegeids “| - aRstbee de Double. g cots SEs 202 ale ieee ec ema es Pay Ca; double line. O34 Se cal Meee ary Cee ee So oe 8 Fe. Ce 10 OND a ee or ee oe Cee Fe. 0 tS a eT een re eee Fe. G 4310+) 18— | 2854.4 Fe.; winged. Fe; winged; broad. H; winged; very broad. Fe; winged; very broad. 44-08 10 2686°4 f Fe; winged. 18 447 2670-0 e Fe. F 4865+; 10+ | 2080-0 g HL; winged. 76—| 19+ | 2066°6 e;5e¢ | Fe; double. D b; 6c | Fe; double. 49:22 + 2007:2 ¢ Fe. 24+ 2 2005-2 d Fe; winged on one side. Fe; with wings of intensity 6. 6 51:72—| 2114 | 1655°6 e Fe; Mg; winged on one side. . { 73+ Fee oneed b Fe; Ni; winged on one side. by 77 4— | 16488 if Me; winged. b; “88 11 16341 g, Mg; winged. ‘96+ 8+ 1622°8 56,5¢ |Fe; double like H. 52°37 46— | 1569-6 5e Fe 70 28 1527-7 5e Fe; Co. . BE, 73+ 3+ | 1523-7 6¢ Fe Tnterval between EH, and RE, 74 1 1522-7 6c Ke, Ca. f E,=1-07 Xth-metres. 87+) 138 1508-6? | 56 Fe. 53°20 33a— | 1473-9 5b Fe. 28 — 8— | 1466°8 be Fe. "32 — + 1463-0 5e,5e | Fe; double line, closer than E. ‘44 12+ 1451°8 56,5c | Ke; double line like H. RN dee et, Vanna cea ea A a ee ie a a c2 20 Mr. G.J. Stoney on the Physical [ Recess that given between iron electrodes from a battery of 50 cells, which gives a far greater number™* of iron lines, and with this apparatus he has been able to observe the enormous number of 460 coincidences. TABLE (continued). bs SS rod S SY se Bol ee ol ee oe Sle ole. | gee oe ee me 5) ag Zs co H Bea g = 2 6 a Be a g s aie = Remarks. Ba ee Ves alee ae) m2 2% ° 4 RRS a ae | ge | Bes | 22S 8 = > 2 Ba =f 8 |S aees 2 3 4 28 HO 2 SOS ee 5 Ss) A 5369+} 25+ | 14282 5b Fe Ti+ 2 1425°4 5d Fe 74+ 3 1423:0 5b Fe 76— 1+ | 1421°5 6e Fe 5408+} 383— | 18909 5d Fe = iZe 1389-4 6e¢ Fe 28+) 19— | 1372°6 5b Fe o4— 5+ | 1367:0 6d Fe 49+; 16— | 1852-7 5b Fe 51 14+ |) 1351-1 5b Fe 54:60 — 9 1343°5 Ge Fe 5o77—| 117 12426 6¢ Fe 91 144+ | 1231°3 5d Fe 99 8 1224-7 5d Ca 56:03 — 4— | 12216 5d Ca. 07 44 1217°8 nd Fe; Ca. ‘20 13 1207.3 5g Fe. Dy 58°94-+| 274+ | 10068 66 Na | Interval between D, and D, D, 5900+ 6 1002°8 66 Naj =6-03Xth-meires. 61:05—| 204+ 894-9 2e Ca. 24—| 19 884-9 4b Ca. Co. ‘89—| 15 877-0 4¢ Fe 435-4 5— 874:3 4d Ba 63+} 20 863-9 5d Ca 7i 8— 860-2 od Ca. 92—| Q1— 849-7 3¢ Fe. a 62:59 OIF ee sie A ras RR Oe ri A strong line caused by the earth’s C 65°68 309 694-1 Ge H; winged. | atmosphere. B 68°75 307 592°7 Ge Winged on one side. A 76:12 737 404-1 6 Winged. In this list two of Angstrém’s rays have been omitted—those to which he assigns the . wave-lengths 1903-4 and 1936:4 VIIIth-inches, which correspond to 51°53—, and 52:42 VITIth-metres; since there are no conspicuous lines in the solar spectrum cor- responding to them, and since, in the case of the latter at least, there is plainly some misprint. If we might conjecture that they ought to have been entered as 1900-4 and 1932°4 eighth-inches, they would correspond to 51-44-+ and 52-31 eighth-metres, and belong to two strong iron rays. | * This appears at variance with the usual law that spectral lines increase in bright- ness with the temperature, inasmuch as the temperature of a Ruhmkorff’s spark is probably very much higher than that from the battery of many cells, We are still too 1868. | Constitution of the Sun and Stars. 21 29. The first thing that strikes the eye in the part of the table appro- priated to the iron lines is a continuous gradation of intensity from the indigo to the red. The most refrangible iron lines mapped by Kirchhoff are those in the indigo, all of which he found of the deepest black, which - he represents by the number 6. Then follow the lines in the blue, in which there appears to be a struggle between this intense blackness, and the darkest shade short of blackness recorded by Kirchhoff, and to which he assigns the number 5. In this part of the spectrum lines of the in- tensity 6 are still predomimant. In the next region, the bluish-green, this struggle is continued, but now with a predominance of lines of the intensity 5. About the middle of the green we for the first time meet with an unexceptionable line of intensity 4, corresponding to the -wave- length 53°87 VIIIth-metres. The last line of intensity 6 presents itself at wave-length 55°77, after which, in the yellow, orange, and red, the in- tensity of iron lines has for the most part sunk to 4 or 3. 30. Now the iron lines seen in the solar spectrum originate in the upper part of the iron atmosphere, each ray coming from a stratum of such a thickness that it is opake for that particular ray. This thickness differs from ray to ray, being greater for those rays which are caused by atomic motions of feeble intensity. Such rays therefore will in part originate from a greater depth in the solar atmosphere, and therefore from a region of greater heat. ‘They will therefore be brighter, or in other words less con- little informed on these subjects to speculate with any confidence on the cause, and _ perhaps the following conjecture is the best that can yet be made. The effect may perhaps be due to the brief duration of the sparks. The enormous temperature caused by each spark lasts for a very short time, and is not renewed until after the lapse of an interval long in comparison. The electricity, when it passes, pro- bably produces its direct effect in accelerating and controlling the directions of the motions cf translation of the molecules of the gas; and only indirectly, through the resulting violence of the molecular collisions, excites those more subtle atomic motions which give out the light. Those of the atomic motions therefore which are most in- fluenced by each collision will be the first to reveal themselves, and the rest not until after very many collisions shall have taken place, so that before they have had time to culminate, the duration of the spark may be over: whereas when they have time fully to unfold themselves, as they can in a continuous current, they may attain in some cases a higher inteusity, and consequently emit a greater brightness. In support of this explanation, we have the fact that the lines seen with Ruhmkorff’s coil have. been observed to correspond to the most conspicuous lines in the solar spectrum. Now those atomic motions which are most developed by a few collisions will usually be those of which the periodic time is most subject to perturbation (see Phil. Mag. 1868, vol. xxxvi. p. 132). They will therefore in such cases give rise to dilated lines in the solar spectrum, and if the circumstances be such as to cause much of the breadth of the line to appear quite black, as for example in many of the iron lines, it will in consequence of its breadth appear much more intense. On the other hand it should be remembered as against our conjecture, that if the Ruhmkorff’s sparks last as long as the measures Wheatstone made of the duration of the spark of a Leyden Jar, viz. four Vth-seconds, the number of collisions which take place during the continuance of a spark must be so great as to take away much from the probability of the explanation. a2 Mr. G.J. Stoney on the Physical [ Recess, spicuous as dark rays. These same rays, since they are due to feeble atomic motions, will, in the iron spectrum produced by artificial means, appear the faintest. Now in all regions of the iron spectrum artificially produced, rays present themselves of every possible degree of intensity ; whereas of those observed by Kirchhoff in the solar spectrum, the fluc- tuation of intensity in any one region of the spectrum seldom exceeds one degree of his numerical scale, and but once exceeds two degrees. This is conclusive evidence that iron isso very abundant in the solar atmosphere as to be opaque for the feeblest of these rays before a depth is reached which is very much hotter than the outer surface of the iron atmosphere. It also shows that the gradation of brightness in the iron lines from the more to the less refrangible parts of the spectrum is not due to the less refran- gible lines coming from profound depths, and being on this account brighter. But the cause is sufficiently obvious. Ifa body of such a kind that it emits the maximum light corresponding to its temperature, be gradually heated, it will first begin to glow with scarlet, orange, yellow, and green rays ; and according as its temperature rises its spectrum will ex- pand in both directions towards the extreme red, and still more towards the violet. If, then, a body heated im a furnace be compared with one at a much higher temperature, the spectrum of the former will every- where be fainter than that of the latter, but not equally so. It may have a considerable brightness in the red and orange rays, and show sensible light mm the green, and at the same time appear in the comparison abso- lutely black at higher refrangibilities. And the same general appearance® would doubtless be found if the maximum spectrum of any one tempera- ture were compared with the maximum spectrum of a higher tempera- turey. Now the upper layer of the iron atmosphere, from which comes all the light that reaches us in the iron lines of the sun’s spectram, is at a vastly lower temperature than the photosphere, but not so cool as to be of insensible brightness through the whole range of the spectrum. It begins to glow sensibly in the green, even in comparison with the intense light of the sun, and renders the iron lines of the green short of absolute blackness. And this effect goes on increasing until it reaches its climax in the orange and red. 31. As molecules of calcium vapour are of a mass less than that of iron ‘molecules, in the ratio of 40 to 56, calcium vapour must reach a far cooler * See § 52. t It is natural to suppose that this steady increase of intensity with the temperature which pervades the whole range of the visible spectrum, should extend beyond it; and we are assured of it by the phenomena of calorescence. Dr. Tyndall succeeded in heating a body so as to be visible by the concentration upon it of rays beyond the red. This would have been impossible,—it would have been at variance with the principles of the exchange of heat, if‘the rays which were brought together were of an intensity that could be emitted by a non-luminous source. Hence the source from which they came (which was in fact a far hotter body whose luminous rays had been intercepted) was able to send forth invisible rays more intense than any non-luminous body could emit. 1868. ] Constitution of the Sun and Stars. 28 region of the solar atmosphere than iron. Nevertheless none* of the calcium lines observed by Kirchhoff appear to be as intense as many of the iron lines. This is no doubt due to calcium vapour being a much smaller constitueut of the sun’s atmosphere than iron, just as oxygen is less abun- dant in our atmosphere than nitrogen, and carbonie acid much less abun-— dant than either. Judging from the indigo and green calcium lines, which are all less intense than the iren lines in their neighbourhood, it would appear that some light reaches us from a hotter region than any light that reaches us from iron lines, and accordingly that calcium gas is so rare, and in consequence the stratum which can intercept and therefore is em- ployed in emitting these rays is so thick that, though its upper surface soars far above the upper surface of the iron atmosphere, its under surface stretches further down than the under surface of the corresponding, and comparatively shallow, active stratum of iron gas. This appears to be the case too with most of the rest of the calcium lines observed by Kirch- hoff; but the lines 55:99 and 56:03 in the yellowish-green, and the lines 61°63, 64°32, and 64°55 in the red, all of which are of intensity 5, are probably exceptions, and owe their strength to calcium gas being much more opake in reference to them, so that they are emitted by a stratum shallow enough to reach but little beyond the extreme verge of the iron atmosphere. These are some of the lines that give the calcium light, when seen undispersed, its beautiful purple colour. Calcium is no doubt very opake also in reference to the other lines of the same class, such as the lines H,, H, and g, beyond the limit of Kirchhoff’s maps. In taking a general review of the calcium spectrum, these lines should be left out of consideration as not being comparable with the rest; and if this be done, the remaining lines will exhibit the same gradation of intensity from the red to the blue which we found in the iron lines. 32. But in the immense extent of atmosphere which spreads upward from the surface of the calcium, in the vast elevation to the boundary of the atmospheres of magnesium and sodium, and in the far greater heights to which hydrogen alone can soar, the temperature has fallen too low to produce light visible in comparison with solar light in any part of the spectrum. And accordingly all the lines referable to magnesium, sodium, or hydrogen, in whatever part of the spectrum they may lie, are in- tensely black. But before proceeding to examine these lines in detail, it will be convenient to inquire into the state of the regions further down. 33. The sun’s atmosphere is heated beneath by contact with the scorch- ing body of the sun, and it would throughout its whole extent attain this * The lines 48°83 and 52-74 of intensity 6, the latter of which is the less re- frangible of the lines constituting the close double line E, are left out of account ; as they are also iron lines, and no doubt owe their intensity to this circumstance. The line 56°07 of intensity 5, which is also a line common to the two spectra, is probably a stronger line on this account than it would be either as a calcium or as an iron line. 24, Mr. G. J. Stoney on the Physical [ Recess, enormous temperature were it not for the escape of heat from it, which is perpetually going on. The first and principal escape of heat takes place from the photosphere, but it is also going on in the form of spectral lines, whether visible or beyond the range of refrangibility that the eye can see, ‘from the upper layer of each gas tbat is successively left behind in ascending through the atmosphere. The last escape of heat is from the hydrogen lines. The stream of heat which passes per second through any spherical shell concentric with the sun into those parts of the atmosphere that lie outside it, is equal to what escapes per second from the latter mto space. This stream therefore remains constant wherever an interval exists between the outer boundary of one gas and the bottom of that upper layer of the next which is thick enough to be opake for the faintest of its spectral lines; but throughout the depth of each such upper stratum the stream of heat is on the decrease. 34. We shall better understand what takes place by considering the agency by which the heat is carried outwards through the solar atmosphere. It is partly by conduction, but principally by what may be called internal radiation, to which are probably to be added in some situations convection and irregular motions such as would result from storms. By conduction IT mean that conduction which is effected by the rectilinear motions of the molecules. It is the only conduction to which experimentalists have found it necessary to attend, since the quantities of transparent gas upon which they operate are not such as to be, in the cool state in which they have examined them, perceptibly opake to any of the incident rays. But when the gas is incandescent and present in enormous quantity, the chief trans- ference of heat through it will be in consequence of what I have called internal radiation, which comes into play whenever the spectral rays emitted by one part of the gas are absorbed by the surrounding parts before they can reach the outer boundary and escape. If the gas be highly opake for any particular ray, which is in general the case of those rays that appear very bright in spectroscope experiments, it will travel but a short distance before it is effectually absorbed; but the rays which are faint in spectro- scope experiments will wander further, and will contribute the most to the rapid carriage of the heat to great distances. It should also be borne in mind that if an extensive gas have a uniform temperature throughout, the rays which at profound depths are dashing about, are all of the maximum brightness corresponding to that temperature; but that if the tempera- ture of the gas be shaded off in one direction, as it is in the solar atmo- | sphere, the rays of internal radiation which are directed outwards at any particular spot are brighter than the maximum brightness corresponding to the temperature of that situation, since they come from warmer regions ; and that those rays will be the brightest which in our experiments would be faint, since they come from the most remote, and, therefore, from the hottest of the parts from which any of the rays arrive. a 35. It will not now appear strange that the region immediately outside 1868. | Constitution of the Sun and Stars. 25 the photosphere should attain an enormous temperature. It is in contact with the luminous clouds, and would on this account alone be brought to as high a temperature as theirs; but, beside this, rays of every refrangi- bility are emitted from the hotter region beneath the clouds of an intensity — corresponding to the far more consuming heat which there prevails. And if out of this terrific heat all the rays be selected which correspond to all the spectral lines of every gas in the solar atmosphere, they will constitute a body of heat, a smali part of which is no doubt spent upon the gauze- like luminous clouds, or absorbed by the intermingled atmosphere, but the bulk of which is poured into the atmosphere overhead. On the other hand the only heat which escapes outwards from this upper atmosphere is the quantity, small in comparison, which is emitted by these same spectral rays at the reduced temperatures which correspond to the dusky lines visible in the solar spectrum, or to similar lines lying beyond the limits we can see*. All the rest of the heat received by the superincumbent atmo- sphere is returned by it downwards, and is the measure of the fervid tem- perature which its lowest stratum attains. Thus the atmosphere above the luminous clouds will begin by waxing in temperature, and continues to grow hotter through that interval to which the heat emitted from beneath can in any abundance directly penetrate. At the limit of this space there will be a surface of maximum temperature, after which the heat will very gradually fade off by reason of the conduction, convection, and internal radiation which feed the escape outwards from the upper layers of the successive atmospheres. 36. It is of importance to observe that if the boundary of any one of the gases that constitute the sun’s atmosphere fall within the stratum which is hotter than the luminous clouds, or very close above it, that gas can only exist in a state of such utter attenuation within the stratum that we can scarce expect to detect any lines in the spectrum corresponding to it. The stratum in question rests upon the luminous clouds beneath, and its upper limit is to be defined as that situation in which the temperature has again fallen to the same point at which it stands in the shell of clouds. At all intermediate stations the temperature is higher, or, in other words, the motions of the molecules of the gases are more active. At the upper and under boundaries of the stratum they are equal; but the pressure, and consequently the density, is somewhat less at the upper station, or, in other words, the molecules of the gases constituting the atmosphere are there a little more separated. Now any gas which comes to an end within the stratum must be unable to maintain itself at the upper surface * We should remember that much of the sun’s heat lies in this direction; for the wayve-lengths of almost all visible vibrations lie between 4 and 8 seventh-metres, and _ the invisible rays beyond the extreme lavender probably do not include waves much less in length than 2 seyenth-metres, while the obscure heat-rays at the other end of the spectrum have been observed to extend, though with decreasing intensity, until the waves are 18 or 20 seventh-metres long, and probably reach much further. 26 Mr. G. J. Stoney on the Physical [ Recess, of the layer, while in the stratum of luminous clouds it is able to hold its ground with equal molecular motions, solely because the molecules are there somewhat nearer together. It must therefore at the lower station be in a state of almost inconceivable rarefaction; and, from the laws of diffusion, its density at any higher point can nowhere go beyond this. It appears, therefore, almost in vain to expect to see bright lines in the solar spectrum. If, however, any such exist*, they will probably be most readily detected in light taken from near the margin of the sun’s disk, where the bright- ness of the region behind the luminous clouds is eut off, and where the thickness of the stratum of attenuated gas which forms the bright lines is increased by the oblique position of the spectator. 37. This rarefaction (which would be carried to an extreme in the case of a gas, if any such exist, which extends into, but not beyond, the stratum that is hotter than the lummous clouds) will also affect in a very consi- derable degree those gases which do not spread far beyond it. Accord- ingly the fainter lines in the solar spectrum either arise from such low- lying gases in a state of great tenuity, in which case those lines only can be visible in reference to which these gases are most opake, which will therefore be the brightest of their artificial spectra; or they arise from constituents of the solar atmosphere which spread into the colder regions above, in-which case they can only be those lines in reference to which these gases are highly transparent—such as are lines 50°48 and 53°52 of the Calcium spectrum, and the lines 49°21 and 51°81 of the Nickel spec- trum. It may perhaps be found that faint lines of this latter class will be seen about equally distinctly in spectra formed of light taken from the centre of the sun’s disk, and in spectra formed of light taken from near its margin. When the light is taken from the centre these lines have the ad- vantage of a brighter background to set them off; when it is taken from the margin they have in their favour the greater depth of Calcium or of Nickel atmosphere which is looked through. But in the ease of those faint lines of the other class which originate in the lower strata of the sun’s * T have several times thought I saw such a line, of wave-length 58°88, between the more refrangible of the lines D and the next line recorded in Kirchhoff’s map to the left, almost in contact with this latter line. The appearance, however, may have arisen from. the adjoining part of the spectrum having been subdued by lines not marked on Kirchhoff’s map, and which a spectroscope of two equilateral flint-glass prisms could not sufficiently make out. I sometimes received the impression that there were such — dim lines, but could not satisfy myself that they accounted for the bright line. Pos- sibly there is also a bright line somewhere between the lines 1025:5 and 1027-7 of Kirchhoff’s scale, and another in the right hand of the two parts into which the space between the lines D is divided by the Nickel line. Although it is on the whole im- probable that the appearances are really due to bright lines, it would perhaps be worth repeating the observations under more favourable circumstances, of which the most important would be to admit only light from the margin of the sun’s disk. If the sus- pected bright line between the lines D should prove real, it is perhaps occasioned by zinc. [For a continuation of this note, see the postscript, p. 57.] 1868. | Constitution of the Sun and Stars. 27 atmosphere, the effect of obliquity will be very much greater; so that we may expect to find these rays most conspicuous in spectra of light from very near the edge of the disk. This appears to account for observations* lately made by Angstrém. 38. Let us now consider the information given to us by the lines of the spectrum which are due to hydrogen, sodium, and magnesium. In the first place the sodium lines are narrow and sharply defined. In both respects they differ from the lines of hydrogen and magnesium, which are broad and winged, that is, shaded off on one or both sides into dusky bands less dark than themselves. Now at and up to the temperature of the flame of a spirit-lamp sodium vapour can give rise to such lines; but at the temperature of a Bunsen’s burner the sodium lines have begun to expand and be ill defined. Hence we learn that in those upper regions of the sun’s sodium atmosphere in which these lines originate, the temperature is lower than that of the flame of a Bunsen’s burner. Nor need we be astonished that this or a much lower temperature can prevail so close to the fierce heat of the photosphere, when we take into account how effectu- ally the outer parts of the sun’s atmosphere are screened from the glare beneath by the stoppage in the intermediate regions of almost every ray that could act upon them. 39. The absence of wings to the lines D indicatest to us that there is not in the sun’s atmosphere enough of sodium vapour of temperatures inter. mediate between the temperature of a Bunsen’s burner and the temperature of the photosphere to be in a sensible degree opake to the wings of the rays which it emits. This both shows what a mere trace of sodium is diffused through the solar atmosphere, and also to what a vast height it rises as com- pared with the thickness of that part of the solar atmosphere which ranges in temperature between a temperature below that of a Bunsen’s flame, and a temperature comparable with the intense heat of the photosphere. In fact, the atmosphere of sodium, owing to the small mass of its molecules, which is less than half the mass of molecules of iron, must spread to a vast distance beyond the iron atmosphere; and through this immense space the temperature appears to vary very slowly, and to be nowhere high. 40. The outward stream of heat which reaches the upper layer of the iron atmosphere for the most part escapes into space from that neighbour- hood through the numberless lines of iron, calcium, chroniuin, manganese, and through the darker of the lines of nickel and cobalt, all of which * See Comptes Rendus of October 15, 1866, or Philosophical Magazine of January 1867. It would be very desirable to have observations made upon spectra of light taken from different parts of the sun’s disk, brought one over the other into the same field. is + [I remain unsatisfied with part of this discussion of the absence of sodium wings. There is something in the limitation of the wings of the rays of this and of some other gases, especially of hydrogen, of which I do not see the explanation.—September 1868. | 28 Mr. G. J. Stoney on the Physical [ Recess, drain off heat from this region. No heat passes beyond, except the small quantity necessary to keep up the feeble escape from the lines of hydrogen, sodium, and magnesium, and others of the same class, such as B, A, &c., which are not only of a lower temperature, but are also few in number, if we may deem those that fall within the visible part of the spectrum a sufficient sample of the whole. Since, then, there is so much greater an escape of heat from the upper layer of the iron atmosphere than from the regions outside, there will exist a surface of minimum temperature near the limit of the iron, beyond which there will be first a very slight recovery and then a gradual fading off of the temperature. The observations of the sodium lines indicate that this surface of minimum temperature which lies near the outer boundary of the layer from which iron lines originate, can- not be as hot as the flame of a Bunsen’s burner. 41. Within the iron atmosphere, on the other hand, there is a rapid stream of heat directed outwards to supply the outpourings from near the boundary of the iron atmosphere, as well as what is feebly dispersed by lines such as those of hydrogen, sodium, and magnesium. Still further down the stream becomes a torrent, as it has there to supply also the lavish expenditure of heat by the multitude of lines more faint than the iron lines, which are not only more numerous than lines of an intensity comparable with the iron lines, but also each one of which discharges into space a flood of heat proportioned to its exalted temperature, or, in other words, to its faintness as a line in the spectrum. All this leads us to con- clude not only that the temperature increases very rapidly within the iron atmosphere, but that the rate of this increase becomes more and more pre- cipitate as we descend. And this is in exact accordance with the intelli- gence brought to us by the sodium lines, which, from being wingless, indi- cate that the interval from the surface of the iron to the region where the temperature first becomes comparable with that of the photosphere, is both intensely hotter, and of trifling extent when compared with the vast expanse from the surface of the iron up to the surface of the sodium atmosphere. 42. Molecules of magnesium have very nearly the same mass as mole- cules of sodium. The two gases therefore rise to nearly the same height in the solar atmosphere. Nevertheless the lines in the spectrum due to magnesium present a very different aspect from those of sodium, into which we must now ‘inquire. ‘The lines of sodium are narrow and sharp; those of magnesium broad and fringed, the borders being of the intensity that — Kirchhoff represents by the number 4. Now, the iron lines in their neigh- bourhood are of intensities 5 and 6, which shows that the upper layer of iron in which the iron lines take their rise may be distinguished into two strata, the outer of which produces in that part of the spectrum lines of intensity 6, while both together produce lines of intensity 5. To produce a line of intensity 4, a third stratum below the layer in which iron lines originate must be in action. Light reaches us from this third stratum in 1868. | Constitution of the Sun and Stars. oD 9 the wings of the magnesium lines ; and in fact the black part of the mag- nesium lines is due exclusively to the magnesium vapours between the top of the magnesium atmosphere and the plane of demarcation between the two strata into which we have distinguished the active layer of iron, while the wings are caused, at least in part, by the magnesium vapour which © exists in the lower section of the active layer of iron and in the stratum which immediately adjoins it bencath. Thus the layer of magnesium which gives rise to the lines of the group 6 may conveniently be distin- guished into two parts, the outer of which extends from the remote boun- dary of the magnesium atmosphere to the middle of the layer from which iron lines originate, and the second from this latter station through a hotter layer which lies further down. If magnesium vapour existed in the situation of this lower moiety only, the magnesium lines would be bands of their present breadth, but nowhere attaining the intensity 6: the super- position of the central black stripe is the work of the magnesium vapour in the vast outer section. 43. When we take into account how much higher a specific opacity sodium and magnesium vapour have than iron for the principal rays which they respectively emit, we are led to conclude that while magnesium va- pour is abundant when compared with the attenuated vestige of sodium in the sun’s atmosphere, it may be but sparingly present when compared with such a constituent as iron; and that this is so is established by the absence from the sun’s spectrum of any lines corresponding to the rays of magne- sium, in reference to which the specific opacity of magnesium is low, such as the magnesium lines 44:92 and 46°06. 44. We have found that there is but the merest trace of sodium in the sun’s atmosphere, and that this trace mounts to an immense height above theiron. To render this possible there must be some abundant gas which extends as far as or beyond the sodium, in which it may diffuse itself, and so be borne to the full height corresponding to the small mass of its mole- cules. The gas which does it this service appears to be hydrogen, which, having a molecular mass only one twenty-third of that of sodium, must soar to an almost inconceivably greater height. Hydrogen seems to be a very large constituent of the sun’s atmosphere. There are three considerable rays in the spectrum of incandescent hydro- gen, and a fourth faint one has been lately pointed out by Angstrom. To these four rays, even to the faintest, there correspond intensely black lines in the solar spectrum. This indicates an abundance of hydrogen. , The wave-lengths of the four lines are 41°04, the new hydrogen line, Ang- strém’s A, in the violet ; 43°43, in the indigo, which is the second of the six very conspicuous lines seen in the sun’s spectrum on the less refrangi- ble side of G; 48°65 in the blue, which is Fraunhofer’s F ; and 65°68 in the red, which is Fraunhofer’s C. All these lines are winged: the black stripe in the more refrangible lines is very broad, and in the others it is of considerable width. These circumstances also indicate an abundance 30 Mr. G. J. Stoney on the Physical [Recess, of hydrogen. The temperature of the sun’s atmosphere above the surface of the iron is too low to dilate hydrogen lines. The breadth, therefore, of the black part of the hydrogen lines must be due to the quantity of this element which is to be found in the interval between the outer boundary of the iron and that situation in which the temperature first becomes too high to appear black when projected against the brightness of the photosphere. This interval is small in the part of the spectrum where the line C occurs ; at the line F it extends through a considerable part of the thickness of the layer that gives out iron lines; at the hydrogen line near G it extends quite through this layer; and in the situation of the fourth hydrogen line it extends much further down. But even in the least of these intervals there is enough of hydrogen to give a very sensible breadth to the line C. This quantity must be very considerable ; as also must the quantity which can produce, in the hotter regions below, the fringes which border all the hydrogen lines. To recapitulate,—the width of the hydrogen lines, the wings that fringe them, the intense line in the sun’s spectrum which corresponds to a faint hydrogen ray, and the height to which hydrogen can support traces of other gases, and more especially the vestige of sodium in the solar atmosphere, all testify to the abundance of this element. : 45. The sodium lines D are an open channel through which heat is poured from avery hot region into that immense upper expanse of the sun’s atmosphere which is tenanted by sodium, magnesium, and hydrogen alone. This is not the case with the magnesium lines of the group 4, nor with the four hydrogen lines. ‘These all stop heat before it has travelled to any great distance, by reason of the great abundance of hydrogen, and by reason of the specific opacity of magnesium for the rays 6, and its quantity, which, though small, is immeasurably greater than the quantity of sodium. And on a different account, the same-may be true of the faint rays of the spectra of sodium and magnesium. Two such mag- nesium rays were observed by Kirchhoff of wave-lengths 44:92 and 46:06; and Huggins has recorded three faint pairs of sodium lines, of wave-lengths 51°6, 56°9, and 61:6, and a nebulous band at 49°9. It is not yet fully ascertained whether there are lines in the solar spectrum answering to any of these rays. If there are such lines, they are faint. Now, if it shall prove that no such lines can be detected, it will indicate that heat from beneath of these wave-lengths passes without sensible diminution through the cool parts of the sun’s atmosphere and therefore does not heat them; - and if it be found that they give rise to faint lines, this faintness is to be attributed to but little of the heat despatched from hot regions being en- tangled in its passage outwards. Similarly the heat which is so trans- mitted through the wings of conspicuous lines crosses with little obstrue- tion the colder regions above ; since at the temperatures that there prevail few of the periodic times of the atomic orbits deviate sufficiently from those central periodic times which correspond to the middles of the lines. 1868. ] Constitution of the Sun and Stars. 31 _ 46. But of whatever kind these or other vehicles for the conveyance of heat beyond the atmospheres of calcium and iron may be, it is certain that no sodium or magnesium rays can carry heat beyond the limits of the so- dium atmosphere. It is also certain that the heat borne outwards is un- able to maintain beyond the iron atmosphere a temperature as high as ~ that of a Bunsen’s burner, and that, after passing a situation but little out- side the iron, the temperature falls off from this maximum. It must have sunk very low where the next considerable escape of heat takes place —at the boundaries of the atmospheres of magnesium and sodium. Ac- cordingly, we must regard the hydrogen in that still higher dreary waste which is tenanted by hydrogen alone, asa feebly conducting body, of im- mense depth, warmed but moderately beneath, and exposed on the outside to a chilling radiation towards the open sky. Its outer strata must be in- tensely cold. 47. The case of a comet consisting of a gas * not found in the solar at- mosphere is altogether different. Asit approaches the sun itis exposed to the full unveiled glare of the photosphere, and absorbs the heat of those wave-lengths which correspond to the lines of its spectrum. However small a part of the incident heat this may be, it may make the comet nearly as hot as an opake body would become ; since the comet can lose by radiation no heat except through these same spectral rays. 48. Having now examined in detail the lines of hydrogen, sodium, magnesium, calcium, and iron, we may treat in a more cursory manner the other elements that have been observed in the sun’s atmosphere. Chro- mium, nickel, cobalt, copper, and zinc enter in small quantities into the * Tf, indeed, a comet consist of gas, which, perhaps, we ought to deem ‘highly im- probable. The molecules of a gas pass most of their time beyond the reach of one another’s molecular action, and, unless further confined by a sufficient force of gravity, would each pursue an independent orbit of its own. ‘They would therefore tend gra- dually to extend like a stream of meteors along their common path; for the orbits being slightly different would have slightly different periodic times, which in the lapse of ages would operate in this way. It does not appear likely that the gravity of a body so large, and with so smail a mass as a comet, could successfully withstand this ten- dency. But if the comet were kept together by a molecular cohesion, somewhat like a solid, there would be no such difficulty. Nor is it necessary to suppose that this solid, if such we are to call it, would retain this constitution when subjected to an intense gravity like the earth’s: the hardest Archangel pitch flattens down under its own weight, and in time adapts itself to its containing vessel. The matter of comets may on our earth be gas. And, again, it seems improbable that a comet can have been raised to the temperature of ignition at the distance from the sun that the earth is; yet this was the distance of Tempel’s comet when its nucleus was seen by Mr. Huggins to emit a spectral ray. The only bodies we know to have the property of glowing at low temperatures are phospho- rescent bodies; and we know from Becquerel’s observations that the spectra of phospho- rescent solids consist of bands, in some cases narrow. The comz of comets cannot be transparent gas, since transparent gas would not be conspicuous by reflected light. The phenomena of tails, too, suggest some entirely peculiar constitution. 4 Mr.G. J. Stoney on the Physical [ Recess, composition of the sun’s atmosphere. Probably nickel is the most abun- dant of them. Of the others no lines appear in the sun’s spectrum, except those in reference to which they have a high specific opacity, in many eases higher than that which iron has for any of its rays. There are, therefore, but traces of them present; and the appearance of the lines agrees well with the situation in the sun’s atmosphere assigned to them by the masses of their molecules: chromium, projecting quite through the iron atmosphere, produces a few lines of an intensity comparable with that of the iron lines in their neighbourhood; and the boundaries of cobalt, nickel, copper, and zinc, appear to lie within that upper layer of iron which sends forth iron lines. 49. The appearance of the zinc lines is not incompatible with this element’s having the vapour-density usually supposed by chemists, viz., 32°5 instead of 65; but the evidence of the sun’s spectrum, such as it is, for it is scanty, owing to the paucity of the lmes, seems to lean against this hypothesis, unless a similar reduction is to be made in the case of -all the other metals of the atmosphere. But whatever uncertainty may rest on this point, there is at least no doubt that barium cannot have a vapour- density anything like so high as 137. At most it cannot exceed half that number, which would barely raise the boundary of the barium atmosphere within the lower part of the layer from which iron lines proceed ; and, if it were not for objections on chemical grounds, the strength of such lines as the barium lines 45°66, 49°37, and 61°43 would prompt us to suspect for the vapour of barium even a lower density. But the strength of these lines is probably due to the remarkably high specific opacity of the vapour of barium in reference to them. There is plainly only a small amount of barium in the sun’s atmosphere. 50. It will readily be perceived that it is vain to look for the cause of any conspicuous line mapped by Kirchhoff, in any substance with a vapour- density more than 70 times that of hydrogen. This narrows very much the field in which to search for the origin of the darker of the Imes enume- rated in Table III., opposite, the table of unappropriated lines. Many of these, as, for example, three of the five lines of the group at 60-3, are probably due to manganese, and may be removed from this table, as soon as a list of the thirty manganese lines, lately identificd by Angstrém, shall have been published. Others of them are probably some of the 460 iron lines, produced by a continuous electrical current, or among the additional lines which may be produced under like circumstances in others of the | elements which we have been heretofore examining. When all these are eliminated it does not seem likely that many conspicuous lines between G and B will remain to be traced to their source. Carbon is probably as devoid of volatility as it is infusible; or at all events the one probably bears Some proportion to the extraordinary eminence of the other. If this be so, it cannot be a gas at the temperature of the situations from which dark lines come, or at least not in sufficient quantity to produce visible effect. [Zo face p. 32. rt ~ fo} 0} =| om | pe =>) for 0) S gh) Nn om n=} or o mM fod Crimson. 68 69 70 ced ‘ oo S| |S | | | | um is not given in Kir chho : 5555555644 L ae 1214000 or next after it. re that was afterwards taken. e Tays n the spectra of Green. gases; distinguishing the intensi (eh Bo 65 66 67 68 69 | cre Colours....--+-+++ Indigo. Standard rays .. G. 3 Wave-lengths in eighth-metres .....- 43 44 45 46 47 I x Hydrogen 1 .....-..ss+sesssereeresneseres (9 Bas th orcces Seat ERG | Sock sc svvea || ucwesces |) (veccsescvescercavenctace” | mornin enectasenssnn, ['0 desseuncbuanaameaenocuecetencers axel ll (gee aRivanusbrancnsaapvacerths 66566655 |5556665 |] 5555555555644 | 556445655564 | 4645 (Mg)(Ni) (Co) (Ca) Wii 5438 | 288354461 | wren NO Liga ae Totalu( 1027 622- = 5474 See eclipses yy) AvG3 Bd~ 4g eee t-* 2-10 » 0 at rose 10°84 2: 300k 3 eee 5 2-52 39:8-4.,) 4 8 It thus appears that the thermometer fell from 91° to 85° as the moon was covering the sun, and that it rose from 85° to 96° as the sun was re- appearing. The wet-bulb thermometer fell from 80°-5 to 83° at the total eclipse, and rose to 89° at the termination of the whole eclipse. Ten minutes before the total eclipse there seemed to be a luminous crescent reflected upon the dark body of the moon*. In another minute a long beam of light, pale and quite straight, the rays diverging at a small angle, shot out from the westerly corner of the sun’s crescent. At the same time Mr. Ellis noticed a corresponding dark band, or shadow, shooting down from the east corner of the crescent (fig. 2). At this time the sea assumed a darker aspect, and a well-defined green band was seen distinctly around the horizon. The temperature had fallen * See note at the end. 1868. ] Total Eclipse of the Sun. 85 and the wind had slightly freshened. The darkness then came on with — great rapidity. The sensation was as if a thunderstorm was just about to break, and one was startled on looking up to see not a single cloud over- head. ‘The birds, after flying very low, disappeared altogether. The_ dragonflies and butterflies disappeared, and the large drone-like flies all collected on the ceiling of the tent and remained at rest. The crickets and Cicadse in the jungle began to sound ; and some birds, not visible, also began to twitter in the jungle. The sea grew darker, and immediately before the total obscuration the horizon could not be seen. The line of round white clouds that lay near the horizon changed their colour and aspect with great rapidity. As the obscuration took place they all became of a dark purple, heavy looking, and with sharply defined edges ; they then presented the appearance of clouds close to the horizon after sunset. It seemed as if the sun had set at the four points of the horizon. | The sky was of a dark leaden blue, and the trees looked almost black. The faces of the observers looked dark, but not pallid or unnatural. The moment of maximum darkness seemed to be immediately before the total obscuration; for a few seconds nothing could be seen except objects quite close to the observers. Suddenly, there burst forth a luminous ring around the moon. This ring was composed of a multitude of rays, quite irregular in length and in direction ; from the upper and lower parts they extended in bands to a distance more than twice the diameter of the sun. Other bands appeared to fall towards one side; but in this there was no regularity, for bands near them fell away apparently towards the other side. When I called attention to this, Lieut. Ray said, “ Yes, I see them; they are like horses’ tails ;*° and they certainly resembled masses of luminous hair in complete disorder. I have said these bands appeared to fall to one side; but I do not mean that they actually fell or moved in any way during the observation. If the atmosphere had not been perfectly clear, it is possible that the appear- ance they presented would lead to the supposition that they moved; but no optical delusion of the kind was possible under the circumstances. During the second when the sun was disappearing, the edge of the luminous crescent became broken up into numerous points of light. The moment these were gone, the rays I have just mentioned shot forth, and at the same time we noticed the sudden appearance of the rose-coloured protuberances. The first of these was about one-sixth of the sun’s diameter in length, and about one-twenty-fourth part of the sun’s diameter in breadth. It all appeared at the same instant, as if a veil had suddenly melted away from before it. 86 Governor Hennessy’s Observations on the _{ Recess, It seemed to be a tower of rose-coloured clouds. The colour was most beautiful—more beautiful than any rose-colour I ever saw; indeed I know of no natural object or colour to which it can be, with justice, com- pared. Though one has to describe it as rose-coloured, yet in truth it was very different from any colour or tint I ever saw before. This protuberance extended from the right of the upper limb, and was visible for six minutes. In five seconds after this was visible, a much broader and shorter pro- tuberance appeared at the left side of the upper limb. This seemed to be composed of two united together. In colour and aspect it exactly re- sembled the long one. This second protuberance gradually sank down as the sun continued to fall behind the moon, and in three minutes it had disappeared altogether. A few seconds after it had sunk down there appeared at the lower cor- responding limb (the right inferior corner) a similar protuberance, which grew out as the eclipse proceeded. This also seemed to be a double pro- tuberance, and in size and shape very much resembled the second one; that is, its breadth very much exceeded its height. In colour, however, this differed from either of the former ones. Its left edge was a bright blue, like a brilliant sapphire with light thrown upon it; next to that was the so-called rose-colour, and, at the right corner, a sparkling ruby tint. This beautiful protuberance advanced at the same rate that the sun had moved all along, when suddenly it seemed to spread towards the left, until it ran around one-fourth of the circle, making a long ridge of the rose- coloured masses. As this happened, the blue shade disappeared. In about twelve seconds the whole of this ridge vanished, and gave place to a rough edge of brilliant white light, and in another second the sun had burst forth again. In the meantime the long, rose-coloured protuberance on the upper right limb had remained visible; and though it seemed to be sinking into the moon, it did not disappear altogether until the lower ridge had been formed and had been visible for two seconds. This long protuberance was quite visible to the naked eye, but its colour could not be detected except through the telescope. To the naked eye it simply appeared as a little tower of white light standing on the dark edge of the moon. The lower protuberance appeared to the naked eye to be a notch of light in the dark edge of the moon—not a protuberance, but an indentation. In shape the long protuberance resembled a goat’s horn. As J have not time to attempt an elaborate drawing of these objects, I content myself with inclosing to your Lordship two pages from my rough note-book, showing the sketches taken at the moment. Though the darkness was by no means so great as I had expected, I was 1868. } Total Eclipse of the Sun. 87 unable to mark the protuberances in my note-book without the aid of a lantern, which the sailors lit when the eclipse became total. Fig. 3. Fig. 4. Rose ae X% Jr» oe \Rose OF Rese Blue Those who were looking out for stars counted nine visible to the naked eye. One planet (Venus?) was very brilliant. Its altitude at 1" 31™ U* was 30° 32’ (Carey’s Government Sextant, no error), and its distance from the nearest limb of the moon was 37° 28’. The altitude of the lower limb of the moon at 17 32™ 0° was 66° 30’. On board the ‘ Rifleman’ the fowls and pigeons went to roost, but the cattle showed no signs of uneasiness ; they were lying down at the time. Whatever interest the foregoing observations may have for men of science, I am happy to be able to report that Capt. Reed has added to his public services by seizing this opportunity for determining the exact lon- gitude of Barram Point. Navigators have long been anxious to fix the precise longitude of some point along the coast of Borneo, and the event of yesterday has probably accomplished this. When Capt. Reed’s calculations have been finally re- duced, he will, no doubt, communicate them to the head of his depart- ment ; and in the meantime he has kindly undertaken to place in a cover, directed to your Lordship, the true time as worked out from the observa- tions, so that the times given in this despatch may be corrected before the despatch is used. The time given in this despaten was taken from one of Parkinson and Frodsham’s Government pocket chronometers, No. 1887. As I believe we were the nearest group of observers to the Equator, and as the other conditions were unusually favourable for our work, I venture to hope that even the inadequate and very unscientific account I have 88 Governor Hennessy’s Observations on the [ Recess, given may prove to be of some interest to your honey and to the men of science in England. Before closing my despatch I received from Capt. Reed the error of the chronometer-watch used for taking the time. It was fast on the mean time at Barram Point 0° 4™ 8°:7 I have the honour to be, My Lord, Your Lordship’s most obedient humble Servant, (Signed) J. Pope HENNESsy, Governor of Labuan, and Consul-General in the Island of Borneo. To the Right Honourable Lord Stanley, M.P., Secretary of State for Foreign Affairs. [ Note.—The phenomenon of the sun’s crescent refiected on to the disk of the moon would seem to have been something accidental, perhaps (if seen by the writer only) a mere ghost, depending on a double reflection between the glasses of his instrument. The figure represents the “reflected” image as in the same position as the crescent itself, not reversed, indicating either a refraction or a double reflection. The slender beams of light or shade shooting out from the horns of the crescent would seem to admit of easy explanation, supposing them to have been of the nature of sunbeams, depending upon the illumination of the atmosphere of the earth by the sun’srays. ‘The perfect shadow, or uméra, would be a cone circumscribing both sun and moon, and having its vertex far below the observer’s horizon. Within this cone there would be no illumination of the atmosphere, but outside it a portion of the sun’s rays would be scattered in their progress through the air, giving rise to a faint illumination. When the total phase drew near, the nearer surface of the shadow would be at no great distance from the observer; the further surface would be remote. Attend in the first instance to some one plane passing through the eye and cutting the shadow transversely, and in this plane draw a straight line through the eye, touching the section of the cone which bounds the shadow; and then imagine ether lines drawn through the eye a little inside and outside this. In the former case the greater part of the line, while it lay within the lower regions of the atmo- sphere, would be in shadow, the only part in sunshine being that reaching from the eye to the nearer surface of the shadow ; but in the latter case the line would be in sunshine all along. In the direction of the former line, therefore, there would be but little illumination arising from scattered light, while in the direction of the latter the illumination would, com- paratively speaking, be considerable. In crossing the tangent there would be a rapid change of illumination. Now pass on to three dimensions. Instead of a tangent line we shall have a tangent plane, and there will 1868. ] - Total Eclipse of the Sun. 89 of course be two such planes, touching the two sides of the cone respec- tively. Hach of these will be projected on the visual sphere into a great circle, acommon tangent to the two small circles, which are the projections of the sun and moon. Im crossing either of these there will be a rapid. change of illumination (feeble though it be at best) which will be noticed. According as the observer mentally regards darkness as the rule and illumi- nation as the feature, or illumination as the rule and darkness as the feature, he will describe what he sees as a beam or a shadow. The direction of these beams or shadows given by theory, as just explained, agrees very well with the drawing sent = Governor Hennessy, which dines not represent the left-hand Bani so distinctly divided as it appears’ in the woodcut. The times mentioned in the above despatch have not been corrected for the error of the chroncmeter-watch. In the following Tables, furnished by Staff Commander Reed, the corrected mean times alone are printed. The observations of time by Capt. Reed, Mr. Ray, and Mr. Doorly were made by Government pocket chronometer No. 1887, which was fast on mean time of place 0" 4" 8*-7; those by Mr. Ellis by a gold pocket watch, com- pensation balance, which was fast on mean time of place 0° 17” 2°7 those belonging to the meteorological observations with a pocket sonal which was fast on mean time of place 6" 2™ 47°-9. G. G. SToxes. |] Meteorological Observations taken on board H.M.S. ‘Rifleman,’ at Barram Point, during the Total Eclipse of the Sun, August 18th, 1868. | Mean of | Dry thermo- | Wet thermo- | Retaidtinc at Marine baro-| two ther- | meter hung in| meter hung in ahi 1 meter in | mometers | the main rig- | the main rig- re Chart-house. | in Chart- | ging exposed | ging exposed. | house. to the sun. | to the sun. feo om +s in. ° peer. F273 29°98 81 ° ° Eo ee eae 30°01 | 81 92 93°5 57. 12% 30°00 85 86°5 33°5 10 57 i211 29°99 84 gI 87 aE. SZ .F2*! 29°98 85 88 85 P.M. ChisSS. 122 29°96 85 gt 38 O 42 I2°1 29°96 85 go 37 os57) eat 29°94 $5 38 86 He eka) {Ee E 29°93 85 37 85 Tyee een? we 29°92 85 85 83 wp get 327% 29°92 85 35 33 1 me ae 29°91 35 gI $5 Fog ane ly ales ag 29°91 35 96 go Beha ¥S-K 29°91 86 9G." 89 Jno. W. Resp, Staff Commander in charge of China Sea Survey. | 90 Governor Hennessy on the Total Eclipse of the Sun. [Recess, Observations of the Total Eclipse of the Sun, August 18th, 1868. HLM.LS. ‘Rifleman, Barram Point. Mean Time at Place. Phenomena observed. First contact of moon with sun’s) hh m s |h m sg hm °s83 hi m 8s Nima eee see att Blea es emetate eer ah eee It 56 o7'1 Contact of moon’s limb with pen- umMbraOhINOs TISpOl sea reetee ns IZ 20 10°8 |12 20 I1°5 Contact of moon’s limb with left of INO: SPOb se tacos seaerecs cane Meecha 12 21 16°3 |12 21 /16°8|\E2 2a age Contact of moon’s limb with right) OL INOS SI SPOLt vies dancers neces I2 22 49°3 |12 22 49°3 |I2 22 493 Contact of moon’s limb with sun’s CONC s)s oc. enw ansscie keine aes sen eee eRe ee I2 40 063 Contact of moon’s limb with centre | Of INO: 2 SpObsrtite-- eo teat ates 1 06 38°8| 1 06 38°83} £ 06 433 Contact of moon’s limb with No. 3 Spot (double) e vwcvsnseceoe-eeeeeee I 03 58°9") 1. 14 57 -gae ae : Contact of moon’s limb with No. 4 ae the a SINOI. Socosmass guact Joao Secaaabos odes I 2C 09°3 Sun totally obscured <2-5..422-2- 20.5 T.23 13°39) 1 23 99239 eee Rose-coloured mass left side ee CALCO" ©. .f2 cc ereeeee esac pene ene E25 30-4 Altitude of planet Venus 30° 32’ (Carey’s Govt. sextant, no error)...| ...........5 1 200558 Planet Venus distant from nearest hima bso lL mMOOnEs 7icg2 Oe catenins cee Ieeceecana oe: I 2750138 Rose-coloured protuberance appeared) Delo We aiigeeheiviacoces anoetes montac seers T27- 5U'3 | ckatevccsce ek ees Altitude of lower limb of moon 66° BO ai wdc aoe eee a ceeeeaeh ae eta I 27 5153 First appearance of sun’s limbf...... I 29 25°3 |-E 29-2573 e2zonsoe No. 1 spot reappeared (centre) ...... | Ee caeepe eee E37 038 Venus disappeared from view......... 207 36:3 No. 2 spot reappeared (centre) ...... sssecvessees | 2 29.0573 [2 i2Q tage atEEagmO eos No. 3 spot (double) reappeared (GEGEN Boe) Var re elie RA re EM ecg ta eae an 235 39°3 | 2 "35 vaeed No. 4 spot (double) reappeared MCCDLES) I. .neteeceene omen tascatacen. ca). Posaamarenee 2 43 583 Gast contact of Nmibs ac. sce2 3. se0<-1 |p boserncesa ss 2 48 311} 2 43.92 onae ar I Jno. W. REED, Staff Commander in charge of China Sea Survey. Remarks,—11® 0™ a.m., wind W.S.W. 2 b. c., a hazy appearance about the horizon. * Accompanied by a figure representing the sun touching the moon on the upper right, the line joining the centres being inclined about 45° to the vertical. t Accompanied by a figure representing the sun as emerging vertically beneath the moon. { Accompanied by a figure representing the sun touching the moon on the lower right, the line joining the centres being inclined about 45° to the vertical. — 1868.] Prof. Nordenskidld on the Swedish Arctic Expedition. 91 VII. “Further particulars of the Swedish Arctic Expedition, in a Letter addressed to the President, by Prof. NorpENsKIOLD.” Communicated by the President. Received October 15, 1868. Kobbe Bay, Sept. 16th, 1868. Sir,—In my last letter from Stockholm I promised to send you, with the returning naturalists, a detailed relation of the first scientific part of the Swedish Arctic Expedition of 1868; but unfortunately our last coal- ship, with which five of our fellow travellers, with the rich geological, zoological, and botanical collections, made during this season in the arctic regions, return to Tromso, and which gives us the last occasion of com- municating with Europe, leaves this harbour 7x some hours, and that makes it impossible for me to keep my promise. However, a detailed report will immediately be sent to you by one of the returning naturalists, Dr. Malmgren, a member also of the expeditions of 1861 and 1864. The remaining part of our expedition will from here go, first, to Seven Island, and then (perhaps one of the first days of October), after having depo- sited a boat and a depot of provisions on Ross Islet, further northward. The polar sea was in the end of August quite covered with ice north of 81° 9’, the highest latitude hitherto reached by our steamer. But a week later the sea was open to Walden and Table Island, and the 8th of September I could, from one of the highest peaks of Parry Island, dis- cern only traces of ice further northward. I remain, Sir, respectfully yours, A. I. NoRDENSKIOLD. VIII. “ Notice of an Observation of the Spectrum of a Solar Pro- minence, by J. N. Lockyer, lisq., in a Letter to the Secre- tary.” Communicated by Dr. SuHarrry. Received October 21, 1868. October 20, 1868. Sir,—lI beg to anticipate a more detailed communication by informing you that, after a number of failures, which made the attempt seem hope- less, I have this morning perfectly succeeded in obtaining and observing part of the spectrum of a solar prominence. Asa result I have established the existence of three bright lines in the following positions :— I. Absolutely coincident with C. II. Nearly coincident with F. III. Near D. The third line (the one near D) is more refrangible than the more re- frangible of the two darkest lines by eight or nine degrees of Kirchhoff’s 92 Prof. Tyndall on a New Series of _ [Recess, scale. I cannot speak with exactness, as this part of the spectrum re- quires remapping. I have evidence that the prominence was a very fine one. The instrument employed is the solar spectroscope, the funds for the construction of which were supplied by the Government-Grant Committee. It is to be regretted that its construction has been so long deiayed. I have &e., J. Norman Locxyer. The Secretary of the Royal Society. IX. “On a New Series of Chemical Reactions produced by Light.” By Joun Tynpatz, LL.D., F.R.S., &. Received October 24, 1868. I ask permission of the Royal Society to draw the attention of che- mists to a form or method of experiment which, though obvious, is, I am informed, unknown, and which, [ doubt not, will in their hands become a new experimental power. It consists in subjecting the vapours of volatile liquids to the action of concentrated sunlight, or to the con- centrated beam of the electric light. Action of the Electric Light. A glass tube 2°8 feet long and of 2°5 inches internal diameter, frequently employed in my researches on radiant heat, was supported horizontally. At one end of it was placed an electric Jamp, the height and position of both being so arranged that the axis of the glass tube and that of the parallel beam issuing from the lamp were coincident. The tube in the first experi- ments was closed by plates of rock-salt, and subsequently by piates of glass. | As on former occasions, for the sake of distinction, I will call this tube the experimental tube. The experimental tube was connected with an air-pump, and also with a series of drying and other tubes used for the purification of the air. A number of test-tubes (I suppose I have used fifty of them in all) were converted into Woulfe’s flasks. Each of them was stopped by a cork through which passed two glass tubes: one of these tubes (a) ended immediately below the cork, while the other (4) descended to the bottom of the flask, being drawn out at its lower end to an orifice about 0°03 of an inch in dia- meter. It was found necessary to coat the cork carefully with cement. The little flask thus formed was partially filled with the liquid whose vapour was to be examined; it was then introduced into the path of the purified current of air. The experimental tube being exhausted, and the cock which cut off the supply of purified air being cautiously turned on, the air entered the flask 1868. ] Chemical Reactions produced by Light. 93 through the tube 6, and escaped by the small orifice at the lower end of 6 into the liquid. Through this it bubbled, loading itself with vapour, after which the mixed air and vapour, passing from the flask by the tube a, entered the experimental tube, where they were subjected to the action of light. The power of the electric beam to reveal the existence of anything within the experimental tube, or the impurities of the tube itself, is extraordinary. When the experiment is made in a darkened room, a tube which in ordi- nary daylight appears absolutely clean is often shown by the present mode of examination to be exceedingly filthy. The following are some of the results obtained with this arrange- ment :— Nitrite of amyl (boiling-point 91° to 96° C.).—The vapour of this liquid was in the first instance permitted to enter the experimental tube while the beam from the electric lamp was passing through it. Curious clouds were observed to form near the place cf entry, which were afterwards whirled through the tube. The tube being again exhausted, the mixed air and vapour were allowed to enter it in the dark. The slightly convergent beam of the electric light was then sent through the tube from end to end. For a moment the tube was optically empty, nothing whatever was seen within it; but before a second had elapsed a shower of liquid spherules was precipitated on the beam, thus generating a cloud within the tube. This cloud became denser as the light continued to act, showing at some places a vivid iri- descence. The beam of the electric lamp was now converged so as to form within the tube, between its end and the focus, a cone of rays about eight inches long. The tube was cleansed and again filled in darkness. When the light was sent through it, the precipitation upon the beam was so rapid and intense that the cone, which a moment before was invisible, flashed suddenly forth like a solid luminous spear. The effect was the same when the air and vapour were allowed to enter the tube in diffuse daylight. The cloud, however, which shone with such extraordinary radiance under the electric beam, was invisible in the ordinary light of the laboratory. The quantity of mixed air and vapour within the experimental tube could of course be regulated at pleasure. The rapidity of the action diminished with the attenuation of the vapour. When, for example, the mercurial column associated with the experimental tube was depressed only five inches, the action was not nearly so rapid as when the tube was full. In such tases, however, it was exceedingly interesting to observe, after some seconds of waiting, a thin streamer of delicate bluish-white cloud slowly forming along the axis of the tube, and finally swelling so as to fill it. 94: Prof. Tyndall on a New Series of _ (Recess, When dry oxygen was employed to carry in the vapour, the effect was the same as that obtained with air. When dry hydrogen was used as a vehicle, the effect was also the same. The effect, therefore, is not due to any interaction between the vapour of the nitrite and its vehicle. This was further demonstrated by the deportment of the vapour itself. When it was permitted to enter the experimental tube unmixed with air or any other gas, the effect was substantially thesame. Hence the seat of the observed action is the vapour itself. With reference to the air and the glass of the experimental tube, the beam employed in these experiments was perfectly cold. It had been sifted by passing it through a solution of alum, and through the thick double- convex lens of the lamp. When the unsifted beam of the lamp was em- ployed, the effect was still the same; the obscure calorific rays did not ap- pear to interfere with the resulé. I have taken no means to determine strictly the character of the action here described, my object being simply to point out to chemists a method of experiment which reveals a new and beautiful series of reactions; to them I leave the examination of the products of decomposition. ‘The mo- lecule of the nitrite of amyl is shaken asunder by certain specific waves of the electric beam, forming nitric oxide and other products, of which the nitrate of amyl is probably one. ‘The brown fumes of nitrous acid were seen to mingle with the cloud within the experimental tube. The nitrate of amyl, being less volatile than the nitrite, could not main- tain itself in the condition of vapour, but would be precipitated in liquid spherules along the track of the beam. In the anterior portions of the tube a sifting action of the vapour occurs, which diminishes the chemical action in the posterior portions. In some experiments the precipitated cloud only extended halfway down the tube. When, under these circumstances, the lamp was shifted so as to send the beam through the other end of the tube, precipitation occurred there also. Action of Sunlight. The solar light also effects the decomposition of the nitrite-of-amyl vapour. On the 10th of October I partially darkened a small room in the Royal Institution, into which the sun shone, permitting the light to enter through an open portion of the window-shutter. In the track of the beam was placed a large plano-convex lens, which formed a fine convergent cone in the dust of the room behind it. The experimental tube was filled in the laboratory, covered with a black cloth, and carried into the partially darkened room. On thrusting one end of the tube into the cone of rays behind the lens, precipitation within the cone was copious and immediate. The vapour at the distant end of the tube was in part shielded by that in front, and 1868. | Chemical Reactions produced by Light. 95 was also more feebly acted on through the divergence of the rays. On re- versing the tube, a second and similar cone was precipitated. Physical considerations. I sought to determine the particular portion of the white beam which produced the foregoing effects. When, previous to entering the experi- mental tube, the beam was caused to pass through a red glass, the effect was greatly weakened, but not extinguished. This was also the case with various samples of yellow glass. A blue glass being introduced, before the removal of the yellow or the red, on taking the latter away augmented precipitation occurred along the track of the blue beam. Hence, in this case, the more refrangible rays are the most chemically active. The colour of the liquid nitrite of amyl indicates that this must be the case; it is a feeble but distinct yellow: in other words, the yellow portion of the beam is most freely transmitted. Itisnot, however, the transmitted portion of any beam which produces chemical action, but the absorbed por- tion. Blue, as the complementary colour to yellow, is here absorbed, and hence the more energetic action of the blue rays. This reasoning, how- ever, assumes that the same rays are absorbed by the liquid and its va- pour. A solution of the yellow chromate of potash, the colour of which may be made almost, if not altogether, identical with that of the liquid nitrite of amyl, was found far more effective in stopping the chemical rays than either the red or the yellow glass. But of all substances the nitrite itself is most potent in arresting the rays which act upon its vapour. A layer one-eighth of an inch in thickness, which scarcely perceptibly affected the luminous intensity, sufficed to absorb the entire chemical energy of the con- centrated beam of the electric light. The close relation subsisting between a liquid and its vapour, as regards their action upon radiant heat, has been already amply demonstrated *. As regards the nitrite of amyl, this relation is more specific than in the cases hitherto adduced ; for here the special constituent of the beam which pro- vokes the decomposition of the vapour is shown to be arrested by the liquid. A question of extreme importance in molecular physics here arises :— What is the real mechanism of this absorption, and where is its seat +? I figure, as others do, a molecule as a group of atoms, held to- gether by their mutual forces, but still capable of motion among them- selves. The vapour of the nitrite of amyl is to be regarded as an assemblage of such molecules.. The question now before us is this :—In the act of ab- sorption, is it the molecules that are effective, or is it their constituent * Phil. Trans. 1864. + My attention was very forcibly directed to this subject some years ago by a con- versation with my excellent friend Professor Clausius. 96 Prof. Tyndall on a New Series of ~ [Reecess, atoms’? Is the vis viva of the intercepted waves transferred to the molecule as a whole, or to its constituent parts ? The molecule, as a whole, can only vibrate in virtue of the forces exerted between it and its neighbour molecules. The intensity of these forces, and ‘consequently the rate of vibration, would, in this case, be a function of the distance between the molecules. Now the identical absorption of the liquid and of the vaporous nitrite of amyl indicates an identical vibrating period on the part of liquid and vapour, and this, to my mind, amounts to an experimental demonstration that the absorption occurs in the main within the molecule. For it can hardly be supposed, if the absorption were the act of the molecule as a whole, that it could continue to affect waves of the same period after the substance had passed from the vaporous to the liquid state. In point of fact the decomposition of the nitrite of amy] is itself to some extent an illustration of this internal molecular absorption ; for were the ab- sorption the act of the molecule as a whole, the relative motions of its constituent atoms would remain unchanged, and there would be no me- chanical cause for their separation. It is probably the synchronism of the vibrations of one portion of the molecule with the incident waves which enables the amplitude of those vibrations to augment until the chain which binds the parts of the molecule together is snapped asunder. The Liquid nitrite of amyl is probably also decomposed by light; but the reaction, if it exists, Is comparably less rapid and distinct than that of the vapour. Nitrite of amyl has been subjected to the concentrated solar rays until it boiled, and it has been permitted to continue boiling for a considerable time, without any distinctly apparent change occurring in the liquid *. 3 I anticipate wide, if not entire, generality for the fact that a liquid and its vapour absorb the same rays. A cell of liquid chlorine now preparing for me will, I imagine, deprive light more effectually of its power of causing chlorine and hydrogen to combine than any other filter of the lumimous rays. The rays which give chlorine its colour have nothing to do with this combination, those that are absorbed by the chlorine being the really effec- tive rays. A highly sensitive bulb containing chlorine and hydrogen in the exact proportions necessary for the formation of hydrochloric acid was placed at one end of the experimental tube, the beam of the electric lamp being sent through it from the other. The bulb did not explode when the tube was filled with chlorine, while the explosion was violent and im- mediate when the tube was filled with air. I anticipate for the liquid chlorine an action similar to but still more energetic than that exhibited by the gas. If this should prove to be the case, it will favour the view that * On the 21st of October, Mr. Ernest Chapman mentioned to me in conversation that he once exposed nitrite-of-amyl vapour to the action of light. With what result I do not know. 1868. ] Chemical Reactions produced by Light. 97 chlorine itself is molecular and not monatomic. Other cases of this kind I hope, at no distant day, to bring before the Royal Society. Production of Sky-blue by the decomposition of Nitrite of Amyl. When the guantity of nitrite vapour is considerable, and the light in- tense, the chemical action is exceedingly rapid, the particles precipitated being so large as to whiten the luminous beam. Not so, however, when a well-mixed and highly attenuated vapour fills the experimental tube. The effect now to be described was obtained in the greatest perfection when the vapour of the nitrite was derived from a residue of the moisture of its liquid, which had been accidentally introduced into the passage through which the dry air flowed into the experimental tube. In this case the electric beam traversed the tube for several seconds be- fore any action was visible. Decomposition then visibly commenced, and advanced slowly. The particles first precipitated were too small to be dis- tinguished by an eye-glass ; and, when the light was very strong, the cloud appeared of a milky blue. When, on the contrary, the intensity was mode- rate, the blue was pureand deep. In Bricke’s important experiments on the blue of the sky and the morning and evening red, pure mastic is dissolved in alcohol, and then dropped into water well stirred. When the proportion of mastic to alcohol is correct, the resin is precipitated so finely as to elude the highest microscopic power. By reflected light, such a medium appears bluish, by transmitted light yellowish, which latter colour, by augmenting the quantity of the precipitate, can be caused to pass into orange or red. But the development of colour in the attenuated nitrite-of-amyl vapour, though admitting of the same explanation, is doubtless more similar to what takes place in our atmosphere. The blue, moreover, is purer and more sky-like than that obtained from Briicke’s turbid medium. There could scarcely be a more impressive illustration of Newton’s mode of re- garding the generation of the colour of the firraament than that here ex- hibited ; for never, even in the skies of the Alps, have I seen a richer or a purer blue than that attainable by a suitable disposition of the light falling upon the precipitated vapour. May not the aqueous vapour of our atmosphere act in a similar manner? and may we not fairly refer to liquid particles of infinitesimal size the hues observed by Principal Forbes over the safety-valve of a locomotive, and so skilfully connected by him with the colours of the sky? In exhausting the tube containing the mixed air and unitrite-of-amyl vapour, it was difficult to avoid explosions under the pistons of the air- pump, similar to those which I have already described as occurring with the vapours of bisulphide of carbon and other substances. Though the quantity of vapour present in these cases must have been infinitesimal, its explosion was sufficient to destroy the valves of the pump. VOL. XVIi. H 98 Prof. Tyndall on a New Series of [ Recess, Iodide of Allyl (boiling-point 101° C.).—Among the liquids hitherto subjected to the concentrated electric light, iodide of allyl, in point of rapidity and intensity of action, comes next to the nitrite of amyl. With the iodide of allyl I have employed both oxygen and hydrogen, as well as air, as a vehicle, and found the effect in all cases substantially the same. The cloud column here was exquisitely beautiful, but its forms were different from those of the nitrite of amyl. The whole column revolved round the axis of the decomposing beam ; it was nipped at certain places like an hour-glass, and round the two bells of the glass delicate cloud-filaments twisted them- selves in spirals. It also folded itself into convolutions resembling those of shells. In certain conditions of the atmosphere in the Alps I have often observed clouds of a special pearly lustre; when hydrogen was made the vehicle of the iodide-of-allyl vapour a similar lustre was most exquisitely shown. With a suitable disposition of the light, the purple hue of iodine- vapour came out very strongly in the tube. The remark already made as to the bearing of the decomposition of nitrite of amyl by light on the question of molecular absorption applies here also; for were the absorption the work of the molecule as a whole, the iodine would not be dislodged from the allyl with which it is combined. The non-synchronism of iodine with the waves of obscure heat is illus- trated by its marvellous transparency to such heat. May not its synchronism with the waves of light in the present instance be the cause of its divorce from the allyl? Further experiments on this point are im preparation. Iodide of Isopropyl—tThe action of light upon the vapour of this liquid is at first more languid than upon iodide of allyl; indeed many beautiful reactions may be overlooked in consequence of this languor at the commencement. After some minutes’ exposure, however, clouds begin to form, which grow in density and in beauty as the light continues to act. In every experiment hitherto made with this substance the column of cloud which filled the experimental tube was divided into two distinct parts near the middle of the tube. In one experiment a globe of cloud formed at the centre, from which, right and left, issued an axis which united the globe with the two adjacent cylinders. Both globe and ey- linders were animated by a common motion of rotation. As the action continued, paroxysms of motion were manifested; the various parts of the cloud would rush through each other with sudden violence. During these motions beautiful and grotesque cloud-forms were developed. At some places the nebulous mass would become ribbed so as to resemble the graining of wood; a longitudinal motion would at times generate in it a series of curved transverse bands, the retarding influence of the sides of the tube causing an appearance resembling, on a smal! scale, the dirt-bands of the Mer de Glace. In the anterior portion of the tube those sudden commotions were most intense; here buds of cloud would sprout 1868. | Chemical Reactions produced by Light. 99 forth, and grow in a few seconds into perfect flower-like forms. The most curious appearance that I noticed was that of a cloud resembling a serpent’s head: it grew rapidly ; a mouth was formed, and from the mouth a cord of cloud resembling a tongue was rapidly discharged. The cloud of iodide of . isopropyl had a character of its own, and differed materially from all others that I had seen. A gorgeous mauve colour was developed in the last twelve inches of the tube; the vapour of iodine was present, and it may have been the sky-blue produced by the precipitated particles which, mingling with the purple of the iodine, produced this splendid mauve. As in all other cases here adduced, the effects were proved to be due to the light ; they never occurred in darkness. I should like to guard myself against saying more than the facts war- rant regarding the chemical effects produced by light in the following three substances ; but the physical appearances are so exceedingly singular that I do not hesitate to describe them. Hydrobromic Acid.—The aqueous solution of this acid was placed in a small Woulfe’s flask, and carried into the experimental tube by a current of air. The tubebeing filled with the mixture of acid, aqueous vapour, and air, the beam was sent through it, the lens at the same time being so placed as to produce a cone of very intense light. Two minutes elapsed before anything was visible ; but at the end of this time a faint bluish cloud appeared to hang itself on the most concentrated portion of the beam. Soon afterwards a second cloud was formed five inches further down the experimental tube. Both clouds were united by a slender cord of cloud of the same bluish tint as themselves. As the action of the light continued, the first cloud gradually resolved itself into a series of parallel disks of exquisite delicacy ; the disks rotated round an axis perpendicular to their surfaces, and finally they blended to- gether to produce a screw surface with an inclined generatrix. This surface eradually changed into a filmy funnel, from the end of which the ‘‘ cord ”’ extended to the cloud in advance. This also underwent modification. It resolved itself into a series of strata resembling those of the electric dis- charge. After a little time, and through changes which it was difficult to follow, both clouds presented the appearance of a series of concentric fun- nels set one within the other, the interior ones being seen through the spec- tral walls of the outer ones; those of the distant cloud resembled claret- glasses in shape. As many as six funnels were thus concentrically set together, the two series being united by the delicate cord of cloud already referred to. Other cords and slender tubes were afterwards formed, and they coiled themselves in spirals around and along the funnels. Rendering the light along the connecting-cord more intense, it diminished in thickness and became whiter ; this was a consequence of the enlarge- H 2 100 Prof. Tyndall on a New Series of [ Recess, ment of its particles. The cord finally disappeared, while the funnels melted into two ghost-like films, shaped like parasols. The films were barely visible, being of an exceedingly delicate blue tint; they seemed ~woven of blue air. To compare them with cobweb or with gauze would be to liken them to something infinitely grosser than themselves. In a second trial the result was very much the same. A cloud which soon assuried the parasol shape was formed in front, and five inches lower down another cloud was formed, in which the funnels already referred to were considerably sharpened. It was connected as before by a filament with the cloud in front, and it ended in a spear-point which extended 12 inches further down the tube. After many changes, the film in front assumed the shape of a bell, to the convex surface of which a hollow cylinder about 2 inches long attached itself. After some time this cylinder broke away from the bell and formed itself into an iridescent ring, which, without apparent connexion with anything else, rotated on its axis in the middle of the tube. The inner diameter of this ring was nearly an inch in length, and its outer diameter nearly an inch and a half. The whole cloud composed of these heterogeneous parts was animated throughout by a motion of rotation. The rapidity of the rotatien could be augmented by intensifying the beam. The disks, funnels, strata, and con- volutions of the cloud exhibited at times diffraction colours, which changed colour with every motion of the observer's eye. Moisture appeared to be favourable to the production of these ap- pearances ; and it hence became a question how far they were really pro- duced by the light: hydrobromic acid, even from its solution, fumes when | it comes into contact with the aqueous vapour of the air; its residence in water does not appear to satisfy its appetite for the liquid. The same effect, as everybody knows, is observed in the solution of hydrochloric acid. Might not, then, those wonderfully shaped clouds be produced by an action of this kind, the presence of the light being an unnecessary accident ? The hydrobromic acid was permitted to enter the experimental tube and remain in diffuse daylight for five minutes. On darkening the room and sending the electric beam through it, the tube was optically empty. Two minutes’ action of the light caused the clouds to appear, and they afterwards went through the same variety of changes as before. No matter how long the hydrobromic acid was allowed to remain in the tube, no action occurred until the luminous beam was brought into play. The tube filled with the mixture of air, aqueous vapour, and hydrobromic acid was permitted to remain for fifteen minutes in the dark. On send- ing the beam through the tube it was found optically empty; but two minutes’ action of the light developed the clouds as before. Permitting the beam to pass through a layer of wafer betore entering 1868. ] Chemical Reactions produced by Light. 101 the experimental tube, no diminution of its chemical energy was observed. Permitting it to pass through a solution of hydrobromic acid, of the same thickness, the chemical energy of the beam was wholly destroyed. This shows that the vibrations of the dissolved acid are synchronous with those of the gaseous acid, and is a new proof that the constituent atoms of the molecule, and not the molecule itself, is the seat of the absorption. Hydrochloric Acid.—The aqueous solution of this acid was also employed and treated like the solution of hydrobromic acid. I intend to invoke the aid of an artistic friend in an effort to reproduce the effects ob- served during the decomposition, if such it be, of hydrochloric acid by light. But artistic skill must, I fear, fail to convey a notion of them. The cloud was of slow growth, requiring 15 or 20 minutes for its full develop- ment. It was then divided into four or five sections, every adjacent two of which were united by a slender axial cord. Lach of these sections pos- sessed an exceedingly complex and ornate structure, exhibiting ribs, spears, funnels, leaves, involved scrolls, and iridescent fleurs-de-lis. Still the struc- ture of the cloud from beginning to end was perfectly symmetrical ; it was a cloud of revolution, its corresponding points being at equal distances from the axis of the beam. There are many points of resemblance between the clouds of hydrochloric and hydrobromic acid, and both are perfectly distinct from anything obtainable from the substances previously mentioned ; in fact every liquid appears to have its own special cloud, varying only within narrow limits from a normal type. The formation of the cloud depends rather upon its own inherent forces than upon the environment. It is true that, by warming or chilling the experimental tube at certain points, extraordinary flexures and whirlwinds may be produced; but with a per- fectly constant condition of tube, specific differences of cloud-structure are revealed, the peculiarity of each substance stamping itself apparently upon the precipitated vapour derived from its decomposition. When the beam before entering the experimental tube was sent through a layer of the aqueous acid, thirteen minutes’ exposure produced no action. A layer of water being substituted for the layer of acid, one minute’s ex- posure sufficed to set up the decomposition. Hydriodic Acid.—The aqueous solution of this acid was also employed. On first subjecting it to the action of light no visible effect was produced ; but subsequent trials developed a very extraordinary one. A family re- semblance pervades the nebulz of hydriodic, hydrobromic, and hydro- chloric acids. In all three cases, for example, the action commenced by the formation of two small clouds united by a cord; it was very slow, and the growth of the cloud in density and beauty very gradual. The most vivid green and crimson that I have yet observed were exhi- bited by this substance in the earlier stages of the action. The de- 102 Ona New Series of Chemical Reactions produced by Light. | Recess, velopment of the cloud was like that of an organism, from a more or less formless mass at the commencement, to a structure of marvellous complexity. I have seen nothing so astonishing as the effect obtained, on the 28th of October, with hydriodic acid. The cloud extended for about 18 inches along the tube, and gradually shifted its position from the end nearest the lamp to the most distant end. The portion quitted by the cloud proper was filled by an amorphous haze, the decomposition which was progressing lower down being here apparently complete. A spectral cone turned its apex towards the distant end of the tube, and from its circular base filmy drapery seemed to fall. Placed on the base of the cone was an exquisite vase, from the interior of which sprung another vase of similar shape ; over the edges of these vases fell the faintest clouds, resembling spectral sheets of liquid. From the centre of the upper vase a straight cord of cloud passed for some distance along the axis of the experi- mental tube, and at each side of this cord two involved and highly iridescent vortices were generated. The frontal portion of the cloud, which the cord penetrated, assumed in succession the forms of roses, tulips, and sunflowers. It also passed through the appearance of a series of beautifully shaped bottles placed one within the other. Once it presented the shape of a fish, with eyes, gills, and feelers. The light was suspended for several minutes, and the tube and its cloud permitted to remain undisturbed in darkness. On re-igniting the lamp, the cloud was seen apparently motionless within the tube; much of its colour had gone, but its beauty of form was unimpaired. Many of its parts were calculated to remind one of Gassiot’s discharges ; but in complexity and, indeed, in beauty, the discharges would not bear comparison with these arrangements of cloud. A friend to whom I showed the cloud likened it to one of those jelly-like marine organisms which a film barely capable of reflecting the light renders visibie. In- deed no other comparison is so suitable; and not only did the perfect symmetry of the exterior suggest this idea, but the exquisite casing and folding of film within film suggested the internal economy of a highly complex organism. The ¢woness of the animal form was displayed through- out, and no coil, disk, or speck existed on one side of the axis of the tube that had not its exact counterpart at an equal distance on the other. I looked in wonder at this extraordinary production for nearly two hours *. The precise conditions necessary to render the production of the effects observed with hydrobromic, hydrochloric, and hydriodic acids a certainty have not yet been determined. Air, moreover, is the only vehicle which has been employed here. I hazard no opinion as to the chemical nature of these reactions. The dry acids, moreover, I have not yet examined. * “Tt is as perfect as if turned in a lathe.” “It would prove exceedingly valuable to pattern-designers,” were remarks made by my assistants as they watched the experi- ment. Mr. Ladd, who is intimately acquainted with the phenomena of the electric discharge through rarefied media, remarked that no effect he had ever seen could compete in point of beauty and complexity with the appearance here imperfectly described. I mention this to indicate how the phenomena affected other eyes than mine. ° 0 PROCEEDINGS OF No. 106. CONTENTS. November 19, 1868. 2 PAGE received since the end of the Session, already Lem in the ‘ Pro- he Solar Eclipse of 1868, as seen at Jamkandi in the Bombay Me Rleuta wy FMueCHE, MM ee ee Oe 6 of the’Total Solar Eclipse of aa 18,1868. By Captain OR RIWG fio ee hie ines RNS c ams Er | he ae aie 18 of the Total Solar Eclipse of lest 18, 1868. By Captain 125 : a Re es Roe easy iy oe Note on a Beni of a Solar Prominence. By J. Nor- KYE F.R.A'S., in a Letter to the Secretary . . - © . . 128 opic fe Observations of the Sun.—No. II. Pe J. Norman Lock- Dee Mee ree bed ah hcl. Sy oTeB Me November 26, 1868. | "7 of os by the Swedish Arctic Se cieditiens at the close ale 1868, in a Letter to the President. By Professor A. Nor- eee rs ¢ Observations of the Sun.—No. I. rat meen e J. Nor- bas beers, BRAS. a te eee Mee eR ae aoe le) Mee n of Contents see the 4th page of Wrapper. 1868. | Papers received during the Recess. 103 November 19, 1868. Lieut.-General SABINE, President, in the Chair. In pursuance of the Statutes, notice of the ensuing Anniversary Meeting | for the Election of Council and Officers was given from the Chair. Mr. Currey, Mr. Hudson, Mr. Newmarch, Mr. Prestwich, and Mr. Stainton, having been nominated by the President, were elected by ballot Auditors of the Treasurer’s Accounts on the part of the Society. Dr. Bastian, Rear-Admiral Cooper Key, and Mr. Vernon Harcourt were admitted into the Society. The following communications were read :— “On the Physical Constitution of the Sun and Stars.” By G. JOHNSTONE Stonery, M.A., F.R.S., F.R.A.S., Secretary to the Queen’s University in Ireland. Received May 15, 1867. (See page 1.) I. “Second List of Nebule and Clusters observed at Bangalore with the Royal Society’s Spectroscope ;” preceded by a Letter to Professor G. G. Stokes. By Lieut. Joun Herscuet, R.E. Communicated by Prof. Stokes. Received July 20, 1868. (See page 58.) II. “On the lightning Spectrum.” By Lieut. Jonn Herscuet, R.E. Communicated by Prof. Sroxzs. Received August 8, 1868. (See page 61.) Ill. “Products of the Destructive Distillation of the Sulphobenzo- lates.,—No. II. By Joun Strennovussz, LL.D., F.R.S., &c. Received September 8, 1868. (See page 62.) IV. “Compounds Isomeric with the Sulphocyanic Ethers. — II. Homologues and Analogues of Ethylic Mustard-oil.” By A. W. Hormann, Ph.D., M.D., LL.D. Received September 11, 1868. (See page 67.) V. “ Account of Spectroscopic Observations of the Eclipse of the Sun, August 18, 1868.” In a Letter addressed to the President of the Royal Society by Captain C. T. Hate, R.E. Communicated by the President. Received September 21,1868. (See page 74.) VI. “ Account of Observations of the Total Eclipse of the Sun, made August 18th, 1868, along the coast of Borneo.” In a Letter ad- dressed to H.M. Secretary of State for Foreign Affairs, by His Excellency J. Porn Hunneussy, Governor of Labuan. Com- VOL. XVII. : I 104 Lieut. J. Herschel’s Account of the [Nov. 19, municated by the Right Hon. Lord Stanuey, F.R.S. Received October 8, 1868. (See page 81.) VII. “ Further Particulars of the Swedish Arctic Expedition.” Ina Letter addressed to the President, by Professor NorDENSKIOLD. Communicated by the President. Received October 15, 1868. (See page 91.) VIII. “ Notice of an Observation of the Spectrum of a Solar Promi- nence.” By J. N. Lockyer, Esq., in a Letter to the Secretary. Communicated by Dr. SHarpry. Received October 21, 1868. (See page 91.) IX. “Qn a New Series of Chemical Reactions produced by Light.” By Joun Tynpatt, LL.D., F.R.S., &c. Received October 24, 1868. (See page 92.) X. “Account of the Solar Eclipse of 1868, as seen at Jamkandi in the Bombay Presidency.” By Lieut. J. Hurscurer, R.E. Com- municated by Prof. G, G. Stoxus, Sec. R.S. Received October 19, 1868. To the President, Council, and Fellows of the Royal Society. GENTLEMEN,—The time has arrived when I must offer for your accept- ance a connected report of the employment of the instruments intrusted to me for the special purpose of observing the late solar eclipse. 1. Plan of this Report. In framing this Report I propose in the first place to describe those in- struments sufficiently in detail to render unnecessary such explanations as would otherwise be required in the course of my narrative, and then to show the circumstances which preceded their actual employment on that occasion. 2. Description of Telescope and clockwork. The principal instrument is an equatorially mounted telescope, with a lens of 5 inches aperture and 62 inches focal length. The mounting is adapted to any latitude (except very low and very high ones), the polar axis being a moveable tangent to the circular-arched roof of the chamber con- taining the clockwork. The latter, as well as the rest of the instrument, is by Messrs.Cooke and Sons, of York, and is, as I understood from Mr. Cooke, of a — somewhat novel description. Ihave not examined the mechanism closely, and therefore cannot describe it very accurately ; but I believe the peculiarity consists in the maintenance of continuous motion in a fan-wheel, regulated by a pendulum time-keeper acted on through a remontoir escapement, whereby the irregularity of the surplus energy of the driving-weight, while it is pre- vented by the latter from interfering with the time-keeper at all, is modi- fied in its action on the tube by the former. The mean rate of motion is 1868.] _ Solar Eclipse of 1868. 105 thus uniform ; and though there is very perceptible irregularity in the actual motion, it is not intermittent. Thus, when the image ofa star, for instance, is brought on the slit of the spectrum-apparatus, the spectrum is fitful in appearance, if the slit is perpendicular to the direction of diurnal motion. The mean motion may be easily regulated as in a pendulum-cleck. The- motion is communicated by friction to the first of a series of wheels which terminates in an endless screw working in the circumference of a large toothed are attached to the hour-axis. Motion imparted by hand to one of these wheels, grooved and provided for this purpose with an endless cord, is thus communicated directly to the tube without greater strain on the clock than is implied in overcoming the connecting friction. 3. Its Mounting. The declination-axis terminates in a T-shaped head carrying two circular collars, in which the telescope-tube rests. For convenience in mounting and dismounting, these collars are attached to the T-head by nut and pins, so that they lift off with the tube, while the balance can be adjusted by releasing their grasp of the tube when required. This is a great conveni- ence in a portable instrument. The tube can be dismounted and taken indoors readily without assistance ; and the body of the instrument (which, besides being far less easily handled, has cost hours of adjustment) may be left under a suitable waterproof case when no observatory has been con- structed. . 4. Its Stand. The stand is a strong wooden one, of remarkably firm construction, consi- dering that it is of the three-legged portable kind. Its upper surface is a stout brass annulus, on which the clock-chamber rests and rotates, if required, for adjustment in azimuth. Two of the legs have foot-screws for adjusting the level and completing the adjustment for latitude. 5. Of the Spectroscope. The spectroscope intended for use with the above telescope was con- structed by Messrs. Simms, on a pattern or design supplied (I believe) by Mr. Huggins; but its construction was too much delayed to allow of a practical examination of all its parts before packing. It consists of a single flint-glass prism, of refracting angle 60°, contained in a cylin- drical brass chamber, from which radiate three tubes in such directions as to fulfil the several purposes of (1) receiving the light to be analyzed, (2) delivering it after refraction and separation to the eye, and (3) admitting external light for reflection to the eye off the second surface of the prism. The first consists externally of a long connecting tube for insertion into the telescope in place of the ordinary eye-tube, where it is grasped in the focusing-slide. Internally it carries a smaller tube, carrying at one end a lens, and at the other, at the principal focal distance of the latter, a beautiful piece of workmanship by which a slit is obtained whose sides 12 106 Lieut. J. Herschel’s Account of the [Nov. 19, approach each other equally. Half the length of this slit may be obscured by the intervention of a right-angled prism, which reflects a side light through it if required. The converging rays from the object-glass falling on the slit are admitted, while those which do not are stopped. The former diverging again, as though from a luminous line, emerge from the next lens and fallon the prism as parallel rays, are independently refracted and dis- persed in traversing it, and after emergence are again condensed, but not reunited, by the object-glass in the small telescope composing the second of the above-mentioned tubes, and, forming a spectrum in its focus, are viewed as such by an eyepiece. Means of measurement.—The direction of emergence defines the position in the spectrum ; and the difference of direction is measured by the change of direction of the small telescope necessary to receive the several refracted rays directly. This change of direction is effected and measured by a tan- gent screw, whose complete revolutions are indicated by the march of a graduated scale (attached to the telescope-arm) over a circle marked on the circumference of the divided cylindrical head of the screw. The posi- tion of the centre of motion of the telescope-arms, it should be said, though optically unimportant, is practically within the prism. By the help of a reading-lens the revolutions, and tenths and hundredths of a revolution, can be easily read off by a very slight movement of the eye from the eye- piece. New pique Scale for micrometer measures.—A mistake having oc- curred in graduating the scale, I substituted one of my own making. As I was fortunate in this, I may venture to describe how it was effected. The graduation required was too fine for any ink lines I could make; I there- fore varnished a piece of card, and drew fine lines at the proper intervals on the shellac-coating with a sharp blade; and applying a little ink, these were instantly rendered visible. J then cut the card across the lines and glued the scale so formed over the old one with varnish, giving the whole a dash of varnish for the sake of protection. When dry I was gratified to find the graduation correspond well with the revolutions; for it was rather a delicate job, and I did not succeed without failures. 6. Graduated Scale inthe Field of View. The third tube was intended to present in the field of view of the tele- scope last described, by external reflection off the second surface of the prism, an illuminated image of a photographed scale placed at one end of the tube, in the principal focus of a lens at the other. Thetube carriesa — small moveable mirror outside. Upon this mirror was intended to be thrown the light of a small lamp, held n position by a bent arm projecting from the prism-chamber. I am sorry to say that this ingenious contrivance proved, in my hands, more unsatisfactory than perhaps it should have done. As in not using it I departed from the letter of my instructions, I am in a measure bound to explain my reasons for discarding it. 1868. ] Solar Eclipse of 1868. 107 Reasons for discarding it.—In the first place, I never could with any kind of illumination train my eye to read the scale, partly because (whether from diffraction or irradiation) the image was never distinct, partly because the figures were illegible. Inthe next place the little lamp was capricious ; either it refused to keep alight, or it boiled its own oil and melted off its - handles, and ended by burning my fingers! Thirdly, it was an additional weight at the eye-end of the telescope and involved a counterpoise when not in use, and an additional projection to be avoided in every movement —in the dark,—all implying additional distractions and sources of failure. Lastly, I found I could do very well without it—in the preliminary traiming which I underwent on examining the nebule. At the same time I must confess that I made an oversight in trusting too much to the illuminating power of a hand-lamp, as will be apparent when I come to describe the actual eclipse-observations. 7. Smaller Telescopes and Polarizers. The second instrument supplied was an achromatic refractor of 3 inches aperture mounted with vertical and horizontal axes, the socket of the former being supported on a three-legged wooden stand, afterwards replaced by one of greater stability and more convenient height. Two cells, containing a double-image prism and quartz plate, and the combination known as Savart’s polariscope, respectively, were supplied for use with this telescope, but without any connecting adaptation. 8. Hand Spectroscopes. The other instruments were hand spectroscopes for direct vision, four in number, which I was directed to distribute according to circumstances, It is needless to describe these instruments, as they are well known; but I must venture to correct a statement made at a meeting of the Royal Asiatic Society last December, that they have a magnifying-power of 8 or 10. I do n’t think they can be credited with a higher power than 3; and I was never able to recognize any of the peculiar characteristics of nebular or stellar spectra, the recognition of which might have Ee expected with the higher See iie ine power: 9. Arrivalin India and communication with Colonel Walker, R.E. Soon after my arrival in India I communicated with Colonel Walker, with the object of receiving his instructions and of ascertaining whether he had decided on any plan, and, if not, to learn his views with reference to the assistance I might expect from the Survey Establishment. The choice of a station of observation and the disposal of the instruments were also dis- cussed in the course of correspondence. 10. His Reply, and application to the Indian poe Colonel Walker’s action in this matter has been most gratifying. He Ammediately promised me the assistance of Lieut. W. Maxwell Campbell, 108 Lieut. J. Herschel’s Account of the [Nov. 19, of the Bombay Engineers, one of the executive officers of our Department, at that time engaged with myself and others in measuring a base-line in the neighbourhood of Bangalore, for the polarization-observations or other- wise, as I might arrange with him. He also placed at my future disposal for the occasion the services of Lieut. Campbell’s assistants, in case such should be required, at the same time presenting to the Indian Government an urgent proposal to give the Royal Society’s expedition both countenance and support. I enclose a copy of the reply to this proposal, in which it will be observed that the Governor General in Council “ cordially approves,’’ and “ sanctions the necessary expenditure,’ and pledges the Government “‘ to do everything in ifs power towards securing full and accurate observations ”’ on the occasion—a pledge fully redeemed by the ready assent given to more than one other application. Iam accordingly enabled to submit to your Society my present Report unaccompanied by any further appeal to your Treasurer. 11. Steps taken to procure local information as to weather &c. The local Governments were also applied to to give effect to the circula- tion of aseries of queries calculated to elicit local information as to probable climate at numerous points situated along the line of shadow. This was the more necessary, as my position at Bangalore (in the very centre of the peninsula) seemed to give a so much greater range of choice. In this respect also a warm interest was evinced. I wish I could add that the mass of correspondence which resulted was productive of an- equal amount of valuable information. The practical value was chiefly confined to extracts from rain-registers, the principal question relating to probable cloudiness or otherwise being perhaps necessarily replied to too vaguely to form legiti- mate grounds for decision, owing in great measure to the fact that August is one of the most uncertain months in the year, in that respect, in southern India. | Rough notion of rain distribution across the peninsula in August.—On the whole, however, it appeared that across the whole width of the penin- sula cloudy weather was to be expected at that season; and there was therefore no choice but what could be based on rainfall. The annexed diagram represents the impression (necessarily a vague one) remaining on my mind after considering the reports. On the west coast anything up to 25 inches a week has been recorded in August ; on the eastern slopes of 1868. | Solar Eclipse of 1868. 109 the western Ghauts the fall seems both smaller and more regular, 6 to 10 inches being the usual fall in the month of August. Further inland we come to a tract notorious for its dryness, several places, such as Gokak, Jamkandi, Béjapur, and others thereabouts, being favoured with occasional showers only. I attributed this to the descent into a lower - and hotter region of the prevailing south-west current, the greater part of whose moisture had been deposited during the disturbance of strata caused by passing over the sudden barrier of the Ghauts. Beyond this again, eastwards, there is a gradual rise in the amount due in August, until towards the east coast the average fall is again 6 or 8 inches. 12. Jamkandi selected. Jamkandi, the residence of a native chief, was among the first to at- tract my attention, partly owing to the offers of assistance which were made in the name of the chief; and this place was eventually selected for the advantages of climate which it appeared to offer. 13. Distribution of the Instruments. Lieut. Campbell, R.E. In the meantime the distribution of the instruments was attended to. The smaller telescope with polarizing eyepieces was made over to Lieut. Campbell with a copy of the ‘‘ Instructions,” in the full assurance that he would acquaint himself with the theory and practice necessary to turn them to account. I annex a copy of his Report, the perusal of which will show that the instrument was in good hands. It is much to be regretted that he was not permitted to give more practical evidence of the forethought which characterized his prepa- rations. I am also sorry that he has not given a fullerdescrip- tion of the ingenious contri- vance which he designed and constructed for the ready appli- cation of the analyzers to the eyepiece. The annexed rough sketch (from memory) may help to giye a correct idea of the contrivance. I apprehend that in the event of fair weather he would be able to settle the question of polarity readily, and would have leisure to make use of a hand spectroscope as well. One of these instruments also was there- fore made over to him. 14, Captain Haig, R.E. Colonel Walker had further consented to allow another of our executive officers (Captain Haig, R.E.) to leave his regular duties for a time if he wished. As he was stationed at Poona and could avail himself of the railway as far as the border of the shadow’s path, I offered him, and he accepted, the charge of another of the hand spectroscopes. 110 Lieut. J. Herschel’s Account of the [Noy. 19, 15. Peninsular and Oriental Steam Navigation Companys Agent, Captain Henry, Superintendent at Bombay. Lastly, I communicated with the agents of the Peninsular and Oriental Company at Calcutta and Madras Bay, and eventually intrusted the remain- ing two spectroscopes to the latter for employment on board two vessels, outward- and homeward-bound, which would probably be on the track at the right time. 16. Memorandum of explanations and suggestions for use of Hand Spectroscopes. It was necessary, however, not only to distribute these instruments, but also to provide for their being intelligently employed in unpractised hands. I accordingly drew up a short memorandum with the object of putting it into the power of those interested to understand as much of the subject as seemed necessary, and of suggesting the probable appearances which might be presented. A copy of the pamphlet accompanies this Report. 17. Examination of Nebule as bearing on the main subject. While these arrangements were in progress I was myself engaged with the equatorial in the examination of the southern nebule, to which I de- voted as much time as the duties of my profession enabled me todo. The weather was very favourable in March (towards the middle of which month the base-line was completed), in April, and until the middle of May; but from that time until the latter end of June, when the instrument had to be despatched, I hardly got a single observation, owing to the setting-in of the south-west monsoon. I congratulated myself on having been able to use the fine nights we had had. The results, showing the nature of the spectra of about fifty nebulz, have been already communicated to your Secretary ; there is therefore no occasion to enter into particulars on this subject here, except as bearing on instrumental peculiarities not previously touched upon, and as suggesting the probability that a considerable fami- liarity with the special kind of observation had been acquired, as well as with the individual instrument. Those who are acquainted with the spec- troscope as applied to a telescope will remember that it involves several additional screws to be attended to, and that the finding of these ntecha- nically in the dark is no inconsiderable perplexity until habit has taught the way. But this by the way. 18. The Finder, and the trouble it gave. The finder attached to the telescope has a very low magnifying-power and decidedly bad definition—so much so that even Saturn can scarcely be recognized with it; none but the most conspicuous nebulz and clusters are visible; I have looked in vain for the planetary nebula in Lyra with it, though it was certainly in the field; and of all the planetary nebule in the southern hemisphere, only two (Nos. 2102 & 4510) are noted by meas 1868. | Solar Eclipse of 1868. TE ‘visible in finder.”’ It was therefore almost always necessary to find with the principal, by the setting; and afterwards either to exchange the light eyepiece for the heavy spectroscope (removing at the same time a coun- terpoise) without disturbing the direction, if possible, or to take the bear- ings of the most conspicuous stars visible in the finder. But asthere never - was and never could be any certainty that in the act of insertion a disturb- ance sufficient to displace the image from the position the slit should oc- cupy would not take place, the latter method became the surest, if the most troublesome. [The connecting-tube, I should remark, cost me, literally, days of worry and giinding before I could induce it to slide in and out at all.] If after these precautions the result of a blind search was negative, the whole had to be done de novo. What with removing and replacing the spectroscope, inserting eyepieces and counterpoises, setting the readings, searching in both finder and telescope, winding the driving-clock over and over again, in endless combination, all by the light of a bull’s-eye lantern, perhaps without catching a single spectrum all night, I often found four or five hours’ observing (?) more fatiguing than a long walk. It may appear strange that I did not replace the finder by a better telescope. I can only say that India is not England, and Bangalore is not London. The idea did not occur to me as a practical one, and I was ner- vously afraid of making any alteration which might leave me worse off than I was. A bad finder was after all no great matter, for the eclipse and the nebulze could wait. At the same time I wish now that my finder had been more serviceable as a telescope for I got ; but a poor sight of the eclipse with it. 19. Further preparations, Observatory, &c. To return to my preparations. In the utter absence of any precise knowledge of the appearances which would be presented, but anticipating a faint spectrum as the most probable, all my preliminary arrangements had in view as complete an exclusion of external light as practicable. A wooden frame was constructed for an observatory with a revolving roof, the latter being covered with painted canvas. A large black curtain was pro- vided, through the centre of which were to be passed the observing-end of the telescope and finder, and the declination-clamp and slow-motion screw. A segment of the octagonal observing-chamber would thus be in a great measure protected from the light which might be expected to enter the limited aperture in the roof. 20. The Expedition leaves Bangalore. The instruments, observatory, and camp-equipage started from Bangalore on the 7th of July, and reached on the 7th of August—a creditable march of 390 miles in 31 days (including halts) in the height of the rainy season. My subsequent experience of the state to which so-called ‘“‘made”’ roads may be reduced, in these parts of India, by a few days’ rain, afforded grounds 112 Lieut. J. Herschel’s Account of the [Nov. 19, for self-congratulation that the journey was accomplished as quickly as it was. I followed on the Ist of August, and reached Jamkandi on the morning of the 14th. The journey was so exceedingly disagreeable a one that I shall say no more about it. 21. Arrival at Jamkandi. By the evening of the 14th the observatory was put together and the telescope &c. ready for adjustment. 22. Prospects. I was surprised and considerably disappointed to learn that the weather had been for some days past as cloudy as I foundit. I had left heavy rain behind me at Belgaum, and found none at Jamkandi certainly ; but the sky was thick with passing cloud. I was told that it was quite unusual, and that it could not last; but by the morning of the 18th both Lieut. Campbell and myself had made up our minds not to be disappointed (if we could help it), should we be denied more than a few glimpses. 23. Bad weather not unusual at this season. T learned afterwards that at some time or other at that season a burst usually takes place on the Ghauts, causing a sudden and violent flood in all the rivers, and that the influence of this extends beyond their limits and occasions the fortnight of cloudy skies and scanty rainfall which such places as Jamkandi enjoy once a year. This periodical flood had occurred be- tween the time of our camp’s and our own arrival, and we were now expe- riencing the cloudy season. It was very unfortunate, but could hardly have been foreseen. Not only our own party, but others in the neigh- bouring district of Béjapur were unlucky. Three days later the whole aspect of the country was changed. The rivers subsided; the heat which we had expected, but missed, began to make itself felt ; the villanous black soil hardened ; and the natives said confidently that their rainy season was past, and that the rivers would not rise again till next year. 24. Lieut. Campbell s Station. On the 17th Lieut. Campbell selected his position on a hill about a mile distant. We had agreed that the character of the clouds was such that a greater separation was unnecessary, owing to their uniform distribution and regular current. 25. Final preparations. I come at length to the more interesting part of my narrative. The three days and nights which preceded the event were occupied in adjusting the polar axis, in examining every adjustment that could or could not require it, in exchanging the broad coarse pointer which I had used for night work for a stout but sharp needle, in going over and over again a mental review of the probable appearances and the possible contingencies which might arise. The three months’ disuse, too, since I had to give up the 1868. | Solar Eclipse of 1868. 113 nebulze, made fresh exercise necessary. Among other things, I concluded not to alter the pendulum, long ago adjusted for sidereal time. The difference of rate being only 1 in 365 for mean time (and 1 in 388 for solar time at that date), the telescope would only gain on the sun by less than one second during the 54 minutes of totality; so that even supposing I ~ should wish to keep it directed on one and the same point the whole time, the practical effect would only be that that pomt would move along the slit by perhaps 5, part of its visible length (estimating that length, or the width of the field, at 5’). I mention this as the “ Instructions ”’ direct the adjustment to apparent solar time. 26. Disuse of the Barlow Lens accounted for. In one other respect, too, I must plead guilty to a departure from the letter of those instructions, which hardly perhaps needs justifica- tion; I allude to the disuse of the Barlow lens. My reason was prin- cipally this, that its insertion keeps the observer some 6 inches further from the body of the instrument, and, besides involving a complete dis- turbance of equilibrium, puts him out of reach of the declination screw— results which I could not but think had not been contemplated. I should add that I was quite confident of the practicability of catching a promi- nence, without having its image doubled in size, though I was by no means so sure that I could spare any of the light, which would be reduced one-fourth. 27. Care in adjusting the Pointer during the approach of the Moon. During the advance of the moon, and up to the last available moment, I paid particular attention to the collimation (1 use the word in its true sense of aim) of the needle-point, being perhaps unnecessarily anxious to avoid my old difficulty of finding my object in the spectroscope. The sharp cusps were well suited to this purpose, and the sun-spots were good tests. I had been fortunate in getting the pointer very exact, and was therefore not troubled with any collimation-error to allow for. 28. Spectrum at the Moon’s centre. While thus employed I had occasion to remark that at the centre of the moon, some nine or ten minutes before totality, the intensity of the solar spectrum was much about the same as that of the full moon. 29. Measurement of Solar Lines. Intensity of Spectrum of Iimb at D.—The principal solar lines were measured at intervals during the advancing eclipse. A few minutes before totality, in going over these lines for the last time, the slit being as wide as was allowable for full sunlight, 7. e. very narrow, I recorded an increasing brilhancy in the spectrum in the neighbourhood of D, so great in fact as to prevent any measurement of that line till an opportune cloud moderated the light. Iam not prepared to offer any explanation of this. The clouds were 114 Lieut. J. Herschel’s Account of the [Nov. 19, arranged in two distinct strata, the lower one containing masses hurrying past with the monsoon-current at no great height, the upper consisting of light, thinly scattered cirri showing very little motion. It is conceivable that the latter may have been obstinately interposed until the time when I remarked the recorded brilliancy; but I cannot say that I should be satisfied with such an explanation. Whiteness of the Crescent.—I also remarked that the whiteness of the crescent, as seen in the finder, was apparently intensified as it grew narrower. Possibly this was the effect of contrast with the darkening background ; for at this time I began to be annoyed by the appearance of five or six phantom crescents, which seemed to be trying to rival the legitimate one. Limagine I was indebted to the dark glass for these apparitions ; but whatever called them up, they most effectually confused the view of the closing scene; whatever might otherwise have been seen at this stage was swamped in the confusion. 30. Restlessness during approach of shadow. Up to within about ten minutes of totality I was every now and then out- side watching progress through one or the other of two smaller telescopes of moderate power, one of which I had borrowed from the chief, who in- dulges a taste for the possession of English manufactures to an extraordi- nary degree. I noticed no marked inequalities of surface in the advancing limb, nor any bluntness of the cusps; but I must allow that I was not in a sufficiently composed state of mind to observe critically anything not bearing directly on the special problem before me. I was impressed with a notion that everything must be subordinated, in my case, to the requisite freedom of attention when totality commenced, and was specially anxious to save my eyesight. I studiously avoided looking at the sun except under cover of a cloud; and though I had provided the telescopes with gradu- ated smoked glasses, I was nervously afraid to look through them too long or too intently—all which can only be understood by referring to what has been said about the absence of any foreknowledge of the impending revelation. My last view of external appearances showed nothing very striking—a few deeply neutral-tinted patches of sky in the zenith, and an Increasing gloominess in all directions, being all the phenomena whose im- pression has outlived the excitement of the shortlived minutes which ensued. I reentered the observatory, and retired behind my black curtain to watch the event. 31. Gentlemen, I have thus far endeavoured to lay before you, as faras possible, in an orderly manner, an outline of the preliminary arrange- ments for the employment of your Society’s instruments, and a sketch of my proceedings up to the hour of the eclipse. If inso doing I have been un- necessarily tedious, I would ask you to remember that these few pages but faintly represent the months of anxious study and preparation which have passed since I accepted the responsibility involved in the charge of an ex- 1868. | Solar Eclipse of 1868. 115 pedition deputed by the illustrious body I have now the honour of ad- dressing—a responsibility more engrossing, it may be, but not lessened, by the specific but novel character of the proposed object of the expedition. I proceed now to describe how far that object has been attained; and here I feel that I cannot well indulge in too great a minuteness of detail. 32. Relative positions of Pointer, Slit, and Sun’s Limb. The spectroscope may be inserted, and employed with its slit in any di- rection perpendicular to the optical axis of the telescope. It is therefore competent to the observer to place the slit perpendicular or tangential to the sun’s circumference at any point; and there can be no doubt that, were the observations conducted at leisure, 1t would be desirable to examine the whole circumference in both positions ; but the operation of turning the spectroscope is not so very simple a one but that the advantages and disad- vantages of any such proceeding require to be well considered where time is of the first importance. I decided on employing the slit in one direction only, that which corresponded with the diurnal motion. It so happened that this corresponded nearly with the direction of the relative motion of the sun and moon, so that the widest part of the crescent could be made to fall nearly perpendicularly across the slit. The needle (in the finder) and its point accurately represented the direction and centre respectively of the slit; therefore, when the needle-point touched the sun’s limb at the centre of the crescent, a solar spectrum of definite width appeared in the field, of which one edge (the right-hand) continued stationary, while the other (the left) advanced slowly but perceptibly towards it, the solar spectrum decreasing visibly in width. 33. Last view of Solar Spectrum. About a minute’s breadth remained. A few seconds more and it would vanish suddenly. Whatever spectrum the corona could show must then be revealed, unless indeed a “‘ prominence ” or “‘ sierra’’ should happen to be situated at that precise spot, in which case the double spectrum should be presented. The nervous tension at the moment may be conceived: what would be seen? what call for action would be made? and for what action ? or, if nothing were seen, what would have to be done? I cannot say that I was prepared, at that moment, either with these questions, or with ready answers to them; but that was the sensation. With regard to the last, I suppose I should have instinctively widened the slit; and had that failed, should then have gone to the finder to look for a prominence. As it was, the spectrum faded out as I looked, while it had still appreciable width, and I knew a cloud had intervened. _ Totality commences unseen.—A few seconds more and the spectrum of diffuse light vanished also, and told me the eclipse was total, but behind a cloud. 34. On the watch for a glimpse. I went to the finder, removed the dark glass, and waited; how long, I 116 Lieut. J. Herschel’s Account of the [ Nov. 19, cannot say ; perhaps half a minute. Soon the cloud hurried over; follow- ing the moon’s direction, and therefore revealing first the upper limb, with its scintillating corona, and then the lower. _ A prominence seen and aimed at.—Instantly I marked a prominence near the needle-point, an object so conspicuous that I felt there was no need to take any precautions to secure identification. It was a long finger-like projection from the (real) lower left-hand portion of the cireum- ference. A rapid turn of the declination-screw covered it with the needle- point, and in another instant I was at the spectroscope. A single glance and the problem was solved. Tts Spectrum.—THREE VIVID LINES, RED, ORANGE, BLUE; NO OTHERS, AND NO TRACE OF A CONTINUOUS SPECTRUM. 35. Measurement of lines undertaken, with partial success. When I say the problem was solved, I am of course using language suited only to the excitement of the moment! It was still very far from solved, and I lost no time in applying myself to measurement. And here I hesitate ; for the measurement was not effected with anything like the ease and certainty which ought to have been exhibited. Much may be attributed to haste and unsteadiness of hand, still more to the natural difficulty of measuring intermittent glimpses; but I am bound to confess that these causes were supplemented by a failure less excusable. I have no idea how those five minutes passed so quickly! Clouds were evidently passing continually; for the lines were only visible at intervals—not for one- half the time, certainly—and not always bright ; but still I ought to have measured them all. My failure was in insufficient illuminating power ; but why, I cannot tell. I never experienced any difficulty of the kind with the nebulz, which required that I should flash in light suddenly over and over again. I had found the hand-lamp the surest way ; but it failed me here in great measure. The ved line must have been less vivid than the orange ; for after a short attempt to measure it, 1 passed on to secure the latter. Two lines measured.—In this I succeeded to my satisfaction, and ac- cordingly tried for the blue line. Here I was not so successful. The glimpses of light were rarer and feebler, the line itself growing shorter and, what remained of it, further from the cross. I did, however, place the cross wires in a position certainly very near the true one, and got a reading before the reillumination of the field told me that the sun had reappeared on the other limb. These readings were called out, as those of the solar lines | had been, to my recorder ; and it was only afterwards that I compared them. I need not dwell on the feelings of distress and disappointment which I experienced on realizing the fact that the long-anticipated opportunity was gone, and, as it seemed to me then, wasted. I seemed to have failed entirely. Almost mechanically I directed the telescope to the bright limb, to verify the readings of the solar lines; and in so doing my interest was 1868. | Solar Eclipse of 1868. 117 again awakened by the near coincidence, as it seemed, of the line F with the position of the wires; but a little reflection convinced me that the distance of the former was greater than the error which I might have made in intersecting the blue line. Their readings and those of the solar lines.—I read F, and then D&C. The following were my readings up and dowa :— C. D. b. Be: 1°91 2°96 4°58 5°64 Before 1:90 2°94 4°56 5°61 eri~ b. £93 2°98 4:60 5°65 1:92 2°97 4°58 5°62 Bright lines... [3°00] sn foroo)| ae 1°93 3°00 Me 5°63 36. Identity of the Orange Line. 1 consider that there can be no question that the ORANGE LINE was identical with D, so far as the capacity of the instrument to establish any such identity is concerned. 37. Of the Blue Line: doubtful. I also consider that the identity of the BLUE line with F is not esta- blished ; on the contrary, 1 believe that the former is less refracted than F, but not much. 38. Of the Red Line: uncertain. With regard to the rep line, [ hesitate very much in assigning an approximate place: B and C represent the limits; it might have been near C ; I doubt its being so far as B; I am not prepared to hazard any more definite opinion about it. Its colour was a bright red. This esti- mate of its place is absolutely free from any reference to the origin of the lines C and F. 39. Subsequent mental aberration: not unusual. It is a fact not unworthy of notice that in all the accounts of eclipses, written soon after the event, which I have read, the record hurries rapidly to a close after the sun has reappeared ; the reason, no doubt, is that a reaction takes place after the excitement of witnessing the actual eclipse, and phenomena which might be noticed after, quite as well as before, pass unregarded on that account. For my part I was surprised to find how utterly indifferent I felt to the appearance of things when I came out of my observatory. I am almost ashamed to confess that I went straight to my tent, and tried to write down what I had seen, instead of going to the telescope to watch for what still might be seen. It never even occurred to me to remove the spectroscope and use the fine telescope I had at command. 40. Afterconsideration of the phenomena witnessed. : I have not quite exhausted the statement of my observations, though is Lieut. J. Herschel’s Account of the [ Noy. 19, what I have still to state was rather the result of subsequent reflection than of actual cognizance at the time. I said that the prominence was situated close to the needle-point. I estimate its position as at the east point, a few degrees to the left of the lowest, of the sun’s limb. Its form was that of a projecting finger slightly curved to the southward, and its height nearly 2’. The slit was at right angles to the hour-circle, and therefore perpendicular to the sun’s limb at this point. A vertical section (so to speak) of the prominence was therefore admitted through the slit. It ap- _ pears, then, that the length of the lines corresponded with the height of the prominence, being limited (as in the case of the spectrum of the section of the crescent) on the one hand (the left) by the advancing moon’s limb at the centre of the field, and on the other by the natural summit of the prominence, or flame, as we are now entitled to call it. Spectrum of Corona not seen.—Beyond this summit the light of the corona was free to enter ; it was also free to enter with that of the flame ; but I saw the spectrum of the latter only. I thence conclude that the spectrum of the corona was a faint solar one,—a conclusion quite in ac- cordance with the other characteristics of this phenomenon, such as the radiated appearance and the evidence from polarity, indicating a central source of light. With regard to the latter, it is clear that the light of the corona is polarized in planes passing through the sun’s centre (as the gist of Lieut. Campbell’s Report), and therefore that the corona shines mainly by reflected light. At the same time it is possible that the absence of a spectrum of the corona at this particular spot may have been accidental. I have since heard that the corona was particularly feeble at this point. I had no opportunity of studying the corona myself. After first catching sight of the eclipse in the finder, I never left the spectroscope but once, when a long interval of cloudiness sent me to the finder to make sure. I then caught a few seconds’ glimpse again, and remarked a red blot (1 recognized no shape) of a prominence at about the north point, or rather to the west of it. | 4]. Remarks on the ease with which the lines might be measured, and suggestions for future observations. I have now a few remarks to add which may be of use to future ob- servers, if not of any present value. It is difficult to say what might or might not have been done but for the clouds; but I am pretty certain that (even labouring, as I was, under the difficulty of bad illumination) not only might all three lines have been satisfactorily measured, but time would have sufficed for further examination. The course which that examination should take is a question which itis of the highest importance for an observer to decide on previously. I believe I was right in using a narrow slit to begin with, not anticipating such a totally dark field; but 1 should not do so again; or if I did, with the object of getting exact mea- sures of the three principal lines, I should be prepared to widen the slit 1868. ] Solar Eclipse of 1868. iid to look for faint ones, the positions of which I should estimate with re- ference to those three. I should then direct the telescope at the brightest part of the corona, taking very good care to prefer a part free from any appearance of sierra, and if possible near the east or west points, so that the slit might admit a vertical section. Assuming that the corona does not emit tosochromatic light —if I may be allowed to coin a word to indi- eate definite but unspecified colours, both in respect of number and tint (or pitch )—of very distinct character, the spectrum of such a vertical slice might indicate by its varying width that the light was not umformly con- stituted. Another point to be ascertained is whether all flames are con- stituted alike. This would require a more or less rapid glance at the spectra of several. I have spoken of “the three principal lines’’ because I saw no others. I have, however, heard rumours of a greater number having been seen by other observers, whether of equal brilliancy or not I do not know; but it inclines me to enforce the statement I have already made of “ three vivid lines—no more,’’ as seen with a narrow slit. I had no suspicion whatever of the presence of any but those three; and as I first saw them they were as sharp and bright as one could well wish to see. Whether the prominence which I looked at was the same as those in which more than three lines were seen I do not know. 42. Lieut. Campbells Observations satisfactory in their result. The determination of the polarization-plane of the corona is as satisfac- tory as can be desired, and Lieut. Campbell’s account is so clear that I have little to say about it. It is to be regretted that he did not see the effect of polarization all round at the same time, with a power low enough to in- clude the whole of the phenomena; but the view fortunately obtained with the higher power remedies this in great measure by showing what would have been seen at points 90° distant from that which he describes. 43. Results with Hand Spectroscopes unknown. With regard to the hand spectroscopes I have scarcely any report to make. Lieut. Campbell had no opportunity. Capt. Haig has sent no re- port. Neither have I heard anything of one of the two sent to sea. The only record I have received is that of Capt. Rennoldson, of the ‘ Rangoon,’ P. & O. Co.’s Steam Ship, which I enclose. He mentions having seen with the spectroscope a prominence not seen by others with (I presume) ships’ glasses of greater power. This is difficult to understand, except on the supposition that the light of the corona was weakened by dispersion, while that of the flame was not, or not in so great a degree. Should it turn out that the prominence he describes was a reality, it is barely possible that the above explanation may be the true one; in which case it suggests the possibility of seeing the prominences with a heavy battery of prisms when the sun is not eclipsed, especially if they are made of yellow glass; nay, even of seeing them, without the help of dispersion, through a medium calculated to stop all hght but that of the sodium flame. VOL. XVII. : K 120 Lieut. J. Herschel’s Account of the [Nov. 19, 44, Mr. Chambers prevented by Clouds from using two other Spectroscopes. Two other hand spectroscopes in my possession were lent to Mr. Chambers, Government Astronomer at Bombay, who stationed himself not far from Bégapur; but I am sorry to say he was denied the opportunity of using them by the clouds. Gentlemen, I beg to apologize for the length of my narrative, and to subscribe myself, with much respect, Your obedient Servant, J. Herscue., Lieut. R.E. Bangalore, Sept. 1868. LIEUT. CAMPBELL’S REPORT. ‘“‘T was deputed to accompany Lieut. Herschel on his expedition to ob- serye the phenomena of the total eclipse, and to use the instruments sup- plied by the Royal Society for the observation of polagens light in the corona and red flames. “The instruments in question were as follows :—A telescope of 3-inclz aperture, mounted on a rough double axis, admitting of motion in azimuth ‘and altitude by hand only, unaided by any appliance for clamping and slow motion. The telescope was provided with three eyepieces of magni- fying-powers 27, 41, and 98; and with it were furnished two analyzers for polarized light, viz. a double-image prism and a ‘ Savart’s polariscope.’ “The first gives two images of the object viewed, which, when polarized light is present, become strongly coloured with complementary tints, by whose changes, according to the position in azimuth of the analyzer, the plane of polarization may he found. “The second shows the presence of polarized light by the formation, across the image of the object viewed, of coloured bands, which alter in arrangement and intensity according to the position of the polariscope with reference to the plane of polarization, and hence afford a meaus of arriving at a knowledge of the latter. «With the former, slight polarization would probably be more readily recognized at aglance ; while with the latter the plane of polarization could be more easily and accurately determined. “To carry these aes I had a pair of jointed arms constructed, so at- tached by a collar and screw to the eye-tube of the telescope as to admit of the eyepiece being changed. Each arm carried one of the analyzers in a cell, in which a rotatory motion could be given for analyzing purposes. “Hither analyzer could in this way be brought instantly into position before the eyepiece of the telescope, or both could be turned aside and the telescope used. by itself at pleasure. ‘“‘Immediately behind the apparatus a circular piece of cardboard of about 12 inches diameter and neatly graduated was firmly attached to the eye-tube, and to each analyzer was affixed along pointer by which its 1858. Solar Eclipse of 1868. 121 ip azimuth could be referred to the graduations on the card circle, should measures of position or change of azimuth appear desirable. ‘I was also furnished with a hand spectroscope for direct vision. “The poimt chosen for my station was on the northern slope of a low range of hills, about 1} mile W. by 8. of Jamkandi. The flatness of the hills on top offered no point from which an uninterrupted view could be obtained in all directions; and from my station I only had a view of the northern half of the distant horizon over the plains extending in that di- rection for many miles, above the level of which I was raised about 200 feet, “‘ Marly on the morning of the 18th I proceeded to the spot, having pre- viously sent up the instruments and a tent for shelter in case of necessity. ** At sunrise the sky was beautifully clear, except in the northern horizon, where there were low clouds lying over the river Kistna. There wasa gentle breeze from S.W.by W. A little later light flocculent clouds began to rise and form in an arch overhead from west to east, continuing to in- crease as the morning wore on; then a light scud set in, and turned gra- dually into broken masses of thick dark clouds. ** Before the commencement of the eclipse I took observations for time with a small theodolite, from which I computed the error of my chrono- meter (a mean time one by M‘Cabe) to be 15 14™ 55*5 fast on local appa- rent time; and by that quantity I have accordingly corrected all observed chronometer times in the statements of time which follow. “Tl observed the first contact, which took place at 7° 45™ 13° (local apparent time), about 15° from the vertex; after which I watched the progress of the eclipse, and noted the times of occultation of three sun- spots. No. 1 was a large double ragged spot, No. 2 a small well-defined one, No. 3 also double, but not so large or distinct as No.1. After tota- lity I saw a fourth spot very near the sun’s limb. “During the progress of the eclipse I observed no unevenness in the moon's limb, nor any want of sharpness in the cusps, using magnifying- power 27. “The following notes were taken on the spot :— At first contact. Sun very slightly obscured by clouds. At 8° 0™. Clouds thick, and gathering from 8.W. and W. Wind higher and gusty. . At 8° 10". Clouds overhead, increasing and thickening and rising steadily from west. At 8" 20™. Sky nearly entirely overcast; clouds thickest in neigh- bourhood of sun. At 8° 25™. A clear break. At 8" 30™. I thought I could discern very faintly the dark limb of the moon beyond that of the sun; and at this time, making allow- ance for the general cloudiness, I did not perceive any decrease of light on the landscape. K 2 122 Lieut. J. Herschel’s Account of the [Nov. 19, At 8" 40". But ten minutes later the darkness was decided. At 8" 45™. Thick clouds well broken up, stil. gathered most closely in the region of the sun. Light becoming lurid, and merease of darkness very apparent. At 8° 52™. Cusps perfect (magnifying-power 27). ‘Closely before totality a bright line of light appeared to shoot out at a tangent to the mcon’s limb at its centre, as if running aeross the _ bright crescent of the sun (though of course not visible against the superior light) and extended beyond each cusp to a distance nearly, if not quite, 15’. [Note by Lieut. H. Thesketchin the margin represents Lieut. Campbell’s meaning, as asceriained oraily.] The corona became vi- sible immediately after, between the dark limb of the moon and the bright line. The corona did not appear so briglit as the line, the brilliance and whiteness of the light of which was most striking. This was seen through a highly smoked glass. At this period, probably not more than 3 to 5 seconds before totality ensued, a thick cloud shut out everything, and the rest of the phenomenon was only seen fitfully through openings in the clouds, for an aggregate period which I estimate at sumewhat less than half that of totality. “This alternate appearance and disappearance troubled me greatly, and gave rise to nervousness and excitement ; for owing to the imperfect mount- ing of my telescope I was apt to lose my place whenever the light was cut off by clouds, and to waste the precious moments of clearness m finding it agalil. ‘On the first opportunity after the commencement of the eclipse I turned on the double-image prism with the eyepiece of 27 magnitying-power, as recommended in the Instructions, which gave a field of abcut 45’ dia- ineter. A most decided difference of colour was at once apparent between the two images of the corona; but I could not make certain of any such difference in the case of a remarkable horn-like protuberance, of a bright- red colour, situated about 210 degrees from the vertex, reckoned (as I have done in all cases) with reference to the actual, not the inverted image, and with direct motion. I then removed the double-image prism and applied the Savart’s polariscope, which gave bands at right angles to a tangent to the limb, distinct but not bright, and with little, if any, appearance of colour. On turning the polariscope in its cell the bands, instead of appear- ing to revolve on their own centre, passing through various phases of - brightness, arrangement, &c., travelled bodily along the limb, always at right angles thereto, and without much change in intensity, or any at all in arrangement. “The point at which they seemed strongest was about 140° from the vertex, and I recorded them as black centred. “* Believing that with a higher power and a smaller field I should find it easier to fix my attention on one point of the corona and observe the phases 1868.) Solar Eclipse of 1868. 123 of the bands at that point, I changed eyepieces applying that of 41 power. With this eyepiece the first clear instant showed the bands much brighter than before, coloured, and as tangents to the limb at a point about 200° from the vertex; but before J could detcrmine anything further a cloud shut out the view, and a few seconds later a sudden rush of light teld that the totality was over, though it was difficult to believe that five minutes had flown by since its commencement. “T experienced a strong feeling of disappointment and want of success ; the only points on which I can speak with any confidence being as fol- lows :—(1) When using the double-image prism, the strong difference of colour of the two images of the corona, and the absence of such difference in the case of the most prominent red flame. (2) With the ‘Savart’s po- lariscope’ the bands from the corona were decided; with a low power they were wanting in intensity and colour; excepting alternate black and white, making it difficult to specify the nature of the centre; and their position was at right angles to the limb, extending over about 30° of the circumfe- rence. When the polariscope was turned the bands travelled bodily round the limb without other change in position or arrangement, as if indeed they were revolving round the centre of the sun as an axis. With a higher power, when a smaller portion of the corona was embraced, the bands were brighter, coloured, and seen in a different position, viz. tangents to the limb. “The appearance observed with a iow power seems exactly what might be expected, supposing the bands to be brightest at every point when at right angles te the limb, in which case the bands growing into brightuess at each succeeding point of the limb would distract attention from those fading away at the points passed over as tie analyzer revolved. “ After totality was over the clouds cleared away somewhat, and I watched the eclipse till its conclusion, noting the times of emersion of the spots and of last contact. ** A light shower fell at 9.30. “During totality several stars and planets were seen by those who were with me; and a fowl which I had placed near me, out of curiosity, was ob- served to compose itself to sleep. It was at no time so dark as I had ex- pected: after the total phase had commenced I read the chronometer and wrote notes in pencil without difficulty; and the light of a bull’s-eye lantern when thrown on my paper appeared somewhat dull. “The brilliance of the light of the corona when it burst out through the openings in the clouds astonished me. Also the very gradual decrease of light before totality, and the wonderful flood of light which followed the instant of the sun’s reappearance (though behind a cloud) were very striking. 7 “«] was too much occupied in watching the position of the sun, so as not to lose an instant of the precious intervals uf clearness, to see much of the general effect. I had no opportunity of using the hand spectroscope, 124: Account of the Solar Eclipse of 1868. [ Nov. 19, ‘There was no one in my neighbourhood (except those of my own party, who had been warned to keep silence), but when tctality commenced a wail- ing shout was heard in the distance, apparently rising all round us, which was succeeded after a few seconds by silence. “The distant features of the landscape disappeared, and I noticed one light (apparently a village fire) some miles distant. “I give below the different times I observed as of possible interest. Local apparent time is used :— First contact. Last contact. h m= Js h 7s Sin aud moon. ose f2 ee eee ee 10° 21-59 Spot Norio 2 a. eee 7 97 39 tga Entire disappearance .... 7 99 5 Spot Noi2s) fa). Sete ts 2 eee 9 54 39 SporaNons. 22h eee ee eee Oe 8 46 58 10° “aaa I cannot state with any approach to accuracy either the instant of com- mencement or [that of] termination of totality.” Patiude of shGoue a ee 16 30 10 Loncitudes 54 oes. See eee ia 2 (Signed) “W. R. Camppext, Lieut. R.E.” “ Bangalore, August 31, 1858.” True copy. J. Herscuen, Lieut. R.E. Bangalore, September 15, 1863. (Copy.) No. 886. From J. Geoghegan, E'sqy., Under Secretary to Government of India. To The Superintendent Lp the Great Trigonometrical Survey of India. Fort William, February 21, 1868. Sta,—I am fected to acknowledge receipt of your letter No. oe, of 4th instant ; requesting permission to employ certain officers of the Go- | vernment Trigonometrical Survey in taking observations of the total solar eclipse of the "17th, 18th August, and asking sanction to the expenditure on this account estimated sore not to exceed 2000 Rupees. In reply, Lam directed to state that the Governor-General in Council cordially approves of your proposed arrangements, and sanctions the ne- cessary expenditure. The Gover nment. of India, I am to state, will be prepared to do every- 1568. ] Capt. D. Rennoldson on the Solar Eclipse of 1868. 125 thing im its power towards securing full and accurate observations on this rare and important occasion. T have, &c., (Signed) J. GroGuHreayn, Under Secretary to Government of India. True copy. J. Herscuen, Lieut. R.E. [Commander Rennoldson’s letter, which was sent independently by the Secretary of the Peninsular and Oriental Steam Navigation Company ap- pears below. | *XI. “ Observations of the Total Solar Eclipse of August 18, 1868.” By Captain Cuartes G. Prerrins. Communiéated by Prof. Stokes. Received October 30, 1868. (Abstract.) These observations are contained in a letter dated ‘°S.S. ‘ Carnatic,’ Suez, 28th August, 1868,” addressed to the Managing Directors, Penin- sular and Oriental Steam Navigation Company. One of the hand spectro- scopes sent out by the Royal Society had been entrusted to Captain Perrins ; but as his ship at the time of the eclipse was about 20 miles north of the track of the total phase, he had no opportunity of using it for the observations contemplated. He thus describes the appearance at the time of greatest obscuration :— “That portion of the sun remaining uneclipsed consisted of a narrow streak (in shape like acrescent) of its upper left limb, in size about ;4; part of its diameter. The light emitted from this was of a very peculiar de- scription and difficult to describe, being at the same time extremely bril- liant and yet most remarkably pale. The high sea running appeared like huge waves of liquid lead, and the ghastly paleness of the light thrown upon it and all around revealed a scene which, for its weird-like effect, it would be as impossible to depict as it is to describe.”’ The slender crescent showed in the spectroscope several dark lines, as was to be expected. XII. “ Observations of the Total Solar Helipse of August 18, 1868.” By Captain D. Rennotpson. Communicated by Prof. Stoxss. Received October 30, 1868. (Copy-) From Captain D. Rennoldson. ‘Peninsular and Oriental Company, Bombay, 22nd August 1868. « Dear Srr,—lI enclose you a sketch of the eclipse seen on board the * This and the following three communications were transmitted by the Directors of the Peninsular and Oriental Steam Navigation Company. 126 Capt. D. Rennoldson on the Solar Kelipse of 1868. { Nov. 19, Rangoon’ on the morning of the 18th inst. The ship was at that time on the central line, viz. in lat. 15° 42’ N., long. 59° 15! E. “‘ The total eclipse lasted 4’ 8”. The sketch shows what was seen by a ‘large number of persons. In observing with the spectroscope, I saw what none of the others could see with their glasses, viz. two prominences on the right limb of the moon (showing in the spectroscope to the left) of a yellow flame-colour, immediately opposite to the red ones, the whole forming a square, with the moon in the centre, showing out likea mass of rock. The colour of the corona, as seen through the prism, was red, a yellowish green, blue, and violet,—the violet the brightest till the middle of the eclipse, when the red became lumpy and showed brighter. “The spectrum from the moon cut through the centre of this, but very faint, the red thrown out with a curve. “The motion of the ship was so great it was impossible to get minute observations ; so much haze and flying cloud, only Venus and one other star could be seen. «T return the spectroscope, and am only sorry I could not make more use of it. “Tam, &c., (Signed) ‘PD. RENNOLDSON, “Commander 8.8. ‘ Rangoon.’ ”” Capt. Henry, Superintendent P.§ O. 8. N. C., Bombay. [This letter was accompanied by four coleured sketches of the promi- nences and corona. Of these No. 1 shows a small low prominence extend- ing from about azimuth 144° to 150°, azimuths being measured in the di- rection of the motion of the hands of a watch, round the centre of the moon’s disk, from the highest point, and another low prominence from azimuth 160° to 180°. No. 2 shows a lofty prominence at azimuth 198°, curved in the upper part, with the concavity turned in the direction of in- creasing azimuth, and a low prominence from azimuth 332° to 345°. No.3 _ shows the long prominence at azimuth 202°, and the upper prominence at azimuth 320° to 338°. No. 4 shows the long prominence, reduced in height, at azimuth 212°, and the upper prominence at azimuth 230° to 255°. ‘The figures are thus described. | No. 1. A small red fiame or protuberance on the right-hand lower corner of the moon, visible for a few seconds before the sun was totally eclipsed ; disappeared a few seconds after. No. 2. 