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SP et | Pata “ “haige be im bree SR Ae Ldeted | aa “he te wea aide ap, Armen, Sara (Wed hag 4 aS We 9 ieeeweh a 4-408 A eee soa Gi Ads ke See Syne Oh Wry qe ea La ret ye ea Bate Vad n oeey COC ak aati stare a ety een he ay matali Deh DOr qe dite eae WOR edad ee Ged g tne Pidew BB PA Hei g, Nets Kaa Went 8 Get Materiay Masha erties hey “ bad edt qed EN tys “ian hs a ae eect ee a Esths 499 Geel adh dene is hee Ree hemged, HW aegare SS Oe pats rit we ns Betas ys Athy A ghts ty it roth tok as Aer Nae seen wan tt the the he Phe om Weer. wate eet ah rd oni ‘ onan tye By ew er ae Pentre ne on ow " Amare Paty tel R=) a 1 har ar ee " ame da WA dee TO 1 oie Na tle bai bee Manone al As Ws aie a ieaee At eas Wedd ne “ae on es ek o na 4 word E ue WG dritedk Geert ai 44: oe tt i fi “sews tb ae . pS % wr Rica whey Ratatat cae Chaba be ee i te Mie AC Hdmi Ag oe « wate tee erg He an Modioe Oe ad Aa ened aw a das oe KS. me " Wiig WG Tae a dear ae bbs banal tL a De he ee ee ae Ghd we ya yd, 4 | 9 +. \batien Ge Wale Weenie. ae dae Wok f fn) “it bait Pee ates Bee hS4 os Betti vera Pirlo ae © RoR omen. carder t i ll ae Wea Ge ‘ donee ‘et 1 nthnn Ct po a ee te te ee F < Aneto. . a er : pti ee: Pv ANA eara Tn cats GPG Ry ‘ ee SS aes Mon 4 Arh HUN aot Haw Rew tint es oo ee ee SLM Na We Mh cok fu ek, Rt at : Ror STatutatariten teat A i sk ates c te Hedineieaane setae =e erftars on SRR hasty pay th A rn ee ee te | oan seas ee ete «+ c i] [ ~n Oe Pha te et . wh) 4 4. daw ae pes “ at Saueaoes eB he +4 dibs WN rg any. Os) « br ble . nl Botte Hone eee > gto HU seed ‘ + statins +iBete®, 4.954: tte EDL i etn’ | At « “ ce a peak hw tt age 2a PhP ase WU othe a ae Herd) | . ae cleat mia ete eae uae ‘ AY a od ey pes bey ALI) SMe amar d G ero wae PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON. From November 21, 1878, to Tria 24, 1879. VOI SOX EET. | ‘See 23 1879 LONDON: HARRISON AND SONS, ST. MARTIN’S LANE, Printers in Ordinary to Her Majesty. MDCCCLXXIX. CONTENTS. VOL. XXVIII. No. 190.—November 21, 1878. Page On a method of using the Balance with great delicacy, and on its Employ- ment to determine the Mean Density of the Earth. By J. H. Poynt- ing, B.A., Fellow of Trinity College, Cambridge, Demonstrator in the Physical Laboratory, Owens College, Manchester. (Plate 1) ou... 2 On Repulsion nee from Radiation. Part VI. Ee William Crookes, MeN PAO Sereda ais anansocuselasaetsvae chests cnssescat MMMMMMm Coste Wius seasveve sy teasseosecsoe ace 35 November 30, 1878. ANNIVERSARY MEETING. EMRE MCLARNON Secs se 8, occ. e cctincat cad. say uocshsveuhavecasdesedssieoreatviebesbaveastevsesoeveaueas 42 List of Fellows deceased since last nerry Bad se dear areca, obese es 42 CECE CR eyes. cuEN a ete ah, anh WANG vet telens ia. Saks MmCaNS 43 MORNE C SILOM G1 ...5c0:cecsedssedesoedescecsecesseetn sorcvccvsedessececs cosecveuvsbevevacneacens 43 Seater ee TMM EMT CALS (25, ccujscaectsesecscvossdeecdusiedestcsseessVescbuscddecedsscedveddeevadtedees 63 PA eremieg im Ota @ OMEN ATIC! OMACETS oo. 6 jeciscceccscsvsecessevacvarcsessosevseconeneconesuedaneceiascers: 68 RSE MIM SPALLING INGA Mees 6.50! op cccssuntucavscvanussontsceduovondenccestessedariSivessteeates 7@, wl Sees SUPERTTIN mere mn ESL, ss ccsvegsacsnsonssonessovaitenscecevantescescegeabesecsseness 72-74 Account of Grants from the Donation Fund in 1877-78 .....cceccessessseeeeees 75 Account of the Appropriation of the sum of £1,000 (the Government Grant) annually voted by Parliament to the Royal Society, to be employed in aiding the advancement of Science .........c.ceccseceesssecsenseseres 15 Account of Appropriations from the Government Fund of £4,000 made by the Lords of the Committee of Council on Education, on the recom- mendation of the Council of the Royal Society” .................ccrscssesoscensees 77 Pmaprotimoteanine Kew COMMILLCE! jceccscescccsaseassessvessencsnsconetsiecesesnssecsanceetenneegecdqeses 80 ILLS Gp SRICCRSYSUTILASS cole oder hos eee eSeEnE er RAR crciian nC eR 98 lv No. 191.—December 5, 1878. On the Illumination of Lines of Molecular Pressure, and the Trajectory of Molecules. By William Crookes, F.R.S., V.P.C.S. ..... Pr cis) oo On a Machine for the Solution of Simultaneous Linear Equations. By oie Wallliammn ER OMISOM )\.cccccoseasessedecanseucensseesenee= ieesceestttaevessesttseesanaeesea December 12, 1878. On the Flow of Water in Uniform Régime in Rivers and other Open Channels. By James Thomson, LL.D., D.Sc, F.RS., and F.R.S.E., Professor of Civil Engineering and Mechanics in the University of GIASSOW ceevvecescsncsscsseasdoecorssnctvera coer teidedGstbaveradseocess-desiecasnesttve SCLISS, cig LRVOTTTE ITT] Fe eR 20 Dt Ne ree OP let ae ee 266 January 23, 1879. Researches on Chemical Equivalence. Part I. Sodic and Potassic Sul- phates. By Edmund J. Mills, D.Sc, F.R.S., “ Young” Professor of Technical Chemistry in Anderson’s College, Glasgow, and T. U. ME RR RE eS eee seco cus couichvanceccuesbacceiniiactsbeatarcuibvadcssdseesesevuneeanisens tiscash cabiieebes 268 v1 Page Researches on Chemical Equivalence. Part IJ. Hydric Chloride and . Sulphate. By Edmund J. Mills, D.Sc., F.R.S., and James Hogarth .... 270 Researches on Lactin. By Edmund J. Mills, D.Sc. F.R.S., “ Young” Professor of Technical Chemistry in Anderson’s College, Glasgow, and James Hogarth .......-..0.00 UE SUE dooms TALON See sccoen eget cote ee 273 On the Microrheometer. By J. B. Hannay, F.R.S.E., F.C.S., lately Assistant Lecturer on Chemistry in Owens College, Manchester ............ 279 Limestone as an Index of Geological Time. By T. Mellard Reade, C.E., REGS a5 EB BAG osc cscs sone vnc so soneseus teste te enstacteet a bctotesnosns soeatetceusecol ae aaenenm 281 Preliminary Note on the Substances which produce the Chromospheric inimes. : -By+J. Norman Jhockyer, PURIS. .scccceccceccsccesceescoansc-opene eee 283 January 30, 1879. On the Effect of Heat on the Di-iodide of Mercury, HgI3. By G. F. Rodwell, Science Master, and H. M. Elder, a Pupil, m Marlborough CONOR eh. cnc Scecesi sch case ave sasespase canstenonsceteresasssean ios ucetatreseean settee 284 A Comparison of the Variations of the Diurnal Range of Magnetic Declination as recorded at the Observatories of Kew and Trevandrum. By Balfour Stewart, F.R.S., Professor of Natural Philosophy in Owens College, Mianchester, and Morisabro Hiraoka: ..,.2..c.cccc ee 288 On the Determination of the Rate of Vibration of Tuning Forks. By Herbert McLeod, F.C.S., and George Sydenham Clarke, Lieut. R.E. .... 291 On certain Means of Measuring and Regulating Electric Currents. By C. William Siemens, D.C.1L., F.R.S. (Plates 4,5) <0... 292 WISEIOR UehESENUSER Ca ce eee jcveacsaveaseendeten te ee 297 No. 193.—february 6, 1879. On certain Dimensional Properties of Matter in the Gaseous State. Part I. Experimental Researches on Thermal Transpiration of Gases through Porous Plates, and on the Laws of Transpiration and Im- pulsion, including an Experimental Proof that Gas is not a Continuous Plenum. PartII. Onan Extension of the Dynamical Theory of Gas which includes the Stresses, Tangential and Normal, caused by a Vary- ing Condition of the Gas, and affords an explanation of the Phenomena of Transpiration and Impulsion. By Osborne Reynolds, F.R.S., Pro- fessor of Engineering at Owens College, Manchester .........ccscecssseveeseesne B04 Absorption of Gases by Charcoal. Part II. Ona new Series of Equiva- lents or Molecules. By R. Angus Smith, Ph.D., FURS. ..ccsccsescsscsseees 322 February 13, 1879. Note on the Development of the Olfactory Nerve and Olfactory Organ of Vertebrates. By A. Milnes Marshall, M.A., D.Sc., Fellow of St. John’s Collese, \Cambrid@e sissies ieealbcautllsu cies Sree be behsedlg eee ea 324 vil . ; Page On the Development of the Skull and its Nerves in the Green Turtle (Chelone midas), with remarks on the Segmentation seen in the Skull mevarious types. (By brotessor W.K. Parker, FURS. .ccccccccessescssesncss, O29 On an Extension of the Phenomena discovered by Dr. Kerr and described by him under the title of “A New Relation between Electricity and Light.” By J. E. H. Gordon, B.A., Assistant Sec. of the British BRM OW Sette ee eee c scat oncsive TREIDRSWBRSWCCR seb ce te Ree Bene eee an ee ee A494 A Summary of an Inquiry into the Function of Respiration at Various Altitudes on the Island and Peak of Teneriffe. By William Marcet, MEMORIES eee aca c cy osnineciescocaysiceasnocsarsueiasanstveededecdso¥ebecdeistvedatasdiveioss 498 Further Researches on the Physiology of Sugar in relation to the Blood. eam em ect IN HRS. nce. cs0sceceuseonn! ace stennvadiees srguquseeeeseeneselessyeleaceatsers 520 Obituary Notices :— emma branwhite: Clarke... ...........0cccossccsensssssesssossassedevetsersssedecs -soenve 1 Pepe MTCO MOTE VON OMIAQEG | 12..Ge.cc.roncsncecechescgascedecserenassantdondesecseocavoavessss iv Cok 2 LS CUD TINGS BRR NES Ra ee Oo REE On OR ee acne er vil ise iy a bisaljontY ak pe fu te BN 3 a ha chee ie r a ve a SO ay 2 f ab ae, Bie Ne 7 } by e eoy eS ata aa Aipoes bet ay : " 4 ns ‘ va f 4 of ety ig : ) ’ mi) ion ‘ : * MY . , i W iy a) t lua 4 i] fi rs f i ° ni nO | Nene He fa a a oe " ih Weal het , a fe n, ; : PERU EY a ae Oe eg iyaaes LO" mh ve Pet e, is he 4 wat is yh Pe Wy 29 res walt & } ee \ re eae othe, bart Souaaeott aay HW pte Wi of 3 * i fA PL . x i : = ¥ + = * i - ¥ _ ut : A « f wr ‘ ‘ ib; ; . Per Pa! a ae " % : , 0 u i \ Sum c = * y \ i & 4 y “ f . t a a OBITUARY NOTICES OF FELLOWS DECEASED. Tue Rev. WitLIAM BRANWHITE CLARKE was born 2nd June, 1798, at Hast Bergholt, county of Suffolk, and educated partly in his father’s house, under the Rey. R. G. Suckling Browne, B.D., a distinguished Hebrew scholar, and Fellow of Dulwich College, and partly at Dedham Grammar School; he entered into residence at Jesus College, Cam- bridge, in October, 1817. He took his degree in January, 1821, and in 1824 became M.A. In May, 1821, he received deacon’s orders from Dr. Bathurst, Bishop of Norwich, and priest’s orders in May, 1823. From May, 1821, to November, 1824, he was trained as curate at Ramsholt, at Nedging and Whatfield, at Chellesworth and Brantham, and then in his native parish. He took advantage of his rector’s per- mission to travel every year, and thus laid the foundation of practical application of the geological and mineralogical lessons he had received at the University, under Professor Sedgwick and Dr. H. Clarke, the great traveller. He made a personal examination of the most cele- brated formations of Europe. He travelled extensively in England and Wales and on the Continent from 1820 to 1839, not omitting a single year. He thus visited the Lake District, the Isle of Man, Staffordshire, Derbyshire, North Wales, the chalk and oolite of York- shire and Lincolnshire, the chalk of Sussex and Normandy, the central and southern parts of France, the Alps and North of Italy, the Nether- lands, Rhenish provinces, Prussia, Belgium, the Ardennes, the tertiary districts of Nassau, the volcanic districts of the Rhine and Moselle. In 1829 he completed his survey of the counties of Suffolk, Norfolk, and Essex. In 1830 he visited the chalk districts and older formations of the frontiers of France and Belgium. Then followed Dorsetshire, West of England, Isle of Wight, Sussex, South- west of Hngland, the coal beds of the Boulonnais, the North of France, the Channel Islands and Isle of Portland, the new red sandstone of Staffordshire, Cheshire, and Lancashire, the Silurian old red sand- stone and coal districts of Shropshire, Herefordshire, Monmouthshire, and South Wales. _ In 1830 and 1831 he was present during many of the stirring scenes of the Belgian War of Independence and the last siege of Antwerp ; at which time also he made the acquaintance of the lady who soon after became his wife, a daughter of Dr. Stather, a gentleman of VOL. XXVIII. ; a ll position in the Island of Nevis. This lady, with a son and two daughters, survives him. In 1833 he was presented to a small vicarage near Poole, where in addition to his clerical duties he discharged the functions of a magis- trate. His ardour in pursuit of travel and geology exposed him to a severe illness which culminated in rheumatic fever, which so crippled him that he was induced in 1839 to try the effects of a warmer climate, and as the investigation of a new country had peculiar charms, he resolved to visit the colony of New South Wales, which im those days included what are now Victoria and Queensland. He had also a kind of special mission from his brother geologists to investigate the carboniferous formation of Australia. The ship in which he was makine the voyage touched at the Cape of Good Hope, and Mr. Clarke seized the opportunity of making a survey of and report upon the geology about Cape Town. From the time he landed in Australia, in 1859, to the day of his death, he never ceased pushing forward his researches into the unknown regions which lay before him. It is no exaggeration to state that he knew every inch of the greater part of New South Wales proper, and from constant investigation of reports by explorers and others he knew the general character and geography, almost topography, of Australasia. The modest income which is supposed to be the lot of those who undertake the duties of a clergyman, and which in the case of Mr. Clarke, averaged, up to 1861, less than £200 per annum, in- clusive of the grant of £1,000 made in recognition of his services, orevented his issuing well illustrated works. Most of his publications appeared in a very modest form, either as Parliamentary papers, newspaper letters, or as papers in the various scientific journals. Latterly, the Government Printing Office offered some relief from the expense of publication, and the last edition of his last work is creditable to that establishment. The Government always had a high appreciation of his services, and never failed when in difficulties to atilise his knowledge. Thus in 1851, when the Government wished to have a proper report upon the mineral resources of the country, no fitter person could be found. The neighbouring colonies also appealed to Mr. Clarke upon all matters of a geological nature. His name was in fact a “ household word ” all over Australasia. It is proved beyond controversy that he ascertained the auriferous nature of the country in 1841, ten years before the popular date of 1851. The main conclusions at which Mr. Clarke arrived from his geological investigations were, that matrix gold was the thing to be looked for, and that the. carboniferous deposits of the main seams in New South Wales were Paleozoic. To a geologist of Europe, with libraries of reference in every city, snd with rapid means of locomotion and comfortable quarters every- ae ri where, the difficulties of Australian geology are not apparent. When Mr. Clarke set out on his explorations there was no other means of travel but horses, with pack-horses for provisions, tents, and instru- ments. In some parts of the country there were no roads or land- marks of any kind, and the maps of the district were nearly useless, as being only skeleton outlines of boundaries. He had to carry on his work single-handed, and gradually to form his own library. Mr. Clarke’s travels extended to Tasmania, Victoria, and Queens- land, and he has written various exhaustive reports relating to these countries. His writings have guided persons to various profitable gold mines, and the successful tin industries of Australia and Tasmania have been commenced from indications furnished by him. In 1863 the Legislature of New South Wales voted Mr. Clarke £3,000, at a time when his various ailments seemed coming to a head, to enable him to secure a little comfort in his old age; but since that time his “pen of a ready writer” has never been weary; and we are almost tempted to say that his latter years have surpassed the former, for his facts seemed to have accumulated more quickly, and his experience being, of course, more matured, enabled him to seize upon the more salient points of the geology of the country. The fruit of his labours during this part of his life consists of a geological map of the whole colony, which has been compiled from his note-books and memoranda. Up to 1870 he never ceased from the work of his sacred calling, even when on his explorations; but on lst October of that year, his in- creasing infirmities obliged him to retire from his parochial labours. He was thus in a position to avail himself of the improved locomotion afforded by the railways to revisit his old haunts, and to visit other places of interest, so as to fill up gaps in his former works. He was an indefatigable observer of meteorological facts and of general natural history. ; Mr. Clarke was elected F.G.S. in 1826. He was a member of the Geological Society of France, and held a diploma from the Imperial and Royal Geological Institution of Austria, F.R.G.S., and one of the early Fellows of the Zoological Society. Mr. Clarke contributed largely to the periodical literature of England prior to 1839, and his poetical effusions are by no means un- deserving of praise. In 1876 he was elected F.R.S., and in 1877 he was awarded the Murchison Medal of the Geological Society of London. The terms in which the award was made express the results of his geological labours in Australia. The excessive heat of March, 1878, combined with the labour of preparing a new edition of “Sedimentary Formations of New South Wales,” proved too much for Mr. Clarke’s strength. He was seized with paralysis on the 16th of that month; and though he rallied, so VOL. XXVIII. b lV that he was able to move about without help, and to arrange and label fossils received from Professor de Koninck on the 15th June, he was seized with a violent pain in the heart on the morning of the 16th, and before medical aid could be procured he was called to his long-earned rest. It is proposed by the Government to purchase his collection of minerals, fossils, library, and geological maps, and with them to form a nucleus, under the name of the “Clarke Collection,” of a grand Mining Museum. ADOLPHE THEODORE BRroneantart, son of the illustrious Alexandre Brongniart, and grandson of Théodore Brongniart, an eminent archi- tect, was born at Paris on the 14th January, 1801. Hducated for the medical profession, he soon gave up that career in order to devote. himself, under his father’s guidance, to scientific pursuits, and early took a place among the first living botanists. In his nineteenth year he published his first and only zoological paper, containing the descrip- tion of Limnadia, a new genus of Crustacea. In the following year he established the genus Ceratopteris for a curious and anomalous aquatic fern. In his twenty-first year he published his first paleontological memoir on the classification and distribution of fossil plants. He reviewed, in this paper, the various plant-remains then known, and grouped them in 4 classes and 19 genera. ‘This memoir has been described as the starting point of the intelligent study of fossil plants. From this beginning Brongniart continued his labours and expounded the fragmentary remains of extinct floras, and traced their relation to living plants, and their position in the vegetable kingdom. He was singularly fitted for this work, for he already had an extensive ac- quaintance with the structure and classification of living plants, and he had so digested his knowledge that he was able to utilize it in the study of these obscure fossils. Seldom has a man made a more brilliant début than Adolphe Brongniart. The memoir on the classifi- cation and distribution of fossil plants, and another, which threw an entirely new light on the subject of the fertilization of living plants, were already finished, if not published, when he was about twenty-four years of age. The study of the reproduction of organic beings had, up to his time, made so little progress that Brongniart obtained little assistance from previous workers. Without committing himself to any of the theories which had been suggested in explanation of the processes of fertilization, he confined himself to the observation and arrangement of facts. ‘Il est certains sujets,” he says, “dont la difficulté éloigne et rebute les observateurs, tandis que la grandeur de leurs conséquences excite au plus haut degré Vimagination des hommes disposés 4 se contenter d’une hypothese. Quant 4 moi, j’ai cherché d’abord 4a les Vv oublier toutes, 4 réunir des faits bien observés, 4 déduire de leur com- paraison des conclusions de détail, et 4 former du rapprochement de celles-ci une théorie propre a les représenter.” Brongniart showed how the embryo is formed, little by little, by a process which he did not hesitate to say is identical over the whole of the vegetable kingdom. Microscopically small plants, the most majestic trees of our forests, our cultivated plants, all are reproduced by one and the same process. For some years Brongniart prosecuted his investigations of living plants, and published, between 1824 and 1827, a new classification of fungi, a memoir on the natural order Bruniacez, and several histo- logical and physiological memoirs. The labours and observations of six years in Paleontology were exhibited in his “ Prodrome d’une Histoire des Végétaux Fossiles,” puplished in 1828, and in his great work, ‘‘ Histoire des Végétaux Fossiles,” begun in the same year. The first volume, consisting of twelve parts, and containing 488 pages of letter-press and 160 quarto plates, was issued within a few months. The further progress of the work was interrupted by Brongniart’s ill health, and it was not resumed for nine years, and then only three additional parts were issued, leaving this great work incomplete. The “‘ Histoire” includes the whole of the Cryptogams, vascular as well as cellular, with the exception of the Lycopodiacez, to which the later plates are devoted; and the letter-press is suddenly stopped before the remarkable introduction to this natural order was completed. In 1839 he brought out his well-known memoir on Sigillaria elegans. In 1849 he contributed to the ‘‘ Dictionnaire Universel d’Histoire Naturelle,” a short and popular review of fossil plants on the plan of his ‘‘ Prodrome,” exhibiting their botanical affinities and classification and their stratigraphical distribution. It is worthy of notice that, as Brongniart began his scientific career with his labours on fossil plants, so the latter part of his life was devoted to a further investigation on the same subject. At the time of his first investigation only few and imperfect specimens had been obtained. Fifty years later his friends, Messieurs Renault and Grand d’Hury, sent him, from the environs of Autun and St. Etienne, a quantity of specimens of seeds which had been converted into siliceous masses of a texture as fine as that of the most beautiful agates. ’ From these masses Brongniart separated transparent flakes, and, by the aid of the microscope, made out minute details of their organiza- tion, cells with excessively thin walls, vessels with delicate membranes, nebulosities which are the first indications of the formation of tissues, organisms, in fact, of dimensions so small as can only be detected by high powers of the microscope. He found, in fruits dating from remote ages, all the particulars of organization which he had formerly observed in living plants. No one had hitherto imagined it possible al that we should one day see in the substance of a hard and translucent stone indications of the sap which had, in former ages, circulated in the delicate vessels of a living plant, of the grains of pollen burst- ing from the anthers, and of the presence of the minute ovules where appearing. In his memoir on this subject, the last he ever published, Brongniart not only disclosed the evidence of a remarkable and varied gymnospermous vegetation in Carboniferous times, but the structure preserved in these Paleeozoic plants led him to suspect the existence of a curious and hitherto unobserved detail in the organiza- tion of the ovule of living Gymnosperms. After having satisfac- torily shown that the beautifully silicified tissues of the plants of St. Etienne belonged to plants of which we find analogous species in Mexico, he confidently asserted that a peculiarity, a cavity for the reception of the pollen, never previously observed in living specimens, would be found in the species of that country, and he subsequently had the satisfaction of exhibiting, to the Académie Frangaise, some plants living in the hothouses of the Museum which had a pollen cavity of which a plant dead countless ages ago had furnished us with the first example. Brongniart did not live to complete this important research. The decline of his health first manifested itself in a failure of sight brought on by excessive use of the microscope, and he owed it to the assistance of his friends and colleagues, Messieurs Bureau, Cornu, Renault, Grand d’Eury, and other friends, that he was able to work on at the investigation as long as he did. From the time of the siege of Paris his health, affected by the privations and sufferings he then underwent, steadily declined, but he retained to the end of his life his tranquillity of mind, his intellect, and his memory. He took an affectionate interest in the progress of a grandson, whose first steps in the career of science he hoped to guide. At length, in February, 1876, fore- seeing that his end was near, he desired to be surrounded by his family, and expired in the arms of his eldest son. Less fortunate than his father, Adolphe Brongniart had, some years previously, lost the affectionate wife whom he had married in early life. He Jeft two sons and several grand-children. The herbarium left by A. Brongniart has been placed in the Botanical Gallery (of Paris), and his unique and beautiful collection of fossil plants forms one of its greatest ornaments. Brongniart was elected a member of the Academy of Sciences in 1834, in the place of Desfontaines, and in the same year he was appointed Professor of Vegetable Physiology in the Museum of Natural History. In 1840 he was appointed a foreign member of the « Geological Society of London, and in the following year he received the Wollaston Medal, in consideration of his important works on fossil plants. Im 1852 he was elected a foreign member of the Vil Royal Society, and was also appointed Inspector-General for Science of the University of Paris. With regard to his scientific character, Brongniart has been charac- terized as the Linneeus of fossil botany; not so much a great discoverer as a great systematizer ; introducing lucid order and general principles into the study of the materials which had been already collected. To those materials, also, he undoubtedly added much by his own observa- tions, and probably (as in the case of Linnzus) his example gave a stimulus to the exertions of his opponents as well as of his followers. He was eminent, not only for industry, accuracy, and judgment, but also for the clearness and neatness of his scientific writings. Brongniart’s favourite branch of study is one in which exceed- ingly rapid progress has been made, since he was at the height of his fame, and in which rapid progress is still making. The researches of Heer, Unger, Httingshausen, and others, in the fossil plants of the Tertiaries, have opened to us almost entirely new departments of Paleo-botany ; the microscopic studies, which have been followed up with so much zeal and success by some in our own country, have thrown a greater amount of new light on the structure of the Paleo- zoic vegetation. But the name of Adolphe Brongniart deserves to be held in honour as long as the sciences of botany and geology are cultivated ; and, however far the knowledge of these subjects may be earried, such works as his treatise on the structure of Sigillaria must always be valued as models of accurate examination, lucid exposition, and caution in drawing conclusions. Adolphe Brongniart’s careful investigation and illustration of the veining of recent ferns (see his ‘‘ Histoire des Végétaux Fossiles,”’ vol. i, p. 148) probably suggested some of the more recent methods of arranging that family of plants. As a teacher he was remarkable for courtesy and kindness, and readiness to help students in that branch of science to which he had devoted himself. Huras Macnus Fries was born at the parsonage of Femsjo, in Smaland, in the southern part of Sweden, on the 15th August, 1794. He appears to have inherited from his father a love of natural history, and his parents carefully fostered and encouraged this taste, in hopes of thereby supplying to him the place of companions and playmates. At the age of twelve he was already familiar with many of the plants of the neighbourhood. In one of his rambles, in 1806, his attention was attracted by the large and peculiar Hydnum coralloides, and it was this discovery, he said in after years, which awakened in him a desire to study the Fungi. The very next day he set to work and learnt the few genera then known from Liljeblad’s Swedish Flora. In the year 1808, when Sweden was ravaged by war and disease, it Vill became necessary to close the school at Wexio, which Fries attended, and he remained for atime at home. He made use of this period of leisure to describe all the Fungi he could find, and before 1811 he had succeeded in distinguishing three or four hundred species, but not having access to books on the subject, he gave them temporary names. In 1811 he left the Gymnasium, and went to the University of Lund. At Lund he continued to give all his spare time to Botany, and had the satisfaction of finding many plants new to him. He spent much of his time in the library studying botanical works, in which he found the names of many of the species he had described. While at Lund he was fortunate enough to make the acquaintance of two dis- tinguished naturalists, Retzius and Agardh, who put into his hands the mycological works of Persoon and Albertini, the best then existing. During the year 1812 he studied Hypodermia (Ustilaginex, Aicido- mycetes). While earnestly studying for the degree of Doctor of Philosophy he still found some leisure for his favourite pursuit. He took the degree of Ph.D. in 1814, and was also in this year appointed Docens of Botany. In 1819 he became ‘‘ Adjunkt” and received the title of Professor in 1834. From the time of taking his degree Fries devoted himself to the study of the Fungi, and went with this view fora time to Copenhagen. About the year 1814 he brought out his earliest important work, his ‘“ Novitize Flore Suecie;’’ and his ‘‘Observationes Mycologice” was published, in the years 1815—1818, at Copenhagen. In 1814 he began to write his ‘‘ Monographia Pyrenomycetum Suecie,” which work he presented in parts from 1816 to 1819 to the Academy of Sciences, in Stockholm. In the year 1816, having come to the conclusion that the method of describing and classifying hitherto adopted was by no means satisfac- tory, Fries began to work out a new system and to make fresh investigations of all the Fungi. This new system was based upon a minute examination of their different stages of development, and of the morphological relations of their different parts. The result of this investigation—the ‘‘ Systema Mycologicum,” in three volumes— he published between the years 1821 and 1829, and a supplement appeared in 1830. In 1828 Fries published his ‘ Hlenchus Fungorum,” in whieh he described some of the Fungi, of which great quantities had been sent to him from abroad. Hitherto Fries had been absolutely prevented by want of means from indulging his ardent wish to explore foreign countries in search of specimens, but in the year 1828 he was at length able to visit the northern part of Germany and the Museum at Berlin, and had the opportunity of extending bis knowledge of Lichens, of exotic Fungi, as well as of studying the literature of these plants. 1X After the publication, in 1829, of the third volume of his “ Systema Mycologicum,” he again subjected the Fungi to a close investigation, comparing them with his own descriptions. Having thus revised and completed his observations, separated the Discomycetes from the Hymenomycetes, &c., he published the results of his observations in his “ Flora Scanica’”’ in 1835. Fries became Demonstrator in Botany at the University of Lund in 1828. In 1834 he was translated to the University of Upsala as Professor of Rural Economy, with which, after the death of Professor Wahlenberg in 1851, the chair of Botany was united. He discharged these teaching duties until 1859, when he retired on a pension. At Upsala he found new fields for his mycological studies, and published his “‘ Hpicrisis Systematis Mycologici sen Synopsis Hymeno- mycetum ” in 1836—1838. In the year 1844 the Academy of Science in Stockholm resolved to be at the expense of a series of engravings of all the species of Fungi principally belonging to Hymenomycetes that could not be preserved in a natural state, and gave the superintendence and direction of this work to Fries. This collection, containing now from 1,600 to 1,700 — coloured figures, is one of the richest and most extensive in existence. | Hleven parts, with 110 plates, have been published under the title ‘“‘Tcones selectee Hymenomycetum nondum delineatorum.”’ These admirable figures, to the preparation of which his latter days were devoted, afford great help to the student in one of the most difficult parts of botany. The last large work of Fries was the “‘ Hymenomycetes Huropei sive Hpicriseos Systematis Mycologici, editio altera,” published in Upsala, in 1874: Fries had also, at an early age, studied the Lichens no less thoroughly than the Fungi, and he essentially reformed the descrip- tions and systematic arrangement of these plants. His “ Licheno- eraphia Huropea reformata,” published in Lund in 1831, was long regarded as a principal work in lichenographical literature, and the successively published parts of his ‘‘ Lichenes exsiccati Suecie,”’ form aremarkably valuable series. He also published explanations and critical examinations of some of the more difficult genera among the higher plants, for instance Mieracium, Salix, Curex, and several others. He wrote Floras of the whole of Scandinavia, and of separate parts of it, and in his “‘ Novitiee Flore Sueciz,” ‘‘Botaniska Notiser,” &c., he gave descriptions of many new plants discovered by himself. His Herbarium Normale, collected at great expense, and with in- credible industry, contains dried specimens of many of the rarest plants of Scandinavia. It was issued in fifteen numbers, during a period of over twenty years, the last being dated 1857, and is con- x sidered to be of the greatest value for the study of the plants of northern Europe. This collection of typical plants is quoted by Fries throughout the first part of his “‘Summa Vegetabilium Scandinavie.” Fries has also written treatises on Agriculture and on Practical Botany, on the Nomenclature of Plants, and on the History of Botany. In the “ Botanical Excursions,” 1852—1864, he has very successfully popularised his science, and the book has been read with lively interest beyond his own country. Important, however, as were many of Fries’ labours on Phzenogamic plants and Lichens, his future fame must rest upon his reformation of Fungology. The brilliant discoveries of later observers seem at first sight to eclipse altegether what was done so many years before, but they are quite in a different line, and doubtless have been assisted by the labours of Fries. His arrangement of the genus Agaricus alone has been described as a great effort of genius, and every division of his mycological system is full of matter for reflection. To appreciate his system, full allowance must be made for the state in which he found mycology and the comparative imperfection of microscopes. Fries was eminent as a systematic botanist, and the Friesian system is still followed by some Swedish writers. The system was first pub- lished in the “ Flora Scanica,” 1835), and an outline of it will be found in Lindley’s ‘‘ Vegetable Kingdom.” With regard to the relationship of species, his point of view appears to have been the same as that taken by Linneeus, “A species is each form brought forth by the Creator in the beginning.”’ Fries had remarkable fluency and power of expression both in writing and lecturing, and this faculty no doubt contributed much to his influence in gathering round him a large number of disciples. Foreign scientific men seldom visited Upsala during the last forty years of his life without making the acquaintance of the celebrated botanist, whose amiable and engaging manners and kind disposition made him beloved by all who knew him. Fries continued his scientific labours into the last years of his life. In his eightieth year he published a new and improved edition of his extensive work ‘‘ Hymenomycetes Huropei,” and about a week before | his death he completed an essay for a foreign periodical. He died on the evening of the 8th of February, 1878, to the last actively useful. In 1851, Fries had been appointed Director of the Botanical Museum and garden attached to the University of Upsala, and in 1853 became Rector of the University. He was a member of mary learned societies, Swedish and foreign. In 1835 he was elected a Foreign Member of the Linnean Society, and in 1875, a Foreign Member of the Royal Society. PROCHKEDINGS OF i OLA SOCTET Y. 0 DOWD OWA ANAND November 21, 1878. Sir JOSEPH HOOKER, K.C.S.I1., 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 Council proposed for election was read as follows :— President.—William Spottiswoode, M.A., D.C.L., LL.D. Treasurer.—John Hvans, F.G.S., F.S.A. Professor George Gabriel Stokes, M.A.,D.C.L., LL.D. Professor Thomas Henry Huxley, LL.D. Secretaries.— Foreign Secretary. Alexander William Williamson, Ph.D. Other Members of the Cowncil.—F rederick A. Abel, C.B., V.P.C.S. ; Willam Bowman, F.R.C.S.; Wiliam Carruthers, V.P.L.S.; Major- General Henry Clerk, R.A.; William Crookes, V.P.C.S.; Sir William Robert Grove, M.A.; Augustus G. Vernon Harcourt, F.C.S.; Sir Joseph Dalton Hooker, C.B., K.C.S.I., D.C.l.; Admiral Sir Astley Cooper Key, K.C.B.; Lieut.-General Sir Henry Lefroy, C.B.; luord Lindsay, P.R.A.S.; Sir John Lubbock, Bart., V.P.L.S.; Lord Rayleigh, M.A.; Charles Wiliam Siemens, D.C.L.; John Simon, C.B., D.C.L.; Professor Allen Thomson, M.D., F.R.S.H. The Presents received were laid on the table, and thanks ordered for them. The Rey. Thomas George Bonney, Dr. John Hughlings Jackson, and Mr. Edward Alfred Schafer were admitted into the Society. General Boileau, General Clerk, Mr. J. Evans, Dr. Gladstone, and Mr. Simon having been nominated by the President, were elected by ballot Auditors of the Treasurer’s Accounts on the part of the Society. VOL. XXVIII. | B 2 Mr. J. H. Poynting on a method of [Nov. 21, The following Papers were read :— I. “On a method of using the Balance with great delicacy, and on its employment to determine the Mean Density of the Earth.” By J. H. Poyntine, B.A., Fellow of Trmuity College, Cambridge, Demonstrator in the Physical Labora- tory, Owens College, Manchester. Communicated by Pro- fessor B. STEWART, F.R.S. Received June 21, 1878. [Prats 1. | In the ease and certainty with which we can determine by the * balance a relatively small difference between two large quantities, it probably excels all other scientific instruments. By the use of agate knife edges and planes, even ordinary chemical balances have been brought to such perfection that they will indicate one-millionth part of the weight in either pan, while the best bullion balances are still more accurate. The greatest degree of accuracy which has yet been attained was probably in Professor Miller’s weigh- ings for the construction of the standard pound, and its comparison with the kilogramme, in which he found that the probable error of a single comparison of two kilogrammes, by Gauss’s method, was Ua part of a kilooramme:= (¢ lebih iranse aslo) But, though the balance is peculiarly well fitted to detect the relatively small differences between large quantities, it has not hitherto been considered so well able to measure absolutely small quantities as the torsion balance. ‘The latter, for instance, was used in the Cavendish experiment; when the force measured by Cavendish was the attraction of a large lead sphere upon a smaller sphere, weighing about 14]1bs., the force only amounting to z5p/sq50th part of this weight, or about =>4,5th part of a grain. The two great sources of error, which render the balance inferior to the torsion balance in the measurement of small forces, are :— 1. Greater disturbing effects produced by change of temperature, such as convection currents and an unequal expansion of the two arms of the balance. 