13” after commencement of total eclipse. A large red flame of - about 5’ of arc on lower left-hand corner, and a red flame or blotch on upper left hand —both visible from commencement of totality, and very bright. No. 3. 3" after commencement. ‘The long red flame rather shorter, and the upper one increased in size. No. 4. At reappearance of sun’s upper limb the upper protuberance dis- appeared ; the lower one was visible for about 10° after, about half its former size. 1868.] Capt. H. Welchman King on the Solar Eclipse of 1868. 127 XIII. “ Observations of the Total Solar Helipse of August 18, 1868.” By Captain Somervirts Murray. Communicated by Prof. Stokes. Received October 30, 1868. (Abstract. ) In accordance with the instructions he had received from the Managing — Directors of the Peninsular and Oriental Steam Navigation Company, Captain Murray made all observations that were possible of the eclipse of the 18th August; but the high northern latitude of the ship’s (‘ Ellora’) position at the time precluded the possibility of observing any remarkable phenomenon, the obscuration of the suu being comparatively shght. XIV. “ Observations of the Total Solar Eclipse of August 18, 1868.” By Captain Henry Wetcuman Kine. Communicated by Prof. Stokes. Received October 30, 1868. (Abstract. ) The weather was cloudy throughout, but the clouds were thin, so much so as to allow two or three stars to be seen during the time of totality. The corona exhibited itself quite suddenly on the instant of first totality. It presented the appearance of a golden-yellow brightness of no very in- tense brilliancy. It disappeared as suddenly as it appeared, on the first sign of the retirmg sun. The flames or prominences became visible simultaneously with the corona. The paper was accompanied by four coloured sketches, the first re- presenting the positions of the sun and moon, with the spots on the former, at an early stage of the eclipse, as observed with a 5-foot telescope by Ross of three inches aperture; the remaining three representing dif- ferent stages of the totality. The second figure shows a red prominence about 25° to the left or east of the lowest point, with a smaller green pro- minence, also in contact with the moon, a little distance to the east of it. The third shows a red prominence about 30° to the right of the lowest point. The fourth figure shows a broad prominence a litile to the left of the highest point. ‘The figures 2-4 are thus described :— Fig. 2. “ First instant of totality. This flame or prominence was visible during the whole period of totality by ordinary glasses. The prismatic colours to the eastward of flame I did not see myself, and cannot vouch for them.” Fig. 3. “Middle of totality. This flame or prominence visible during the whole period of eclipse to ordinary glasses.” Fig. 4. “‘ First reappearance of sun. I did not observe this flame in early stages of totality, though it may have been visible. It was observed by the above-mentioned Ross, and was not so brilliant as the others, though more extended. Entire power of the totality extended over 2 minutes 48 seconds.”’ The observations were made on board the steamer ‘ Rangoon,’ approxi- mate latitude 16° 44’ N., longitude 83° 55’ I. 128 Notice from the Chair of Anniversary Meeting. [Nov. 19, XV. “Supplementary Note on a Spectrum of a Solar Prominence.” By J. Norman Locxyer, F.R.A.S., in a Letter to the Secretary. Communicated by Dr. SuHarrgry, Sec. R.S. Received November 5, 1868. Str,—I have the honour, in continuation of my letter of the 20th ultimo, to inform you that I have this morning obtained evidence that the solar prominences are merely the expansion, in certain regions, of an envelope which surrounds the sun on all sides. I may add that other facts observed seem to point out that we may shortly be in a position to determine the temperature of these circumsolar regions. J. Norman Lockyer. XVI. “Spectroscopic Observations of the Sun.”—No. II. By J. Norman Lockyer, F.R.A.S. Communicated by Dr. Suarpzy, Sec. R.S. Received November 19, 1868. The reading of this Paper was commenced. November 26, 1868. Lieut.-General SABINE, President, in the Chair. In pursuance of the Statutes, notice was given from the Chair of the ensuing Anniversary Meeting, and the list of Officers and Ceuncil proposed for election was read as follows :— President.—Lieut.-General Edward Sabine, R.A., D.C.L., LL.D. Treasurer.—William Allen Miller, M.D., LL.D. y ee ( William Sharpey, M.D., LL.D. BEBE S | George Gabriel Stokes, Esg., M.A., D.C.L., LL.D. Foreign Secretary.—Prof. William Hallows Miller, M.A., LL.D. Other Members of the Council.—Frederick Augustus Abel, Esq. ; Sir Benjamin Collins Brodie, Bart., M.A.; William Benjamin Carpenter, M.D.; J. Lockhart Clarke, Esq.; Frederick Currey, Esq., M.A.; Warren De La Rue, Esq., Ph.D. ; Sir Wilham Fergusson, Bart.; William Henry Flower, Esq.; Capt. Douglas Galton, C.B.; John Peter Gassiot, Esq. ; John Hawkshaw, Esq. ; John Marshall, Esq. ; Joseph Prestwich, Esq.; George Henry Richards, Capt. R.N.; Archibald Smith, Esq., M.A. ; Lieut.-Col. Alexander Strange. — Lieut.-Col. Cameron, Mr. Crofton, Mr. Griess, and the Rev. Dr. Tristram were admitted into the Society. The following communications were read :— 1868.] Nordenskidld on the Swedish Arctic Explorations of 1868. 129 I. “Account of Explorations by the Swedish Arctic Expedition at the close of the Season 1868, in a Letter to the President.” By Professor A. NorpENSKIOLD. Communicated by the President. Received November 20, 1868. Tromso, October 23, 1868. Srr,—The second geographical part of our expedition anchored a few days ago in the harbour of Tromso, after a difficult and adventurous autumn cruise of a month in the polar basin north of 20° lat.; and as these regions were never before visited in such a late season, I hope that our observations will be of interest for the arctic men of Great Britain, as contri- buting to settle some points of the polar question recently much debated. According to the plan adopted for the Swedish Expedition, five of its naturalists returned, in the middle of September, to Tromso with one of the small ships that brought coal to our depot at Amsterdam Island, and the same day the ‘Sofia,’ with the remaining part of the expedition (consisting of vy. Otter, Berggren, Nystrém, Palander, Lemstrom, and myself), steamed northward for Seven Islands, where it was our intention to wait for a fa- vourable occasion to go further. But finding these islands so surrounded by ice that no anchorage was accessible, we were compelled to abandon this plan and go directly northward, following a tolerably large opening in the pack. After a cruise of some days among the ice we, on the 19th of Sep- tember, at 173° long. east of Greenwich, reached 81° 42’ N. Lat.; but, as may be seen by the adjoied photograph, the ice further northward was so closed that it was impossible even for a boat to advance. We turned westward, in vain looking for another practicable opening. Following the border of the pack, we were, on the 24th September, at a longitude of 2° W. already south of 79° lat., after often having passed fields of drift-ice covered with particles of earth, which seems to indicate that land is to be met with further northward. Despairing of finding the ice westward more favourable, and anxious to make a new survey later in the autumn of the position of the ice-field between 0° and 20° long., we returned to our coal-depot. North of 80° 30’ the season was already far more advanced than one would presume from the observations at Spitzbergen during the first part of September. The temperature of the air being —6° to —8° (Centigrade) below zero, the surface of the sea was, when calm, covered by a layer of new ice more than an inch thick; and after sunset the obscurity, increased by constant intense frost-rime, made the sailing or steaming among the ice both uncertain and dangerous. As the salt water has no maximum of den- sity, the freezing of the surface overadepth of 1000 to 2000 fathoms would be difficult to explain, were it not that the sea-water in the polar regions is bythe melting of the ice and the heavy autumnal snowfalls less salt, and accordingly lighter, even when at a temperature lower than that of the layers beneath. The last week of September was employed in filling our coal-boxes and refitting our steamer for a new struggle with the ice. During these days a strong easterly snow-storm prevailed, which made us hope to find the newly-fermed ice broken and the pack move dispersed than before. Our 180 Nordenskidld on the Swedish Arctic Explorations of 1868. | Noy.26, intention was to employ this favourable circumstance for making a last attempt to go northward, and if this should prove to be unsuccessful to winter at Seven Islands. This plan was frustrated by an accident similar to that which happened to the expeditions of Buchan and Ross in 1818. The calm that during the summer prevails in the Arctic Sea gave way after September 23rd to almost uninterrupted stormy weather, which caused such a violent and irregular sea on the border of the pack that it was impossible to advance without exposing the ship to be instantly erushed by the large rollig hummocks. Consequently we were obliged to lay to under the 81st parallel, waiting for better weather and a calmer sea. How- ever, everywhere on the surface of the sea large pieces of ice were scattered, dangerous by their rolling movement, their hardness (the temperature was —14° 5 Centigrade), and the obscurity that prevailed at night. Duringa couth-easterly storm on April 24 our steamer was so vehemently thrown against such a hummock that a large leak ensued, which foreed us to make as soon as possible for land. After hard work in keeping the steamer afloat, we reached Amsterdam Island, where the leak was provisionally caulked so as to enable us to reach a safer harbour in Kings Bay the follow- ing day. Here we had the ship down, ana the damage was repaired as well as possible. October 12 we left this harbour, going through a large field of new ice. Evidently the season was tuo far advanced for further enterprises to the northward; besides, our steamer, having got two rios broken, was no longer strong enough for a new encounter with the ice; and as a wintering only on Seven Islands could not be of an interest great enough to outweigh the loss of time, privations, and dangers unavoidably associated with it, we resolved to employ the yet toleravly open sea around the southern part of Spitzbergen to make an attempt toreach Giles Land. But being, at Thou- sand Islands, prevented by ice from penetrating further, we turned south- ward and reached Tromso, April 19, after having at Beeren Eiland sustained a severe storm, during which our steamer was gnite ice down by the waves that washed over. During our cruize in the polar basin interesting observations were ob- tained on the temperature, currents, &c. of the sea, and a number of care- fully examined deep soundings were made with an apparatus resembling the ‘Bulldog’ apparatus of M‘Clintock, by the intelligent and intrepid com- mander of the ‘Sofia,’ Captain Baron v. Otter, and I hope soon to be able to present you a copy of his map on these subjects, the position of the ice, &c- As you already know by the letter of Dr. Malmgren, the scientific re- sults of the first part of our expedition have been very satisfactory, and I hope also that its second part will give important information about several arctic questions. By the expeditions of Tschitschayoff (1765 & 1766), Phipps, Buchan, Franklin, Scoresby, Sabine, Clavering, Parry, ‘forell, &c., it was already long ago proved that in the summer compact masses of drift-ice prevented vessels from penetrating far into the polar basin. But during the most 1868.] Nordenskidld on the Swedish Arctic Explorations of 1868. 131 favourable season, 7. e. the time before the formution of new ice, no vessel had as yet made such an attempt. This was the aim of the Swedish Expedition, and it found— (1) That the polar sea is far more open in the autumn than at any other season of the year, but that even then the passage is soon stopped by dense ~ and impenetrable masses of broken ice. (2) That during the winter the polar basin is covered by an unbroken ice, and that the freezing of the surface begins as early as the end of Sep- tember. From September 23 to October 12 we had almost every day, either with the steamer or with boats, to cross new-formed ice. (3) That an autumn cruise north of 803° lat. is attended with unusual dangers, owing to the darkness and storms then prevailing, no ships being able a long time to sustain a night storm among large rolling pieces of ice and a cold of —15° Cent. If the ship has the good luck not to be more or less damaged by the constant unavoidable encounters with the ice mounts, it will soon by the immediate freezing of the washing waves be itself quite covered and pressed down by ice. (4) The idea of an open and comparatively milder polar basin is quite chimerical; on the contrary, 20’'—30' north of Spitzbergen a region of cold seems to begin which no doubt stretches far around the pole. (5) The only plan to attain the pole, from which success can be expected, is that adopted by most English arctic men, namely of going northward by sledges in the winter either from Smith Sound or Seven Islands. I remain, Sir, Your obedient humble Servant, A. E. NoRDENSKIOLD. P.S. As soon as the magnetical observations of Dr. Lemstrém shall be duly worked out I will send you a copy of them. Should you think it worth communicating this letter to the Royal Geographical Society, I beg you especially to inform its celebrated President, Sir R. Murchison, that besides other specimens interesting in a geological point of view (for instance, a mass of Miocene and coal plants, bones of Ichthyosaurus? &c.), we found a number of large fish fragments, probably belonging to the Devonian age, in the red slate of Liebde Bay, constituting the overmost layer of what I in my ‘Geology of Spitzbergen’ called Hecla block-formation. Accordingly Sir Roderick probably is right in sup- posing that the deeper layers of this ‘‘ formation” belong to the Silurian age. The underlying crystalline plates are evidently Laurentian. IJ. The reading of Mr. Lockyer’s Paper, ‘‘ Spectroscopic Observation of the Sun, No. II.,”? was resumed and concluded. (Abstract. ) Tue author, after referring to his ineffectual attempts since 1866 to ob- serve the spectrum of the prominences with an instrument of small dis- 132 Mr. J. N. Lockyer on Observations of the Sun. _—_ [ Nov. 26, persive powers, gave an account of the delays which had impeded the construction of a larger one (the funds for which were supplied by the Government-Grant Committee early in 1867), in order that the coinci- dence in time between his results and those obtained by the Indian ob- ‘servers might not be misinterpreted. Details are given of the observations made by the new instrument, which was received incomplete on the 16th of October. These observations in- clude the discovery, and exact determination of the Imes, of the prominence- spectrum on the 20th of October, and of the fact that the prominences are merely local aggregations of a gaseous medium which entirely envelopes the sun. The term Chromosphere is suggested for this envelope, in order to distinguish it from the cool absorbing atmosphere on the one hand, and from the white light-giving photosphere on the other. ‘The possibility of variations in the thickness of this envelope is suggested, and the pheno- mena presented by the star in Corona are referred to. It is stated that, under proper instrumental and atmospheric conditions, the spectrum of the chromosphere is always visible in every part of the sun’s periphery ; its height, and the dimensions and shapes of several pro- minences, observed at different times, are given in the paper. One promi- nence, 3’ high, was observed on the 20th October. T'wo of the lines correspond with fraunhofer’s C and F; another hes 8° or 9° (of Kirchhoff’s scale) from D towards HK. There is another bright line, which occasionally makes its appearance near C, but slightly less re- frangible than that line. It is remarked that the line near D has no cor- responding line ordinarily visible in the solar spectrum. ‘The author has been led by his observations to ascribe great variation of brilliancy to the lines. On the 5th of November a prominence was observed in which the action was evidently very intense ; and on this occasion the light aad colour of the lime at F were most vivid. This. was not observed all along the line visible in the field of view of the instrument, but only at certain parts of the line which appeared to widen out. The author points out that the line F invariably expands (that the band of light gets wider and wider) as the sun is approached, and that the C line and the D line do not; and he enlarges upon the importance of this fact, taken in connexion with the researches of Plucker, Hittorf, and Frankland on the spectrum of hydrogen—stating at the same time that he is engaged in researches on gaseous spectra which, it is possible, will enable us to de- termine the temperature and pressure at the surfaces of the chromosphere, and to give a full explanation of the various colours of the prominences which have been observed at different times. The paper also refers to certain bright regions in the solar spectrum itself. Evidence is adduced to show that possibly a chromosphere is, under certain conditions, a regular part of star-economy ; and the outburst of the star in Corona is eqpecuile dwelt upon. 1868. | Anniversary Meeting. 133 III. “ Extract from a Letter addressed by Cuas. Bassacz, Esq., F.R.S., to Dr. Bacne, of Washington, May 10, 1852. Com- municated by Mr. Bassace. Received November 26, 1868. « Tu reading the account of the great solar eclipse of last year (1851) I was much struck by the description of the pink excrescences apparently attached to the sun’s disk, and connected with its spots (see Proceedings of Royal Astronomical Society). They are only visible during a few minutes in a total eclipse. It occurred to me that it might be possible to render them visible at other times by two different inethods :— “Ist. By placing in the focus of an equatorial telescope moved by clockwork an opake disk, equal to or a little larger than the sun’s image. This would represent a continuous total eclipse; and if every known means of excluding light were adopted, it might be possible to see those faint pink objects, which are probably clouds raised by the eruption of solar volcanoes. ‘2nd. If this fail, it might yet be possible to render them visible by taking daguerreotype or photographic images. “It is really surprising that nobody has yet taken such images regularly, for the sake of recording the solar spots and their changes. “1 have no clock-moving equatorial myself fit for these observations, nor have I time to spare for them. “7 cannot persuade my countrymen that they are important, so you are at liberty to try them, or publish the plan on your side of the At- lantie. ‘““Mr. Gould will probably have explained to you an old plan of mime for mapping zones of stars without moving the eye from the telescope.” November 30, 1868. ANNIVERSARY MEETING. Lieut.-General SABINE, President, in the Chair. Mr. Newmarch, on the part of the Auditors of the Treasurer’s Accounts appointed by the Society, reported that the total receipts during the past year, including a balance of £495 10s. 3d. carried from the preceding year, amount to £4780 5s. 1ld.; and that the total expenditure in the same period amounts to £4286 11s. 5d., leaving a balance of £479 16s. 1d. at the Bankers’, and of £13 18s. 5d. in the hands of the Treasurer. The thanks of the Society were voted to the Treasurer and Auditors. The Secretary read the following Lists :— | Fellows deceased since the last Anniversary. Royal. His Imperial and Royal Highness the Archduke Louis of Austria (1264). 134: Anniversary Meeting. [ Nov. 30, On the Home List. Charles Dickson Archibald, Esq. Charles James Beverly, Esq. Capt. Benjamin Blake*. Rev. Miles Bland, D.D. Sir David Brewster, K.H., LL.D., D.C.L. Henry, Lord Brougham and Vaux, MA Rev. Jonathan Cape. Robert John, Lord Carington. Antoine Frangois Jean Claudet, Esq. The Right Hon. Sir George Clerk, Bart., D.C.L. John Crawfurd, Esq. Charles Giles Bridle Daubeny, M.D., LL.D. John Davy, M.D. Rev. Wiliam Rutter Dawes. George Douglas,Msq. (1853). | Sir William Francis Eliott, Bart. (1864). John Ellioctson, M.D. The Right Hon. Sir Edmund Walker Head, Bart. William Bird Herapath, M.D. Sir Charles Lemon Bart. Sir John Liddell, K.C.B., M.D. John Carnac Morris, Esq.* Rev. Henry Noel-Fearn, M.A., D.C.L. Robert Porrett, Esq. Archibald John, Karl of Rosebery, K.T., M.A, Li: The Ven. Archdeacon Tattam, D.D. Thomas Pridgin Teale, Esq. Nathaniel Bagshaw Ward, Esq. Alexander Luard Wollaston, M.B*. On the Foreign List. Marie Jean Pierre Flourens. Jean Bernard Léon Foucault. Julius Plicker. Jean Victor Ponecelet. Withdrawn. Rear-Admiral Thomas Edward Lawes Moore. Defaulters. Sir John Macneill. Edward Solly, Esq. he Right Hon. Charles Pelham Villiers. Fellows elected since the last Anniversary. John Ball, Esq., M.A. Henry Charlton Bastian, M.D. Lieut.-Col. John Cameron, R.E. Prof. Robert Bellamy Clifton, M.A. Morgan William Crofton, Esq., B.A. Joseph Barnard Davis, M.D. Peter Martin Duncan, M.B. John Peter Griess, Esq. Augustus G. Vernon Harcourt, Esq. Rear Ad. Astley Cooper Key, C.B. Rear-Admiral EK. Ommanney, C.B. James Beil Pettigrew, M.D. Laurence Parsons, Earl of Rosse. Edward James Stone, Esq., M.A. Rev. Henry Baker Tristram, M.A. Wm. 8. Wright Vaux, Esq., M.A. On the Foreign List. Theodor Ludwig Wilhelm Bischoff. Rudolph Julius Emmanuel Clausius. Hugo von Mohl. Samuel Heinrich Schwabe. Readmitted. Colonel John Le Couteur. * Date of decease unknown. 1868.] President’s Address. 135 The President then addressed the Society as follows :— GENTLEMEN, I nave the satisfaction of now laying before you the second volume of the Catalogue of Scientific Papers. The volume now completed carries on the list of titles in alphabetical order as far as Gra, inclusive. The Li- brary Committee, under whose superintendence the Catalogue is published, had hoped that the printing of the work would have made greater progress than it has done during the time that has elapsed since the appearance of the first volume ; but notwithstanding their earnest endeavours to attain that object, they found that, with due regard to the careful revision of the press, the rate of printing could not be materially accelerated. In fulfilment of the understanding with Her Majesty’s Government, explained in my Address last year, copies have been presented to various Scientific Institutions and individuals, according to a list drawn up by the Council, and approved by the Treasury. It is gratifying to know that in the numerous letters of acknowledgment received in return, as well as more publicly through the press, the value of the work as an aid to scientific research has been warmly recognized. As a special instance of this favourable expression of opinion, I would refer to the ample notice of the book written by our Foreign Member, Hofrath W. Ritter v. Haidinger, of Vienna, and circulated by him in different parts of Europe. Already of the remaining copies 120 have been sold. My last year’s Address contained an account of the proceedings of the Committee of the Royal Society, which, at the request of Her Majesty’s Government, had undertaken the reorganization and superintendence of the meteorological department of the Board of Trade. The year that has since elapsed has been employed, 1°, In perfecting the instrumental arrangements, and the systematic working of the staff, at the seven British Observatories which have been supplied, under the Committee’s direction, with continuously self-recording meteorological apparatus. For this pur- pose one or more of the staff of each Observatory has passed some days at the Central Observatory at Kew; and the Observatories themselves have been visited, some by Mr. Scott, the Director of the Meteorological Office in London, and all by Mr. Stewart, the Superintendent of the Central Observatory, and also by Mr. Beckley, the Engineer of the Kew Establish- ment. By these means it is hoped that uniformity of action on thoroughly well considered principles has been secured, and a considerable advance made towards the systematic record of the meteorological phenomena over the British Islands. The monthly records are now heginning to be re- ceived at the Office in London with regularity from all the Observatories, but have scarcely yet quite attained in all instances to that uniform accu- racy which it is hoped will be fully secured at the close of the present VOL. XVII. L 136 Anniversary Meeting. [ Nov. 30, year. The means and the methods by which the facts thus considerately and systematically obtained may be communicated to the public, in the form which may be at once suitable for the study of the weather pheno- mena over the very limited territorial area of the British Islands—and may at the same time contribute in the most satisfactory manner to the impor- tant investigations which are now in progress on the Continent of Europe regarding the periodic and non-periodic variations—will be the next point to which the careful attention of the Committee will be directed. 2°, In the branch of ocean meteorology the cooperation of several of our leading oceanic steam companies has been secured; and a large number of the commanders of their vessels are now actively engaged in the work of observing. Instruments have also been supplied to other masters of vessels of our mercantile marine, care being always taken that the reci- pients are both competent to observe and willing to do so regularly and accurately. The zeal and judgment displayed by Captain Henry Toynbee, the Marine Superintendent of the Office, in the selection of observers, has already begun to bear fruit in the marked improvement in the quality of the information in the registers which are now received compared with those which had previously accumulated in the office. The discussion of the material which has been thus collected and is still collecting is in pro- gress; but some time must elapse before a significant portion of the im- mense arrear can be advanced to such a stage as to afford a prospect of its speedy publication. ‘The staff of clerks is already fully occupied; so that the rate of progress cannot be much accelerated, unless the Committee find themselves in a position to devote more funds to this object than they are at present able to do. The special subject to which the attention of this department of the office has been first directed, is the discussion of information respecting the district of the Atlantic Ocean comprised between the parallels of 20° N. and 10°S., for which region it is in contemplation to ascertain the conditions of atmospheric pressure, temperature, and vapour tension, as well as the direction and force of wind, the character of the weather, and the surface temperature of the sea. These elements will be discussed for spaces of a single square degree in area for the different months. ; As regards the temperature of the surface of the sea (a subject so much dwelt on by the President and Council of the Royal Society in their letter to the Board of Trade of February 22, 1855), a very valuable series of monthly charts has been published by the Royal Meteorological Institute | of the Netherlands, exhibiting the temperature for each degree of latitude for the North and South Atlantic Oceans, and for the Indian Ocean. The Committee considered that a conversion of the data in these charts into British measures would be likely to be of immediate use to our own marine, and they have accordingly directed that a set of charts should be prepared in the first instance for the South Atlantic Ocean, exhibiting the Dutch results, as well as those obtained from the British registers received by the meteo- 1868. ] President?s Address. 137 rological department of the Board of Trade under its former management. These latter, however, were only calculated for spaces of five degrees Square. In addition, some of the work left in an unfinished state by Ad- miral Fitz Roy has been undertaken by the office at extra hours, and a series of wind-tables for the Atlantic have been ordered to be printed. The discussion of general meteorological information for the Pacific seaboard of South America is in a state far advanced towards completion. 3°. The system of telegraphic weather-intelligence, described in my last year’s anniversary address, has received a further development, and at present the Drum signal is hoisted at 97 British stations, to convey the intelligence of the existence of atmospherical disturbance in each case to such ports as may appear to the central office to be reasonably liable to be affected by it. Similar intelligence has been telegraphed to Hamburg since February 1868; and in the course of last month Herr von Freeden, the Director of the newly established meteorological office in that city (the Nord-deutsche Seewarte), has informed the London office that the harbour authorities on the Elbe have resolved to hoist the Drum signal at Ham- burg and Cuxhaven whenever intelligence implying probable danger shall be received from London. In France also the ministry of the marine has adopted, for the present at least, the practice of telegraphing facts and not prophecies, In addition to the telegraphic communications already referred to, the London Office sends, by special request, telegraphic intelligence of the e®istence of a certain amount of difference of barometric pressure between two stations within a defined area, to Mr. Rundell (Secretary of the Under- writers’ Association at Liverpool), and to the Dutch authorities. The in- fluence which the distribution of atmospheric pressure exerts on the motion of the air has been much dwelt upon by Dr. Buys Ballot, of Utrecht, and a rule has beeu propounded by him for inferring the coming direction of the wind from simultaneous readings of the barometer at different places. In order to lay the foundation of a systematic study of our weather, and, at the same time, to test the truth of this rule, it has been the practice of our meteorological office, for more than a year past, to prepare, and subject to systematic discussion, daily charts of the meteorological condition over the area embraced by the daily telegraphic reports which it receives, viz. the British Islands and a portion of the nearer continental coasts. The results of this investigation are on the whole encouraging, and favour the hope that with a more extended experience a real, if slight, advance will have been made in this most intricate but interesting inquiry. | The magnificent but rare phenomenon of a total solar eclipse is not more striking as a spectacle than interesting in a scientific point of view, from the precious opportunity it affords of gathering information, then only to be obtained, which bears on the constitution of our great lumi- nary. The corona which surrounds the dark body of the moon must have L2 138 Anniwersary Meeting. [ Nov. 30, been seen from the earliest times; but what does it import? Has it its seat in our own atmosphere, or in an atmosphere of the moon, or in some- thing surrounding the sun? and, in the latter case, is it self-luminous, or does it shine by reflected light? What, again, is the nature of those singular rose-coloured luminous objects seen just outside the dark disk of the moon, which were first brought prominently into notice by the obser- vers who watched the eclipse of July 7, 1842, and have subsequently been Seen on the occasion of total solar eclipses ? Evidence bearing in an important manner on the true answers to these questions had already been obtained on the occasion of former total eclipses. In that of July 18, 1860, M. Prazmouski ascertained that the light of the corona was strongly polarized in a plane passing through the centre of the sun, while that of the prominences was unpolarized. The fact of the polari- zation discarded the hypothesis, sufficiently improbable on other grounds, that the corona belongs either to our own atmosphere or to a lunar atmo- sphere (since in that case the light would be refiected or scattered at an almost grazing incidence), and proved it to belong to the sun, and to shine mainly, if not wholly, by reflected light. The absence of polarization in the light of the prominences proved that they are very probably self- luminous. The elaborate photographic observations of Mr. Warren De La Rue on the same eclipse proved, by the motion of the prominences rela- tively to the moon, that they belong to the sun, and showed that their light is remarkable for its actinie power. In the interval between this eclipse and that of the present year, a néW method of research had sprung up, in the application of the spectroscope to the celestial bodies, and already, in the hands of Mr. Huggins, had revealed in many of the nebule a constitution hitherto unsuspected. It was impor- tant to apply this method of research to the red prominences. Should they give a continuous spectrum, the conclusion would be that the matter of which they consist is probably in a solid or liquid condition, such as clouds formed by precipitation; should the spectrum be one of bright lines, we must conclude that they are glowing gas. To solve this important problem, independently of what might be done by other scientific bodies or by individuals, the Royal Society procured an equatorially mounted telescope, furnished with a spectroscope and clock- movement. With the sanction of Colonel Walker, R.E., Director of the Great Trigonometrical Survey of India, this instrument was entrusted to Lieut. John Herschel, R.E., who is attached to the Survey, and who, ~ being at the time in England, had the advantage of instruction from so skilful an observer as Mr, Huggins before his return to India. After his return to India, Lieut. Herschel worked diligently at the spectra of the southern nebuls, thereby at the same time making an important addition to our knowledge, and practising for the approaching eclipse. Four direct- vision hand-spectroscopes, intended for distribution to observers at dif- ferent stations, were also sent out,—partly that the occasion might not be 1868. ] President’s Address. 139 wholly lost in case clouds should prevent observations from being taken at the principal station; partly because a more rough and general view of the whole phenomenon might reveal features which would be missedin a more careful scrutiny of a particular part. Another telescope, furnished with analyzers for the examination of polarization, was also sent out; for from the shortness of the time at the disposal of an observer, it would be satisfac- tory that the results obtained, even by so skilful an observer as M. Praz- mouski, should be confirmed. The observations of the observers entrusted with these instruments were greatly impeded by flying clouds, notwithstanding which, however, important work was done. With the principal instrument, Lieut. Her- schel ascertained that the spectrum of the prominences showed three isolated bright ines—red, orange, and blue. He had time to take a good measure of the position of the orange line, which proved to be coincident with D, as nearly as the instrument could measure. Clouds prevented the measure of the blue line from being equally good; it proved, however, to be nearly coincident with F, apparently a very little less refrangible. With one of the hand-spectroscopes Captain Haig, R.E., observed the spectrum of the red prominences to consist of two bands, ‘‘ rose-madder” and ‘** golden yellow,” corresponding, doubtless, to the “red” and “ orange”’ of Herschel. But besides these, just before the emergence of the sun, Capt. Haig observed, “‘in the spectrum of the moon’s edge,” two well-defined bright bands, one green and one indigo. ‘he seizing of this almost mo- mentary phenomenon, establishing as it does the existence of a thin enve- lope of glowing gas (unless, indeed, the constitution thus revealed were merely local, and its occurrence just at the part of the sun first measured were a mere matter of chance), proves the advantage of not neglecting the use of a comparatively rough instrument intended for a general scrutiny of the phenomenon. Of the remaining hand-spectroscopes, one was entrusted to Mr. Cham- . bers, Director of the Bombay Observatory, but could not be used on ac- count of clouds, and two were placed in the hands of the commanders of homeward-bound steamers, belonging to the Peninsular and Oriental Steam Navigation Company. Capt. Charles G. Perrins, of the ‘ Carnatic,’ who had charge of one, was unable to apply it to the intended observa- tions, as his ship was about 20 miles north of the track of the total phase ; with the other, Capt. Rennoldson, of the ‘ Rangoon,’ ascertained the discontinuous character of the red prominences, and his observation would have been very valuable had clouds prevented observations from being taken on shore. The telescope furnished with analyzers was placed in the hands of Lieut. Campbell, R.E., who has fully confirmed the previous observation of M. Prazmouski relative to the strong polarization of the light of the corona. A feature of the prominences, which is specially noticed in Capt. Haig’s. 140 Anniversary Meeting. [Nov. 30 j account, resting on the observations of Capt. Tanner and Mr. Kero Laxu- man, who were of his party, is their streaked character. This had been noticed before, in the eclipse of 1860. Mr. Warren De La Rue, in speak- ing of the prominences, expressly mentions their structure; and M. Cha- ~cornac, who devoted himself to this object, has given a long description of their appearance*, which, however, is a little difficult to follow for want of a figure. The strong actinic power, the streaked character, and the bright-line spectrum of the prominences seem certainly to accord very well with the hypothesis in which they are regarded as gigantic auroree— a view, however, which may be rendered less probable by the apparently general prevalence over the sun’s surface of a lower stratum of similar nature, of which the prominences are merely elevated portions. The great Melbourne Telescope was despatched to its destination in an Australian packet (‘The Empress of the Seas’), which sailed from Liver- pool on the 18th of July last; and M. Le Sueur proceeded overland to await its arrival. The micrometer and spectroscope which are to follow are quite ready, and the photographic apparatus is also nearly ready, to be despatched to Melbourne. In June last the President and Council received from Dr. Carpenter and Professor Wyville Thomson letters strongly recommending that the Zoo- logy of the Deep Sea, especially in the North Atlantic Ocean, should be more thoroughly and systematically examined than has hitherto been ac- complished, and requesting the intervention of the Royal Society with the Admiralty for the purpose of obtaining the services of a vessel, with proper means and appliances for deep-sea sounding and dredging, to carry on a systematic research, in the seas immediately north of our own island, for a month or six weeks in the approaching autumn—and tendering their _own services to accompany the vessel. With the thoroughly efficient aid of the Hydrographer, Capt. Factaxas, R.N., the ‘ Lightning,’ surveying-ship, Staff-Commander May, was selected and Creonel expressly for this service; and Dr. Carpenter and Professor Thomson embarked in her on the 10th of August, at Stornoway. After examining the seas between Scotland and the Faroe Islands, the ‘ Light- ning’ returned on the 9th of September to Stornoway, to land Professor Thomson (whose presence was required elsewhere), and sailed again (this time accompanied by Dr. Carpenter only) for a second, more westerly - eruise, which lasted until the 26th of September. A preliminary report of the results has been received from Dr. Car- penter, and will be read to the Society at an early evening meeting in the present session; I will only venture to anticipate the contents of this very valuable report so far as to say that it will be found of very high interest both in respect to the temperature of the sea at great * Le Verrier’s ‘ Bulletin’ for Sept. 4-8, 1860. 1868. ] President’s Address. 14] depths, and to the nature of the sea-bottom, and the life existing in its vicinity. . ; The report strongly recommends the continuation and extension of these researches—a recommendation which in due time will require and receive the attention of your Council, who may confidently anticipate _ that should a further application to the Admiralty be deemed desirable it will receive favourable consideration, and, if approved, will be secure of the same cordial and invaluable cooperation on the part of the Hydrographer as that which has been enjoyed on this occasion. We have to rejoice in the safe return of the Swedish and North-German Expeditions, engaged in the past summer in the endeavour to extend the domain of Arctic Exploration to the north and to the west. Though the limits previously attained have not been passed in either direction, much valuable information has been obtained regarding the Natural History of Northern Lands, as well as many important facts bearing on the Hydro- graphy of the Arctic Seas; while an experience has been gained in Arctic navigation, and habits acquired of surmounting the difficulties which it presents, that may yield good fruit hereafter. The Arctic explorations of the Swedes included, from their commence- ment, the design of accomplishing such a preliminary survey of Spitz- bergen as might solve the question of the practicability of the measure- ment of a degree of the meridian in that high latitude. The idea of such an undertaking having originated in this country and in this Society more than forty years ago, it is natural that we should regard the steps taken towards its accomplishment with a lively sympathy. A sketch of what was effected in 1861 and 1864 by MM. Chydenius, Diiner, and Nordenskiold, communicated to the Royal Society by Captain Skogman, of the Royal Swedish Navy, was printed in the Proceedings of December 1864. An official and elaborate Report has since been published (in Sept. 1866) by the Royal Swedish Academy, entitled ‘‘ Forberedande Undersékningar rorande Utforbarheten af en Gradmatning pa Spetsbergen” (preliminary researches touching the facilities for a measurement of a degree at Spitz- bergen), by MM. Diiner and Nordenskiold (Chydenius having unfortunately died). In the Map accompanying the Report the triangles are laid down which connect the extremes of land, and comprehend an arc of about 4° 11’. One of the objects contemplated by the expedition which has just returned was, to examine the possibility of the extension of the arc to lands existing to the north of the north-easternmost part of Spitzbergen—a question, however, which cannot be regarded as yet perfectly solved, the northern progress of the ‘ Sophia’ having been stopped by ice, which is described by M. Nordenskiold as “ consisting in part of fields of drift-ice, covered with particles of earth, which seems to indicate that land is to be met with further north.” Should these preliminary researches and surveys eventuate in a Scandi- 142 Anniversary Meeting. [ Nov. 30, navian are-measurement at Spitzbergen, I need scarcely say with what interest such an undertaking would be regarded by this country and by its Royal Society. With reference to the operations of the Committee, appointed at the Nottingham Meeting of the British Association, for the Exploration of the Tertiary Plant-beds of North Greenland, it was stated in my last Address that a large collection of fossil plant-remains had been brought from Greenland by Mr. Edward Whymper. The entire collection has been sent, for examination and description, to Prof. Oswald Heer, of Zurich, who has already published a work, ‘ Flora Fossilis Arctica,’ containing the results of his examination of the fossils brought at various times from Greenland and other parts of the arctic regions and deposited in the museums of this country and of Denmark and Sweden. The Committee, finding that their funds were exhausted, made a fresh application to the Government-Grant Committee, and received an ad- ditional sum to defray the expense of carriage of the specimens to and from Zurich. The collection was forwarded to Switzerland at the end of last year; and within the last week Prof. Heer has sent the description of the fossils to London, with the view of submitting it to the Royal Society. The localities which were examined by Mr. Whymper were situated on the shores of the Waigat, at two points on Disco Island, and at Atane- kerdluk, on the mainland of Greenland. From Disco, whence specimens had only once been obtained before (by Dr. Lyall), 14 species were procured. Among them the occurrence of two cones of Magnolia present the greatest interest, as they prove to us that -an evergreen, such as Magnolia, could ripen its fruit at the high north lati- tude of 70°. . The collection from Atanekerdluk is especially rich, but this locality was well known before; the number of species from it in this collection is 73. Among the most important of these are the flowers and fruit of a Chestnut, proving to us that the deposits which contain them must have been formed at different seasons, corresponding to the times of flowering and fruit of the Chestnut. The collection is not rich in animal remains; however, some insects have been noticed, as well as a freshwater bivalve, probably “ Cyclas.2 The results of this expedition have been eminently satisfactory, whether we look to the number of new species discovered, or to the additional facts, confirmatory of previous determinations, which have been ascertained. This latter remark is of special importance when we find that the identi- fication of a tree by means of its leaves has been supported by the sub- sequent discovery of its flowers and fruit. The number of fossil species of vegetable remains discovered in Green- 1868.] _ President’s Address. 143 land has increased to 137, of which 46, or exactly one-third, belong to it in common with the’ Miocene deposits of Europe. Four of these are found in our own Bovey Tracey beds, which have been already described by Prof. Heer in the ‘ Philosophical Transactions.’ Among these is Sequoia Couttsie, the commonest tree in the British locality. Accordingly the age of the Greenland deposits has been fixed beyond a doubt as Lower Miocene. The collection itself is expected to arrive in London shortly, when a complete series of the specimens will be deposited in the British Museum, in accordance with the terms prescribed by the British Association and the Gorernment-Grant Committee of the Royal Society. The redaction of the great scientific work, the Magnetic Survey of the South Polar Regions—commenced in 1839, under the auspices and at the expense of Her Majesty’s Government—has been completed in the present year by the presentation to the Royal Society, and the publication in the Philosophical Transactions, of Maps of the three Magnetic Elements in Southern Parallels, commencing in 30° south, and extending far beyond the limits of ordinary navigation. These Maps are accompanied by Tables containing the numerical coefficients to be employed in a revision of ‘ Gauss’s General Theory,’ at the intersection of every fifth degree of lati- tude and every tenth degree of longitude, between 30° south latitude and the south terrestrial pole. The magnetical determinations of the Survey correspond to the epoch 18423. Similar Maps for the corresponding latitudes of the Northern Hemisphere, from 30° north latitude to the north terrestrial pole, are in preparation, founded on a coordination of results obtained by magneticians of all countries in the fifteen years preceding and the fifteen years following the same mean epoch of 18424, and reduced to it. It is hoped that these Maps, with an accompanying Memoir, will be presented to the Royal Society before the close of the present session. There will then remain for subsequent completion the filling up (still for the same epoch) of the space between the parallels of 30° north and 30° south latitude, for which much preparation has been made in the assem- blage of materials, requiring only, for their coordination, the allotment of the time needed for the due examination and treatment of so large a body of materials. Should I be so happy as to be able to complete this task aiso, (my occupation in Terrestrial Magnetism has now extended, more or less, over half a century,) I venture to express a hope that the great work of which the foundation will thus have been laid, viz. “the Revision of the Gaussian Theory, corresponding to a definite epoch in the great cycle of terrestrial magnetism,’ may, when a suitable time shall appear to have arrived, be taken up and completed under the auspices of the Royal Society. Whilst on the subject of Terrestrial Magnetism, I may remark that, in a recent number of his ‘ Wochenberichte,’ Dr. Lamont has called the 144 Anniversary Meeting. [ Nov. 50, attention of magneticians to the probable occurrence of the epoch of max- imum of the magnetic disturbances at the end of the present year 1868, in accordance with the hypothesis of a decennial period, and has noticed the already great increase in the number of days of unusual magnetic disturbance observed at Munich in the months of August, September, and October last. Coincidently with Dr. Lamont’s experience in this respect, the continuous records of the magnetometers at Kew have shown larger and more frequent magnetic disturbances than usual; and the Photoheliographs, taken there on all days when the sun is visible, have shown larger and more numerous groups of sun-spots. It may be worthy of remark in this connexion, that 1868 is the fourth decennium since the occurrence of the first well-ascertained maximum of magnetic disturbance ; I mean that which, resting on the authority of Arago’s admirable and systematic series of observations (1821-1830), has been shown to have taken place in 1828*. It may be proper, however, to await the more decisive evidence which the years 1873 to 1879 may afford, as to the preference to be given to either of the periods assigned by different magneticians (respectively 10 and 11, years) as the dura- tion of this remarkable phenomenon, which appears to attest the simul- taneity of physical affections of the sun and of the earth. If the decen- nial hypothesis be correct, 1873 will be the year of minimum, and 1878 that of maximum; if, on the other hand, the period be one of 11 years and a small fraction, 1873 should be the year of maximum, and 1878 the year of minimum; and the order of progression and sequence be reversed. I mentioned in my last year’s Address that the operations of the Bombay Observatory were delayed by the non-reception of the necessary self-recording magnetical and meteorological instruments of the best modern construction. Iam glad to be able to state on this occasion that a communication which I ventured to make to Sir Stafford Northcote, Secretary of State for India, had the immediate effect of removing the difficulty which had intervened, and that advice has recently been received of the safe arrival of these instruments at Bombay. We may now con- fidently anticipate that, under the able and zealous superintendence of Mr. Chambers, the Bombay Observatory will speedily take a place in the first rank of institutions specially devoted to these two branches of Phy- sical Science. A paper of considerable interest and importance, entitled “Scientific Exploration of Central Australia,” was presented to the Society in April - last. The geographical and scientific researches of its author, Dr. Neu- mayer, published under the authority of the Victorian Government, attest his competency to discuss a subject of this magnitude in its various points of view. The paper itself is an able and interesting one; it contains the * Avago, Meteor. Essays, English Translation. Longman, 1855. Editor's Note, pp. 355-357. 1868. ] President’s Address. 145 outline of a large and apparently well-considered scheme, with estimates and other essential details ; it contemplates an expedition to last three or four years, starting from the eastern shores of Queensland, and termi- nating in an exploration of. the western portion of the Australian conti- nent ; and he offers his own services for the conduct of such an underta- king. Should the plan find favour with the different Australian Colonies who would bear its expense and reap the chief material advantage of its results, there can be no doubt of its producing a rich harvest in physical geography and natural history, and as little doubt of the warm interest it would command in the Scientific Societies of the mother country, espe- cially in the Royal Society, and of the pleasure with which they would give to it every assistance in their power. I proceed to the award of the Medals. The Copley Medal has been awarded to Sir Charles Wheatstone, F.R.S., for his researches in Acoustics, Optics, Electricity, and Magnetism. The researches of Sir Charles Wheatstone in acoustics, optics, elec- tricity, and magnetism, numerous and important as they are, have already taken their place as integral parts of science, and have become so com- pletely incorporated into its teaching that it will be hardly necessary on the present occasion to do more than enumerate the leading ones, in recognition of which the Copley Medal has this year been awarded. The earliest of these researches in point of time were those connected with acoustics ; and among these we may mention a paper on the trans- mission of sound through solid conductors, which (in 1828) describes the means discovered by the author of transmitting musical performances to distant places, where they are made audible by sounding-boards through the intervention of wires or wooden rods. His paper on the acoustic figures of vibrating surfaces was published in the ‘ Philosophical Transactions’ for 1832. In this the laws of the for- mation of the varied and beautiful figures discovered by Chladni were first traced. His subsequent invention of the Kaleidophone furnished him with an elegant means of showing optically the coexistence of different forms of vibrations in sounding bodies. His wave-machine furnished a still more complete method of demon- strating the composition of undulations by mechanical means. In optics his contrivance of the Stereoscope and the Pseudoscope, and his discussion of the modes in which binocular vision is effected, described in the ‘ Philosophical Transactions’ for 1838 and 1852, were even more ingenious and important, as showing us how we obtain a perception of solidity or relief, or of its reverse, by the simultaneous observation of two plane images. | Another ingenious optical invention was the Polar Clock, described to the British Association at their Meeting in 1849. This is an instrument 146 Anniversary Meeting. [ Nov. 30, which indicates the time by means of the changes of polarization of the blue light of the sky in the direction of the pole, founded on the discove- ries of Arago and Quetelet. In 1835 he communicated to the British Association a paper on the Prismatic Analysis of the Electric Light, proving that the electrie spark from different metals presents for each a different spectrum, exhibiting a definite series of lines, differing in position and colour from each other, and thus enabling very small fragments of one metal to be distinguished with certainty from all the others. This was a starting-point in a new and fertile field of physical inquiry which has abundantly rewarded the labours of subsequent investigators. But no series of his researches have shown more originality and inge- nuity than those by which he succeeded in measuring the velocity of the electric current and the duration of the spark. The principle of the ro- tating mirror employed in these experiments, and by which he was enabled to measure time to the millionth part of a second, admits of appli- cation in ways so varied and important that it may be regarded as having placed a new instrument of research in the hands of those employed in delicate physical inquiries of this order. Scarcely less valuable are the instruments and processes which Sir Ch. Wheatstone devised for determining the constants of a voltaic circuit, in- cluding, among others, the rheostat and the differential resistance mea- surer (or Wheatstone’s bridge, as it is usually called), which, in one or other of its modifications, is become an indispensable means of measuring the resistance of telegraphic wires and cables, as well as for determining electromotive forces. The description of these methods is contained in a paper in the ‘ Philosophical Transactions ’ for 1843. But it is with the Electric Telegraph that the name of Sir C. Wheatstone is in the public mind most completely identified ; and ever since the first messages were transmitted along the Great Western Railway by insulated copper wires enclosed in iron tubes, to the present day—when a network of copper wires insulated by means of caoutchouc is suspended across our public thoroughfares for the instantaneous transmission of intelligence, not merely from one district to another in our large towns, but from one continent and capital to another—Sir C. Wheatstone has not ceased to contribute the most important aid towards perfecting the means of electro- telegraphic communication. A bare enumeration of these various inventions would carry us beyond our limits on the present occasion. In 1840 he devised a cable adapted for transmitting intelligence under the sea; and it is to him that we are indebted for the Alphabetic Dial Telegraph working without any clock- power, and in which a magneto-electric machine supplies the place of a voltaic battery. These instruments were first used in the Paris and Ver- sailles Railway in 1846. A more recent invention is his High-Speed Telegraph, in which the 1868. | President’s Address. 147 messages, previously prepared on slips of paper, are, by passing through a very small machine constructed somewhat on the principle of the Jac- quard Loom, made to print the messages at the remote station, in the ordi- nary telegraphic characters, with a rapidity unattainable by the hand of an operator. Allied to these inventions are others where electro-magnetism is the © motive power, as, for example, the electro-magnetic clock for telegraphing time, a modification of which has since been employed to aid in deter- mining the longitude of distant places; also the Chronoscope, for mea- suring the velocity of projectiles or falling bodies. In this enumeration of his discoveries, inventions, and researches, we have passed over many, such as his speaking machine, the investigation of Fessel’s Gyroscope, his experiments in illustration of Foucault’s proof of the rotation of the earth, and others. More than enough, however, has been stated to justify the presentation of the Copley Medal on this occasion to our eminent fellow-countryman. Sir Cuartes WHEATSTONE, I have the very agreeable duty of presenting to you this Medal, which you will receive as a testimony of the sense so universally entertained by your countrymen, and specially by the Fellows of the Royal Society, of the high scientific merit and practical value of your many discoveries and inventions, and of their varied applications. The Council has awarded a Royal Medal to the Rev. Dr. George Salmon, Regius Professor of Divinity in the University of Dublin, for his original investigations on Analytical Geometry, published in the Transactions of the Royal Irish Academy and in the Philosophical Transactions,—and, specially, for his solution of the problem of the degree of a surface reci- procal to a given surface—and for his researches in connexion with surfaces subject to given conditions, analogous to those of Chasles in plane curves. yen Besides the original investigations thus referred to, Dr. Salmon is the author of a series of works on Conic Sections, on higher Plane Curves, on Geometry of Three Dimensions, and on higher Algebra (the modern Analysis), full of original matter of great value to the advanced mathe- matician, and at the same time adapted to the requirements of the student. These works have become widely spread as text-books through- out Europe; and the estimation in which they are held is attested by the fact that they have already been translated into French, German, Italian, and Russian. Dr. Sarton, I have the pleasure of presenting you this Medal in testimony of the 148 Anniversary Meeting. [Nov. 30, high estimation in which your attainments and labours in the higher branches of mathematics are held by the Royal Society. A Royal Medal has been awarded to Mr. Alfred Russell Wallace, in re- cognition of the value of his many contributions to theoretical and prac- tical zoology, among which his discussion of the conditions which have determined the distribution of animals in the Malay archipelago (in a paper on the zoological geography of that region, published in the Proceedings of the Linnean Society for 1859) occupies a prominent place. The case may be briefly stated thus:—The strait separating the islands of Baly and Lembok is only fifteen miles wide ; nevertheless the animal inhabitants of the islands are widely different, the fauna of the western island being substantially Indian, that of the eastern as distinctly Australian. Mr. Wallace has described, in a far more definite and complete manner than any previous observer, the physical and biological characters of tue two regions which come into contact in the Malay archipelago; he has given an exceedingly ingenious and probable solution of the difficulties of the problem, while his method of discussing it may serve as a model to future workers in the same field. Another remarkable essay, “On the tendency of Varieties to depart indefinitely from the Original Types,” published in the Proceedings of the Linnean Society for 1858, contains an excellent statement of the doctrine of Natural Selection, which the author, then travelling in the Malay ar- chipelago, had developed independently of Mr. Darwin; and, apart from its intrinsic merits, this paper will always possess an especial interest in the history of science, as having been the immediate cause of the publica- tion of the ‘ Origin of Species.’ Mr. Wallace’s ability as an observer and describer of animal forms is shown in his numerous and valuable contributions to our knowledge of the animals, and especially the Pigeons, Parrots, and Butterflies, of the Ma- layan region. It must not be forgotten that a knowledge of the circumstances under which the majority of these contributions to the higher branches of zoolo- gical science were made must greatly enhance our respect for the author. Mr. Wallace has spent the greater part of his life amidst the exhausting and often dangerous fatigues of a traveller in tropical countries rarely ex- plored by Europeans ; and some of his most valuable papers are dated from places which some might consider so little favourable to study as — Ternate and Sarawak. | Mr. WALLACE, I have the pleasure of presenting to you this Medal in recognition of the great merit of your researches both in practical and theoretical Zoology, carried out in countries where such pursuits are necessarily presen with more than usual difficulties and dangers. 1868. ] President’s Address. 149 The Rumford Medal has been awarded to Mr. Balfour Stewart, for his researches on the qualitative as well as quantitative relations between the powers of emission and absorption of bodies for heat and light, published originaliy in the Transactions of the Royal Society of Edinburgh and in the Proceedings of the Royal Society of London, and now made more generally accessible by the publication, in 1866, of his treatise on heat. When a body is placed within an opaque envelope which is kept at a constant temperature, it soon acquires the temperature of the envelope— and that, whatever be the nature or form of the envelope or of the body. The same is true if any number of bodies of different kinds be placed within the envelope; in the permanent state each of the bodies attains a fixed temperature, the same as that of the walls of the envelope. The equilibrium of temperature is not, however, of the nature of statical equi- librium; according to.the theory by which Prevost so beautifully ex- plained the apparent radiation of cold, each body radiates heat all the while, at a rate depending only on its nature and temperature, and not at all on its environment; and it is because the other bodies and the enve- lope are also radiating heat, and the first body absorbs a portion of the radiant heat thus falling upon it, that its temperature remains unchanged. The equality of radiation and absorption follows as a simple corollary. It had long been known that rock-salt is remarkable for its trans- parency for obscure radiant heat. According to Melloni, a plate of rock- salt of the thickness of three or four millimetres transmits 92 per cent. of heat-rays from whatever source. Now, on measuring by the thermo- pile the radiation from thin and thick plates of rock-salt, as well as from two or more plates placed one behind the other, all being heated up to a definite temperature, Mr. Stewart found that the radiation from a thick plate, or from many plates, was, indeed, greater than from a thin plate or from a single plate, but that the difference was not by any means so great as it ought to have been on the supposition that the heat radiated by the hinder portion of a thick plate, or by the hinder plates of a group, passed through the front portion of a thick plate, or through the front plate of a group, as freely as obscure heat would have passed which was radiated by lampblack or most other substances. It thus appeared that rock-salt at any temperature is by no means transparent to heat radiated by rock-salt of the same temperature—that it exerts a preferential absorption on rays of the quality of those which it emits. This conclusion was confirmed by using a plate of cold rock-salt as a screen by which to sift the heat-rays falling on the thermopile. It was found that a much larger proportion of the heat was stopped by the screen when the source of heat was a plate of heated rock-salt than when it was a body coated with lampblack. The proportion stopped was also sensibly greater when the source of heat was a thin than when it was a thick plate of rock-salt, the reason being that the heat radiated from the hinder portion of a thick plate was partially sifted, in passing across the front portion, before it reached the rock-salt 150 Anniversary Meeting. [ Nov. 30, screen, and therefore was transmitted by it in greater proportion than the heat which radiated from the front portion. Similar conclusions were obtained from experiments on glass and mica, though the numerical results were not so striking, in consequence of the comparatively great opacity of those substances for obscure radiant heat. It thus appeared, 1st, that the heat radiated by a body is not confined to that which comes from the immediate neighbourhood of the surface, but emanates from various, in the case of rock-salt considerable, depths ; 2ndly, that there is a relation between the quality of the heat radiated and that absorbed by any given element of a body, and consequently by a sufficiently thin plate of a body, of such a nature that the kind of heat most freely radiated is also most freely absorbed. These results and others were comprehended by Mr. Stewart in a definite theory, by means of his extension of Prevost’s theory of ex- changes. According to this extension, the stream of radiant heat within a uniformly heated enclosure is the same throughout in quality as well as quantity; 2.¢. the uniformity of radiation exists for each kind of heat in particular of which the total flux is made up. Few now can doubt the identity of nature of radiant heat and light ; and, accordingly, the application to light of the extension of Prevost’s theory was an obvious step. This step was taken by Mr. Stewart, who verified by experiment that which theory predicted—that a coloured glass when heated, as compared with an opaque body glowing at the same tem- perature, gives out by preference rays of the kind which it absorbs, and consequently tends to glow with a colour complementary to its own. For a similar reason a plate of tourmaline cut parallel to the axis, when heated, and viewed in a direction perpendicular to the axis, is seen to glow with light which is partially polarized in a plane parallel to the axis. It is right to mention that, in regard to the extension of Preyost’s theory in its application to light, Mr. Stewart was slightly anticipated by Professor Kirchhoff, whose brilliant application of the theory to the lines of the spectrum has attracted general attention, whose researches, however, had hardly, if at all, reached this country when Mr. Stewart’s papers were presented. As regards Radiation, however, without specifying of what kind, the priority in the extension of Prevost’s theory belongs to Mr. Stewart, whose papers on Heat were published before those of Professor Kirchhoff, to whom, however, they were not known when he published his earlier papers. Mr. STewakt, : I have particular pleasure in presenting to you this Medal, tse it will testify to you that all that really conduces to the advance of our knowledge meets sooner or later with its due recognition—and because I hope that this tribute to your earlier labours will be especially agreeable to you now that you are engaged in work of high public value, but which must necessarily leave you little leisure for such original researches. 1868. ] Anniversary Meeting. | 151 On the motion of Sir Charles Lyell, seconded by Sir Thomas Watson, it was resolved,—‘ That the thanks of the Society be returned to the President for his Address, and that he be requested to allow it to be printed.” The Statutes relating to the election of Council and Officers having been read, and Sir Edwin Pearson and Mr. Erasmus Wilson having been, with the consent of the Society, nominated Scrutators, the votes of the Fellows present were collected, and the following were declared duly elected as Council and Officers for the ensuing year :— President.—Lieut.-General Sabine, R.A., D.C.L., LL.D. Treasurer.—Whilliam Allen Miiler, M.D., D.C.L., LL.D. A f William Sharpey, M.D., LL.D. | George Gabriel Stokes, Esq., M.A., D.C.L., LL.D. Foreign Secretary.—Prof. William Hallows Miller, M.A., LL.D. Other Members of the Council.—Frederick Augustus Abel, Esq. ; Sir Benjamin Collins Brodie, Bart., M.A.; Wilham Benjamin Carpenter, M.D.; J. Lockhart Clarke, Esq. ; Frederick Currey, Fi:q., M.A.; Warren De La Rue, Esq., Ph.D.; Sir William Fergusson, Bart.; Wilham Henry Flower, Esq.; Capt. Douglas Galton, C.B.; John Peter Gassiot, Esq. ; John Hawkshaw, Esq.; John Marshall, Esq.; Joseph Prestwich, Esq. ; George Henry Richards, Capt. R.N.; Archibald Smith, Esq., M.A.; Lieut.-Col. Alexander Strange. 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" bO1-96 ‘SON ‘SSUTpPooOA OF4ICT Westin: Srrecteaen ee aatrakie qae (9 8 | 60P a ‘1981 TL Wd ‘nuout ai: beam 96 COO CaCI nC ana air ir SenCrieiCar ica aCe ae a esos eee ewes eeenee OVP Surpulg, al Ce ee ee Oem eee eee ee i iy revenseues ssa (TRACI Ut LOF syoog A ae sa ae SEE MEMO SSN" Ch qUsloay pue VIPUT LOZ syMOUUNASUT rane CCR CO CORSON TC MCL IO TERETE CICLIPISTORC IIE For continuation of Contents see the 4th page of Wrapper. 1869. ] Prof. Owen on the Cavern of Bruniquel. 201 January 7, 1869. Lieut.-General SABINE, President, in the Chair. The following communications were read :— I. “Description of the Cavern of Bruniquel, and its Organic Con- tents.—Part II. Equine Remains.” By Professor Owen, F.R.S. Received August 20, 1868. (Abstract. ) In this paper the author has selected the fossil remains of the Equine family as the subject of the second part of his Description of the Cave of Bruniquel and its contents, which Cave, with the human remains, was de- seribed in Part I. communicated to the Royal Society, June 9, 1864. He premises a definition of the several parts of the grinding-surface of the upper and lower molars and premolars in the genus Hquus, homolo- gizing them with those in the corresponding teeth of Hipparion, Paloplo- therium, and Paleotherium. Next, referring to the want of figures of the natural size, or of any figures of the characteristic surface of the teeth of the molar series in the known species of the existing Equines, the author gives a description thereof in the Horse (Equus caballus), Ass (H. asinus), Kiang (2. hemiconus), Quagga (L. quagga), Dauw (£. Burchelli), and Zebra (EF. Zebra), indica- ting by comparison their respective characteristics. These descriptions are accompanied with drawings (of the natural size) of the working-surface of the dentition of each species, with lettered details of such surface in the teeth of both upper and under jaws. The Equine fossils from the Cave of Bruniquel are then described and compared with each other, with the above-named existing species of Hquus, and with previously defined fossil species of Equide. Two varieties in respect of size and some minor characters are pointed out in the Bruniquel. series, of one of which figures (of the natural size) of the grinding-surface of the upper and lower molar series, and of the second variety, figures of the same surface of the upper molar series are given. The author, remarking that such evidences of mature and full-grown ani- mals are rare from the Bruniquel Cave-deposits, selects evidence of certain phases of dentition in the Cave Equines which lend aid in determining their affinities; these phases being illustrated by four drawings of the natural size. Of the various fossil teeth of Hquide with which those from Bruniquel have been compared, the author finds the closest resemblance, approaching to identity, in certain fossils from freshwater sedimentary deposits of Post- pliocene or ‘‘ Quaternary”? age in the Department of the Puy-de-Déme, France. Of these, descriptions are given of the teeth of the upper and lower jaws from such deposits at a locality traversed by the river Allier, VOL. XVII. Q 202 Rev. H. Moseley on the Mechanical Possibility [Jan. 7 near the “Tour de Juvillac.” A figure of the working-surface of the teeth of the lower jaw from this locality is given (of the natural size), showing the characters of the canine and proportions of the diastema. The close conformity in the characters of the upper grinders of the Puy-de-Déme - fossils of deposit with those of the Bruniquel cavern enables the author to dispense with figures of them. The sum of the several comparisons is to refer the above Equine fos- sils from sedimentary deposits and both varieties from the Bruniquel cave to one and the same species or well-marked race belonging to the true Horses, or restricted genus Hguus of modern mammalogists ; the in- dividuals of which race, with a small range of size, probably due to sex, were less than the average-sized horse of the present period, but larger than known existing striped or unstriped species of Asznus, Gray. Interesting testimony, confirmatory of the conclusion from the palzeon- tological comparisons, is adduced from outlines of the heads of different in- dividuals of the Cave Equine when alive, neatly cut on the smooth sur- face of a rib of the same species, discovered by the Vicomte de Lastic St. Jal in 1863, in his cavern at Bruniquel, under circumstances which indis- putably showed the work to have been done by one of the tribe of men inhabiting the cavern and slaying the wild horses of that locality and period for food. The author remarks that every bone of the Horse’s skeleton (and such evidence had been obtained from about a hundred individuals that had been exhumed at the period of his second visit to Bruniquel, in February 1864) had been split or fractured to gain access to the marrow. The dental canal and roots of the teeth had been similarly exposed in every specimen of jaw. II. On the Mechanical Possibility of the Descent of Glaciers, by their Weight only.” By the Rev. Henry Mosrtry, M.A., Canon of Bristol, F.R.S., Instit. Imp. Sc. Paris, Corresp. Received Oc- tober 21, 1868. (Abstract. ) All the parts of a glacier do not descend with a common motion; it moves faster at its surface than deeper down, and at the centre of its sur- face than at its edges. It does not only come down bodily, but with dif- ferent motions of its different parts; so that if a transverse section were made through it, the ice would be found to be moving differently at every _ point of thar section. This fact*, which appears first to have been made known by M. Rendu, * The remains of the guides, lost in 1820 in Dr. Hamel’s attempt to ascend Mont Blanc, were found imbedded in the ice of the Glacier des Bossons in 1863. ‘‘The men and their things were torn to pieces, and widely separated by many feet. All around them the ice was covered in every direction for twenty or thirty feet with the hair of one knapsack, spread over an area three or four hundred times greater than that of the knap- 1869.] of the Descent of Glaciers by their Weight only. 203 - Bishop of Annecy, has since been confirmed by the measurements of Agassiz, Forbes, and Tyndall. There is a constant displacement of the par- ticles of the ice over one another, and alongside one another, to which is opposed that force of resistance which is known in mechanics as shearing force. By the property of ice called’ regelation, when any surface of ice so sheared is brought into contact with another similar surface, it unites with it, so as to form of the two, one continuous mass. Thus a slow displace- ment of shearing, by which different similar surfaces were continually being brought into the presence and contact of one another, would exhibit all the phenomena of the motion of glacier ice. Between this resistance to shearing and the force, whatever it may be, which tends to bring the glacier down, there must be a mechanical rela- tion, so that if the shearing resistance were greater the force would be in- sufficient to cause the descent. The shearing force of cast iron, for in- stance, is so great that, although its weight is also very great, it is highly improbable a mass of cast iron would descend if it were made to fill the channel of the Mer de Glace, as the glacier does, because its weight would be found insufficient to overcome its resistance to shearing, and thus to supply the work necessary to those internal displacements, of which a glacier is the subject, or even to shear over the irregularities of the rocky channel. The same is probably true of any other metal. I can find no discussion which has for its object to determine this me- chanical relation between what is assumed to be the cause of the descent of a glacier, and the effect produced,—to show that the work of its weight (supposing that alone to cause it to descend) is equal to the works of the several resistances, internal and external, which are actually overcome in its descent. It is my object to establish such a relation. The forces which oppose themselves to the descent of a glacier are, —Ist, the resistance to the sliding motion of one part of a piece of solid ice on the surface of another, which is taking place continually throughout the mass of the glacier, by reason of the different velocities with which its different parts move. This kind of resistance will be called in this paper (for shortness) shear, the unit of shear being the pressure in lbs. necessary to overcome the resistance to shearmg of one square inch, which may be presumed to be constant throughout the mass of the glacier. 2ndly. The friction of the superimposed lamine of the glacier (which moye with different velocities) on one another, which is greater in the lower ones than the upper. drdly. The resistance to abrasion, or shearing of the ice, at the bottom of the glacier, and on the sides of its channel, caused by the roughnesses sack.” ‘ This,” says Mr. Cowell, from whose paper read before the Alpine Club in April 1864 the above quotation is made, “is not an isolated example of the scattering that takes place in or on a glacier, for | myself saw on the Theodule Glacier the remaing of the Syndic of Val Tournanche scattered over a space of several acres.” Q 2 - 204 Rev. H. Moseley on the Mechanical Possibility (Jan. 7, of the rock, the projections of which insert themselves into its mass, and into the cavities of which it moulds itself. 4thly. The friction of the ice in contact with the bottom and sides so sheared over or abraded. ‘If the whole mechanical work of these several resistances in a glacier could be determined, as it regards its descent, for any relatively small time, one day for instance, and also the work of its weight in favour of its descent during that day, then, by the principle of “ virtual velocities’ (sup- posing the glacier to descend by its weight only), the ageregate of the work of these resistances, opposed to its descent, would be equal to the work of its weight, in favour of it. It is, of course, impossible to represent this equality mathematically, in respect to a glacier having a variable direction and an irregular channel and slope; but in respect to an imaginary one, having a constant direction and a uniform channel and slope, it is possible. Let such a glacier be imagined, of unlimited length, lying on an even slope, and having a uniform rectangular channel, to which it fits accurately, and which is of a uniform roughness sufficient to tear off the surface of the glacier as it advances. Such a glacier would descend with a uniform motion if it descended by its weight only, because the forces acting upon it would be uniformly distributed and constant forces*. The conditions of the descent of any one portion of it would therefore be the same as those of any other equal and similar portion. The portion, the conditions of whose descent it is sought in this paper to determine, is that which has de- scended through any given transverse section in a day ; or, rather, it is one half this mass of ice, for the glacier is supposed to be divided by a vertical plane, passing through the central line of its surface, it being evident that the conditions of the descent of the two halves are the same. The mea- surements which have been made of the velocities of the surface-ice at different distances from the sides, make it probable that the differences of the spaces described in a given time would be nearly proportional to the distances from the edge in a uniform channel? ; and the similar measure- ments made on the velocities at different depths on the sides that, under the same circumstances, the increments of velocity would be as the distances from the bottom. This law, which observation indicates as to the surface * It is supposed that the weight is only just sufficient to cause the descent. + Prof. Tyndall measured the velocity of the surface of the Mer de Glace at a series of points in the same straight line across it at a place called Les Ponts. The distances of these points in feet along the line up to the point of greatest velocity are set off toa scale in fig. 1 ; and the space in feet through which each point would pass in thirty-six. - days, if its velocity continued uniformly the same, is shown by a corresponding line at right angles to the other. The extremities of these last lines are joined. It will be seen that the line joining them is for some distance nearly straight ; if it were exactly so, the law stated in the text would, in respect to this ice, be absolutely true. Fig. 2 shows in the same manner the spaces described in thirty-six days by points at different depths on the side of the Glacier du Géant, as measured by Prof. Tyndall at the Tacul. See Phil. Trans. Royal Society, vol. cxlix. part 1, pp. 265, 266. [The figures referred to in this note accompany the MS. of the paper.] 1869.| of the Descent of Glaciers by their Weight only. 205 and the sides, is supposed to obtain throughout the mass of the glaciers. Any deviation from it, possible under the circumstances, will hereafter be shown to be such as would not sensibly affect the result. ; The trapezoidal mass of ice thus passing through a transverse section in a day is conceived to be divided by an infinite number of equi- distant vertical planes, parallel to the central line, or axis of the glacier, and also by an infinite number of other equidistant planes parallel to the bed of the glacier. It is thus cut into rectangular prisms or strips lying side by side and above one another. If any one of these strips be sup- posed to be prolonged through the whole length of the glacier, every part of it will be moving with the same velocity, and it will be continually shearing over two of the similar adjacent strips, and being sheared over by two others. The position of each of these elementary prisms in the trans- verse section of the glacier is determined by rectangular coordinates; and in terms of these, its length, included in the trapezoid. The work of its weight, while it passes through the transverse section into its actual posi- tion, is then determined, and the work of its shear, and the work of its friction. A double integration of each of the functions, thus representing the internal work in respect to a given elementary prism, determines the whole internal work of the trapezoid, in terms of the space traversed by the middle of the surface in one day, the spaces traversed by the upper and lower edges of the side, and a symbol representing the unit of shear. Well-known theorems serve to determine the work of the shear and the friction of the bottom and side in terms of the same quantities. All the terms of the equation above referred to are thus arrived at in terms of known quantities, except the unit of shear, which the equation thus deter- mines. The comparison of this unit of shear (which is the greatest pos- sible, in order that the glacier may descend by its weight alone) with the actual unit of shear of glacier ice (determined by experiment), shows that a glacier cannot descend by its weight only ; its shearing force is too great. The true unit of shear being then substituted for its symbol in the equation of condition, the work of the force, which must come in aid of its weight to effect the descent of the glacier, is ascertained. The imaginary case to which these computations apply, differs from that of an actual glacier in the following respects. The actual glacier is not straight, or of a uniform section and slope, and its channel is not of uni- form roughness. In all these respects the resistance to the descent of the actual glacier is greater than to the supposed one. But this being the case, the resistance to shearing must be less, in order that the same force, viz. the weight, may be just sufficient to bring down the glacier in the one case, as it does in the other. The ice in the natural channel must shear more easily than that in the artificial channel, if both descend by their weight only; so that if we determine the unit of shear necessary to the descent of the glacier in the artificial channel, we know that the unit of: 206 Rey. H. Moseley on the Mechanical Possibility ([Jan.7, shear necessary to its descent by its weight only in the natural channel must be less than that. A second possible difference between the case supposed and the actual case lies in this, that the velocities of the surface-ice at different distances from the edge, and at different heights from the bottom, are assumed to be proportional to those distances and heights; so that the mass of ice at any time passing through a transverse section may be bounded by plane sur- faces, and have a trapezoidal form. This may not strictly be the case. All the measurements, however, show that if the surfaces be not plane, they are convex downwards. In so far therefore as the quantity of ice passing through a given section in a day is different from what it is sup- posed to be, it is greater than it. A greater resistance (other than shear ing) is thus opposed to each day’s descent, and also a greater weight of ice favours it; but the disproportion is so great between the work of the additional resistance to the descent, and that of the additional weight of ice in favour of it, that it is certain that any such convexity of the trape- zoidal surface would necessitate a further reduction of the unit of shear, to make the weight of the actual glacier sufficient to cause it to descend. A third difference between the actual glacier and the imaginary one, to the computation of whose unit of shear the following formule are applied, is this—that the formule suppose the daily motion of the surface of the glacier and the daily motion of its side to have been measured at the same place, whereas there exist no measurements of the surface motion and the side motion at the same place. The surface motion used has been that of the Mer de Glace at Les Ponts, and the side motion that of the Glacier du Géant at the Tacul—both from the measurements of Prof. Tyndall. This error again, however, tends to cause the unit of shear, deduced from the case of the artificial glacier, to be greater than that in the actual one ; for the Glacier du Géant moves-more slowly than the Mer de Glace. The. quantity of ice which actually passes through a section at Les Ponts is therefore greater than it is assumed in the computation to be, whence it follows, as in the last case, that the computed unit of shear is greater than the actual unit of shear. To determine the actual value of » (the unit of shear in the case of ice) the following experiment was made. ‘Two pieces of hard wood, each three inches thick and of the same breadth, but of which one was con- siderably longer than the other, were placed together, the surfaces of con- tact being carefully smoothed, and a cylindrical hole, 13 inch in diameter, was pierced through the two. The longer piece was then screwed down upon a frame which carried a pulley, over which a cord passed to the middle of the shorter piece, which rested on the longer. There were lateral guides to keep the shorter piece from deviating sideways when moved on the longer. The hole in the upper piece being brought so as accurately to coincide with that in the lower, small pieces of ice were 1869.| of the Descent of Glaciers by their Weight only. 207 thrown in, a few at a time, and driven home by sharp blows of a mallet on a wooden cylinder. By this means a solid cylinder of ice was constructed, accurately fitting the hole. Weights were then suspended from the rope, passing over the pulley until the cylinder of ice was sheared across. As by the melting of the ice, during the experiment, the diameter of the cylinder was slightly diminished, it was carefully measured with a pair of callipers. | Ist experiment.—Radius of cylinder ‘65625 in., sheared with 98 Ibs. 2nd experiment.—Radius of cylinder *703]2 in., sheared with 119 lbs. By the first experiment the shear per square inch, or wait of shear, was 72°433 lbs.; by the second experiment it was 76°619 lbs. The main unit of shear of ice, from these two experiments, is therefore 75 lbs. Now it appears by the preceding calculations, that to descend by its own weight, at the rate at which Prof. Tyndall observed the ice of the Mer de Glace to be descending at the Tacul, the unit of shearing ferce of the ice could not have been more than 1°3193 lb.* To determine how great a force, in addition to its weight, would be necessary to cause the descent of a glacier of uniform section and slope, such as has been supposed in the calculations, let u represent, in inch-lbs., the work of that force in twenty-four hours. Then assuming the unit of shear (j) in glacier ice to be 75 lbs., it follows, by the principle of virtual velocities, that u= 94134000 + 1012560 — 2668400 : = 92478160 inch-lbs.=7706513 foot-lbs.t This computation has reference to half only of the width of the glacier, and to 23°25 inches of its length. The work, in excess of its weight, re- quired to make a mile of the imaginary glacier, 466 yards broad and 140 feet deep, descend, as it actually does descend per twenty-four hours, is represented by the horse-power of an engine, which, working constantly day and night, would yield this work, or by 27 ,UG 13a <.2280: X12 23°2 x 24 x 60 x 33000 The surface of the mass of ice, on which the work u is required to be done, in aid of its weight, to make it descend as it actually does, is 124771°5 square inches. The work required to be done on each square inch of surface, supposing it to be equally distributed over it, is therefore, ee) 7706513 in foot-lb peter: == on Peaeiguas. ! =883-78 h. p. * By an experiment on the shearing of putty, similar to that which was made on the shearing of ice, its unit of shear was found to vary from 1 Ib. to 3 lbs., according to its degree of hardness. If ice were of the same weight per unit of volume as soft putty, and its consistency about the same, it would descend by its weight only without the aid of any other force. It would not, however, be possible to walk on such ice. T aa the work to be done in aid of the weight is thirty-four times the work of the weight. 208 On the Descent of Glaciers by their Weight only. [Jan. These 61°76 foot-lbs. of work are equivalent to -0635 heat-units, or to the heat necessary to raise ‘0635 lb. of water by one degree of Fahrenheit. This amount of heat passing into the mass of the glacier per square inch of surface per day, and reconverted into mechanical work there, would be sufficient, together with its weight, to bring the glacier down. The following considerations may serve to disabuse some persons of the idea of an unlimited reservoir of force residing somewhere in the prolon- gation of a glacier backward, and in its higher slopes, from which reservoir the pressure is supposed to come which crushes the glacier over the obsta- cles in its way. Let a strip of ice one square inch in section, and one mile in length, im the middle of the surface of the imaginary glacier, be conceived to be sepa- rated from the rest throughout its whole length, except for the space of one inch, so that throughout its whole length, except for that one inch, its de- scent is not retarded either by shear or by friction. Let, moreover, this inch be conceived to be at the very end of the glacier, so that there is no glacier beyond it. Now it may easily be calculated that this strip of ice, one inch square and one mile long, lying on a slope of 4° 52’, without any resistance to its descent, except at its end, must press against its end, by reason of its weight, with a force of 194:42 lbs. But the cubical inch of solid ice at its extremity opposes, by the shear of its three surfaces, whose attachment to the adjacent ice is unbroken, a resistance of 3 X 75 lbs., or 225 lbs. That resistance stops therefore the descent of this strip of ice, one mile long, having no other resistance than this opposed to its descent, by reason of its detachment from the rest*. It is clear, then, that it could - not have descended by its weight only when it wdhered to the rest, and when its descent was opposed by the shear of its whole length; and the same may be proved of any number of miles of strip in prolongation of this. Also, with obvious modifications, it may be shown, in the same way, to be true of any other similar strip of ice in the glacier, whether on the surface or not, and therefore of the whole glacier. It results from this investigation that the weight of a glacier is insuf- ficient to account for its descent; that it is necessary to conceive, in addi- tion to its weight, the operation of some other and much greater force, which must also be such as would produce those internal molecular dis- placements and those strains which are observed actually to take place in glacier ice, and must therefore be present to every part of the glacier as its weight is, but more than thirty-four times as great. * Tf, however, the glacier were inclined at 35° 10’, instead of 4° 52’, and a strip were detached from its surface, as described above, it would equal the shear of one cubic inch at its lower end, if it were 300 yards long, and if the glacier were vertical, when it was 172°8 yards long. 1869. | On the Granites of Cornwall and Devonshire. 209 III. Notes of a Comparison of the Granites of Cornwall and Devon- shire with those of Leinster and Mourne.” By the Rev. Samvuex Haveuton, M.D., D.C.L., F.R.S., Fellow of Trinity College, Dublin. Received December 18, 1868. The granites of Mourne are eruptive, and can be proved to contain al- bite as their second felspar. The granites of Leinster are also eruptive ; and although albite has never yet been actually found to occur in them, its existence can be inferred with considerable probability. During the past summer (1868) I have succeeded in proving that the second felspar that occurs in the granites of Cornwall is albite. I found this mineral as a constituent of the granite at Trewavas Head, where it has the following composition :— I. Albite, var. Cleavelandite (Trewavas Head). SOHINGAN MRD. etapa b ent Sa wperice MPAs 65°76 PAUUUNINININE sv 5racque Ss oid os ava DANE Ts 1 LANTOS en! ee nee 0°89 Midenesiane = ves... ; trace S010 2 Sealed ee he eee Se 9°23 Ratashie sy cide 2. AES Fae 1:76 PNRM a aR areola th oul © a's 0°40 99°76 This albite is opaque, cream-coloured, lamellar, and associated with quartz and orthoclase, wbich has the following composition :— Il. Orthoclase (Trewavas Head). No. 1*. No. 2f. Sas SS Secale ee 63°60 63°20 PMMOMUR Te st Psy ie tees LOA 21°00 Iron and manganese oxides .... trace trace LL TING er cea A Oe a eam 0-90 0-68 PAR HCRION Gos ie's ves 2s! ees se sa; - trace trace SOGGis ent Ob ce ee eee 3°08 2°75 ots emt eben. tr. 9°91 10°30 WENGE Gucice Wbower tos coonecwe m0 0°40 98°93 98°33 The granites of Cornwall and Devon contain two micas, white and black. _ I was fortunate enough to obtain, through my friend Mr. W. J. Henwood, F.R.S., of Penzance, a sufficient quantity of white mica from Tremearne, neat Trewavas Head, to determine accurately its composition, which proves to be highly interesting. It differs essentially from the white mica of Leinster and Donegal, and proves to be a variety of lepidolite. * From veins at foot of cliff associated with Cleavelandite albite. + From the granite at summit of cliff. 210 Rev. S. Haughton on the Granites [Jan .7 Il. White Mica, Lepidolite (Tremearne, near Trewavas Head). Siltea; SiO, <5 See ee Flaosilicon; SIP, 2.2. 2e 5°68 Adana te i eae eee eee Irom peroxide? 2-5 seas 5°20 Manganese protoxide.... 1°20 ame ee eee ee 0°45 Magnesia. ./..4.\.<.s. 26 se, PEaEE Potash. :25sc 0223. ee Soda -.2 2s. eee ee hithia: seh eee 1-14 99°67 This lepidolite is white, pearly, and occurs in rhombic tables of 60° and 120°. Its oxygen ratios are, reckoning for the fluorine its equivalent of oxygen,— Oxygen Ratios. SiliCa- ss ae bine meek Tt | 26-461 9-9 Plnosthcon: =e ae tes 1°747 Alumina > eae. Ts | 14-270 4:8 Irom peromide M8." cey eel oom Manganese protoxide .. 0°268 | 1 Brits ie eee ere ee so rd7. | Moasnesia a eee -eieeet eo an Potash #65 tes sh 1°776 - zon ee Soda: ith aa ee ee 0-184 | ities es eee yO O27.) This corresponds with a theoretical formula, in which the oxygen of the silica is to that of the bases as 3: 2. The Black Mica of the Cornish granites seems to be more abundant than the White Mica already described. I found a sufficient quantity of it at Coron Bosavern, near St. Just, to enable me to make the following analysis: — IV. Black Mica, Lepidomelane (Coron Bosavern, near St. Just). Nilica(SiO)) 5 ose ok ee Fluastheon (Sil) ce 3°04 Alumnae cc colen eae 22°88 Trongperoxide: cer =. 15°02 Tron protoxide... ....2<27...° - w2eae Manganese protoxide .... 1°40 Lame lee ee ee pee 0°68 Macnesing. <2 ysis einer 1°07 Potash 3) i ae eee 9°76 Oda cater As see tee 0-99 Lithia of. once ee le 1869. ] of Cornwall and Devonshire. 215 The Black Mica of St. Just is of a blackish-bronze colour and metallic lustre, and occurs in rhombs of 60° and 120° angles. Its oxygen ratios are, reckoning for the fluorine its equivalent of oxygen,— . Oxygen Ratios. SITET pi ae ue = = 21°64 Fluosilicon.......... .. 0-918 : PIETER.) os pcs se aay : 15°092 Benn peroxide ........4.- 4-400 ” Irom protoxade .....:.-. 0-514) Manganese protoxide.... 0°310 | _ CTR Be ee 0-192 Peete ss 2a, . 427 > 4:209 RR ic 3 Se rs Sk 1°655 Se Sage ae eae aes sas AD Mammen os O9AL | The oxygen ratio of this iron-potash Mica (which is undoubtedly a lepi- domelane) for silica and bases is BiG = 3G4~ or 121. The granites of Cornwall and Devon, which have been frequently ex- amined by me during the last sixteen years, appear all to contain the two felspars and the two micas above analyzed. In a future communication I hope to describe their composition in detail, and to give a comparison of this composition with that of the granites of Ireland. The following generalizations will be found, as I believe, capable of proof. (1) The granites of Ireland may be divided into two distinct classes, marked by characters both geological and mineralogical. (2) The First Class of granites consists of Eruptive rocks, of ages vary- ing from the Silurian to the Carboniferous periods. To this class may be referred the granites of Leinster and Mourne, and the granites of Cornwall and Devon, (8) The First Class of granites is characterized by the presence of ortho- clase and albite, and by the absence of all the Lime Felspars. (4) The Second Class of granites consists of Metamorphie rocks, of un- known geological age, but probably subsequent to the Laurentian period. To this class may be referred the granites of Donegal and Galway, and the granites of Scotland, Norway, and Sweden. (5) The Second Class of granites is characterized by the presence of or- thoclase and oligoclase, or Labradorite, or some other of the Lime Felspars, and by the absence of albite. 212 Mr. Graham on the Relation [Jan. 14, January 14, 1869. Lieut.-General SABINE, President, in the Chair. The following communications were read :— “I. “On the Relation of Hydrogen to Palladium.’ By Tuomas GraHam, F.R.S., Master of the Mint. Received November 23, 1868. It has often been maintained on chemical grounds that hydrogen gas is the vapour of a highly volatile metal. The idea forces itself upon the mind that palladium with its occluded hydrogen is simply an alloy of this vola- tile metal, in which the volatility of the one element is restrained by its union with the other, and which owes its metallic aspect equally to both constituents. How far such a view is borne out by the properties of the compound substance in question will appear by the following examination of the properties of what, assuming its metallic character, would have to be named Hydrogenium. 1. Density.—The density of palladium when charged with eight or nine hundred times its volume of hydrogen gas is perceptibly lowered; but the change eannot be measured accurately by the ordinary method of immer- sion in water, owing to a continuous evolution of minute hydrogen bub- bles which appears to be determined by contact with the liquid. However, the linear dimensions of the charged palladium are altered so considerably that the difference admits of easy measurement, and furnishes the required density by calculation. Palladium in the form of wire is readily charged with hydrogen by evolving that gas upon the surface of the metal in a galvanometer containing dilute sulphuric acid as usual*. The length of the wire before and after a charge is found by stretching it on both occasions by the same moderate weight, such as will not produce permanent disten- tion, over the surface of a flat graduated measure. The measure was gra- duated to hundredths of an inch, and by means of a vernier, the divisions could be read to thousandths. The distance between two fine cross lines marked upon the surface of the wire near each of its extremities was observed. Expt. 1.—The wire had been drawn from welded palladium, and was hard and elastic. The diameter of the wire was 0°462 millimetre; its specific gravity was 12°38, as determined with care. The wire was twisted into a loop at each end and the mark made near each loop. ‘The loops were varnished so as to limit absorption of gas by the wire to the measured length between the two marks. To straighten the wire, one loop was fixed, and the other connected with a string passing over a pulley and loaded with 1°5 kilogramme, a weight sufficient to straighten the wire without occasioning any undue strain. The wire was charged with hydro- gen by making it the negative electrode of a small Bunsen’s battery con- sisting of two cells, each of half a litre in capacity. The positive electrode was a thick platinum wire placed side by side with the palladium wire, and * Proceedings of the Royal Society, p. 422, 1868. 1869. | of Hydrogen to Palladium. 2138 extending the whole length of the latter within a tall jar filled with dilute sulphuric acid. The palladium wire had, in consequence, hydrogen carried to its surface, for a period of 13 hour. A longer exposure was found not to add sensibly to the charge of hydrogen acquired by the wire. The wire was again measured and the increase in length noted. Finally the wire, being dried with a cloth, was divided at the marks, and the charged por- tion heated in a long narrow glass tube kept vacuous by a Sprengel aspi- rator. The whole occluded hydrogen was thus collected and measured ; its volume is reduced by calculation to Bar. 760 millims., and Therm. 0° C. The original length of the palladium wire exposed was 609'144 millims. (23-982 inches), and its weight 1°6832 grm. The wire received a charge of hydrogen amounting to 936 times its volume, measuring 128 cubic centims., and therefore weighing 0°01147 grm. When the gas was ultimately ex- pelled, the loss as ascertained by direct weighing was 0°01164 grm. The charged wire measured 618-923 millims., showing an increase in length of 9°779 miilims. (0°385 inch). The increase in linear dimensions is from 100 to 101-605, and in cubic capacity, assuming the expansion to be equal in all directions, from 100 to 104°908. Supposing the two metals united without any change of volume, the alloy may therefore be said to be com- _ posed of By volume. Palladium. 2s... 2.2% 100 or 95°32 Hydrogenium.....4.... 4°908 or 4°68 104908 100 — The expansion which the palladium undergoes appears enormous if viewed as a change of bulk in the metal only, due to any conceivable physical force, amounting as it does to sixteen times the dilatation of palladium when heated from 0° to 100° C. The density of the charged wire is re- duced, by calculation, from 12°3 to 11°79. Again, as 100 is to 4°91, so the volume of the palladium, 0°1358 cubic centim., is to the volume of the hydrogenium, 0°006714 cubic centim. Finally, dividing the weight of the hydrogenium, 0°01147 grm., by its volume in the alloy, 0:006714 cubic centim., we find Werusity. of hy drosemiunn, 2. S65. eee Se es 1708 The density of hydrogenium, then, appears to faipeoach: that of magnesium, 1:743, by this first experiment. Further, the expulsion of hydrogen from the wire, however caused, is attended with an extraordinary contraction of the latter. On expelling the hydrogen by a moderate heat, the wire not only receded to its original length, but fell as much below that zero as it had previously risen above it. The palladium wire first measuring 609°144 millims., and which increased 9°77 millims., was ultimately reduced to 599°444 millims., and contracted 9-7 millims. The wire is permanently shortened. The density of the pal- 214, My. Graham on the Relation [Jan. 14, ladium did not increase, but fell slightly at the same time, namely from 12°38 to 12°12, proving that this contraction of the wire is in length only. The result is the converse of extension by wire-drawing. The retraction of the wire is possibly due to an effect of wire-drawing in leaving the par- ticles of metal in a state of unequal tension, a tension which is excessive in the direction of the length of the wire. The metallic particles would seem to become mobile, and to right themselves in proportion as the hydrogen escapes; and the wire contracts in length, expanding, as appears by its final density, in other directions at the same time. A wire so charged with hydrogen, if rubbed with the powder of mag- nesia (to make the flame luminous), burns like a waxed thread when ig- nited in the flame of a lamp. Expt. 2.—Another portion of the same palladium wire was charged with hydrogen in a similar manner. The results observed were as fel- lows :— Length of palladiam wire... ae. ee 488:976 millims. Thesame with 867-15 volumes ofoccluded gas 495°656 < Linear elongation 47... 5k. siete eines 6°68 ee Linear elengation onsl00,. 2 ie ere 13065 50 ae Cubicexpansionon100\ <3... 1 ae 4°154 i Weight of palladium wire’... ere 1:0667 grm. Volume of palladium wire.............: _ 0:08072 cub.centim. Volume of occluded hydrogen gas ...... 73°2 se Weight ol samen, 6) oe ee reer 0:00684 grm. Volume: of hydrosemmm, 20 ier 4 ee 0:003601 cub. centim. From these results is calculated Density of hydrogenium .............. 1°898. Expt. 3.—The palladium wire was new, and on this occasion was well annealed before being charged with hydrogen. ‘The wire was exposed at the negative pole for two hours, when it had ceased to elongate. Length of palladium wire ............ 556°185 millims. Same with §88°303 volumes hydrogen .. 563°652 BS imeareloneation, .~ 2... a. 7'467 - Lanear elongation on 100). “c..2.- eaee 1°324 “4 Cubie expansion on 100>....2i 5. 22.5 3: 4:025 5 Weight of palladium wire...:...2....:<. | 167 oq@gcme Volume: of palladium wire’ -..2:224.-%% 0-0949 cub. centim. Volume of occluded hydrogen gas ...... - 84°3 cub. centims. Weeightvof Same)... (oie arte ce 1 tee 0:007553 grm. Volume of hydrogentum »...<:<-..0222. 0:003820 cub. centim. These results give by calculation Density of hydrogenmm,. 32 oni ee eee: O77. It was necessary to assume in this discussion that the two metals do not 1869. | of Hydrogen to Palladium. 215 contract nor expand, but remain of their proper volume on uniting. Dr. Matthiessen has shown that in the formation of alloys generally the metals retain approximately their original densities *. In the first experiment already described, probably the maximum ab- sorption of gas by wire, amounting to 935°67 volumes, is attained. The palladium may be charged with any smaller proportion of hydrogen by shortening the time of exposure to the gas (329 volumes of hydrogen were taken up in twenty minutes), and an opportunity be gained of observing if the density of the hydrogenium remains constant, or if it varies with the proportion in which hydrogen enters the alloy. In the following state- ment, which includes the three experiments already reported, the essential points only are produced. TABLE. Volumes Linear expansion in Density of hydrogen millimetres. of occluded. ee To Hydrogenium. 329 496°189 498°552 2°055 462 493°040 496520 1:930 487 370°358 373126 T9274 745 305°538 511°303 Ue) 867 488°976 495°656 1898 888 556°185 563°652 oad 936 | 609°144 618-923 1-708 If the first and last experiments only are compared, it would appear that the hydrogenium becomes sensibly denser when the proportion of it is small, ranging from 1°708 to 2°055. But the last experiment of the Table it perhaps exceptional ; and all the others indicate considerable uniformity of density. The mean density of hydrogenium, according to the whole experiments, excluding that last referred to, is 1:951, or nearly 2. This uniformity is in favour of the method followed for estimating the density of hydrogenium. On charging and discharging portions of the same palladium wire repeat- edly, the curious retraction was found to continue, and seemed to be inter- minable. The following expansions, caused by variable charges of hydro- gen, were followed on expelling the hydrogen by the retractions men- tioned. Elongation. Retraction. Pigexperiment 9-7/7 .millims. ... 6. 4.6. 9°70 millims. 2nd my 5°765 ng, wee Mine eaten a O20 ii has ord 5 2°36 RG StS Pe AEE a es Ae 4th as 3°482 NM We NE Sv arictiat a Ae 5 a ails 23°99 The palladium wire, which originally measured 609-144 millims., has * Philosophical Transactions, 1860, p. 177. 216 Mr. Graham on the Relation [Jan. 14, suffered, by four successive discharges of hydrogen from it, a permanent contraction of 23°99 millims. ; that is, a reduction of 3-9 per cent. on its original length. The contractions will be observed to exceed in amount the preceding elongations produced by the hydrogen, particularly when the charge of the latter is less considerable. With another portion of wire the contraction was carried to 15 per cent. of its length by the effect of re- peated discharges. The specific gravity of the contracted wire was 12°12, no general condensation of the metal having taken place. ‘The wire shrinks in length only. In the preceding experiments the hydrogen was expelled by exposing the palladium placed within a glass tube to a moderate heat short of red- ness, and exhausting by means of a Sprengel tube; but the gas was also withdrawn in another way, namely, by making the wire the positive elec- trode, and thereby evolving oxygen upon its surface. In such circumstances a slight film of oxide of palladium is formed on the wire, but it appears not to interfere with tne extraction and oxidation of the hydrogen. The wire measured, Difference. Beforeicharce <2 47 443°25 millims. With hydrogen...... 44990 x +6°65 millims. After discharge...... AS-i - —5°94 ts The retraction of the wire therefore does not require the concurrence of a high temperature. This experiment further proved that a large charge of hydrogen may be removed in a complete manner by exposure to the positive pole (for four hours in this case); for the wire in its ultimate state gave no hydrogen on being heated zn vacuo. That particular wire, which had been repeatedly charged with hydrogen, was once more exposed to a maximum charge, for the purpose of ascer- taining whether or not its elongation under hydrogen might now be facili- tated and become greater in consequence of the previous large retraction. No such extra elongation, however, was observed on charging the retracted wire more than once; and the expansion continued to be in the usual proportion to the hydrogen absorbed. The final density of the wire was 12°18. The wire retracted by heat is found to be altered in another way, which appears to indicate a molecular change. When the gas has been expelled by heat, the metal gradually loses much of its power to take up hydrogen. The last wire, after it had already been operated upon six times, was again charged with hydrogen for two hours, and was found to occlude only 320 volumes of gas, and in arepetition of the experiment, 330°5 volumes. The absorbent power of the palladium had therefore been reduced to about one-third of its maximum. The condition of the retracted wire appeared, however, to be improved by raising its temperature to full redness by sending through it an electrical 1869. ] of Hydrogen to Palladium. ay current from a battery. The absorption rose thereafter to 425 volumes of hydrogen, and in a second experiment to 422°5 volumes. The wire becomes fissured longitudinally, acquires a thready structure, and is much disintegrated on repeatedly losing hydrogen, particularly when the hydrogen has been extracted by electrolysis in an acid fluid. The pal- ladium in the last case is dissolved by the acid to some extent. The metal appeared, however, to recover its full power to absorb hydrogen, now con- densing upwards of 900 volumes of gas. The effect upon its length of simply annealing the palladium wire by exposure in a porcelain tube to a full red heat, was observed. The wire measured 5567075 millims. before, and 555°875 millims. after heating ; or a minute retraction of 0-2 millim, was indicated. In a second annealing experiment, with an equal length of new wire, no sensible change whatever of length could be discovered. There is no reason, then, to ascribe the retraction after hydrogen, in any degree, to the heat applied when the gas is expelled. Palladium wire is very slightly affected in physical properties by such annealing, retaining much of its first hardness and elasticity. 2. Tenacity.—A new palladium wire, similar to the last, of which 100 millims. weighed 0°1987 grm., was broken, in experiments made on two different portions of it, by a load of 10 and of 10°17 kilogrammes. Two other portions of the same wire, fully charged with hydrogen, were broken by 8°18, and by 8°27 kilogrammes. Hence we have— Memagiey Of Palladiumy WITE 05... 6. ee ee ee ves 100 Tenacity of palladium and hydrogen .......... 81°29 The tenacity of the palladium is reduced by the addition of hydrogen, but not to any great extent. It is a question whether the degree of tenacity that still remains is reconcileable with any other view than that the second element present possesses of itself a degree of tenacity such as is only found in metals. 3. Electrical Conductivity.—Mr. Becker, who is familiar with the practice of testing the capacity of wires for conducting electricity, submitted a palla- dium wire, before and after being charged with hydrogen, to trial, in com parison with a wire of German silver of equal diameter and length, at 10°°5. The conducting-power of the several wires was found as follows, being re- ferred to pure copper as 100 :— AKC) COP PCL eG ay er teeh Shin one. Saas hee Saas 100 PeePirebIUNTIA ar ce. Subs Pr wees Boats ee SOW. eT 8°10 Elloy of 80 copper+-20mekel oy. eee. 6°63 Palladium Phydrosenis 5 le. &. 2h POA 5°99 A reduced conducting-power is generally observed in alloys, and the charged palladium wire falls 25 per cent. But the conducting-power remains still considerable, and the result may be construed to favour the metallic character of the second constituent of the wire. Dr. Matthiessen confirms these results. VOL. XVII. R 218 Mr. Graham on the Relation [Jan. 14, 4. Magnetism.—It is given by Faraday as the result of all his experi- ments, that palladium is “‘feebly but truly magnetic ;”’ and this element he placed at the head of what are now called the paramagnetic metals. But the feeble magnetism of palladium did not extend to its salts. In repeating such experiments, a horseshoe electromagnet of soft iron, about 15 centims. (6 inches) in height, was made use of. It was capable of supporting 60 kilogs., when excited by four large Bunsen cells. This is an induced magnet of very moderate power. ‘The instrument was placed with its poles directed upwards ; and each of these was provided with a small square block of soft iron terminating laterally in a point, ikea small anvil. The palladium under examination was suspended between these points in a stirrup of paper attached to three fibres of cocoon silk, 3 decimetres in length, and the whole was covered by a bell glass. A filament of glass was attached to the paper, and moved as an index on a circle of paper on the glass shade divided into degrees. The metal, which was an oblong fragment of electrc- deposited palladium, about 8 millims. in length and 3 millims. in width, being at rest in an equatorial positon (that is, with its ends averted from the poles of the electromagnet), the magnet was then charged by connecting it with the electrical battery. The palladium was deflected slightly ‘rom the equatorial line by 10° only, the magnetism acting against the torsion of the silk suspending thread. The same palladium charged with 604°6 volumes of hydrogen was deflected by the electromagnet through 48°, when it set itself at rest. The gas being afterwards extracted, and the palladium again placed equatorially between the poles, it was not deflected in the least perceptible degree. The addition of hydrogen adds manifestly, therefore, to the small natural magnetism of the palladium. To have some terms of comparison, the same little mass of electro-deposited palladium was steeped in a solution of nickel, of sp. gr. 1°082, which is known to be magnetic. The deflection under the magnet was now 35°, or less than with hydrogen. The same palladium being afterwards washed and impregnated with a solution of protosulphate of iron of sp. gr. 1:048, of which the metallic mass held 2°3 per cent. of its weight, the palladium gave a deflec- tion of 50°, or nearly the same as with hydrogen. With a stronger solution of the same salt, of sp. gr. 1:17, the deflection was 90°, and the palladium pointed axially. Palladium in the form of wire or foil gave no deflection when placed in the same apparatus, of which the moderate sensitiveness was rather an advantage in present circumstances ; but when afterwards charged with hydrogen, the palladium uniformly gave a sensible deflection of about 20°. A previous washing of the wire or foil with hydrochloric acid, to remove any possible traces of iron, did not modify this result. Palladium reduced from the cyanide and also precipitated by hypophosphorous acid, when placed in a small glass tube, was found to be not sensibly magnetic by our test ; but it always acquired a sensible magnetism when charged with hydrogen. . : 1869.] of Hydrogen to Palladium. "219 It appears to follow that hydrogenium is magnetic, a property which is confined to metals and their compounds. This magnetism is not per- ceptible in hydrogen gas, which was placed both by Faraday and by M. E. Becquerel at the bottom of the list of diamagnetic substances. This gas is allowed to be upon the turning-point between the paramagnetic and diamagnetic classes. But magnetism is so liable to extinction under the influence of heat, that the magnetism of a metal may very possibly disappear entirely when it is fused or vaporized, as appears to be the case with hydrogen in the form of gas. As palladium stands high in the series of the paramagnetic metals, hydrogenium must be allowed to rise out of that class, and to take place in the strictly magnetic group, with iron, nickel, cobalt, chromium, and manganese. 5. Palladium with Hydrogen at a high Temperature.—The ready per- meability of heated palladium by hydrogen gas would imply the reten- tion of the latter element by the metal even at a bright red heat. The hydrogenium must in fact travel through the palladium by cementa- tion, a molecular process which requires time. The first attempts to arrest hydrogen in its passage through the red-hot metal were made by transmitting hydrogen gas through a metal tube of palladium with a vacuum outside, rapidly followed by a stream of carbonic acid, in which the metal was allowed to cool. When the metal was afterwards examined in the usual way, no hydrogen could be found in it. The short period of exposure to the carbonic acid seems to have been sufficient to dissipate the gas. But on heating palladium foil red-hot in a flame of hydrogen gas, and suddenly cooling the metal in water, a small portion of hydrogen was found locked up in the metal. A volume of metal amounting to 0:062 cubic centim., gave 0-080 cubic centim. of hydrogen; or, the gas, measured cold, was 1°306 times the bulk ofthe metal. This measure of gas would amount to three or four times the volume of the metal at a red heat. Platinum treated in the same way appeared also to yield hydrogen, although the quantity was too small to be much relied upon, amounting only to 0:06 volume of the metal. The permeation of these metals by hydrogen appears therefore to depend on absorption, and not to require the assumption of anything like porosity in their structure. The highest velocity of permeation observed was in the experiment where four litres of hydrogen (3992 cub. centims.) per minute passed through a plate of palladium 1 millim. in thickness, and calculated for a square metre in surface, at a bright red heat a little short of the melting-point of gold. This is a travelling movement of hydrogen through the substance of the metal with the velocity of 4 millimetres per minute. 6. Chemical Properties.—The chemical properties of hydrogenium also distinguish it from ordinary hydrogen. The palladium alloy precipitates mercury and calomel from a solution of the chloride of mercury without any disengagement of hydrogen; thatis, hydrogenium decomposes chloride of mercury, while hydrogen does not. This explains why M. Stanislas R2 220 Prof. Cayley on the Theory of Reciprocal Surfaces. (Jan. 14, Meunier failed in discovering the occluded hydrogen of meteoric iron, by dissolving the latter in a solution of chloride of mercury ; for the hydrogen would be consumed, like the iron itself, in precipitating mercury. Hy- drogen (associated with palladium) unites with chlorine and iodine in the dark, reduces a persalt of iron to the state of protosalt, converts red prussiate of potash into yellow prussiate, and has considerable deoxidizing powers. It appears to be the active form of hydrogen, as ozone is of oxygen. The general conclusions which appear to flow from this inquiry are, that in palladium fully charged with hydrogen, as in the portion of palladium wire now submitted to the Royal Society, there exists a compound of palladium and hydrogen in a proportion which may approach to equal equivalents*. That both substances are solid, metallic, and of a white aspect. That the alloy contains about 20 volumes of palladium united with a volume of hydrogenium ; and that the density of the latter is about 2, a little higher than magnesium to which hydrogenium may be supposed to bear some analogy. That hydrogenium has a certain amount of tenacity, and possesses the electrical conductivity of a metal. And finally, that hydrogenium takes its place among magnetic metals. The latter fact may have its bearing upon the appearance of hydrogenium in meteoric iron, in association with certain other magnetic elements. T cannot close this paper without taking the opportunity to return my best thanks to Mr. W. C. Roberts for his valuable cooperation throughout the investigation. II. “ A Memoir on the Theory of Reciprocal Surfaces.” By Professor Cavey, F.R.S. Received November 12, 1868. (Abstract.) The present Memoir contains some extensions of Dr. Salmon’s theory of Reciprocal Surfaces. I wish to put the formule on record, in order to be able to refer to them in a “ Memoir on Cubic Surfaces,” but without at present attempting to completely develope the theory. Dr. Salmon’s fundamental formule (A), (B) are replaced by a(n-—2)= w«— B+ p+2e, b(n—2)= p+2B+3y+3t, e(n—2)=2e+48+ y+ 8, a(u— 2)(n—3)=2(8—C)+3(ace —30—y) +2(ab—2p — 7), B(n—2)(n—3)= — 4k+. (ab—2p— j) + 3(Be—3B— y— I), c(n—2)(n—3)= 6h+ (ac—3o—yx)+2(be—36—y—2), where j, 0, x, B, C refer to singularities not taken account of in his theory ; viz. j is the number of pinch-points on the nodal curve 6, x, the numbers of certain singular points on the cuspidal curve, C the number of conic nodes, B the number of biplanar nodes: the reciprocal singularities 7’, 0, X's * Proceedings of the Royal Society, 1868, p. 425. 1869. | Prof. Cayley on Cubic Surfaces. 221 B, C’, are of course also considered. An equation of Dr. Salmon’s is presented in the extended form, o =4n(n—2)—8b—11le—2j’—3y'—2C'’—4B'; and it is remarked that o’ denotes the order of the spinode-curve. The Memoir contains an entirely new formula giving the value of 6’, but some of” the constants of the formula remain undetermined. III. “ A Memoir on Cubic Surfaces.” By Professor Cavity, F.R.S. Received November 12, 1868. (Abstract.) The present Memoir is based upon, and is in a measure supplementary to that by Professor Schlafli, «‘On the Distribution of Surfaces of the Third Order into Species, in reference to the presence or absence of Singular Points, and the reality of their Lines,’”’ Phil. Trans. vol. cliii. (1863) pp. 193-241. But the object of the Memoir is different. I disregard altogether the ulti- mate division depending on the reality of the lines, attending only to the division into (twenty-two, or as I prefer to reckon it) twenty-three cases depending on the nature of the singularities. And I attend to the question very much on account of the light to be obtained in reference to the theory of Reciprocal Surfaces. The memoir referred to furnishes in fact a store of materials for this purpose, inasmuch as it gives (partially or completely de- veloped) the equations in plane-coordinates of the several cases of cubic surfaces ; or, what is the same thing, the equations in point-coordinates of the several surfaces (orders 12 to 3) reciprocal to these respectively. I found by examination of the several cases, that an extension was required of Dr. Salmon’s theory of Reciprocal Surfaces in order to make it applicable to the present subject ; and the preceding ‘“‘ Memoir on the Theory of Reci- procal Surfaces”? was written in connexion with these investigations on Cubic Surfaces. The latter part of the Memoir is divided into sections headed thus:—“Section I= 12, equation (X, Y,Z, W)°=0”’ &c. referring to the several cases of the cubic surface; but the paragraphs are numbered continuously through the Memoir. The principal results are included in the following Table of singularities. The heading of each column shows the number and character of the case referred to, viz. C denotes a conic node, B a biplanar node, and U a uniplanar node ; these being further distinguished by subscript numbers, showing the reduction thereby caused in the class of the surface: thus XII=12—B,—2C, indicates that the case XIII is a cubic surface, the class whereof is 12—7,=5, the reduction arising from a biplanar node, B,, reducing the class by 3, aud from 2 conic nodes, C,, each reducing the class by 2. : (Jan. 14, Prof. Cayley on Cubic Surfaces. 222 SIo exe Bn Haya eX ne boR DAs OF SB Bw BRRoeRL VRRKSCTR Dan © Aa te » ile | | | | | ‘TNTXx J | | Se mwesm |rooonn |oooooes looolicoo | ¢ 1 oH S00 oOo0n etx. . ae a oososs |coo|oo "ge-z1=1xx | meee [ooocee [cooces [ooo [on | 1xx|meoe |oocose |cocose [soe lon ya) =vVvVv — : We enix nena |ecooss |sococe [eos [=n | XX{aeoe |ooooos |nonnon loos [on 9 —"q—Z1=XIX "XIX Wqg—'g -Z1=IAX pREWS |oooSOoS |OSSSSS |oos | +O TAX, HOSA | monmome |ooooos |ooo joo “O7—Z1=IAX TAX “4 — 1 =AX | "AX i ge eae sooooe |osooce ooo laa ‘AIX 1 19 CO® | ROSSRmA | wANBHON |AOoSO1OO 29% —"¢ —Z1=I111X | Oras iol — TIX ] "TIX °“q—Z31=IX Px *o—'a—ai=x (7° coocos loosooso loco limo Ig] DESH | DOO AAD woeawsoo |mooloo “e—ZI=INIA | ‘TITA ; Sq — — ° ia z G—a1=lAl Gi [oooses [ooosee lose |= | ITA neon |ancone |exzann [woo loo Sy — 8 —SL=IA TA | =aN eee) nen |ooooos |oosees [ooo [ao | Alaoooa Se = | eb aoe [ace eo tg-zi=u |poon [oooses |[oosecs [ooo [o- | Mle ce |>2ece> |eavae> Boo Gs “y-g1=11 | weno |ecssce [oosees [ooo |-2 | | | | = | ae (Se ZI=1| meow |oosese |eooose |[s00 |oe | | | | B | Seiler a ge soex SRR Bany CLF HDR Qe OF See Se eta ye Om a Oe 1869.] Onthe Blue Colour of the Sky, and the Polarization of Light. 223 IV. “On the Blue Colour of the Sky, the Polarization of Sky- light, and on the Polarization of Light by Cloudy matter gene- rally.’ By Joun Tynpatt, LL.D., F.R.S. Received December 16, 1868. Since the communication of my brief abstract ‘‘On a new Series of Che- mical Reactions produced by Light,” the experiments upon this subject have been continued, and the number of the substances thus acted on considerably augmented. New relations have also been established be- tween mixed vapours when subjected to the action of light. I now beg to draw the attention of the Royal Society to two questions glaneed at incidentally in the abstract referred to,—the blue colour of the sky, and the polarization of skylight. Reserving the historic treatment of the subject for a more fitting occasion, I would merely mention now that these questions constitute, in the opinion of our most eminent authorities, the two great standing enigmas of meteorology. Indeed it was the interest manifested in them by Sir John Herschel, in a letter of singular speculative power, that caused me to enter upon the consideration of these questions so soon. The apparatus with which I work consists, as already stated to the Society, of a glass tube about a yard in length, and from 23 to 3 inches internal diameter. ‘The vapour to be examined is introduced into this tube in the manner described in my last abstract, and upon it the condensed beam of the electric lamp is permitted to act until the neutrality or the ac- tivity of the substance has been declared. It has hitherto been my aim to render the chemical action of light upon vapours visible. For this purpose substances have been chosen, one at least of whose products of decomposition under light shall have a boiling-point so high that as soon as the substance is formed it shall be precipitated. By graduating the quantity of the vapour, this precipitation may be rendered of any degree of fineness, forming particles distinguishable by the naked eye, or particles which are probably far beyond the reach of our highest microscopic powers. I have no reason to doubt that particles may be thus obtained whose diameters constitute but a very small fraction of the length of a wave of violet light. In all cases when the vapours of the liquids employed are sufficiently attenuated, no matter what the liquid may be, the visible action commences with the formation of a blue cloud. I would guard myself at the outset against all misconception as to the use of this term. The blue cloud to which I here refer is totally invisible in ordinary daylight. To be seen, it requires to be surrounded by darkness, 7 only being illuminated by a pow- erful beam of light. This blue cloud differs in many important particulars from the finest ordinary clouds, and might justly have assigned to it an in- termediate position between these clouds and true cloudless vapour. 224 Prof. Tyndall on the Blue Colour of the Sky, [Jan. 14, With this explanation, the term “cloud,” or “incipient cloud,” as I pro- pose toemploy it, cannot, I think, be misunderstood. I had been endeavouring to decompose carbonic acid gas by light. A faint bluish cloud, due it may be, or it may not be, to the residue of some vapour previously employed, was formed in the experimental tube. On looking across this cloud through a Nicol’s prism, the line of vision being horizontal, it was found that when the short diagonal of the prism was ver- tical, the quantity of light reaching the eye was greater than when the long diagonal was vertical. When a plate of tourmaline was held between the eye and the bluish cloud, the quantity of light reaching the eye when the axis of the prism was perpendicular to the axis of the illuminating beam, was greater than when the axes of the crystal and of the beam were parallel to each other. This was the result all round the experimental tube. Causing the erystal of tourmaline to revolve round the tube, with its axis perpendicular to the illuminating beam, the quantity of hght that reached the eye was in allits positions a maximum. When the crystallographic axis was par- allel to the axis of the beam, the quantity of light transmitted by the crystal was & minimum. From the illuminated bluish cloud, therefore, polarized light was dis- charged, the direction of maximum polarization being at right angles to the illuminating beam; the plane of vibration of the polarized light, moreover, was that to which the beam was perpendicular*. Thin plates of selenite or of quartz, placed between the Nicol and the bluish cloud, displayed the colours of polarized light, these colours being most vivid when the line of vision was at right angles to the experimental] tube. The plate of selenite usually employed was a circle, thinnest at the centre, and augmenting uniformly in thickness from the centre outwards. When placed in its proper position between the Nicol and the cloud, it ex- hibited a system cf splendidly coloured rings. The cloud here referred to was the first operated upon in the manner described. It may, however, be greatly improved upon by the choice of proper substances, and by the application in proper quantities of the sub- stances chosen. JBenzol, bisulphide of carbon, nitrite of amyl, nitrite of butyl, iodide of allyl, iodide of isopropyl], and many other substances may be employed. I will take the nitrite of butyl as illustrative of the means adopted to secure the best result with reference to the present question. And here it may be mentioned that a vapour, which when alone, or mixed with air in the experimental tube, resists the action of light, or shows but a feeble result of this action, may, by placing it in proximity with an- * T assume here that the plane of vibration is perpendicular to the plane of polariza- tion. This is still an undecided point; but the probabilities are so much in its favour, and it is in my opinion so much preferable to have a physical image on which the mind can rest, that I do not hesitate to employ the phraseology in the text. Even should the assumption prove to be incorrect, no harm will be done by the provisional use of it. 1869. | and on the Polarization of Light. | 220 other gas or vapour, be caused to exhibit under light vigorous, if not violent action. The case is similar to that of carbonic acid gas, which diffused in the atmosphere resists the decompusing action of solar light, but when placed in contiguity with the chlorophy] in the leaves of plants, has its mo- lecules shaken asunder. Dry air was permitted to bubble through the liquid nitrite of butyl until the experimental tube, which had been previously exhausted, was filled with the mixed air and vapour. The visible action of light upon the mix- ture after fifteen minutes’ exposure was slight. The tube was afterwards filled with half an atmosphere of the mixed air and vapour, and another half atmosphere of air which had been permitted to bubble through fresh commercial hydrochloric acid. On sending the beam through this mixture, the action paused barely sufficiently long to show that at che moment of commencement the tube was optically empty. But the pause amounted only to a small fraction of a second, a dense cloud being immediately pre- cipitated upon the beam which traversed the mixture. This cloud began blue, but the advance to whiteness was so rapid as almost to justify the application of the term instantaneous. The dense cloud, looked at perpendicularly to its axis, showed scarcely any signs of polarization. Looked at obliquely the polarization was strong. The experimental tube being again cleansed and exhausted, the mixed air and nitrite-of-butyl vapour was permitted to enter it until the associated mercury column was depressed 75 of an inch. In other words, the air and vapour, united, exercised a pressure not exceeding =1.,, of an atmosphere. Air passed through a solution of hydrochloric acid was then added till the mercury column was depressed three inches. The condensed beam of the electric light passed for some time in darkness through this mixture. There was absolutely nothing within the tube competent to scatter the light. Soon, however, a superbly blue cloud was formed along the track of the beam, and it continued blue sufficiently long to permit ofits thorough examination. The light discharged from the cloud at right angles to its own length was perfectly polarized. By degrees the cloud became of whi- tish blue, and for a time the selenite colours obtained by looking at it nor- mally were exceedingly brilliant. The direction of maximum polarization was distinctly at right angles to the illuminating beam. ‘This continued to be the case as long as the cloud maintained a decided blue colour, and even for some time after the pure blue had changed to whitish blue. But as the light continued to act the cloud became coarser and whiter, particu- larly at its centre, where it at length ceased to discharge polarized light in the direction of the perpendicular, while it continued to so at both its ends. But the cloud which had thus ceased to polarize the light emitted nor- mally, showed vivid selenite colours when looked at ob/iquely. The direc- tion of maximum polarization changed with the texture of the cloud. This point shall receive further illustration subsequently. A blue, equally rich aud more durable, was obtained by employing the 226 Prof. Tyndall on the Blue Colour of the Sky, —_ [Jan. 14, nitrite-of-butyl vapour in a still more attenuated condition. Now the in- stanee here cited is representative. In all cases, and with all substances, the cloud formed at the commencement, when the precipitated particles are sufficiently fine, is d/ue, and it can be made to display a colour rivalling that of the purest Italian sky. In all cases, moreover, this fine blue cloud polarizes perfectly the beam which illuminates it, the direction of polari- zation enclosing an angle of 90° with the axis of the illuminating beam. It is exceedingly interesting to observe both the perfection and the decay of this polarization. For ten or fifteen minutes after its first appearance the light from a vividly illuminated incipient cloud, looked at horizontally, is absolutely quenched by a Nicol’s prism with its longer diagonal vertical. But as the sky-blue is gradually rendered impure by the introduction of par- ticles of too large a size, in other words, as real clouds begin to be formed, the polarization begins to deteriorate, a portion of the light passing through the prism in allits positions. It is worthy of note that for some time after the cessation of perfect polarization the residual light which passes, when the Nicol is inits position of minumum transmission, is of a gorgeous blue, the whiter light of the cloud being extinguished*. When the cloud texture has become sufficiently coarse to approximate to that of ordinary clouds, the rotation of the Nicol ceases to have any sensible effect on the quality of the light discharged normally: The perfection of the polarization in a direction perpendicular to the illu- minating beam isalso illustrated by the following experiment. A Nicol’s prism large enough to embrace the entire beam of the electric lamp was placed between the lamp and the experimental tube. A few bubbles of air carried through the liquid nitrite of butyl were introduced into the tube, and they were followed by about 3 inches (measured by the mercurial gauge) of air which had been passed through aqueous hydrochorie acid. Sending the polarized beam through the tube, I placed myself in front of it, my eye being on a level with its axis, my assistant Mr. Cottrell occupying a similar position behind the tube. The short diagonal of the large Nicol was in the first instanee vertical, the plane of vibration of the emergent beam being therefore also vertical. As the light continued to act, a superb blue cloud visible to both my assistant and myself was slowly formed. But this cloud, so deep and rich when looked at from the positions mentioned, utterly disappeared when looked at verticallg downwards, or vertically upwards. Reflection from the cloud was not possible in these directions. When the large Nicol was slowly turned round its axis, the eye of the observer being on the level of the beam, and the line of vision perpendicular to it, entire extine-- - tion of the light emitted horizontally occurred where the longer diagonal of the large Nicol was vertical. But now a vivid blue cloud was seen when looked at downwards or upwards. This truly fine experiment was first defi- nitely suggested by a remark addressed to me in a letter by Prof. Stokes. * This seems to prove that particles too large to polarize the blue, polarize perfectly light of lower refrangibility. 1869. | and on the Polarization of Light. 227 Now, as regards the polarization of skylight, the greatest stumblingblock has hitherto been that, in accordance with the law of Brewster, which makes the index of refraction the tangent of the polarizing angle, the re- flection which produces perfect polarization would require to be made in air upon air; and indeed this led many of our most eminent men, Brewster himself among the number, to entertain the idea of molecular reflection. I have, however, operated upon substances of widely different refractive indices, and therefore of very different polarizing angles as ordi- narily defined, but the polarization of the beam by the incipient cloud has thus far proved itself to be absolutely independent of the polarizing angle. ‘The law of Brewster does not apply to matter in this condition, and it rests with the undulatory theory to explain why. Whenever the preci- pitated particles are sufficiently fine, no matter what the substance form- ing the particles may be, the direction of maximum polarization is at right angles to the illuminating beam, the polarizing angle for matter in this condition being invariably 45°. This I consider to be a point of capital importance with reference to the present question*. That water-particles, if they could be obtained in this exceedingly fine state of division, would produce the same effects, does not admit of reason- able doubt. And that they must exist in this condition in the higher regions of the atmosphere is, I think, certain. At all events, no other assumption than this is necessary to completely account for the firmamental blue and the polarization of the sky. Suppose our atmosphere surrounded by an envelope impervious to light, but with an aperture on the sunward side through which a parallel beam of solar light could enter and traverse the atmosphere. Surrounded on all sides by air not directly illuminated, the track of such a beam through the iir would resemble that of the parallel beam of the electric lamp through in incipient cloud. The sunbeam would be d/ue, and it would discharge -aterally light in precisely the same condition as that discharged by the in- * The difficulty referred to above is thus expressed by Sir John Herschel :—“ The cause of the polarization is evidently a reflection of the sun’s light upon some- thing. The question is on what? Were the angle of maximum polarization 76°, we should look to water or ice as the reflecting body, however inconceivable the existence in acloudless atmosphere, and a hot summer’s day of unevaporated molecules (particles ?) of water. But though we were once of this opinion, careful observation has satisfied us that 90°, or thereabouts, is a correct angle, and that therefore whatever be the body on which the light has been reflected, ¢f polarized by a single reflection, the polarizing angle must be 45°, and the index of refraction, which is the tangent of that angle, unity ; in other words, the reflection would require to be made in air uponair!’’ ( ‘Meteorology,’ par. 233). + Any particles, if small enough, will produce both the colour and the polarization of the sky. Butis the existence of small water-particles on a hot summer’s day in the higher regions of our atmosphere inconceivable? It is to be remembered that the oxygen and nitrogen of the air behave as a vacuum to radiant heat, the exceedingly attenuated vapour of the higher atmosphere being therefore in practical contact with the cold of space. 228 Prof. Tyndall on the Blue Colour of the Sky, [Jan. 14 eipient cloud. In fact the azure revealed by such a beam would be to all intents and purposes that which I have called a ‘‘ blue cloud” *. _ But, as regards the polarization of the sky ,we know that not only is the - direction of maximum polarization at right angles to the track of the solar beams, but that at certain angular distances, probably variable ones, from the sun, “neutral points,” or points, of no polarization exist, on both sides of which the planes of atmospheric polarization are at right angles to each other. I have made various observations upon this subject which I reserve for the present ; but pending the more-complete examination of the questiou the following facts and observations bearing upon it are submitted to the Royal Society. The parallel beam employed in these experiments tracked its way through the laboratory air exactly as sun-beams are seen to do in the dusty air of London. I have reason to believe that a great portion of the matter thus floating in the laboratory air consists of organic germs, which are capable of imparting a perceptibly bluish tint to the air. This air showed, though far less vividly, all tle effects of polarization obtained with the incipient clouds. The light discharged laterally from the track of the illuminating beam was “ciereaae deh not perfectly, the direction of maximum pone zation being at right nee to the beam. The ental Gann of air thus illuminated was 18 feet long,, and could therefore be looked at very obliquely without any disturbance from a solid envelope. At all points of the beam throughout its entire length the light emitted normally was in the same state of polarization. Keeping the positions of the Nicol and the selenite constant, the same colours were observed throughout the entire beam when the line of vision was perpen- dicular to its length. I then placed myself near the end of the beam as it issued from the electric lamp, and looking through the Nicol and selenite more and more obliquely at the beam, observed the colours fading until they disappeared. Augmenting the obliquity the colours appeared once more, but they were now complementary to the former ones. Hence this beam, like the sky, exhibited its neutral point, at opposite sides of which the light was polarized in planes at right angles to each other. Thinking that the action observed in the laboratory might be caused in * The opinion of Sir John Herschel, connecting the polarization and the blue colour of the sky is verified by the foregoing results. ‘‘ The more the subject [the polarization of skylight] is considered,” writes this eminent philosopher, “ the more it will be found beset with difficulties, and its explanation when arrived at will probably be found to carry with it that of the blue colour of the sky itself and of the great quantity of light it actually does send down to us.”’ ‘‘ We may observe, too,” he adds, “that it is only where the purity of the sky is most absolute that the polarization is developed in its highest degree, and that where there is the slightest perceptible tendency to cirrus it is materially impaired.” This applies word for word to the “ incipient clouds.” 1869. ] and on the Polarization of Light. 229 some way by the vaporous fumes diffused in its air, I had a battery and an electric lamp carried to a room at the top of the Royal Institution. The track of the beam was seen very finely in the air of this room, a length of 14 or 15 feet being attainable. This beam exhibited all the effects observed with the beam in the laboratory. Even the uncondensed electric light falling on the floating matter showed, though faintly, the effects of polarization*. When the air was so sifted as to entirely remove the visible floating matter, it no longer exerted any sensible action upon the light, but behaved like a vacuum, I had varied and confirmed in many ways those experiments on neutral points, operating upon the fumes of chloride of ammonium, the smoke of brown paper, and tobacco smoke, when my attention was drawn by Sir Charles Wheatstone to an important observation communicated to the Paris Academy in 1860 by Professor Govi, of Turint. His observations on the light of comets had led M. Govi to examine a beam of light sent through a room in which was diffused the smoke of incense. He also ope- rated on tobacco smoke. His first brief communication stated the fact of polarization by such smoke, but in his second communication he announced the discovery of a neutral point in the beam, at the opposite sides of which the light was polarized in planes at right angles to each cther. But unlike my observations on the laboratory air, and unlike the action of the sky, the direction of maximum polarization in M. Govi’s experi- ment enclosed a very small angle with the axis of the illuminating beam, The question was left in this condition, and I am not aware that M. Govi or any other investigator has pursued it further. I had noticed, as before stated, that as the clouds formed in the experi- mental tube became denser, the polarization of the light discharged at right angles to the beam became weaker, the direction of maximum pola- rization becoming oblique to the beam. Experiments on the fumes of chloride of ammonium gave me also reason to suspect that the position of the neutral point was not constant, but that it varied with the density of the illuminated fumes. The examination of these questions led to the following new and re- markable results :—the laboratory being well filled with the fumes of in- cense, and sufficient time being allowed for their uniform diffusion, the electric beam was sent through the smoke. From the track of the beam polarized light was discharged, but the direction of maximum polarization, instead of being along the normal, now enclosed an angle of 12° or 13° with the axis of the beam. ; A neutral point, with complementary effects at opposite sides of it, was also exhibited by the beam. The angle enclosed by the axis of the beam, and a line drawn from the neutral point to the observer’s eye, measured in the first instance 66°. * T hope to try Alpine air next summer. + Comptes Rendus, tome li. pp. 360 & 669. 230 Prof. Tyndall on the Blue Colour of the Sky, [Jan. 14; The windows of the laboratory were now opened for somé minutes, a portion of the incense smoke being permitted to escape. On again darkening the room and turning on the beam, the line of vision to the neutral point was found to enclose with the axis of the beam an angle of . 63°. The windows were again opened for a few minutes, more of the smoke beimg permitted to escape. Measured as vefore the angle referred to was found to be 54°. This process was repeated three additional times ; the neutral point was found to recede lower and lower down the beam, the angle between a line drawn from the eye to the neutral point and the axis of the beam falling successively from 54° to 49°, 43° and 33°. The distances, roughly measured, of the neutral point from the lamp, corresponding to the foregoing series of observations, were these :— Ist observation 2 feet 2 inches. 2nd 33 2 5) 6 33 Sieh a panier Vi Ath Bs OD. sssniee ae 5th 53 3 33 7, 33 6th 33 4 33 6 33 At the end of this series of experiments the direction of maximum pola- ization had again become normal to the beam. The laboratory was next filled with the fumes of gunpowder. In five successive experiments, corresponding to five different densities of the gun- powder smoke, the angles enclosed between the line of vision to the neutral point and the axis of the beam were 63°, 50°, 47°, 42°, and 38° respectively. After the clouds of gunpowder had cleared away the laboratory was filled with the fumes of common resin, rendered so dense as to be very irritating to my lungs. The direction of maximum polarization enclosed in this case an angle of 12°, or thereabouts, with the axis of the beam. Looked at, as in the former instances, from a position near the electric lamp no neutral point was observed throughout the entire extent of the beam. When this beam was looked at normally through the selenite and Nicol, the ring system, though not brilliant, was distinct. Keeping the eye upon the plate of selenite and the line of vision normal, the windows were opened, the blinds remaining undrawn. ‘The resinous fumes slowly diminished, and as they did so the ring system became paler. It finally disappeared. Continuing to look along the perpendicular, the rings revived, but now the colours were complementary to the former ones. The neutral point had passed me in its motion down the beam consequent upon the attenuation of the fumes of resin. In the fumes of chloride of ammonium substantially the same results were obtained as those just described. Sufficient I think has been here stated to illustrate the variability of the position of the neutral pomt. The 1869. | and on the Polarization of Light. 201 explanation of the results will probably give new work to the undulatory theory*. ; Before quitting the question of the reversal of the polarization by cloudy matter, I will make one or two additional observations. Some of the clouds formed in the experiments on the chemical action of light are aston- ishing as to form. The experimental tube is cften divided into segments of dense cloud, separated from each other by nodes of finer matter. Looked at normally, as many as four reversals of the plane of polarization have been found in the tube in passing from node to segment, and from segment to node. With the fumes diffused in the laboratory, on the con- trary, there was no change in the polarization along the normal, for here the necessary differences of cloud-texture did not exist. Further. By a puff of tobacco smoke or of condensed steam blown into the illuminated beam, the brilliancy of the colours may be greatly augmented. But with different clouds two different effects are produced. For example, let the ring system observed in the common air be brought to its maximum strength, and then let an attenuated cloud of chloride of ammonium be thrown into the beam at the point looked at; the ring system flashes out with augmented brilliancy, and the character of the polarization remains unchanged. ‘This is also the case when phosphorus or sulphur is burned underneath the beam, so as to cause the fine particles of phosphoric acid or of sulphur to rise into the light. With the sulphur-fumes the bril- liancy of the colours is exceedingly intensified ; but in none of these cases is there any change in the character of the polarization. But when a puff of aqueous cloud, or of the fumes of hydrochloric acid, hydricdic acid, or nitric acid is thrown into the beam, there is a com- plete reversal of the selenite tints. Each of these clouds twists the plane of polarization 90°. On these and kindred points experiments are still in progresst. The idea that the colour of the sky is due to the action of finely divided matter, rendering the atmosphere a turbid medium, through which we look at the darkness of space, dates as far back as Leonardo da Vinci. Newton conceived the colour to be due to exceedingly small water particles acting as thin plates. Goethe’s experiments in connexion with this sub- ject are well known and exceedingly instructive. One very striking observa- tion of Goethe’s referred to what is technically called ‘chill’? by painters, which is due no doubt to extremely fine varnish particles interposed be- tween,the eye anda dark background. Clausius, in two very able memoirs, * Brewster has proved the variability of the position of the neutral point for sky- light with the sun's altitude. Is not the proximate cause of this revealed by the fore- going experiments? + Suir John Herschel has suggested to me that this change of the polarization from positive to negative may indicate a change from polarization by reflection to polarization by refraction. This thought repeatedly occurred to me while looking at the effects ; but it will require much following up before it emerges into clearness. 232 Prof. Tyndall on the Blue Colour of the Sky, [Jan. 14, endeavoured to connect the colours of the sky with suspended water-vesicles, and to show that the important observations of Forbes on condensing steam could also be thus accounted for. Bruecke’s experiments on precipitated mastic were referred to in my last abstract. Helmholtz has ascribed the blueness of the eyes to the action of suspended particles. In an article written nearly nine years ago by myself, the colours of the peat smoke of the cabins of Killarney* and the colours of the sky were referred to one and the same cause, while a chapter of the ‘‘ Glaciers of the Alps,” published in 1860, is also devoted to this question. Roscoe, in con- nexion with his truly beautiful experiments on the photographie power of sky-light, has also given various instances of the production of colour by suspended particles. In the foregoing experiments the azure was produced in az, and exhibited a depth and purity far surpassing any- thing that I have ever seen in mote-filled liquids. Its polarization, more- over, was perfect. In his experiments on fluorescence Professor Stokes had continually to separate the light reflected from the motes suspended in his liquids, the action of which he named “ false dispersion,” from the fluorescent light of the same liquids, which: he ascribed to “ true dispersion.” In fact it is hardly possible to obtain a liquid without motes, which polarize by re- flection the light falling upon them, truly dispersed light bemg un- polarized. At p.530 of his celebrated memoir ‘‘On the Change of the Refrangibility of Light,’ Prof. Stokes adduces some significant facts, and makes some noteworthy remarks, which bear upon our present subject. He notices more particularly a specimen of plate glass which, seen by reflected light, exhibited a blue which was exceedingly like an effect of fluorescence, but which, when properly examined, was found to be an instance of false dispersion. “It often struck me,” he writes, “while engaged in these observations, that when the beam had a continuous appearance, the polarization was more nearly perfect than when it was sparkling, so as to force on the mind the conviction that it arose merely from motest. Indeed in the former case the polarization has often appeared perfect, or all but perfect. It is possible that this may in some measure have been due to the circumstance, that when a given quantity of light is diminished in a given ratio, the illumination is perceived with more diffi- culty when the light is diffused uniformly, than when it is spread over the same space, but collected into specks. Be this as it may, there was at least no tendency observed towards polarization in a plane perpendicular * | have sometimes quenched almost completely, by a Nicol, the light discharged normally from burning leaves in Hyde Park. The blue smoke from the ignited end of a cigar polarizes also, but not perfectly. f + The azure may be produced in the midst of afield of motes. By turning the Nicol, the interstitial blue may be completely quenched, the shining, and apparently unaffected motes, remaining masters of the field. A blue cloud, moreover, may be precipitated in the midst of the azure. An aqueous cloud thus precipitated reverses the polarization ; but on the melting away of the cloud the azure and its polarization remain behind. ’ 1869. ] and on the Polarization of Light. 2993 to the plane of reflection, when the suspended particles became finer, and therefore the beam more nearly continuous.” Through the courtesy of its owner, I have been permitted to see and to experiment with the piece of plate glass above referred to. Placed in front of the electric lamp, whether edgeways or transversely, it discharges bluish polarized light laterally, the colour being by no means a bad imita- tion of the blue of the sky. Prof. Stokes considers that this deportment may be invoked to decide the question of the direction of the vibrations of polarized light. On this poit I would say, if it can be demonstrated that when the particles are small in comparison to the length of a wave of light, the vibrations of a ray refiected by such particles cannot be perpendicular to the vibra- tions of the incident light; then assuredly the experiments recorded in the foregoing communication decide the question in favour of Fresnel’s assumption. As stated above, almost all liquids have motes in them sufficiently nu- merous to polarize sensibly the light, and very beautiful effects may be obtained by simple artificial devices. When, for example, a cell of dis- tilled water is placed in front of the electric lamp, and a slice of the beam permitted to pass through it, scarcely any polarized light is dis- charged, and scarcely any colour produced with a plate of selenite. But while the beam is passing through it, if a bit of soap be agitated in the water above the beam, the moment the infinitesimal particles reach the beam the liquid sends forth laterally almost perfectly polarized light; and if the selenite be employed, vivid colours flash into existence. A still more brilliant result is obtained with mastic dissolved in a great excess of alcohol. The selenite rings constitute an extremely delicate test as to the quantity of motes in a liquid. Commencing with distilled water, for example, a thickish beam of light is necessary to make the polarization of its motes sensible. A much thinner beam sufiices for common water; while with Briicke’s precipitated mastic, a beam too thin to produce any sensible effect with most other liquids, suffices to bring out vividly the selenite colours. January 21, 1869. JOHN PETER GASSIOT, Esg., Vice-President, in the Chair. The Chairman stated that Sir John Macneill and Mr. Edward Solly, who, by reason of non-payment of their annual contributions, ceased to be Fellows of the Society at the last Anniversary, had applied for readmission. Extracts from their letters, explaining the circumstances under which non- payment had occurred, were read, and notice was given that the question of their readmission would be put to the vote at the next Mecting. The following communications were read :— wh YOL. XVII. 204: Mr. Frederick Guthrie on the Thermal [Jan. 21, I. “On the Thermal Resistance of Liquids.” By Frepzricx Gururiz, F.C.S. Communicated by Dr. Tynpaty. Received October 16, 1868. (Abstract. ) The memoir of which the following is an abstract gives an account of some experiments made by the author with the object of determining the laws according to which heat travels by conduction through liquids. After pointing out the importance of the subject, and briefly recapitu- lating the methods previously used and the results obtained by other ex- perimenters, the ‘‘ Diathermometer”’ is described. This instrument, which may be employed for the examination of the thermal resistance or conducting power of solids as well as liquids, has the following form. :28' 10-2 W_.). If we bear in mind (as a fact well proved, chiefly by the researches of General Sabine) that magnetic disturbances are of a cosmical nature, we cannot evidently expect any considerable difference between these two stations, and it might be very naturally supposed that the magnetic varia- tions should be precisely the same in each. This is no doubt approximately true, but nevertheless there is on cer- tain occasions a residual difference between the indications of the two places, and one which is caught by the eye from the automatic records with very great ease, inasmuch as the instrumental time-scale of these is precisely the same for both places; and not only is the time-scale the same, but for slow disturbances the vertical spaces traversed by the traces are the same for both declination magnetographs. We venture to bring before the Royal Society certain results of an inter- comparison of the declination curves of these two observatories, although only of a preliminary nature, because the subject is one of much interest, and because these results appear to exhibit, superposed upon a disturbance which is mainly cosmical, a comparatively small effect, which appears to be more of a local nature, but which is not unworthy of investigation. The records which we have investigated are represented graphically in Plates III. and IV.; and in them the disturbances which have been measured are denoted by figures attached to their extremities. The following Table exhibits the results of these measurements : — Sidgreaves & Stewart. 1868. Plote di. Jan 247 1868. Feb. 5. 1868. _ March 6. 1868. (2) PM 4 | 16 PM 6) IME 1G, dU cae 166 vit March 23. 1868. Mee z 1868. (3) (2) {2) = a (4) \ \G i \ ay ‘) AN 1) (1) \ Wen (2) 3 (22) (4. () : H | y T T i 1 7 as asi te, al PM. if S} 4 5 6 PM. te Wabarae Zi. (e) May 11. 1866. May 20. 1868. ap 1868. Oe (2 vi aC \ GI es (4) 3) 2] _ (4) {1 Fai SER OE oy Sear (taal wae ela ee 7 Or - PM iL 12 AM PM. 2 W.H Wesley del Proc. Roy. Soc Vol.XVI Plate lV. (B) March 21.1868. (A) (B) - farch 20. 1868. Moarch 20: 1868 - ok a March 21. 1868. i of i (4, (2) p (1) (1) (3) x y i) (4) (2) (4) (3) (2) Tie. ean SEC ae SUG ae] eae Ea ee La Poti leas mata Gm : 0 T Oso | AM 5 os AONE 1 Penh ie , es (1) ape April 2. 1868. April 19. 1868. | | (1) aaa A ee es) | i | | | (3) | ot i | (8) \, (f} My | eit \ | | | (3) (5} (7) (2) (2) (11! a (4), (6) uy 5 (2) 14) fh | (3) (3) \ (1! (1) (8) to | I (5) (5) (7) | \ ‘4) (63) : (2) (7) (9) ep (Gea Ves LEE [ae al eee ee are : 6 vi 8 IEDM 1 W. West imap. 1869. ] Kew and Stonyhurst Declination Magnetographs. 237 Dura ation, | Amount of vertical dis- | Abruptness repre- | |Stonyhurst Date Disturbance = i turbance in units of | sented by vertical | minus (see Plate). | measured. scale (hundredths of |disturbance at Kew Kew distur- minutes, es an inch. ) in one minute. | bance. 1868. Kew. Stonyhurst. | Jan. 24 (1) to (2) 14 2 54 ae ies ae Feb. 5 (1) to (2) 12 57 4°2 + 6 2 (2) to (3) | a7 O4 2-6 | +6 Mar. 6. (1) to (2) 17 | 107 115 6°3 | + 8 20(a).| (1) to (2) |long con-) 30 31 slow and curved + 1 tinued. disturbance. 20(B).| (1) to (2) at 30 40 7°5 +-10 2 (3) to (4) 12 40 45 3'3 oo 21 (B).| (1) to (2) 11 | a: 73 6:4 + 2 21(a).| (1) to (2) |long con-| 41 40 slow and curved — 1 tinued. | disturbance. 21(c).| (1) to (2) gb = 80 a5. Ai 3°5 a fe 23. (1) to (2) a =| 61 12 8°7 Saul “ 2 2 are | doubtful. = (5) to (6) 3 32 57 10°7 +25 pe (6) to (7) 2°5 30 40 12:0 +10 a (8) to (9) 10 70 90 7°0 +20 24, (iyte (2):| 12 40 44 3:3 my Apr. 1. (1) to (2) 11 57 60 5:2 + 3 = (3) to (4) 10 63 70 6°3 ae 2 (1) to (2) 45 21 30 4-7 irq se (2) to (3) Fa 11 21 2°8 +10 7 (4) to (5) 4°5 30 51 6°6 +21 = (6) to (7) LS eae 66 11-2 +21 Zs (8) to (9) 4°5 43 65 9°6 +22 sa (10) to (11) 5 39 63 78 +24 19. (1) to (2) 5°5 35 50 6-4 +15 . (3) to (4) 55 27 38 4:9 ag (5) to (6) 10 74 87 74 +13 = (6) to (7) 23 94 99 4°] +5 27. (1) to (2) 16 63 60 4:0 — 3 ” (2) to (3) 7 22 22 3°1 0 9 (4) to (5) 6 52 60 8°7 a= 3 May 11. (1) to (2) 17 53 53 3°1 0 20. (1) to (2) 7 20 -24 2:9 + 4 ” (3) to (4) 12 22 23 1:8 = a 20-21.| (1) to (2) 12 99 111 Aa +21 - (2) to (3) 14 40 65 2°9 +25 » | (3) to (4) 10 20 30 2°0 +10 9 (4) to (5) jlong con- 63 65 | slowand curved | 0 | tinued. | disturbance. It may be inferred from this Table that where the disturbances are slow and long continued, that is to say, where there is scarcely any abruptness, the amount of disturbance as represented by the traces is the same for both places; and this is quite confirmed by placing the curves the one over the other, when they will be found to coincide even in their most minute features. Let us now take the excesses of Stonyhurst over Kew for the varicus disturbances, and endeavour to see if this element is in any way connected with the abruptness of the disturbance. 7 We may for convenience sake divide these excesses inte four groups. 238 | Senhor Capello on the reappearance [Jan. 21], Group I, Excesses not exceeding 4 scale-units. II. Excesses exceeding 4 and not exceeding 9 scale-units. III. Exeesses exceeding 9 and not exceeding 19 scale-units. TV. Excesses above 19 scale-units. Group I. Group IT. Group IIT. Group IV. | Excess Excess Excess Excess ee. ee | ‘ h | Gn , 5. A vll€ a (under 5). pr aepines (under 10). a bpapiness (under 20). Dep eS (above 20). eas pines. | 2 37 6 4-2 10 75 Py es teal (a Z 6-4 6) 2°6 LO 20 25 2°9 —3 4° 8 6-3 11 8-7 25 et Or7 0 ork 5 3°3 10 12°0 29 7°90 9 3°] 3 8:77 10 2°38 21 6°6 4 2:9 5 Bry ail IS 6-4 ee i 18 7 6.3 1l 4°9 we 9°6 4 3°3 9 4°7 13 a4 24 ig 3 5°2 5 Ar] Means 1°5 37 6°6 4:9 14 6°5 22 9 | it would appear from these groups that generally, and on an average, the excess of Stonyhurst over Kew in declination disturbances varies ah the abruptness of the disturbance, being great when the disturbance is very abrupt. It is hoped that on some future occasion further results, derived from an intercomparison of these curves, may be presented to the Society. III. ‘ On the reappearance of some periods of Declination Disturbance at Lisbon during two, three, or several days.’ By Senhor CaPELLo, of the Lisbon Observatory. Communicated by Bat- rour Stewart, LL.D. Received October 28, 1868. Any one who carefully éxamines the magnetograph curves must often notice that there are, during periods of disturbance, synchronous move- ments of the needle during corresponding hours for two, three, or more days. In some cases the repetition is ouly in two or three parallel movements, in others there are true periods of some hours in duration. The repeated periods are not entirely similar, their phases being in general so modified that in some cases their identity can only be recog- nized by a very minute investigation. The same periods, when repeated, have not always the same total dura- tion; nor do they recommence at the same precise hour, but sometimes earlier, and sometimes later, the differences varying from a few minutes to two or three hours. There is also to be remarked in the repeated disturbances a tendency to modify in form, or to level their peaks and hollows, or, on the contrary, to augment the angular forms. SF eT LRN) FE NEE Pe eee Re ee eT | Sea ie ee ame te hee j v K oF ee, , ee ee “a (se oF ano Eee ape —— OF * poe CL at ee a) as aa 6 1da¢ . eee ea ~ 9) Mop Ee coe ; 1 AAP il TAX 1A, 995 Aen Oy, | | oypdw) ‘dart 338MM Top A°1SOM HMA 02 ADIN ee ee ee ; : na) ae : = i eget a . ‘gail thy dy Wire L98h 4 LOS! ce pe gy x — ot oh Uv L9O8L LAP ld 1869.] of some periods of Declination Disturbance at Lisbon. 239 We also see that the greatest number of repetitions belong to the night hours, that is to say, those hours when the movements of the needle are easterly. In the morning hours there do not appear to be any well- marked repetitions. I append examples chosen from the five years complete (July 1863 to June 1868) of the declination curves of the Observatory at Lisbon (see © Plates V. & VI.). ; A greater number of cases might be quoted, but those I have chosen are sufficient for our purpose. Meanwhile I must mention that, in the majority of instances, where no relation apparently exists between one disturbance and the disturbances of the days preceding and following, the disturbances are generally violent. There are twenty-four examples, fifteen of which show repetition on two days, eight on three days, and one only where the curve appears repeated for four days. In order that the identity may be easily recognized, I have placed the curves with their corresponding periods vertical, the hours being marked on each-curve. ; It appears that all the facts exhibited in these examples agree with the cosmical theory; the cause (existing in the sun or in space) appears to continue sometimes during two, three, or several days without undergoing remarkable transformations. The repetition, being sometimes earlier, sometimes later, seems also to indicate that the cause possesses a proper movement; the cause persists, but only comes again into operation when the earth by its diurnal rotation is placed in a similar position or conjunction to that of the preceding days. It would be very curious to analyze the photographs of the sun so as to see if there were any spots in the days of the examples, and if these spots remained without sensible alteration during the days when the disturbances remained so similar. Remarks by B. STEWART. I have compared Senhor Capello’s curves with the corresponding traces of the declination at Kew, and it would appear that the Lisbon disturb- ances are almost invariably reproduced at Kew at the same time, only to a greater extent. It would further appear that the same amount of similarity which the various Lisbon curves exhibit is also exhibited in the corre- sponding Kew curves. Opinions may differ with regard to the strength of the evidence exhi- bited by Senhor Capello in support of the peculiar action of the disturbing forces of which he is an advocate. It would appear to me that the strongest point in favour of the hypothesis is not so much the repetition. of a single disturbance as the repetition of a complicated disturbance in most if not all of its sinuosities. Several examples of this occur in these diagrams. 240 Mr. C. Tomlinsen on the Action of Solid Nuclei [Jan. 21, IV. “On the Action of Solid Nuclei in hberating Vapour from Boiling Liquids.” By Cuartes Tomuinson, F.R.S. Received November 5, 1868. History.— During many years after the invention of the barometer and the consequent discovery of atmospheric pressure, the boiling-point of a liquid was defined to be the temperature at which its evaporating tendency is,equal to the common pressure of the atmosphere, or the lowest tempera- ture at which its vapour can have the elasticity of common air. About the middle of the last century it was noticed by several distin- guished Fellows of this Society that the boiling-point of water under a constant pressure varies within certaim limits, according to the depth to which the thermometer is plunged into the beiling hquid. In the Report on Thermometers published in the Transactions for 1777, it was stated that the steam from boiling water fairly represents the atmo- spheric pressure ; and it was recommended that, in determining the boiling- point, the water be boiled in a metal vessel constructed so as to allow the bulb, and nearly the whole of that part cf the stem that contained mercury, to be surrounded by the steam. In the fine experiments undertaken by Dalton, Watt, Robison, Southern, and others for determining the pressures of saturated steam at different temperatures above and below the standard boiling-point, it was noticed that if a minute portion of soda or of some salt soluble in water, and not capable of rising in vapour with it, be allowed to ascend to the top of the mereury, the column rises, thereby indicating a diminished pressure of steam. ‘The adhesion of the soda to the water tends to restrain the water from evaporating, and thus the steam-emitting tension ofa solution of soda is measurably less than that of pure water at the same temperature. In 1785 Achard* showed by a number of experiments that the boiling- point of water, under a constant pressure, is much more inconstant in metallic than in glass vessels. He also noticed that if, while water was boiling steadily in a glass vessel, a drachm of iron-filings or cf some other insoluble solid were added to the water, the boiling-point was lowered 1° Reaumur or even more, and that there were considerable differences in the amount of depression, according as the same substance was in powder or in lump. In 1803 De Luct stated, in very precise terms, that boiling is produced by the bubbles of air which the heat disengages from the liquid. If the water be completely purged of air it cannot boil, because steam can only form on free surfaces, such as the air-bubbles present. Deprived of air, water can boil only on the upper or free surface. Water in a tube from which the air had been earefully expelled was raised to 2343° F. without boiling. * Nouveaux Mémoires de l’ Académie Royale de Berlin for 1784-85. t Introduction 4 la Physique terrestre par les Fluides expansibles. Paris, 1803. 1869. ] in liberating Vapour from Boiling Liquids. 241 Tn 1812, and again in 1817, Gay-Lussac* noticed Achard’s experiments on the effect of the vessel on the boiling-point, and of metal turnings, charcoal powder, and pounded glass in lowering it. He supposed the boiling-point to vary in different vessels according to the nature of their surfaces, and that the variation depends both on the conducting-power of the material for heat and on the polish of the surfaces. When water is boiling in a_ glass vessel, the temperature is higher than ina metal one; but if a few pinches of iron-filings be put in, the boiling goes on as in a metal vessel. Without this aid the water boils in bursts, the steam having to overcome the cohesion or viscosity of the liquid, and its resistance to change of state. The adhesion of the liquid to the vessel must also be a force analogous to its viscosity. The use of platinum is recommended for preventing soubresauts. In 1825 Bosteck+ noticed that ether in a matras over a spirit-lamp boiled at 112° F.; but in a test-tube put into hot water it did not begin to boil under 150°, and on one occasion 175°. Bits of cedar-wood put into the ether made it boil at 110°; the wood was covered with bubbles until (according to Bostock) having discharged all its air, it became inactive and sank. Bits of quill, feather, wire, pounded glass, &c. also lowered the boiling-point considerably. A thermometer plunged into the ether pro- duced bubbles many degrees below the point at which ebulliticn took place when the thermometer was not inserted: this effect soon ceased; but by alternately plunging the thermometer into the ether and removing it, the bubbles were produced at each immersion. Leerand{ in 1835 also referred bursting ebullition and soubresauts to the absence of air in the liquid. Many salts prevent soudresauts; others, such as the neutral tartrate of potash, favour them. In 1842 Marcet§. considered that iron, zinc, and other substances tend to depress the boiling-point, because they have a less molecular adhesion for water than glass has. If the vessel be coated with a thin layer of sul- phur, gum-lac, or any similar substance that has no sensible adhesion for water, the temperatures of the water and of the steam are alike. The boiling-point varies in flasks of different kinds of glass, and in the same flask at different times. In a flask used for holding sulphuric acid the boiling-point of pure water was 106° C. These variations are referred to molecular changes on the surface of the glass. In 1843 Donny || referred to the powerful influence of air or gases dis- solved in the liquid on the phenomena of ebullition; but as his theory is the same as that advanced by De Luc many years before, it is not necessary to notice it further. In 1861 Dufour described an experiment in which globules of water * Annales de Chimie, vol. Ixxxii. p. 171; Annales de Chimie et de Physique, vol. vii. p. 807. t Annals of Philosophy, N.§. vol. ix. p. 1€6. + Annales de Chimie et de Physique, vol. lix. § Annales de Chimie et de Physique, 3e Série, vol. v. p. 449. || Mémoires couronnés par l’Académie Royale de Bruxelles, vol. xvii. pub. 1845. € Archives de la Bibliotheque Universelle de Geneve. 242 Mr. C. Tomlinson on the Action of Solid Nuclei [Jan. 21, suspended in hot oil are said to have been raised to from 110° to 178° C. without boiling; but the moment they were touched with a solid they burst into steam. Porous bodies acted best because, it is said, they carried down air to the globules. Such is a very brief notice of a few of the numerous memoirs that have been published on the subject of boiling. The writers are all more or less disposed to adopt the following conclusions :—(1) that liquids boil with difficulty, or produce only sudden flashes of steam, as soon as the air which had been dissolved in them is expelled by heat; (2) that those liquids that have the weakest affinity for air, such as sulphuric acid, alcohol, ether, &c., boil with the greatest difficulty ; (3) that the adhesion of the liquid to the vessel, and the mutual cohesion of its own molecules, cause the liquid to boil in bursts, and produce soubresauts; (4) that the action of solid sub- stances in preventing soubresauts is by carrying down air. My object in introducing a new set of experiments on boiling is (1) to show the action of solid nuclei in liberating vapour from liquids at or near the boiling-point; (2) to define the conditions under which soudresauts take place; and (3) to show what is the best remedy for the same. Definition.—A liquid at or near the boiling-point is a supersaturated solution of its own vapour, constituted exactly like soda-water, Seltzer-water, champagne, and solutions of some soluble gases. Action of Nuclei.—lf the above definition be admitted, the behaviour of solid substances in liberating vapour on some occasions, and remaining ‘‘inactive’’ on others, becomes clear. If the solid be chemically clean, the solution of vapour will adhere to it as a whole, and there will be no libe- ration of vapour. If, on the contrary, the solid be unclean, the adhesion between the vapour and the solid will remain the same as before, while the adhesion between the liquid and the solid will be more or less diminished, according to the nature of the impurity and the liquid operated on; and hence there will be a separation of vapour. But not only is it necessary to distinguish bodies as chemically clean or unclean, but also as porous or compact. The same force by which one volume of charcoal absorbs 98 volumes of ammoniacal gas, enables charceal and some other porous bodies, when thrown into a boilmg liquid, to sepa- rate the vapour from it, and thus to act as most efficient nuclei. The liquids operated on were water, alcohol, ether, wood-spirit, naphtha, carbonic disulphide, benzole, paraffine oil, oil of turpentine, rosemary, and a few other essential oils. The liquids with low boiling-points are convenient for illustrating the _ phenomena in question. Any one of them ina tube about one-third or one- half filled may be raised to the boiling-point by putting the tube into hot water contained in a six- or eight-ounce German flask standing on the ring of a retort-stand. The tube should fit loosely into the neck, and rest on the bottom of the flask. In reheating the water a small spirit-lamp flame may be applied, not directly under the tube, but on one side of it, the 1869. ] in liberating Vapour from Boiling Liquids. 243 object being to keep the liquid in the tube at or near the boiling-point, but not actually boiling. The temperature of the liquid in the tube may be taken from time to time, and the thermometer, when not in use, may be kept in a tall narrow glass containing a little of the liquid under examination. Carbonic disulphide, from its low boiling-point, gives off vapour with facility, and is consequently well adapted to show the action of solid nuclei. When the tube was placed in the hot water, a quantity of dense white vapour ascended from the surface of the liquid to the top of the tube; but instead of overfiowing it condensed in copious tears, which fell back into the liquid and caused a strong descending current. On touching the sur- face of the liquid with the end of a brass wire, violent ebullition set in, the bubbles rising to near the mouth of the tube. The boiling ceased alto- gether as soon as the wire was removed; but when the surface was touched with a strip of paper, it set in as violently as before. Now in these two experiments no air could have been carried down, since the surface only was touched, and the boiling continued only while the solid was kept in contact with such surface. Iron wire also liberated vapour abundantly. The end of a glass rod was active at two small points, libe- rating from each a rapid stream of bubbles, the remaining portions being clean, or having soon become so by the action of the hot liquid, since glass is readily cieansed by liquids near the boiling-point. But it is said that rough bodies are most favourable to the liberation of vapour. The hot carbonic disulphide was touched with a rat’s-tail file, and it produced furious boiling. The file was then held in the flame of a spirit-lamp, and while hot placed in the upper part of the tube, so that it might cool down to about the temperature of the liquid, and yet be shel- tered from the air. On teuching the surface of the disulphide with the end of the file, there was no liberation of vapour; and the file was slowly passed to the bottom of the liquid, but still there was no action. ‘The file was now taken out and waved in the air; on reinserting it into the liquid, there was a burst of vapour arising from some mote or speck of, dust caught by the file from the air. The file was quickly cleaned by the liquid, and it became inactive as before. It was again taken out and waved in the air, and on ence more putting it into the liquid boiling set in again. A tube containing ether was put into the hot-water bath; it quickly reached the boilig-point, and two specks in the tube became active in discharging rapid streams of bubbles. Specks of this kind are often powerful as nuclei in separating gas. from soda-water &c., and in causing the sudden crystallization of supersaturated saline solutions. Such specks i the bottoms of flasks, beakers, and retorts are powerful nuclei in sepa- rating vapour from a liquid during the boilmg. The vapour seems to be generated by these points, and to proceed from them to the surface in rapidly enlarging bubbles. These specks consist of iron, carbon, or some other material which is not so readily cleaned as the glass, or they present a porous point to the vapour. 244: Mr. C. Tomlinson on the Action of Schid Nuclei [Jan. 21, As the temperature of the water-bath fell, the ether in the tube ceased to give off bubbles of vapour. A small pellet of writing-paper was now thrown in: the liquid boiled up furiously, the paper being much agitated, when suddenly.it sank as if dead, and all vapour-giving action ceased. It had become, in fact, chemically clean. The paper was removed and a brass wire passed to the bottom of the tube, when the whole liquid boiled up briskly during a few seconds; when, the wire becoming chemically ciean, all action ceased, except from a point near the bottom of the wire, which continued to pour off a fine stream of bubbles during some minutes. The wire was now taken out and filed, in order to get rid of this nucleus. On returning it to the tube the ether boiled up as before, the handling and filing having made the whole immersed surface unclean ; but the ether soon cleaned it, and it became inactive; but the active point was not only not got rid of, but there were now two points rapidly discharging vapour. These points are probably portions of porous dross entangled with the metal. During these experiments the ether was maintained at about 96°, and it boiled only when a solid nucleus was introduced. Methylated spirit was raised to about 175°. A piece of flint that had long been exposed to the air was put into the tube; it gave off vapour from its surface in abundance. The flint was taken out a ea broken, and the two fragments were returned to the spirit. The newly fractured surfaces, being chemically clean, were quite inactive, not a single bubble of vapour appear- ing on them, while the outer surface continued to give off vapour as before. A strip of slate gave off vapour from a number of points in beth surfaces ; it was split into two strips and replaced in the hot liquid; the old surfaces were active as before, but the fresh surfaces were perfectly inactive. Mica and selenite do not answer well for these experiments. In the specimens tried, air containing dust had been dragged in in patches between the plates; these, when newly split and put into soda water, showed consider- able portions that were chemically clean in the midst of unclean patches. The action of nuclei can be well! exhibited in oils with high boiling-points, such as the essential oil of turpentine, rosemary, &c. When the oil is boiling in a tube over a spirit-lamp, a strip of slate with one new surface may be introduced before the lamp is removed, so as to prevent the oul from being chilled. If, now, the lamp be taken away, vapour will pour off from the unclean surface of the slate during some minutes, while the freshly fractured surface will be quite inactive. The behaviour of nuclei, as thus far described, is the same as for super-- saturated saline and gaseous solutions. A chemically clean nucleus will not separate either the salt or the gas from solution; a chemically unclean nucleus will do so immediately it comes in contact with the solution. If the definition I have given of a liquid at or near the boiling-point be accepted, and it be admitted that solid nuclei behave in the same manner under the same conditions in separating salt, or gas, or vapour from solu- tion, what is the action in this respect of air and gases? 1869.] in liberating Vapour from Boiling Liquids. 245 It has been maintained that air is a powerful nucleus in separating salt from a supersaturated solution, that it is the air alone, as carried down by the solid, that acts as a nucleus in separating gases from solution, and that if air be absent from a liquid it cannot boil, because there is nothing for the vapour to expand upon. I have shown in former experiments that, in the case of supersaturated saline solutions, air is not a nucleus; but that when it appears to be so, it is merely acting the part of a carrier of some chemically unclean mote or speck of dust. I have also shown that masses of air may be introduced into soda-water without any separation of the gas, provided the conditions of chemical purity be observed. A wire-gauze cage, for example, full of air can be lowered into soda water without producing any discharge of gas into the cage, or any separation of gas from the surface of the cage, so long as it is chemically clean; when unclean, there is an abundant separation of gas from the surface of the cage, but the enclosed air remains purely passive all the time. A similar result may be obtained in the case of a liquid at or near the boiling-point, if precautions be taken to raise the cage to the temperature of the liquid before introducing it. The cage used in these experiments was smaller than that used in the soda-water experiments. It was five-eighths of an inch in diameter, and an inch and a half in length, and made of fine iron-wire gauze, such as is used by millers in bolting meal. Two of these cages were prepared. One was cleaned by being put into boiling spirits of wine; it was rinsed in clean water, and so held in the steam of pure water boiling in a test-tube, so that the cage and the enclosed air might be adjusted to the temperature of the water. The cage was gently lowered into the water the moment the spirit- lamp was withdrawn. ‘There was no escape of vapour; there was no violent boiling up, which must have ensued had air been a nucleus. But here was a mass of air in the midst of the liquid, and yet the steam did not expand into it. The openings into the cage must have been very much larger than the diameter of the globules of air which are supposed always to be present when a liguid is boiling, and yet there was no separation of vapour. This clean cage was removed, and the other cage, just as it had left the hands of the maker, was held in the steam of the water of the same tube, and the moment the lamp was removed gently lowered into the water. It was instantly and completely covered with bubbles of steam; but there was no expansion of steam into the cage, and no escape upwards either of steam or of air. A good result was obtained with ine oil boiling at 320°. While the cage was being lowered, it becam led about one- half with the liquid, but when lege submerged ieee was no action whatever. But, per- haps, it may be said that the liquid was now so far below the boiling-point as to be incapable of giving off vapour to any nucleus, clean or unclean. To test this, a small slic a paper was thrown in; the liquid immediately pa 4 efi 246 Mr. C. Tomlinson on the Action of Solid Nuclei [Jan. 21 began to seethe audibly, and it continued to give off vapour during more than two minutes, the paper pellet resting during the latter part of the time on the top of the cage. Similar good results were also obtained with oil of turpentine. The cage was also lowered into naphtha, and some of the other low boiling liquids, and whenever there was an escape of vapour, it could always be referred to some unclean portion of the cage. Care is required in lowering the cage, so as to expand the air; for unless this be properly done, there may be a violent burst of air when the cage is near the bottom of the tube. It really does seem to me that too much importance has been attached to the presence of air and gases in water and other liquids as a necessary conditicn of their boiling. Cold water dissolves only one-fiftieth of its volume of nitrogen, and one twenty-fifth of its volume of oxygen, and these small quantities must be reduced to an almost inappreciable amount in hot or boiling water ; and yet some observers represent boiling water purged of air as reabsorbing it eagerly while still boiling. The only function I should assign to air would be that of diminishing somewhat the cohesive force of the liquid molecules. If the tube be of narrow bore and chemi- cally clean, or becomes so by the action of the Higuid, adhesion has some influence in raising the boiling-point. But the mode of heating the liquid is of still greater importance in this respect, as is evident in De Lue’s ex- periments, and was well brought out in Bosteck’s. In the latter case ether in a matrass over a spirit- Agi: boiled at 112°; but in a test-tube in hot water at 150° andeven 175° F. The difference in the conditions of heating has doubtless been regarded as too evident to be insisted on; and yet it is of great importance in studying the conditions under which the boiling- point of a liquid becomes raised. When the vessel is placed over a flame, that part in contact with the flame is heated, or tends to become heated, much more strongly than the rest of the vessel. This produces active convective currents, the effect of which is to loosen the cohesion of the particles, and so allow vapour to form more easily. When the water once begins to assume the elastic form, it does so from the overheated part of the vessel in contact with the fiame. In a clean glass vessel contaiming distilled water placed over a spirit-lamp, no aie HUIS form, either on the sides or on the clean thermometer. They appear on the bottom surface only, playing about and disappearing upwards until the water is at about 160°. At about 180° small steam-bubbles are given off from the bottom heated sur- face with a crackling noise; they rise rapidly, expand, and disappear before reaching the surface; and until they succeed in doing so, the convective — currents are active. When the bubbles reach the surface and discharge steam into the air, the whole column in broken up, echesion is overcome, and the boiling is maintained, while the liquid gradually disappears. Such is the process of boiling in a vessel heated by a flame from below. When, however, all that part of the vessel (such as a test-tube) that contains liquid is put into a hot bath, the whole column is equably heated, or 1869. ] in liberating Vapour from Boiling Liquids. 247 rather the top of the column isa little more heated than the bottom (since the upper layers of hot water are at a higher temperature than the lower ones), and the effect of this is that there are no convective currents; cohesion is diminished by expansion, not by convection. The whole column being thus about equally heated at the same moment, vapour cannot form at one’ part in preference to another, except at the surface ; but the whole column of liquid goes on expanding under an increasing temperature until, becom- ing more and more supersaturated with its own vapour, the increasing elastic force suddenly overcoming pressure, cohesion, and adhesion, there is a sudden burst of vapour. Or before this disruption takes place, if the surface be touched with a chemically unclean solid, the vapour adhering to it and thus set free, starts the vapour-giving action, just as touching a cold supersaturated saline solution starts crystallization, and the action once begun is propagated. If, however, the tube containing the ether &c. be not chemically clean, if there be minute specks and points in the glass (as there often are) all but invisible to the naked eye, and these be porous or not chemically clean, vapour will stream from them long before the temperature of disruption is attained, and there will be no disruption at all. These points and specks account for many anomalous cases of crystallization which occur in operat- ing with supersaturated saline solutions, and which puzzled Lowel and other observers. We may have, for example, two tubes apparently pre- cisely alike, cleaned in the same manner, containing a hot filtered solution of the same salt, of the same strength, and exposed to the same cooling influence. One of the solntions in cooling will suddenly become solid, while the other will remain liquid, and continue so during weeks and months. On examining the solidified solution, it will be found that crys- tallization has been promoted by a minute speck or point at some part of the tube, no matter where, and from this point, as from a centre, proceed fine crystalline needles radiating in all directions. Soubresauts.—Liquids which render the surface of the vessel in which they are boiled or distilled chemically clean, thereby favour the production of soubresauts, or jumping ebullition. This is a mechanical action which does not seem to have been sufficientiy explained. Thus Gay-Lusaac says, “‘ When the liquid is above the boiling-point, it is in a forced state: instantly a burst of vapour is formed, the liquor is thrown out, and the vessel itself raised.” But why should the vessel be raised? The burst of vapour follows an upward motion along the line of least resistance, which, so far from raising the vessel, has a precisely contrary effect. It produces an equal reaction in a downward direction, tending to force the vessel further into the ring of the retort-stand, or other support, and it is the rebound from this that causes the vessel to rise. .If proof be required of the trutkof this explana- tion, it can easily be supplied by suspending, by means of an india-rubber line or a bit of elastic, a tube containing crystals of sodic sulphate and a 248 Mr. C. Tomlinson on the Action of Sold Nuclei [Jan. 21, very little water. If the flame of a spirit-lamp be applied to the bottom of the tube, the crystals soon fuse and throw down a portion of the anhy- drous salt, which is highly favourable to the production of soubresauts. If the tube be suspended against an upright surface, with a mark opposite the mouth, it will be easily seen that every burst of steam is accompanied by a violent downward jerk. In order to mitigate or prevent this bumping ebullition, it has long been the practice to intreduce into the retort or other vessel, a few angular pieces of solid matter, metallic being the best—such as platinum-foil, silver, copper, or platinum-wire or filings, fragments of cork or torn cartridge- paper. Faraday names these substances ‘‘ promoters of vaporization,” without explaining their action; and he remarks that if any one of these substances be suddenly introduced, ‘‘it is probable that the consequent burst of vapour would be so instantaneous and strong as to do more harm than the bumping itself’ *. This is precisely the action of an unclean solid introduced into a supersaturated gaseous solution, or in the case of a liquid at or near the boiling-point, into a supersaturated vaporous solution. When sand, fragments of glass, or other non-metallic substances are used for preventing bumping, they facilitate the escape of vapour only so. long as they are unclean; but as siliceous bodies are readily cleansed by the action of boiling water and other boiling liquids, they often aggravate the evil. For example, two ounces of distilled water containing a little sand from the sand-bath, were boiled in a six-ounce German flask over a spirit-lamp. The boiling proceeded briskly without any kicking. The lamp was removed and the flask left to cool. Next morning the lamp was again put under the flask, when the water boiled with such violent kick- ings as to endanger the safety of the vessel. ‘The sand had become che- mically clean during the first boiling. If sand, cleaned by means of sulphurie acid and much rinsing, be added to water in the first mstance, the kickings set in at once. Similar results were obtained with fragments of glass ; when chemically clean, they serve to enlarge the adhesion surfaces, instead of the vapour-giving surfaces, and so increase the resistance to be overcome. With respect to the action of metals, there is no advantage in making them sharp-pointed, nor in having their surfaces rough ; only, in the latter case, unclean vapour-giving substances are apt to lodge in the rough lines, or between the teeth, and so far a file or other rough body may be of ad- vantage. Metal filings are also liable to collect dust and specks of dirt, which act as nuclei. The following experiment shows the action of clean, as compared with unclean iron-filings. A flask cleaned by means of sul- phuric acid contained four ounces of distilled water, which boiled at 215°. Some iron-filings that had long been kept in spirits of wine were thrown in. There was a good deal of kicking, and the temperature oscillated between 213,75° and 2134,°.. Some unclean filings were thrown in, and the effect * Chemical Manipulation, p. 200. ; 1869. | in liberating Vapour from Botling Liquids. 249 was instantaneous. Copious streams of bubbles proceeded from the filings, the soubresauts ceased, and the temperature fell to 21142°. Similar re- sults were obtained with copper-filings, and copper and brass wire, clean and unclean, and also with platinum foil and wire. An experiment with mercury may perhaps be of interest. The metal was cleaned by being repeatedly shaken up with dilute nitric acid; and after standing some time under it, a portion was drawn off from the bottom. Five ounces of water in a clean flask boiled at 21343°. Enough mercury was poured in to form a ring at the bottom of the flask. The water soon regained its temperature, and even rose to 214°, with a good deal of bump- ing—steam forming under the mercury and distending it into a large he- misphere, which burst with a kick. The temperature varied between 213,8,° and 214°. It would have been dangerous to have entirely covered the bottom with the metal; for, as it was, the bursts of vapour were of an ex- plosive character. While this uneasy boiling was going on, a very little dirty mereury was added to the flask, and, although the quantity was not more than one-sixth of that previously added, the effect was remarkable. Instead of the uneasy, kicking, jerking bursts, the whole instantly changed into a brisk, easy, soft boiling, rapid volleys of steam-balls being given off by the metal, breaking up the mass of water, while the temperature tre- mained steady at 212,2,°. It will thus be seen that the vitreous and metallic bodies employed in these experiments, as also the bits of paper, shavings of cedar-wood, &c., are efficient as nuclei only so long as they are chemically unclean. When clean they beeome inactive as “ promoters of vaporization.” Action of Porous Bodies.— But there are certain bodies, such as charcoal, coke, &c., that I have not been able to make inactive, either by the action of strong sulphuric or nitric acid, or by repeated boiling in water, ether, spirits of wine, naphtha, &c. The same piece of charcoal held in the flame of a spirit-lamp and then put into soda-water, or into a liquid at or near the boiling-point, will liberate gas or vapour without any apparent diminution of its powers. It may be transferred from one liquid to another, from ether to alcohol, from alcohol to water, and from water to oil of turpentine without ceasing to perform useful work in setting vapour free, making the voiling soft and easy, and preventing sowbresauts*. The same remark ap- plies to coke. It may be cleaned in the strongest acids, washed in water and alkalies without losing any of its vigour as a liberator of vapour from a hot liquid. It is quite remarkable to see how efficiently a lump of coke acts in a vessel of boiling water in giving off vapour, promoting tranquil boiling, and preventing the jumping of the vessel. Platinum sponge is also active. A small piece of this substance at the bottom of a flask of boiling water will send up vigorous jets of steam-bubbles, raising the water * Box-wood charcoal, which Saussure found so efficacious in his experiments on the absorption of gases, is very active in boiling liquids; but specimens of chareoal and of chareoal-bark from the softer wood are also of untiring activity. VOL, XVII. T 250 Mr. C. Tomlinson on the Action of Solid Nuclei [Jan. 21, far above the surface. As in the case of charcoal and coke, the liberation of vapour is confined to the solid nucleus, no part of the flask giving off visible vapour. The following data show the influence of the solid upon the temperature. Five ounces of distilled water in a clean flask boiled at 21313°. A small lump of platinum sponge was held in the flame of a pee? cal then put into the flask. The temperature subsided to 212,4,°, and re- mained so for some time. A second small piece of sponge was similarly heated and put into the flask ; it was as active as the former piece in libe- rating vapour, but there was no further depression of temperature. The water was now allowed to get cold; and on again applying the spirit-lamp there was a good deal of loud explosive bumping, until the water was near 200°, when the platinum sponge began to give off steam and the boiling be- came soft and regular. I have not the command of apparatus for determining the volume of vapour absorbed by platinum sponge, charcoal, &c. at given temperatures ; but it would not be difficult to do so by one or other of the contrivances made by Dalton and Gay-Lussac in determining the elasticity of the va- pours of liquids at the boiling-poimt. It would also be interesting to study the action of nuclei on liquids heated above the pressure of one atmosphere. . Meerschaum is also an active nucleus. A bit of this substance was thrown into a tube filled about one-third with newly distilled oil of turpentine which boiled at about 310°. The whole tube became filled with bubbles ; and long after the lamp was removed the nucleus continued to liberate nu- merous streams of bubbles, an effect that is common to all porous bodies tried in these experiments, but more remarkable in some cases than others*. A fine-grained pumice-stone cleaned in nitric acid, and another piece not cleaned, were both very active in giving off vapour from liquids. As in the_ case of charcoal and meerschaum, they soon sank to the bottom of the ves- sel, unless buoyed up by the steam while the lamp was burning under the flask, and continued to pour off vapour so long as the liquid was at or near the boiling-peint. When the water was below 100°, the flask was put under the receiver of an air-pump and the air exhausted; the water soon boiled, and the pumice was as active as before in liberating vapour. Chalk, plumbago, and platinum balls are all active promoters of vapori- zation. In the absorption of gases by charcoal, Saussure found that, if a piece of charcoal impregnated with one gas were introduced into another gas, a por- * Jllustrations were frequently afforded in these experiments of the different action — of a clean as compared with an unclean surface. In the experiment in hand, in order to take the temperature of the boiling turpentine, the thermometer-bulb and part of the stem were made chemically clean ; but having on one occasion to leave the thermometer in the tube, its bulb was made to rest on the bottom, so that about an inch and a half of the stem that had not been made chemically clean became immersed. This portion was instantly covered with minute beads of vapour, so as to giveit a frosted appearance, exactly distinguishing the clean from the unclean portion. 1869. | in liberating Vapour from Boiling Liquids. 251 tion of the absorbed gas might either be driven out or further condensed. A somewhat similar action may be noticed by transferring a piece of charcoal from one boiling liquid to another. For example, a small piece of well- burnt charcoal from the centre of a lump was held in the flame of a spirit- | lamp until it was red-hot, and so put into boiling water. It was not very active at first, but it soon became so, and continued so as long as the heat was kept up. After about half an hour’s action the charcoal was taken out, dried in a cloth, and put into boiling turpentine; here it was amazingly active, and continued so during some minutes after the lamp had been removed. The charcoal was dried on filtering-paper and put into spirits of" wine; it was now much less active than fresh charcoal would have been ; and in ether its activity was still more diminished. The charcoal was next put into hot water, and it at once started into activity; it was far more vigorous than clean charcoal is in water under any of the circumstances that have come under my notice. The charcoal was doubly active, not only from its porosity, but also from its want of chemical purity. On this latter account charcoal that has been used in boiling turpentine is singu- larly active in boiling water. And this sufficiently accounts for the fact noticed by Dufour, that when globules of water in hot oil came into con- tact with the thermometer or the sides of the vessel, they at once exploded into steam ; but I believe the globules of water were in the spheroidal state in all the cases of very high temperature cited by him. The diminished activity of charcoal and other porous bodies depends on the order in which they are introduced into liquids of different boiling- points. If transferred from a liquid with a high into one with a low boil- ing-point, the charcoal is more or less inactive, its absorptive powers being already satisfied ; but if transferred from a liquid with a low into one with a high boiling-point its activity is mcreased, not only by the expulsion of the liquid absorbed, but also by the want of chemical purity that accom- panies the process. Thus meerschaum or coke that is very active in tur- pentine becomes inactive when transferred to spirits of wine; but after a time a single point in the solid may become active, and produce a rapidly rising inverted cone of vapour that has a very striking effect. Conclusions.—The conclusions to which the foregoing details seem to lead are :— | (1) That a liquid at or near the boiling-point is a supersaturated solution of its own vapour. (2) That a solid non-porous nucleus either is or is not efficient in libe- rating vapour, according as it is chemically unclean or clean. (3) That as porous bodies do not become inactive, the proper nucleus for liberating vapour in the operations of boiling and distilling liquids, and for preventing soubresauts, is charcoal, coke, or some other porous body. P.S. (Jan. 21, 1869).—As it seemed probable that some numerical re- sults as to the action of porous nuclei in increasing the amount of the x 2 252 Mr. C. Tomlinson on the Action of Nuclei. [Jan. 28, distillate might be expected, I asked my friend Mr. Hatcher, late of King’s College, to perform some experiments for me. The following are selected from his results. 1. A glass flask with a wide neck was filled about one-third with distilled water ; it was boiled over a gas-burner, rapidly weighed, and replaced over the burner. After boiling twenty minutes, it was weighed again. The flask was onee more filled to the original quantity, and some bits of coke were added; it was boiled and weighed as before, the gas-flame remaining unaltered all the time. Results.— Water boiled away in the first trial (water only) 995 grains, in the second trial (with coke) 1130 grains. Ratio of products, as 100: 113°6. 2. Water was made to distil freely from a still, and the quantity col- lected in fifteen minutes was weighed. A few pieces of coke were then added to the water in the still, and the distillate collected again during fifteen minutes. Results.— Distillate from water only, 293 grains; from water with coke, 310 grains. Ratio of products, as 100 : 105°8. 3. A similar trial was made with common wood-charcoal; but the vessel having been made much cleaner by the action of the first boiling, the water boiled irregularly, with bumping. The addition of the charcoal made the boiling tranquil and regular. Results.—Distillate from water only, 262 grains; from water with charcoal, 334 grains. Ratio of results, as 100 : 127°4. January 28, 1869. Lieut.-General SABINE, President, in the Chair. Pursuant to notice given at the last Meeting, Sir Henry Holland pro- posed, and Lord Justice Bovill seconded The Most Noble the Marquis of Salisbury for election and immediate ballot. The ballot having been taken, the Marquis of Salisbury was declared duly elected. Pursuant to notice given at the last Meeting, the question of the read- mission of Sir John Maeneill and Mr. Edward Solly was put to the vote, and the ballot having been taken, those two gentlemen were declared read- mitted into the Society. The following communications were read :— 1869. ] Dr. Tnaudichum on Luteine. 253 I, “Researches conducted for the Medical Department of the Privy Council, at the Pathological Laboratory of St. Thomas’s Hospital.” By J. L. W. Toupicnum, M.D. Communicated by Joun Simon, Esq. Third Series—Results of Researches on _ Luteine and the Spectra of Yellow Organic Substances con- tained in Animals and Plants. Received November 11, 1868. 1. Name.—Various parts of animals and plants contain a yellow crystal- lizable substance which has hitherto not been defined, and to which, from its prominent property, I assign the name of “ luteine.”’ 2. Oceurrence.—It occurs normally in the corpora lutea of the ovaries of mammals, in the serum of the blood, the cells of the adipose tissue, and the yellow fat of the secretion of the mammary gland, or butter; in mam- mals it occurs abnormally in ovarian tumours and cysts, and in serous effusions. It is a regular ingredient of the yelks of the eggs of oviparous animals. In the vegetable world it is observed in seeds, such as maize; in the husks and pulps of fruits, such as anatto; in roots, such as carrots ; in leaves, such as those of the coleus; and in the stamina and petals of a great variety of flowers. 3. Properties.—Luteine is easily soluble in alcohol, ether, and chloro- form, but is insoluble in water. It is soluble in albuminous liquids, such as the contents of ovarian cysts and the serum of the blood. All these solu- tions are yellow; but the chloroform solution when concentrated has an orange-red colour. 4, Spectrum.—The spectrum of these solutions is distinguished by great brilliancy of the red, yellow, and green part, and by three absorption-bands, which are situated in the blue, indigo, and violet part of the spectrum. The positions of the absorption-bands vary a little with the different solvents. Ovario-luteine in alcohol. Egg-luteine in ether. 5. Crystallization.—The crystals of luteine are apparently rhombic ees plates, as shown in the accompanying figure, of which two or more are 254 Dr, Thudichum on Luteine and the Spectra of {Jan. 28, always superposed in a curious manuer. Possibly these crystals may be rhombohedra imperfectly developed on four of their edges. They are microscopic, yellow when thin, orange to red when thick, and have no resemblance to any other known animal or vegetable substance. 6. Reactions.—Luteine combines with few substances, mercury-acetate being perhaps the only ordinary reagent by which it is immediately and completely precipitated, as a yellow deposit. Mercury-nitrate produces a yellow precipitate, which on standing becomes white. Nitric acid poured over the crystals produces a blue colour, which immediately passes into yellow. The blue is not produced when nitric acid is added to either alcohol, chloroform, or ether solution, bunt appears with the solution in acetic acid and disappears again rapidly. 7. Affinity for Fats.—In the corpora lutea luteine is deposited in gra- nules, which become the darker and larger the older the corpora grow. In the yelks of eggs it also exists in granules; and when extracted from any of these bodies it is always mixed with a considerable amount of an oily fat which contains cerebrine, and neutral fats, amongst them a peculiar fat containing phosphorus, like cerebrine. In butter after clarification it is found dissolved. 8. Affinity for Albumen.—On the other hand, luteine has great attrac- tion to albumen, and can only with difficulty be extracted from serum or the fluid of ovarian cysts. 9. Luteine in Vegetables.—In vegetable matters luteine is contained in such a form that a clear watery solution cannot easily be obtained. All vegetable matters, however, readily yield their luteine to aleohol, and form by proper treatment clear solutions. In maize, luteime is accompanied by fats which are somewhat similar to those of eggs. 10. Type of new Spectra.—The spectrum of luteine is the type of the spectra of a series of bodies which are probably chemically identical; but not all yellow vegetable, animal, or chemical products are identical with luteine. 11. New Spectra like that of Luteine.—The yeilow-coloured matters of the following plants present the spectrum of luteine, or one closely re- sembling it:—(1) Crocus or saffron (stamina); (2) Helianthus annuus (flower); the petals of the following plants—(3) Leontodon tarazxa- cum, (4) Leontodon (varietas’), (5) Gazania elegans, (6) Marigold common, (7) Hypericum oblongifolium, (8) Acacia leprosa, (9) Galphi- mia splendens, (10) Stigmatophyllum ciliatum, (11) Lankesteria elegans, (12) Allamanda neriifolia, (13) Colutea frutescens, (14) Tagetes lucida, — (15) Schkuhria atrovirens, (16) Diplotaxis tenuifolia, (17) Virgilia syl- vatica, (18) Ginothera grandifiora, (19) Verbascum phlomoides, (20) Tagetes pumila, (21) Helianthus macrophyllus, (22) Chrysopsis villosa, (23) Helenium autumnale, (24) Obeliscaria pinnata, (25) Heliopsis levis, (26) Linosyris vulgaris, (27) Berberis Darwinii, (28) Solidago serotina, (29) Ruta graveolens, (30) Melilotus elegans, (31) Medicago 1869.] Yellow Organic Substances. 255 elegans, (32) Allamanda Hendersonii; (33) the root of the common earrot, Daucus carota; (34) the seeds of Indian corn, Zea mays. The extracts of the derries of the following plants also give the luteine spec- trum :—(35) Anatto; (36) Asparagus; (37) Physalis Alkekengi (outer shell and inner berry); (38) Solanum duleamara; (39) Solanum capst- eastrum; (40) Cyphomandra betacea; (41) Crategus crus-galli; (42) Pyrus aria. 12. Uncertainty.—Iu several of these matters only two absorption-bands are with certainty distinguished. The third, clearly observable e.g. in the extract from the common marigold, requires further researches with more powerful light. 13. Yellow Bodies with one Band.—The yellow principles contained in yellow-wood or fustic, in the flowers of the Calceolaria of ornamental gardens, and in the yellow feces of sucking infants, show but one absorp- tion-band, in the blue. 14. Uranium Salts.—The yellow solutions of uranium salts exhibit two absorption-bands in the blue, which are very different from any of the above bands. 15. Spectra of Yellow Bodies with continued Absorption of Blue.-—A great number of yellow substances, amongst them some of the most im- portant dye-stuffs, show spectra with continued absorption of blue, indigo, and violet, without any bands. On dilution the absorption gradually recedes towards violet. To this class belong (1) Rhamnine, from French berries; (2) Luteoline, from weld; (3) Quercitrine, from extract of quer- citron or fluorme; (4) Turmeric; (5) Picric, and (6) Purrée, or Indian yellow; the orange-coloured solution of the petals of (7) Coreopsis lanceo- lata, (8) Helichrysum bracteatum; the light-yellow solution of (9) Viola lutea, (10) Acacia decurrens, (11) Helianthus macrophyllus (2), (12) Berberis Darwinii (°), (13) Gnaphalium foetidum. 16. Luteine not identical with Hematoidine or Cholopheine.—Luteine differs entirely from hematoidine on the one, and from cholopheeine on the other hand, and ought not, and after the elucidation of its spectral pheno- mena cannot, any longer be confounded with either of them. 17. Error of Stéideler and Holm.—The bodies described by Holm and Stadeler under the name of hematoidine are not hematoidine, but luteine. 18. Robin's Hematoidine is Cholopheine.—The bodies described by Va- lentiner, and by Robin, Riche, and Mercier, under the name of hematoidine, are not hematoidine, but cholophzine or bilirubine. 19. Hematoidine peculiar. — Hematoidine is a useful expression for certain microscopical crystals and amorphous bodies occurring in effused blood, the substance of which has not as yet been chemically isolated or defined. 20. Luteine leads to new morphological views.—The discovery of the identity of luteine from corpora lutea of mammals with that from yelks of eges will probably lead to a revision of the present doctrines regarding the 256 Mr. G. Gore on Hydrofluorte Acid. (Jan. 28, homologies of the various parts of the ova of mammals and the eggs of birds and lower animals. Chemically the corpus luteum is the homologue of the yelk, genetically it is nearly so; but its use and destiny are totally different. Note.—The foregoing researches are technical parts of inquiries carried on by the author at the Pathological Laboratory, St. Thomas’s Hospital, for the Medical Department of the Privy Council, in continuation of re- searches already published in the Ninth and Tenth Reports of the Medical Officer of the Privy Council. The special thanks of the author are due to Dr. Hooker, Director of the Royal Botanical Gardens, Kew, for the kindness and liberality with which he supplied, through Mr. Smith, the Curator, most of the botanical speci- mens examined in the course of this research. Il. “On Hydrofluoric Acid.” By G. Gorz, F.R.S. Received November 14, 1868. (Abstract.) A. Anhydrous Hydrofluorie Acid. This paper contains a full description of the leading physical and che- mical properties of anhydrous hydrofluoric acid, and also an account of various properties of pure aqueous hydrofluoricacid. The author obtained the anhydrous acid by heating dry double fluoride of hydrogen and potas- sium to redness in a suitable platinum apparatus (shown by a figure ac- companying the paper), and states the conditions under which it may be obtained in a state of purity. The composition and purity of the anhydrous acid are shown and care- fully verified by various methods of analysis, both of the double fluoride from which it was prepared and of the acid itself; and particulars are given of all the circumstances necessary to insure reliable and accurate results. Nearly all the operations of preparing, purifying, analyzing, and examining the properties of the acid were conducted in vessels of platinum, with lu- tings of paraffin, sulphur, and lampblack; articles of transparent and colourless fluor-spar were also employed in certain cases. Nearly all the manipulations with the acid were effected while the vessels containing it were immersed in a strong freezing-mixture of ice and crystallized chloride of calcium. The pure anhydrous acid is a highly dangerous substance, and requires © the most extreme degree of care in its manipulation. It is a perfectly co- lourless and transparent liquid at 60° Fahr., very thin and mobile, extremely volatile, and densely fuming in the air at ordinary temperatures, and ab- sorbs water very greedily from the atmosphere. It was perfectly retained in platinum bottles, the bottle having a flanged mouth with a platinum plate secured with clamp-screws, and a washer of paraffin. 1869. ] Mr. G. Gore on Hydrofluoric Acid. 257 A number of attempts were made, finally with success, to determine the molecular volume of the pure anhydrous acid in the gaseous state, the acid in these cases being prepared by heating pure anhydrous fluoride of silver with hydrogen ia a suitable platinum apparatus over mercury. Particulars are given of the apparatus employed and of the manipulation. The results - obtained show that one volume of hydrogen, in uniting with fluorine, pro- duces not simply one volume of gaseous product as it does when uniting with oxygen, but two volumes, as in the case of its union with chlorine. The gaseous acid transferred to glass vessels over mercury did not corrode the glass, or render it dim in the slightest degree during several weeks, pro- vided that moisture was entirely absent. The author concludes that the anhydrous acid he has cbtained is destitute of oxygen, not only from the various analyses and experiments already re- ferred to, but also, 1st, because the double fluoride from which it was pre- pared, when fused and electrolyzed with platinum electrodes, evolved abundance of inflammable gas at the cathode, but no gas at the anode, al- though oxides are by electrolysis decomposed before fluorides ; 2nd, because the electrolysis of the acid with platinum electrodes yiélded no odour of ozone, whereas the aqueous acid of various degrees of strength evolved that odour strongly ; and, 3rd, because the properties of the acid obtained from hydrogen and fluoride of silver agree with those of the acid obtained from the double salt. He considers also that the acid obtained from pure fluor-spar and monohydrated sulphuric acid heated together in a platinum retort is free from oxygen and water. The specific gravity of the anhydrous liquid acid was several times de- termined, both in a specific-gravity bottle of platinum, and also by means of a platinum float submerged and weighed in the acid. Concordant and reliable results were obtained; the specific gravity found was 0°9879 at 55° Fahr., that of distilled water being=1:000 at the same temperature. The anhydrous acid was much more volatile than sulphuric ether. Its boiling-point was carefully determined in a special apparatus of platinum, and was found to be 67° Fahr. Not the slightest sign of freezing occurred on cooling the acid to —30° Fahr. (= —34°'5 C.); and it is highly probable that its solidifymg temperature is a very great many degrees below this. Its vapour-tension at 60° Fahr. was also approximately determined, and was found to be =7°58 lbs. per square inch. On loosening the lid of a bottle of the acid at 60° Fahr., the acid vapour is expelled in a jet like steam from a boiler ; this, together with the low boiling-point, the extremely dangerous and corrosive nature of the acid, and its great affinity for water, illustrates the very great difficulty of manipulating with it and retaining it ina pure state. Nevertheless, by the contrivances described, and by placing the bottles in a cool cellar (never above a temperature of 60° Fahr.), the author has succeeded in keeping the liquid acid perfectly, without loss and unaltered, through the whole of the recent hot summer. The electrical relations of different metals &c. in the acid were found to 258 Mr. G. Gore on Hydrofluoric Acid. [Jan. 28, be as follows at 0° Fahr. :—zinc, tin, lead, cadmium, indium, magnesium, cobalt, aluminium, iron, nickel, bismuth, thallium, copper, iridium, silver, gas-carbon, gold, platinum, palladium. Numerous experiments were made of electrolyzing the anhydrous acid with anodes of gas-carbon, carbon of lignum-vitze and of many other kinds of wood, of palladium, platinum, and gold. The gas-carbon disintegrated rapidly ; all the kinds of charcoal flew to pieces quickly ; and the anodes of palladium, platinum, and gold were corroded without evolution of gas. The acid with a platinum anode conducted electricity much more readily than pure water; but with one of gold it scarcely conducted at all. These elec- trolytic experiments presented extreme difficulties, and were conducted in a platinum apparatus (shown by a figure) specially devised for the purpose. The particulars of the conditions and results obtained are de- scribed in the paper. Various mixtures of the anhydrous acid with monohydrated nitric acid, with sulphuric anhydride, aud with monohy- drated sulphuric acid were also electrolyzed by means of platinum anodes, the particulars and results of which are also described. To obtain an idea of the general chemical behaviour of the pure anhy- drous acid, numerous substances (generally anhydrous) were immersed in separate portions of the acid in platinum cups, kept at a low temperature (0° to —20° Fahr.). The acid had scarcely any effect upon any of the me- talloids or noble metals; and even the base metals in a state of fine powder did not cause any evolution of hydrogen. Sodium and potassium behaved much the same as with water. Nearly all the salts of the alkali and alka- line-earth metals produced strong chemical action. Various anhydrides (specified) dissolved freely. Strong aqueous hydrochloric acid produced active effervescence. The alkalies and alkaline earths united strongly with the acid. Peroxides gave no effect. Numerous oxides (specified) produced strong chemical action, some of them dissolving. Some nitrates were not chemically affected ; others (those of lead, barium, and potassium) were decomposed. Fluorides generally were unchanged ; but those of the alkali- metals and of thallium produced different degrees of chemical action, those of ammonium, rubidium, and potassium uniting powerfully. Nume- rous chlorides were also unaffected, whilst those of phosphorus (the solid one only), antimony (the perchloride), titanium, and of the alkaline-earth and alkali metals, were decomposed with strong action, and generally with effervescence. The chlorates of potassium and sodium were also decom- posed with evolution of chloric acid; the bromides of the alkaline-earth and alkali metals behaved like their chlorides. Bromate of potassium rapidly set free bromine. Numerous iodides were unaffected ; but those of the alkaline-earth and alkali metals were strongly decomposed, and iodine (in some cases only) set free. The anhydrous acid decomposed all carbonates with effervescence, and those of the alkaline-earth and alkali metals with violent action. Borates of the alkalies also produced very strong action. _Silico-fluorides of the alkali metals dissolved with effervescence. 1869. | Mr. G. Gore on Hydrofiuoric Acid. 259 All sulphides, except those of the alkaline-earth and alkali metals, exhi- bited no change; the latter evolved sulphuretted hydrogen violently. Bisulphite of sodium dissolved with effervescence. Sulphates were variously affected. The acid chromates of the alkali metals dissolved with violent action to blood-red liquids, with evolution of vapour of fluoride of chro- mium. Cyanide of potassium was violently decomposed, and hydrocyanic acid set free. Numerous organic bodies (specified) were also immersed in the acid; most of the solid ones were quickiy disintegrated. The acid mixed with pyroxylic spirit, ether, and alcohol, but not with benzole; with spirit of turpentine it exploded, and produced a blood-red liquid. Gutta percha, india-rubber, and nearly all the gums and resins were rapidly disintegrated and generally dissolved to red liquids.. Spermaceti, stearic acid, and myrtle wax were but little affected, and paraffin not at all. Sponge was also but little changed. Gun-cotton, silk, paper, cotton-wool, calico, gelatine, and parchment were instantly converted into glutinous: substances, and generally dissolved. The solution of gun-cotton yielded an inflammable film on evaporation to dryness. Pinewood instantly blackened. From the various physical and chemical properties of the anhydrous acid, the author concludes that it lies between hydrochloric acid and water, but is much more closely allied to the former than to the latter. It is more readily liquefied than hydrochloric acid, but less readily than steam; like hydrochloric acid it decomposes all carbonates ; like water it unites power- fully with sulphuric and phosphoric anhydrides, with great evolution of heat. The fluorides of the alkali metals unite violently with hydrofluoric acid, as the oxides of those metals unite with water; the hydrated fluorides of the alkali metals also, like the hydrated fixed alkalies, have a strongly alkaline reaction, and are capable of expelling ammonia from its salts. It may be further remarked that the atomic number of fluorine lies between that of oxygen and chlorine; and the atomic number of oxygen, added to that of fluorine, nearly equals that of chlorine. B. Aqueous Hydrofluoric Acid. Under the head of the aqueous acid the author enumerates the various impurities usually contained in the commercial acid, and describes the modes he employed to detect and estimate them, and to estimate the amount of HF in it. The process employed by him for obtaining the aqueous acid in a very high degree of purity from the commercial liquid, is also fully described. It consists essentially in passing an excess of sul- phuretted hydrogen through the acid, then neutralizing the sulphuric and hydrofiuosilicic acids present by carbonate of potassium, decanting the liquid after subsidence of the precipitate, removing the excess of sul- phuretted hydrogen by carbonate of silver, distilling the filtered liquid in a leaden retort with a condensing-tube of platinum, and, finally, rectifying. . 260 Mr. G. Gore on a momentary [Jan. 28, The effect of cold upon the aqueous acid was briefly examined, the result being that a comparatively small amount of hydrofluoric acid lowers the freezing-point of water very considerably. The chemico-electric series of metals &c. in acid of 10 per cent. and in that of 30 per cent. were determined. In the latter case it was as follows :—zinc, magnesium, aluminium, thallium, indium, cadmium, tin, lead, silicon, iron, nickel, cobalt, antimony, bismuth, mercury, silver, copper, arsenic, osmium, ruthenium, gas-carbon, platinum, rhodium, pal- ladium, tellurium, osmi-iridium, gold, iridium. Magnesium was remark- ably unacted upon in the aqueous acid. The chemico-electric relation of the aqueous acid to other acids with platinum was also determined. Various experiments of electrolysis of the aqueous acid of various degrees of strength were made with anodes of platinum. Ozone was evolved, and, with the stronger acid only, the anode was corroded at the same time. Mixtures of the aqueous acid with nitric, hydrochloric, sulphuric, selenious, and phosphoric acids were also electrolyzed with a platinum anode, and the results are described. III. “ On a momentary Molecular Change in Iron Wire.” By G. Gorz, F.R.S. Received November 14, 1868. Whilst making some experiments of heating a strained iron wire to red- ness by means of a current of voltaic electricity, I observed that, on discon- necting the battery and allowing the wire to cool, during the process of cooling the wire suddenly elongated, and then gradually shortened until it became quite cold. On attempting, some little time afterwards, to repeat this experiment, although a careful record of the conditions of the experiment had been kept, it was with some difficulty, and after numerous trials, that I succeeded in obtaining the same result. Having again obtained it, I next examined and determined the successful conditions of the experiment, and devised the following arrangement of apparatus. A A (fig. 1) is a wooden base 6] centimetres long and 15°5 centimetres wide. Band C are binding-screws ; they are provided with small brass mer- cury-cups fixed in the heads of the screws for attachment of the wires of a voltaic battery. Dis a binding-screw for holding fast the sliding wire hook E. F is a cylindrical binding-screw, fixed to the sliding wire G, which is held fast by the binding-screw B. H is the iron or other wire (or ribbon) to be heated: one end of this wire passes through the screw F and is tightly secured by it, whilst the other end is held fast by the cylin- drical binding-screw I; the binding-screw I has a small projecting bent piece of copper wire secured to it, which dips into a little shallow dish or cup of mercury, J; and the mercury in this cup is connected by a screw and strip of brass to the binding-screw C. K is a stretched band of vul- canized india-rubber, attached at one end to the hook of the wire E, and aS it Fr rar a eeremry, ae See TENE Sawa ie Fi x1 4 ae a (SSL RPA gonulbhiah Xe e/a mm a OTe Zag Ie 3 2 Tony eee eet ral he 4 fl é. boy Sn =o a “ee eS Fy. —it Labs a) - TA To ‘ Ms o Pe i a ay <= td > ~~, ~ = ~ ® Dp ~ 3 n> \S) ~~ S > ce) nv S ny rS —* — oe Bova own , 5 Ee Fd ene ee feck AA L —< —— 262 Mr. G. Gore on a momentary [Jan. 28, * at the other end to the hook L (see fig. 2). The cylindrical binding- screw I has a hook by which it is attached to the loop M (fig. 2). N is an axis suspended delicately upon centres, and carrying a very light index pointer O. The hook L and loop M are separate pieces of metal, and move freely upon an axis, P (fig. 2). The distance from the centre of the axis N to that of P is 12°72 millimetres (=0°5 inch), and to the top of the index pointer 25°45 centimetres (=10°0 inches) ; every movement hori- zontally, therefore, of the loop M is attended by a movement, twenty times the amount, of the top of the pointer. Q is a screw for supporting the axis N. I have found it convenient to put the zero-figure of the index towards the left-hand side of the index-plate. RK is a separate piece of wood fitting into arectangular hole in the base board ; it carries a graduated rule, 8, for measuring the length of the wire to be heated, and is easily removed, so that the wire may, if necessary, be heated by means of a row of Bunsen’s burners. The rule T is used when measuring the amount of strain. U is a vertical stud or pin of brass (of which there are two) for limiting the range of movement of the pointer O. In using this apparatus, a str aight wire or ribbon, H, of a suitable length and thickness was inserted, the index pointer brought to 0 by adjustment of the sliding-wire G, and a suitable amount of ssa (varying from less than two ounces to upwards of twenty) put upon the wire by adjusting the sliding hooked wire E. One pole of a voltaic battery, generally consisting of six Grove’s elements, was connected with the binding-screw C, and the other pole then inserted in the mercury-cup of B. As soon as the needle O attained a maximum or stationary amount of deflection, the battery-wire was suddenly removed from B, and the wire allowed to cool. The move- ment of the needle O was carefully watched both during its movement to the right hand and also during its return, to see if any irregularity of motion occurred. Wires of the following metals and alloys were employed :—palladium, platinum, gold, silver, copper, iron, lead, tin, cadmium, zinc, brass, german- silver, aluminium, and magnesium; metallic ribbon was also employed in certain cases. In these experiments the thickness and length of the conducting-wire or ribbon had to be carefully proportioned to the quantity and electromotive power of the current, so as to produce in the first experiments with each metal only a very moderate amount of heat ; thinner (and sometimes also shorter) wires were then successively used, so as ultimately to develope sufficient heat to make the metal closely approach its softenimg or fusion- point. ‘The battery employed consisted in each case of six Grove’s cells, each cell containing two zinc plates 32 inches wide, and a platinum plate 3 imches wide, moe immersed about 5 inches in their respective liquids. The amount of tension imparted by the elastic band required to be care- fully adjusted to the cohesive power of each metal; if the stretching power was too weak, the phenomenon sought for was not clearly deve- 1869. | Molecular Change in Iron Wire. : 268 ~ loped; and if too great, the wire was overstretched or broken when it approached the softening-point. The amount of strain imparted was ap- proximately measured by temporarily substituting the body of a small spring balance for the hooked wire F. The heated wire must be protected from currents of cold air. With wires of iron 0°65 millimetre thick (size “ No. 23”) and 21:5 centimetres long, strained to the extent of 10 ounces or more, and heated to full redness, the phenomenon was clearly developed. As an example, the needle of the instrument went with regularity to 18-5 of index-plate; the current was then stopped; the needle instantly retreated to 17°75, then as quickly advanced to 19°75, and then went slowly and regularly back, but not to zero. If the temperature of the wire was not sufficiently high, or the strain upon the wire not enough, the needle went directly back without ex- hibiting the momentary forward movement. The temperature and strain required to be sufficient to actually stretch the wire somewhat at the higher temperature. A higher temperature with a less degree of strain, or a greater degree of strain with a somewhat lower temperature, did not deve- lope the phenomenon. The wire was found to be permanently elongated on cooling. The amount of elongation of the wire during the momentary molecular change was usually about =+5 part of the length of the heated part of the wire ; but it varied in different experiments; it was greatest in amount when the maximum degrees of strain were applied. The mole- cular change evidently includes a diminution of cohesion at a particular temperature during the process of cooling ; and it is interesting to notice that at the same temperature during the heating-process no such loss of cohesion (nor any increase of cohesion) takes place ; a certain temperature and strain are therefore not alone sufficient to produce it; the condition of cooling must also be included. The phenomena which occur during cooling are not the exact converse of those which take place during heating. The phenomenon of elongation of iron wire during the process of cool- ing evidently lies within very narrow limits; it could only be obtained (with the particular battery employed) with wires about 21°5 centimetres (=8,4, inch) long, and about 0°65 millimetre (=Nos. 22 & 23 of or- dinary wire-gauge) thick, having a strain upon them of 10 ounces or upwards ; with a weaker battery the phenomenon could only be obtained by employing a shorter and thinner wire. The experiment may easily be verified in a simpler manner by stretching an iron wire about 1:0 millimetre diameter between two fixed supports, keeping it in a sufficient and proper degree of tension by means of an elastic band, then heating it to full redness by means of a row of Bunsen’s burners, and, as soon as it has stretched somewhat, suddenly cutting off the source of heat. In some experiments of this kind, with a row (42 centi- metres long) of 21 burners and a row (76 centimetres long) of 43 burners, and the wire attached to a needle with index-plate, as in the figure, con- spicuous effects were obtained ; but the momentary elongation was relatively 264 On a momentary Molecular Change in Iron Wire. (Jan. 28, much less (in one instance z+, of the length of the heated part) than when a battery was employed, apparently in consequence of the wire being less intensely heated. A large number of experiments were made with wires of palladium, pla- tinum, gold, silver, copper, lead, tin, cadmium, zinc, brass, german-silver, aluminium, and magnesium (wire and ribbon), diminishing the length and thickness of the wire in each case, and adjusting the tension until suitable temperature and strain were obtained ; but in no instance could a similar molecular change to that observed in iron be detected. Palladium and platinum wires of different lengths, thickness, and degrees of strain were examined at various temperatures, up to that of a white heat; but no irre- gularity of cohesion, except that of gradual softening at the higher tempera- tures, was observed; they instantly contracted with regular action on stopping the current. Several gold wires were similarly examined at different tem- peratures up to that of a full red heat; no irregularity occurred either during heating or cooling; but little tension (about 4 ounces) was applied, on account of the weak ssiagae of this metal. Wires of silver similarly examined would only bear a strain of about 2 ounces, and a temperature of feeble red heat visible in daylight; no irregularity of elongation or con- traction occurred during heating and cooling. By employing exactly the proper temperature and strain, a very interesting phenomenon was ob- served ; the wire melted distinctly on cts surface without fusing in its inte- ae although the surface was most exposed to the cooling influence of the ; this occurred without the wire breaking, as it would have done if its Sige: portion had melted; the phenomenon indicates the passage of the electricity by the surface of the wire in preference to passing by its inte- rior. Wires of copper expanded regularly until they became red-hot ; they then contracted slightly (notwithstanding the strain applied to them), probably in consequence of a cooling effect of increased radiation produced by the oxidized surface, as a similar effect occurred with brass and german- silver*. On stopping the current the wire contracted without manifest irregularity. Wires of lead and tin were difficult to examine by this method, on account of their extremely feeble cohesion and the low temperature at which they softened: wires about 1:63 millimetre diameter, 25:5 centi- metres long (with a strain upon them of about one ounce), were employed ; no irregularity was detected. Wires of cadmium from 1:255 millimetre to 1°525 millimetre thick, and 24-2 centimetres long (with a strain of two ounces), exhibited a slight irregularity of expansion at the lower tempera- tures ; they elongated, and also cooled, with extreme slowness, more slowly - than those of any other metal. Wives of zinc exhibited a slight irregu- larity of expansion, like those of cadmium ; the most suitable ones were about 25 centimetres long and 1-2 millimetre in diameter, with a strain of 10 ounces. Wires of brass and german-silver, when heated to redness, * 'This supposition does not agree with the results obtained with iron wire, which also oxidizes freely. 1869. | On the Development of Electric Currents, &c. 265 behaved like those of copper in expanding regularly until a maximum was attained, and then contracting slightly to a definite point whilst the battery remained connected ; on stopping the current they contracted without irre- gularity. When examined at lower temperatures, with a greater degree of strain, no irregularity was observed. Various wires of aluminium were examined ; the most suitable was one 0°88 millimetre thick, 20°4 centi- © metres long, with a strain of 12 ounces’; no irregularity was observed at any temperature below redness; aluminium expanded and cooled very slowly, but less so than cadmium. Various wires and ribbon of magnesium were also examined below a red heat, but no irregularity of cohesion, ex- cept that due to gradual softening by heat, was detected. All the metals examined exhibited gradual loss of cohesion at the higher temperatures if a suitable strain was applied to develope it. It is probable that if the fractions of time occupied by the needle in passing over each division of the index were noted, and the wire perfectly protected from currents of air, small irregularities of molecular or cohesive change might be detected by this method; cadmium and zinc offer a prospect of this kind. This molecular change would probably be found to exist in large masses of wrought iron as well as in the small specimens of wire which I have examined, and would come into operation in various cases where those masses are subjected to the conjoint influence of heat and strain, as in various engineering operations, the destruction of buildings by fire, and other cases. IV. “On the Development of Electric Currents by Magnetism and Heat.” By G. Gorz, F.R.S. Received November 14, 1868. I have devised the following apparatus for demonstrating a relation of current electricity to magnetism and heat. A A, fig. 3, is a wooden base, upon which is supported, by four brass clamps, two, B, B, on each side, a coil of wire, C ; the coil is 6 inches long, 13 inch external diameter, and 3 of an inch internal diameter, lined with a thin glass tube ; it consists of 18 layers, or about 3000 turns of insulated copper wire of 0°415 millim. diameter (or size No. 26 of ordinary wire- gauge); D is a permanent bar-magnet held in its place by the screws E, BH, and haying upon its poles two flat armatures of soft iron, F, I’, placed edgewise. Within the axis of the coil is a straight wire of soft iron, G, one end of which is held fast by the pillar-screw H, and the other by the cylindrical binding-screw I; the latter screw has a hook, to which is attached a vul- canized india-rubber band, J, which is stretched and held secure by the hooked brass rod K and the pillar-screw L. The screw H is surmounted by a small mercury cup for making connexions with one pole of a voltaic battery, the other pole of the battery being secured to the pillar-screw M, VOL. XVII. U 266 Mr. Gore on the Development of Electric Currents [Jan. 28, which is also surmounted by a small mercury cup, and is connected with the cylindrical binding-screw I by a copper wire with a middle flattened portion O to impart to it flexibility. The two ends of the fine wire coil are soldered to two small binding-screws at the back; those screws are but partly shown in the sketch, and are for the purpose of connexion with a suitable galvanometer. The armatures F, F are grooved on their upper edges, and the iron wire lies in these grooves in contact with them; and to prevent the electric current passing through the magnet, a small piece of paper or other thin non-conductor is inserted between the magnet and ~- one of the armatures. The battery employed consisted of six Grove’s ele- ments (arranged in one series), with the immersed portion of platinum plates about 5 inches by 3 inches ; it was sufficiently strong to heat an iron wire 1-03 millim. diameter and 20°5 centims. long to a low red heat. By making the contacts of the battery in unison with the movements of the galvanometer-needles, a swing of about 12 degrees of the needles each way was obtained. ‘The galvanometer was not a very sensitive one; it con tained 192 turns of wire. Similar results were obtained with a coil bait inches long and 13 inch diameter containing 16 layers, or about 3776 turns of wire of 0415 millim. diameter (or No. 26 of ordinary wire-gauge), and a permanent magnet 10 inches long. Less effects were obtained with a 6-inch coil consisting of 40 layers, or about 10,000 turns of wire 0°10 millim. diameter, also with several other coils. The maximum effect of 12 degrees each way with six Grove’s cells in one series was obtained when the wire became visibly red-hot, and this occurred with an iron wire 1°03 millim. diameter (or No. 19 of ordinary wire-gauge) ; but when employing ten such cells as a double series of five, the maximum effect was then obtained with an iron wire (size Nos. 17 and 18) 1°28 to 1°58 millim. diameter, the deflec- tion being 16 degrees each way. By employing a still thicker wire and a battery of greater heating-power still greater effects were obtained. The galvanometer was placed about 8 (and in some instances 12) feet distant from the coil. A reversal of the direction of the battery current did not reverse or perceptibly affect the current induced in the coil; but by reversing the poles of the magnet, the direction of the induced current was reversed. On disconnecting the battery, and thereby cooling the iron wire, a reversed direction of induced current was produced. By substituting a wire of pure nickel 24°5 centims. long and 2:1 millims. diameter, induced currents were obtained as with the iron, but they were more feeble. No induced current occurred by heating the iron wire if the magnet was absent; nor was any induced current obtained if the magnet was present and - wires of palladium, platinum, gold, silver, copper, brass, or german-silver were heated to redness instead of iron wire; nor with a rod of bismuth 3°63 millims. diameter enclosed in a glass tube and heated nearly to fusion ; it is evident, therefore, that the axial wire must be composed of a magnetic metal. No continuous current (or only a very feeble one) was produced in the Wig, " fi ; ; TON. vg ats 2 CONTENTS—(continued). | January 28, 1869. PAGE I. Researches conducted for the Medical Department of the Privy Council at the Pathological Laboratory of St. Thomas’s Hospital. By J. L. W. THupicoum, M.D... . 0 ee 5 eee ame A> cee _ II. On Hydrofiuoric Acid. By G. Goce F. R. g. ee ee 8 Re III. On a momentary Molecular Change in Iron Wire. By G. Gonz, F.R.S. . 260 IV. On the Development of Electric Currents by he and Heat. By ORR, BRB. ee See aie ay. Obituary Notices of Deceased Fellows : JULIUS PLUCKER... Me eee ices Leoy Meneieee POPP oe TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET. 7 pig iz 3 PROCEEDINGS OF aa 7 ee Nhs si THE ROYAL SOCIETY. VOL. XVII. No. 109. CONTENTS. February 4, 1869. PAGE I. On Fossil Teeth of Equines from Central and South America, referable to Equus conversidens, Equus tau, and Equus arcidens. By Professor 2 CT 1S a . 267 II. Compounds Isomeric with the ahi nhiaafiic Rehors: re Ty ansforasiiers of Ethylic Mustard-oil and Sulphocyanide of Ethyl. By A. W. Hor- meee en). M.D. LL.D. FERS.) 2... Ce . 269 III. On the Solar Protuberances. By M. Janssen. me a Lette to ese EMBO rs eT ee cee oe ee ek ge ee February 11, 1869. I. On the Structure and Development of the Skull of the Common Fowl (Gallus domesticus). By W. Kitcuen Parker, F.R.S. . . 2... . 297 If. Determinations of the Dip at some of the principal Observatories in Europe by the use of an instrument borrowed from the Kew Observatory. By Lieut. E~acin, Imperial Russian Navy . . . wily ie eO Ill. On a New Class of Organo-metallic Bodies aac Sodan: By J. ALFRED WANKLYN, Professor of Chemistry in the London Institution . 286 1¥. On the Temperature of the Human Body in Health. By Sypyery RincER, M.D. (Lond.), Protessor of Materia Medica in University College, London, and the late ANDREW Patnick StuarrT .. . . 287 Y. Preliminary Note of Researches on Gaseous Spectra in relation to ie Physical Constitution of the Sun. By Epwarp Franxxanp, F.R.S., eet NORMAN LOCKYER, FORA So ie re eae ane a BS February 18, 1869. I. On the Structure of Rubies, Sapphires, Diamonds, and some other Minerals. By H. C. Sorsy, F.R.S., and P.J. BUTLER . . . . . 291 Ii. Note on a Method of viewing the Solar Prominences Bieud an = Wolinas Pee rELIAM LIU GGING, WB Si clan seit oo occ ea Sire oe oe hs ee Oe For continuation of Contents see the 4th page of W: heer MPA UR 6h a Dees ney 1869.] Prof. Owen on Fossil Teeth of Equines. 267 coul by continuously heating the iron wire. In several experiments, by employing twelve similar Grove’s elements asa double series of six intensity, an iron wire 1°56 millim. diameter was made bright red-hot ; and by keeping the current continuous until the galvanometer-needles settled nearly at zero, and then suddenly disconnecting the battery, the needles remained nearly stationary during several seconds, and then went rapidly to about 10: this slow decline of the current during the first few seconds of cooling was probably connected with the ‘‘momentary molecular change of iron wire ”’ during cooling which I have described in the preceding paper. The irregularity of movement of the needles did not occur unless the wire was bright red-hot, a condition which was also necessary for obtaining the molecular change. The direction of the current induced by heating the iron wire was fouad by experiment to be the same as that which was produced by removing the magnet from the coil; therefore the heat acted simply by diminishing © the magnetism, and the results were in accordance with, and afford a further confirmation of, the general law, that wherever there is increasing or decreasing magnetism, there is a tendency to an electric current ma conductor at right angles to it. February 4, 1869. Dr. WILLIAM ALLEN MILLER, Treasurer and Vice-President, in the Chair. The following communications were read :— I. “On Fossil Teeth of Equines from Central and South America, referable to Hquus conversidens, Equus tau, and Equus arcidens.” By Professor Owrn, F.R.S. Received November 17, 1868. (Abstract.) The author, referring to his previous paper on the Equine fossil remains from the cavern of Bruniquel, finds, in the preliminary illustrations of the dental characters of existing species of the Horse-kind, the requisite and much-needed basis of comparison for the determination of other fossils of the Solidungulate group, and he devotes the present paper to the elucidation of those which have reached him from Central and South America. We commences by referring to the type-specimens of teeth, from two localities in South America, on which he founded the species EL. curvidens, describing it (in 1840) “as one coexisting with the Megatherium, Toxodon, &c. in that continent, and which had become extinct at a prehistoric period.’ He then proceeds to describe more complete evidences of the dentition of an allied extinct Horse discovered by Don Antonio del Castillo, mining engineer, in newer Tertiary deposits of the Valley of Mexico. Besides repeating the originally described characters of the curvature of VOL. XVII. % 268 Prof. Owen on Fossil Teeth of Equines. [Feb. 4, the grinder, with a certain resemblance of enamel-pattern to the grinding- surface of the Z. curvidens, they show a greater degree of curvature of the alveolar series of the upper jaw, with corresponding greater convergence of the right and left molar series toward the fore part of the palate, than in any previously described species of Hquus. Deciduous teeth of the Hquus conversidens from the same deposits of the Valley of Mexico are described. Having determined these corroborative and distinctive characters of aboriginal and now extinct American horses, the author remarks, ‘‘It is unlikely, seemg the avidity with which the Indians of the Pampas have seized and subjugated the stray descendants of the European horses introduced by the Spanish ‘Conquistadors’ of South America, and the able use the nomad natives make of the multitu- dinous progeny of those war-horses at the present day, that any such tameable Equine should have been killed off or extirpated by the ancestors of the South-American aborigines.” If, therefore, the fossil Equine teeth do belong, as the author deems that he has proved, to a species distinct from Equus cabailus, Linn., “the circumstances of their discovery, and the fact of the extinction of such (curvident and conversident) species of Horse would point to some other cause than that of man’s hostility to so useful an animal, and such doubt as to extinction by human means may then be extended to the contemporaries of the Yquus curvidens and EH. conversidens, viz. Megatherium, Mylodon, Toxodon, Nesodon, Macrauchenia, Glyptodon, Mastodon, &c.”’ The author next proceeds to describe fossil teeth from the upper and lower jaws, discovered by Don A. del Castillo in the same deposits of the Valley of Mexico, and referable to a third species of Hquus, viz. Equus tau, Ow. Finally the author proceeds to the description of some fossil upper molar teeth from Pampas deposit, in the bed of a brook falling into the ‘‘ Arroyo Negro’? near Paysandi, Monte Video, showing characters more decisively distinct from any other known species of Hquus than have hitherto been described. . The degree of curvature of the upper molar teeth exceeds that in Hguus eurvidens, and equals that in Torodon; and the specific name “‘ arcidens”’ is accordingly proposed for this aboriginal American species of Horse. It is compared with so much of the characters as have been given by Dr. Lund of his Lquus neogeus and £. principalis from Brazilian caverns ; and the differences from all other Equines which these species and the £. arcidens agree in presenting lead the author to view them as having, like the Hippotherium of Kaup, formed a generic group in the Mquide, for - which he proposes the name Hippidion. The fossil teeth of H. arcidens were found associated with remains of Megatherium and Glyptodon in the above-named locality ; the specimens were transmitted and presented to the British Museum (in 1867) by the Hon. W. G. Lettsom, Her Britannic Majesty’s Minister at Monte Video. This paper is illustrated by drawings of the specimens described. 1869.] On Ethylic Mustard-oil and Sulphocyanide of Ethyl. 269 II. “Compounds Isomeric with the Sulphocyanic Ethers.——III. Transformations of Ethylic Mustard-oil and Sulphocyanide of Ethyl.” By A. W. Hormann, Ph.D., M.D., LL.D., F.R.S. Received November 19, 1868. In the present paper I beg leaye to communicate to the Royal Society some experiments made for the purpose of testing the views which.I have lately* advanced respecting the constitution of the mustard-oils and the sulphocyanic ethers isomeric with them. These experiments were exclu- sively performed in the ethyl-series. Not only is ethylamine much more readily prepared than the methyl-base, but the elucidation of the meta- morphoses examined was not. unfrequently facilitated by the selection of compounds for the construction of which the material had simultaneously been taken from the monocarbon- and dicarbon-series. Action of Hydrogen in condicione nascendi upon Kthylic Mustard-oil. I have, in the first place, examined this reaction, because experiments performed by M. Oeser+ have already supplied some information on the behaviour of allylic mustard-oil under analogous conditions. On adding zine and hydrochloric acid to an alcoholic solution of ethylic mustard-oil an evolution of sulphuretted hydrogen becomes at once percep- tible ; it soon diminishes, but continues for several days. In the several stages of this process the gas evolved was examined for carbonic acid; but not a trace of this gas could be detected. As soon as the evolution of sul- phuretted hydrogen has ceased, the liquid is found to contain a large quantity of fine white needles; when submitted to distillation, it yields the same body, which, passing over with the vapour of water and alcohol, col- lects in the form of white crystals upon the water in the receiver. If the residue be now allowed to cool, an additional quantity of the crystalline compound is deposited. Analysis and examination of the properties of these crystals have identified them with the substance generated by the action of sulphuretted hydrogen upon methylic aldehydet, to which I assigned the formula CH,8, stating at the same time that a higher molecular weight might possibly be- found to belong to this sulphaldehyde of the methyl-series. On adding strong soda-lye to the liquid containing chloride of zinc, from which the crystals have been separated, until the oxide at first precipitated is redissolved, a strongly alkaline layer collects on the surface of the solu-. tion, which may be considerably augmented by the intervention of a small quantity of alechol. This layer was removed and separated from adhering soda by distillation. When the very volatile distillate was saturated with * Proceedings, vol. xvii. p. 67. tT Ann. Chem. Pharm. vol. cxxxiv. p. 7. < Proceedings of the Royal Society, vol. xvi. p. 156. Bay 270 Dr. Hofmann on Transformations of [Feb. 4, hydrochloric acid and mixed with perchloride of platinum, the well-known hexagonal tables of the ethylamine-platinum-salt were at once deposited. The mother-liquor was found to contain a second salt, much more soluble both in water and alcohol, which was precipitated by ether. By recrys- tallization it was obtained in magnificent orange-red needles, which on ana- lysis exhibited the composition of the platinum-salt of methyl-ethylamine. The interpretation of these observations presents no difficulty. There are obviously two parallel reactions to be distinguished. In the first place (and this is doubtless the principal reaction) there are two molecules of hy- drogen inserted at the place in which the two compounds of ethylic mus- tard-oil are joined together—this insertion giving rise to the formation, on the one hand, of ethylamine, the mother-compound of the mustard-oil, and on the other hand, of methylic sulphaldehyde, the hydrogen-derivative of bisulphide of carbon. ‘gs’ [N+ 2Hu= “tL N + CHS Or the substance, under the powerful ate of hydrogen, splits in an- other place ; three molecules of hydrogen penetrate into the fragment of the bisulphide, and the products of this secondary and subordinate trans- formation are methyl-ethylamine and sulphuretted hydrogen. ig ve Dae Ae LN 138 1— 10,0 Ne ee H Action of Hydrogen in condicione nascendi on Sulphocyanide of Ethyl. On treating the isomeric sulphocyanide of ethyl with zinc and hydro- chloric acid, sulphuretted hydrogen is also evolved; it contains, however, so abundant an admixture of mercaptan, that the brown spot of sulphide of lead appearing upon lead-paper held over the mouth of the flask in which the reaction takes place 1 is surrounded by a yellow ring of mercaptide of lead. In order to examine the gases evolved, they were passed in the first place through lime-water, then through hydrate of sodium, and lastly through acetate of lead and perchloride of mercury ; ultimately they were collected in a gas-holder. The lime-water remained clear; hence the gases did not contain carbonic acid; the liquid, however, was saturated with hydrocyanic acid. By the hydrate of sodium large quantities of sul- phuretted hydrogen and ethyl-mercaptan were fixed; the two metallic salts, lastly, retamed some ethylic mercaptan and ethylic sulphide. The gas collected in the gas-holder was transmitted once more through lime- water and sodic hydrate, and then passed over a layer of incandescent oxide of copper. ‘Together with water, large quantities of carbonic acid were thus produced, proving that the hydrogen contained a carbonated gas, which I do not hesitate to consider Sale although verification of this as- sumption, by transformation of the hydrocarbon into tetrachloride, has still to be adduced. 1869.] LEthylie Mustard-oil and Sulphocyanide of Ethyl. 271 On distilling the liquid, when the evolution of sulphuretted hydrogen has ceased, there are evolved, together with a small quantity of the latter gas, ethylic mercaptan, sulphide and, under certain conditions, even bisul- phide of ethyl, these several compounds being easily recognized by their special reactions. The residue, when heated with hydrate of sodium, disengages abundant quantities of ammonia, and also an appreciable amount of methylamine. If these varied results be taken into consideration, the action of nascent hydrogen upon sulphocyanide of ethyl would appear to be a very compli- cated process. ‘The principal transformation of the body is nevertheless extremely simple. Here, again, the point of junction of the two components of sulphocyanide of ethyl is the vulnerable part. A molecule of hydrogen entering at this point, between the sulphur and the carbon, the compound separates into hydrocyanic acid on the one hand and ethylic mercaptan on the other. Gn’ | S+HH=HNC+ Oats. All the other products belong to secondary reactions. In contact with hydrogen, hydrocyanic acid is converted into methylamine. CH, HN C+2HH= 4H N, H Sulphide of ethyl, ammonia, marsh-gas, and sulphuretted hydrogen may be looked upon as resulting from a further and deeper destruction of the molecule of sulphocyanide of ethyl under the influence of hydrogen. C,H C,H, a) Ton’ S| +8HE =¢'y | S+2H,N+2H, C+H, 8. Action of Hydrogen in condicione nascendi upon Allylic Mustard-oil. Accordmg to the experiments of M. Oeser already quoted, the mustard- oil par excellence, when submitted to nascent hydrogen, would appear to undergo a transformation different from that of its ethylic congener. M. Oeser represents the metamorphosis of the allyl-compound by the follow- ing equation :— “gg | N+2H,0=°F: | N+H,8+C0,, This equation, however, obviously represents no reduction process; the nascent hydrogen has no share in this reaction, which is simply accomplished under the influence of the elements of water. To clear up this anomaly, the experiments above described were repeated in the allyl-series. On treating mustard-oil with zinc and hydrochloric acid, an abundant evolution of sulphuretted hydrogen was observed, but (under the conditions, at all events, in which I repeatedly performed this experiment) the gas did not contain a trace of carbonic acid; on the other hand, large quantities of the sulphaidehyde of the methyl-series were inva- 272 Dr. Hofmann on Transformations of [Feb. 4, riably obtained. If the spirit which is employed in dissolving the mustard- oil to be reduced be dilute, a fine crystallization of the sulphaldehyde is frequently observed after the lapse of a few hours. Together with this compound allylamine is generated in large proportion. The principal reac- tion is thus seen to be exactly the same as with ethylic mustard-oil. C, H, CS The sulphuretted hydrogen would therefore likewise belong to a secondary reaction. Vainly, however, have I endeavoured to trace in the mother- liquor of the allylamine-platinum salt the existence of the platinum com- pound of a second base—of methyl-allylamine for instance ; though working on a rather large scale, I was unable to detect even a trace of such a com- pound. The origin of the sulphuretted hydrogen, however, could not be doubtful. In the gas evolved during the reaction, a large amount of a gaseous hydrocarbon (very probably marsh-gas) was present, as could be easily proved by burning the gas, after an appropriate purification, with oxide of copper. C,H CS pt) sal \ N+2H H= Oo 2 | N+CH,s. C, H, ‘| N+4HH= i } N+OH,+H,8. Action of Hydrogen in condicione nascendi upon Hydrosulphocyanie Acid. It would have been strange if in the course of these researches I had omitted to investigate the action of zine and hydrochloric acid upon sul- phocyanide of potassium. The result of this experiment could scarcely be doubtful—evolution of sulphuretted hydrogen in torrents, copious sepa- ration of sulphuretted methylic aldehyde, in the residue ammonia and me- thylamine. The reaction is not without interest, since the hydrosulpho- cyanic acid liberated by the hydrochloric acid exhibits the principal meta- morphosis both of mustard-oil and the isomeric sulphocyanide of ethyl. i | he | N4+2HH=H,N +OH,8, ch | S+HH =HON+H,S. Hydrocyanic acid, it is true, is not directly observed in this case; but we meet with its hydrogen-derivative, methylamine. Together with the behaviour of these bodies under the influence of redu- cing agents, I have studied the action of water and of acids upon the mus- tard-oils and the ethers isomeric with them. Action of Water and Hydrochloric Acid upon Ethylic Mustard-oil. When exposed in sealed tubes together with water to a temperature of 200° for eight or ten hours, ethylic mustard-oil splits up into ethylamine, carbonic acid, and sulphuretted hydrogen. The idea naturally suggests itself that two water-molecules act in succession. Under the influence of 1869.| Ethylic Mustard-oil and Sulphocyanide of Ethyl. 273 the first, ethylic mustard-oil. would yield ethylamine and sulphoxide of carbon. C,H, ©, H, We \N+H,0= | HY [| N+C80. The action of the second would transform the rather unstable sulphoxide of carbon into carbonic acid and sulphuretted hydrogen. CSO+H,0=C O,+H,8. ‘The decomposition remains essentially the same if, instead of water, hy- drochloric acid be employed. The reaction, however, is very considerably _ accelerated ; in fact an hour’s digestion at 100° is sufficient to split up the mustard-oil right off into ethylamine, carbonic acid, and sulphuretted hy- drogen. Action of Water and Hydrochloric Acid upon Sulphocyanide of Ethyl. Water, even at rather high temperatures, acts but very slowly upon sulpho- cyanide of ethyl. Even at 200°, after several days’ digestion, very appre- ciable quantities of the compound had remained unaltered. The reaction, as might have been expected, proceeds much more rapidly in the presence of concentrated hydrochloric acid. The ultimate products of transforma- tion are sulphuretted hydrogen, sulphide of ethyl, carbonic acid, and am- monia. Here, again, we have by no means to deal with direct products of decomposition. Probably the compound, with the cooperation of one mo- lecule of water, changes in the first place into ethyl-mercaptan and cyanic acid, CN Under the influence of a second molecule of water, cyanic acid yields am- monia and carbonic acid. CHNO+H,0=H,N+C0O.. Sulphide of ethyl and sulphuretted hydrogen, lastly, have to be looked upon as products of transformation of ethylic mercaptan. 2[ CaP } S| =O \ S+H,S. Action of Water and Hydrochloric Acid upon Allylic Mustard-oil. Whilst engaged with these researches, I have incidentally made also some experiments upon the mustard-oil par excellence. As might have been expected, when submitted to the action of water at a high tempera- ture, and more especially in the presence of hydrochloric acid, allylic mus- tard-oil splits up into allylamine, carbonic acid, and sulphuretted hydrogen, Cae} N+CO,+H, S, 5 2 Gy | St HO= Coa | S+CHNO. ©, H, a ae \N+2H,0= Simultaneously, however, another reaction takes place, which up to the present moment I have not yet been able to elucidate. Together with 274 Dr. Hofmann on Transformations of [Feb. 4 allylamine there is formed a second liquid base having a very high boiling- point, which yields an amorphous platinum-salt. It remains behind as an oily layer, not volatilizable with the vapour of water, when the product of the action of hydrochloric acid upon mustard-oil, for the purpose of puri- fying the allylamine, is distilled with scda. Action of Sulphuric Acid upon Ethylic Mustard-oil. Dilute sulphuric acid acts like water and hydrochloric acid. Highly characteristic, however, is the behaviour of ethylic mustard-oil towards concentrated sulphuric acid. The two liguids mix with considerable eyvo- lution of heat, and after a few moments a powerful disengagement of gas takes place, which, if the reaction be promoted by the application of heat, may be increased to explosive violence. ‘The gas evolved is inflammable, and burns with a blue fiame. It has a peculiar odour, essentially different from that of bisulphide of carbon, or of sulphuretted hydrogen; from the latter it differs, moreover, by its having no action upon lead-paper. ‘These are the characteristics of sulphoxide of carbon, lately discovered by vonThan, The residue contains sulphate of ethylamine. CEE C, O, CS bls In contact with water, more especially in the presence of an alkali, sulphoxide of carbon is converted into carbonic acid and sulphuretted hy- drogen. Treatment of ethylic mustard-oil with concentrated sulphuric acid thus enables us to arrest halfway the transformation which is accom- plished under the influence of water. \N+H,0= \wicso. Action of Sulphuric Acid upon Sulphocyanide of Ethyl. Dilute sulphuric acid acts but slowly upon sulphocyanide of ethyl ; con- centrated acid, on the other hand, attacks the compound with great energy, powerful evolution of heat and disengagement of carbonic and sulphurous acids taking place. On distilling the liquid after addition of water, sulphu- retted ethereal products are volatilized; the deep-brown residue, when treated with lime, yields abundance of ammonia. In the presence of these observa- tions, it appeared very probable that the action of sulphuric acid resembled that of water and of hydrochloric acid, and that in this case likewise the ethyl- group was eliminated in combination with sulphur. Interesting experiments on the action of sulphuric acid upon sulpho- cyanide of ethyl, lately communicated to the Chemical Society of Berlin* _ by Messrs. Schmitt and Glutz, have indeed verified this assumption ; but these experiments have proved, moreover, that the reaction, exactly as in the case of the transformation of ethylic mustard-oil, is capable of stopping at an intermediate stage, inasmuch as the above-named chemists have suc- ceeded in isolating from the products of the reaction a compound isomeric * Sitzungsberichte der chemischen Gesellschaft, 1868, S. 182, 1869.] Ethylie Mustard-oil and Sulphocyanide of Ethyl. 275 with xanthic ether. Accordingly the metamorphosis of sulphocyanide of ethyl under the influence of sulphuric acid would appear to be accom- plished in the following two phases :— 2 Ents) ‘s 3H, 0=¢' 4 | C8, 0+4+2H,N+CO,, GN C,H C, H, C, H, ca aS 0+, 0=¢'4y" sbs+e OL bMS. It is true Messrs. Schmitt and Glutz, when submitting their ether to the action of water, obtained mercaptan, whilst, according to my ob- servations, the products of decomposition of sulphocyanide of ethyl with hydrochloric acid are sulphide of ethyl and hydrosulphuric acid. But since two molecules of mercaptan contain the elements of one molecule of sulphide of ethyl and one molecule of sulphuretted hydrogen, the final products of decomposition of sulphocyanide of ethyl by water and by hydrochloric and sulphuric acids are virtually the same. Action of Sulphuric Acid upon Allylic Mustard-oil. Mustard-oil par excellence, when treated with sulphuric acid, as might have been expected, exactly imitates the behaviour of the ethyl-compound. Sulphoxide of carbon is evolved with effervescence ; the residue contains sulphate of allylamine. ©, Hi. ef N+H,0= N+CSO. Orel ‘| “HH, The reaction proceeds with the utmost regularity and precision. The liquid scarcely becomes coloured; mixed with water and distilled with hydrate of sodium, it yields abundance of perfectly pure allylamine. It would be difficult te imagine a more elegant and expeditious process for preparing this interesting base in a state of perfect purity. Allylamine thus obtained was identified by the analysis of the platinum-salts, the preparation of the terribly smelling allyl-formonitril, which I shall describe in another paper, and, lastly, by its retransformation into mustard-oil, according to the method described in my last paper*. Also phenylic and tolylic mustard-oils exhibit an analogous behaviour with sulphuric acid ; in these cases likewise sulphoxide of carbon is evolved ; the base, however, does not remain as sulphate, but in the form of an amine-sulphate in the residue. ie N+ nyse" =! N,S0,+C80. Even phenyl-sulphocarbamide, as well as its homologues and analogues, is changed in this sense. * Proceedings of the Royal Society, vol. xvii. p. 67. 276 M. Janssen on the Solar Protuberances. [Feb. 4, (C,H,), CS H, In the presence of an excess of sulphuric acid, the water-molecule eli- minated is without influence upon sulphoxide of carbon. [x.42H80,=2[° TN 80, | +H,0+CSO, ie 2 Action of Nitric Acid upon Hthylic Mustard-oil. I have still to say a few words respecting the behaviour of ethylic mustard-oil with nitric acid, although the experience acquired in the several experiments I have described could not possibly leave any doubt on the nature of this reaction. Here, again, the ethyl-group separates, united with nitrogen, in the form of ethylamine, from the molecule, while the carbon and sulphur of the group C S are burnt and eliminated in the form of carbonie and sulphuric acids. The same deportment is exhi- bited by the homologues of ethylic mustard-oil, and also by the allyl- compound. The products which are generated by the action of nitric acid upon sulphocyanide of ethyl and its homologues are known. According to the experiments of Muspratt, sulphocyanide of ethyl yields with nitric acid ethyl-sulphurous acid, C7 ie H Accordingly there is also in this case elimination of the ethyl-group, in the form of a sulphur-compound. In conclusion it may be stated that I have examined the action of several other chemical agents, and more especially of the alkali-metals and their hydrates, on the two classes of isomeric compounds. Most of the experiments, however, which I have made in this direction are not yet completed, and I will here only briefly allude to the elegant transformation which sulphocyanide of ethyl suffers in contact with metailic sodium. A powerful reaction ensues, cyanide of sodium and sulphide of ethyl being formed. } so, ol ant s | +NaNa=? NaCN+o°y } S, It affords me great pleasure to mention the energy and intelligence with which Dr. Bulk has assisted me during the performance of the experi- ments described in this paper. My best thanks are due to him. IIT. ‘On the Solar Protuberances.” By M.Janssen. Ina Letter _ to Warren De ta Ruz, F.R.S. Communicated by Mr. Dr 1a Ruz. Received February 2, 1869. | «Je voulais vous écrire depuis longtemps pour vous faire part de mes travaux et vous remercier des bonnes et puissantes introductions que je vous dois. J’attendais que j’eusse quelque chose de complet a4 vous pré- senter, et j’al €té ainsi entrainé peu a peu. 1869.] On the Skull of Gallus domesticus. 27% *« Vous connaissez maintenant la méthode que j’ai proposé pour l'étude des protubérances, et dont Mr. Norman Lockyer avait eu Vidée, m’é- crit-on, depuis deux années. J’ignorais cela, et c’est une circonstance qui a été favorable 4 Mr. Lockyer; car si j’avais su qu’on travaillait sur ce sujet, naturellement j’aurais, en citant Pidée émise, fait connaitre immé- diatement par le télégraphe les résultats que j’obtenais dans Inde. Mais je ne regrette pas que Mr. Lockyer soit parvenu séparément a la confirma- tion de ses idées. Je trouve qu’il le méritait. Nous restons aussi indé- pendants l'un de l’autre. « Je dois vous dire que je viens de découvrir que les protubérances se rattachent au soleil par une atmosphére dont ’hydrogéne forme la base, au moins générale, et qui enveloppe la photosphére. Cette atmosphére est basse, & niveau fort inégal et tourmenté ; souvent elle ne dépasse pas les saillies de la photosphére. Les protubérances ne paraissent étre que des portions soulevées, projetées, détachées de cette enveloppe. J’étudie aussi les taches, sujet difficile, mais qui promet d’importantes notions sur la constitution du soleil. “ J’aurai Vhonneur, a Vissue de ces études, denvoyer un mémoire A votre Société Royale, comme hommage rendu a sa grande et juste célé- brité, et aussi comme témoignage de reconnaissance des bonnes réceptions que j'ai eues dans |’ Inde et chez vous toutes les fois que j’y vais. “Mais, en attendant, je vous prie de vouloir bien lui communiquer les résultats dont je vous fais part ici. ‘“‘ Je suis, en ce moment, 4 Simla, résidence d’été du Gouverneur, ot jai un beau ciel et 8000 de vos pieds au-dessous de moi. Je profite de ces heureuses conditions pour aborder ici toutes sortes d’ études. *‘ Je serai encore dans le Bengale en Mars. J’aurai donc le temps de recevoir une lettre de vous, ce qui me ferait un bien grand plaisir. Je n’ai ici aucune nouvelle scientifique d’ Angleterre, et bien peu de France.” February 11, 1869. Dr. W. B. CARPENTER, Vice-President, in the Chair. The following communications were read :— I. “On the Structure and Development of the Skull of the Com- mon Fowl (Gallus domesticus)’ By W. Kircuen Parker, F.R.S. Received November 25, 1868. (Abstract. ) In a former paper (Phil. Trans. 1866, vol. clvi. part 1, pp. 113-183, plates 7-15) I described the structure and development of the skull in the Ostrich tribe, and the structure of the adult skull of the Tinamou—a bird which connects the Fowls with the Ostriches, but which has an essentially struthious skull. 278 Mr.W.K. Parker on the Structure and Development of [Feb. 11, That paper was given as the first of a proposed series, the subsequent communications to be more special (treating of one species at a time) and _ earrying the study of the development of the cranium and face to much earlier stages than was practicable in the case of the struthious birds. - Several years ago Professor Huxley strongly advised me to concentrate my attention for some considerable time on the morphology of the skull of the Common Fowl ; that excellent advice was at length taken, and the paper now offered is the result. A full examination of the earlier conditions of the chick’s skull has cost me much anxious labour; but my supply of embryonic birds (through the kindness of friends)* was very copious, and in time the structure of the early conditions of the skull became manifest to me. The earliest modifications undergone by the embryonic head are not given in this paper: they are already well known to embryclogists; and my purpose is not to describe the general development of the embryo, but merely the skeletal parts of the head. These parts are fairly differentiated from the other tissues on the fourth day of incubation, when the head of the chick is a quarter of an inch (3 lines) in length; this in my paper is termed the “first stage.” The next stage is that of the chick with a head from 4 to 5 lines in length, the third 8 to 9 lines, and so on. The ripe chick characterizes the ‘fifth stage ;? and then I have worked out the skull of the chicken when three weeks, two months, three months, and from six to nine months old, the skull of the aged Fowl forming the “last stage.” During all this time (from their first appearance to their highly consoli- dated condition in old age) the skeletal parts are undergoing continual change, obliteration of almost all traces of the composite condition of the early skull being the result—except where there is a hinge, for there the parts retain perfect mobility. — Here it may be remarked that although the Fowl is only an approach to what may be called a typical Bird, yet its skull presents a much greater degree of coalescence of primary centres than might have been expected from a type which is removed so few steps from the semistruthious Tina- mou, abird which retains so many of its cranial sutures. The multiplicity of parts in the Bird’s skull at certain stages very accu- rately represents what is persistent in the Fish, in the Reptile, and to some degree in certain Mammals ; but the skull at first is as simple as that of a Lamprey or a Shark, and, in the Bird above all other Vertebrates, reverts in adult age to its primordial simplicity—all, or nearly all, its metamorphic ~ changes having vanished and left no trace behind them. Although in this memoir I have no business with the Fish, yet all along I have worked at the Fish equally with the Bird, the lower type being taken as a guide through the intricacies of the higher; and here the Car- * Dr. Murie is especially to be thanked for his most painstaking kindness in this respect. 1869. | the Skull of Gallus domesticus. 279 tilaginous and the Osseous Fishes are never fairly out of sight. ‘The Rep- tile, and especially the Lizard, has been less helpful to me, on account of its great specialization. On the fourth day of incubation the cranial part of the notochord is two- thirds the length of the primordial skull, but it does not quite reach the pituitary body ; it lies therefore entirely in the occipito-otic region. The ~ fore part of the skull-base extends horizontally very little in front of the pituitary space; this arises from the fact that the ‘“ mesocephalic flexure ”’ has turned the “horns of the trabecule ”’ under the head. Thus at this stage the nasal, oral, and postoral clefts are all seen on the under surface of the head and neck of the chick. At this time the facial arches have begun to chondrify ; but only the quadrate, the Meckelian rod, and the lower thyro-hyal are really cartilaginous; the other parts are merely tracts of thickened blastema or indifferent tissue. In the second stage an orbito-nasal septum has been formed; the “ horns of the trabeculze’’ have become the ‘nasal ale,” and an azygous bud of cartilage has grown downwards between them; this is the “ prenasal’’ or snout cartilage; it is the azs of the intermaxillary region. At the com- mencement of this second stage the primordial skull stands on the same morphological level as that of the ripe embryo of the Sea-turtle ; at the end of this stage it has become struthious; and now parosteal tracts (the an- gular, surangular, dentary, &c.) appear round the mandibular rod. In this abstract I shall not trace the changes of the skull any further, but conclude with a few remarks on the nomenclature of certain splints, and as to the nature of the great basicranial bones. Some years ago I found that certain birds (for instance the Emeu) pos- sessed an additional maxillary bone on each side; knowing that the so- called ‘‘turbinal”’ of the Lizard and Snake was one of the maxillary series, I set myself to find the homologies of these splints. Renaming the rep- tilian bones ‘“‘ preevomers,” on account of their relation to the vomer, and supposing the feeble maxillaries of the Bird to represent them, I considered that the true maxillaries were to be found in those newly found cheek- bones of the Emeu and some other birds. After discussion with Professor Huxley I have determined to drop the term “ preevomer,” and to call the supposed turbinal of the Lizard ‘septo- maxillary,”’ and the additional bone in the Bird’s face “‘ postmaxillary.”’ In many Birds, but not in the Fowl, the “ septo-maxillary ”’ is largely represented—not, however, as a distinct osseous piece, but as an outgrowth of the true maxillary. With regard to the basicranial bones, I have now satisfied myself that the, “‘parasphenoid”’ of the Osseous Fish and the Batrachian reappears in the Bird as three osseous centres—all true ‘‘ parostoses,”’ as in the single _ piece of the lower types; these three pieces are, the “rostrum ”’ of the basi- sphenoid and the two ‘‘ basitemporals.”’ : These three centres rapidly coalesce to form one piece, the exact counter- 280 Lieut. Elagin’s Determinations of the Dip. [Feb. 11, part of the Ichthyic and Batrachian bone; but just as this coalescence begins, ossification proceeds inwards from these ‘‘ parostoses,” and affects the overlying cartilage, the cartilage of the basisphenoidal region having no other osseous nuclei. This process of the extension inwards of ossification from a splint-bone to a cartilaginous rod or plate. I have already called ** osseous grafting ”’*. In my former paper the basisphenoidal “rostrum” and ‘‘ basitempo- rals’? were classed with the endoskeletal bones; they will in the present paper be placed in the parosteal category, in accordance with their primor- dial condition. By the careful following out of these and numerous other details I have corrected and added to my previous knowledge of the early morphological conditions of the Bird’s cranium, and at the same time, I trust, have con- tributed to an enlarged and more accurate conception of the history and meaning of the Vertebrate skull in general. II. “Determinations of the Dip at some of the principal Obser- vatories in Europe by the use of an instrument borrowed from Kew Observatory.” By Lieut. Etaern, Imperial Russian Navy. Communicated by Batrour Stewart, LL.D. Received February 2, 1869. Before I give a short account of the observations and the results de- duced from them, I beg to express in the first place my best thanks to Dr. Balfour Stewart, Director of the Kew Observatory, who, having heard of my desire to take the dip at different places, was so kind as to lend me an instrument from the Kew Observatory,—also to James Glaisher, Esq., F.R.S., &c., who furnished me with a tripod-stand, which I found to be of great use to me on some Stations. I may also remark that, having other duties to perform in obedience to instructions from the Russian Government, I could only devote a portion of my time to the observations of dip. The instrument I had from Kew Observatory was one of Barrow’s Dip- Circles, furnished with two 34-inch needles in the form generally used at the Observatory. The Dip-Circle used had been in use for some time at the Kew Observatory, until, it having been ascertained that one of its needles was somewhat deteriorated, it was replaced with that now in use. Before I left Kew Observatory I was aware that one of the needles was not as good as might be desired ; but as Mr. Stewart bad no other circle’ suitable for my purpose, I considered it desirable to take this circle. The observations were made according to the instructions of Lieut.- General Sabine, given in the ‘ Admiralty Manual of Scientifie Enquiry.’ The following Table I. shows the results of the observations with the circle from Kew ; in it the name of station and the date of observation are * See memoir “ On the Shoulder-girdle and Sternum,” Ray Soc. 1868, p. 10. 1869.] Lieut. Elagin’s Determinations of the Dip. 281 mentioned in the first column; in the second column is noted the particular needle used, and whether in the first series of observations the marked end r “N. Pole” was dipping, in which case it has been indicated by the 3° word “ direct ; first, it is indicated by. the word ‘“‘ reversed.” end, each of the two results is that formed from the mean of four sets of observations ; pole, and in the other it is a south pole. columns explain themselves. 1868. Kew Observatory (Magnetic House). h ue Royal Observatory, Green- wich (Magnetic Offices). August eee tenes eeereeese eeetetees eee teeees eect eeoes Seeeeeeee ee reeoess eeeeeeeces Peeeercee seeeceoee eeeccesee weeteenes fee eeeeee eee estes eee seeeee eeesecens Norwich (Mr. Firth’s gar- den, St. Giles Street). August 18 20 eeeeennae = ae SO) atin aceds fs BAD kal aes ss AEN OS wea ora . 2 aA eee (Mr. Gibson’s garden, Bethel Street). August 24 23:0 2 24 23:0 A, reversed. A, direct. b) A, reversed. A, direct. A, direct. 7 iP) A, direct. 7 A, direct. ep] A, direct. direct. A, TABLE L. Marked end. N. Pole. 4-69) 67 47 55 68 O 49 5d- OT: 32. 50 68 20-50) 68 23°19 68 23:12 68 0: in the case when the opposite or “S. Pole”’ was dipping Under the head of marked S. Pole. 51-30) 68 44-38] 67 res 88) 68 47°77| 67 ThE 7 52-06) 67 52°22! 67 49°12) 67 "25 55: 44: 10 70 "45 ‘00 38 12 19 68 9:37 15:50} 68 Means of the two results. (ep) (90) H> Oo LO ©9 E+ Cox WNWONWa® SOCAN On 67 Or.Ot Gy Or Or DA SW AIHA AD HH OS 68 68 67 68 67 57-84 67 67 67 5 SmMoOwwm-~AWwWd M109 w OUST GI HB G9 00 HO OS aT Or 68 in one of these two results the marked end is made a north The headings of the remaining Means of | Means of separate both Needles. | Needles. 68 2°55 68 3:87 } 68 5:20 | ei 58°25 | \ | | | +67 58:88 | jor 59-51 ) fe 16°93 | 4 68 17:94 } 68 18-95 68 16:28 63 1921 | | 68 1786 [Feb. 11, 282 Lieut. Hlagin’s Determinations of the Dip. TABLE I. (continued). ; Marked end. {Means of} Means of | Means of Station and Date. Needle. | ———— the two | separate both N. Pole. | 8. pole. | results. | Needles. | Needles. 1868. | Brussels Observatory (Magnetic House). dah! i Ova | August) 63023 5 A, direct. | 67 15-22|68 5912/67 7171) — “ September 2 O......... & 67 10°55} 66 5842/67 4:48) $67 5-67 ; AEN Tiere a 67 6°70/67 4:00)67 5:35 2 : Th yee ae A, direct. |67 510/67 445167 4°75 p67 677 : LORS i a bene : 67 1810/67 4-90] 67 11-50 ie 7-37 |) ; Pye ei i : 67 1400/67 567/67 9-83) ;° zo AO OC aie: “) 67 590/67 560167 5°75 | Utrecht Meteorological Ob- servatory (Magnetic House). September 9-0 | ......... A, direct. | 67 oe 67 29-0 67 39°6 67 406 . LO RO erase tans » p24 30°5 41°5 67 43 5 Oe eee menees A, direct. |67 49°38 | 67 38°8 |67 44:3 67 46-0 ‘3 _ S428) aide : 49°38. | 4040 | AiG e ieee Vienna (Theresianum Gar- | den, Magnetic House). Septemberal QO eee A, direct. |63 42°7 |63 248 | 63 33°75 3 OA Reon artes AGA 29:2 38:15} +63 36:2 93 21 OC Se yr) 44-0) 29°7 36°80 63 33-8 ¥ 1G re Ue case suc A, direct. |63 443 |63 40:5 | 63 42:40 y a Lees ane cen: : 43°3 41:05) 42-18) +63 41-40 :; aL Teese A 42°3 36°80} 39°60 ~ Munich Observatory (Magnetic House). ~ September 29 22°5 ......... A, direct. | 64 11-7 |63 539/64 28 [1 6, 96 Ne 30/13: Wve. . 1-3) 50:1 5-0 i = is a QO 3 en eee A, direct. |64 13-0 |64 11-0 | 64 12:0 G4 0% “p NS): UD 5 oes see Hf 14-9 6:9 10°9 | +64 11:5 i SOMO Caveats be ae 12:2 Ae UOTE Paris Observatory (in the garden close to the Magnetic House). October 14 22:5 .........| A, direct. |65 55°7 |65 36:7 |65 46:2 ;; UG 23 Dien: 54:6 39'8 47-2 | +65 484 |) 5 PACS ile 0 Ree aaa 5 2:2 Al-7 51:95 65 49-85 Sn SRO | Se Rance A, direct. |65 55:1 |65 45:2 | 65 50-20 ' Oe “6 G2 SsO heacesae 5 53°4 48-2 50°80} +65 51:3 | 5 45 PAV) AOE Rae gd 5 56°95) 48°55 52°75 Royal Observatory, Green- wich (Magnetic Offices). Mecember aoa a ieee: A, direct. | 68 11:0 | 67 50:0 |67 05 67 58-7 : ES NR » .|68 35 | 67 50-0 | 67 568 Pes ie 3 8 Se ER A, direct. | 68 10-9 67 58:0 93 Tee eigen a ine rp 68 1-1 | 67 54-4 167 572) 67 57-2 J At the Royal Observatory, Greenwich, I took more observations with one needle than the other ; and the reason for that was, I found that this needle, A,, gave two distinctly different positions: for instance, at times 1869. | Lieut. Elagin’s Determinations of the Dip. 283 dips were found which differed from those obtained at ether times about seven minutes, whilst the other needle, A,, gave more uniform and satis- factory results; and this is also the reason I preferred to take the sepa- rate means for each needle, and then means of both needles, and to give to them equal weights, notwithstanding the number of observations is greater in one case than the other. The cause of needle A, giving dif- ferent positions must be most probably in the axis of the needle, not in the agate plates ; otherwise both needles would indicate the same difference. Having given the results of my observations, I think it desirable to state the precautions I took to obtain the best results. First of all, whilst at the Royal Observatory, Greenwich, where I was for several months study- ing the several instruments in the magnetic department, through the kind- ness of the Astronomer Royal and Mr. Glaisher, I had made myself well acquainted with the necessary care in those observations ; besides, I several times visited the Kew Observatory, through the kindness of Dr. Balfour Stewart, and took some observations of dip. At all times my first efforts were directed to have a firm support; next, to accurately levelling the instrument; third, to see that the agate plates were clean, that the axis of the needle was also clean and tested by the use of cork, that the needles were free from dust and damp, their ends being passed in and out of cork, and their surfaces wiped with wash-leather ; and in damp weather increased attention was paid to everything; but, as a rule, observations were not made at such times; care was also had in determining the magnetic meridian corresponding, and in all cases several readings were taken in every position. The results of observations of dip with local imstruments at different places were as follows :— Kew Observatory, monthly observations of dip with an instrument No. 33 Circle, of the same pattern I had made by Barrow; the length of the needle is about 33 inches. To compare No. 33 Circle with the Circle bor- rowed from Kew, I made simultaneous observations; the mean from six observations with two needles gave for No. 33 Circle=68° 2':19, and for the Circle I had from Kew 68° 3’°8, this result being 1'°6 larger. Royal Observatory, Greenwich.—Observations of dip are made frequently with Mr. Airy’s dip instrument, described in the yearly volumes of ob- servations at the Royal Observatory. Six needles of three different lengths are observed on the same instrument; the results derived from each separate needle seldom differ more than five minutes in the year. I took from the Royal Observatory observations the mean of the determined dip for the period from 1st July to 30th September, which was=67° 56°15, derived from twenty-seven observations, and nearly corresponds to the time of my observations. The dip obtained from my observations with Kew Circle was =67° 58'°88, being 2'*73 larger. ; Brussels Observatory.—The observations of dip were made with an instrument of old English construction, which was made in the year 1828, wor, XVIt. ¥ 284: Lieut. Elagin’s Determinations of the Dip. [Feb. 11, by the English makers Troughton and Simms; two needles about 8 inches long are observed, and the observations are made in the usual manner, in the magnetic meridian. The dip is observed at the beginning of each year, in the month of March or April; thus for the year 1868 there was one observation made with two needles the 30th of March, and the dip obtained was 67° 11'"1. The 5th of September Professor Quetelet’s son, according to my wish, was so kind as to observe the dip, and obtained almost the same result (that is, 67° 11'°0), whilst from observations with the Kew Circle I obtained the dip =67° 6°77, being 4'-2 smaller. Utrecht Meteorological Department.—The observations were made with an instrument not differing much from instruments of this class formerly used in England. It was constructed by Olland, a maker at Utrecht; the dip is observed every fortnight, in the middle and at the end of each month, with two needles about 8 inches in length. The results of the separate needles are very close to one another, and the dip is generally observed about 9 o’clock in the morning. Simultaneous observations were made by Mr. H. Welers Bethink and myself, each observing his own instrument. The dips obtained are as follows :— With the Observatory instrument.... 67° 47:7 Wath the Kew Cirele. 2225 2 7.5 28 67° 43'°3, being 4°4 less. Vienna Meteorological Department.—The Dip Circle was made by Rep- sold, and a description of it is given in the ‘Magnetische und meteorologische Beobachtungen zu Prag bei Karl Kreil, sechster Jahrgang, vom Januar bis 31. December 1845.’ The instrument is provided with eight needles, whose lengths are about 9 inches each; the axis of the needle is perforated, and can be turned round the centre of the needle through a definite angle ; each dip is deduced from eight separate sets of observations, by turning each time the axis of the needle through an angle of about 45°. The sepa- rate results derived in this way differ sometimes about 1° from each other, and the means for separate needles differ in some cases about 20’; so that the determinations of dip with this instrument are very uncertain, whilst the labour to obtain a pretty good result is very great; at the same timea single determination with one of the Barrow’s Circles gives a result nearer to the truth. I must say here that the present Director of the Meteoro- logical Institution in Vienna, Professor Yelynak, was so pleased with the instrument I had from Kew, that he asked me to order one for him of Mr. Barrow. The mean result derived from the observations from January 1 to Sep- tember 18, 1868, is =63° 32'-06; the result obtained with the Kew Circle is 63° 38'-80, being larger by 6/7. Munich. —Regular observations of absolute dip are not made at the Ob- servatory. The last determined dip was in 1866, in September, and was 64° 16'°8. The dip for the present time is deduced from the variation of horizontal force and the constant relation between it and the dip as found by Dr. Lamont from a large series of observations ; according to this the 1869. ] Lieut. Elagin’s Determinations of the Dip. 285 dip for September 1868 is 64° 10'9. The observed dip with the Kew Circle is 64° 7'*7, being smaller by 3!°2. Paris.—The observations of dip at the Observatory are made with an in- strument of Gambey regularly three times every day—that is, at 9 o’clock in the morning, at noon, and at 4 o’clock in the afternoon. This instru-- ment gives only the variations of dip. To determine the absolute dip, a long series of simultaneous comparisons with a Dip-circle have been made. The following dip is deduced from observations with this instrument on the same days as my observations: itis =65° 45'"3; the result I obtained with the Kew Circle is 65° 49°85, being 4'°5 larger. These were all the stations at which I was able to make satisfactory ob- servations; but as at most of these stations comparative observations atadjoint stations had been made before and the differences found between them, there was less need to extend my observations beyond the principal observatories. Table II. contains the dips observed at the different stations before mentioned, and the differences between the local instruments and the Circle from Kew. Taste II. ‘Dips observed | Dips observed| Local instru- Sep Ree 1868. ar local | with Circle | ments—Kew ee. instruments. | from Kew. Circle. Normal Observatory, Kew ......... 68 219 | 68 3-80 —1-61 Royal Observatory, Greenwich ...; 67 56°15 67 58°88 —2-73 _ TL TLD. ee een Aen hori 68 17°86 Brussels Observatory ............... 67 11:00 67 677 +4-93 Utrecht, Meteorol. Department ...; 67 47°70 67 43°30 +4:40 Vienna, Meteorol. Institution ...... 63 32-06 65 38:80 —6°74 MICU CPMSEEVALOLY 6. emaien iss nanlecese-seutus coon 627710 Pea tee COOSEEVALOLY.... 6.2... 0.cac dees 65 45°30 65 49°85 —4:55 I will now endeavour to deduce the most probable dips at each station. First I shall deduce the dip at Munich, as no observations are made there speciaily for dip, by taking the differences between the values I found at Munich and at every other station, and applying it to the result as found with the local instrument at each place. Thus the dip I obtained at Kew was 68° 3'-80, and at Munich was 64° 7':70; the difference is 3° 561; and ap- plying this to the result as found at Kew by the Kewinstrument 68° 2'°19, I deduce 64° 6'-09 as the dip for Munich; and treating all the other sta- tions in a similar way I find :— Sly Dip, from Kew........ = 64 6°09 ao) (Greenwieh, .. == © 4°97 ao Nonwiely .. 23 212720 % « \Beussela) so. -h1-95 to vUitrechGaeys es = 6 12" 10 coc ACLOMINA pee aes =O oG Parise! yap vc == old Mean.... 64 6°70 eo 286 On a New Class of Organo-metallic Bodies. [Feb. 11, And in a similar way I calculated the dips for all the stations, taking trecht first, because the dip found for Munich from this station gave a result differing from the mean the most of any; and then I treated Brussels in the same way, it being the next in order of discordance, and so on. I thus formed Table II1., giving the calculated dips, the observed dips with the local instruments and the Kew Circle, and the corrections for the Kew Circle. Tase III. Dips observed Dips observed Calcul.— Obs. Stations. Galen rita local: |r itaieereele a tps instruments. | from Kew. | Kew Circle. Rew folder: 68 i169 | 68 319 | 68 380 —$-11 Greenwich...| 67 56°84 Of ako) 67 58°88 — 2-04 Norwich...... 68 15:50 67 17°86 68 17-86 — 9°36 Brussels......, 67 4:12 67 11:00 OF M677 — 2:65 Utrecht ...... 67 41:37 67 47:70 67 43°30 —1-93 Vienna 5... ..|. | Go d07fo 63 32:06 63 38°80 —2:07 Munich ...... 64°C (OlC eee eee 64 7:70 —1-:00 PArisiendeeson 65 47°30 65 45:30 65 49°85 —2°05 Mean ...... — 2-03 This Table shows that the Circle from Kew gave at all stations the dip about 2! too large; and only for Munich this difference is but 1', which shows that the calculated dip for Munich is a little too large. Ill. “ On a New Class of Organo-metallic Bodies containing So- dium.” By J. Atrrep Wanxktyn, Professor of Chemistry in the London Institution. Communicated by Professor E. W. Braytey. Received February 6, 1869. Up to the present time organo-metallic bodies containing ethylene in union with the metal have been often sought, but never recognized. I have to announce the existence of organo-metallic compounds of ethy- lene with the alkali-metals. In ethylate of sodium, or at any rate in the substance which is produced by heating up to 200° C. the well-known crystals got by acting on alcohol with sodium, I see the hydrated oxide of ethylene-sodium— Ya” (C, H ye a { OH” ° which, as I have recently shown,. yields alcoho! and a new compound on being heated with the ethers of the fatty acids: thus Hydrate of ethylene- sodium. ~ Nia { C, lal Acetate of ethyl. C,H, 0 C,H, O Acetate of ethylene=-sodium. fC, Na | 0b, 11,0 ae Ha: Of — 1869. | On the Temperature of the Human Body. 287 Acetate of ethylene-sodium yields alcohol and common acetate of soda on treatment with water :— vot PCH ae t 2( Na | 00, Ho) + 2H, 0=2C, H,0+2Na0 C,H, 0. The extreme lightness of the so-called ethylate of sodium (it swims in ether) is a reason for regarding it as a compound belonging to a less con- densed order of sodium-compound than ordinary sodium-compounds. The property of yielding up its olefine in the shape of alcohol when it is treated with water is a reason for assigning to the new compound given by the action of acetic ether the above formula, and shows that the olefine is associated with the alkali-metal, not with the acid. IV. “On the Temperature of the Human Body in Health.” By Sypney Rineer, M.D. (Lond.), Professor of Materia Medica in University College, London, and the late AnpRew Patrick Stuart. Communicated by Dr. Bastian. Received December 18, 1868. (Abstract.) These observations were conducted by the authors in order to learn with minuteness the fluctuations of the temperature in health. They were performed on persons of different ages, and were in many instances continued through the night and day. The temperature was noted every hour, and on many occasions much more frequently. The following subjects are discussed in this communication :-— 1. The daily variation of the temperature. 2. The effects of food on the temperature. 3. The effects of cold baths on the temperature. 4. The effects of hot baths on the temperature. From their observations and experiments the authors have drawn the following conclusions :— The average maximum temperature of the day in persons under 25 years of age is 99°'1 Fahr.; of those over 40, 98°°8 Fahr. There occurs a diurnal variation of the temperature, the highest point of which is maintained between the hours cf 9 a.m. and 6 p.m. At about the last-named hour the temperature slowly and continuously falls, till, between 11 p.m. and 1 A.m., the maximum depression is reached. At about 3 A.M. it again rises, and reaches very nearly its highest point by 9 A.M. The diurnal variation in persons under 25 amounts, on an average, to 2°-2 Fahr. ; but in persons between 40 and 50 it is very small, the average being not greater than 0°87 Fahr.; nay, on some days no variation what- ever happens. In these elderly people the temperature still further differs #83 Messrs. Frankland and Lockyer on Gaseous Spectra [Feb. 11 from that of young persons; for in the former the diurnal fall occurs at any hour, and not, as is the case with young persons, during the hours of night. : Concerning the influence of food on the temperature of the body the authors have concluded that none of the diurnal variations is in any way caused by the food we eat. The experiments to prove this conclusion are very numerous. Some were made with the breakfast, others with the dinner and tea; but all point to the conclusion just stated. This important question is very fully discussed in the section devoted to it. By cold baths both the surface of the body and the deep parts were lowered in temperature. The temperature of the surface was in some instances reduced to 88° Fahr.; but the heat so soon returned to all parts as to show that the cold bath is of very little use as a refrigerator of the body. The cold bath produced no alteration in the time or amount of the diurnal variation. This began at the same hour, and reached the same amount as on those days when no bath was taken. By hot-water or vapour baths the heat of the body could be raised very considerably. ‘Thus, on some occasions, when using the general hot bath, the temperature under the tongue was noted to be between 103° and 104° Tahr., a fever temperature. The body beiag heated considerably above the point at which combus- tion could maintain it, it was then shown with what rapidity heat may be lost, simply by radiation and evaporation. ‘The particulars of these results are given in the paper. The experiments tend to prove that hot baths in no way affect the diurnal variation of the temperature. V. “Preliminary Note of Researches on Gaseous Spectra in re- lation to the Physical Constitution of the Sun.” By Hpwaxrp FRANKLAND, F.R.S., and J. Norman Lockyer, F.R.A.S. Received February 11, 1869. 1. For some time past we have been engaged in a careful examination of the spectra of several gases and vapours under varying conditions of pressure and temperature, with a view to throw light upon the discoveries recently made bearing upon the physical constitution of the sun. a Although the investigations are by no means yet completed, we consider it desirable to lay at once before the Royal Society several broad conclu- sions at which we have already arrived. It will be recollected that one of us in a recent communication to the Royal Society pointed out the following facts :— i. That there is a continuous envelope round the sun, and that in the 1869.] inrelation to the Physical Constitution of the Sun. 289 spectrum of this envelope (which has been named for accuracy of descrip- tion the “‘chromosphere”’) the hydrogen line in the green corresponding with Fraunhofer’s line F takes the form of an arrowhead, and widens from a — to the lower surface of the chromosphere. . That ordinarily in a prominence the F line is nearly of the same ee as the C line. iii. That sometimes in a prominence the F line is exceedingly brilliant, and widens out so as to present a bulbous appearance above the chromo- sphere. = iv. That the F line in the chromosphere, and also the C line, extend on to the spectrum of the subjacent regions and re-reverse the Fraunhofer lines. v. That there is a line near D visible in the spectrum of the chromo- sphere to which there is no corresponding Fraunhofer line. vi. That there are many bright lines visible in the ordinary solar spec- trum near the sun’s edge. vu. That a new line sometimes makes its appearance in the chromo- sphere. 2. It became obviously, then, of primary importance— i. To study the hydrogen spectrum very carefully under varying con- ditions, with the view of detecting whether or not there existed a line in the orange, and i. To determine the cause to which the thickening of the F line is due. We have altogether failed to detect any line in the hydrogen spectrum in the place indicated, 7. e. near the line D; but we have not yet completed all the experiments we had proposed to ourselves. With regard to the thickening of the I line, we may remark that, in the paper by MM. Plucker and Hittorf, to which reference was made in the communication before alluded to, the phenomena of the expansion of the spectral lines of hydrogen are fully stated, but the cause of the phenomena is left undetermined. We have convinced ourselves that this widening out is due to pressure, and not appreciably, if at all, to temperature per se. 3. Having determined, then, that the phenomena presented by the F line were phenomena depending upon and indicating varying pressures, we were in a position to determine the atmospheric pressure operating in a promi- nence, in which the red and green lines are nearly of equal width, and in the chromosphere, through which the green line gradually expands as the sun is approached*. With regard to the higher prominences, we have ample evidence that the gaseous destin of whieh they are composed exists in a condition of ezx- eessive tenuity, and that at the lower surface of the chromosphere itself the pressure is very far below the pressure of the earth’s atmosphere. * Will not this enable us ultimately to determine the temperature? 290 On the Physical Constitution of the Sun. [Feb. 11, The bulbous appearance of the F line before referred to’ may be taken to indicate violent convective currents or local generations of heat, the condition of the chromosphere being doubtless one of the most intense action. 4, We will now return for one moment to the hydrogen spectrum. We have already stated that certain proposed experiments have not been carried out. We have postponed them in consequence of a further consideration of the fact that the bright line near D has apparently no representative among the Fraunhofer lines. This fact implies that, assuming the line to be a hydrogen line, the selective absorption of the chromosphere is insufii- cient to reverse the spectrum. It is to be remembered that the stratum of incandescent gas which is pierced by the line of sight along the sun’s limb, the radiation from which stratum gives us the spectrum of the chromosphere, is very great compared with the radial thickness of the chromesphere itself; it would amount to something under 200,000 miles close to the limb. Although there is another possible explanation of the non-reversal of the D line, we reserve our remarks on the subject (with which the visibility of the prominences on the sun’s disk is connected) until further experiments and observations have been made. 5. We believe that the determination of the above-mentioned facts leads us necessarily to several important modifications of the received theory of the physical constitution of our central luminary—the theory we owe to Kirchhoff, who based it upon his examination of the solar spectrum. Accor- ding to this hypothesis, the photosphere itself is either solid or liquid, and it is surrounded by an atmosphere composed of gases and the vapours of the substances incandescent in the photosphere. We find, however, instead of this compound atmosphere, one which gives us nearly, or at ail events mainly the spectram of hydrogen; (itis not, how- ever, composed necessarily of hydrogen alone ; and this point is engaging our special attention ;) and the tenuity of this incandescent atmosphere is such that it is extremely improbable that any considerable atmosphere, such as the corona has been imagined to indicate, lies outside it, —a view strengthened by the fact that the chromosphere bright lines present no appearance of absorption, and that its physical conditions are not statical. With regard to the photosphere itself, so far from being either a solid surface or a liquid ocean, that it is cloudy or gaseous or both follows both — from our observations and experiments. The separate prior observations of both of us have shown :— i. That a gaseous condition of the photosphere is quite consistent with its continuous spectrum. ‘The possibility of this condition has also been suggested by Messrs. De La Rue, Stewart, and Loewy. ii. That the spectrum of the photosphere contains bright lines when the 1869.] On the Structure of Rubies, Sepphires, Diamonds, &§c. 291 limb is observed, these bright lines indicating probably an outer shell of the photosphere of a gaseous nature. ii. That a sun-spot is a region of greater absorption. iv. That occasionally photospheric matter appears to be injected into the chromosphere. May not these facts indicate that the absorption to which the reversal of the spectrum and the Fraunhofer lines are due takes place in the photosphere itself or extremely near to it, instead of in an extensive outer absorbing atmosphere? And is not this conclusion strengthened by the con- sideration that otherwise the newly discovered bright lines in the solar spectrum itself should be themselves reversed on Kirchhoff’s theory? this, however, is not the case. We do not forget that the selective radiation of the chromosphere does not necessarily indicate the whole of its possible selective absorption ; but our experiments lead us to believe that, were any considerable quantity of metallic vapours present, their bright spectra would not be entirely invisible in all strata of the chromosphere. February 18, 1869. Lieut.