2. The errors arising from the raising of the beam on the support- ing frame between each weighing, consisting of varying flexure of the beam and inconstancy of the points of contact of the knife edges and planes. The disturbances due to convection currents interfere with the torsion balance as well as with the ordinary balance, though they are * Even so far back as 1787, Count Rumford used a balance which would indicate one ina million and measure one in seven hundred thousand. (“Phil. Trans.,” 1739.) 1878. | using the Balance with great delicacy, &c. 3 more easily guarded against with the former, by reason of the nature of the experiments usually performed with it. They might, perhaps, as has been suggested by Mr. Crookes, be removed from both by using the instruments in a partial vacuum, in which the pressure is lowered to the ‘“‘ neutral point,” where the convection currents cease, but the radiometer effects have not yet begun. But a vacuum balance requires such complicated apparatus to work it, that it is perhaps better to follow the course which Baily adopted in the Cavendish experiment. He sought to remove the disturbing forces as much as possible, and to render those remaining as nearly uniform as possible in their action during a series of experiments, so that they might be detected and eliminated. For this purpose the instrument was placed | in a darkened draughtless room, and was protected by a thick wooden casing gilded on its outer surface. Most of the heat radiated from the surrounding bodies was reflected from the surface of the case by the gilding. The heat absorbed only slowly penetrated to the in- terior, and was so gradual in its action, that, for a considerable time, the effect might be supposed nearly uniform. Under this supposition it was then eliminated by the following method of taking the observa- tions. The resting point (that is the central position of equilibrium, about which the oscillations were taking place) of the torsion rod, at the ends of which were the small attracted weights, was first observed when the two large masses pulled it in one direction. The masses were then moved round to the opposite side, when they pulled the rod in the opposite direction and the resting point was again observed. The masses were then replaced in their original position and the resting point was observed a third time. These three observations were made at equal intervals of time; if, then, the disturbing effect was uniform during the time, the mean of the first and third observations gave what the resting point would have been, had the rod been pulled in that one direction at the same time that it was actually observed when pulled in the opposite direction. The difference between the second resting point and the means of the first and third might, therefore, be considered as due to the attractions of the masses alone. In the experiments of which this paper contains an account, I have endeavoured to apply this method of introducing time as an element to the ordinary balance. But, before it could be properly applied, it was necessary to remove the errors due to the raising of the beam between successive weighings, as they could not be considered to vary in any uniform way with the time. I think I have effected this satis- factorily, by doing away altogether with the raising of the beam by the supporting frame, between the weighings. For this purpose I have introduced a clamp underneath one of the pans, which the observer can bring into action at any time, to fix that pan in whatever position it may be. The weight can then be removed from the pan, B 2 A Mr. J. H. Poynting on a method of [Nov. 21, and another, which is to be compared with it, can be inserted in its place without altering the relative positions of the planes and knife edges. The counterpoise in the other pan, meanwhile, keeps the beam in the same state of flexure. The pan is then unclamped and the new position about which it oscillates is observed. The only changes are due to the change in the weight and the effect of the external disturb- ing forces; the latter we may consider as proportional to the time, if sufficient precautions have been taken, and by again changing the weights and again observing the position of the balance, we may eliminate their effects. Though the method when applied to the balance does not yet give such good results as Baily obtained from the torsion balance—partly, I believe, because I have not yet been able to apply all his precautions to remove external disturbing forces—it still gives better results than would have been obtained without it. This may be seen by the numbers recorded in the tables, where a progressive motion of the resting point may be noticed in most cases, in the same direction, during a series of experiments. Hven when this is not the case, the method at once shows when the disturbing forces are irregular, and when we are justified in rejecting an observation on that account. I give in this paper two applications of the method, one to the comparison of two weights, the other to the determination of the mean density of the earth. The latter is given only as an example of the method, but I hope. shortly to continue the experiments with a large bullion balance, for the construction of which I have had the honour to obtain a grant from the Society. The balance is now in course of construction, by Mr, Oertling, of London. Description of the Apparatus. The balance which I have employed is one of Oertling’s chemical balances, with a beam of nearly 16 inches, and fitted with agate planes and knife edges. It will weigh up to a little more than 1 lb. To protect it from sudden changes of temperature, the glass panes of the case are covered with flannel, on both sides of which is pasted gilt paper, with the metallic surface outwards. This case is enclosed in another outer case, a large box of inch deal, lined inside and out with gilt paper. The experiments have been conducted in a darkened cellar under the chemical laboratory at Owens College, which was kindly placed at my disposal by Professor Roscoe. As the ceilings and floors of the building are of concrete, any movement near the room causes a considerable vibration of the floor and walls. It was necessary, therefore, to support the balance independently of the floor. For this purpose, six wooden posts (A, B, C, D, H, F, fig. 1) were erected resting on the ground underneath and passing freely through the floor to a height of 6 feet 6 inches above it. They are connected at 1878. ] using the Balance with great delicacy, §c. 5 the top by a frame like that of the table, and stayed against each other to give firmness. The wider part of the frame, near the posts E and F, is boarded over to form a table for the telescope (¢, fig. 1) and scale (s), by which the oscillations of the balance are observed. The box containing the balance rests on two cross pieces, on the narrower part, ABCD, of the frame, with the beam parallel to AD, and its right end towards the telescope. In order to observe the position of the beam, a mirror, 14 inches by 3 inch, is fixed in the centre of the beam, and the reflection of a vertical scale (s, fig. 1) in this is viewed with a telescope (¢) placed close to the scale. The light from the scale passes through two small windows cut in each of the cases of the balance and glazed with plate glass. The position of the beam is given by the division of the scale upon the cross line on the eyepiece of the telescope. The scale, which was photographed on glass, and reduced from a large scale, drawn very carefully, has 50 divisions to the inch. These are ruled diagonally with ten vertical cross lines. It is possible to read, with almost certainty, to a tenth of a division, or =3,th of an inch. Since the mirror is about 6 feet from the scale, a tenth of a division means an angular deflection of the beam of about 3”".* The scale is illuminated from behind by a mirror (m), several inches in diameter, which reflects through it a parallel beam from a paraffin lamp (J). A plate of ground glass between the scale and mirror diffuses the light evenly over the scale and, by altering the position of the mirror, any desired degree of brilliancy may be given to the illumination of the scale. A screen (not shown in fig. 1) prevents stray light from striking the balance-case. This method of reading—which, of course, doubles the deflection— has been so far sufficiently accurate for my purpose; that is to say, the errors arising from other sources are far greater than those arising from imperfections of reading. But in a long series of preliminary experiments I used the following plan to multiply the deflection still further. A rather smaller fixed mirror, ab, is placed opposite to and facing the beam-mirror, AB, fixed on the beam, and a few inches from it. Suppose the beam-mirror to be deflected from the position BL, parallel to ab, through an angle, 6, to the position AB. If a ray, PQ, perpendicular to ab strikes AB at Q, it will make an angle, 0, with QM, the normal at Q, and will be reflected along QR, making an angle, 20, with its original direction, and therefore with the normal RO, at R, when it strikes it. If it be reflected again to AB at §, it will make an angle, 36, with the normal SN, and the reflected ray, ST, will make an angle, 40, with the original direction, PQ, of the ray. It may be still further reflected between the two mirrors, if * The numbers on the scale run from below upwards, so that an increase in the weight in the right hand pan is indicated by a lower number on the scale. 6 Mr. J. H. Poynting on a method of [Nov. 21, desirable, each reflection at the mirror, AB, adding 26 to the deflection of the ray. I have, for instance, employed three reflections from the beam-mirror, so multiplying the deflection six times. In this case, one division of my scale, at the distance at which it was placed from the beam, corresponded to a deflection of 7” in the beam, and this could be subdivided to tenths by the eye. The only limit to the multiplication arises from the imperfection of the mirrors and the decrease in the illumination of the successive refiections.* The chair of the observer is placed on a raised platform, and a small table rising from the platform and free from the frame on which the instruments rest, is between the observer and the telescope. On this he can rest his note-book during an experiment. As the differences of weight observed are sometimes exceedingly minute, the balance is made very sensitive—usually vibrating in periods between 30’’and 50”. The value of a division of the scale cannot be determined by adding known small weights to one pan, as the deflection would usually be too great. Any approach of the observer to the case causes great disturbances, so that the ordinary method of moving a rider an observed distance along the beam is inapplicable. In some experiments made last year I calculated the force equivalent to the small differences in weight, in absolute measure, by observing the actual angular deflec- tion and the time of vibration. With a knowledge of the moment of inertia of the beam and treating it a$ a case of small oscillations, it was possible to calculate the value of the scale. But the observa- tions and subsequent calculations were so complicated that the following method of employing riders was ultimately adopted. A small bridge about an inch long (fig. IT, 1) is fitted on to the beam. The sides of the bridge are prolonged about half an inch above the * This method was used in the seventh and eighth series here recorded. Two reflections from the beam mirror were employed, giving four times the actual deflec- tion. 1878. ] using the Balance with great delicacy, Sc. 7 arch which fits on to the beam, as shown in the end view (oI, 2). im each of these sides are cut two V-shaped notches directly opposite to each other, one of the opposite pairs being 6°654 millims. (about } inch) distant from the other pair. Two equal riders of the shape shown in fig. IT, 3, are placed across the bridge, and are of such a size that they will just fit into the bottom of the notches. When one of these rests across the bridge the other is raised up from it. The lowering of one rider and the raising of the other corresponds herefore to a trans- ference of a single rider from one pair of notches to the other. The length of the half beam being 202°716 millims. and the distance between the notches 6°654 millims., this transference will be equivalent to the addition to one pair of 3:03284 of the weight of the rider used. As I have generally used a centigramme rider this means 0°3284: mems. Two levers ll’ (fig. II, 4:), with hooks hh’ are used to raise one rider while the other is lowered. These levers are worked by two cams cc’ on arod R, which is prolonged out of the balance case to the observer. By turning this rod round, the one lever is raised while the other is depressed. The hook at the end of the raised lever picks up its rider while the other hook deposits its rider on the bridge, and then sinks down between the raised sides (as shown in fig. II, 4), leaving the rider resting freely on the bridge. The levers are so adjusted that the beam even in its greatest oscil- lations never comes in contact with the hooks. This arrangement might probably be still further perfected by intro- ducing two small frames for the riders to rest upon, the frames resting on the beam by knife edges. It would then be certain that the movement of the riders was equivalent to a transference from one knife edge to the other, whereas the rider at present may not rest exactly over the centre of the notch. But I find that I get fairly consistent results by lowering the rider somewhat suddenly so as to give it sufficient impetus to go to the bottom of the notch, and have not therefore thought it necessary as yet to introduce more complicated apparatus. In place of the right hand pan of the usual shape, another of the shape shown in fig. III, 1, is employed. To the centre of the pan un- derneath is attached a vertical brass rod which passes downwards through the bottom of the inner case of the balance. To the under side of this case is attached the clamping arrangement before referred to. ‘I'his consists of two sliding pieces (fig. IV, 1, ss) working hori- zontally in a slot cut in a thick brass plate which is fastened to the ease. Through a circular aperture in this plate (the slot is not cut through the whole thickness of the plate, but only as shown in fig. IV, 2) and about the middle of the slot hangs the rod r attached to the scale pan. By means of right and left handed screw on a rod R, which is pro- 8 Mr. J. H. Poynting on a method of [Nov. 21, longed out of the case to the observer, these two sliding pieces can be made to approach, and clamp the rod, or to recede and free it. By having the opposite surfaces of the sliding pieces and the rod polished and clean, it is possible to clamp and unclamp without producing any disturbance. The clamp is of great use also to lessen the vibrations when they are too large, as it may be brought into action at any moment, and on releasing carefully the beam will start again from rest without any impetus. It may be used too to increase the vibrations by releasing suddenly when the beam will have a slight impetus in one direction or the other. The weights which I have compared are two brass pounds avoirdu- pois, made for me by Mr. Oertling, and marked A and B respectively. They are of the usual cylindrical shape with a knob at the top (fig. III,2). Two small brass pans (fig. III, 3) with a wire arch by which they can be suspended, are used to carry them; these are called respectively X‘and Y. I found on beginning to use them that there was too great a difference between A and B. I therefore adjusted them by putting a very small piece of wax upon A, the lighter. But the difference between them increased by 0:0782 mgm. in two days, which I thought was probably due to the wax. After the fourth series I therefore removed it and scraped B till it was more nearly equal to A. The weighings I—IV have, however, been retained, for though the differences on different days vary they are fairly constant on the same day. The weights are changed by the following apparatus which has been designed to effect the change as simply and quickly as possible. A horizontal “side rod” or link (ss, fig. V) is worked by two cranks (cc, fig. V, 2), which are attached to the axles of two equal toothed wheels (it) with a pinion (jp) connecting them. A second pinion (q), on a rod prolonged out of the case to the observer, gears with one of the toothed wheels. By turning this rod the toothed wheels are set in motion, both in the same direction, moving the horizontal “side rod” from the right say upwards and over to the left. A pin (pn) stops its motion downwards further than is shown in fig. V, 1. Near each end of the rod is cut a notch, and across these are hung the pans carrying the weights. The apparatus is fastened to the floor of the case between the central upright supporting the beam and the scale pan, the side rod being perpendicular to the direction of the beam, and exactly over the centre of the pan. In fig. V, 1, one of the weights B is supposed to be resting on the scale pan (the wires suspending the pan from the beam not being shown), the side rod having moved down so far below the wire of the smaller pan carrying the weight that it leaves it quite free. If, now, it is desired to change the weights the rod R is turned, setting the wheels in motion, the side rod moves up, picks up B—the notch catching the wire—then travels 1878. ] using the Balance with great delicacy, &e. op over round to the extreme right, when A will be just over and nearly touching the scale pan. By continuing the motion slightly A will be gently deposited on the pan, and the side rod will move slightly down leaving the weight quite free. On the scale pan are four pins, turned slightly outwards, acting as guides for the small pan, and ensuring that it shall always come into the same position. The wheels and inions are of such a size that two revolutions of the rod just suffice to change one weight for the other. It will be seen that all the manipulation required from the observer during a series of weighings is the simple turning of three rods, which are prolonged out of the balance case to where he is stationed at the telescope. By turning one of these he can change the position of the rider on the beam by a known amount, and so find the value of his scale. By turning a second he clamps the scale pan, and so steadies the balance while the weights are changed by turning a third rod. I have made this arrangement not only because it seems as simple as possible to secure the end required, but also because it seemed more applicable to a vacuum balance (with which I hope ultimately to test it). I take this opportunity of expressing my thanks to Mr. Thomas Foster, mechanician of Owens College, for his aid in the construction of the apparatus, and in the planning of many of its details. Method of conducting a Series of Weighings. After the counterpoise has been adjusted so that the beam swings nearly about its horizontal position, the frame is lowered so that the balance is ready for use. The pan is then clamped and the balance is left to come to a nearly permanent state of flexure if possible, some- times for the night or even longer. The lamp is lighted usually half- an-hour or more before beginning to observe, so that its effect on the balance may attain a more or less steady state. It is necessary also to wait some time after coming into the room, for the opening of the door will always cause a considerable and immediate deflection of the beam. When a sufficient time has elapsed, the observations are com- menced with a determination of the value of one scale division by means of the riders. The three extremities of two successive oscilla- tions are observed with one of the riders resting on the beam. These are then combined as follows:—The mean of the first and third is taken, and the mean again of this and the second, this constituting the “resting point,’ that is, the position of equilibrium of the beam at the middle of the time. For instance, in weighing No. I (see tables at the end) the three extremities of successive oscillations were 280°5, 312°0, and 286°0 (column 2). The resting point was taken as— 280°5+ 286-042 x 312-0 ry 297°62, 10 Mr. J. H. Poynting on a method of [ Nov. 21, the rider on the beam being the right hand one denoted by R, column 1. The balance is the clamped, and the other rider is brought on to the beam while the first is taken up. The resting point is again observed. In No. I it was 270°05. The balance is again clamped, and the first rider again brought on the beam, and in unclamping the resting point again observed. In the same weighing it was 296775. These three are sufficient to give one determination of the deflection due to the transference of a rider. This will be the difference between the second resting point and the mean of the first and third. For eRernce, ee divisions. ‘This’ aveieeee found in the fifth column. This process is continued, the resting points being combined in threes till several values of the deflection due to the rider have been obtained, and the mean of these is taken as the true value. This plan of com- bining the resting points requires that the observations should be taken at nearly equal intervals. After a little practice it will always take the observer about the same time to go through the same opera- tions of clamping, changing the riders, unclamping, clamping again to lessen the vibrations about the new resting point, and then beginning to observe, and I have considered that this was a sufficiently correct method of timing the observations. When a series has been taken it will at once be seen whether they were begun too soon after entering the room, or whether any irregular disturbing force has acted. For instance, in weighing No. II, determi- nation of one scale division, the first resting pomt is so much lower than the succeeding with the same rider that evidently the balance was still affected by my entrance into the room. It was, therefore, rejected. Again, in weighing No. III determination of the difference between the weights, the fourth resting point was much lower than the others with the same weight in the pan. ‘The resting points, when the other weight was in the pan, showed no similar sudden drop of such magni- tude. This observation was, therefore, rejected as being affected by some irregular disturbance. When the value of the deflection is determined, the value of one scale division is at once found by dividing *3282 mgm. by the number of divisions of the deflection, since the charge of the sides is equivalent to the addition of °3282 mgm. to one pan. The determination of the difference between the weights is then begun. This is carried on in a precisely similar manner, the only difference being, that the rod changing the weights is now turned round in place of the rod changing the riders. I have usually taken a greater number of observations of the difference between the weights than of the deflection due to the riders, as the former is somewhat more irregular than the latter. This irregularity I believe to arise 1878. ] using the Balance with great delicacy, Sc. it from slight differences of temperature of the two weights, and perhaps from air currents caused by their motion inside the case. They do not seem to be due to any fault in the clamping arrangement, since that is employed equally in both, and the changing of the weights, if effected gently, does not move the beam at all. When the deflection has been determined, it is multiplied by the number of milligrammes corresponding to one scale division, and this, of course, gives the difference between the weights. I have inter- changed the weights in the two pans X and Y, between the series of weighings, in order to make the experiments like those conducted in the weighings for the standard pound. But my object has not been to show at all that the method gives consistent results day after day, and, in fact, the difference between the weights has varied. For instance, according to weighings i and Il, A—~B=-0446, while, according to weighings III and IV, A~B=-0232. There is a greater difference between these than can be accounted for by errors of experiment, and it probably arose from the small piece of wax with which I made A nearly equal to B. The difference between the weights when measured to such a degree of accuracy as that which I have attempted, will, no doubt, vary from time to time, partly with deposits of dust, partly with changes in the moisture in the atmo- sphere, and so on. But I think the numbers which are given in the tables are sufficient to show that the difference between two weights in any one series of weighings can be measured with a greater degree of accuracy than has hitherto been supposed possible. I give in the tables a full account of the weighings, each series coutaining a determination of the value of one scale division and a determination of the difference between the weights. The greatest deviation of any one of a series from the mean of that series of differences is always given. This I consider a better test of accuracy of weighing than the probable error. What is wanted in weighing is rather a method which will give at once a good determination of the difference between two weights. But I may state, that if the error of any one of a series be taken as its difference from the mean of that series, the probable error of a single determination of the difference between the weights in the first four series is °4344 of a division, or ‘0054 mgm., that is, szocssspth of the total weight, while the greatest error is 1:8 divisions, or ‘0224 mgm., that 1s s5ocon00th of the total weight. It may be remarked that these weighings were all made during peculiarly unfavourable weather when there were frequent heavy showers, causing sudden changes of temperature, and thus seriously affecting the working of the balance. In the series V—VIII the greatest error is only soocpo00 Of the total weight, the weather having improved considerably. 12 Mr. J. H. Poynting on a method of [Nov. 21, On the Employment of the Balance to determine the Mean Density of the ) Earth. In the Cavendish experiment, the attraction of a large sphere of lead of known mass and dimensions upon another smaller sphere also of known mass and dimensions, is measured when the two are an observed distance apart. Comparing this attraction with the weight of the small sphere—that is the attraction of the earth upon it—and knowing the dimensions of the earth, we can deduce the mass of the earth in terms of the mass of the large lead sphere, and so obtain its mean density. The torsion balance, which was invented for the pur- pose by Mitchell, the original contriver of the experiment, has hitherto been used to determine the force exerted by the mass upon the small sphere. In the arrangement here described, I have replaced the torsion balance by the ordinary balance, and have so been able to compare the attraction of a lead sphere with that of the earth upon the same mass somewhat more directly. The results which I have obtained have no value in themselves, but they serve as an example of the employment of the balance for more delicate work than any which it has as yet been supposed able to perform. The method is shortly this :—A lead weight (called ‘the weight ”’) weighing 452°92 grms. (nearly 1 lb.) hangs down by a fine wire from one arm of a balance, from which the pan has been removed at a distance of about six feet below it, and is accurately counterpoised in the other pan, suspended from the other arm. A large lead mass (called ‘the mass”) weighing 154,220°6 grms. (340 Ibs.) is then introduced directly under the hanging weight. The attraction of this mass increases the weight slightly and the beam is deflected through an angle which is observed. The value of this deflection in milli- grammes is measured by the employment of riders in the manner described above, and so the attraction of the mass is known. The increase of the weight caused by the mass has been in my experiments about ‘01 of a milligramme, or gsgg'op50th of the whole weight. The balance which I have used is that which I have described above. It was placed in the same room and in the same position as in the weighing experiments. The same method was used to observe the oscillations with a single mirror on the beam. The scale was a simple one etched on glass and not diagonally ruled. It had about 50 divisions to the inch, and the numbers increased from above down- wards, so that an increase in the weight hanging from the left arm was indicated by a lower number on the scale. The weight which is suspended by a very fine brass wire from the left arm, passing through a hole in the bottom of the balance case, hangs in a double tin tube, 4 inches in diameter, to protect it from air currents. At the botttom of the tube is a window, through which can 1878. ] using the Balance with great delicacy, 5c. 13 be seen the bottom of the weight as it hangs. The weight is 4°248 centims. in diameter and is gilded. The mass is a sphere of an alloy of lead and antimony. It was cast with a “head” on and then accurately turned. Its vertical diameter is 30°477 centims. (about 1 foot). The specific gravity of a specimen of the metal was found to be 10-422. Its weight given by a weighing machine is 340 lbs. about, and this agrees very nearly with the weight calculated from the specific gravity. Jam obliged to accept this as the true weight pro- visionally, until it is found more correctly by the large balance referred to above and now being constructed. This mass (fig. I, M) is placed in a shallow wood cup at one end of a 2-inch plank, 8 inches wide and 6 feet 11 inches long, mounted on four flanged brass wheels, and serving as a carriage for it (fig. I). A plank about 12 feet long nailed to the floor in a direction perpendicular to the beam of the balance, as shown in fig. I, pp, acts as a railway for the carriage, and a firm stop at each end prevents the carriage from running off the rail. The distance between the stops is rather less than twice the length of the carriage, and the weights hangs down from the balance exactly midway between the stops. The mass is placed on the carriage so that it is exactly under the weight when the carriage is at one end of its excursion against one of the stops. An empty cup (c, fig. 1) of the same dimensions as that in which the mass rests is placed at the cther end of the carriage, and is just under the weight when the carriage is against the other stop. By this arrangement no correction is needed for the attraction of the carriage upon the weight or counterpoise, and the effect caused by the removal of the carriage from one end of its excursion to the other is entirely due to the differ- ence of attractions of the mass upon the weight and counterpoise in its two positions. The position of the mass when directly under the weight is called its “in position,” and that when it is at the other end of its excursion is called the “out position.” The length of the excur- sion is 5 feet 7°3 inches. To draw the carriage along the rail a vertical iron shaft with a wood cylinder at the lower end, pivots on the floor, and is prolonged up to the level of the observer as he sits at the telescope with a handle by which he can turn it, The two ends of a rope which winds round the cylinder pass through pulleys on the stops, and are attached to the ends of the carriage. The. observer can then move the mass with great ease by turning the handle, even while looking through the tele- scope. When a series of observations is made, the general method is this. The deflection (7) due to the transference of a rider from one notch to the other on the beam is first observed exactly in the manner before described, the mean of four or five values being taken as the true value. Then the deflection (7) due to the difference of attraction of 14 Myr. J. H. Poynting on a method of [Nov. 21, the mass in its two positions is found in exactly the manner in which the difference between two weights 1s found, except that now when three successive extremities of oscillations have been observed for a resting point the mass is moved from one position to the other where the weights were changed in the former experiments, the clamp not being brought into action. The second extremity of the oscillation which is proceed- ing while the mass is moved, is observed as the first of the next three. When nine or more resting points have been observed they are com- bined in threes, and the mean of the resulting values of the deflection n is used in the subsequent calculation. This deflection is, of course, less than that which would be observed were there no attraction on the counterpoise, and were the out position of the mass at an infinite distance. To find the factor f by which the deflection n due to the change of position of the mass must be multi- plied in order to reduce it to the deflection which would be observed under these conditions, let AB be equal and parallel to the beam of the balance at the level of the counterpoise of which B is the centre. Let C be the centre of the weight, D that of the mass in its in position, E that of the mass in its out position. Draw BF, DF, parallel to AD, AB. Let » = the mass. The vertical attraction of the mass in its in position will be— ay aE Cy? ED) The vertical attraction in its out position will be— wCD_ «BF CE = (Bie The difference between these is actually observed, viz. : ; “ pe ey CD? BD?) «CH? ;) @SniaeG 1878. ] using the Balance with great delicacy, &c. 15 The factor by which we must multiply the observed difference to reduce it to the attraction of the mass on the weight in its in position is therefore— CD BH C2) CL BE Pe Te CHa), BEE = b-OlSd since CD= 22°13 centimetres. EAA cB ale as Bh s70 * CH=172:36 i = 2/09 “3 The values of rand 7 being observed, the distance between the centres of the mass and weight d is then measured by adding 17°362 centims. to the sum of their radi, the distance from the top of the mass to the bottom of the weight as measured by a cathetometer. It now remains to explain the calculation of the mean density A from the observed values of 7,7”, and d. We have— f X increase in weight observed __ Attraction of mass on weight when “‘in” Weight of weight Attraction of earth on weight But the increase in weight is ee mgms., since the distance be- tween the notches is 6°654 millims., and the half beam 202°716 millims, The weight of the weight is 453-92 grammes. The attraction of the mass in centimetres Volume x density . distance between centres of mass and weight 7)” _ Weight in grammes =e 154220: 6 aa? .y: The attraction of the earth is A xorR | 1+M—3(M—e) \ cos? where A=mean density of the earth, R=earth’s polar radius in centimetres, I __centrifugal force at the equator Equatorial gravity e=ellipticity. \= latitude. The logarithm of the coefficient of A when R is in inches is 9°0209985 (‘‘ Astronomical Soc. Mem.,” xiv, p. 118), or if R is in centimetres it is 9°4258322. 16 Mr. J. H. Poynting on a method of [Nov. 21, Inserting these values in equation A we obtain 154220°6 oo d2 453290 ~ 4 5 0 6654 “7R 4 1+M—{-M— re ay os ee a { ine 9 COO rere A= Cx ne 15220°6 x 453290 x 202716 arR( 1 +M—Sif=¢)oos" Vx fx 6654 where C= and log C=1°8951337, log ASO 33/5 SOs i, —log n, —2 log d. The following table is an account of an experiment made on May 80th, 1878, and will serve as aspecimen of the method of making the observa- tions. It is the best which I have yet made in the closeness with which all the values of agree with each other. VII.—May 30, 1878.—Determination of r. Mean of pre- Rider on Extremities of Resting ceding and _ Of r differences beam. oscillations. point. sueceeding i resting points. L 205 ‘0 2u9 °22 256 °74 AT *52 R 246 -7 257 07 210°31 47°36 L 209 -2 211 °40 257 °62 46°22 . R 263°8 257 °57 212 °23 45°34 L 220 °7 213 °07 Mean r=46'61. 1878.] Determination of vn. Extremities of oscillations. Position of mass. Resting point.. 212 °22 32 213° Mean of pre- ceding and succeeding resting points. mean! 7120. VOL. XXVIII. using the Balance with great delicacy, &c. 17 Differences =n. 18 Mr. J. H. Poynting on a method of [Nov. 21, At the close of the experiment d was found to be 22'216 centimetres. We have therefore— log A=log C. + log 46°61. —log 1-26. —2 log 22°16. =F S9oloaue +1-6684791: —0°1003705. — 2°6937226. == 000i po. A —orSo2e I have made in all 11 experiments with this method. The resulting vaiues of A are— dha, Reena May 20) een ere move Din eae eg: a DS eae 5°570 Oa 5 Are eae Ar 415 As Meee i MOG ae uae TAY? a et 3 Ol aire aes 5109 Occ nO No ae 6°075 Tes cS (ea ds ae 5882 Bh se ace aaiah ee ee 6°336 Ot so veeercer: Me 25) ea eee 5:977 INO Genin Mere, ae 5°580 | Be ee ee sar ihe AO irecentweaweee 5°100 The resulting mean value of the mean density of the earth is 5°69. If the eleven determinations be supposed to have equal weight, the probable error of their value is 0°15. The various determinations differ very much among themselves, but they seem to me sufficiently close to justify the hope that with a large balance and a large weight, which will not be so easily affected by air currents, and with greater precautions to prevent those air currents, a good determination of the mean density of the earth may ultimately be obtained by this method. 1878. | using the Balance with great delicacy, &c. 19 I.—June 12.—Determination of Value of 1 Scale Division. é iti f wodeeon Hxtremities o the beam. oscillations. L 312°0 297 R 275-0 267° L 298-7 292° R 260-6 266 ° three successive | Resting point. 62 On “90 Means of pre- ceding and successive resting points. 297 -18 294 °81 266 °'79 Differences, z.e., deflec- tion due to °3282 mgm. Mean R—L=27:08 divisions. 0°3282 Pe le division === — 27°08 0°01212 milli gramme. ee 20 Mr, J. H. Poynting on a method of | Nov. 21, Determination of (B+X)—(A+Y). Means of pre- Weight on | Extremities of Resting point. ceding and Diteeeees pan. oscillations. succeeding resting points. 254 °5 A+Y 272-9 264 °4.0 257 °3 | 267-5 | B+X 249 °8 257 97 263 °27 5°30 264-8 258 °5 A+Y 265 °4 262 °15 257 ‘04 5°11 259 °3 259 °3 B+X 253 °6 256 12 261 ‘87 5°75 258 °0 2535 A+Y 268 °5 261 ‘60 255 ‘63 5 97 255 °9 2446 | B+xX 264°5 255 ‘15 261 87 6°72 24:7 -O 273 6 A+Y 252 °0 26215 255 °85 6°30 271-0 252 °7 B+xX 260 256 °55 262 °90 6 37 253 °5 275 Mean A+Y 253 °7 263 °70 . difference 272, °4 5°93 .(B+X)—(A4+ Y)='01212 x 593. ='0718 milligramme. Greatest deviation from the mean— ='82 division. =°0099 milligramme. The weather during this series of weighings was very unfavourable, with frequent heavy showers. 1878. ] using the Balance with great delicacy, Sc. 21 I1.—June 19 —Deteaninaiien of 1 Scale Division. Means of pre- Rider on Extremities of Resting ceding and Differences beam. oscillations. point. succeeding due to R—L. resting points. 302 °8 This is rejected as it is so L 299 -9 301 °37 much lower than the suc- 302 °9 ceeding. 321°8 R 335 330 ‘00 326 8 299 °6 L 308 °7 304 °50 330 68 26°18 301 ‘0 322 °9 R 337 °5 331 °37 305-10 26°27 327 °6 299 °5 L 310 ‘9 305 70 331°77 26 ‘07 301 °5 325 °2 R 337°1 332 °17 305 90 26°27 329 °3 290 °4 L 319-4: 306 °10 295 *2 .°. mean R—L=26:20. .*. 1 division ='01252 milligramme. The weather was as unfavourable as on the previous day. The weights were changed shortly before the commencement of this series and the balance then worked so irregularly that for some 22 Mr. J. H. Poynting on a method of [Nov. 21, time I was unable to begin the rider determination. Hven then the first resting point had to be rejected. Determination of (A+X)—(B+Y). Means of pre- Weight Extremities of Resting ceding and in pan. oscillations. point. succeeding resting points. Differences. A+X 307 °8 301 °27 295 ‘8 These are all rejected, as the ~ SS —— motion was so irregular. 309 °6 The weights had been B+¥Y 322 °3 316°70 > changed a short time be- 312°6 fore, and had probably not reached an uniform tem- 295 °5 perature. A+X 309 °6 303 °17 B+Y 322 °7 314 °4 A+X 300-1 297 30 309 95 12°65 Mean (A+ X)—(B+Y)=12°86 divisions. . (A+X)—(B+Y)=0°1610 milligramme. Greatest deviation from mean =0°54 division=0°0067 milligramme. 1878.] using the Balance with great delicacy, ke. es IU1.—June 13.—Determination of 1 Scale Division. Mean of pre- ceding and Differences succeeding due to R—L. resting points. Rider on Extremities of beam. oscillations. Resting point. "92 bo Or 313°7 L 328 °7 322 °30 296 38 R 300 4: 297 °22 322 °47 L 331°6 322 65 297 88 bo Or =) bo ho Or bo Ou L 335 '8 324 °50 298 62 Mean R—L=25°37 divisions. aia division= == = 01293. OF ol 2 | 4 Mr. J. H. Poynting on a method of [Nov. 21, Determination of (A+X)—(B+Y). Mean of pre- Weight in | Extremities of Resting point. ceding and Differences pan. oscillations. succeeding resting points. oo SSN EE ee Oe 303 °3 Bap OG 294.°5 298 52 301 °8 303 °6 B+Y 315 °8 310 °35 297 ‘07 13°28 306 °2 288 °9 A+ X 301°5 295 °62 290 °6 300 °2 This is evidently due to some B+Y 311°6 306 °47 irregular and short disturb- 302 °5 ing cause, and is rejected. Mean (A+ X)—(B+Y)=13'40 divisions. . (A+X)—(B+Y)=0°1732 milligramme. Greatest deviation trom mean ='44 division ='0057 milligramme. 1878.] using the Balance with great delicacy, &c. 29 IV .-—June 14.—Determination of 1 Value of Scale Division. Rider on Extremities of beam. oscillations. Resting point. L 273 7 281 °75 R 266 °7 255 °22 L 289 °7 282 °17 R 253 °9 256 *57 L | 280 ‘0 283 °17 Mean of pre- ceding and succeeding resting points. Differences due to R—L. This was taken soon after en- tering the room. It is so much lower than the suc- ceeding that it is rejected. 281 ‘96 255 *89 282 °67 Mean R—L=26'37 division. 3282 1 division ee 26°37 01244, 26 74 26-28 26°10 Being interrupted, [ could not continue the series of rider determi- nations further. 26 Weight in pan. B+X Mr. J. H. Poynting on a method of Determination of (B+ X)—(A+Y). Extremities of oscillations. 29nd 275 289 °5 bo bo ple) ~I ~J No) 6G) @2) 0 . . me OUD HE bo OL bo ~I OURO D | Tb Co On bo We) Resting point. € ‘80 25 ‘90 ‘07 90 287° 67 Mean of pre- ceding and succeeding resting points. 283 °90 289 °28 [Nov. 21, Differences. 11°83 Mean (B+ X)—(A+Y)=12°06 divisions. ~. (B+X) —-(A+Y)=0°1500 milligramme. Greatest deviation from the mean =1°8 division =0°01224 mom. The previous determination of (B+X)—(A+Y) was ‘0718 mgm. The difference is too great, ‘(0782 mgm., to be accounted for by errors of experiment. weights, either of dust or moisture. There must have been some deposit on one of the I therefore took them ont; cleaned and adjusted them by scraping B till nearly equal to A, and removing the wax from A. 1878.] using the Balance with great delicacy, §¢. 2a V.—June 14.—Determination of Value of 1 Scale Division. Rider on beam. Extremities of oscillations, 221 bo bo bo Resting point. Si Mean of pre- bo bo e ceding and __| Differences due succeeding to R—L. resting points. 222 °16 24°96 246 *67 24°32 221 87 24°35 245 °98 24°58 221 -26 24-49 .°. mean R—L=24'54 divisions. .. 1 division= 0°3282 24:54: 0:01337 milligramme. 28 Mr. J. H. Poynting on a method of [Nov. 21, Determination of (B+ Y)—(A+X). Mean of pre- ceding and succeeding resting points. Weight in | Extremities of ra Differences. pan. oscillations. Resting point. Asx ee 7 209 62 This was rejected as being so 206 3 - much higher than the rest. B+Y 206 *4: 207 °6 A+X 204-0 207 *92 207 “71 Pal B+Y 208 °8 207 °82 207 °88 06 A+X 204: *4 207 °85 207 64 “21 B+yY 206 °1 207 47 207 *86 *39 A+X 205 °5 207 ‘87 207 °11 “76 B+Y 205 °3 206 °75 207 °83 “78 A+X 205°1 207 °20 206 °45 “75 B+Y 208 °7 206-15 —s*| Mean (B+ Y)—(A+X)='49 division =0°00655 miligramme. Greatest deviation from mean ='43 division =0°'00575 mgm. A and B had here been cleaned and B readjusted by scraping. A small vessel containing calcium chloride was put inside the balance to dry the air. This improved the action of the clamp, diminishing the cohesion. , 1878. | using the Balunce with great delicacy, §c. 29 Vi—June 17.—Determination of Value of 1 Scale Division. Mean of pre- ceding and _ | Differences due succeeding to R—L. resting points. Rider on Extremities of beam. oscillations. Resting point. R 214 °3 212 °42 L 233°3 235-77 212 °93 22 *84. R ZO 213 °45 236 °17 22°72 L 228 °1 236 °57 213 °38 23°19 R 219 °4 213 °75 Mean R—L=23°02 divisions. Pr itcigicign == ='01425 milligramme. 23°02 30 Weight in pan. Mr. J. H. Poynting on a method of Determination of (B+ X)—(A+Y). Extremities of Oscillations. B+xX Resting point. 215 °67 244 °55 216 °50 245 °25 217 °65 245 °72 245 °65 216 °57 Mean of pre- ceding and succeeding resting points. 216°08 244 °90 217 °37 245 68 [ Nov. 21, Differences. 28°47 27°83 28 °35 28 ‘58 28 *82 .. mean (B+X) —(A-++Y)=28°38 divisions =0°4043 milligramme. Greatest deviation from mean ='55 division ='00784 milligramme. + 1878. | using the Balance with great delicacy, Sc. ViIlI.—June 18.—Determination of 1 Scale Division. Rider on Extremities of beam. oscillations. R 173-2 178° —————— ee, eee, EEE Eee 6 Rh 190°7 181° 2 Resting point. Or bo ~T Mean of pre- ceding and succeeding resting points. 180 °47 217 54 216 °17 Mean R—L=37°'71 divisions. ‘. 1 scale division = "3282 37¢1 ='00870 miligramme. 38 ‘02 37°73 ol Differences due to R—L. 32 Mr. J. H. Poynting on a method of [Nov-21, Determination of (B+Y)—(A+X). Mean of pre- ceding and succeeding resting points. Weight in | Extremities of pan. oscillations. Differences. Resting point. 208 °5 B+Y 221°7 215 °35 209 *5 216 °32 13°73 ————————————————— a eee eS —— eee ee —_=——=—=—=_—_—S== ee eS eee eee 9-0 A+X 243-0 23180 2-2 8°3 This sudden change of resting B+Y 229-0 219 05 point must be due to some 9°9 irregular disturbance. It is therefore rejected. it was slowly returning to nearly its former values. Mean (B+ X)—(A+Y)=14°75 divisions ='12831 milligramme. Greatest deviation from the mean =1-02 division ='0089 mgm. The great difference between the result here and that in series V is probably due to deposit of dust. The new mirrors had to be fixed up just before the experiment began, and the doors were open for some time. At the conclusion of the weighing I found a good deal of dust on the weights, 1878. | using the Balance with great delicacy, Sc. oo VI1II.—June 19.—Determination of 1 Scale Division. Mean of pre- Rider on | Extremities of . . ceding and Difference beam. oscillations. Wlre pont: succeeding due to R—L. resting points. This is so much higher than 235 8 the rest, probably through L 222 °3 228 42 being observed soon after I 233 °3 entered the room, that it is rejected. 197 R 181 °2 188 °32 193 °9 228 °2 L 222°7 225 40 188 *24 37°16 228 ‘0 197 °4 | R 180°7 188 ‘17 225 *46 37°29 193 ‘9 233 °6 L 218 ‘0 225 °52 187 63 37 °89 232 °5 | OTT R 183 3 187-10 225 °28 38 18 190°] 230 °2 L 220°3 225 °05 187 °35 37 ‘70 229 *4 193 °8 R 182 °5 187 °60 191 °8 Mean R—L=37'64 divisions. 8282 _ 99879, 3764 1 scale division= VOL, XXVIII. | D a4 Weight in pan. A+Y B+X A+Y B+X A+Y B+xX Mr. J. H. Poynting on a method, &c. Determination of (B+ X)—(A+Y). Extremities of oscillations. Resting point. 241 °72 188 95 235 *60 187 °55 234 °85 187 -4: 234°57 234 °45 Mean of pre- ceding and succeeding resting points. [Nov. 21, Differences. In one observation not re- corded just before this the clamp had been loose, and the scale pan had slipped, and the resting point was thereby changed. The dis- turbance had apparently not subsided when this was taken, it is therefore re- jected. 188 °22 235 °22 187 ‘47 234 °71 187 °50 47°38 47°67 47 38 Mean (B+ X)—(A+Y) =47°24 divisions =0°4119 miligramme. Greatest deviation from the mean =°'43 division — ‘00375 mem. Poynting. 2 PLAET'S Ns AD DATALUS SUMMA VTL ESALE SAAT LEEDS ANGEL senses SUUTTSPLIUAAAEN ADEA THAN EDU EAA UHHH : 7 > hs a ~~ “uP A) See “eh iy ae Feet aS - > ~< ee MA att me dee Sr apes eae eT ERS * - a _ i ie an bs Se se > ’ Ab . . 0 : os aa = a £5 s 2 id a ve - 3 a oe By har A jZS ; or ek gee ae Ayate? . iy sibs F i ‘ é ne 3 eo j > 2 - : Ag : * z = = = ¥ bid 1878. ] On Repulsion resulting from Radiation. 35 Summary. Greatest deviation Series. Mems. from mean in milligrammes. PB Oe AY) = 0718 ed are 7 ec y=. 1610. 0067f. a (A+X)—(B+Y) = 17382 ee, oe ; be Meteo i+ y) = i500, dlgef “> Ne mam 5 (B+Y)—(A+X) = :0065 ae Re e Mga (k+¥) = -404a «ores PEt A9P? mem. eB PY)—(A+X) = 1288 -0089] ,_,.. 8 (B+X)-(A+Y) = “4119 - 0037 f B=A+1418 mem. The greatest error—that is the greatest deviation of any one value from the mean of its series—in the first four series is s55q5p5 qth of a pound. The greatest error in the four series Nos. 5—8 is of a pound, sooo oooOUL II. “On Repulsion resulting from Radiation.” Part VI. By WILLIAM CROOKES, F.R.S., V.P.C.S. (Abstract. ) In this part, with which the research closes, the author first examines the action of thin mica screens fixed on the fly of an ordinary radio- meter, in modifying the movements. It is found that when a disk of thin clear mica is attached 1 millim. in front of the blacked side of the vanes of an ordinary radiometer, the fly moves negatively, the black side approaching instead of retreating from the light. When a thin mica disk is fixed on each side of the vanes of a radiometer, the result is an almost total loss of sensitiveness. In order to examine the action of screens still further an instru- ment is described having the screens movable, and working on a pivot independent of the one carrying the fly, so that the screens can move freely and come close either to the black or to the white surfaces of the disks. By gentle tapping the screens can be brought within 2 millims. of the black surfaces. A candle is now brought near, shaded so that the ight has to pass through one of the clear disks and fall on the black surface. The black side immediately retreats, the clear disk remaining stationary for a moment and then approaching the light. If the candle is allowed to shine on the plain side of the black disk, no immediate movement takes place. Very soon, however, both disks move in the same direction away from the candle, the speed of the ular disk gradually increasing over that of the blacked disk. p 2 36 Mr. W. Crookes on [Nov. 21, Instead of allowing the clear screens to freely move on a pivot, an instrument was made in which the screens could be fixed beforehand in any desired position in respect to the blacked disks. It was then found that with the screens close to the blacked sides of the vanes the fly rotates very slowly in the negative direction, stopping altogether when the candle is moved five or six inches off. With the screens | millim. from the black surface the direction is negative and the speed at its maximum. When the screens and disks are 7 millims. apart a position of neutrality is attained, no movement taking place. When the distance is further increased, positive rota- tion commences, which gets stronger as the screens approach the bright sides of the disks, where the positive rotation is at its maxi- mum. ‘The author adduces reasons for considering that the negative rotations here observed are caused by the warming up of the black surface by radiation falling direct on it, through the clear mica screen, and the deflection backwards of the lines of molecular pressure thereby generated. The action of these radiometers being complicated, owing to the surfaces of the vanes being different in absorptive power, another in- strument was made in which the vanes were of polished aluminium, perfectly flat and symmetrical with the bulb. The screens were of clear mica movable in respect to the vanes, and at right angles to their surface. When exposed to the light of a candle it was found that with the screens brought up close to the disks, the rotation was as if the unscreened side were repelled ; at an intermediate posi- tion there was neutrality. Explanations are given of these move- ments, but without the illustrative cuts they would be unintelligible. — Experiments on radiometers having movable screens interposed be- tween the vanes and the bulb are next given, and these are followed by a long series of experiments on the influence of movable screens on radiometers with cup-shaped metallic vanes, the screens being varied in shape, and position in respect to the plane of rotation, as well as in respect to the distance from the vanes. A similar series is given with metallic cylinders as vanes, and from the behaviour of the latter kind of radiometer, an explanation is given of the various movements previously obtained. It is found that when the screen touches the convex surface of the vanes the rotation under the influence of light is always positive. It commences at a low exhaustion, increases in speed till the rarefaction is so high that an ordinary radiometer would begin to lose sensitiveness, and afterwards remains at about the same speed up to the highest rarefaction yet obtained. At any rarefaction after 87 M (millionths of an atmo- sphere) there is a neutral position for the screen. When it is an the concave side of this neutral position the direction of rotation is positive, and when on the convex side of the neutral position it is 1878. | Repulsion resulting from Radiation. ov negative; the speed of rotation is greater as the vanes are further removed from this neutral position on either side. The position of this neutral point varies with the degree of exhaustion; thus at 12 M, the screens must be 3 millims. from the convex side; at ‘18 M they must be 13 millims. from the convex side. The higher the exhaustion the greater the distance which must separate the convex side of the hemi-cylinders and the screens. The author gives explanations of these phenomena, based on the following already ascertained facts:—When thin aluminium vanes are exposed to light the metal rises in temperature and becomes equally warm throughout, and a layer of molecular pressure is generated on its surface. The thickness of this layer of pressure, or the length of the lines of force of repulsion, varies with the degree of exhaustion, being longer as the exhaustion increases. The lines of force appear to radiate from the metal in a direction normal to its surface. The force of repulsion is also greater the closer the repelled body is to the generating or driving surface, and the force diminishes rapidly as the distance increases, according to a law which does not appear to be that of “‘inverse squares.” Diagrams are given illustrating the author’s explanation, based on the above data. _An apparatus is next described not differing in principle from the last, but having, in addition to the aluminium hemi-cylinder and movable mica screen, a small rotating fly made of clear mica, mounted in such a way that it could be fixed by means of an exterior magnet in any desired position inside the bulb. The screen was also capable of adjustment by means of another magnet; the aluminium hemi- cylinder in this apparatus being fixed immovable. The adjustible indicator being very small in diameter in comparison to the other parts of the apparatus, and, being easily placed in any part of the bulb, was expected to afford information as to the intensity and direction of the lines of pressure when a candle was brought near the bulb. Experiments have been tried, a, with the screen in different positions in respect to the hemi-cylinder; 0, with the indicator in different parts of the bulb; c, with the candle at different distances from the hemi-cylinder on one side or the other; d, with the degree of exhaustion varying between wide limits. It would be impossible to give an intelligible abstract of the results obtained with this apparatus without numerous diagrams. It may, however, be briefly stated that they entirely corroborate the theories formed from a study of the behaviour of the instruments previously described. The next part of the paper treats of the action of heat employed inside the radiometer. In a previous paper, the author showed that phenomena feeble and contradictory when caused by radiation external to the bulb, became vigorous and uniform when the radiation was applied internally by the agency of an electrically-heated wire. It 38 Mr. W. Crookes on [Nov. 21, was hoped that some of the more obscure phenomena shown by the deep cups with movable screens in front (referred to above) might be intensified if set in action by a hot wire. Several kinds of apparatus and experiments with them are described, but the results are too com- plicated to be given in abstract. One experiment proves that the direction of pressure is not wholly normal to the surface on which it is generated, but that some of it is tangential. The author then describes the turbine radiometer, early specimens of which were exhibited before the Royal Society on April 5, 1876. In the ordinary form of radiometer the number of disks constituting the fly is limited to six or eight, a greater number causing interference one with the other and obstruction of the incident light. In the turbine form of fly there is no such difficulty, the number of vanes may be considerably increased without overcrowding, and with corre- sponding advantage. In the earlier turbine radiometers the flies were made of mica blacked on both sides, and inclined at an angle like the sails of a windmill, instead of being in a vertical plane. This form of instrument is not sensitive to horizontal radiation, but moves readily in one or other direction to a candle held above or below. A vertical light falling on the fly gives the strongest action, but rotation takes place, whatever be the incident angle, provided the light is caught by one surface more than by the other. Hther dropped on the top of the bulb to chill it causes rapid negative rotation. If the turbine radio- meter is floated in a vessel of ice-cold water, and the upper portion exposed to the air of a warm room, it rotates rapidly in the positive direction, acting as a heat engine, and continuing so to act until the rotating fly has equalised the temperature of the upper and lower portions of the bulb. By reversing the circle of operations—by floating the turbine radiometer in hot water and cooling the upper portion of the bulb—the fly instantly rotates in the negative direction. After describing experiments in which the same fly was made to rotate first in a large bulb and then in a small one at the same degree of exhaustion, the author proceeds to discuss the influence exerted by the inner side of the glass case of the radiometer as a reacting surface. A flat metal band was put equatorially inside a radiometer, and lamp- blacked, so that the molecular pressure generated under the influence of light should react between the fly and the black band, instead of between the fly and the glass side of the bulb. It was found that the maximum speed with the band present was 40 revolutions a minute, against 84 revolutions when the band was absent. The rotation of the case of a radiometer, the fly being held immovable by magnetism, is next described. A preliminary note on this subject having already appeared in the ‘“‘ Proceedings,” * it need not be again * “Proc. Roy. Soc.,”’ No. 168, March 30, 1876. 1878. ] Repulsion resulting from Radiation. 39 described in detail. Many different forms of instrument for effecting this rotation are described, and their mode of action explained. The reacting inner surface of the envelope being thus proved to be essential to the rotation of the fly, other instruments were made in which this necessary reaction is obtained in a more direct manner. In one, the radiometer is furnished with a fly carrying four flat aluminium vanes, polished on both sides. Three vertical partitions of thin clear mica are fixed in the bulb, with their planes not passing through the axis of rotation, but inclined to it, thus throwing the obliquity off the fly on to the case, and giving three fixed planes for the reaction to take place against. Candles arranged symmetrically round the bulb make the fly rotate rapidly against the edges of the inclined planes. Breathing gently on the bulb gives negative rotation. A hot glass shade inverted over the instrument causes strong negative rotation, changing to positive on cooling. When the fly is furnished with clear mica or with silver flake mica vanes, the same results are obtained as when aluminium vanes are employed. The principal action is produced by dark heat warming the bulb, screens, and vanes. The otheoscope is the next subject treated on in the paper. This has already been given in abstract,* and need not be again referred to. Many different varieties of otheoscope are figured and described. "ie. 1. * “ Proc. Roy. Soc.,” No. 180, April 26, 1877. 40 Mr. W. Crookes on : [Nov. 21, It was suggested by Professor Stokes that a disk might be made to revolve on its axis, and the author describes an instrument in which this suggestion is carried out. The disk is horizontal, mounted like the fly of a radiometer, and for lightness’ sake is of mica, blacked above. Fixed to the bulb above the disk are four flat pieces of clear mica; each extends from the side of the bulb to near the centre, and ends below in a straight horizontal edge, leaving just space enough for the disk to revolve without risk of scraping. The edge is in a radial direction, and the plane of the plates is inclined about 45° to the horizon, in the same direction for them all. Exposed to the light of a candle, the rotation is against the edge. By slightly modifying this form, the instrament becomes much more sensitive. Fig. 1 shows the complete instrument; a, a, are six vanes of copper foil, oxidised by heating to redness in the air; they are attached to arms, and are inclined at an angle of 45° to the horizon. They are firmly fixed to the support. Through the centre passes a needle-point, on which is balanced a glass cup, carrying a thin clear disk of mica, }, b, freely rotating about 1 millim. above the top edges of the copper vanes. When exposed to light, the mica disk rotates with great speed against the edges. The pressure which drives the movable fly round reacts equally on the driving surface: by suspending both vanes and disk independently on needle-points the effect of light causes them to rotate in opposite directions. Whilst experimenting with the otheoscope it was found that, for a given exhaustion, the nearer the reacting surfaces were together the greater was the speed obtained. In the “ Proceedings of the Royal Society ” for November, 1876,* the author described an apparatus by which he was able to measure the thickness of the layer of molecular pressure generated when radiation impinged on a blackened surface enclosed in an atmosphere the rarefaction of which could be varied at will. It was found that in this apparatus repulsion could be obtained at ordinary atmospheric pressures. Observations are given at normal pressure and at various degrees of rarefaction, with the driving and moving surfaces separated 1, 2, 3, 4, 6, 8, and 12 millims.; and dia- grams of the resulting curves are shown when the atmospheric tension and the force of repulsion are used as abscisse and ordinates. The tables and curves show that the law of increase of the force with the diminution of the distance between the disks does not remain uniform at all rarefactions. At the lowest exhaustions the mean path of the molecules of the attenuated gas is less than | millim., as rendered evident by the force of repulsion diminishing rapidly as the distance increases. At exhaustions higher than 9 millims. this condition alters, and as the * “ Proc. Roy. Soc.,”’ No. 175, vol. xxv, p. 310. 1878. | Repulsion resulting from Radiation. Al gauge approaches barometric height, the molecular pressure tends to become uniform through considerable distances, the mean path of the molecules now being comparable with the greatest distance separating the surfaces between which they act. A similar apparatus to the one in which the last experiments were tried was used to measure the action at pressures at and approaching atmospheric. At pressures between atmospheric and 210 millims., the first action is very faint repulsion, immediately followed by strong attraction. The attraction then begins to decline, until at 15 millims. pressure it disappears. At the same time the repulsion, which begins to be apparent at 250 millims., increases as the attraction diminishes. The author considers that the attraction is the result of air-currents, caused by the permanent heating of the surface in front of the move- able disk. The paper concludes with experiments undertaken to measure the amount of repulsion, using a horizontal torsion balance,* on the prin- ciple of Ritchie’s, in which the force of repulsion is balanced by the torsion of a fine glass fibre. The pan of the balance is a clear mica disk, and a similar disk is fastened to the tube in which the beam oscillates. This fixed disk is lampblacked on the upper side, and beneath is a spiral of platinum wire, connected with terminals sealed through the side of the tube. When the spiral is ignited by a constant electric current, the blacked mica disk fixed above it becomes heated, and the molecular pressure thereby generated between it and the mica pan causes the latter to rise. The glass thread attached to the beam is thus twisted, and by means of a graduated circle the number of degrees through which the thread has to be turned in order to bring the beam back to equilibrium is noted. This gives a measurement of the pressure exerted, in torsional degrees, and these are converted into grains by ascertaining how many torsional degrees correspond to a known weight. A ray of light reflected from a mirror in the centre of the beam is used as an index, being brought back to zero at each experiment. The author gives in a table, and also shows in the form of a curve, the results ob- tained with this apparatus, giving the force of molecular pressure in grains weight at exhaustions varying between 2,237 and 0°7 millionths ot an atmosphere. * For a description of this form of torsion balance, see the author’s paper, “ Phil. Trans.,” 1876, vol. clxvi, p. 371. 42 Anniversary Meeting. [ Noy. 30, November 30, 1878. ANNIVERSARY MEETING. Sir JOSEPH HOOKER, C.B., K.C.S.I., President, in the Chair. General Boileau, for the Auditors of the Treasurer’s Accounts on the part of the Society, reported that the total ordinary receipts during the past year, including a balance of £933 11s. 1d. carried from the preceding year, amount to £5,924 5s. 9d., and that the total ordinary expenditure in the same period amounts to £5,008 Is. 2d., leaving a balance at the Bankers of £894 2s. 3d., and £22 2s. 4d. 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. On the Home List. Admiral Sir George Back, D.C.L. Edward Blackett Beaumont. Rev. James Booth, LL.D. Lieut.-General John Cameron, lash Deal Opies Frederick, Lord Chelmsford, DiCan Rey. William B. Clarke, M.A. Thomas Grubb, M.R.1.A. Right Hon. Russell Gurney, Q.C. Rear-Admiral Sir William Hutcheon Hall, K.C.B. Prof. Robert Harkness, F.G.S. John Hilton, F.R.C.S. Cuthbert William Johnson. Rev. Robert Main, M.A. Colonel Thomas George Mont- gomerie, R.E. Thomas Oldham, M.A., LL.D. John Penn. John, Earl Russell, K.G. Very Rev. Augustus Page Saun- ders, D.D., Dean of Peter- borough. William Stokes, M.D., D.C.L. Thomas Thomson, M.D. Major-General Sir Andrew Scott Waugh, R.E. On the Foreign List. Antoine César Becquerel. Claude Bernard. Khas Magnus Fries. Henri Victor Regnault. Angelo Secchi. Ernst Heinrich Weber. 1878. | President's Address. Ao Fellows elected since the last Anniversary. John Gilbert Baker, F.L.S. John Hopkinson, M.A., D.Sc. Francis Maitland Balfour, M.A. John Hughlings Jackson, M.D. Rey. Thomas George Bonney, M.A. | Lord Lindsay, P.R.A.S. Prof. James Henry Cotterill, M.A. | Samuel Roberts, M.A. Sir Walter Hlliot; K.C.S.I. Edward A. Schafer, M.R.C.S. Rev. Canon W. Greenwell, M.A. | Right Hon. Wiliam Henry Smith. Right Hon. Sir William Henry | Hermann Sprengel, Ph.D. Gregory, K.C.M.G. George James Symons. Thomas Hawksley, C.E. Charles S. Tomes, M.A. On the Foreign List. Marcellin Berthelot. Adolph Wilkelm Hermann Kolbe. Joseph Decaisne. Rudolph Leuckart. Emil Du Bois Reymond. Simon Newcomb. Pafnutij Tchebitchef. The President then addressed the Society as follows :— GENTLEMEN, Art the conclusion of this, the fifth and last year during which I shall have held the most honorable office of your President, I have the eratifying assurance that the communications made to the Society and its publications have in no respect fallen off in scientific interest and value. We have not, indeed, been called upon to undertake during the past year such responsible and time-absorbing duties in behalf of the Government as the Polar, Circumnavigation, Transit of Venus, and other Committees demanded of us during the previous four years; but some of the results already achieved by those expeditions have been contributed to our publications, and we are in expectation of more. It is also with satisfaction that I can refer to the good attendance at our | evening meetings, soirées, and réunions as evidence of the interest taken in our proceedings by the Fellows generally and their friends. Before proceeding to touch upon some of the advances made in Science during the last few years, I have, as heretofore, to inform you of the Society’s condition and prospects, and of those duties under- taken by its Council, for information as to which non-resident Fellows look to the annual address. The loss by death of Fellows, twenty-one in number, is but little short of last year’s rate, while that of Foreign Fellows (six) is twice as great as last year. On the home list is Sir George Back, the last, with 44. Anniversary Meeting. [ Nov. 30, the exception of our former President, the venerable Sir H. Sabine, of that celebrated band of Arctic voyagers, which during the early part of the century added so much to our renown as navigators and discoverers. Sir George was further the companion of Franklin and Richardson in that overland journey to the American Polar Sea, in which human endur- ance was tried to the uttermost compatible with human existence, as is related by two of the party in that modest but thrilling narrative which will ever hold a unique place in the annals of geographical dis- covery. Of our Indian explorers four have been taken away, namely, Major-General Sir Andrew Waugh, for many years Director of the Great Trigonometrical Survey of India; and shortly afterwards his friend, Col. Montgomerie; Dr. Oldham, for a quarter of a century the Director of the Geological Society of India; and Dr. Thomas Thomson, my fellow-traveller in the Himalaya, whose report of ex- plorations in Western Tibet contains the first connected account of the physical and natural features of that remote and difficult country. Lieut.-General Cameron survived but for one year our late Fellow, Sir Henry James, his predecessor in the Direction of the Ordnance Survey of Great Britain. In the Rev. James Booth we have lost a mathematician of high attainments. The Rev. W. B. Clarke, of New South Wales, was the author of many papers on the Meteorology and Geology of the Cape of Good Hope, Australia, and the Pacific. The Rev. R. Main, Director of the Radcliffe Observatory, was for nearly half a century an indefatigable observer. Lastly, Harl Russell, the distinguished statesman, and the earnest advocate, whether in the Government or in Parliament, of every measure for the promotion of scientific inquiry. He it was who, when Prime Minister in 1849, wrote to the then Harl of Rosse, President of the Society, offering to place £1,000 (now known as the Government Grant) on the annual votes of Parliament, if the Council would undertake to apportion that sum among scientific workers requiring aid in their researches. Of Foreign Fellows our losses are a great Chemist in Becquerel, of Paris, whose election took place upwards of forty years ago; a great Physiologist in Claude Bernard, also of Paris; the father of Mycology, and for long the patriarch of Scandinavian Botanists, Elias Fries ; a most distinguished Physicist and the recipient of both a Rumford and Copley medal in Regnault; a veteran Anatomist in Weber; and in Secchi, of Rome, an Astronomer of astonishing activity, the author of more than three hundred separate contributions to the science of which he was so great an ornament. In matters of Finance I may with satisfaction refer you to our Treasurer’s Balance Sheets. It will be in your recollection that Mr. T. J. Phillips Jodrell placed in 1874 a sum of £6,000 at the disposal of the Society, with the view 1878. | President's Address. A5 of its being devoted to the encouragement of Scientific Research by periodical grants to investigators whom your Council might think it expedient thus to aid. Shortly after the receipt of this munificent sift, the Government announced its intention of devoting annually for five years £4,000 to the same object, thus anticipating the special purpose which Mr. Jodrell had in view. Thereupon, with his consent, the donation was temporarily funded and the proceeds applied to the general purposes of the Society until some other scheme for its appropriation should be approved. In April last I received a further communication from Mr. Jodrell, declaring it to be his wish and intention that, subject to any appropriation of the sum which we might, with the approval of the Society, make during his lifetime, it should immediately on his death be incorporated with the Donation Fund, the annual income in the meantime going to the general revenue of the Society. Upon this subject I have now to state that since the receipt of that letter Mr. Jodrell has approved of £1,000 of the sum being contributed to a fund presently to be mentioned. I have also to inform you of a cheque for £1,000 having been placed in my hands by our Fellow, Mr. James Young, of Kelly, to be expended in the interests of the Society in such manner as I should approve. , , Mr. De La Rue, to whose beautiful experiments I shall have occasion to refer, has presented to the Society both the letterpress and the exquisitely engraved fac-similes of the electric discharges described in his and Dr. Hugo Miller’s paper, recently published in our “ Transactions.” Our Fellow, Dr. Bigsby, has presented seven copies of his ‘‘ Thesaurus Devonico-carboniferus”’ for distribution, and they have been distributed accordingly. A very valuable addition to our Gallery of deceased Fellows has been the gift by Mr. Leonard Lyell of a copy in marble by Theed of the bust of his uncle the late Sir Charles Lyell, F.R.S., together with a pedestal. This is the best likeness of the late eminent geo- logist that has been executed, and is in every respect a satisfactory one. Thave the gratification of announcing to you, that through the muni- ficence of asmall number of Fellows, means have been advanced for reducing the fees to which all ordinary Fellows in future elected will be liable. That these fees, though not higher than the most econo- mical expenditure on the part of the Society for its special purposes demanded, were higher than it was expedient to maintain if any possible means for reducing them could be obtained, -was not only my own opinion but that of many Fellows. They exceed those of any other scientific society in Hngland or abroad; their amount has 46 Anniversary Meeting. [ Nov. 30, occasionally prevented men of great merit from having their names brought forward as candidates, and they press heavily, especially upon those who, with limited incomes, have other scientific societies to sub- scribe to. Nor does it appear to me as otherwise than regrettable that so high an honour as Fellowship of the Royal Society, the only one of the kind in England that is limited as to the number annually elected, and selective in principle, should be attainable only at a heavy pecuniary expenditure. It is true that our Fellows receive annually in return publications of great value to Science generally; but these treat of so many branches of knowledge that it is but a fraction of each that can materially benefit the recipient, while their bulk entails an additional expenditure; and now that the individual papers published in the “Transactions ” are separately obtainable, the advan- tages of Fellowship are less than they were when to obtain a treatise on his own subject a specialist had either to join the Society, or to pur- chase a whole volume or a large part of it annually. It was not, however, till I had satisfied myself that the annual income of the Society, though not ample, was sufficient for its ordinary purposes, that its prospects in other points of view were good, and that the expenditure upon publication was the main, if not the sole, obstacle to a reduction of fees, that I consulted your Treasurer on the subject of taking steps to attain this object. My first idea was to create, by contributions of small amount, a fund the interest of which should be allowed to accumulate; and when the income of the accumulated capital reached a sufficient amount to enable the Society to take the step without loss of income, to reduce either the entrance fee or annual contribution; and to which fund Mr. Young’s gift should be regarded as the first donation. This proposal was in so far entertained by your Council that they resolved to establish a Publication Fund, and to place Mr. Young’s gift to the credit thereof; and further, appointed a Committee to consider and report upon the Statutes of the Society concerning the fees. The movement once set on foot met with an unexpectedly enthu- siastic reception, several Fellows with the best means of forming a judgment, not only approved of it, but offered liberal aid, urging that the reduction of fees should be the first and immediate object, and that if such a course were thought desirable, the means of carrying it out would surely be forthcoming. On this your Treasurer pre- pared for my consideration a plan for raising £10,000, the sum re- quired for effecting any material reduction ; and we resolved to ascer- tain by private inquiry whether so large an amount could be ob- tained. Here again our inquiries were responded to ina spirit of, I may say, unexampled liberality: in a few weeks upwards of £8,000 was given 1878.] President's Address. 47 or promised by twenty Fellows of the Society, and I need hardly add that the remaining £2,000 was contributed very shortly afterwards. At a subsequent meeting of the Council it was resolved :— 1.—That the sums referred to as the Publication Fund, as well as those received or that may be hereafter received, for the purpose of relieving future ordinary Fellows from the Entrance Fee, and for reducing their Annual Contribution, be formed into one fund. 2.—That the Hntrance Fee for ordinary Fellows be henceforth abolished; and that the Annual Contribution for ordinary Fellows hereafter elected be £3 (three pounds). Also, that the income of the Fund above-mentioned be applied, so far as is requisite, to make up the loss to the Society arising from these remissions and reductions. 3.