-General SABINE, President, in the Chair. The Most Noble the Marquis of Salisbury and the Right Hon. Lord Houghton were admitted into the Society. The following communications were read :— I, “On the Structure of Rubies, Sapphires, Diamonds, and some other Minerals.” By H.C. Sorsy, F.R.S., and P. J. Burzer. Received December 8, 1868. [Plate VII.] For many years Mr. Butler has had the opportunity of examining very many rubies, sapphires, and diamonds, and has taken advantage of it in forming a most interesting collection, cut and mounted as microscopical objects. He had very carefully studied the included fluid-cavities, and ascertained many curious facts. Mr. Sorby had for some time paid much attention te the microscopical structure of crystals, and published a paper * in which he showed that their microscopical characters often serve to throw much light on the origin of rocks. Mr. Butler therefore placed the whole of his collection in Mr. Sorby’s hands for careful examination, and it was decided that a paper should be written by the two conjointly ; and since Mr. Sorby had previcusly made many experiments in connexicn with the expansion of liquids, as already described in a paper published in the Philosophical Magazine+, he took advantage of the opportunity to investi- * Quarterly Journal of Geo). Soc., 1858, vol. xiv. p. 453. T “ On the Expansion of Water and Saline Solutions at High Temperatures,” August 1859, vol. xviii. p. 81. 292 Messrs. Sorby and Butler on the Structure of — [Feb. 18, gate the law of the expansion of the very interesting fluid met with in the cavities of sapphire. In describing the various facts, it will be well to consider them in rela- tion to the following general principles :— (1) The structure of the various minerals as mere microscopical objects. (2) The physical characters of the fluid-cavities, as throwing light on the origin of the minerals. (8) The influence of some included crystals on the structure of the sur- rounding mineral. Sapphires. By far the most interesting objects contained in sapphires are the fluid- cavities. Their occasional presence has been already noticed by Brewster *, who met with one no less than about = inch long, two-thirds full of a liquid which expanded so as to fill the whole cavity when heated to 82° F. (28° C.). He thought the liquid was less mobile than that described by him in topaz, and could not see a second liquid in the cavity. ‘Though many thousand sapphires have been examined by the authors, no such large cavity has been found ; but several have been met with about ;4, inch in diameter; the greater number are far less, and some are very minute; and they seem to contain only the liquid which expands so much when warmed. The size of the included bubble varies much, according toe the temperature. At the ordinary heat of a room it is sometimes equal to one-half of the capacity of the cavity, whereas in other cases the cavity is quite full. This is espe- cially the case with the very small cavities, and is to some extent due to the forced dilatation of the liquid. But if we only take into consideration the larger cavities, the temperature required to expand the fluid so as to fill them certainly varies from 20° to 32° C. (68° to 90° F.), and this not only in different crystals, but also, to a less extent, in the same specimen. As illustrations of the form of such cavities, we refer to Plate VII. figs. 1, 2, 3, and 4, the extent to which they are magnified being shown in each case. At the ordinary temperature the bubble in the cavity shown by fig. 1 is about one-half its diameter, but disappears entirely at 30° C. By carefully mea- suring the size of the cavity in various positions, and comparing it with the diameter of the bubble at 0° C., it appears that the liquid expands from 100 to 152 when heated from 0° to 30° C. Fig. 2 is a tubular cavity, and shows in a very excellent manner the boiling of the liquid when it cools after having been made to expand to fill the whole space. At the ordinary temperature the liquid occupies only about half the cavity ; but when heated in a water-bath to 32° C., it fills it entirely. No bubble is formed until the temperature has fallen to 31°; and then innumerable small bubbles are suddenly formed, which rise to the upper part and unite; but instead of the liquid merely contracting by further cooling, it still continues to boil for some time, as represented in the drawing. Two other large cavities * Sochting’s Einschlisse von Mineralien in krystallisirten Mineralien, p. 121, who re- fers to Edin. Journ. of Sc., vol: vi. p. 115. 1869.] Rubies, Sapphires, Diamonds, and some other Minerals. 298 contained in the same specimen also behave in the same manner, and become full and suddenly boil at almost absolutely the same temperature, as that figured. We need scarcely say that such cavities are extremely rare, and are very remarkable even when merely looked upon as microsco- pical objects, independently of their interest in connexion with physics. Fig. 3 is a tubular cavity of more irregular form, and is interesting on ac- count of there being two plates of the sapphire projecting into the cavity so as to nearly divide it into three portions. At the ordinary temperature these partitions prevent the passage of the bubble from one part to the other ; but by breathing on the object through a flexible tube, the slight increase of temperature expands the liquid so as to make the bubble small enough to pass into the next compartment; and a repetition of the process causes it to pass into that at the other end. Such plates projecting into the cavities are very common; and it is requisite to pay attention to this fact, since otherwise they might easily be mistaken for crystals of some other substance included in the cavity, which, if they ever occur, must be extremely rare, since no decided case has come under our notice. Tn examining sections of sapphire cut in a plane more or less parallel to the principal axis of the crystal, the double refraction is so strong that two images of every object lying at any depth below the surface are seen, in such a manner as to make them very confused. This may be avoided by using polarized light without an analyzer, and arranging the plane of polarization so as to coincide with one of the axes of the crystal. High powers may then be used with perfect definition ; and they show many small cavities, sometimes of most irregular forms, like fig. 4; and very often their sides are so inclined that they totally reflect transmitted light, and appear black and opake. In some specimens most of the cavities have lost their fluid. Besides fluid-cavities, there are many small crystals of other minerals included in sapphires, but not so many asin rubies. The most striking are small plate-like crystals, often of triangular form, with one angle very acute. ‘They are very thin, and give the colours of thin plates; so that when viewed by reflected light they look something like the scales from a butterfly. Seen edgewise, they appear as mere black lines, and are ar- ranged parallel to the three principal planes of the sapphire, as shown by fig. 5. These small crystals and the minute fluid-cavities cause many sapphires to appear milky by refiected, and somewhat brown by trans- mitted light ; and being arranged in zones related to the form of the erys- tal, they often show, as it were, lines of growth. Rubies. Though the ruby and the sapphire are of course essentially the same mineral, yet their structure is in many respects as characteristically different as their coiour. The number of the fluid-cavities in rubies is far less, and the larger cavities are very rare, and only contain what appears to be water or a saline aqueous solution, as is shown by the amount of expansion when 294 Messrs. Scrby and Butler on the Structure of [Feb. 18, the specimen is heated to the temperature of boiling water. Those con- taining a similar fluid to that included in sapphires do occasionally occur ; and when they are minute, they are extremely interesting, since they show the spontaneous movement of the bubbles to greater perfection than any mineral that has come under our notice. This is perhaps to some extent due to the nature of the liquid, which is more mobile than the saline aqueous solutions contained in the cavities of the quartz of granite and syenite. It is manifestly a molecular movement analogous to that seen in all matter when very minute particles are suspended in a liquid, so as to allow freedom of motion; and the rapidity of the movement is certainly dependent on the size of the particles. It is not seen to advantage if the diameter of the bubbles is more than ;,4,, of an inch ; but whenit is about suey they move to and fro in the most surprising manner, with such rapi- dity that the eye can scarcely follow them. The number of small crystals of other minerals included in rubies is often very great. There must be at least four different kinds; but it would be difficult to determine what minerals they all are. Some are very well cha- racterized octahedrons, variously modified ; and, as shown by fig. 5, their planes are very generally arranged parallel to planes of the ruby, and to the small plate-like crystals already mentioned in describing sapphire. These octahedrons have no influence on polarized light, and in general form - and character correspond so closely with spinel that it seems very probable that they are that mineral. For some time we thought they were angular fluid-cavities filled with hquid; but when cut across im the sections they are clearly seen to be solid, though less hard than ruby. Many of the other included crystals are of such very rounded forms that, if it were not for their action on polarized light, they might easily be mistaken for cavi- ties filled with some fluid. Most of these rounded crystals are colourless ; but some are of more or less dark orange-red colour, and are certainly not the same mineral as the colourless or the octahedral crystals ; and in all proba- bility the thin andflat are a fourth kind. Occasionally alternating plates of ruby with their axes in different positions gave rise to a beautiful series of coloured stripes when examined with polarized light. Spinel. The ruby spinels from Ceylon sometimes contain fluid-cavities which differ in a striking manner from those of any other mineral that has come under our notice. One of these is shown in fig. 7. They are toa great extent filled with a yellow substance, indicated by the shading, which seems to be either a solid or a very viscous liquid. It incloses transparent, sometimes well-defined cubic crystals, which haye no action on polarized light ; trans- parent, prismatic, or plate-like crystals, which strongly depoiarize it ; and black opake crystals, either in larger pieces or mere grains. The rest of the cavity is in each case about one-third full of a colourless liquid, which seems to contract on the application of heat, because it passes entirely into 1869.| Rubies, Sapphires, Diamonds, and some other Minerals. 295 vapour, as occurred in some of the cavities in topaz described by Brewster. In this change it must expand about six hundred times less than when water passes into steam. Spinel also incloses crystals of several other minerals which we have not yet been able to identify. Aquamarina. The most striking peculiarity of this mineral is the occurrence of num- bers of fluid-cavities containing two fluids and a vacuity, as shown by fig. 6. Emerald. Some of the specimens which we have examined are so full of fluid- cavities that they are only partially transparent. They differ entirely from those already described, and contain only one liquid, which does not sensibly expand when warmed. Im all probability this is a strong saline aqueous solution, since the cavities also inclose cubic crystals, as shown by fig. 8, which dissolve on the application of heat, and recrystallize on cooling. On the whole, therefore, these cavities are very similar to those found in the quartz of some granites, and in some of the minerals found in blocks ejected from Vesuvius, as described in Mr. Sorby’s paper on the microscopical structure of crystals, already referred to. Diamend- Few, if any, of the specimens of diamond that have come under our notice contain objects similar to those which, in the opinion of Goppert*, are evidence of its having been derived from vegetable remains, but we have been able to study to great advantage some facts which do not appear to have presented themselves to either GOppert or Brewster. We have examined twenty-one objects similar to the two described by Brewster, in his paper in the Trans- actions of the Geological Society+; and this has enabled us to clear up some of the difficulties to which he alludes, and has led us to propose a different explanation. He thought that the black specks, which were surrounded by a black cross when examined with polarized light, were minute cavities ; but at the same time he admitted that they were so small that it was not possible to say whether they contained a fluid or were empty. Judging from what we have seen of such small examples, we consider it impossible to say whether they are cavities or inclosed crystals; but fortunately we have met with several of such a size and character that it was quite easy to see that they were crystals. Fig. 9 is a most excellent example of this fact. The form is clearly that of a crystal, and it depolarizes light very powerfully. Its refractive power must be very much less than that of diamond; for the inclined planes totally reflect the transmitted light, and thus lock quite black, as shown in the figure. It is this circumstance which causes many smaller inclosed crystals to appear like mere black specks. * “Ueber Hinschliisse im Diamant,’ Natuurkundige Verhandelingen, Haarlem, 1864, -f 2nd series, vol. ili, p. 455. 296 Messrs. Sorby and Butler on the Structure of [Feb. 18, Brewster has shown that the irregular depolarizing action of diamond is analogous to that of an irregularly hardened gum; and this much inter- feres with the perfection of the black crosses seen round the inclosed crys- tals, and sometimes even neutralizes this action. Still, as a general rule, a black cross is seen; and, as described by Brewster, when examined by means of a plate of selenite which gives the blue of the first order, the tints of the sectors in the line of its principal axis are depressed in the same manner as when such a black cross is produced by the compression of glass—thus proving that the inclosed crystals have exerted a pressure on the surrounding diamond. We, however, do not imagine that the crystals have increased in size, but that probably they have prevented the uniform contraction of the diamond, which, as already mentioned, must have been very irregular, even where no such impediment was present. A few of the crystals inclosed in rubies give rise to similar black crosses, as shown by fig. 11; and we are informed by Professor Zirkel that his brother-in- law Professor Vogelsang has prepared a thin section of a specimen of partially devitrified glass, which also shows black crosses round the inclosed crystals. Brewster suggested that this phenomenon in diamond was due to the elastic force of an inclosed gas or liquid, and compared it with what is seen in the case of some cavitiey in amber. We, however, find that the optical character of the crosses seen round the undoubted cavities in amber is the very reverse of that in the case of diamond, and cannot be explained by the mere mechanical action of an included elastic substance, but is similar to the change to a crystalline state which has occurred over the whole external surface, and on both sides of cracks passing from it inwards. The optical properties, however, are not the only evidence of contraction round crystals inclosed in diamond ; for actual cracks are often seen to pro- ceed from them. These present the striped appearance shown in fig. 10, owing to more or less perfect total reflection from their waved surface. | The same kind of phenomenon may be seen in sapphire, and still better in spinel, as shown by figs. 12 and 13. Sometimes there is a system of radia- ting cracks nearly in one plane, terminating in a transverse crack which surrounds the whole, as in fig. 12; and in other cases there are various complicated wavy cracks in different planes, as in fig. 13. There seems to be some connexion between this structure and the nature of the in- cluded minerals ; for round some kinds itis very common, but round others very rare or quite absent ; and it appears probable that it may be referred to unequal contraction in cooling from a high temperature ; and, if so, the results would necessarily depend on a variety of circumstances. Now that attention has been directed to it, it will probably be found to be a very common peculiarity of certain classes of minerals, and serve to throw a good deal of light.on their origin. Crystals surrounded by radiating cracks on a much larger scale have 1869.| Rubies, Sapphires, Diamonds, and some other Minerals. 297 been observed by Mr. David Forbes*, and may, we think, be explained in a similar manner. The crystals formed in blowpipe beads kept hot for some time over the lamp, also furnish good illustrations of these facts. Phosphate of zirconia is deposited in cubes from a borax bead to which much microcosmic salt has been added; and when examined with the microscope whilst cooling, eracks like those described in diamond and spinel are seen to be formed round many of the crystals, which are evidently due to the crystals con- tracting less than the surrounding material. On the contrary, the long prisms of borate of baryta deposited from solution in borax are seen to separate from the borax on cooling, and to be filled with transverse cracks, like those in sehorl inclosed in quartz, which is clearly owing to their con- tracting more than the borax. Fluid-cavities in general. Before discussing the nature of fluid-cavities in connexion with the origin of the various minerals, we think it best to describe the remark- able properties of the liquid included in the sapphire, and to point out what it seems to be. Brewster, in his paper on the fluid-cavities in topazyt, says that the more expansible liquid contained in them expands one-fourth its size, when heated from 50° to 80° F, or thirty-one and a quarter times as much as water; and, as already stated, he found that the fluid in sapphire expands about one-half when heated to 82°F. Though this amount of expansion is very remarkable, yet, when the relative expansion at various temperatures is examined, it will be seen to be still more remarkable. Very fortunately the tubular cavity in sapphire, shown by fig. 2, is most admirably fitted for experiment. Mere inspection shows that its general diameter is very uniform; and that it is really so can be proved by causing the liquid to pass from one end to the other; for at 175° C. the length of the column of liquid was 323, of an inch, whether it was at the end A or B. The total effective length of the cavity is -3%. The specimen inclosing this cavity was fastened to a piece of glass, and this was fixed in a beaker containing water, supported so that the cavity was in the focus of the microscope under a low power. The temperature was raised very slowly, and was maintained for some minutes at each parti- cular degree at which it was thought desirable to measure the volume of the liquid; and this was usnally repeated over and over again when the heat was both rising and falling, so as to obtain as accurate a result ag possible. In making the measurements with the micrometer, care was taken to allow for the tapering ends of the cavity and the curved surface of the liquid. The results are given in degrees Centigrade. Though the expansion below 30° was very great, compared with that of any other known substances except liquid carbonic acid and nitrous oxide, when the * Kd. New Phil. Journ. July 1857. t Trans. Roy. Soc, Edin. 1824, vol. x. p. 1. 298 Messrs. Sorby avd Butler on the Structure of — | Feb. 18, temperature rose above 30° it was so very extraordinary that it was not until after having performed the experiment over and over again that Mr. Sorby felt confidence in the results. This will not be thought surprising when we state that from 31° to 32° the apparent expansion of the liquid is no less than one-fourth of the bulk i¢ eceupies at 31°; the length of the column increasing for that single degree from ;4% to 3% inch. This is about 780 times as great as the expansion of water would be, and even 69 times as much as that of air and permanent gases. It was not possible to ascertain the amount of expansion above 32° C., because the cavity was quite filled at that temperature. If the expansion increase at the same increased rate, the liquid would soon occupy several times as much space; but it seems very probable that before then it would pass into the state of gas. At ail events it appears as if this enormous rate of expansion indicated a close approach to a fresh physical condition. The following Table gives the results of the experiments ; and it has been found, by drawing them as a curve, that their general relations indicate that there cannot be any serious error; but at the same time, considering all the circumstances, they must only be looked upon as tolerably good approximations to the truth. Temperature. Volume. (@) 0: Cie aact okt ee 173 cet aaa ae eS D0, bs as lg eae Pa Ree IN eile Me 7) 5 2S wrcahiat ns etn jic cei Ne Se 5 5 eke 139 Us Seen Shade S~ 150 Dil e eanpuine: ee rte a l/s DOr, gee. Ste isos oe eee The apparent expansion of the liquid is doubtless to some extent in- creased by the condensation of the gas, as the space occupied by it is diminished. When in the highly expanded condition this hquid appears to be remarkably elastic. Berthelot has shown, in his paper on forced dilatation *, that the force with which liquids adhere to the interior of a glass tube is sufficient to prevent their contraction to the normal volume, if they have been heated so as to expand and quite fill the tube, and then cooled to a temperature below that requisite to fill it. This fact must always be borne in mind in studying fluid-cavities, and explains why the bubbles, as it were, hesitate to return, and then make their appearance with a sudden start. Such a forced dilatation is very remarkable in the case described ; for though it was requisite to raise the temperature to 32° C. to fill the cavity, no vacuity was formed until it fell to 31°; and therefore it seems as if the force of cohesion were sufficient to stretch it to considerably * Annales de Chimie sér, 3. t. xxx. p. 232. 1869.] Rubies, Sapphires, Diamonds, and some other Minerals. 299 more than its normal bulk, even perhaps to the extent of one-fifth or one- fourth. Moreover, in the case shown in fig. 1., the liquid expanded so as to fill the cavity at about 30° C.; and yet it can be heated up to 42° without bursting it, though, even if the expansion did not continue to Increase, and were the same for each degree as from 31° to 32°, the normal volume would be about four times that of the cavity,—which in any case seems only to be explained by supposing that its elasticity is-most remark- ably great, more like that of a gas than of a liquid. ‘There was no decided evidence of its passing into a gaseous state, as does occur when cavities con- tain a less amount of liquid. Simmiler * has shown that the physical properties of the liquid in topaz, as observed by Brewster, agree more nearly with those of liquid carbonic acid than with those of any other known substance. Dana, in his ‘ Minera- logy’ (5th edition, 1868, p. 761), calls it Brewséerlinite, and says that its composition is unknown. The facts at Simmler’s command were not in all respects satisfactory—since the amount of expansion given by Brewster was from 10° to 26°°7 C., whereas that of liquid carbonic acid observed by Thilorier was from 0° to 30°, and, as shown above, the expansion in- creases so much as the temperature rises that the average rate for 1° is very indefinite. ‘The only reliable method is therefore to compare the ex- pansion between equal degrees of temperature. According to Thilorier + liquid carbonic acid, when heated from 0° to 30°, expands from 100 to 145. One of the experiments described above showed that the liquid in sapphire expands from 100 to 152; and the other from 100 to 150, which is the most reliable. ‘This agrees so closely with the expansion of liquid carbonic acid, that the difference might easily be due to a slight error in the ther- mometers. The expansion of ordinary liquids is not to be compared with it, nor is that of liquid sulphurous acid. Dr. Frankland has kindly ascer- tained this fact, with special reference to the case in question, and found that from 0° to 32° C. the expansion was ouly from 100 to 104°36 instead of to 217. According to Andréefft the expansion of liquid nitrous oxide is not much inferior to that of liquid carbonic acid, being, from 15° to 20°, :00872 for each degree, which differs decidedly from that of the liquid in sapphires. The occurrence of nitrous oxide in minerals is also so very much more im- probable, that, on the whole, it seems as if we should be justified in con- cluding provisionally that it is liquid carbonic acid, which, like water, should therefore be classed amongst natural liquid mineral substances. Brewster has shown § that when cavities in topaz contain less than one- third of their volume of the expansible liquid, it does not expand when heated, but passes entirely into the state of a compressed vapour. Un- * Pogg. Ann. vol. cv. p. 460. : + Gmelin’s Handbook of Chemistry, Cavendish Society’s Translation, vol. i, p. 225. { Liebig’s Ann. vol. cx. p. I. § Trans Roy. Soc. Edin. vol. x. p. 25. VOL. XVII. 3800 —— Messrs. Sorby and Butler on the Struciure of [Feb. 18, fortunately he does not state the temperature at which this occurs, nor does he seem to have tried to ascertain the exact limit of the volume, which must, however, lie between one-half and one-third. Cagniard-Latour* found that when ether and other liquids sealed up in small strong tubes, with a certain space left empty, were heated, they expanded very much, and sud- denly passed into the state of vapour. The temperature, pressure, and vo- lume at which this change took place varied very considerably. Ether ex- panded to nearly double its volume, and passed into vapour at about 200° C., with an elastic force of 37 or 38 atmospheres. Alcohol expanded to about three times its volume, and passed into vapour at about 260° C., with an elastic force of 119 atmospheres; whereas water appeared to expand to nearly four times its volume, and required a temperature near that at which zine melts (328° C., Daniel). When in this highly expanded state, the liquids were very mobile, and seemed much more compressible than under other circumstances; for they did not burst the tube, if too much had been sealed up in it, until after their normal volume would have been decidedly greater than its capacity. No one could fail to see that these phenomena have much in commen with what occurs at a lower temperature in the case of the liquid inclosed in sapphire, and that they are of great importance in connexion with the origin of fluid-cavities. Since they become full of liquid at a comparatively low temperature, it was not unreasonable to sup- pose that the minerals in which they occur must have been formed where the heat was scarcely above that of the atmosphere ; but these facts seem to show that the occurrence of such fluid-cavities is quite reconcilable with a very high temperature ; for it is obvious that if, at a great depth below the surface, heated, highly compressed gaseous carbonic acid were inclosed in growing crystals, it might condense on cooling so as to more or less com- pletely fill the cavities with the daqued acid. If the same principles could be applied in the case of water, we should be led to infer that it could not exist in a liquid state at a higher tempe- rature than that of dull redness, corresponding closely with what Mr. Sorby deduced from the fiuid-cavities in some volcanic rocks. In that case, ac- cording to Cagniard-Latour, the liquid when condensed would occupy only one-fourth part of the cavity, and it would searcely be hkely to con- tain avy fixed salt in solution; whereas the fiuid-cavities in the minerals of ejected blocks are often two-thirds full of what seems to have been a supersaturated solution of alkaline chlorides. ‘The phenomena now under consideration should certainly be borne in mind in studying voleanic action ; and itis possible that some cavities now containing water may have been formed by the inclosure of very highly compressed steam. In some cases the requisite pressure would be enormous, and other facts seem to show that it was more generally caught up in a liquid state. The cavities in emerald are very interesting in connexion with this subject, and also furnish strong evidence against the opinion that the liquid was not * Ann. de Chimie, 1822, t. xxi. pp. 127 & 178; t. xxi. p. 410. 1869.] Rubies, Sapphires, Diamonds, and some other Minerals. 3801 present when the crystals were formed, but penetrated into the fluid-cavities at a subsequent period, and either filled vacant spaces, or removed and re- placed the material of glass cavities, as suggested by Vogelsang*. In the specimens which we have examined, each of the cavities contains what is no doubt an aqueous saline solution, and, as shown by fig. 8, one or more cubic crystals, probably chloride of potassium, which dissolve on the appli- cation of heat, and are deposited again on cooling. These cavities are thus analogous to those met with im the quartz of some granite, and in the mi- nerals of blocks ejected from Vesuvius ; and it seems difficult, if not impos- sible, to explain them except by supposing that a strong saline solution was caught up by the mineral at the time of its formation. In some cases the amount of such saline matter is so great in comparison to the liquid, that a high temperature wouid be requisite to make it all dissolve. It also seems probable that, if water could penetrate into such crystals, it would soon be lost when they were kept dry. This certainly occurs in some Soluble salts, especially those containing combined water, and in some minerals of loose texture; but we have never seen evidence of it when fluid-cavities are completely inclosed in hard and dense substances like quartz or emerald. ‘Though in some instances the size of the bubbles does not bear a uniform relation to that of the cavities, yet in many cases the general proportion is very similar in each specimen ; and the exceptions can easily be explained by supposing that occasionally small bubbles of gas were caught up along with the water, or that there was some variation in either temperature or pressure during the growth of the crystal; all of which conditions were discussed in Mr. Sorby’s paper already referred to. We have not had the opportunity of studying many examples of cavities which contain two fluids, probably water and liquid carbonic acid, and therefore forbear to say much about them. According to Brewster} the temperature at which those in topaz become full corresponds very closely with what we have observed in the case of sapphire, so that the carbonic acid might have been inclosed either as a highly dilated liquid, or as a highly compressed gas; but since the other liquid has deposited crystals which dissolve on the application of heat, it seems most probable that the water was caught up in a liquid state, sometimes perhaps holding a con- siderable amount of carbonic acid in solution as a gas. On the whole, therefore, the various facts described in this paper seem to show that ruby, sapphire, spinel, and emerald were formed at a moderately high temperature, under so great a pressure that water might be present in a liquid state. The whole structure of diamond is so pecitiie that it can scarcely be looked upon as positive evidence of a high temperature, though not at ail opposed to that supposition. The absence of fluid-cavities-con- taining water or a saline solution does not by any means prove that water * Philosophie der Geologie und mikroskopische Gesteinsstudien, (Bonn, 1867 )pp. 155, 196. T Trans. Roy. Soc. Edin. vol. x. p. 1 e¢ seq. { See Brewster’s paper, Phil. Mag. tof; vol, Xxxi. p. 497, Zz 2 302 Mr. Huggins on Solar Prominences. [¥eb. 18, was entirely absent, because the fact of its becoming inclosed in crystals depends so much on their nature. At the same time the occurrence of fluid-cavities containing what seems to be merely liquid carbonic acid is scarcely reconcilable with the presence of more than a very little water in either a liquid or gaseous form. We may here say that we do not agree with those authors who maintain that the curved or irregular form of the fluid-cavities is proof of the minerals having been in a soft state, since ana- logous facts are seen in the case of crystals deposited from solution. EXPLANATION OF PLATE VII. Figs 1. & 2. Fluid-cavities in sapphire ; magnified 20 linear. 3. Fluid-cavity in sapphire, partially divided by plates of sapphire ; mag. 50. 4, Branched fluid-cavity in sapphire ; mag. 50. Fig. 5. Crystal of spinel ? inclosed in ruby ; mag. 50. 6. Cavity in aquamarina, with two fluids; mag. 150. 7. Cavity in ruby spinel; mag. 100. : Fig. 8. Fluid-cavity in emerald, with soluble crystals; mag. 200. Fig, 9. Crystal inclosed in diamond, surrounded by a black cross, as seen with pola- rized light; mag. 100. Fig. 10. Crystal inclosed in diamond, with a crack proceeding from it; mag. 100. Fig. 11. Crystal inclosed in ruby, surrounded by a black cross, seen by polarized light ; mag. 75. Figs. 12 & 13. Crystals in ruby spinel, surrounded by various cracks ; mag. 50. II. “ Note on a Method of viewing the Solar Prominences without an Hclipse.” By Witi1am Hvueerns, F.R.S. Received February 16, 1869. Last Saturday, February 13, I succeeded in seeing a solar prominence so as to distinguish its form. A spectroscope was used; a narrow slit was inserted after the train of prisms before the object-glass of the little tele- scope. ‘This slit limited the light entering the telescope to that of the refrangibility of the part of the spectrum immediately about the bright line coincident with C. The shit of the spectroscope was then widened sufficiently to admit the form of the prominence to be seen. The spectrum then became so impure that the prominence could not be distinguished. A great part of the light of the refrangibilities removed far from that of C was then absorbed by a piece of deep ruby glass. The prominence was then distinctly perceived, something of this form. Sorby & Butler Proc.Qov. Joc Vol_ XVII Plate VIl. H.C Sorby del. W.H-Wesley lith. W. West rump - 1869.] Lieut. Herschel’s Observations of Southern Nebule. 303 A more detailed account is not now given, as I think I shall be able to modify the method so as to make the outline of these objects more easily visible. February 25, 1869. Capt. RICHARDS, R.N., Vice-President, in the Chair. The following communications: were read :— I. “ Additional Observations of Southern Nebule.” In a Letter to Professor Stones, Sec. R.S., by Lieut. J. Herscurn, R.E. Communicated by Prof. Stoxrs. Received January 4, 1869. Bangalore, Dec. 1, 1868. Dear Si1r,—I have the pleasure to subjom a few additions to my former list of Southern Nebulee spectroscopically examined. The observations extend from the 24th October to the 20th November. I will first enumerate those of which no trace of a spectrum of any kind has been detected, and which, I can with confidence state, have no other than a continuous spectrum. Iam enabled to do this for the following reason—that even when the jaws of the slit were entirely removed, so as to command a perfectly free field of view (in which stellar spectra were frequently recognized), no light from these objects was visible. That no doubt might remain as to the justice of this conclusion, three faint plane- tary nebulze were looked at in the same way, and were more or less easily recognized as spots of light in the spectroscopic field. It is much to be regretted that I did not long ago make the experiment ; had I done so I should unquestionably have saved myself many tedious hours lost in vain searching. The following may safely be erased from a list of nebulze to be examined for evidence of a ‘‘ linear’ character :— Nos. 47: of. “Very bright ; pretty small.”’ 27. *“ Very bright; very large.” 67. ‘Very bright; large.” *162. ‘* Globular cluster; bright ; large.” fos. ~ Very bright ; large.”* 339. “ Bright; large.” *342. “Very bright; pretty large.” 361. “ Very bright; very large.” 369. ‘Bright; pretty large.” +544. “ Very bright ; very large.” 604. “‘ Very bright; pretty large.” 7o10. ° Very bright; large,” * These were not looked at in the way described above (without a slit), but are nevertheless included, because it is certain they have no visible spectrum. t+ The same remark applies to these; they were twice examined. The brackets denote that the objects are so near each other that one observation sufficed for both. 304 Lieut. Herschel’s Observations of Southern Nebula. [Feb. 25, 709. ak 7ol. 7A. 744. 746. 748, 750- 747. 792. “Very bright; small.” “Bright; large.” “Very remarkable; very bright; very large; barely re- solvable.” } “Globular cluster ; bright; pretty large.” ** Globular cluster; very bright; pretty large.” “ Bright; pretty small.” “Globular cluster; very bright; pretty large; partially resolved.”’ ‘Very bright; pretty large.” \ ‘Considerably bright; pretty small.’ “‘Very bright; large.” “ Bright ; pretty small.”’ “Very bright; large.’’ “Globular cluster; bright; considerably large; partially resolved.” DEX \ * Bright; very large.” “Pretty bright; pretty large.” “ Very bright ; pretty small.” “‘ Very bright ; very large; partially resolved.”’ “ Globular cluster ; bright; pretty large.” The following were not spectroscopically examined, only because they appeared too faint in the telescope :— Nos. 279. 811. 813. } S15. 824. 916. « Bright ; small.” «Bright; large.” «Bright ; large.” “ Pretty bright ; round.” “Very bright ; very large.” ‘Very bright; large.” The following were ‘not identified”? :-— Nos. 73. “Very bright; small.” [Not seen on three different nights, 243. 769. with clear sky. | “Bright; small.” Several small mdistinet objects in the field. . * Very bright; small.’ Not found: two independent settings gave the same field. 1. * Bright; small.” [No remark.| 70. “Very bright; round.’ Nosuch object. No. 685 precedes by 24 min., and has the same N.P.D.; it appears as de- scribed, very bright in the middle, and has a small star invelved. ‘Globular cluster; very bright.” Not found on two nights. 1869.| Lieut. Herschel’s Observations of Southern Nebule. 305 Checked AX by No. 767 ; “‘ very bright; large.’ In searching for it, found a nebula which agreed well with No. 766, ‘pretty faint; small.’ 1401. ‘‘ Very bright; small.” Not recognized ; twice. I come now to those of which the spectrum has been recognized. The following have continuous spectra :— Nos. 138. “Very remarkable; extremely bright; extremely large.’ A fine object, and certainly very bright; but the spectrum was recognized with great difficulty (through the slit). 600. <“ Verybright; pretty large; partially resolved.” Spectrum continuous. a 685. “Globular cluster ; very bright; pretty large; round; easily resolvable.” Spectrum continuous—readily. 697.) “Very bright; considerably large.’ . Spectrum continuous —without difficulty. * Pretty bright ; pretty small.” ? 715. ‘‘Very bright; pretty small.’ Spectrum continuous—barely visible. 748. “Globular cluster; very bright; pretty large; round; par- tially resolved.”’ Spectrum continuous. 1061. “Globular cluster; remarkable; very bright; very large; round; well resolved.” Spectrum continuous—bright. 1076. “Very bright; large; round; barely resolvable.’ Spectrum continuous. 4687. *‘ Remarkable; globular cluster; bright ; large; stars.’ Spec- trum continuous—bright, almost stellar in middle. Lastly, I am able to report that one globular cluster proves to be of the same character as the “planetary” nebule, viz. :— No. 826. “Globular cluster; very bright; small; round; barely re- solvable (IV. 26).”” Spectrum “linear.” This object shows one principal, one secondary, and one very faint line in the usual places. It also shows an undoubted continuous spec- trum, principally (but not only) on the more refrangible side. This is visible even when the slit is very narrow. The following measurements were taken—that of D by a spirit flame before the object-glass :— Prin, line,== 5:17 (D=3-02) Ge elite A ce ae No. 1225. “A planetary nebula; pretty bright ; very small ; very little ex- tended; barely resolvable’? No spectrum of this planetary nebula had been obtained in April. It was now recognized instantly, and without the smallest doubt, as “linear,”’ or at least apparently monochromatic, in the open field of the 806 Lieut. Herschel’s Observations of Southern Nebula. [Feb. 25, spectroscope. The position of the line has not been mea- sured. No. 1565. “A planetary nebula; pretty bright ; pretty small; extremely little extended ; barely resolvable.” ‘The ‘‘ linear”? cha- racter of the spectrum of this object has been already re- cognized; but it was again examined, as a test of the ad- vantage of removing the slit. It is a considerably larger and less bright object than No. 1225, and situated in a magnificent cluster of stellar points. In the open field of the spectroscope it appeared as a similar faint patch of light, in the midst of an infinity of streaks. Nothing could have been more conclusive as a test. No. 1185. ‘Remarkable; very bright; very Jarge; round; with tail; much brighter in middle, a star of 8-9 magnitude.’ A neighbour of the great nebula of Orion. Examined with the slit repeatedly. Ou the first occasion the spectrum was J described as ‘linear, but faintly seen; not certainly seen in presence of the central star. When the latter is put out, the spectrum becomes broadly continuous, with monochro- matic light across it.’ On the next it was, ‘‘ To-night I could trace no lines. There is ampie light, but it is not ‘linear,’ though certainly confined principally to the neigh- bourhood of the position of the ordinary lines. The spec- trum in any case occupies nearly the width of the field, and is not much less in length.’ On a third occasion I noted that I could ‘barely trace any limes, while there is a broad patch of spectral light on either side, which is certainly not due to the stellar centre.’ The trace of lines is confirmed on a fourth occasion. I think I am justified in saying that we have here a nebula of a class er description intermediate between those which show a clear continuous spectrum only, and those which show bright lines only. Not that the ap- parent character of these two extremes is necessarily absolute; it is far more probable that the non-appearance in either, of the distinguishing characteristic of the other, is relative only. Indeed there are nct wanting instances of nebule whose place im a series would be short of the latter extreme. For instance,— No. 826, supra, and No. 4964. ‘“‘Extremely remarkable; a planetary nebula; very bright; pretty small; round; blue.’ Presented ‘a continuous spectrum and a fourth line (besides the three usual ones) ; the first strongly suspected, the last less so.” The fourth line I find has been noted by Mr. Huggins. And the great nebula of Orion appears to be of the same order. I have examined this nebula repeatedly of late, because on the first occasion of 1869.] Lieut. Herschel’s Observations of Southern Nebula. 307 looking at No. 1185 I had appended a remark that “the principal nebula shows a great deal of continuous light on this side,”’ an observation which seemed to require confirmation. The following extracts from my note- book must speak for themselves :— No. 1179, The great Nebula of Orion. Oct. 25. ‘A fourth line, almost beyond question: measured twice with reference to principal line, 7°3—5°05=2°25, 7°6—5:'06=2°54, mean 2°4; con- tinuous spectrum suspected, but, owing to moonlight and low altitude, there was no conviction.’ Nov. 7. ‘“ Previous ob- : servation confirmed. ‘The fourth line is a fact. The dif- fused light, which also is certainly visible, to the extent of rendering the edges of the field visible beyond the immediate neighbourhood of the lines, can only be a continuous spec- trum.” Nov. 9. “ Fourth line, 7°9—5'1=2°8, very rough. T am satisfied that there is a continuous spectrum, though I am not cerfain it may not be dispersed stellar light.” Ditto, later: “ I have no longer any hesitation as to the continuous sueetenm. . Noy.10. “Fourth lime, 7-92, 7°88, 7-91, —5'09=2'81*. Continuous spectrum distinctly ending coincidently with the bright lines at the edge of the bright part of the nebula.” There is nothing very remarkable in the presence either of an additional line or of a continuous spectrum; but as this nebula has been examined very carefully in England without the detection of eitherT, it appeared neces- sary to put both beyond question; taken, too, in connexion with the very different character of its near neighbour, 1155, and with others in which _ the relative intensity of the two kinds of spectra varies in degree, it appears to break down, to a considerable extent, the barrier between ‘‘ gaseous”’ and “ solid’? nebulous matter, and to lead towards the inference that con- densation is in a more or less advanced stage in all nebule, and in the vast majority of cases, including all ‘ clusters,” has become complete. I am sorry to say that I shall be unable to prosecute these observations for some months, as my survey duties require my presence elsewhere. In the meanwhile I should be glad to learn whether the course I have been pursuing appears a desirable one to continue, now that so large a number of the southern nebule have been tested, or whether a reexamination would be preferred. I remain, dear Sir, yours truly, J. HERSCHEL, * Adopting D+2°-19 as the position of the principal line gives D+5:00 2, = fourth line. Kirchhoff’s 272-1 —D-+4-80 a 285°5=D+5:25 + [A faint continuous spectrum appears to have been seen with Lord Rosse’s great telescope. See a paper by Lord Oxmantown “On the Great Nebula in Orion,” Phi- losophical Transactions for 1868, p. 72.—G. G. 8.] | ; hence the fourth line is about midway between these. 308 _ Separation of the Isomerie Amylic Alcohols. (Feb. 25, II. “Note on the Separation of the Isomeric Amylic Alcohols formed by Fermentation.” By Ernest T. Caapman and Mites H. Smiru. Communicated by Prof. EH. W. Braytey. Received January 14, 1869. At present we are acquainted with two amylic alcohols formed by fer- mentation. They were discovered by Pasteur, who observed that different specimens of amylic alcohol caused a ray of polarized light to rotate to dif- ferent degrees. He succeeded in devising a separation of these alcohols, which consisted in converting them into sulphamylates of barium and re- crystallizing these salts. The one alcohol is without action on polarized light, and the other rotates it. This method of separation is beset with great practical difficulties, and has, we believe, only once been repeated, viz. by Mr. Pedler. He gives no detailed account of the separation, but gives some of the leading properties of the alcohols. He found that the rotating alcohol caused a ray of polarized light to rotate 17° with a column of 500 millims. of liquid. The following are some examples of the rotations effected by eleven dif- ferent samples of amylic alcohol in a column of 385 millims. For compa- rison with Pedler’s number, the observed numbers have been reduced in the second column to observations on 500 millims. :— Designation of Rotation observed on | Reduced to observations specimen. column of 385 millims. on 500 millims. ° So 1. aon 4:55 2: ah 4°81 3. 4 5-2 4, Be 4-81 De 4:7 6-11 6. 4 5:2 as 35 4°55 8. 2:7 3°51 9. 5 6°5 10. | 4 72 11, 3's | 4:94 Pedler’s rotating alcohol........s:0scommssesese essere 17-0 If Pedler’s number be absolutely correct, it follows that these specimens of amylic alcohol contained from 15:9 per cent. as a minimum, to 38-2 as a maximum of the rotating alcohol. ‘The boiling-points of the whole of the samples lay between 131°-5 and 133°. We have effected the separation of these alcohols more simply. soda, ~ potash, chloride of calcium, or, apparently, any salt easily soluble in amylic alcohol be dissolved in that alechol at the boiling-point, and the saturated solution be distilled, the non-rotating aleohol will be to a great extent re- tained and the rotating alcohol distils off. The substance which appears to lend itself most conveniently to this operation is caustic soda. Amylic alcohol is boiled with excess of caustic soda; when saturated, 1869.] Mr. Huggins on the Heat of the Stars. 309 the hot solution is decanted into a flask and distilled from an oil-bath, the temperature of which may be allowed to rise to 200°. The alcohol distils off at first readily, after a while with greater difficulty; finally the con- tents of the distilling flask solidify, and it becomes extremely difficult to drive over any more amylic alcohol. On now adding water to the contents of the flask and again distilling, amylic alcohol comes over of about half the rotating power of the aleohol employed. Ifthe power of rotation be very small, the reduction is considerably greater; thus, operating on an aleohol rotating 1°°3 on the 385 millims., by one operation we have re- duced it to 0°3.. By a sufficient number of repetitions of the process, it is possible to effect a separation of the aleohols, and very easy to obtain considerable quantities of the non-rotating alcohol quite pure. No valeri- anic acid is formed ; and the soda-solution remaining in the flask after the operation is completed is barely coloured. The separation of the aleohols may also be effected by dissolving metallic sodium in amylic alcohol, and distilling, &c., as above described, the re- sulting solution of amylate of soda in amylic alcohol. The process appears to present no point of advantage over that with caustic soda. We shall shortly publish a detailed account of differences in structure of these alcohols, together with a description of some of their principal deri- vatives. Til. “Note on the Heat of the Stars.” By Wriiiiam Huearns, F.R.S. Received February 18, 1869. In the summer of 1866 it occurred to me that the heat received on the earth from the stars might possibly be more easily detected than the solar heat reflected from the moon. Mr. Becker (of —— Elliott Brothers) prepared for me several thermopiles, and a very sensitive galvanometer. Towards the close of that year, and during the early part of 1867, I made numerous observations on the moon, omy on three or four fixed stars. I succeeded in obtaining trustworthy indications of stellar heat in the case of the stars Sirius, Pollux, and Regulas, though I was not able to make any quantitative estimate of their calorific power. J bad the intention of making these observations more complete, and of extending them to other stars. i have refrained hitherto from making them known; I find, however, that I cannot hope to take up these re- searches again for some months, and therefore venture to submit the ob- servations in their present incomplete form. An astatic galvanometer was used, over the upper needle of which a small concave mirror was fixed, by which the image of the flame of a lamp could be thrown upon a scale piaced at some distanee. Usually, however, I preferred to observe the needle directly by means of a lens so placed that the divisions on the card were magnified, and could be read by the ob- _ server when ata little distance from the instrument. The sensitiveness of the 310 Mr. Huggins on the Heat of the Stars. [Feb. 25, instrument was made as great as possible by a very careful adjustment from time to time of the magnetic power of the needles. The extreme delicacy of the instrument was found to be more permanently preserved when the needles were placed at right angles to the magnetic meridian during the time that the instrument was not in use. The great sensitiveness of this instrument was shown by the needles turning through 90° when two pieces of wire of different kinds of copper were held between the finger and thumb. For the stars, the images of which in the telescope are points of light, the thermopiles consisted of one or of two pairs of elements; a large pile, containing twenty-four pairs of elements, was also used for the moon. A. few of the later observations were made with a pile of which the ele- ments consist of alloys of bismuth and antimony. The thermopile was attached to a refractor of eight inches aperture. I considered that though some of the heat-rays would not be transmitted by the glass, yet the more uniform temperature of the air within the telescope, and some other circumstances, would make the difficulty of preserving the pile from extraneous influences less formidable than if a reflector were used. The pile a was placed within a tube of cardboard, 6; this was enclosed in a much larger tube formed of sheets of brown paper pasted over each other, c. The space between the two tubes was filled with cotton-wool. At about 5 inches in front of the surface of the pile, a glass plate (e) was placed for the purpose of intercepting any heat that might be radiated from the inside of the telescope. This giass plate was protected by a double tube of cardboard, the inner one of which (d@) was about half an inch in diameter. The back of the pile was protected in a similar way by a glass plate (¢). The small inner tube (2) beyond the plate was kept plugged with cotton- wool; this plug was removed when it was required to warm the back of the pile, which was done by allowing the heat radiated from a candle-flame to pass through the tube to the pile. The apparatus was kept at a distance of about 2 inches from the brass tube by which it was attached to the telescope by three pieces of wood (2), for the purpose of cutting off as much as possible any connexion by conduction with the tube of the tele- scope. The wires connecting the pile with the galvanometer, which had to be 1869.] Mr. Huggins on the Heat of the Stars. Sit placed at some distance to preserve it from the influence of the ironwork of the telescope, were covered with gutta percha, over which cotton-wool was placed, and the whole wrapped round with strips of brown paper. The binding-screws of the galvanometer were enclosed in a small cylinder of sheet gutta percha, and filled with cotton-wool. These precautions were necessary, as the approach of the hand to one of the binding-screws, or even the impact upon it of the cooler air entering the observatory, was sufficient to produce a deviation of the needle greater than was to be expected from the stars. The apparatus was fixed to the telescope so that the surface of the ther- mopile would be at the focal point of the object-glass. The apparatus was allowed to remain attached to the telescope for hours, or sometimes for days, the wires being in connexion with the galvanometer, until the heat had become uniformly distributed within the apparatus containing the pile, and the needle remained at zero, or was steadily deflected to the extent of a degree or two from zero. When observations were to be made, the shutter of the dome was opened, and the telescope, by means of the finder, was directed to a part of the sky near the star to be examined where there were no bright stars. In this state of things the needle was watched, and if in four or five minutes no deviation of the needle had taken place, then by means of the finder the telescope was moved the small distance necessary to bring the image of the star exactly upon the face of the pile, which could be ascertained by the position of the star as seen in the finder. The image of the star was kept upon the small pile by means of the clock-motion attached to the tele- scope. Theneedle was then watched during five minutes or longer ; almost always the needle began to move as soon as the image of the star fell upon it. The telescope was then moved, so as to direct it again to the sky near the star. Generally in one or two minutes the needle began to return towards its original position. In a similar manner twelve to twenty observations of the same star were made. These observations were repeated on other nights. The mean of a number of observations of Sirius, which did not differ greatly from each other, gives a deflection of the needle of 2°. The observations of Pollux 13°. No effect was produced on the needle by Castor. Regulus gave a deflection of 3°. In one observation Arcturus deflected the needle 3° in 15 minutes. The observations of the full moon were not accordant. On one night a sensible effect was shown by the needle; but at another time the indications of heat were excessively small, and not sufficiently uniform to be trust- worthy. it should be stated that several times anomalous indications were ob- served, which were not traced to the disturbing cause. The results are not strictly comparable, as it is not certain that the 312 Sir W. Thomson on the Fracture of Brittle. [Feb. 25, sensitiveness of the galvanometer was exactly the same in all the observa- tions, still it was probably not greatly different. Observations of the heat of the stars, if strictly comparable, might be of value, in connexion with the spectra of their light, to help us to determine the condition of the matter from which the light was emitted in different stars. I hope at a future time to resume this inguiry with a larger telescope, and to obtain some approximate value of the quantity of heat received at the earth from the brighter stars. IV. “On the Fracture of Brittle and Viscous Solids by ‘Shearmg.’ ” By Sir W. Tuomson, F.R.S. Received January 2, 1869. On recently visiting Mr. Kirkaldy’s testing works, t he Grove, South- wark, I was much struck with the appearances presented by some speci- mens of iron and steel round bars which had been broken by torsion. Some of them were broken right across, as nearly as may be in a plane perpendicular to the axis of the bar. On examining these I perceived that they had all yielded through a great degree to distortion before having broken. Itherefore looked for bars of hardened steel which had been tested similarly, and found many beautiful specimens in Mr. Kirkaldy’s ‘museum. ‘These, without exception, showed complicated surfaces of frac- ture, which were such as to demonstrate, as part of the whole effect in each case, a spiral fissure round the circumference of the cylinder at an angle of about 45° to the length. This is just what is to be expected when we consider that if A B DC (fig. |) represent an infinitesimal square on the surface of a round bar with its sides A C and B D parallel to the axis of the cylinder, before torsion, and ABD'C! the figure into which this square becomes distorted just before rupture, the diagonal A D has become elon- gated to the length A D’, and the diagonal B C has become contracted to the length BC’, and that therefore there must be maximum tension every- Pigs 1; CC’ Dp’ fs B JA. B where, across the spiral of which B C’ is an infinitely short portion. But the specimens are remarkable as showing in softer or more viscous solids a tendency to break parallel to the surfaces cf “shearing” AB, CD, rather than in surfaces inclined to these at an angle of 45°. Through the kindness of Mr, Kirkaldy, his specimens of both kinds are now exhibited : j . os th Binary Quartic or Quintic” aR Re go. BS PROCEEDINGS OF 5 “ 4 THE ROYAL SOCIETY. VOL, XVII. No. 110. mee > “8 a a + Se fee: ay; “ane 3. CONTENTS. Mere February 25, 1869. PAGE Y. Note by Professor CayLEY on his Memoir “ On the Conditions for the Ex- istence of Three Equal Roots, or of Two Pairs of Equal isis 8 of a a: Seeumry Quartic or Quintic” 2°. 0. we en . . 314835 March 4, 1869. 2 I. Appendix tothe Description of the Great Melbourne ee T. R. Rowinson, D.D., F.BS.,&c.. . . .. , : ; ~- O15 i I. Note on the Formation and Phenomena of Clouds. sid JOHN s Temas | = PMNS At oh dg a SL Roe ey ed vale «BEE 3 III. On the Behaviour of Thermometers ina Vacuum. By BEensaMiy Lace Ee SANG ea a a cag Gi wp apse 0 WA, wh, wi heh Oe ; TV. Account of the Building in progress of erection at Melbourne for the Great e Telescope. In a Letter addressed to the President of the Royal Society 23 by Mr. R. J. Exuzry, of the Observatory, Melbourne . . .. . . 328 March 11, 1869. I. Contributions to the Fossil Flora of North Greenland, being a Descrip- tion of the Plants collected by Mr. Edward Whymper ore the Sum- mer of 1867. By Prof. Oswanp Hzxr, of Zurich. . . no ane II. On the Specific Heat and other physical properties of yee Mixtures and Solutions. By A. Dupré, Ph.D., Lecturer on Chemistry at the Westminster Hospital and F.J.M.Pacze. . . . . ... . . 383 es March 18, 1869. | es I. Researches into the Chemical Constitution of Narcotine, and of its Pro- o ducts of Decomposition.—Part III. By A. Marrursssen, F.R.S., Lec- aids & turer on Chemistry in St. Bartholomew’s Hospital. . . . . . . , 387. : i we ae “s For continuation of Contents see the 4th page of Wrapper. 1869. | and Viscous Solids by “ Shearing.” 313 to the Royal Society. On a smaller scale I have made experiments on round bars of brittle sealing-wax, hardened steel, similar steel tempered to various degrees of softness, brass, copper, lead. Sealing-wax and hard steel bars exhibited the spiral fracture. All the other bars, without exception, broke as Mr. Kirkaldy’s soft steel bars, right across, in a plane perpendicular to the axis of the bar. These expe- riments were conducted by Mr. Walter Deed and Mr. Adam Logan in the Physical Laboratory of the University of Glasgow ; and specimens of the bars exhibiting the two kinds of fracture are sent to the Royal Society along with this statement. I also send photographs exhibiting the spiral fracture of a hard steel cylinder, and the “shearing” fracture of a lead cylinder by torsion. These experiments demonstrate that continued “ shearing” parallel to one set of planes, of a viscous solid, developes in it a tendency to break more easily parallel to these planes than in other directions, or that a viscous solid, at first isotropic, acquires ‘‘ cleavage-planes”’ parallel to the planes of shearing. Thus, if C D and AB (fig. 2) represent in section two sides of a cube of a viscous solid, and if, by “‘shearing”’ parallel to these planes, CD be brought to the position C’ D’, relatively to A B supposed to remain at rest, and if this process be continued until the material breaks, it breaks parallel to AB and C' D!. The appearances presented by the specimens in Mr. Kirkaldy’s museum. attracted my attention by their bearing on an old controversy regarding Forbes’s theory of glaciers. Forbes had maintained that the continued shearing motion which his observations had proved in glaciers, must tend to tear them by fissures parallel to the surfaces of “shearing.” ‘The correctness of this view for a viscous solid mass, such as snow becoming kneaded into a glacier, or the substance of a formed glacier as it works its way down a valley, or a mass of débris of glacier-ice, reforming as a glacier after disintegration by an obstacle, seems strongly confirmed by the experiments on the softer metals described above. Hopkins had argued against this view, that, according to the theory of elastic solids, as stated above, and represented by the first diagram, the fracture ought to be at an angle of 45° to the surfaces of “shearing.” There can be no doubt of the truth of Hopkins’s principle for an isotropic elastic solid, so brittle as to break by shearing before it has become distorted through more than a very small angle; and it is illustrated in the experiments on brittle sealig-wax and hardened steel which I have described. The various specimens of fractured elastic solids now exhibited to the Society may be looked upon with some interest, if only as illustrating the correctness of each of the two seemingly discrepant propositions of those two distin- guished men. VOL. XVIT. OPN 314 Prof. Cayley on Equal Roots of a Binary Quartic. [Feb. 25, V. Note by Professor Caytey on his Memoir “ On the Conditions for the Existence of Three Equal Roots, or of Two Pairs of Equal Roots, of a Binary Quartic or Quintic.” Received February 20, 1869.5 — The title is a misnomer; I have in fact, in regard to the quintic, consi- dered not (as according to the title and introductory paragraph I should have done) the twofold relations belonging to the root-systems 311 and 221 respectively, but the threefold relations belonging to the root-systems 41 and 32 respectively. The word “quadric,” p. 582, line 1, should be read “cubic.” The proper title is, “On the Conditions for the Existence of certain Systems of Equal Roots of a Binary Quartic or Quintic.” March 4, 1869. Lieut.-General SABINE, President, in the Chair. In accordance with the Statutes, the names of the Candidates for elec- tion into the Society were read as follows :— Sir Samuel White Baker, M.A. John Robinson M‘Clean, C.E. _ William Baker, C.E. | George Matthey. John J. Bigsby, M.D. | St. George Mivart. Francis T. Buckland, M.A. | Prof. Alfred Newton, M.A. George William Callender, F.R.C.S. | Captain Sherard Osborn, R.N., C.B. Charles Chambers. Oliver Pemberton. Walter Dickson, M.D. | Charles Bland Radcliffe, M.D. Henry Dircks. | Wilham Henry Ransom, M.D. Sir George Floyd Duckett, Bart. | Theophilus Redwood, Ph.D. William Esson, M.A. _ John Russell Reynolds, M.D. Alexander Fleming, M.D. _Vice-Admiral Sir Robert Spencer Ro- Prof. George Carey Foster, B.A. | binson, K.C.B. Peter Le Neve Foster, M.A. | Major James Francis Tennant, R.E. William Froude, M.A., C.E. | Edward Thomas. Edward Headlam Greenhow, M.D. | Prof. Wyville Thomson, LL.D. William Withey Gull, M.D. | Col. Henry Edward Landor Thuillier, G. B. Halford, M.D. | o5ae ee Townshend Monckton Hall. | Cromwell Fleetwood Varley, C.E. Edmund Thomas Higgins, M.R.C.S. | Augustus Voelcker, Ph.D. Charles Horne. Edward Walker, M.A. James Jago, M.D. George Charles Wallich; M.D. George Johnson, M.D. Henry Wilde. J. Norman Lockyer. { Samuel Wilks, M.D. James Atkinson Longridge, C.E. 1869. ] Dr. Robinson on the Great Melbourne Telescope. 315 I. “Appendix to the Description of the Great Melbourne Telescope.” ByT.R. Rorrson, D.D.,F.R.S.,&c. Received February 10,1869. (Abstract.) Since this paper was read the author has made several observations of the quantity of light transmitted by object-glasses, and determined the index of absorption in various specimens of glass. The results of some of these are in accordance with the opinion expressed in the paper; but others present a difference which is very satisfactory as indicating a sur- prising progress in the manufacture of optical glass. The observations were made by means of Zollner’s photometer. The following results were obtained for the intensity of the light trans- mitted by a variety of object-glasses :— Description. Focus. Intensity. in. in. @) Priple Object-elass .................-s000.- 2°75 48 0:5497 0. DL 2 ee 3°80 63 0:5962 3. 12) 1 SESE ee 3°25 48 0:6567 [2 LL) URE 6°50 96 0-6772 2 1 PTS 2h ee ee 5°50 58 0°7928 f. Double, inner surface cemented......... 5-00 0:8739 Me MGHINe, GEMEDEC — .........ccseceevenesees 12-00 224 0-8408 | © LA nfo Se ae 3:20 0°7393 Of the above, a belongs to the Armagh Observatory ; it is by one of the Dollonds, older than 1790, and is probably one of their first attempts at a triple combination. @ is the original object-glass of the Armagh circle ; it was made by Tulley about 1828; the crown is greenish, and is supposed to be English ; the flint is believed to have been from Daguet. e¢ was made for the author by Tulley in 1838; its glass is French, the crown is greenish. d is by Cauchoix; the crown is greenish, and has probably a high », but its mean thickness is only 0°39. eis by Messrs. Cooke; the glass is Chance’s. fis by Grubb, the glass Chance’s: the very high trans- mission of this lens is in part due to the cementing of the adjacent sur- faces, which, while it makes more difficult the correction of spherical aberration, removes almost entirely the reflection at a surface of crown and one of flint: the factor for this =0°9036; and if the I be multiplied by this, we obtain 0°7806, nearly that of e, the difference being due to the reflection at the film of cement. g is also by Grubb, and cemented ; the glass is by Chance. A is by Fraunhofer. On examining this Table the progressive increase in the light of the object-glasses :s evident. The first two, which may be considered good specimens of the early achromatics, have less illuminating-power than the Herschelian reflector. A great advance was made .by Guinand and those who followed in his steps; and a still greater one by Chance, whose glass is nearly perfect as to colour and transparency. The same inference follows from the author’s measure of the index of 2Aa2 316 Dr. Robinson on the Great Melbourae Telescope. [Mar. 4, absorption, n. The specimens examined were, with two exceptions, prisms ; and this form is very convenient. If a ray is incident on an isosceles prism parallel to its base, it emerges parallel to itself after undergoing total internal reflection at the base; and the length of the path of the light within the glass, and the loss by the two reflections, are easily calculated from the known angle and refractive index. ‘The mean index used in the calculation was that of the line E. The results are given in the following Table, in which are introduced those given in the paper that they may be referred to at once; and there is added to them one found in Bouguer’s ‘Traité d'Optique,’ which seems trustworthy. Description. N 1. Prism, originally Captain Kater’s ...... 01829 2. French plate; Mr. Grubb ......-. ee gues: 3. London plate, Mr. Grubb ............ 0°2140 A. Two of same, Mr. Grubb 773225) e 0°1446 5. Prism, Mr. Grubb .. 2... e 2 ee 6. Bouewers classe. cele oe asics see 0-1895 7, Gassiot’s prisms 22). 25s. chee 0°6209 8. Prism by Dubosq, flint ~.. 0.0. >... eee 9, Prism by Merz, tint. 2... .2.\)-= eee 0°1089 10: Prism by Merz, crowis\ Cylinder, of alimt see sace eue 0:0090 No. 1 was shown to the author in 1830 by Captain Kater, as the chef- @ euvre of the Glass-Committee ; he used it as the small speculum of his Newtonian. Afterwards it came into the possession of the late Lord Rosse, who made the above measures with Bunsen’s photometer in 1848, It is English plate, greenish. Nos. 2, 3, 4, 5 were measured by Mr. Grubb in 1857. No. 5 was a prism of 90°. He does not remember its history ; but evidently it was of Chance’s glass. — ~ No. 6 is described by Bouguer as “ glace,’”’ 3 Paris inches thick. It was probably that of St. Gobain, which has probably not varied in compo- sition, and zés x has been used in the computation. No. 7 consists of two prisms of 60°, which Mr. Gassiot, with his wonted. . kindness, intrusted to the author for some inquiries about the improvement of the spectroscope. They are by Merz, of glass which seems nearly iden- tical with Faraday’s dense glass, having a specific gravity of 5:1, and a mean p=1'7664, It is very pellucid, but, like its prototype, has a yellowish tinge, probably given by the large proportion of lead. As Merz does not polish the base or ends of his prisms, the usual method could not be employed; but the prisms were put together with the angles opposed, and a drop of olive-oil between, and the reflections allowed for. The great 1869. | On the Formation and Phenomena of Ciouds. 317 absorption is remarkable, and apparently cannot be explained by the colour of the glass. No. 8 is of 60°; its » for E=1:620. It is free from colour, and an evident improvement on the earlier ones. No. 9, a prism of 90°, was given to the author by Dr. Lloyd fora ical mirror in the Newtonian form of the Armagh 15-inch reflector ; its p for E=1°'6188. No. 10, of 90°, was obtained by the late Lord Rosse to be similarly used in his 3-feet Newtonian; its wp for E=1°5321. No. 11, of 60°, obtained at Munich in 1837. For these measures the ends were polished flat ; its u for E=1°'6405. These three show considerable progress, and an object-glass made of such materials would have a great power of transmission, though much behind the following. No. 12 is of 90°. Its glass is from Chance; its » for E=1°6216. No. 13 is acylinder 2°2 inches in diameter, and 4°3 long, which Mr. Grubb obtained from Messrs. Chance for these measures; its » for E=1:5200. No. 14 is a cylinder got at the same time, 2°1 inches in diameter and 4°4 long; its » for K=1°6126; the ends of both are polished flat, and they are of wonderful transparency. If, as there is good ground for hoping, Messrs. Chance shall succeed in manufacturing large disks of the same perfection as these two cylinders, the author’s comparison of the achromatic and the reflector must be considerably modified. Assuming n="'02, he calculates that the aperture of an achromatic, of | _ focal length equal to 18 times the aperture, equivalent to a 4-feet Newto- nian, is 35°435 inches. This aperture would be diminished if the process of cementing were found applicable to lenses of such magnitude. The author concludes with suggesting that, as very slight variations in the manufacture of glass seem to make great changes in its absorptive power, it would be prudent to examine the value of in the disks intended for lenses of any importance. This could be done by polishing a couple of facets on their edges, and need not involve the sacrifice of many minutes. II. “ Note on the Formation and Phenomena of Clouds.” By Joun Tynpaut, LL.D., F.R.S. Received January 25, 1869. It is well known that when a receiver filled with ordinary undried air is exhausted, a cloudiness, due to the precipitation of the aqueous vapour diffused in the air, is produced by the first few strokes of the pump. It is, as might be expected, possible to produce clouds in this way with the vapours of other liquids than water. In the course of the experiments on the chemical action of light which have been already communicated in abstract to the Royal Society, I had frequent occasion to observe the precipitation of such clouds in the experi- mental tubes employed; indeed several days at a time have been devoted 318 On the Formation and Phenomena of Clouds. [Mar. 4, solely to the generation and examination of clouds formed by the sudden dilatation of the air in the experimental tubes. The clouds were generated in two ways: one mode consisted in opening the passage between the filled experimental tube and the air-pump, and then simply dilating the air by working the pump. In the other, the experimental tube was connected with a vessel of suitable size, the passage between which and the experimental tube could be closed by a stopcock. This vessel was first exhausted ; on turning the cock the air rushed from the experimental tube into the vessel, the precipitation of a cloud within the tube being a consequence of the transfer. Instead of a special vessel, the cylinders of the air-pump itself were usually employed for this purpose. It was found possible, by shutting off the residue of air and vapour after each act of precipitation, and again exhausting the cylinders of the pump, to obtain with some substances, and without refilling the experimental tube, fifteen or twenty clouds in succession. The clouds thus precipitated differed from each other in luminous energy, some shedding forth a mild white light, others flashing out with sudden and surprising brilliancy. This difference of action is, of course, to be referred to the different reflective energies of the particles of the clouds, which were produced by substances of very different refractive indices. Different clouds, moreover, possess very different degrees of stability ; some melt away rapidly, while others linger for minutes in the experi- mental tube, resting upon its bottom as they dissolve like a heap of snow. The particles of other clouds are trailed through the experimental tube as if they were moving through a viscous medium. Nothing can exceed the splendour of the diffraction-phenomena exhibited - by some of these clouds; the colours are best seen by looking along the experimental tube from a point above it, the face being turned towards the source of illumination. The differential motions mtroduced by friction against the interior surface of the tube often cause the colours to arrange themselves in distinct layers. The difference in texture exhibited by different clouds caused me to look a little more closely than I had previously done into the mechanism of cloud-formation. A certain expansion is necessary to brmg down the cloud; the moment before precipitation the mass of cooling air and vapour may be regarded as divided into a number of polyhedra, the particles along the bounding surfaces of which move in opposite directions when precipita-. tion actually sets in. Every cloud-particle has consumed a polyhedron of vapour in its formation; and it is manifest that the size of the particle must depend, not only on the size of the vapour polyhedron, but also on the relation of the density of the vapour to that of its liquid. If the vapour were light, and the liquid heavy, other things being equal, the cloud-particle would be smaller than if the vapour were heavy and the liquid light. There would evidently be more shrinkage in the one case than in the other: these considerations were found valid througehut the 1869.] On the Behaviour of Thermometers in a Vacuum. 519 experiments ; the case of toluol may be taken as representative of a great number of others. The specific gravity of this liquid is 0°85, that of water being unity; the specific gravity of its vapour is 3°26, that of aqueous vapour being 0°6. Now, as the size of the cloud-particle is _ directly proportional to the specific gravity of the vapour, and inversely proportional to the specific gravity of the liquid, an easy calculation proves that, assuming the size of the vapour polyhedra in both cases to be the same, the size of the particle of toluol cloud must be more than six times that of the particle of aqueous cloud. It is probably impossible to test this question with numerical accuracy ; but the comparative coarseness of the toluol cloud is strikingly manifest to the naked eye. The case is, as I have said, representative. In fact, aqueous vapour is without a parallel in these particulars; it is not only the lightest of all vapours, in the common acceptation of that term, but the lightest of all gases except hydrogenand ammonia. To this circumstance the soft and tender beauty of the clouds of our atmosphere is mainly to be ascribed. The sphericity of the cloud-particles may be immediately inferred from their deportment under the luminous beams. The light which they shed when spherical is continuous: but clouds may also be precipitated in solid flakes ; and then the incessant sparkling of the cloud shows that its particles are plates, andnot spheres. Some portions of the same cloud may be com- posed of spherical particles, others of flakes, the difference being at once manifested through the calmness of the one portion of the cloud, and the uneasiness of the other. The sparkling of such flakes reminded me of the plates of mica in the River Rhone at its entrance into the lake of Geneva, when shone upon by a strong sun. III. “On the Behaviour of Thermometers in a Vacuum.” By Bengamin Lonwy, F.R.A.S. Communicated by Prof. Stoxzs, Sec. B.S. Received January 8, 1869. 1. In the year 1828 General Sabine made a series of pendulum-experi- ments* in a receiver from which the air was exhausted, and observed inci- dentally that on the pump being worked the thermometer in the receiver fell about 7-tenths of a degree of Fahrenheit’s scale when the pressure was reduced to 7 inches, while the converse took place when the air was re- admitted. He ascribed this effect to the removal of the pressure of the atmosphere on the exterior of the bulb and tube of the thermometer; and to ascertain whether this explanation was correct the following experiment was made :—A thermometer being immersed in pounded ice and placed on the brass plate of an air-pump, the mercury coincided exactly with the division of 32°; it was then covered with a receiver, and the air with- drawn; the thermometer fell as the pump was worked, and when the * Published in the Philosophical Transactions, 1829, part 1. 820 Mr. B. Loewy on the Behaviour [ Mar. 4. gauge indicated a pressure of half an inch the mercury stood at 31°25; on readmitting the air it rose again to 32°. The experiment was repeated, with be oicele similar results; and a correction was ultimately adopted, corresponding to the varying pressures in the receiver, in order to reduce the pendulum-experiments to the true temperature at which they were made. 2. It was generally admitted that this apparent fall of the mercury arose from a change in the capacity of the interior of the thermometer; and the physicists, especially the pendulum-experimenters who followed in General Sabine’s steps, never neglected this correction when their object was to discuss the results of experiments made in a vacuum, and in the reduction of which the temperature entered as an element. In the pendulum- experiments which were made at the Kew Observatory in connexion with the Great Trigonometrical Survey of India (vide Pro- ceedings of the Royal Society, No. 78, 1865), the thermometers used were, before the discussion of the observations, sabe to independent experi- ments, to determine their ‘‘vacuum-correction,”’ which was found nearly the same for each of the two thermometers employed, viz. 0°-43. In these experiments the two thermometers were suspended, together with another (the latter enclosed in a sealed glass tube, and hence surrounded by air), in the receiver, and their readings taken some time after the exhaustion, sufficient to equalize its He upon all three thermometers, bearing in mind the fact that the thermometer in the glass case would take a some- what longer time for showing changes of temperature than those without such an enclosure. The arrangement of the experiments was precisely the same as that originally adopted by General Sabine ; and the precaution taken as regards the time of reading the different thermometers left no doubt on my mind that the observed difference of 0°43, by which amount the thermometers exposed to the effect of exhaustion were in every experi- ment found to read Jess than that enclosed in a glass tube, gaye the required vacuum-correction in this particular case. It is also clear that in this method of carrying on the experiment the refrigeration due to the work done by the expanding air during the process of exhaustion will affect all thermometers alike, and that consequently the residual difference must be due to other causes. 3. One point, however, was overlooked in these experiments, viz. to wait a number of hours and then to take another series of readings, in order to determine whether the effect of the removal of the atmosphere upon the capacity of a thermometer was only transient or permanent. Professor Oscar Meyer, in Breslau, was the first to call attention* to this question. While making some experiments on the internal friction of gases, he found that the primary effect of the exhaustion upon a ther- mometer was quite in accordance with the observations of General Sabine, but that after some time (for the thermometer employed by him, after about half an hour) this effect entirely disappeared. Captain Basevi, who * Vide Poggendorff’s ‘ Annalen,’ vol. exxy. p. 411. 1869. | of Thermometers in a Vacuum. 821 has charge of the pendulum-experiments in India, communicated to me that the results of some experiments made by him strengthened Professor Meyer’s conclusion, and caused him grave doubts as to the necessity of applying the yvacuum-correction in pendulum-experiments, one swing often - lasting in such experiments from five to eight hours. 4. It appeared to me that there were various sources of error in the experiments previously made. The only experiments which seem con- clusive are those made by General Sabine with thermometers placed in ice ; but we are not informed in the account of these experiments how long each of them lasted, probably because there was no reason to regard the element of time as of importance. In the experiments made by comparing the thermometers with one enclosed in a glass tube and surrounded by air, it is obvious that the ther- mometers under comparison are throughout. under different circumstances as regards their sensitiveness, and that this difficulty cannot be entirely overcome by allowing some time for the equalization of the original effect of the exhaustion. Again, it is questionable whether the glass tube which surrounds the thermometer which must be considered the standard of comparison has not, during the process of being closed up before the blow- pipe, been so heated that the remaining air, instead of representing the pressure of a whole atmosphere, is really of a much less density. Further, there is the question of time, raised by Professor Meyer and Captain Basevi. In Professor Meyer’s experiments one thermometer was placed within the receiver, and another suspended outside, on the exterior of the receiver itself. He found that exhaustion lowered the reading of the former by from one-half to one degree of the centesimal scale, but that after about half an hour both thermometers agreed again: the readmission of air caused the thermometer in the receiver to rise by the same quantity by which it had previously fallen; but after the lapse of some time the two thermometers read again alike. This lowering of the mercury on evacu- ation, and rising on readmission of the air, ceased almost entirely when the thermometer was introduced into the receiver immersed in dehydrated glycerine. From these observations Professor Meyer concludes that it is solely the mechanical labour of the air during expansion or compression which produces these fluctuations, and that they do not depend on the vary- ing pressure upon the bulb of the thermometer. This conclusion may be correct as far as the particular thermometer is concerned which Professor Meyer employed, for it will be seen in the sequel that certain thermometers really behave exceptionally ; but it will also appear on examining the ex- periments given in Table IJ. that two thermometers, under precisely the same external circumstances, and in close juxtaposition, often differ in their readings by half a degree of Fahrenheit’s scale, and even more, with- out any assignable cause. We may obviously infer from this that two thermometers, arranged as in Professor Meyer’s experiments, are not strictly comparable when small differences of temperature have to be ascertained. 822 | Mr. B. Loewy on the Behaviour [ Mar. 4, 5. In order to decide the question of the “ vacuum-correction ”’ by avoiding the above indicated sources of error, I had three A Na pairs of thermometers made, each pair of equal shape | f and size as regards bulb and tube, but these pairs differing | in this respect among themselves. These six thermometers were, in the manner which is shown in the annexed figure for one pair of them, enclosed in glass cases, which ter- aI minated in narrow tubes of about 5 inches in length. One case with its thermometer was left open at the top (A), while the other (A’) with the corresponding thermometer was closed by a rapid puff of the blowpipe, without the possibility of heating the enclosed air and thus diminishing the pressure upon the enclosed thermometer. There were thus subjected to experiment six thermo- meters, of three different forms, as may be seen from the following description of them :— (1) A* (No. 6700), Spherical bulb, diameter of bulb 3 inch, length of stem 13 inches, enclosed in open =) =o == Se ae eee 7 ESS REE CRO UE OTE ETE — case. (2) A’ (No. 6701), Spherical bulb, diameter of bulb 3 inch, length of stem 13 inches, enclosed in shué case. (3) B (No. 6703), Cylindrical bulb, 145 inch long, | =35 inch wide, length of stem 15 inches, enclosed in | open case. - Lw (4) B’ (No. 6702), Cylindrical bulb, 14, inch long, | ©) oy =25 inch wide, length of stem 15 inches, enclosed in i | | shut case. . Ka) Ld (5) C (No. 6704), Spherical bulb, diameter of bulb 3 inch, length of stem 27 inches, enclosed in open case. (6) C' (No. 6982), Spherical bulb, diameter of bulb 3 inch, length of stem 27 inches, enclosed in shut case. The thermometers A, A’, B, B’ represent the usual form and size of these instruments, while those marked C, C’ are unusually large, and would hardly be employed except for special purposes. ‘The former had each degree divided into five parts, hence reading by estimation to =, of a = STR ERATE Aa TES EA ETNA > Rane eee Le rt i ft + ! war & degree, while the latter had each degree divided into ten parts, each of which occupied about the space of one degree in the common form; +4, of a degree of Fahrenheit’s scale could thus be read with the utmost accuracy. 6. The thermometers and the receiver employed in these observations were made by Mr. L. Casella, who took the greatest interest in the purpose of the experiments, and consequently tock especial care to make the instruments as perfect as possible. * These letters are the same as those used in the succeeding Table of Experiments to designate the different thermometers. 1869.] of Thermometers in a Vacuum. 823 The thermometers were tested before putting them into the glass cases by comparing them from three to three degrees with the Kew standard, taking a great number of readings by two independent observers for this purpose. From this comparison and by interpolation, the following Table of corrections for every degree over the range of temperature during the experiments was constructed. It will not only prove that the utmost precaution was taken to ensure the experiments against errors inherent in the instruments employed, but will also show the excellency of the ther- mometers and the degree of accuracy now obtained by eminent makers in _the construction of these instruments. Thermo- meters. |40 No. No. No: No. No. No. | Tasxe I. Corrections to be applied to the Readings of the Thermometers. N.B. The corrections are in all cases subtractive. 44 °142°143°144°145°146°147°148°149°150°/51°152°153° 54° ° ° O° ° fe) Lo) oO ° ie) ie) ie) ° fo) ce) ie) ie) O° ie) fo) fo) 6700./E2 |°42 \°12 [02 [11 |°13 [16 [1g [28 [17 26 [16 [17 27 [716 [16 [47 [19 [20 [17 | 6702.|°13 |°13 13/12 [12 15 |-19 [22 [2d [1g [18/07 [TS [14 [15 [15 |°17 [1g |"20 [19 |- G7O20)83 53 PI [09 |'08 jog 10 [NT |X [rd Ly [Ly (ry [re [rd 12 (13 rg rs 23 re 6703.|"09 |"09 |"I0 |"12 |°13 |°16 |°18 [20 [1g |18 [18 |°16 |°13 [10 |°08 |'07 |°08 |'09 |"10 |-r0 "09 G7OF- en) Og (10/10 {TF [13 |°16 \"19 [17 [ES [13 [13 [12 | 12 |r (12 |r2 [12 G982./°24 |°24. |-23 |°22 [20 |°22 [24 |°25 [25 [25 |'25 |°25 |°26 [27 |°28 [28 |Z0 [32 7. The thermometers were placed in the receiver, arranged close to each other on a board fixed to a support, the four smaller thermometers on one side, the two larger ones on the other; and the manner of proceeding with each experiment was the following. Hetire pumping, all the thermometers were twice read in rapid succession; after exhausting the receiver to be- tween one and two inches of pressure (a manipulation which generally lasted about ten minutes), two or more readings were again taken to deter- mine the ‘“‘ immediate effect of exhaustion” on each thermometer. After an interval of several hours the thermometers were supposed to have assumed the surrounding temperature, and two readings were now taken for the “‘residual effect of exhaustion.” The whole apparatus was then left undisturbed for nearly a whole day, when another set of readings were taken, and the apparatus was refilled. After readmission of the air the temperature shown by the instruments was immediately 1 registered to find the heating-effect upon them of the inrush of air. The readings, both for the comparison of the instruments and during the experiments themselves, were taken alternately by Mr. Thomas Baker, Assistant at the Kew Observatory, and myself. By the kind permission of Mr. Balfour Stewart, Superintendent of the Kew Observatory, I was enabled to avail myself of the obliging assistance of Mr. Baker and his great experience in thermomeitric experiments. I take this opportunity of expressing to both these gentlemen my gratitude for the aid given to me in the pursuit of this inquiry. 24: Mr. B. Loewy on the Behaviour [ Mar. 4, 8. In the following Table I give the results of six experiments which were made for my purpose, leaving their discussion for the next para- graphs. A number of experiments made previously to these here given, in the large Kew receiver, had to be rejected ; for the apparatus has leaked latterly to a considerable amount during a day, causing a feeble but con- Tasxe II. Experiments for determining the Vacuum-correction of Thermometers. : SH Dn =) nm ay n c+ D ne Biol Ee 2 EE a. }9 (82 ) 8 |8 135) engl a oFfisS WES aate hate aS oles Be hem al Peta | se sae isd 18 2iS$2 cia’ la silos SF ja slo ar laslos Sr la sige. Ho lg B/S eg A OOS 2H a oO 8 D5 “1 01,0 & 28 j= O12 9. 5, (3 8 Bat est OO ee 6 [90.2 me Se eS ; 2 10.2; aS Ss Sioa we i S-s/S-g] » al ee ge [S'S] 2 ool a S [Se] Be ae |eele «f S |HgiS-8 3 SSC BS Sia Bs] OF 1S Ola Bs] OF |S Slags| Ot 13919 6 20 Se Sin 2b ROS So ma a2 sae nm He Sarl mH P| mm: 6 /BSic agg Sis "Fos! 8 |e "|Feos| £8 |S “\Zos| ds [8 "1s868 ° Sip eC2kKkis gps |e] se ig eee] ss 16 SSeo| se if =z B-s 6 AFIS #10 8 Bia Bepaaied bet py Sor ae ae ara? ae py S Q Zi iS) = — ey |. 4 = = | A in, am | ti, | Sn | : A’ 52:40 | 50°56 | 3507) 3°15 50°64 3°16 18 37 | S247 | 359) ee : oe: A 53 4 UNE | ay aga a iter) 6k x BTi02| eee oe pars Wes -- 3 53°03 IB e256) O77 || 50°45 | 51°39 . ee | 53°08 Bi 52,001 ear 5 Gel ae = 50°92 | | 51°71 o. oe) A 36 2709 COMED EGO: Lies 50°63 | ieee we ++ a ae) C5048.) 850744) oc 50°57 | GI 32 2: | s= | 52°33 eel . | TT.| A | 53°63} 51°77 | 2°14) 3 40 | 53°45] 2°20) 20 15| 4897/2747] .«- | ~ | 50°55 A’ | 53°34] 52°64 ve 1:53°85 [i- | 49°45 Jos - | 50°07 BS hak 74 502 53°26] «5 | 49°09 | -- = 211 50°83 BY | 53°24] 52°45 53°74) a 49°45 | .+ + | 50°31 C | 52°94) 51°42 58 35H 49°21 “ - | 50°43 C52 Go| 51-32 | 53°28 49°27| .. Si =e 49°95 TG, || AL | 50°94: |) 49715]. 1°63| 220 | 51°37 | 1-741 20 5) a7 aol e golemee a | 43°74 A’ | 50°93! 49°96] .. aie Bree) a -- | 47°40 ais 5 48-02 | S| 50778 |49:13'| 9 : 51°10 | | 46°97 Fs .. | 48°78 B’ | 50°79] 49°84] . 51°58 | 47°32 ae geri) 40°20 C | 50°67} 49°08 51°10 46°93 AG lie | 48°23 C’ | 50°25} 48°94 5104 | 46°96 ig | 2: | 47°64 l IV.| A | 49°53} 47°78 | 1°72) 3 10 | 49°92 | 1°80, 19 55| 51°25] 2°16 |: | 52°72 AT A492 01040129) 0 ae GO 2) esa Mare 51°54 eho" LO B | 48°99| 47°42) .. 49°71 51°09 -» | 52°86 B’ | 49°08 | 48°11 501s 51°47 HES "29 C 48°80 | 47°28 49°65 50°93 eh 25225 C’ | 48:26 | 47°03 49°59 | 50°93 | «+ | 51°61 V.| A | 55°03| 52°64uigt-16) 0 35 | 52°68 | 1°16) 18 15| 47°55 | 1°43 : «+ | 48°96 A’. | 54°86| 53°60m .. a4 53°20 ares pal (A SROST ERE . «+ | 48°56 B | 54°63) 52°68 a) 9 53770 oa 47°86 : 49°55 BY | 54°77 | 53°55 53°16 | 48°16 43°84 C | 54°58) 52°72 52°90 47°73 | 48°88 C’ | 54°09) 52°61 52°32 47°93 | 48°48 NG. GAN 56°34" 28:24 lo-otlvor2 5 nlaan323 “org! 20 0} 42°40 I'TO 24 50} 46°88 | 1°44) 48°52 AY SOCTGH J49°20))\\as 49°72 42°90 A AAA) 2 | 47°80 B | 50°04} 43°37 49°12 42°48 46°70 48°78 B’ | so'12| 49°10 49°45 42°94 47°06 48°00 C’ | 49°87) 48:19 49°0 42°60 46°65 47°84 | OC” | 49°40} 48-11 48°89 42°59 46°48 47°23 1869.] of Thermometers in a Vacuum. 525 stant rush of air, which. vitiated the ultimate results. Only those expe- riments are here given and discussed which were made in a smaller receiver expressly constructed for my purposes by Mr. Casella. In this Table the corrected means of the individual observations are given, while a larger Table, embodying also the latter, has been deposited with the Royal Society for future reference. It is seen from this larger Table that the average amount of error in these observations is not more than about two-hundredths of a degree of Fahrenheit. In a very few cases only, where the thermal effect was not quite completed when the readings were taken, errors of about one-tenth of a degree occur; care, however, was taken in these solitary cases to ascertain the completion of the effect by the more close agreement of a new series of observations. 9. A glance at the preceding Table will at once show that the immediate effect of exhaustion is a fall, that of readmission of air a rise of all ther- mometers, and that there is at once a difference in the behaviour between the thermometers A’, B’, C’, which are still surrounded by air, and A, B, C, which are in a vacuum. But this difference is also observable to a certain extent when the receiver is refilled, and when, as regards external pressure, all thermometers are in the same condition; hence this zmmediate difference must have another cause than the supposed change in the capacity of the instruments; at any rate if a permanent difference is found afterwards in consequence of such a change, it must be included in that difference which shows itself immediately. The cause of the latter is obvious. The ther- mometers in closed cases lag a little behind when they are affected by such sudden fluctuations as those produced in these experiments, and they assume, as the experiments have shown, the normal temperature a little later. The following Table gives the immediate fall and rise of all thermometers, observed respectively on evacuating and refilling the receiver, and the im- mediate mean difference between the differently placed thermometers. It exhibits a very close agreement between the effect of exhaustion and that of readmission of air ; but its more important practical purpose is to show that an error of nearly two degrees of Fahrenheit is made in thermometer- readings in a receiver immediately after exhaustion or readmission of air. Immediate effect of exhausting the Receiver. Thermometers falling. (es a ae Se ee A, AY. By BY, @ C. (Oar ° ° 12) ° ° ° Pmperanent + Est. es cies 1°84. o°91 1°97 1°05 161 1°34. FA Bk Kes Sats ot 1°86 0°70 roe E 0°79 E52 1°18 F %. EES > oe, BRO 0°97 1°65 0°95 1°59 Tee Pi EVES betes eae o'91 Eo7 0°97 1°52 ¥23 3 ve 2°39 Vi7 1°95 Ea 1°86 1°48 = VI 2°10 0°96 1°67 ‘02 1°68 E29 OR oso 6 oe ayia, Wea way ae 1°95 0°94. 1°69 1°00 1°63 1°30 —_~---—-——"’ ——-~-——’/ W—_- >_> Differences immediately } @nseryable .,.i.5+. | 326 Mr. B. Loewy on the Behaviour _- [Mar4, Immediate effect of refilling the Recciver. Thermometers rising. cl A B. Be C. i. : ° ° ° ° °o ° Bxpermmaent, Sle iis pei.) a c0r7 1°24 1°69 1°28 1°47 IOI 5 1d Dig ane ear 1°58 0°62 1270: 0°86 1-22. 0°68 5 Ts ee eceh 1°64 0°62 1°81 0°83 1°30 0°68 s Re ene Dae 0°56 oT 0°76 1°20 0°68 : View i theekis ae O°51 1°69 0°68 PxG C55 ss Vii eee s WO: 0°67 2°08 0°94 1°38 0°75 WVRCAIS ag eet cece ae: eye ees 1°62 0°70 1°63 0"90 1°29 0°73 ©; 2S. [eo eis = = SB Ss ee | Sing o | o | < ge |S Be | am > Boe °S les oer) & | 2B See |e © ee ee |e x | = [e Si ee | oe ie | —|——|-— By ale = OQ =) io e) aa 5 a ry : 3 ; = ur AYTIQnTOS ba B 2 ‘snoydaroure ‘Ire 07 oamsod -xo@ 110 AjTozeIp -OULUT UOT sum ‘poyegrd -iooad $= ATYSouz “0 N eT, te) ‘uly Usp FIT AA } -OOTVU _TUULTONT ‘snoydaoure *UMOAG SOUT} -omos ‘poyegid | “OQ nO -roord AT Ysouy ‘QuTZOOTU UOT OVI AA |-[eutsou-jAqQoTT 26 wt HO ‘OUTJOOLVU-[VUL -1ou - TAqgouTG 6) N sor 6) ‘(outjoo ~reu Aavurpto) oUliqoorVU-[BUL ‘seqsAr0 OFM | . cou- KyyourLey, ‘snoyd Ogt MA. ~1LOULB “ULIO WT 340 Messrs. Matthiessen and Wright on —_——[ Mar. 18, iI. “Researches into the Chemical Constitution of Narcotine, and of its Products of Decomposition.”—Part IV. By Aveustus Martrtuiessen, F.R.S., Lecturer on Chemistry in St. Bartholo- mew’s Hospital, and C. R. A. Wricut, B.Sc. London. Re- ceived February 18, 1869. (Abstract.) In Section I. of this memoir some new reactions of narcotine are described. A. When narcotine is submitted to the action of water, either boiling in open vessels or at temperatures above 100° C. in sealed tubes, it splits up into meconin and cotarnine. Cy ae NO,=C,, i , us ate Cs Ee NO.. The splitting up of narcotine under the influence of heated water may explain the occurrence of meconin in opium-residues, as probably the small amount of meconin always found there is simply due to the partial de- composition of the narcotine during the processes of extraction of morphia. B. Narcotine heated per se to a little above 200° splits up as above into meconin and cotarnine, the latter being immediately decomposed at that temperature. C. When hydrochlorate of narcotine is heated along with ferric chloride solution, the latter is reduced and the narcotine converted into opianic acid and cotarnine. | C,. ie NO,+ O=C,, it O, = Cz if ee NO,. Section II. treats of the decompositions of the narcotine-bases. A. Dimethyl-nornarcotine, when heated to above 100° C. with water in sealed tubes, undergoes decomposition: from the corresponding narcotine reaction it would seem that this decomposition might take place in either of two ways :— Narcotine. Meconin. Cotarnine. C,, H,,(CH,), NO, =C, H,(CH,), 0,+C,, H,, (CH,) NO,. Dimethyl-nornarcotine. Methyl-normeconin. Cotarnine. vr H,, (CH,), NO, = C, i (CH,) 0, a C., By (CH,) NO,, or Meconin. Cotarnimide. C,, H,, (CH,), NO,=C, H, (CH,), O,+-C,, H,, NO,. Of these the former reaction is apparently the one which thus takes place. This conclusion is borne out by the fact that, when treated with ferric or platinic chloride, the hydrochlorate of dimethyl-nornarcotine forms methyl- noropianic acid and cotarnine, and not opianic acid and cotarnimide. Dimethyl-nornarcotine. |Methyl-noropianic acid. Cotarnine. C,, H,; (CH,), NO, +O=€, H, (CH,)0,+C,, H,, (CH,) NO,, and not Opianic acid. Cotarnimide. C,, H,; (CH,), NO,+O0=C, H, (CH,), 0,+C,, H,, NO,. 1869. ] the Chemical Constitution of Narcotine. 341 B. From reasons given in the memoir, the reactions of methyl-nornar- eotine and nornarcotine with heated water and oxidizing agents are as follows :— Methyl-nornarcotine. Normeconin. Cotarnine. H,, (CH,) NO, = C, ee oO “hi Cc. EF (CH,) NO,, and not Methyl-normeconin. Cotarnimide. C,, H. (CH,) NO, = C, H, (CH,) OS C, i NO,, Methyl-nornarcotine. Noropianic acid. Cotarnine. C,, H,,(CH,) NO, +O= C,H, 0, +C,, H,, (CH;) NO,, and not Methyl-noropianic acid. Cotarnimide. Se us (CH,) NO,+ OC; H, (CH,) Oi C,, 13 NO,, Nornarcotine. Normeconin. Cotarnimide. eG Ee NO, = C, H, O, 5 cr He NO,, Noropianic acid. Cotarnimide. eH NOLO "= ¢,H,0, + ©, HNO, Section III. contains some miscellaneous observations on opianic acid, meconin, and hemipinic acid. A. Opianic acid treated with sulphuric acid and dilute solution of bichro- mate of potassium becomes oxidized to hemipinic acid. C,, H,, 0,+0= Cs 13 ie O,. When heated a few degrees above its melting-point, opianic acid loses water and yields a substance crystallizable from hot alcohol, differing in properties from opianic acid, and apparently containing C,,H,,0,,, being formed thus :-— 19? 4C,, HE , O,=H, ne. H B. All attempts to oxidize meconin to opianic or hemipinic acid were failures. Nitrous acid gas passed into melted meconin caused the formation of nitromeconin, identical with that got by the action of nitric acid, each sample, however, giving rather different qualitative reactions from those usually ascribed to this substance. : C. Hemipinic acid, when heated to 170°, loses water and becomes an anhydride, C,, H, O,, which may be crystallized unaltered from absolute alcohol, but when treated with ordinary spirit of 90 per cent. alcohol forms ethyl-hemipinic acid, C,, H, (C, H,) O,. Résumé of results obtained in the four portions* of this research. (1) It has been shown from the analyses of various samples of narcotine - derived from various sources, that narcotine has always the same composi- tion, viz. C,,H,, NO, (vol. xii. p. 501). * Parts I. & II. by Professor G. C. Foster and one of us, Proc. Roy. Soc. vol. xi. p- 55; xii. p. 501; xvi. p. 39. Part III. Proc. Roy. Soc. vol. xvii. p. 337. Part. IV. vol. xvii. p. 840. 342 Messrs. Matthiessen and Wright on - [Mar. 18, (2) As stated by former observers, narcotine under the influence of oxi- dizing agents splits up into opianic acid and cotarnine. Ors Bu Oe O= (Gh, i OF. oe Ley NO,. (3) When heated to a little above 200° per se, or for a considerable time in contact with water, narcotine splits up into meconin and cotarnine (vol. xvi. p. 340). C, Hy, NO, aa wt i 0, 1 ce H,, NO,. (4) When narcotine is heated with excess of hydrechloric acid for a short time (about two hours), chloride of methyl is formed, and one atom of H substituted for CH, in the narcotine ; if heated for a long time (some days), two atoms of Hi are substituted for two of CH,; when heated with fuming hydriodic acid, iodide of methyl is formed in such quantities as to prove that three atoms of Hare substituted for three of CH,. A series of homo- logous bases is thus formed, whose decompositions are analogous to those of narcotine. j (5) Cotarnine has been shown to have the formula C,, H,, NO,, and not C,,H,,NO,, and is capable of crystallizing with half a molecule, and with a whole molecule, of water of crystallization. (6) When cotarnine is heated with dilute nitric acid, under certain not clearly understood circumstances, eotarnic acid and methylamine is pro- duced, C,,H,, NO,+2H, O=C,, H,,0,+CH,N ; with strong nitric acid, as stated by previous observers, apophyllic acid is produced; other oxidizing agents give no definite results (vol. xi. p. 59). (7) When cotarnine is heated with strong hydrochloric acid, chloride of methyl is formed, and hydrochlorate of cotarnamic acid. C,, H,, NO,+H, 0+2HCI=CH, C1+C,, H,, NO, HCl. Hydriodic acid produces a similar reaction, only one equivalent of CH, being removed for one of cotarnine (vol. xu. p. 503). (8) Opianic acid under the influence of nascent hydrogen (as when treated with sodium-amalgam or zinc and sulphuric acid) is reduced to meconin (vol. xu. p. 503). C,, H,, O,+ H,=H, 0+C,, H,, O,. (9) Opianic acid heated with bichromate of potassium and dilute sul- phuric acid becomes oxidized to hemipinie acid (vol. xvi. p. 341). C,, EL O, AP O= Os ES O,. (10) Opianic acid heated with caustic potash splits up into meconin and hemipinic acid (vol. xi. p. 57). 2C,, H,,0,=C,, H,,0,+C,, H,, O¢- (11) Opianic acid heated with excess of hydrochloric acid forms chloride of methyl, hydrogen being substituted for CH, in the opianiec acid: it ap- pears probable that two distinct substances are thus produced, noropianic acid and methyl-noropianic acid—the former by substitution of H, for 1869. ] the Chemical Constitution of Narcotine. 043 (CH,),, and the latter by substitution of Hl for CH,; only the latter has been isolated in a pure state, the former decomposing spontaneously. C,, H,, 0, +2HCl=2CH, Cl+ ©, H, O,, C,,H,,O,+HCl = CH, CI-+C, H, O,. _ Hydriodic acid apparently produces similar decompositions. Like opianic acid, methyl-noropianic acid is monobasic (vol. xvi. p: 39). (12) All experiments to oxidize meconin to opianic acid or hemipinic acid or any other product have proved failures. (13) Meconin treated with excess of hydrochloric or hydriodic acid forms chloride or iodide of methyl, and a body derived from meconin by substi- tution of H for CH,, methyl-normeconin. eer ©, 1 Cl— CH, Cl- Ce, HO. Attempts to procure (hypothetical) normeconin by substituting H, for ves did not yield anything capable of isolation in a pure state (vol. xvi. 239). - (14) Hemipinic acid treated with various reducing agents has in no case been reduced to opianic acid or meconin; nor have experiments to form opianic acid by the union of hemipinic acid and meconin been successful ; nor has hemipinic acid been oxidized to any other compound. (15) When hemipinic acid is heated with excess of hydrochloric acid, chloride of methyl and carbonic acid are formed, together with a new acid, methyl-hypogallic acid, in accordance with the following equation :— C,, H,, 0, + HCI=CH, Cl+CO,+ C0, H, 9,. When heated with hydriodic acid, hypogallic acid is found, together with iodide of methyl] and carbonic acid: thus, C,, H,, O,+2 HI=2CH, 1+ CO,+ C, H, O, (vol. xvi. p. 40). (16) The observations of Anderson, that hemipinic acid is bibasic, have been confirmed, and an anhydride obtained by simple desiccation (vol. xvii. p- 341). Gy Ee Op Os C.. T O.. Methyl- hypogallic acid, however, is monobasic (vol. xvi. p. 40). (17) Hemipinic acid is capable of crystallizing with different amounts of water of crystallization, crystals with half a molecule, with a whole mo- lecule, and with two molecules of water having been obtained (vol. xvi. p. 40). (18) All the reactions of narcotine and of its products of decomposition may be satisfactorily accounted for by the following rational formula :— CH, (C,.8,0,)" I (C,H, Oy" (CH,),H ;9,. 344, Mr. H. Breen on the Corrections 4 [Maras, III. “On the Corrections of Bouvard’s Elements of Jupiter and Saturn (Paris, 1821).”. By Huen Breen, formerly of the Royal Observatory, Greenwich. Communicated by Professor G. G. Stoxss, Sec. R. 8. Received December 17, 1868. The Tables of Jupiter and Saturn which have been used for some years past in the computations of the ‘ Berlmer Jahrbuch’ and ‘ Nautical Al- manac,’ differ more from observation than is consistent with the present re- quirements of astronomy ; aud, moreover, abundant means for the correction of Bouvard’s ‘ Elements’ exist in the publication of the Greenwich Plane- tary Observations, 1750-1835, and the annual volumes issued from the Royal Observatory since 1836. The present work, which has been under- taken for this purpose, is based exclusively on the Greenwich Observations, 1750-1865. Fach mean group of observations in the Greenwich Planetary Reduc- tions &c. gives the mean error of the planet’s tabular geocentric place, with its equivalent in terms of the heliocentric errors of the earth and planet; but in the present investigation the places of Carlini’s Solar Tables, which have been used throughout the whole period (with the ex- ception of 1864 and 1865), have been accepted without alteration; for Jupiter and Saturn the factors of the earth’s heliocentric errors are so small, that the difference of Carlini’s Solar Tables from the recent investiga- tions of Leverrier may be neglected. The coefficients of the errors of the elements in heliocentric longitude and radius vector, for different values of the mean anomaly, are calculated in the usual way ; and the formation of the equations of condition is effected by their multiplication by the printed factors of the heliocentric errors of the planet in the Greenwich Observations. A weight is assigned to each equation of condition, dependent on the number of observations in the group, and the relation of the geocentric and heliocentric errors. The equations thus, multiplied by the weights, are then solved by the method of least squares. The results are given in the following Table :— Jupiter. 1750, October 29, to 1771, July 14. da =— 0:°000331873. de =+ 0:00000123252. Of = — 4 54304. 07 == —22'°36544. ol =— O”°311. SN=+99"'1819 (neglecting 07 as insensible). da ig the error of the planet’s semiaxis major, de is the error of the eccentricity, ¢¢ is the error of the epoch of the mean longitude, and é7 is the error of the longitude of the perihelion, oI is the error of the inclina- tion, and ON is the error of the longitude of the node. 1869.] of Bouvard’s Elements of Jupiter and Saturn. 1772, August 31, to 1810, Jannary 9. oa =— 0:000181527. de =— 0°00000211230. of = — 50080. Om =—41""7566. ol =— 0”:561. ON=+24"-911. 1811, February 12, to 1839, May 30. da2=— 0'0000355943. de =+ 0:00000126876. (i= 94801. om = —58"9578. 6b =—) 1438. ON=—/72'0634. 1840, January 18, to 1865, August 8. a= — 0:000166480. de =— 0:00000677360. d¢ =— 47°88982. Or =— 77'°3245. ob ==— 1668. ON=—118'°266. Saturn. 845 The tabular results of the ‘ Nautical Almanac’ and ‘ Berlin Ephemeris’ have been reduced to the value of the mass of Jupiter adopted in the Greenwich Planetary Reductions, 1750-1830; and the equations are formed as before mentioned. VOL. XVII, 1751, February 19, to 1783, September 28. da=+ 0:00048429. de =— 9:°000035957. 5 0¢ =— 7'°86558. On = +214'-9774, ol =— 10°°7538. ON =—157'"156. 1784, July 12, to 1814, July 19. da =+ 0:0000371094. se =— 0:°00000436038. of =— 438974. Om = -+121"'9323. ol =— 9”:046. oN = +.107''67. 346 Mr. W. 8. Savory on the Structure of the | [Mar. 18, 1815, July 29, to 1839, July 13. da =+ 0-00081572. de =+ 0000000334917. 0b = 0 e714 99: O¢ =-+ 40'°71125. él =— 10-418: ON=-+ 95/207. 1840, March 9, to 1865, June 9. da =+ 0:00076325. de =+ 0:0000286012. dé =— 2”°89008. On ==— 31:47275. ON oa eee ON =+38''16. IV. “On the Structure of the Red Blood-corpuscle of Oviparous Vertebrata.” By Wiztitiam 8S. Savory, F.R.S. Received February 20, 1869. The red blood-cell has been perhaps more frequently and fully examined than any other animal structure ; certainly none has evoked such various and even contradictory opinions of its nature. But without attempting here any history of these, it may be shortly said that amongst the con- clusions now, and for a long time past, generally accepted, a chief one is that a fundamental distinction exists between the red corpuscle of Mam- malia and that of the other vertebrate classes—that the red cell of the oviparous vertebrata possesses a nucleus which is not to be found in the corpuscle of the other class. This great distinction between the classes has of late years been over and over again laid down in the strongest and most unqualified terms. But I venture to ask for a still further examination of this important subject. As the oviparous red cell is commonly seen, there can be no doubt whatever about the existence ofa ‘‘nucleus”’ initsinterior. Itis tco striking an object to escape any eye; but 1 submit that its existence is due to the circumstances under which the corpuscle is seen, and the mode in which it is prepared for examination. I think it can be shown that the so-called nucleus is the result of the changes which the substance of the corpuscle undergoes after death (and which are usually hastened and exaggerated by exposure), and the disturbance to which it is subjected-in being mounted for the micro- scope. When a drop of blood is prepared for examination, little orno attention is given to the few seconds, more or less, which are consumed in the mani- pulation. It is usually either pressed or spread out on the glass slip, and 1869. | Red Blood-corpuscle of Oviparous Vertebrata. O47 often mixed with water or some other fluid, But it is possible to place blood-cells under the microscope for examination so quickly, and with such slight disturbance, that they may be satisfactorily examined before the nuclei have begun to form. They may then be shown to be absolutely structureless throughout ; and, moreover, as the examination is continued the gradual formation of the nuclei can be traced. The chief points to be attended to are—to mount a drop of blood as quickly as possible, to avoid as much as possible any exposure to air, to avoid as much as practicable contact of any foreign substance with the drop, or any disturbance of it. After many trials of various plans, I find that the following will often succeed sufficiently well. Having the microscope, and everything else which is required, conveniently arranged for immediate use, an assistant secures the animal which is to furnish the blood (say, a frog or a newt), in such a way that the operator may cleanly divide some superficial vessel, as the femoral or humeral artery. He then instantly touches the drop of blood which exudes with the under surface of the glass which is to be used as the cover, immediately places this very lightly upon the slide, and has the whole under the microscope with the least possible delay. Thus for several seconds the blood-cells may be seen without any trace of nuclei ; then, as the observation is continued, these gradually, but at first very faintly, appear; and the study of their formation affords strong proof of their absence from the living cells. The “nucleus” first appears as an indistinct shadowy substance, usually, but not always, about the centre of the cell. The outline of it can hardly, for some seconds, be defined ; but it gradually grows more distinct. Often some small portion of the edge appears clear before the rest. At the same time the nucleus is seen to be paler than the surrounding substance. Syn- chronously with this change—and this is noteworthy—the outline of the corpuscle (the “cell-wall’’) becomes broader and darker, What was at first a mere edge of homogeneous substance, becomes at length a dark border sharply defined from the coloured matter within. Thus a corpuscle, at first absolutely structureless, homogeneous throughout, is seen gradually to be resolved into central substance or nucleus, external layer or cell- wall, and an intermediate, coloured though very transparent, substance. But—and this is significant—these changes are not always thus fully carried out. It not seldom happens that the nucleus does not appear as a central well-defined regularly oval mass. Sometimes it never forms so as to be clearly traced in outline, but remains as an irregular shapeless mass, in its greater portion very obscure. Sometimes only a small part, if any, of an edge can be recognized, most of it appearing to blend indefinitely with the rest of the cell-substance. Sometimes it happens that in many corpuscles the formation of a nucleus does not proceed even so far as this. No distinct separation of substance can anywhere be seen, but shadows, more or less deep, here and there indicate that there is greater aggregation of matter at some parts than at others. Occasionally some cf the cells 2ce2 348 Mr. W. 8S. Savory on the Structure of the |Mar. 18, present throughout a granular aspect. I have almost invariably observed, too, a relation between the distinctness of the nucleus and of the cell-wall. When the nucleus is well defined, the cell-wall is strongly marked ; when one is confused, the other is usually fainter. This, however, does not apply to colour; on the contrary, when the nucleus is least coloured it contrasts most strongly with the surrounding cell. As a rule, the wall. of the cell is more strongly marked than the nucleus. It will of course be said that the nuclei are present all the while, but are at first concealed by the surrounding substance—the contents of the cell. Thus the fact has been accounted for, that the nuclei are not so obvious at first as they subsequently become. But I think a careful com- parison of cells will show that those in which a nucleus may be traced are not more transparent than others which are structureless; and, moreover, when one cell overlaps another, the lower one is seen through the upper clearly enough to show that the substance of these cells is sufficiently transparent to allow of a nucleus being discerned if it exists. When a nucleus is fully formed, it hides that portion of the outline of a cell which lies beneath it. How is it, then, if the nucleus is present from the first, that the portion of the cell over which it subsequently appears is, for a while, plainly seen ? The success of the observation is of course influenced by numerous cir- cumstances. The rate at which the nuclei form in the corpuseles varies in different animals. I have usually found that in the common frog they are more prone to form than in many other animals—quicker than in most fishes, or even than in some birds. But this does not seem always to depend upon their larger size; for in the common newt the cells, which are larger than those of the frog, remain, as I have noticed, for a longer period without any appearance of nuclei. But even in the frog it can be satis- factorily demonstrated that the corpuscle is structureless. I have found, too, that the observation succeeds best with the blood of animals which are healthy and vigorous. Thus the first observations upon fresh animals are usually the most satisfactory. After they have been repeatedly wounded or have lost much blood, the cells are more prcne to undergo the changes which result in the production of nuclei. Again, the formation of nuclei may be hastened, and their appearance rendered more distinct at last, by various reagents. Acids and many other reagents are well known to have this effect. The addition of a small | quantity of water acts in the same way, but less energetically. It hastens the appearance of an indistinct nucleus, but interferes with the formation of a well-defined mass, so that, after the addition of water, neither the outline of the cell nor of the nucleus becomes so strongly marked as it often does without it. Exposure to air also promotes their formation; indeed, as a rule, the nuclei form best under simple exposure. Any disturbance of the drop, as by moving the point of a needle in it, certainly hastens the change; and perhaps it is influenced by temperature. 1869. | Red Blood-corpuscle of Oviparous Vertebrata. 349 Sometimes, when the drop of blood has been skilfully mounted, the majority of cells will remain for a long while without any trace of nucleus; but, again, in almost every specimen, the nucleus in some few of the cells, particularly in those nearest the edges, begins to appear so rapidly that it is hardly possible to run over the whole field without finding some cells with an equivocal appearance. It would follow, of ccurse, from these observations that, if the living blood were examined in the vessels, the corpuscle would show no trace of any distinction of parts; and this is so. Indeed, in my earlier observations*, before I had learnt to mount a drop of blood for observation in a satisfactory manner, I examined, at some length, blood in the vessels of the most transparent parts I could select; and several observations on the web and lung of the frog and elsewhere were satisfactory. But still, when the cells were thus somewhat obscured by intervening membrane, one could not generally feel sure that the observation was so clear and complete, but that a faintly marked nucleus might escape detection. While, therefore, the result of observations on blood-cells in the vessels fully accords with the description I have given, I do not think that the demonstration of the fact, that while living they have no nucleus, can be made so plain and un- equivocal as when they are removed from the vessels. The question naturally arises, Why, then, does not a nucleus form in the mammalian corpuscle? But while it is accepted that the great majority of these corpuscles exhibit no nuclei after death, excellent observers still affirm their occasional existence; and I am convinced that an indistinct, imperfectly formed “‘nucleus”’ is often seen; and the shadowy sub- stance seen in many of the smaller oviparous cells after they have been mounted for some time is very like that seen under similar circumstances in some of the corpuscles of Mammalia. Many, too, affirm that these cor- puscles do not exhibit that distinction of wall and contents which is generally described. It appears to me that this- difference of opinion de- pends on the changes they are prone to undergo. How far the absence of a distinctly defined “nucleus” after death depends on their smaller size I am not prepared to say. Many questions of course follow. For example, how far is this separa- tion of the substance of a homogeneous corpuscle into nucleus, cell- membrane, and contents to be compared to the coagulation of the blood? and how do the agents which are known to influence the one process affect the other? A still further and more important question is, How are these changes in the corpuscles, and in the blood around them, related ? But in this paper I propose to go no further than the statement that the * Made many years ago. Other observers have been unable to detect a nucleus in the living cells within the vessels. t By the word homogeneous I do not mean to affirm that the substance of the cor- puscle is of equal consistence throughout. The central may be the softest part of it: But I regard the corpuscle, in its whole substance, as ‘ having the same nature.” 850 Mr. J. N. Lockyer on Spectroscopic . {Mar. 18, red corpuscle of all vertebrata is, in its natural state, structureless. When living, no distinction of parts can be recognized ; and the existence of a nucleus in the red corpuscles of ovipara is due to Bo after death, or removal from the vessels. I cannot conclude this paper without acknowledging the great help I have received in this investigation from Mr. Howard Marsh, Demonstrator of Microscopical Anatomy at St. Bartholomew’s Hospital. V. “Spectroscopic Observations of the Sun.—No. III.” By J. Norman Locxyer, F.R.A.S. Communicated by Dr, Franx- LAND, F.R.S. Received March 4, 1869. - Since my second paper under the above title was communicated to the Royal Society, the weather has been unfavourable to observatory work to an almost unprecedented degree ; and, as a consequence, the number of observations I have been enabled to make during the last four months is very much smaller than I had hoped it would be. Fortunately, however, the time has not been wholly lost in consequence of the weather ; for, by the kindness of Dr. Frankland, I have been able in the interim to famiharize myself at the Royal College of Chemistry with the spectra of gases and vapours under previously untried conditions, and, in addition to the results already communicated to the Royal Society by Dr. Frankland and myself, the experience I have gained at the College of Chemistry has guided me greatly in my observations at the telescope. In my former paper it was stated that a diligent search after the known third line of hydrogen in the spectrum of the chromosphere had not met with success. When, however, Dr. Frankland and myself had determined that the pressure in the chromosphere even was small, and that the widening out of the hydrogen lines was due in the main, if not entirely, to pressure, I determined to seek for it again under better atmospheric conditions ; and I succeeded after some failures. The position of this third line is at 2796 of Kirchhoff’s scale. It is generally excessively faint, and much more care is required to see it than is necessary in the case of the other lines; the least haze in the sky puts it out altogether. Hence, then, with the exception of the bright yellow line, the observed spectra of the prominences and of the chromosphere correspond exactly with the spectrum of hydrogen under different conditions of pressure—a | fact not only important in itself, but as pointing to what may be hoped for in the future. With regard to the yellow line which Dr. Frankland and myself have stated may possibly be due to the radiation of a great thickness of hydrogen, it became a matter of importance to determine whether, like the red and green lines (C & F), it could be seen extending on to the limb. I have not observed this: it has always in my instrument appeared asa very fine sharp line resting absolutely on the solar spectrum, and neyer encroaching on it. 1869. | - Observations of the Sun. 301 Dr. Frankland and myself have pointed out that, although the chromo- sphere and the prominences give out the spectrum of hydrogen, it does not follow that they are composed merely of that substance: supposing others to be mixed up with hydrogen, we might presume that they would be indi- © cated by their selective absorption near the sun’s limb. In this case the spectrum of the limb would contain additional Fraunhofer lines. I have pursued this investigation to some extent, with, at present, negative results ; but I find that special instrumental appliances are. necessary to settle the question, and these are now being constructed. If we assume, as already suggested by Dr. Frankland and myself, that no other extensive atmosphere besides the chromosphere overlies the pho- tosphere, the darkening of the limb being due to the general absorption of the chromosphere, it will follow :— I. That an additional selective absorption near the limb is extremely probable. II. That the hydrogen Fraunhofer lines indicating the absorption of the outer shell of the chromosphere will vary somewhat in thickness : this I find to be the case to a certain extent. Iii. That it is not probable that the prominences will be visible on the sun’s disk. In ecnnexion with the probable chromospheric darkening of the limb, an observation of a spot on February 20th is of importance. ‘The spot observed was near the limb, and the absorption was much greater than anything I had seen before ; so great, in fact, was the general absorption, that the several lines could only be distinguished with difficulty, except in the very brightest region. I ascribe this to the greater length of the absorbing medium in the spot itself in the line of sight, when the spot is observed near the limb, than when it is observed in the centre of the disk— another indication of the great general absorbing power of a comparatively thin layer, on rays passing through it obliquely. T now come to the selective absorption ina spot. I have commenced a map of the spot-spectrum, which, however, will require some time to com- plete. In the interim, I may state that the result of my work up to the present time in this direction has been to add magnesium and barium to the material (sodium) to which I referred in my paper in 1866, No. I. of the present series; and I no longerregard a spot simply as a cavity, but as a place in which principally the vapours of sodium, barium, and magne- sium (owing to a downrush) occupy a lower position than they do ordi- narily in the photosphere. I do not make this assertion merely on the strength of the lines observed to be thickest in the spot-spectrum, but also upon the following observa- tions on the chromosphere made on the 21st and 28th ultimo. On both these days the brilliancy of the F line taught me that something unusual was going on; so I swept along the spectrum to see if any materials - were being injected into the chromosphere. 352 Mr. J. N. Loek yer on Spectroscopic — [ Mar. 18, On the 21st I caught a trace of magnesium; but it was late in the day, and I was coinpelled to cease observing by houses hidin® the sun. On the 28th I was more fortunate. If anything, the evidences of intense action were stronger than on the 21st, and after one glance at the F line I turned at once to the magnesium lines. I saw them appearing short and faint at the base of the chromosphere. My work on the spots led me to imagine that I should find sodium-vapour associated with the magnesium ; and on turning from 6 to D I found this to be the case. I afterwards re- versed barium in the same way. The spectrum of the chromosphere seemed to be full of lines, and I do not thik the three substances I have named accounted for all of them. The observation was one of excessive delicacy, as the lines were short and very thin. ‘The prominence was a small one, about twice the usual height of the chromosphere; but the hydrogen lines towered high above those due to the newly injected materials. The lines of magnesium extended perhaps one-sixth of the height of the F line, barium a little less, and sodium least of all. We have, then, the following facts :— I. The lines of sodium, magnesium, and barium, when observed in a spot, are thicker than their usual Fraunhofer lines. IT. The lines of sodium, magnesium, and barium, when observed in the chromosphere, are thinner than their usual Fraunhofer lines. A series of experiments bearing upon these observations is now ia progress at the College of Chemistry, and will form the subject of a commu- nication from Dr. Frankland and myself. I may at once, however, remiark that we have here additional evidence of a fact I asserted in 1865 on tele- scopic evidence—the fact, namely, that a spot is the seat of a downrush, a dowurush to a region, as we now know, where the selective absorption of the upper strata is different from what it would be (and, indeed, is elsewhere) at a higher level. Messrs. De La Rue, Stewart, and Loewy, who brought forward the ery of a downrush about the same time as my observations were made in 1865, at once suggested as one advantage of this explanation that all the grada- tions of darkness, from the faculee to the central umbra, are thus supposed to be due to the same cause, namely, the presence to a greater or less extent of a relatively cooler absorbing atn nosphere. This I think is now spectro- scopically established ; we hae e, in fact, two causes for the darkening of a spot :— I. The general absorption of the chromosphere, thicker here than else- aire as the spot is a cavity. II. The greater selective absorption of the lower sodium, barium, mag- nesium stratum, the surface of its last layer being below the ordinary level. Messrs. De La Rue, Stewart, and Loewy also suggested, in their ‘ Re- searches on Solar Physics,’ that if the photosphere of the sun be the plane of condensation of gaseous matter, the plane may be found to be subject to 1869. ] _ Observations of the Sun. 358 periodical elevations and depressions, and that at the epoch of minimum sun-spot-frequency. the plane might be uplifted very high in the solar atmosphere, so that there was comparatively little cold absorbing atmosphere above it, and therefore great difficulty in forming a spot. This suggestion is one of great value ; and, as I pointed out in my previous paper, its accuracy can fortunately now be tested. It may happen, how- ever, that in similar periodical fluctuations the chromosphere may be carried up and down with the photosphere ; and I have already evidence that possibly such a state of things may have occurred since 1860, for I do not find the C and F Fraunhofer lines of the same relative thickness as they were in that year*. [am waiting to make observations with the large Steinheil spectroscope before I consider this question settled. But the well-known great thickness of the F line in Sirius and other stars will point out the excessive importance of such observations as a method of ascertain- ing not only the physical constitution, but the actual pressures of the outer limits of stellar atmospheres, and of the same atmosphere at different epochs. And when other spectra have been studied as we have now studied hydrogen, additional means of continuing similar researches will be at our command ; indeed a somewhat careful examination of the spectra of the different classes of stars, as defined by Father Secchi, leads me to believe that several broad conclusions are not far to seek; and I hope soon to lay them before the Royal Society. For some time past I have been engaged in endeavouring to obtain a sight of the prominences, by using a very rapidly oscillating slit; but although I believe this method will eventually succeed, the spectroscope I employ does not allow me to apply it under sufficiently good conditions, and I am not at present satisfied with the results I have obtained. Hearing, however, from Mr. De La Rue, on February 27th, that Mr. Huggins had succeeded in anticipating me by using absorbing media and a wide slit (the description forwarded to me is short and vague), it imme- diately struck me, as possibly it has struck Mr. Huggins, that the wide slit is quite sufficient without any absorptive media; and during the last few days I have been perfectly enchanted with the sight which my spectro- scope has revealed to me. The solar and atmospheric spectra being hidden, and the image of the wide slit alone being visible, the telescope or slit is moved slowly, and the strange shadow-forms flit past. Here one is reminded, by the fleecy, infinitely delicate cloud-films, of an English hedge- row with luxuriant elms; here of a densely intertwined tropical forest, the intimately interwoven branches threading in all directions, the prominences generally expanding as they mount upwards, and changing slowly, indeed almost imperceptibly. By this method the smallest details of the pro- * T have learnt, after handing this paper in to the Royal Society, that in Angstrém’s Map the C and F lines are nearly of the same breadth: this I had gathered from obser- vations made with my own spectroscope. Os o4 Mr. J. N. Lockyer ‘on Spectroscopic _ [ Mar. 18, minences and of the chromosphere itself are rendered perfectly visible and easy of observation. > ? ADDENDUM.—Received March 117, 1869. Since the foregoing paper was written, I have had, thanks to the some- what better weather, some favourable opportunities for continuing two of the lines of research more especially alluded to in it; [refer to the method I had adopted for viewing the prominences, and to the injection of sodium, magnesium, &c, into the chromosphere. With regard to seeing the prominences, I find that, when the sky is free from haze, the views I obtain of them are so perfect that I have not thought it worth while to remount the oscillating sht. Iam, however, collecting red and green and violet glass, of the required absorpticns, to construct a rapidly revolving wheel, in which the percentages of light of each colour may be regulated. In this way I think it possible that we may in time be able to see the prominences as they really are seen in an eclipse, with the additional advantage that we shall be able to see the sun at the same time, and test the connexion or otherwise between the prominences and the surface-phenomena. Although I find it generally best for sketching-purposes to have the open slit in a radial direction, I have lately placed it at a tangent to the limb, in order to study the general outline of the chromosphere, which in a previous communication I stated to be pretty uniform, while M. Janssen has characterized it as ‘‘d niveau fort inégal et tourmenté.’ My Opinion is now that perhaps the mean of these two descriptions is, as usual, nearer the truth, unless the surface changes its character to a large extent from time to time. I find, too, that in different parts the outline varies: here it is undulating and billowy; there it is ragged to a degree, flames, as it were, darting out of the general surface, and forming a ragged, fleecy, interwoven outline, which in places is nearly even for some distance, and, like the billowy surface, becomes excessively uneven in the neighbour- hood of a prominence. According to my present limited experience of these exquisitely beautiful solar appendages, it is generally possible to see the whole of their structure ; but sometimes they are of such dimensions along the line of sight that they appear to be much denser than usual; -and as there is no longer under these circumstances any background to the central portion, only the - details of the margins can be observed, in addition to the varying bright- nesses. Moreover it does not at all follow that the largest prominences are those in which the intensest action, or the most rapid change, is going on, —the action as visible to us being generally confined to the regions just in, or above, the chromosphere, the changes arising from violent uprush or rapid dissipation, the uprush and dissipation representing the birth and death of a prominence. As a rule, the attachment to the chromosphere 1869. | Observations of the Sun. 355 is narrow and is not often single; higher up, the stems, so to speak, inter- twine, and the prominence expands and soars upward until it is lost in delicate filaments, which are carried away in floating masses. Since last October, up to the time of trying the method of using the open slit, I had obtained evidence of considerable changes in the pro- minences from day to day. With the open slit it is at once evident that changes on the small scale are continually going on; it was only on the 14th inst. that I observed any change at all comparable in magnitude and rapidity to those already observed by M. Janssen. About 9” 45™ on that day, with a tangential slit I observed a fine dense prominence near the sun’s equator, on the eastern limb. I tried to sketch it with the slit in this direction ; but its border was so full of detail, and the atmospheric conditions were so unfavourable, that I gave up the attempt in despair. I turned the instrument round 90° and narrowed the slit, and my attention was at once taken by the F line; a single look at it taught me that an injection into the chromosphere and intense action were taking place. These phenomena I will refer to subsequently. At 105 50™, when the action was slackening, I opened the slit ; I saw at once that the dense appearance had all disappeared, and cloud-like filaments had taken its place. ‘The first sketch, embracing an irregular prominefice with a long perfectly straight one, which I called A, was finished at 11> 5%, the height of the prominence being 1! 5!', or about 27,000 miles. I left the Observatory for a few minutes; and on returning, at 11" 15™, 1 was as- tonished to find that part of the prominence A had entirely disappeared ; not even the slightest rack appeared in its place: whether it was entirely dis- sipated, or whether parts of it had been wafted towards the other part, I do not know, although I think the latter explanation the more probable one, as the other part had increased. We now come to the other attendant phenomena. First, as to the F line. In my second paper, under the above title, I stated that the F line widens as the sun is approached, and that sometimes the bright line seems to extend on to the sun itself, sometimes on one side of the F line, sometimes on the other. Dr. Frankland and myself have pointed out, as a result of a long series of experiments, that the widening out is due to pressure, and apparently not to temperature per se; the F line near the vacuum-point is thin, and it widens out on both sides (I do not say to the same extent) as the pressure is increased. Now, in the absence of any disturbing cause, it would ap- pear that when the wider line shows itself on the sun on one side of the I* line, it should at the same time show itself on the other; this, however, it does not always do. J have now additional evidence to adduce on this point, and this time in the prominence line itself, off the sun. In the pro- minence to which I have referred, the F bright line underwent the most strange contortions, as if there were some disturbing cause which varied the refrangibility of the hydrogen-line under certain conditions and pressures. 306 On Spectroscopic Observations of the Sun. _ [Mar. 18, The D line of hydrogen (?) also once bore a similar appearance. Secondly, as to the other phenomena which accompanied this strange behaviour of the F line, and were apparently the cause of it. In the same field of view with F, I recognized the barium-line at 1$89°5 of Kirchhoff’s scale. Passing on, the magnesium-lines and the enclosed nickel-iron-line were visible in the chromosphere. The magnesium was projected higher into the chromosphere than the barium, and the nickel or iron was projected higher than the magnesium. I carefully examined whether the other iron-lmes were visible in the spectrum of the chromosphere ; they were not. I also searched for the stronger barium-lines in the brighter portion of the spectrum; but I did not find them, probably owing to the feeble elevation of the barium-vapour above the general level of the photo- sphere, which made the observation in this region a very delicate one. I detected another chromosphere-line very near the iron-line at 1569°5 (on the east side of it). The sodium-lines were also visible Unfortunately clouds prevented my continuing these interesting observa- tions; but the action was evidently toning down. “Here, then, we have an uprush of Barium, Magnesium, ? Nickel, and an unknown substance from the photosphere into the chromosphere, and with the uprush a dense prominence ; accompanying the upr ush we have changes of an enormous magnitude in the prem ence and as the uprush ceases the prominence melts away. As stated in the former part of this paper, the barium- and magnesium- lines were thinner than the corresponding Fraunhofer lines. In con- nexion with this subject, I beg to be allowed to state that I have com- menced a careful comparison of Kirchhoff’s map with the recently pub- — lished one of Angstrém. From what I have already seen, I believe other important conclusions, 10 addition to that before alluded to, may be derived from this comparison ; but I hesitate to say more at present, as I have not yet been able to compare Angstrom’ s maps with the sun itself, or to examine the angular diameters of the sun registered at Greenwich during the pre- sent century. On the 14th inst. I also succeeded in detecting the hydrogen -line in the extreme violet in the spectrum of the chr Hips = The Society then adjourned over the Easter Recess to Thursday, April 8. CONTENTS—(continued). PAGE II. Researches into the Chemical Constitution of Narcotine, and of its Pro- ducts of Decomposition.—Part IV. By Augustus MATTHIESSEN, F.R.S., Lecturer on Chemistry in St. Bartholomew’s eee: and C. R. A. Woeeen BSc. London..." .. sa . 340 III. On the Corrections of Bouvard’s Elements of Jupiter and Saturn pa 1821). By Hue ee Pes! of the Royal lactis Green- “TUNEL ok Sens aes : coe ; . . . 044 IV. On the Structure of the Red a. of f Oriparou Vertebrata. By Witram §. SAvoRY, BOBS. 7. ee : 2 os ie os ae V. Spectroscopic Observations of the Sun.—No. IIL. Fed J.*° NoRMAN ockyER: TRA 2)... Lato Bae ee Se iS Obituary Notices : ANTOINE Francois JEAN CLAUDET. . .. . ... .%. . «. ixxxy CHARLES JAMES BEVERLY, F.R.S.,F.LS. . . . . . . . . Ixexxvii TAYLOR AND FRANCIS, RED LION COURT, FLERT STREET. PROCEEDINGS OF *« 4 ° THE ROYAL SOCIETY. | VOL. XVII. ar No. 111. Sl aa 3) ' CONTENTS. - : PAGE Note on the Blood-vessel-system of the Retina of the Hedgehog (being a fourth Contribution to the Anatomy of the Retina). By J.W. Huxxz, F.R.S., Assistant-Surgeon to the Middlesex Hospital and the Royal London MME EDOSDIGA 6 hig: 0 he ee te ke ow a I OE On the Measurement of the Luminous Intensity of Light. By Wuttiam IEEE GE oh Gre noi Foun ele ky wl oleh ether vee ape cere Addendum to description of Photometer. By W. Crooxss, F.R.S. . 369 April 8, 1869. I. Preliminary Notice on the Mineral Constituents of the Breitenbach Mete- orite. By Professor N. Story Maskrtyne, M.A. . . .... . . 340 II. On the Derivatives of Propane (Hydride of Propyl). By C. SchorLEMMER 372 _ III. Researches in Animal Electricity. By Caartes Buanp Rapourre, M.D.. 377 | ~ g OEP nc continuation of Contents see the 4th page of Wrapper. « Ye g April 15, 1869. I. On the Source of Free Hydrochloric Acid in the Gastric Juice. By Professor ert onewenn, Cambridac, U. S.A oe ees 6 a a SE II. Contributions to the History of Explosive Agents. By F. A. ABEL, F.R.S., Lah 2h SANG oe ee oe EN RCs Ure Tt: Results of Mccrctical Observations made at Ascension Island, Latitude 7° 55’ 20” South, Longitude 14° 25’ 30” West, from July 1863 to emeareh 1866. By Licut. Romesy, B.M. se os a eee April 22, 1869. ine f. Des iption of Parkeria and iho, two gigantic: Hy pes of Arenaceous n, V.P.B.S., and. B. Faas, WS . 400 weet : oy ihe 4 y woe 1869.| Blood-vessel-system of the Retina of the Hedgehog. 357 * Note on the Blood-vessel-system of the Retina of the Hedgehog (being a fourth Contribution to the Anatomy of the Retina).” By J. W. Hurxs, F.R.S., Assistant-Surgeon to the Middle- sex Hospital and the Royal London Ophthalmic Hospital. Received May 26, 1868*. The distribution of the retinal blood-vessels in this common British Insec- tivore is so remarkable that I deem it worthy of a separate notice—only capillaries enter the retina. The vasa centralia pierce the optic nerve in the sclerotic canal, and, passing forwards through the lamina cribrosa, divide, at the bottom of a relatively large and deep pit in the centre of the intraocular disk of the nerve, into a variable number of primary branches, from three to six. These primary divisions quickly subdivide, furnishing many large arteries and veins, which, radiating on all sides from the nerve-entrance towards the ora retinze, appear to the observer’s unaided eye as strongly projecting ridges upon the inner surface of the retina. When vertical sections parallel to and across the direction of these ridges are examined with a quarter-inch objective, we immediately perceive that the arteries and veins lie, throughout their entire course, upon the inner surface of the mem- brana limitans interna retinze, between this and the membrana hyaloidea of the vitreous humour, and that only capillaries penetrate the retina itself. In sections of the retina across the larger vessels the membrana limitans may be seen as a clean distinctly unbroken line passing over the divided vessels, with which it does not appear to have any direct structural connexion. The relation of the hyaloidea to the large vessels seems to be more intimate, but its exact nature can be less certainly demonstrated, owing to the ex- treme tenuity of this membrane. In my best sections I saw the hyaloidea also crossing the large vessels, as does the limitans, but excessively delicate extensions of the hyaloidea appeared to me to lose themselves upon the vessels. The capillaries, shortly after their origin, bend outwards away from the large vessels, and, piercing the retina vertically to its stratification in a direc- tion more or less radial from the centre of the globe, and branching dicho- tomously in the granular and inner granule-layers, they form loops, the outermost of which reach the intergranule-layer. As they enter the retina the membrana limitans interna is prolonged upon the capillaries in the form of a sheath, which is wide and funnel-like at first, but soon em- braces the vessels so closely as to become indistinguishable from their proper wall; so that, notwithstanding the existence of a sheath, there is no perivascular space about the retinal capillaries, such as His has described * Read June 18, 1868: see Abstract, vol. xvi. p. 439. VOL. XVII. 25 358 Mr. W. Crookes on the Measurement of the in the brain or spinal cord, and has stated to occur in the retina and else- where. In all other mammals, except the hedgehog, as far as my present know- ledge extends, the arteries, veins, and capillaries lie in the retina. In fish, amphibia, reptiles, and birds, however, as H. Miiller and others (myself as regards amphibia and reptiles) have shown, the retina is absolutely non- vascular, the absence of proper retinal blood-vessels being compensated for in fish, amphibia, and some reptiles by the vascular net which in these animals channels the hyaloidea, and by the highly vascular pecten present in other reptiles and in birds. Thus it is possible to divide vertebrates into two classes, according as their retina is vascular or non-vascular ; and these classes would be connected by the hedgehog, the larger branches of whose vasa centralia lying upon the membrana limitans in intimate relation with the hyaloidea, represent the equivalent vessels of the hyaloid system, which forms so exquisite a microscopic object in the frog; whilst the capillary vessels channelling the retinal tissues occupy the same position which they do in most mammalia. [The drawings in illustration of this paper are preserved for reference in the Archives of the Royal Society. | “On the Measurement of the Luminous Intensity of Light.” By Wiuiiam Crooxss, F.R.S. &c. Received June 27, 1868*. The measurement of the intensity of a ray of light is a problem the solu- tion of which has been repeatedly attempted, but with less satisfactory results than the endeavours to measure the other radiant forces. The problem is susceptible of two divisions—the absolute and the relative measurement of light. , : I. Given a luminous beam, we may require to express its intensity by some absolute term having reference to a standard obtained at some previous time, and capable of being reproduced with accuracy at any time and at any part of the globe. Possibly two such standards would be necessary, differing greatly in value, so that the space between them might be subdivided into a definite number of equal parts; or the same result might perhaps be obtained by the well-known device of varying the appa- rent intensity of the standard light by increasing and diminishing its dis- tance from the instrument. II. The standard of comparison, instead of being obtained once for all, like the zero- and boiling-points of a thermometer, may be compared separately at each observation ; and the problem then becomes somewhat simplified into the determination of the relative intensities of two sources of light. The absolute method is of course the most desirable; but as the pre- * Read December 17,1868: see Abstract, antea. p. 166. Luminous Intensity of Light. 359 liminary researches and discoveries are yet to be made, before a photometer analogous to a thermometer in fixity of standard and facility of observa- tion could be devised, the realization of an absolute light-measuring method appears somewhat distant. The path to be pursued towards the attain- — ment of this desirable object appears to be indicated in the observations which from time to time have been made by M. Becquerel, Sir John Herschel, R. Hunt, and others, on the chemical action of the solar rays, and the production thereby of a galvanic current, capable of measurement on a delicate galvanometer, by appropriate arrangements of chemical baths and metallic plates connected with the ends of the galvanometer wires. Many so-called photometers have been devised, by which the chemical action of the rays at the most refrangible end of the spectrum have been measured, and the chemical intensity of light tabulated by appropriate methods ; and within the last few years Professors Bunsen and Roscoe have contrived a perfect chemical photometer, based upon the action of the chemical rays of light on a gaseous mixture of chlorine and hydrogen, causing them to combine with formation of hydrochloric acid. But the measurement of the chemical action of a beam of light is as distinct from photometry proper as is the thermometric registration of the heat-rays constituting the other end of the spectrum. What we want is a method of measuring the intensity of those rays which are situated at the intermediate parts of the spectrum, and produce in the eye the sensation of light and colour; and, as previously suggested, there is a reasonable presumption that further researches may place us in possession of a pho- tometrie method based upon the chemical action of the luminous rays of light. The rays which affect an ordinary photographic sensitive surface are so constantly spoken of and thought about as the ultra-violet invisible rays, that it is apt to be forgotten that some of the highly luminous rays of light are capable of exerting chemical action. Fifteen years ago* the writer was engaged in some investigations on the chemical action of light, and he suc- ceeded in producing all the ordinary phenomena of photography, even to the production of good photographs in the camera, by purely luminous rays of light free from any admixture with the violet and invisible rays. When the solar spectrum (of sufficient purity to show the principal fixed lines) is projected for a few seconds on to a sensitive film of iodide of silver, and the latent image then developed, the action is seen to extend from about the fixed line G to a considerable distance into the ultra-violet invisible rays. When the same experiment was repeated with a sensitive surface of bromide of silver instead of iodide of silver, the result of the development of the latent image showed that, in this case, the action commenced at about the fixed line 6, and extended, as in the case of the iodide of silver, far beyond the violet. A transparent cell, with parallel glass sides one inch across, was filled with a solution of twenty-five parts of sulphate of quinine * The Journal of the Photographic Society, vol. i. p. 98. 2E2 360 Mr. W. Crookes on the Measurement of the to one hundred parts of dilute sulphuric acid; this was placed across the path of the ray of light, and photographs of the spectrum were again taken on iodide of silver and on bromide of silver, the arrangements being, in all cases, identical with those in the first-cited experiments, with the exception of the interposition of the quinine screen. The action of the sulphate of quinine upon a ray of light is peculiar; to the eye it scarcely appears to have any action at all, but it is absolutely opaque to the ultra-violet, so- called chemical rays, and thus limits the photographic action on the bro- mide and iodide of silver to the purely luminous rays. On developing the latent images, it was now found that the action on iodide of silver was con- fined to a very narrow line of rays, close to the fixed line G, and in the case of bromide of silver, to the space between 6 and G. Designating the spaces of action by colours instead of fixed lines, it was thus proved that, behind a screen of sulphate of quinine, iodide of silver was affected only by the luminous rays about the centre of the indigo portion of the spectrum, whilst bromide of silver was affected by the green, blue, and some of the indigo rays. It is very likely that a continuance of these experiments would lead to the construction of a photometer capable of measuring the luminous rays ; for although bromide of silver behind quinine is not affected by the red or yellow rays, still it is by the green and blue; and as the proportion of | red, yellow, green, and blue rays is always invariable in white light (or the light would not be white, but coloured), a method of measuring one set of the components of white light would give all the information we want—yjust as in an analysis of a definite chemical compound the chemist is satisfied with an estimation of one or two constituents only, and calcu- lates the others. Methods based upon the foregoing considerations would supply us with what may be termed an absolute photometer, the indication of which would be always the same for the same amount of illumination, requirmg no standard light for comparison; and pending the development of experi- ments which the writer is prosecuting in this direction, he has been led to devise a new and, as he believes, a valuable form of relative photo- meter. A relative photometer is one in which the observer has only to deter- mine the relative illuminating powers of two sources of light, one of which is kept as uniform as possible, the other being the light whose intensity is to be determined. It is therefore evident that the great thing to be aimed at is an absolutely uniform source of light. In the ordinary pro- cess of photometry the standard used is a candle, defined by Act of Par- liament as a “sperm-candle of six to the pound, burning at the rate of 120 grains per hour.’ This is the standard from which estimates of the value of illuminating gas are deduced; hence the terms ‘‘ 12-candle gas,” “‘ 14-candle gas,” &c. In his work on ‘ Gas Manipulation,’ Mr. Sugg gives a very good account of the difficulties which stand in the way of Luminous Intensity of Light. 