—That the account of this Fund be kept separate; and that the annual surplus of income, after providing for the remission and reduction above recommended, be re-inyested, until the in- come from the Fund reaches £600. So soon as the annual income reaches this amount, any surplus of income in any year, after providing for the remission and reduction above-mentioned, shall be available, in the first instance, in aid of publication and for the promotion of research. A list of subscribers to this Fund will be placed in the hands of every Fellow, with the information that it will be kept open for future contributions, in the interests of research and of the Society’s publica- tions. I hope that it will be largely and speedily augmented, and that it may eventually reach an amount which will provide us with the means of accomplishing as much as is effected by the Government Fund, upon our own sole and undivided responsibility. I must not conclude my notice of this movement without a mention of those whose encouragement and liberality have most largely promoted it; and first of all, Mr. Spottiswoode, to whose counsel and active co-operation throughout, its success is mainly due; Messrs. Young’s and Jodrell’s contributions have already been mentioned, they have been supported by others :—£2,000 from Sir Joseph Whitworth, £1,000 from Sir W. Armstrong, and £500 each from His Grace the Duke of Devon- shire, Mr. De La Rue, Mr. Spottiswoode and Mr. Eyre (jointly), Dr. Siemens, and the Earl of Derby, and £250 from Dr. Gladstone. The balance comprises contributions by thirty-two Fellows. I have to mention your obligations to Dr. W. Farr for the labour he has bestowed in ascertaining those vital and other statistics of the Society, upon an accurate knowledge of which the calculations for the reduction of fees had to be based; and to Mr. Bramwell for construct- ing a table showing to what extent these changes will affect the 48 Anniversary Meeting. - [Nov. 30, Society’s present and future income. It may interest you to know that the contribution of ordinary Fellows in future to be elected, is but little over that which was required of all Fellows from the very commencement of the Society’s existence till 1823, namely, ls. per week, and that the last Fellows who paid that sum died in 1869. Looking back over the five years during which I have occupied this chair, I recognise advances in scientific discovery and research at home and abroad far greater than any previous semi-decade can show. I do not here allude to such inventions as the Telephone, Phonograph, and Microphone, wonderful as they are, and promising immediate results of great importance to the community; nor even to those outcomes of high attainments, the Harmonic Analyser of Sir W. Thomson, and the Bathometer and Gravitation Meter of Siemens; but to those discoveries and advances which appeal to the seeker of knowledge for its own sake, whether as developing principles, suggesting new fields of research, or awakening attention to hitherto unseen or unrecognised, or unexplained phenomena of nature, and of which the Radiometer and Otheoscope of Crookes are conspicuous examples. In the foremost rank as regards the magnitude of the undertakings and the combination of means to carry them out, nothing in the history of physical science can compare with the Transit of Venus Expeditions. To observe the Transit of Venus various nations of Hurope and the United States competed as to the completeness of the Expeditions they severally equipped. The value* of the solar parallax cannot be ascertained until the results of all the Expeditions are taken into account, when it will have an international claim to acceptance. But advances in this direction will not have ended here, the very difficul- ties attending the observation of the Transit of Venus, having directed attention to the method originally suggested by the Astronomer Royal in 1857, of obtaining the solar parallax from the diurnal parallax of Mars at its opposition. Mr. Gill by the skilful employment at Ascension Island of the heliometer lent by Lord Lindsay, has greatly increased the accuracy of the method by which the necessary star comparisons with Mars are made, and there is every reason to believe that the results of his observations which are now in course of reduction will be very satis- factory. Within the last two years a remarkable addition has been made to * The Astronomer Royal informs me that Captain Tupman, who has taken the principal share in the superintendence of the calculation, fixes provisionally on a mean parallax of 8”°8455, corresponding to a distance of 92,400,000 British miles, but that the observations would be fairly satisfied by any parallax between 8-82 and 8’88, which in distance produces a range of from 92,044,000 and 92,770,000 miles, differing by 726,000 miles, a quantity almost equal to the sun’s diameter. 1878.] President's Address. AQ the number of members of the solar system by Professor Asaph Hall’s discovery of the satellites of Mars; and more recently, Professor Watson has announced his detection of planetary bodies within the orbit of Mercury, during the Solar Hclipse which was visible in America. In 1876 Schmidt recorded an outburst of light in a star in Cygnus, which showed a continuous spectrum containing bright lines similar to those of the remarkable star of 1866. As the star waned the continuous spectrum and bright lines faded, all but one bright line in the green, giving the object the spectroscopic appearance of a small gaseous nebula. Great progress has been made during the last five years at Green- wich in the method of determining the motions of the heavenly bodies by the displacement of the lines in their spectra, as first successfully accomplished by Mr. Huggins in 1868. Not only do the results obtained by the stars observed at Greenwich agree with those of Mr. Huggins, as satisfactorily as can be expected in so delicate an investigation, but the motions of seventeen more have been determined ; while the trustworthiness of the method has been shown by the agreement of the values for the rotation of the sun and the motions of Venus, with the known movements of these bodies. Mr. Huggins has also obtained photographs of the spectra of some of the brighter stars, which give well defined lines in the violet and ultra- violet parts of the spectrum. These spectra have already shown alterations in the lines common to them and the sun, which are of much interest. In Solar Physics, which afford remarkable evidence of Mr. Lockyer’s energetic labours in this country and Mr. Janssen’s in France, I must mention our Foreign Member’s wonderful photographs of the sun, wherein the minutest of the constant changes in the granulations exhibited on its surface (and which vary in size from + of a second to 3 or 4 seconds) can be studied in future from hour to hour and day to day; as can also their different behaviour at different periods of the occurrence of sun-spots. Before dismissing this fruitful field of research, I must allude to Mr. Lockyer’s discovery of carbon in the sun; and to his announced but not yet published observations on the changes and modifications of spectra under different conditions, some of which he even regards as indicating the breaking up of the atoms of bodies hitherto re- garded as elementary. Some important investigations on the Electric Discharge have been communicated to the Society by Messrs. De La Rue and Miller, and by Mr. Spottiswoode. These, prosecuted by different means, tend to limit the possible causes of the stratification observed in discharges through vacuum tubes. They also point to the conclusion that this VOL. XXVIII. E 50 Anniversary Meeting. | Nov. 30, phenomenon is in a great measure due to motions among the mole- cules of the residual gas, which themselves become vehicles for the transmission of Electricity through the tube. It is well known that. gases at atmospheric pressure offer great resistance to the passage of Electricity ; and that this resistance diminishes (to a certain limit, different for different gases) with the pressure. And the researches in question appear to show that the discharge, manifestly disruptive at the higher pressures, is really also disruptive even at pressures when stratification takes place. The period of these discontinuous dis- charges has not yet been the subject of measurement, but it must, in any case, be extremely rapid. The remarkable experiments which have resulted in the liquefaction of the gases hitherto regarded as permanent will be noticed presently when I deliver to their authors the medals they so richly deserve. Under the auspices of the Elder Brethren of the Trinity House, and as their scientific adviser, Professor Tyndall has conducted an investigation on the acoustic properties of the atmosphere. The instruments employed included steam whistles, trumpets, steam syrens, and guns. ‘The propagation of sound through fog was proved to depend not upon the suspended aqueous particles, but upon the con- dition of the sustaining air. And as air of great homogeneity is the usual associate of fog, such a medium is often astonishingly transparent to sound. Hail, rain, snow, and ordinary misty weather, were also proved to offer no sensible obstruction to the passage of sound. Hvery phenomenon observed upon the large scale was afterwards repro- duced experimentally. Clouds, fumes, and artificial showers of rain, hail, and snow were proved quite ineffectual to stop the sound, so long as the air was homogeneous, while the introduction of a couple of burners into a space filled with acoustically transparent air soon rendered it impervious to the waves of sound. As long as the con- tinuity of the air in their interstices was preserved, the sound-waves passed freely through silk, flannel, green baize, even through masses of hard felt half an inch in thickness, the same sound-waves being intercepted by goldbeater’s skin. A cambric handkerchief which, when dry, offered no impediment to their passage, when dipped into water became an impassable barrier to the sound-waves. Hchoes of extraordinary intensity were sent back from non- homogeneous transparent air; while similar echoes were afterwards obtained from the air of the laboratory, rendered non-homogeneous by artificial means. Detached masses of non-homogeneous air often drift through the atmosphere, as clouds pass over the face of the sky. This has been proved by the fluctuations observed with bells having their clappers adjusted mecbkanically, so as to give a uniform stroke. The fluctuations occur only on certain days; they occur when care has been taken to perfectly damp the bell between every two suc- 1878.] | President's Address. 51 ceeding strokes ; and they also occur when the direction of the sound is at right angles to that of the wind. Numerous observations were also made on the influence of the wind, the results obtained by previous observers being thereby confirmed. From his own observations, as well as from the antecedent ones of Mr. Alexander Beazeley and Professor Osborne Reynolds, Professor Tyndall concludes that the explanation of this phenomenon given by Professor Stokes is the true one. Turning now to biological branches of Science, I find that the dis- coveries and researches of the past five years in this department also are far in advance of those of any previous period of equal length. The “ Challenger’ Expedition was, in point of the magnitude of the undertaking and completeness of its equipment, the rival of that for observing the Transit of Venus. Its general results, as far as hitherto made known, have been dwelt upon in my previous addresses, and the publication of them in detail is being rapidly pushed forward. Some very important papers by Mr. Moseley on the Corals collected on the voyage have indeed been published in our “ Transactions” with admirable illustrations by himself. To the Botanist and Geologist no subject has a greater interest than that of the conditions under which the successive Floras, which in- habited the polar area, existed and were successively dispersed over lower latitudes previous to their extinction, some 7m toto and over the whole globe, while others, though extinct in the regions where they once flourished, exist now only in lower latitudes under identical or under representative forms. It is only during the last few years that, thanks to the labours of those engaged in systematic Botany in tracing accurately the directions of migrations of existing genera and species, and in determining the affinities of the extinct ones, and of Paleontologists in referring the latter to their respective geological horizons, that any material advance has been made towards a knowledge of the origin and distribution of earlier and later Floras. I cannot better illustrate the condition of this inquiry than by calling your attention to two publications on the subject, which have appeared within the last few months. As a contribution to the principles of Geographical Botany, Count Gaston de Saporta’s essay, entitled “ L’Ancienne Végétation Polaire ” (which appeared in the ‘‘Comptes Rendus” of the French Inter- national Geographical Congress) is a very suggestive one, and having regard especially to its author’s eminence as a geologist and palxonto- logist, is sure to command attentive study. Although it may be argued that neither is solar nor terrestrial physics, nor Geology, nor Paleonto- logy in a sufficiently advanced condition to warrant the acceptation as fully established truths of all the conclusions therein advanced, still the array of facts adduced in evidence of these conclusions is very im- E 2 52 Anniversary Meeting. [Nov. 30, posing, while the ability and adroitness with which they are brought to bear on the subject are almost worthy of the great French genius whose speculations form the starting-point of the theory, which is that life appeared first in the northern circumpolar area of the globe, and that this was the birthplace of the first and of all subsequent Eloras. | I should premise that Count Saporta professedly bases his specula- tions upon the labours of his friend, Professor Heer, whose reasonings and speculations he ever puts forward with generous appreciation, while differing from him wholly on the subject of evolution, of which he is an uncompromising supporter; Professor Heer holding to the doctrine of the sporadic creation of species. In his “ Hpoques de la Nature” Buffon argues that the cooling of the olobe, having been a gradual process, the polar regions must have been the first in which the heat was sufficiently moderate for life to appear upon it; that other regions being as yet too hot to give origin to organised beings, a long period must have elapsed, during which the northern regions, being no longer incandescent, as they and all others originally were, must have had the same temperature as the tropical regions now possess. Starting from this thesis, Count Saporta proceeds to assume that the termination of the Azoic period coincided with a cooling of the water to the point at which the coagulation of albumen does not take place; and that then organic life appeared, not in contact with the atmosphere, but in the water itself. Not only does he regard life as originating, if not at the North Pole, at least near to it, but he holds that for along period life was active and reproductive only there. In evidence of this he cites various geological facts, as that the older, and at the same time the richest, fosilliferous beds are found in the cool latitudes of the North, namely in lats. 50° to 60°, and beyond them. It is in the North, he says, that Silurian formations occur, and though they extend as far south as lat. 35° N. in Spain and America, the most characteristic beds are found in Bohemia, England, Scandi- navia, and the United States. The Laurentian rocks again, he says, reacn their highest development in Canada, and Paleozoic rocks cover a considerable polar area north of the American great lakes, and appear in the coasts of Baffin’s Bay, and in parts of Greenland and Spitzbergen. It is the same with the Upper Devonian and marine carboniferous beds preceding the coal formations; these extend to 76” N. in the polar islands and in Greenland, and to 79° N. in Spitzbergen, and he adds that M. d’Archiac has long ago remarked that, though so continuous to the northward, the coal-beds become exceptional to the southward of 35° N. Hence Count Saporta concludes that the climatic conditions favourable to the formation of coal were not everywhere prevalent on the globe, for that while the southern limit of this forma- 1878. | President s Address. 53 tion may be approximately drawn, its northern must have extended to the Pole itself. I pass over Saporta’s speculations regarding the initial condi- tions of terrestrial life, which followed upon the emergence of the earlier stratified rocks from the Polar Ocean, and proceed to his dis- cussion of the climate of the carboniferous epoch as indicated by the characters of its vegetation, and of the conditions under which alone he conceives this can have flourished in latitudes now continuously deprived of solar ight throughout many months of the year. In the first place, he accepts Heer’s conclusions (founded on the presence of a tree-fern in the coal measures specifically similar to an existing tropical one), that the climate was warm, moist, and equable, and continuously so over the whole globe, without distinction of latitude. This leads him to ask whether, when the polar regions were inhabited by the same species as Hurope itself, they could have been exposed to conditions which turned their summers into a day of many months’ duration, and their winters into a night of proportional length P A temperature so equable throughout the year as to favour a rich growth of Cryptogamic plants, appears, he says, to be at first sight incompatible with such alternating conditions as a winter of one long night and asummer of one long day; but equability, even in high latitudes, may be produced by the effect of fogs due to southerly warm oceanic currents, such as bathe, the Orkneys and even Bear Island (in lat. 75° N.), and render their summers cool and winters mild. To the direct effects of these he would add the action of such fogs in obstructing terrestrial radiation, and hence preventing the evil effects which its cold would otherwise induce; and he would further efface the existing conditions of a long winter darkness by the hypo- thesis that the solar ight was not, during the formation of the coal, distributed over the globe as it now is, but was far more diffusive, the solar body not having yet arrived at its present state of condensation. That the polar area was the centre of origination for the successive phases of vegetation that have appeared in the globe is evidenced, under Count Saporta’s view, by the fact that all formations, Car- boniferous, Jurassic, Cretaceous, and Tertiary, are alike abundantly represented in the rocks of that area, and that, in each case, their constitutents closely resemble that of much lower latitudes. The first indications of the climate cooling in these regions is afforded by Conifere, which appear in the polar lower Cretaceous formations. These are followed by the first appearance of Dicotyledons with deciduous leaves, which again marks the period when the summer and winter season first became strongly contrasted. The introduction of these (deciduous-leaved trees) he regards as the greatest revolution in vegetation that the world has seen; and he conceives that once evolved they increased, both in multiplicity and in diversity of form, 54 Anniversary Meeting. [Nov. 30, with great rapidity, and not in one spot only, and continued to do so down to the present time. Lastly, the advent of the Miocene period, in the polar area, was accompanied with the production of a profusion of genera, the majority of which have existing representatives which must now be sought in a latitude 40° farther south, and to which they were driven by the advent and advance of the glacial cold; and here Count Saporta’s conclusions accord with those of Professor A. Gray, who first showed, now twenty years ago, that the representatives of the elements of the United States Flora previously inhabited high northern latitudes, from which they were driven south during the Glacial period. Perhaps the most novel idea in Count Saporta’s Hssay is that of the diffused sunlight which (with a densely clouded atmosphere), the author assumes to have been operative in reducing the contrast between the polar summers and winters. If it be accepted it at once disposes of the difficulty of admitting that evergreen trees survived a long polar winter of total darkness, and a summer of con- stant stimulation by bright sunlight; and if, further, it is admitted that it is to internal heat we may ascribe the tropical aspect of the former vegetation of the polar region, then there is no necessity for assuming that the solar system at those periods was in a warmer area of stellar space, or that the position of the poles was altered, to account for the high temperature of Pre-Glacial times in high northern latitudes; or, lastly, that the main features of the great continents and oceans were very different in early geological times from what they now are. Count Saporta’s views in certain points coincide with those of Professor Le Conte of California, who holds that the uniformity of climates during earlier conditions of the globe is not explicable by changes in the position of the poles, but is attributable toa higher temperature of the whole globe, whether due to external or internal causes, to the great amount of carbonic acid and water in the atmosphere, which would shut in and accumulate the sun’s heat, according to the principles discovered by Tyndall and applied by Sterry Hunt in explanations of geological times. Le Conte, however, admits the possibility of the earth’s having occupied a warmer position in stellar space, of its having exhibited a more uniform distribution of surface temperature, and a different distribution of land and water.* Before Count Saporta’s Essay had reached this country} another contribution to the subject of the origin of existing Floras had been communicated to our own Geographical Society, by Mr. Thiselton Dyer, in a Lecture on “ Plant Distribution as a field for Geographical * Professor Jos. Le Conte, in “ Nature,’’ October 24, 1878, p. 668. + Count Saporta’s Essay was presented to the International Congress of Geo- graphical Science which met in Paris in 1875, and was not received by me till the autumn of 1878, though it bears the date 1877 on the title page. 1878. ] President s Address. ay Research.” Mr. Thiselton Dyer’s order of procedure is the reverse of Count Saporta’s, and his method entirely different. He first gives a very clear outline of the distribution of the principal existing Floras of the continents and islands of the globe, their composition, and their relations to one another, and to those of previous geological epochs. He then discusses the views of botanists respecting their origin and distinctive characters, and availing himself of such of their hypotheses as he thinks tenable, correlates these with those of paleontologists, and arrives at the conclusion ‘‘ That the northern hemisphere has always played the most important part in the evolution and distribution of new vegetable types, or in other words, that a greater number of plants has migrated from north to south than in the reverse direction, and that all the great assemblages of plants which we call Floras, seem to admit of being traced back at some time in their history to the northern hemisphere.” This amount of accordance between the results of naturalists working wholly independently, from entirely different stand-points, and employing almost opposite methods, cannot but be considered as very satisfactory. I will conclude by observing that there is a certain analogy between two very salient points which are well brought out by these authors respectively. Count Saporta, looking to the past, makes it appear that the fact of the several Floras which have flourished on the globe being successively both more localised and more specialised, is the natural result of con- ditions to which it is assumed our globe has been successively sub- jected. Mr. Dyer, looking to the present, makes it appear that the several Floras now existing on the globe are; in point of affinity and specialisation, the natural results of the conditions to which they must have been subjected during recent geological time on continents and islands with the configuration of those of our globe. The modern development of botanical science, being that which occupies my own attention, is naturally that on whieh I might feel especially inclined to dwell; and I should so far have the excuse that there is, perhaps, no branch of research with the early progress of which this Society is more intimately connected. One of our earliest Secretaries, Robert Hooke, two centuries ago, Jaboured long and successfully in the improvement of the microscope as an implement of investigation. He was one of the first to reap the harvest of discovery in the new fields of knowledge to which it was the key, and if the results which he attained have rather the air of spoils gathered hither and thither im a treasury, the very fulness of which was embarrassing, we must remember that we date the starting point of modern histology from the account given by Hooke in his ‘ Micrographia”’ (1667) of the structure of cork, which had attracted his interest from the singularity of its physical properties. 56 Anniversary Meeting. 7 [Nov. 30; Hooke demonstrated its cellular structure, and by an interesting coin- cidence he was one of the first to investigate, at the request, indeed, of the founder of the Society, Charles 11, the movements of the sensi- tive plant Mimosa pudica—one of a class of phénomena which is still occupying the attention of more than one of our Fellows. In attribut- ing the loss of turgescence, which is the cause of the collapse of the petiole and subordinate portions of the compound leaf which it supports, to the escape of a subtle humour, he to some extent foreshadowed the modern view which attributes the collapse of the cells to the escape of water by some mechanism far from clearly understood—whether from the cell-cavities, or from the cell-walls into the intercellular spaces. Hooke having shown the way, Nehemiah Grew, who was also Secretary of the Royal Society, and Marcello Malpighi, Professor of Medicine in the University of Bologna, were not slow to follow it. Almost simultaneously (1671-5) the researches of these two indefati- gable students were presented to the Royal Society, and the publication of two editions of Malpighi’s works in London proves how entirely this country was at that time regarded as the head quarters of this branch of scientific inquiry. We owe to them the generalisation of the cellular structure, which Hooke had ascertained in cork, for all other vegetable tissues. They described also accurately a host of microscopic structures then made known for the first time. Thus, to give one example, Grew figured and described in several different plants the stomata of the epidermis :—“‘ Passports,” as he writes, either ‘‘ for the better avolation of superfluous sap, or the admission of air.” With the exception of Leeuwenhoek no observer attempted to make any substantial addition to the labours of Grew and Malpighi for more than a century and a helf, and however remarkable is the impulse which he gave to morphological studies, the view of Caspar Wolff in the middle of the 18th century (1759), in regarding cells as the result of the action of an organizing power upon a matrix, and not as themselves influencing organization, were adverse to the progress of histology. It is from Schleiden (1838) who described the cell as the true unit of vegetable structure, and Schwann who extended this view to all organisms whether plants or animals, and gave its modern basis to biclogy by reasserting the unity of organization throughout animated nature, that we must date the modern achievements of histo- logical science. Seldom, perhaps, in the history of science has any one man been allowed to see so magnificent a development of his ideas in the space of his own lifetime as has slowly grown up before the eyes of the venerable Schwann, and it was, therefore, with peculiar pleasure that a letter of congratulation was entrusted by your Officers to one of our Fellows on behalf of this Society on the recent occasion of the celebration of the 40th anniversary of Schwann’s entry into the professorate. 1878.] President's Address. He If we call up in our mind’s eye some vegetable organism and briefly reflect on its construction, we see that we may fix on three great steps in the analysis of its structure, the organic, the microscopic, and the molecular, and, although not in the same order, each of the three last centuries is identified with one of these. In the 17th century Grew achieved the microscopic analysis of plant tissues into their constituent cells; in the 18th, Caspar Wolff effected the organic analysis (inde- pendently but long subsequently expounded by the poet Goethe) of plant structures into stem and leaf. It remained for Nageli in the present century to first lift the veil from the mysterious processes of plant growth, and by his memorable theory of the molecular constitu- tion of the starch-grain and cell-wall, and their growth by intussus- ception (1858), to bring a large -class of vital phenomena within the limits of physical interpretation. Strasburger has lately (1876) followed Sachs in extending Nageli’s views to the constitution of protoplasm itself, and there is now reason to believe that the ultimate structure of plants consists universally of solid molecules (not how- ever identical with chemical molecules) surrounded with areas of water which may be extended or diminished. While the molecules of all the inert parts of plants (starch-grains, cell-wall, &c.) are on optical grounds believed by most physiologists to have a definite crystalline character, no such conclusion can be arrived at with respect to the molecules of protoplasm. In these molecules the characteristic properties of the protoplasm reside, and are more . marked in the aggregate niass in proportion to its denseness, and this is due to the close approximation of the molecules and the tenuity of their watery envelopes. The more voluminous the envelopes, the more the properties of protoplasm merge in those of all other fluids. It is, however, to the study of the nuclei of cells that attention has been recently paid with the most interesting results. These well- known structures, first observed by Ferdinand "Benes at the beginning of the century (1802), were only accurately described thirty years later by Robert Brown (1835). Up to the present time their function has been extremely obscure. The beautiful investigations of Strasburger (1875) have led him to the conclusion that the nucleus is the seat of a central force which has a kind of polarising influence upon the protoplasm molecules, causing them to arrange themselves in lines radiating outwards. Cell-division he regards as primarily caused by the nucleus becoming bipolar, and the so-called earyolitic figures first described by Auerbach, exhibit the same arrangement of the protoplasm molecules in connecting curves as in the case of iron-filings about the two poles of a bar-magnet. The two new centres mutually retire, and each influencing its own tract of protoplasm, the cell-division is thereby ultimately effected. This is but a brief account of processes which are greatly complicated in 58 Anniversary Meeting. — [Nov. 30, actual detail, and of which it must be remarked that while the interest and beauty of the researches are beyond question, caution must be exercised in accepting the mechanical speculations by which Strasburger attempts to explain them. He has himself shown that cell-division presents the same phenomena in the animal kingdom; a result which has been confirmed by numerous observers, amongst whom I may content myself with mentioning one of our own Society, Mr. F. Balfour. Strasburger further points out that this affords an argument for the community of descent in animal and vegetable cells ; he regards free cell-division as derivable from ordinary cell-division by the suppression of certain stages. Turning now to the discoveries made during the last five years in Physiological Botany, we find that no one has advanced this subject so greatly as Mr. Darwin. In 1875 was published his work on Insectivo- rous Plants, in which he aseertained the fact that a number of species having elaborate structures adapted for the capture of insects, utilized the nitrogenous matter which these contain as food. The most impor- tant principle established in the course of these researches was, that such plants as Drosera, Dioncea, Pinguicula, secrete a digestive fluid, which has led through Gorup Bezanez’s investigations on the ferment in germinating seeds, to a recognition of the active agency of ferments in the transmission of food-material, which marks a great advance in our knowledge of the general Physiology of Nutrition. The extreme sensitiveness of the glands of Drosera to mechanical and chemical stimulus (especially to phosphate of ammonia), the directive power of its tentacles, depending upon the accurate trans- mission of motor impulses, and the ‘‘reflex”’ excitation of secretion in the glands, were all discoveries of the most suggestive nature in connexion with the subject of the irritability and movements of plants. The phenomenon of the aggregation of the protoplasmic cell-contents in the tentacles of Drosera is a discovery of a highly remarkable nature, though not yet thoroughly understood. Lastly, Mr. Frank Darwin, following his father’s footsteps, as it were crowned the edifice by showing to what an extent insectivorous plants do profit by nitro- genous matter supplied to their leaves. In close relation to these researches are those, also by Mr. Darwin, on the structure and functions of the bladder of Utricularia, which he has shown to have the power of absorbing decayiig animal matter ; and those of Mr. Frank Darwin on contractile filaments of extra- ordinary tenuity attached to the glands on the inner surface of the cups formed by the connate bases of the leaves of the Teasel, which filaments exhibit motions suggesting a protoplasmic origin. It is to be hoped that their discoverer will pursue his investigations into these curious bodies, whose origin and real nature in relation to the plant and its functions are involved in obscurity. 1878. ] President's Address. 59 The subject of the cross-fertilization of plants, which though a long known phenomenon, first become a fruitful scientific study in Mr. Darwin’s now classical work ‘‘On the various contrivances by which Orchids are fertilized,” has within the last few years made rapid ad- vance under its author’s hand. The extreme importance of avoiding self-fertilization might indeed be inferred from the prevalence in flowers of elaborate contrivances for preventing it; but it remained to be shown that direct benefit attended cross-fertilization, and this has now been proved by an elaborate series of experiments, the results of which are not only that both increased fertility or greater vigour of constitution attend cross-fertilization, but that the opposite effects attend self-fertilization. In the course of these experiments it became evident that the good effects of the cross do not depend on the mere fact of the parents being different individuals, for when these were grown together and under the same conditions, no advantage was gained by the progeny ; but when grown under different conditions a manifest advantage was gained. As instances, if plants of Ipomea and Mimulus, which had been self-fertilized for seven previous gene- rations, were kept together and then intercrossed, their offspring did not profit in the least; whereas, when the parent plants were grown under different conditions, a remarkably vigorous offspring was obtained. Mr. Darwin’s last work, ‘‘ On the different forms of Flowers,” though professedly a reprint of his paper on dimorphic plants, pub- lished by the Linnean Society, contains many additions and new matter of great importance concerning the behaviour of polygamous plants, and on Cleistogamic flowers. Among other points of great interest is the establishment of very close analogies between the pheno- mena attending the illegitimate union of trimorphic plants, and the results of crosses between distinct species, the sterile offspring of the crosses of the same species exhibiting the closest resemblance to the sterile hybrids obtained by crossing distinct species; while a whole series of generalizations, founded on the results of the one series of experiments, are closely paralleled by those founded on the other. The bearing of this analogy on the origin of species is obviously important. Besides these investigations, Mr. Darwin has produced within the last five years second editions of his volume on the Fertilization of Orchids, and on the Habits and Movements of Climbing Plants; as also of his early works on Coral Reefs, and Geological Observations in South America; all of them abounding in new matter. Of special interest to myself, as having been conducted in the Jodrell Laboratory at Kew, are Dr. Burdon Sanderson’s investi- gations on the exceptional property possessed by the leaves and other organs of some plants which exhibit definite movements in a 60 Anniversary Meeting. [ Nov. 30, response to mechanical, chemical, or electric stimuli. In 1878, Dr. Sanderson showed us in this meeting room, that the closing of the laminze of the leaf of Dioncea is preceded by a preliminary state of excitement, and is attended with a change in the electric conditions of the leaf; and this so closely resembled the change which attends the excitation of the excitable tissues of animals, that he did not hesitate to identify the two phenomena. This remarkable discovery immediately directed the attention of two German observers to the electromotive properties of plants, one, Dr. Kunkel, in the Laboratory of Professor Sachs; the other Pro- fessor Munk, in that of the University of Berlin. Professor Munk, whose researches are of much the greater scope and importance, took as his point of departure Dr. Burdon Sanderson’s discovery. The leading conclusion to which he arrived was, that in Dioncea each of the oblong cells of the parenchyma is endowed with electromotive properties, which correspond with those of the ‘“ muscle- cylinder ” of animals ; with this exception, that whereas in the muscle- cylinder the ends are negative to the central zone, in the vegetable cell they are positive; and he endeavours to prove, that according to this theory, all the complicated electromotive phenomena which had been observed, could be shown to be attributable to the peculiar arrange- ment of the leaf-cells. During the last two summers Dr. Burdon Sanderson has been .engaged in endeavouring to discover the true relations which subsist between the electrical disturbance, followed by the shutting of the leaf-valves of Dioncea and the latent change of protoplasm which precedes this operation. He has found that though the mechanism of the change of form of the excitable parenchyma which causes the contraction is entirely different from that of muscular contraction, yet that the correspondence between the exciting process in the animal tissues, and what represents this in plant tissues appears to be more complete the more carefully the comparison is made; and that whether the stimulus be mechanical, thermal, or electrical, its effects correspond in each case. Again, the excitation is propagated from the point of excitation to distant points in the order of their remoteness, and the degree to which the structure is excited depends upon its temperature. Notwithstanding, however, the striking analogies be- tween the electrical properties of the cells of Dionewa and of muscle- cylinders, Dr. Burdon Sanderson is wholly unable to admit with Professor Munk that these structures are in this respect comparable. In Morphological Botany attention has been especially directed of late to the complete life-history of the lower order of Cryptogams, since this is seen to be more and more an indispensable preliminary to any attempt at their correct classification. 1878. ] President's Addvess. 61 The remarkable theory of Schwendener, now ten years old, astonished botanists by boldly sweeping away the claims to auto- nomous recognition of a whole group of highly characteristic organisms—the Lichens—and by affirming that these consist of asco- mycetal fungi united in a commensal existence with Algw. The con- troversial literature and renewed investigations which this theory has given rise to are now very considerable. But the advocates of the Schwendenerian view have gradually won their ground, and the success which has attended the experiments of Stahl in taking up the challenge of Schwendener’s opponents and manufacturing such lichens as Hndocarpon and Thelidium, by the juxtaposition of the appropriate Algz and Fungi, may almost be regarded as deciding the question. Sachs, in the last edition of his Lehrbuch, has carried out completely the principle of classification of Alg, first suggested by Cohn, and has proposed one for the remaining Thallophytes, which disregards their division into Fungi and Alge. He looks upon the former as standing in the same relation to the latter as the so-called Saprophytes (e.g. Neottia) do to ordinary green flowering-plants. _ This view has especial interest with regard to the minute organisms known as Bacteria, a knowledge of the life-history of which is of the greatest importance, having regard to the changes which they effect m all lifeless and, probably, in all living matter prone to decom- position. This affords a morphological argument (as far as it goes) against the doctrine of Spontaneous Generation, since it seems extremely probable that just as yeast may be a degraded form of some higher fungus, Bacteria may be degraded allies of the Oscillatorice which have adopted a purely saprophytal mode of existence. Your “‘ Proceedings ” for the present year contain several important contributions to our knowledge of the lowest forms of life. The Rev W. H. Dallinger, continuing those researches which his skill in using the highest microscopic powers and his ingenuity in devising experi- mental methods have rendered so fruitful, has adduced evidence which seems to leave no doubt that the spores or germs of the monad which he has described differ in a remarkable manner from the young or adult monads in their power of resisting heated fluids. The young and adult monads, in fact, were always killed by five minutes’ exposure to a temperature of 142° F. (61° C.), while the spores germinated after being subjected to a temperature of ten degrees above the boiling point of water (222° F.). Two years ago, Cohn and Koch observed the development of spores within the rods of Bacillus subtilis and B. anthracis. These observa- tions have been confirmed, with important additions, in these two species by Mr. Ewart, and have been extended to the Bacillus of the infectious pneumo-enteritis of the pig, by Dr. Klein; and to Spirillum ‘by Messrs. Geddes and Ewart; and thus a very important step has 62 Anniversary Meeting. [ Nov. 30, been made towards the completion of our knowledge of the life-history of these minute but important organisms. Dr. Klein has shown that the infectious pneumo-enteritis, or typhoid fever of the pig, is, like splenic fever, due to a Bacillus. Having succeeded in cultivating this Bacillus in such a manner as to raise crops free from all other organisms, Dr. Klein inoculated healthy pigs with the fluid contain- ing the Bacilli, and found that the disease in due time arose and followed its ordinary course. It is now therefore, distinctly proved that two diseases of the higher animals, namely, “‘ splenic fever” and ‘infectious pneumo-enteritis,” are generated by a contagiwm vivum. Finally, Messrs. Downes and Blunt have commenced an enquiry into the influence of light upon Bacteria and other Fungi, which promises to yield results of great interest, the general tendency of these investigations leaning towards the conclusion that exposure to strong solar light checks and even arrests the development of such organisms. The practical utility of investigations relating to Bacillus organisms as affording to the pathologist a valuable means of associating by com- munity of origin various diseases of apparently different character, is exemplified in the ‘‘ Loodiana fever,” which has been so fatal to horses in the Hast. The dried blood of horses that had died of this disease in India has been recently sent to the Brown Institution, and from seeds therein contained a crop of Bacillus anthracis has been grown, which justified its distant pathological origin by reproducing the disease in other animals. Other equally interesting experiments have been made at the same Institution, showing that the ‘“ grains” which are so largely used as food for cattle, afford a soil which is peculiarly favourable for the development and growth of the spore filaments of Bacillus; and that by such “‘ grains” when inspected, the anthrax fever can be pro- duced at will, under conditions so simple that they must often arise accidentally. The bearing of this fact on a recent instance in which anthrax suddenly broke out in a previously uninfected district, destroying a large number of animals, all of which had been fed with grains obtained from a particular brewery, need scarcely be indicated. In Systematic Botany, which in a nation like ours, ever extending its dominions and exploring unknown regions of the globe, must always absorb a large share of the energies of its phytologists, I can but allude to two works of great magnitude and importance. Of these, the first is the “Flora Australiensis” of Bentham, com- pleted only a year ago; a work which has well been called unique in botanical literature, whether for the vast area whose vegetation it embraces (the largest hitherto successfully dealt with), or for the masterly manner in which the details of the structure and affinities of upwards of 8,000 species have been elaborated. Its value in reference as os a 1878.] President's Address. 63 to all future researches regarding the geographical distribution of plants in the southern hemisphere, and the evolution therein of generic and specific types, cannot be over estimated. The other great work is the ‘“ Flora Braziliensis,’” commenced by our late Foreign Fellow, von Martius, and now ably carried on by Hichler, of Berlin, assisted by coadjutors (among whom are most of our leading systematists) under the liberal auspices of His Majesty the Emperor of Brazil. When completed, this gigantic undertaking will have embraced, in a systematic form, the vegetation of the richest botanical region of the globe. Having now endeavoured to recall to you some of the creat advances in Science made during the last few years, it remains for me, after the distribution of the Medals awarded by your Council, to retire from the Presidency in which I have so long experienced the generous support of your Officers and yourselves. This support, for which I tender you my hearty thanks, together with my sense of the trust and dignity of the office, and the interest attached to its duties, make my resignation of it a more difficult step than I had anticipated. ' My reasons are, however, strong. They are the pressure of official duties at Kew, annually increasing in amount and responsibility, together with the engagements I am under to complete scientific works, undertaken jointly with other botanists, before you raised me to the Presidency; and the fact that indefinite postponement delays the publication of the labours of my coadjutors. I am also influenced by the consideration that, though wholly opposed to the view that the term of the Presidency of.the Royal Society should be either short or definitely limited, this term should not be very long; and that, considering the special nature of my own scientific studies, it should, in my case, on this as well as on other grounds, be briefer than might otherwise be desirable. Cogent as these reasons are, they might not have been paramount, were it not that we have among us, one pre-eminently fitted to be your President by scientific attainments, by personal qualifications, and by intimate knowledge of the Society’s affairs; and by calling upon whom to fill the proud position which I have occupied, you are also recognising the great services he has rendered to the Society as its Treasurer for eight years, and its ofttimes munificent benefactor. On the motion of Dr. Graham Balfour, seconded by Sir Alexander Armstrong, it was resolyved—‘“‘ That the thanks of the Society be re- turned to the President for his Address, ard that he be requested to allow it to be printed.” The President then proceeded to the presentation of the Medals. The Copley Medal has been awarded to Jean Baptiste Boussingault b4 Anniversary Meeting. | Nov. 30, for his long-continued and important researches and discoveries in agricultural chemistry. The researches of Boussingault have extended over nearly half a century, and it might be difficult to find an investigator whose results relating to a great variety of subjects have in respect of accuracy and trustworthiness better stood the test of time. The lucid simplicity with which his writings narrate well-established and well-arranged facts, is not less remarkable than the judicial caution with which he has abstained from expressing opinions upon questions beyond the reach of decisive evidence. His experimental results and the conclusions which he has drawn from them have been deservedly trusted by other workers in the same field, and have safely guided them in their labours. Their incon- testable excellence has prevented them from becoming subjects of animated discussion, and thus arousing as much attention and interest in the outer world as has sometimes been aroused by hasty experi- ments and daring generalizations. I cannot attempt within the limits of this address to give an account of his investigations, and I should probably weary you were I even to enumerate them, relating as they do to a vast variety of phenomena ; but I may point out that lying as most of them do in the domain of agricultural chemistry, they have involved difficulties of no common order. Boussingault is not only an excellent chemical analyst and experimentalist, but at the same time a model farmer. His numerous determinations of the nitrogen, carbon, and hydrogen in crops and in the manures supplied to them, have proved him to be skilled not only in selecting and applying the best known methods of analysis, but even in improving and perfecting them. His determinations of the proportions of those valuable constituents of manures which can be assimilated by various crops, have involved an intimate acquaintance with the conditions which experience has proved to be most favourable to the cultivation of the various crops. His numerous and varied experiments on the feeding of animals, showing the proportions between the nitrogenized and fatty or amy- laceous constituents supplied in the food and those assimilated or formed by the animal organism, while tracing the distribution of the remainder between the pulmonary and other excretions, have had most important physiological as well as practical bearings. In all his investigations we see proofs that while accurately and critically acquainted with the discoveries and opinions of other workers and thinkers in his own particular domain of science, he has been able to devise and carry out simple and crucial forms of experiment well calculated to decide the truth. A remarkable instance of this is afforded by those truly masterly experiments by which he proved that all the nitrogen found in the 1878. | | President s Address. 65 organism of plants can be traced to compounds of that element which had been supplied to them ; and accordingly that there are no grounds for believing that plants can assimilate the free nitrogen of the air. By awarding to Boussingault the Copley Medal, we place his name in the honoured list of those who, in modern times, have rendered the highest services to the advancement of natural knowledge. A Royal Medal has been awarded to Mr. John Allan Broun for his imvestigations during thirty-five years in magnetism and meteorology, and for his improved methods of observation. When the labours of Gauss had given an impetus to the study of terrestrial magnetism by rendering precision possible, Observatories devoted to this branch of research, in conjunction with meteorology, began to rise in various places. The late General Sir T. M. Brisbane erected one at Makerstown, in Scotland, and placed it under the direc- tion of Mr. Broun, who remained in charge of it from 1842 to 1850. His observations and their results, have been commended by magne- ticians and meteorologists, for the skill employed in the development of new methods of reduction and investigation. In 1851 Mr. Broun went to India to organize and take charge of a similar Observatory established at Trevandrum by His Highness the late Rajah of Travancore. Here he remained for thirteen years, accumulating results of very great value, the first instalment of which, consisting of a volume on the magnetic declination, was published some years ago. Magneticians look eagerly towards the completion of this publication when the means necessary for the purpose shall have been furnished to Mr. Broun. While in India he established an Observatory on a mountain peak 6,000 feet above the sea, and fitted it up with a very complete assort- ment of scientific instruments. This was an undertaking of a very arduous nature, effected in a wild country, and presenting great diffi- culties in the erection of instruments and obtaining trained observers. Shortly after the commencement of. magnetic observatories, Mr. Broun indicated the insufficiencies of the methods then in use for determining coefficients and correcting observations, and he devised new methods for these ends, the principal of which have been gene- rally adopted. This is not the place in which to give a complete catalogue of Mr. Broun’s researches in magnetism and meteorology, extending as they do over a period of thirty-five years, but I may indicate those of his results that are of the greatest importance. Among them are the establishment of the annual laws of magnetic horizontal force, exhibiting maxima at the solstices and minima at the equinoxes. Mr. Broun was also the first to give ina complete form the laws of change of the solar-diurnal variation of magnetic declination near the VOL. XXVIII. E 66 Anniversary Meeting. [Nov. 30, equator, showing the extinction of the mean movement near the equinox. His researches on the lunar-diurnal variation of magnetic declination are of very great interest. Besides being an independent discoverer of the existence of this variation, he showed that near the equator its law in December was the opposite of that in June. He found, too, that the lunar-diurnal variation was in December some- times greater than the solar-diurnal variation—that the lunar action was reversed at sunrise, and that rt was much greater during the day than during the mght, whether the moon was above or below the horizon. Finally, he found that the lunar-diurnal law changed (like the solar-diurnal law at the equator) near the equinoxes, so that, as a consequence, the laws for the southern and northern hemispheres were of opposite natures. Another and very remarkable fact discovered by Mr. Broun was that the variations from day to day of the earth’s daily mean horizontal force were nearly the same all the world over. He found certain oscillations in these daily means which were due to the moon’s revolution, and others having a period of twenty-six days; the latter he considered as due to the sun’s rotation. It results from these in- vestigations that the observed variations of the earth’s daily mean horizontal force have been represented with considerable accuracy in all their more marked features, by the combination of the means calculated for these different solar and lunar periods. During the discussion of these periods, Mr. Broun found that the great magnetic disturbances were apparently due to actions proceeding from par- ticular points or meridians of the sun—a fact this (af verified) of very great importance. In meteorology he has shown the apparent simultaneity of the changes of daily mean barometric pressure over a great part of the globe, and he has likewise discovered a barometric period of twenty- six days nearly. He was also the first to commence and carry out, during several years, a systematic series of observations of the motions of clouds at different heights in the atmosphere; and, lastly, he has found certain laws connecting the motions of the atmosphere, and the directions of the lines of equal barometric pressure. A Royal Medal has been awarded to Dr. Albert Ginther, F.R.S., for his numerous and valuable contributions to the zoology and anatomy of fishes and reptiles. Dr. Ginther’s labours as a systematist and a descriptive zoologist have been devoted chiefly to the order of Fishes, Reptiles, and Am- phibia. Upon these he has published during the last quarter of a century a very long series of valuable papers, whereby our knowledge of the structure, affinities, and distribution of the genera and species of those interesting groups has been greatly advanced. We owe to his indefatigable exertions the excellent condition in point of arrangement 1878. | President's Address. 67 and nomenclature of the unrivalled collection of fishes in the British Museum, and of which he prepared a systematic catalogue in eight volumes, which has been published by order of the Trustees. This isa work of prodigious labour; it required for its satisfactory execution an intimate knowledge of the fish of all parts of the world, and an intui- tive perception of the natural character upon which a sound classifica- tion should be based. From possessing these attributes it has been accepted as the standard authority on the order by all zoologists. Under this head too I must specially allude to his excellent work on the Ceratodus. The Reptilian collections of the Museum have been no less successfully dealt with by Dr. Gunther, and have afforded the material for some of his most important works, amongst which his ‘“‘ Reptiles of British India,” ‘‘Memoir on Hatteria,’’ and “‘ Mono- graph of the Gigantic Land Tortoises of certain islands in the Pacific and Indian Oceans,” are examples conspicuous for their completeness and accuracy. The Rumford Medal has been awarded to Mr. Alfred Cornu for his various Optical Researches, and especially for his recent redetermina- tion of the Velocity of Propagation of Light. _ Mr. Alfred Cornu is the author of papers on optical and other subjects published in the ‘‘Comptes Rendus’”’ and other scientific periodicals. He has been engaged, for example, with the difficult subject of crystalline reflection, and kindred researches. It was in 1849 that Fizeau astonished the scientific world by an actual experimental determination of the velocity of light, a velocity so enormous that hitherto its finiteness has been proved, and its value approximately determined, only by two astronomical phenomena. Foucault almost simultaneously brought out an experimental deter- mination by a totally different method. The method of Fizeau gave at once a near approximation to the value got from those two astronomical phenomena, combined with the parallax of the sun, assumed known. But the difficulties of obtaining a sufficiently accurate result were such that the velocity obtained by Fizeau’s method was not considered to rival in exactness the velocity determined astronomically. Indeed, Foucault’s method seemed to be | preferred, though Fizeau’s is the simpler in principle, and is free from certain doubts which may be raised as regards the other. But the difficulties alluded to, which turned mainly on the determination of the velocity of the revolving wheel, were such that almost twenty years have elapsed without the method having been brought to a sufficient degree of perfection to make it astronomically available. Such was the state of the problem when it was taken up by M. Cornu. By methods of his own devising he succeeded in getting over the difficulties with which Fizean’s further progress had been F2 68 Anniversary Meeting. [ Nov. 30, stopped, and in achieving a determination so exact as to compete with the astronomical determinations, and thereby lead, we may say, to an experimental determination of the solar parallax fully rivalling that which is likely to result from the observations of the transit of Venus which have béen carried out at so much cost and trouble. A double award of the recently instituted Davy Medal has again been made, the recipients on the present occasion being M. Louis Paul Cailletet and M. Raoul Pictet. This award is made to these dis- tinguished men for having, independently and contemporaneously, liquefied the whole of the gases hitherto called permanent. The methods pursued by these experimenters, in accomplishing results which equal in interest and importance those obtained by Faraday in the same direction fifty-five years ago, were quite distinct, and were, in each case, the result of several years’ preparatory labour. M. Cailletet, by comparatively very simple arrangements, such as admit of ready employment in lecture-demonstrations, has succeeded in obtaining evidence of the liquefaction, and possibly solidification, of carbonic oxide, marsh-gas, oxygen, nitrogen, and hydrogen. His system of operating consists in submitting the gases to very powerful compression at comparatively moderate degrees of cold, aad in then allowing them very suddenly to expand. M. Pictet has applied the very perfect system, elaborated and put to industrial use by him, for obtaining low temperatures to the attain- ment, though on a larger scale, of results like some of those arrived at by M. Cailletet. By an arrangement of vacuum and force pumps he reduces liquefied sulphurous acid to a low temperature, and applies this as the means for cooling down liquid carbonic acid which, in turn, serves to reduce to a very low temperature a thick glass tube, in which the gas to be condensed is confined at a very high pressure. M. Pictet has not only produced liquid oxygen in somewhat consider- able quantity, and succeeded in determining its density, he has also obtained evidence of the solidification of hydrogen, and the description given of its appearance in the solid form seems to leave no doubt regarding its metallic character. The interest which attaches to the remarkable experiments of MM. Cailletet and Pictet is only equalled by the importance of the fact, now absolutely demonstrated by those experiments, that the property of molecular cohesion 1s common to all known bodies without exception. The Statutes relating to the election of Council and Officers were then read, and Mr. Ellis and Mr. Mchachlan having been, with the consent of the Society, nominated Scrutators, the votes of the Fellows 1878.] Number of Fellows. 69 present were taken, and the following were declared duly elected as Council and Officers for the ensuing year :— President.— William Spottiswoode. M.A., D.C.L., LL.D. Treasurer.—John Evans, F.G.S., F.S.A. elses | Professor George Gabriel Stokes, M.A., D.C.L., LL.D. eerelaries.— ) Professor Thomas Henry Huxley, LL.D. Foreign Secretary.—Alexander William Williamson, Ph.D. Other Members of the Couwncil_—Frederick A. Abel, C.B., V.P.C:S. ; William Bowman, F.R.C.S.; William Carruthers, V.P.L.S.; Major- General Henry Clerk, R.A.; William Crookes, V.P.C.S.; Sir William Robert Grove, M.A.; Augustus G. Vernon Harcourt, F.C.S.; Sir Joseph Dalton Hooker, C.B., K.C.S.I., D.C.L.; Admiral Sir Astley Cooper Key, K.C.B.; Lieut.-General Sir Henry Lefroy, C.B.; Lord lindsay, P.R.A.S.; Sir John Lubbock, Bart., V.P.LS.; Lord Rayleigh, M.A.; Charles William Siemens, D.C.L.; John Simon, C.B., D.C.L.; Professor Allen Thomson, M.D., F.R.S.E. The thanks of the Society were given to the Serutators. The following Table shows the progress and present state of the Society with respect to the number of Fellows :— Patron Com- £4 and Foreign. | pounders. | yearly. Total. Royal. | | November 30, 1877. 4 43 252 250 552 DECHE0) ae tie + 4 + 13 Je Weceased ........ — 6 a A) — 16 | — 27 Since compounded Se 2a ee 12 November 30, 1878. 4 | 44 253 248 d49 [ Nov. 30, Financial Statement. 9 I i or) OL Se © 0 Ons él LVLOLF (0: Boece eee uoryeVUocy ‘spoorpog odaoryoyqeyy Cae eage Se sosreyy Ayjog pur ‘spooreg ‘asvqysog 0 6T 91 AAAIOODCOOOOODODOOOUO OSD OIODOOOODUUOOOOCOOOOOUOOOUD SUISLOAPW Boieiice SOXtT, ee 4 0 CT IP cece terre ena t ete n ee ensseaseteseeessbessensseeee doUBINSUT OIL AL 9 g 0Z pace e eee r arena cerns ener esaseresceeearessseretare sosuod xi eOT, jh T 1K RRINSIDOOOODOODOOODOOOOOOOOUCOOOCOOOCOIOOOOU sosuod xi osnoyy 6 iP 6Z AOD DODDS DDUOOUDODOUDUGOODOOOOODDDODOD0UO00 sosuod xp sO Le PL 06 isvesateloletaielelavele/ayeletoceisielsrejalei/axe/ereiaiio{eTs\aleve 1016)» “op ‘SOUNYSIT Te0g (Ee sosuad xy uorydeooy pur eeatog Ge. eee Sono fydeasoyyvy pur SUIABASU TiOMeDlicws soaker op Suroiyg pur Surpurg 0 GL Sif “ “Sssurpossorg puv suoorsuety, coy sodeg e06‘T I G7 19 eee eee tenet essen esses sete ersscere SNOOULTIOSI TAL oy GLE Gag Seer Z8T-OLT ‘SON ‘sSurpoa001g OF91(T OL GI 88 cme royst Gn pure sco lp ‘s g 09 setdog oyvavdeg pue “g48T “I Weg pue YZJ8T ‘IT Meg ‘suomovsuesy, PEE I ips Cancers ePeccecenos=oorcon oygtp Surpurg, SPL ReetetelelatetetsiststefeletelstaletelefoveleseliereleeisTels[o{elalearafelnlatelelslalalezelelelefeleieze Arecquy oma LOF syooq OZ cect cece cnccsscccertvessresscscsssce Sereeseeesassace ansoTeyeVy OYIYWOTO ony, 66L ga s)e.aleiee sineieieianisienaeieotenceessevinsee (uortpodxiy snud A. -JO- qISUeLT,) systernqeny jo yaodey «oz aodeg pus suomeajeny[y OZLT nodgonnansuedac0gd0 canoe obocdOaNEHDOdoaGesoS0Gb0qG0N 0000000 SO5U AA pur SoLmeyeg a s[OSUON “s9T ZF JWSnog 000‘eT soonoacdooosundoNoBO0O ADDS doUNodadQOTABADNOMODIDOONUBOOGNoDND0d0000 uvory odes zoyy + oo RS LT Lt '0erF TL RG teers eneetennecnnene JIGT wos soourreg Re ee eer eereeeeorceenereer pung woremocy roy“ 0 GOL cere tse soy] aq JO 4809 10 SMOeUO | teesesssseeestnsuneenecscssnencassecenncnesteceecuneregsunnntte seme OL OTL ee y re eee iota = “OW ‘sSuIp90001 7 ‘SUOTIOVSUBLT, JO 9[BS 6 6S Pee e eee eee emer e eee terete sree ete eeeees UvOrT ISVSILOTY ne) qso.toquy Cee oa TeOpe. © Li Cre’ et tet ae eat es ae - (spung qysud 7, JO OAISNOX9) SPUOPIAT FUG eerneerrerteseeccentecteeshehateseemnticessaateenteactennenten mest 6) 000‘ST eee eee e eee e teen ee ee etre rteenseene EOD “p9 ‘SOT Von Cig a[eg 0 rats joo npdood sav bbacboDdsdeGadabGCUdOUOUbUO LO DUdDDADODADODROOOODOOD00 suorisodutog OST memriestsersrestesnseemscenssensstste Zag MOTT 0 S20‘ aleeleletsfeteieleisfarsielstelaiiekslefelerelaiatelelelateleinleielelsfelatsle(ereyeleyelefelslalee suOTNGIy WON jenuy ae ‘SLST old HOQuraao AT 99 ‘2181 ‘eZ HOQUWado AT Uotf aingupuada ay Ee) sydiaoay fo JUIWIZDIS 71 Financial Statement. 1878.] “pung epon £4eq—"S8 ACM LOY ‘puny Tepopy Aodog pu uei "(84-L18 pues sorpmMuUwy JUOLUULTO AO K) ‘yee ogy UO 4SotoJUL [enuus YANOF IUC) uur sod ep ‘surtoishyg JO odo][OD oy} WOT TH 9 “mUnUUY ‘unuur dod ‘pot “SZT LZ ‘mmuue dod 9¢TF ‘(a ZUG “V SG ‘qsndy, JOISSVH ST —'Spuog WONVSIAAT ULITRIT OOO'OTS ‘quar tod G pooyuRaeny seIpey O9IT ‘staO jf BIPUT “PO “SG LOGF “puny [jetpo F—'s90tt MO NT ‘PL “SPL 12% OF TOyR—yoojG “quay aod 4% MON “PS “86 EOVS ‘SOIMULY YUB_ PoywpTPOSMo“) "PST SQ 88G‘OTF ‘quo aod p ‘Uvory 09v54.LOW OOO'STF ‘sormuny “gue dod ¢ poonpoy, “PS 8B 868°61F ‘qsonbog ‘spung ysnay, Hurpnjow Kyawog wwhoy a7 Jo Hpiadorg Pun 8a,0ISH “MOMNSVDIA T, ‘“TAOOMSIELEOdS “M Ga 6 & a6 0cF Vee GGe cos “USB AyWog pue onsoypeye9 “purty MO SODULTCE Dg oes, i gaa cone cate TE quer qu oowepegg (e 61 ee ee aanqoory UBITOO.L | er epee ee re oamnyoory UvILoyeg T Gi P BON OCD COU DDO ODOUUCOOUOUCUGUOCUOUDUORG puny [ePent Katdon Sasi O9e ge ecg 9 pun Urey SULAyUT AA | T c Sol deueseeeuaeenecceneccertvesteuseenmeenes puny Tepey Lang Lo GC COL see eleiws eve teu sieieesisesisiese ens sienereie qtiquesinvs puny WOTYVUO(T “Pp 9 - 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Pe eeeenne COTO COD ve ee ee renee eerecorecnonneseersesereceovescee oOULl eg ! 0 OL Pes Cote eee e secre seereceeseresescnes eseees cae nem renee [050 G0pn OCU DONORS ERO PONE O aU BODOE SATE IEE Rae yy snoq spulog @ CL CGR tt ees nioleur¥oXalelela/a{eTolsitfelofefeleleisiatelsistevaisiaiatetevciste 90} }TULTLOD MOY 074 syUOUIAR Ag 0 0 98z scalelelelateyatereseinieteiniernielars lelelereteiccmreisicteceieiarere IF SG: Core e ete tere reneraseccee verseve bia alejejolaje/elelelelsioieielelalalelslelelefaisvelalefels(ejerelereinieictiieieiete oouRleq wesoreLeeershaLeaiavelnlainlsiiniuacssiesiselaiostye e/afelaicrarsiatuclvivitaherieresareaafeleceieieretteraee S[Rpoyl ploy (44 Il 8 Ze Wieteie{ss/ssareluieialejsielels/s/s\xieleinlein]sivielojelelejsisisieisisiele\pieisis) — sieiejalaieinie Souryqt pue sol Kq Gc e OFZ O/e)ealaielolejeimisieinialelelstale{d/els|s\e/ole(efadcis(evs\e/elerele DSSS: OT 8L 649F ‘Y00}G ‘quop aod g poonpoy “pe “sg gEg’cR ‘pung haypunyy ay, Ee GF "y004g “quoy tod G MON ‘PT “SPL 1zz‘OR “PUNT [J24pOf AY, ‘Splog woresiaay welypery OOO‘OTS ‘JSNMNT, JOUSD) AUT, bv GL 8LeF "y0}G AVMTIOAT ‘quog aod ¢ pooyuBren4 svIpey 0997 ‘pung yopayr hang 6 OL ESI conn noododdusscnauDdobOUDGGSdb0b00N Pde e rere are rere sesstreessneereees ter wher eane Leese ecenes SZ8T ‘Sspuopral(y Tete wea rece enee resseee LL81 ‘OoUvlRg huis onesie OaePveeneie rei aae eye S/8T ‘Spmoprarc(y anoosnossudnandDCUOdaNOTOGD AGE TABI spuog fe) Yolefelelelehel-satetalelstefstetetatele/avertettersisteerts spuoprary S- ppdonadandnonane oouvye OF, dondaous0po0dd. angunbAANBoGanGUEEed spueprarq avonobe Reselalefctetalaretsietieieteryetst aceite ooueleg OL, 1878. | Appropriation of the Government Grant. 75 Account of Grants from the Donation Fund in 1877-78. For Illustrations for the Naturalists’ (Transit of Venus) [NGIDNGIOUS Vovp-fie, BID idee wale 18 Bt CYR Emon re means et Cee £200 0 O J. Hvans, for Exploration of Caves in Borneo.......... SOP OO J. KH. H. Gordon, for continuation of Researches on the Specific Inductive Capacity of Dielectrics ...... 20) 9) 0 W. R. Hodgkinson, for an Investigation on the Action of Ethylbenzol Acetate upon acetic, butyric, and iso- inirne TNMs Gees Go sboeseeseo once noes cence 29,° OF 0 £300 0 O Account of the appropriation of the sum of £1,000 (the Govern- ment Grant) annually voted by Parliament to the Royal Society, to be employed in aiding the advancement of Science (continued from Vo]. XX VI, p. 457). 1878. 1. W. Ramsay, for Apparatus to be employed in a Research into the Action of Light and Heat in Decomposing Hydriodic and Hydrobromic Acids, with a view to compare the action of Re em NTC Nis 6.5 acc. 2 5 Bhs, HAAS D8 ea a eas, spot dae sa a's # es eisue oe £30 2. J. H. Poynting, to determine the Mean Density of the Harth by means of an Ordinary Balance in place of the Torsion Balance, and to Investigate means to very greatly increase the Premmmtemmorstnhe Balance. ... 62. s.ccs ew cc cs cvaccertscedees 150 3. Captain Abney, for registering the Intensity of the Spec- SUMMON ANIMATE een ie wee a vie ge eee eee wine els seul woe et esis D0 4, Dr. Duncan and P. Sladen, for Publication of a Monograph of the Arctic Hchinodermata, especially those of Smith’s Sound SPIO MMOMIAME MONG (25,421 op APRIGNONTas re a aild w ailsde. hata =, 4 vie + siesie thecheja's meats 60 5. Bevan Lewis, for a Research into the Histology of the Cerebral Cortex in Man and the higher Mammalia, with especial reference to the Motor Area as defined by Professor Ferrier.... lo 6. D. Mackintosh, for aid in tracking Streams of Erratic Blocks from their Parent Rocks, to ascertain the Character of the Drift Deposits with which they are associated ............ 25 7. W.C. Williamson, for continuation of Researches into the Wasci@elants of the Coal Measures ...... 2.5.00. ecceecces 30 @arriedttiorweandis cas 4 45.62 s0 6 en 7360 76 Appropriation of the Government Grant. [Nov. 30, Brought forward. . Ja... 252s. aresou 8. Professor Lankester, for the Investigation of the Life- History and Specific Forms of Bacteria; the Relation of Special Forms to Special Putrefactive and other Physiological Activities; and the Generie and Speciic Distimebionsss..4.. 0.0 eee 4.0: 9. A. Wynter Blyth, for continuation of Researches into the Chemical Constitution of the Poison of the Cobra de Capello .. 20: 10. M. M. Pattison Muir, for Investigation of the Chemical Nature of Hssential Oil of Sage, and the Determination of the Chemical and Physical Constituents of this Oil .............. 30 11. A. Macfarlane, for Apparatus to continue and extend an exact experimental Research into the Conditions of Passage of the Disruptive Discharge or Mlectrictiyey ses) r eee 50: 12. W. Crookes, for continuing his Researches connected with Repulsion resulting from Radiation ............... ois ciebeenans 200° 13. Professor Church, for continuation of Researches in Plant Chemistry 0.5 dc eels b Fie' so dye ese oye Soy soles ei cibie sce 50 14. H. Neison, for Computations in the Lunar Theory ...... 75: 15. G. J. Stoney, for completing a Spectroscope of great Aperture and continuing his Experiments on the Motions in GASES so Pa) aseva oie Hele. 0) Sie ie se See oie eUaISe Sl Sey 100: 16. B. Stewart, for analysing the Records of Magnetic Decli- _ TRA GTON. £6600 oscug Ses 0S S08) ahaa vers in ouece Catal pees yoleeh cee eee ene ae 15- 17. Baron Ettingshausen, for travelling expenses, and main- tenance in England during the preparation of a Monograph on the Hocene Flora ot Great Britaim..... <2... 2 0.4. eee 50: £1050 Dr. Or.. £ Some den| | 35 Ss. d. To Balance on hand, Nov. 30, | By Appropriations, as RSG eis dares vereqeie 1015 18 G|.. above....... d,s ielGsG imme Grant fon Teenoune Y> 1878 .... 1000 0 0 | Printing, Postage, and . Repayments. |) Advertising a erci-rr 8. oa R. H. Scott, balance £35 O O | Balance on hand, NGe W. Ramsay s,, 30 0 O |; 80,1878 ....5sn6 LOSZISiGe 65 0 0 IGA SIRER hie CIRO A ens Cemces OPE, c S) iy) 2090 11 3 | 2090 11 3 — —____! 1878. | Appropriation of the Government Fund. righ Account of appropriations from the Government Fund of £4,000 made by the Lords of the Committee of Council on Educa- tion, on the recommendation of the Council of the Royal Society. 1878. D. Gill, to defray expenses connected with a Determination of the Solar Parallax by Observation of the Diurnal Parallax of IIUAIRE . oo 0 6 1b 466,08 CHOON CRC IORI? ICE aE Inn IRIN Par Reet ee a, Panne £250 Rey. Dr. Haughton, for aid in the Numerical Reductions of the Tidal Observations made on board the “Discovery” and eeweria in the late Arctic Expedition...........06...6.00. «* 75 J. A. Broun, for continuation of Correction of the Hrrors in the Published Observations of the Colonial Magnetic Obser- fe ee MEE aor SPshcr's Mala! Niorete cise oe sno tc sd" 5 6 6 sss waist s epasle 150 J. P. Joule, for an Exhaustive Enquiry into the Change which takes place in the Freezing and Boiling Points of Mercurial Thermometers by Long Exposure to those Temperatures ...... 200 Professor Jenkin, for Hxperimental Investigations on Friction 50 W. C. Roberts, for Researches on Metals and Alloys in a Molten State passing through Capillary Tubes .............. 25 J. Kerr, for continuation of Hlectro-optic and Magneto-optic Macnee MMMM reread voi als Sco e sc sls a's. a cin ae o H's dhevaie wa Giaieiat scelo. 50 J. N. Lockyer, for continuation of Spectroscopic Researches.. 200 _ Dr. O. J. Lodge, for Investigations into the Effect of Light on the Residual Charge of Dielectrics; on the Conductivity of Hot Glass, and other Transparent Conductors; on Electrolytic Con- Pee UmAMOPOUMe! SMO|CCUS 6.55. ces ye eles eres ere cenes ces 100 Mr. Stevenson, for aid in carrying on Observations of the Temperature of Salmon Rivers in Scotland, and other Meteoro- MMe MO CRVAIOMS. Wlotetec cosas erciwee sees ce seco ec cce ee ve ve 50 W. Galloway, for further Investigation of the Explosive Pro- perties of Mixtures of Firedamp and Coal Dust with Air ...... LOO Sir W. Thomson, for continuation of Tidal Investigation.... 100 Sir W. Thomson, for experiments in Magnetisation of Different Qualities of Iron, Nickel, and Cobalt under varying Stresses and Memiperatures.......... aehiaelotelstalorsr ata’. ste! a ahah ela me cece cna ove 100 J. KH. H. Gordon, for continuation of Experimental Measure- ments of the Specific Inductive Capacity of Dielectrics ........ 100 H. Tomlinson, for Researches on the Alteration of Thermal and Hlectrical Conductivity produced by Magnetism ; and on the CaeriedhOnwarderns cise wicecrele oe 61550 " FS Appropriation of the Government Fund. [Nov. 30, Bronekt forwarder eee £1550 Alteration of Hlectrical Resistance produced in Wires by Sire wel Mi. 1) Le 6 2 ele RS CRG, oeeads clita leks ls 0s Elle eater o fs tec a H. Alleyne Nicholson and R. Htheridge, jun., for aid in ex- amining the Fauna of the Silurian Deposits of the Girvan Dis- trict, Ayrshire, and in publishing a Descriptive List of the same W.K. Parker, for assistance in continuation of Researches on the Morphology of the Vertebrate Skeleton, and the Relations of the Nervous to the Skeletal Structure, chiefly in the Head .. R. McLachlan, for aid towards the expense of publication of a Revision and Synopsis of Huropean Trichoptera .,.......... C. Callaway, for aid in working out the so-called Hruptive Rocks of Shropshire, and in verifying certain points in Local GEOLOGY... sce 6 dois 0s siete eae aOR Sere Obie dah are eee H. T. Stainton, in aid of the Publication Fund of the Zoolo- eical Record Association .))5 +.) 21-13. sso ene ORI ele eee J. W. Dawson, for aid in excavating erect Trees in the Coal Formation of Nova Scotia, in Beds where they are known to conta Reptilian)and other Remams: 2). 52.0 eee eee Professor A. H. Garrod, for aid towards production of the Second Fasciculus of an exhaustive Treatise on the Anatomy of BITS: oo. es stoie fois Kleseoe os Bucdeld ae. helo: sieht apemenoa ete Cele ee eee : Rey. J. F. Blake, for aid in continuing the publication of a Synopsis of British Wossil, Cephalopoda -- <2 )7)-)3) seer ee Dr. W. A. Brailey, for Researches on the Causes determining the Tension of the Globe of the Hye in Man and Animals, and on the Physiological Influence on this Tension of such substances as Atropia, Daturin, Hserim, and Pilocarpine ..............-.. W. Saville Kent, to pay for Microscopical Apparatus for the further Prosecution of Investigations into the Structure and Life-Eistory of certain Wower Protozoa) 3---). 7%). \.-— eee Dr. R. H. Traquair, for aid in preparing and publishing a Monograph on the Carboniferous Ganoid Fishes of Great Britain K. A. Schafer, for payment of an Assistant in continuing his Histological and Embryological Investigations .............. H. Woodward, for continuation of work on the Fossil Crus- tacea, especiaily with reference to the Trilobita and other Hx- tinct Forms, and their publication in the Volumes of the Pa- lgontographical Society <. 06.0. -6 6 sec eae nee Professor Seeley, for an Hxamination of the Structure, Aff- nities, and Classification of the extinct Reptilia and allied Ani- MAIS. 5 doobabueduLodooaed. cyl avn wei wns poispyelelisite le: » ere ciel ener Dr. Wright, for continuation of Researches on certain points 100 70 150 50 100 100 50 05 Carried forward .);) 2225-50 £2875 1878. | Appropriation of the Government Fund. 719 Brought forwand.........