361 obtainmg uniform results with the Act-of-Parliament candle. A true sperm-candle is made from a mixture of refined sperm with a small pro- portion of wax, to give it a certain toughness, the pure sperm itself bemg extremely brittle. The wick is of the best cotton, made up into three cords and plaited. The number of strands in each of the three cords composing the wick of a six-to-the-pound candle is seventeen, although Mr. Sugg says there does not appear to be any fixed rule, some candles having more and others less, according to the quality of the sperm. Sperm-candles are made to burn at the rate of one inch per hour, and the cup should be clean, smooth, and dry. The wick should be curved slightly at the top, the red tip just showing through the flame, and consuming away without requiring snuffing. ‘To obtain these results, the tightness of the plaiting and size of the wick require careful attention ; and as the quality of the sperm differs in richness or hardness, so must the plaiting and number of strands. A variety of medifying circumstances thus tend to affect the illuminating power of a standard sperm-candle. These difficulties, how- ever, are small compared with those which have resulted from the sub- stitution of paraffin &c. for part of the sperm; and Mr. Sugg points out that candles can be made with such combinations of stearin, wax, or sperm, and paraffin, as to possess all the characteristics of sperm-candles and yet be superior to them in illuminating-power; while, on the other hand, eandles made from the same materials otherwise combined are inferior. When, in addition to this, it is found that candles containing paraffin re- quire wicks more tightly plaited and with fewer strands than those suitable for the true sperm-candle, our readers will be enabled to judge of the almost insurmountable difficulties which beset the present system of photometry. But assuming that the true parliamentary sperm-candle is obtained, made from the proper materials, and burning at the specified rate, its illuminating-power will be found to vary with the temperature of the place where it has been kept, the time which has elapsed since it was made, and the temperature of the room wherein the experiment is tried. The Rev. W. R. Bowditch, in his work on ‘The Analysis, Purification &c. of Coal-gas,’ enters at some length into the question of test-candles, and emphatically condemns them as light-measurers. One experiment quoted by this author showed that the same gas was reported to be 14°63 or 17°36 candle-gas, according to the way the experiment was conducted. The present writer has taken some pains to devise a source of light which should be at the same time fairly uniform in its results, would not vary by keeping, and would be capable of accurate imitation at any time and in any part of the world by mere description. The absence of these conditions seems to be one of the greatest objections to the sperm-candle. It would be impossible for an observer on the continent, ten or twenty years hence, from a description of the sperm-candle now employed, to make a standard which would bring his photometric results into relation 362 Mr. W. Crookes on the Measurement of the with those obtained here. Without presuming to say that he has satis- factorily solved all difficulties, the writer believes that he has advanced some distance in the right direction, and pointed out the road for further improvement. Before deciding upon a standard light, experiments were made to ascer- tain whether the electric current could be made available. Through a coil of platinum wire, so as to render it brightly incandescent, a powerful galvanic current was passed, and its strength was kept as constant as possible by a thick wire galvanometer and rheostat. To prevent the cooling action of air-currents, the incandescent coil was surrounded with glass ; and it was hoped that by employing the same kind of battery, and by varying the resistance so as to keep the galvanometer-needle at the same deflection, uniform results could be obtained. In practice, however, it was found that many things interfered with the uniformity of the re- sults, and the light being much feebler than it was advisable to work with, _ this plan was deemed not sufficiently promising, and it was abandoned. The method ultimately decided upon is the following :—Alcohol of sp. gr. 0°805, and pure benzol boiling at 81° C., are mixed together in the proportion of 5 volumes of alcohol and 1 of benzol. This burning fluid can be accurately imitated from description at any future time and in any country ; and if a lamp could be devised equally simple and invariable, the light which it would yield would, it is presumed, be invariable. This difficulty the writer has attempted to overcome in the followmg manner. A glass lamp is taken of about two ounces capacity, the aperture in the neck being 0°25 inch diameter ; another aperture at the side allows the liquid fuel to be introduced, and, by a well-known laboratory device, the level of the fluid in the lamp can be kept uniform. The wick-holder con- _ sists of a platinum tube 1°81 inch long and 0-125 inch internal diameter. The bottom of this is closed with a flat plug of platinum, apertures being left in the sides to allow free access of spirit. A small platinum cup 0°5 inch diameter and 0°1 inch deep is soldered round the outside of the tube 0°5 inch from the top, answering the threefold purpose of keeping the wick-holder at a proper height in the lamp, preventing evaporation of the liquid, and keeping out dust. The wick consists of fifty-two pieces of hard-drawn platinum wire, each 0:01 inch in diameter and 2 inches long, perfectly straight, and tightly pushed down into the platinum holder, until only 0°1 inch projects above the tube. The height of the burning fluid in the lamp must be sufficient to cover the bottom of the wick- holder: it answers best to keep it always at the uniform distance of 1°75 inch from the top of the platinum wick; a slight variation of level, however, has not been found to influence the light to an extent appre- ciable by our present means of photometry. The lamp with reservoir of | spirit thus ar ranged, with the platinum wires parallel, and their projecting ends level, a light is applied, and the flame instantly appears, formmg a perfectly shaped cone 1°25 inch in height, the point of maximum bril- Luminous Intensity of Light. 363 liancy being 0°56 inch from the top of the wick. The extremity of the flame is perfectly sharp without any tendency to smoke; without flicker or movement of any kind, it burns when protected from currents of air at a uniform rate of 136 grains of liquid per hour. The temperature should be about 60° F., although moderate variations on either side exert no perceptible influence. Bearing in mind Dr. Frankland’s observations on the direct increase in the light of a candle with the atmospheric pres- sure, accurate observations ought to be taken only at one height of the barometer. ‘To avoid the inconvenience and delay which this would occa- sion, a table of corrections should be constructed for each 01 inch variation of barometric pressure. There is no doubt that this flame is very much more uniform than that of the sperm-candle sold for photometric purposes. Tested against a candle, considerable variations in relative illuminating-power have been observed ; but on placing two of these lamps in opposition, no such vari- ations have been detected. ‘The same candles have been used, and the experiments have been repeated at wide intervals, using all customary pre- cautions to ensure uniformity. The results are thus shown to be due to variations in the candle, and not in the lamp. It is expected that whoever may be inclined to adopt the kind of lamp here suggested will find not only that its uniformity may be relied upon, but that, by following accurately the description and dimensions here laid down, each observer will possess a lamp of equivalent and convertible photometric value; so that results may not only be strictly comparable between themselves, but, within slight limits of accuracy, comparable with those obtained by other experimentalists. The dimensions of wick &c. here laid down are not intended to fix the standard. Persons engaged in pho- tometry as an important branch of their regular occupation will be better able to fix these data than the writer, by whom photometry is only occa- sionally pursued as a means of scientific research. Already many improve- ments suggest themselves, and several causes of variation in the light have been noticed. Future experiments may point out how these sources of error are to be overcome; but at present there is no necessity to refine our source of standard light to a greater degree of accuracy than the photo- metric instrument admits of. The instrument for measuring the relative intensities of the standard and other lights next demands attention. The contrivances in ordinary use are well known. Most of them depend on the law in optics, that the amount of light which falls upon a given surface varies inversely with the square of the distance between the source of light and the object illumi- nated. The simplest observation which can be taken is made by placing two sources of light (say, a candle and gas-lamp) opposite a white screen a few feet off, and placing a stick in front of them, so that two shadows of the stick may fall on the screen. The strongest light will cast the strongest shadow; and by moving this light away from the stick, keeping the sha- 364: Mr. W. Crookes on the Measurement of the dows side by side, a position will at last be found at which the two shadows appear of equal strength. By measuring the distance of each light from the screen and squaring it, the product will give the relative intensities of the two sources of light. In practice this plan is not sufficiently accurate to be used except for the roughest approximations; and from time to time several ingenious contrivances, all founded upon the same law, have been introduced by scientific men by which a much greater accuracy is obtained; thus, in Ritchie’s photometer, the lights are reflected on to a piece of oiled paper in a box, and their distances are varied until the two halves of the paper are equally illuminated. In Bunsen’s photometer, which is the one now generally used, the lights shine on opposite sides of a disk of white paper, part of which has been smeared with melted spermaceti to make it more transparent. When illuminated by a front light, the greased portion of the paper will look dark; but if the observer goes to the other side of the paper, the greased part looks the lighter. If, therefore, lights of unequal intensity are placed on opposite sides of a piece of paper so prepared, a difference will be observed ; but by moving one backwards or forwards, so as to equalize the intensity, the whole surface of the paper will appear uniformly illumimated on both sides. This photometer has been modified by many observers. By some the disk of paper is moved, the lights re- maining stationary ; by others the whole is enclosed in a box, and various contrivances are adopted to increase the sensitiveness of the eye, and to facilitate calculation: but in all these the sensitiveness is not greatly aug- mented, as the eye cannot judge of very minute differences of illumination approximating to equality. In 1833 Arago described a photometer in which the phenomena of polarized light were employed. This instrument is fully described, with drawings, in the tenth volume of the ‘ Giuvres complétes de Francois Arago ;’ but the description, although voluminous, is far from clear. The principle of its construction is founded on the law of the square of the cosines, according to which polarized rays pass from the ordinary to the extraordinary image. The knowledge of this law, he says, will not only prove theoretically important, but will further lead to the solution of a great number of very important astronomical questions. Suppose, for ex- ample, that it is wished to compare the luminous intensity of that portion of the moon directly illuminated by the solar rays, with that of the part which receives only light reflected from the earth, called the partie cendrée. — Were the law in question known, the way to proceed would be as follows :— After having polarized the moon’s light, pass it through a doubly refracting crystal, so disposed that the rays, not being able to bifureate, may entirely undergo ordinary refraction. A lens placed behind this crystal will there- fore show but one image of our satellite; but as the crystal, in rotating on its axis, passes from its original position, the second image will appear, and its intensity will go on augmenting. The movement of the crystal Luminous Intensity of Light. 365 must be arrested at the moment when, in this growing extraordinary image, the segment corresponding to the part of the moon illuminated by the sun exhibits the intensity of the ashy part shown by the ordinary image. From these data it is easy to perceive, he says, that the problem is capable of solution. in another part of the same volume, after speaking of the polariscope which goes by his name, Arago writes:—‘I have now arrived at the geueral principle upon which my photometric method is entirely founded. The quantity (I do not say the proportion)—the quautity of completely polarized light which forms part of a beam partially polarized by reflection, and the quantity of light polarized rectangularly which is contained in the beam transmitted under the same angle, are exactly equal to eacli other. The reflected beam, and the beam transmitted under the same angle by a sheet of parallel glass, have in general very dissimilar intensities ; if, how- ever, we examine with a doubly refracting crystal first the reflected and then the transmitted beam, the greatest difference of intensity between the ordinary and the extraordinary images will be the same in the two cases, because this difference is precisely equal to the quantity of polarized light which is mixed with the common light.” In Arago’s ‘Astronomy,’ the author again describes his photometer in the following words :—‘‘I have constructed an apparatus by means of which, upon operating with the polarized image of a star, we can succeed in at- tenuating its intensity by degrees exactly calculable after a law which I have demonstrated.’’ It is difficult to obtain an exact idea of this instru- ment from the description given; but from the drawings it would appear to be exceedingly complicated and to be different in principle and construction from the one now about to anes be described. The present photometer has this in com- (++) mon with that of Arago, as well as with those de- D ¢ scribed in 1853 by Bernard *, and in 1854 by Babinet f, that the phenomena of polarized light are used for effect- a ing the desired end; but it is believed that the present arrangement is quite new, and it certainly appears to answer the purpose in a way which leaves little to be é desired. The instrument will be better understood if -)K) the principles on which it is based are first described. Fig. 1 shows a plan of the arrangement of parts,not = 1 ——<——+—_ drawn to scale, and only to be regarded as an outline sketch to assist in the comprehension of general prin- ciples. Let D represent a source of light. This may be a white disk of porcelain or paper illuminated by any artificial or natural light. C represents a similar (7) (>) white disk, likewise illuminated. It is required to com- * Comptes Rendus, April 25, 1853. + Proceedings of the British Association, Liverpool Meeting, 1854. [=| 366 Mr. W. Crookes on the Measurement of the pare the photometric intensities of D and C. (It is necessary that neither D nor C should contain any polarized light, but that the light coming from them, represented on each disk by the two lines at right angles to each other, forming a cross, should be entirely unpolarized.) Let H represent a double refracting achromatic prism of Iceland spar; this will resolve the disk D into two disks d and d', polarized in opposite directions; the plane of d being, we will assume, vertical, and that of d' horizontal. The prism . H will likewise give two images of the disk C ; the image ¢ being polarized horizontally, and c! vertically. The size of the disks D, C, and the sepa- rating power of the prism H, are to be so arranged that the vertically polarized image d, and the horizontally polarized image ¢, exactly overlap each other, forming, as shown in the figure, one compound disk ¢ d, built up of half the light from D and half that from C. The measure of the amount of free polarization present in the disk ¢ d will give the relative photometric intensities of D and C. The letter I represents a diaphragm with a circular hole in the centre, just large enough to allow the compound disk e d to be seen, but cutting off from view the side disks c’, d’. In front of the aperture in I is placed a piece of selenite, of appropriate thickness for it to give a strongly con- trasting red and green image under the influence of polarized light. K is a doubly refracting prism, similar in all respects to H, placed at such a distance from the aperture in I that the two disks into which I appears to be split up are separated from each other, as at g,r. If the disk e d con- tains no polarized light, the images g, 7 will be white, consisting of oppo- sitely polarized rays of white light; but if there is a trace of polarized light in ¢ d, the two disks g,7 will be coloured complementarily, the contrast between the green and the red being stronger in preportion to the quantity of polarized light ined. _ The action of this arrangement will be readily evident. Let it be sup- posed, in the first place, that the two sources of light, D and C, are exactly equal. They will each be divided by H into two disks d! d and ¢ c’, and the two polarized rays of which ¢ d is compounded will also be absolutely equal in intensity, and will neutralize each other, and form common light, no trace of free polarization being present. In this case the two disks of light, g, 7, will be colourless. Let it now be supposed that one source of light (D, for instance) is stronger than the other (C). It follows that the two images d’, d will be more luminous than the two images ¢, ec’, and that the vertically polarized ray d will be stronger than the horizontally polarized ray c. The compound disk ¢ d will therefore shine with partially polarized light, the amount of free polarization being im exact ratio with the photometric intensity of D over C. In this case the image of the selenite plate in front of the aperture I will be divided by K into a red and a green disk. Fig. 2 shows the instrument fitted up. A is the eyepiece (shown in enlarged section at fig. 3); G Bisa brass tube, blacked inside, having a Luminous Intensity of Light. 367 piece (shown separate at DC) slipping into the end B. The sloping sides, DB, BC, are covered with a white reflecting surface (white paper or finely ground porcelain), so that when DC is pushed into the end B, one white surface D B may be illuminated (as in fig. 2) by the candle, and the other surface BC by the lamp. If the eyepiece A is removed, the observer, looking down the tube G B, will see at the end a luminous white disk divided vertically into two parts, one half being illuminated by the candle E, and the other half by the lamp F. By moving the candle E, for in- stance, along the scale, the illumimation of the half D B can be varied at will, the illumination of the other half remaining stationary. The eyepiece A (shown enlarged at fig. 3) will be understood by refer- ence to fig. 1, the same letters representing similar parts. At L isa lens to collect the rays from D B C (fig. 2), and throw the image into the proper part of the tube. At M is another lens so adjusted as to give a sharp image of the two disks into which I is divided by the prism K. The part N is an adaptation of Arago’s polarimeter; it consists of a series of thin plates of glass capable of moving round the axis of the tube, and furnished with a pointer and graduated are (shown at A G, fig. 2). By means of this pile it is possible to partially polarize the rays coming from the illuminated disks in one or the other direction, and thus bring to the neutral state the partially polarized beam e d (fig. 1), so as to get the images g,7 free from colour. It is so adjusted that when at the zere-point it produces an equal effect on both disks. } The action of the instrument is as follows. The standard lamp being placed on one of the supporting pillars which slide along the graduated stem (fig. 2), it is adjusted to the proper height, and moved 368 Mr. W. Crookes on the Measurement of the along the bar to a convenient distance, depending on the intensity of the light to be measured: the whole length being a little over 4 feet, each light can be placed at a distance of 24 inches from the disk. The flame is then sheltered from currents of air by black screens placed round, and the light to be compared is fixed in a similar way on the other side of the instrument. The whole should be placed in a dark room, or surrounded with non- reflecting screens; and the eye must also be protected from the direct rays of the two lights. On looking through the eyepiece two bright disks will be seen, probably of different colours. Supposing F represents the standard flame, and E the light to be compared with it, the latter must now be slid along the scale until the two disks of light, seen through the eyepiece, are about equal in tint. Equality of illumination is easily obtained ; for as the eye is observing two adjacent disks of light, which pass rapidly from red- green to green-red through a neutral point of no colour, there is no diffi- culty in hitting this point with great precision. It has been found most convenient not to attempt to get absolute equality in this manner, but to move the flame to the nearest inch on one side or the other of equality. The final adjustment is now effected at the eye-end by turning the polari- meter one way or the other up to 45°, until the images are seen without any trace of colour. This will be found more accurate than the plan of relying entirely on the alteration of the distance of the flame along the scale ; and by a series of experimental adjustments the value of every angle through which the bundle of plates is rotated can be ascertained once for all, when the future calculations will present no difficulty. Squaring the number of inches between the flames and the centre will give their ap- proximate ratios ; and the number of degrees the eyepiece rotates will give the number to be added or subtracted in order to obtain the necessary accuracy. ; : The delicacy of the instrument is very great. With two lamps, each about 24 inches from the centre, it is easy to distinguish a movement of one of them to the extent of 0:1 inch to or fro; and by using the polari- meter an accuracy considerably exceeding this can be attained. The employment of a photometer of this kind enables us to compare lights of different colours with one another, and leads to the solution of a problem which, from the nature of their construction, would be beyond the powers of the instruments in general use. So long as the observer, by the eye alone, has to compare the relative intensities of tint-surfaces, respectively illuminated by the lights under trial, it is evident that, unless they are of the same tint, it is impossible to obtain that equality of illu- mination in the instrument which is requisite for a comparison. By the unaided eye one cannot tell which is the brighter half of a paper disk, illuminated on one side with a reddish, and on the other with a yellowish light ; but by using the above-described photometer the problem becomes practicable. For instance, on reference to fig. 1, suppose the disk D were illuminated with light of a reddish colour, and the disk C with greenish Luminous Intensity of Light. 369 light, the polarized disks d', d would be reddish and the disks ¢, e! greenish, the central disk ec d being of the tint formed by the union of the two shades. The analyzing prism K, and the selenite disk I, will detect free polarization in the disk c¢ d, if it be coloured, as readily as if it were white; — the only difference being that the two disks of light, g, 7, cannot be brought to a uniform white colour when the lights from D and C are equal in intensity, but will assume a tint similar to that of ed. When the con- trasts of colour between D and C are very strong—when, for instance, one is bright green and the other scarlet—there is some difficulty in estimating the exact point of neutrality ; but this only diminishes the accuracy of the comparison, and does not render it impossible, as it would be according to other systems. No attempt has been made in these experiments to ascertain the exact value of the standard spirit-flame in terms of the Parliamentary sperm- candle. Difficulty was experienced in getting two lots of candles yielding light of equal intensities; and when their flames were compared between themselves and with the spirit-flame, variations of as much as 10 per cent. were sometimes observed in the light they gave. Two standard spirit- flames, on the other hand, seldom showed a variation of 1 per cent., and had they been more carefully made they would not have varied 0-1 per cent. This plan of photometry is capable of far more accuracy than the pre- sent instrument will give. It can scarcely be expected that the first instrument of the kind, made by an amateur workman, should possess equal sensitiveness with one in which all the parts have been skilfully made with special adaptation to the end in view. ADDENDUM to description of Photometer. By W. Crooxxss, F.R.S. Received December 17, 1868. When I wrote that. other experimentalists had already made use of the phenomena of polarized light for measuring the intensity of light, I was not aware that a photometer already existed in which the principle of the one above described was adopted. By the kindness of Sir Charles Wheatstone I have, within the last few days, been enabled to experiment with a photometer devised by M. Jamin, * founded on the same principle. I have not yet succeeded in finding a printed account of this instrument, but a written one was supplied with it, and having been allowed to take it to pieces its construction is evident. It consists, first, of a Nicol’s prism, then of an achromatized doubly refracting prism; next, of two plates of quartz, cut oblique to the axis, reversed, and superposed ; and finally, at the eye-end, of a second Nicol’s prism. As in my instrument, each of the two lights to be compared split 370 Prof. Maskelyne on the Mineral Constituents (Apr. 8, into two images; the ordinary ray from one is superposed on the extra- ordinary ray from the other, and the compound beam so produced is ex- amined further. The means adopted to effect the desired object are, however, very different, being much simpler in my method, whilst the re- sults are superior. In Jamin’s photometer the light which eventually reaches the eye is comparatively feeble, and the field of view is very restricted; the objects themselves under comparison are seen direct through the instrument with- out the interposition of a telescopic arrangement, and no means are taken to prevent extraneous light from entering. The deficiency of light makes observations by artificial light difficult, whilst when examining objects illuminated by diffused or direct sunlight the eye is fatigued and bewildered by the variations of shape, size, and colour assumed by the overlapping objects seen through the instrument. In the photometer described in the former part of this paper, there is abundance of light, and the observation is made upon two luminous disks, which are magnified by means of a lens, so as to appear close to the eye. It will be found much easier to detect differences of colour between these two adjacent disks than to observe the presence or absence of the coloured fringes in the central portion of the field of Jamin’s photometer. In the former case the eye has nothing to observe but two uniform and purely coloured disks, changing from red- green to green-red through an intermediate stage of neutrality ; in the latter case the eye has to detect the stage of neutrality in the central por- tion of the field, where the two images under comparison overlap, the at- tention being distracted, and the sensitiveness of the eye weakened, by the brilliantly coloured fringes which cross the adjacent objects. A. direct comparison of the two instruments for sensitiveness shows that the present photometer will detect much more minute differences of in- tensity than Jamin’s will, whilst it will work with tolerable accuracy in a light too feeble to give any results with the latter instrument. , April 8, 1869. Lieut.-General SABINE, President, in the Chair. The following communications were read :— I. “Preliminary Notice on the Mineral Constituents of the Breiten- bach Meteorite.” By Professor N. Story Masxenyne, M.A. Communicated by Professor Warineron W. Suyru, F.R.S. Re- ceived March 2, 1869. This meteorite, which belongs to the rare class intermediate between meteoric irons or siderites and meteoric stones or aérolites (a class to | 1869. ] of the Breitenbach Meteorite. 371 which I applied some years since the term siderolites), was found in Brei- tenbach in Bohemia. : It is a spongy metallic mass, very similar to the siderolite of Rittersgriin in Saxony, the hollows in the iron being filled by a mixture of crystalline minerals. These minerals are two in number; and the present notice deals with these two minerals. 1. One of them is of a pale-green colour, crystallizing in the prismatic system, and presenting at once the formula of an augitic mineral and a crystalline form nearly approximating to that of olivine. Dr. Viktor von Lang, when my colleague at the British Museum, measured some mero- hedral crystals of this mineral, and obtained for its elements a:b6:c=0°8757 : 0°8496 : 1, 110.010 = 44 8 101.100 = 41 11 104.100 74 3 GF]. 0.80 40 16 The analysis of this green mineral gave, from 0°4127 grm.,— per cent. Oxygen-ratios. Equivalent ratios. Site ee O-2315 56°101 29°920 1°87 MPAeMESIAMHsieie 0-1247 30°215 12°087 ol } 1°88 Ferrous oxide .... 06°0560 13°583 3°018 0°37 0°4122 99-899 results which correspond very nearly with an Enstatite of the formula : (Mg, Fe;) Si0,. The specific gravity is 3°23. It is remarkable that of the minerals presenting the general formula M Si0,, where M stands for one or more metals of the calcium and magnesium groups, we are acquainted with two anorthic types (Rhodonite and Ba- bingtonite); three oblique types, those, namely, of Wollastonite, of Horn- blende, and of Augite; two prismatic types, those, namely, of Enstatite and Anthophyllite, homceomorphous with the oblique Augites and Horn- blendes ; and to these we shall have now to add (if the measurements of Dr. Lang shall prove to be distinct from those of Enstatite) a third, in the green mineral under description. Of these, the prismatic types are essentially those of the magnesian group. The rest, with the exception of the calcium silicate (Wollastonite), are types belonging to the mixed groups. 2. The other mineral is one of very great interest. It is, in short, silica crystallized in forms and in a system distinct from quartz, and pos- 372 Mr. C.Schorlemmer on the Derwatives of Propane. {Apr. 8, sibly is tridymite. In bulk it forms about a third part of the mixed crystalline mass. The crystals are very imperfect, and are twinned: but there are two cleavages parallel to the planes of a prism of about 119°; and, on looking through a plane that is perpendicular to this zone, it is seen that the crystal is biaxial. The normal to this plane is parallel to the second mean line, the optical character being negative. A section made for examination in the microscope showed two small crystals in which light traverses the section with equal brilliancy during its rotation between crossed Nicol prisms. This, and possibly a similar case recorded by Vom Rath, seems to result from the section being cut parallel to a composite portion of the crystal. The analysis of the mineral gave, by distillation of the silica as silicic difluoride, and subsequent determination as potassic fluosilicate, 97°43 per cent. of silica, the remainder being oxide of iron and lime. Thus 0°3114 grm. gave : per cent. Silica 2 22m 3a ne, 03034 97°43 Ferric oxide...... 0°0035 1°124 Lime 32:0... 22> 10-0018 0°578 0°3087 99-132 A second analysis gave 99°21 per cent. silica, 0°79 of residue. Its specific gravity, as determined from a very small amount of the mi- neral picked under the microscope, was 2°18 ; a second determination made on a larger amount gave the value 2°245. That of tridymite is 2°295 to 2:3. This may be taken as evidence that the mineral is not quartz, the specific gravity of which is 2°65. Vom Rath’s experiments were made on a rather less pure form of tridymite. There can be no doubt from these results, further details of which shall be shortly laid before the Society, that this mineral is silica in the form of its allotropic condition and lower density. It may possibly be the mineral to which Vom Rath has given the name of Tridymite; the crystalline system, however, of Tridymite, as given by Vom Rath, does not accord with the above facts. II. “On the Derivatives of Propane (Hydride of Propyl).” By C. ScHORLEMMER. Communicated by Prof. Sroxns, Sec. R.S Received March 5, 1869. At the time when I commenced this investigation, the existence of normal propyl alcohol was very doubtful. According to Chancel*, this body is found in the fusel-oil from the mare of grapes; but Mendelegeffy tried in vain to isolate it from a sample of this oil which he had obtained * Compt Rend. vol. xxxvii. p. 410. t Zeitschrift fir Chemie, 1868, p. 25. 1869.] Mr. C.Schorlemmer on the Derivatives of Propane. 373 from Chancel himself. Several attempts to prepare the normal alcohol by synthesis failed. Thus Linnemann and Siersch* tried to obtain it by converting acetonitril into propylamine, by means of hydrogen in the nascent state, and decomposing the hydrochlorate of this base with silver. nitrite ; but the alcohol thus formed was found to be the secondary one. The same compound was obtained by Butlerow and Ossokint, by acting upon ethylene iodohydrine, C,H, | . a with zinc methyl, in order to re- place iodine by methyl. Now as in both cases, according to theory, the normal or primary alcohol ought to have been formed, and as we have no explanation why instead of this compound the secondary alcohol was obtained, Butlerow and Ossokin believe that the normal propyl-alcohol cannot exist. Not agreeing with this view, I was led to an investigation of this subject, the results of which I have the honour to lay before the Society. My reasoning was as follows :—It appears, as the most probable theory, and which is now accepted by most chemists, that the four combining powers of the carbon atom have the same value. If so, only one hydro- carbon having the composition C, H, can exist. This propane must be formed by replacing the iodine in the secondary propyl iodide, by hydro- gen, and subjecting the hydrocarbon thus obtained to the action of chlo- rine, by which primary propyl! chloride must be formed in accordance with the behaviour of other hydrocarbons of the same series. I soon found that my theory was correct ; and in a short note, which I published in ‘ Zeitschrift fiir Chemie’ (1868, p. 49), I stated that I had obtained the normal propyl! alcohol by this method. At the same time, Fittig proved that it was contained in fusel-oilst, and lately Linnemann prepared it synthetically from ethyl-compounds by converting acetonitrile (ethyl cyanide) into propionic a and acting upon this body with nascent hydrogen§. The propane which I used in my researches was obtained by acting upon isopropyl iodide with zinc turnings and diluted hydrochloric acid. A continous evolution of gas takes place if the flask containing the mix- ture is kept cold. If it is not cooled down a violent reaction soon sets in. The gas always contains vapour of the iodide, even if it has been evolved very slowly. In order to purify it as much as possible, it was washed with Nordhausen sulphuric acid, with a mixture of nitric and sulphuric acids and with caustic soda solution. As a gas-holder I used a tubulated bell-jar, which was suspended in a larger inverted one, filled with a concentrated solution of common salt. When a sufficient quantity of gas had collected, chlorine was passed into * Annalen Chem. Pharm. vol. exliv. p. 137. t Ibid. vol. exlv. p. 257. + Zeitschrift fir Chemie, 1868, p. 44. § Annalen Chem. Pharm. vol. cxlyiii. p. 251. won: XVII. QF 374 Mr. C.Schorlemmer on the Derivatives of Propane. (|Apr. 8, it, care being taken not to have it inexcess. In diffused daylight substitu- tion-products were formed, which collected as an oily layer on the salt solution. Alternately more propane and chlorine were passed into the apparatus, until it was nearly filled with the excess of propane and vapours of the most volatile substitution-products. The latter were con- densed by passing the gas into a receiver surrounded by a freezing-mix- ture. To collect the liquid chlorides which were contained in the gas- holder, the tubulus of the bell-jar was closed with cork, which was provided with a wide short glass tube, open at both ends, and so much salt solution put into the gas-holder that the chlorides entered this tube, from which they could easily be removed with a pipette. By repeating this process several times, a quantity of chlorine compounds, sufficient for further investigation, was obtained. This was washed with water, dried over caustic potash, and distilled. The liquid commenced to boil at 42° C., the boiling-point rising towards the end above 200°C. By fractional distillation, a comparatively small quantity of a liquid was obtained, which boiled at 42°-46°, and consisted of the primary propyl chloride, C, H, Cl. 0:0975 of this chloride gave 0°1730 silver chloride, and 0-005 silver, corresponding to 0:044 chlorine. Calculated for C, H, Cl. Found. 452 per cent. Cl. 45:5 per cent. Cl. In order to prove that this body was really the normal chloride, it had to be converted into the alcohol. For this purpose I used that portion of the chlorides which, after repeated distillation, boiled below 80° C. It was heated in sealed tubes with potassium acetate and glacial acetic acid for several hours to 200° C., and thus converted into the acetate, a light colourless liquid, possessing the characteristic odour of the acetic ethers. I did not endeavour to obtain this ether in the pure state, as this could have been effected only with great loss of material, but converted it at once into the alcohol, by heating it with a diluted solution of potash, in sealed tubes, up to 120° C. After cooling, the contents of the tubes were distilled and rectified. A portion of it was- oxidized with a cold diluted solution of chromic acid. No gas was evolved, but a strong smell of aldehyde was perceived, which disappeared on adding more chromic acid. On distilling to dryness, an acid liquid was obtained, which was neutralized with sodium carbonate. The solution was evaporated to dry- ness, and the residue distilled with a quantity of sulphuric acid, sufficient to — liberate about one-fourth of the acid. The residue in the retort was_again distilled with the same quantity of sulphuric acid, and, by repeating this process, the acid was obtained in four fractions. Each of these was con- verted into the silver-salt by boiling with silver carbonate. The silver-salts crystallized from the hot saturated solution in small shining needles, which were grouped in stars and feathers. These were dried, first, over sulphuric acid, afterwards in the steam-bath, and the silver determined by ignition. 1869.] Mr. C.Schorlemmer on the Derivatives of Propane. 375 per cent. Fraction (1) 0°2350 gave 0:1404 silver=59°74 > = = wh i | ae ee eee eee ee mation. Proce Roy. Soc. Vol XVIL Plate IX. -diurnal Variation of. the Decl THOSE HLL LEELA eT JUV NUIHIOHONEAIOAIP UTE PUVA UE EN TT EE EE, ied BZ a aL PAT et TTT A a Oe Pap BAL LL PELL si LTP fl CLSL LPN eet LCE PASTY teat PASTS eT TT Pea ist Howrs 4stromnomuiucal Z i UE SE SUUDEDREEES AUDEROERDERODEUPANEROEE ELAN eet ELE ATT UAT PLETE ee TAT A i-annual Inequality of the Solar Whipple. Demi- = ~ ~ Rokeby & 1869.] Lieut. Rokeby on Magnetic Observations. 397 in a state of high chemical tension, will, by their tendency to develope those . vibrations, either determine the explosion of that substance, or at any rate greatly aid the disturbing effect of mechanical force suddenly applied, while, in the instance of another explosion, which developes vibratory im-_ pulses of different character, the mechanical force applied through its agency has to operate with little or no aid, greater force, or a more power- ful detonation, being therefore required in the latter instance to accom- plish the same result. Instances of the apparently simultaneous explosion of numerous distinct and even somewhat widely separated masses of explosive substances (such as simultaneous explosions in several distinct buildings at powder-mills) do not unfrequently occur, in which the generation of a disruptive impulse by the first or initiative explosion, which is communicated with extreme rapidity to contiguous masses of the same nature, appears much more likely to be the operating cause, than that such simultaneous explosions should be brought about by the direct operation of heat and mechanical force. A practical examination has been instituted into the influence which the explosion of gun-cotton through the agency of a detonation, exercises upon the nature of its metamorphosis, upon the character and effects of its explosion, and upon the uses to which gun-cotton is susceptible of application. Ill. “ Results of Magnetical Observations made at Ascension Island, Latitude 7° 55! 20" South, Longitude 14° 25! 30” West, from July 1863 to March 1866.” By Lieut. Roxesy, R.M. Re- duced by G. M. Wuiprrz, Magnetical Assistant at the Kew Observatory. Communicated by B. Stewart, LL.D. Received March 11, 1869. On leaving England for Ascension Island in May 1862, Lieut. Rokeby was supplied by General Sabine with the following instruments for the purpose of making observations of magnetical variation and intensity, viz. :— A portable declinometer and unifilar for absolute observations of declina- tion and horizontal intensity, a Barrow’s dip-circle (No. 24), a differential declinometer, and a differential bifilar. The differential declinometer and the bifilar were erected at George Town, Ascension, in August 1862, and bihorary observations commenced ; but in consequence of instability in the supports of the instruments, caused pro- bably by the shifting of the volcanic cinders which formed the ground at the observing-station, the observations made exhibit frequent discrepancies. The whole of the bifilar observations, and all the differentiai declinometer observations prior to June 1864, have therefore been omitted from the present discussion. 398 Lieut. Rokeby on Magnetic Observations. _—_ [ Apr. 15, These observations were discontinued in June 1866, when Lieut. Rokeby left the Island. Observations of absolute horizontal force and dip were made on the Green Mountain, Ascension, once every mouth from July 1863 to March 1866, two months in 1865 excepted. Observations were not made with the portable declinometer. Observations of Horizontal Force and Dip. The horizontal, vertical, and total forces (Table No. 1) are calculated to English measure ; one foot, one second of mean solar time, and one grain being assumed as the limits of space, of time, and of mass. The vertical and total forces are obtained from the absolute measures of the horizontal force and the dip. The observations of dip (Table No. 1) were made in every instance save one with the needle marked A 2. For the observations of defiection and vibration taken each month for absolute measure of horizontal force, the same magnet (collimator 5) has always been employed. The moment of inertia of the magnet, with its stirrup for different de- grees of temperature, and the coefficients in the corrections required for the effects of temperature and of terrestrial magnetic induction on the magnetic moment of the magnet, were determined in 1858 at the Kew Observatory by the late Mr. Welsh. That these corrections held good in 1862 was proved by the agreement of the horizontal force obtained at Kew with this instrument previous to its departure, with the value of the force determined by the observatory unifilar. The moment of inertia of the magnet with its stirrup is 5°3828 at 60° Fahr. The induction-coefficient »=0-°000252. The correction for error of graduation of the deflection-bar at 1:0 foot is 0:00000 foot, and at 1°3 foot 0:00003 foot. The formula used for determining the temperature correction was q(é.—35°) +9! (€—35°)’, where é, is the observed temperature, 35° F. being the adopted standard temperature. The values of g and q’ for the mene used are respectively 0:00011035 and 0:000000581. | The observed times of vibration have been corrected for rate of chrono- meter when it has exceeded five seconds per day. A correction has also been applied for the effect of torsion on the suspending thread. The initial and terminal semiares of vibration have always been less than 30', consequently no correction was requisite on this account. The time of one vibration is derived from the mean of twelve observations of the time of 100 vibrations. 1869. ] Lieut. Rokeby on Magnetic Observations. 399 The angles of deflection given are each the mean of two determinations. In deducing from these observations the ratio and product of the mag- netic moment m of the magnet, and the earth’s horizontal magnetic intensity X, the induction- and temperature-corrections have always been _ applied. In calculation of the ratio = the third and subsequent terms of the Q y stant P was found to be —0°00291, by the mean of ten determinations ob- tained each from six pairs of deflection-observations at distances 1°0 and 1-3 foot. series ] +t +&c. have always been omitted. The value of the con- 2a : ‘ ; The mean of the values of x derived from deflection-observations at the distances 1-0 foot and 1:3 foot has been used in calculating the measure of horizontal force. Observations made with the Differential Declinometer. Observations were made of the scale-reading of the differential declino- meter at 3 a.m., and hourly from 6 a.m. to midnight, daily, from December 1863 to June 1865, from which date to the conclusion of the series the 3 A.M. observations were discontinued. The observations from the commencement until May 1864 were found on inspection to be valueless for the purposes of reduction, for the reason assigned in the introduction. The two years’ records, June 1864 to 1866, were treated according to the method employed by General Sabine in the reduction of declination-ob- servations. In the first place, hourly means were taken for each month. All ob- servations which vary from these means to a greater extent than 4’-0 were then rejected, and new means taken of the unrejected observations. The mean reading for each month was then computed; finally, the hourly means were subtracted from the monthly means. Table 2 shows these differences as derived from the mean of two years’ observations, excepting in the case of 15 hours, which is the result of one year only. In the Table, the sign + represents the north pole of the magnet to the east of the mean position, and the sign — that it was to the west of the - mean. . At the bottom of the Table semiannual and annual means are given, and these means are exhibited in the form of curves in the diagram accompany- ing the paper. 3 Figure 1 shows the differences of the semiannual and annual means from the normal position, which is represented by the straight horizontal line. . : In figure 3 the annual mean is represented as a straight line, and the 400 - Messrs. Carpenter and Brady on _ [Apr. 22, curves show the deviations of the semiannual means from it. In both figures the curyes between twelve and fifteen hours and fifteen and eighteen hours are interpolated. Figures 2 and 4 are copied from General Sabine’s St. Helena Observa- tions, vol. i1., and show the similarity between the movements of the mag- net at Ascension and St. Helena. The Tables annexed to this Paper are preserved for reference in the Archives. April 22, 1869. JOSEPH PRESTWICH, Esq., Vice-President, in the Chair. Alphonse DeCandolle, of Geneva, Charles Eugéne Delaunay, of Paris, and Louis Pasteur, of Paris, were proposed for election as Foreign Members, and notice was given from the Chair that these gentlemen would be ballotted for at the next Meeting. The following communications were read :— I. “ Description of Parkeria and Loftusia, two gigantic Types of Arenaceous Foraminifera.” By Dr. Carpenter, V.P.R.S., and H. B. Brapy, F.L.S. Received March 18, 1869. (Abstract.) The Authors of this Memoir commence by referring to the separation of the series of Arenaceous Foraminifera from the Imperforate or Porcel- Janous, and from the Tubular or Vitreous, first distinctly propounded in Dr. Carpenter’s ‘Introduction to the Study of the Foraminifera’ (1862), on the basis of the special researches of Messrs. Parker and Rupert Jones ; who had pointed out that whilst there are several genera in some forms of which a cementation of sand-grains into the substance of the calcareous shell is a common occurrence, there are certain genera in which a “test”’ formed entirely of an aggregation of sand-grains takes the place of a cal- careous shell; and that these genera constitute a distinct Family, to which important additions might probably be made by further research. The propriety of this separation of the 4renacea from the calcareous: shelled Foraminifera has been fully recognized by Prof. Reuss, the highest Continental authority upon the group; who had come to accept the prin- ciple laid down in Dr. Carpenter’s successive Memoirs (Phil. Trans. 1856— 1860), that the texture of the shell is a character of fundamental im- portance in the classification of this group, the plan of growth (taken by M.d’Orbigny as his primary character) being of very subordinate value ; and who had, on this basis, independently worked out a Systematic Ar- rangement of the entire group, which presents a most remarkable cor- respondence with that propounded by Dr. Carpenter and his coadjutors. And their anticipation of important additions to the Arenaceous series has é 1869. ] two gigantic Types of Foraminifera. — 401 been fully borne out, on the one hand by the discovery of several most remarkable new forms at present existing at great depths in the Ocean, which has been made by the dredgings of M. Sars, Jun., and these of the ‘Lightning’ Expedition, and on the other by the détermination of the . real characters of two fossils, one of the Cretaceous, and the other probably of the earlier Tertiary period, which prove to be gigantic examples of the same type. ; The first of these, discovered by Prof. Morris more than twenty years ago in the Upper Greensand near Cambridge, was long supposed to be a Sponge; but his more recent discovery of two specimens which had been but little changed by fossilization, led him to suspect their Foraminiferal character ; and this suspicion has been fully confirmed by the careful ex- amination made of their structure by Dr. Carpenter, to whom he committed the inquiry, and by whom, with his concurrence, the name Parkeria was assigned to the geuus. The second, which was obtained by the late Mr. W. K. Loftus from “a hard rock of blue marly limestone”? between the N.E. corner of the Persian Gulf and Ispahan, bears so strong a resem- blance in its general form and mode of increase to the genus Alveolina, that its Foraminiferal character was from the first recognized by the discoverer ; but as all the specimens brought by Mr. Loftus had undergone considerable alteration by fossilization, their minute structure, though carefully studied by means of transparent sections, could not in the first instance be satisfac- torily made out. When, however, Dr. Carpenter’s investigation of Parkeria, with the full advantage of specimens but little changed by fossilization, revealed the very remarkable plan of its structure, the investigation of this type was resumed by Mr. Brady (who assigned to it the name Loftusia), with the new light thence derived: for as transparent sections of infiltrated Parkerig furnish a middle term of comparison between specimens of the same type which retain their original character, and transparent sections of infiltrated Loftusie, the last-mentioned can now be interpreted by reference to the preceding; so that the obscurities which previously hung over their minute structure have been almost entirely dissipated.—The de- scription of the structure of Parkeria in this Memoir is by Dr. Carpenter, and that of the structure of Loftusia by Mr. H. B. Brady; but each has gone over the work of the other, and can testify to its correctness. The specimens of Parkeria which have been collected by Prof. Morris* are spheres varying in diameter from about 3-4ths of an inch to about 13 * Since this Memoir was completed, the Author has learned that Mr. Harry Seeley, of Cambridge, has collected several specimens of this type, and has been studying it inde- pendently with a view to publication. And Mr. Henry Woodward has placed in his hands a specimen from the Upper Greensand in the Isle of Wight, which is not less than 21 inches in diameter. It is interesting to remark that the ‘‘ nucleus” of a smaller specimen from the same locality consists of a considerable number of chambers arranged in a spire, the structure of its concentric spherical ee being exactly the same as in the specimens described in the text. 402 Messrs. Carpenter and Brady on [Apr. 22, inch. The character of their external surface differs considerably in dif- ferent individuals; but the Author gives reason for believing that it was originally tuberculated, like a mulberry, and that the departures from this have been the result of subsequent abrasion. The entire sphere is com- posed of a great number of concentric layers, all of which, except the inner- most, are arranged with very considerable regularity around a central ‘‘ nu- cleus,” which consists of five chambers, disposed in rectilineal sequence, thus unmistakeably indicating the Foraminiferal character of the organism, which might otherwise have remained in doubt, en account of the entire divergence from any known type presented in the structure of the concen- tric layers. The first of these layers is moulded (as it were) on the exterior of the nucleus, and partakes of its elongated form; but the parts of every additional exogenous layer are so arranged as to bring about a gradual approximation to the spherical form, which is afterwards maintained with great constancy. Each layer may be described as consisting of a lamella of “‘labyrinthic structure”’ (that is, of an assemblage of minute cham- berlets, whose cavities communicate freely with one another), separated from the contiguous lamelle by an “interspace,” which is traversed by ‘‘ radial tubes,’ that pass from each lamella to the one external to it. All these structures, in common with the chamber-walls and septa of the “nucleus,” are built up by the aggregation of sand-grains of very uniform size. These sand-grains are found to consist of Phosphate of lime; and they seem to be united by a cement composed of Carbonate of lime, which was probably exuded by the animal itself. Although there is a very general uniformity in the thickness of the successive layers, the pro- portion of their several components varies considerably in different parts of the sphere. In those which immediately surround the nucleus, the solid lamellee, which are composed of labyrinthic structure, are compara- tively thin; whilst the interspaces which separate them from one another are very broad, so that the radial tubes which traverse these interspaces are very conspicuous. As we pass outwards, we find the labyrinthic lamellz increasing in thickness, whilst the breadth of the interspaces diminishes in the same degree, until we meet with layers in which the interspaces are almost entirely replaced by labyrinthic structure. With this increased development of the labyrinthic structure in the concentric lamelle themn- selves, we find it extending between one lamella and another, as an invest- ment to the radial tubes; thus forming “radial processes”? of a sub- conical form, which occupy a considerable part of what would otherwise — be the interspaces between the successive lamelle. Still every lamella is separated from that which invests it (except where brought into con- nexion with it by its radial processes) by a system of cavities, which are in free communication with each other, and which may be collectively de- signated the “‘interspace-system ;”’ and from this system the labyrinthic structure of the investing lamella is entirely cut off by an impervious wall, which bounds it upon its énner side ; whilst its chamberlets open freely upon 1869. | two gigantic Types of Foraminifera. 403 the outer side of the lamella,.into what, when it is newly formed, is the surrounding medium, but, when it has itself been invested by another layer, into its ‘‘interspace-system.’’—In the larger of the two non-infiltrated specimens which have furnished the materials for the present description, - the number of concentric layers is 40, and their average breadth about 1-65th of an inch. The Author discusses the mode in which this composite structure was formed ; and comes to the conclusion that the production of each new layer was probably accomplished by the instrumentality of the sarcodic substance, which not only filled the chamberlets of the preceding layer, but projected beyond it; that the radial processes were first built up like the columns of a Gothic cathedral, and that their impervious invest- ing wall spread itself from their summits, so as to form a continuous lamella over the sarcodic layer, in the manner that the summits of such columns extend themselves to form the arched roof of the edifice ; and that on the floor of the new layer thus laid the partitions of the chamberlets were progressively built up by the agency of the sarcodic substance con- veyed to the outer surface of that floor through the radial tubes. The author further argues, from the analogy of living Foraminifera, that not- withstanding the indirectness of the communication between the cavitary system of the inner layers and the external surface, the whole of that system (consisting of the labyrinthic structure of the successive lamelle, and of the interspaces which separate them) was occupied during the life of the animal by its sarcode-body. _ The plan of growth in Loftusia is stated by Mr. Brady to differ ex- tremely from that of Parkeria, whilst its intimate structure, on which its physiological condition must have depended, is essentially the same; thus affording a conspicuous example of the validity of the principle of Classifi- cation already referred to. This difference is indicated by its shape, which closely resembles that of many Alveoline and Fusuline ; being a long oval, frequently taperimg almost to a point at either end, though sometimes obtusely rounded at its extremities. Of two large and perfect examples in the collection of the late Mr. Loftus, one measures 37 inches by 1 inch, the other 2+ inches by I} inch. A transverse section at once indicates that the plan of growth is a spiral, formed by the winding of a continuous lamina around an elongated axis; the general disposition of the chambered structure being very similar to that which would be produced if one of the simple Rotalians were thickened and drawn out at the umbilici. The space inclosed by the primary lamina is divided into chambers by longitudinal septa, which may be regarded as ingrowths from it, extending, not perpen- dicularly (as'in Alveolina), but very obliquely. The chambers, sepa- rated by these principal or secondary septa, are long and very narrow, and extend from one end of the body to the other. Their cavities are further divided into chamberlets by tertiary ingrowths, which are gene- 404 On two gigantic Types of Foraminifera. [Apr. 22, rally at right angles to the septa or nearly so, but are otherwise irregular in their arrangement. No large primordial chamber, such as is common among Foraminifera, has been yet discovered in Loftusia ; but its absence cannot be certainly affirmed. In fully grown specimens the turns of the spire, which succeed each other with tolerable regularity at intervals of from 1-50th to 1-30th of an inch, are usually from twelve to twenty in number; but as many as twenty-five have been counted in one instance, and a yet larger number might not improbably be met with. The spiral lamina and its prolongations, forming the accessory skeleton, are all con- structed of almost impalpable grains of sand, which is proved by analysis to have consisted of Carbonate of Lime, united by a cement of the same material. The Author then describes in detail the several components of the fabric of Loftusia, and compares them with the corresponding parts of Parkeria. The continuity of increase of the spiral lamina always leaves an open fissure between its last-formed margin and the surface of the previous whorl ; and through this aperture the whole system of chambers included within its successive laminee communicates with the exterior, through the passages between their cavities, which are left in the building up of the septa. As ~ already explained, the labyrinthic structure takes its origin from the inner surface of the impervious spiral lamina, the septa being directed towards the central axis. These ingrowths have in many instances the form of tubular columns, which traverse the chambers in a radial direction (7. e. perpendicular to the spiral lamina), terminating either on the septum of the previous chamber, or on the exterior wall of the preceding whorl of chambers. But these tubes do not seem to be homologous with the “ radial tubes” of Parkeria, whose relations differ in important particulars. The range of variation in a number of specimens, as to the amount of the ‘secondary’? and “‘ tertiary”? ingrowths which divide and subdivide the chambers in Loftusia is very great. The principal office fulfilled by this accessory skeleton seems to be that of a support to the primary spiral lamina, imparting the necessary solidity to the organism. ‘The degree of subdivision of the chambers into chamberlets seems to have little bearing on the general economy of the animal. | The Author attempts to determine from the other Foraminifera, of which the remains are found associated in the same Limestone with those of Loftusia, what was its probable Geological age, and under what condi- tions it was deposited ; and he thence draws the conclusion that the rock © belongs to the lowest portion of the Tertiary period, presenting a microzoic Fauna very similar to that of some of our Miliolite Limestones, but richer in the small arenaceous Rhizopods; and that the sea-bottom was a soft Calcareous mud lying at a depth of from 90 to 100 fathoms. ~1869.] Prof. Owen on Remains of a large extinct Lama. 405 II. “On Remains of a large extinct Lama (Palauchenia magna Owen) from Quaternary deposits in the Valley of Mexico.” By Professor OwEN, F.R.S. &c. Received March 22, 1869. (Abstract.) The author premises to his descriptions of these remains a summary of the evidence of Fossil Cameloid Quadrupeds in the memoirs and works of Lund, Pictet, De Blainville, Gervais, Burmeister, and Leidy, deferring the further analysis and comparison of the descriptions by the latter pale- ontologist to the conclusion of the present paper. The subject of it con- sists of casts and photographs of fossils discovered by Don Antonio del Castillo, mining engineer, in a posttertiary deposit beneath volcanic ma in the Valley of Mexico. The fossils include the dentition of the left ramus of the lower jaw, wanting the incisors ; also the series of cervical vertebrze, wanting the first or atlas. Assuming the incisors to be in number as in Ruminants, the dentition of this mandibular ramus is formularized as :—7 3, ¢1, p 3, m3=10. Of the grinding-teeth, the three molars, with the last two premolars, form a close-set or continuous series of five teeth, the first of which (p 3) is small, simple, conical, and obtusely pointed. A still smaller or rudi- mental premolar (p 2 or p 1) is situated in the long diastema between the series of five teeth and the canine; the latter tooth is relatively smaller than in the Camel. Detailed descriptions are given, illustrated by drawings, of each of the teeth, from which the author shows that they have belonged toa Cameloid species, as large as the larger variety of existing Dromedary, but with modifications of the teeth, testifying to a closer affinity with the Lama and Vicugna. He then proceeds to give detailed descriptions, with figures, of the cervical vertebree ; they present the intraneural position of the vertebro- arterial canals characteristic of the Camelideé, and of the extinct Perisso- dactyle genus Macrauchenia ; and the comparisons of the fossil vertebra are made with the corresponding one of that extinct genus and of the existing species of Camelus and Auchenia. The result of the comparison concurs with that of the dental characters in demonstrating the former existence in America of a Cameline Ruminant as large as the largest variety of living Camel or Dromedaiy, with closer affinities to the Lamas and Vicugnas, yet with such departures from the dental and osteological characters of duchenia, Mlig., as justify the author in indicating them by the generic or subgeneric term Palauchenia, which he proposes for such extinct form of American Cameline quadruped. The atithor, in conclusion, refers more at large to Prof. Leidy’s descrip- tions of Procamelus occidentalis, Leidy, and Camelops Kansanus, Leidy, pointing out the more important particulars wherein they differ from Palau- VOL. XVII. 2 8 406 Mr. M. W. Crofton on the Proof of the Law of [Apr. 22, chenia magna, Owen, and dwelling on the evidences of a progress from a more generalized to a more specialized type of Ruminant dentition in the extinct Cameloid forms succeeding each other, from the old Pliocene of Nebraska to the new or Postpliocene of Mexico. Tables of dimensions of teeth and vertebree of Palauchenia, Auchenia, and Camelus, and drawings arranged for one folding and three 4to plates, accompany the memoir. III. “ On the Proof of the Law of Errors of Observations.” By M. W. Crorron, F.R.S. Received March 24, 1869. (Abstract. ) The object of this Paper is to give the mathematical proof, in its most general form, of the law of single errors of observations, on the hypothesis that each error in practice arises from the joint operation of a large number of independent sources of error, each of which, did it exist alone, would occasion errors of extremely small amount as compared generally with those actually produced by all the sources combined. This proof is contained in a process given for a different object, namely, Poisson’s generalization of Laplace’s investigation of the law of the mean results of a large number of observations, to be found in the ‘ Connaissance des Temps’ for 1827, and also in his ‘ Recherches sur la Probabilité des Jugements;’ it is also re- produced in Mr. Todhunter’s able ‘ History of the Theory of Probability.’ It is not therefore pretended that any new results are arrived at in the present Paper. Considering, however, the importance and celebrity of the question, and the refined and difficult character of Poisson’s analysis, it will not probably be deemed superfluous to show how the same law may be demonstrated with equal generality, in a much more simple and elementary manner. The difficulty of the general proof seems indeed to have been so extensively felt, that several attempts have been made to simplify its However, so far as the present writer is aware, no proof has been given, except Poisson’s, which is not open to grave objection, as based upon unjustifiable assumptions, or as unduly iin the generality of the in- vestigation. The mathematical reasoning in this Paper is based entirely on the above- mentioned hypothesis as to the causation of error, namely, that errors in rerum naturd result from the superposition of a large number of minuter errors arising from a number of independent sources. The laws of these elementary errors are supposed entirely unknown, no further restriction whatever being imposed on the generality of the investigation ; as would be © the case, for instance, were we to assume (as has sometimes been done) that each independent source gives positive and negative errors with equal facility. To decide fully how far the above hypothesis (which seems now to be generally accepted) really agrees with facts, is an extremely subtle question in 1869. ] Errors of Observations. 407 philosophy,—one which probably never can be more than partially resolved. Stull, even a cursory and superficial examination of a few particular cases seems to show that, far from being a mere arbitrary assumption, it is at least a reasonable and probable account of what really does take place in nature, in many large classes of errors of observations. The history of practical astronomy, in particular, seems to prove that, whatever doubt may be entertained of its exactness as applied to the errors of rude and primi- tive observers, we may safely accept it in the case of the refined and deli- cate observations of modern astronomers. ‘ It would be scarcely possible in this Abstract to convey any clear idea of the mathematical analysis employed in reducing the above hypothesis te calculation. It will suffice to remark that, whereas in the processes given by Laplace and Poisson, when applied to the problem before us, the ele- mentary component errors are at first supposed of finite magnitude, and finite in number, and the results are afterwards modified for the supposition that the magnitude of the errors becomes infinitesimal and their number infinite; much simplicity is gained in this Paper by making these suppo- sitions at the commencement. Also, instead of taking a simultaneous view of all the elementary errors, as affecting the actual or resultant error, the latter is considered as produced by the superposition of some one of the elementary errors upon the error produced by the combination of all the others. We are thus led to examine the infinitesimal change produced in a given finite error, as expressed by a given function, by the superposition of a new infinitesimal error; and from the analytical expression arrived at, it is shown how to find the form of the function of error resulting from the combination of an infinite number of given infinitesimal errors. This form is found to be altogether independent of the nature or laws of the compo- nent errors. If we assume the following data as known, viz. m=sum of the mean values of the component errors, h=sum of the mean values of the squares of component errors, 2=sum of squares of the mean values of component errors, it is proved that the probability of the actual resulting error being found to lie between zw and «+ dz is 1 _(2-m)? a) 2h—-1) dx. This result will be found to agree with Poisson’s. April 29, 1869. Lieut.-General SABINE, President, in the Chair. Pursuant to notice given at the last Meeting, Alphonse DeCandolle, of Geneva; Charles Eugéne Delaunay, of Paris; and Louis Pasteur, of Paris, were ballotted for and elected Foreign Members of the Society. The following communications were read :— 2H 2 408 Mr. A. Smith on the Causes of the Loss of the. [Apr. 29, I. “On a certain Excretion of Carbonic Acid by Living Plants.” By J. Broventon, B.Sc., F.C.S., Chemist to the Cinchona Plantations of the Madras Government. Communicated by J. D. Hooker, M.D., F.R.S. Received March 31, 1869. [ Abstract. ] While the author was engaged in some experimental determinations of the changes that take place in the composition of the Cinchona barks after being taken from the tree, he noticed a somewhat singular circum- stance, which induced him to institute a series of experiments, by which he discovered that the various parts of living plants excrete carbonic acid, not only in their normal condition, but after they have been deprived for days together of all access of oxygen. The experiments were mostly made on cut portions of the plants; but experiments were also made, for control, on plants as they actually grow. The deprivation of oxygen was effected sometimes by Sprengel’s air-pump, sometimes by substituting for air an atmosphere of hydrogen or nitrogen; while comparative experiments were made on plants supplied with air that had been freed from carbonic ‘acid. The main conclusions to which he was led are those enunciated by the author : — Ist. That nearly all parts of growing plants evolve carbonic acid in considerable quantities, quite independently of direct oxidation. 2nd. That this evolution is connected with the life of the plant. 3rd. That it is due to two causes, namely, to previous oxidation, result- ing after a lapse of time in the production of carbonic acid, and to the separation of carbonic acid from the proximate principles of the plant while undergoing the chemical changes incident to plant-growth. II. “On the Causes of the Loss of the Iron-built Sailing-ship ‘Glenorchy.’” By Arcuipatp Situ, Esq., M.A., LL.D., F.R.S. Received April 15, 1869. When the loss of an iron-built vessel has been caused ie an error in the direction of her course by dead reckoning, as derived from her course by compass, it is a question of scientific interest whether the error has or has not arisen from an error in the assumed deviation of the compass. By careful consideration of all the circumstances of the case, and by piecing ~ together the generally scanty fragments of information which can be obtained as to the magnetic state of the ship, a probable or certain answer to this question may be given more frequently than might be supposed possible by those who do not know how perfectly definite and well ascer- tained the laws of the deviation of the compass are, how small is the number of quantities involved which are peculiar to each particular ship, and from what apparently slight indications an approximate estimate of the numerical values of these quantities can be made, 1869. ] Tron-built Sailing-ship ‘ Glenorchy,’ 409 The case the circumstances of which I now propose to lay before the Royal Society, is one in which it appears to me that a positive answer to the question can be given. It will, I hope, be found to have some interest as an example of the manner in which such an answer can be elicited from the data. It may have some scientific interest as the first case in which any information as to the magnetic character of an English merchant-ship has been published since the publication of the Third Report of the Liverpool Compass Committee in 1861; and I think it will be found to have much practical interest, as bringing into prominence a particular error of great importance, not as yet, I believe, ascertained or corrected in the usual course of adjustment of compasses in merchant-ships, even by the most experienced and skilful compass-adjusters, but which, ever since the mode of ascertaining and correcting it without heeling the ship was given in the ‘Admiralty Manual for the Deviation of the Compass’ in 1862, has been ascertained, and when necessary corrected, in the ships of the Royal Navy, viz. the Heeling Error. The case to which I refer is the loss of the ship ‘Glenorchy’ of Glasgow, on the Kish Bank, in Dublin Bay, on the 1st of January 1869, on which a court of inquiry was held under the direction of the Board of Trade in pursuance of the Merchant Shipping Act. In examining this case I have had the advan- tage, by the permission of the Board of Trade, of perusing the evidence taken before the Court of inquiry, and the report of the Court. I have also had the advantage of discussing the nautical as well as the magnetical circumstances of the case with Captain Evans, F.R.S., the highest authority in all that relates to such an inquiry, and who permits me to state his concurrence in the conclusions at which I have arrived; and above all, I have to express my obligations to Mr. William Fleming, compass-adjuster, James Watt Street, Glasgow, for the full particulars with which he has kindly furnished me of the deviations and correction of the compasses of the ‘Glenorchy ’—information without which the results of this inquiry would have been in a great measure conjectural. The ‘Glenorchy’ was an iron-built sailing-ship of 1200 tons, having an iron poop, with a wooden deck laid upon iron beams, with iron bulwarks, except on the poop-deck, above which there was a light rail. She was built at Dumbarton in 1868. Her head in building was about N.N.E. After being launched she was taken to Glasgow, where she lay for some time head N.W. taking in a cargo of about 1100 tons of iron railway- chairs and sleepers. : She had two compasses on deck—a steering-compass and a standard compass. The card of each had two edge-bar needles 83 inches long, the ends separated 50°. The steermg-compass was near the stern, about 32 or 33 inches above the poop-deck, and 2 feet in front of the steering-wheel, which had an iron spindle. The standard compass was on a wooden pillar about 5 feet high, 410 Mr. A. Smith on the Causes of the Loss of the . [Apr. 29, standing on a wooden platform laid from the poop to the mainmast, and about 15 feet abaft the mainmast, which was of iron. On the 18th of December the ‘Glenorchy’ had her compasses adjusted in the Gareloch by Mr. Fleming in the usual way. The deviation of the steering-compass, as might have been expected from the combined effect of the position of the compass in the ship and of the ship in building, was enormous. Mr. Fleming says it was “‘as bad if not worse than any he ever saw.’ Mr. Fleming informs me that before magnets were applied to the steering-compass, when the ship’s head bore N. (magnetic) it bore S. by the steering-compass; when the ship’s head bore W. (magnetic) it bore about S.W. by S. by the steering-compass. In other words, at N. (magnetic) there was a deviation 180°, at W. (magnetic) a deviation of about 56° 15’ E. The quadrantal deviation was about 10°. These data give, using the notation of the ‘Admiralty Manual for the Deviation of the Compass,’ 46 = — 1°250, C= 49, or a force of the ship to the stern exceeding by one-fourth the whole directive force of the earth’s magnetism acting on the compass, a disturbing force about twice as great as that found at the steering-compass in any of the iron-built armour-plated ships in Her Majesty’s Navy. This enormous disturbing force was corrected by three large magnets one of 36 inches and two of 26 and 28 inches placed together, fore and aft, on the starboard side of the binnacle, and by two or three smaller magnets placed so as to correct as far as possible the residual error on the other cardinal points. The ship was then placed head N.W. (magnetic), when a westerly deviation of three-fourths of a point 8° 26’ was observed. This was of course approximately the amount of the quadrantal deviation, and it was corrected by a No. 12 iron jack-chain placed in the chain-boxes on each side of the compass. The ship was then swung on sixteen points and the following deviations of the steering-compass obtained (+ signifying that the N. point of the needle was drawn to the H., — to the W.). ‘Glenorchy’ Steering-Compass, December 18, 1868. Magnetic Course.| Deviation. | Magnetic Course. Deviation. | qe 0 S. —2° N.N.E. +3° | S.S.W. +3 N.E. +7 S.W. 0 E.N.E. +2 W.S.W 0 EK. +3 | W. +5 H.S.E. —3 | W.N.W —3 S.E. —2 I N.W. 0 S.S.E —1 | N.N.W —2 1869. | Tron-built Sailing-ship ‘ Glenorchy.’ 411 From these I derive the following expression for the deviation (6) in terms of the azimuth of the ship’s head (¢) measured eastward from the magnetic N, 6=30'+ 30' sin Z+1° 2’ cos + 2° 37’ sin 2¢ —38' cos 27. These values show that the semicircular, deviation had been entirely corrected. Of the quadrantal deviation a small part appears to have been uncorrected. ‘There are practical difficulties in the way of correcting very large amounts of this deviation by soft iron, and I have no doubt Mr. Fleming acted with judgment in not attempting to carry this correction further. We may probably assume the maximum quadrantal deviation to have been about 10°. The standard compass was not corrected by magnets, but its deviations - were observed, and a Table of the deviations furnished. They were :— ‘Glenorchy’ Standard Compass, December 18, 1868. Magnetic Course. Deviation. |, Magnetic Course. Deviation. N. +12° | S. | — 5° N.N.E. ee | area 8.S.W. + 7 30’ N.E. —24 | S.W. +16 E.N.E. —37 30 | W.S.W. +22 30 E. —38 | W. +33 E.S.E. —d31 30 | W.N.W. +35 30 S.E. —24 | N.W. | +35 S.S.E. —11 30 | N.N.W. +20 30 These values give A=0, %=—-610, @=+:'105, B=+°100, €=0. This Table and these values de not bear directly on the loss of the ship, because owing, as I collect, to the unsteadiness of the pillar the standard compass was found to be useless, and the ship was navigated by the steering-compass alone; but it is interesting from the light it throws on the general magnetic character of the ship, and its confirmation of the results obtained from the steering-compass. The proportion of € to —% exactly agrees with what we know of the direction in which the ship was built. The large value of —% was no doubt owing to the original magnetism of the hull and not to the iron cargo, which in fact probably rather diminished than increased the —%. Cards containing the deviations of both compasses were furnished to the captain. | The question of the correction of the standard compass by magnets is one which has become of so much importance that I may be pardoned for interposing a digression on this subject and for inserting a passage from the third edition of the ‘Admiralty Manual’ now in the press. 412 Mr. A. Smith on the Causes of the Loss of the . [Apr. 29, “The question of the mechanical deviation of the compass has mate- rially changed its aspect of late years. Before that time the deviation of a properly placed standard compass was of moderate amount, its maximum seldom exceeding 20°, and the directive force which acted upon it being generally comprised within the limits of two-thirds and four-thirds of the mean force. There was ther no difficulty and some advantage in dis- pensing altogether with mechanical correction ; or, if mechanical correction was employed, it was possible, at least in vessels which did not change their magnetic latitude, to make the eorrection so complete that tabular correction might be dispensed with. But in the present day it is fre- quently impossible to find a position for the standard compass at which the deviation and the variation of directive force do not greatly exceed these limits. In such cases the application of magnets for the purpose of equalizing the directive force on different azimuths becomes a matter of necessity ; while at the same time the danger of trusting to mechanical correction alone without ascertaining and applying the residual errors is increased. “This change of the condition of the question has produced a corre- sponding change in the practice in the Royal Navy. “The same care as before is still used in the selection of a place for the standard compass; but a magnet is frequently or generally introduced for the purpose of equalizing the directive force on different azimuths, and at the same time diminishing the semicircular deviation. The quadrantal deviation is not often corrected mechanically, but is generally left for tabular correction. ‘The heeling deviation is always ascertained, and is sometimes corrected mechanically.” After the ‘Glenorchy’ was swung she took in an additional quantity (about 120 tons) of iron. I do not, however, think it possible that this quantity could have altered the deviations sensibly. : The ‘Glenorchy’ sailed from Greenock on the 25th of December. She had on board a pilot accustomed to the navigation of the Irish Channel. She was towed to Lamlash Harbour, in the Island of Arran, where she lay till 3 a.m. on the 31st of December. She then got under way, the wind blowing moderately from the N.W., and steered a course down mid- channel, sighting the Copeland, the Mull of Galloway, the North and South Rock, St. John’s Point, and the Calf of Man lights. a The wind gradually heading her, she tacked about 6.15 a.m. on the ist of January. At 7.10 a.m. her position was determined by a bearing and distance of the South Stack Light, which then bore 8S. by W., distant five miles. Till the ship tacked she had been on the starboard tack, on courses from S.W. to S., on which the deviation-card gave small deviations for the stecring-compass. The bearing of the lights successively passed had, 1869.] Tron-built Sailing-ship ‘ Glenorchy.’ 413 however, been carefully taken by the captain, and from these he found that the compass had a westerly deviation of one point not shown by the deviation-card. From 7.10 a.m. till 3 p.m. the ship was on the port tack, sailing by the wind but kept good full, ner course by the steering-compass being about S.W. by W. During the whole of this time a gale of wind was blowing from S8.S.E., gradually increasing in intensity, with thick weather and rain, which cleared only for a little about 1.30, when land was seen in the distance bearing W.N.W. ‘The lead was cast and 35 fathoms found. ‘The captain and pilot consulted the chart, and making what they considered a proper allowance for tide and leeway, came to the conclusion that the land was Wicklow Head, bearing W.N.W., distant twenty-two miles. The ship then stood on the same course till 3 p.m., when soundings were again taken and 25 fathoms found. Orders were then given to wear, but in wearing, and when nearly before the wind, the ship struck and remained fixed on the Kish Bank, about four miles S. of the Kish Lightship. ‘ The point at which the ship so unexpectedly found herself was about twenty geographical miles to leeward of that at which the captain and pilot supposed themselves to be. In other words, the ship’s actual course was about 28° or 23 points to the right of her supposed course. To what, then, was the error due? In the first place, it seems impossible to attribute any large part of the error to an insufficient allowance for the effects of tide and leeway. It is true that from 7 to 1 o’clock a spring flood-tide, assisted by a southerly gale, had been running, but this was known to the captain and pilot. They had watched with great care throughout the day the courses, the leeway, and the rate, and, if we may judge from their estimate of the distance run, had estimated them with great exactness. The next cause that suggests itself is a deviation of the compass not allowed for. The steering-compass by which the ship was navigated was, we have seen, carefully adjusted in the Clyde, and was then nearly correct on a S.W. by W. course. Is it possible that any change in the magnetism of . the ship had taken piace, as has sometimes been found or supposed in new ships, which would account for the error? The answer to this must be in the negative. It is certain that any such change in the ‘Glenorchy’ would have had the effect of producing an error of the opposite kind, and, had it operated, she would have been found to the south, not to the north, of her supposed course. , Is there, then, any other cause adequate to produce an easterly deviation on a S8.W. by W. course which might lurk concealed and undetected in the process of adjustment and only emerge during the voyage? To this the answer is emphatically Yes! The Heeling Error. 414 On the Loss of the Iron-built Sailing-ship ‘Glenorchy.’. | Apr. 29, From the combined effects of the position of the steering-compass in the ship and of the ship in building, it is certain that there must have been a very large heeling error drawing the north point of the compass to the weather side of the ship. This error was probably not less than 3° or 4° for each degree of heel on a N. or S. course, before the chain- correctors were applied. The chain-correctors would reduce it about 50’, leaving 2° or 3° for each degree of heel. On a S.W. by W. course this error would be reduced to five-ninths of its maximum amount, or would be from 1° to 13° for each degree of heel. Hence if the ‘Glenorchy’ was heeling 10°, she would certainly have an easterly deviation of a point to a point and a half, or possibly more, introduced. But it may be asked, if the ship had this large amount of heeling deviation, how did it escape detection in the earlier part of the voyage, when the ship was on a southerly course and the bearings of the lights were taken? and if detected, how was it not allowed for on the Ist of January ! The answer to these questions is remarkable; it is shortly this. The error was detected and was allowed for correctly when the ship was on the starboard tack. Afterwards, and when the ship was put on the port tack, it was still allowed for, but in the same direction as before, aad therefore in the wrong direction. It was allowed for as a westerly deviation, although it had become an easterly deviation; and consequently the heeling error instead of being corrected, was doubled. And of this the cause was as follows. Between Greenock and Lamlash, the ship being towed and on even keel, there were no means of detecting the error. Between Lamlash and the Calf of Man, when the ship was on the starboard tack and on a southerly course, an error of a point of westerly deviation was, as we have seen, detected and allowed for by the captain. This error I think there cannot be a doubt was heeling error. But when on the morning of the lst of January the ship tacked and was put on the port tack, the heeling deviation changed from being a westerly deviation to being an easterly deviation. The captain not being aware that there would be this change, and having no opportunity of verifying his course, continued to make the same allowance as before, and consequently made it, as I have said, in the wrong direction. As to the fact I think I cannot be mistaken. | The captain’s words are :—‘‘ Our observations of the different lights all the way down Channel showed the compasses were inaccurate, and during the whole course on the starboard tack we had to steer one pomt more to the west than the proper course.” Then, speaking of the ship’s supposed position at 1.30, he says :— ‘The courses I had observed, and the rate we were going, allowing for the tide and the leeway, and the point the compass was in error while on the 1869. ] On Spectroscopic Observations of the Sun. 415 starboard tack, should have brought us to a point with Wicklow Head, lying W. by N., twenty-one miles distant.” It is clear from this that the captain made an allowance for the point. of error he had discovered. Had he applied it in the opposite direc- tion, he would undoubtedly have mentioned that he did so and why he did so. The particular conclusions, then, which I draw from the facts of the case are these :— 3 1, There must have been a large heeling error affecting the steering- compass of the ‘Glenorchy,’ which, on the courses steered, would be a westerly deviation on the starboard tack, an easterly deviation on the port tack. 2: The westerly deviation detected on the starboard tack was this heeling error. 3. The true construction to be put on the captain’s statement is, that when on the port tack he allowed for the point of deviation which he had detected on the starboard tack as a point of westerly deviation, not as a point of easterly deviation, as he would have done had he known the cause and the law of the deviation which he had detected. 4. That, in consequence, his supposed course was in error one point plus the heeling deviation, which, on a 8.W. by W. course, was probably about one point more. The general conclusions to be drawn from the history of the ship- wreck seem to me to be :— 1. The great importance of selecting a position for the navigating- compass where the force of the ship’s magnetism is moderate and uniform. 2. The importance of extending the usual process of “ adjustment”? of a compass to the ascertaining and (if necessary) the correcting of the heeling error. This is a matter of no difficulty if the compass-adjuster is duly instructed and supplied with the requisite instruments. III. “ Spectroscopic Observations of the Sun.—No. IV.” By J. Norman Locxyer, F.R.A.S. Communicated by Dr. SHarrey, Sec.R.S. Received April 14, 1869. I beg to lay before the Royal Society very briefly the results of observa- tions made on the 11th instant in the neighbourhood of a fine spot, situated not very far from the sun’s limb. I. Under certain conditions the C and F lines may be observed bright on the sun, and in the spot-spectrum also, as in prominences or in the chromosphere. II. Under certain conditions, although they are not observed as bright lines, the corresponding Fraunhofer lines are blotted out. III. The accompanying changes of refrangibility of the lines in question 416 Mr. J. N. Lockyer’s Spectroscopie . [Apres, show that the absorbing material moves upwards and downwards as regards the radiating material, and that these motions may be deter- mined with considerable accuracy. IV. The bright lines observable in the ordinary spectrum are sometimes interrupted by the spot-spectrum, 7. e. they are only visible in those parts of the solar spectrum near, and away from, spots. V. The C and F lines vary excessively in thickness over and near a spot, and on the 11th in the deeper portion of the spot they were much thicker than usual. IV. Stars, in the spectrum of which the absorption-lines of hydrogen are absent, may either have their chromospheric light radiated from beyond the limb just balanced by the light absorbed by the chro- mosphere on the disk, or they may come under the condition referred to in (II.), either absolutely or on the average. AppENDUM.—Received April 29, 1869. Since the date on which the foregoing paper was written, I have ob- tained additional evidence on the points referred to. I beg therefore to be permitted to make the following additions to it. The possibility of our being able to determine the velocity of movements of uprush and downrush taking place in the chromosphere depends upon the alterations of wave-length observed. It is clear therefore that a mere uprush or downrush at the sun’s limb will not affect the wave-length, but that if we have at the limb cyclones, or backward or forward movements, the wave-length will be altered ; so that we may have :— 1. An alteration of wave- length near the centre of the disk caused by upward or downward movements. 2. An alteration of wave-length close to the limb, caused by backward or forward movements. If the hydrogen-lines were invariably observed to broaden out on both sides, the idea of movement would require to be received with great caution; we might be in presence of phenomena due to greater pressure, both when the lines observed are bright or black upon the sun; but when they widen out sometimes on one side, sometimes on the other, and some- times on both, this explanation appears to be untenable, as Dr. Frankland and myself in our researches at the College of Chemistry have never failed to observe a widening out on both sides the F line when the pressure of the gas has been increased. On the 21st I was enabled to extend my former observations. On that day the spot, observations of which form the subject of the paper, was very near the limb; as this was the first opportunity of 1869. | Observations of the Sun. A417 observing a fine spot under such circumstances I had been able to utilize, I at once commenced work upon it. The spot was so near the limb that its spectrum and that of the chromosphere were both visible in the field of view. The spot-spectrum was very narrow, as the spot itself was so greatly foreshortened ; but the spectrum of the chromosphere showed me that the whole adjacent limb was covered with prominences of various heights all blended together. Further, the prominences seemed fed, so to speak, from, apparently, the preceding edge of the spot; for both C, F, and the line near D, were magnificently bright on the sun itself, the latter especially striking me with its thickness and brilliancy. In the prominences C and F were observed to be strangely gnarled, knotty, and irregular, and I thought at once that some “‘ injection”? must be taking place. I was not mistaken. On turning to the magnesium lines I saw them far above the spectrum of the limb and unconnected with it. A portion of the upper layer of the photosphere had in fact been lifted up beyond the usual limits of the chromosphere, and was there floating cloud-like. The vapour of sodium was also present in the chromosphere, though not so high as the magnesium, or unconnected with the spectrum of the limb, and, as I expected, with such a tremendous uplifting force, I saw the iron lines (for the first time) in the spectrum of the chromo- sphere. My observations commenced at 7.30 a.m.; by 8.30 there was compara- tive quiet. At 9.30 the action had commenced afresh; there was now a single prominence. At the base of the prominence I got this appearance : ek. Higher up this: vation madeon March 14, in which a slight movement of the slit gave is, cee , then , and finally me first , all these appearances being due to cyclonie action. 418 Spectroscopic Observations of the Sun. __— [ Apr. 29, On the following side of the spot, at about 10 a.m., I observed that the F line had disappeared; at the point of disappearance there appeared to be an elongated brilliantly illuminated lozenge lying across it at right angles, as if the spectroscope were analyzing the light proceeding from a cyclone of hydrogen on the sun itself, but so near the limb that the rotatory motion could be detected. The next observations I have to lay before the Royal Society were made on the 27th inst. Careful observations on the 25th and 26th revealed nothing remarkable except that the chromosphere was unusually uni- form. On the 27th a fine spot with a long train of smaller ones and faculze was well on the disk. The photosphere in advance of the spot, and the large spot itself, showed no alteration from the usual appearance of the hydrogen- lines; but in the tails of the spot the case was widely different. The F line, at which I worked generally, as the changes of wave-length are better seen, was as-irregular as on the former occasions. I. It often stopped short of one of the small spots, swelling out prior to disappearance. II. It was invisible in a facula between two small spots. Ill. Zé was changed into a bright line, and widened out on both sides two or three times IN THE VERY SMALL SPOTS. IV. Once I observed it to become bright near a spot, and to expand over it on both sides. V. Very many times near a spot it widened out, sometimes consider- ably, on the less refrangible side. VI. Once it extended as a bright line without any thickening over a small spot. VII. Once it put on this appearance : / bright. HAN fet " | ' 4 VIII. I observed in it all gradations of darkness. IX. When the bright and dark lines were alongside, the latter was always the less refrangible. The Society then adjourned over-Ascension Day to Thursday, May 13. Be Mie 6 * bs: bea , . iy CONTENTS—(continued). PAGE II. On Remains of a large extinct Lama (Palauchenia magna, Owen) from Quaternary deposits in the Valley of Mexico. By Professor Owen, BARS. Ge. Eo ees III. On the Proof of the Law of Errors of Observations. By M. W. Crorton, April 29, 1869. ; I. On a certain Excretion of Carbonic Acid by Living Plants. By J. Brovueuton, BSc., F.C.S., Chemist to the Cmchona Plantations of the Madras Government: 9.0.00 0 Ue a ee ie TI. On the Causes of the Loss of the Iron-built Sailing-ship ‘ ws By ; ArcHiBaLp Smiru, Esq.,M.A., LL.D.,F.RS. ......- . . 408 III. Spectroscopic Observations of the Sun_—No. IV. By J. Norman Lockyer, BIRLA Bei oes i ig ye ii on) Ue lee ens “eats wet TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET. PROCEEDINGS OF THE ROYAL SOCIETY. VOL. XVII. No. 112. Be chug. | CONTENTS. fe bp’? | 6 AA, <2 PAGE Sera May 13, 1869. I. On some of the minor Fluctuations in the Temperature of the Human Body when at rest, and their Cause. By A. H. Garrop, St. John’s College, Cam- ONE)... . 419 II. Observations of the isolate Dit sao ae iiten ee of WDarceetrtal Magnotinrn at Bombay. By CuariLes CHAMBERS, Superintendent of the Colaba Observatory . . . 426 III. On the Uneliminated ter iilcdtal Histor: in the Gbesecatans af ‘WN enistio Dip. By Cuartes CHAMBERS, Superintentlent of the Government Ob- UIE atear cf 03S ne eA koe Ge hie wT wid enenep aaa aI May 27, 1869. I. On the Laws and Principles concerned in the Aggregation of Blood-corpuscles both within and without the vessels. By Ricnarp Norris, M.D., Pro- fessor of Physiology, Queen’s College, Brmingham ... . . 429 Ii, Researchéson Turacine, an Animal Pigment containing Copper. By A & W. \HUE ‘4 .A. Oxon,, Professor of ue in the Royal Agricultural epe, Cirencester. . . SOR aR Mera ce cane ies Sten ae aay III. On the Radiation of Heat fier the Now. By the Hart or Rosset, F.R.S. 436 IV. On a New Arrangement of Binocular oe Microscope. By WILLIAM Crookes, F.R.S.&e. . . . nih aati SE odie Gaeatin he, 08 ed ays oben cn tt Ae Y. On some Optical Phenomena of Gpale ae WILLIAM CROOKES, F.R.S. &. 448 June 10, 1869. I. Researches on Gaseous Spectra in relation to the Physical Constitution of the Sun, Stars, and Nebule.—Second Note. By EH, Franxuanp, F.R.S., and meebo in.: WRG Pe aie is ayy CL Sth acne ok) eae 2 3) hal «eae For aye of Ce see the 4th page of Wrapper. 1869.| On Fluctuations in the Temperature of the Human Body. 419 May 18, 1869. Dr. WILLIAM ALLEN MILLER, Treasurer and Vice-President, - in the Chair. In conformity with the Statutes, the names of the Candidates recom- mended for election into the Society were read from the Chair, as follows :— Sir Samuel White Baker, M.A. John Russell Reynolds, M.D. John J. Bigsby, M.D. Vice-Admiral Sir Robert Spencer Charles Chambers, Esq. Robinson, K.C.B. William Esson, Esq., M.A. Major James Francis Tennant, R.E. George Carey Foster, B.A. Wyville Thomson, LL.D. William W. Gull, M.D. Col. Henry Edward LandorThuillier, J. Norman Lockyer, Esq. R.A. John Robinson M°Clean, Esq. Edward Walker, Esq., M.A. St. George Mivart, Esq. The following communications were read :— I. “On some of the minor Fluctuations in the Temperature of the Human Body when at rest, and their Cause.” By A. H. Garrop, St. John’s College, Cambridge. Communicated by Dr. Bratz. Received April 16, 1869. The author’s object in the following communication is to show that the minor fluctuations in the temperature of the human body, not including those arising from movements of muscles, mainly result from alterations in the amount of blood exposed at its surface to the influence of external ab- sorbing and conducting media. In the following Tables, when not otherwise mentioned, all the tempe- ratures are taken under the tongue, the thermometer remaining in the mouth for five minutes, except when the observations were made each two- and-a-half minutes, on which occasions the temperature of the bulb was not allowed to fall below 85°F. It may be remarked that in no case mentioned below was the tempera- ture of the air above 65° F., and that on all occasions the skin was dry, whereby any complications from the presence of perceptible moisture were avoided ; and the arguments based on the facts necessitate.an approxima- tion to those conditions. The Tables have been selected from a great number of observations; and no results have been obtained which are not easily explained on the theory given. VOL. XVII. 21 420 Mr. A. H. Garrod on some of the Minor [May 13, The temperatures were taken on one subject, aged 22, male, thin. No. [.—From 10.30 p.m. tell 12 night. Sie 98° SIGN 100° Sitting in a room (temp. of air 66° F.) all the time. Fully clad till 11, when stripped in a minute, therefore nude at 11.1. Warm when dressed, but got cold when nude. At 11.40 covered body all over with a thick blanket, soon followed by aslight skin-glow. In the blanket until 12 night. When body covered, pulse much more bounding than when not covered. 97° 982 99° 100° io = Standing from 11 till 12.5 in a : i ° 11.35 pe] tN stripped ‘a minutes, so nude at 11.40 SS 2 = ——- 11.32. Fairly warm all the while. 11.45 7 Got to bed at 12.6, and lay closely 11.50% wrapped by bedclothes for the rest 11.55 ; of the time. A decided glow came 12 on at 12.113, lasting a minute, after 12.5 which feet became a little cold, but 12.105 a skin of body quite warm. 12.155 Whilst standing nude pulse small, 12.205 but bounding when dressed and when 12.25 in bed. 12.30 G7 gee 99° 100° © Indicates the temperature of the pectoral region, two inches above the nipple, taken by placing, for five minutes, a flat spiral thermometer on the part. ® Indicates the temperature of the front of the thigh, with the same instrument as the last. 1869.] Fluctuations in the Temperature of the Human Body. 97° 11.20 421 No. Lil.—From 11 p.m. till 1 a.m. 98° 99° EEEEET TY Bie Red coe ers Seam oaeed ete ee RE Ses ac ESB SMEs as | dye sloedoo dredge | | ffs | | ie Pees pm ea Ae ey ee DEV Aseneac ce ps PF aS ee Na eee LL BH fabs abs Pale Nai bske Pepel tad MAAR cis OER ee PEER EEE 98° 99° 100° 100° Standing in room (temp. of air 52° F.) from 11 until 12. Fully clad until 11.30, and then stripped in two minutes, so nude at 11.32, Warm in body all the while. At 12.2 got to bed, and there the rest of the time, closely wrapped. A glow came on at 12.83, lasting half a minute, after which feet became coldish. Pulse not so bounding when nude as when body covered. © Indicates the temperature of the pectoral region, found by pla- cing a spiral flat thermometer on it, and keeping it there five minutes. No. 1V.—From 11 p.m. till 12.45 night. ob nae 99° Ses ed ome Nude at 11.11 in a room (temp. of air 56°). Standing from 10.50 until 12.20 nude. At 12.21 got to bed, and remained there rest of time. At 11.45 be- gan moving about and stooping, and whenever stooped felt a chill. Quite shivering from 11.574 till 12.74, when, leaving off moving, the shivering ceased. When in bed had no marked glow, and feet continued to be warm ; skin of thighs not warm. The following is the sphygmo- graphic curve of radial artery at wrist : when in bed at 12.40, pulse same as at 11 (the same pressure spring in all the traces) :— : was used on the sphygmograph- Eee LUU° Mr. A. H. Garrod on some of the Minor [May 13, No. V.—From i0.30 p.m. till 12 night. os 100° ata = Sitting in a room (temp. of air 58° F.) all the HH = time. Warmly clad till 11, when stripped in two : a : minutes, so nude at 11.2. At 11.20 went for half | Ev ANE a minute into a colder room. At 11.45 put on 11.10 SS several flannel things, which had been warmed by 11.15 NEE eA the fire, and sat in front of a warm fire. 1.20 RRERNEES sees cr Took sphygmograph-trace from right superfi- cialis vole at 10.40 and at 11.10. Tried to do so at 11.40, but could not get any indication, from the smallness of its pulsation. At12the pulsation was as great as at 10.40. Sitting in’a room (temp. of air 59° F.) from 9.30 until 10.40, quiet, cool, and warmly clad. From 10.40 till 10.55 moving about in the same room. Stripped at 10.55, and nude in two minutes. Re- mained nude until 11.24, when got to bed, and remained there for the rest of the time. 1869.| Fluctuations in the Temperature of the Human Body. 4238 No. VII.—From 11.10 p.m. ll 11.55 p.m. Standing in a room (temp. of om 98° 99° 100° air 58° F.) from 11 until 11.25. al | Fully clad until 11.9, when — stripped, and nude at 11.10. Continued nude until 12. At 11.25 seated, and remained so until 12, on a bed. At 11.40 Por eee ate areal put feet in water from 110°- sbeaeeseseeas 114°, above ankles, and re- Bes mained thus rest of time, main- taining the heat of the water. b= | Chilly when feet in bath, not 97° gg° 99° luue _—ibefore. At 11.523 contracted limb muscles tonically, and maintained them so until 11.55. © Indicates temperature of pectoral region, two inches above nipple, taken with spiral thermometer, for five minutes. No. VIII.—From 11.25 p.m. till 12.40 night. 98° goe 100° Standing in a room (temp. of air 58° F.) eS from 11 until 12, and sitting during the rest of the time on a bed. Fully clad until 11.50. Na Nude from 11.52, and remained so. Feet a little cold at 12.20, and put them into hot Spe hres _water (108°<114°) at 12.21, gradually in- i Be "Kept fo ‘ereasing the heat of the water. Kept feet in water, above ankles, until 12.40. On adding more hot water and putting feet in it chills followed. 98° 100° No. 1X.—From 9.15 a.m. 211 10 a.m. 98° 99° 100° Sitting all the while in a room (temp. of air 52°), not far from an ordinary fire. Felt cold all over during the time. Reading. At 9.30 turned to the fire and put feet on the fender, having been previously quite at the side of the fireplace. As feet got warm, hands, which were previously warm, became cold. Clad in winter clothes. 424 | Mr. A. H. Garrod on some of the Minor — [ May 13, No. X.—From 11.10 a.m, tall 12.40 p.m. 99° 100° Temperature of air 62° F. A cloudy, breezy day. At 11.10 11 walked about 200 yards on to a beach, and sat down on 11.20 the shingle at 11.5, where there was a slight side breeze. 11.30 Hands and feet a little cold. 11.40 Sun covered by clouds until 11.35, after which it began 11.50 to shine; immediately after which began to feel warm, 12 and continued to get warmer until 12.7, when at 12.7 a eon cloud covered sun until 12.11. During time sun covered, 12.30 several chills came over body. 12.40 Sacer Walking in sun from 12.16 onward. 99° 109° Clad in thin merino next skin and summer clothes. No. Xl.—From 3 p.m. till 6 P.M. 100° 3 3.15 senaeit cele Temperature of air 66° F., slowly diminishing 3.30 Be 4 to 64° F. Sitting on a beach from 3 until 5, after 3.45 a dinner at 2.15-2.45. A slight face breeze. In 4 ae the shade. Warm until 4.15, when feet began 4.15 to get a little cold, and by 5 so cold that 4.30 obliged to move about. At5 began to walk 4.45 slowly, and had to go up several steps. At 5 5.20 began to walk briskly. Began to perspire 5.15 at 5.25. Continued walking, perspiring un- 3.30 til 6. 5.45 Clad as in last. 6 98° 99° 100° To explain these Tables :— The actual temperature of the body at any given moment must be fie resultant of (1) the amount of heat generated in the body, and (2) the amount lost by conduction and radiation. (1) The source of heat in the body is not considered in this paper ; and no more will be now said of it, except that there is every reason to believe that it is not in the skin itself, and that, for the short periods through which each observation was made, it is approximately uniform. (2) The loss of heat from the body is modified by changes in the skin and by changes in the surrounding media ; and these two are mutually dependent. It has long been known that. ‘cold contracts and heat dilates the small arteries of ae skin, respectively raising and lowering the arterial tension, and thus modifying the amount of blood in the cutaneous capillaries. But modifications in the supply of blood to the skin must alter the amount of heat diffused by the body to surrounding substances ; and so we should expect that by increasing the arterial tension, thus lessening the cutaneous circulation, the blood would become hotter from there being less facility for the diffusion of its heat, and that by lowering the ten- 1869.] Fluctuations in the Temperature of the Human Body. © 425 sion, thus increasing the cutaneous circulation, the blood would become colder throughout the body, from increased facility for conduction and radiation. That such is the case is proved by Tables I., II., Ili., IV., V., and VI., . where, by stripping the warm body of clothing, in a cold air, when the tension was low (as in Tables IV., V., shown by the sphygmograph-trace), the temperature and tension rose, at the same time that the surface became colder. In Tables I., II., III., IV., V., and VI., by covering the nude body with badly conducting clothing, when the tension was high, the surface-heat soon accumulated sufficiently to cause a sudden reduction of arterial tension, commonly called a glow, and a rapid fall in the temperatures, from the larger amount of blood exposed at the surface of the body to the influence of colder media. Changes in the arterial tension are easily recognized by the subject of experiment, from the sensations they produce; a feeling of warmth fol- lowed by a shiver, or a shiver itself, generally shows that the tension is lowered, while the opposite effect follows a rise in the tension; and this can be generally confirmed by the sphygmograph-trace. A bounding weak pulse shows a low, and a small thready one a high tension. We know, from the observations of Davy and others, that by reducing the tension in one part of the body the tension of other parts is lowered ; thus by placing one hand in hot water, a thermometer in the other rises. In Tables VII. and VIII. it is shown that by putting the feet in hot water (at 110° to 115°) the lowering of the tension was so great that the amount of heat lost into the air considerably exceeded that gained to the body from the water, so that the temperature of the body began to fall di- rectly, and decreased considerably ; and it was noticed that on adding more hot water chills were produced, which was the same as the effect of first putting the feet in the water. By covering a small part of the body with a bad conductor, the ten- sion of the whole body soon falls, from the accumulation of heat in the covered parts causing a lowering in the tension generally, and a con- sequent greater carrying away of heat. In this way the fall after sitting down on a bad conductor when nude can be explained (Table VII:). A glow is felt in the skin directly upon short muscular movement, as stooping, and the temperature falls at the same time, as in Table IV., be- tween 11.45 and 12.20, and in Table XI., between 5.0 and 5.15. In the latter case the muscular movement was carried to such an extent that the loss was made up for by the increase of heat from the muscular move- ment. Simply heating the feet lowers the tension and temperature together, as in Table IX. and in Table X. The passage of a cloud before the sun seems to have acted by reducing the loss of heat, as the temperature rose at the time. 426 ~Mr. C. Chambers on Terrestrial Magnetism. [May 13, Further confirmation of the facts stated as to the modification of arterial tension may be found in Marey’s work, ‘ De la Circulation du Sang,’ published in Paris in 1863. In that book the author ascribes the uni- formity of the heat in the internal parts to the same cause as the author of the present paper ascribes the variations. The fact observed by Dr. W. Ogle in the St. George’s Hospital Reports for 1866, and by Drs. Ringer and Stewart ina paper read before the Royal Society this year, that the temperature falls at night, and is lowest at from 12 to 1 a.m., and begins to rise after that time, is simply explained on the theory given above; for it depends on the custom of Englishmen going to bed at about that hour, and thus giving a large amount of heat to the cold bedclothes, which at first is expended in warming the sheets &c., while later on in the night the bedclothes are warm, and therefore the body has only to make up for the heat diffused. Other natural phenomena can be similarly explained. Thus, on a cold day, the effect of sitting with one side of the body in the direct rays of a fire is to cause the other side to feel much colder than if there was no fire at all, because the fire lowers the tension over the whole body, and supplies heat to the full cutaneous vessels of one side, while the other side, being equally supplied with blood in the skin, does not receive heat, but has to distribute it rapidly to the cold clothes &c. II. ‘ Observations of the Absolute Direction and Intensity of Ter- restrial Magnetism at Bombay.” By CuHaritus CHAMBERS, Esq., Superintendent of the Colaba Observatory. Communi- cated by Lieut-General Sasine, R.A., President. Received April 5, 1869. (Abstract. ) The observations made by the author were of the three usual elements —the Dip, Declination, and Intensity of the Horizontal Component of the Force. They were taken with instruments supplied to the Colaba Obser- vatory in the year 1867 through the Kew Committee of the British Asso- ciation, after having been tested at the Kew Observatory. The dip-circle was made by Barrow of London, and is furnished with two needles; the other instrument, the unifilar magnetometer, which serves both for observations of declination and horizontal force, was made by Elliott Brothers of Lon- don. ‘The results of the observations for dip only have as yet been received _ from the author. | A complete observation consists of thirty-two readings, each end of the needle being read twice in each different position of the needle and circle ; and the mean of the thirty-two is taken as the result of the observation. The observations were 178 in number, commencing on the 29th of April 1867, and extending to the 29th of December 1868. They were gene- rally taken, with the two needles alternately, on particular days of the 1869.] Mr.C. Chambers on Magnetic Dip-Observations. 427 week. Up to August 17, 1867, the observations commenced with either end (A or B) of the needle dipping, and without remagnetizing the needle ; 2. e. the magnetization for the latter half of one observation was made to serve for the first half of the next observation with the same needle, the - two needles having been kept during the interval with contrary poles ad- jacent in a zinc box; but after August 17, 1867, the needle was always re- magnetized, so as to make the end A dip during the first half of the obser- vation. The effect of this change of practice was to produce a marked increase in the accordance of successive observations. Tables are given containing every complete observation made up to the end of 1868, and showing, as well as the mean dip, the partial results in each position of the circle, and with each end of the needle dipping, and also the mean weekly and mean monthly values. The mean dip obtained for the months April to December 1867 was 19° 2’:00, and for the year 1868 was 19° 3'°87. The period embraced by the observations is too limited to allow of an exact determination of the rate of secular change; nevertheless the observations show distinctly that the dip is increasing. The author takes + 1'-3 as the rate of annual change. For the probable error of a single weekly determination, including the effect of actual magnetic disturbance of an irregular character, the author obtaius for the period from April 29 to August 16, 1867, 0'°67; from August 23 to December 31, 1867, 0':26; from January 1 to December 31, 1868, 0'-24. Notwithstanding the extreme smallness of these probable errors, the indications of needle No. 2 exceeded those of needle No. 1 by quantities ranging, in the means of periods of a few months, from about 0 to +5°0. An endeavour is made in another communication to explain a possible cause of these differences. ILI. “On the Uneliminated Instrumental Error in the Observations of Magnetic Dip.” By Cuartes CuamBers, Esq., Superinten- dent of the Government Observatory, Bombay. Communicated by Lieut.-General Sapinz, R.A., President. Received April 15, . 1869. (Absiract.) A single reading of one end of a dipping-needle placed in a dip-circle pro- vided with microscopes for observing is liable to a variety of instrumental errors, which are eliminated by taking the mean of the sixteen readings of the two ends in the eight different positions included in a complete observation. Nevertheless it is found that with the best modern instruments a mean value results from these sixteen observations different for each different needle, and that the difference between the results obtained with two different needles is not the same at all times. The irregularities in the values of the dip observed at Bombay with two needles of excellent character made by Barrow of London, led the author 428 Mr. C. Chambers on Magnetic Dip-Observations. [May 13, to investigate the effect of a hypothetical irregularity in the shape of the axle of the needle, such that a section of the axle by a plane perpendicular to its axis would be elliptical instead of circular in form. Another source of error, which was brought to the notice of the Royal Society many years ago in a paper published in the Proceedings, is the displacement of the centre of gravity of the needle from the centre of the axle, combined with in- equality in the magnetization of the needle when the poles are direct and re- versed. Experience has led the author to the conclusion that the usual method of magnetization, by a definite number of passes of the same pair of bar-magnets, communicates magnetism to the needle very unequally when the one end of the needle is made north and when the other end is made north. Consequently it is advisable to investigate the effects of ellipticity of the axle and of displacement of the centre of gravity at the same time, which the author proceeds to do. As each of these errors depends upon two independent unknown quanti- ties, suppose the excentricity and the azimuth of the major axis of the elliptic section of the axle for the first, and the two coordinates of the centre of gravity, referred to axes in the plane of motion of the needle and passing through the centre of the axle, for the second, the equation con- necting the true and apparent dip, in any one position of the needle and of the face of the dip-circle, will involve four unknown quantities depending | on the above errors. If we suppose the instrumental errors small, so that the apparent dip does not much differ from the true dip, these four unknown quantities will appear as coefficients respectively of the sine and of the cosine of twice the dip for tie elliptic error, and of the sine and the cosine of the dip for the error of excentricity of the centre of gravity, and will be divided in each case by the magnetic moment of the needle. On taking the mean of the apparent dips in the four usual positions of the needle and of the dip-circle before the magnetism of the needle is reversed, two of the terms, one for each error, disappear, and there results for the difference between the true dip 8 and the mean of the four apparent dips (@’) an equation of the form n(A—B)=(0)—0, . . (soe need where z' is the reciprocal of the magnetic moment of the needle, and A and B are the constants depending on the errors of the pivot and of the centre of gravity respectively. These two quantities are constant only for the same place, the first involving as a factor the sine of twice the dip divided by the total force, the second the cosine of the dip divided by = total force. Now let the poles be reversed in the usual way, and let n” be the reci- procal of the magnetic moment, and (6") the mean apparent dip i in the four positions after remagnetization ; then n'(A+B)=(0—6. . ~. re The equations (1), (2) contain three unknown quantities A, B, 6; but if we repeat the observations with the difference that this time the needle is 1859.] Dr. Norris on the Aggregation of Blood-corpuscles. 429 magnetized as weakly as is consistent with the condition that the apparent shall not greatly differ from the true dip, we shall obtain two more equa- tions of the form n'”’ (A—B)=(0'") —6, a" A + B)=(0"")—0; and these four equations, when suitably combined, will determine the values of the three unknown quantities A, B, 0. The magnetic moments involved in these equations may be determined with little trouble, and with sufficient accuracy, by placing the needle as a deflector on a unifilar magnetometer, and observing the angle of deflection » produced thereby upon the suspended magnet. A series of observations has been commenced by the author with the view of testing whether the true dip can be determined exactly with a single needle by the method above described, the results of which he hopes to communicate to the Royal Society hereafter. The Society then adjourned over the Whitsuntide Recess to Thursday, May 27. May 27, 1869. Lieut.-General SABINE, President, in the Chair. The following communications were read :— I. “On the Laws and Principles concerned in the Aggregation of Blood-corpuseles both within and without the vessels.” By Ricuarp Norris, M.D., Professor of Physiology, Queen’s Col- lege, Birmingham, Communicated by Dr. SHarrry. Received April 29, 1869. (Abstract.) In 1827, or forty-one years ago, the phenomenon which forms the sub- ject of this paper was first observed by Mr. Joseph Jackson Lister and the late Dr. Hodgkin. To these observers the microscope revealed the fact that if a minute drop of human blood is placed between two plates of glass, the red corpuscles apply themselves to each other by their concave surfaces in such a manner as to form long cylindrical masses, which resemble piles of coin, and that very frequently these piles are so arranged as to form with each other a complete network of rouleaux with clear intervening spaces occupied by liquor sanguinis. Simple as this observation may appear, its importance in a pathological point of view can scarcely be overrated ; for upon its correct interpretation depends our knowledge of the real nature of one of the most marked cha- racteristics of inflammation, viz. the phenomenon of inflammatory or homo- geneous stasis. | During the forty years which have elapsed since the discovery of this 430 Dr, Norris on the Aggregation of Blood-corpuscles. {May 27, fact, many theories have been advanced to explain its nature; but all of them, without exception, have laboured under the disadvantage of being purely hypothetical in their character, and quite incapable of demonstra- tion by an appeal to experiment. Thus, while some writers have attri- buted the effect to an imaginary law of vital attraction, others have more correctly referred it to the operation of some unexplained physical cause. Professor Lister (son of the original ohserver already mentioned), who has devoted much attention to this subject, says, in a paper submitted to the Royal Society, June 18, 1857, and published in the Philosophical Transactions for 1858, p. 648 :—“ For my own part, I am satisfied that the rouleaux are simply the result of the biconcave form of the red disks, to- gether with a certain though not very great degree of adhesiveness, which retains them pretty firmly attached together when in the position most favourable for its operation, viz. when the margins of their concave surfaces are applied accurately together, but allows them to slip upon one another when in any other position. There is never to be seen anything indicating the existence of an attractive force drawing the corpuscles towards each other: they merely stick together when brought into contact by accidental causes. ‘Their adhesiveness does not affect themselves alone, but other substances also, as may be seen when blood is in motion in an extremely thin film between two plates of glass, when they may be observed sticking for a longer or shorter time to one of the surfaces of the glass, each ‘one dragging behind it a short tail-like process.” Again, at the end of section I., p. 652 of the same paper, Lister says, ‘* From the facts detailed in this section, it appears that the aggregation of the corpuscles of blood removed from the body depends on their pos- sessing a certain degree of mutual adhesiveness, which is much greater in the colourless globules than in the red disks, and that in the latter this property, though apparently not dependent upon vitality, is capable of remarkable variations in consequence of very slight chemical changes in the liquor sanguinis.” From these quotations it is apparent that Mr. Lister ignores altogether the idea of the aggregation of the corpuscles being due to an attractive force or energy, and refers it to adhesiveness or stickiness of the corpuscles ; in his own words, “‘ they merely stick together when brought into contact by accidental causes.” At the same time he states that this adhesiveness is liable to great variations, both in the way of increase and diminution, by very slight changes in the chemical qualities of the plasma. Dipping deeper into the writings of Lister, we find that this idea of adhesiveness or stickiness of the corpuscles is retained in his explanation of the nature of inflammatory stasis. And his views upon the subject generally may be summed up im three propositions :— 1. The blood-corpuscles exhibit no tendency to unite together in healthy blood within the vessels, although such blood may be in a state of rest. 2. The corpuscles become suddenly adhesive (in 10 seconds) when, by being shed, the blood is brought inte contact with ordinary matter. 1869.| Dr. Norris on the Aggreyation of Blood-corpuscles. 431 3. Irritation, by reducing the vitality of the surrounding tissues, causes them to bear the same relation to the blood within the vessels in their immediate vicinity as ordinary matter does to that which has been shed, inducing adhesiveness of the corpuscles, and thus bringing about inflam- matory stasis. These effects upon the blood-corpuscles are assumed by Lister to depend upon chemical changes induced by ordinary matter or by vitally degraded tissues upon the plasma of the blood ; but inasmuch as chemical changes cannot occur without corresponding physical modifications, it is quite as rational to refer the increased aggregating-tendency displayed by the cor- puscles to physical as to chemical changes in the liquor sanguinis; and this view has the advantage of not requiring us to believe that the functional activity of the tissues is depressed by mild forms of irritation—an idea which is opposed to all we know of the increased nutritive and formative changes which follow in the wake of irritation. Having now briefly reviewed the existing position of the subject, we will proceed to consider the real causes at work in the production of the phenomenon under consideration. Many years since, having familiarized myself with the behaviour of, and the appearances presented by blood-corpuscles under almost every con- ceivable ‘condition, both within and without the vessels, I became pro- foundly impressed with the conviction that these phenomena had their origin in some physical law of attraction, and at the same time felt not the less certain that, if this view proved to be correct, the behaviour of the blood-corpuscles would be found to be no isolated exhibition of this law, and that, provided conditions similar to those which exist in the case of the blood-corpuscles could be obtained, many illustrative examples of the operation of the law would be immediately forthcoming. That such attractive force did not exert its influence through distances readily appreciable was obvious, and this fact at once indicated that it must be sought for among those forms of attraction which have been designated molecular. After much experiment and reflection I came, in 1862, to the conclusion that these phenomena were due to no less universal a law than that of cohesive attraction; and 1 embodied the views I then held upon the subject in a paper which was read before the Royal Society, and published in the Proceedings, entitled ‘‘ The Causes of various Phenomena of Attraction and Adhesion as exhibited in Solid Bodies, Films, Vesicles, Liquid Globules, and Blood-corpuscles.” Since that time other departments of physiology have occupied my attention ; and I have only been induced to recur to the old theme because I find that, in some recent references to the history of this subject, my observations have not been mentioned, from which I am led to infer either that my views had not been sufficiently put forward, or that my experiments had failed to produce conviction in others. I therefore now present the result of a renewed investigation, in which I 432 Dr. Norris on the Aggregation of Blood-corpuseles.. [May 27, believe I have established, by conclusive experiments, the correctness of my explanation of the phenomena. Among the various modes of aggregation which the bleod-corpuscles undergo, two typical forms stand prominently forward, of which all others are merely modifications. The one appears to be dependent upon the normal disk-shape, the other upon the globular or spherical form which the corpuscles assume on the addition of various substances to the blood, such as gum, gelatine, linseed mucilage, potash, &c. With the first of these modes of aggregation, viz. into rouleaux, we are all sufficiently familiar ; and an excellent notion of the character of the second form may be obtained by a careful examination of microphoto- graphs of the blood- corpuscles which have been obtained instantaneously by exploding magnesium in heated oxygen*. In order to leave as little as possible to hypothesis, it was disirable as a preliminary step to make sure that these differences in form of the cor- puscles were the real cause of the diverse modes of arrangement—whether, in fact, we could safely predicate that disk-shaped bodies having an attrac- tion for each other would arrange themselves so as to form rolls or cylin- ‘drical masses, and whether, on the other hand, attracting spheres of soft material would attach themselves together in such a fashion as to cause plane surfaces to be opposed to each other—in a word, to convert them- selves by mutual attraction into polyhedral bodies just as they might do under mutual compression. In the first place, we had to ascertain experimentally how disk-shaped bodies, having the utmost freedom of movement, and possessing an attrac- tion for each other, would arrange themselves. In casting about for the conditions to make such an experiment, I re- membered a very familiar phenomenon which had often excited my curi- osity, viz. the rapidity with which a bubble or a small floating fragment upon the surface of a cup of tea or other liquid rushes to the side of the con- taining vessel, cr with which two such bubbles or fragments rush together, the moment they approach within a certain range. I determined to see if I could not make use of this attraction, the true nature of which I at the time imperfectly understood, and with this object prepared a number of circular disks of cork, which I accurately poised so that they should assume and maintain the vertical position when partially immersed in liquid. On throwing these disks into liquid, I had the satisfaction of seeing them run together and form themselves into the most perfect — rouleaux after the fashion of the blood-disks. This experiment has the value of demonstrating that if the blood- disks attracted each other, their shape would determine the formation of rouleaux. As regards the behaviour of spherical vesicles or globules which attract * Specimens of these, as well as the several experiments referred to in the paper, were exhibited to the Society. 1869.] Dr. Norris on the Aggregation of Blood-corpuscles. 433 each other, it is found that the moment any point in their convex surfaces is made to touch, these surfaces become flattened, and consequently bubbles in a group convert each other into polyhedral-shaped bodies. This effect is not due to compression, but to a progressive mutual attraction of the surfaces of these bodies for each other. As soap-bubbles are vesicles with aérial contents, and are therefore physically unlike the blood-corpuscles, it became desirable to ascertain how vesicles with liquid contents would behave in regard to each other. This was accomplished by placing in a large test-tube a solution of soap, and upon its surface a stratum of petroleum an inch or so in depth ; the petro- leum does not mix with or injure the soap solution, which is the case with most othersubstances. A glass tube is now passed through the petroleum into the solution of soap below. On blowing down the tube, we succeed in forming innumerable small bodies or corpuscles of a spherical form, which are very plastic, and the contents of which consist of petroleum, and the ex- ternal envelope or vesicle of soap. Corpuscles so produced float in the upper stratum of petroleum, and are found to unite themselves into groups and masses in precisely the manner of the air-bubbles, although they are en- tirely submerged in liquid. These experiments show that disk-shaped bodies, having an attraction for each other, will arrange themselves in rolls or cylindrical masses, and that spherical bodies of a plastic character and vesicular structure, be their contents aérial or liquid, will attach themselves together in such a fashion as to cause plane surfaces to be opposed to each other—in a word, convert themselves by a progressive attraction, which commences at their points of mutual contact, into groups of polyhedral bodies. The question now remaining is, do the blood-corpuscles possess such attractions for each other as those displayed by the objects with which we have been dealing? ‘The reply is that their physical nature being analo- gous, if the same conditions exist, they cannot escape the influence of the same law. An examination of the photographs and of the drawings of blood-corpuscles exhibited will serve to show that these bodies are amenable to the law which is concerned in grouping together the bubbles and liquid vesicles. But in the cases we have heretofore been considering, the disks, bubbles, and other factitious objects are not in precisely the same conditions as the blood-corpuscles—the former being only partially, or not at all submerged in liquid, while the latter are entirely so, and nevertheless they run together into rouleaux and groups. It may fairly be asked if the artificial bodies will do the same. The answer obtained by experiment is, that the moment these disks or bubbles are entirely submerged, they lose at once their attraction for each other and fall apart. For several years I unceasingly asked myself the cause of this difference in behaviour. I at length found that when small bodies, such as disks of cork or gelatine, are first wetted with water, and then submerged in a liquid with 434 Dr. Norris on the Aggregation of Blood-corpuscles. {May 27, which water will not mix, such as oil of turpentine or petroleum, they will run together in piles or rouleaux, very much in the same way as the blood-disks. To understand this result, a few simple primary principles must be called to mind. In the first place, the particles which compose any liquid have a mutual attraction for each other ; but between the particles which compose different liquids a mutual repulsion may exist, e.g. water and oil, or chloroform and water. It is likewise true that there is a mutual attrac- tion between certain liquid and rigid bodies, and also a mutual repulsion between others. Any rigid body which can be wetted by a liquid is re- garded as having a cohesive attraction for it, while one which cannot be wetted is said to have no such attraction, or to exert a repulsive influence, as the case may be. These phenomena therefore depend upon what might be justly termed double cohesion—cohesion in the first place between the rigid body and the liquid, and in the second place between the particles of the liquid itself. 3 If, now, we examine into the cases in which we have complete sub- mergence, viz. the blood-rolls, the gelatine disks, and the loaded cork disks, we find the same law to be in operation. These bodies must all be regarded as localizers of liquids, either by their cohesive attraction for liquids, or, as in the case of the blood-corpuscles, by being receptacles containing liquids. If the cork disks, bubbles, or other bodies are entirely submerged in water, all attraction ceases, and this because a cohesive equilibrium is established; there is no longer any differentiation such as exists between water and air. If, however, after having wetted these bodies in water, we completely submerge them in a liquid which has a cohesive antagonism to water, or even a liquid which has simply no cohesion for water, which may be known by the insolubility and immiscibility of one liquid in the other, such as turpentine or petroleum, we get the phenomena of attraction pre- cisely as in the atmosphere. This fact is illustrated by taking the cork disks from the water in which they are non-adherent, and placing them in the vessel of petroleum, in which they become instantly attractive of each other. This principle is further illustrated by the gelatine disks, which are first made to absorb as much water as possible, and are then submerged in petroleum. : In all these cases there are present, therefore, two dissimilar or antago-_ nistic liquids; and upon the presence of these the phenomena depend. My idea of the blood-corpuscle is that its contents are something essen- tially different, so far as cohesive attraction is concerned, from the liquor sanguinis—that is to say, not readily miscible with liquor sanguinis. This is of course self-evident, if, according to some modern views, we regard the corpuscles “as tiny lumps of a uniformly viscous matter,’ inasmuch as such matter must be insoluble in and immiscible with the liquor sanguinis. 1869.] Dr. Norris on the Aggregation of Blood-corpuscles. 435 The explanation is equally easy if we accept the old and, I believe, the true view, of the vesicular character of these bodies, as we have only to -assume that the envelope is so saturated with the corpuscular contents as practically to act as such contents would themselves act, 7. e. to exhibit - a greater cohesive attraction for their own particles than for those of the centiguous liquid. The cohesive power of the blood-corpuscles varies with varying conditions of the liquor sanguinis; and this is doubtless due to the law of osmosis ; for we can readily imagine that when the exosmotic tendency is in excess, the corpuscles will become more adhesive, and, on the contrary, when the endosmotic current prevails, less so. In any case the increased cohesive- ness will be due to the increased extrusion of the corpuscular contents upon the surface. All, then, that is required in the case of the blood-corpuscles, is a differ- ence between their liquid contents and the plasma in which they are sub- merged. That this difference is not so great as between the liquids used in these experiments is probable ; but it must also be remembered that the attraction is not so powerful. The power required to attach the blood- corpuscles together is, on account of their exceeding minuteness, extremely small, as they are thus so much more removed from the influence of gravi- tation, and brought under that of molecular attraction. I shall conclude this paper by a brief reference to inflammatory stasis. In one of my papers(communicated to the Royal Societyin 1862) Idescribed no, less than four distinct forms of stasis. I proposed to designate that in- duced by irritation homogeneous stasis, because the blood-corpuscles be- come so blended together as to entirely lose their outlines and present the appearance of a uniform and continuous plug filling up the capillaries. This peculiar blending of the corpuscles is dependent upon the law I have been describing, viz. that of double cohesion, and is brought about by diminished quantity of liquor sanguinis in a part in proportion to the corpuscles, and by loss of fluidity in that which remains. One of the primary effects of irritation is neural paralysis of the minute arteries which supply capillary tracts; and this paralysis gives rise to increased diosmotic action, in fact to exudation of liquor sanguinis; conse- quently there is a lagging behind of the corpuscles, and an increase of their numbers in the capillaries; the plasma, too, which still surrounds the cor- puscles in the capillaries, is modified ; and when a certain relation has been reached between the corpuscles and the plasma, the former blend together precisely in the same manner as the soap-bubbles, or as the biood-corpuseles exhibited in the photographs. This completely arrests the passage of blood through the capillaries, which become as much occluded as if Blocked up by solid fibrin. I have frequently had opportunities of watching in the transparent webs of frogs the mode in which this homogeneous stasis is resolved. In these creatures the restoration of the circulation commences some hours after the VOL. XVII. 2K 436 The Earl of Rosse on the Radiation of: [May 27, application of the irritant. When the circulation is about to be resumed, the stagnating mass in the vessel appears to thaw as it were. The corpuscles are not pushed onwards in mass as a coherent plug; but the homogeneity of appearance is suddenly lost by the resumption of their normal form by the corpuscles and the reappearance of their differentiating outlines, which were previously obscured by their blending with one another and with the walls of the vessels. Before this takes place, the vessel very gradually assumes a lighter tint, passing in some instances from a deep red to a pale orange. This appears to be due to a washing away of extruded colouring- matter. When this change from homogeneity to heterogeneity commences, although sufficiently progressive in its character as it traverses the vessel, it nevertheless takes place with considerable rapidity. It is evidently brought about by the gradual permeation of new liquor sanguinis among the corpuscles, and the contemporaneous abolition of their cohesive attraction for each other in accordance with the principles previously established. II. “ Researches on Turacine, an Animal Pigment containing Copper.” By A. W. Cuurcu, M.A. Oxon., Professor of Chemistry in the Royal Agricultural College, Cirencester. Communicated by Dr. W. A. Mitter, Treas. R.S. Received May 4, 1869. (Abstract.) From four species of Touraco, or Plantain-eater, the author has-ex- tracted a remarkable red pigment. It occurs in about fifteen of the primary and secondary pinion feathers of the birds in question, and may be ex- tracted by a dilute alkaline solution, and reprecipitated without change by an acid. It is distinguished from all other natural pigments yet iso- lated, by the presence of 5:9 per cent. of copper, which cannot be removed without the destruction of the colouring-matter itself. The author pro- poses the name ¢wracine for this pigment. The spectrum of turacine shows two black absorption-bands, similar to those of scarlet cruorine ; turacine, however, differs from cruorine in many particulars. It exhibits great constancy of composition, even when derived from different genera and species of Plantain-eater ; as, for example, the Musophaga violacea, the Corythaix albo-cristata, and the C. porphyreolopha. III. “On the Radiation of Heat from the Moon.” By the Ear oF Rossz, F.R.S. Received May 27, 1869. The following experiments on Lunar Radiant Heat were undertaken §f with the view of ascertaining whether with more powerful and more suitable means than those previously employed by others, with little or no success, it would be possible to detect and estimate the amount of heat which reaches the earth’s surface ‘rom the moon. 1869. ] Heat from the Moon. 437 Professor Piazzi Smyth had conducted a series of experiments on the Peak of Teneriffe with a thermopile, but apparently without any means of concentrating the moon’s heat beyond the ordinary polished metal cone. Melloni had employed a glass lens of considerable diameter (I believe about three feet); but as glass absorbs rays of low refrangibility, it was not so well adapted to concentrate heat as a metallic mirror. In the following experiments the point sought to be determined was, in what proportions the moon’s heat consists of (1) That coming from the interior of the moon, which will not vary with the phase. (2) That which falls from the sun on the moon’s surface, and is at once reflected regularly and irregularly. (3) That which, falling from the sun on the moon’s surface, is absorbed, raises the temperature of the moon’s surface, and is afterwards radiated as heat of low refrangibility. The apparatus consisted of a thermopile of four elements, the faces half an inch square, on which all the moon’s heat which falls on the large speculum of the 3-foot telescope is concentrated, by means of a concave mirror of 33 inches aperture, 2°8 inches focal length. As it was found difficult to compensate the effects of unequal radiation on the anterior face of the pile, by exposing the posterior face also of the same pile to radiation from the sky, during the later experiments (be- . ginning with March 23rd) two piles were used, and the following was the form of apparatus adopted. D E is the large mirror of the telescope; FG the two small concave mirrors of 3% inches aperture, and 2°8 inches focal length, fixed in the plane of the image formed by the large mirror DE. The two thermo- piles are placed respectively in the foci of F and G, their anterior faces shielded from wind and other disturbing causes by polished brass cones, and their posterior faces kept at a nearly uniform temperature by means of brass caps filled with water. The thermopiles and accompanying mirrors are supported by a bar screwed temporarily on the mouth of the tube. Two wires are connected with the two poles of each pile; and the ends of the wires are connected, two and two, close to the galvanometer, in such a manner that a given amount of heat on the anterior face of one pile will produce a deviation equal in amount, and opposite in direction, to that produced by an equal amount of heat on the anterior face of the other pile. Thomson’s Reflecting Galvanometer was the one used. 2K 2 438 The Earl of Rosse on the Radiation of [May 27, This apparatus has not yet had a fair trial, as I was unable to obtain from Messrs. Elliot a pile ready made of similar dimensions to that which I already possessed. That which they sent had only one-fourth the re- quired area of face. The following is a summary of the results :— g : = 3 5 E = g S S Cony RS a 3S ee a 1868. I. | Dec. 30 ie tans SE 1869. ill. | Jan. 1. hie eee 0 Vel oe VI. | Mar. 23. Vil | wor VIL. | ee sx, Bl. X. April 14 XT. | ie | PEGE a Seton, [e) aa Bea MV oe 2g eae MOVES i005 Mean error. Mean deviation. 115 | Deviation (calcu- lated). Observed deviation | lag 3 [esis (8 e s > i= by g |8sié fs sole 4 cB Wad Gea OS 2 8 8/3 SE a ed | al ee | f | | 110 | 19 ehh 92-1 | 47 | | 81:1 | 79 | ... | ... |Occasional clouds. | ’ ( White frost. Mirrors became 86-8 | 15 | 5G dewed; but the readings 2 | gt cea i taken after this took place | _\. have been rejected. 84-2 | 57 | ... | 40 | Occasional clouds. e | ieee 15 | Occasional clouds, strong | = ss | - bese es 4q | | No note of cloud, very little | 17 | 16 | 30 49 iY breeze, generally ae | | ieee low, an —— — eh a clouds, thro which | aid | 38) AS ss | Has SS | | | |. diminished brilliancy. | | Very eh and calm, but 92 | |} moon low; no perceptible is a -| 4 | ee eee imparted <9 the | | | Wied “gee strong into 79 |110| 27 | 65 |; the mouth of the tube nearly | | the whole time. | | ( No note of cloud till just at | 96 | 85 | 25 | 14 | the end of these observa- | fas Sie : i 5S. are ~ | =, | { Avery little wind; occasiona | 68 | 72/35 | 51 { eee | (Halo with hazy clouds; 45 15 } moon seen through them ate = ° || with much-diminished bril- | | Haney. | Frequent passing clouds ae 88-2 | 18 | 30 | 29 | ring the latter part of these observations. No cloud visible, but haziness 88:8 | 6 | 25 | 66 |4 suspected, as it existed both lg at sunset and at sunrise. ee | 1869. ] Heat from the Moon. 439 In column 3 is given the mean of the deviations of all the single differ- ences from the mean difference of all the readings taken with the moon on and with the moon off the apparatus. In column 4 the arithmetic mean of all the observed deviations. In column 5 the calculated deviation for each night at midnight, on the assumption that the deviation corresponding to full moon =100, and that the moon is a smooth sphere. We have then Q (quantity of heat coming from the moon’s surface) oy cos 6. cos (e—@) dd 2 = 9 {r—e . cos e-+ sin e}*, where e=2x—apparent distance between the centres of the sun and moon. When e=0 (full moon), Q= ~ an ‘ when e= z (half moon), Q= when e=z (new moon), Q=0; . 1f full moon =100, Q in general =100(1—£c0s e+ sine). a a imme os Sait C7) Tv In column 6 we have the deviation for full moon calculated from the observed mean deviation for each night, In column 7 the supplement of the apparent distance between the cen- tres of the sun and moon. In column 8 the approximate mean altitude of the moon. In column 9 the number of times the telescope was put on or off the moon during the observations included in the mean result. In all these observations the deviations which have been measured are those due to the difference between the radiation from a circle of sky con- taining the moon’s disk, and that from a similar circle of sky close to it not containing the moon’s disk. The annexed diagram will show approximately the rate at which the moon’s light increases and diminishes with its phases as deduced from for-. mula (a); and the ringed dots with the accompanying Roman figures (for reference) give the quantity of the moon’s heat as determined by observa- tion on different nights. Although there is considerable discordance between some of the observed: * This formula is based on the assumption that the heat coming to the earth from an, element (dS) of the moon’s surface =K.0S.cos@.cos ¢, 6 and ¢ being respectively the inclinations of the lines to the sun ae to the ue from the normal to that point of the moon’s surface, and K a constant. 4.40 The Earl of Rosse on the Radiation of [May 27, 2 & ee s : e o Ss S 62 4 shee rs Spey 2 68 a Fo BS A) ° (>) = we o S N a pS Elo S> Si i=) (a fH o 2B eI 60° (9) FIRST QUARTER. FULL MOON. 140° 120° 100° = 80° 60° 40° 20° 0° 20° 40° 160° NEW MOON. 180° qs ° 5 de lm o a 1869. ] Heat from the Moon. 4A} and calculated quantities of heat, the results suggest to us that the law of variation of the moon’s heat will probably be found not to differ much from that of the moon’s light. It therefore follows that not more than a small part of the moon’s heat can come from the first of the three sources already mentioned. With the view of ascertaining what proportion of the sun’s heat does not leave the moon’s surface until after it has been absorbed, some readings of the galvanometer were taken on four different nights near the time of full moon, with a disk of thin plate glass in front of the face of each pile; and the deviation was about six or eight divisions. As the glass screens were examined with care for dew after removal on each night, and none was perceived except on one occasion, the probable percentage of the moon’s heat which passes through plate glass is 8, or rather less. Few experiments appear to have been made on the absorptive power of glass for the sun’s rays; but, from the best data that I have been able to obtain, I find that probably about 80 per cent. pass through glass. The greater part of the moon’s heat which reaches the earth appears, therefore, to have been first absorbed by the lunar surface. It now appeared desirable to verify this result, as far as possible, by de- termining by direct experiment the proportion which exists between the heat which reaches the earth from the sun and from the moon. If we start with the assumption that the sun’s heat is composed of two portions, the luminous rays, whose amount = L, and the non-luminous,__sez, ere — ee also that the moon’s light consists of two corresponding portions, L’, O’, the luminous not being absorbed, and the non-luminous being entirely ab- sorbed in their passage through glass, then L pio 8. me eoeets be) --19 pes 2-08: L L+0 LO ae | Substituting for L its generally received value (800,000), we have BELO 0) L+0 ~~ 80,000° e . . e ° ° ° e ° ° ° (6) Owing to the extremely uncertain state of the weather, only one series of eighteen readings was obtained for the determination of the sun’s heat. A beam of sunlight was thrown, by means of a plane mirror, alternately on and off a plate of polished metal with a hole*175 inch in diameter. At a short distance behind this the pile was placed. The deviation thus found was 4.42 On the Radiation of Heat from the Moon. [May 27, connected with that previously found for Full Moon by using the devia- tion produced by a vessel of hot water as a term of comparison. The relative amount of solar and lunar radiation thus found was 898193. se eee ae (e) which is quite as near that given by (0) as we could epee wnt we con- sider the roughness of the data. As a further confirmation of the correctness of the two rough approxi- mations to the value of the ratio existing between the sun’s and the moon’s radiant heat already given, the subject was investigated from a purely theoretical point of view. It was assumed (1) That the quantity of heat leaving the moon at any instant may with- out much error be considered the same as that falling on it at that instant. (2) That the absorptive power of our atmosphere is the same for lunar and solar heat. (3) That, as was already assumed in obtaining formula (a), the moon is a smooth sphere not capable of reflecting light regularly. Then the heat which ipayes the moon in all directions = quantity which falls on the of the quantity which falls on the earth from the sun =K {" {(w—e).cose+ sine} sine.de= t 3x. 0 moon >——; 13° = The part which falls on the earth 1 =K APF o—0 cose+ sine} sine. de 0 2+ cos (1° 55’) al — sin (1°55) | — — 7 * { —7n .versin (1° 55')+ = = . E suppose ; therefore (if we may be allowed the expression) sun-heat — 13°55 x 3a moon-heat E = a (quam proximé). . . . (d) In the above, the proportion between the areas of surface presented by the moon and earth to the sun is taken =13°55, and the angle subtended by the earth at the moon =1° 55’. The value of the readings of the galvanometer was determined by compa- rison with those obtained by using a vessel of hot water coated with shellac and lampblack varnish asa source of heat. The vessel was of tin, circular, and subtended the same angle at the small concave reflectors as the large mirror of the telescope. It was thus found that (the radiating power of the moon being supposed equal to that of the lampblack surface and the earth’s atmosphere not to influence the result) a deviation of 90 for full 1869.] New Arrangement of Binocular Spectrum-Microscope. 448 moon appears to indicate an elevation of temperature through 500° Fahr.* In deducing this result allowance has been made for the imperfect ab- sorption of the sun’s rays by the lunar surface. In the present imperfect state of these observations it would be prema- ture to discuss them at greater length; but as some months must elapse before any more complete series can be obtained, and the present results are sufficient to show conclusively that the moon’s heat is capable of being detected with certainty by the thermopile, I have thought it best to send this account to the Royal Society ; and I shall be most happy to receive suggestions as to improvements in the method of working, and as to the direction in which it may be most desirable to carry on future experiments. IV. “On a New Arrangement of Binocular Spectrum-Microscope.” By Witxitam Crookes, F.R.S. &c. Received April 23, 1869. The spectrum-microscope, as usually made, possesses several disadvan- tages: it is only adapted for one eyet ; the prisms having to be introduced over the eyepiece renders it necessary to remove the eye from the instru- ment, and alter the adjustment, before passing from the ordinary view of an object to that of its spectrum, and vice versd; the field of view is limited, and the dispersion comparatively small. I have devised, and for some time past have been working with, an in- strument in which the above objections are obviated, although at the same time certain minor advantages possessed by the ordinary instrument, such as convenience of examining the light reflected from an object, and com- paring its spectrum with a standard spectrum, are not so readily associated with the present form of arrangement. The new spectrum-apparatus consists of two parts, which are readily attached to an ordinary single or binocular microscope ; and when attached they can be thrown in or out of adjustment by a touch of the finger, and may readily be used in conjunction with the polariscope or dichrooscope ; object-glasses of high or low power can be used, although the appearances are more striking with a power of 3-inch focus or longer ; and an object as small as a single corpuscle of bloodcan be examined anditsspectrum observed. * This may seem a very large rise of temperature ; but it is quite in accordance with the views of Sir John Herschel on the subject (Ontlines of Astronomy, section 432 and preceding sections), where he says that, in consequence of the long period of rotation of the moon on its axis, and still more the absence of an atmosphere, “‘ The climate of the moon must be most extraordinary, the alternation being that of unmitigated and burning sun- shine, fiercer than that of an equatoreal noon; and the keenest severity of frost, far ex- ceeding that of our polar winters, for an equal time.” And again, ‘‘.... the surface of the full moon exposed to us must necessary be very much heated, possibly to a degree much exceeding that of boiling water.” + Mr. Sorby in several of his papers (Proc. Roy. Soc. 1867, xv. p. 433; ‘How to Work with the Microscope,’ by L. Beale, F.R.S., 4th edition, p. 219) refers to a binocular spectrum-microscope; but he gives no description of it, and in one part says that it is not suited for the examination of any substance less than ¥, of au inch in diameter. 