-.:- £2875 in Chemical Dynamics; on the determination of Chemical Affi- nity in terms of Electrical Magnitudes; and on some of the less [and Wri AIG HCCI ie A See ne ee Pr s sheet apeeeyass ares rts 300 C. Schorlemmer, for continuation of Researches into (1) the ermal Paratins (2) Suberone (6) Aurin ..........0.-...-- 250 - EK. J. Mills, for a Research on Standard Industrial Curves .. 100 W. N. Hartley, for Investigation of the Fluid Contents of Mineral Cavities ; of the Properties of the Phosphate of Cerium ; of Methods of Estimating the Carbonic Acid in small samples of Pielke LHoLOgraphic Spectra... ..-. . 6.6 oe cence e oe ceen 150 Dr. Armstrong, for continuation of Researches into the Phenol CSTE 2. 0.0 Oe Alo een ee a 250 3925 PmoaMoIairaiive: Hx penses.. u.')oLsi- lee. 2 dee oe esc Sede 7} 80 Report of the Kew Committee. Report of the Kew Committee for the Year ending October 31, 1878. The Kew Committee has had its strength increased during the past year by the accession of two new members, Professor W. G. Adams and Professor G. C. Foster, and is now constituted as follows :— General Sir E. Sabine, K.C.B., Chatman. Mr. De La Rue, Vice-Chairman. | The Earl of Rosse. Prof. W. G. Adams. Mr. R. H. Scott. Capt. Evans, C.B. Lieut.-General W. J. Smythe. Prof. G. C. Foster. Lieut.-General R, Strachey, Mr. F. Galton. C.S8.1. Vice-Adm. Sir G. H. Richards, | Mr. E. Walker. K.C.B. Magnetic Work.—The Magnetographs have been in constant operation throughout the year, but only few magnetic disturbances have been registered, the period being one of almost continued magnetic calm. The most notable perturbation was that of May 15th. The scale values of all the instruments were re-determined in January, in accordance with the usual practice. A shght alteration has been made in the cases enclosing the hori- zontal and vertical force magnets; zinc cylinders with glass covers being substituted for the glass shades lined with gold-leaf previously employed, which were found to be very expensive to replace in case of breakage. The tabulation of the magnetic curves has not been continued during the year, the time of the department being very fully occupied with the verification of magnetic instruments. The Committee have referred the whole subject of the reduction of the accumulated magnetograph records to a Sub-Committee, with a view of considering what steps shall be taken to utilize them to the best advantage. The monthly observations with the absolute instruments have been Report of the Kew Committee. 81 made as usual by Mr. Figg, and the results are given in Tables appended to this Report. The catalogue of the documents and papers in the late Magnetic Office, directed by Sir EH. Sabine, having been completed, a selection was made of all those relating to marine observations, and at the request of the Hydrographer, these were transferred to the Hydro- graphic Department of the Admiralty. The magnetic instruments have been examined and knowledge of their manipulation obtained by Lieutenants Speelman and van Hasselt, of the Dutch Navy; Professor Greene, of the United States Navy; M. Hooreman, of the Brussels Observatory; and Dr. T. EH. Thorpe, F.R.S. The latter gentleman made a series of base observations at Kew before and after an extended tour, for the purpose of a magnetic survey along the fortieth parallel of latitude in the United States. A large magnet and a journeyman clock, the property of the Royal Observatory, Greenwich, which have been for many years at Kew, have been returned to the former establishment at the request of the Astronomer Royal. Information on matters relating to terrestrial magnetism and various data have been supplied to the Hydrographic Office, Mr. Adie, Mr. Archbutt, Mr. Gordon, and Mr. Frost. Meteorological Work.—The several self-recording instruments for the continuous registration respectively of pressure, temperature, humidity, wind (direction and velocity), and rain have been maintained in regular operation under the care of Mr. T. W. Baker, assisted by J. Hillier. The daily standard eye observations, for the control of the automatic records have been made regularly, as well as daily observations in connexion with the Washington synchronous system. The tabulation of the meteorological traces has been regularly carried on by Mr. Hawkesworth, and copies have been transmitted weekly to the Meteorological Office. In compliance with a request made by the Meteorological Council to the Kew Committee, the Observatories at Aberdeen, Armagh. Falmouth, Glasgow, Stonyhurst, and Valencia have been visited and their instruments inspected by Mr. Whipple, who has also inspected the telegraph-reporting and climatological stations throughout Ireland, an allowance has been made by the Meteorological Office to Kew, for the time occupied by Mr. Whipple on this duty. With the sanction of the Meteorological Council, weekly abstracts of the meteorological results have been regularly forwarded to and published by ‘‘ the Times,” ‘“‘ Illustrated London News,” and “Mid- Surrey Times; ’’ and meteorological data have been supplied amongst others to Mr. G. J. Symons, F'.R.S., Dr. Rowland, Mr. Mawley, and the Institute of Mining Engineers. WOR. XXVIUI. G 82 Report of the Kew Committee. Hlectrograph.—This instrument has been in almost continuous action through the year under the care of Mr. Harrison. Certain improve- ments in minor details, suggested by Sir W. Thomson, have been introduced from time to time. It has been thought desirable to make a determination of the scale value of the instrument throughout the whole extent of its range. The Committee not possessing a sufficiently powerful battery for the purpose, the Electrometer was conveyed at Mr. De La Rue’s sugges- tion to his Laboratory, where a complete determination of its scale value was made over the range of tension afforded by 1,200 chloride of silver cells. A detailed account of the experiment was afterwards laid before the Royal Society, and printed in the ‘ Proceedings,” vol. XXVU, p. 356.* At the request of Professor Mascart, a typical set of cnrves, illustrating the action of the Electrograph during different kinds of weather, was reduced and engraved by the Pantagrapn at the Meteorological Office, and forwarded for his use in illustration of the lectures he delivered before the Société Météorologique de France. These engravings have since been reproduced, together with notes respecting the instrument, in a Report on Atmospheric Electricity, drawn up by Professor Everett, for the Permanent Committee of the Vienna Congress, which is about to be published by the authority of the Meteorological Council. The late Captain R. G. Scott, R.E., and since his decease, Captain R. Y. Armstrong, R.E., visited the Observatory and inspected the working of the instrument with the view of possibly utilizing the EHlectro- meter in the study of atmospheric electricity at the various torpedo stations round the coast. Two Electrographs, similar in construction to the instrument at Kew, have been constructed by Mr. White, of Glasgow, and after examination at the Observatory, forwarded, the one to the Brussels Observatory, the other to Zi-ka-Wei, China. Photoheliograph.—The re-examination of the measurements of the Kew sun-pictures, as noticed in former Reports, has been steadily carried on throughout the year by Mr. Whipple, assisted by Mr. M‘Laughlin, who has been temporarily engaged for this purpose. During the year upwards of 400 pictures have been measured, and it is hoped that the end of the series will be reached in the early months of 1879. * With the view of rendering the indications of the instrument better adapted for treatment with the Harmonic Analyser, it is in contemplation to somewhat alter the existing bifilar suspension of the needle, and at the same time to adopt the new insulating stand devised by Professor Mascart (“ Nature,” vol. xviii, p. 44) which will be substituted for the present supports of the water reservoir. These changes may cause a short discontinuity in the observations. Report of the Kew Committee. 85 Mr. Marth is still engaged on the reduction to heliocentric elements of the pictures for 1864 to 1868 inclusive. All of these operations have been conducted under the direction and at the expense of Mr. De La Rue. The eye-observations of the sun, after the method of Hofrath Schwabe, have been made daily, when possible, as described in the Report for 1872, in order for the present to maintain the continuity of the Kew record of sun-spots. EHztra Observations.—The Solar-radiation Thermometers are still observed daily, and a new form of the instrument designed by Pro- fessor G. C. Foster, is at present undergoing trial. The question of observing Solar Radiation having been referred by the Meteorological Council to the Kew Committee, a sub-committee has been appointed to take the whole subject into consideration. The Campbell Sundial described in the 1875 Report, continues in action, and the improved form of the instrument, giving a separate record for every day, of the duration of sunshine, has been regu- larly worked throughout the year and its curves tabulated. A paper comparing the relative amount of sunshine recorded by this instrument dnring the year 1877, with the amount registered at the Royal Observatory, Greenwick, by a similar apparatus, has been read by the Superintendent before the Meteorological Society, and pub- lished in their Quarterly Report, vol. iv, No. 28. It shows that the difference in the total duration of sunshine observed at the two stations, which amounted to 171 hours in the year, was in great mea- sure due to the preponderance of westerly winds, which carry the smoke of the metropolis over the Royal Observatory. A copy of the Kew instrument, constructed by Mr. Browning for the Brussels Observatory, has been compared at the Observatory; and another instrument, with a new form of mounting, designed by Mr. R. J. Lecky, F.R.A.S., is at present being tried. Wind Component Integrator—This instrument, at the time of the last Report, was working temporarily, attached to the Kew Anemo- graph. This arrangement was found, however, to interfere with the regular action of the latter instrument, and accordingly its own cups and vane, sent over by Professor von Oettingen, have been fitted to it by Mr. R. W. Munro; and with the exception of a small period, during which it was under repair (one of the cups having been carried away by a high wind), it has been in good action. A comparison of its indications with those of the ordinary instrument will shortly be made. Photo-nephoscope.—This instrument, designed by Professor Stokes and Wr. F. Galton for the purpose of photographing clouds at the time of their passage across the zenith, has been the subject of experi- ment for some time, with a view of its adoption as a means of trigo- G2 84 Report of the Kew Committee. nometrically determining the height of clouds. The experiments are — still in progress. | Verifications.—-The Committee have to report that the ane of this department of the Observatory is still increasing, and its field ex- tending, the makers who send instruments for examination, from places both at home and abroad, is continually becoming more numerous. The following magnetic instruments have been verified, and had their constants determined :— A set of Magnetographs for the Brussels Observatory. A Unifilar for Messrs. Negretti and Zambra. A Unifilar for the Dutch Arctic Expedition. A Dip-circle A Fox Circle » He An Azimuth Compass _,, Two Azimuth Compasses for Mr. H. M. Stanley. A Dip-circle for the Austro-Hungarian Government. 99 bP) There have also been purchased on commission and verified :—a Unifilar and Dip-circle for the Marine Observatory, San Fernando, Spain; a pair of Dipping-needles for Professor Wild, St. Petersburg ; a Unifilar, Dip-circle, and Fox Circle for Captain Carl Wille, Horten, Norway; a Dip-circle for Senhor Capello, Lisbon Observatory. There are also now undergoing verification a Dip-circle for Lieutenant van Hasselt; a Dip-circle for the Austro-Hungarian Government; a Unifilar, Dip-circle, and Fox Circle for Professor Greene. Two Sextants have been verified. The following meteorological instruments have been verified, this portion of the work being entrusted to Mr. T. W. Baker, assisted by Messrs. Foster, Constable, and Gunter :— Barometers: (Stand ard ey ce oo. eet 56 i Marimeyands Station rey ieee NS Potal...2ts Selene 193 ATSrOid es WSR ee iia hata Apa ane 29 Thermometers, ordinary Meteorological .... 1435 A Boiling-point Standards .... 47 i Moumtarmii gece Gisie einer ereon 16 he Chim calia ze huts (ee ee ee ae 2032 5 Solar cadiationmieye sei) oF eee 65 Report of the Kew Committee. 85 In addition, 134 Thermometers have been tested at the melting- point of mercury. . 14 Standard Thermometers have been calibrated and divided. The following miscellaneous instruments have also been verified :— lslyomoilletGin § 6a dsbnac guBnnoomeDrmo sor ee 356 PARTE MM OUUCL ETE ee erie: ciate Bukketckas » Gievelie eisieicnetars i A Barograph and Thermograph have been examined, and their scale values determined, for the Brussels Observatory ; also a similar pair of instruments for the Zi-ka-Wei Observatory, and a Thermo- graph for the Japanese Government. There are at present in the Observatory undergoing verification, 19 Barometers, 182 Thermometers, 4 Anemometers, and 1 Rain- gauge. A number of Aneroid Barometers, of a new pattern, have been received from MM. Hottinger and Co., of Ziirich, for comparison. ihe “Hall Mark,” figured in last report, has been etched, at the desire of the makers, upon a number of the Thermometers compared at the Observatory. A ITydraulic Press especially constructed for the purpose of sub- jecting Deep sea Thermometers to pressures similar to those they experience when sunk to great depths, has been erected in the work- shop, by Messrs. Hopkinson and Cope. It is capable of exerting a strain equal to 4 tons on the square inch. Several protected Ther- mometers have been found to stand this test successfully. Air’ Thermometer.—Yhe Committee are taking steps to obtain a standard air thermometer. The old ‘Royal Society”? Standard Barometer, with the flint and crown-gilass tubes refilled by Negretti and Zambra, has been compared with the Kew standard daily for several months. Its scale has also been measured and its error determined. Comparison of Standard Barometers.—The account of the com- parison of the Standard Barometers at Greenwich and Kew, which resulted in proving a close agreement between the standards of the two Observatories, was published in the ‘‘ Royal Society Proceed- mess ¢ vol, xXxvil, p. 76. With a view to determine the source of small variations in the correction to the working standard of the Observatory (Newman 34) and the large Welsh’s standards, numerous comparisons have been made between the instruments, from time to time, but as yet without SUCCESS. _ Professor B. Stewart has had similar series of readings made between the Owens College ordinary Standard Barometer and one after the Kew model, also filled by Welsh’s system. The results tend to show a most close agreement between the two forms of instru- 86 Report of the Kew Committee. ment. For a complete account of these experiments, see “‘ Manchester Philosophical Society’s Proceedings,” vol. xvu, No. 10. Freezing Point of Water.—In consequence of a communication from Dr. Guthrie as to the presence of cryohydrates in water lowering its freezing point, a series of experiments was made for determining the melting point of distilled-water ice, rainwater ice, clean pond ice, and the commercial ice used at the Observatory. It was found to be practically identical in all the specimens examined, the differences observed only amounting to a few hundredths of a degree Fahrenheit. Wazed Paper, §c., swpplied— Waxed paper has been supplied to the following Observatories :— Bombay: Montsouris. Brussels. Radcliffe. Coimbra. Zi-Ka-W ei. A supply of chemical and photographic material has also been pro- cured for the Coimbra Observatory. A set of lamps, for use with Maynetographs, has been supplied to the Mauritius Observatory. Loan Evhibition.—The old instruments (with the exception of a Magnet, the property of the Royal Observatory, Greenwich, and a Unifilar Magnetometer) lent to the Science and Art Department, enumerated in the Report for 1876, remain for the present deposited in the galleries at South Kensington. A Dip-cirele, the property of ‘Mr. Dover, has been withdrawn from the collection. Workshop.—The several pieces of Mechanical Apparatus, such as the Whitworth Lathe and the Planing Machine, procured by Grants from either the Government Grant Fund or the Donation Fund, for the use of the Kew Observatory, have been kept in thorough order, and many of them are in constant, and others in occasional use at the Obser- vatory, but the funds of the Committee do not at present allow of the employment of a mechanical assistant, although one is much needed. Iabrary.—During the year the Library has received, as presents, the publications of 11 English Scientific Societies and Institutions, 43 Foreign and Colonial Scientific Societies and Institutions. Ventilation Hxperiments.—The Sanitary Institute of Great Britain having applied to the Committee for permission to use the experi- mental house (which was unoccupied at the time) for a series -of experiments on the ventilating powers of cowls of different form, the Committee granted it, and a large number of observations were made by them, extending over several weeks. A second set, with other appliances, is now about to be instituted. Report of the Kew Committee. 87 Observatory and Girrownds.—The buildings and grounds have been kept in repair, and application has been made to Her Majesty’s Com- missioners of Woods and Forests for a repainting of the interior, six years having elapsed since it was last done. The Committee have received, as a donation, from Commander Sebastian Gassiot, R.N., busts of his father, the late J. P. Gassiot, Esq., and General Sir H. Sabine. The Experimental House and Magnetic Observatory have been painted externally. 3 Staf.—The Staff employed at Kew is as follows:—Mr. G. M. Whipple, B.Sc., Superintendent; T. W. Baker, First Assistant ; J. Foster, J. W. Hawkesworth, H. M‘Langhlin, F. G. Figg, R. W. F. Harrison, E. G. Constable, T. Gunter, J. Hillier, and J. Dawson. Mr. C. Robinson resigned his appointment in March, and was suc- ceeded by Mr. Hillier. Visitors.— The Observatory has been honoured by the presence, amongst others, of :— Mr. Blanford. Mr. Chambers. The Chinese Educational Mission. Captain De La Haye. Professor Everett. Mons. Houzeaa. The Hydrographer of the Japanese Navy. Lieutenant-General Sir J. H. Lefroy. Professor E. Mascart, Directeur du Bureau Central Météoro- logique, Paris. Captain von Obermayer. Dr. Wijkander. (Signed ) Warren De La Rug, Vice-Chairman. heport of the Kew Committee. CO BD my 09 © co N N “UTddIHM ‘N° = (poustg) ae “LopnK ‘LLOOS “H LYATOW Feb errr sor eee rarecereccooresece + veo si veareeven ves doueleq POO rer eee eccreercc cece tooseeses Jadeg pox pur ‘sTeorurayo ‘snqvieddy Peer eeneeerescescvneooceeveseey os Poorreccosccvceve SAILLITIAVIT (peusis) I 81 6662F L Gil CO) ———— = wy ~ in = co oD ook HO © “Dp °s O71 bp & LI Fl 0 0 08 G GT Geo eee eee ee ee ee ey puey ul seo se eee tee cccvoncen yurg Ayunoy pue uopuoT Scere reo-sseenece- +e ee o- ss eeessceccsseeen ae 66 66 8 ILZ SJUstULedxy Loy syusUIN.AYsUT 6 Sl 6 ~ Ulelig yaiH Jo aynqysuy Lrejtuvs Jo Jreyoq uo sasuedxy SOOOUOCOOROOOUSCOOMOAEAnTTE aan CER Y tach a Cay tea yom-ung i ® CQ te 9 Pot - Cee cree rcereree seseesccaseeeresce solipung pue YOM S,layuadieg 8 6 L 9 § 0141p jo ueday Soccer reerescce sJUIUIN.AISUT be 66 sjooys ydeisomouy * sf SV) PlOV-oluoqivg pu sop = of saqny-lajowoulleyy, * hs GL atte cette esc cee cee sesesereeree eet nee s[eorUayO 66 66 ee ee a O_ONNIP aulypouquioded paxe(\ Jo asvyomg rere" QO [BIGOLOLOI}aI JO Jyeyaq uo sjuswmAeg pue soseisog PPO roe res eecesecee sesercsvcccccsee- UOISSIULUIOD uo poseyomnd $]U9UIN.A4SUT Cot Oey wae ree ree reeesssenses (eee os cesccesee crcceses isislolalslarefastale erefciefetslerceisiere lentes sofouesuTyu0)g pue 99¥19}.10 Jadooyasnoyy] puv 1osuassayy Pig ogee a See lea cose ence unilenent cena Crear sosvqsog Aouoteyg pus Sunuwg & LI 0& 0 Fr Lg 6 € &I O- ® i01 6 0 LF Oe Ot ee eee eee ree ee ree Coen cence tee ce eee e eee ce sree scecsecccccecce COB e re eee eo eeeroe eee reeeed reorsseveseensceser sen ese ee SS gee eh escees bees er eee toes onT pue SUulUIvg PO = COO ee eee reserve eesesescoerse ‘OR ‘Aro[puryg “ sSuIyIly puw aiming bie ere eases oy ue oNT puey jo quay ¢ 8I cg 9 FI ZI Oly sgt G 9 g9 00 TR ee ere i iy eoorce qUNOd..V esnoy pue ‘jong ‘svg oy yUe_ JoIsurTUysay, puke UopuoT—aourleg YOM ViZXe pue soweresg fq “SL8L PL aquiaaogr mHODONCONMS “ps *J091.09 Puno puv ‘sayONOA OY} YIM patedwmoo pure paururexy ——____ POOR eOe So roar Oe ooD ETE H OO BED haven eet aecserose ULRILI Jvaty JO anyysuy AvejTUEG ae a a a cee aa ce mio an y04s UL 66 +6 Sees ah ese os aay eMOOIIOU DLE DUIS Pee teres eonp aaa TOW EaGnont Pete ee eee Meee er a ece ne eeeesesseese Source ean cee tetensene -eseeecse yoo1s Ur 66 66 BeOS BO REEOS COT YTaTS Jodeg Pax A, EPO SEE CED ERR SEDATE GRITS Pies cee gees Sas’ sree SOLID UTS puv soournolry ‘S00 [Bordo o.Loajayy ew ecese ceo Poo O ee eas eesceseers oeteeen oF Cee ees cee cer ses ceere-scerccoce= ‘SILASSV "8181 ‘EL Laquiaaogr IT 81 666¢F oaoct cI COO rere Drea sessed rere Oooo eesedOHSEDO0D. 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Magnetic Observations made at the Kew Observatory, Lat. 51° 28' 6" N., Long. 0° 1™ 15%1 W., for the year October 1877 to September 1878. The observations of Deflection and Vibration given in the annexed Tables were all made with the Collimator Magnet marked K C 1, and the Kew 9-inch Unifilar Magnetometer by Jones. The Declination observations have also been made with the same Magnetometer, Collimator Magnet N E being employed for the purpose. The Dip observations were made with Dip-circle No. 33, the needles 1 and 2 only being used; these are 34 inches in length. The results of fie Bieerrations of Deflection and cane give the values of the Horizontal Force, which, being combined with the Dip observations, furnish the Vertical and Total Forces. These are expressed in both English and metrical scales—the unit in the first being one foot, one second of mean solar time, and one grain; and in the other one millimetre, one second of time, and one milligramme, the factor for reducing the English to metric values being 0°46108. By request, the corresponding values in C.G.S. measure are also given. The value of log 7*K employed in the reduction is 1°64365 at tem- perature 60° F. The induction-coefficient uw is 0:000194. The correction of the magnetic power for temperature ¢, to an adopted standard temperature of 55° F. is 0:0001194(¢,—35) + 0:000,000,213(¢,—35)’. The true distances between the centres of the deflecting and deflected magnets, when the former is placed at the divisions of the deflection- bar marked 1:0 foot and 1°3 feet, are 1000075 feet and 1°300997 feet respectively. The times of vibration given in the Table are each derived from the mean of 12 or 14 observations of the time occupied by the magnet in making 100 vibrations, corrections being applied for the torsion-force of the suspension-thread subsequently. No corrections have been made for rate of chronometer or arc of ale these being always very small. he value of the constant P, employed in the formula of reduction ="(1-= =i 2000179. a each Picetiiide of absolute Declination the instrumental read- ings have been referred to marks made upon the stone obelisk erected about a quarter of a mile north of the Observatory as a meridian mark, the orientation of which, with respect to the Magnetometer, was de- termined by the late Mr. Welsh, and has since been carefully verified. The observations have all been made and reduced by Mr. F. G. Figg. 90 Report of the Kew Committee. Observations of Deflection for Absolute Measure of Horizontal Force. Distances m 5 of Tempe- | Observed | Log —. | & Month. GoM. T: Centres of | rature. | Deflection. =e g Magnets. Mean. 5 Sie Gli. Jn, shale foot. . Be pinns October vss. 25. 26 12 34P.M. 1:0 Bis) °F) 5 388 6 F. 13 ose | Uf 3. 8 : hy Daaeie 1-0 58°8 | 15.387 3 |) Sosa 13 ae 7 2 42 November...... OW) MW BAL Te Ni. 1:0 54°6 15 37 46 FE 13 wrk Ss |. : | 218 , 1-0 55:3 | 15 37 26 |) oa 13 aa. 7 245 - [sbecembert 224) 2ilet2 obese amt ( 43-6 | 15 88 37 F 13 wee Fie ee. 2/30. + 1-0 454 +| 15 88 4 |" aoe cere 13 eps! ES J amunry-e/.4otot 28 12), Ailes ae) |i @ 45°3 | 15 39 26 F 13 ie | ona : De | a0 43°6 ‘| 1 3028 | oo ee 13 ei i 7 2 | February ....-.| 26 12 16P.u 1:0 D079) de 3726 F | 1:3 ee yi 2 47 e ¢ b] | IB) if Ta) 52°7 | 15 37 14 |) toe | 13 apa B23 >, | March Woon cede) BF 12 1922, 10 46°6 | 15 39 24 F { 1b3} cee UL 3 45 : 5 | QO 1-0 52-2 | 15 37 65)/- oo | 13 ink a pe DBA . | Ae enc ceseey) 20 12 aaah Teo Gey PLS 63 62 F 13 Ae 7 Oo 1) ) OR 1-0 62-7 | 15 35 fog eee 13 toe AONB f Maye pietecittel Ht, ota bo ORE ENE: 1:0 66°8 | 15 34 23 F | 13 ide (al Sa |. Dae | 1-0 68-2 | 15 34 19 |7eceeiam | 13 Me jee i ISHS os enceco os 28 12 Aare) tO 87°4 | 15 31 55 F 13 es OG |. : 2 3000 1-0 go°7 145 31 2 13 in 6 59 52 - | uly .......4..] 2912 429.0) 10 72°8 | 15 34 7 F | QTE lies 1:0 725 | 15 23 26 ‘ | 13 ae Ns 5 August ........| 2812 27pm] 1:0 71-3 | 15 33 52 F 13 hie 7 1105002 239 , 1-0 70-6 | 15 23 1610 oe 13 Aa ete 2 i September......| 24 12 33P.mM 1:0 7/915) 15 36) F 12 ae 7 21616 aya DET 1:0 60-1 | 15 34 47 sf 13 be 7 142 : Report of the Kew Committee. 91 Vibration Observations for Absolute Measure of Horizontal Force. Time of f Month. Gene 8) eee | one van (ee | ele rature bes Mean. of m. ration. oe | 1877. aeph.; mM: F secs, | Oeropeee es... | 26 LL 52 4.m. 542 46353 | 3 14P.mM. 611 4°6356 | 0°31152 | 0°52661 | | November........| 2711 45a.m. | 535 | 4°6328 | 2 58 P.M. a49 4°6331 | 031187 | 0°52673 | | Wevember........| 21.11 544.m. 42°0 46266 0 46286 | 0°31224 | 052672 1878. | January..........| 28 12 QOnoon| 44°5 46290 | 3 9pm.| 440 | 46308 |0:31182 | 0:32674 | . > > > > xy "Observer. 2 49 P.M. 52°4 46316 | 0°31200 | 0°52657 | rx} | Hebruary ........| 26 11 37a.m. | 49°7 | 46305 Mareh>.:........| 27 11 3lam.| 443 | 46331 3 4pM.| 547 | 46338 | 031133 |0-52645 | pets. -..:| 2¢ 11 2Zlam. | 6C°7 46365 | eB 3 2P.M. 65°4 4°6366 | 0°31166 | 0°52630 | ,, aoe 27 11 53 a4.M. 65:4 46383 | F. iy 3 13P.M. 70°1 4°6381 |0°31188 | 0°52636 | ,, Din 5. 26 11 56a.m.| 881 | 4°6454. | F. | | 3 15p.m.| 902 | 46454 |0:31195 |0°52650 |_,, Minky .......-..|29 11 57axc.| 73-6 | 46418 F. 3 17p.m.| 73:0 | 46398 |0-31175 | 052637 |_,, | August ..........| 28 11 454.m.| 71:3 | 46407 F. | 315pm.| 71:0 | 46385 |0-31184 |0:52627 | ,, | September........ 24 11 52a.M. | 56:2 46361 . de 3 11 P.M. 61°4 46340 | 0°31188 | 0°52631 | _,, 32 Month. Noy. 1878. Jan. Feb. Mar. G. M. T. Ganhe em: 293 8P.M MO Mean 28 2 56P.M BBM gp 30 2 49 ,, 2 48 ,, Mean 20 2 55P.M 5) yal BAZ DO! f. PA. Pk, 1 Mean 2902) 55 PAM. iy SB) 30) 2 193) he Zod 5, Mean 27.2, 5O Pint Oy Gls) 3 LS) SO. 55 Si Oe, Mean. . 28 2 54P.M. iO See 29 2 57 ,, 2°57 4; Report of the Kew Committee. Dip Observations. = aS) North. 67 45-97 45°19 67 45°58 67 44°31 44°16 44075 44°09 bor bo oe wrewre eee if 2 1 2 1 2 1 2 NMiea nie alec .| 67 44°33 67 44°87 44°06 44°87 44°06 | 67 44-46 67 45:12 44°19 44°81 44°50 | 67 44:65 67 44°75 43°50 45°12 44°31 | 67 44-42 67 44-69 43°94, 44°68 43°81 67 44°28 | Observer. Mean..|.... = G. M. T fe) = 1S78s da, h. mm. Apl. | 293 4PM Sikes, S40) 8) AS) 3) 2 gp Mean May | 293 7PM Sun) Liew, 3003 Our. 32a Mean. i dune 27/93) LO) pie BYTE «Sp ZSESy vee Sik OMe. Mean | July |303 6PM By | SILTY zh. 3 9 5, Mean | Aug. | 29 3 15 P.M. Selanne 30 Pomona oplome | Sept.| 25 3 2PM. 3 We, 26401 OMe: Syolae | Mean.. eee .| 67 4410 67 43°81 44:06 © 44-68 44°12 67 4417 67 42°12 41°37 43°81 41°81 .| 67 42°28 67 43:06 41°32 44°00 43°00 .| 67 42°84 67 43°68 43°00 43°31 43°18 67 43°29 67 43°53 43°43 43°75 43°81 67 43°63 | Observer. | a 29 Report of the Kew Committee. 93 Declination Observations. Uncorrected. Corrected for Torsion. | 2 | Month. | G.M.'. pea Observa- | Monthly | Observa- | Monthly | 2 | tion. Mean. tion. Mean. Oo eS West. West. West. West. | S77. ay hm: Res NS 87 A ie | October ....} 29 12 34p.m.] 19 18 56 19 18 56 Ine 30 12 33 ,, | 19 20 28 | 19 19 42 | 19 20 28 | 19 19 42! , | November ..| 28 12 27 ,, | 19 15 52 19 17 58 [ee | PAZ 34. %, 116 482) 19 16-20 | 1916-48.) 1947 20 i, Werembper ..| 22 12 35 ,, | 19 15 21 19 16 32 | F. Za t2 290" | 19 16 50) 19 16.5 | 19 16-50 | 19.16 41 |. 1878. January....| 29 12 22 ,, | 19 16 40 19 16 40 gl fe S0ni2 st | TOr13.25 1 1945 2 |) 19 F445 | 19 15 49) | Pebruary. ..| 27 12 28 ,, | 19 21 20 19 18 50 F. | 28.12 40 ,, | 19 17 23] 19 19 21 | 19 16 33 | 19 17 41), March ..:.. 28 12 30 ,, 19.11 33 19 18 29 F. Oe O | eho 7 ae 19) 1434) 11915 39 | 19 1434: ee | Peer. . | 20 12 29) ,, | 19°13 47 19 10 59 F. | 30 12/86) ,,.| 19 1425 | 19 14 6 | 1917 12/19 14 5 | ,, i) 2902130) 13, 19 12. 9 ED 1AS°36 ine 30 12 42 ,, | 19 17 46] 19 14 57 | 19 17.46 | 19 15 41 | ,, | mewn. | 27 12 30° .,, | 19 15 10 LOR fe ot 1D) 28) 12 35 |,; TOE GO (8s | 19) 20) 53" | 19) 19 22a Duly, cece « 30 12 19 ,, | 19 12 52 19 12 18 F. SZ Om MOM soo LO TSsetoo | TO oes 9) Lana Ms August..... 29 12 33 ,, 19 17 44 19 15 59 ine 3112 40 ,, | 1912 9] 19 1456/19 13 53 | 19 14 56] ,, September..| 25 12 27 ,, | 19 9 50 19 12 10 F. | 26) 12723) 19 138384019 teat 19) 13)33 | 1912 St J+ Month. 1877. October .. | | November | December 1878. | January.. February . | | March ... ' August... September] 3°8962 | | .| 38958 Report of the Kew Committee. Maenetic Intensity. English Units. | Metric Units. Y, or Ver- | Total |! zontal | tical | Force. | | Force. 5 or | | , Force. | | 9°5148 |10°2795 3°8930 9°5104. | | 3°8963 | 9°5196 10°2861 | 3-8923 9°5113 10-2771 3:8953 | 9:5168 | | | 3:8902 | | | | | 9°5032 | 3:8943 10-2783 9°5161 |10°2828 3°8953 | 9°4999 |10°2676 | 3:8946 | 9°5025 [10-2698 88961, 9°5128 |10°2797 10°2764 10-2830 | | | 10-2686 | 9 5098 |10°2768 | X, or Hori- Ver- zoutal | tical Force. | Force. Y, or 1:7939 | 4:3871 | 1:7950| 4°3851 43893 | 43855 43880 1:7937| 4:3818 | 4° 1°7956| 4°3857 | || 1:7963 | 4°3877 1:7961| 4°3803 43815 1:7964.| 4°3848 17965 | 4°3862 | 4°7398 C G. S. Measure. Y, or Ver- tical Force. 0°4387 0°4385 0°4389 0°4385 i) = ~I No) On 0:4388 | 0:1794| 0-4382 | 01796 | 0°1796| 0-4388 | 0°1796| 04380 0:4381 0°4385 0°1796 | 0°4386 Total | Foree. | *[OAO]-BOs OF poonpodl soulpwoy *puUNOLS YY OAOGL 4OOF OT OLV sqTNG-LoJOULOLUAOY OUT, x S ‘[IOUNOL) [BOLGOTO.10040 JV, eyy jo uoisstutted sq ‘ooyjy) [VOLSO[OAOO{oPW OY] JO qaodoyy AoyQVvo AA ATALOJAVNY) oY4 UOAT pozoLayxXO SI oTqey, OAOG” OTT, | 199.62] LOE: | os ie . | ee PGC Cs eat “ ae ¢.0S OE ei el AS ese ee Ce a = wie | ee ee eee 129-62| PLE. || S966 | ‘Wag EZ | 6OE-0E|Mooud G | c6666 | OLE ao} Waal Gv ye €.9¢ | * toquroydog Z1¢-.66| APY. || FST-66 | HVO O€ | €48.0€) NVT T | 694-66 || 6.19 We (OG. |- IeZZ meses Gog |°'** ysneny 809.62| Sep || 799-60 | “ PF Pe | ELeoe/aprmto Te \96008 | Lay | “ & V | B18 | ° @ 6L| Leg | “fur : 6VS-66 | P6E- || SSV-66 fe Py IL | 4b¢.0€| ~ 119 | 876-62 || O-FP Gre C 9.58 Se Ole Sap). |e 9 Po Gili Y ¢ ip \ aS LYE 6Z| LVE- 200-62 4 ee hae 99T-0 | ‘NV OT O€ | P6L-66 || 168 | -“ b 16) 614 PE OU OSHS BRIE © St ae AN = 213-62 | 998: || 6E1-6Z “ @ TL | pez.og Gea 888.62 0-62 Or Pik 9.19 “IT O08 | ¥-8P - ee qty = piace ) ' 66 ee eo ® -S TL48-62| POG. |) 841-66 | NVG 66 | 999.06 Le a 91} 40-0 G16 “ 4h 9%} 1-48 py 4 8-6V ore yn _ LF0-0€| 8&z- || 6c9.62 | Was Zz | sc9.0e] “ T 2 |eszog || 6$¢ | wv6 g | gzg | “-@ LT | Gap | °° Aconsqog aS OC6i6e | Zz: 9/€.6Z Gee g | cO4. Oct = Olecl a One P.92 | ‘Nd OL IL 1494 ss : ae } s.or "+ IVnURP “BIST ES 1Z8-66 | G6: 8El-66 | NVG TL 169:08| “ 6 0% | ¥P0.08 6-46 eh: SG |= G:SGe |W da CeO OTP | tequieoe dg meabrcvoa|) coc. | Si4ec | il it | Py oe) 1 ZL 68oce || OGe | FY Y | OSS) | wv Th Ol | oey | 2 uequekoN ee 8PL.66} 6246- GIG-66 | WdZG CG} O$9-08| WVY8 9 |220-06 | 0-66 | NVS 8ST} 069 |"WdT WI G-8p | °°" 40G0}O “LAST ) ‘soyour | “Your |) ‘soyour ‘Y “p | ‘seyout BU aaa} “SOUOUL | 2 “wp 0) ‘ op 0) = = “IG | UOTSUOY |} = “LR mou @ | midere § ‘aqeq i] “LOU, O4Vq “HOUT, menu @ | v kag, |-anodv 4! 2 "SUBOTA | eco RS | “UMUTUTUL OULOLYXGT | “TUNTUTXVUT OULOI}XTT TWUNUIULUL OWOAGX A | “UUNTHIXVTU O09 x “StPUOTAL “SUvOTT | | \ “LOJVIUUOLV i y, LIJOULOULLOT ‘oanssorg | EES IEE 4 IND | “Q/QT ‘L409 teqmojdeg SuIpUS STYUOPY OA[OAT, OY} LOJ SpAOOOY SNOVUIQUOD OY TOA SqPNsoa ATT QUOT UBOTW "JOOF PE JOAOP-COS OACQL FYSIOPT “N ,,9 8% o1G OPUMIT “MM TST mT yO Opnzouory “£10JVALOSYQ, MOTT ‘T 2QeJ—'suoyeVArasqd [VOLd0[0.10049 WT IE XIGNWddV | _—E eee Report of the Kew Committee. 96 ‘Wd OT pue at 7 td Tto0u “W'y OL 78 Spel SUOTZVALOSGO ULOAT poatsod f. ‘ydersomous oyy Aq posoistsor sy f &V 6¢ FOE = SV, IT 66 O& && | SST 9 6 OL il = I if G 9 i 4 Tbs g I 9 $ x wae g 9 & L 5, g 9 Si &1 I G él G € V 4 G OL I g él 4 I V G G ST I G i) g T 6 & € Gl 8 4 v IL - G & 9 lt G q 8 g G & T G ZT Sg 9 Z 6 if G & 14 IL L L 8 V I T = 6 TAL v G IT IT q = T ae 6 G 4 GL V ae G 6 V OL Ars : ate sae : ; : 4880 ANNIE | ANS] BINS 8 a's Cl HN N || -1019 AOTC J YOM uo sup Jo soquanyy “tf purAy 9T 1G Z So T 9 G § G 9 a p I G Z na e oe e Me *SULIOJS “AYs a aS) ES) “UNIT, jo skup jo roquinyy *4 tayyve M “MOUG ‘L10}VALIS() AOS] (12), 5(22) .... 3(n2) the distancesvoi\ Pio, Ps, ¢ ) eee the axis of B., and so on. In practice the mounting of the pulleys are to be adjustable by proper geometrical slides, to allow any prescribed positive or negative value to be given to each of the quantities (11), (12), . . . (21), &e. Suppose this to be done, and each of the bodies B,, B,, . . . By, to be placed in its zero position and held there. Attach now the cords firmly to the fixed points D,, D., . . . Dz respectively; and passing them round their proper pulleys, bring them to the other fixed points Ki, HE, . . . H,, and pass them through infinitely small smooth rings fixed at these points. Now hold the bodies B,, B,, . .. each fixed, and (in practice by weights hung on their ends, outside Ei, Hy, .. . E,) pull the cords through H,, H,, . . . H, with any given tensions* Ti, T:, +. . Ty. ~luet Gy, Ga... G, be moments round thesieed axes of B,, B,, . .. B, of the forces required to hold the bodies fixed when acted on by the cords thus stretched. The principle of ‘ virtual velocities,’ just as it came from Lagrange (or the principle of “‘ work’), gives immediately, im virtue of (1), Gi=— Geel. a. 4 Cla, G.=(12)T14+ (22)To+ ... +(12)Tr (a ~~ G,=An)Tit+(2n)Tet . «.. + (tn) Tn Apply and keep applied to each of the bodies, B,, B, . . .B, Gn practice by the weights of the pulleys, and by counter-pulling springs), such forces as shall have for their moments the values Gi, G. . . . Ga, calculated from equations (II) with whatever values seem desirable for. the tensions T;, T, ...Tn. (In practice, the straight parts of the cords are to be approximately vertical, and the bodies B,, B., are to be each balanced on its axis when the pulleys belonging to it are * The idea of force here first introduced is not essential, indeed is not technically admissible to the purely kinematic and algebraic part of the subject proposed. But it is not merely an ideal kinematic construction of the algebraic problem that is in- tended ; and the design of a kinematic machine, for success in practice, essentially involves dynamical considerations. In the present case some of the most important of the purely algebraic questions concerned are very interestingly illustrated by these dynamical considerations. 1378. | Solution of Simultaneous Linear Equations. 113 removed, and it is advisable to make the tensions each equal to half the weight of one of the pulleys with its adjustable frame.) The machine is now ready for use. To use it, pull the cords simultaneously or successively till lengths equal to é:, é, . . . @, are passed through the rings H,, Eo, . . . Hn, respectively. The pulls required to do this may be positive or negative; in practice, they will be infinitesimal, downward or upward pressures applied by hand to the stretching weights which (§) remain perma- nently hanging on the cords. Observe the angles through which the bodies B,, B., ... B, are turned by this given movement of the cords. These angles are the required values of the unknown %, %, . . . a, satisfying the simul- taneous equations (1). The actual construction of a practically useful machine for calculat- ing aS many as eight or ten or more of unknowns from the same number of linear equations does not promise to be either difficult or over-elaborate. A fair approximation being found by a first applica- tion of the machine, a very moderate amount of straightforward arithmetical work (aided very advantageously by Crelle’s multiplica- tion tables) suffices to calculate the residual errors, and allow the machines (with the setting of the pulleys unchanged) to be re-applied to caleulate the corrections (which may be treated decimally, for con- venience): thus, 100 times the amount of the correction on each of the original unknowns, to be made the new unknowns, if the maegni- tudes thus falling to be dealt with are convenient for the machine. There is, of course, no limit to the accuracy thus obtainable by suc- cessive approximations. ‘The exceeding easiness of each application of the machine promises well for its real usefulness, whether for cases in which a single application suffices, or for others in which the requisite accuracy is reached after two, three, or more of successive approxima- tions. December 12, 1878. W. SPOTTISWOODEH, M.A., D.C.L., President, in the Chair. Dr. Philipp Hermann Sprengel was admitted into the Society. The Presents received were laid on the table, and thanks ordered for them. The following Papers were read :— 114 Prof. J. Thomson on the Flow of Water in [Dec. 12, T. “On the Flow of Water in Uniform Régime in Rivers and other Open Channels.” By James THomson, LL.D., D.Sc., F.R.S., and F.R.S.E., Professor of Civil Engineering and Mechanics in the University of Glasgow. Received Au- gust 15, 1878. In respect to the mode of flow of water in rivers, a supposition which has been very perplexing in attempts to form a rational theory for its explanation, has during many years past, during at least a great part of the present century, been put forward as a result from experi- mental observations on the flow of water in various rivers, and in artificially constructed channels. It was, I presume, put forward in the earlier times only as a vague and doubtful supposition; but, in later times it has, in virtue of more numerous and more elaborately conducted experimental observations, advanced to the rank of a. con- firmed supposition, or even of an experimentally established fact. This experimentally derived and gradually growing supposition was perplexing, because it was in conflict with a very generally adopted theory of the flow of water in rivers which appeared to be well founded and well reasoned out. . That commonly received theory, which for brevity we may call the laminar theory, was one in which the frictional resistance applied by the bottom or bed of the river against the forward motion of the water was recognized as the main or the only important drag hinder- ing the water, in its downhill course under the influence of gravity, from advancing with a continually increasing velocity ; and in which it was assumed that if the entire current is imagined as divided into numerous layers approximately horizontal across the stream, or else trough-shaped so as to have a general conformity with the bed of the river, each of these layers should be imagined as flowing forward quicker than the one next below it, with such a differential motion as would generate through fluid friction or viscosity, or perhaps jointly with that, also through some slight commingling of the waters of con- tiguous layers, the tangential drag which would just suffice to prevent further acceleration of any layer relatively to the one next below it. Under this prevailing view it came to be supposed that for points at various depths along any vertical line imagined as extending from the surface of a river to the bottom, the velocity of the water passing that line would diminish for every portion of the descent from the surface to the bottom. The experimentally derived and perplexing supposition for which no tenable theory appears to have been proposed, though the want of such a theory has been extensively felt as leaving the science of the flow of water in rivers in a state of general bewilderment, 1s, that inconsistently with the imagination of the water’s motion conceived 1878.] Uniform Régime in Rivers and other Open Channels. 115 under the laminar theory, the forward velocity of the water in rivers is, in actual fact, sometimes or usually not greatest at the surface with gradual abatement from the surface to the bottom; but that when the different forward velocities are compared which are met with at suc- cessive points along a vertical line traversing the water from the surface to the bottom, it may often be found that the velocity increases with descent from the surface downwards through some part of the whole depth, until a place of maximum velocity is reached, beyond which the velocity diminishes with further descent towards the resist- ing bottom. That the superficial stratum of water flowing downhill under the influence of the earth’s attraction should not have its forward velocity continually accelerated until, by its moving quicker than the bed of water on which it lies, a frictional drag would be communicated to 1+ from below, by that supporting bed of water, sufficient to hold it back against further acceleration, has appeared very paradoxical. In various cases, during a long period of time, the alleged result appeared so incredible that the experimental evidence was doubted, or was dis- missed as untrustworthy. In some cases the phenomenon was admitted as a fact, but was attributed to a frictional drag or resist- ance applied to the surface of the water by the superincumbent air, even in case of the air being at rest with the water flowing below, or more strongly so when the wind might be blowing contrary to the motion of the river. Omitting to touch on the experimental results, and the opinions of various investigators in the older times, as | have not had sufficient opportunity to scrutinise them in detail, I have to refer to the investi- gations conducted at about the year 1850 by Hllet on the Mississippi and Ohio Rivers.* He was led to the conclusion} from his own expe- riments on the Mississippi, that the mean velocity of that river (or at least the mean velocity of the great body of its current, as the part near the bottom or bed of the river had not been definitely included in his researches) instead of being less, is in fact greater than the mean surface velocity. He attributed this phenomenon, which he regarded as indubitably proved, and which if true must certainly be very remarkable, to a frictional drag or resistance, against the forward motion, applied to the surface of the water by the atmosphere in contact with the surface. Like suppositions had previously been made by some observers and theoretical investigators in Europe, as may be gathered from D’Aubuisson “ Traité d’Hydraulique,” 2nd edition, 1840, p. 176, and from other sources of information. * Ellet on the “ Mississippi and Ohio Rivers.” Philadelphia: 1853. This is a republished edition of a Report to the American War Department by Ellet on his investigations, which were made under authority of an Act of Congress. + Pages 37 and 38 of the book referred to in the preceding note. 116 Prof. J. Thomson on the Flow of Water in [Dec. 12. Other experimental researches on the flow of the Mississippi River, much more elaborate than those of Ellet, were made in the period between 1850 and 1861 by Captain Humphreys and Lieutenant Abbot, with others acting under authority from the American Government, and an account of them was published as a Report by Humphreys and Abbot in 1861.* These experiments and the investigations exhi- bited in the report, where the observed results are combined in various ways so as to bring out average results and more or less probable con- clusions for various circumstances, lead very clearly and very con- vincingly to the conclusion that ordinarily the maximum velocity is not at the surface but at some depth below it, usually much nearer to the surface than to the bottom, and often at some such depth from the surface as ¢ or 4 of the whole depth of the water. These investigators (Humphreys and Abbot) show further (at pages 285, 288, and 289 of their Report) that this phenomenon is not wholly nor even mainly due to any frictional resistance applied by the superincumbent atmosphere to the forward flow of the surface of the water; because they found that even when the wind is blowing in the direction of the river current, and advancing at the same velocity as that current, so that the air lies on the surface of the water without relative motion, the phenomenon manifests itself almost in as great a degree as when the air is lying at rest relatively to the land; and found yet further that the phenomenon still manifests itself even when the wind is blowing in the direction of the flow of the river much faster than the current, so that it blows the water surface forward instead of applying a resisting drag or backward force to the surface. At about the middle of the present century very important experi- ments on flowing water were made in France by Boileau, and by Darcy and Bazin; and elaborate accounts of these researches were published.+ The experiments comprised among the researches of Boileau and of Darcy and Bazin, to which I have to refer as bearing on the special subject of the present paper, relate to the flow of water in long channels and conduits constructed artificially, some in wood and some in ma- sonry and other materials. The channels or conduits in different cases were of widths comprised between half a metre and two metres. In some of the more important experiments the channels were con- * Report on the “ Physics and Hydraulics of the Mississippi River.” By Captain A. A. Humphreys and Lieutenant H. L. Abbot. Philadelphia: 1861. + Boileau: ‘‘'Traité de la mesure des eaux courantes.”’ Paris: 1854. Darcy : ‘‘ Re- cherches experimentales relatives au mouvement de l’eau dans les tuyaux.” Paris : 1857. Darey et Bazin: “ Recherches Hydrauliques.” Paris: 1865. This last book con- stitutes a memoir by Bazin on researches commenced by Darcy, and continued for some time by him with the aid of Bazin; and, after the death of Darcy in 1858, continued by Bazin, and by him completed and worked out in the discussion of their results. 1878.] Uniform Régime in Rivers and other Open Channels. 117 structed in wood, and were open above, and had a flat bottom and vertical sides, so that the current was rectangular in cross-section. Channels of various other forms were also used, and the mode of flow of the water in them was scrutinized. The results arrived at by these experimenters tend very much towards establishing the supposition which forms the subject of the present paper—the supposition namely of the prevalence or frequent occurrence of a distribution of velocities having the maximum velocity not at the surface but at some moderate depth below. Boileau, by his experiments, was led to announce as one of his conclusions (page 308), that in the medial longitudinal ver- tical section of a rectangular canal with uniform régime, the maximum of velocity is situated not at the surface, but at a depth which isa fraction more or less considerable of the total depth of the current. He also announced, as a conclusion, that the decrease of velocity, from the place of maximum velocity up to the surface, must be attributed to some new cause different from that which produces the diminution of velocity from the place of maximum down to the bottom. This new cause, he says, cannot be solely the resistance of the bed of air in contact with the liquid surface acting like the face of a pipe or con- duit ; and he assigns, in proof of this, the reason that the mobility of this bed of air does not permit of our attributing to it a retarding in- fluence so great as that which is implied in the rapid abatement of velocities in approach towards the surface in the upper part of the current. He recounts his own special experiments, made in 1845, on the influence of wind on the velocities in currents,—a subject which he says had up to that time been very little investigated by hydran- licians. He deduces from his experiments conclusions (page 313) to the effect that in spite of varied disturbances produced by wind blowing over the water with varied intensity, yet there is manifested a very sensible tendency to a decrease of velocities of the water for approach towards the liquid surface ; and that the maximum velocity is yet below the surface, even when the wind blows forward with the current, and has a velocity greater than that of the current. Judging, then, that resistance of the air cannot be the cause of the phenomenon, he says that it is then principally in the mutual actions which bind among one another the liquid particles, and in the oblique and rotatory movements which result, under the influence of these forces, from the difference of velocities of neighbouring particles, that it is necessary to seek for the explanation of the phenomena of the decrease of velo- cities in the approach towards the surface of currents. He goes on to say that we have to conceive, in fine, that these oblique mcvements, producing transverse living forces (“forces vives’), diminish according to certain general laws, the living forces of forward motion which the hydrometric instruments are adapted to indicate. T have cited this passage from Boileau very fully, because it seems VOL. XXVIII. K 118 Prof. J. Thomson on the Flow of Water in [Dee. 12, to me to contain the nearest approach towards an explanation of the phenomenon in question of any that have been attempted, so far as any such attempts have come under my notice. It involves, I think, at least a glimmering towards a true explanation; but I regard it as being in great part erroneous, and importantly so in principle, and as being besides altogether incomplete. I do not think it has been offered by the very able investigator himself, who has proposed it, as being at all sufficient ; but I think it has been offered only as tending to throw some light over the region for further search, and some indication to- wards courses in which speculation and research might well advance. Bazin’s experiments, of the general character already mentioned, were very extensive in their scope, and were carried out in great detail, and with some remarkable refinements of method. The velocities were measured mainly or wholly by a modification devised by Darcy of the well known instrument called Pitot’s tube. Bazin, in the case of canals not very wide relatively to the depth of the current, found very clearly and decisively the phenomenon in question of the maxi- mum velocity being below the surface. But, in the case of rect- angular channels of more considerable width, channels having the width of the current so much as four or five times the depth or more, Bazin by his scrutiny and consideration of his experimental results, was led to conclude that the diminution of velocity for approach towards the surface in the upper part of the current is to be found only in the side parts of the current—the parts flowing along the two side walls. He judged that throughout the whole of the current, except two side parts, each having some moderate width, which might be equal to about twice the depth of the current, the maximum of the velocities for all points, situated in a vertical line, is to be found at the surface; and that the rate of diminution of velocity for descent from the surface would begin as nothing at the surface, and would go on increasing with descent to the bottom. His experiments, according to his own careful analysis and combination of them, appeared to be in agreement with this assumption, or to bring this supposition out as a result. I do not, however, regard this conclusion as being trustworthy. His experiments for the case of great width relatively to depth had not, in any instance, a depth of water exceeding ‘38 of a metre, or 17 foot, and thus the depths were so small absolutely as not to admit of a fine enough discrimination of minute changes of velocity for minute changes of depth of the point where the velocity was observed, nor of measuring velocities close enough to the surface. So far as experi- mental researches go, some doubt I presume must still remain over this part of the subject. Indeed, the Indian experiments, next to be mentioned, show results in disagreement with this conclusion offered by Darcy. ~1878.] Uniform Régime in Rivers and other Open Channels. 119 Quite recently, in 1874—75, experiments were conducted in India on the Ganges Canal, close to Roorkee, by Captain Allan Cunningham, R.EH.* These experiments bring out among their results, very remarkably, the frequently alleged phenomenon of the maximum velocity of the water being not at the surface, but at some moderate depth below. And further, it is deserving of special notice that those of his experi- ments, which have chiefly to be referred to as throwing light on this subject, were made in an aqueduct about 85 feet wide, and with an approximately level bottom; and that the depths of the water in different experiments ranged from about 6 feet to about 94 feet, so that the width was on different occasions from about nine times to about fourteen times the depth, and yet the maximum of the velocities at mid-channel (or the maximum velocity in the longitudinal medial vertical section) came out by averages of numerous results, and, by varied modes of experimenting, to be very decidedly below the sur- face. Hxperiments carried out lately on a very large scale on the Irawaddy river by Robert Gordon, Executive Engineer, British Burmah, Public Works Department, go to confirm the truth of the same phenomenon. These experiments of Mr. Gordon, however, although valuable in many respects, appear to be subject to some doubt as to whether, through the mode of experimenting, the level of supposed maximum velocity has not been brought out too low, that is to say, too near the bottom. On this point Mr. Gordon (in his Introductory Note, § vii, page ii of date 16th June, 1875) intimates his intention to make further experi- ments with other instruments, but still asserts his. confidence in his previous methods and results. Until about two years ago I had not happened to become acquainted with any of the evidence for the phenomenon in question except the unsatisfying experimental results given by Hllet; but about two years ago I met with accounts of some of the more recent and more convinc- ing experimental investigations. It then appeared to me that if the asserted phenomenon must really be accepted as a@ truth, there ought to be some mode possible of accounting for it: and a theory occurred to me which I now propose to submit. The mode of thought which near the beginning of the present paper I have described as constituting the laminar theory, I must premise, has long appeared to me to be an erroneous and a very misleading view. It was a very prevalent mode of thought, and was usually too influential on people’s minds even when they did entertain decidedly, though often not clearly enough, the consideration of eddies and trans- verse movements or commingling currents with different velocities. * “ Wrvdraulic Experiments at Roorkee, 1874-75,” by Captain Allan Cunning- ham, R.H., published in “ Professional Papers on Indian Engineering.” Thomason, College Press, Roorkee, 1875: also Spon and Co., London, &c. Ken 120 Prof. J. Thomson on the Flow of Water in [Dec. 12, The great distinction between the mode of flow of a very viscid fluid, such as treacle or tar, and the mode of flow of water in ordinary circumstances in pipes and in open channels, has not been enough generally and enough consistently attended to. The laminar theory constitutes a very good representation of the viscid mode of motion; but it offers a very fallacious view of the motion in the flow of water in ordinary cases in which the inertia of the various parts of the fluid is not subordinated to the restraints of viscosity. In the flow of water in an open channel in ordinary circumstances the earth’s attraction is perpetually tending to accelerate the forward motion of the water throughout the whole body of the current in con- sequence of the surface declivity ; or we may say, with more complete expression, in consequence of the fall of free-level* which, in virtue of the surface declivity, occurs to all particles in the current as they advance in their down-stream course. The tendency to increase of velocity, if we neglect the backward or forward force, usually very small, or it may be nothing, applied by the air to the water surface, we may say is counteracted solely by a backward resisting force-system applied by the wetted face of the channel to the water momentarily in contact with it. The wetted channel face, it must be observed, is ordinarily more or less rough with gravel, mud, weeds, or other asperities. Itis not a true view to imagine a smooth channel face washed by a thin lamina of water, which imagined lamina of water receives a backward or resisting force-system applied tangentially by the so imagined channel face, and transmits tangential backward force to another lamina of water lying next to itself on the side remote from the channel face. It 1s not the case that from any layer of water whatever, thick or thin, spread over the channel face, resisting forces are transmitted to the interior of the body of the current in any great degree by mere viscid resistance to change of form in the intervening fluid, as would be the case if it were like treacle or tar. But, very differently, indefinite increase of velocity of the water situated in the interior of the current is prevented by continual transverse flows thereto, and commingling therewith, of portions of water already retarded through their having been lately in close proximity to the resisting channel face; and, jointly with that, by the condition that portions of the fluid which have been flowing forward temporarily in * The free-level for any particle of water, in a mass of statical or of flowing water, is the level of the atmospheric end of a column, or of any bar of statical water, straight or curved, haying one end situated at the level of the particle, and having at that end the same pressure as the particle has, and having the other end consisting of a level surface of water freely exposed to the atmosphere, or else haying otherwise atmospheric pressure there. Or, briefly, we may say that the free-level for any particle of water is the level of the atmospheric end of its pressure- column, or of an equivalent ideal pressure-column. 1878.] Uniform Régime in Rivers and other Open Channels. 121 the interior of the current, and have been gaining forward acceleration there are gradually expelled, or do gradually flow from that region, and come themselves into close proximity to the resisting channel face; and so, in their turn, do receive very directly backward forces from the face, because in proximity to it processes of fluid distortion subject to viscid resistance are going on with great activity and intensity. The transverse motions have their origin primarily in the rush of the water along the wetted channel face. When that face is rough or irregular with lumps and hollows or other asperities, reasons for the origination of transverse currents may be sufficiently obvious. But even if the channel face is extremely smooth, so as to present no sensible asperities, still there is good reason to assert that transverse flows will come to be instituted in consequence of the rapid flow of the main body of the current along a lamina, very thin it may be, of water greatly deadened as to forward motion by viscid cohesion with the channel face, and throughout and across which, if regarded as only very thin, in virtue of its thinness, the backward force applied by the face can be transmitted by mere viscosity. The thin lamina of deadened water will tend by the scour of the quicker going water always moving subject to variations both of velocity and of direction of motion to be driven into irregularly distributed masses; and these, acted on by the quicker moving water scouring past them, will force that water sidewise, and will be entangled with it and will pass away with some transverse motion to commingle with other parts of the current.* If we watch the surfaces of flowing rivers, or of tidal currents flowing in narrows or kyles, we may often have opportunity to observe very prevalent indications of rushes of water coming up to the surface and spreading out there. These rushes often may be seen to keep rising in quick succession in numerous neighbouring parts of the * This principle I noticed myself in the connexion in which it is here adduced ; and the idea has since been confirmed to me and rendered more definite through additional considerations mentioned to me lately by my brother, Sir Wiliam Thomson, which have originated with him in some of his theoretical investigations in quite another branch of hydraulic science, and which relate to finite slip im a frictionless fluid. He pointed out that if, for water theoretically regarded as frictionless, or devoid of viscosity, we imagine a long smoothly formed straight trough or channel with a thin vertical longitudinal plane septum dividing it into two parts each uniform in cross-section throughout its length, and if we imagine the space on one side of the septum to be occupied by still water, and a current to be flowing along on the other side; and if, while this is in progress, we imagine the vertical partition to be with- drawn so as to leave the current flowing along a plane face of still water, the motion with the finite slip thus instituted will be essentially unstable. Reasons for this, when once it is brought under notice, are very obvious from consideration of the centrifugal forces, or centrifugal actions, which would be introduced on the slightest beginning being made of any protuberance or hollow im the originally plane interface between the still water and the current. 122 Prof. J. Thomson on the Flow of Water in [Dee. 12, water surface, and they may be seen presenting appearances of spread- ing out till they meet one another and give indication of momentary downward sinking at their places of meeting. From whence do these transverse currents come to the surface? It seems to me they must have had their origin in the deadened water scouring along the bottom, or along the wetted side-faces of the channel, in such ways as have just now been briefly sketched out. Thus it seems that there are tendencies bringing about the result that the superficial stratum of the river receives perpetually renewals of its substance by water currents arriving to it, and spreading out there, which have very recently departed from the bottom before coming up to enter into that superficial stratum. But their substance, having come in great part from the bottom, must be largely made up of the deadened or slow- going bottom-water. It is to be understoed that this deadened water, in rising through the current towards the surface, is partly urged for- ward in the down-stream direction by the surrounding quicker-going water, but that it arrives at the surface without having attained fully to the down-stream velocity of that intermediate stream. It may readily be perceived that it is from the washed face of the channel alone, or from that and the retarded layer of water in proxi- ‘mity to it, that any strong transverse impulses can be applied to any parts of the current. No rapid transverse current will originate in the middle of the body of the river; for there is no cause for the origination of transverse currents there, unless perhaps we were to regard as such any slight transverse motions which may be produced through the gliding forward of parts of the water there relatively to others near them going with different velocities, and unless we were to regard as such any transverse disturbances that may be imparted to forward- flowing water there by the intrusion and commingling of partially deadened water from the channel-face. We may now have great confidence, I think, in taking as a well- established truth, or at least as a very probable view, the supposition already laid down to the effect that very commonly the superficial stratum of a river receives perpetually renewals of its substance by water currents arriving to it and spreading out there, which have very recently departed from the bottom or sides of the channel before coming up to enter into that superficial stratum ; and that the substance thus perpetually renewing the surface stratum is largely composed of deadened or slow-going bottom-water, or of water going slower forward than the water through which it traverses in ascending to the surface. It is further to be noticed that the water which at any moment consti- tutes the superficial stratum is, in its turn, very soon overflowed by later arrivals from the bottom. So it gradually descends from the sur- face into the interior of the body of the river. But during this action it is always flowing downhill, or we may better say it is experiencing 1878.] Uniform Régime in Rivers and other Open Channels. 123 a fall of free level, in consequence of the surface declivity. It is thus receiving forward acceleration in the downhill direction, and its velocity goes ou increasing until at some depth from the surface it reaches a maximum, from whence, during further lapse of time and further descent of this water towards the bottom, the retarding influences imparted to it from the bottom are predominant over the downhill accelerating influence of gravity. These retarding influences, chiefly acting through transverse rushes of water from the bottom commingling more numerously and more briskly with the descending water under consideration the more it gets into the neighbourhood of the bottom, bring about the result that the water goes forward with less and less velocity as it approaches nearer and nearer to the bottom. I have now to offer, by consideration of an imaginable case different from that of an ordinary river, an illustration which will aid in the forming of clear ideas on what I have been presenting as a true theory of the real behaviour of the water in rivers. Let us imagine a flowing river composed mostly of water, but with a layer of oil floating on the top, the oil being of some such depth as a tenth or a twentieth part of the whole depth of the river. Let us suppose the width of the river to be so very great relatively to the depth as that in considering the flow in a middle portion of the river, we may regard it as experiencing no sensible retarding influences, either through the water or the oil, from the sides of the river; and let the flow to be kept under consideration be only that middle portion without the lateral portions which would be sensibly affected by retarding influences from the sides. Here we have a case differing from that of an ordinary river of water in this important respect, that, while in the ordinary river the superficial stratum of fluid is per- petually changing its substance, and is, as I suppose, perpetually recelving new supplies of deadened water from the bottom, in the imagined case now adduced the substance of the superficial layer being of oil floating at top, does not undergo any such change. The oil then, it seems very certain, would really rush down what we may call the in- clined plane of water on which it lies, and would go on accelerating its motion until, by advancing very much faster than the water, it would introduce a frictional drag between itself and the water sufficient to hinder its further acceleration ;*' or rather until, without attaining to * Postscript note, lst November, 1878.—An observed phenomenon, which, if duly taken into consideration, must doubtless be found to be closely allied in its nature to the supposed behaviour of the imagined layer of oil on a flowing river of water above adduced, and which is certainly of much interest, both for its own sake and in refe- rence to theoretical views which have been held as to its origin and its indications, has come under my notice since the time when the present paper in manuscript was presented to the Royal Society. The book by Bazin, which may be briefly named as Darcy et Bazin “ Recherches Hydrauliques,” Paris, 1865 (see a previous foot-note in this paper), contains prefixed to it a report, dated 1863, of a committee of the 124 Prof. J. Thomson on the Flow of Water in [Dev. 12, that stage of great relative velocity, it would at an earlier stage ruffle up Wh: mutual face of meeting of itself and the water into pro- tuberances and hollows, somewhat files waves, on the principle referred to already in a foot-note as having been proposed by Sir William Thomson, and would carry this action on to the extent of causing commotion and commingling of the water and oil. The contrast be- tween this case and that of an ordinary river of water is so remarkable as to aid the forming of a clear comprehension of the very different mode of action which I have been attributing to the water in ordi- nary rivers and other open channels. It is further worthy of notice that if, from any local cause, the water flowing forward in some part of the width of a river has in its motion a component downward from the surface towards the bottom, and is free from intrusion of upward currents or rushes of deadened water Academy of Sciences on the memoir of M. Bazin, “Sur le Mouvement de I’ Hau dans les Canaux decouverts.’’ In that report the committee remark (as confirmatory of the view which they accept, to the effect that in deep rivers, especially when not very wide relatively to their depth, the place of maximum velocity is at a considerable depth below the surface) as follows :—“‘ Il yalongtemps que les bateliers du Rhin et nos pontonniers savent qu’un bateau chargé et ayant un fort tirant d’eau, marche, en . descendant, plus vite que ]’eau qui le soutient ou que les corps flottants 4 la surface.” This obviously conveys the opinion that a heavily loaded boat, sinking deep into the water, and thereby having its deeper part immersed in water which is flowing quicker than the surface water, is dragged forwards by that deeper and quicker moving water, and so is made to nilemmes quicker than the surface water does. The idea seems to be that the boat has some average velocity less than that of the water at its bottom, and greater than that of the surface water. The view which thus appears to be held in respect to the observed phenomenon seems to me to be inadequate and erroneous. On the principle put forward above in the present paper in reference to the imagined case of a river with an upper layer of oil, I would suppose that a large and heavy boat, even if flat-bottomed and of shallow draught of water, would run down the river-course quicker than the water in which it swims; for the reason that while all the water surrounding it makes occasional visits to the bottom of the river, and meets with great retardation there, the boat does not dive to the bottom, and is free from any such retardation, and so is only held back by the surrounding water against taking from gravity a perpetually increasing velocity. Thus it must go faster than the surrounding water which has to hold it back. The boat of deeper draught referred to by the committee I would suppose would advance quicker than the surface water, for the same reason, and not merely because of its bottom being situated in water moving quicker than that at the surface. The principles I have assigned would afford ample reason for our supposing that the boat of deep draught might swim forward much quicker not only than the surface water, but also than the water at its bottom, or indeed than any part of the water of the river surrounding the boat. Very small floating objects, such as sticks or leaves, would present, in proportion to their small masses, so much resistance to motion through the surrounding water that they would be constrained in fact to move sensibly at the same velocity as that of the water surrounding them. The phenomenon would thus be presented of the boat swimming forward past the small floating objects around it. J.T. 1878.] Uniform Régime in Rivers and other Open Channels. 125 from the bottom, or of water retarded by the influence of the river- bed, we ought to expect the forward velocity to increase from the sur- face to very nearly the bottom. The accelerative influence of gravity due to the surface inclination, and more particularly due to the fall of free-level experienced, as an accompaniment of that inclination, by the water throughout the body of the current in its onward flow would generate in every portion or particle of this water increase of velocity for advance along its course; because, in the absence of rushes of deadened water from the bed, such as it appears do commonly intrude into the body of the current, there wou!d be no retardative influence to counteract the gravitational accelerative influence; since the mere viscosity of the water unaided by transverse commingling is, I con- sider, insignificantly small and quite ineffectual as a resisting influence or means of transmitting resistance from the bed to any part of the water in the body of the current out of close proximity to the bed. But as this forward moving water is also descending towards the bottom while it is gaining forward velocity, it follows that, in the cir- cumstances of flow supposed, we ought to expect the forward velocity to increase with descent from the surface to very nearly the bottom. It is to be understood that the freedom supposed from upward rushes or intrusions of deadened water will not be maintained in the water when it arrives into proximity to the bottom. In approaching very near to the bottom the water must begin to receive important resisting forces communicated to it from the bottom through commingling of dead- ened water, and by intense distortional actions with viscosity. Tt is also to be noticed in connexion with the case under con- sideration that if, in one part of the width of the river, there is a pre- vailing descent towards the bottom, there will be upward flows to compensate for this in other parts of the width. Then obviously the whole character of the action of the water will be very different in the regions where ascent prevails from that in the regions where there is a prevailing descent; and the distribution of forward velocities throughout any vertical line in the one region will be quite different from the distribution of forward velocities throughout any vertical line in the other region. Local circumstances casually affecting the flow in the way here described I think may perhaps account for some of the apparent anomalies in respect to the distribution of velocities through different parts of the depth from surface to bottom which have been met with by various experimenters, and have been included among the recognised causes of the perplexity and bewilderment with which this branch of hydraulic science is pervaded. I wish next to draw attention to one of the results of observation and experiment announced by Captain Cunningham in his book already referred to (‘‘ Hydraulic Experiments at Roorkee’). In his discussion of his experimental results on the flow of water in each of 126 Prof. J. Thomson on the Flow of Water. | Dee? a2y two artificially-formed channels on the Ganges Canal, one of them, 168 feet wide, and the other 85 feet wide, and each having the water often about from 6 feet to 9 feet deep, he states (p. 46, article 35): “There is a constant surface motion (deviation) from the edges towards the centre, most intense at the edges and rapidly decreasing with distance from the edges.” This experimental conclusion, on the supposition of its being decidedly trustworthy, as Mr. Cunningham asserts with confidence that it is, I think may probably be satisfactorily explicable through considerations intimately connected with those which I have already given for an amended theory of the flow of water in rivers. I wish, however, not to prolong the present paper by entering on any detailed discussion of this branch of the subject, and besides I prefer to reserve this for some further consideration before venturing to put forward the views in reference to it which at present appear to me likely to be tenable. It may be noticed, however, that Captain Cunningham’s experimental result, if decidedly correct, throws addi- tional light on the subject of the abatement of surface velocity compa- ratively to the velocity at some depth below the surface being found in Bazin’s experiments to occur in a much greater degree near the sides of rectangular and various other channels than at middle. Bazin thought indeed from his own experiments (as I have already had occa- sion to mention) that the relative retardation or slowness of the surface occurred not in the middle of wide channels (that is to say, of channels wide relatively to the depth of the water) but only near the sides; but this supposition I have referred to as appearing not to be trustworthy. With these brief suggestions I will now leave for further consideration the subject of the special phenomena of the influence of the sides. Historical Note. Subsequently to my having formed, in all its primary or more essential features, the new view now explained of the flow of water in rivers, and before I had met with the book of Humphreys and Abbot, I happened to see in the writings of another author (paper of Mr. Gordon already referred to) the following remark in reference to their views as to the velocity at the surface being less than at some depth below. ‘‘ Humphreys and Abbot attribute the fact to trans- mitted motion from the irregularities of the bottom; but confess them- selves dissatisfied with their own explanation.” These words seemed to me to indicate a probability of Humphreys and Abbot having anticipated me in some part at least of the theory which I had been forming. On obtaining their book, how- ever, and reading the passage referred to, not by itself alone, but. with its context, it appeared to me that it involved no real anticipation, 1878. | The Magic Mirror of Japan. 