444, Mr. W. Crookes on a New Arrangement of [May 27, The two additions to the microscope consist of the substage with slit &c., and the prisms in their box. The substage is of the ordinary con- struction, with screw adjustment for centring, and rackwork for bringing it nearer to or withdrawing it from the stage. Its general appearance is shown in fig. 1, which represents it in position. A B is a plate of brass, Fig. 1. WwW sliding in grooves attached to the lower part of the substage; it carries an adjustable slit, C, a circuiar aperture, D, 0°6 inch in diameter, and an | aperture, O, 3 inch square. A spring top enables either the slit or one of the apertures to be brought into the centre of the field without moving the eye from the eyepiece. Screw adjustments enable the slit to be widened or narrowed at will, and also varied in length. At the upper part of the sub- stage is a screw of the standard size, into which an object-glass of high power is fitted. E represents one in position. I generally prefer a 3-inch power; but it may sometimes be found advisable to use other powers here. 1869.] . Binocular Spectrum- Microscope. 445 The slit C and the object glass E are about 2 inches apart; and if light is reflected by means of the mirror along the axis of the instrument, it is evident that the object-glass E will form a small image of the slit C, about 0-3 inch in front of it. The milled head F moves the whole substage up or down the axis of the microscope, whilst the screws G and H, at right angles to each other, will bring the image of the slit into any desired part of the field. If the slide A B is pushed in so as to bring the circular aperture D in the centre, the substage arrangement then becomes similar to the old form of achromatic condenser. Beneath the slit C is an arrange- ment for holding an object, in case its surface is too irregular, or substance too dense, to enable its spectrum to be properly viewed in the ordinary way*. Supposing an object is on the upper stage of the microscope (shown in fig. 2) and viewed by light transmitted from the mirror through the large aperture D and the condenser E, by pushing in the slide A B s0 as to bring the slit C into the field, and then turning the milled head F, it is evi- dent that a luminous image of the slit C can be projected on to the object; and by proper adjustment of the focus, the object and the slit can be seen together equally sharp. Also, since the whole of the light which illumi- nated the object has been cut off, except that portion which passes through the slit, all that is now visible in the instrument is a narrow luminous line, in which is to be seen just so much of the object as falls within the space this line covers. By altering the slit-adjustments the length or width of the luminous line can be varied, whilst by means of the rackwork attached to the upper stage, any part of the object may be superposed on the luminous line. The stage is supplied with a concentric movement, which permits the object to be rotated whilst in the field of view, so as to allow the image of the slit to fall on it in any direction. During this examination a touch with the finger will at any time bring the square aper- ture O, or the circular aperture D into the field, instead of the slit, so as to enable the observer to see the whole of the object; and in the same manner the slit can as easily be again brought into the field. The other essential part of this spectrum-microscope consists of the prisms. These are enclosed in a box, shown at K (fig. 2). The prisms are of the direct-vision kind, consisting of three flint and two crown, and are altogether 1°6 inch long. The box screws into the end of the micro- scope-body at the place usually occupied by the object-glass ; and the ob- ject-glass is attached by a screw in front of the prism-box. It is shown in its place at L. The prism-box is sufficiently wide to admit of the prisms being pushed to the side when not wanted, so as to allow the light, after passing * In carrying out the experiments which were necessary before this spectrum-micro- scope could be made in its present complete form, I have been greatly assisted by Mr.C. _ Collins, Philosophical-Instrument Maker, 77 Great Tichfield Street, to whom I am also indebted for useful suggestions as to the most convenient arrangement of the different parts, so as to render them easily adapted to microscopes of ordinary construction. 446 Mr. W. Crookes on a New Arrangement of [May 27, through the object-glass, to pass freely up the tube K. A pin at M en- ables the prisms to be thrown either in or out of action by a movement of the finger. As the prisms are close above the object-glass, the usual sli- ding box, carrying the binocular prism and the Nicol’s prism (shown at N), may be employed as usual, and the spectrum of any substance may thus be examined by both eyes simultaneously, either by ordinary light, or when it is under the influence of polarized light. The insertion of the prism-box between the object-glass and the body of the microscope does not interfere with the working of the instrument in theordinary manner. The length of the tube is increased 1 or 2 inches, and a little additional rackwork may in some instruments be necessary when using object-glasses of low power. The stereoscopic effect when the Wenham prism is put into action does not appear to be interfered with. \ “i sa al \. RAS: ; aie / Ce AN ; ( Booey / 2 |e Bs E B/S Zz FY -{& { A 4 = Wi = —= he y: ‘nun \ -) NY y A 5) < _— feet iat nt aaeal| \ ( For ordinary work both these additions may be kept attached to the mi- croscope, the prisms being pushed to the side of the prism-box, and the large aperture D being brought into the centre of the substage. When it is desired to examine the spectrum of any portion of an object in the field 1869. ] | Binocular Spectrum-Microscope. 44,7 of view, all that is necessary is to push the slit into adjustment with one hand, and the prisms with the other. The spectrum of any object which is superposed on the image of the slit is then seen. The small square aperture at O (fig. 1) is for the examination of dichroic substances. When this is pushed into the field, by placing a double-image prism P between A B and E, two images of the aperture are seen in juxta- position, oppositely polarized; and if a dichroic substance is on the stage, the differences of colour are easily seen. When the spectrum of any substance is in the field and the double-image prism P is introduced, two spectra are seen, one above the other, oppositely polarized, and the variations in the absorption-lines, such as are shown by didymium, jargonium, &c., are at once seen. A Nicol’s prism, Q, as polarizer, is also arranged to slip into the same position as the double-image prism, and another, R, as analyzer, above the prism-box. The spectra of the brilliant colours exhibited by certain erys- talline bodies, when seen by polarized light, can then be examined. Many curious effects are then produced, a description of which I propose to make the subject of another paper. Both the prisms P and Q are capable of rotation. If the substance under examination is dark coloured, or the illumination is not brilliant, it is best not to divide the light by means of the Wenham prism at N, but to let the whole of it pass up the tube to one eye. If, however, the light is good, a very great advantage is gained by throwing the Wenham prism into adjustment and using both eyes. The appearance of the spectrum, and the power of grasping faint lines, are incomparably superior when both eyes are used; whilst the stereoscopic effect it confers on some absorption and interference spectra (especially those of opals) seem to throw entirely new light on the phenomena. No one who has worked with a stereoscopic spectrum-apparatus would willingly return to the old monocular spectroscope*. If the illumination in this instrument is taken from a white cloud or the sky, Fraunhofer’s lines are beautifully visible; and when using direct sun- light they are seen with a perfection which leaves little to be desired. The dispersion is sufficient to cause the spectrum to fill the whole field of the .microscope, instead of, as in the ordinary instrument, forming a small por- tion of it, the dispersion being four or five times as great ; whilst, owing to the very perfect achromatism of the optical part of the microscope, all the lines from B to G are practically in the same focus. As the only portion of the object examined is that part on which the image of the slit falls, and as this is very minute (varying from 0°01 to * It is not difficult to convert an ordinary spectroscope into a binocular instrument. The rays after leaving the object-glass of the telescope are divided into two separate bundles and received on two eyepieces properly mounted. As it is immaterial whether the spectrum be stereoscopic or pseudoscopic, a simpler form of prism than Mr. Wen- ham’s arrangement can be used. 448 Mr. W. Crookes on some Optical Phenomena of Opals. [May 27, 0:001 inch, according to the actual width of the slit), it is evident that the spectrum of the smallest objects can be examined. If some blood is in the field, it is easy to reduce the size of the image of the slit to dimensions covered by one blood-disk, and then, by pushing in the prisms, to obtain its spectrum. If the object under examination will not transmit a fair image of the slit Gf it be a rough crystal of jargoon for instance), it must be fixed in the universal holder beneath the slit and the light concentrated on it be- fore it reaches the slit. If the spectra of opaque objects are required, they can also be obtained in the same way, the light being concentrated on them either by a parabolic reflector or by other appropriate means. By replacing the illuminating lamp by a spirit-lamp burning with a soda- flame, and pushing in the spectrum-apparatus, the yellow sodium-line is seen beautifully sharp; and by narrowing the slit sufficiently it may even be doubled. Upon introducing lithium or thallium compounds into the flame, the characteristic crimson or green line is obtained; in fact so readily does this form of instrument adapt itself to the examination of flame-spectra, that for general work Ihave almost ceased to use a spectro- scope of the ordinary form. The only disadvantage I find is an occasional deficiency of light; but by an improved arrangement of condensers I hope soon to overcome this difficulty. V. “On some Optical Phenomena of Opals.” By Witi1am Crookes, F.R.S. &c. Received April 23, 1869. When a good fiery opal is examined in day-, sun-, or artificial light, it appears to emit vivid flashes of crimson, green, or blue light, according to the angle at which the incident light falls, and the relative position of the opal and the observer ; for the direction of the path of the emitted beam bears no uniform proportion to the angle of the incident light. Examined more closely, the flashes of light are seen to proceed from planes or sur- faces of irregular dimensions inside the stone, at different depths from the surface and at all angles to each other. Occasionally a plane emitting light of one colour overlaps a plane emitting light of another colour, the two colours becoming alternately visible upon slight variations of the angle of the stone; and sometimes a plane will be observed which emits crimson? light at one end, changing to orange, yellow, green, &c., until the other end of the plane shines with a blue light, the whole forming a wonder- fully beautiful solar spectrum in miniature. I need scarcely say that the colours are not due to the presence of any pigment, but are interference colours caused by minute strize or fissures lying in different planes. By turning the opal round and observing it from different directions, it is generally possible to get a position in which it shows no colour whatever. Viewed by transmitted light, opals appear more or less deficient in trans- parency and have a slight greenish yellow or reddish tinge. 1869.] Mr. W. Crookes on some Optical Phenomena of Opals. 449 In order to better adapt them to the purposes of the jeweller, opals are almost always polished with rounded surfaces, back and front; but the flashes of coloured light are better seen and examined when the top and bottom of the gems are ground and polished flat and parallel. A good opal is not injured by moderate heating in water, soaking in - turpentine, or heating strongly in Canada balsam and mounting as a microscopic slide. By the kindness of Mr. W. Chapman, of Frith Street, Soho, and other friends, I have been enabled to submit some thousands of opals to optical examination ; and from these I have selected about a dozen which appeared worthy of further study. If an opal which emits a fine broad crimson light is held im front of the slit of a spectroscope or spectrum-microscope, at the proper angle, the light is generally seen to be purely homogeneous, and all the spectrum that is visible is a brilliant luminous line or band, varying somewhat in width and more or less irregular in outline, but very sharp, and shining brightly ona perfectly black ground. If, now, the source of light is moved, so as to shine into the spectrum-apparatus through the opal, the above appearance is reversed, and we have a luminous spectrum with a jet-black band in the red, identical in position, form of outline, and sharpness with the luminous band previously observed. If instead of moving the first source of light (the one which gave the reflected luminous line in the red) another source of light be used for obtaining the spectrum, the two appear- ances, of a coloured line on a black ground, and a black line on a coloured ground, may be obtained simultaneously, and they will be seen to fit accu- rately. Those parts of the opal which emit red light are therefore seen to be opaque to light of the same refrangibility as that which they emit ; and upon ex- amining in the same manner other opals which shine with green, yellow, or blue light, the same appearances are observed, showing that this rule holds good in these cases also. It is doubtless a general law, following of necessity the mode of production of the flashes of colour. Having once satisfied myself that the above law held good in all the in- stances which came under my notice, I confined myself chiefly to the examination of the transmitted spectra, although the following descrip- tions will apply equally well, mutatis mutandis, to the reflected spectra. The examinations were made by means of the spectrum-microscope a de- scription of which I have just had the honour of sending to the Society. This instrument is peculiarly adapted to examinations of this sort, both on account of the small size of the object which can be examined in it, and also as it permits the use of both eyes in viewing the spectrum. The following is a brief description of some of the most curious transmis- sion spectra shown by these opals. The accompanying figures, drawn with the camera lucida, convey as good an idea as possible of the different ap- * pearances. The exact description will of course only hold good for one 450 Mr. W. Crookes on some Optical Phenomena of Opals. [May 27, portion of the opal; but the general character of each individual stone is well marked. No. 1 shows a single black band in the red. When properly in focus this has a spiral structure. Examined with both eyes it appears in decided relief, and the arrangement of light and shade is such as to produce a striking resemblance to a twisted column. No 2. gives an irregular line in the orange. Viewed binocularly, this exhibits the spiral structure in a marked manner, the different depths and distances standing well out; upon turning the milled head of the stage- adjustment, so as to carry the opal slowly from ieft to right, the spiral line is seen to revolve and roll over, altering its shape and position in the spec- trum. It is not easy to retain the conviction that one is looking merely at a band of deficient light in the spectrum, and not at a solid body, pos- sessing dimensions and in actual motion. No. 3 has a line between the yellow and green, vanishing to a point at the top, and near the bottom having a loop, in the centre of which the green appears. Higher up, in the green, is a broad green band, indistinct on one side and branching out in different parts. No. 4 has a broad, indistinct, and sloping band in the blue, and another, still more indistinct, in the violet. : No. 5 has a band in the yellow, not very sharp on one side, and some- what sloping. Upon moving the opal sideways, it moves about from one part of the yellow field to another. In one position it covers the line D, and is opaque to the sodium-flame of a spirit-lamp. No. 6 shows a curiously shaped band in the red, very sharp and = and terminating in one part at the line D. In the yellow there is a black dot. The spectrum of this opal showed by reflected light intensely bright red bands, of the shape of the transmission bands. On examining this opal with a power of 1 inch, in the ordinary manner, the portion giving this spectrum appeared to glow with intense red light, and was bounded with a tolerably definite outline. Without altering any other part of the microscope, the prisms were then pushed in so as to look at the whole surface of the opal through the prisms, but without the slit. The shape and appearance of the red patch were almost unaltered ; and here and there over other parts of the opal were seen little patches of homogeneous light, which, not having been fanned out by the prisms, retained their original shape and appearance. No. 7 shows a black patch in the red, only extending a little distance, — and a line in the yellow. On moving the opal the line in the red vanishes, and the other line changes its position and form. No. 8 shows the most striking example of a spiral rotating line which I have yet met with. On moving the opal sideways the line is seen to start from the red and roll over, like an irregularly shaped and somewhat hazy corkscrew, into the middle of the yellow. The drawing shows the appear- ance of this band in two positions. | 451 1869.] Mr. W. Crookes on some Optical Phenomena of Opals. No. 5. on LO: N 2. No. I VOL. XVII. 452 Mr. W.Crookes on some Optical Phenomena of Opals. [May 27, No. 9 is one of the most curious. A broad black and sharp band stretches diagonally across the green, touching the blue at the top and the yellow at the bottom. No. 10 gives a diagonal band, wide, but straight, and tolerably sharp across the green. By rotating these opals, 9 and 10, in azimuth, whilst in the field of the instrument, the lines can be made to alter in inclination until they are seen to slope in the opposite direction. No. 11 gives another illustration of a diagonal line, across the yellow and green, not extending quite to the top. No. 12 is one of the best examples I have met with of a narrow, straight, and sharply cut line. It is in the green, and might easily be mistaken for an absorption-band caused by an unknown chemical element. ' Other opals are exhibited which show a dark band travelling along the spectrum, almost from one end to the other, as the opal is moved side- ways. It is scarcely necessary to say that the colour of the moving luminous line varies with the part of the spectrum to which it belongs. The ap- pearance of a luminous line, slowly moving across the black field of the instrument, and assuming in turn all the colours of the spectrum, is very beautiful. All these black bands can be reversed, and changed into luminous bands, by illuminating the opal with reflected light. They are, however, more difficult to see ; for the coloured light is only emitted at a particular angle, whilst the special opacity to the ray of the same refrangibility as the emitted ray holds good for all angles. The explanation of the phenomena Is probably as follows :—In the case of the moving line, the light-emitting plane in the opal is somewhat broad, and has the property of giving out at one end, along its whole height and for a width equal to the breadth of the band, say, red light; this merges gradually into a space emitting orange, and so on throughout the entire length of the spectrum, or through that portion of it which is traversed by the moving line in the instrument, the successive pencils (or rather ribbons) of emitted light passing through all degrees of refrangibility. It is evident that if this opal is slowly passed across the slit of the spec- trum-microscope, the slit will be successively illuminated with light of gradually increasing refrangibility, and the appearance of a moving lumi- nous line will be produced ; and if transmitted light is used for illumination, the reversal of the phenomena will cause the production of a black line moving along a coloured field. A diagonal line will be produced if an opal of this character is examined in a sloping position. The phenomenon of a spiral line in relief, rolling along as the opal is moved, is doubtless caused by modifying planes at different depths and connected by cross planes; I can form a mental picture of a structure which would produce this effect, but not clear enough to enable me to de- seribe it in words. 1869.] Messrs. Frankland and Lockyer on Gaseous Spectra. 453 It is probable that similar phenomena may be seen in many, if not all, bodies which reflect coloured light after the manner of opals. A magnifi- cent specimen of Lumacelli, or Fiery Limestone, from Italy, kindly pre- sented to me by my friend David Forbes, shows two sharp narrow and parallel bands in the red. I have also observed similar appearances in > mother-of-pearl. The effects can be imitated to a certain extent by: examining ‘‘ Newton’s rings,” formed between two plates of glass, in the spectrum-instrument. June 3, 1869. The Annual Meeting for the election of Fellows was held this day. Lieut.-General SABINE, President, in the Chair. The Statutes relating to the election of Fellows having been read, Mr. Balfour Stewart and Dr. Maxwell Simpson were, with the consent of the Society, nominated Scrutators to assist the Secretaries in examining the lists. The votes of the Fellows present having been collected, the following Candidates were declared to be duly elected into the Society. Sir Samuel White Baker, M.A. John Russell Reynolds, M.D. John J. Bigsby, M.D. Vice-Admiral Sir Robert Spencer Charles Chambers, Esq. Robinson, K.C.B. William Esson, Esq., M.A. Major James Francis Tennant, R.E. Prof. George Carey Foster, B.A. Prof. Wyville Thomson, LL.D. William W. Gull, M.D. Col. Henry Edward Landor Thuillier, J. Norman Lockyer, Ksq. R.A. John Robinson M°Clean, Esq. Edward Walker, Esq., M.A. St. George Mivart, Esq. Thanks were voted to the Scrutators. June 10, 1869. Lieut.-General SABINE, President, in the Chair. Dr. J. J. Bigsby, Prof. G. Carey Foster, Mr. J. R. M°Clean, Mr. St. George Mivart, and Dr. J. Russell Reynolds were admitted into the Society. The following communications were read :— I. “ Researches on Gaseous Spectra in relation to the Physical Con- stitution of the Sun, Stars, and Nebulz.”—Second Note. By HE. Franxianp, F.R.S., and J. N. Locxyrr. Received May 5, 1869. | : We beg to lay before the Royal Society some further results of the re- searches on which we are engaged. : 22 454. On Macrauchenia patachonica, Ow. [June 10, I. The Fraunhofer line on the solar spectrum, named A by Angstrém, which is due to the absorption of hydrogen, is not visible im the tubes we employ with low battery and Leyden-jar power ; it may be looked upon therefore as an indication of relatively high temperature. As the line in question has been reversed by one of us in the spectrum of the chromo- sphere, it follows that the chromosphere, when cool enough to absorb, is still of a relatively high temperature. II. Under certain conditions of temperature and pressure, the very com- plicated spectrum of hydrogen is reduced in our instrument to one line in the green corresponding to F in the solar spectrum. Ili. The equally complicated spectrum of nitrogen is similarly reducible to one bright line in the green, with tracesof other more refrangible faint lines. IV. From a mixture of the two gases we have obtained a combination of the spectra in question, the relative brilliancy of the two bright green lines varying with the amount of each gas present in the mixture. V. By removing the experimental tube a little further away from the slit of the spectroscope, the combined spectra referred to in II. & III. were reduced to the two bright lines. VI. By reducing the temperature all spectroscopic evidence of the nitrogen vanished ; and by increasing it, many new nitrogen-lines make their appearance, the hydrogen-line always remaining visible. The bearing of these latter observations on those made on the nebulze by Mr. Huggins, Father Secchi, and Lord Rosse is at once obvious. The visibility of a single line of nitrogen has been taken by Mr. Huggins to in- dicate possibly, first, ‘‘a form of matter more elementary than nitrogen, and which our analysis has not yet enabled us to detect *, and then, secondly, “‘a power of extinction existing in cosmical space ’’ y. Our experiments on the gases themselves show not only that such assumptions are unnecessary, but that spectrum analysis here presents us with a means of largely increasing our knowledge of the physical constitu- tion of these heavenly bodies. Already we can gather that the temperature of the nebule is lower than that of our sun, and that their tenuity is excessive; it is also a question whether the continuous spectrum observed in some cases may not be due to gaseous compression. IT. “On the Molar Teeth, lower Jaw, of Macrauchenia patachonica, — Ow.” By Professor Owen, F.R.S. Received April 21, 1869. (Abstract.) The intraneural course of the vertebral arteries is limited, in the class Mammalia, to the Ungulate Series, and is present in very few of these. Of * Phil. Trans. 1864, p. 444. t Thid. 1868. p. 544. © 1869. ] On the Action of Hydrochloric Acid on Morphia. A55 existing species it characterizes the Camelide, occurring also, as shown in Palauchenia, in the fossil form of that family ; but this rare disposition of the vertebral arteries was likewise met with in a large fossil Ungu- late of South America, Macrauchenia, belonging to the Perissodactyle group*. The author therefore communicates, as an appendix to his former paper on Palauchenia, a description, with drawings, of the mandibular dentition of Macrauchenia patachonicha, of the natural size, the lewer jaw of that fossil animal being still a unique specimen in the British Museum. It displays the entire molar series, with the exception of the first small pre- molar: the several teeth in place are described in detail and compared with those of other Perissodactyles. The grinding-surface of the true molars presents the bilobed or bicrescentic type, as in Paleotherium and Rhino- ceros; but Macrauchenia differs from both those genera in the limitation of the assumption of the molar type to the last premolar, the antecedent ones retaining the single-lobed crown. From Paleotherium it further dif- fers in the last molar being bilobed, as in Rhinoceros, not trilobed. In Palauchenia all the premolars have the simpler structure, as in Artiodac- tyles generally. Macrauchenia resembles Anoplotherium and Dichodon in retaining the typical dentition, ‘==, c= p—> m— =44, and in the uninterrupted course of the dental series, not any of the teeth having a crown much higher or longer than the rest. The paper is illustrated by drawings. III. “ Researches into the Chemical Constitution of the Opium Bases. Part I.—On the Action of Hydrochloric Acid on Mor- phia.” By Aveustus Marruisssen, F.R.S., Lecturer on Chemistry in St. Bartholomew’s Hospital, and C. R. A. Wrieur, B.Sc. Received May 6, 1869. It has been shown that when narcotine is heated with an excess of con- centrated hydrochloric or hydriodic acid, one, two, or three molecules of methyl are successively eliminated, and a series of new bases homologous with narcotine obtained. It appeared interesting to see if any similar re- actions took place with morphia; and for this purpose a quantity of that base, in a perfectly pure state, kindly furnished by Messrs. M‘Farlane, of Edinburgh, was submitted to experiment. The purity of the substance was shown by the following analysis. It was found that although crystallized morphia does not lose its water of crystallization in an ordinary steam drying-closet (7. e. slightly below 100°), yet it readily loses the whole when placed in a Liebig’s drying-tube immersed in boiling water, dry air being aspirated over it. * Odontography, 1846, p. 602. 456 Messrs. A. Matthiessen and C. R. A. Wright on the [June 10, (1) 1:824 gramme of M‘Farlane’s morphia thus lost 0-111 gramme. : (2) 2°458 grammes Be i 0°145 i. (3) 2°312 es Me , after recrystallization from boiling alcohol, lost 0°148 gramme. Calculated. Found. (L) Gaye. GL) HO 18 5°94 6°09 5°90 6°40 C,, H,, NO, 285 94°06 we C,, H,, NO,+H,O0 303 100:00 Combustions of morphia with oxide of copper and oxygen :— (I.) 0°3015 gramme of M‘Farlane’s morphia, dried at 120°, gave 0°7930 carbonic acid and 0°1890 water. (II.) Morphia recrystallized from boiling alcohol, and dried at 120° :— 0°3635 gramme gave 0°9535 carbonic acid and 0°2230 water. Calculated. Found. (1.) (II.) C.. 204 71:58 71°91 71°54 H, 19 6°66 6°97 6°81 N 14 4°91 O, 48 16°85 C,,H,NO, 285 100-00 Morphia recrystallized from boiling alcohol, and dried below 100° :— 0°3575 gramme gave 0°8780 carbonic acid and 0°234 water. Calculated. Found. C., 204 67°33 67°00 isle 21 6°93 f Le N 14 4°62 O, 64 ZAcheZ C,, H,, NO, H,0 303 100°00 When morphia is sealed up with a large excess of hydrochloric acid (about 10 cub. centims. of ordinary acid, of about 35 per cent. HCl to each gramme of morphia), and heated to 140°—150° for two or three hours, on opening the tubes after cooling no gas is found to have been formed, nor is there any formation of chloride of methyl. The residue in the tube contains - the hydrochlorate of a new base, differing considerably in its properties from morphia. It may be obtained in a state of purity by dissolving the con- tents of the tube in water, adding excess of bicarbonate of sodium (not the ordinary carbonate Na, CO,, nor caustic soda, as these hasten the decom- position of the precipitated base), and extracting the precipitate with ether or chloroform, in both of which the new base is readily soluble, whilst morphia is almost insoluble in both menstrua. On shaking up the ether 1869. | Action of Hydrochloric Acid on Morphia. 457 or chloroform solution with a very small quantity of strong hydrochloric acid, the sides of the vessel become covered with crystals of the hydrochlo- rate of the new base. These may be drained from the mother-liquor, washed with a little cold water, in which the salt is sparingly soluble, and — recrystallized from hot water and dried on bibulous paper or over sulphuric acid. No difference in the result appeared to be produced by continuing the digestion at 150° for six or twelve hours. The new base may also be formed by digesting morphia and excess of hydrochloric acid under paraffin on the water-bath for some days. This hydrochlorate contains no water of crystallization. After drying in the water-bath, it yielded the following results on combustion with chromate of lead and oxygen :— (I.) 0°4300 gramme gave 1:0600 carbonic acid and 0:237 water. (II.) Sample (I.), recrystallized, and again dried in water-bath. 0°3270 gramme gave 0°8045 carbonic acid and 0°1830 water. (III.) 0°3830 gramme, burnt with soda-lime, gave 0°1240 metallic pla- tinum. (IV.) 0°4720 gramme, burnt with soda-lime, and the ammonia estimated volumetrically, gave 0°0234 nitrogen. (V.) 0°4680 gramme, precipitated by nitrate of silver and nitrie acid,- gave 0°2170 chloride of silver. (VI.) 0°3410 gramme, burnt with lime, gave 0°1645 chloride of silver. Calculated. Found. ; Gn? (EE ee (LEE) (EVA Vie) a GVFES) cs 204. 67:22 67:23 67:10 ue 18 5:93 G12. 6:21 N 14 4-61 460 4:95 Oo, 32 10°54 Cl ea yl 70 11:50 11:93 C,,H,,NO,HCl 3035 100-00 From a solution of the hydrochlorate in water, bicarbonate of sodium precipitates a snow-white non-crystalline mass, which speedily turns green on the surface by exposure to air, and is therefore difficult to obtain dry in a state of purity. The followimg combustion of a portion washed with water, and dried at 100° as rapidly as possible, shows that this precipitate is the base itseif. 0°3310 gramme gave 0:9250 carbonic acid and 0°1830 water. Calculated Found. C.,, 204 76°40 76-22 IL, tS ey 6-37 6°15 N 14 5°24 32 11°99 eee CAH NO, 267. 100-00 458 Messrs. A. Matthiessen and C.R. A. Wright on the [June 10, This substance was free from chlorine, as shown by its giving no preci- pitate with nitrate of silver after heating with nitrie acid. It hence appears that the new base is simply formed from morphia by _ the abstraction of the elements of water. Mozrphia. New base. C,, H,, NO,=H,0+C,, H,, NO,, the reaction under the influence of hydrochloric acid being perfectly analo- gous to that by which kreatine, under the influence of strong acid, splits up into water and kreatinine. Kreatine. Kreatinine. C,H, N, 0,=H,0+C, H, N,O. We propose to call the new base apomorphia, for reasons given subse- quently. When the hydrochlorate of apomorphia in a moist state is exposed to the air for some time, or if the dry salt is heated, it turns green, probably from oxidation, as the change of colour is accompanied by an increase of weight. The base itself, newly precipitated, is white, but it speedily turns green on exposure to air. The green mass is partly soluble in water, com- municating to it a fine emerald colour—in alcohol yielding also a green, in ether and benzole giving a magnificent rose-purple, and in chloroform producing a fine violet tint. The following Tables show the most marked properties and reactions of apomorphia as contrasted with morphia. } | Water. Alcohol. Ether. - | Chloroform. : Morphia ...... | Almost insolu- Sparingly so-, Almost insolu- | Almost insolu- ; | | ble. luble cold,!| ble. | ble. | | more soluble | | boiling. —= es | oe EEE ee | Apomorphia ...| igay solu- | Soluble. | Soluble. | Soluble. ble, especially | | | if charged | | with carbonic | acid. | | The following comparative reactions were made with solutions contain- — - ing each 1 per cent. of the hydrochlorate of the base :— 459 Action of Hydrochloric Acid on Morphia. 1869.] ‘souo viydaouode sutpuodsoatoo oyy ueyy eTqnTos o1our YONUL ore syuOsvOL osoy} Uji soyeyrd -1o0ad viydrour ou, “UINTUOULULy jo oye[exgQ ‘untip -0og jo oyeydsoug ‘OplLto[yO oLnoso pl “SUTULIG A uo — sosoduooep ‘oyepidrooad §=mMoT]o xX "SUOTINOS 195 00.148 UL oyeqidrooad "Ud0Id surutooeq A{tpaeds ‘oyeqidioord = OUT -[eysh10-UOU OFT] AA stor -NJOS poyeayud0u00 eurppeysho §=mozjox | Wyrm oyeqtdrooad ONT ‘OpMMOTYD oLMNyeig |wMIsseyog. Jo oprpoy *INOT -o00-yskqjoule yaeq ‘anojoo onyq oand w “SULTATIVA TO sozed = Ssuruooeq ‘Ino[oo poed-pool_ ‘SUL SOATS OUR BI dAoP | -TLeEM TO porouayq “NOT -09 Be ONT OTAIO | [BM9 py qsouye ‘nor enq{q- Meneane) -00-09URIO MOTIOX “preoy OMEN, SOAS "ploo et} ur WdAO ‘poonpoer Atyom’y ‘poonp -ar ATMoys «104 “IOATIG JO OYCIGINT —-~ SHOUT -e.10[00 ‘ploy ormuydqng suows pure umis -Sv}Og Jo ayvumoayorg, "M9018 surmmy ‘ssooxo ur etqnpos ATyY SITs ‘oqeqidiooad = 941 AA "s900X0 Ul 9[q -njos ATWysI[s 94%9 -idioaid += o[qeaoqye -un oytya @ pyors SUOTINTOS deduU0.A4G Oe jo oyeuogavorg ‘ayeqtdrooad 0 yp ‘outuoyaep ATMOTS ‘sso0xo UT 9[qnTos ‘ageqidroord §=—oqTy AA “TOYOM -omllT UL ATIproda goATossip weryd.aoyAl ‘oyeytdrooad Oy “LOVCM-OULITT ‘Suruoyoryq Ajrpoods Atos ‘sso0xo UL 9[qny{os ‘oqeqidtoord Og ttL AA. "$800 -x9 UL oTqnjosuUt ‘oyeqtdroord oyrtpad ourypeyshao @ oats SUOTN]OS a«oesuoayg "eIUOWLUL ‘oyeqtdrooad op “sursoduiooep uoos ‘oyezdiooad pol-yareq, | odurs0 Moro osttocy "TUNISSey -Og jo oyeuroayoug ea erydaronody eee eran wiydaoyfy ‘suru -uoyoetq AyTtpoods ‘gs00x9 UL 9[qnTOs ‘ayeqtdrooad = ory |’ erydaouody LO) -1soduiooop sulosd -opun ynoyyiaAr ‘gg00xO UL 9]qN] -os Ayipeoa oye91d 10 -o1d o4It[M @ OATS SUOINTOS AOdU0.14G ee ‘eqeyidioead on | CEO ‘ysejog osnep "* juod voy 460 Messrs. A. Matthiessen and C. R.A. Wright on the [June 10, The physiological effects of apomorphia are very different from those of morphia; a very small dose produces speedy vomiting and considerable depression, but this soon passes off, leaving no after ill effects,—facts of which we have repeatedly had disagreeable proof while working with it. Dr. Gee is now studying these effects, and has found that +1, of a grain of the hydrochlorate subcutaneously injected, or 7 grain taken by the mouth, produces vomiting in from four to ten minutes. Our friend Mr. Prus al- lowed himself to be injected with ;!, grain, which produced vomiting in less than ten minutes. From Dr. Gee’s experiments on himself and others, he concludes that the hydrochlorate is a non-irritant emetic and powerful anti- stimulant. As from these properties it appears probable that it may come into use in medicine, we have called it apomorphia, rather than morphinine, to avoid any possible mistakes in writing prescriptions. Apomorphia is likewise formed by heating morphia and dilute sulphuric acid (1 vol. acid to 8 or 10 of water) in sealed tubes to 140°-150° for three hours. It appears possible that the substance obtained by Arppe *, sub- sequently named sulphomorphide by Laurent and Gerhardt f, is an impure sulphate of apomorphia, as the formula deduced by these latter chemists from their analysis, C,,H,,N,O,8, is identical with that of this sul- phate, (C,, H,, NO,), H,SO,. They, however, considered it a species of amide. On repeating Arppe’s experiments, we have obtained apomorphia from the product. The physical characters ascribed to sulphomorphide (of becoming green on keeping, especially on heating, of communicating this green tint to water, and of solubility in caustic alkalies, producing a brown substance by decomposition) are precisely those of the hydrochlorate of apomorphia. It appears probable that the class of analogous bodies pro- duced from other alkaloids by similar means, such as sulphonarcotide, may possibly be the sulphates of new bases. We propose to submit these to ex- periment, and to prosecute our researches on the opium bases. On sealing up codeia with hydrochloric acid and digesting it at 150°, we find some permanent gas is evolved, probably chloride of methyl, in which case the new base, if any, will be morphia or apomorphia or their isomers, as codeia differs from morphia only by CH,,. IV. “Researches into the Constitution of the Opium Bases. Part I1.—On the Action of Hydrochloric Acid on Codeia.” By Aveustus Marrutsssen, F.R.S., Lecturer on Chemistry in St. Bartholomew’s Hospital, and C. R. A. Wricut, B.Sc. Re- — . ceived June 2, 1869. Codeia and morphia are, as is well known, homologous, only differing in composition by CH,. Both of them contain one atom of hydrogen re- placeable by organic radicals, from which it appears that methyl-morphia * 1845. Ann. der Chem und Pharm. vol. lv. p. 96. t+ Ann. de Chimie et-de Phys. [3] vol. xxiv. p. 112. 1869. ] Action of Hydrochloric Acid on Codeia. 461 (which does not contain a replaceable atom of hydrogen) is only isomeric with codeia, and not identical. If, therefore, codeia be morphia where H is replaced by CH,, the atom of hydrogen so replaced must be one of those contained in one of the radicals which enter into the composition of mor- phia. Thus— Morphia. Methyl-morphia. Codeia. C,, HH, HNO, C,, H,, (CH,) NO, Cr Lib H NO, H H CH, The action of hydrochloric acid on morphia * leads to the elimination of H,O, and the formation of a new base, apomorphia, thus— Morphia. . Apomorphia. ere NO — HO CH NO ccc. + he ce CL) Codeia under the same circumstances might yield a similar base, apo- codeia, thus— Codeia. Apocodeia. eH. NO. —H.0-+.C,, Hi, NOje gs. Rice gle a9 ae (2) Or it might behave like narcotine +, which, under the same conditions, splits up into chloride of methyl] and the hydrochlorate of a uew base. Thus with codeia— Codeia. Morphia. eee mE HCI—Cl Ci4-C. Ht, HINO,; |...-0..0.0 0! (3) but, as has already been shown, if morphia were thus produced, it would be converted, under the circumstances, into water and apomorphia, so that the whole reaction would be— Codeia. Apomorphia. C,, H,, (CH,) H NO, + HC1=CH, Cl+ H,0+C,, H,, NO,.........(4) In order to examine the nature of the reaction taking place, some codeia (forming part of 2 supply of 10 oz. given to us by the eminent manufactu- ring chemists, Messrs. M‘Farlane, of Edinburgh).was submitted to experi- ment. The substance used when examined for morphia failed to indicate the presence of the smallest trace, was wholly soluble in ether, and, on combustion with oxide of copper and oxygen, after drying at 120°, yielded the followig numbers :— , 0°3720 gramme gave 0°9830 carbonic acid and 0°2450 water. Calculated. Found. Ce 216 TPP ay F207 H,, 21 7-02 7°32 N 14 4:68 O 48 16°05 ow C,,H,NO, 299 100-00 Codeia was sealed up with from twelve to twenty times its weight of * Proc. Roy. Soc. vol. xvi. p. 499. 1 Proc. Roy. Soc. vol. xvu. p. 337. NN 4.62 Dr. B. Stewart on the Kew Magnetic Curves. [June 10, strong hydrochloric acid, and heated to about 140° for two or three hours. After cooling, a layer of colourless liquid was observed floating on the top of the brown tarry contents. It immediately became gaseous on opening the tubes, and was presumedly chloride of methyl, as the issuing gases were found to be free from carbonic acid. The residue in the tubes, when dis- solved in water and precipitated by carbonate of sodium, yielded, on extrac- tion with ether and agitation with hydrochloric acid, a crystalline chloride having, when purified by recrystallization, all the properties of the chloride of apomorphia derived from morphia. It gave the same qualitative reactions, produced the same remarkable physiological effects, and yielded the follow- ing numbers on combustion with chromate of lead and oxygen :— 0°3120 gramme gave 0°7680 carbonic acid and 0°1740 water. Calculated. Found. Ce 204 67522 Op ae be H, 18 3°93 6°19 N 14 4°61 O, bs 10°54 Cl E 30°) 11°70 C,, H,, NO, HCl 303°5 100°00 Hence the reaction which takes place is in accordance with formula (4) above, viz. Codeia. Apomorphia. C,, H,,(CH,) HNO,-+ HCI=CH, Cl+ H,0+C,, H,, NO.. Doubtless there is an intermediate reaction, viz. either that indicated by formula (3), where morphia is the intermediate product, or that in ac- cordance with (2), where a base homologous with apomorphia, and thence called apocodeia, is first produced, and subsequently split up ito apo- morphia and chloride of methyl, thus— Apocodeia. Apomorphia. C,, H,, NO, +HCI=CH, Cl+C,, H,, NO,. We are at present engaged in investigating the nature of this interme- diate reaction. V. “A Preliminary Investigation into the Laws regulating the Peaks and Hollows exhibited in the Kew Magnetic Curves for the first two years of their production.” By Batrour — Stewart, LL.D., F.R.S., Supermtendent of the Kew Obser- vatory. Received May 20, 1869. The Kew magnetographs began to be in regular operation in May 1858, and have continued so up to the present date. The curves derived from these instruments, representing the changes which take place in the three components of the earth’s magnetism at Kew, are often found to be studded with small serrated appearances, which have been denominated peaks and 1869. | Dr. B. Stewart on the Kew Magnetic Curves. 463 hollows ; and the following remarks will serve to show that the study of these may be attended with considerable advantage. The labours of General Sabine have been instrumental in showing that there are at least two forces concerned in producing disturbances ; and this conclusion is confirmed by the appearance of the Kew curves, from which - it may be seen that no disturbance of any magnitude is due to the action of a single force merely varying m amount and not in direction; for if this were the case the distance at any moment of a point in the curve of one of the elements from its normal position should bear throughout such a disturbance an invariable proportion to the distance of a corresponding point in the curve of another of the elements from its normal ; but this is by no means the case. It becomes therefore a question of interest to endeavour to find the elementary forces concerned in producing a disturbance ; and it is thought that this knowledge may to some extent be attained by a study of those small and rapid changes of force which are denoted by peaks and hollows. For if several independent forces are at work, it may be thought unlikely that at the same moment a sudden change should take place in all; there is thus a probability that sudden changes of force, as exhibited in peaks and hollows, are changes in one of the elementary forces concerned, which may thus enable us to determine the nature of that force. Even if the change is not a very abrupt one, provided that we confine ourselves to such peaks and hollows as present a similar appearance for all the curves, we may suppose that we are observing changes in one only of the ele- mentary disturbing forces ; for it is unlikely that two or more independent forces, changing independently, should produce similar appearances in all of the three curves. Thus what we have to look for is similar appearances; and the precise meaning attached to this expression will be rendered clear by means of the annexed graphical representation. We see here that (time being reckoned horizon- tally) we have a disturbance commencing at the Hor. force. same moment in each of the three elements, that for the declination being throughout three times as__ Vert. force. large, and that for the annexed furce twice as large as the corresponding vertical-force disturbance. In a paper communicated by me to the Royal Society, and published in the Transactions (1862, page 621), it was stated that, as a rule, small and abrupt disturbances at Kew tend either to increase at the same moment both components of magnetic force and the westerly declination, or to decrease these elements, as the case may be. As in the Kew curves of 1862, increasing ordinates represented decreasing horizontal force, decreas- ing vertical force, and decreasing declination, the above statement is the asme as saying that, as a rule, peaks and hollows in one element correspond to peaks and hollows in the other two. : Declination. ! ! J | J 1 ) | | | 464 Dr. B. Stewart on the Kew Magnetic Curves. [June 10, Nevertheless one notable exception to this rule was mentioned in the above paper, namely, that at the beginning of the great disturbance of August-September 1859, an abrupt fall of the declination curve corre- sponded to a rise of the other two components. It was also shown in this paper that while the horizontal-force peaks are always as nearly as possible double in size of the vertical-force peaks, the proportion between the declination peaks and those of the other components appeared to be variable. Some light was thrown upon this variability in a subsequent paper by Senhor Capello and myself, in which the peaks and hollows at Lisbon and at Kew were compared together (Proc. Roy. Soc. 1864, p. 111). It was found that these phenomena occurred simultaneously at these two observatories ; and it was stated that, as far as Kew is concerned, the pro- portion of the declination peaks and hollows to those of the horizontal and vertical force presents the appearance of a daily range, being great at the early morning hours and small in those of the afternoon. Thus the type of small and abrupt changes, judging from the behaviour of the declination, seemed to vary from two causes, being in the first place subject to a diurnal variation, and in the second place appearing to vary with the disturbance, inasmuch as that for the great disturbance August— September 1859 was, as above stated, entirely different from the usual type. This complexity seems puzzling ; but the results of a preliminary com- parison between the Stonyhurst and Kew declination magnetographs (Sidgreaves and Stewart, Proc. Roy. Soc. 1869, p. 236) appear to throw some light upon its cause. It was there stated that when the declination- curves of Stonyhurst and Kew are compared together during rather slow disturbances, the scales are such that the traces seem exactly to coincide even to their most minute features; but, on the other hand, when the disturbance is abrupt, there is an excess of Stonyhurst over Kew, which appears to vary with the abruptness of the disturbance, being great when this is great. In fine, there appears to be superimposed upon a disturb- ance, which is mainly cosmical, a comparatively small effect, which appears to be of a more local nature, and may perhaps be caused by earth-currents. This circumstance renders it prudent, in discussing the laws of the small and abrupt changes of force (peaks and hollows) at Kew, to avoid all great and excessively abrupt disturbances, confining ourselves to those cases in which there is only a moderate abruptness. The result obtained for the great disturbance August-September 1859 may therefore be dismissed as probably effected by this local cause, inasmuch as the disturbance measured was very abrupt. The question then arises—Rejecting very great and abrupt disturbances, has the peak-and-hollow force only a regular diurnal variation, or is it subject besides to other changes of type? Mr. Whipple, magnetical assistant at Kew, has carefully selected and measured all the similar peaks and hollows for the first two years of the Kew curves; and the result exhibits a manifest diurnal variation in the type of the peak-and-hollow force. 1869. | Dr. B. Stewart on the Kew Magnetic Curves. 465 In the following Table we have these various measurements ranged in order of date, the unit of the scale adopted being 54,5 of an inch. Tas_e I. Measurements of the Peaks and Hollows in the Kew Magnetograph Curves. . | Hori-| Ver- | j;_| Hori- | Ver- Date. | Time. peed zontal| tical || Date. Time. ee zontal | tical | “| force. force. | are! force. | force. ass. | hh m || 1858. h m Mag 22.| 15 15 |. 30 21 To. ||) Dee. 13. 2E 10 24 16 8 pecs 30 | ..35' |. 15 i jaa | 16, [7 45 39 18 10 ee 15° P AN 28 16 | 16. 23a EF 13 9 June 3.| 16 10 | 22 9 5 £7: 15 2 55 45 20 BIL EP 2S | 45 19 II 18. 200816 64 58 25 Ae EG ES |. 42 2.3 11 oY 19 18 2g 14 6 Aa) EO, 1G. | . 24 II 6 1859. ey Ge) rs r7 | 23 II 5. || dan. 8. 23 45 42 32 14 Za tS £0 | 20 I Gr 10. CAST XG) 103 $2 32 Say 27° 1O.|,- 35 19 6 aye I5 40 19 9 4 See Hehe |. Be 51 25 7 2 Ae 23 15 7 gO.| 17 55 20 13 Tine | 18. 2200s 36 22, 12 BSN Ba. | 57 23 Tae | 19. 18 20 17 rig 5 Fee} 2. ¥G 14. ri Ree 19. 20 10 47 34. 12 Re A oa: | 15 18 Hew 29. 14 55 23 14 7 rg.) £7 30 24. Ly Sr | 30. I4 10 9 a 4 Ee ks, 42 | > 19 12 | 30. 21 48 25 17 9 Bpapite SA |- 14. 18 9 || Feb. 1. 20 50 54 36 14. 24.| 18 14 | I9 II Bae tty TO. 2 27 55 41 19 26.) 4 16 25 Bier | 10. 15 50 20 13 v4 2 20 26-| 33 23 1Oy. | 14. 13- © a2 as 7 Sept. 2.; 18 0 | 20 10 aaa | 15. 23 30 21 15 7 ¥I,| 162 TI 7 ane. 16. 19 45 18 II 5 Ee oe. Ay 16 12 4 | 21. 2 50 27, 4.0 17 2a TO: 56 3 19 6 | Poe 14 50 35 41 17 23s| TE 55 9 15 | op 16 Io 82 55 24. ge FS 56 | 10 18 6 |\March 2. 21 30 25 16 7 29295 TO. |) 40 39 2G Oe 21 40 21 15 5 26.| © 30 | 19 18 Loe | 9. 18 40 27 14 8 Bee) 490 | - 32 38 23 Io. 20 40 42 22 se) 2aeh ig 35 |. 21 13 4 10. 22 NO 25 21 10 29-20, 10 | ° 16 EE 6 Eis © 55 18 18 3 Oe, 25) 18" 10°]. ©5 9 5 a 1236 17 18 8 8.| 20 20 | 28 22 Io Ted, 16 50 63 4.0 17 oe t. 22 | - Da 14 5 bis 18 30 19 fe) 4 ee} 3.48 IO 15 4 ae 22 10 21 13 6 18.| 23 52 | 108 70 31 ues 13 45 18 9 4 Pe Lo. 27.227 17 G 16. 17 50 15 fe) 5 245) 18.56 | 28 16 Gi) 16. 20 50 54. 42 18 27.| 22 40/ 43 | 49 | 19 16.| 22 35 93 83 | 40 27-| 23 7) 44 38 27 17 20 30 45 28 13 28.| 19 20 12 5 5 22 5 30 II 12 7 292 tA (CO 1.28 32 15 2.6 Ig 30 28 20 10 Woy. 2-| 12 50 |. 20 31 Io al 23 40 18 nie 6 P22 50.-\-. 26 18 a) 29 20. 10 61 38 22 12 Si) 20h 43 47 19 30 20 59 38 18 Fe, | 2 17 30 20 7 I 19 30 IOI 53 26 235) 128 |. 32 5) 124) | April 6 18 55 25 16 8 2#a| © 50 |, 20 19 It 7, 288A) 23 ag 8 4.66 Dr. B. Stewart on the Kew Magnetic Curves. [June 10, Tas _e I. (continued). rT | | . | Hori-| Ver- | | - | Hori-| Ver- | Date Pane ee ‘zontal | tical Date. | Times |e eee eal nation. f ¢ nation. f f | orce. | force. || orce. | force. | 1859. hm 1860. |- hm | April ii. | 17-55 36 26 11 || Jan. do.1022) es 17 9 12). | S16! 20 13 9 4 16.| 17 50:|, 34 13 9 I2.| 16 50 12 13 4 20.1 20 45 fo 2m 18 9 12 18 50 29 17 7 Zi. | 20 35 50 29 14 | 13 17 30 22, 16 S| 20.423 8G on 16 7 13 18 Io 42 20 10 27. \ lS Ot er 9 | 13 20 30 34. 21 10 28.| 15 20 13 5 2 13 22 45 25 22 TZ 23:4) 240 21 ste) 5 12-3) 23625 22 21 TOG 29:20 Bie es 22 9 if! 1g) 5O 14 13 7 || Feb.12.| 15 55 12 8 4 14.| 17 40 22 15 hae || 14.12% Topless 21 9 14.| 18 5 34. 15 pl 16.| IP Zou gag 23 12 15 17) 25 20 14. 5a 16. | 16-10 | 92 II 5 16.; 18 50 25 12 & Mar. 5. | 8*25¢4) e2y 13 5 17; BESO) 35 49 27 7. | a5 tos eee, a7 19 20 8 Oo 3 II 5 7.1 59 30 50 22 II 20. |= (201-33 22 II 6 8.| 21 5 36 oy 9 May 4.| 19 © 24. 15 7 9x. 3°50: 2 aR 15 8 5. Tol 25 24. 13 5 9.| E9* 24s 65 32 fe) 6 17) 55 5 / al 4 12, | 20" 10 /eiz9 59 27 3 17 30 43 23 Io |i 12. | 27-30 | mgm 23 II 9. |k 161.20 27 19 6 145} 28" Shee 64. 29 Aug. 4.| 17 15 13 7 3 14. | 19) YS ee 19 10 7 I 35 14 24 12 14./ 21 45 | 28 23 9 9 16 30 19 13 5 15..|:-4p 40) ya 34 13 fe) 2 50 13 18 10 I9.| 18 40 35 19 9 fe) 7 45 49 39 24 Ig. | 19° oO) 956 26 13 22 17 58 20 ae 20.] E208 eae 16 8 Sept. 15.| 18 ro 27 i 5 26. | Omri 17 20 10 | i Sethe ade (fly 25 20 Sea 22.) 19 45 19 10 5 17. | 23; Lo 15 16 gi 22:, | 2E TO 39 29 13 26 4 10 44 56 37_ ‘|| April 2.) 0 55) 21 21 fe) 30 18 55 31 21 oe 24°) 2aAs 15 17 7 Oct. 1 © 10 21 25 re | 2.4 Gag OniaenG 21 10 2 Ova 59 34. 17 21 Aas 15 22 II 21 18 50 38 23 ee ty 4.'| TS: tS) eee 17 INoOVv. 2. | 13 36 23 12 6 || Iz.| 17-40 | ° 27 13 (6) 6 4 20 II 14 7h 1t.4 20°4:54 25 (4) GH AQE ss 21 9 5 El.) 23°10 4g 35 (47) 12 3 58 29 23 14 || 17.) 3°95) 1 ss 20 9 16 17 40 27 15 7 || 19. | 22° 5) |e 2e 9 4 17 15 20 24. 23 10 NOV) ONE 32 33 18 17.\, 16 50 21 itis g 21.) 16 40 15 fo) 5 Dee. 4.| 20 56 33 18 7 29. 14 5 | 19 | 21 TO 4. |" 2120 30 21 ao 2.9: | 20! ZO. 1a eee 19 5 20 10 38 18 8 30.1 0759 30 20 fe) 6 PONS 17 19 30:|. 230) |) eae 16 8 ON heute 63 41 Le 20. | 23210; | a iae ees 43 1o.| 18 10 97 55 28 May. 124295} mea 18 9 15. |. 22010 37 By Phe 1.1 47° 50) ag 4 2. _ | 1860. pla lig WTS) 3 17 ie ') Jan. 5.| 20 40 21 15 Teall 4.| 15 10} 19 10 5 HO.) 1-19) O 30 2.0 es 27-\ 10> 5) ee 12 | 5 In the following Table each disturbance is entered under its appro- priate hour. EAKS AND 19 21 10 Tante IL—HOURLY RATIOS OF PEAKS AND HOLLOWS. ~ Frrsr Year, 1858-59. 0-1. 34. 4-5. 5-6, 6-7. 7-8. 8-9. 9-10. 10-11. 11-12. 12-18. || Te-14 | 14=15. 15-16. 16-17. 17-18. 18-19, ee D. HF. VF. | D. HF. VE. | D. HF. VF, | D. HF. vp.| D. uF. vF.| D. HF. VE.| D. uF. VF.| D. HP. vr. |, D. UF, vF.| D. HF. vF.| D. ne. yr.| D. HIF. YF. D. HF. VF.| D. MP. VR, 19 18 10 32 38 23 | 15 18 10 Ke 8411 5| S11 5 819 6! 915 7| 14 18 9] 52 51 25 | 28 32 35 FS RO RN RST eS a7 20 19 II DOTS 4a, Sons me 3 Sor 5 sesseeeee | 1018 61] 28 3215 | 23 14 7 35 19 6) 23 mr 5 1818 8 43° 47 19 20 3110/1413 7| 9 7 4 20) 18) S7i|| 39 aes 20 23 10 : Soren cen PED Oey, 24°17 8) 19 WE 5 2 Seay: @o I0 5] a0 10 § 39 18 10) 15 9 5 34 ar 7a 28 x6. os EO AG) Gah ea) EL G 36. AG) -Xt)] yaar a2 16 8] 27 m4 8 2A TS! Sg AG) XG) 4: 20 14 5] 1 g « Ge EE Gy 43 23 10| 29 17 7 - rc) 42 20 Io | 3415 (7 25) stars | 24°15 7 | one ae i Pee a | al ee |b ee] ewes See ees eee S| — 77 78 39 | 79 84 36 | 158 364 82 | 85 100 46 | 15 18 10) rx 12 7 811 5] 81x 5 819 6] 915 7 | 44 67 25 | 94 96 47 | 95 94 43 | 144 101 47 | 345 216 96 | 390 228 104 | 45x 246 111 | 440 28x 126 | 662 466 206 | 160 1x1 47 | 250 211 104 | 471 286 144 Sxconp Year, 1859-60. O41 1-2 2-3 34 45, 6, 6-7. 7-8. 8-9. 910. | 10-11. | 11-12, | 1243, | 1834 | 14-15, 15-16. 16-17. 17-18. 18-19, 19-20. 20-21. 21-22, 22-93, 28-0. or D UF VP D. HR. VF. De uP. VF. D. HE VF. D I Ve. D TE. VR 35° 19 9) 19) XO, 5) 5. 1) (4) 2B) ag 56 26 13] 39 29 13] 41 38 I9 | x11 98 43 ay § Be 1B S| sasncuves see . . VE. | D. uF. VF. | D. UP. YF. | D. UF. ve.| D. HF. W.| D. MIF. VE. D. WE. VE. D. WF. YF. D. me VF.| D. HF. VF. | D. re yr. | D. HF. VP. | D, MF. YF. a ae i D. HE. VF. | D. HE. VE. | D. HF. VF. a a we i : Pax 1307. | a7 ae gil de) ag sil ga ras) cilia ao alot lay aay aa cmc 21 25 11 13 18 Io | 29 23 4 44 56 37 ; 817 4 £3; 20 8 4| 3m ar rr] 9o 20 g| 38 18 8 gO 2x 10 ar 16 7 21 21 10 17 19 9| 13 15 WUTC Ty Er 27 1§ 7| 38 23 ge PY eo bale Cleo hw) ila Meo qolen Uy 29 35 (17) 40 20 10 17 20 10| 16 21 10 | 15 22 11 63 41 20] 23 12 6 9 32 10} 24 18 gg} gr 22 g ase one spesenees 34 18 9| 97 55 28] 41 19 10} 50 29 14] 3r 21 9 21 9 4! 25 13° 5| 7X 34 13] 129 59 27] 36 17 9 17 13 (6) 112 64 29] 56 26 13] 39 29 13] 34 23 11 2 9 72 66 31 U3 IRD GP 7° 9% 55 49 39 24 19 21 10 466 261 122 | 418 213 94 so 25318 | 357 255 ne | 1869. ] Dr. B. Stewart on the Kew Magnetic Curves. 467 It will be seen from this Table that there is great constancy in the type of the peak-and-hollow force for the same hour. Bearing in mind the — difficulty of finding exactly similar appearances denoting an unmixed force, and remembering also the small size of many of the peaks and hollows observed, it is not too much to say that, as far as these two years’ obser- vations are concerned, there is no trace of anything else than a diurnal change in the type of the peak-and-hollow force. But this question can- not be finally decided until more observations are discussed. In the following Table the final results of Table II. are brought before the eye in a condensed form. TaBLe IIi. Hourly Ratios and Frequency of the Peaks and Hollows, the vertical force being taken as unity. } | Declination, Horizontal force. HLGUIDG OD a y GLUES. Number Hour. Pah E of obser-' 7 z : aan Declina- | Horizon-| yations, | 1858-59. | 1859-60.| 1858—59.| 1859-60.) tion. |tal force. o-I 1°97 2°32 2°00 2503 2°14 2°06 aaa 2 2°19 1°76 539 2°00 1°97 2°16 gp 2-3 I'92 Tor 2°00 1°98 1°86 1°99 os oa 3-4 1°84 1°78 2207 1°93 1°81 2°05 ves 4-5 I°50 1°27 1°80 1°67 1°38 173 Bow yl 5-6 oe ieee 1°71 7 7-8 1°60 2°04 2°20 1°62 | 8-9 Ga Sees 2°20 g-I0 10-II ME Ob csceide’s apnG | 11-12 1°29 1°31 2°14 2°50 | | 12-13 oy 3 aan a 2°68 | gst): 6 7-Cole aan ae | 2°04 | 14-15 ae I'90 2°18 2°10 2°10 PEA: 5 | 15-16 3°06 3G Ms phe 2°07 2°65 PTE | TOF pe EHP’ 9 3°59 ap 2°25 2°07 3°48 2°16 HS) oe pmo) [3°75 3°85 2°19 2°09 3°80 2°14 22 | 18-19 4°06 3°82 2°22, 2°14 3°94 2°18 28 19-20 3°49 4°45 2°23 2°27 3°97 2725 21 20-21 g°25 3°61 2°26 2°16 3°41 2.2% ZG al 21-22 3°40 2°03 2°36 2°24. 3°26 2°30 LO ss 22-23 2°40 3°19 2°03 1°96 2°79 2°00 LOM 23-0 2°58 2°03 1°99 ZIG 2°30 2°04 13 | From this Table it will be seen that, as was formerly stated, the ratio between simultaneous peaks and hollows of the two components of the force is very nearly constant, the horizontal force disturbance bemg very nearly double of that of the vertical force. It will also be seen that there is a very marked diurnal range in the ratio which the declination peak or hollow bears to that of the vertical force, this ratio being greatest about 7 a.m. About this hour we have also most peaks and hollows, while in the evening and very early morning VOL. XVII. 2M 468 Sir W. Thomson on a New Astronomical Clock. [June 10, hours there is a comparative absence of these phenomena. So much is this the case that for the two years investigated I have not succeeded in finding a single example of a peak or hollow, suitable for this research, between the hours of 6 and 7 p.m., or between those of 9 and 10 p.m. I forbear to make further remarks on this subject, but hope in a short time to extend the investigation up to the present date, and to bring the results before this Society. VI. “ On a new Astronomical Clock, and a Pendulum Governor for Uniform Motion.” By Sir Witu1am THomson, LL.D., F.R.S. Received June 10, 1869. It seems strange that the dead-beat escapement should still hold its place in the astronomical clock, when its geometrical transformation, the cylinder escapement of the same inventor, Graham, only survives in Geneva watches of the cheaper class. For better portable time-keepers, it has been altered (through the rack-and-pinion movement) into the detached lever, which has proved much more accurate. If it is possible to make astronomical clocks go better than at present by merely giving them a better escapement, it is quite certain that one on the same principle as the detached lever, or as the ship-chronometer escapement, would improve their time-keeping. But the inaccuracies hitherto tolerated in astronomical clocks may be due more to the faultiness of the mercury compensation pendulum, and of the mode in which it is hung, and of the instability of the supporting clock-case or framework, than to imperfection of the escapement and the greatness of the arc of vibration which it requires ; therefore it would be wrong to expect confidently much improvement in the time-keeping merely from improvement of the escapement. I have therefore endea- voured to improve both the compensation for change of temperature in the pendulum, and the mode of its support, in a clock which I have recently made with an escapement on a new principle, in which the simplicity of the dead-beat escapement of Graham is retained, while its great defect, the stopping of the whole train of wheels by pressure of a tooth upon a surface moving with the pendulum, is remedied. Imagine the escapement-wheel of a common dead-beat clock to be mounted on a collar fitting easily upon a shaft, instead of being rigidly attached to it. Let friction be properly applied between the shaft and the collar, so that the wheel shall be carried round by the shaft unless resisted - by a force exceeding some small definite amount, and let a governor giving uniform motion be applied to the train of wheel-work connected with this shaft, and so adjusted that, when the escapement-wheel is unresisted, it will move faster by a small percentage than it ought to move when the clock is keeping time properly. Now let the escapement-wheel, thus mounted and carried round, act upon the escapement, just as it does in the ordinary clock. It will keep the pendulum vibrating, and will, just as in the ordinary 1869.] Sir W. Thomson on a New Astronomical Clock. 469 clock, be held back every time it touches the escapement during the interval. required to set it right again from having gone too fast during the preceding interval of motion. But in the ordinary clock the interval of rest is con- siderable, generally greater than the interval of motion. In the new clock it is equal to a small fraction of the interval of motion: =4, in the clock as now working, but to be reduced probably to something much smaller yet. The simplest appliance to count the turns of this escapement-wheel (a worm, for instance, working upon a wheel with thirty teeth, carrying a hand round, which will correspond to the seconds’ hand of the clock) com- pletes the instrument; for minute and hour-hands are a superfluity in an astronomical clock. In various trials which I have made since the year 1865, when this plan of escapement first occurred to me, I have used several different forms, all answering to the preceding description, although differing widely in their geometrical and mechanical characters. In all of them the escapement- wheel is reduced to a single tooth or arm, to diminish as much as possible the moment of inertia of the mass stopped by the pendulum. This arm revolves in the period of the pendulum (two seconds for a one second’s pendulum), or some multiple of it. Thus the pendulum may execute one or more complete periods of vibration without being touched by the escapement. I look forward to carrying the principle of the governed motion for the escapement-shaft much further than hitherto, and adjusting it to gain only about ;4, per cent. on the pendulum; and then I shall probably arrange that each pallet of the escapement be touched only once a minute (and the counter may be dispensed with). The only other point of detail which I need mention at present is that the pallets have been, in all my trials, attached to the bottom of the pendulum, projecting below it, in order that satisfactory action with a very small arc of vibration (not more on each side than ;4,; of the radius, or 1 centimetre for the seconds’ pendulum) may be secured. My trials were rendered practically abortive from 1865 until a few months ago by the difficulty of obtaining a satisfactory governor for the uniform motion of the escapement-shaft; this difficulty is quite overcome in the pendulum governor, which I now proceed to describe. Imagine a pendulum with single-tooth escapement mounted on a collar loose on the escapement-shaft just as described above—the shaft, however, being vertical in this case. A square-threaded screwis cut on the upper quarter of the length of the shaft, this being the part of it on which the collar works, and a pin fixed to the collar projects inwards to the furrow of the screw, so that, if the collar is turned relatively to the shaft, it will be carried along, as the nut of a screw, but with less friction than an ordinary nut. The main escapement-shaft just described is mounted vertically. The lower screw and long nut collar, three-quarters of the length of the escapement-shaft, are surrounded by a tube which, by wheel-work, is carried round about five per 470 Sir W. Thomson on a New Astronomical Clock. [June 10, cent. faster than the central shaft. This outer shaft, by means of friction produced by the pressure of proper springs, carries the nut collar round along with it, except when the escapement-tooth is stopped by either of the pallets attached tothe pendulum. A stiff cross piece (like the head of a T), projecting each way from the top of the tubular shaft, carries, hanging down from it, the governing masses of a centrifugal friction governor. These masses are drawn towards the axis by springs, the inner ends of which are acted on by the nut collar, so that the higher or the lower the latter is in its range, the springs pull the masses inwards with less or more force. A fixed metal ring coaxial with the main shaft holds the governing masses 1n when their centrifugal forces exceed the forces of the springs, and resists the motion by forces of friction increasing approximately in simple proportion to the excess of the speed above that which just balances the forces of the springs. As long as the escapement-tooth is unresisted, the nut collar is carried round with the quicker motion of the outer tubular shaft, and so it screws upwards, diminishing the force of the springs. Once every semiperiod of the pendulum it is held back by either pallet, and the nut collar screws down as much as it rose during the preceding interval of freedom when the action is regular; and the central or main escapement-shaft turns in the same period as the tooth, being the period of the pendulum. If through increase or diminution of the driving-power, or diminution or increase of the coefficient of friction between the govern- ing masses and the ring on which they press, the shaft tends to turn faster or slower, the nut collar works its way down or up the screw, until the governor is again regulated, and gives the same speed in the altered circum- stances. It is easy to arrange that a large amount of regulating power shall be implied in a single turn of the nut collar relatively to the central shaft, and yet that the periodic application and removal of about =; of this amount in the half period of the pendulum shali cause but a very small periodic variation in the speed. The latter important condition is secured by the great moment of inertia of the governing masses themselves round the main shaft. I hope, after a few months’ trial, to be able to present a satisfactory report of the performance of the clock now completed accord- ing to the principles explained above. As many of the details of execution may become modified after practical trial, it is unnecessary that I should describe them minutely at present. Its general appearance, and the arrange- ment of its characteristic parts, may be understood from the pibtopraph now laid before the Society. Vil. ‘On the Effect of Changes ef Temperature on the Specitic Inductive Capacity of Dielectrics.” By Sir W. THomson, LL.D., ERS. | [The publication of the text of this paper is postponed. ] vULY 12, 1870, i ae CONTENTS— (continued). PAGE II. On the Molar Teeth, lower Jaw, of Macrauchenia patachonica, Ow. By Professor OWEN, F.R.S. . . . . 454 III, Researches into the Chemical Constitution of the Opes ‘Gnaad Part in On the Action of Hydrochloric Acid on Morphia. By Aveusrus MarruiessEn, F.R.S., Lecturer on Chemistry in St. Bartholomew’s Hos- pL OR A Ween BS ae 3.2 2 0 EM Uieee ee ee a ee IV. Researches into the Constitution of the Onin Bised Part II.—On the Action of Hydrochloric Acid on Codeia. By Aueustus MAtrHtessEn, F.R.S., Lecturer on Chemistry in St. Bartholomew’s Hospital, and C. R. AC AVuiGut, B.Se.. - - 460 VY. A Preliminary Investigation into the tout vopilation the Paks ea Hollings ; as exhibited in the Kew Magnetic Curves for the first two years of their production. By Baurour Stewart, LL.D., F.B.S., Pipe ee of the - Kew Observatory . . . 462 VI. On a new Astronomical Glock: aa a Patan Goierake for Uniform Ma. tion. By Sir Wint1am Tuomson, LL.D.,F.RS. . . . .. =. . » 468 ERRATA.TO Vou. XVII. Page 127, line 20, for retirmg read returning. ,, 210, lines 18 and 14 from bottom, for Coron read Carn. », 845, line 8 from bottom, for —157’156 read +157”-156. TAYLOR AND FRAN CIS, RED LION COURT, FLEET STREET. PROCEEDINGS OF Per ROYAL SOCEETY. VOL. XVII. I. III. A ge oF Wk: VII. VIII. IX. II. bys logical Reporter to the Government of Bengal No. 113. as Pt A \ CONTENTS. 1? i . oS = - en S: i June 17, 1869. PAGE Note on Professor Sylvester’s representation of the Motion of a free rigid Body by that of a material Ellipsoid rolling on a rough Plane. By the Rey. N. M. Ferrers, Feliow and Tutor of Caius College, Cambridge On the Origin of a Cyclone. By Henry F. Buanrorp, F.G.S., Meteoro- Note upon a Self-registering Thermometer adapted to Deep-sea Soundings. By W. A. Mitten, M.D., Treas. and V.P.R.S. Magnetic Survey of the West of France. By the Rev. STEPHEN J. PERRY, F.R.A.S., F.M.S. foks A cog ERO yak ssc ae a An Account of Experiments made at the Kew Observatory for deter- ‘mining the true Vaeuum- and Temperature-Corrections to Pendulum Observations. By Batrovr Stewart, F.R.S., and Benzamin Lorwy, F.R.AS. . Additional Observations on 5 saat oy Tuomas GRAHAM, F.R.S., Master of the Mint ef, SREBALAY Spibsd pat ake’ Spectroscopie Observations of the Sun (continued). By Lieut. J. Hzr- SCHEL, in a Letter addressed to W. Hueetns, F.R.S. . SBOE On Jargonium, a new Elementary Substance associated with Zirconium. By H. C. Sorsy, F.R.S. &e. Solar Radiation. By J. Park Harrison, M.A. . Index . . 471 . 472 . 482 . 486 . 488 . 500 . 506 [ See last page of Wrapper. ok te pile of tet a sitith A bat nai mje sonladin pial Pie, multe? a Pr eEae att We abe ah again ay rote ie tase e able ie tik mci Loniyy.. yt SLORY % aided Jo ant Moen HG bo AED Leib: A ¥ e BE eae E | coe EN ie . nla ¢ a i dai ani ‘, Ht Z aH As eae AAT eli set >is AE sais ase id elt, $e tad oe et | 1869. ] On the Motion of a free rigid Body. 471 June 17, 1869. Lieut.-General SABINE, President, in the Chair. Mr. J. Ball, Mr. J. N. Lockyer, and Vice-Admiral Sir Spencer Robinson were admitted into the Society. The following communications were read :— I. “Note on Professor Sylvester’s representation of the Motion of a free rigid Body by that of a material Ellipsoid rolling on a rough Plane.” By the Rev. N. M. Ferrers, Fellow and Tutor of Caius College, Cambridge. Communicated by Professor J. J. SyLvEesteR. Received May 29, 1869. (Abstract.) This paper is intended as a sequel to Professor Sylvester’s paper above mentioned, which was published in the Philosophical Transactions for 1866. The notation, so far it differs from Professor Sylvester’s, is as follows :— p is the distance from the centre of the ellipsoid to the rough plane. \ the (constant) component angular velocity of the ellipsoid about the diameter normal to the rough plane. p the component angular velocity of the ellipsoid about the diameter parallel to the projection of the instan- taneous axis on the rough plane. hy, h, ‘are the component angular momenta about these diameters respec- tively. h; about the diameter at right angles to both. n the angular velocity, in space, of the plane through the instantaneous axis perpendicular to the rough plane, Then the mass of the ellipsoid being taken, as in Professor Sylvester’s paper, to be unity, it is proved that h=(7 48? +c?—p)r\ — ~ ye. The following theorem is then established :—‘‘The component angular momentum of the ellipsoid about any diameter parallel to the rough plane is equal to p, multiplied into the component velocity of the point of contact of the ellipsoid and rough plane, in the direction at right angles to this diameter.” It hence follows that whence it is proved that VOL. XVII, 2Nn 472 Mr. H. F. Blanford on the Origin of a Cyclone. [June 17, and that ‘ 1 d’p P= eeu n*) o(- dé? These results are then reduced into the following form :— rv’ r Pap | — 248+ (1—By—y2—aB)X*4 apy §s — ay? XY, 2 2\14 ie a {—(W+ Byrd)? + yar’)? aBr)}, 2 2 where a, 3, y are written for 1 — is es ae _— ee respectively. & Pp In the last clause of the paper it is pointed out that Poinsot’s “rolling and sliding cone”’ is a particular case of Professor Sylvester’s ‘correlated and contrarelated bodies.” II. “On the Origin of a Cyclone.” By Henry F. Buanrorp, F.G.S., Meteorological Reporter to the Government of Bengal. Communicated by Dr. T. Toomson. Received May 21, 1869. It has long been an object to the completion of our knowledge of vor- tical storms to trace out their early history, and to show, by the compari- son of a sufficient number of local observations, by what wind-currents the vortex is generated in each storm-region, and by what agency these cur- rents are directed to the spot at which the storm originates. - With this object in view, I endeavoured, immediately after the great Calcutta storm of the Ist of November 1867, to obtain, through the as- sistance of Captain Howe (then officiating as Master Attendant of the Port), the logs of as many ships as possible that had been in the Bay of Bengal or anywhere to the north of the Equator during any part of the last week of October. A similar application was made to the Meteorolo- vical Department of the Board-of Trade and readily granted. The me- teorological stations recently established in Bengal, and the observatories of Calcutta and Madras, contributed a number of observations, for the most part fairly trustworthy ; and I was thus placed in possession of data which, although far from sufficient to the complete solution of the pro- blem for the storm in question, have at least enabled me to elucidate its origin to a greater extent than has been accomplished, as far as I am aware, for any previous storm in these seas or elsewhere. The following Tables give the noon barometric pressures at several sta- tions in Bengal * and on the shores of the bay, and those of a few ships * These are calculated from the observations at 10 a.m. and 4 p.m., but so regular is 1869.] 473 from the 23rd to the 27th of October ; also the temperatures and humidi- ties of the atmosphere at land stations at the hours of observation, and the prevalent wind-directions for the same period. The barometric read- ings are throughout the paper reduced for temperature and sea-level, and, — with one exception* (noticed below), the instruments have been compared and corrected to the Calcutta standard. Mr. H. F. Blanford on the Origin of a Cyclone. Noon Barometric pressures. 23rd. 24th. 25th. 26th. 27th. Uo a 29°912 in. hs 30°014in.| 29°939 in.| 29°926 in. CANCAE asses iccsssce0es "913 29°967 in.| 29°983 940 "965 1277 ee 963 "999 =| 30°005 943 "965 Chittagong............ 965 972 008 °932 953 False Point’ 2... ..3:: 901 "940 =| 29-939 908 928 1 er ere 910 "933 "939 “900 901 BPMGRAS 1 <.5054....00. 897 "926 949 "993 930 lat. } ‘PrinceArthur,’ ssf S.S. long. Between Calcutta and Port Blair.| Port Blair. bar. lag. LSS34'N. |1¥° 50’ N. 118° 36’ N.|19° 67 Ne |20° 107N. ‘Winchester’ | long. 89° 43’ E. |89° 14' E.|89° 8' E.|88° 46’ E. ? bar. 29°894 in. |29°834 in. |29°966 in. |29-931 in. |29°972 in. lat. 8° 12'N. 9° 53’ Ne j12° 17’ N.|14° 3° N, (14° 477-N. ‘St. Marnock’ | long. 88° 54’ E. |88° 49’ E. |88° 55’ E. |88° 31’ E. [88° 36’ E. bar. 29°833 in. |29°901 in. |29°903 in. |29°936 in. |29°896 in. lat. 5° ag! Nei 7°44" Ne! 8°.20' N. 110° 16’ N. [LLo 22N. ‘3. G. Botte? long. 91° 20’ E. |91° 30’ E. 92° E. 91° 24’ K. 91° 38’ E. bar.f 29°770 in. |29°772 in. |29°777 in. |29°740 in. |29°750 in. lat. Galle. 6° 27'N.|10° 21'N. |Madras. {15° 43’N. ‘Mongolia,’ S.S. } one harbour. [81° 25’ E./81° 32’ E. |Roads. 82° 51’ EK. bar. 29°928 in. |29°904 in. |29°946 in. |29°918 in. |29°986 in. Helis: sossuss ves 1s 2° 14'S. | 0° 29'S. | 3° 44'N.| 7° 5’N. ‘Gauntlet’......... Fonsi eh td 89° 47'E. ? 92° 25' B: 92° 6 E. | ane aeecghe ss 29°804 in. |29°828 in. |29°707 in. |29°562 in. Mab a ieeas sencecceasit |< Ssaas8 AS SES: |» 2° 5918) 10% 88. ‘Astracan’ ...... | IOGE catccboescssst esos. 89° 27' EK. |89° 24'E. {89° 56’ E. Dale. ed-beskeeoccsd | seasss 29°886 in. |29°816 in. |29°786 in. Nahe P cptxtectuecseecl atstwe) “| 2) eSece _ OSs. 14° BV S: ‘Tron King’ ...... { NOG SR ca vsec eased: danas er ht. sbeae 87° 4° BE. |87° 30’ E. Ridle caveseceticgstei pil ssmeseis: |) So! Gusts 29°834 in. |29°842 in. the march of the barometer that they may safely be accepted as within °02 of the truth. * The Madras barometer should be included in this remark, but being an excellent standard instrument, it may fairly be assumed that its difference, if any, is insignificant. + The barometer of this ship has not been compared with the standard, but from a comparison ofits reading at a later date, at the Sandheads, with that of Saugor Island, it may be inferred that its error is small, not exceeding °05 inch, and probably less, For the purpose of comparison, I have added -04 to the reported readings, ow 2 A7 4 Mr. H. F. Blanford on the Origin of a Cyclone. [June 17, Observed Temperatures. 23rd. 24th. 25ths 26th. 27th. 110.) 42, | 104) 44, | 102.) 4h, | 108, 4h, | 10h,) 42. | ° ° fo) fo) fo) fo) | ro) fe) ° ° Patna ches sek aol ..| 80 | 85 | 80 | 83 | $4 | 90 | 84 | 87 | 81 | 86 Calcutta se oe. 85 | 87 | 83 | 85 | 83 | 80 | 82 | 84 | 81 | 85 IDACCa eee Paes 81 |.86.| 83 |.83°|-82.4. 33") 82 S267 SE Chittagong... isssecars 84 | 82 | 83 | 85 | 83 | 86 | 83 | 85 | 81 | 84 False Point.........000-+- 85 | 85 | 85 | 85 | 85 | 86 | 84 | 84 | 84 | 84 Mey GaE sine seo cute ce hevecr 83 | 87 | 84 | 87 | 84 | 87 | 83 | 86 | 83 | 85 Madras <2..6: nee peneed 84 | 85 | 86 | 84 | 84 | 84/ 83 | 83 | 83 | 84 Humidities. Saturation = 100. 23rd. 24th. 25th. 26th. 27th. 10%.| 4», 10®,| 4h, / 10%) 45.) 108} 48, | 108.) 4h Ratna es 2cert Bice eieen: 78 | 68 | 70 | 63 | 67 | 50 | 54 | 42 | 55 | 35 Calcutta siscccss ce “7140 |78|77 | 85 | 861 80 | 67 | 68 | 64 DacGa tt: cc tee. sooeeenes 91/911] 87 {87191 | 87; 911 91 | 86 | 91 Chittagong............0.. 93 | 85 | 83 | 89 | 86 | 85 | 86.| 83 | 84 | 87 False Point... ...<0.+0s+0- 79 | 75179179 | 79 | 79 | 79 | 75 | 71 | 64 Akyab ..... dedeae a Sanae 87 | 79 | 79 | 76.1 87 1-92 | 83.) Goueee ae Madras ........ REET eee 7171) 92) 91 | 754 Fa ee ee [See Table, Prevalent Winds, p. 475. | A comparison of the above data* shows as follows :— On the 23rd of October the barometric pressure was about 0-005 higher at Chittagong and Dacca than elsewhere around or on the bay. From Calcutta to Galle, at Akyab over the northern and down the western part of the bay, it was nearly uniform, being slightly lower at Madras ; but to the west of Acheen and the Nicobars it was from 0°15 to 0:2 inch lower than around the coasts of India and Arakan. In Bengal and down the west coast of the bay the winds were light from between S. and E., and the same was the case over the bay down to the latitude of the Nicobars. Tn lat. 4° to 6° 30’ N., in the region of barometric depression, the ‘J. C. Botelbhoe’ experienced rain and cloudy weather, with a moderate breeze from W.N.W. during the latter part of the day, and the ‘St. Marnock’ about 2° further north had similar weather and a heavy sea from W.S.W., but the breeze was light from E. and S.E. It appears from the log of the last-named vessel, and that of the ‘ Léonie’+, that from the Equator up to lat. 5°, W.N.W. winds with rain and squally weather had prevailed for many days previously (at least, from the 11th of October); and this current, * Some additional data are given from ships’ logs, &c. T Of which I have received only a cursory abstract. 475, Mr. H. F. Blanford on the Origin of a Cyclone. 1869.] “AA 94'S “WH OE oL8 S ,TE of “ANS AL “H 19S 068 ’S 8 00 “M “H/9 086 "N iG of “WN “W /1S 028 *"N JEP OST “ANH 9} “AN “Wd 86 o1G "N/T6 OTL “WN “a SZ -68 ‘N/T OL. * ‘ON OF-D'N' 196 088 ‘N LF oP ‘O'N'N é "NOT 002 “U'S 93 ONE “TCT, FAO “dH 02 °O'N “UNON BN *A[IIYINOY “A'N ANN "M 97 ‘'N “M'N 9 'N “MN ‘NB 'M'N "O°NAQ*N 09 "MQ "NON "M9 “AACN ‘HS 93 “HSE ‘TF ol ‘Sol deta "M'N'M 03° ‘SR “a FZ 068 “A LZ 068 "8.169 0% ‘S$ 9S of “MN M “AN AN “78S 086 é "NPP of °S 62 00 “NN “A[IOYILON P "W 128 o18 Speor SCIP NI 1zZ 501 "] 0} “ON. "A'S 07 “AA'N “HA FZ 016 “A 006 "N /OT OL "N 102 08 a LZ 006 BuChe Mole & Bae “09 “ON “ANS 99 ON "JIE 088 "HSS 088 “N AG oVI "NZL ool “NN 93 ‘°N “UN'S "HOF o88 ‘1 18 68 "N19 061 "N 19€ o8T ‘TS'a "A NOM 29 OUN AT “MeL JOT pue eyM9/e9 U990M49 “IBA °K [104seq "AN 0} “a St "ON Aq “of *S9ZIIIG Bas “T'N 03 °AA'N “aA°N 07 °N "M 0} °N “M'S"AA 04 'N ‘T'S WN "N "M'N "N "N B°M'N 'N *M'N'N 8 °N “TNO 07 “ANN "MN 9 OL a | aM geet’ | NY fe @eoeee “44S “MN 9} “M'S'S “SPUTA\ JUO]VAII T pura eoeeee @eeees “SUO] @eeeoe eoaree pura erovee eoeeee *SUO] "ANA 0} “LS eereee pura “HLF 068 pea *BUO] °S iat oG eeoree “MSA “IVA pura “HZ SS O18 “NL 69 “IMOqIeY s[eH “A OE o16 "A 02 016 © “Bo AN Aid ol! °"N ULP 0G ae tee puta seoccee eoeoece *Su0] ner a sc tees pur ecccce eeovee BuO] “a 07 TNO ‘T0}'G'S pura “M iGF 088 “FS 088 "NES 06 "N ZT 8 “TN 99ND “TNA pura "dF 068 “WEF 68 ‘suoy "N06 oLT *N VE OGL eG teh siesta pura oretee osbeee *BUO] “O'S BE “Ws pue pury Iepnsoy “ABA “a's “M 03 °N "NN YDS "Nl “IRA, “M'S'S “M'S’S *N "NB "A'S B'S “ON 9} "MN “H'S 9F°"M'S “a “a “UIFS “PASS “AUN'M 93°S pura fo maine 9-1 a Ceercsence , SUIS uouy , eocseseore , UPIIYSV , Pe age Sy yoTFUNVY) 9 eoevccdcn , Vosuop F WOPOLOCOE LY Saqkaiiokayay, ao 6c0e i yeqs LOOULTT, 9 weteoe OOUILTY 39 , seeeoe TOISOUOUTAA 4 "8 ANYYLY BOUL , UE OODIIOIT GL fa) er ti) seeeedeccoesenroe’ SBINUTH ee ek ecevsessecene’ quay GORE Sheila ya cia KEI secceeceesce Suosepyiwyg Og ULC ECOSUN ahi gy eee eeertsone sroduey.ia g Bk ine ysneqoo.1eze Fy EDC ECOL ELUTAI h 0) (cta at aCe aul AIC 15414: a “ meas 476 Mr. H. F. Blanford on the Origin of a Cyclone. [June 17, “as appears from the accounts furnished by other vessels, eventually contri- buted in a great degree to produce the cyclone, being diverted from its pre- vious direction towards the place of low barometer in the south of the bay *. On the 24th and 25th the barometric pressure increased slightly over the north and west of the bay, but chiefly at Patna. ‘The increase was from 0°04 to 0:07 inch at stations in Lower Bengal, 0-05-at Madras, and 0°03 at Akyab. The difference of pressures at Chittagong and Madras amounted on the latter day to about 0°06 inch, and between Chittagong and Akyab to about 0°05inch. In the region to the west of the Nicobars the pressure seems to have remained much the same as on the 23rd, and was about 0°23 inch less than at Chittagong, and 0°19 less than at Madras. At the same time, in lat. 5°.8., the pressure was about 0-1 inch higher than in the south of the bay. The figures given in the Table thus indi- cate a region of slight but distinct barometric depression running from Sumatra up towards Arakan, with a minimum to the west of the Nicobars, or, more probably, somewhat further to the south. Meanwhile the northerly or north-easterly wind, which was first felt at Chittagong on the afternoon of the 23rd, extended over Lower Bengal _ and down the western half of the bay as far as the northern extremity of Ceylon. It prevailed also over the northern part of the bay from N.E. and E.N.E. as far down as lat. 12°, and was accompanied with fine and clear weather. Below this latitude to the west and north-west of the Ni- cobars the winds were light and variable, with rain and squally weather (‘Léonie,’ ‘J. C. Botelbhoe’). Still further south, on the Equator (‘Gauntlet’), and probably for some degrees to the north, the W.N.W. winds, already noticed, prevailed with squally weather, while the S.E. trade was blowing (‘ Gauntlet,’ ‘Astracan’) up to 2° 30! or 3° south latitude. On the 26th there was a general fall of the barometer, greatest in Bengal, and the pressure became nearly equal over Bengal, down the west coast to Madras and over the bay (‘ Winchester,’ ‘ St. Marnock’”) down to lat. 14°. In the eastern part of the bay, between lats. 14° and 10°, there was a barometric dip of 0°17 inch (‘ St. Marnock,’ ‘J. C. Botelbhoe’), and the barometer stood at about the same height in N. lats. 10° and 4° (« J. _C. Botelbhoe,’ ‘ Gauntlet’). The area of maximum depression lay evi- dently between these latitudes, since in S. lat. 3° the pressure was 0°1 inch and in S. lat. 7° 0°13 inch higher (‘Astracan,’ ‘ Iron King’). The state of the wind and wéather appears to have been much the same as on the previous day ; but there is some evidence in the logs of the ‘J. C. * This W.N.W. current is very prevalent in the winter months, as is well known to mariners. Its prevalence is clearly shown in the Board of Trade charts, and it is especi- ally noticed by Maury (Phys. Geog. of the Sea, 12th edit. p. 375) as the winter or west- erly monsoon of the line. It is usually accompanied by rain and squally weather, and not improbably plays an important part in the production of all the cyclones that origi- nate in the south of the bay to the west of the Andamans and Nicobars. On this point compare the Report on the Calcutta cyclone of 1864, especially pp. 79, 85,105, See ls posted. 1869.] Mr. H, F. Blanford on the Origin of a Cyclone. 477 Botelbhoe,’ ‘Timoor Shah,’ and ‘ Gauntlet’ that the wind was beginning to circulate around the area of greatest depression and of variable winds. The first of these ships, whose course was northward and on the east of. the area in question, had a moderate breeze veering from N.E. to E. with heavy squalls; the second, moving slowly up on the west of the area, had northerly freshening breezes and an overcast sky with rain and a heavy S.W. swell. The ‘Gauntlet,’ at 200 to 250 miles to thesouth, hadthewindat W.N.W, with hard rain-squalls. There is, however, no evidence of the wind having attained to anything like hurricane violence until the following day. On the 27th the barometric pressure remained much the same as on the previous day over the greater part of our area, The barometric difference between Chittagong and Akyab amounted to about 0-05 inch, and to an equal amount between the latter place and Port Blair. At 70 miles to the west of the Andamans the barometer of the ‘J. C. Botelbhoe’ stood 0:1 inch lower ; but the lowest pressure recorded on this day was experienced by the ‘Gauntlet’ in lat. 7° 5' at about 100 miles due west of the Nicobars. ‘The reading of this ship’s barometer was 29°562, or 0°29 less than at Port Blair, and 0°22 less than on the Equator to the south, 0°4 less than at Caleutta and Dacca, and nearly 0°36 less than at Madras. There can be little doubt that to the west of the Nicobars there had beeen a rapid fall during the two previous days. On the morning of the 24th the ‘ Jam- setjee Cursetjee Botelbhoe’ had passed within 40 miles of the ‘ Gauntlet’s’ noon position of the 27th, her barometer standing at 29°772 at noon of the 25th ; when her barometric reading was nearly the same, she was at a distance of little more than a degree to the north, The form of the area of depression would seem to have been a very elongated ellipse, or a trough, stretching from south to north, and of no great width. ‘That the rise was rapid to the eastward, we have evidence in the observations of the ‘Prince Arthur’ and the ‘ Jamsetjee Cursetjee Botelbhoe.’ On the other hand, the barometer of the ‘Comorin,’ at 200 miles to the west of the Little Andaman, showed a reduced reading of not less than 29°9. Itis true that the barometer of this ship has not been compared, and it is not improbable that its readings are somewhat high, but that its error is so great as to produce the whole of the apparent difference of its reading and that of the ‘J. C. Botelbhoe’ barometer is highly improbable. In Bengal the winds were from the N. and N.W. (the usual directions during the cold-weather months), and N.E. down the coast of Orissa and the Carnatic. Over the north of the bay, as on the previous day, the pre- valent directions were N.H. and E.N.E. (‘ Winchester,’ ‘ St. Marnock,’ ‘ Léonie,’ ‘ Mongolia’). But at Akyab the wind was southerly, and at Port Blair veering to 8.E. The W.N.W. winds that had hitherto pre- vailed between the line and 5° or 6° N. lat. were now drawing round to the place of maximum depression, since the ‘ Astracan,’ coming up from the Equator across this belt on the 27th and the following day, experienced strong breezes with hard squalls from W,S.W., the sky overcast with cirro- 478 Mr. H. F. Blanford on the Origin of a Cyclone. [June 17, stratus and scud moving rapidly from the westward. TotheS.E., between Sumatra and the Malacca peninsula, the ‘T. A. Gibb’ encountered cloudy weather with occasional squalls and variable or southerly winds. Her barometer has not been compared with the Calcutta standards*, but, as far as can be judged by a comparison of its reading at the Sandheads with that of the Saugor Island instrument at a later date, the actual barometric pressure on the 27th, in lat. 2° 18’ N., long. 101° 56! E., would seem to be about 29°8, or nearly the same as that recorded by the ‘ Astracan’ on the Equator, 12 degrees to the westward, on the same date. In and around the area of maximum depression a cyclone had already formed. Its centre was probably somewhere between the Andamans and Nicobars, as indicated by the wind-directions of the ‘J. C. Botelbhoe,’ the ‘Timoor Shah’ and ‘ Comorin,’ and the ‘ Gauntlet ;? and that its force was considerable may be inferred from the fact that the ‘ Ferose Shah,’ bound from Carical to Penang, was dismasted on the 27th and driven on a bank near the Little Andaman, known as the South Brother. The four ships above mentioned experienced hard squalls and heavy rain, and the ‘' Timoor Shah ’ describes the wind as blowing a hard gale in the after part of the day. During the five days under notice there appears to have been little change in the prevalent temperatures. A general fall of from 1 to 2 de- grees is the utmost shown by the temperature Table given on a previous page. The decrease in the humidity is more marked at all the land stations, but especially at Patna, owing probably to the increasing prevalence of a northerly or north-westerly wind. It is much to be regretted that, owing to Mr. Barnes’s departure from Ceylon, the valuable meteorological record which that gentleman used to keep, and an extract from which he was able to furnish for the discussion of the storm in 1864, is no longer avail- able ; and I am unable to ascertain whether the humidity of the atmo- sphere in Ceylon was as high as before the cyclone of 1864. The principal facts exhibited in the foregoing description may be summed up as follows :— For at least four days previously to the formation of the cyclone vortex the barometric pressure to westward of the Nicobars and the northern ex- tremity of Sumatra was lower than elsewhere in or around the bay. It was also lower (on the 24th of October certainly, and probably on the previous day also) than on the open sea to the southward. ‘The depres- sion was gradually intensified up to the 27th, when it began to blowa hurricane on the northern limit of this area. It then amounted to —0-4 of the pressure in Bengal, —0°36 of that in Madras, and —0-22 of that on the Equator. It would appear, however, that over the greater part of the bay the pressure was nearly equable, and that the depression was local and bounded by a much higher barometric gradient than would be indicated by the figures above given. Thus the ‘ Gauntlet’ reading was 0°29 less * It was sent to me for comparison, but was injured in the carriage, so that no com- arison could be made, and the tube had to be replaced. 1869.] Mr. H. F. Blanford on the Origin of a Cyclone. 479 than that at Port Blair, equal to a gradient of 1 inch in 1034 miles, while that of the ‘J.C. Botelbhoe’ showed a gradient of 1 inch in 700 miles. Around the north and west coasts of the bay the differences of pressure and its changes were inconsiderable. On the 23rd there was a slightly higher pressure (0°05 in.) in the N.E. corner, which difference remained unaltered on the two following days. In Ceylon also the pressure was 0-03 greater than at Madras; at the same time there was a general rise of the barometer, small in amount, over Bengal and the northern and western coasts. On the 27th there was a general fall, and the pressures were nearly equalized. Coincident with these changes were those of the winds. For many days previously to the 24th * light south-easterly winds prevailed on the west coasts of the bay, while in Bengal the wind was variable, with a predomi- nance of easterly components. To the south, between the Equator and N. lat. 5°, a squally damp W.N.W. wind blew continuously, having pre- vailed at least from the 11thof October. On the 27th it became W.S.W., drawing round towards the area of depression. With the barometric rise on the 24th and 25th a N.E. wind set in in Bengal and down the western half of the bay displacing the S.E. wind, which, however, continued to be felt in the immediate neighbourhood of the Nicobars. The cyclone vortex was formed by the indraught of these three currents to the preexisting area of barometric depression. The storm chart of the Bay of Bengal drawn up by Mr. Piddington shows that the majority of the cyclones, the tracks of which are there laid down, proceed from a line running from south to north by the Nicobars, Anda- mans, and the islands of the Arracan coast, following the westward side of the mountain-axis, which, in part submarine, is a prolongation of that of the Sunda Islands. Of these storms, several appear to have originated in the neighbourhood of the Andamans; but none of them have been traced batk to a sufficiently early period to admit of a comparison of the circumstances of their origin with those of the storm now under dis- cussion. The data for the great Calcutta cyclone of October 1864 dis- cussed by Colonel Gastrell and myself in the report published by the Bengal Government, were insufficient fora satisfactory determination of the conditions under which it originated, but they offer several points of simi- larity to those detailed in the preceding pages. The two storms agree approximately in their place of origin, in their course up the bay and over Bengal, and in their termination ; and ag re- gards period, both occurred at the close of the S.W. monsoon. The chief noticeable differences are, that the cyclone of 1864 originated about N. lat. 10°, and therefore 3° or 4° further north, and on the morning of the 2ud of October, or nearly a month earlier. Previously to this date, for at least five days, the wind in Ceylon had been from the west + or W.S.W., * T have tabulated them for the six days previous. Tt We had no data to show how far to the south or south-east this direction prevailed, 480 Mr. H. F. Blanford on the Origin of a Cyclone. [June 17, with occasional squalls, especially on the latter days; and the same stormy damp wind prevailed over the south of the bay up to the Great Andaman on the Ist and 2nd. The greater northern extension of this current is, doubtless, connected with the above-mentioned difference in the position of the storm’s birthplace. At Port Blair, on the 29th and 30th, and over the greater part of the bay as far south as Madras, southerly and east-south-easterly winds prevailed up to the 3rd of October. In Eastern Bengal alone the wind was northerly, becoming N.H. on the Ist and 2nd; but it was not until the 3rd of October that a N.E. wind established itself over the north and west of the bay. It may, however, be noticed that during the five days preceding the cyclone, an unusually high barometer prevailed in Bengal, and this may have been due to the existence of an upper northerly current. A north-east wind was also felt in lat. 15° on the north-west limb of the vortex, on the 2nd, but was evidently merely the indraught of the south-east current. The barometer data for the storm of 1864 were few in number, and not comparable inter se; but we adduced some reason for the inference that a low barometric pressure prevailed near the Andamans for some days pre- viously to the 2nd of October. It appears, then, that the same three wind-currents eventually took part in the formation of both storms, viz. a south-east wind in the south-east of the bay, a north-east wind along the west coast, and a westerly wind to the south ; but that while in the storm of 1864 the north-east wind did not pre- vail until after the formation of the vortex, up to which time the south-east current held possession of the bay, in that of 1867 the former current had established itself three days prior to the commencement of the cyclone. These facts, coupled with the further fact that neither the north-east nor (at this time of year) the south-east currents are stormy winds capable of feeding the vortex and increasing the barometric depression, tend to confirm the view enunciated in the Report on the Caleutta Cyclone of 1864, viz. that the formation of the vortex was mainly determined by the inrush of a saturated westerly current towards the place of low barometer. The fact above mentioned, that the majority of the Bay of Bengal cyclones arise along a line parallel to, and immediately to the west of, the chain of islands that form the eastern boundary of the bay, indicates the operation of some general cause tending to produce a low atmospheric pressure in that region at those seasons at which cyclones are most pre- valent. Such a cause may be suggested, but the data available to me are not sufficiently precise to establish its existence. Ifit can be shown that, either owing to a predominance of marine currents from the south, or to any other cause, the water along the eastern side of the bay has a higher temperature than that of the western side during those months at which cyclones prevail, the increased evaporation thus arising, together with the but despite the difference in mean direction, the wet squally character of this wind permits of its identification with Maury’s westerly monsoon of the line. 1869.] Mr. H. F. Blanford on the Origin of a Cyclone. — 481 more elevated temperature it would impart to the atmosphere, would give rise to a diminution of barometric pressure, small at first, but becoming more marked with the continued operation of the producing cause, so that after several days it might become capable of causing that extensive in- draught of air which appears to be the immediate antecedent of the forma- tion of a cyclone vortex. According to Horsburgh, from April to the early part or middle of October, a current generally sets to the north or north-east all over the bay in the open sea, but governed in its direction and strength by the pre- vailing winds. ‘‘In the eastern side of the bay, and about the entrance to the Malacca Strait more particularly, it sometimes sets to the southward. The current begins to set along the coast of Coromandel to the southward in October, sometimes about the middle of the month. Near the end of this month, or early in November, it begins to run very strong to the southward.’ He adds, however, that the period of the currents or mon- soons changing in the Bay of Bengalis not alwaysthe same. These changes happen in some years nearly a month sooner or later than in others. From this and the remainder of the description, it is to be gathered that the set of the current changes with the monsoon, and that in general its direction and strength are governed by the prevailing winds. Now it is well known that at the change from the south-west to the north-east mon- soon, the latter is first felt down the western part of the bay, and that at this season ships bound to Calcutta from the southward keep up the east of the bay, with a view to catching a favourable wind. It might be ex- pected, therefore, that there would be a tendency to northerly currents in the east of the bay, and to southerly currents in the west; and, so far as can be gathered from Horsburgh’s description, such indeed appears to be the case; but facts are at present wanting to establish it, and also the existence of those differences of water-temperature which would seem to be the necessary consequence. : It would appear from Horsburgh’ s description that, at the commence- ment of the south-east monsoon in May (the minor of the two cyclone seasons), the tendency of the currents is the opposite of the above, that from January to June a northerly current sets strongly up the Coromandel coast, and that from April there is a current to the north or north-east all over the bay, but on the eastern side of the bay, and particularly the entrance to Malacca Strait, it sometimes sets to the south. Now from April to August the sun is vertical over the northern part of the bay ; but no data are available to show how the temperature of the currents is affected by this change in its declination, and I am unable therefore to ascertain how far the supposed condition of a higher temperature in the currents of the east of the bay holds good in the case of those barometric depressions which determine the cyclones of the beginning of the south-west monsoon, and which Piddington’s chart shows to originate in that region. I may, however, remark that, as far as I can gather from the recorded cyclones I 482 Dr. W. A. Miller on a Self-registering Thermometer [June 17, have tabulated, these storms appear to be about half as frequent only at the beginning as at the end of the south-west monsoon. It is probable that in the course of a few years, if not already, the obser- vations of currents and sea temperatures, collected by the Meteorological Department of the Board of Trade, will afford data for a satisfactory dis- cussion of this subject, which is one of great importance to the compre- hension of the meteorology of the Bay. Postscript. Received June 29, 1869*. Since the above was written, I have visited Chittagong, and have found that the elevation of the barometer-cistern at that place above sea-level (which had been reported as 166°46 feet) is actually about 108 ft. only. This correction requires an alteration of the reduced barometric pressures for Chittagong (given on p. 473), which will consequently stand as fol- lows :— 23rd. 24th. 25th. 26th. 27th. Chittagong .. 29°906 29:913 29°949 29-873 29-894 A. few corrections must also be made in the text. The excess of pressure at Chittagong, as compared with certain other stations on the 23rd and 25th, disappears, and on the 26th and 27th the noon pressure at this place becomes lower than at any other station. The conclusions arrived at in the foregoing paper are, however, unaffected by the correction. III. “Note upon a Self-registering Thermometer adapted to Deep-sea Soundings.” By W. A. Mituer, M.D., Treas. and V.P.R.S. Received June 3, 1869. The Fellows of the Royal Society are already aware that the Admiralty, at the request of the Council of the Society, have placed a surveying-ves- sel at the disposal of Dr. Carpenter and his coadjutors for some weeks during the present summer, to enable them to institute certain scientific inquiries in the North Sea. Among the objects which the expedition has in view is the determination of deep-sea temperatures. _ Now it is well known that self-registering thermometers of the ordinary construction are lable to error when sunk to considerable depths in water, in consequence of the diminution produced for the time in the capacity of the bulb under the increased pressure to which it is subjected. The index, from this cause, 1s carried forward beyond the point due to the effect of mere temperature, and the records furnished by the instrument rise too hight. A simple expedient occurred to me as being likely to remove the diffi- * A chart, with wind arrows, showing the limits of the cyclone, accompanies the paper, and is preserved for reference in the Archives of the Society. tT In cea-water of sp. gr. 1:027, the pressure in descending increases at the rate of 280 lbs. upon the square inch for every 100 fathoms, or exactly one ton for every 800 fathoms, 1869. | adapted to Deep-sea Soundings. 453 culty ; and as upon trial it was found to be perfectly successful, I have thought that a notice of the plan pursued might not be nndeceplablet to wae observers. The form of self-registering thermometer which it was decided to em- ploy is one constructed upon Six’s plan. Much care is requisite in adjusting the strength of index-spring, and the size of the pin, so as to allow it to move with sufficient freedom when pressed by the mercury, without running any risk of displacement in the ordinary use of the in- strument while raising or lowering it into the water. Several of these thermometers have been prepared for the purpose with unusual care by Mr. Casella, who has determined the conditions of strength in the spring and diameter of tube most favourable to accuracy. He has also him- self had an hydraulic press constructed expressly with the view of testing these instruments. By means of this press the experiments hereafter to be described were made. The expedient adopted for protecting the ther- mometers from the effects of pressure consisted simply in enclosing the bulb of such a Six’s ther- mometer in a second or outer glass tube, which was fused upon the stem of the instrument in the manner shown in the accompanying figure. This outer tube was nearly filled with alcohol, leaving a little space to allow of variation in bulk due to expansion. The spirit was heated. to displace part of the air by means of its vapour, and the outer tube and its contents were sealed hermeti- cally. In this way, variations in external pressure are prevented from affecting the bulb of the thermo- meter within, whilst changes of temperature in the surrounding medium are speedily transmitted through the thin stratum of interposed alcohol. The thermometer is protected from external in- jury by enclosing it im a suitably constructed copper case, open at top and bottom, for the free passage of the water. In order to test the efficacy of this plan, the instruments to be tried were enclosed in a strong wrought-iron cylinder filled with water, and submitted to hydraulic pressure, which could be raised gradually till it reached three tons upon the square inch, and the amount of pressure could be read as the experiment proceeded upon a gauge attached to the apparatus. Some preliminary trials made upon the 5th of May showed that the 484 Dr. W.A. Miller on a Self-registering Thermometer [June 17, press would work satisfactorily, and that the form of thermometer pro- posed would answer the purpose. These preliminary trials showed that, even in the thermometers with protected bulbs, a forward movement of the index of from 0°:5 to 1° F. occurred during each experiment. This, however, I belieyed was caused, not by any compression of the bulb, but by a real rise of temperature, due to the heat developed by the compression of the water in the cavity of the press. This surmise was shown to be correct by some additional experiments made last week to determine the point. On this occasion the following thermometers were employed :— No. 9645. A mercurial maximum thermometer, on Prof. Phillips’s plan, enclosed in a strong outer tube containing a little spirit of wine, and hermetically sealed. No. 2. A Six’s thermometer, with the bulb protected, as proposed by myself, with an outer tube. No. 5. A Six’s thermometer, with a long recurved cylindrical bulb, also protected in a similar manner. No. 1. Six’s thermometer, with cylindrical bulb of extra thickness, not protected. ? No. 3. Six’s thermometer, with spherical bulb, extra thick glass, not protected. No. 6. Admiralty instrument, Six’s thermometer, ebonite scale, bulb not protected. No. 9651. An ordinary Phillips’s maximum mercurial thermometer, spherical bulb, not protected. The hydraulic press was exposed in an open yard, and had been filled with water several hours before. A maximum thermometer, introduced into a wrought-iron tube filled with water, open at one end to the outer air, closed at the other, where it passed into the water contained in the press, registered 46°°7 at the commencement, and 47° at the end of the experiment. ‘Temperature of the external air 49° F. In commencing the experiment, the seven thermometers under trial were introduced into the water in the cavity of the press, and after a lapse of ten minutes the indices of each were set, carefully read, and each instru- ment was immediately replaced in the press, which was then closed, and by working the pump the pressure was gradually raised to 24 tons upon the inch. It was maintained at this point for forty minutes, in order to allow time for the slight elevation of temperature caused by the compres- sion of the water to equalize itself with that of the body of the apparatus. At the end of the forty minutes the pressure was rapidly relaxed. A cor- responding depression of temperature was thus occasioned, the press was opened immediately, and the position of the indices of each thermometer was again read carefully ; and the water was found to be at a temperature sensibly lower than before the experiment began, by about 0°°6 F. By this means it was proved that the forward movement of the index in the pro- tected thermometers, amounting to 0°°9, was really due to temperature, 1869.] adapted to Deep-sea Soundings. 485 and not to any temporary change in the capacity of the bulb produced by pressure. This will be rendered evident by an examination of the subjoined Table of observed temperatures :— First Series: Pressure 2} tons per square inch. Masher of | Minimum index. || Maximum index. etal Whermometer. | pir [| Arian SEO | Before. | After. || Before.| After. After. Protected ... 9645| ...... ee 47-0 | 47-7 ” wet yor Ac. -| .46:5 »46°7 47-6 465 35 5| 47:0 | 463 46°5 47-6 46:0 PEM dis see | geusss | focage.ce [fp teenes 47-6 Unprotected. 1] 467 | 464 || 465 | 540° |. 46 is 3| 47:0 46°5 46:5 56°5 46 5 56| 47:0 | 460 || 47:0 | 555 46 Sl i 46-7 | 1185 Mean ...... __ 46°9 463 2 oy gen meee 46:1 Temperature of external air...... 49 49 Temperature of thermometer ; PEN DECSA 625.5 exo stanean tat | aa 7 In the Phillips’s maximum thermometer, with unprotected spherical bulb, No. 9651, the bulb had experienced so great a degree of compression as to drive the index almost to the top of the tube. In all the other un- protected instruments, which had been made with bulbs of unusual thick- ness, the index had been driven beyond its proper position from 6°°4 to 8°-9 F.; and it is obvious that the amount of this error must vary in each instrument with the varying thickness of the bulb and its power of resist- ing compression. Notwithstanding the great pressure to which these instruments had been subjected, all of them, without exception, recovered their original scale- readings as soon as the pressure was removed. It will be seen that the mean rise of temperature indicated by the three protected instruments was 0°°9 F., whilst the mean depression registered on removing the pressure amounted upon all the instruments which ad- mitted of its measurement to 0°°6, an agreement as close as was to be expected from the conditions of the experiment. A second set of experiments was made upon the same set of instruments, with the exception of 9651; but the pressure was now raised to 3 tons upon the inch; this was maintained for ten minutes. When it had risen to 22 tons a slight report was heard in the press, indicating the fracture of one of the thermometers. On examining the contents of the press afterwards it was found that No. 2 was broken, the others were uninjured, 486 Rey. S. J. Perry on the Magnetic ~~ (Sane, The broken thermometer was the earliest constructed upon the plan now proposed, and it was consequently not quite so well finished as subsequent practice has secured for those of later construction. The results of the trial under the higher pressures showed an increase in the amount of com- pression experienced by the unprotected instruments rising in one instance to asmuchas 11°°5 F. With the protected instruments the rise did not exceed 1°°5, due, as before, to the heat evolved from the water by its compression. A pressure of 3 tons, it may be observed, would be equal to that of 448 atmospheres of 15 lb. upon the square inch; andif it be assumed that the diminution in bulk of water under compression continues uniformiy at the rate of 47 millionths of its bulk for each additional atmosphere, the reduc- tion in bulk of water under a pressure of 3 tons upon the square inch will amount to about ,4 of its origmal volume. This probably is too high an estimate, as the rate of diminution would most likely decrease as the pressure increases. IV. “ Magnetic Survey of the West of France.” By the Rev. StnpHEn J. Perry, F.R.A.S., F.M.S. Communicated by the President. Received June 3, 1869. (Abstract.) This survey was undertaken by the Rev. W, Sidgreaves and myself in connexion with the Observatory at Stonyhurst College. The instruments employed were those in constant use for the monthly observations of the magnetic elements at this observatory, 2. e. Barrow’s dip-circle, No. 33, a unifilar by Jones, and Frodsham’s chronometer, No. 3148. A portable altazimuth and an aneroid barometer were kindly placed at our disposal by the late Mr. Cooke. . A complete set of observations of the dip, declination, and horizontal intensity were taken at the following stations :—Paris, Laval, Brest, Vannes, Angers, Poitiers, Bordeaux, Abbadia (near Hendaye), Loyola, Bayonne, Pau, Toulouse, Périgueux, Bourges, Paris (a second time), and Amiens. The chronometer was compared on every possible occasion, and its rate was found to be nearly always 2° per day. The dip was observed according to the description of the observation given by the President of the Royal Society in the ‘ Manual of Scientific Inquiry.’ The method of vibrations and deflections was invariably adopted for determining the horizontal component of the intensity. For the declination it was deemed most convenient to find the azimuth of a fixed mark by observing transits of the sun with Cooke’s altazimuth, and then to measure the azimuthal angle between the magnet and the fixed mark with Jones’s unifilar. Dr. Lloyd’s method, by reflection, was made use of only at Brest. The results of these observations, reduced to the epoch January Ist, 1869, are contained in the following Table :— 1869. | Survey of the West of France. Dip. Decl. HEB: - 6) ° ° Paris... 65°875 17°84] 4°1133 TT Se 65°802 19:073.- 4°1245 iT ee 66°460 21-005 4:0442 lL ee a OOnoo 20°225 4-1328 Jp ae 65140 19°093 4°2106 EES ee 64°468 18°306 4°2955 0 63°383 18°209 4°4110 Abbadia...... 62°463 18°235 4°5456 2 ee 62°5038 18°391 4°5520 i 61°970 17°825 4°5823 _ LE 62°018 L122 4°5883 memrevietix........--- 63°398 17°682 4°4268 WOOMTPES 5... os 64°543 17003 4°2845 mmicens........ 66°672 18°316 4°0143 Secular Variation.. .. —3'°68 +0:0050 ). meceleration........ 0°43 ( 0:00002 (me 0- 3 The secular variation has been obtained by comparing the seas of this survey with those of Dr. Lamont, taken about ten years previously. Maps of the isodynamice, isoclinal, and isogonic lines of the epoch, Sep- | tember Ist, 1868, are drawn from the following data, Paris being chosen as the central station for reasons given in the paper :-— For the isoclinals the direction is Bega 2a. 10 Beto S273? 25). 10 Ws “ the distance between the lines being 44°25 geographical miles for a change of 30’ of dip. The direction for the isogonics is Ne20° SL: 16"-E. to S.:20° 31° 16" W., and the distance only slightly greater than for the isoclinals, 72. e. 44°35 geographical miles for 30’ of angle. The isodynamics lie in the direction ING 70% 34137 Eto 82702 34).13" W.; the distance in this case being 115 geographical miles for a change of 0°1 in the intensity. For the lines of equal horizontal force the direction is N. 74° 19’ 30” E. to S. 74° 19’ 30” W., and 72 geographical miles the distance separating lines where the horizontal intensity differs by 0°1. An attempt has been made to apply a correction for the magnetic dis- turbances at the times of observation by means of the magnetograms ob- tained at Stonyhurst Observatory during the Survey ; but these corrections have not been taken into account. in forming the equations of condition from which the final results have been obtained. The probable error of any single observation of the dip, declination, total force, and. horizontal component are found to be respectively 3°13; 0°95; 0°0144 ; and 0-0067. VOL. XVII. 20 A488 Messrs. Stewart and Loewy on the true —§ [June 17, V. “An Account of Experiments made at the Kew Observatory for determining the true Vacuum- and Temperature-Corrections to Pendulum Observations.” By Batrour Stewart, Esq., F.R.S., and Bengamin Lorwy, Hsq., F.R.A.S. Received May 27, 1869. ]. Pendulum-observations, whether undertaken for the purpose of ob- taining unalterable standards of length or for physical and geodetic objects, are usually made in air or in a receiver, from which the air is partially or almost entirely withdrawn ; and in order to render such observations, made at different places and by different observers, capable of intercomparison, they are, by means of a ‘‘ correction for buoyancy,” reduced to a vacuum. It is well known that the most illustrious physicists and mathematicians have given a great deal of attention to a correct determination of the prin- ciples on which this reduction to a vacuum ought to be based, and of the actual resistance which such a body as a pendulum meets during its vibra- tions ina fluid body. Until some years ago, especially since the researches of General Sabine and Bessel, it was thought best to determine for every pendulum a certain constant by finding its vibrations in air at the usual pressure, and also in a receiver from which the air is as much as possible withdrawn; from the difference in the number of vibrations thus found the correction was then calculated on the assumption that this difference is proportional to the difference of density of the air. 2. In the pendulum-observations made at the Kew Observatory in con- nexion with the Great Trigonometrical Survey of India (vide Proceedings of the Royal Society for 1865, No. 78) we adopted, for determining the necessary constant, the method first carried out by General Sabine, and of which a detailed account is given in the Philosophical Transactions for 1829, Part I. page 207 &c. But since our account has been published, two eminent physicists, Professor Clerk Maxwell and Professor O. E. Meyer in Breslau, have independently investigated the internal friction in gases, and its effect upon bodies moving in them; and among the prominent results ob- tained by them is this, that the influence of the internal friction of a fluid on a moving body is not proportional to its density. However, for small differences of pressure, such as those experienced by General Sabine in his researches, the old method for determining the correction is sufficiently accurate ; or again, if a series of such experiments as our own fundamental Kew observations for India be made at a very low pressure, say from 3 an inch to 14 inch, the correction is itself a very small quantity; and the application of a more correct principle of reduction will not sensibly affect the ultimate results, because the difference between the true and approxi- mate correction is in such a case extremely small.- But if, as is the case in the Indian observations, experiments are made at higher and varying pressures, it is very desirable to apply experimental methods which will give the true correction. 3. With a view to collect for the theory of the subject a great many 1869.] Corrections to Pendulum Observations. 489 carefully conducted experiments, and also to supply those who are actually engaged in pendulum-experiments at the present time with practically valuable results, we proposed to ourselves to observe the behaviour of pen- dulums of the different forms hitherto used in such researches in which the pendulum is employed, at pressures varying through the whole range, from the lowest obtainable in a receiver to the usual atmospheric pressure. The carrying out of our intentions met, however, with many delays through unavoidable circumstances, and there is, indeed, at present little prospect of our being able to complete the whole of the original plan. We give, therefore, here an account of some preliminary results which are, in our opinion, not without practical importance, and which will certainly find their use in the reduction of observations made with pendulums of a form similar to that used by ourselves, viz. that form of reversible pendulum known as “‘ Kater’s pendulum.” 4. The following is an account of the operations :—The pendulum was swung in the Kew receiver, made of five pieces, two of metal and three of glass, the parts fitting closely, and the whole being connected with siphon- gauge and air-pump by tubes. One of the metal pieces is perforated be- hind and in front, and the apertures are covered by plate glass for the observation of the coincidences. The pendulum was swung at the following pressures :— I. At about 4 of an inch V. Between 4and 5inches.| X. At about 20 inches. (lowest obtainable). NE as Gee rasOey ass D4 ern yee eee eee IT. Between1andz2inches.} WII. By age ass i XIT. At the fullatmosphe- TIT. Peet Ss, VIII. At about ro inches. ric pressure. IV. ” 3 4 » Ix. ” ” 15 EP) | At each pressure a good many observations were made, in order to ensure reliable mean results. 5. With reference to the registration of the observations, we have strictly adhered to the method previously adopted after careful consideration, and explained in our former account; hence we need not here enter upon this part again. Instead of registering one coincidence at the beginning, during the progress, and at the end of an experiment, we have this time in most cases observed three successive coincidences, and the arithmetical mean of these, together with the mean of the corresponding registrations of are, temperature, and pressure, stands for one observation; we think that this method ensures greater correctness, although it is more laborious than that previously adopted. , _ 6. The reduction of the observations comprises, as shown in the previous paper alluded to above, several corrections to be applied to the number of abserved vibrations ; we shall mention here only those points which differ numerically or experimentally from the numbers or methods explained in that paper, which contains also an experiment with its full reductions. By referring to these and the following remarks our method of procedure will be so abundantly clear, we hope, that we shall be able to proceed immedi- ately afterwards to the statement of the final results. 202 490 Messrs. Stewart and Loewy on the true [June 17, A. Correction of the observed arc-readings and reduction of the vibra- tions to infinitely small ares. We have previously shown that if D=distance of scale from the object-glass of the telescope, d= distance of scale from the tailpiece of the pendulum, O=observed scale-reading for the whole arc of vibration, . S=distance of indicating-point of the tailpiece from the knife-edge, a=true semiare of vibration, O(D—d) 2DS) 2 expressing all distances in inches into which the scale is divided. In our case repeated measurements gave the following mean values for these quantities :— D=101°86 inches ; d=0°56 inch ; S=47-55 inches. Hencewe have to add los(spe \ =los( sag rG aT 5 = 270194252 to the logarithm of the observed scale-readings to obtain the semiare of - vibration. For the reduction to infinitely small arcs, we have again used the well- known formula number of infinitely small vibrations M sin (2+a’) sin (2—a’) 32 (log sin a—log sin a’)’ the symbols having the same meaning as previously stated. We are well aware that more convenient formule, and more correct methods, have been used or proposed by different observers for this cor- rection; but we thought it best to adhere to a uniform method in the reductions, in order to facilitate any future rediscussion of our original observations (which are preserved at the Kew Observatory), should such appear desirable when the results of the Indian pendulum observations will be published. B. The precise determination of the rate of the clock might have been of minor importance in our experiments, an approximate uniformity of rate being the chief desideratum. We expected, however, that very small dif- ferences in the number of vibrations would result in those experiments where the pressure differed only by an inch or even less. We considered it hence of the utmost value to have a precise record of the behaviour of the clock during these experiments, so as to discover at once changes in the rate, and to make our reductions depending on it for each experiment. A great number of transit-observations were accordingly made, and during these not only the pendulum-clock, but also the behaviour of a chronometer by Dent and a meantime-clock by Shelton was accurately determined. These two latter served during those days when no transits could be ob- tained for deducing the rate of the pendulum-clock by intercomparison. From the whole of these observations the following Table of the number of vibrations during a mean solar day has been calculated for every day of then tan a= =n+n 1869. | Corrections to Pendulum Observations. 491 the four months during which the experiments were carried on, each re- sult being of course employed for the pendulum-experiments of the corre- sponding day. The Table shows that our plan was the safest, as differences of nearly one second are observable; these differences have, however, ap- parently no connexion with changes of temperature, as the rate of the clock during the artificial heating of the pendulum-room, of which we shall soon have to speak, showed hardly any difference from the mean rate, proving that the compensation was not faulty. The pendulum-clock showing sidereal time, the Table is calculated from the formula:—Number of vibrations in a mean solar day =N’= 86636°5354(1— seqa)' and hence: Number of vibrations of detached t pendulum =N=‘", where V, V’' are respectively the number of vibra- tions of the detached and clock-pendulum from beginning to the end of our experiment. TaBxe I. Number of Vibrations made by the clock-pendulum during a mean solar day. 1866. |September.| October. | November.) December. I. | 76577°40 | 86577°38 | 86577°43 | 86577°50 Se agi "25 7a "4.0 3: De 14 ee) "39 4. "29 09 | 86576-99 48 5. | 86576°97 "21 | 86577°02 "31 6. 33 "22 | $6576°94 319 vp “81 06 95 "50 8. 88 | 8657691 "99 54 9- "90 | 86577°00 | 86577711 54 Io. | 86577°04 °ED 17 5t II. "00 LE "24. 61 12. 07 28 ae 63 13. 26 ob Ke) 28 70 14. "16 "04, "40 yh) 15. AE "2.2 52 64. 16. "08 "2.9 "61 64 17. | 86576798 "4.0 "60 60 18. "gO “50 ‘70 7° TQ. ve 194 75 TE 20. "90 "60 71 66 21. "99 “61 80 59 Bee 93 43 74 40 2a. "35 28 79 47 24. "83 227, 62 44 25. "99 ‘47 "51 46 26. |. 86577°20 40 49 48 27% ail "29 "44 47 28. 33 33 "64. 59 29. fe) Bats 56 61 30. | 86577°24 "29 | 86577°56 “51 cee aes $6577°40 HA 36577°56 C. Correction for temperature.—The method of suspending the ther- 492 Messrs. Stewart and Loewy 9n the true [June 17, mometers was precisely the same as that used in our previous experiments and described in the account we gave of them to the Royal Society. The formula employed for deducing the most probable mean temperature for each experiment was as before, using the same symbols :— tt ; RS i ‘ fi" sgn Pi el WT sll oo As explained in the paper mentioned above, we had then no time at our disposal to swing the pendulums used at extremes of temperature, and hence we availed ourselves of the elaborate series of experiments on the temperature-correction of pendulums made by General Sabine (vide Phil. Trans. 1830, p. 251), adopting the mean of his entire results, viz. 0°435 vibrations per diem, as correction for 1° of Fahrenheit’s scale for our reductions. In our present investigation we thought it indispensable to obtain the utmost accuracy, by ascertaining the temperature-correction for each pen- dulum intended to be used by an independent series of experiments in an artificially heated room, the natural annual range of temperature in the Kew pendulum-room being insufficient for our purposes. The arrangement consisted in erecting an iron stove in the vicinity of the pendulum- apparatus, and carrying a long pipe through the whole height of the room. By several preliminary trials, it was soon found that up to about 80° the temperature could be maintained constant for several hours, but that the difficulties increased with the rise of the temperature, and be- came almost unsurmountable when: the temperature was above 100°. Besides the maintenance of a pretty equable temperature during the dura- tion of an experiment, another. difficulty arose. The pillar of masonry which carries the apparatus on one side, and the wall of the room on the other, prevented us giving to the heating-apparatus such a lateral po- sition as to bring the bar which carried the thermometers and the pen- dulum in equal proximity to it. The stove had to be placed in front, somewhat to the left of the apparatus, and hence the brass bar which carried the thermometers was nearer to the source of heat than the pendu- lum. In order to arrive at the most exact measurement of the real ‘temperature of the pendulum, two additional thermometers were sus- pended behind it, at about the same distance from it as those in front, and all four were read during the experiments. . Seeing from the preliminary trials that an approximately equal distri- bution of temperature throughout the apparatus could only be relied upon up to about 70°, and that after that point the differences in the readings of the thermometers, behind and in front, increased to an extra- ordinary degree, we decided upon making two different classes of ex- periments, viz. one set confined to temperatures of about 70°, and another comprising higher temperatures; and we further, during the pro- 1869. ] Corrections to Pendulum Observations. 493 cess of reducing our observations, came to the conclusion that it would be best to exclude all experiments made at temperatures above 100°, and also those where great differences in the readings for temperature occurred, from our final results. The principle which guided us was not to vitiate good observations by doubtful ones ; and the following small Table, showing the temperature-readings during four experiments, taken quite at random, will show best how we proceeded :— | L | it, Thermometer | Thermometer | Thermometer | Thermometer in front. behind. | in front. behind. Upper | Lower | Upper | Lower | Upper | Lower | Upper | Lower therm. | therm. | therm. | therm. | therm. | therm. | therm. | therm. ed | | — —— 7E2O ||) 79°20 '}, 70°0 GRae cue hh 0 550 a3i7 84°38 eo BEINN i415 | 7o20 | 70°4 69°4. | |S || 86-2 33°8 84°90 83-0 ]/5 | ZE30 ) 7G°00 | 70°6 697 | BU} 86-7 $36 83°3 32°6 == 71°85 | 69°60 | 71°4 714 (|8 S|) 78°4 78°8 82°2 82°1 eo, 72°00 | 69°55 71°4 716 |i || 79°4 80°4 80°8 812 5 71°90 | 69°50 | 71°4 70°7 a | 8172 82°0 79°4 32°8 ee ee ee Mean 70-9 70°6 | 82°5 82°45 70°8 82°5 EEF, | EY. 99°5 | 987 | 92°4 | 92°5|., || 7084 | 107°3 | TOO" | 99°5 +2 974 | 97°0 g1°6 906 || 5 107°6 | 106°5 99'7 | 99° |18_. 95°5 | 943 | 903 | 881 \}g'B]] 105°7 | 103°3 | 985 | 973 12 8 eee > | 782 (FS a OFF | 965 | 98 | Ors (leo eee | 774 | Te OV eo} 963 ° OSE f° 922 | 909 | re 809 | 792 | 755 | 7417 |S 959 | 947 | 918 | 903/7/R a ae) a Mean 88:8 33°7 I01°3 953 a, a ee 86:2 | 93°3 i Although in the rejected experiments the means of all readings of both sets of thermometers approach each other, still there occurs a fall of nearly 20° at the end of an experiment, as compared with that temperature which is recorded at the beginning, besides differences of nearly 8° between the thermometers in front and those at the back of the pendulum. That the temperature of the latter during an experiment is represented by the arithmetical mean of such discordant readings, we think most unlikely; and hence these experiments and similar ones were not used, although, of course, the number of available experiments was thereby reduced. | : The following experiments, which represent the final results of this temperature-investigation, deserve at least some confidence, although we 494: Messrs. Stewart and Loewy on the true | [June 17, should have liked to see their number much increased. To avoid a cor- rection for pressure, we took care to correct at once, before beginning an experiment, the reading of the gauge to 32° of temperature, and to regulate by a few strokes of the pump the pressure, so as to assimilate it to the mean pressure (also reduced to 32°) of the experiments pre- viously made in cold air. All pressures are reduced to 32°, and the small difference of pressure which still resulted, comparing the mean er the hot-air experiments with those in cold air, amounting to about tov of an inch, has been disregarded in the final reduction. An attempt to test the constancy of the temperature-correction in vacuo, with reference to a suggestion made by Colonel Walker, Super- tendent of the Great Indian Survey, who suspects that the coefficient ot expansion of a pendulum in air varies slightly from that in a vacuum, proved a failure. The pomatum which is used for tightening the dif- ferent parts of the receiver melted by the heat of the stove, and rendered it impossible to reduce the pressure in the receiver sufficiently for the purpose of the experiments. I. Experiments made in cold air. | II. Experiments made in hot air. No. No. of No. No. of of Te = Pressure.| vibrations of Pees Pressure.| vibrations exp. ; per day. exp. Penne per day. S inches. | bs inches. I. | 47°84 | 30°052 | 86013°60 X.| 76 29°964 | 86002°72 Zon ld a7, 30°112 | 86013°76 zs [> 7s 29°970 | 86002°64 25° | eAtonag 30°182 | 36013°82 2/4 3.| 72°71 29°958 | 86002°50 4- | 46°25 | 29°938 | 8601402 || 4.| 70°8 29°950 | 86002°90 ea 72 30°460 | 36013°58 Fy Cool 73.5 29°960 | 86002°43 Oma e4 7201 29°498 | 86013°64 2 eas oss 29°914 | 85997784 7- | 48°43 | 297582 | 8601398 >) 20 sa8oa5 29°988 | 85997°10 8. | 47°76 | 29°328 | 86014"40 || 2 3: | °° 83'9" aoe 85995°65 g- | 45°09 | 30°202 | 86013°90 Bi \4.| 88:3 | 29°941 | 8599223 Io. | 4619 | 30°011 | 86013°99 ®| | 5.| -go°8 29'982 | 85992°73 11. | 47°50 | 30°107 | 86013°61 | “| \6.| 99°9 | 29971 | 85988'43 The following are the mean results, with their respective differences :— Temp. Pressure. Vibra- ‘s inches. tions. A. Experiments in cold air ............... AFLG Veen: 201952) paxseee 86013°85 B. Experiments in hot air, first set ...... TIA. eee 29°960) fonece 8600264 C. Experiments in hot air, second set... 88:00 ...... 29°959 .:--50 85994;00 Resulting differences of temperature and number of vibrations :— Temperature. Vibrations. 1869. ] Corrections to Pendulum Observations. 495 Hence we find a correction between 2 2 BI°25 2 F \ 47°16 and 71°64 of = "458 vibrations 24°48 hoa f 3 per diem for one AerG 7 88-00 5, a 486 5 degree of Fahr- fe 4 enheit’s scale. : : 23 oa 7564." ,,@aS°OO 5, 756 528 5 Comparing these results with those obtained by General Sabine (Phil. Trans. 1830, p. 251, &c.), we find that the pendulums employed by him gave a correction of 0°44 of a vibration per diem for each degree of Fahrenheit between 30° and 60°, a result which agrees well with that found by ourselves between 40° and 70°, the small difference being probably referable to a difference in the composition of the metal of which the pendulums were made. But a considerable difference appears in the expe- riments made at the higher temperature. General Sabine made some experiments, previously to those discussed in the above-mentioned paper, with two different pendulums in a chamber artificially heated to between 80° and 90°, which gave for the correction for each degree of Fahrenheit, respectively for the two pendulums, 0°432 and 0-430 vibrations, cor- responding to that part of the thermometer-scale which is included be- tween 45° and 85°. These results are somewhat different from those which are obtained for the scale-reading between 30° and 60°, and General Sabine points to this difference in the following words * :— “In the experiments in the chamber artificially heated, the fluctuations of temperature, in spite of every precaution, were considerable, and rendered the determination of the mean temperature more difficult, and probably less exact than in the natural temperatures ; hence it would be unsafe to conclude in favour of the inference to which these facts would otherwise lead, that the correction at high temperatures is less than at low temperatures, or that the metal expands a smaller proportion of its length for one degree between 85° and 45° than for one degree between 60° and 30°.” Our own experiments, on the other hand, seem to agree with the general fact that the coefficient of expansion increases with the tem- perature, and that in a series of experiments a lower range of temperature will give a lower, a higher range a greater value for the expansion for one degree. Nevertheless the values resulting from our high temperature- experiments appear decidedly too large to be explained solely by this general behaviour of bodies; and in our reductions of the pressure-expe- riments, where the differences of temperature, as will be seen in the fol- lowing paragraph, are inconsiderable, we have adopted that value for the temperature-correction which results from the experiments between 45° and 70°, viz. 0°458 of a yibration for one degree, a result which not only well agrees with those found by General Sabine, but also appeared to our * Phil, Trans. 1830, p. 252, 496 Messrs. Stewart and Loewy on the true —- [June 17, own considerations the most reliable, for reasons which will appear presently. j Speaking generally of the subject of the temperature-correction, we must admit that our experiments do not tend to remove the difficulties that seem to surround it. Our experience goes to prove, what the Indian officers, entrusted with the pendulum-experiments and their reduction, have also suspected, that the thermometers fixed to a so-called dummy-bar (in order to place them in conditions similar to the swinging pendulum) do not give a true indication of the real temperature of the pendulum. If this is the case, the differences found by ourselves between the result of the lower and that of the higher range can easily be understood. Indeed, during the progress of these experiments it has always appeared to us that not only the fluctuations indicated by the thermometers are greater in range than those to which the pendulum itself is subjected, but that they are also more rapid, and that the heavy and substantial pen- dulum cannot keep time in these changes with the light and delicate thermometers which are not absolutely sealed up into the substance itself. In our experiments, each of which lasted from one to two hours, a high temperature was usually produced at the beginning, and we attempted to maintain the heat as much as possible by keeping the pendulum-room closely shut on all sides during the progress of the experiment. The inrush of cold currents can, however, obviously not be wholly prevented, and a steady, more or less considerable fall of the temperature is recorded in each of the experiments beyond 70°. This fall affects, in our opinion, chiefly the thermometers themselves, while probably the pendulum main- tains its higher temperature much longer. Thus we are inclined to think that the mean temperature of the pendulum, if it could by some means be exactly ascertained, might perhaps appear considerably higher than the mean of the thermometer-readings recorded ; and to this circuni- stance we ascribe it mainly that the high temperature-experiments give too large a correction, for in these experiments a greater difference in the number of vibrations corresponds to an apparently smaller difference in temperature. The question will, we have reason to hope, find its best solution by the labours of Colonel Walker and Captain Basevi in India, where these gentlemen can avail themselves of a great natural range, which will free the experiments from the doubts and difficulties met by ourselves ; but we cannot conclude this part without reminding experimenters of the words with which, nearly forty years ago, General Sabine concluded the account of his own experiments, and which have gained new force by the short- comings of our own investigations *. ‘Tt seems therefore desirable, for the sake of experiments, which are becoming greatly multiplied, and which are daily increasing in accuracy, that means should be devised of obtaining the rates of pendulums in * Phil. Trans, 1830, p. 253. : 1869. ] Corrections to Pendulum Observations. 497 artificial temperatures, embracing a wider range than the natural tem- peratures, but capable of being determined with equal accuracy.” 7. There remains now only to give the results of the experiments made for determining the changes in the number of vibrations of our pendulum produced by varying pressures, and hence the correction necessary to reduce experiments made at any pressure toa vacuum. ‘These results, as given by each separate experiment, are contained in the following Table :— Taste II. Experiments for determining the number of vibrations made by Kater’s invariable pendulum at different pressures. > te Full atmospheric pressure. About 25 inches. About 20 inches. 1.0) ee a ck Pres- | Vibra- Pres- | Vibra- Pres- | Vibra- ? eo, _| Muehes. > | inches. inches. I. | 47°84 30°052| 86013°60} 45°82] 24°632| 86014°57| 47°66| 19°895| 86015°87 IT. | 47°77 | 30°112| 86013°76| 45°54| 24°634| 86014°70| 47°21 | 19°852]| 86015°99 IIT. | 46°33 | 30°182| 8601382 | 46°03| 24°620/ 86014°71| 51°04 19°902| 8601601 IV. | 46°25 | 29°938| 8601402 | 47°19 | 24°599| 86014°49| 48°00] 19°914| 86016°07 V. | 47°72| 30°460| 86013°58| 51°01 | 24°651| 86014°60| 46°47| 19°921 | 86016°10 VI. | 47°91 | 29°498| 86013°64| 49°84| 24°646| 86014°70| 49°00| 19°864| 86015°94 VIL. | 48-43 | 29°582 | 86013°98 VIII. | 47°76! 29°328| 86014°40 IX. | 45°09 | 30°202| 8601390 X. | 46°19 | 30°011 | 86013°99 XI. | 47°50] 30°107]| 86013°61 About 15 inches. About to inches. Between 7 and 8 inches. No. of : ereieske Oh eel ks oe ee experi- ment. | Temp. Pres- Vibra- sure. tions. Pres- | Vibra- sure. tions. moss o | inches. o | inches. a) |pinehes: T. | 43°47| 14°563| 86017°91| 50°75| 9'998 | 86019°65| 49°37| 77586 | 86021°61 IT. | 44°30] 14°567| 8601734) 45°54 9°868 | 86019°'29| 54°11] 7°491 | 86021°41 IIT. | 50°07} 14°532| 86018°20| 47°13] 9°900 | 8601943} 51°29| 7°303 | 86021°30 IV. | 51°71 | 14°680}| 86017°95| 48°24| 9°870 | 86019°60}| 50°06} 7°554 | 86021'44 V.| 47°09| 14°575| 86018°00| 4g'o1| 10015 | 86019°35| 53°42| 77601 | 86021719 VI. | 46°83) 14°499| 86017°95| 51°77| 10°064 | 86019°51 | 48°73) 7°384 | 86021°58 | 54°33 | 14°555| 86017°93 Pres- Vibra- sure. tions. Temp. Temp. Between 5 and 6 inches. | Between 4 and 5 inches. | Between 3 and 4 inches. No. of ig on Pres- | Vibra- Tem Pres- | Vibra- cgay Pres- | Vibra- 4 P-| sure. tions. P-| sure. tions. ‘| sure. tions. be a ate eepat ya. ee a ea > | Iches. o _| inches. inches. oO T. | 52°13) 5°461 | 86022°10| 51°07| 4°241 | 86022°48| 51°34] 3°144 | 86023°03 II. | 47°86! 5°420 | 86022711] 51°17] 4°245 | 86022°71| 50°95] 3°155 | 8602290 ma | 48°90, 5°510 | 86021°97| 54°06| 4:440 | 86022°69| 50°80) 3°266 | 86022°94 IV. | 51°30! 5403 | 86021°84| 50°39| 4°530 | 86022°69| 52°09] 3°204 | 86022°70 V. | 49°63! 5°390 | 86022719] 49°384| 4°107 | 86022°37| 54°16) 3°170 | 86022°71 Ge eye | 5489 | 86022715] 54°77| 4°298 | 86022°54| 53°70| 3°104 | 86022°95 | a TABLE II. (continued), 498 Between 2 and 3 inches. No. of experi- é fet ment. | Temp. ae oe > _| inches. To e517501 2373 | 60023723 II. | 48°93 | 2°462 | 86023'09 TIT. | 55°55] 2°501 | 86023°05 IV. | 54°76} 2°389 | 8602321 V.| 52°38 | 2°417 | 86023708 VI. | 54°14.) 2°451 | 86023:23 5 WE A hee 8 shen, each Between 1 and 2 inches. Pres- | Vibra- Pres- —— sure. tions. 2 sure. a inch. is inch. 60°97| 1°393 | 86023°35| 62°76| 0472 59°47| 1°416 | 86023°24| 60°85 | 0°431 58°32| 1411 | 86023°04| 60°79] 0444 61°15 | 1°430 | 86023°45| 61°57| 0°451 60°83 | 1°471 | 86023°65)| 62°36] 0425 57°58| 1°319 | 86023°17| 60°77| 0°389 spisiede all Ragistte | =eaanmeeee 49°72 | 0°427 Messrs. Stewart and Loewy on the true [June 17, Below 1 inch. Vibra- tions. 86023°26 86023°47 86023°60 86023°74 86023°79 $6023°31 $6023°55 Tas ie III. Mean results of Pressure-experiments. Mean Mean number Mean Mean number pressure. of vibrations pressure. of vibrations inches. per diem. inches. per diem. Looms 86023°53 VIL.) 27486) eee 86021°42 TR 0409 or eee 36023 °32 VEIL. “9-9530- eaee 86019°47 EET Ve 2432 Wires $6023°15 TX... 14°5§69 eee 86017°97 ye ie Wee RG et 8602237 Xe. I9S9Le | eee 86016'00 Vi. i4gi10 86022°58 XI. 24°630 36014°63 Wil esaaign Beene. 86022°06 ALL. | “2g°g52 0 ees 86013°85 while Table III. contains the resulting means for the different sets, as specified in paragraph 4. The experiments made at a full atmospheric pressure are the same as those given previously in connexion with the temperature-experiments, but they are here repeated for the sake of comparison. Their mean temperature being 47°°16, the whole of the other experiments has been reduced to the same temperature by means of the coefficient adopted i in accordance with our preceding statement. The results as given in Table III. do not require any special remarks. It will be seen that the resistance of the air to the motion of a pendu- lum, as measured by the number of its vibrations, increases very slowly up to 7 or 8 inches of pressure; a more energetic action is exerted up to about 20 inches, and after that point the resistance increases very slowly up to the full atmospheric pressure. This behaviour is represented in a more impressive manner on the ac- companying curves. One of them, marked A, shows simply the result- ing number of vibrations at the given pressures, which latter form the abscissee, while the former are the ordinates. The second curve, B, is derived from A, by assuming the whole correction necessary to reduce the pendulum observations made in air to a vacuum as unity, and expressing the correction for intermediate pressures as fractions. The ordinate representing unity has been divided into forty parts, each representing 0°025, enabling us to represent the correction to three decimals with great precision. Corrections to Pendulum Observations. 499 1869.] 000.0 : a < ae i 0$7.0 peeeeadncneln : a ; TELA . o$Z.0 the old correction, and shows best » gives eee co BOSS Et anaes —<—}—-}- a g00.02098 00.0£098 The straight dotted line, C how it differs from the correct one. 500 Mr. T. Graham on Hydrogenium. [June 17, VI. “ Additional Observations on Hydrogenium.” By Txomas Grauam, F.R.S., Master of the Mint. Received June 10, 1869. From the elongation of a palladium wire, caused by the occlusion of hydrogen, the density of hydrogenium was inferred to be a little under 2. But it is now to be remarked that another number of half that amount may be deduced with equal probability from the same experimental data. This double result is a consequence of the singular permanent shorten- ing of the palladium wire observed after the expulsion of hydrogen. In a particular observation formerly described, for instance, a wiré of 609°14 millims. increased in length to 618°92 millims. when charged with hy- drogen, and fell to 599-44 millims. when the hydrogen was extracted. The elongation was 9°78 millims., and the absolute shortening or retrac- tion 9°7 millims., making the extreme difference in length 19°48 millims. The elongation and retraction would appear, indeed, to be equal in amount. Now it is by no means impossible that the volume added to the wire by the hydrogenium is represented by the elongation and re- traction taken together, and not by the elongation alone, as hitherto assumed. It is only necessary to suppose that the retraction of the palladium molecules takes place the moment the hydrogen is first ab- sorbed, instead of being deferred till the latter is expelled; for the righting of the particles of the palladium wire (which are in a state of excessive tension in the direction of the length of the wire) may as well take place in the act of the absorption of the hydrogen as in the ex- pulsion of that element. It may indeed appear most probable in the abstract that the mobility of the palladium particle is determined by the first entrance of the hydrogen. The hydrogenium will then be assumed to occupy double the space previously allotted to it, and the density of the metal will be reduced to one half of the former estimate. In the experiment referred to the volume of hydrogenium in the alloy will rise from 4°68 per cent. to 9°36 per cent., and the density of hydro- genium will fall from 1°708 to 0°854, according to the new calculation. In a series of four observations upon the same wire, previously recorded, the whole retractions rather exceeded the whole elongations, the first amounting to 23°99 millims., and the last to 21°38 millims. Their united amount would justify a still greater reduction in the density of hydrogenium, namely to 0°8051. The first experiment, however, in hydrogenating any palladium wire appears to be the most uniform in its results. The expulsion of the hy- drogen afterwards by heat always injures the structure of the wire more or less, and probably affects the regularity of the expansion afterwards in different directions. The equality of the expansion and the retraction in a first experiment appears also to be a matter of certainty. This is a curious molecular fact of which we are unable as yet to see the full import. In illustration, another experiment upon a pure palladium wire 1869. | Mr. T. Graham on Hydrogenium. 501 may be detailed. This wire, which was new, took up a full charge of hydrogen, namely 956°3 volumes, and increased in length from 609°585 to 619-354 millims. The elongation was therefore 9°769 millims. With the expulsion of the hydrogen afterwards, the wire was permanently shortened to 600°115 millims. It thus fell 9-470 millims. below its normal or first length. The elongation and retraction are here within 0°3 millim. of equality. The two changes taken together amount to 19°239 millims., and their sum represents the increase of the wire in length due to the addition of hydrogenium. It represents a linear expansion of 3°205 on 100, with a cubic expansion of 9°827 on 100. The compositon of the wire comes to be represented as being, In volume. 2 Pia ee 100°000 or 90°895 UI CHAIN 5 Soin ae ene scene 9°827 or 9:105 109°827 or 100:000 The specific gravity of the palladium was 12°3, the weight of the wire 1°554 grm., and its volume 0°126 cub. centim. The occluded hydrogen measured 120°5 cub. centims. The weight of the same would be 0°0108 grm., and the volume of the hydrogenium 0°012382 cub. centim. (100: 9°827 :: 0°126: 0°01238). The density of the hydrogenium is therefore 0:0108 0°01238 This is a near approach to the preceding result, 0-854. Calculated on the old method, the last experiment would give a density of 1-708. It was incidentally observed on a former occasion that palladium alloyed with silver continues to occlude hydrogen. This property is now found to belong generally to palladium alloys, when the second metal does not much exceed one half of the mixture. These alloys are all enlarged in dimensions when they acquire hydrogenium. It was interesting to per- ceive that the expansion was greater than happens to pure palladium (about twice as much), and that, on afterwards expelling the hydrogen by heat, the fixed alloy returned to its origmal length without any further © shortening of the wire. The embarrassing retraction of the palladium has, in fact, disappeared. The fusion of the alloys employed was kindly effected for me by Messrs. Matthey and Sellon, when the proportion of palladium was con- siderable, by the instrumentality of M. Deville’s gas-furnace, in which coal-gas is burned with pure oxygen—or by means of a coke-furnace when the metals yielded to a moderate temperature. The alloy was always drawn out into wire if possible, but if not sufficiently ductile, it was extended by rolling into the form of a thi ribbon. The elongation caused by the addition of hydrogenium was ascertained by measuring the wire or ribbon stretched over a graduated scale, as in the former ex- periments. , =0°872. 502 Mr. T. Graham on Hydrogenium. — [June 17, 1. Palladium, Platinum, and Hydrogenium.—Palladium was fused with platinum, a metal of its own class, and gave an alloy consisting, according to analysis, of 76°03 parts of the former and 23:97 parts of the latter. This alloy was very malleable and ductile ; its specific gravity was 12°64. Like pure palladium, it absorbed hydrogen, evolved on its surface in the acid fluid of the galvanometer, with great avidity. A wire 601°845 millims. in length (23°69 inches) was increased to 618°288 millims., on occluding 701°9 volumes of hydrogen gas measured at 0° C. and 0°76 barom. This is a linear elongation of 16°443 millims. (0°6472 inch), or 2°732 on a length of 100. It corresponds with a cubic expansion of 8°423 volumes on 100 volumes; and the product may be represented— In volume. ‘Fixed metals. os... 6.2: 0ecs.2 100°000 ory 92-225 Hiydrogenium Woe. see eee 8°423 or = =7°775 108°423 or 100-000 The elements for the calculation of the density of hydrogenium are the following, the assumption being made as formerly, that the metals are united without condensation :— Original weight of the wire 4°722 grms. Original volume of the wire 0°373 cub. centim. Volume of the hydrogen extracted 2645 cub. centims. Weight of the hydrogen extracted, by calculation, 0:0237 grm. The volume of the hydrogenium will be to the volume of the wire (0°373 cub. centim.) as 100 is to 8°-423—that is, 0°03141 cub. centim. Finally, dividing the weight of the hydrogenium by its bulk, 0°0237 by 0:03141, the density of hydrogenium is found to be 0°7545. On expelling all hydrogen from the wire at a red heat, the latter returned to its first dimensions as exactly as could be measured. ‘The platinum present appears to sustain the palladium, so that no retraction of that metal is allowed to take place. This alloy therefore displays the true - increase of volume following the acquisition of hydrogenium, without the singular complication of the retraction of the fixed metal. It now ap- pears clear that the retraction of pure palladium must occur on the first entrance of hydrogen into the metal. The elongation of the wire due to the hydrogenium is negatived thereby to the extent of about one half, and the apparent bulk of the hydrogenium is reduced to the same extent. Hydrogenium came in consequence to be represented of double its true density. The compound alloy returns to its original density (12°64) upon the expulsion of the hydrogen, showing that hydrogen leaves without pro- ducing porosity in the metal. No absorptive power for vapours, like that of charcoal, was acquired. A wire of the present alloy, and another of pure palladium, were charged 1869. ] Mr, T. Graham on Hydrogenium. 503 with hydrogen, and the diameters of both measured by a micrometer. The wire of alloy increased sensibly more in thickness than the pure palladium, about twice as much; the reason is, that the latter while expanding re-- tracts in length at the same time. The expansion of both wires may be familiarly compared to the enlargement of the body of a leech on absorbing blood. The enlargement is uniform in all dimensions with the palladium- platinum alloy ; the leech becomes larger, but remains symmetrical, But the retraction in the pure palladium wire has its analogy in a muscular con- traction of the leech, by which its body becomes shorter but thicker in a corresponding measure. The same wire of palladium and platinum charged a second time with hydrogen, underwent an increase in length from 601°845 to 618:2, or sensibly the same as before. The gas measured 258-0 cub. centims., or © 619°6 times the volume of the wire. The product may be represented as consisting of By volume. SEE toes 5 popes veces 9, Qa ale RMMOMETOUIAD Ce aos were cn abet 22ees 7°728 160-009 The density of hydrogenium deducible from this experiment is 0°7401. The mean of the two experiments is 0°7473. 2. Palladium, Gold, and Hydrogenium.—Palladium fused with gold formed a malleable alloy, consisting of 75°21 parts of the former and 24°79 parts of the latter, of a white colour, which could be drawn into wire. Its specific gravity was 13:1. Of this wire 601°85 millims. occluded 464-2 volumes of hydrogen with an increase in length of 11°5 millims. This is a linear elongation of 1°91 on 100, and a cubic expansion of 5°84 on 100. The resulting composition was‘therefore as follows :— In volume. Alloy of palladium and gold .... 100 “or 94°48 RIE RONTUMD oo = ges es 8 e's 5°84 or 5°52 105°84 100-00 The weight of the wire was 5°334 grms. The volume of the wire was 0°4071 cub. centim. The volume of hydrogen extracted, 189-0 cub. centims. The weight of the hydrogen, 0°01693 grm. The volume of the hydrogenium, 0°02378 cub. centim. Consequently the density of the hydrogenium is 0°711. The wire returned to its original length after the extraction of the hy- drogen, and there was no retraction. The results of a second experiment on the same wire were almost iden- tical with the preceding. The elongation on 601°85 millims, of wire was 11°45 millims., with the occlusion of 463°7 volumes of hydrogen, This is a linear expansion of VOL. XVII, 2P 504 Mr. T. Graham on Hydrogenum. ——[June 17, 1:902 on 100, and a eubic expansion of 5°81 on 100. The volume of hydrogen gas extracted was 188°8 cub. centims., of which the weight is 0:016916 grm. The volume of the hydrogenium was 0°02365 cub. centim., that of the palladium-gold alloy being 0°4071 cub. centim. Hence the density of the hydrogenium is 0°715. In a third experiment made on a shorter length of the same wire, namely 241°2 millims., the amount of gas occluded was very similar, namely 468 volumes, and was not increased by protracting the exposure of the wire for the long period of twenty hours. ‘There can be little doubt, then, of the uniformity of the hydrogenium combination, the volume of gas occluded in the three experiments being 464°2, 463°7, and 468 volumes. The linear _ expansion was 1°9 on 100 in the third experiment, and therefore similar also to the preceding experiments. The hydrogenium may be supposed to be in direct combination with the palladium only, as gold by itself shows no attraction for the former element. In the first experiment the hydrogenium is in the proportion of 0°3151 to 100 palladium and gold tegether. This gives 0°3939 hydrogenium to 190 palladium ; while a whole equivalent of hydrogenium is 0°939 to 100 pal- ladium*. The hydrogenium found is by calculation 0:4195 equivalent, or 1 hydrogenium to 2°383 equivalents palladium, which comes nearer to 2 equivalents of the former with 5 of the latter than to any other proportion. To ascertain the smallest proportion of gold which prevents retraction, an alloy was made by fusing 7 parts of that metal with 93 parts of palla- dium, which had a eee) gravity of 13°05. The button was rolled into a thin strip and charged with hydrogen by the wet method. An occlusion of 585°44 volumes of gas took place, with a linear expansion of 1°7 on 100. , —_—_——— drawing. It is not easy fi iS. to convey the impression J ae this of a fleecy cloud such as - I saw. I looked at one or two others in the same way, and left off even- tually quite satisfied that with a suitable battery the whole of any promi- nence or eruption might be seen with comfort (either the red, or the orange, or the blue, or any other principal image being examined at will) by limiting the field of view, and with it the unnecessary diffuse light, to the actual dimensions of the object. The portion of a cloud-shape which is due to one element will thus be artificially separated from the form which is due to another, and the regions or strata to which the various elements are confined will become known with certainty *. t is unfortunately impossible for me to prosecute these researches any further. -I have neither the leisure nor the opportunity to devise and use suitable instruments except at rare intervals, for which such discoveries will not wait. Yours very truly, J. Herscuen, Lt. R.E. * As an instance of this kind, I may point to Captain Haig’s observations with the hand-spectroscope. As this instrument as x0 slit, his “ bands” mean the coloured re- petitions of the line of sierra or low clouds fringing the moon’s limb at the point, only that with so low a power, and amid the confusion of images, he did not recognize (ap- parently) the similarity of general outline of the differently coloured images. Hence the term “‘ bands,’ which has misled at least one reviewer into inferring a slit, and thereby immensely overrating the scope of these instruments. J. H. 1869.] _ Mr. H. C. Sorby on Jargonium. 511 VIII. “On Jargonium, a new Elementary Substance associated with Zirconium.” By H.C. Sorsy, F.R.S. &c. Received June 4, 1869. 7 . At the Soirée of the President of the Royal Society on March 6th, I exhibited various spectra, differimg so much from those characteristic of any known substance, that I considered myself warranted in concluding that they were evidence of a new element. Since this may be studied to the greatest advantage in the jargons of Ceylon, it appeared to me that, like as the name zirconium has been adopted for the principal constituent of zircons, so that of jargonium would be very suitable for this constituent of jargons. At the above-named Soirée I gave away a printed account of the objects I exhibited, and in this I said that the earth jargonia “is distin- guished from zirconia and all other known substances by the following very remarkable properties. The natural silicate is almost, if not quite colour- less, and yet it gives a spectrum which shows above a dozen narrow black lines, much more distinct than even those characteristic of salts of didymium. When melted with borax it gives a glassy bead, clear and colourless both hot and cold, and no trace of absorption-bands can be seen in the spec- trum; but if the borax bead be saturated at a high temperature, and flamed, so that it may be filled with crystals of borate of jargonia, the spectrum shows four distinct absorption-bands, unlike those due to any other known substances” *. I have since applied myself almost exclusively to this subject, hoping to have been able to communicate to the Royal Society a full account before the close of this session; but so much still remains to be done, that it is now impossible to give more than a brief outline of some of the more im- portant facts. The delay has not been occasioned by any difficulty in proving it to be a newsubstance, but because its properties are so unique and have so much interest in connexion with physics that it appeared de- sirable to carefully examine all other known elements, in order to ascer- tain whether any exhibit analogous phenomena. That jargonium is quite distinct from zirconium is proved not only by the spectra, but also by other facts. Both I and Mr. David Forbes have succeeded, by entirely different processes, in separating from jargons zirconia apparently quite free from jargonia, and jargonia nearly, if not quite, free from zirconia ; and, even if the separation be not perfect, it is, at all events, more than sufficient to prove that they are distinct. They are certainly closely alJied, and are deposited from borax blowpipe beads in microscopical crystals of the same general forms, quite unlike those characteristic of other known earths; but, beyond this, the difference is * For the further history of this subject see Professor Church’s papers, Intellectual Observer, 1866, vol. ix. p. 291, Chemical News, March 12 and 19, 1869, vol. xix. pp- 121 & 142, Atheneum, March 27; and also my own, Chemical News, vol. xix, p- 122, and Atheneum, April 3, 1869. 512 Mr. H.C. Sorby oa Jargonium. [June 17, as great as that between any other two closely related elements. Judging from Mr. D. Forbes’s analysis, kindly made at my request, and from a comparison of the spectra, the amount of jargonia in different jargons varies up to about 10 per cent. The entire or comparative absence from the zircons of Miask, Fredericksvarn, and various other localities, appears to explain some of the facts which led Svanberg* to conclude that zircons contain more than one earth. He was so far correct, but failed to esta- blish the existence of any substance with special chemical or physical pro- perties ; and if, as is probable, the Norwegian zircons, which, according to his views, contain such a notable quantity of this supposed new earth as to have led him to give it the name noria, were from Fredericksvarn, and if the Siberian were from Miask, his norium cannot be looked upon as equivalent to my jargonium, which is almost or quite absent from those ZIXCONS. The most remarkable peculiarity of jargonium is that its compounds may exist in no less than three different crystalline states, giving spectra which differ from one another as much as those of any three totally dif- ferent elements which give the most striking and characteristic spectra. Several substances can be obtained in two physical states, giving different spectra: but usually only one of them is crystalline; the other is the vitreous or colloid condition. Crystalline minerals, coloured by oxide of chromium, do indeed show two types of spectra, but I am not aware that they ever both occur in the same mineral. In the case of jargonium, however, the three types of spectra are all met with in crystalline modi- fications of apparently the same compound. The most characteristic test for jargonia is the spectrum of the borax blowpipe beads, seen with the spectrum-microscope, which enables us to de- tect it in zircons containing less than one per cent. As much of the earth or natural silicate as will completely dissolve should be melted in cireular loops of platinum wire, about 3 of an inch in diameter, with a mixture of borax and boric acid, and avery strong heat kept up till crystals begin to be deposited, owing to loss of the solvent by volatilization. On removing the beads from the flame they remain clear, and show a few acicular crystals, but give no absorption-hands in the spectrum. On reheating to a temperature just below very dull redness, they turn white, and so very opaque that no ordinary light will pass through them. When, however, a small and very bright image of the sun is formed in their centre, by means of an almost hemispherical condensing lens of $ inch diameter, and a cap placed over the object-glass, with a round hole less than the beads nearly in the focus, so as to prevent the passage of extraneous light, they are seen to be illu- minated by transmitted light of about the same brilliancy as that of a bright cloud, so as to give an excellent spectrum, without being at all daz- zling. In the case of beads containing jargonia, the spectrum differs com- pletely according to the temperature at which the included crystals have * Poge. Ann. 1845, vol. Ixy. p. 317. 1869. ] Mr. H. C. Sorby on Jargonium. 5138 been deposited. As already mentioned, a clear glassy bead gives no ab- sorption-bands ; and when the crystals are deposited at as low a tempera- ture as possible, much below dull redness, and only just high enough to soften the borax, there may be scarcely any trace of bands ; but, if a clear bead be quickly raised to a temperature very little below dull redness, it suddenly becomes opaque, and shows a spectrum with a number of narrow black absorption-bands (fig. 1). The most distinct is in the green, then one in the red, and one in the blue; and there are three fainter, one in the orange, and two in the green. On raising the temperature to bright redness all these bands vanish, and four others appear, none of which coin- cides with the former (fig. 2). Three are situated in the red and orange, and Red end. Blue end. one in the green, so as to give a spectrum of very different general cha- yacter. In this state the bead is a pale straw-colour, and not, as before, almost white. In the case of nearly pure jargonia, the bead should not be more than 5: of an inch thick, or else it would be too opaque. Pure zirconia treated in the same manner gives no bands whatever in any condition ; the bead is quite white, and sufficiently transparent when two or three times as thick as just named. It might be thought that the three different spectra thus briefly de- scribed were due to different compounds, if it were not that there is a similar series in the case of the natural crystalline silicate. Some of the jargons of Ceylon have a specific gravity very little inferior to that of pure zircons (4°70), and contain very little jargonia; but those of low gravity (4:20 or thereabouts) contain perhaps nearly 10 per cent., in a form which gives scarcely any trace of absorption-bands. On keeping such a specimen at a bright red heat for some time, the specific gravity increases from about 4°20 to 4°60. Judging from the imperfect data now known, this indicates that the volume of the silicate of jargonia is reduced to about one-half; the hardness becomes somewhat greater, and, when exa- mined with the spectrum-microscope, the spectrum is found to be entirely changed. Instead of a mere trace of bands, a spectrum is seen with thirteen narrow black lines and a broader band, more remarkable than that of any clear transparent substance with which I am acquainted. No such changes occur in the case of zircons free from jargonia, like those from Miask, Siberia; there is no increase in the specific gravity, and no ab- sorption-bands are developed, and, as a general rule, the increase varies 514 Mr. H. C. Sorby on Jargonium. | [June 17, simply and directly as the amount of jargonia which passes from one state into the other. Zircons in their natural condition from various localities contain a very variable absolute and relative amount of these two modifica- tions of jargonia, and there seems good reason to believe that this differ- ence in physical state may materially assist us in determining the temperature at which certain rocks have been formed. I have also met with one example of the third form of spectrum. A brown-red zircon from Ceylon was so dark in one part as to be quite opaque, and therefore I do not know what the original spectrum might have been. On heating it to redness, the whole became a clear pale green; and, without examina- tion with the spectroscope, no one would have suspected any difference be- tween the different portions. That which was originally a pale brown-red then showed the same spectrum as that usually developed by heat, whilst that which was originally very dark showed an entirely different spectrum, corresponding exactly with that of the borate deposited in blowpipe beads at a medium temperature. It also corresponds in general character, but not in detail, with that of the biue spinels from Ceylon, which must, I think, contain a small quantity of jargonia. That part of the zircon which gave this spectrum appears to have had the same remarkably low specific gravity of about 4:0, both before and after ignition, as though the volume of the silicate of jargonia in this state were even greater than in that which gives no bands. All these spectra, due to jargonium, are ofa very marked character, and quite unlike those due to any other element in similar conditions. The alteration produced in jargons by heat is, to some slight extent, analogous to what occurs on heating carbonate of lime in the state of arragonite ; but, instead of changing into an opaque mass of minute crys- tals of another form of the carbonate (calcite), which has a less specific gravity, is less hard, and does not give a different spectrum, they are still as simple and transparent crystals as at first; the specific gravity and hardness are increased, and the spectrum is entirely changed. Iodide of mercury is an excellent illustration of an alteration in the spectrum, due to a change in crystalline form produced by heat; but still the facts differ most materially from those described, and there are only two modi- fications—the yellow and the scarlet. The existence of three erystalline modifications is similar to what occurs in titanic acid. Anatase, Brookite, and rutile have distinct crystalline forms, but they do not differ much in specific gravity, and their spectra present no characteristic differences. On the whole, the different states of carbon (charcoal, graphite, and dia- mond) are perhaps the best illustration of the existence of three different conditions in the same substance, since they differ materially in specific gravity and optical characters, one being black, the other having a metallic lustre, and the third being transparent and colourless; but these are varia- tions of the element itself, and not, as in the case of jargonium, modifica- tions of its compounds. So far as I am aware, there is indeed no substance which shows strictly comparable facts. 1869. | Mr. J. P. Harrison on Solar Radiation. 515 There cannot then, I think, be any doubt whatever that jargonium is not only a new elementary substance, but is also one likely to throw much light on several important physical questions. By the time that the Society resumes its meetings, I trust that I shall be able to send a complete account of the whole of my investigations, including such facts connected with other substances as may serve to illustrate the very peculiar properties of this hitherto unrecognized element. Postscrirr. Received June 18, 1869. I here subjoin a brief account of the methods employed by Mr. David Forbes* and myself in separating zirconia and jargonia from one another. He separated apparently pure zirconia by means of strong hydrochloric acid, which dissolved the chloride of jargonium, but left chlo- ride of zirconium undissolved; and obtained the approximately pure jar- gonia by adding to the solution excess of ammonia, and then considerable excess of tartaric acid, which left most of the tartrate of jargonia insolu- ble, but dissclved what may turn out to be a mixture of zirconia and jar- gonia with a third substance, not yet sufficiently studied—perhaps Svan- berg’s noria. My own analysis was only qualitative. I fused powdered jargon with several times its weight of borax, which gave a perfectly clear glass, completely soluble in dilute hydrochloric acid. After separating the silica in the usual manner, a slight excess of ammonia was added to the hydrochloric-acid solution of the earths, and then some oxalic and hydro- chloric acids, which left undissolved apparently pure zirconia that had passed into an imperfectly soluble state. To the solution so much am- monia was added as to give a very copious precipitate, but yet to leave the solution with a very decided acid reaction. After removing the precipi- tate, which was chiefly oxalate of zirconia, almost or quite free from jar- gonia, excess of ammonia was added to the solution, and the washed precipitate digested in dilute hydrochloric acid, to remove peroxide of iron. The insoluble portion must have been approximately pure oxalate of jar- gonia, for it gave the characteristic spectra described below in remark- able perfection. Though this method succeeded far better than I antici- pated, I do not yet understand the exact conditions requisite to ensure success, and have been prevented by absence from home from making further experiments. ) IX. “Solar Radiation.” By J. Park Harrison, M.A. Com- municated by Prof. Stoxrs, Sec. R.S. Received June 12, 1869. _ In a communication which the author had the honour of making to the * Chemical News, June 11, 1869, vol. xix. p. 277. 516 Mr. J. P. Harrison on Solar Radiation. [June 17, Royal Society in 1867 *, it was shown, from observations of the black-bulb thermometer and Herschel’s actinometer, that maximum effects of solar radiation occur at Greenwich, on the average, some weeks after the summer solstice, and about two hours after mid-day, when the atmosphere would appear to be charged with a considerable amount of vapour. These results accord with the fact that the highest readings of the solar thermometer are met with in India in districts of great relative humidity +, the explanation of the phenomenon being, as the author ventured to sug- gest in the paper above alluded to, that an increase of insolation is pro- duced by radiation from cloud and visible vapour. During the two years which have elapsed since the spring of 1867, whenever the state of the sky and other circumstances permitted, special observations have been made for the purpose of ascertaining with greater certainty the nature of the relation between insolation and humidity. Before proceeding to state results, it will afford additional proof that a connexion between the phenomena really exists, if a passage in the appendix to a work by the late Principal of St. Andrews, until very recently overlooked, is quoted in support of the fact. Mr. Forbes, writing some years ago, employs much the same words that were used in the paper above referred to: —‘‘ Cloudy weather, if the sun be not itself greatly obscured, apparently increases the effect of solar radiation” 2. The action, however, does not appear to be confined to days on which there is visible cloud ; for even on cloudless days (so called) very high read- ings of solar radiation seem to be due to the presence of opalescent vapour, which can be easily detected if the hand or some other screen is held for a few minutes before the sun. Thus, on May 2, 1868, at 1° 30™, solar radiation appearing to be rela- tively intense, on raising a screen white glare was observed around the sun, and the tint of the sky, which had previously appeared a fair blue, was found, more especially in the south, to be very pale. But the most interesting result of this series of observations is the dis- covery that an apparent increase of solar radiation occurs as the sun enters a white cloud of sufficient tenuity to allow free passage for its rays. In October 1867, at 2°, whilst attentively watching a solar thermometer, a sudden rise was observed to take place, upon which, the sun being im- mediately screened, it was found that it had entered the bright border of a cumulus. On May 11, 1868, at 22" 40™, as a very light cloud approached the sun, which was shining in blue sky, the mercury rose 4°, and in 30 seconds 3° more as it entered the white cloud. On the same day, at 23”, the reading of the solar thermometer was 101°F. when the sun was in the midst of cirri, but it fell in 3 minutes 9° when * Proc. Roy. Soc., Feb. 1867. Tt Proc. Roy. Soc., March 1865. { Travels through the Alpsof Savoy, App. III. p. 417. 1869. | Mr, J. P. Harrison on Solar Radiation. 517 well free again; then rose 6° as light cloud again crossed it. The air was perfectly still. On May 15, 1868, the highest reading of the solar thermometer for the day occurred at 2" 17™, just as the sun entered the skirts of a cloud. On July 21, 1868, at 2", the maximum of the day (128° F.) was reached when the sun was shining in a patch of pale sky surrounded with white cumuli, some of which were within one or two diameters of its disk. To mention one more example amongst numerous others which might be cited ; on Aug. 3, 1868, at 0° 40", under an apparently clear sky, the solar thermometer registering 112°, and the temperature of shade 82°, in two minutes insolation increased to 125°, whilst the temperature of shade rose 0°3 only; on examining the sky in the neighbourhood of the sun, white cirri were detected crossing its disk. Light cloud and opalescent vapour having been thus found, when in the direction of the sun, to intensify the effects of solar radiation, a series of experiments was commenced with circular screens of various sizes, to dis- cover, if possible, the distance to which the effects of bright glare and light vapoury cloud extended round the sun. The observations were made when the sun’s altitude was between 30 and 50 degrees. All the screens were placed at a uniform distance of six inches from the bulb of a solar thermometer, 7 in. in diameter, coated with China ink, and laid on a small piece of dark oak about two inches by ten inches on grass. The bulb of the thermometer was not covered with an exhausted globe. The mean results of the experiments were as follows* :— 1. A screen 3 in. in diameter reduced the difference of the readings of the black-bulb thermometer and a thermometer in the shade, four yards distant, by one-third. 2. A screen 23 ins. in diameter reduced the difference by two-thirds. On reversing the experiment, converse results were obtained, e.g. The rays of the sun, after passing through a circular aperture 24 ins. in diameter in a 12-in. screen, were made to fall on the bulb of the solar thermometer, when the readings were found to equal in value those ob- tained when the instrument was entirely exposedt. And no difference was noticed when the black-bulb thermometer was screened from the rest of the sky by a double cover of mill-board placed tent-wise over it. * Similar results were obtained when the solar thermometer was laid upon short grass, in the afternoon, when the dew was off the ground. With the instrument freely suspended 6 in. above the grass, the readings showed a proportionate fall. +t In the above experiments, it is evident that the whole of the results were not due to direct radiation or reflection. Account must be taken of the greater or less distance of the heated surface of the ground, and of the hot air in contact with it, from the bulb of the solar thermometer. 518 Mr. J. P. Harrison on Solar Radiation. © [June 17. Results of an equally negative kind were obtained in the case of other experiments which were made with the object of detecting heat in the light reflected from sky and cloud not in the direction of the sun. A black-bulb thermometer, atter having been placed for some time in a dark room, was then exposed to the sky, near a large French window, facing S.E., the glass of which was clear, and had been carefully cleaned, without any rise being perceptible. The sun, at an altitude of about 40°, was shining brightly on white vapour and light cirro-cumuli*. Thermometers were also placed in the open air on the north side of the house, on a still day, exposed to half the sky when covered with bright white clouds; but the mercury stood at the same height as in a dark passage on the same side of the buildingy. The same apparent absence of any direct heating-power in the light re- flected from the sky generally was shown in this, as in the previous series of experiments when the solar thermometer was screened, excepting in the direction of the sun. As respects the momentary increase of insolation which occurs in connexion with bright vapour in the neighbourhood of the sun, further experiment is required for the purpose of ascertaining whether it is due to radiation or to reflection. Norr.—An opportunity occurred on the 7th of June of repeating the experiments with screens at altitudes of the sun exceeding 50°. The following results were obtained :— h m AtO O. BB. 110. Temp. of shade 73. Sky cloudless, but with a good deal (Exposed to the sun and sky.) | of white vapour, more especially about the sun. 0 4. B.B. 90. Temp. of shade 73. FF (Shaded from sun by a 2-in. screen. ) 0 30. B.B.104. Temp. of shade 73. Light ait, (Exposed to sun and sky.) 0 35. B.B. 94. Temp. of shade 73. Light air. (Shaded from sun by a 4-in. screen.) 1 0. B.B.108. Temp. of shade 74. Quite calm, (Exposed to sun and sky.) 1 5. B.B.109. Temp. of shade 74. Quite calm. (Exposed to sun through a 2-in. circular aperture in a 12-in. screen.) 115. B.B.108. Temp. of shade 74. Quite calm. (Exposed to sun and sky.) 118. B.B.106. Temp. of shade 74. Quite calm. (Exposed to sun through a 2-in. circular aperture in a 12-in. screen. 1 20. B.B.106. Temp. of shade 74. Quite calm. (Exposed to sun but screened from sky.) * Experiments were also tried with a 7-inch lens, without result. +t The thermometer exposed to the sky would probably have stood Jower than the one in the house if the sky had been perfectly clear. INDEX to VOL. XVII. ———S——_ ABEL (EF. A.), contributions to the history of explosive agents, 395. Acid, on hydrofluoric, 256. Acoustic figures of vibrating surfaces, notice of, 145. a (G. B.) on the diurnal and annual inequalities of terrestrial magnetism, as deduced from observations made at the Royal Observatory, Greenwich, from 1858 to 1863 ; being a continuation of a- communication on the diurnal in- equalities from 1841 to 1857, printed in the Philosophical Transactions, 1863. With a note on the luno-diurnal and other lunar inequalities, as deduced from observations extending from 1848 to 1863, 163. Allylic mustard-oil, action of water and hydrochloric acid on, 273 ; of sulphuric acid, 275. _Amylic alcohols, note on the separation of the isomeric, found by fermentation, 308. —— mustard-oil, 70. Animal electricity, researches in, 377. Anniversary Meeting, November 30, 1868, 133. Annual meeting for election of Fellows, June 3, 1869, 453. Aquamarina, on the structure of, 294. Arctic expedition, further particulars of the Swedish, 91, 129, 141. Ascension Island, results of magnetical observations made at, 397. Auditors, election of, 103. Australia (Central), scientific exploration of, 144. Ball (J.) admitted, 471. Bastian (H. C.) admitted, 103. Benzylic mustard-oil, 71. Beverly (C. J.), obituary notice of, Ixxxvii. Bigbsy (J. J.) admitted, 453. Bisulphide of phenyl, 64. Blanford (H. F.) on the origin of a cy- clone, 472. Blood-corpuscle, on the structure of the red, of oviparous vertebrata, 346. corpuscles, on the laws and principles concerned in the aggregation of, 429, YOL, XYII, Boilmg liquids, on the action of solid nuclei in berating vapour from, 240. Bombay, on the solar and lunar variations of magnetic declination at, 161. ——, observations of the absolute direc- tion and intensity of terrestrial mag- netism at, 426. observatory, magnetical and meteo- rological instruments for, 144. Breen (H.) on the corrections of Bouvard’s elements of Jupiter and Saturn (Paris, 1821), 344. Breitenbach meteorite, preliminary notice on the mineral constituents of the, 370. Brewster (Sir D.), obituary notice of, lxix. British meteorological observations, notice of, 135. Broughton (J.) on a certain excretion of carbonic acid by living plants, 408. Bruniquel, description of the cavern of, and its organic contents: Part II. Equine remains, 201. Brussels, dip observations at, 283. Campbell (Lieut.), report on the eclipse of the sun of August 18, 1868, 120. Candidates for election, list of, Mar. 4, 1869, 314. Candidates selected, list of, May 13, 1869, 419. Capello (Senhor) on the reappearance of some periods of declination disturbance at Lisbon during two, three, or several days, 238. Carbonic acid, on a certain excretion of, by living plants, 408. - Carpenter (W. B.), preliminary report of dredging operations in the seas to the north of the British Islands, carried on. in Her Majesty’s steam-vessel ‘ Light- ning,’ by Dr. Carpenter and Dr. Wy- ville Thomson, 168. and Brady (H. B.), description of Parkeria and Loftusia, two gigantic types of arenaceous foraminifera, 400. Catalogue of scientific papers, notice of publication of vol. u., 135. Cavern of Bruniquel, description of: Part 1{. Kquine remains, 201. Cayley (A,), note on his memoir “on the. 2Q 520 conditions for the existence of three equal roots, or of two pairs of equal roots, of a binary quartic or quintic,” 314. Cayley (A.), a memoir on the theory = reciprocal surfaces, 220. , 2memoir on cube surfaces, 221. Chambers (C.) on the solar and lunar variations of magnetic declination at Bombay: Part L., 60. 2 , observations of the absolute direc- tion and intensity of terrestrial magne- tism at Bombay, 426. on the uneliminated instrumental error in the observations of magnetic dip, 427. Chapman (E. T.) and Smith (M. H.), note on the separation of the isomeric amylic alcohols formed by fermentation, 308. Chemical reactions produced by light, on a new series of, 92. Church (A. W.), researches on turacine, an animal pigment containing copper, 436. Claudet (A. F. J.), obituary notice of, lxxxv Clock, on a new astronomical, 468. Clouds in the sun’s outer atmosphere, on, 39. , note on the formation and phene- mena of, 317. Codeia, on the action of hydrochloric acid on, 460. Compass errors, correction of essential, in iron-built ships, 411. Compounds, isomeric, with the- sulpho- cyanic ethers (III.), 269. Copley medal awarded to Sir Charles Wheatstone, 145. Council, list of, 128, 151. Crofton (M. W.) on the proof of the law of errors of observations, 406. Crookes (W.) on the measurement of the luminous intensity of light, 166, 358. , addendum to description of photo- meter, 369. on a new arrangement of binocular spectrum-microscope, 443. on some optical phenomena of opals, 448. Cubic surfaces, memoir on, 221. Cyclone, on the origin of a, 472. Daubeny (C. G. B.), obituary notice of, lxxiy. Pe Candolle (A.) elected foreign member, 407. Declination disturbance at Lisbon, on the reappearance of some periods of, 238. Deep sea, temperature of, 188. soundings, note on a self-registering thermometer adapted to, 482, INDEX. ae (C. E.) elected foreign member, 407. Diamonds, on the structure of, 291. Dip, determinations of, at some of the principal observatories in Europe, 280. —, magnetic, on the uneliminated in- pie error in the observations of, 427. Dupré (A.) and Page (F. J. M.) on the specific heat and other physical pro- perties of aqueous mixtures and solu- tions, 333. Dredging expedition in North Atlantic, notice of, 140. ; preliminary report on, 168 ; letters concerning, 197. Eclipse of the sun, 1851, Mr. Babbage’s note on, 133. , Aug. 18, 1868, spectroscopic obser- vations of, 74; observations of, along the coast of Borneo, 81; Lieut. Her- schel’s report on, 104; Lieut. Camp- bell’s report on, 120; Captain Perry’s observations of, 125 ; aid by Indian go- vernment towards observations of, 124 ; Capt. Rennoldson’s observations of, 125; Capt. Murray’s observations of, 127; Capt. King’s observations of, 127 ; notice of, 137. Elagin (Lieut. ), determinations of the dip at some of the principal observatories in Europe by the use of an instrument borrowed from the Kew Observatory, 280. Electric current, measurement of Huss of, 146. light, prismatic analysis of, 146. telegraph, instruments for ‘the, 146. Electrical phenomena of the nerves, 378. Electrotonus, on, 386. Ellery (R. J.), account of the building in progress of erection at Melbourne for the great telescope, 328. Emerald, on the structure of, 294. Equal roots, note on the memoir on the conditions for the existence of three, &e. 3 314. Equines, on fossil teeth of, from Central and South America, 267. Errors of obser vations, on the proof of the law of, 406. Ethylic ‘alcohol and water, specific heat of, 333; boiling-points of, 333; capil- lary attraction, 334; rate of expansion and compressibility, 338. mustard-oil, homologues and ana- logues of, 67, 69; action of hydrogen on, 269; of water and hydrochloric acid, 272; of sulphuric acid, 274; of nitric acid, 276. Explosive agents, contributions to the history of, 395, INDEX. Faraday (M.), obituary notice of, i.* Fellows deceased, list of, 133. elected, list of, 134, 453. » number of, 154. Ferrers (N. M.), note on Prof. Sylvester’s representation of the motion of a free rigid body by that ofa material ellipsoid rolling on a rough plane, 471. Financial statement, 152. Foreign members elected:—A. De Can- - dolle, C. E. Delaunay, L. Pasteur, 407. Fossil flora of North Greenland, contri- butions to the, 329. plants from North Greenland, notice of, 142. teeth of equines from Central and South America, on, 267. Foraminifera, description of two gigantic types of arenaceous, 400. Foster (G. C.) admitted, 453. Fowl, common, on the structure and de- velopment of the skull of the, 277. Fracture, on the, of brittle and viscous solids by shearing, 312. France, magnetic survey of the west of, 486 Frankland (E.) and Lockyer (J. N.), pre- - liminary note of researches on gaseous spectra in relation to the physical con- stitution of the sun, 288. , researches on gaseous spectra in relation to the physical constitution of the sun, stars, and nebule (I1.), 453. Free rigid body, note on Prof. Sylvester’s representation of the motion of a, 471. Foucault (J. B. L.), obituary notice of, Garrod (A. H.) on some of the minor fluctuations in the temperature of the _ human body when at rest, and their cause, 419. Gaseous spectra, researches on, in relation to the physical constitution of the sun, stars, and nebule, 453. Gastric juice, on the source of free hydro- chloriec acid in the, 391. Gems, on fluid cavities in, 297. Glaciers, on the mechanical possibility of - thedescent of, by their weight only, 202. Glenorchy sailing-ship, on the causes of the loss of the, 408. Gore (G.) on hydrofluoric acid, 256. on a momentary molecular change in iron wire, 269. on the development of electric cur- rents by magnetism and heat, 265. Graham (T.) on the relation of hydrogen to palladium, 212. , additional observations on hydro- -. genium, 500. Granites of Cornwall and Devonshire, 527 comparison of, with those of Leinster and Mourne, 209. Greenland, North, description of the plants collected by E. Whymper, 329. - Greenwich, dip observations at, 283. Guthrie (F.) on the thermal resistance of liquids, 234. Haidinger (W. Ritter von) on the phe- nomena of light, heat, and sound accom- panying the fall of meteorites, 155. Haig (Capt. C. T.), account of spectro- scopic observations of the eclipse of the sun, August 18, 1868, in a letter ad- dressed to the President of the Royal Society, 74, 103. Harcourt (A. G. V.) admitted, 103. Harrison (J. P.), solar radiation, 515. Haughton (Rev. S.), notes of a compa- rison of the granites of Cornwall and Devonshire with those of Leinster and Mourne, 209. Heat, on the radiation of, from the moon, 436. , Specific, of aqueous mixtures and solutions, 333. of the stars, note on, 309. and magnetism, on the development of electric currents by, 265. Hedgehog, note on the blood-vessel system of the retina of the, 357. Heer (O.), contributions to the fossil flora of North Greenland, being a descrip- tion of the plants collected by Mr. Ed- ward Whymper during the summer of 1867, 329. Hennessy (J. Pope), account of observa- tions of the total eclipse of the sun, made August 18, 1868, along the coast of Borneo, in a letter addressed to H.M. Secretary of State for Foreign Affairs, 81, 103. ; Herschel (Lieut. J.), second list of nebul and clusters observed at Bangalore with the Royal Society’s spectroscope ; pre- ceded by a letter to Professor G. G. Stokes, 58, 103. —— on the lightning spectrum, 61, 103. , account of the solar eclipse of 1868, as seen at Jamkandi, 104. —— , additional observations of southern nebulz, 303. , spectroscopic observations of the sun (continued), 506. History of explosive agents, contribution to the, 395. Hofmann (A. W.), compounds isomeric with the sulphocyanic ethers: II. Ho- mologues and analogues of ethylic mustard-oil, 67, 103; III. Transfor- mations of ethylic mustard-oil and sul- phocyanide of ethyl, 269. Horsford (E. N.) on the source of free 522 hydrochloric acid in the gastric fuice, oul. Houghton (Lord) elected, 155 ; admitted, 291. Huggins (W.), note on a method of view- ing the solar prominences without an eclipse, 302. ——, note on the heat of the stars, 309. Hulke (J. W.), note on the blood-vessel- system of the retina of the hedgehog, being a fourth contribution to the ana- tomy of the retina, 357. Human body, on the temperature of, in health, 287. ——-—, on some of the minor fluctuations in the temperature of the, when at rest, and their cause, 419. Hydride of propyl, on the derivatives of, 372 Hydriodie acid, action of light on, 101. Hydrobromie acid, action of light on, 99. Hydrochloric acid, action of light on, 101. ——, on the source of free, in the gastric juice, 391. ——, action of, on morphia, 455; on co- deia, 460. Hydrofluoric acid, on, 256; anhydrous, 256; aqueous, 259. Hydrogen, on the relation of, to palladium, 212. Hydrogenium, characteristics of, 220. ——, additional observations on, 500; density of, 506. Todide of allyl, action of light on, 98. of isopropyl, action of light on, 98. Iron wire, on a momentary molecular change in, 260. Janssen (M.) on the solar protuberances, 276. Jargonium, a new elementary substance associated with zirconium, 511; spec- tra of, 512. Jupiter, on the corrections.of Bouyard’s elements of, 344. Kaleidophone, notice of, 145. Kew magnetic curves, preliminary inves- tigation in the laws of the peaks and hollows, 462. Kew, comparison with Stonyhurst of cer- tain curves of the declination magneto- graphs, 236. , dip observations at, 283. Key (A. C.) admitted, 103. King (H. W.), observations of the total solar eclipse of August 18, 1868, 127. Lama, on remains of a large extinct, from quaternary deposits in the valley of Mexico, 405. Light, action of, on nitrite of amyl, 94; INDEX, on iodide of allyl, 98; on iodide of iso- propyl, 98; on hydrobromie acid, 99 ; on hydrochloric acid, 101; on hy- driodic acid, 101. Light, on a new series of chemical reac- tions produced by, 92. , on the measurement of the lumi- nous intensity of, 166, 358. , on the polarization of, by cloudy matter generally, 223. , heat, and sound, phenomena of, ac- companying fall of meteorites, 155. Lightning spectrum, on the, 61. Liquids, on the thermal resistance of, 234. Lisbon, on the reappearance of some periods of declination disturbance at, 238. Lockyer (J. N.), notice of an observation of the spectrum of a solar prominence, 91, 104. , Supplementary note on a spectrum of a solar prominence, 128. ; Spectroscopic observations of the sun: No. II., 128, 131; No. III., 350 ; No. IV., 415. admitted, 4:71. Loewy (B.) on the behaviour of thermo- meters in a vacuum, 319. Loftusia, an arenaceous foraminifer, de- scription of, 400.. Luno-diurnal and other lunar inequalities of terrestrial magnetism, 163. Luteine, results of researches on, 253. M‘Clean (J. R.) admitted, 453. Macneill (Sir J.) readmitted, 252. Macrauchenia patachonica, on the molar teeth of, 454. Magnetic curves, on the laws regulating the peaks and hollows exhibited in, 462. declination, on the solar and Iunar variations of, at Bombay, 161. -——— dip, on the uneliminated instru- mental error in the observations of, 427. survey of south polar regions, com- pletion of reduction of, 143. survey of the west of France, 486. Magnetical observations made at Ascen- sion Island, 397. Maenetism, terrestrial, on the diurnal and annual inequalities of, at Greenwich, 1858 to 18638, 163; luno-diurnal and other linar inequalities of, 164. and heat, on the development of electric currents by, 265. Magnetographs, results of a preliminary comparison of certain curves of the Kew and Stonyhurst declination, 236. Maskelyne (N. 8.), preliminary notice on the mineral constituents of the Brei- tenbach meteorite, 370. ° INDEX, Matthiessen (A.), researches into the chemical constitution of narcotine, and of its products of decomposition: Part IIT., 337 ; Part IV., 340. and Wright (C. R. A.), researches into the chemical constitution of the opium bases: Part I. On the action of hydrochloric acid on morphia, 455 ; IT. On the action of hydrochloric acid on ~ codeia, 460. Melbourne telescope, notice of the, 140. Meteorite, preliminary notice on the mineral constituents of the Breiten- bach, 370. Meteorites, on the phenomena of light, heat, and sound accompanying the fall of, 155. Meteorological department of Board of Trade, notice of reorganization of, 135. Methylic mustard-oil, 70. Microscope, binocular spectrum, on a new arrangement of, 443. Miller (W. A.), note on a self- -registering thermometer adapted to deep-sea soundings, 482. Mivart (St. G.) admitted, 453, Moon, on the radiation of heat from, 436. Morphia, on the action of hydrochloric acid on, 455. Moseley (Rev. H.) on the mechanical possibility of the descent of glaciers by their weight only, 202. Motor phenomena ascribed to the action of galvanic currents, 380. Munich, dip observations at, 284. Murray (Capt. 8.), observations of the total solar eclipse of August 18, 1868, 127. Mustard-oil, ethylic, 69; methylic, 70; amylic, 70; tolylic,70; benzylic, 71. , , transformations of, and sul- phocyanide of ethyl, 269. Narcotine, researches into the chemical constitution of: III., 337; IV., 340; action of hydriodic acid on, 337; of hydrochloric acid, 338; action of water on, 340. Nebule, southern, additional observations of, 303. and clusters observed at Bangalore, second list of, 58. Nitrite of amyl, action of sunlight on, 94; production of skyblue by decomposi- tion of, 97. Nordenskiéld (A. H.), further particulars of the Swedish arctic expedition, in a letter addressed to the President, 91, 104, , account of explorations by the Swedish arctic expedition at the close of the season 1868, 129. Norris (R.) on the laws and principles 523. concerned in the aggregation of blood- corpuscles both within and without the vessels, 429. North Greenland fossil plants, notice of, 142; description of, 329. Nuclei, on the action of solid, im liberating vapour from boiling liquids, 240. Obituary notices of deceased Fellows :— Michael Faraday, i. Sir David Brewster, lxix. Charles Giles Bridle Daubeny, Ixxiv. Julius Phicker, Ixxxi. Jean Bernard Léon Foucault, Ixxxii. Antoine Frangois Jean Claudet, lxxxy. Charles James Beverly, Ixxxvii. Ocean temperature, observations of, 136. Opals, on some optical phenomena of, 448, Opium bases, researches into the che- mical constitution of: I. 455; IL, 460. Organo-metallic bodies, on a new class of, containing sodium, 286. Oviparous vertebrata, on the structure of the red blood-corpuscle of, 346. Owen (R.), description of the cavern of Bruniquel and its organic contents: Part II. Equine remains, 201. , on fossil teeth of equines from Cen- tral and Southern America, referable to Equus conversidens, Equus tau, and Equus arcidens, 267. , on the molar teeth, lower jaw, of Macrauchenia patachonca, Ow., 454. , on remains of a large extinct lama (Palauchenia magna, Ow.) from qua- ternary deposits in the Valley of Mex- ico, 408. Palauchenia magna, a large extinct lama, on remains of, 405. Palladium, on the relation of hydrogen to, 212. , loss of occluding power of, in alloys, 504. , platinum and hydrogenium, 502; gold and hydrogenium, 503; silver and hydrogenium, 504; nickel and hydro- genium, 509. Paris, dip observations at, 285. Parker (W.K.) on the structure and deve- lopment of the skull of the common fowl (Gallus domesticus), 277. Parkeria, an arenaceous foraminifer, de- scription of, 400. Pasteur (L.) elected foreign member, 40. Pendulum governor for uniform motion, on a, 468. observations, account of experiments for determining the true vacuum- and temperature-corrections to, 488. Perrins (Capt, C. G.), observations of the 524 total solar eclipse of August 18, 1868, 125. Perry (Rev. 8. J.), magnetic survey of the west of France, 486. Phenyl-mercaptan, 62. Phenyl-mercaptide of lead, decomposi- tion of, 64. Phenylene sulphide, 65. —, sulphobromide of, 65. _ Phenyl-hyposulphurous acid, 66. Photometer, description, 367, 369. Photosphere and subjacent parts, on the, 34. Physical constitution of the sun and stars, 1. Plants, on a certain excretion of carbonic acid by living, 408. Pliicker (J.), obituary notice of, lxxxi. Polar clock, notice of, 145. Propane, on the derivatives of, 372. Pseudoscope, notice of, 145. Radcliffe (C. B.), researches in animal _ electricity, 377. Reciprocal surfaces, memoir on the theory of, 220. Rennoldson (Capt. D.), observations of the total solar eclipse of Aug. 18, 1868, 125. Researches conducted for the medical de- partment of the Privy Council at the Pathological Laboratory of St. Thomas’s Hospital, 253. Retina, a fourth contribution to the ana- tomy of the, 357. Reynolds (J. R.) admitted, 453. Ringer (S.) and Stuart (A. P.) on the temperature of the human body in health, 287. Robinson (Sir 8.) admitted, 471. Robinson (T. R.), appendix to the de- scription of the great Melbourne tele- scope, 315. Rokeby (Lieut.), results of magnetical ~ observations made at Ascension Island, latitude 7° 55’ 20" south, longitude 14° 25' 30" west, from July 1863 to March 1866, 397. Rosse (Harl of) on the radiation of heat _ from the moon, 436. Royal medal awarded to Rev. G. Salmon, 147; to Mr. A. R. Wallace, 148. Rubies, on the structure of, 291. Rumford medal awarded to Dr. B. Stew- | art, 149. Salisbury (Marquis of) elected, 252; ad- mitted, 291. Salmon (Rev. G.), Royal medal awarded to, 147 Sapphires, on the structure of, 291. Saturn, on the corrections of Bouvard’s elements of, 345. Savory (W.S.) on the structure of the INDEX. red blood-corpuscle of oviparous vertes brata, 346. ; Schorlemmer (C.) on the derivatives of propane (hydride of propyl), 372. Saal of a, through compass errors, 415. Sidgreaves (Rev. W.) and Stewart (B.), results of a preliminary comparison of certain curves of the Kew and Stony- hurst declination magnetographs, 236. Sifted air, behaviour of, in a vacuum, 229. Skull of the common fowl, on the struc- ture and development of the, 277. Sky, on the blue colour of the, 223. Skylight, on the polarization of, 223. Smith (A.) on the causes of the loss of the iron-built sailing-ship ‘ Glenorchy,’ 408. ; Sodium, on a new class of organo-metallic bodies containing, 286. Solar prominences, observations of the spectrum of, 91; supplementary note on, 128. , cyclonic action in, 417. , on a method of viewing the, without an eclipse, 302. protuberances, on the, 276. radiation, 515. Solids, on the fracture of brittle and vis- cous, by shearing, 312. Solitary stars, of, 47. Solly (E.) readmitted, 252. Sorby (H. C.) on jargonium, a new ele- mentary substance associated with zir- conium, 511. —— and Butler (P. J.) on the structure of rubies, sapphires, diamonds, and some other minerals, 291. Soundings, deep-sea, 179. South polar regions, completion of reduc- tion of magnetic survey of, 143. Southern nebule, additional observations of, 303. Specific heat of aqueous mixtures and so- lutions, 333. Spectra of yellow organic substances con- tained in animals and plants, results of researches on, 253. , gaseous, preliminary note of re- searches on, in relation to the physical constitution of the sun, 288. ; , researches on, in relation to the physical constitution of the sun, stars, and nebule. : Spectroscopic observations of the sun: No. TI., 128, 131; No. IIL, 350; No. IV., 415, 506. Spectroscopic observations of eclipse of the sun, 74. Spectrum, lightning, on the, 61. of a solar prominence, 91; supple- mentary note on, 128. INDEX. Spectrum-microscope, on a new arrange- ~ ment of binocular, 443. Spinel, on the structure of, 294. Sponges, vitreous, from the North Atlantic, 195. Stars, note on the heat of, 309. , of multiple systems of, 51. , of solitary, 47. , physical constitution of the, 1. Stenhouse (J.), products of the destruc- tive distillation of the sulphobenzo- lates (No. II.), 62, 103. Stereoscope, notice of, 145. Stewart (B.), a preliminary investigation into the laws regulating the peaks and hollows, as exhibited in the Kew mag- netic curves for the first two years of their production, 462. , remarks on Senhor Capello’s curves of declination disturbance, 239. , Rumford medal awarded to, 149. and Loewy (B.), an account of ex- periments made at the Kew Observa- tory for determining the true vacuum- and temperature-corrections to pendu- lum observations, 488. Stokes (G. G.), note on Governor Hen- nessey's account of the eclipse of the sun, 88. Stoney (G. J.) on the physical constitution of the sun and stars, 1, 108. Stonyhurst, comparison with Kew of cer- tain curves of the declination magneto- graphs, 236. Sulphobenzolates, products of the destruc- tive distillation of (No. II.), 62. Sulphobromide of phenylene, 65. Sulphocyanic ethers, compounds isomeric with (II.), 67. Sulphocyanide of ethyl, transformations of, and ethylic mustard-oil, 269. , action of water and hydrochloric acid on, 273. , action of sulphuric acid on, 274. Sun, account of spectroscopic observa- tions of the eclipse of August 18,1868,74. , eclipse of, observations of, 104, 120, 124, 125, 127; of 1851, Mr. Babbage’s note on, 133; notice of, 187. , of the distribution and periodicity of the spots in the, 42. , outer atmosphere of the, 17; of clouds in the, 39. , physical constitution of the, 1. , preliminary note of vesearches on gaseous spectra in relation to the phy- sical constitution of the, 288. , Spectroscopic observations of: No. i, 128, 131; No. III., 350; No. IV., 415, 506. Swedish arctic expedition, further parti- culars of, 91, 129, 141. 525 Telegraphic weather-signals, 137. Telescope, great Melbourne, appendix to the description of, 315. » great, account of the building ~ in progress of erection at Melbourne for the, 328. Temperature, on the, of the human body in health, 287. , on the effect of changes of, on the specific inductive capacity of dielectrics, 470. — of the human body when at rest, on some of the minor fluctuations in the, and their cause, 419. Terrestrial magnetism, suggestion con- cerning a decennial period in, 14/4. , on the diurnal and annual inequa- lities of, at Greenwich, 1858 to 1863, 163. , observations of the absolute di- rection and intensity of, at Bombay, 4.26. Thermometer, note on a self-registering, adapted to deep-sea soundings, 482. Thermometers, on the behaviour of, in a vacuum, 319. Thomson (Sir W.) on the fracture of brittle and viscous solids by ‘ shearing,’ 312. on a new astronomical clock and pendulum governor for uniform motion, 468. Thudichum (J. L. W.), researches con- ducted for the medical department of the Privy Council at the Pathological Laboratory of St. Thomas’s Hospital, 253. Tolylic mustard-oil, 70. Tomlinson (C.) on the action of solid nuclei in liberating vapour from boiling liquids, 240. Turacine, an animal pigment containing copper, researches on, 436. Tyndall (J.) on a new series of chemical reactions produced by light, 92, 104. on the blue colour of the sky, the polarization of skylight, and on the po- larization of light by cloudy matter generally, 223. , note on the formation and pheno- mena of clouds, 317. Utrecht, dip observations at, 284. Vacuum, on the behaviour of thermome- ters in, 319. ‘ and temperature-corrections to pen- - dulum observations, 488. Vice-presidents appointed, 155. Vienna, dip bservations at, 284. Voltaic circuit, instruments for determin ing the constants of, 146. Or 96 INDEX. Wallace (A. R.), Royal medal awarded to, | Weather-signals, telegraphic, 137. 147, Wheatstone (Sir C.), Copley medal awar- Wanklyn (J. A.) on a new class of or- ded to, 145. gano-metallic bodies containing sodium, | Whymper (E.) fossil plants collected by, 286. notice of, 142; description of, 329. Wave-machine, notice of, 145, END OF THE SEVENTEENTH VOLUME. PRINTED BY TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET, Se ere Us a bes Z The following Papers, read on mags 17th of June, will be published ‘in No. 114 :— | Fourth and concluding Supplementary Paper on the Calculation of the Numerical Value of Euler’s Constant. By Witiiam SHANKs. On some Elementary Principles in Animal Mechanics.—No. II. By the Rev. Samvet Haveuton, M.D. Dublin, D.C.L. Oxon., Fellow of Trinity College, Dublin. ~ Baxerian Lecture.—On the Continuity of the Gaseous and Liquid States of Matter. By Tuomas Anprews, M.D., F.RB.S., &e. On Paleocoryne, a genus of the Tubularine Hydrozoa from the Carboniferous forma- tion. By Dr. G. Martin Duncan, F.R.S., Sec. Geol. Soc., and H. M. Jenxrys, FE.G.S. An Inquiry into the Variations of the Human Skull, particularly in the Antero- posterior Direction. By JoHn CieLtanp, M.D., Professor of Anatomy and Phy- siology, Queen’s College, Galway. Researches on Vanadium.—Part Il. By Henry E. Roscos, B.A., Ph.D., F.R.S. The Physiological Action of Atropine, Digitaline, and Aconitine on the Heart and Blood-vessels of the Frog. By FrepEeric B. Nunnetey, M.D. London. On Holtenia, a Genus of Vitreous Sponges. By Wryvitie Taomson, LL.D., F_R.S.. Professor of Natural Science in Queen’s College, Belfast. On the Derivatives of Propane. By C. ScHORLEMMER. Researches on the Hydrocarbons of the series C,, Ho, 49— No. V. On Octyl Com- pounds. By C. ScHoRLEMMER. On the Refraction-Equivalents of the Elements. ByJ.H. GrapstoyE, Ph.D., F.R.S. On a Group of Varieties of the Muscles of the Human Neck, Shoulder, and Chest, with their transitional Forms and Homologies inthe Mammalia. By JoHN Woop, F.R.C.S., Examiner in Anatomy at the University of London. Results of the first Year’s Performance of the photographically Self-recording Me- teorological Instruments at the Central Observatory of the British System of Me- teorological Observations. By Lieut.-General EDwarp Sasing, R.A., President. On the Connexion between oppositely disposed Currents of Air and the Weather sub- sequently experienced in the British Islands. By Rosert H. Scort, M.A., Director of the Meteorological Office. On the Structure of the Cerebral Hemispheres. By W. H. Broapsent, M.D., Lec- turer on Physiology at St. Mary’s Hospital Medical School, and Senior Assistant Physician to the Hospital. On the Rhizopodal Fauna of the Deep Sea. By Wittiam B. CaRPenter, M.D., V.P.RB.S. On the Presence of Sulphocyanides in the Blood and Urine. By Arruur LEARED, M.D., M.R.1A. Some Experiments with the Great Induction Coil. By JoHN Henry PEppER, F.CS., Assoc. Inst. C.E. On the Mechanical Description of Curves. By W. H. L. Russxtz, F.R:S. TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET. sais OBITUARY NOTICES OF FELLOWS DECEASED. #1. | to 12 (1791 to 1804). Micuaet Farapay* was born in theworking class, of avery religious family. For two generations at least those who preceded him shared the extreme views in favour of toleration and disestablishment which caused, first, the de- position of the Rev. John Glas, and afterwards, the secession of his son-in- law, R. Sandeman, from the Presbyterian Church of Scotland. That the re- vealed will of Christ should be the supreme and only law, not only in all church questions, but in every thought and word and deed, was the belief of those who were nearest to Faraday in his infancy ; and this he held through- out his life, as though it had been a special revelation to himself. His father, James, was the third of ten children born at Clapham in Yorkshire. He was a blacksmith; his eldest brother worked as slater, grocer, and millowner, another brother was a farmer, another a packer, an- other a shopkeeper, and the youngest ashoemaker. Another of the brothers died young, in the year Michael was born; andaletter from the mother of the young man shows the strength of the religious feeling in mother and son. When twenty-five, in 1786, James Faraday married Margaret Hastwell, daughter of a farmer near Kirkby Stephen. Soon after their marriage they came to Newington in Surrey, where Michael, their third child, was born, September 22, 1791, in a house probably long since pulled down. The father obtained work at Boyd’s, in Welbeck Street; and when Michael was about five years old, after living a short time in Gilbert Street, they removed to rooms over a coach-house in Jacob’s Well Mews, Charles Street, Man- chester Square. The home of Michael Faraday was in these mews for nearly ten years; and his family remained there until 1809, when they moved to 18 Weymouth Street. Faraday himself has pointed out where he played at marbles in Spanish Place, and where, years later, he took care of his little sister in Manchester Square. He says, ‘‘ My education was of the most ordinary description, consisting of little more than the rudiments of reading, writing, and arith- metic at acommon day-school. My hours out of school were passed at home and in the streets.” Only a few yards off was a bookseller’s shop, No. 2 Blandford Street ; there, as a boy of thirteen, in 1804, he went on trial for a year to Mr. George Riebau. Once when walking with a niece they passed a little news-boy, when he said, “‘ I always feel a tenderness for those boys, because I once carried newspapers myself.” * An account of ‘‘ Faraday as a Discoverer” haying been already given to the world by one eminently qualified for the task, it has been deemed advisable in this place to give a narrative of the chief events of his personal history, with such indications of his character and opinions as may be read in his written correspondence and private memorials. This service has been kindly rendered by Dr. Bence Jones, F.R.S., Secre- tary to the Royal Institution, the devoted friend of Faraday, in whose hands have been placed the letters and manuscripts from which the substance, and, for the most part, the words of the present notice have been taken.—W. S., See. B.S, VOL, XVII. a ul 4Et. 13 to 19 (1805 fo 1811). On the 7th of October, 1805, when fourteen, Faraday was apprenticed; and, in consideration of his faithful service, no premium was given to Riebau. Four years later his father wrote (1m 1809), ‘‘Michael is bookbinder and sta- tioner, and is very active at learning his business. He has been most part of four years of his time out of seven. He has a very good master, and mistress, and likes his place well: he had a hard time for some while at first going; but, as the old saying goes, he has rather got the head above water, as there is two other boys under him.” Faraday himself says, ‘‘ Whilst an apprentice I loved to read the scien- tific books which were under my hands, and amongst them delighted in Marcet’s ‘Conversations on Chemistry,’ and the electrical treatises in the ‘ Encyclopedia Britannica.’ I made such simple experiments in chemistry as could be defrayed in their expense by a few pence per week, and also constructed an electrical machine, first with a glass phial, and afterwards with a real cylinder, as well as other electrical apparatus of a corresponding kind.’”? He told a friend that Watts on the Mind first made him think, and that his attention was turned to science by the article ‘‘ Electricity ” in an encyclopeedia he was employed to bind. “‘ My master,”’ he says, ‘ allowed me to go occasionally of an evening to hear the lectures delivered by Mr. Tatum in natural philosophy at his house, 53 Dorset Street, Fleet Street. I obtained a knowledge of these lectures by bills in the streets and shop-windows near his house. The hour was eight o’clock in the evening. The charge was Is. per lecture, and my brother Robert [who was three years older and followed his father’s busi- ness| made me a present of the money for several. I attended twelve or thirteen lectures between February 19, 1810, and September 26, 181i. It was at these lectures I first became acquainted with Magrath, Newton, Nicol, and others.” He learned perspective of a Mr. Masquerier, that he might illustrate these lectures. ‘‘ Masquerier lent me Taylor’s Perspective, a 4to volume, which I studied closely, copied all the drawings, and made some other very simple ones, as of cubes or pyramids, or columns in perspective, as exer- cises of the rules. I was always very fond of copying vignettes and small things in ink; but I fear they were mere copies of the lines, and that I had little or no sense of the general effect and of the power of the limes in producing it.’ How he was educating himself at this time and the subjects that interested him, may be seenin a manuscript volume (a shadow of the future) which he called “‘ The Philosophical Miscellany, being a collection of notices, occurrences, events, &c. relating to the arts and sciences col- lected from the public papers, reviews, magazines, and other miscellaneous works. Intended,” he says, “‘to promote both amusement and instruc- tion, and also to corroborate or invalidate those theories which are continu- ally starting into the world of science. Collected by M. Faraday, 1809-10.” In 1811 (zt. 19) he became acquainted, at Mr. Tatum’s, with Mr. il Huxtable and Mr. Benjamin Abbott ; the first was a medical student, the other, who belonged to the Society of Friends, was employed in a house of business in the city. Mr. Huxtable lent him Parkes’s ‘Chemistry,’ which Faraday bound for him, and the third edition of Thompson’s ‘ Chemistry.’ t. 20 (1812). Among the few notes Faraday made of his own life are the following :— “During my apprenticeship I had the good fortune, through the kindness of Mr. Dance, who was a customer of my master’s shop and also a member of the Royal Institution, to hear four of the last lec- tures of Sir H. Davy in that locality [he always sat in the gallery over the clock]. The dates of these lectures were February 29, March 14, April 8 and 10, 1812. Of these I made notes, and then wrote out the lectures in a fuller form, interspersing them with such drawings as I could make. The desire to be engaged in scientific occupation, even though of the lowest kind, induced me, whilst an apprentice, to write, in my ignorance of the world and simplicity of my mind, to Sir Joseph Banks, then President of the Royal Society. Naturally enough, ‘ No answer,’ was the reply left with the porter.” On Sunday, July 12, 1812, three months before his apprenticeship was over, he wrote the first of a series of letters to his friend Mr. Benjamin Abbott (who was a year and a half younger than himself), from which a full view can be gained of what he was by nature, and what his self-edu- cation at this time had made him. “‘T have lately made a few simple galvanic experiments merely to illus- trate to myself the first principles of the science. I was going to Knight’s to obtain some nickel, and bethought me that they had malleable zinc. I inquired and bought some; have you seen any yet? ‘The first portion I obtamed was in the thinnest pieces possible,—observe, in a flattened state. It was, they informed me, thin enough for the electric smoke, or, as I before called it, De Luc’s electric column. I obtained it for the purpose of form- ing disks, with which and copper, to make a little battery. The first I com- pleted contained the immense number of seven pair of plates!!! and of disks of the size of halfpences each! I, sir, covered them with seven half- pence, and I interposed between seven, or rather six, pieces of paper soaked in a solution of muriate of soda!!! But laugh no longer, dear A., rather wonder at the effects this trivial power produced ; it was sufficient to produce the decomposition of sulphate of magnesia, an effect which extremely sur- prised me.”? And then he describes how he built up a larger battery, and ob- tained greater and further effects, and reasons on the results, and urges his friend to think of these things, and ‘let me, if you please, siz, if you please let me know your opinion.” On the Monday he adds a postscript : ‘I am just now involved in a fit of vexation. I have an excellent prospect before me, a 2 Iv and cannot take it up for want of ability. Had I perhaps known as much of mechanics, mathematics, mensuration, and drawing as I do perhaps of some other sciences, that is to say, had I happened to employ my mind with these instead of other sciences, I could have obtained a place, an easy place, too, and that in London, at 5’, 6’, 7’, £800 per annum. Alas! alas! Inability. I must ask your advice on the subject, and intend, if I can, to see you next Sunday ; one necessary branch of knowledge would be that of the steam-engine, and, indeed, anything where iron is concerned.” In his next letter he says, speaking of fresh experiments with his battery, ‘*] must trust to your experiments more than my own; I have no time, and the subject requires several ;”” and in a letter written August 11, ‘‘ Pyro- techny is a beautiful art, but I never made any practical progress in it, except in the forming a few bad squibs ; so that you will gain little from me on that point.” In his next letter (August 19) he says, “ I cannot see any subject except chlorine to write on. Be not surprised, my dear A., at the ardour with which I have embraced this new theory. I have seen Davy himself support it. I have seen him exhibit experiments (conclusive experiments) explanatory of it; and I have heard him apply these experiments to the theory, and explain and enforce them in (to me) an irresistible manner. Conviction, sir, struck me, and I was forced to believe him, and with that belief came admiration.” In a letter dated about a fortnight before his apprenticeship was out he writes, ‘‘ Your commendations e the MS. lectures [of Davy] compel me to apologize most humbly for the numerous (very, yery numerous) errors they contain. If I take you right, the negative words ‘no flattery * may be substituted by the affirmative ‘irony ;’ be it so, I bow to the superior scholastic erudition of Sir Ben. There arein them errors that will not bear to be jested with, since they concern not my own performance so much as the performance of Sir H., and those are errors in theory; there are, I am conscious, errors in theory, and those errors I would wish you to point out to me before you attribute them to Davy.” In the last letter before the great change came (October 1, 1812), he says, *T rejoice in your determination to pursue the subject of electricity, and have no doubt that I shall have some very interesting letters on the subject. I shall certainly wish to (and will if possible) be present at the performance of the experiments ; but you know I shall shortly enter on the life of a jour- neyman, and then I suppose time will be more scarce than it is even now.” On the 8th of October he went as journeyman bookbinder to a Mr. De la Roche, then a French emigrant in London. His master was a very pas- sionate man, and troubled his assistant much; so much, that he felt he could not remain in that place, though every inducement was held out to him. His master liked him; and, to tempt him to stay, said ‘‘ I have no child, and if you will stay with me you shall have all I have when I am gone.” In his first letter to his friend Abbott, after his apprenticeship was ended, Vv October 11, he says, “ As for the change which you suppose to have taken place with respect to my situation and affairs, I have to thank my late master, it is but little. Of liberty and of time I have, if possible, less than before, though I hope my circumspection has not at the same time decreased. I am well aware of the irreparable evils that an abuse of those blessings will give rise to. These were pointed out to me by common sense; nor do I see how anyone who considers his own station and his own free occupations, pleasures, actions, &c. can unwittingly engage himself in them. I thank that Cause to whom thanks are due that Iam not in general a profuse waster of those blessings which are bestowed on me as a human being; I mean health, sensation, time, and temporal resources. Understand me here, for I wish not to be mistaken: I am well aware of my own nature; it is evil, and I feel itsinfluence strongly. I know, too, that ; but I find that I am passing insensibly to a point of divinity ; and as these matters are not to be treated lightly, I will refrain from pursuing it.” To his friend Huxtable he writes on the 18th: ‘‘ Conceiving it would be better to delay my answer until my time was expired, I did so; that took place Oct. 7, and since then I have had by far less time and liberty than before. With respect to a certain place I was disappointed, and am now working at my old trade, the which I wish to leave at the first convenient opportunity. I am at present in very low spirits, and scarce know how to continue on in a strain that will be any way agreeable to you.”’ “Under the encouragement of Mr. Dance,” he says, “I wrote to Sir Humphry Davy, sending, as a proof of my earnestness, the notes I had taken of his last four lectures ; the reply was immediate, kind, and favour- able. After this I continued to work as a bookbinder, with the excep- tion of some days during which I was writing as an amanuensis for Sir H. Davy, at the time when the latter was wounded in the eye from an ex- plosion of the chloride of nitrogen.” On the 24th of December, 1812, Sir Humphry Davy wrote to Faraday :— “Sir, I am far from displeased with the proof you have given me of your confidence, and which displays great zeal, power of memory, and attention. I am obliged to go out of town, and shall not be settled in town till the end of January ; | will then see you at any time you wish. It would gratify me to be of any service to you; I wish it may be in my power. Iam, Sir, Your obedient humble Servant.” At. 21 (1813). He “went,” he says, ‘‘to the City Philosophical Society, which was “ounded in 1808 at Mr. Tatum’s house, and, I believe, by him. He introduced me as a member of the Society in 1813. Magrath was Secretary to the So- ciety. It consisted of thirty or forty individuals, perhaps all in the humble or moderate rank of life. Those persons met every Wednesday evening for mutual instruction. Every other Wednesday the members were alone, and considered and discussed such questions as were brought forward by vl each in turn. On the intervening Wednesday evenings friends also of the members were admitted, and a lecture was delivered, literary or philo- sophical, each member taking the duty, if possible, in turn (or in default paying a fine of half a guinea). ‘This Society was very moderate in its pre- tensions, and most valuable to the members in its results.”’ [I remember, too, says one of the members, we had a “ class-book,”’ in which, in rota- tion, we wrote essays, and passed it to each other’s houses. | Sir H. Davy, at his first interview, advised him to keep in business as a bookbinder, and he promised to give him the work of the Institution, as well as his own and that of as many of his friends as he could influence. One night, in Weymouth Street, he was startled by a loud knock at the door, and on looking out he saw a carriage from which the footman had alighted and left a note for him. This was a request from Sir H. that he would call on him the next morning. Sir H. then referred to their former interview, and inquired whether he was still in the same mind, telling him that if so he would give him the place of assistant in the laboratory of the Royal Institution, from which he had on the previous day ejected its former occupant. ‘The salary was to be 25s. a week, with two rooms at the top of the house. In the minutes of the meeting of Managers on the Ist of March, 1813, is this entry :—‘‘ Sir Humphry Davy has the honour to inform the Managers that he has found a person who is desirous to occupy the situation in the In- stitution lately filled by William Payne. His name is Michael Faraday. He is ayouth of twenty-two years of age. As far as Sir H. Davy has been able to observe or ascertain, he appears well fitted for the situation. His habits seem good, his disposition active and cheerful, and his manner intelligent. He is willing to engage himself on the same terms as given to Mr. Payne at the time of quitting the Institution. “‘ Resolved,— That Michael Faraday be engaged to fill the situation lately occupied by Mr. Payne, on the same terms.” 7 As early as the 8th of March, Faraday dates his first letter from the Royal Institution to his friend Abbott. “‘T have been employed,’ he says, ‘‘ to-day in part in extracting the sugar from a portion of beetroot, and also in making a compound of sul- phur and earbon—a combination which has lately occupied in a consider- able degreé the attention of chemists.” A month later he says :—‘* When writing to you I seize that opportunity of striving to describe a circumstance or an experiment clearly, so that you will see I am urged on, by selfish motives partly, to our mutual correspon- dence ; but though selfish yet not censurable. *« Agreeable to what I have said above, I shall at this time proceed to acquaint you with the results of some more experiments on the detonating compound of chlorine and azote; and I am happy to say I do it at my ease, for I have escaped (not quite unhurt) from four different and strong explosions of the substance. Of these the most terrible was when I was Vil holding between my thumb and finger a small tube containing 74 grains of it. My face was within 12 inches of the tube, but I fortunately had on a glass mask. It exploded by the slight heat of asmall piece of cement that touched the glass above half an inch from the substance, and on the out- side. The explosion was so rapid as to blow my hand open, tear off a part of one nail, and has made my fingers so sore that I cannot yet use them easily. The pieces of tube were projected with such force as to cut the glass face of the mask I had on.” On the Ist of June he writes :—‘* The subject upon which I shall dwell more particularly at present has been in my head for a considerable time, and it now bursts forth in all its confusion. The opportunities that I have lately had of attending and obtaining instruction from various lecturers in their performance of the duty attached to that office, has enabled me to ob- serve the various habits, peculiarities, excellencies, and defects of each of them, as they were evident to me during the delivery. I did not wholly let this part of the things occurrent escape my notice ; but, when I found myself pleased, endeavoured to ascertain the particular circumstance that had affected me; also, when attending to Mr. Brande and Mr. Powell in their lectures, I observed how the audience were affected, and by what their pleasure and their censure was drawn forth. “Tt may perhaps appear singular and improper that one who is entirely unfit for such an office himself, and who does not even pretend to any of the requisites for it, should take upon him to censure and to commend others, to express satisfaction at this, to be displeased with that, according as he is led by his judgment, when he allows that his judgment is unfit for it ; but I do not see, on consideration, that the impropriety is so great. If I am unfit for it, it is evident that I have yet to learn; and how learn better than by the observation of others? If we never judge at all we shall never judge right ; and it is far better to learn to use our mental powers (though it may take a whole life for the purpose) than to leave them buried in idleness, amere void.” And then for three letters he goes on with his ideas on lecture-rooms, lectures, apparatus, diagrams, experi- ments, audiences; and when urged, two years later, to complete his re- marks, he answers, Dec. 31, 1816 :—‘‘ With respect to my remarks on lec- tures, I perceive I am but a mere tyro im the art, and therefore you must be satisfied with what you have, or expect at some future time a recapitu- lation, or rather revision of them.” * During this spring Magrath and I established the mutual-improve- ment plan, and met at my rooms up in the attics of the Royal Institution, or at Wood Street at his warehouse. It consisted perhaps of half a dozen persons, chiefly from the City Philosophical Society, who met of an even- ing to read together, and to criticise, correct, and improve each other’s pronunciation and construction of language. The discipline was very sturdy, the remarks very plain and open, and the results most valuable. This continued for several years.”’ Saturday night was the time of meeting Vill at the Royal Institution, in the furthest and uppermost room in the house, then Faraday’s place of residence. He says :—‘“‘ In the autumn Sir H. Davy proposed going abroad, and offered me the opportunity of going with him as his amanuensis, and the promise of resuming my situation in the Institution upon my return to England. Whereupon I accepted the offer, left the Institution on the 13th of October, and, after being with Sir H. Davy in France, Italy, Swit- zerland, the Tyrol, Geneva, &c. in that and the following year, returned to England and London the 23rd April 1815.” Whilst abroad he kept a daily journal, ‘‘ not,” he said, ‘to mstruct or to inform, or to convey even an imperfect idea of what it speaks ; its sole use is to recall to my mind at some future time the things I see now, and the most effectual way to do that will be, I conceive, to write down, be they good or bad, my present impressions.”” From this journal, and from his letters to his mother and his friend Benjamin Abbott, only a few cha- racteristic passages can be given here. In his journal he wrote, Wednesday, 13th October :—‘‘ This morning formed a new epoch in my life. I have never before, within my recollec- tion, left London [he had as an infant gone to Newcastle and Whitehaven, by sea chiefly] at a greater distance than twelve miles, and now I leave it perhaps for many years, to visit spots between which and home whole realms will intervene. ”T is indeed a strange venture at this time to trust ourselves in a foreign and hostile country, where also so little regard is had to protestations and honour, that the slightest suspicion would be sufficient to separate us for ever from England, and perhaps from life. But curiosity has frequently incurred dangers as great as these, and therefore why should I wonder at it in the present instance. If we return safe, the plea- sures of recollection will be highly enhanced by the dangers encountered ; and a never-failing consolation is that, whatever be the fate of our party, variety, a great source of amusement, and pleasure must occur.” Some idea of the variety of his observat'ons may be got from this note, 28th October, Dreux :—‘‘I cannot help dashing a note of admiration to one thing found in this part of the country—the pigs! At first I was po- sitively doubtful of their nature; for though they have pointed noses, long ears, rope-like tails, and cloven feet, yet who would have imagined that an animal with a long thin body, back and belly arched upwards, lank sides, long slender feet, and capable of outrunning our horses for a mile or two together, could be at all allied to the fat sow of England! When I first saw one, which was at Morlaix, it started so suddenly, and became so ac- tive in its motions on being disturbed, and so dissimilar in its actions to our swine, that I leoked out for a second creature of the same kind before I ventured to decide on its being a regular or an extraordinary production of nature; but I find they are all alike, and that what at a distance I should judge to be a greyhound, I am obliged, on a near approach, to ac- knowledge a pig.” 1X Ait. 22 (1814). To his mother he writes, April 14, 1814, from Rome :— When Sir H. Davy first had the goodness to ask me whether I would go with him, I mentally said, ‘no, I have a mother, I have relations here,’ and I almost wished that I had been insulated and alone in London; but nowI am glad that I have left some behind me on whom I ean think, and whose actions and occupations I can pictureinmy mind. Whenever a vacant hour occurs I employ it by thinking on those at home. In short, when sick, when cold, when tired, the thoughts of those at home are a calm and refreshing balm to my heart. Let those who think such thoughts are useless, vain, and paltry think so still. I envy them not their more refined and more estranged feelings. Let them look about the world unencumbered by such ties and heart-strings, and let them laugh at those who, guided more by nature, cherish such feelings. For me, I still cherish them, in opposition to the dictates of modern refinement, as the first and greatest sweetness in the life of man.” In a letter to his friend Abbott, dated September 6, 1814, he says :—“I fancy that when I set my foot in England I shall never take it out again; for I find the prospect so different from what it at first appeared to be, that I am certain, if I could have foreseen the things that have passed, I should never have left London. In the second place, enticing as travelling is (and I appreciate fully its advantages and pleasures), I have several times been more than half decided to return hastily home ; but second thoughts have still induced me to try what the future may produce, and now I am only detained by the wish of improvement. I have learned just enough to per- ceive my ignorance, and, ashamed of my defects in everything, I wish to seize the opportunity of remedying them. The little knowledge I have gained in languages makes me wish to know more of them, and the little I have seen of men and mannersis just enough to make me desirous of seeing more ; added to which, the glorious opportunity I enjoy of improving in the knowledge of chemistry and the sciences continually, determines me to finish this voyage with Sir Humphry Davy; but if I wish to enjoy those advantages | have to sacrifice much; and though those sacrifices are such as an humble man would not feel, yet I cannot quietly make them. Travelling, too, I find, is almost inconsistent with religion (I mean modern travelling), and I am yet so old-fashioned as to remember strongly (I hope perfectly) my youthful education, and upon the whole, malgré the advan- tages of travelling, it is not impossible but that you may see me at your door when you expecta letter.”’ Zit. 23 (1815). On the 25th January 1815, he writes :—“* You tell me I am not happy, and you wish to share my difficulties. [I have nothing important to tell you, or you should have known it long ago; but, since your friendship makes you feel for me, I will trouble you with my trifling affairs. xX “It happened, a few days before we left England, that Sir H.’s valet declined going with him, and in the short space of time allowed by circum- stances, another could not be got. Sir H. told me he was very sorry, but that if I would do such things as were absolutely necessary for him until he got to Paris, he should there get another. I murmured, but agreed. At Paris he could not get one; at Lyons he could not get one; at Mont- pellier he could not get one; nor at Genoa, nor at Florence, nor at Rome, nor in all Italy; and I believe at last he did not wish to get one; and we are just the same now as we were when we left England. This, of course, throws things into my duty which it was not my agreement, and is not my wish to perform, but which are, if I remain with Sir H., unavoid- able. These, it is true, are very few; for having been accustomed in early years to do for himself, he continues to do so at present, and he leaves very little for a valet to perform; and as he knows that itis not pleasing to me, and that I do not consider myself as obliged to do it, he is always as care- ful as possible to keep those things from me which he knows would be dis- agreeable. But Lady Davy is of another humour. She likes to show her authority, and at first I found her extremely earnest in mortifying me. This occasioned quarrels between us, at each of which I gained ground and she lost it; for the frequency made me care nothing about them and weakened her authority, and after each she behaved in a milder manner. Sir H. has also taken care to get servants of the country, yeleped lacquais de place, to do everything she can want, and now I am somewhat comfort- able ; indeed at this moment I am perfectly at liberty, for Sir H. has gone to Naples to search for a house or lodging to which we may follow him, and I have nothing to do but see Rome, write my journal, and learn Italian.”’ About the same time he writes to his friend Huxtable :— ‘Since Sir H. has left England he has made a great addition to chemistry in his researches on the nature of iodine. He first showed that it was a simple body. He combined it with chlorine and hydrogen, and lately with oxygen, and thus has added three acids of a new species to the science. He combined it with the metals, and found a class of salts ana- logous to the hyperoxymuriates. He still further combined these sub- stances, and investigated their curious and singular properties. “The combination of iodine with oxygen is a late discovery, and the paper has not yet perhaps reached the Royal Society. It confirms all Sir H.’s former opinions and statements, and shows the inaccuracy of the labours of the French chemists on the same subjects. “Sir Humphry also sent a long paper lately to the Royal Society, on the ancient Greek and Roman colours, which will be worth your reading when it is printed.” A fortnight after his return to England he was engaged as assistant in the laboratory at a salary of 30s. a week, and apartments were given to him, X1 Zit. 24 (1816). On the 17th of January, 1816, Faraday began a course of seventeen Lectures on Chemistry, at the City Philosophical Society, which extended over two years andahalf. He called them “‘ an account of the inherent Pro- pertiesof Matter, of the forms in which matter exists, and of simple ele- mentary substances.” During the year he gave six or seven lectures on the general propertiesof matter, on theattraction of cohesion, on chemical affinity, on radiant matter, on oxygen, chlorine, iodine, and fluorine, on hydrogen, and on nitrogen. He wrote his first lectures at full length, whilst of the latter lectures he only made notes, putting the experiments very distinctly apart, and he kept very much to this plan during the rest of his life. It was in this year also that Faraday published his first paper, an analysis of native caustic lime, in the Quarterly Journal of Science. In the volume of his ‘ Experimental Researches on Chemistry and Physics,’ he has added a note :—‘‘ I reprint this paper at full length ; it was the beginning of my communications to the public, and in its results very important tome. Sir Humphry Davy gave me the analysis to make asa first attempt in chemistry, at a time when my fear was greater than my confidence, and both tar greater than my knowledge; at a time, also, when I had no thought of ever writing an original paper on science. The addition of his own comments, and the publication of the paper, encouraged me to go on making, from time to time, other slight communications, some of which appear in this volume. ‘Their transference from the ‘ Quarterly’ into other journals in- creased my boldness, and now that forty years have elapsed, and I can - look back on what successive communications have led to, I still hope, much as their character has changed, that I have not either now or forty years ago been too bold.” Early in February he thus wrote to his friend Abbott :—‘‘ Be not of- fended that I turn to write you a letter, because I feel a disinclination to do anything else; but rather accept it as a proof that conversation with you has more power with me than any other relaxation from business,— business I say ; and I believe it is the first time for many years that I have applied it to my own occupations. But at present they actually deserve the name; and you must not think me in a laughing mood, but in earnest. It is now 9 o'clock p.m., and I have just left the laboratory and the pre- paration for to-morrow’s two lectures. Our double course makes me work enough ; and to them add the attendance required by Sir H. in his re- searches, and then if you compare my time with what is to be done in it, you will excuse the slow progress of our correspondence on my side. Un- derstand me, I am not complaming; the more I have to do the more I learn, but I wish to avoid all impression on your side that I am lazy— suspicions, by-the-by, which a moment’s reflection convinces me can never exist.” In consideration of the additional labour caused to him by Mr. Brande’s xu lectures in the laboratory, his salary at the Institution was increased to £100 per annum. This year Faraday began a common-place book, in which he continued to make entries on all subjects for fifteen years. Some of the earliest are on the production of oxygen, on the combustion of zine and iron in condensed air, on a course of lectures on geology delivered at the Royal Institution by Mr. Brande, and an account of Zerah Colburn, thirteen years old, the American calculating boy. Sir H. Davy sent him with a note, saying “his father will explain to you the method the son uses, in confidence ; I wish to ascertain if it can be practically used.” He wrote in this year :—‘‘ When Mr. Brande left London in August, he gave the Quarterly Journal in charge to me; it has very much of my time and care, and writing through it has been more abundant with me. It has, however, also been the means of giving me earlier information on some new objects of science.” Mit. 23 (181 F): In 1817 he gave five lectures at the City Philosophical Society on the atmosphere, on sulphur and phosphorus, on carbon, on combustion, and on the metals generally. He had a paper in the Quarterly Journal on the escape of gases through capillary tubes. The entries in his common- place book consist of geological notes of South Moulton Slate, Tiverton, Hulverston, Taunton, Somerton, and Castle Cary; a multitude of che- mical queries or questions to be worked at, among which are the exciting effects of different vapours and gaseous mixtures ; compounds of chlorine and carbon made out in the autumn of 1820; electricity, magnetism; a pyrometer ; extracts from Shakspeare, Lalla Rookh, Rambler, &c. At the end of the year he tells his friend Abbott that he can see less of him, “ in consequence of an arrangement I have made with a gentleman recommended to me by Sir H. Davy; I am engaged to give him lessons in mineralogy and chemistry, three times a week, in the evenings, for a few months.” 4Gt. 26 (1818). In 1818 five lectures were given by Faraday at the City Philosophical Society, on gold, silver, &c., on copper and iron, on tin, lead, and zine, and on alkalies and earths. He had six papers in the Quarterly Journal, of which the most important was on sounds produced by flame in tubes. In his common-place book there is a long course of lectures on oratory, by Mr. B. H. Smart; questions for Dorset Street ; an experimental agitation of the question of electrical induction, “‘ Bodies do not act where they are not—query, isnot the reverse of this true? Do not all bodies act where they are not ; and do any of them act where they are? Query, the nature of courage ; is it a quality or a habit ?’’ Chemical questions. On July 1st he gavea lecture to the City Philosophical Society. It is en- titled ‘‘ Observations on the Inertia of the Mind.” As this lecture is wholly xiii written out, it probably was one of the essays contained in the class-book of the Society. Towards the end of the year Faraday wrote his first letter to M. G. Dela Rive, the father of the present M. Auguste De la Rive. He says :— *«< Dear Sir,—Your kindness, when here, in requesting me to accept the honour of a communication with you on the topics which occur in the general progress of science, was such as almost to induce me to overstep the modesty due to my humble situation in the philosophical world, and to accept of the offer you made me. But I do not think I should have been emboldened thus to address you had not Mr. Newman since then informed me that you again expressed a wish to him that I should do so; and fearful that you should misconceive my silence I put pen to paper, willing rather to run the risk of being thought too bold than of incurring the charge of neglect towards one who had been so kind to me in his ex- pressions. My slight attempts to add to the general stock of chemical knowledge have been received with favourable expressions by those around me; but I have, on reflection, perceived that this arose from kindness on their parts, and the wish to incite me on to better things. I have always, therefore, been fearful of advancing on what has been said, lest I should assume more than was intended; and I hope that a feeling of this kind will explain to you the length of time which has elapsed between the time when you requested me to write and the present moment when I obey you. “T am not entitled, by any peculiar means of obtaining a knowledge of what is doing at the moment in science, to deserve your attention, and I have no claims in myself to it. Ijudge it probable that the news of the philoso- -phical world will reach you much sooner through other more authentic and more dignified sources, and my only excuse even for this letter is obedience to your wishes, and not on account of anything interesting for its novelty.” He then describes a new process for the preparation of gas for illumina- tion. He ends, “I am afraid that, with all my reasons, I have not been able to justify this letter. If my fears are true I regret at least ; it was your kindness that drew it from me, and to your kindness I must look for an excuse.” Zit. 27 (1819). In 1819 he had no paper in the Quarterly Journal. He gave one lec- ture at the City Philosophical Society on the Forms of Matter. Matter he classifies into four states, which depend on differences in the essential B properties, and cautiously says, ‘‘thus a partial reconciliation is esta- blished to the belief that all the variety of this fair globe may be con- _ verted into three kinds of radiant matter.” His common-place book contains scarcely any scientific notices. Oa July the 10th he started by coach for a three weeks’ walking tour in Wales, with his friend Magrath. He kept a journal, and his descriptions of the scenery, of the copper works of Swansea, the mines of Anglesea, and the slate-quarries of Bangor, are still of interest. X1V At, 28 (1820). This year was one of the most important in the life of Faraday ; he had his first paper read to the Royal Society on two new compounds of chlo- rine and carbon, and on a new compound of iodine, carbon, and hydrogen ; and with Mr. Stodart, the surgical instrument maker, he published, in the Quarterly Journal of Science, experiments on the alloys of steel, made with a view to its improvement. In his common-place book, among the chemical questions, we find che- mical lessons, or a plan of lessons in chemistry, and processes for manipu- lation, the germ of his work on Chemical Manipulation. There is also a list headed ‘‘ Lecture Subjects,’’ including application of statics to che- mistry, approximation of mechanical and chemical philosophy, application of mathematics to actual service and use in the arts, series of mechanical arts, as tanning. On the 20th of April he writes to M. G. De la Rive :—*‘1 never in my life felt such difficulty in answering a letter as I do at this moment your very kind one of last year. I was delighted on receiving it to find that you had honoured me with any of your thoughts, and that you would permit me to correspond with you by letter. Mr. Stodart and myself have lately been engaged in a long series of experiments and trials on steel, with the hope of improving it, and I think we shali in some degree suc- ceed. We are still very much engaged in the subject ; but if you will give me leave I will, when they are more complete, which I expect will be | shortly, give you a few notes on them. I succeeded by accident a few weeks ago in making artificial plumbago, but not in useful masses, We have lately had some important trials for oil in this metropolis, in which I, with others, have been engaged. ‘They have given occasion for many experiments in oil, and the discovery of some new and curious results ; one of the trials only is finished, and there are four or five more to come. As soon as I can get time, it is my intention to trace more closely what takes place in oil by heat.”’ June 26 he sends a long abstract of the paper on Steel, and ends :—‘* Now I think I have noticed the most interesting points at which we have arrived. Pray pity us, that after two years’ experiments we have got no further; but I am sure if you knew the labour of the experiments you would applaud us for our perseverance at least. We are still encouraged to go on, and I think the experience we have gained will shorten our future labours. | “If you should think any of our results worth notice in the ‘ Biblio- théque,’ this letter is free to be used in any way you please. Pardon my vanity for supposing anything I can assist in doing can be worth atten- tion; but you know we live in the good opinion of ourselves and of others, and therefore naturally think better of our own productions than they deserve.” Early the following month there is evidence that an entire change took XV place in the state of his mind. Among his friends was Mr. Edward Barnard, one of a family living in Paternoster Row, with which he had long been intimate, and which agreed with his own family in its religious views. Faraday proposed to, and ultimately was accepted by, Mr. Barnard’s sister, Sarah. Ait. 29 (1821). March 11, Sir H. Davy wrote :—‘ Dear Mr. Faraday, I have spoken to Lord Spencer, and I am in hopes that your wishes may be gratified; but do not mention the subject till I see you.’’ This wish was probably to bring his wife to the Institution. In June he was appointed superinten- dent of the house and laboratory, in the absence of Mr. Brande. All obstacles were removed, and the marriage took place on the 12th of June. Mr. Faraday, desiring that the day should be considered just like any other day, offended some of his near relations by not asking them to his wedding. In a letter to his wife’s sister, previous to the marriage, he says, ‘‘ There will be no bustle, no noise, no hurry cccasioned even in one day’s proceeding. In externals, that day will pass like all others, for it is in the heart that we expect and look for pleasure.” A month later, at a meeting of the congregation, he was fully admitted as a member of the Sandemanian Church. His common-place book shows that he read little. In a letter, May 19, to M. G. De la Rive, he says, “ Mr. Stodart and myselfare continuing our experiments on steel, which are very laborious.” On July 12, a paper was read to the Royal Society on a new Compound of Chlorine and Carbon, by Phillips and Faraday. This, as well as Faraday’s previous paper on two Chlorides of Carbon, was printed in the Philoso- phical Transactions. In the Quarterly Journal he had a short paper on the Vapour of Mercury at common temperatures. On the 12th of September he writes the following letter to M. G. De la Rive :— «‘ You partly reproach us here with not sufficiently esteeming Ampére’s experiments on electro-magnetism. Allow me to extenuate your opinion a little on this point. With regard to the experiments, I hope and trust that due weight is allowed to them; but these you know are few, and theory makes up the great part of what M. Ampére has published, and theory in a great many points unsupported by experiments, when they ought to have been ad- duced. At the same time, M. Ampére’s experiments are excellent, and his theory ingenious ; and for myself, I had thought very little about it before your letter came, simply because, being naturally sceptical on philosophi- eal theories, | thought there was a great want of experimental evidence. Since then, however, I have engaged on the subject, and have a paper in our Institution journal, which will appear in a week or two, and that will, as it contains experiment, be immediately applied by M. Ampére in sup- xvi port of his theory much more decidedly than it is by myself. I intend to enclose a copy of it to you, and only want the means of sending it. “| find all the usual attractions and repulsions of the magnetic needle by the conjunctive wire are deceptions, the motions being not attractions or repulsions, nor the result of any attractive or repulsive forces, but the result of a force in the wire, which, instead of bringing the pole of the needle nearer to or further from the wire, endeavours to make it move round it in a never-ending circle and motion whilst the battery remains in action. I have succeeded not only in showing the existence of this motion theoreti- cally, but experimentally, and have been able to make the wire revolve round a magnetic pole, or a magnetic pole round the wire, at pleasure. The law of revolution, and to which all the other motions of the needle and wire are reducible, is simple and beautiful. Conceive a portion of connect- ing wire north and south, the north end being attached to the positive pole of a battery, the south to the negative ; a north magnetic pole would then pass round it continually in the apparent direction of the sun from east to west above, and from west to east below. Reverse the connexions with the battery, and the motion of the pole is reversed. Or if the south pole is made to revolve, the motions will be in the opposite directions, as with the north pole. <‘ If the wire be made to revolve round the pole, the motions are according to those mentioned. For the apparatus I used there were but two plates, and the direction of the motions was of course the reverse of those with a battery of several pair of plates, and which are given above. Now I have been able experimentally to trace this motion into its various forms, as ex- hibited by Ampeére’s helices, &c., and in all cases to show that dissimilar poles repel as well as attract, and that similar poles attract as well as repel, and to make, I think, the analogy between the helice and common bar- magnet far stronger than before; but yet I am by no means decided that there are currents of electricity in the common magnet. I have no doubt that electricity puts the circles of the helice into the same state as those circles are in that may be conceived in the bar-magnet ; but I am not cer- tain that this state is directly dependent on the electricity, or that it can- not be produced by other agencies, and therefore, until the presence of elec- trical currents be proved in the magnet by other than magnetical effects, I shall remain in doubts about Ampére’s theory.” Oct. 8th he writes to J. Stodart, Esq. :— ‘«‘T hear every day more and more of those sounds, which, though only whispers to me, are, I suspect, spoken aloud amongst scientific men, and which, as they in part affect my honour and honesty, I am anxious to do away with, or at least to prove erroneous in those parts which are disho- nourable to me. You know perfectly well what distress the very unex- pected reception of my paper on Magnetism in public has caused me, and you will not therefore be surprised at my anxiety to get out of it, though I give trouble to you and others of my friends in doing so. If I under- Xvi stand aright, I am charged (1) with not acknowledging the information I received in assisting Sir H. Davy in his experiments on this subject ; (2) with concealing the theory and views of Dr. Wollaston ; (3) with taking the subject whilst Dr. Wollaston was at work on it; and (4) with disho- nourably taking Dr. Wollaston’s thoughts, and pursuing them without acknowledgment to the results I have brought out. «There is something degrading about the whole of these charges ; and were the last of them true, I feel that I should uot remain on the terms I now stand at with you or any scientific person. Nor can I indeed bear to remain suspected of such a thing. My love for scientific reputation is not yet so high as to induce me to obtain it at the expense of honour, and my anxiety to clear away this stigma is such, that I do not hesitate to trouble you, even beyond what you may be willing to do for me.” He proceeds then to justify himself, and says, ‘‘ The cause of my making the experiments detailed in my paper, was the writing of the historical Sketch of Electromagnetism that has appeared in the last two Numbers of the ‘ Annals of Philosophy.’ ” On the 30th of October he writes directly to Dr. Wollaston, saying :-— “<7 heard from two or three quarters that it was considered that I had not behaved honourably, and that the wrong I had done I had done to you; I immediately wished and endeavoured to see you, but was prevented by the advice of my friends, and am only now at liberty to pursue the plan I in- tended to have taken at first. «Tf I have done any one wrong it was quite unintentional, and the charge of behaving dishonourably is not true. I am bold enough, sir, to beg the favour of a few minutes’ conversation with you on this subject, simply for these reasons, that I can clear myself, that I owe obligations to you, that I respect you, that I am anxious to escape from unfounded impressions against me, and, if I have done any wrong, that I may apolo- gise for it.” The following day Dr. Wollaston writes :—‘‘ You seem to me to labour under some misapprehension of the strength of my feelings upon the sub- ject to which you allude. As to the opinions which others may have of your conduct, that is your concern, not mine ; andif you fully acquit your- self of making any incorrect use of the suggestions of others, it seems to me - that you have no occasion to trouble yourself much about the matter. But if you are desirous of any conversation with me, and could with conveni- ence call to-morrow morning between ten and half-past ten, you will be sure to find me.” In a letter to M. G. De la Rive a fortnight later, he does not allude to the distress of mind he had gone through. On Christmas Day he succeeded in making a wire through which a current of voltaic electricity was passing obey the magnetic poles of the earth in the way it does the poles of a bar-magnet. Mr. George Barnard, who was with him in the laboratory at the time, yOL. XVII. 6b 7 XV1l1 writes :— ‘All at once he exclaimed, ‘ Do you see, do you see, do you see, George!’ as the small wire began to revolve. One end I recollect was in the cup of quicksilver, the other attached above to the centre. I shall never forget the enthusiasm expressed in his face, and the sparkling in his eyes!” Zit. 30 (1822). In 1822, a paper on the Alloys of Steel by Stodart and Faraday was read to the Royal Society, and printed in the Transactions. In the Quar- terly Journal of Science he had two papers on the Changing of Vegetable Colours as an alkaline property, and on some Bodies possessing it; and on the Action of Salts on Turmeric Paper. The results of the paper on steel were of no practical value, and this, one of his first and most laborious investigations, is strikingly distin- guished from all his other works by ending in nothing, This year he began a fresh manuscript volume, which he called “ Che- nical Notes, Hints, Suggestions, and Objects of Pursuit.’’ To it he trans- ferred many of the queries out of his common-place book, but he separated his subjects under different heads. He puts as a sort of preface, “ I already owe much to these notes, and think such a collection worth the making by every scientific man. Iam sure none would think the trouble lost after a year’s experience.” When a query got answered, he drew a pen through it, and wrote the date of the answer across it. In this book are the first germs, in the fewest possible words, of his future work. The last week in July he went with his friend Richard Phillips to Mr. Vivian’s, near Swansea, to introduce a new process into the copper-works, and for atrial at Hereford, which was put off. At the end of a fortnight he returned to London. His letters to Mrs. Faraday, who went to Ramsgate, are full of affection, and the account of his ‘ escape from the large mansion and high company ”’ on the Sunday, and other passages, show how strongly religious feeling was at work in him. Ait. 31 (1823). Two papers this year were read to the Royal Society, and printed in the Transactions—one on Fluid Chlorine, the other on the Condensation of seve- ral Gases into Liquids; and he had four papers in the Quarterly Journal of Science—one on Hydrate of Chlorine, one on the Change of Musket-balls in Shrapnell Shells, on the Action of Gunpowder on Lead, on the purple tint of Plate-glass affected by Light. In a letter to Prof. G. De la Rive, March 24, he says:—‘‘I have been at work lately, and obtained results which I hope you will approve of. I have been interrupted twice in the course of experiments by explosions, both in the course of eight days. One burnt my eyes, the other cut them, but I fortunately escaped with slight injury only in both cases, and am now nearly well. During the winter I took the opportunity of examining the hydrate of chlorine, and analyzing xix it; the results, which are not very important, will appear in the next num- ber of the Quarterly Journal (over which I have no influence), Sir H. Davy, on seeing my paper, suggested to me to work with it under pres- sure, and see what would happen by heat &c. Accordingly I enclosed it in a glass tube, hermetically sealed, heated it, obtained a change in the substance, and a separation into two different fluids ; and upon further ex- amination I found that the chlorine and water had separated from each other, and the chlorine gas, not being able to escape, had condensed into the liquid form. To prove that it contained no water, I dried some chlo- rine gas, introduced it into a long tube, condensed it, and then cooled the tube, and again obtained fluid chlorine. Hence what is called chlorine gas is the vapour of a fluid. I have written a paper, which has been read to the Royal Society, and to which the President did me the honour to attach a note, pointing out the general application and importance of this mode of producing pressure with regard to the liquefaction of gases. He imme- diately formed liquid muriatic acid by a similar means, and, pursuing the experiments at his request, I have since obtained sulphurous acid, carbonic acid, sulphuretted hydrogen, euchlorine, and nitrous oxide in the fluid state, quite free from water. Some of these require great pressure for this pur- pose, and I have had many explosions. “I send you word of these results because I know your anxiety to hear of all that is new, but do not mention them publicly (or at least the latter ones, until you hear of them, either through the journals, or by another letter from me, or from other persons), because Sir Humphry Davy has promised the results in a paper to the Royal Society for me, and I know he wishes first to have them read there; after that they are at your ser- vice. | “T expect to be able to reduce many other gases to the liquid form, and promise myself the pleasure of writing you about them.” March 25, Monday, he writes to his friend Huxtable :—“ I met with an- other explosion on Saturday evening, which has again laid up my eyes. It was from one of my tubes, and was so powerful as to drive the pieces of glass like pistol-shot through a window. However, I am getting better, and expect to see as well as ever in a few days. My eyes were filled with glass at first.” On May the Ist his certificate was read for the first time at the Royal Society :— **Mr. Michael Faraday, a gentleman eminently conversant in chemical science, and author of several papers, which have been published in the Transactions of the Royal Society, beimg desirous of becoming a Fellow thereof, we, whose names are undersigned, do of our personal knowledge recommend him as highly deserving that honour, and likely to become a useful and valuable member.”’ Twenty-nine names follow; the first six were Wm. H. Wollaston, J. G. Children, Wm. Babington, Sir W. Herschel, J. South, Davies Gilbert. The ioe XX certificate had to be read at ten successive meetings before the ballot came on. On the 30th of May he wrote to H. Warburton, Esq. :—“ Sir, I have been anxiously waiting the opportunity you promised me of a conversation with you, and from late circumstances am now still more desirous of it than at the time when I saw you in the Committee. I am sure you will not regret the opportunity you will afford for an explanation; for I do not believe there is anything you would ask after you have communicated with me, that I should not be glad to do. I am satisfied that many of the feel- ings you entertain on the subject in question would be materially altered by granting my request. At the same time, as I have more of your opi- nions by report than otherwise, 1 am perhaps not well aware of them. It was only lately that I knew you had any feeling at all on the subject. You would probably find yourself engaged in doing justice to one who can- not help but feel that he has been injured, though he trusts unintention- ally. I feel satisfied you are not in possession of all the circumstances of the case, but I am also sure you will not wish willingly to remain ignorant of them. Excuse my earnestness and freedom on this subject, and consider for a moment how much I am interested in it.” At the foot of the copy of this letter Faraday made the following notes :— ‘In relation to Davy’s opposition to my election at the R. S.: Sir H. Davy angry, May 30; Phillips’s report through Mr. Children, June 5; Mr. War- burton called first time, June 5, evening ; I called on Dr. Wollaston, and he not in town, June 9; I called on Dr. Wollaston and saw him, June 14; I called at Sir H. Davy’s, and he called on me, June 17.” Many years ago he gave a friend the following facts, which were written down at the time: Sir H. Davy told him that he must take down his certificate. Faraday replied that he had not put it up: that he could not take it down as it was put up by his proposers. Sir Humphry then said, he must get his proposers to take it down. Faraday answered that he knew they would not do so. Then, said Sir H., f, as President will take it down. Faraday replied, that he was sure Sir Humphry Davy would do what he thought was for the good of the Society. One of Faraday’s proposers told him that Sir H. had walked for an hour round the courtyard of Somerset House, trying to convince Faraday’s in- formant that Faraday ought not to be elected. However, the storm passed away, but not without leaving its effects; and on the 29th of June Sir H. Davy ends a note—“I am, dear Faraday, verysincerely, your well-wisher and friend.’ July 8, Mr. Warburton wrote :—‘“I have read the article in the Royal Institution Journal, vol. xv. p. 288, on Electromagnetic Rotation, and with- out meaning to convey to you that I approve of it unreservedly, I beg to say that upon the whole it satisfies me, as I think it will Dr. Wollaston’s- other friends. Having everywhere admitted and maintained that, on the | score of scientific merit, you were entitled to a place in the Royal Society, I XXl never cared to prevent your election, nor should [have takenany pains to form a party in private to oppose you. What I should have done would have been to take the opportunity, which the proposing to ballot for you would have afforded me, to make remarks in public on that part of your conduct to which I objected. Of this I made no secret, having intimated my intention to some of those from whom I knew you would hear of it, and to the President himself. When I meet with any of those in whose presence such conversa- tion may have passed, I shall state that my objections to you as a Fellow are and ought to be withdrawn, and that I now wish to forward your election.” | Aug. 29, Faraday writes to Mr. Warburton :— “T thank you sincerely for your kindness in letting me know your opinion of the statement ; though your approbation of it is not unreserved, yet it very far surpasses what I expected; and I rejoice that you do not now think me destitute of those moral feelings which you remarked to me were neces- sary in a Fellow of the Royal Society. “Conscious of my own feelings and the rectitude of my intentions, I never hesitated in asserting my claims, or in pursuing that line of conduct which appeared to me to be right. I wrote the statement under this influence without any regard to the probable result ; and Iam glad that a step which I supposed would rather tend to aggravate feelings against me has, on the contrary, been the means of satisfying the minds of many, and of making them my friends. ‘Two months ago I had made up my mind to be rejected by the Royal Society as a Fellow, notwithstanding the knowledge I had that many would do me justice ; and in the then state of my mind rejection or reception would have been equally indifferent to me. Now that I have experienced so fully the kindness and liberality of Dr. Wollaston, which has been constant throughout the whole of this affair, and that I find an expression of goodwill strong and general towards me, I am delighted by the hope I have of being honoured by Fellowship with the Society; and I thank you sincerely for your promise of support in my election, because I know you would not give it unless you sincerely thought me a fit person to be admitted.” Faraday was the original Secretary of the Athenzeum Ciub; but finding the occupation incompatible with his pursuits, resigned in May 1824. The original prospectus and early list of members have his name attached to them. This year he was elected Corresponding Member of the Academy of Sciences, Paris, of the Accademia dei Georgofili di Firenze, Honorary Member of the Cambridge Philosophical Society and the British Institution. Aft. 32 (1824). Faraday was elected Fellow of the Royal Society, January Sth. This year he published only a historical statement in the Quarterly Journal of Science on the liquefaction of gases, showing that carbonic acid, ammonia, Xx arseniuretted hydrogen, chlorine, sulphurous acid had been liquefied before his own experiments in 1823. He joined Mr. Brande in the delivery of the morning course of chemical lectures at the Institution. In July he went to the Isle of Wight with Mrs. Faraday, and returned again in August to bring her home. He was elected an Honorary Member of the Cambrian Society of Swansea, and a Fellow of the Geological Society. This year the President and Council of the Royal Society appointed a committee for the improvement of glass for optical purposes, consisting of Fellows of the Royal Society and members of the then Board of Longitude. Zt. 33 (1825). Faraday was made Director of the Laboratory of the Royal Institution, and therein he had three or four evening meetings of the members of the Institution, from which came the Friday evening meetings of the members. He was elected a Member of the Royal Institution, and a Corresponding Member of the Society of Medical Chemists, Paris. He had a paper on new compounds of carbon and hydrogen, and on certain other products obtained during the decomposition of oil by heat, read to the Royal Society, and printed in the Transactions; one of these substances was benzol. He had a paper in the Quarterly Journal on some cases of the formation of ammonia, and on the means of testing the presence of minute portions of nitrogen in certain states. In May a subcommittee, consisting of Mr. Herschel, Mr. Dollond, and Mr. Faraday, was appointed to have the direct superintendence and per- formance of experiments on the manufacture of optical glass. “ It was my business to investigate particularly the chemical part of the inquiry. Mr. Dollond was to work and try the glass, and ascertain practically its good or bad qualities, whilst Mr. Herschel was to examine its physical proper- ties, reason respecting their influence and utility, and make his competent mind bear upon every part of the inquiry. In March 1829 the committee was reduced to two by the retirement of Mr. Herschel, who about that period went to the Continent.” In July he left London by steamboat for Scotland. After visiting the damask works, he went to Leith to see the glass works. He minutely de- scribes the geology of Salisbury Craig, Arthur’s Seat, and Craigleith quarries, and then went to Rubislaw (Bleaching Liquor Works), Aberdeen. — Here he made many experiments for the proprietors, with whom he stayed. | Ait. 34 (1826). He had a paper on the Mutual Action of Sulphuric Acid and Naphthaline printed in the Philoscphical Transactions, and another on the existence of a limit to Vaporization, and in the Quarterly Journal of Science four papers— on Pure Caoutchoue and the Substances by which it is accompanied in the state of Sap or Juice, on the Fluidity of Sulphur at common temperatures, on a peculiar perspective appearance of aérial light and shade, and on the confinement of Dry Gases over Mercury. XX There were seventeen meetings of the members of the Royal Institution held on Friday evenings during this season, and at these Faraday gave seven discourses—on Pure Caoutchouc; on Brunel’s Condensed Gas-engine ; on Lithography ; on the existence of a limit to Vaporization ; on Sulpho- — vinie and Sulphonaphthalic Acid; on Drummond’s Light; on Brunel’s Tunnel at Rotherhithe. This year he was relieved from the duty of chemical assistant at the lectures given at the Institution, because of his occupation in research, and he was made an honorary member of the Westminster Medical Society. In his chemical notes there is an analysis of ‘committee glass” and Saxony gunpowder, and remarks on calico printing and soap making, and soda from common salt. In July he again was in the Isle of Wight. Zit. 35 (1827). Faraday gave his first course of lectures in the theatre of the Institution in April on Chemical Philosophy. He writes:—‘‘The President and Council of the Royal Society ap- plied to the President and Managers of the Royal Institution for leave to erect on their premises an experimental room with a furnace, for the purpose of continuing the investigation on the manufacture of optical glass. They were guided in this by the desire which the Royal Institution has always evinced to assist in the advancement of science; and the readiness with which the application was granted showed that no mistaken notion had been formed in this respect. As a member of both bodies, I felt much anxiety that the investigation should be successful. A room and furnaces were built at the Royal Institution in September 1827, and an assistant was engaged, Sergeant Anderson of the Royal Artillery. He came on the 3rd of December.” He had four papers in the Quarterly Journal of Science :—1, on the Fluidity of Sulphur and Phosphorus at common temperatures. ‘In this,” he says, “I published some time ago [the year previous] a short account of an instance of the existence of fluid sulphur at common temperatures ; and though I thought the fact curious, I did not esteem it of such importance as to put more than my initials to the account. I have just learned through the ‘ Bulletin Universel’ for September, p. 78, that Signor Bellani had ob- served the same fact in 1813, and published it in the ‘ Giornale di Fisica.’ M. Bellani complains of the manner in which facts and theories which have been published by him are afterwards given by others as new discoveries ; and though I find myself classed with Gay-Lussac, Sir H. Davy, Daniell, and Bostock, in having thus erred, I shall not rest satisfied without making restitution, for M. Bellaniin this instance certainly deserves it at my hand.” 2, on the probable decomposition of certain gaseous compounds of carbon and hydrogen during sudden expansion ; 3, on transference of Heat by change of Capacity in Gas; and 4, Experiments on the Nature of Labarraque’s XX1V Disinfecting Soda Liquid. There were nineteen Friday evening meetings at the Royal Institution. Faraday gave an account of the magnetic pheno- mena developed by metals in motion, on the chemical action of chlorine and its compounds as disinfectants, and on the progress of the Thames tunnel. In this year he published his ‘“‘ Chemical Manipulations,” in one volume, 8vo. A second edition appeared in 1830, and a third in 1842. He was made a Correspondent of the Société Philomathique, Paris. Zt. 36 (1828). He had a few words in the Quarterly Journal on anhydrous crystals of sulphate of soda. He gave four of the Friday evening lectures: Illustra- tions of the new Phenomena produced by a current of Air or Vapour recently observed by M. Clement; on the reciprocation of Sound; and also a discourse on the Nature of Musical Sound. The matter belonged to Mr. Wheatstone, but was delivered by Mr. Faraday. The last evening was on the recent and present state of the Thames tunnel. He was made a Fellow of the Natural Society of Science of Heidelberg. He was invited to attend the meetings of the Board of Managers of the Institution ; and he received his first (gold) medal, one of a series of ten given to Members of the Royal Institution (as a reward for chemical dis- coveries) by Mr. John Fuller, a Member. 4Ht. 37 (1829). He gave the Bakerian lecture at the Royal Society on the Manufacture of Glass for Optical purposes. This most laborious investigation led to no good in the direction that was originally expected, but the use of the glass manufactured, as described afterwards, became of the utmost importance in his diamagnetic and mag- neto-optical researches, and it led to the permanent engagement, in 1832, of Mr. Charles Anderson as Faraday’s assistant in all his researches, “to whose rare steadiness, exactitude, and faithfulness in the performance of all that was committed to his charge Faraday was much indebted.” He gave Friday evening discourses on Mr. Robert Brown’s discovery of Active Molecules in bodies, either organic or inorganic; on Brard’s test of the action of weather on building stones ; on Wheatstone’s further investiga- tions on the resonances or reciprocal vibrations of volumes of air; on Bru- nel’s block machinery at Portsmouth ; on the phonical or nodal figures of elastic laminze ; on the manufacture of glass for optical purposes. He was made a member of the Scientific Advising Committee of the Admiralty, Patron of the Library of the Institution, Honorary Member of the Society of Arts, Scotland. At the end of June he writes to Colonel Drummond, Lieutenant-Governor of the Royal Academy, Woolwich :—‘‘I should be happy to undertake the duty of lecturmg on chemistry to the gentlemen cadets of Woolwich, pro- vided that the time I should have to take for the purpose from professional XXV business at home were remunerated by the salary. . . . . For these reasons [which he gives] I wish you would originate the terms rather than I. . . . . I consider the offer a high honour, and beg you to feel assured of my sense of it. I should have been glad to have accepted or declined it, independent of pecuniary motives; but my time is my only estate, and that which would be occupied in the duty of the situation must be taken from what otherwise would be given to professional business.” At Christmas he for the first time gave the Juvenile Lectures. Zit, 38 (1830). This year he had a paper in the Institution Journal supplementary to his former paper in 1826 on the limits of vaporization. His Friday evening discourses were on Aldini’s proposed method of pre- serving men exposed to flame; on the Transmission of Musical sounds through solid conductors and their subsequent reciprocation ; on the Flow- ing of Sand under Pressure; on the application of a New Principle in the Construction of Musical Instruments ; on the laws of Coexisting Vibrations in strings and rods, illustrated by the kaleidophone. The following recollections from about 1823 to 1830 are by Mrs. Fara- day’s youngest brother, Mr. George Barnard, the artist :— “‘ All the years I was with Harding I dined at the Royal Institution. After dinner we nearly always had our games just like boys—sometimes at ball, or with horse chestnuts instead of marbles, Faraday appearing to enjoy them as much as I did, and generally excelling us all. Sometimes we rode round the theatre on a velocipede (and tradition remains that in the earliest part of a summer morning Faraday has been seen going up Hamp- stead Hill on his velocipede). «« At this time we had very pleasant conversaziones of artists, actors, and musicians at Hullmandel’s, sometimes going up the river in his eight-oar cutter, cooking our own dinner, enjoying the singing of Garcia and his wife and daughter (afterwards Malibran), indeed of all the best Italian singers, and the society of most of the Royal Academicians, such as Stan- field, Turner, Westall, Landseer, &c. «* After Hullmandel’s excellent suppers, served on a dozen or two small tables in his large rooms, we had charades, Faraday and many of us tak- ing parts with Garcia, Malibran, and the rest. ‘My first and many following sketching trips were made with Faraday and his wife. Storms excited his admiration at all times, and he was never tired of looking into the heavens. He said to me once, ‘I wonder you artists don’t study the light and colour in the sky more, and try more for effect.’ I think this quality in Turner’s drawings made him admire them so much. He made Turner’s acquaintance at Hullmandel’s, and afterwards often had applications from him for chemical information about pigments. Faraday always impressed upon Turner and other artists the great necessity there was to experiment for themselves, putting washes and tints of all their pig- XXV1 ments in the bright sunlight, covering up one half, and noticing the effect of light and gases on the other. “On one of our sea-side excursions we were bathing together, when Fara- day, who wasa fair swimmer, on coming in was overtaken by a tremendous wave which overtopped his head, and dashed him with violence on the beach, bruising him much. He impressed on me never to think any one could stand against such a breaker; that one should turn round and dive through it, throwing one’s self off the ground. Faraday did not fish at all during these country trips, but just rambled about geologizing or botanizing.’’ If Faraday’s scientific life had ended here it might well have been called a noble success. He had made two leading discoveries, the one on electro-mag- netic motions, the other on the condensation of several gases into liquids. He had carried out two important and most laborious investigations on the alloys of steel and on the manufacture of optical glass. He had made many communications to the Royal Society, and many more to the Quar- terly Journal of Science. From assistant in the laboratory he had be- come its director. He was constantly lecturing in the great theatre, and he had probably prolonged the existence of the Royal Institution by taking the most active part in the establishment of the Friday evening meetings. But when we turn to the eight volumes of manuscripts of his ‘ Experi- mental Researches,’ which he bequeathed to the Royal Institution, we find that he was just goig to begin to work. The first of these large folio volumes begins in 1831 with paragraph 1, and continues in the seventh to paragraph 15,389 in 1856. The results of this work he has collected himself in four volumes octavo. The three volumes on elec- tricity were published in 1839, in 1844, and in 1855; the Jast volume, on chemistry and physics, he published in 1859. Whenever he was about to investigate a subject, he wrote out, on separate slips of paper, different queries regarding it which his genius made him think were “ naturally pos- sible’? to be answered by experiment. He slightly fixed them one beneath. another, in the order in which he intended to experiment. As a slip was answered it was removed, and others were added in the course of the in- vestigation, and these in their turn were worked out and removed. If no answer was obtained, the slip remained to be returned to at another time. Out of the answers the manuscript volumes were formed, and from these the papers were written for the Royal Society, where they were always read before the popular account of them was given to the Royal In- stitution at a Friday evening meeting. When nearly fifty years of age, he became so seriously troubled with want of memory and giddiness that he thought he should be unable to do any more, and in his most exact way he drew up the following table of the work he had given up temporarily during the first ten years that his experimental investigations in electricity had lasted :— XXVIll PEST May give up Haster lectures and all other busi- ness at Royal Institution. al meme (4 1 Gave up Friday evenings. — ee Ove b Gave up juvenile lectures. —|—|—— | |6e8 1 —|—|——|—| |e 1 Gave up Mr. Brande’s twelve morning lectures. —|—|—|— || |"8e81 Closed three days in the week. ? —|—|—|—_ ||| |se81 —|—|—_—|—|—|— |_| 21 © Gave up many morning lectures. Gave up the rest of professional business. a aC Ce (ee OS —_——_— —|— |__| — | see Gave up excise business. i @ w i | Declined reprinting ‘ Chemical Manipulation.’ Declined all dining-out invitations. | Gave up professional business in courts. Declined Council business at Royal Society. Zt. 39 (1831). In this year the first series of ‘ Experimental Researches in Electricity ’ was read to the Royal Society. It contained experiments (1) on the Induction of Electric Currents, (2) on the Evolution of Electricity from Magnetism, (3) on a new Electrical Condition of Matter, and on Arago’s Magnetic Phenomena. He had also in the Transactions a paper on a peculiar class of acoustical figures, and on certain forms assumed by groups of particles upon vibrating elastic surfaces. In the Quarterly Journal of Science he had a paper on a peculiar class of optical deceptions, which gave rise to the chromatrope. He gave five Friday discourses on a peculiar class of Optical Deceptions ; on Oxalamide, discovered by M. Dumas; on Light and Phosphorescence (being an account of experiments recently made in the Royal Institution by Mr. Pearsall, Chemical Assistant) ; on Trevelyan’s recent Experiments on the production of Sound during the conduction of Heat; and on the Arrangements assumed by Particles upon Vibrating Elastic Surfaces. He was elected an Honorary Member of the Imperial Academy of Sciences, Petersburg. In a letter to his friend, Richard Phillips, he first complains of his memory. ‘My memory gets worse and worse daily, I will not therefore say I have not received your Pharmacopeeia.”’ Three months later he thanks him for the last edition of the Pharmacopceia, and says, “1 am busy just now again on electro-magnetism, and think I have got hold of a good thing, but can’t say. Itmay be a weed instead of a fish that, after all my labour, I may at last pull up. I think I know why metals are magnetic when in motion, though not (generally) when at rest.” Nov. 29.—Two months later he again writes, and this time from XXVIl Brighton :—‘‘ We are here to refresh. I have been working and writing a paper that always knocks me up in health, but now I feel well again and able to pursue my subject, and now I will tell you what it is about. The title will be, I think, ‘ Experimental Researches in Electricity’ :—I. On the Induction of Electric Currents ; IJ. On the Evolution of Electri- city from Magnetism; IIT. On a new Electrical Condition of Matter ; IV. On Arago’s Magnetic Phenomena. There is a bill of fare for you, and, what is more, I hope it will not disappomt you. Now the pith of all this I must give you very briefly, the demonstrations you shall have in the paper when printed. “J. When an electric current is passed through one of two parallel wires, it causes at first a current in the same direction through the other, but this induced current does not last a moment, notwithstanding the in- ducing current (from the voltaic battery) is continued; all seems un- changed, except that the principal current continues its course. But wnen the current is stopped, then a return current occurs in the wire under induction, of about the same intensity and momentary duration, but in the opposite direction to that first formed. Hlectricity in currents there- fore exerts an inductive action like ordinary electricity, but subject to peculiar laws. The effects are a current in the same direction when the induction is established, a reverse current when the induction ceases, and a peculiar state in the interim. Common electricity probably does the same thing; but as it is at present impossible to separate the beginning and the end of a spark or discharge from each other, all the effects are simultaneous and neutralize each other. “TJ. Then I found that magnets would induce just like voltaic cur- rents, and by bringing helices and wires and jackets up to the poles of - magnets, electrical currents, were produced in them, these currents being able to deflect the galvanometer, or to make, by means of the helix, magnetic needles, or in one case even to give a spark. Hence the evolv- tion of electricity from magnetism. The currents were not permanent ; they ceased the moment the wires ceased to approach the magnet, because the new and apparently quiescent state was assumed just as in the case of the induction of current; but when the magnet was removed, and its in- duction therefore ceased, the return currents appeared as before. ‘These two kinds of induction I have distinguished by the terms volta-electric and magnefo-electric induction. Their identity of action and results is, I think, a very powerful proof of M. Ampére’s theory of magnetism. *‘ IIT. The new electrical condition which intervenes by induction between the beginning and end of the inducing current gives rise to some very curious results. It explains why chemical action or other results of electricity have never been as yet obtained in trials with the magnet. In fact the currents have no sensible duration. I believe it will explain perfectly the ¢ransfer- ence of elements between the poles of the pile in decomposition ; but this part of the subject I have reserved until the present experiments are com- XX1X pleted ; and it is so analogous, in some of its effects, to those of ‘Ritter’s secondary piles, De la Rive and Van Beck’s peculiar properties of the poles of a voltaic pile, that I should not wonder if they all proved ulti- mately to depend on this state. The condition of matter I have dignified . by the term Electrotonic, Tur Evecrroronic Strate. What do you think of that? Am I not a bold man, ignorant as I am, to coin words? but I have consulted the scholars, and now for IV. “TV. The new state has enabled me to make out and explain all Arago’s phenomena of the rotating magnet or copper plate. I believe, perfectly ; but as great names are concerned (Arago, Babbage, Herschel, &c.), and as I have to differ from them, I have spoken with that mo- desty which you so well know you and I and John Frost * have in common, and for which the world so justly commends us. I am even half afraid to tell you what it is. You will think I am hoaxing you, or else in your compassion you may conclude Iam deceiving myself. However, you need do neither, but had better laugh, as I did most heartily, when I found that it was neither attraction nor repulsion, but just one of my old rota- tions in a new form. I cannot explain to you all the actions, which are very curious; but in consequence of the electrotonic state being assumed and lost as the parts of the plate whirl under the pole, and in consequence of magneto-electric induction, currents of electricity are formed in the direc- tion of the radii,—continuing, for simple reasons, as long as the motion con- tinues, but ceasing when that ceases. Hence the wonder is explained that the metal has powers on the magnet when moving, but not when at rest. Hence is also explained the effect which Arago observed, and which made him contradict Babbage and Herschel, and say the power was re- pulsive; but, as a whole, it is really tangential. It is quite comfortable to me to find that experiment need not quail before mathematics, but is quite competent to rival it in discovery; and I am amazed to find that what the high mathematicians have announced as the essential con- dition to the rotaticn, namely, that time is required, has so little foun- dation, that if the time could by possibility be anticipated instead of beimg required, 7. e. if the currents could be formed before the magnet came over the place instead of after, the effect would equally ensue. Adieu, dear Phillips. Excuse this egotistical letter from yours, very faithfully.” | Ait. 40 (1832), The second series of Experimental Researches in Electricity was this year the Bakerian lecture on Terrestrial Magneto-electric Induction, and on the Force and Direction of Magneto-electric Induction generally. His Friday discourses were, (1) on Dr. Johnson’s Researches on the Re- productive Power of Planariz ; (2) recent experimental Investigation of Volta-electric and Mazgneto-electric Induction; (3) Magneto-electric In- * A pushing acquaintance, who, without claim of any kind, got himself presented at Court. XXX duction, and the explanation it affords of Arago’s Phenomena of Magne- tism exhibited by moving Metals; (4) Evolution of Electricity, naturally and artificially, by the inductive action of the Earth’s Magnetism ; (5) on the Crispation of Fluids lying on vibrating Surfaces ; and on Morden’s Machinery for manufacturing Bramah’s locks. He was made Hon. Member of Philadelphia College of Pharmacy, and of Chemical and Physical Society, Paris; Fellow of the American Aca- demy of Arts and Sciences, Boston ; Member of the Royal Society of Science, Copenhagen ; D.C.L. of Oxford University ; and he received the Copley medal. He collected the different papers, notes, notices, &c. published in octavo up to this year, and he added this preface to the volume :—“ Papers of mine published in octavo in the Quarterly Journal of Science and else- where, since the time that Sir H. Davy encouraged me to write the ‘ Analysis of Caustic Lime.’ Some I think (at this date) are good, others moderate, and some bad; but I have put all into the volume, because of the utility they have been to me, and none more than the bad im pointing out to me in future, or rather after times, the faults it became me to watch and avoid. As I never looked over one of my papers a year after it was written without believing, both in philosophy and manner, it would have been much better done, I still hope this collection may be of great use to me.” In December, the Royal Institution being in trouble, a committee re- ported on all the salaries. ‘‘ The Committee are certainly of opinion that no reduction can be made in Mr. Faraday’s salary, £100 per annum, house, coals, and candles, and beg to express their regret that the circumstances of the Institution are not such as to justify their proposing such an increase of it as the variety of duties which Mr. Faraday has to perform, and the zeal and ability with which he performs them, appear to merit.” Ait. 41 (1833). The third series of Experimental Researches contamed the Identity of Electricities derived from different sources, and the relation by measure of common and voltaic electricity. The fourth series consisted of a new law of Electric Conduction, and on Conducting-power generally. The fifth series was on Electro-chemical Decomposition, new conditions of Electro- chemical Decomposition, influence of Water in Electro-chemical Decom- position, and Theory of Electro-chemical Decomposition. The sixth series was on the Power of Metals and other Solids to induce the combination of gaseous bodies. He sent a short note to the editors of the Philosophical Magazine on a means of preparing the Organs of Respiration so as considerably to extend the time of holding the breath, with remarks on its application im cases in which it is required to enter an irrespirable atmosphere, and on the precautions necessary to be observed in such cases. XXX1 His Friday discourses were on the Identity of Electricity derived from different sources ; on the practical prevention of Dry Rot in Timber; on the investigation of the Velocity and Nature of the Electric Spark and Light by Wheatstone; on Mr. Brunel’s new mode of constructing Arches for - Bridges ; on the mutual relations of Lime, Carbonic Acid, and Water ; on a new law of Electric Conduction; and on the power of Platina and other solid substances to determine the combination of gaseous bodies. In the early part of the year Mr. Fuller had founded a professorship of chemistry at the Royal Institution, with a salary of about £100 a year. Mr. Faraday was appointed for his life, with the privilege of giving no lectures. He was made Corresponding Member of the Royal Academy of Sciences of Berlin, and Hon. Member of the Hull Philosophical Society. #t. 42 (1834). The seventh series of Experimental Researches was on Electro-chemical Decomposition (continued): on some general conditions of Electro-decom- position; on a new measure of Volta Electricity ; on the Primary and Secondary character of bodies evolved in Electro-decomposition ; on the definite nature and extent of Klectro-chemical Decomposition; on the absolute quantity of Electricity associated with the Particles or Atoms of Matter. The eighth series was on the Electricity of the Voltaic Pile, its source, quantity, and general characters; on simple Voltaic Circles; on the Intensity necessary for Electrolyzation ; on associated Voltaic Circles on the Voltaic Battery ; on the resistance of an Electrolyte to Electrolytic Action ; general remarks on the active Voltaic Battery. The ninth series was on the influence by induction of an Electric Current on itself, and on the inductive action of Electric Currents generally. He gave four Friday discourses, the first on the principle and action of Ericsson’s Caloric engine. The other lectures were on Hlectro-chemical Decomposition ; on the definite action of Electricity ; and on new appli- cations of the products of Caoutchouc. He was made Foreign Corresponding Member of the Academy of Sciences and Literature of Palermo. Ait, 43 (1835). The tenth series of Experimental Researches was on an improved form of the Voltaic Battery, some practical results respecting the Construction and Use of the Voltaic Battery. He gave Friday discourses on Melloni’s recent discoveries on Radiant Heat; on the Induction of Electric Currents; onthe Manufacture of Pens from Quills and Steel, illustrated by Morden’s machinery ; on the Condi- tion and Use of the Tympanum of the Ear. In July he went with Mrs. Faraday from Brighton to Dieppe, spending a week in Paris, and some days at Geneva; he stayed two days at Cha- mouni. He writes to his friend Magrath :—“ We are almost surfeited with XXXil magnificent scenery ; and for myself I would rather not see it than see it with an exhausted appetite. The weather has been most delightful, and everything in our favour, so that the scenery has been in the most beautiful condition. Mont Blanc, above all, is wonderful, and I could not but feel, what I have often felt before, that painting is very far beneath poetry in cases of high expression, of which this is one. No artist should try to paint Mont Blanc, it is utterly out of his reach. He | cannot convey an idea of it, and a formal map, or a common-place model, con- veys more intelligence, even with respect to the sublimity of the mountain, than his highest efforts can do; in fact he must be able to dip his brush in light and darkness before he can paint Mont Blane. Yet the moment one sees it Lord Byron’s expressions come to mind, and they seem to apply. The poetry and the subject dignify each other.” On the 20th of April Sir James South wrote to him to say that he would have a letter from Sir Robert Peel acquainting him with the fact that, had Sir R. Peel remained in office, a pension would have been givenhim. On the 23rd he wrote a letter to Sir James South, which, however, his father-in- law prevented him from sending. He said, ‘I hope you will not think that I am unconscious of the good you meant me, or undervalue your great exertions for me, when I say that I cannot accept a pension whilst I am able to work for my living. Do not from this draw any sudden conclusion that my opinions are such and such. I think that Government is right in rewarding and sustaining science. I am willing to think, since such approbation has been intended me, that my humble exertions have been worthy, and I think that scientific men are not wrong in accepting the pensions; but still I may not take a pay which is not for services per- formed whilst I am able to live by my labours.” In the ‘ Times’ of Saturday, 28th Oct. 1835, under the head of Tory and Whig Patronage to Science and Literature, is the we conver- sation, copied from Fraser’s Magazine :— ‘¢ Mr. F. I am here, my Lord, by your desire; am I to understand that it is on the business which I have partially discussed with Mr. Young? (Lord M.’s Secretary.) Lord Melbourne. You mean the pension, don’t you? Mr. F. Yes, my Lord. Lord M. Yes, you mean the pension, and I mean the pension too. I hate the name of the pension. I look upon the whole system of giving pensions to literary and scientific persons as a piece of gross humbug ; it was not done for any good purpose, and never ae to have been done. It is a gross humbug from beginning to end. F. (rising, and making a bow). After all this, my Lord, I perceive ae my business with your Lordship is ended. I wish you a good morning.” Faraday said that the report of this conversation was full of error ; however he wrote :— To the Blas Hon. Lord Viscount Melbourne, First Lord of the Treasury. ** October 26. “* My Lord,—The conversation with which your Lordship honoured me XXX11 this afternoon, including, as it did, your Lordship’s opinion of the general character of the pensions given of late to scientific persons, induces me respectfully to decline the favour which I believe your Lordship intends for me; for I feel that I could not, with satisfaction to myself, accept at your Lordship’s hands that which, though it has the form of approbation, is of the character which your Lordship so pithily applied to it.” This note, Mr. F. says, “was left by myself, with my card, at Lord Mel- bourne’s office on the same evening, 7. e. of the day of our conversation.” On the 6th of November Faraday wrote to Sir James South :— ** And now, my dear Sir, pray let me drop. .... I know you have serious troubles of your own. Do not let me be one any longer either to you or to others. You have my most grateful feelings for ali the kindness you have shown to him who is ever truly yours.” The intervention of Miss Fox and Lady Mary Fox, caused Lord Mel- bourne to write the following letter :— ** November 24. * Sir,—It was with much concern that I received your letter declining the offer which I considered myself to have made in the interview which I had with you in Downing Street, and it was with still greater pain that I col- lected from that letter that your determination was founded upon the cer- tainly imperfect, and perhaps too blunt and inconsiderate manner in which I had expressed myself in our conversation, I am not unwilling to admit that anything in the nature of censure upon any party ought to have been abstained from upon such an occasion; but I can assure you that my ob- servations were intended only to guard myself against the imputation of having any political advantage in view, and not in any respect to apply to the conduct of those who had or hereafter might avail themselves of a similar offer. I intended to convey that, although I did not entirely ap- prove of the motives which appeared to me to have dictated some recent grants, yet that your scientific character was so eminent and unquestionable as entirely to do away any objection which I might otherwise have felt, and to render it impossible that a distinction so bestowed could be ascribed to any other motive than a desire to reward acknowledged desert and to advance the interest of philosophy. “ T cannot help entertaining a hope that this explanation may be suffi- cient to remove any unpleasant or unfavourable impression which may have been left upon your mind, and that I shall have the satisfaction of receiving your consent to my advising His Majesty to grant to you a pen- sion equal in amount to that which has been conferred upon Professor Airy and other persons of distinction in science and literature.” The same day Faraday wrote:—‘‘My Lord, your Lordship’s letter, which I have just had the honour to receive, has occasioned me both pain and pleasure—pain, because I should have been the cause of your Lord- ship’s writing such a one, and pleasure, because it assures me that I am not unworthy of your Lordship’s regard. VOL. XVII. c XXXIV *« As, then, your Lordship feels that, by conferring on me the mark of approbation hinted at in your letter, you will be at once discharging your duty as First Minister of the Crown, and performing an act consonant with your own kind feelings, I hesitate not to say I shall receive your Lord- ship’s offer both with pleasure and with pride.” The pension was granted December 24, but in the interval he was much troubled by some, who thought that a contradiction to the injurious state- ment in the ‘Times’ against Lord Melbourne ought to be made. To one Faraday writes :—“ The pension is a matter of indifference to me, but other results, some of which have already come to pass, are not so. The continued renewal of this affair, to my mind, tempts me at times to what might be thought very ungenerous under the circumstances, namely, even at this late hour a determined refusal of the whole.” On the 8th of December he, however, published a letter in the ‘ Times,’ in which he says, “‘I beg leave thus publicly to state that neither directly nor indirectly did I communicate to the Editor of Fraser’s Magazine the information on which that article (an extract of which was published in the ‘Times’ of the 28th) was founded, or further, either directly or indirectly, any information to or for any publication whatsoever.” This year he-was made Corresponding Member of the Royal Academy of Medicine, Paris; Hon. Member of the Royal Society of Edinburgh, Institution of British Architects, and Physical Society of Frankfort ; Hon. Fellow of the Medico-Chirurgical Society of London; and he was awarded one of the Royal Medals by the Royal Society. Zit. 44 (1836). This year the whole course of Faraday’s scientific work was changed by his appointment as Adviser to the Trinity House. He published one paper in the Philosophical Magazine on the general Magnetic Relations and Cha- racters of the Metals, which he begins by saying, ‘‘ general views have long since led me to an opinion, which is probably also entertained by others, though I do not remember to have met with it, that all the metals are magnetic in the same manner as iron.” He gave four Friday discourses on Silicified Plants and Fossils; on Mag- netism of Metals as a general character; on Plumbago, and on Pencils, Morden’s Machinery ; and considerations respecting the nature of Chemical Elements. The 3rd of February he wrote to Capt. Pelly, Deputy Master of the Trinity House:— “I consider your letter to me as a great compliment, and should view the appointment at the Trinity Honse, which you propose, in the same light ; but I may not accept even honours without due consideration. “ In the first place, my time is of great value to me, and if the appoint- ment you speak of involved anything like periodical routine attendances, I do not think I could accept it. But it it meant that in consultation, in the XXXV examination of proposed plans and experiments, in trials, &c. made as my convenience would allow, and with an honest sense of a duty to be per- formed, then I think it would consist with my present engagements. You have left the title and the sum in pencil. These I look at mainly as regards the character of the appointment; you will believe me to be sincere in this, when you remember my indifference to your proposition as a matter of interest, though not us a matier of kindness. “Tn consequence of the goodwill and confidence of all around me I can at any moment convert my time into money, but I do not require more of the latter than is sufficient for necessary purposes. ‘The sum therefore of £200 is quite enough in itself, but not if it is to be the indicator of the cha- racter of the appointment; but I think you do not view it so, and that you and I understand each other in that respect ; and your letter confirms me in that opinion. The position which I presume you would wish me to hold is analogous to that of a standing counsel. « As to the title, it might be what you pleased almost. Chemical ad- viser is too narrow; for you would find me venturing into parts of the philosophy of light not chemical. Scientific adviser you may think too broad (or in me too presumptuous) ; and so it would be, if by it was under- stood all science. It was the character I held with two other persons at the Admiralty Board in its former constitution. “ The thought occurs to me whether, after all, you want such a person as myself. This you must judge of; but I always entertain a fear of taking an office in which I may be of no use to those who engage me. Your ap- _ plications are, however, so practical, and often so chemieal, that I have no great doubt in the matter.” On the 4th he was made Scientific Adviser in experiments on lights to the Corporation. For thirty years nearly he held this post. What he did may be seen in the portfolios, full of manuscripts, which Mrs. Faraday has given to the Tri- nity House, in which, by the marvellous order and method of his notes and indices, each particle of his work can be found and consulted immediately. His first work was to make a photometer. Throughout the whole year he was busy on the subject, making three photometers, and ascertaining the capability and accuracy of the instruments. He also experimented on the preparation of oxygen for the Bude light, drawing up the most exact tables for the record of the manufacture; for example, the 10th of November he says, “‘ hence oxygen costs very nearly twopence per cubical foot ; exactly 1-909 pence.” He was made Senator of the University of London ; Hon. Member of the Society of Pharmacy of Lisbon and of the Sussex Royal Institution ; Fo- reion Member of the Society of Sciences of Modena, and the Natural-His- tory Society of Basle. Zit. 45 (1837). This year the ‘Eleventh Series of Experimental Researches in Electricity’ e2 XXXV} was communicated to the Royal Society. It was on Induction: Induction an action of contiguous particles ; absolute charge of Matter ; Electrometer and Inductive Apparatus employed; Induction in Curved Lines; Specific Inductive Capacity ; general results as to Induction. His work for the Trinity House consisted in examining the Trinit y lamp, the French lamp, and the Bude lamp, as to intensity of light and price: ‘pressed Mr. Gurney, by letter, to give us his best iamp at once and not to lose time.” Two of his four Friday discourses were on the views of Pro- fessor Mossotti as to one general law accounting for the different Forces in Matter; on Dr. Marshall Hall’s views of the Nervous System. He was elected Honorary Member of the Literary and Scientific Institu- tion, Liverpool. Mit, 46 (1838). The twelfth series of Researches was published this year.—On Induction (continued) : Conduction or Conductive Discharge ; Electrolytic Discharge; Disruptive Discharge, Insulation, Spark, Brush, Difference of Discharge at the positive and negative surfaces of conductors. The thirteenth series was also on Induction (continued): Disruptive Discharge (continued). Pecu- liarities of positive and negative discharge either as spark or brush; Glow Discharge ; Dark Discharge. Convection or Carrying Discharge. Relation of a vacuum to Electrical Phenomena. Nature of the Electrical Current. The fourteenth series was on the nature of the Electric Force or Forces. Relation of the Electric and Magnetic Forces, and notes on Electrical Kxci- tation. The fifteenth series was a notice of the character and direction of the Electric Force of the Gymnotus. For the Trinity House he a second time reported on the new Gurney lamp, comparing it in light and cost with the French lamp. He gave four Friday discourses this year. He was made Honorary Member of the Institution of Civil Engineers ; Foreign Member of the Royal Academy of Sciences, Stockholm; and he oat the Copley Medal. Ait. 47 (1839). At the end of July he was four days at Orfordness for the Trinity House, measuring and comparing at sea and on land the Argand lamp, the French lamp, and the Bude lamp. He gave four Friday discourses, two of which were on the Electric powers of the Gymnotus and Silurus. An account of Gurney’s oxv-oil-iamp. During thirteen years, Miss Reid, a niece of Mrs. Faraday s, had lived at the Institution, and she has thus given her recollections of Mr. Faraday during these and the following six years :— ‘“‘There could be very few regular lessons at the Institution ; there were so many breaks and interruptions. Sometimes my uncle would give me a few sums to do, and he always tried to make me understand the why and wherefore of everything I did. Then occasionally he gave me a reading- lesson. How patient he was, and how often he went over and over the XXXVI same passage when I was unusually dense. He had himself taken lessons from Smart, and he used to practise reading with exaggerated emphasis oecasionally. “Tn the earlier days of the juvenile lectures he used to encourage me to tell him everything that struck me, and where my difficulties lay when I did not understand him fully. In the next lecture he would enlarge on those especial points, and he would tell me my remarks had helped him to make things clear to the young ones. He never mortified me by wondering at my ignorance, never seemed to think how stupid I was. I might begin at the very beginning again and again; his patience and kindness were un- failing. ** A visit to the laboratory used to be a treat when the busy time of the day was over. «We often found him hard at work on experiments connected with his researches, his apron full of holes. If very busy he would merely give a nod, and aunt would sit down quietly with me in the distance, till pre- sently he would make a note on his slate and turn round to us for a talk, or perhaps he would agree to come upstairs to finish the evening with a game at bagatelle, stipulating for half an hour’s quiet work first to finish his experiment. He was fond of all ingenious games, and he always ex- celled in them. For a time he took up the Chinese puzzle, and, after making all the figures in the book, he set to work and produced a new set of figures of his own, neatly drawn, and perfectly accurate in their propor- ticns, which those in the book were not. Another time, when he had been unwell, he amused himself with Papyro-plastics, and with his dexterous fingers made a chest of drawers and pigeon-house, &c. «When dull and dispirited, as sometimes he was to an extreme degree, my aunt used to carry him off to Brighton, or somewhere, for a few days, and they generally came back refreshed and invigorated. Once they had very wet weather in some out of the way place, and there was a want of amusement, so he ruled a sheet of paper and made a neat draught-board, on which they played games with pink and white lozenges for draughts. But my aunt used to give up almost all the games in turn, as he soon be- eame the better player, and, as she said, there was no fun in being always beaten. At bagatelle, however, she kept the supremacy, and it was long a favourite, on account of its being a cheerful game requiring a little moving about. | «‘ Often of an evening they would go to the Zoological Gardens and find interest in all the animals, especially the new arrivals, though he was al- ways much diverted by the tricks of the monkeys. We have seen him laugh till the tears ran down his cheeks as he watched them. He never missed seeing the wonderful sights of the day—acrobats and tumblers, giants and dwarfs; even Punch and Judy was an unfailing source of delight, whether he looked at the performance or at the admiring gaping crowd. “He was very sensitive to smells; he thoroughly enjoyed a cabbage XXXVI rose, and his friends knew that one was sure to be a welcome gift. Pure Eau de Cologne he liked very much; it was one of the few luxuries of the kind that he indulged in; musk was his abhorrence, and the use of that scent by his acquaintance annoyed him even more than the smell of tobacco, which was sufficiently disagreeable to him. The fumes from a candle or oil-lamp going out would make him very angry. On returning home one evening, he found his rooms full of the odious smell from an expiring lamp ; he rushed to the window, flung it up hastily, and brought down a whole row of hyacinth-bulbs and flowers and glasses. *“Mr. Magrath used to come regularly to the morning lectures, for the sole purpose of noting down for Mr. F. any faults of delivery or defective pronunciation he could detect. The list was always received with thanks ; although his corrections were not uniformly adopted, he was encouraged to continue his remarks with perfect freedom. In early days he always lec- tured with a card before him with Slow written upon it in distinct cha- racters. Sometimes he would overlook it and become too rapid ; in this case Anderson had orders to place the card before him. Sometimes he had the word ‘ Time’ ona card brought forward when the hour was nearly expired.” Et. 48 (1840). Early in this year the sixteenth series of Experimental Researches ap- peared. It was on the Source of Power in the Voltaic Pile:—1. Exciting electrolytes, &c., being conductors of thermo and feeble currents ; 2. Inac- tive Conducting Circles containing an electrolytic fluid; 3. Active Circles excited by solution of Sulphuret of Potassium. The seventeenth series came afew days after. Also on the Source of Power in the Voltaic Pile (continued): 4. The exciting Chemical Force by temperature; 5. The ex- citing Chemical Force affected by dilution; 6. Differences in the Order of the Metallic Elements of Voltaic Circles; 7. Active Voltaic Circles and Batteries without metallic contact; 8. Considerations of the sufficiency of chemical action; 9. Thermoelectric evidence; 10. Improbable nature of the assumed Contact Force. He gave three Friday discourses. The previous year, Dr. Hare, Professor of Chemistry in the University of Pennsylvania, wrote his objections to Faraday’s theoretical opinions on Static Induction. At the end of Faraday’s reply, he says: —“‘The paragraphs which remain unanswered refer, I think, only to differences of opinion, or else not even to differences, but opinions regarding which I have not ventured to judge. These opinions I esteem of the utmost importance ; but that is a reason which makes me the rather desirous to decline entering upon their consideration, inasmuch as on many of their connected points I have formed no decided notion, but am constrained by ignorance and the contrast of facts to hold my judgment as yet in suspense. It is indeed to me an annoying matter to find how many subjects there are in electrical science on which, if I were asked for an opinion, I should have to say I XXX1X cannot tell—I do not know; but, on the other hand, it is encouraging to think that these are they which, if pursued industriously, experimentally, and thoughtfully, will lead to new discoveries. Sucha subject, for instance, occurs in the currents produced by dynamic induction, which you say it will be admitted do not require for their production intervening ponderable atoms. For my own part, I more than half incline to think they do re- quire these intervening particles. But on this question, as on many others, I have not yet made up my mind.” On the Ist of January the following year, Dr. Hare sent a reply. In Faraday’s answer to this, he says:—‘ You must excuse me, however, for several reasons, from auswering it at any length. The first is my distaste for controversy, which is so great that I would on no account our corre- spondence should acquire that character. I have often seen it do great harm, and yet remember few cases in natural knowledge where it has helped much either to pull down error or advance truth. © Criticism, on the other hand, is of much value; and when criticism such as yours has done its duty, then it is for other minds than those either of the author or critic to decide upon and acknowledge the right.” This year he reported to the Trinity House on the necessity and method of examining lighthouse dioptric arrangements, and he had to examine the apparatus intended for Gibraltar. Between Purfleet and Blackwall he made a long comparison between English and French reflecting lamps and between English and French refracting prisms. To Professor Auguste De la Rive, the son of his early friend, he wrote :— “Though a miserable correspondent I take up my pen to write to you, the moving feeling being a desire to congratulate you on your discernment, perseverance, faithfulness, and success in the cause of Chemical Excitement of the current in the Voltaic Battery. You will think it is rather late to do so; but not under the circumstances. For along time I had not made up my mind; then the facts of definite electrochemical action made me take part with the supporters of the chemical theory, and since then Marianini’s paper with reference to myself has made me read and experi- ment more generally on the point in question. In the reading, I was struck to see how soon, clearly, and constantly you had and have sup- ported that theory, and think your proofs and reasons most excellent and convincing. ‘The constancy of Marianini and of many others on the opposite side made me, however, think it not unnecessary to accumulate and record evidence of the truth, and I have therefore written two papers, which I shall send you when printed, in which I enter under your banners.as re- gards the origin of electricity or of the current in the pile. My object in experimenting was, as I am sure yours has always been; not so much to support a given theory as to learn the natural truth; and having gone to the question unbiassed by any prejudices, I cannot imagine how any one _ whose mind is not preoccupied by a theory, or a strong bearing to a theory, can take part with that of contact against that of chemical action. How- xl ever, I am perhaps wrong saying so much, for, as no one is infallible, and as the experience of past times may teach us to doubt a theory which seems to be most unchangeably established, so we cannot say what the future may bring forth in regard to these views.” He was made Member of the American Philosophical Society, Phila- delphia, and Honorary Member of the Hunterian Medical Society, Edin- burgh. He was in the autumn of this year ordained Elder in the Sandemanian Church, and he held the office three years and a half. 4Et. 49 (1841). On the 2nd of September Faraday went down to St. Catherine’s lighthouse in the Isle of Wight, to remedy the condensation of moisture on the glass in theinside. On the 6th he returned home, “quite satisfied with the chimney, and have no doubt we shall have a lantern quite clear from sweat, and also much cleaner, both as to the mirrors and roof, from soot and blackness, than heretofore.” The 30th of June he left London for three months, with Mrs. Faraday and Mr. and Mrs. George Barnard, for Ostend and Switzerland. The journal which he kept contains many most beautiful descriptions. That of Brientz Lake and the Giessbach is perhaps one of the most striking :—“‘ George and I crossed the lake in a boat to the Giessbach, he to draw and I to saunter. The day was fine, but the wind against the boat; and these boats are so cumbrous, and at the same time expose so much surface to the air, that we were about two hours doing the two miles, with two men and occa- sionally our own assistance at the oar. We broke the oar-band ; we were blown back and sideways. We were drawn against the vertical rock in a place where the lake is nearly 1000 feet deep ; and I might tell a true tale, which would sound very serious, yet after all there was nothing of any con- sequence but delay. But such is the fallacy of description. We reached the fall and found it in its grandeur; for, as much rain fell last night, there was perhaps half as much more water than yesterday. This most beautiful fall consists of a fine river, which passes by successive steps down a very deep precipice into the lake. In some of these steps there is a clear leap of water 100 feet or more; in others, most beautiful combinations of leap, cataract, and rapid—the finest rocks occurring at the sides and bed of the torrent. In one part a bridge passes over it; m another a cavern and path occur under it. To-day every fall was foaming from the abun- dance of water, and the current of wind brought down by it was in some parts almost too strong to stand against. The sun shone brightly, and the rainbows seen from various parts were very beautiful. One at the bottom of a fine but furious fall was very pleasant; there it remained motionless, whilst the gusts and clouds of spray swept furiously across its place and were dashed against the rock. It looked like a spirit strong in faith and steadfast in the midst of the storm of passions sweeping across it; and xli though it might fade and revive, still it held on to the rock as in hope and giv- ing hope, and the very drops which, in the whirlwind of their fury, seemed as if they would carry all away, were made to revive it and give it greater beauty. How often are the things we fear and esteem as troubles made to become blessings to those who are led to receive them with humility and patience ! In one part of the fall the effect of the current of air was very curious. The great mass of water fell into a foaming basin, but some diverted por- tions struck the rock opposite the observer, and, collecting, left it at the various projecting parts ; but, instead of descending, these hundred little streams rushed upwards into the air, as if urged by a force the reverse of gravity ; and as there was little other spray in this part, it did not at first occur to the mind that this must be the effect of a powerful current of air, which, having been brought down by the water, was returning up that face of the rock.” Into the pages of this journal he has fixed, with the most extreme neat- ness, the different mountain-flowers that he gathered in his walks. Mrs. Faraday wrote for him part of a letter to Mr. Magrath :—‘“ I think Mr. Young would be quite satisfied with the way my husband em- ‘ploys his time. He certainly enjoys the country exceedingly ; and though at first he lamented our absence from home and friends very much, he seems now to be reconciled to it as a means of improving his general health. His strength is, however, very good. He thinks nothing of walking thirty miles in a day, and one day he walked forty-five, which I protested against _ his doing again, though he was very little the worse for it. I think that is too much. What would Mr. Young say to that ; but the grand thing is rest and relaxation of mind, which he is really taking.’’ He finishes the letter himself :—‘‘ Though my wife’s letter will tell you pretty well all about us, yet a few lines from an old friend (though somewhat worn out) will not be unpleasant to one who, like that friend, is a little the worse for time and hard wear. However, if you jog on as well as we do, you will have no cause for grumbling, by which I mean to say that I certainly have not ; for the comforts that are given me, and, above all, the continued kind- ness, affection, and forbearance of friends towards me, are, I think, such as few experience. ...... Remember me most kindly to Mr. Young. I will give no opinion at present as to the effect of his advice on my health and memory ; but I can have only one feeling as to his kindness, and, whatever I may forget, [ think I shall not forget that. ...... Now, as to the main point of this trip, ¢.e. the mental idleness, you can scarcely imagine how well I take to it, and what a luxury it is. The only fear I have is that when I return friends will begin to think that I shall overshoot the mark ; for feeling that any such exertion is a strain upon that faculty, which I cannot hide from myself is getting weaker, namely, memory, and feeling that the less exertion 1 make to use that the better I am in health and head, so my desire is to remain indolent, mentally speaking, and to retreat _ from a position which should only be held by one who has the power as xlu well as the will to be active. All this, however, may be left to clear itself up as the time proceeds.” 4Gt. 50 (1842). . He resumed the Friday evening lectures, and gave one on the Conduc- tion of Electricity in Lightning-rods, and one on the Principles and Practice of Hullmandel’s Lithotint. This year he made four reports to the Trinity House :—1, on comparison of the amount of Light cut off by French glass and by Newcastle glass ; 2, on a new Mode of suspending the Mirrors ; 3, its application to the Lundy Lighthouse, so as to save light ; 4, a Report on the Ventilation of the Tynemouth Light ; and he went to see the opera- tion of the grinding-apparatus for lenses at Newcastle. To Dr. T. M. Browne, who had asserted the isomerism of carbon and silicon, and who asked Faraday to witness his experiments and give him a_ written testimonial if they were satisfactory, he writes :—‘‘ That which made me inaccessible to you makes me so in a very great degree to all my friends—ill health connected with my head ; and I have been obliged, and I am still, to lay by nearly all my own pursuits, and to deny myself the pleasure of society, either in seeing myself in my friends’ houses or them here. This alone would prevent me from acceding to your request. I should, if I assented, do it against the strict advice of my friends, medical and social. ‘‘The matter of your request makes me add a word or two, which I hope you will excuse. Any one who does what you ask of me, 2. e. certify if the experiment is successful, is bound, without escape, to certify and publish also if ¢¢ fail; and I think you may consider that very few persons would be willing to do this. I certainly would not put myself in such a most un- pleasant condition.” This year he was made Chevalier of the Prussian Order of Merit (one of thirty), and Foreign Associate of the Royal Academy of Sciences, Berlin. Ast. 51 (1843). Early this year he sent the eighteenth series of his ‘ Researches’ to the Royal Society. It was on the electricity evolved by the friction of water and steam against other bodies. This had been first observed by Sir W. Armstrong, and was attributed to evaporation, and was thought to be related to atmospheric electricity. He concluded, ‘‘ the cause being, I believe, fric- tion, has no effect in producing, and is not connected with, the general electricity of the atmosphere.” He read a paper at the Institution of Civil Engineers on the ventilation of lighthouse lamps, the points necessary to be observed, and the manner in which these have been, or may be, attained. He gave three Friday discourses on some Phenomena of Electric In- duction; on the Ventilation of Lamp-burners, and on the Electricity of Steam. For the Trinity House he went to the South Foreland lighthouses re- xh garding their ventilation. He inspected the dioptric light of the first order, which had just been constructed in France and put up by French work- men, and compared its consumption of oil with the 15 Argand burners which were previously in use. He sent to the Philosophical Magazine a paper on Static Electrical Indue- tive Action. Among his notes the following occurs :—“ Propose to send to the Phil. Mag. for consideration the subject of a bar, or circular, or spherical magnet—first, in the strong magnetic field; then charged by it; and, finally, taken away and placed in space. Inquire the disposition of the dual foree, the open or the related powers of the poles externally, and if they can exist un- related. The difference between the state of the power, when related and when not, consistent with the conservation of force. Avoid any particular language. Should not pledge myself to answer any particular observations, or to any one, against open consideration of the subject. Want to direct the thoughts of ail upon the subject, and to tie it there; and especially to gather for myself thought on the point of relation or non-relation of the antithetical force or polarities.” He was made Honorary Member of the Literary and Philosophical Society of Manchester, and Useful Knowledge Society, Aix la Chapelle. Zit. 52 (1844). He communicated to the Royal Society a paper on the Liquefaction and Solidification of Bodies generally existing as Gases. His object was to sub- ject the gases to considerable pressure, with considerable depression of temperature. Though he did not condense oxygen, hydrogen, or nitrogen, the original objects of his pursuit, he added six substances, usually gaseous, to the list of those that could previously be shown in the liquid state, and he reduced seven, including ammonia, nitrous oxide, and sulphuretted hy- drogen, into the solid fori. He sent to the Philosophical Magazine a speculation touching electric conduction and the nature of matter. “DT he calls this ‘‘ a speculation respecting that view of the nature of matter which considers its ultimate atoms as centres of force, and not as so many little bodies surrounded by forces, the bodies being considered in the abstract as independent of the forces, and capable of existing without them. In the latter view these little particles have a definite form and a certain limited size. In the former view such is not the case ; for that which represents size may be considered as extending to any distance to which the lines of force of the particle extend. The particle, indeed, is supposed to exist only by these forces, and where they are it is.” This was the subject of his first Friday discourse. He also gave the last discourse on recent improvements in the Manufacture and Silvering of Mirrors. For the Trinity House he only examined different cottons for the lamps. xliv In October he was sent by Sir James Graham with Mr. Lyell to attend the inquest on those who had died by the explosion in the Haswell colliery. The following account is by Sir Charles :— “Faraday undertook the charge with much reluctance, but no sooner had he accepted it than he seemed to be quite at home in his new vocation. He was seated near the coroner, and cross-examined the witnesses with as much talent, skill, and self-possession as if he had been an old practitioner at the bar. We spent eight hours, not without danger, in exploring the galleries where the chief loss of life had been incurred. Among other questions, Faraday asked in what way they measured the rate at which the current of air flowed in the mine. An inspector took a small pinch of gun- powder out of a box, as he might have taken a pinch of snuff, and allowed it to fall gradually through the flame of a candle which he held in the other hand. His companion, with a watch, marked the time the smoke took going a certain distance. Faraday admitted that this plan was suf- ficiently accurate for their purpose ; but, observing the somewhat careless manner in which they handled their powder, he asked where they kept it. They said they kept it in a bag, the neck of which was tied up tight. But where, said he, do you keep the bag? you are sitting on it was the reply ; for they had given this soft and yieldmg seat, as the most comfortable one at hand, to the Commissioner. He sprang up on his feet, and, in a most animated and expressive style, expostulated with them for their carelessness, which, as he said, was especially discreditable to those who should be setting an example of vigilance and caution to others who were hourly exposed to the danger of explosions. ...... Hearing that a subscription had been opened for the widows and orphans of the men who had perished by the explosion, I found, on inquiry, that Faraday had already contributed largely. On speaking to him on the subject, he apologized for having done so without mentioning it to me, saying that he did not wish me to feel myself called upon to subscribe because he had done so.” To a lady of the highest talent, who proposed to become his disciple, to go through with him all his own experiments, he wrote :—“ That I should rejoice to aid you in your purpose you cannot doubt, but nature is against you. You have all the confidence of unbaulked health and youth, pati’ in body and mind. Iam a labourer of many years’ standing, made daily to feel my wearing out. You, with increasing acquisition of knowledge, en- large your views and intentions. I, though I may gain from day to day some little maturity of thought, feel the decay of powers, and am constrained to a continual process of lessening my intentions and contracting my pur- suits. Many a fair discovery sinnil before me in thought which I once intended, and even now desire, to work out; but I lose all hope respecting them when I turn my thoughts to that one which is in hand, and see how slowly, for want of time and physical power, it advances, and how likely it is to be not only a barrier between me and the many beyond in intellectual xly view, but even the last upon the list of those practically wrought out. Un- erstand me in this; [ am not saying that my mind is wearing out, but those physico-mental faculties by which the mind and body are kept in conjunction and work together, and especially the memory, fail me, and hence a limitation of all I was once able to perform with a much smaller extent than hereto- fore. It is this which has had a great effect in moulding portions of my later life, has tended to withdraw me trom the communion and pursuits of men of science my cotemporaries, has lessened the number of points of in- vestigation (that might at some time have become discoveries) which I now pursue, and which, in conjunction with its effects, makes me say most un- willingly that I dare not undertake what you propose—to go with you through even my own experiments. You do not know, and should not now but that I have no concealment on this point from you, how often I have to go to my medical friend to speak of giddiness and aching of the head, aud how often he has to bid me cease from restless thoughts and mental occupation and retire to the seaside to inaction. You speak of religion, and here you willbe sadly disappointedin me. You will perhaps remember that I guessed, and not very far aside, your tendency in this respect. Your confidence in me claims in return mine to you, which, indeed, I have no hesitation to give on fitting occasions ; but these I think are very few, for in my mind religious conversation is generally in vain. There is no philo- sophy in my religion. Iai of avery small and despised sect of Christians, known, if known at all, as Sandemanians, and our hope is founded on the faith that isin Christ. But though the natural works of God can never by any possibility come in contradiction with the higher things which be- long to our future existence, and must with everything concerning him ever glorify him, still I do not think it at all necessary to tie the study of the natural sciences and religion together; and in my intercourse with my fellow creatures that which is religious and that which is philosophical have ever been two distinct things.”’ in answer to Mr. Magrath, who sent him, from the ‘ Journal des Débats,’ notice of his election as one of the eight foreign associates of the Academy of Sciences, Paris, he said :—‘‘I received by this morning’s post notice of the event in a letter from Dumas, who wrote from the Academy at the moment of the deciding the ballot, and, to make it more pleasant, Arago directed it on the outside.” He was also made Honorary Member of the Sheffield Scientific Society. Ait. 53 (1845). This year produced the nineteenth series of Researches on the Magnetiza- tion of Light and the Illumination of Magnetic Lines of Foree:—1. Action of Magnets on Light ; 2. Action of Electric Currents on Light ; 3. General considerations. Also the twentieth series, on new Magnetic Actions, and on the Magnetic Conditions of all Matter :—1. Apparatus required ; 2. Action of magnets on heavy glass; 3. Action of Magnets on other substances act- xlvi ing magnetically on light; 4. Action of Magnets on the Metals generally. And the twenty-first series, on new Magnetic Actions, and on the Magnetic Condition of all Matter (continued) : 5. Action of Magnets on the ] Darcie Metals and their compounds; 6. Action of Magnets on Air and Gases ; 7. General considerations. For the Trinity House he made a long and exact comparison of the con- sumption and light of sperm and rape-oil. He gave a Friday discourse on the Condition and Ventilation of the Coal-mine Goaf, and another on the liquefaction and solidification of bodies usually gaseous ; another on ana- static painting, and on the Artesian well in Trafalgar Square. Karly in the year he thus wrote to Prof. Men De la Rive :—“ I have waited and waited for a result, intending to write off to you on the instant, and hoping by that to give a little value to my letter, until now, when the time being gone and the result not having arrived, I am in a worse condi- tion than ever; and the only value my letter can have will be in the kind- ness with which you will receive it. The result I hoped for was the con- densation of oxygen; but though I have squeezed him with a pressure of 60 atmospheres at the temperature of 140° F. below 0°, he would not settle down into the liquid or solid state ; and now, being tired and ill and obliged to prepare for lectures, I must put the subject aside for a little while. “‘ Nitrogen is certainly a strange body. It encourages every sort of guess about its nature and wili satisfy none. I have been try ing to look at it in the condensed state, but as yet it escapes me. “JT thank you most truly, not only for the invitation (to the scientific meeting) you have sent me, but for all the favour you would willingly show me. Do you remember one hot day (I cannot tell how many years ago) when I was hot and thirsty in Geneva, and you took me to your house in the town and gave me a glass of water and raspberry vmegar? That glass of drink is refreshing to me still.” Late in the year he writes to M. De la Rive :—“‘I have had your last letter by me for several weeks intending to answer it, but absolutely I have not been able; for of late I have shut myself up in my laboratory and wrought to the exclusion of everything else... .... Iam still so involved in discovery that I have hardly time for my meals, and am here at Brighton both to refresh and work my head at once; and I feel that unless I had been here and been careful I could not have continued my labours. _The consequence has been that last Monday I announced to our members at the Royal Institution another discovery, of which I will give you the pith. ‘‘ Many years ago I worked upon optical glass, and made a vitreous com- pound of silica, boracic acid, and lead, which I will now call heavy glass. It was this substance that enabled me first to act upon light by magnetic and electric forces. Now, if a square bar of this substance, about half an inch thick and two inches long, be very freely suspended between the poles of a powerful horseshoe electromagnet, immediately that the magnetic force is developed, the bar points, but it does not point from pole to pole, but equa- xlvii torially or across the magnetic lines of force, 7. e. east and west in respect of the north and south poles. If it be moved from this position it returns to it, and this continues as long as the magnetic force is in action. ‘This effect is the result of a still simpler action of the magnet on the bar than what appears by the experiment, and which may be obtained at a single magnetic pole. For if a cubical or rounded piece of the glass be suspended by a fine thread 6 or 8 feet long, and allowed to hang very near a strong magneto-electric pole (not as yet made active), then, on rendering the pole magnetic, the glass will be repelled until the magnetism ceases. This effect and power I have worked out through a great number of its forms and strange consequences, and they will occupy two series of the ‘ Experimental Researches.’ It belongs ¢o all matter (not magnetic as iron) without excep- tion; so that every substance belongs to one or the other class of magnetic or diamagnetic bodies. The law of action in its simplest form is that such matter tends to go from strong to weak points of magnetic force, and in doing this the substance will go in either direction along the magnetic curves, or in either direction across them. It is curious that amongst the metals are found bodies possessing this property in as high a degree as perhaps any other substance ; in fact I do not know at present whether heavy glass, or bismuth, or phosphorus is the most striking in this respect.” In July he went with Mrs. Faraday and Mr. G. Barnard to France for three weeks, partly to inspect the lighthouses at Fecamp, Havre, Harfleur, and Cap dela Haye. His chief object was to be received into the Academy. At the same time he gained all the information he could regarding French lighthouses from M. H. Le Ponte aud M. Fresnel. M. Dumas was his most constant companion in his visits to Chevreul, Milne-Edwards, Biot, Arago, the Well of Grenelle, and the water-works at Chaillot. On the 30th of July he went to the Institute. ‘“ Many of the members were gone out of town, but all that were there received me very kindly. I was glad to see Thenard, Dupuis, Flourens, Biot, Dumas of course, and Arago, Elie de Beaumont, Poinsot, Babinet, and a great many others whose names and faces sadly embarrassed my poor head and memory. Chatting together, Arago told me he was my senior, being born in 1786, and consequently 59 years of age.” He finishes his journal thus :—‘‘ We left George at the London Bridge Station ; thanks be to him for all his kind care and attention on the journey, which is better worth remembering than anything else of all that which occurred in it.” He was made Corresponding Member of the National Institute, Wash- ington, and of the Société d’ Encouragement, Paris. Ait. 54 (1846). Early in the year he gave a Friday discourse on the relation of Magnetism and Light, and another on the Magnetic Condition of Matter, and, later in xlviil the season, another on Wheatstone’s Electro-magnetic Chronoscope, at the end of which he said he was induced to utter a speculation long on his mind, and constantly gaining strength, viz. that perhaps those vibrations by which radiant agencies, such as light, heat, actinic influence, &c., convey this force through space, are not vibrations of an ether, but of the lines of force which, in his view, equally connect the most distant masses together and make the smallest atoms or particles by their properties influential on each other and perceptible to us. A little later he sends these views to the Philosophical Magazine as thoughts on ray vibrations ; “ but, from first to last, understand that I merely throw ont, as matter for speculation, the vague impressions of my mind; for I give nothing as the result of sufficient consideration or as the settled conviction, or even probable conclusion, at which I had arrived.’ His last Friday discourse was on the Cohesive Force of Water. He reported to the Trinity House on drinking-water of the Smalls Lighthouse, and on a ventilation apparatus for rape-oil lamps. To the Secretary of the Institution, who consulted him regarding evening lectures, he said, “‘I see no objection to evening lectures if you can find a fit man to give them. As to popular lectures (which at the same time are to be respectable and sound), none are more difficult to find. Lectures which really teach will never be popular; lectures which are popular will never really teach. They know little of the matter who think science is more easily to be taught or learned than ABC; and yet whoever learned his A B C without pain and trouble? Still lectures can (generally) inform the mind and show forth to the attentive man what he really has to learn, and in their way are very useful, especially to the public. I think they might be useful to us now, even if they only gave an answer to those who, judging by their own earnest desire to learn, think much of them. As to agricultural chemistry, it is no douht an excellent and a popular subject ; but I rather suspect that those who know least of it think that most is kuown about it.” He received both the Rumford and a Royal Medal, and was made Hsnorary Member of the Society of Sciences, Vaud. Zit. 55 (1847). He gave Friday discourses on the Combustion of Gunpowder; on Mr. Barry’s mode of ventilating the New House of Lords ; and on the Steam-jet chiefly as a means of procuring ventilation. He reported to the Trinity House on the ventilation of the South Foreland lights, and on a proposal.to light buoys by platinum wire ignited by electricity. He writes to the First Lord of the Admiralty from Edinburgh :—“ For years past my health has been more and more affected; and the place affected is my head. My medical advisers say it is from mental occupa- tion. The result is loss of memory, confusion, and giddiness; the sole tad xlix remedy, cessation from such occupation and head rest. I have in conse- quence given up, for the last ten years or more, all professional occupation, and voluntarily resigned a large income that I might pursue in some degree my own objects of research. But in doing this I have always, as a good subject, held myself ready to assist the Government if still in my power— not for pay, for, except in one instance (and then only for the sake of the person joined with me), I refused to take it. I have had the honour and pleasure of applications, and that very recently, from the Admiralty, the Ordnance, the Home Office, the Woods and Forests, and other departments, all of which I have replied to, and will reply to as long as strength is left me; and now it is to the condition under which I am obliged to do this that I am anxious to call your Lordship’s attention in the present case. I shall be most happy to give my advice and opinion in any case as may be at the time within my knowledge or power, but I may not undertake to enter into investigations or experiments. If I were in London I would wait upon your Lordship, and say all I could upon the subject of the dis- infecting fluids, but I would not undertake the experimental investigation ; and in saying this I am sure that I shal! have your sympathy and appro- bation when I state that it is now more than three weeks since I left London to obtain the benefit of change of air, and yet my giddiness is so little alleviated that I don’t feel in any degree confident that I shall ever be able to return to my recent occupations and duties.” To Professor Schonbein he writes, three months later :—‘‘ I shame to say that I have not yet repeated the experiments (on ozone), but my head has been so giddy that my doctors have absolutely forbidden me the pri- vilege and pleasure of working or thinking for a while; and so I am constrained to go out of town, be a hermit, and take absolute rest. In thinking of my own case it makes me rejoice to know of your health and strength, and look on whilst you labour with a constancy so unremitting and so successful.” He was made Member of the Academy of Sciences, Bologna, Foreign Associate of the Royal Academy of Sciences, Belgium, Fellow of the Royal Bayarian Academy of Sciences, Munich, and Correspondent of the Aca- demy of Natural Sciences, Philadelphia. Ast. 56 (1848). He this year communicated his twenty-second series of ‘ Researches’ as the Bakerian lecture. It was on the Crystalline Polarity of Bismuth (and other bodies), and on its relation to the Magnetic form of Force. 1. Crys- talline Polarity of Bismuth ; 2. Crystalline Polarity of Antimony ; 3. Crys- talline Polarity of Arsenic. The second part of this series on the same _ subject was (4) on the Crystalline Condition of various bodies, and (5) Na- ture of the Magnecrystallic Force, and general observations. ** T cannot conclude this series of Researches,” he says, ‘‘ without remark- ing how rapidly the knowledge of molecular forces grows upon us, and VOL. XVII. d ] how strikingly every investigation tends to develope more and more their importance and their extreme attraction as an object of study. A few years ago magnetism was to us an occult power affecting only a few bodies ; now it is found to influence all bodies, and to possess the most intimate relations with electricity, heat, chemical action, light, crystallization, and, through it, with the forces concerned in cohesion; and we may, in the present state of things, well feel urged to continue in our labours, en- couraged by the hope of bringing it into a bond of union with gravity itself.” He gave three Friday discourses on the Diamagnetic Condition of Flame and Gases; on two recent inventions of Artificial Stone; and on the Con- version of Diamond into Coke by the tlectric Flame. He was made Foreign Honorary Member (one of eight) of the Imperial Academy of Sciences, Vienna, and Doctor of Liberal Arts and Philosophy in the University of Prague. At. 57 (1849). He gave two Friday discourses, one on Plicker’s repulsion of the Optic Axes of Crystals by the Magnetic Poles; and the other on De la Rue’s Envelope Machinery. He reported to the Trinity House on the ventilation of Flambro’ Head, Dungeness, Needles, and Portland Lighthouses. He was made Honorary Member, First Class, Institute Royale des Pays- Bas, and Foreign Correspondent of the Institute, Madrid. Zit. 58 (1850). The twenty-third series of Researches in Electricity appeared, on the Polar or other Condition of Diamagnetic Bodies. The twenty-fourth series was the Bakerian lecture, on the possible relation of Gravity to Electricity. He finishes this paper, saying, ‘‘ Here end my trials for the present. The results are negative; they do not shake my strong feeling of. the exist- ence of a relation between gravity and electricity, though they give no proof that such a relation exists.’ The twenty-fifth series was on the Magnetic and Diamagnetic Condition ef Bodies: —1. Non-expansion of Gaseous Bodies by Magnetic Force. 2. Differential Magnetic Action. 3. Magnetic characters of Oxygen, Nitrogen, and Space. The twenty-sixth series was on Magnetic Conducting-power :—1. Magnetic Conduction. 2. Conduction Polarity. 3. Magnecrystallic Conduction. Atmospheric Mag- netism :—1. General principles. The twenty-seventh series was on Atmo- spheric Magnetism (continued) :—2. Experimental inquiry into the Laws of Atmospheric Magnetic Action, and their application to particular cases. He gave a Friday discourse on the Electricity of the Air, and another on certain conditions uf Freezing Water. He reported on the adulteration of whitelead for the Trinity House. To Prof. Schénbein he writes :—“ By-the-by, I have been working with the oxygen of the air also. You remember that three years ago I dis- hi tinguished it as a magnetic gas in my paper on the diamagnetism of flame and gases, founded on Bancalari’s experiment. Now I find in it the cause of all the annual and diurnal and many of the irregular variations of the terrestrial magnetism. The observations made at Hobarton, Toronto, Greenwich, St. Petersburg, Washington, St. Helena, the Cape of Good Hope, and Singapore, all appear to me to accord with and support my hypothesis. I will not pretend to give you an account of it here, for it would require some detail, and I really am weary of the subject.’’ Later he writes :—‘‘I think I told you in my last how that oxygen in the atmo- sphere, which I pointed out three years ago in my paper on flame and gases aS SO very magnetic compared with other gases, is now to me the source of all the periodical variations of terrestrial magnetism, and so I rejoice to think and talk at the same time of your results, which deal also with that same atmospheric oxygen. What a wonderful body it is!” Miss Martineau had said, on the authority of the Annual Register, that he countenanced the Acarus Crossii. Faraday corrects her :—‘‘I hope you will forgive me for writing to you about this matter. I feel it a great honour to be borne on your remembrance, but I would not willingly be there in an erroneous point of view.” In the summer he was asked by a friend to stay in the country. He writes, August 24, from Upper Norwood :—‘“I have kept your picture to look at for a day or two before I acknowledge your kindness in sending it. It gives the idea of a tempting place; but what can you say to such per- sons as we are who eschew all the ordinary temptations of society? There is one thing, however, society has which we do not eschew; perhaps it is not very ordinary, though I have found a great deal of it, and that is kindness, and we both join most heartily in thanking you for it, even when we do not accept that which it offers. I must tell you how we are situated. We have taken a little house here on the hill-top, where I have a small room to myself, and have, ever since we came here, been deeply immersed in magnetic cogitations. I write and write and write until nearly three papers for the Royal Society are nearly completed, and I hope that two of them will be good if they justify my hopes, for I have to criticize them again and again before I let them loose. You shall hear of them at some of the Friday evenings; at present I must not say more. After writing I walk out in the evening, hand-in-hand, with my dear wife to enjoy the sunset ; for to me, who love scenery, of all that I have seen or can see, there is none surpasses that of Heaven: a glorious sunset brings with it a thousand thoughts that delight me.” Earlier the same friend asked him, for the first time, to dinner. He writes from Brighton :—‘‘ Your note is a very kind one, and very grate- fully received ; I wish on some accounts that nature had given me habits more fitted to thank you properly for it by acceptance than those which really belong to me. In the present case, however, you will perceive that our being here supplies an answer (something like a lawyer’s objection) d 2 li without referring to the greater point of principle. I should have been very sorry in return for your kindness to say zo to you on the other ground, and yet I fear I should have been constrained to do so.” At the end of the year he had another invitation from the Honourable Col. Grey. “If you could make it convenient to come down to Windsor any afternoon in the course of next week, it would give His Royal Highness great satisfaction to have the opportunity of having some conversation with you on this interesting subject (the magnetic properties of oxygen).” He was made Corresponding Associate of the Accademia Pontificia, Rome, and Foreign Associate of the Academy of Sciences, Haarlem. Ait. 59 (1851). The twenty-eighth series of Researches were sent to the Royal Society on Lines of Magnetic Force, their definite character, and their distribution within a Magnet and through Space; also the twenty-ninth series, on the employment of the Induced Magneto-electric Current as a test and measure of Magnetic Forces. He gave three Friday discourses on the Magnetic Characters and Relations of Oxygen and Nitrogen; on Atmospheric Magnetism ; and on Sch6nbein’s Qzone. No work is recorded for the Trinity House. He was made Member of the Royal Academy of Sciences at the Hague, Corresponding Member of the Batavian Society of Experimental Philosophy, Rotterdam ; Fellow of the Royal Society of Sciences, Upsala ; a Juror of the Great Exhibition. This year closed the series of ‘ Experimental Researches in Electricity.’ It began in 1831 with the induction of electric currents, and his greatest dis- covery, the evolution of electricity from magnetism ; then it continued to ter- restrial magneto-electric induction ; then to the identities of electricity from different sources ; then to conducting-power generally. Then came electro- chemical decomposition ; then the electricity of the voltaic pile; then the induction of a current on itself; then statie induction. Then the nature of the electric force or forces, and the character of the electric force in the Gymnotus. Then the source of power in the voltaic pile; then the electricity evolved by friction of steam; then the magnetization of light and the illumination of magnetic lines of force ; then new magnetic actions, and the magnetic condition of all matter; then the crystalline polarity of bismuth, and its relation to the magnetic form of force; then the possible relation of gravity to electricity ; then the magnetic and diamagnetic con- dition of bodies, including oxygen and nitrogen; then atmospheric mag- netism; then the lines of magnetic force, and the employment of induced magneto-electric currents as their test and measure. The record of this work, which he has left in his manuscripts and re- published in his three volumes from the papers in the Philosophical Trans- actions, will ever remain Faraday’s noblest monument—full of genius in the lin conception, full of finished and most accurate work in execution; n quan- tity so vast that it seems impossible one man could have done so much; and this will appear still more when it is remembered that Anderson’s help may be summed up in two words, blind obedience. The use of magneto-electricity in induction machines, in electrotyping, and in lighthouses are the most important practical applications of the ‘Experimental Researches in Hlectricity ;? but who can attempt to measure or imagine the stimulus and the assistance which these researches have given, and will give, to other investigators ? Lastly, if we look at the circumstances under which this work was done, we shall see that during the greater part of these twenty years the Royal Institution was kept alive by the innumerable Friday lectures which he gave at it. ‘‘ We were living,” as he once said to the managers, “on the parings of our own skin.” He had no grant from the Royal Society, and during the whole of this time the fixed income wuich the Institution could aiord to give him was £100 a year, to which the Fullerian professorship added nearly £100 more. By the ‘ Experimental Researches in Electricity,’ Iaraday’s scientific life may be divided into three parts. The first lasted to 1830, when he was thirty-eight ; the second, or ‘‘ research period,” lasted to 1851; and the third and final period began in 1852, and continued to his last report to the Trinity House (in 1865) on the foci and descent of a beam of light 336 feet at St. Bees Lighthouse. Zt. 60 (1852). The first and last Friday discourses of the season were on Lines of Mag- netic Force. In the Philosophical Magazine there was a long paper on the Physical Character of the Lines of Magnetic Force. He begins with a note: —‘* The following paper contains so much of a speculative and hypothetical nature that I have thought it more fitted for the pages of the Philosophical Magazine than for those of the Philosophical Transactions. . .. . i yee He paper, as is evident, follows series xxvill. and xxix., and depends much for its experimental support on the more strict results and conclusions contained in them.” He made many reports to the Trinity House, among others:—on adul- terated white-lead; on oil in iron tanks; on impure clive-oils; on the Caskets lighthouse. And the question of the use of Watson’s electric light was first moved by a letter of Dr. Watson to the Trinity House. In October he wrote a long letter to M. De la Rive. “. . . Do not for a moment suppose Iam unhappy. I am occasionally dull in spirits, but not unhappy. There is a hope which is an abundantly sufficient re- medy for that; and as that hope does not depend on ourselves, I am bold enough to rejoice in that I may have it. “I do not talk to you about philosophy, for I forget it all too fast to make it easy to talk about. When I have a thought worth sending you, it is in liv the shape of a paper before it is worth speaking of; and after that it is astonishing how fast I forget it again; so that I have to read up again and again my own recent communications, and may well fear that, as regards others, I do not do them justice. However, I try to avoid such subjects as other philosophers are working at, and for that reason have nothing im- portant in hand just now. I have been working hard, but nothing of value has come of it.” Two months later he writes to Professor Schonbein from Brighton :— “Tam here sleeping, eating, and lying fallow, that 1 may have sufficient energy to give half a dozen juvenile Christmas lectures. The fact is, I have been working very hard for a long time to no satisfactory end. All the answers I have obtained from nature have been in the negative; and though they show the truth of nature as much as affirmative answers, yet they are not so encouraging ; and so for the present I am quite worn out. I wish I possessed some of your points of character ; I will not say which, for I do not know where the list might end, and you might think me simply absurd, and, besides that, ungrateful to providence.” 44t. 61 (18538). Early in the year he gave a Friday discourse on observations on the Mag- netic Force, and he gave the last lecture of the season on MM. Boussingault, Fremy, and Becquerel’s experiments on oxygen. He gave five reports to the Trinity House—on a comparison of the French lens and Chance’s lens; on the lightning-rods at Eddystone and Bishop’s Lighthouses; on the ventilation of St. Catherine and the Needles Light- houses, and that at Cromer; and on fog-signals. A Company was formed to carry out Watson’s electric light, but no trial of it took place. In June he sent to the Athenzeum an experimental investigation of table- moving. Atthe end he says, ‘‘I must bring this long description to a close. I ama little ashamed of it, for I think im the present age and in this part of the world it ought not to have been required. Nevertheless I hope it may be useful. There are many whom I do not expect to convince, but I may be allowed to say that I cannot undertake to answer such objec- tions as may be made. I state my own convictions as an experimental philosopher, and find it no more necessary to enter into controversy on this point than on any other in science (as the nature of matter, or imertia, or the magnetization of Jight) on which I may differ from others. The world will decide sooner or later in all such cases, and I have no doubt very soon and correctly in the present instance.” A month later he writes to Professor Schonbein :-— ‘J have not been at work except in turning the tables upon the table- turners. Nor should I have done that, but that so many inguiries poured in upon me that I thought it better to stop the inpouring flood by letting all know at once what my views and thoughts were. What a weak, cre- dulous, incredulous, unbelieving, superstitious, bold, frightened, what a ly ridiculous world ours is as far as concerns the mind of man! How full of inconsistencies, contradictions, and absurdities itis! I declare that, taking the average of many minds that have recently come before me (and apart from that spirit which God has placed in each), and accepting for a moment that average as a standard, I should far prefer the obedience, affections, and instinct of a dog before it. Do not whisper this, however, to others. There is One above who worketh in all things, and who governs even in the midst of that misrule to which the tendencies and powers of men are so easily perverted.” After this year, as Director of the Laboratory and Superintendent of the House, he received £300 from the Royal Institution. He was made Foreign Associate of the Royal Academy of Sciences, Turin, and Honorary Member of the Royal Society of Arts and Sciences, Mauritius. Ait. 62 (1854). At the end of this year he sent a long paper to the Philosophical Ma- gazine on some points of magnetic philosophy. He begins saying :— *“Within the last three years I have been bold enough, though only as an experimentalist, to put forth new views cf magnetic action in papers having for titles, ‘On Lines of Magnetic Force,’ Phil. Trans. 1852; and ‘On Physical Lines of Magnetic Force,’ Phil. Mag. 1862. I propose to call the attention of experimenters in'a somewhat desultory manner to the subject again, both as respects the deficiency of the present physical views and the possible existence of lines of physical force.” A course of lectures on education was given by different eminent men at the Royal Institution. Prince Albert came to Faraday’s ‘“ Observations of Mental Education’’ on the 6th of May. In reprinting them, he said, “They are so immediately connected in their nature and origin with my own experimental life, considered either as cause or consequence, that I have thought the close of this volume (of Researches on Chemistry and Physics) not an unfit place for their reproduction.” He ends his lecture by saying, ** My thoughts would flow back amongst the events and reflections of my past life, until I found nothing present itself but an open declaration— almost a confession—as a meaus of performing the duty due to the subject and to you.” He gave two Friday discourses on Electric Induction, associated cases of Current and Static Effects; and on Magnetic Hypotheses. The Parliamentary Committee of the British Association applied to him through Lord Wrottesley for his opinion whether any and what measures could be adopted by the Government or the Legislature to improve the position of science or of the cultivators of science in this country. He an- swers :—‘‘I feel unfit to give a deliberate opinion. My course of life and the circumstances which make it a happy one for me are not those of per- sons who conform to the usages and habits of-society. Through the kind- ness of all, from my Sovereign downwards, I have that which supplies all lvi my need; and in respect of honours, I have as a scientific man received from foreign countries and sovereigns those which, belonging to very limited and select classes, surpass in = opinion anything that it is in the power of my own to bestow. “7 cannot say that I have not valued such distinctions; on the contrary, I esteem them very highly, but I do not think I have ever worked for or sought them. Even were such to be now created here, the time is passed when these would possess any attraction for me, and you will see therefore how unfit I am, upon the strength of any personal motive or feeling, to judge of what might be influential upon the minds of others. Neverthe- less I will make one or two remarks which have often occurred to my mind. A Government should, for its own sake, honour the men who do honour and service to the country. The aristocracy of the class should have distinctions which should be unattaimable except to that of science. But, besides, the Government should, in the very many cases which come before it having a relation to scientific knowledge, employ men who pursue science, provided they are also men of business. This is per- haps now done to some extent, but to nothing like the degree which is practicable with advantage to all parties. The right means cannot have occurred to a Government which has not yet learned to approach and dis- tinguish the class as a whole.” He sent five reports to the Trinity House, one of which, in two parts, was on Dr. Watson’s electric light (voltaic), and on Prof. Holmes’s electric light (magneto-electric). The conclusion was that he could not recommend the electric light, that it had better be tried for other than lighthouse uses first. To Dr. Watson he wrote that he “could not put up in a lighthouse what has not been perfectly established beforehand, and is only experimental.” He was made Corresponding Associate of the Royal Academy of Sciences, Naples. 4Et. 63 (1855). His first Friday discourse was on some Points of Magnetic Philosophy and on Gravity. Later he gave a discourse on Electric Conduction ; and another on Ruhmkorff’s Induction-apparatus. For the Trinity House he only went to Birmingham to examine some apparatus of Chance’s. This year, on the application of his friend M. Dumas, he was made Com- mander of the Legion of Honour, and received the Grand Medal of Honour of the French Exhibition for his discoveries. He was made Honorary Member of the Imperial Society of Naturalists, Moscow, and Corresponding Associate of the Imperial Institute of Sciences of Lombardy. Et. 64 (1856). This year he sent to the Royal Society his last paper, Experimental Rela- tions of Gold (and other metals) to Light. It was read as the Bakerian lecture early the following year. s lvl ** At one time I had hoped that [I had altered one coloured ray into another by means of gold, which would have been equivalent to a change in the number of undulations ; and though I have not confirmed that result as yet, still those I have obtained seem to me to present a useful experi- mental entrance into certain physical investigations respecting the nature and action of aray of light. I donot pretend that they are of great value in their present state, but they are very suggestive, and they may save much trouble to any experimentalist inclined to pursue and extend this line of investigation.” He gave two Friday discourses, the first on certain magnetic actions and affections; and the second on M. Petitjean’s process for silvering glass, and some observations on divided gold. He gave five reports to the Trinity House, and he entered into an en- gagement regarding the Board of Trade Lighthouses, and made four re- ports, two on Cape Race Lighthouse, and one on Dr. Normandy’s distilled water-apparatus. He was made Corresponding Member of the Netherland Society of Sci- ences, Batavia, and Member of the Imperial Royal Institute of Padua. Aut. 65 (1857). Two Friday discourses were given, the first on the Conservation of Force, and the second on the relations of Gold to Light. “Various circumstances,” he begins, “‘induce me at the present moment to put forth a consideration regarding the conservation of force. There is no question which lies closer to the root of all Bb ycical knowledge than that which inquires whether force can be de- stroyed ornot. . . . . . Agreeing with those who admit the con- servation of force to be a principle in physics as large and sure as that of the indestructibility of matter, or the invariability of gravity, I think that no particular idea of force has a right to unlimited and unqualified accep- tance that does not include assent toit. . . . Supposing the truth of the principle is assented to, I come to its uses. No hypothesis should be admitted nor any assertion of a fact credited that denies the principle. The received idea of gravity appears to me to ignore entirely the principle of the conservation of force, and by the terms of its definition, if taken in an absolute sense, ‘varying inversely as the square of the distance,’ to be in direct opposition to it.’’ To Mr. Barlow he writes :— «T am in town, and at work more or less every day. My memory wearies me greatly in working ; for I cannot remember from day to day the conclusions I come to, and all bas to be thought out many times over. To write it Gown gives no assistance, for what is written down, is itself for- gotten. Itis only by very slow degrees that this state of mental muddi- ness can be wrought either through or under; nevertheless I know that to work somewhat, is far better than to stand still, even if nothing comes of it. lvii It is better for the mind itself—not being quite sure whether I shall ever end the research, and yet being sure that, if in my former state of memory, I could work it out in a week or two to a successful result.”’ He gave six reports to the Trinity House. The most important was on Holmes’s magneto-electric light, which was put up at Blackwall, and ob- served from Woolwich, and compared with a Fresnel lamp in the centre of Bishop’s lens, and also in the focus of a parabolic reflector. He critically examined the cost of the apparatus, the price of the light, the suppositions regarding its intensity and advantages, and the proposition to put one up ina lighthouse. He agreed to its being tried at the South Foreland. He was made Member of the Institute of Breslau, Corresponding As- sociate of Institute of Sciences, Venice, and Member of the imperial Academy, Breslau. ; Zit. 66 (1858). He wrote a short paper on Regelation, which he sent with a letter to Dr. Tyndall on Ice of irregular fusibility. These were printed in Dr. Tyndall’s paper on some Physical Properties of Ice inthe Philosophical Transactions for this year. He gave two Friday discourses. The first was remarks on Static Induc- tion; and the other on Wheatstone’s Electric Telegraph in relation to Sci- ence (being an argument in favour of the full recognition of science as a branch of education). This year Prince Albert offered him a house on Hampton Court Green. it required repair, and he doubted whether he could afford to do it up. He writes to a niece :— “The case is settled. The Queen has desired me to dismiss all thoughts of the repairs, as the house is to be put into thorough repair both inside and out. The letter from Sir C. Phipps is most kind.” To Sir C. Phipps he writes :— ‘1 find it difficult to write my thanks or express my sense of the grati- tude I owe to Her Majesty ; first, for the extreme kindness which is offered to me in the use of the house at Hampton Court, but far more for that condescension and consideration which, in respect of personal rest and health, was the moving cause of the offer. I feared that I might not be able properly to accept Her Majesty’s most gracious favour. I would not bring myself to decline so honourable an offer, and yet I was constrained carefully to consider whether its acceptance was consistent with my own particular and peculiar circumstances. The enlargement of Her Majesty’s favour has removed all difficulty. I accept with deep gratitude, and I hope that you will help me to express fitly to Her Majesty my thanks and feelings on this occasion.” To M. De la Rive he thus writes on the death of Mrs. Marcet :— “Your subject interested me deeply every way, for Mrs. Marcet was a good friend to me, as she must have been to many of the human race. I entered the shop of a bookseller and bookbinder at the age of 13 in the year lix 1804, remained there eight years, and during the chief part of the time bound books. Now it was in those books in the hours after work that I found the beginning of my philosophy. There were two that especially helped me, the ‘Encyclopedia Britannica,’ from which I gained my first notions of electricity, and Mrs. Marcet’s ‘ Conversations on Chemistry,’ which gave me my foundation in that science. “‘ Do not suppose that I was a very deep thinker, or was marked as a precocious person. I was a very lively, imaginative person, and could believe in the Arabian Nights as easily as im the Encyclopedia; but facts were important to me and savedme. I could trust a fact, and always cross-examined anassertion. So when I questioned Mrs. Marcet’s book by such little experiments as I could find means to perform, and found it true to the facts as I could understand them, I felt that I had got hold of an anchor in chemical knowledge, and clung fast to it. Thence my deep veneration for Mrs. Marcet: first, as one who had conferred great per- sonal good and pleasure on me, and then as one able to convey the truth and principle of those boundless fields of knowledge which concern natural things to the young, untaught, and inquiring mind. “You may imagine my delight when I came to know Mrs. Marcet personally ; how often I cast my thoughts backwards, delighting to con- nect the past and the present; how often, when sending a paper to her as a thank-offering, I thought of my first instructress; and such like thoughts will remain with me. “1 have some such thoughts even as regards your own father, who was, I may say, the first who personally, at Geneva, and afterwards by corre- _ spondence, encouraged, and by that sustained me.” He made twelve reports to the Trinity House. The most important was on the electric light at the South Foreland. He went there, with a Com- mittee of the Trinity House, to see it from sea and land. The light was im the centre of the Fresnel apparatus, in the upper light, as a fixed light, and so comparable with the lower fixed light, which consisted of oil- lamps in reflectors. They went to the Varne light-ship. The upper was generally inferior to the lower light. Next morning they went to the light- house, and examined it by day and also at night. He was made Corresponding Member of the Hungarian Academy of Sciences, Pesth. Lt. 67 (1859). He gave two Friday discourses on Schonbein’sOzone and Antozone; and on Phosphorescence, Fluorescence, &c. He sent eleven reports to the Trinity House, and one to the Board of Trade. -On the 28th of March, the mag- neto-electric light was again exhibited at the South Foreland. On the 20th of April he went to sea to examine it. ‘The upper light,” he says, “is far superior to the lower light; the electric light very fine.’ He visited the lighthouse ; he found new lamps by Duboscq, and silvered reflectors be- hind. He writes :—‘“ Asa light unexceptionable ; as electric light won- lx derful.”” He had before drawn up instructions to lighthouse keepers and pilot cutters; and on the 29th of April he reports the sufficiency of the light as established. - He reported this year on Way’s mercurial electric light; the one advan- tage it had was that the place of the light was unchangeable. He was one of a Commission appointed to consider the subject of light- ing public galleries by gas ; and he reported favourably on the experimental attempt at the Sheepshanks Gallery. To Mr. Barlow he writes from Hampton Court :—“As I have been out here with only runs into town, I really know very little of what is going on there, and what I learn I forget. The Senate of the Uni- versity accepted and approved of the report of the Committee for Scien- tific Degrees; so that that will go forward (if the Government ap- prove), and will come into work next year. It seems to give much satis- faction to all who have seen it, though the subject is beset with difficul- ties; for when the depth and breadth of science came to be considered, and an estimate was made of how much a man ought to know to obtain aright to a degree in it, the amount in words seemed to be so enormous as to make me hesitate in demanding it from the student; and though in the D.S. one could divide the matter and claim eminence in one branch of science rather than good general knowledge in all, still m the B.S., which is a progressive degree, a more extended, though a more superficial ac- quaiutance seemed to be required. In fact the matter is so new, and there is so little that can serve as previous experience in the founding and arranging these degrees, that one must leave the whole endeavour to shape itself as the practice and experience accumulates.” Zt. 68 (1860). He gave two Friday discourses on Lighthouse Illumination by the Elec- tric Light; and on the Electric Silk-loom. , He gave eleven reports to the Trinity House, and he examined three Red-Sea lighthouses for the Board of Trade. On the 13th of February he went to Dover, but was prevented by snow from reaching the lighthouse ; on the 17th he tried again, and on the 28th he gave his final report on the practicability and utility of the magneto-electric light. He says, ‘Hope it will be applied.” On the 14th of March the magneto-electric light was proposed for Dungeness. On the 21st he gives his reply, and says there is no difficulty. | He was appointed with Sir Roderick Murchison to report upon the means of preserving the stonework of the new Palace at Westminster. At Christmas he gave his last course of juvenile lectures on the chemical history of a candle. : He was made Foreign Associate of the Academy of Sciences, Pesth, and Honorary Member of the Philosophical Society of Glasgow. xi He resumed the office of Elder in his Church in the autumn, and in little more than three years and a half he finally resigned it. 4Gt. 69 (1861). He gave Friday discourses on Platinum, and on Warren De La Rue’s Photographie Eclipse results. He gave ten reports to the Trinity House. The most important work was a visit on 3lst of October to Dungeness, to see the new magneto-electric lamps, the machines, and the steam-engines. He drew up forms of observa- tions to be made at Dungeness, at other lighthouses, and by the pilot cutters. To Prof. Schonbein he writes :—“ You really startle me with your inde- pendent antozone. . . . Surely you must hold it in your hand like a little strugeler ; for, if I understand you rightly, it must be a far more abundant body than cesium. For the hold you have already obtained over it I con- gratulate you, as I would do if you had obtained a crown, and more than fora new metal. But surely these wonderful conditions of existence cannot be confined to oxygen alone. I am waiting to hear that you have disco- vered like parallel states with iodine, or bromine, or hydrogen, and nitro- gen—what of nitrogen? is not its apparent quiet simplicity of action all asham? not a sham, indeed; but still not the only state in which it can exist. Ifthe compounds which a body can form show something of the state and powers it may have when isolated, then what should nitrogen be in its separate state? You see I do not work; Icannot; but I fancy, and stuff my letters with such fancies (not a fit return) to you.” In another letter he says, ‘“‘ I am still dull, stupefied, and forgetful. I wish a discovery would turn up with me, that I might answer you in a decent, respectable way ; but it will not.” Still later he says :—‘‘I look forward to your new results with great interest ; but I am becoming more and more timid when I strive to collate hypotheses relating to the chemical constitution of matter. I cannot help thinking sometimes whether there is not some state or condition of which our present notions give us very little idea, and which yet would reveal to us a flood, a world of real knowledge,—a world of facts available both by prac- tical application and their illustrations of first principles; and yet I cannot shape the idea into a definite form, or reach it by any triai facts that I can devise; and that being the case, I drop the attempt and imagine that all the preceding thought has just been a dreaminess and no more; and so there is an end of it.” In October he wrote to the Managers of the Institution :—“It is with the deepest feeling that I address you. I entered the Royal Institu- tion in March 1813, nearly forty-nine years ago, and, with exception of a comparatively short period, during which I was abroad on the continent with Sir H. Davy, have been with you ever since. During that time I have been most happy in your kindness, and in the fostering care which xii the Royal Institution has bestowed upon me. Thank God, first, for all his gifts. I have next to thank you and your predecessors for the unswerving encouragement and support which you have given me during that period. My life has been a happy one, and all I desired. During its progress I have tried to make a fitting return for it to the Royal Institution, and through it to science. But the progress of years (now amounting in num- ber to threescore and ten) having brought forth first the period of deve- lopment, and then that of maturity, have ultimately produced for me that of gentle decay. This has taken place in such a manner as to make the evening of life a blessmg; for whilst increasing physical weakness occurs, a full share of health free from pain is granted with it, and whilst me- mory and certain other faculties of the mind diminish, my good spirits and cheerfulness do not diminish with them. ‘Still [ am not able to do as I have done. I am not competent to perform as I wish the delightful duty of teaching in the Theatre of the Royal Institution, and I now ask you (in consideration for me) to accept my resignation of the juvenile lectures. Being unwilling to give up what has always been so kindly received and so pleasant to myself, I have tried the faculties essential for their delivery, and I know that I ought to retreat ; for the attempt to realize (in those trials) the necessary points brings with it weariness, giddiness, fear of failure, and the full conviction that it is time to retire; I desire therefore to lay down this duty. I may truly say that such has been the pleasure of the occupation to me, that my regret must be greater than yours need or can be. . “« And this reminds me that I ought to place in your hands the whole of my occupation. It is no doubt true that the juvenile lectures, not being included in my engagement as professor, were when delivered by me un- dertaken as an extra duty, and remunerated by an extra payment. The duty of research, superintendence of the house, and of other services still remains ; but I may well believe that the natural change which incapaci- tates me from lecturing, may also make me unfit for some of these. In such respects, however, I will leave you to judge, and to say whether it is your wish that I should still remain as part of the Royal Institution. I am, gentlemen, with all my heart, your faithful and devoted servant.” Shortly afterwards he wrote to the Secretary :—“ You know my feelings, in regard to the exceedingly kind manner in which the Board of Managers received my letter, and you therefore can best convey to them my deep thanks on this occasion. Please do this for me. Nothing would make me happier in the things of this life than to make some scientific discovery or development, and by that to justify the Board in their desire to retain me in my position here.” Sir Emerson Tennant wished Mr. Faraday to witness the phenomena produced by Mr. Home. Mr. Faraday says, in his reply, ‘* You will see that I consent to all this with much reserve and only for your sake.’ Three days afterwards Sir E. Tennant says, “ As Mr. Home’s wife is dying, the lx probability is that the meeting, at which I wished you to be present, on the 24th may not take place. From the same cause I am unable to see Mr. Home previously, or to make the inquiries of himself necessary to satisfy the queries in your letter.” He was made Honorary Member of the Medical Society of Edinburgh. Zit. 70 (1862). On the 20th of June he gave his last Friday discourse, on Gas furnaces. He gave seventeen reports to the Trinity House, and two to the Board of Trade. The most important of the Trinity House reports were still on the magneto-electric light. On the 12th of February he went to Dunge- ness, examined the engine-room, the machines, the lanthorn, the lamps, and the photometric effects. The keepers he examined, and found them not intelligent enough. At night he went to sea, testing at five miles off the effects of oil-lamp reflectors and the electric light, Prof. Holmes himself being in charge of the lamps for the trials. Then he went to the Varne floating-light, and compared Dungeness, Grisnez, and the South Foreland lights. Inthe morning he went to Dover to examine the upper South Foreland new hydrostatic lamp ; and, in the course of the year, the dif- ferent observations made at South Foreland, Varne, Dungeness, and the pilot-cutters had to be considered and reported on. The House of Com- mons this year called for copies of his reports on the magneto-electric light to be printed. At the International Exhibition he saw Berlio’s magneto- electric machine and light, and he reported on the construction of it. This year he was examined at great length by the Public School Com- missioners. His most important answers were these :—‘‘ that the natu- ral knowledge which had been given to the world in such abundance during the last fifty years, I may say, should remain untouched, and that no suf- ficient attempt should be made to convey it to the young mind, growing up and obtaining its first views of these things, isto me a matter so strange that I find it difficult to understand ; though I think I see the opposition breaking away, it is yet avery hard one to be overcome. That it ought to be overcome I have not the least doubt inthe world.” In answer to the ques- ‘tion at what age it might be serviceable to introduce the physical sciences, he says, ‘I think one can hardly tell that until after experience for some few years. All I can say is this, that at my Juvenile Lectures, at Christ- mas time, I have never found a child too young to understand intelligently what I told him: they came to me afterwards with questions which proved their capability.” Again he says, “‘I do think that the study of natural science is so glorious a school for the mind, that with the laws impressed on all created things by the Creator, and the wonderful unity and stability of matter and the forces of matter, there cannot be a better school for the education of the mind.”’ In September he wrote his last letter to Prof. Schdnbein; he says, lxiv “ Again and again I tear up my letters, for I write nonsense. I cannot spell or write a line continuously. Whether I shall recover this confu- sion, do not know. I will not write any more. My love to you.” The Duke of Devonshire at his installation would have the University of Cambridge confer the degree of LL.D. on Faraday. He was also made Knight Commander of the Order of St. Maurice and Lazarus, Italy. Git. 71 (1863). He made twelve reports to the Trinity House. In February he was again at Dungeness examining a new optic apparatus, and comparing the reflectors with the electric light, and new and old apparatus. He reported on the ob- servations regarding the magneto-electric light, and ona French applica- tion to. the Board of Trade about the magneto-electric light. To the Registrar of the London University he wrote :—‘ Many of your recent summonses have brought so vividly to my mind the progress of time in taking from me the power of obeying their call, that I have at last re- solved to ask you to lay before the Senate my desire to relinquish my sta- tion and render up that trust of duty which I can no longer perform with satisfaction either to myself or to others. “The position of a Senator is one that should not be held by an inactive man to the exclusion of an active one. It has rejoiced my heart to see the progress of the University and of education under its influence and power ; and that delight I hope to have so long as life shall be spared to me.” He was made Foreign Associate of the Imperial Academy of Medicine, Paris. Ait. 72 (1864). Twelve reports were made between January and October to the Trinity House. One was on a new magneto-electric machine ; another on draw- ings, proposals, and estimates for the magneto-electric light at Portland. He made seven examinations of white and red leads, and two examinations of waters from Orfordness and the Fog-gun station, Lundy Island; and he reported on two 4th-order lights for the River Gambia. He replied to an invitation of the Messrs. Davenport :—‘‘ I am obliged by your courteous invitation ; but really I have been so disappointed by the manifestations to which my notice has at different times been called, that I am not encouraged to give any more attention to them, and therefore I leave these to which you refer in the hands of the Professors of Legerde- main. If spirit communications, not utterly worthless, should happen to start into activity, I will leave the spirits to find out for themselves how they can move my attention. I am tired of them.” A few weeks later he replied to another different invitation :— «Whenever the spirits can counteract gravity or originate motion, or supply an action due to natural physical force, counteract any such action, — whenever they can pinch or prick me, or affect my sense of feeling or any other sense, or in any other way act on me without my waiting on them, or, lxv working in the light, can show me a hand, either writing or not, or in any way make themselves visibly manifest to me—whenever these things are done, or anything which a conjuror cannot do better, or, rising to higher proofs, whenever the spirits describe their own nature, and, like honest spi- rits, say what they can do, or pretending, as their supporters do, that they can act on ordinary matter whenever they initiate action, and so make themselves manifest,—whenever by such-like signs they come to me and ask my attention to them, I will give it. But until some of these things be done, I have no more time to spare for them or their believers, or for correspondence about them.” At the end of the year he was asked by Mr. Cole to be a Vice-President of the Albert Hall. He replied :—<‘‘I have just returned from Brighton, to which place my doctor had sent me under nursing care. Hence the delay In answering your letter, for I was unaware of it until my return. Now, as to my acceptance of the honour you propose tome. With my rapidly failing faculties, ought Ito accept it? You shall decide. Remember that I was obliged to ieaiine lecturing before Her Majesty and the Royal Family at Osborne ; that I have declined and am declining the Presidency of the Royal Society, the Royal Institution, and other bodies ; declaring myself unfit to undertake any reponsibility or duty even in the smallest degree. Would it not therefore be inconsistent to allow my name to appear amongst those of the effectual men who delight, as I should have done under other circumstances, to honour in every way the me- mory of our most gracious and regretted leader? These are my diffi- culties. It is only the name and the remembrance of His Royal High- ness which would have moved me from a long-taken resolution.” Mr. Cole decided, ‘‘ without a moment’s doubt,’ that he was to bea Vice-President. To a friend he writes :—‘‘I find myself less and less fit for communi- cation with society, even in a meeting of family—brothers and sisters. I cannot keep pace in recollection with the conversation, and so have to sit silent and taciturn. Feeling this condition of things, I keep myself out of the way of making an exposure of myself.” He was made Foreign Associate of the Royal Academy of Sciences, Naples. . Ait. 73 (1865). He made his last report for the Trinity House in May this year on St. Bees Light. . He wrote to the Deputy Master :—‘‘I write to put myself plainly be- fore you in respect of the matter about which I called two days ago. At the request of the then Deputy Master i joined the Trimity House in February 1836, now near upon thirty years since. I find that time has had its usual effect upon me, and that I have lost the power of remem- bering and also of other sorts, and I desire te relieve my mind. Can this Wet. XVII. e xvi be done without my retiring altogether, and can you help me in this matter ? ”’ . In looking back to his work for the Trinity House, going down to ana- lyses of cottons, oils, paints, and waters, and recalling his words “ that £200 a year is quite enough in itself, but not if it is to be the indicator of the character of the appointment,” one is rejoiced to find that he received the highest reward which the scientific man can obtain. After himself test- ing the results by the most complete and searching trials, he was able to recommend that his own grandest discovery should be applied to “ the great object of guiding the mariner across the dark and dreary waste of waters.” To the Managers of the Royal Institution he wrote, March 1 :-— “Unless it be that as I get older 1 become more infirm in mind, and consequently more timid and unsteady, and so less confident in your warm expressions, I might, I think, trust more surely in your resolution of the 2nd of December, 1861, and in the reiterated verbal assurances of your kind Secretary than I do ; but I become from year to year more shaken in mind, and feel less able to take any responsibility on me. I wish, there- fore, to retire from the position of Superintendent of the house and labo- ratories. That which has in times past been my chiefest pleasure has now become a very great anxiety ; and I feel a growing iability to advise on the policy of the Institution, or to be the one referred to on questions both great and small as to the management of the house. | “In a former letter, when laying down the juvenile lectures, I mentioned ‘that other duties, such as research, superintendence of the house, and other services still remain ;’ but I then feared that I might be found unfit for them ; I am now persuaded that this is the case. If under these cir- cumstances you may think that with the resignation of the positions I have thus far filled the rooms I occupy should be at liberty, I trust that you wil! feel no difficulty in letting me leave them; for the good of the Institution is my chief desire in the whole of this action. Permit me to sign myself personally, your dear, indebted, and grateful friend.” ** Resolved unanimously— “That the Managers thank Professor Faraday for the scrupulous anxiety which he has now and ever shown to act in every respect for the good of the Royal Institution. They are most unwilling that he should feel that the cares of the laboratories and the house weigh upon him. They beg that he will undertake only so much of the care of the house as may be agreeable to himself, and that whilst reliquishing the duties of ‘Director of the laboratory,’ he will retain his home at the Royal In- stitution.”’ Sir David Brewster sent him a pamphlet on the Invention and Intro- duction of the Dioptric Lights, and asked him to give his opinion on the value and importance of these lights. He replied :—“.... I would rather not enter as an arbitrator or judge into the matter, for I have of late been Ixvii resigning all my functions as one incompetent to take up such matters, and the Royal Institution as well as the Trinity House have so far accepted them as to set me free from all anxiety of thought in respect tothem. In fact my memory is gone, and I am obliged to refrain from reading argu- mentative matter or from judging of it. * I am very thankful for their ten- derness in the matter; and if it please Providence to continue me a year or two in this life, I hope to bear the decree patiently. My time for contend- ing for temporal honours is at an end, whether it be for myself or others.”’ In the fine summer at Hampton Court he sat in his window delighting in the clouds and the holiday-people on the green. A friend from London asked how he was. “Just waiting,’ he replied. This he more fully said in a note. “I bow before him who is Lord of all, and hope to keep waiting patiently for His time and mode of releasing me ac- cording to His divine word, and the great and precious promises whereby His people are made partakers of the divine nature.” To Sir James South, who wished to have some account of Anderson’s services, Faraday wrote :—‘‘ Whilst endeavouring to fulfil your wishes in re- lation to my old companion, Mr. Anderson, I think I cannot do better than accompany some notes which he has himself drawn up and had printed, by some remarks of mine, which will show how and how long he has been engaged here. *« He came to assist in the glass house for the service of science in Septem- ber 1827, where he remained working until about 1830. Then fora while he was ‘retained by myself. In 1832 he was in the service of the Royal Institution, and paid by it. From that time to the present he has remained with that body, and has obtained their constant approbation. In January 1842 they raised his pay to £100 per annum with praise. In 1847 they raised it in like manner to £110. For the same reason in 1853 they raised it to £120; and in 1860, in a minute, of which I think Mr. Anderson has no copy, they say that, in consideration of his now lengthened services and the diligence exhibited by him, they are of opinion that his salary should be raised to £130. «© Mr. Anderson still remains with us, and is in character what he has ever been. He and I are companions in years and in work and in the Royal Institution. Mr. Brande’s testimony when he left the Institution is to the same purport as the others. Mr. Anderson was 75 years of age on the 12th of last month (January). Heis a widower, but has a daughter keeping his house for him. We wish him not to come to the Royal Insti- tution, save when he is well enough to make it a pleasure; but he seems to be happy being so employed.” Ait. 74 (1866). Early in January Anderson died. Sir James South wished some monu- ment to be put up to him, and wrote to Faraday. He replied :— e2 = Ixvilt “‘My dear old friend, I would fain write to you, but, indeed, write to no one, and have now a burn on the fingers of my right hand which adds to my trouble; so that I still use my dear J.’s hand as one better than my own, and fear I give her great work by so doing. She has, I understand, written to you this morning, and told you how averse I am to meddling with sepulchral honours in any case. I shall mention your good will to Anderson” [here Faraday took the pen, because his niece made some objection to the words “ mention the good will to Anderson,” who was dead]; “but I tell them what are my feelings. I have told seve- ral what may be my own desire; to have a plain simple funeral, attended by none but my own relatives, followed by a gravestone of the most ordi- nary kind, in the simplest earthly plaee. ‘As death draws nigh to old men or people, this world disappears, or should become of little importance. It is so with me; but I cannot say it simply to others [here he stopped his writing, and his niece finished the note], for J cannot write it as I would. Yours, dear old friend, whilst permitted.” The Society of Arts this summer gave him a medal for his scientific dis- coveries. . During the winter he became very feeble in all muscular power. Almost the last interest he showed in scientific things was in a Holtz electric machine. In the spring, for a short time, with decreasing power, there was at times wandering of mind. One day he fancied he had made some disco- very somehow related to Pasteur’s dextro- and leevo-racemic acid. He de- sired the traces of it to be carefully preserved, for “it might be a glorious discovery.” His loss of power became more and more plain during the summer and autumn and winter: all the actions of the body were carried on with diffi- culty ; he was scarcely able to move; but his mind continually overflowed with the consciousness of the affectionate care of those dearest to him. Ait. 75 (1867). At times he could hardly speak a word, and with difficulty swallow a mouthful. Tn the spring he went to Hampton Court. Gradually he became more © and more torpid, and on the 25th of August he died there. He said of himself, ‘‘ In early life I was a very lively imaginative person, who could believe in the Arabian Nights as easily as in the Encyclopeedia. But facts were important to me and saved me. I could trust a fact.” And so afterwards this blacksmith’s son from Jacob’s Well Mews, full of inborn religion, and gentleness, genius, and energy, searched for and trusted to facts in his experimental researches, and thus left to science a monu- ment of himself that may be compared even to that of Newton. H. B. J. lxix On the lith of December, 1781, at Jedburgh, was born Davip BrewsTErR, who, having made a telescope when only 10 years of age, and having entered on his university course at 12, devoted one of the longest of lives to discoveries in optics, and at last, laden with academic and scientific honours, sank peacefully to rest on the 10th of February, 1868. . He was one of four brothers, all educated for the Church of Scotland, and he advanced to the position of a licentiate ; but a certain nervousness in speaking and delicacy of health, combined with an overpowering love for scientific pursuits, led him to decline a good presentation, and to aban- don the clerical profession for that of an expounder of natural philosophy. Thus he entered on a career of investigation and literary work which for magnitude, as well as importance, has rarely been rivalled. As an editor, he commenced in 1808 a work so large that it occupied him for twenty-two years—the Edinburgh Encyclopedia; and in the mean time he began with Professor Jameson the Edinburgh Philosophical Journal, and subsequently the Edinburgh Journal of Science; and from 1832 he was one of the editors of the Philosophical Magazine. Through- out his connexion with these periodicals he was a frequent contributor of original articles to their pages, and he continued to the last to write for the North British and other Reviews in a style so polished and so vigorous, that multitudes learnt from him the actual state of scientific questions who would never have read a-merely learned dissertation. But his fame rests not so much on this literary work as on his original researches, which were so numerous that the ‘ Catalogue of Scientific Papers’ now being published by the Royal Society contains the titles of 29 papers by him, besides five in which his name is conjoined with those of other investigators. And these researches, though principally connected with the phenomena of light, spread over many other departments of human knowledge. | Ner were Brewster’s labours for the advancement of science confined to the laboratory and the desk. In 1821 he founded the Scottish Society of Arts, and in 1831 he was one of the small party of friends who instituted the British Association, in the meetings of which he usually took a promi- nent part. During this time honours steadily flowed in upon him. He was made an honorary M.A. of Edinburgh in 1800, and seven years afterwards an honorary LL.D. of Aberdeen. From 1838 to 1859 he was Principal of the United Colleges of St. Salvador and St. Leonard’s at the University of St. Andrews ; and for the last eight years of his life he held the same im- portant office in the leading University of Scotland. | Having been chosen a Fellow of the Royal Society of Edinburgh in 1808, Sir David acted for a long time as its Secretary, and he was President at the time of his death. In 1815 he obtained both the Copley Medal and Ixx the Fellowship of our Society ; and this was followed three years after- wards by the Rumford Medal, and subsequently by one of the Royal Medals ; and, singularly enough, in each case for discoveries concerning the Polarization of Light. In 1816 the French Institute awarded him a pecuniary prize, and nine years afterwards he became a Corresponding Member of that body; while in 1849 there was conferred upon him the distinguished honour of being chosen one of the eight Foreign Associates of the Academy of Sciences. It would be tedious to enumerate his other honours from learned bodies at homeand abroad ; suffice it to add that he was made a Cheyalier of the Prussian Order of Merit, and was knighted by his sovereign in 1832. Sir David was twice married: first to the daughter of Jamgs Macpher- son, M.P., of Belleville, the translator of Ossian, and afterwards to Jane Kirk, second daughter of the late Thomas Purnell, Esq., of Scarborough. To give any adequate idea of the discoveries made known in those scien- tific papers which Sir David Brewster published every two or three months for sixty years, would be a task of gigantic magnitude. There seem to be thirty papers by him in our Transactions, principally in the earlier part of his career, and, with two exceptions, they are all on optical subjects. In 1813 he commenced with a communication “‘ On some Properties of Light,” and in the two succeeding years our Society published for him no less than nine papers—on the polarization of light by oblique transmission, by its passage through unannealed glass, by simple pressure, or by reflection, and on the optical properties of mother-o’-pearl, on calcareous spar. The phe- nomena of double refraction were indeed treated of in several subsequent papers ; but there is a gap between 1819 and 1829, when he wrote on the periodical colours produced by grooved surfaces, investigated elliptic polari- zation by metals, and reverted to the optical nature of the crystalline lens. Two papers, one on the Diamond and the other on the Colours of Thin Plates, terminate this series in 1841; and the only paper he afterwards sent to our Transactions was one in conjunction with Dr. Gladstone on the Lines of the Solar Spectrum. But there seems never to have been any long intermission in his researches on light; for he was constantly sending com- munications on this subject to the Royal Society of Edinburgh or some other learned body, or to the various scientific serials with which he was connected. Thus in the first Number of the Edinburgh Philosophical Journal we find two papers from his pen, the first on new optical and mineralogical structure exhibited in certain specimens of Apophyllite and other minerals, the second on the Phosphorescence of Minerals. It was as a laborious observer and ingenious experimenter that he ex- celled ; he cared rather to collect a multitude of facts than to deduce from them general laws. Wonderful proofs of perseverance are his Tables of refractive indices, of dispersive powers, and of the polarizing angles of va- rious reflecting bodies ; and he seems to have submitted to optical exami- lxxi nation every mineral that came in his way. Frequently one of these sub- stances would form the subject of a monograph, as diamond, or amber, the double cyanide of platinum and magnesium, the felspar of Labrador with its changeable tints, or Glauberite with its one axis of double refraction for - the violet, and two axes for the red ray. The prismatic spectrum arrested his attention, and in 1834 he announced the absorption of certain rays by the earth’s atmosphere, and by nitrous gas; while eight years afterwards he pointed out the existence of luminous lines in certain flames correspond- ing to those defective in the light of the sun; but he missed the beautiful explanation of Kirchhoff. He also investigated the phenomena of diffrac- tion and dichroism, and of late years exhibited to the British Association the tints of a soap-bubble, or of decomposing glass rendered still more lively by being viewed through a microscope. Indeed his last legacy to science was a paper on Film forms. The best monument to his fame is perhaps his investigation of polarized light. Malus had first set foot on this domain, but his premature death left it open to the entrance of Brewster, and what wonderful regions did he explore! It not unfrequently happened that some other philosopber, with perhaps a profounder knowledge of mathematics, stepped in and deduced important laws; but sometimes he himself arrived at the higher generali- zations ; as, for instance, may be cited that of the refractive index of a sub- stance being the tangent of its polarizing angle. But he was not always fortunate in his theories ; thus his ingenious view of solar light, as composed of three primary colours (red, yellow, and blue) forming coincident spectra of equal length, has been shown to be completely fallacious. Yet he never abandoned his theory ; a fact which we are disposed to attribute, not to a want of conscientious truthfulness, but rather to an inability to appreciate the real bearing of an argument, and to an over confidence in his own memory and the testimony of his senses. During his optical investigations Sir David often turned from the phe- nomena seen to the organ of sight, and experimented on that wonderful eye which saw bands in the red rays less refrangible than Fraunhofer’s A. Of late years especially he examined the functions of the retina, the foramen centrale, and the choroid coat of the eye of animals; he wrote several papers on the musce volitantes, and explained many peculiarities of single and binocular vision, and not a few optical illusions. While pursuing these researches on light, he made frequent excursions into other regions of science ; he discovered fluids in the cavities of some of the minerals he was examining, and these must be investigated; he rote much on the mean temperature of the globe; his attention was attracted at one time to fossil bones from Ava, at another to the varnish- trees of India; while systems of double stars, and the pyro-electricity of minerals shared the notice of his comprehensive mind. As an inventor of new apparatus Brewster also acquired no little renown. His first paper on this subject appears to have been ‘‘Some remarks on Ixxil Achromatic Eyepieces”’ in Nicholson’s Journal for 1806; and seven years afterwards he published a separate ‘‘ Treatise on new Philosophical Instru- ments for various purposes in the Arts and Sciences.” In 1816, while repeating some experiments of Biot with a glass trough, he noticed that peculiar method of reflection which is the principle of the Kaleidoscope; and no sooner was this pretty instrument before the public than it became marvellously popular, and that not only as a toy for old and young, but large expectations were raised of its usefulness to the artist and designer of patterns. We are also indebted to him for many other ingenious contri- vances for micrometers, burning-glasses, &c., and his writings frequently contained the germs of future inventions. Hence it is not easy to deter- mine his precise share of merit in such appliances as the lenticular stereo- scope, or the polyzonal lenses used in lighthouses. In regard to the latter, however, it may be safely maintained that while the chief credit of elaborating the dioptric system of illumination must be given to Fresnel, the persistent advocacy of Brewster materially contributed to its adoption on the shores of our own island. In addition to the treatises already mentioned he wrote several distinct works of a biographical character :—the Memoirs of Sir Isaac Newton, Euler’s Letters and Life, and the Martyrs of Science, viz. Galileo, Tycho Brahe, and Kepler. Nor must be omitted his letters on Natural Magic, and his ‘More Worlds than One, the Creed of the Philosopher, and the Hope of the Christian.’ Sir David’s anonymous writings were nearly as numerous as those to which his name was attached, and they spread over a wider range of sub- jects. The elaborate treatises on Optics in the Edinburgh Encyclopeedia and in the recent editions of the Encyclopzedia Britannica are both from his pen, and to each he contributed the articles on Hydrodynamics and Elec- tricity. In the older work he also wrote on Astronomy, Mechanics, Mi- croscopy, and Burning instruments, while in the later work he turned his attention among other subjects to that of photography. To the Edinburgh Review he contributed twenty-eight articles, which are comprised between the Nos. LVII. and LXXXI. They include bio- graphical notices of such men as Davy and Watt; reviews of such philoso- phical works as Whewell’s ‘ History and Philosophy of the Inductive Sciences,’ Mrs. Somerville’s ‘Connexion of the Physical Sciences,’ Lord Brougham’s ‘ Discourse on the Study of Natural Philosophy,’ and even Compte’s ‘ Philosophie Positive: ’ they pass from Buckland’s Geology or Daguerre’s photogenic drawings to the lighter subjects of deer-stalking or salmon-fishing ; they follow Sir James Ross or Sir George Back in their arctic researches, and describe the British lighthouse system or the phe- uiomena of thunder-storms. To the Quarterly Review he seems to have contributed five articles, and in them he gives his estimate of works by Babbage, Herschel, and Aber- crombie ; while the subjects he treats are as wide apart as the production ixxiil of sound, and the analysis of the intellectual powers, the supposed decline of science in England, and the philosophy of apparitions. ‘ Meliora’ and the Foreign Review each contain two articles from his pen, one in the latter being a notice of Dutrochet’s ‘Observations sur Endos- mose et Exosmose.’ But it was in the North British Review that the longest series of articles appeared. We have a list before us of seventy-six in the first thirty-nine parts of that quarterly serial, and we doubt whether the enumeration is complete. This shows that, on an average, Sir David wrote two of these literary productions for each part, and suggests the idea that he must have reviewed every book of note that he read. The first Number of the North British commences with an article by him on Flourens’s ‘ Eloge Historique de Cuvier ;’ and further on in the same part he discusses the ‘ Lettres Pro- vinciales” and other writings of Blaise Pascal. In the second Number he describes the Earl of Rosse’s great reflecting telescope; and shortly we find him engaged with such serious works as Humboldt’s ‘Cosmos’ or Mur- chison’s ‘Siluria.’. The rival claimants for the honour of having discovered. Neptune divide his attention with Macaulay’s ‘History of England,’ or the ‘ Vestiges of the Natural History of Creation.’ With Layard he takes his readers to Nineveh, with Lyell he visits North America, and with Ri- chardson he searches the Polar seas. The Exhibition of 1851, the Peace Congress, and the British Association come in turn under his descriptive notice; or, turning from large assemblies to individual philosophers, he sketches Arago, Young, or Dalton. In one Number we have ‘The Weather and its Prognostics,” and “ The Microscope and its Revelations ;” elsewhere he describes the Atlantic telegraph, whilst in a single article he groups together “the life-boat, the lightning-conductor, and the light- house.” He reviews in turn Mary Somerville’s ‘ Physical Geography,’ and Keith Johnston’s ‘ Physical Atlas ;) the History of Photography engages him at one time, and at another Weld’s History of our Society. Under the guidance of Sir Henry Holland he investigates the curious mental phenomena of mesmerism and electro-biology, and under that of George Wilson he inquires into colour-blindness. He criticises Goethe’s scientific works, expounds De la Rive’s ‘Treatise on Electricity,’ and Arago’s on Comets ; or, turning from these severer studies, he allows Hum- boldt to exhibit the ‘Aspects of Nature’ in different lands to the multi- farious readers of the Review. In addition to all this Sir David issued some pamphlets of a personal nature—controversial writings which some objected to as unnecessarily per- sistent, though it should be recorded to his honour that he was ready to profit by friendly remonstrance. : Few of his living companions will remember this Nestor in science otherwise than as a venerable form full of vivacity and intelligence, keenly alive not to physical questions alone, but to the various social, politi- VOL, XVII, g y lxxiv cal, and ecclesiastical interests of his time, and giving frequent indications of that humble faith in God which was the foundation of his character, and which brightened his declining years and the closing scenes of his earthly life. His many personal friends will retain his memory in their warm affection. Posterity will know him mainly for having opened up new regions in our knowledge of optical phenomena, and for having given a mighty impulse to science during two-thirds of the nineteenth cen- tury.—J. H. G. Cuarues Gites Bripte DAuBeNy* was born February 11, 1795, at Stratton in Gloucestershire, third son of the Rev. James Daubeny, entered Winchester School in 1808, and was elected to a demyship in Magdalen College, Oxford, in 1810. In 1814, at the age of 19, he took the degree of B.A. m the second class, according to the old style of the Oxford Examinations. In 1815 he won the Chanecellor’s Prize for the Latin Essay, the prize for the English Essay in the same year being gained by Arnold. Destined for the profession of medicine, he proceeded to London and Edinburgh as a medical student (1815-18). The lectures of Professor Jameson in Edinburgh on Geology and Mineralogy attracted his earnest attention, and strengthened the desire to cultivate natural science which had been awakened by the teaching of Dr. Kidd at Oxford. In Dr. Kidd’s class-room the future historian of volcanoes had frequently met Buckland and the Conybeares, Whateley and the Duncans—men of vigorous minds and various knowledge. The change from thoughtful Oxford to active Edinburgh was the crisis in Daubeny’s career. The fight was then raging in the modern Athens between Plutonists and Neptunists, Huttonians and Wernerians, and the possession of Arthur’s Seat and Salisbury Craig was sternly debated by the rival worshippers of fire and water.. Daubeny entered keenly into this discussion, and, after quittmg the University of Edinburgh, proceeded, in 1819, on a leisurely tour through France, every- where collecting evidence on the geological and chemical history of the globe, and sent to Professor Jameson from Auvergne the earliest notices which had appeared in England of that remarkable volcanic region7. Some of the views afterwards advanced by the young physicist touching the elevation of the hills and the geological age of the valleys of Auvergne t have been reexamined and discussed by later eminent writers, such as Scrope, Murchison, Lyell—not always in agreement with him, or, deed, with one another; while the prehistoric antiquity of the voleanoes them- * Extracted from a more extended Obituary Notice of Dr. Daubeny, read to the Ash- molean Society of Oxford, by Professor John Phillips, F.R.S., February 17, 1868. + Letters on the Volcanoes of Auvergne, in Jameson’s Edinburgh Journal, 1820-21. ~ Transactions of the Royal Society of Edinburgh, 1831. Ixxv selves has been questioned even within a few years, and defended by none more effectually than by Dr. Daubeny*. From the beginning to the end of his scientific career, volcanic pheno- mena occupied the attention of Dr. Daubeny; and he strove by frequent journeys through Italy, Sicily, France and Germany, Hungary and Tran- sylvania, to extend his knowledge of that interesting subject. In 1823-25, he had by this means prepared the basis of his great work on volcanoes, which appeared in 1826, and contained careful descriptions of all the re- gions known to be visited by igneous eruptions, and a consistent hypothesis of the cause of the thermic disturbance, in accordance with the view first proposed by Gay-Lussac and Davy. Water admitted to the uncombined bases of the earths and alkalies existing below the oxidized crust of the globe, was shown to be an efficient cause of local high temperature, and a real antecedent to the earthquake movements, the flowing lava, and the expelled gas and steam. In later years+ Dr. Daubeny freely accepted, as at least very probable, a high interior temperature of the earth; but he did not allow that the admission of water to a heated interior oxidized mass would account for the chemical effects which accompany and follow an eruption. On this point there are still data to be gathered and inferences to be examined. Four years previously to the publication of the ‘ Description of Volcanoes,’ Dr. Daubeny was appointed to succeed Dr. Kidd as Aldrichian Professor of Chemistry, and took up his abode in, or rather below, the time-honoured Museum founded by Ashmole. In these rather gloomy apartments nearly all the scientific teaching of Oxford had been accomplished since the days of Robert Plot; in them were still collected, as late as 1855, by gas-light and furnace-fires, the most zealous students of Practical Chemistry ; but now they are filled with Greek sculpture, and Chemistry has flitted to the magnificent laboratories of the University Museum, directed by Sir Benja- min Brodie. In 1834 he was appointed Professor of Botany, and migrated to the ‘Physic Garden,” as it was called, which had been founded in the early part of the reign of Charles I. Under his diligent and generous management, with liberal aid from the University, Dr. Daubeny lived to see the old Garden entirely arranged, enriched with extensive houses, extended in area, and made both attractive and beautiful. In the pleasant residence at the Botanic Garden, Dr. Daubeny passed the remainder of his life—the third of a century. Here, incessantly active, he instituted many experiments on vegetation under different con- ditions of soil, on the effects of light on plants, and of plants on light, on the distribution of potash and phosphates in leaves and fruits, on * Quarterly Journal of Science, 1866. t+ “Memoir on the Thermal Waters of Bath,” British Association Reports for 1864. f2 Ixxvi the conservability of seeds, on the ozonic element of the atmosphere, and on the effect of varied proportions of carbonic acid on plants analogous to those of the coal-measures*. These last-mentioned experiments are among the very few which can be referred to as throwing light on the curious question whether the amazing abundance of vegetable life in the earboni- ferous ages of the world may not have been specially favoured by the pre- sence, in the paleeozoic atmosphere, of a larger proportion of carbonic acid gas than is found at present. A favourite subject of research with Dr. Daubeny, naturally springing from his volcanic explorations, was the chemical history of mineral waters. The presence of iodine and bromine in some of these formed the subject of a paper in the Philosophical Transactions for 1830; and a Report to the British Association in 1836 included a general survey of mineral and thermal waters. This subject was not neglected in his ‘ North-American Tour’ (1837-38), which contains a great number of interesting observations on the character of the country which he traversed, as well as the educa- tional institutions, where he was heartily welcomed. Dr. Daubeny was a great traveller, almost an annual visitor to the con- tinent, usually, at least in his later years, accompanied by some scientific or literary friend, some member of his family, or some young Oxonian of cultivated taste, to whom the sight of Auvergne and the Tyrol in the com- pany of such a guide was a gift of priceless value. In one of his journeys to Spain in 1843, for the purpose of studying the geological relations and agricultural value of the great phosphatic de- posit of Estremadura, he was accompanied by Captain Widdringtoa, R.N. It was a journey prompted by benevolence and attended by hardship. No doubt, in some future day, railways will carry heavy loads of this valuable substance to enrich the agriculture of Spainf. In another year he might be found in Norway, or musing in the Garden at Geneva, where he was always welcomed by the great botanist whose friendship he gained in early life, and to whose memory he has devoted a careful critical essay, which was read to the Ashmolean Society in 1842f. It was at Geneva that he “began to estimate at their true weight the pretensions of Botany to be regarded as a science, and to comprehend the principle on which it might be inculcated as constituting an essential part of a liberal education.” Here he first pursued his botanical studies under the guidance of Decandolle in 1830, and thus qualified himself for the Professorship to which, as already observed, he was appointed in 1834. | Chemistry, however, was the thread which bound together all the researches of Dr. Daubeny; not that he was personally a dexterous * Miscellaneous Memoirs and Essays, 1867. British Association Reports, 1837-57. + Memoir read to the Geological Society in 1844. { Daubeny’s Miscellanies, vol. ii. ‘On the Life and Writings of A. P. Decandolle.” Ixxvii manipulator of chemical instruments, though a diligent practical ana- lyst. He was rich in chemical knowledge, profound and varied in his acquired views of chemical relations, always prompt and sagacious in fix- ing upon the main argument and the right plan for following up success- - ful experiment or retrieving occasional failure. In 1831 appeared his ‘Sketch of the Atomic Theory,’ a work which well sustained the repu- tation of the author as a master of language and a conscientious teacher of science. So soon as the arrangements were made for the location of Chemistry in its new abode Dr. Daubeny took the occasion of resigning the Chair of Chemistry, and used all his influence to increase the efficieney of the office and secure the services of the present eminent Professor. In his position as a teacher of Botany, he took pleasure in drawing at- tention to the historical aspects of his subject, and specially, as a part of his duty, treated of Rural Economy both in its literary and its practical bearings. Hence arose the ‘‘ Lectures on Roman Husbandry” (1857), written in a style very creditable to the classical training of his early years, and containing a full account of the most important passages of Latin authors bearing on crops and culture, the treatment of domestic animals, and horticulture. To this is added an interesting Catalogue of the Plants noticed by Dioscorides, arranged in the modern natural orders. This was followed, after a few years, by a valuable Essay on the Trees and Shrubs of the Ancients, and a Catalogue of Trees and Shrubs indigenous in Greece and Italy (1865). To facilitate his researches in Experimental Botany, Dr. Daubeny had obtained possession of a piece of land lying some half a mile or so from Oxford ; but of late years symptoms of ill-health interfered both with his enjoyment of the recreation of his little farm, and the experiments for which it was destined. During a few late winters Dr. Daubeny found it desirable to exchange his residence in Oxford for the milder climate of Torquay. Here his activity of mind was equally manifested by public lectures on the tempera- ture and other atmospheric conditions of that salubrious resort, and by ex- periments on ozone and the usual meteorological elements, in comparison with another series in Oxford. By this connexion with Devonshire he was induced to join the Association in that county for the Advancement of Science, Literature, and Art; and one of his latest public addresses was delivered to that body, as President, in 1865. In his whole career Dr. Daubeny was full of that practical public spirit which delights in cooperation, and feeds upon the hope of benefiting humanity by associations of men. When the British Association came into being at York, in 1831, Daubeny alone stood for the Universities of England. In 1856 he was its President, at Cheltenham, in his native county, ixxvili amidst numerous friends, who caused a medal to be struck in his honour— the only occurrence of this kind in the annals of the Association. The same earnest spirit was manifested in all his academic life. No pro- ject of change, no scheme of improvement in University Examinations, no modification in the system of his own college, ever found him indifferent, prejudiced, or unprepared. On almost every such question his opinion was formed with rare impartiality, and expressed with as rare intrepidity. Firm and gentle, prudent and generous, cheerful and sympathetic, pursuing no private ends, calm amid jarring creeds and contending parties—the personal influence of such a man on his contemporaries for half a century of active and thoughtful life fully matched the effect of his published works. His latest labour was to gather his ‘ Miscellaneous Essays’ into two very inter- esting volumes, and then, after patiently enduring severe illness for a few weeks, he sank. to that rest which, often in his thoughts, had ever been expected, with the calmness of the philosopher and the hopefulness of the Christian. He died at five minutes past twelve a.m., December 13, 1867, in his 73rd year. His remains were laid in a vault adjoining the walls of Magdalen Col- lege Chapel, in accordance with his own expressed wish ‘‘ that he might not be separated in death from a society with which he had been connected for the greater part of his life, and to which he was so deeply indebted, not only for the kind countenance and support ever afforded him, but also for supplying him with the means of indulging in a career of life at once so congenial to his taste and the best calculated to render him a useful member of the community.” In the preceding brief notices no mention has been made of Dr. Dau- beny’s short career as a medical man, for which he had prepared himself by professional study in Edinburgh and London. In Oxford he justified his title of M.D. and his Fellowship with the College of Physicians by attaching himself to the Radcliffe Infirmary. In this capacity, how- ever, he did not long remain; nor did he continue his medical practice, though during all his life the progress of medical science was much at his heart, as may be seen in the Harveian Oration which he delivered before the College of Physicians in 1845. In that elegant address he speaks of himself as “... quem, a medicine castris tanquam profugum, Physicarum Scientiarum amor, aut Otii Literati dulcedo, ad aliam vite normam jam tot per annos traustulit, ut ne inter commilitones vestros recenseri merear.”’ In these words we have the key to the valuable life which was passed so busily and so gracefully among his academic brethren, and to the works of scientific and literary interest which are all that now remain to us of Charles Daubeny. What he has said of these works is perhaps the truest and most modest comment that will ever be made on them and on the circumstances under which they were produced. For they are “some of the fruits of a Ixxix life chiefly spent in tranquil intellectual occupation, under the fostering wing of one of those great semimonastic establishments which are peculiar to this country; and however slight their intrinsic value, considered as contributions to the stock of human knowledge, may be, they will serve at © least to show, by their number and variety, what might be accomplished by persons gifted with greater energy and more profound attainments, through the aid cf foundations in which an exemption from domestic cares, and a liberal provision for all the reasonable wants of a celibate life, afford such facilities for the indulgence of either literary or scientific tastes.” Under the influence of the traditions of former scientific culture in Ox ford, and “‘ Not mindless of those mighty times ” when the leading spirits of remote antiquity committed to posterity the pticeless records of early philosophy, was Charles Daubeny conducted to the School of Chemistry, and the School of Geology. In them, but espe- cially in the former, he imbibed sound and various knowledge. From them he passed at once to researches and publications which have contributed as much as those of any physicist of this century to sustain the credit of the University and guide the progress of useful knowledge. And the in- fluence of these publications was in no slight measure due to the pure classical taste, and the sure employment of appropriate language, which were the gift of the foundations of William of Wykeham and William of Waynilete. The same accuracy appeared in the frequent addresses which he was called on to make on social or public occasions. He affected no grace ot oratory ; ‘“‘ Fis words succinct, yet full, without a fault, He said no more than just the thing he ought ;” but the calm and reasonable views which he might be trusted to present on all subjects of scientific interest or administrative reform, never failed to have their due influence even over the agitations of controversy—from which he never shrank if his sense of justice and love of truth called for vindication. Any one accustomed to a considerable degree of inti- macy with Dr. Daubeny would be able to declare that he never met with any man more entirely truthful and just-minded. You might absolutely rely upon him, in regard of deeds, thoughts, and motives. To con- vince his judgment was to enlist his sympathy and secure his active help ; to be censured with overmuch strictness was a passport to such pro- tection as he could honestly give. In defence of a friend whose Essay was unpopular, in opposition to a course of University mutation which he did not think was reform, in advocating what he believed to be de- sirable changes, his arms were ever ready; nor did he throw a pointless dart. With reference to the influence of Dr. Daubeny in scientific discussions, lxxx one may venture to say that it would have been greater had his early studies been more turned in the direction of mathematics, especially as ap- plied to physical research. In the beginning of his career, indeed, Che- mistry was only acquiring numerical exactness, and Geology was quite un- provided with mechanical laws of earth-movement. But no one knew better than Dr. Daubeny that right geometrical conceptions are always necessary to a student of science, and laws of proportion indispensable elements of sound philosophy. The published writings of Dr. Daubeny are very numerous. Besides what have appeared as independent works, the list of his Memoirs in Transactions and Journals up to 1863, as given in the Royal Society’s “Catalogue of Scientific Papers,’ amounts to seventy-too. Many of these, scattered through various periodicals and not conveniently accessible, were collected and arranged by their author in two volumes of Miscellanies. In this collection appeared twelve Experimental Essays, ten Geological Memoirs, eight Essays on Scientific Subjects, and twelve on Literary Subjects. Besides these were several papers of interest, some published separately, which, having been composed after the first edition of the ‘ De- scription of Volcanoes,’ were employed in the preparation of the second edition, or noticed in supplements to that work. By these arrangements Dr. Daubeny has rendered it unnecessary, for those who desire to know his views on the various subjects which occupied his mind, to refer to such publications as the Edinburgh Philosophical Journal, Edinburgh New Philosophical Journal, or Journal of the Geolo- gical Society, or evento the Linnean Transactions, Royal Society’s Trans- actions, or Reports of the British Association, except from a desire to learn his first thoughts from his first words. The following is a list of the works which contain the principal results of Dr. Daubeny’s scientific and literary labours :— 1. Description of Active and Extinct Voleanoes. 8vo, London, 1826. Second Edition, 1848. Several Supplements. 2. Tabular View of Volcanic Phenomena. Folio, thick, 1828. . Notes of a Tour in North America (privately printed). 8vo, 1838. . Introduction to the Atomic Theory. 8vo, 1852. . Lectures on Roman Husbandry. 8vo, 1857. Lectures on Climate. 8vo, 1863. Trees and Shrubs of the Ancients. 8vo, 1865. / ; Miscellanies on Scientific and Literary Subjects. 2 vols. 8vo, 1867. mH Or & Co Go Ixxxi Juuius PricKxer, Foreign Member of the Royal Society, was born on the 16th of July 1801, at Elberfeld. After studying in the Gymnasium of Diisseldorf, and in the Universities of Bonn, Berlin, and Heidelberg, he passed some years in Paris. In 1825 he became a Privatdocent of Mathe- matics in Bonn, and in October 1828 was appointed Professor extraordi- narius in that University. In 1833 he went to Berlin in the same capacity, and lectured also in the Friedrich-Wilhelm’s Gymnasium. In 1834 he obtained the Professorship of Mathematics in the University of Halle, and in 1836 he was appointed Professor of Mathematics in the University of Bonn. The treatises and memoirs on Analytical Geometry written by him during the twenty years that followed his return from Paris secured for him a place among the first mathematicians of his time. He now entered upon a new career; for the superintendence of the Physical Museum having been entrusted to his care, he turned his attention to experimental research, and was appointed to the Professorship of Physics in 1847. A. series of brilliant discoveries soon placed him among the foremost labourers in this department of science. These researches occu- pied him till 1856. In repeating some of Faraday’s experiments, he was led to the discovery of magnecrystallic action,—that is, that a crystallized body behaves dif- ferently in the magnetic field according to the orientation of certain di- rections in the crystal. These researches occupied him till 1856, when he turned his attention to the action of powerful magnets on the luminous electric discharge in glass tubes containing highly rarefied gas. Ina wide tube the light of such a gas is too faint to permit a satisfactory observa- tion of its spectrum; he found, however, that by employing tubes which were capillary in one part, brilliant light and definite spectra were obtained in the narrow part. These spectra were found to be characteristic of the several gases and to indicate their chemical nature, though the gases might be present in such minute quantity as utterly to elude chemical research. In continuing these researches he next made the remarkable discovery of the two totally different spectra of each of the elementary substances, nitrogen, sulphur, selenium, hydrogen, iodine, lead, manganese, and copper, according as it is submitted to the instantaneous discharge of a Leyden jar charged by an induction coil, or rendered incandescent by the simple dis- charge of the coil, or else, in some cases, by ordinary flames. The two spectra were found to exhibit a difference in character, and are not merely different in the number and position of the lines which they show. This difference he attributed, with the greatest probability, to a difference in the temperature of the gas when the two are respectively produced. These results were made known in a memorr by himself conjointly with Dr. 8. W. Hittorf, printed in the Philosophical Transactions for 1865. About this VOL, XVII. g Ixxxil time he resumed his geometrical investigations, but only lived to see the publication of the first part of the treatise upon which he was engaged. He took an active part in the management of the University, having been twice Rector, frequently Dean of the Faculty of Philosophy, for many years Member of the Academic Senate and the Examination Com- mission. He was a Member of the Academies of Munich, Haarlem, Rot- terdam, Lund, and Upsala, of the Société royale de Liege, of the Société des Sciences Naturelles de Cherbourg, of the Société Philomathique of Paris, Honorary Member of the Cambridge Philosophical Society, Corresponding Member of the Institute, of the Academies of Vienna, Gottingen, and the Physikalische Verein of Frankfort; his election as Foreign Member of the Royal Society was in 1855. The Copley Medal for the year 1866 was awarded to him for his researches in Analytical Geometry, Magnetism, aud Spectral Analysis. His separate works are :-— Analyseos applicatio ad geometriam altiorem et mechanicam (Bonne, 1824). Analytisch-geometrische Entwickelungen (Essen, 1831). System der analytischen Geometrie (Berlin, 1835). Theorie der algebraischen Curven (Bonn, 1839). System der Geometrie des Raumes in neuer analytischer Behandlungs- weise (Diisseldorf, 1846, second edition, 1852). Enumeratio novorum phenomenorum in doctrina de magnetismo inven- torum (Bonne, 1849). De crystallorum et gazorum conditione magnetica (Bonne, 1850). Neue Geometrie des Raumes, gegriindet auf die Betrachtung der gera- den Linie als Raumelement (Leipzig, 1868, Erste Abtheilung). He also edited a work by his former pupil, Professor August Beer, entitled “ Hinleitung in die Electrostatic, die Lehre vom Magnetismus und die Electrodynamik,” left in manuscript by the latter at his death. His papers in the ‘ Transactions’ of the Royal Scciety are :— On the Magnetic Induction of Crystals, March 26, 1857. On the Spectra of Ignited Gases and Vapours, with especial regard to the different Spectra of the same elementary gaseous substance, conjointly with Dr. 8. W. Hittorf, February 23, 1864. On a New Geometry of Space, December 22, 1864. Fundamental Views regarding Mechanics, May 29, 1866. He is also the author of numerous papers on analysis, geometry, elec- tricity, magnetism, physical optics, and spectral analysis, in Crelle’s ‘Journal,’ Gergonne’s ‘Annalen,’ Liouville’s ‘Journal,’ Poggendorff’s ‘Annalen,’ the Abbé Moigno’s ‘ Les Mondes,’ the ‘ Philosophical Maga- zine, the ‘ Annali di Matematica.’ He died at Bonn on the 22nd of May, 1868. Ixxxill JEAN BERNARD L£on Foucavtr, Foreign Member of the Royal Society, was born in Paris on the 18th of September 1819. He began the study of medicine, but soon gave the preference to physics and the sciences of observation. At the age of twenty he employed himself in improving the processes of piatormphy. For three years he assisted M. Donné in preparing the illustrations of his lectures on microscopic anatomy, and was associated with M. Fizeau in conducting a variety of original researches. They investigated the comparative intensities of the light of the sun, of the voltaic arc between carbon poles, and of lime heated before the oxyhydrogen blowpipe. They read memoirs on the interference of calorific rays, on the interference of two rays of light in the case of a large difference in the lengths of their routes, and on the chromatic pola- rization of light. In December of 1849 Foucault described an electromag- netic regulator of the electric light. Conjointly with Regnauit he was the author of a paper on binocular vision. He contributed besides several _ memoirs on colour, on voltaic and frictional electricity,‘and on the employ- ment of the conical pendulum as a time-keeper. M. Arago had suggested the employment of Wheatstone’s renee mirror, in a manner eeoapline its use in measuring the propagation of the electric current in a wire, to decide whether the velocity of light within a refractive medium is greater or less than its velocity in air. The former result implies the truth of the emission theory, the latter that of the undulatory theory. The experiment, as devised by M. Arago, was nearly (perhaps quite) impracticable, inasmuch as it depended upon the observa- _ tion of an image of momentary duration formed in an unknown part of the field of view. By the happy introduction of a concave mirror having its centre in the axis of the revolving mirror, a fixed image was obtained ; and the experiment thus rendered possible proved that the velocity of light Is greater in air than in water. This experiment was made in 1850, not _— long after M. Fizeau had approximately determined the velocity of light | in air by measuring the time it occupied in travelling from the place of the - observer to a station 8633 metres distant, and back again. Foucault also suggested the means of measuring the velocity of propagation of radiant heat. In February 1851 he communicated to the Academy the results of his observations on the rotation of the plane of oscillation of a freely suspended pendulum in the direction east-south-west, and thus supplied an ocular demonstration of the diurnal motion of the earth. By the construction of the gyroscope, in September 1852, he gave a second demonstration of the same phenomenon. For these discoveries the Copley Medal for the year 1855 was awarded to him. About this time he was appointed Physical Assistant to the Imperial Observatory. In September of the same year he exhibited a new instance of the conversion of work into heat. A copper Ixxxiv disk being made to revolve rapidly in its own plane, on bringing a horse- shoe magnet into such a position that the disk revolved with its rim be- tween the poles of the magnet, the moving force required to maintain the velocity of rotation increased, and the temperature of the disk was raised. On the 16th of February 1857 he described a reflecting telescope, having a speculum formed of glass coated with chemically reduced silver and afterwards polished, of 10 centims. aperture and 50 centims. focal length, without being aware that a telescope on the same principle and nearly of the same dimensions had been described by Steinheil in the Allgemeine Zeitung of the 24th of March 1856. In the following year Foucault succeeded in giving the speculum the form of a spheroid or of a paraboloid of revolution, and described a new process for finding out the configuration of optical surfaces. A reflector of this description, having an aperture of 40 centims. and 2°5 metres focal length, was mounted in the Imperial Observatory of Paris in June 1859. Another of these reflectors, having an aperture of 78 centims. and a focal length of 4°5 metres, was constructed for the Observatory in 1862. The polarizer known as his was invented in 1857. The project of determining the absolute velocity of light in air with the aid of Wheatstone’s revolving mirror, conceived in 1850, was carried out in 1862. The value Foucault obtained for it was 298,000 kilometres in a second of time, instead of 308,000 kilometres, the previously received value. Combining the newly found velocity with the constant of aberration, 20°445, the sun’s equatorial parallax is found to be 8’"86, the value deduced by Mr. Stone in his recent discussion of the transit of Venus in 1769 being 8"-91, and the value adopted in the ‘ Nautical Almanac’ for 1870 being 8"-95. In this year Foucault was elected a Member of the Bureau des Longitudes. In the years 1863, 1864, 1865 he appears to have been occupied with the task of investigating the conditions of isochronism of Watt’s governor, and modifying its construction so as to render the time of revolution inva- riable. These improved governors are applied to the transit-recorders con- structed for the use of the Indian Survey. In January 1865 he was elected a Member of the Mechanical Section of the Institute. In 1866 he invented a new and improved regulator for the electric light, and a telescope for viewing the sun, in which the light is rendered endurable to the eye by coating the outer surface of the object-glass with a film of chemically re- duced silver so thin as to be transparent. This process was applied with complete success to arefractor having an aperture of 25 centims. In July 1867 he was attacked by paralysis, and died on the 11th of February, 1868. The date of his election as Foreign Member of the Royal Society is June 9, 1864. Ixxxv AnTorne Francors JEAN CLaupet was born at Lyons in 1797. He received a good commercial and classical education in his own country, and at the age of 21 he entered the office of his uncle, M. Vital Roux, an emi- nent banker, whoa few years after placed him at the glass-works of Choisy- le-Roi, as director, in conjunction with M. G. Bontemps, the well-known glass-manufacturer. Eventually M. Claudet came to London to introduce the productions of Choisy. In 1833 be invented the machine now generally used for cutting cylindrical glass. For this invention he received the medal of the Society of Arts in 1853. But all this while he was a student of science training and waiting for the object to which his true life was to be devoted. The path was opened to him by the discovery of M. Daguerre. ' In January 1839 that discovery was first announced to the world, and specimens of the results were exhibited, the modus operandi being still pre- served secret. The French Government at once entertained the project of rewarding the discoverer, and in the following June assigned to M. Da- guerre a pension of 6000 frances annually, and to M. Niépce, jun., a pension of 4000 francs annually, that the new art might be presented a gift to the world. In the month of August 1839 the new discovery was published to the world. It was received with enthusiasm, and rapidly adopted as a means of delineation, portraiture being its most early and extensive application. Kingland alone failed to partake freely of this ‘‘ gift to the world,’ M. Daguerre having entered into negotiations which secured a patent in this country whilst the question of his claims was under the attention of the _ French Government. M. Claudet became the possessor of a part of this patent, and commenced in 1840 the practice of portraiture in the Adelaide Gallery, where his studio remained for many years. ‘There, as a zealous worker, he devoted himself to the improvement and development of pho- tography, perfecting known processes and inventing new ones. His earliest contribution to the art was a mode of obtaining vastly increased sensitive- ness by using chloride of iodine instead of iodine alone. His paper on this subject was read before the Royal Society in June 1841 ; and, by acurions coincidence, it followed Mr. lox Talbot’s description of his own photogra- phic process, the calotype. From this period till his death his contribu- tions to photographic literature were copious and interesting, the idio- matic excellence and elegance of his English being remarkable. In 1847, discussing the properties of solar radiation modified by co- loured glass media, he made a bold attempt to lay the foundation of a more complete theory of the photographic phenomena, and he was re- warded by the publication of his paper in the Philosophical Transactions, and by his subsequent election (in 1853) as a Fellow of the Royal Society. At this time the collodion process had supplanted the method of Daguerre ; and Claudet was one of the first to appreciate and adopt it. The marvellous phenomencn of objects in relief was now brought before him in the stereoscope, and seemed to him a greater charm than the ex- VOL, XVII. h lxxxvi quisite detail of the Daguerreotype. He assisted Sir Charles Wheatstone in the early application of the stereoscope to photography; and in his admirable treatise on the stereoscope he gives the history of the art and the theory of the principles of binocular vision. His great aim was the elevation of photography by rendering her work scientifically true; and the Reports of the British Association during a period of twenty years bear ample testimony to the ingenuity and originality of his inventions. His dynactinometer, his photographometer, his focimeter, his stereomono- scope, his system of unity of measure for focusing enlargements, his system of photosculpture, and other results of his experimental researches are fa- miliar to most photograpners. In the later years of his life he became convinced that one of the greatest deficiencies of photography, in the representation of solid figures, is the in- capability of obtaming an equally well-defined image of all the various parts situated on different planes. Hence it became his object to remove from photographic portraiture the mechanical harshness which marked and marred the plane situated in the exact focus of the lens, and so to pro- duce, as in the best works of art, a uniformly soft and harmonious treat- ment. His success in the first instance was partial, inasmuch as the adopted motion of the posterior lens only of the optical combination slightly altered the size of the superimposed images, and thus introduced a theo- retical, though hardly visible, amount of blurrmg. Dr. Sommer, M. Voigt- lander’s stepson, supplied a series of formule showing that, although for all practical purposes in photography the movement of one lens attained the object in view, yet the simultaneous motion of the two lenses, receding from cr approaching a fixed point between them, was the only legitimate mode of reconciling practice with theory, and of securing in every plane an exact uniformity of image. To fulfil this condition was a difficult pro- blem, the solution of which was most perplexing. But, says Claudet, with a determination which commands success, “‘ I did not like that it should be said my plan was not entirely in accordance with the mathematical laws of optics, and I set to work to find a mechanical means by which I could avail myself of the calculationsof Dr. Sommer. I have found such means and it proves that the differential movement can be effected, not only as readily, but with a greater command and steadiness than by moving only one lens.” His ingenious automatic arrangement is described in his last paper read before the Royal Society, in 1867, and published in the Pro- ceedings, entitled “‘Optics of Photography: on a Self-acting Focus-Equa- lizer, or the means of producing the Differential Movement of the two Lenses of a Photographic Optical Combination, which is capable, during the exposure, of bringing consecutively all the Planes of a Solid Figure into Focus, without altering the size of the various images superposed.” After this, and in the same year, he had an interesting correspondence with his veteran collaborateur Sir David Brewster, who held that the most perfect ‘photographic instrument is a single lens of least dispersion, and lxxxvil least aberration, and least thickness. Claudet realized these views in his portraiture with a small topaz lens, which reached with equal distinctness every plane of the figure. He then communicated the nature and result of his experiments to the British Association at Dundee ; and his work was ~ done. His last illness, in December 1867, was of very brief duration. He suddenly passed away from us, in the 70th year of his age, while his mental powers retained the vigour and freshness of youth ; and by his death pho- tography lost a father, and very many photographers a friend. The scientific life of Claudet is given at length in a “ Memoir” pub- lished in the ‘Scientific Review,’ and reprinted for distribution at the Meeting of the British Association at Norwich in August 1868. In an pendi< there is a list of forty papers communicated from 1841 to 1867 to the Royal and other Philosophical Societies and to photographic and philosophical publications in England and France. Here also we have a striking portrait of this zealous photographer, obtained with his Focus- Equalizer, and printed from the only negative preserved when his “‘ Temple to Photography’ in Regent Street was destroyed by fire, “a few weeks after its chief priest had quitted it for ever.’ In recognition of his merits M. Claudet received awards of eleven medals, including the Council Medal of the Universal Exhibition, 1851, besides that, being on juries, on other great occasions he was excluded from the awards. He was elected a Fellow of the Royal Society in 1853, and in 1865 he was made a Chevalier of the Legion of Honour.—J. B. R. Cuaries JAmMrs Beverty, F.R.S., F.L.S., was born in August 1788, at Fort Augustus in the Highlands, where his father’s regiment was then quartered. He entered the Navy in 1810 as Assistant Surgeon, and was employed in that capacity during four years on the Baltic and Mediterra- nean stations, but chiefly the latter, in H. M. SS. ‘ Pyramus,’ ‘ Resistance,’ and ‘Caledonia,’ during which period he was frequently sent in boats on cutting-out expeditions, and was present at the capture of Porto d’Anzo in 1813. He was then placed on Lord Exmouth’s list for promotion, but, _falling mto bad health, was sent to England in charge of sick and wounded from the fleet. On his recovery he was appointed to the ‘Tiber’ as Assistant Surgeon, and served in that ship till 1818, when, upon a strong recommendation, he was selected by the Admiralty to be Assistant Surgecn in the ‘ Isabella,’ then about to proceed to the polar regions under the command of Sir John Ross. In 1819 and 1820 he served in Sir Edward Parry’s first expedition, and passed the winter at Melville Island, discovered in that well-known voyage. On his return he was promoted to the rank of Full Surgeon, having seen more than ten years’ service in sea-going ships as Assistant Bie an. and being highly commended for his skill and care in his at- tendance on the sick. He subsequently suffered from an affection of his eyes, and immediately on his recovery was nominated most unexpectedly IXXXVlil to the Flagship on the Barbadoes Station as Supernumerary Surgeon. The risk of changing from an arctic to a tropical climate while in weak health forced him to decline the appointment, and he was removed from the list of surgeons. He served in 1827 as a volunteer under Sir Edward Parry in the capacity of Surgeon and naturalist im the long and perilous ice-journey on the Spitzbergen seas. He was elected a Fellow of the Royai Society in May 1831. i After retiring from the Navy, Mr. Beverly entered into private practice in London. We died on the 16th of September, 1868, a short time after attaining the age of 80. 1869. | by Magnetism and Heat. | ' 264. coil by continuously heating the iron wire. In several experiments, by employing twelve similar Grove’s elements as a double series of six intensity, an iron wire 1°56 millim. diameter was made brzghé red-hot ; and by keeping the current continuous until the galvanometer-needles settled nearly at zero, and then suddenly disconnecting the battery, the needles remained nearly stationary during several seconds, and then went rapidly to about 10: this slow decline of the current during the first few seconds of cooling was probably connected with the ‘‘momentary molecular change of iron wire ” during cooling which I have described in the preceding paper. The irregularity of movement of the needles did not occur unless the wire was bright red-hot, a condition which was also necessary for obtaining the molecular change. The direction of the current induced by heating the iron wire was found by experiment to be the same as that which was produced by removing the magnet from the coil; therefore the heat acted simply by diminishing the magnetism, and the results were in accordance with, and afford a further confirmation of, the general law, that wherever there is increasing or decreasing magnetism, there is a tendency to an electric current ina conductor at right angles to it, 1869.] and Viscous Solids by Shearing.” sig” to the Royal Society. On a smaller scale I have made experiments on round bars of brittle sealing-wax, hardened steel, similar steel tempered to various degrees of softness, brass, copper, lead. -Sealing-wax and hard steel bars exhibited the spiral fracture. All the other bars, without exception, broke as Mr. Kirkaldy’s soft steel bars, right across, in a plane perpendicular to the axis of the bar. These expe- riments were conducted by Mr. Walter Deed and Mr. Adam Logan in the Physical Laboratory of the University of Glasgow; and specimens of the bars exhibiting the two kinds of fracture are sent to the Royal Society along with this statement. I also send photographs exhibiting the spiral fracture of a hard steel cylinder, and the “shearing” fracture of a lead cylinder by torsion. These experiments demonstrate that continued “ shearing ” parallel to one set of planes, of a viscous solid, developes in it a tendency to break more easily parallel to these planes than in other directions, or that a viscous solid, at first isotropic, acquires “cleavage planes” parallel to the planes of shearing. Thus, if C D and A B (fig. 2) represent in section two sides of a cube of a viscous solid, and if, by ‘‘shearing”’ parallel to these planes, CD be brought to the position C’ D’, relatively to A B supposed to remain at rest, and if this process be continued until the material breaks, it breaks parallel to A B and C’ D’. The appearances presented by the specimens in Mr. Kirkaldy’s museum attracted my attention by their bearing on an old controversy regarding Forbes’s theory of glaciers. Forbes had maintained that the continued shearing motion which his observations had proved in glaciers, must tend to tear them by fissures parallel to the surfaces of “shearing.” ‘The correctness of this view for a viscous solid mass, such as snow becoming kneaded into a glacier, or the substance of a formed glacier as it works its way down a valley, or a mass of débris of glacier ice, reforming as a glacier after disintegration by an obstacle, seems strongly confirmed by the experiments on the softer metals described above. Hopkins had argued against this view, that, according to the theory of elastic solids, as stated above, and represented by the first diagram, the fracture ought to be at an angle of 45° to the surfaces of “‘shearing.”? There can be no doubt of the truth of Hopkins’s principle for an isotropic elastic solid, so brittle as to break by shearing before it has become distorted through more than a very small angle; and it is illustrated in the” experiments on brittle sealing-wax and hardened steel which I have described. he various specimens of fractured elastic solids now exhibited to the Society may be looked upon with some interest, if only as illustrating the correctness of each of the two seemingly discrepant propositions of these two distin- _ guished men. ol4 Prof. Cayley on Equal Roots of a Binary Quartic. [Feb. 25, V. Note by Professor Cayney on his Memoir “On the Conditions for the Existence’of Three Equal Roots, or of Two Pairs of Equal Roots, of a Binary Quartic or Quintic.” Received February 20, 1869. The title is a misnomer; I have in fact, in regard to the quiutic, consi- dered not (as accordmg to the title and introductory paragraph I should | have done) the twofold relations belonging to the root-systems 311 and 221 respectively, but the threefold relations belonging to the root-systems 41 and 32 respectively. The word “‘quadric,” p. 582, line 1, should be read | ‘“cubic.” The proper title is, “On the Conditions for the Existence of certain Systems of Equal Roots of a Binary Quartie or Quintic.”’ four = =. of sound, and the analysis of the intellectual powers, the supposed decline of science in England, and the philosophy of apparitions. ‘Meliora’ and the Foreign Review each contain two articles from his pen ; one in the latter being a notice of Dutrochet’s ‘Observations sur Endos- mose et Exosmose.’ But it was in the North British Review that the longest series of articles appeared. We have a list before us of seventy-six in the first thirty-nine parts of that quarterly serial, and we doubt whether the enumeration is complete. This shows that, on an average, Sir David wrote two of these literary productions for each part, and suggests the idea that he must have reviewed ev ery book of note that he net The first Number of the North British commences with an article by him, on Flourens’s ‘ Eloge Historique de Cuvier ;’ and further on in the same part he discusses the ‘ Lettres Pro- vineiales’ and other writings of Blaise Pascal. In the second Number he describes the Earl of Rosse’s great reflecting telescope; and shortly we find him engaged with such serious works as Humboldt’s ‘Cosmos’ or Mur- chison’s ‘ Siluria:’ the rival claimants for the honour of having discovered Neptune divide his attention with Macaulay’s ‘History of England,’ or the ‘ Vestiges of the Natural History of Creation.’ With Layard he takes his readers to Nineveh, with Lyell he visits North America, and with Ri- chardson he searches the Polar seas. The Exhibition of 1851, the Peace Congress, and the British Association, come in turn under his descriptive notice ; or turning from large assemblies to individual philosophers, he sketches Arago, Young, or Dalton. In one Number we have “The Weather and its Prognostics,” and “The Microscope and its Revelations :” elsewhere he describes the Atlantic telegraph, whilst in a single article he groups together ‘“‘the life-boat, the lightning-conductor, and the light- house.” He reviews in turn Mary Somerville’s ‘ Physical Geography,’ and Keith Johnston’s ‘ Physical Atlas ;’? the History of Photography engages him at one time, and at another Weld’s History of our Society. Under the guidance of Sir Henry Holland he investigates the curious mental phenomena of mesmerism and electro-biology, and under that of George Wilson he inquires into colour-blindness. He criticises Goethe’s scientific works, expounds De la Rive’s ‘Treatise on Electricity,’ and Arago’s on Comets; or turning from these severer studies, he allows Hum- boldt to exhibit the ‘Aspects of Nature’ in different lands to the multi- farious readers of the Review. In addition to all this Sir David issued some pamphlets of a personal nature—controversial writings which some objected to as unnecessarily per- sistent, though it should be recorded to his honour that he was ces to profit by Badly remonstrance. . Few of his living companions will remember this Nestor in science other- wise than as a venerable form full of vivacity and intelligence, keenly alive not to physical questions alone, but to the various social, political, and eccle- siastical interests of his time, and giving frequent indications of that humble VOL. XVII. i Set nit at Ixxiv faith in God which was the foundation of his character, and which bright- ened his declining years and the closing scenes of his earthly life. His many personal friends will retain his memory in their warm affection. Posterity will know him mainly for having opened up new regions in our knowledge of optical phenomena, and for having given a mignty impulse to science during two-thirds of the nineteenth century. | Jj. Hi. G. | 3 : , SMITHSONIAN INSTITUTION LIBRARIES =" |MMMMINNNMUNILINI wi 3 9088 01305 9753