127 although one clause of a sentence in it, read by itself, might be sup- posed to do so. The passage is to be found in their work at p. 286. They begin by saying, that their experimental observations detailed in their previous pages “ prove that even in a perfectly calm day there is a strong resistance to the motion of the water at the surface as weil as at the bottom,” and that this resistance at the surface “is not wholly or even mainly caused by friction against the air.” They go on to say:—‘‘ One important cause of this resistance is believed to be the loss of living force, arising from upward currents or transmitted motion occasioned by irregularities at the bottom. This loss is greater at the surface than near it. The experiment of transmitted motion through a series of ivory balls illustrates this effect. It is likewise illustrated on a large scale by the collision of two trains of cars on a railway, in which case it has been observed that the cars at the head of the train are the most injured and thrown the farthest from the track; those at the end of the train are next in order of injury and disturbance; while those in the middle of the train are but little injured or disturbed. Other causes may and probably do exist, but their investigation has, fortunately, more of scientific interest than practical value. For all general purposes it may be assumed that there is a resistance at the surface, of the same order or nature as that which exists at the bottom.” Now although this passage does contain the words “ arising from upward currents or transmitted motion occasioned by irregularities at the bottom,’ yet the illustrations, by means of the series of ivory balls, and of the collision of railway trains, show that the authors attribute to those words no clear and correct meaning, but, on the contrary, | would say they put forward quite a false view of the actions going on. Besides I myself do not admit that, except from the air, there is a resistance at the surface. According to my supposition the already resisted and retarded bottom water comes to the surface and spreads out there, but receives no new resistance there, and on the contrary receives acceleration from gravity in running down hill. II. “The Magic Mirror of Japan.” Part I. By Professors W. E. AYRTON and JOHN PERRY, of the Imperial College of Engineering, Japan. Communicated by WILLIAM SPoTTIS- WOODE, Esq., M.A., Treas. R.S., &e, &e. Received October 2, 1878. The Japanese mirror must, from three points of view, attract the notice of foreigners sojourning in that country—its prominence in the temples, the important feature it forms in the limited furniture of a Japanese household, and the wonderful property (which has apparently 128 Profs. W. E. Ayrton and John Perry. [Dec. 12, created more interest in Hurope than it has in Japan) possessed by certain Japanese and Chinese mirrors of apparently reflecting from their polished faces the raised characters on their backs. It was for this third reason, the interest that such mirrors have long possessed for the student of science, that our attention was drawn to the subject, and it has been in this direction that our inquiry has been chiefly directed. The results of our investigation we propose giving in the present paper, reserving for a subsequent occasion*™ some remarks on the Japanese mirror as an object of worship, and the position it holds on the toilet table of a Japanese lady. The mirror of the Far Hast is too well known to need an elaborate description ; suffice it for the present to observe that it is generally more or less convex on the reflecting side, usually made of bronze, polished with a mercury amalgam, and having at its back a gracefully executed raised design, representing birds, flowers, dragons, a geo- metrical pattern, or some scene in Japanese mythical history. Occa- sionally there are in addition one or more Chinese characters (signi- fying long-lhfe, happiness, or some similar idea) of polished metal, in bold relief. To the method of manufacture we shall refer further on, and especially to the mode in which the convexity of the surface is produced; which portion of the manufacture, while playing, as it does, an important part in the magical behaviour of the mirror, is, as far as we are aware, not to be found described in any of the Hastern or Western writings on the subject. Just before leaving England, in 1873, the attention of one of the authors was directed to the so-called magic property of certain Hastern mirrors by the late Sir Charles Wheatstone, who explained to him that the Japanese had a clever trick of scratching a pattern on the surface of a bronze mirror which, after being polished, showed no traces of the scratches when looked at directly, but which, when used to reflect the sunlight on to a screen, revealed the pattern as a bright image. This opinion appears to have been shared by Sir David Brewster, since he says, in the ‘ Philosophical Magazine” for December, 1832 :— ‘‘ Like all other conjurors, the artist has contrived to make the observer deceive himself. The stamped figures on the back (of the mirror) are used for this purpose. The spectrum in the luminous area is not an image of the figures on the back. The figures are a copy of the picture which the artist has drawn on the face of the mirror, and so con- cealed by polishing that it is invisible in ordinary lights, and can be brought out only in the sun’s rays.” As the explanation, therefore, appeared to this one of the authors to be so simple, and at the same time so complete, he practically dis- missed the subject from his mind. * A lecture at the Royal Institution. 1878. | The Magic Mirror of Japan. 129 However, he was a little astonished to find, during his residence in Japan, that, although the magic mirror was supposed in Europe to be a standard Japanese trick, and although it had been considered by Sir Charles Wheatstone as one of the best proofs of the ingenuity of the workmen of Japan, still that it formed no part of the stock-in- trade of any of the numerous conjurors in this country, and was never exposed for sale in any of the curiosity-shops. He was also still more surprised when, during the visit of the “ Challenger,” Sir Wyville Thomson and himself were strolling about Tokio, to find that, although they asked at several mirror shops for a mirror that showed the back, a specimen of which Sir Wyville much desired to possess, the shop- keepers seemed not to have the slightest knowledge of what was wanted. At that time the author could not but regard the total apparent ignorance displayed by the Japanese mirror-vendors on this subject as the result of his limited knowledge of the language, and he had then no notion that, in Japan at any rate, the phenomenon was the result of no clever trickery, but arose from the method in which the mirrors were pre- pared. We have since learnt, however, by diligent inquiry, that, as is the case with many things appertaining to Japan, so with the magic mirror, the people who know least about the subject are the Japanese themselves, and we think this only furnishes another proof that teachers to instruct the Japanese about Japan itself are the greatest desideratum. Our attention was next directed to the subject of the curious pro- perty possessed by some Japanese mirrors by a letter from Professor Atkinson, of the Tokio Dai Gaku (the Imperial University), which appeared in “ Nature,” May 24th, 1877, and in which he says, after referring to the phenomenon of the pattern on the back being ap- parently reflected when sunlight is allowed to fall on the face :— “*I have since tried several mirrors, as sold in the shops, and in most cases the appearance described has been observed with more or less distinctness.* “T have been unable to find a satisfactory explanation of this fact, but on considering the mode of manufacture I was led to suppose that the pressure to which the mirror was subjected during polishing, and which is greatest on the parts in relief, was concerned in the pro- duction of the figures. On putting this to the test by rubbing the back of the mirror with a blunt-pointed instrument, and permitting the rays of the sun to be reflected from the front surface, a bright line appeared in the image corresponding to the position of the part rubbed. This experiment is quite easy to repeat, a scratch with a knife, or with any other hard body, is sufficient. It would seem as if the pressure upon the back during polishing caused some change in * Only a small ycrcentage, however, of the total number of Japanese mirrors that the authors of this paper have experimented on show the phenomenon clearly. 130 Profs. W. E. Ayrton and John Perry. [ Dec. 12, the reflecting surface corresponding to the raised parts, whereby the amount of light reflected was greater; or supposing that, of the hght which falls upon the surface, a part is absorbed and the rest reflected, those parts corresponding to the raised portions on the back are altered by the pressure in such a way that less is absorbed, and there- fore a bright image appears.” Professor Atkinson cautiously adds: ‘“‘ This, of course, is not an explanation of the phenomenon, but I put it forward as perhaps in- dicating the direction in which a true explanation may be looked for.” In vol. i, p. 242, year 1832, of the ‘‘ Journal of the Asiatic Society of Bengal,’ Mr. Prinsep gives an account of a Japanese magic mirror which he had seen in Calcutta. He does not appear to have made any direct experiments with this mirror for the purpose of elucidating which of all the possible causes is the real cause ot the magic pheno- mena, but rather he concludes “from analogy that the thin parts or tympanum of the Japanese mirror are slightly convex with reference to the rest of the reflecting surface, which may have been caused either by the ornamental work having been stamped or partially carved with a hammer and ehisel on its back; or, whieh is more probable, that part of the metal was by this stamping rendered in a degree harder than the rest, so that in polishing it was not worn away to the same extent.” It does not seem to have occurred to him that Japanese mirrors are cast and not stamped at all. In “ Nature,” June 14th, 1877, Mr. Highley refers to the exhibition of a Japanese mirror by Professor Pepper some years ago at the Poly- technic Institution, London, and to the praiseworthy attempt of an English brass worker, who saw the experiment, and who also was under the false impression that such mirrors were stamped, to solve the pro- blem. ‘‘ The workman found that taking ordinary brass and stamping upon its surface with any suitable die, not once, but three times in succession, upon exactly the same spot, grinding down and polishing between each act of stamping, a molecular difference was established between the stamped and unstamped parts, so that images of the pat- tern could be reflected from the finally polished surface, just as with the Japanese specula, though no difference of surface could be detected with the eye.” To people who have not been in China or Japan, and personally studied mirror-making, this idea of stamping seems very plausible, for Sir David Brewster, on p. 113 et seq. of his “‘ Letters on Natural Magie,”’ published in 1842, describes fully a method, depending on the mole- cular change produced by stamping, by means of which the inscrip- tions on old coins, that have been worn quite smooth, may be deciphered. This method merely consists in heating the coin on a piece of red-hot iron, when the inscription becomes visible from the different rate of oxidation of the part of the coin that has been subjected to great 1878. | The Magic Mirror of Japan. | 131 pressure in stamping from that part that has been subjected to less. But, as already mentioned, all explanations depending on stamping must at the outset be put on one side when studying the behaviour of Japanese mirrors, since casting, and not stamping, is the process em- ployed in their manufacture. In the “‘ Reader” (a paper now extinct) for February, 1866, Mr. Parnell attempts to explain the phenomenon by an inequality in the surface of the mirror, produced by the thinner portion warping more in cooling than the thicker part where the pattern exists, and he endea- vours to experimentally examine this by studying the direct reficction of the globe of a gas-lamp, as seen in the different parts of the mirror. We, as well as Professor Atkinson, have tried to repeat this ex- periment with some magic mirrors in our possession, but we cannot say that it affords any conclusive evidence regarding the cause of the phenomenon. It therefore appeared to us a year ago that the subject would repay investigation, an opinion also expressed by Professor Silvanus Thomp- son, who, in writing from University College, Bristol, to “‘ Nature,”’ during June of 1877, suggested that the Japanese mirrors exhibited at the Loan Collection of Scientific Apparatus in London might, if they showed the phenomenon, be used for such an investigation. And as Professor Atkinson did not propose following up the question himself, he lent us the mirror which he possessed, and cordially agreed with our proposal that we should undertake the investigation. This we have done, and obtained the results which we venture to submit this evening to the Society. At the commencement of the inquiry we naturally desired to see what had been written on the subject of Japanese mirrors, and this brought to our notice the information regarding mirrors generally in this country, which, as mentioned at the beginning of this paper, will form, we propose, the substance of a subsequent communication. But, of the magic mirror, Japanese literature (so far as we have been able to ascertain) makes absolutely no mention. In “Les Industries Anciennes et Modernes de I’Empire Chinois,” published in 1869, by MM. Stanislas Julien and Paul Champion, there is a short article on ‘“‘ Les Miroirs Magiques des Chinois, et leur fabrication,” taken from the paper communicated by M. Julien to the French Academy of Sciences. In this he says :— “Many famous philosophers have for a long time, but without suc- cess, endeavoured to find out the true cause of the phenomenon which has caused certain metallic mirrors constructed in China to have acquired the name of magic mirrors. Even in the country itself where they are made no European has, up to the present time, been able to obtain either from the manufacturers, or from men of letters, the information, which is so full of interest to us, because the former keep 132 Profs. W. E. Ayrton and John Perry. Deck 12; it a secret when by chance they possess it, and the latter generally ignore the subject altogether. I had found many times in Chinese books details regarding this kind of mirrors, but it was not of a nature to satisfy the very proper curiosity of philosophers, because sometimes the author gave on his own responsilility an explanation that he had guessed at, and sometimes he confessed in good faith that this curious property is the result of an artifice in the manufacture, the monopoly of which certain skilled workmen reserve to themselves. One can easily understand this prudent reticence when we remember that the rare mirrors which show this phenomenon sell from ten to twenty times as dear as the rest.” M. Julien then givesan elaborate description of one of these mirrors in the possession of the Marquis de La Grange. He further remarks that such mirrors are called in Chinese theou-kouang-kién, which means literally ‘‘ mirrors that let the light pass through them,” and that this name has arisen from a popular error on the subject. Chin-kouo, a Chinese writer who flourished in the middle of the eleventh century, speaks with admiration about them in his memoirs called Mong-ki-pi- tan, book xix, folio 5. The poet Kin-ma has celebrated them in verse ; but up to the time of the Mongolian emperors nobody could explain ~ the cause of the wonderful phenomenon. Ou-tseu-hing, who lived between 1260 and 1341 under this dynasty, had the honour of being the first to throw any light on the subject. He says: ‘‘ When we turn one of the mirrors with its face to the sun, and allow it to throw a reflection on a wall close by, we see the ornaments or the characters which exist in relief on the back appear clearly. Now the cause of this phenomenon arises from the employment of two kinds of copper of unequal density. If on the back of the mirror a dragon has been produced while casting it in the mould, then an exactly similar dragon is deeply engraved on the face of the disk. Afterwards the deep chisel-cuts are filled up with denser copper, which is incorporated with the body of the mirror, which ought to be of finer copper, by submitting the whole to the action of fire, then the face is planed and prepared, and a thin layer of lead or of tin spread over it.* ‘‘When a beam of sunlight is allowed to fall on a polished mirror prepared in this way, and the image is reflected on a wall, bright and dark tints are distinctly seen, the former produced .by the purer copper, and the latter by the parts in which the denser copper is inlaid.” If, then, we understand this description of Ou-tseu-hing correctly, 1% would appear that the pattern appears by reflection as a dark image on a bright ground, the opposite of what is experienced in Japanese mirrors. * This probably refers to the mercury amalgam which is used in polishing, and which Ou-tseu-hing mistook for lead or tin. 1878. ] The Magie Mirror of Japan. 133 Ou-tseu-hing adds that he has seen a mirror of-this kind broken into pieces, and that he has thus ascertained for himself the truth of this explanation. In a recent interesting article published in No. 29 of the “‘ Garten- laube,” Heft 8, 1877, by the well-known German popular writer whose nom-de-plume is Carus Sterne, doubt is thrown on the above explanation, since Herr Sterne thinks the magic mirror he himself possesses is too thin for any such inlaying to have been performed. In quoting the infor- mation given by M. Julien, to which reference is made above, he inci- dentally mentions that it is taken from the fifty-sixth volume of the Chinese encyclopedia called ‘‘ Ke-chi-king-youen.”” Herr Sterne adds that these magic mirrors were known to the Chinese from the earliest times, and that one of their writers spoke about them in the ninth century of the Christian era. He remarks that the Roman writer Aulus Gellius, who lived seventeen centuries ago, referred to mirrors that sometimes reflected their backs and sometimes did not. From the great antiquity of the Chinese magic mirrors Herr Sterne thinks it pro- bable that the mirrors with secret signs and figures of imps on the back which formed a portion of the stock-in-trade of the witches of the middle ages were of Hastern manufacture. He further alludes to the account given by the Italian historian Muratori of the magic mirror found under the pillow of the Bishop of Verona, who was afterwards con- demned to death by Martin della Scala, as well as to the one disco- vered in the house of Cola da Rienzi, on the back of which was the word ‘‘ Fiorone.” Neither in “ Les Memoires concernant les Chinois par les Mis- sionaires,’”’ nor in Duhalde’s classical work on China, is there any mention of the magic mirror. I understand, however, that a short paper on the subject, by Professor Harting, appeared some years ago in a Dutch periodical, the ‘“‘ Album der Naturer;” this I have not seen: but Dr. Geerts, a Dutch gentleman resident in Japan, and who has a most extensive acquaintance with the literature bearing on that country, informs me no explanation of the phenomenon was contained in that article. Japanese literature, as already mentioned, appears to be quite barren of information regarding their own or the Chinese mirrors which appear to reflect their backs. But in the shim-pen-kamakura-shi, or ** New Collection of Writings about Kamakura,” it is mentioned that in the temple Kenchoji, situated in the ancient capital of the Shogun,* there is treasured up a wonderful old mirror, 33 sins high and 3 sins wide,+ which, when looked at somewhat obliquely, shows the image of * Shogun, the military usurper of the throne of Japan, and recognized in modern times prior to the revolution of 1869 as the rightful sovereign. He was sometimes erroneously called the Tycoon. 7 A sun is nearly one and one-fifth of an inch. VOL. XXVIII. L 134 Profs. W. E. Ayrton and John Perry. [(Dee.a2% a Buddhist god. This appearance, however, is in no way connected with the pattern at the back, which consists of a new moon reflected in the sea; the artistic balance of the picture being maintained by a rosary anda plum tree. The hole in the upper portion of the mirror is probably for the attachment of a silk cord to hang it up by. The supposed marvellous character of this mirror causes great reve- rence to be shown to the god of the temple, as it is considered to furnish an undoubted proof of his supernatural character; in fact, the mirror receives nearly as much respect as this Buddhist deity himself. The way in which the optical effect has been produced is said to be the same as that described in the Kokon-i-to, ‘“‘ The Genealogy of the Old and New Physicians,” and which is as follows:—Take ten parts of shio (gamboge), one of funso, and one of hosha (borax). Powder these thoroughly, and mix them to the consistency of a paste with a little dilute glue. If any pattern be drawn on the surface of the mirror with this paste, and then allowed to dry, the pattern will be seen, even after polishing, if looked at obliquely. A mirror, in the face of which was seen the appearance of the famous priest, Shinran-sho-nin, who instituted the Shinshiu religion, to which the Honguangi temples at Kioto belong, was formerly in the possession of the Kuge* Rokujo, and was, to a certain extent, wor- shipped. Wood-cuts of this mirror were also sold at this nobleman’s house, and were regarded as a faithful representation of the priest Shinran-sho-nin. One of the persons formerly employed at the Hon- guangi temples, Kioto, tells us he remembers, some years ago, a messenger, coming from Mr. Rokujo, asking that the authorities of the temple would give a certificate, stating that the mirror had been constructed by Shinran-sho-nin himself for holy purposes. This, how- ever, they declined to do, believing rather that Mr. Rokujo had fabri- cated it himself to obtain money on exhibition. Mr. Rokujo, to whom we have applied on the subject, says, that the old tradition in his family was that the mirror originally came from Hchigo ;+ also that, after the failure to obtain a certificate of its sanctity referred to above, he sold it to a temple situated near Kioto, from which, however, it was subsequently removed, and that he is quite unacquainted with its present whereabouts. A Tokiof mirror maker, however, tells us that he has seen an exactly similar mirror at Okasaki-mura, a small village near Kioto, so perhaps this is the present habitation of Mr. Rokujo’s old mirror. It does not appear that this chemical method of preparing the face * “ Kuge,”’ a nobleman formerly attached to the Micado’s Court at Kioto, the ancient capital. + Echigo, a province in the centre of Japan. + “The Eastern Capital,” the name given to Yedo since the revolution of 1869, when the Micado transferred his court there from Kioto. 1878. | The Magic Mirror of Japan. 135 has ever been employed in Japan to alter a portion of the surface in such a way that this part becomes visible in the image formed by re- flection, although invisible when looked at directly. A certain Tokio mirror maker, however, said that he had employed the chemical method for this purpose in the following way :— Coat the surface of the mirror with wrushi (Japanese varnish), with the exception of the portion that it is desired shall cast the brighter reflection, then act on this part with a paste composed of equal parts of sulphur and copper sulphate, powdered and mixed with shiro-wmedza (white plum acid). If this paste, after being allowed to dry on the mirror, which takes about two days, be rubbed off, and the mirror be frequently polished, the pattern (so said this mirror maker) will become invisible when looked at, but will appear in the reflection of the mirror thrown on to a screen. If the above be true, then, if a pattern be drawn on the face of the mirror with the varnish while the remainder of the face is acted on chemically, this pattern should, on reflection, appear darker than the rest. We therefore instructed him to prepare two mirrors, and on the face of one to act chemically on a portion corresponding with the letter “ C,’ while, with respect to the other, he was to leave untouched only a small part of the face, corre- sponding with the letter ““N.”’ This he did; after several polishings of the two mirrors both letters could be seen, either directly or on reflection ; after many polishings, however, the letter ‘‘ C”’ disappeared for direct vision, but it also disappeared for reflection, and the letter ““N” remained visible, either if looked at very obliquely, or when a bright light was reflected on to a screen. In other words, the attempt of this mirror maker turned out a failure. He regards it as resulting from a loss of his former skill, but we are inclined to think that he was confusing the method with which he was acquainted for making an image visible when the face of the mirror is looked at obliquely (the phenomenon which is observed in the mirror at Kamakura), with a method for making the so-called magic mirror, of which he has pro- bably no knowledge. One very interesting fact, however, came out in this experiment, and that was the mirror on which the letter “C”’ was made, and which did not originally reflect the pattern on the back, acquired the power to do so after ten successive polishings. In fact, the mirror maker caused this mirror to acquire the so-called magic character, but in a way unexpected by himself. Haplanations :—The possible explanations of the phenomenon shown by certain Japanese mirrors may be divided into three classes :— 1. The pattern might be scratched on the face of the mirror and hidden by subsequent polishing. 2. The portion of the face corresponding with the pattern might have a different molecular constitution from the metal forming the remainder of the mirror. 1h; Dy 136 Profs. W. E. Ayrton and John Perry. [Decale This difference in molecular constitution might produce the re- sults :— a. By causing the portion of the face corresponding with the pattern at the back to attract more mercury, and so to become capable of being polished more easily ; or b. By causing it to be harder, and so to acquire a better polish; or c. By causing it to polarise light. This difference in molecular constitution might be produced :— a. By the inlaying of another metal; or b. By portions of the surface being acted on chemically ; or c. By unequal density produced by inequality in the rate of cooling ; but d. Not by stamping, Japanese mirrors being all cast. 3. The phenomenon might arise from the face of the mirror having intentional or accidental inequalities on its surface, in consequence of which, the part corresponding with the pattern on the back might be relatively concave, and so concentrate the light, or, at any rate, might disperse it less than the remainder of the slightly convex mirror. The question then resolves itself into considering to which of these three groups of causes is the apparent reflection of the back in some Japanese mirrors due. To ascertain this, we tried Sir David Brewster’s suggestion that the light reflected by the thicker part of the mirror was polarised ; but even with a fairly good polariscope, we could detect no marked difference between the light reflected from the various portions of the surface. This failing, we availed ourselves of a very simple method of experimenting, but one that has apparently not suggested itself to previous observers. On one occasion, when some of our students were using lenses to endeavour to make the exhibition of the pheno- menon more striking, it occurred to us that the employment of beams of light of different degrees of convergence or divergence would fur- nish a test for deciding the cause of the whole action. For while, if the phenomenon were due to molecular differences in the surface, the effect would be practically independent of the amount of convergence of the beam of light; on the other hand, if it were due to portions of the reflecting surface being less convex than the remainder, a com- plete inversion of the phenomenon might be expected to occur, if the experiment, instead of being tried in ordinary sunlight, were made under certain conditions in a converging beam—tkat is, the thicker portions of the mirror might be expected to appear darker instead of brighter than the remainder. Figs. 1—6, which are all much exaggerated for the sake of distinctness, explain this better. MM, fig. 1, represents an ordinary Japanese slightly convex polished bronze mirror. SA, SB, SC, are rays of a parallel beam of light falling on it, and reflected as AD, BE, CF, on toascreen DI’; then, if the areas 1878. | The Magic Mirror of Japan. 137 AB and BC of the mirror be about equal to one another, the amount of light falling on them will also be equal ; and, since the illuminated areas DE and HF are about equal, they will be equally bright. But if Fie. 1. a portion AB of the mirror be, for any reason, flatter than the re- mainder, then the quantity of light which falls on it, instead of being reflected so as to illuminate the area DE of the screen, will only illu- minate some such area as GH. Now, this area being smaller than HF, but receiving the same quantity of light, will appear much brighter than HF; in addition, too, the spaces DG and HE receive but very Fig. 2. little light, and are consequently relatively dark, the excess of bright- ness, therefore, of the area GH will be apparently much heightened by contrast. And exactly the same reasoning applies to fig. 2, in which the mirror is illuminated by a beam of light diverging from 138 Profs. W. E. Ayrton and John Perry. [Deera2: the point S. But if we now turn to fig. 3, where the light is con- verging to a point behind the convex surface, and nearer to the sur- face than half the radius of the mirror, then, after reflection, the light converges to a point O in front of the mirror, and, as before, the area GH (which has become almost a point, G) is smaller, and therefore brighter, than the area DH, as long as the screen is nearer to the mirror than the point P, but larger, and therefore darker, than D'H', when the screen is farther from the mirror than P. In other words, if the phenomenon of the Japanese mirror is due to the curvature of different parts of the surface being slightly different, then with the arrange- Fig. 3. ment of light shown in fig. 3, the whole effect ought to undergo an inversion as the screen passes through P; that is to say, if the parts corresponding with the pattern at the back are the flatter, then, while these should appear as bright on a dark ground when the screen is at a position DF, they ought to appear as dark ona bright ground when the screen is at a position D'E". Now this is exactly what is found to be the case when tested experimentally. Again, if the phenomenon is, as the previous experiment would lead us to conclude, due not to unequal reflecting power of the different portions of the surface of the mirror, but to minute inequalities on the surface, in consequence of which there is more scattering of the rays of light falling on one portion than on another, then since rays of light making very small angles with one another do not separate per- ceptibly until they have gone some distance, it follows, that if the 1878.] The Magic Mirror of Japan. 139 screen be held very near to the mirror, the apparent reflection of the back, the magical property in fact, ought to become invisible. And this, also, is exactly what happens when we make the screen almost touch the polished surface. We have, therefore, strong reasons for favouring the ‘‘ inequality of curvature’’ theory. In order, however, to make the explanation quite certain, we have had made a small concavity and a small con- vexity on the face of one of the mirrors, by hammering with a blunt tool, carefully protected with a soft cushion to avoid scratching the polished surface, and, as is seen on trying the experiment, the con- cavity reflects a bright image and the convexity a dark one when the screen is in the position DF, but when the screen is shifted to D'E"’, it is the convexity which appears as the bright spot, and the concavity as the dark one. And not only do we think that the thicker portions of the convex mirror are flatter than the remainder, but the existence of a focus for a divergent pencil (as evidenced by a best position of the screen in fig. 2) leads to the conclusion that, in some instances at any rate, the thicker portion is actually concave, and is found to have a radius of about three to four metres. In the account of the Chinese Magic mirror, given by Ou-tseu-hing at the end of the thirteenth century, he mentions that the wall or screen on which the shadow is cast should be near, an instruction which people have usually found it necessary to follow in order to see the phenomenon clearly. But this condition of proximity of the screen to the mirror is necessary, simply because the sunlight falling on the mirror neither forms a parallel beam, nor one diverging from, nor converging to, a single point, but consists, of course, of an enormous number of slightly diverging beams. Consequently, on any one poimt of the mirror there fall rays of light, each making a slightly different angle with the surface. Now, as these, after reflection, pro- ceed in slightly different directions, they will illuminate different points of the screen, and, therefore, make a well-defined image impos- sible, unless the screen be held near. If ordinary sunlight then be employed, the screen, as previously explained, must be held not so near the mirror that the inequalities of the surface are unable to produce any decided displacement of the rays before they strike the screen, and in addition, as we now see, not so far from the mirror that the different rays falling on the sume point are perceptibly separated before they reach the screen; or, putting the above conditions into more pre- cise mathematical language, the screen must not be held so near the mirror that the product of this distance into the angle between the normals to two adjacent parts of the surface is too small, and not so far from the mirror that the product of this distance into the angular diameter of the sun is too large. 140 Profs. W. kK. Ayrton and John Perry. [Dec. 12, This condition, however, of proximity of the screen to the mirror ceases to have any weight, and the phenomenon can be shown to a _Jarge audience by projecting it on a distant wall if one or other of the following devices be adopted :— 1. Allow the sunlight to first pass through a small hole, so that all the rays falling on the same point of the surface of the mirror make the same angle with the surface. 2. Obtain the same result thus :—first let the sunlight fall on a convex lens or on a concave mirror which brings it to a focus, and afterwards causes it to diverge from a single point, then hold the Japanese mirror in the diverging beam at about eight or more feet from the principal focus of the lens or auxiliary concave mirror. 3. Illuminate the mirror with light diverging from a single bright point at some distance, as, for example, from an electric light at the other end of the rcom, the screen, of course, being shaded from the direct light of the lamp. Fra. 4. 4, Allow the sun’s rays to fall on the nearly plane Japanese mirror MM, and after retilection let them pass through a converging lens so adjusted that the screen RR, fig. 4, is beyond the principal focus, P, of the mirror and lens combined, and also beyond JJ, the conjugate focus of the mirror, that is the place at which the image of the pian mirror is formed by the lens. The last method causes the effect to be better than that obtained with ordinary sunlight alone, because the insertion of the lens separates the rays falling on different points of the Japanese mirror more than it separates those which, coming from different points of the sun, are reflected in different directions by the same small portion of the Japanese mirror. In fact, the employment of the lens corrects, to a certain extent, the blurring of the image produced by the sun not being a single luminous point. Number 4 method also economises 1878. | The Magic Mirror of Japan. 14] the light best, and if the screen is distant, may be employed to pro- duce a large figure of the pattern on the back of the mirror, but the result is not nearly as beautiful as that obtained by either of the former three methods, the first two in particular of which, if the mirror is placed in a darkened room, at about fourteen feet distance: from the luminous point produced by a tropical sun, cause the reflec- tion on the wall to assume an appearance startling even to an educated mind, and which might well have brought to the feet of the magician the ignorant poor of the middle ages. Referring to the arrangement of mirror and lens shown in fig. 4, and remembering the reasoning employed in the case of figs. 1, 2, and 3, we Should conclude that if a portion, AB, of the mirror is more concave than the rest, this portion ought to appear as bright on a dark ground if the screen be held in the positions 1, 2, or 4, since, in all these, DE is less than CD or EF, but if it be held at any point, 3 in the region between the principal focus P and JJ, then, since here DE is greater than CD or EF, the concave portion ought to appear as dark on a relatively light ground, while at JJ, the image being uniformly illuminated, the appearance of the pattern ought to dis- appear altogether. We should expect, then, that the passage of the screen, either through P or through JJ, ought to produce an inversion of the phenomenon if the theory that we are here advocating of the Japanese mirror be correct. iG. 5: Again, imagine the lens LL to gradually move up to the mirror until it attains a very near position, as in fig. 5, then an inspection of the direction of the rays shows that any concave part, AB, of the mirror must appear on the screen as light on a dark ground for all points between the lens and the principal focus P, but that it will be seen as dark on a relatively light ground for all positions of the screen 142 Profs. W. E. Ayrton and John Perry. | Deex #2: in the region beyond P. On arranging the light as in fig. 4, and placing the screen successively in the positions 1, 2, 3, JJ, and 4, afterwards moving the lens up to the Japanese mirror, until the distance between it and the mirror was less than the focal length of the lens, we found that the experiments bore out, in every detail, the results that must follow from the ‘inequality of curvature theory.” Returning now to fig. 3, in which it was first shown that a con- verging beam produced an inversion of the phenomenon, we find it impossible to obtain a distinct dark image of the pattern on a light ground by the employment of one converging lens only. This is partly due to the fact that here we are dealing with diverging pencils of light falling on the screen, so that no true image of the pattern is formed; and partly caused by the blurring effect arising from a beam of sunlight, consisting of a number of slightly diverging pencils. This latter may be, to a certain extent, corrected, either by allowing a very small beam of sunlight to fall on the single converging lens, or by causing the sunlight to be brought first to a focus by one lens, and then with a second lens at several feet distance, forming another con- vergent pencil of light, in which the convergent mirror is placed. Guided by all that proceeds, we are led to the undoubted conclusion, that the third of the proposed explanations is the correct one, namely, that the whole action of the magic mirror arises from the thicker portions being flatter than the remaining convex surface, and even being sometimes actually concave. The next question arises, why is there this difference in the curvature of the different portions of the surface? The experience that one gains from an examination of a large number of Japanese mirrors supplies, in part at any rate, the answer to the question. No thick mirror reflects the pattern on the back, not one of the many beautiful mirrors exhibited at the National Exhibition of Japan in 1877, and which we were so fortunate as to be able to experiment with ina darkened room with a bright luminous point at some twelve feet dis- tance, shows the phenomenon in the slightest degree; some good old mirrors in the museum of the Imperial College of Engineering, and which belonged to the family of the late Emperor, the Shogun, of Japan, fail to reflect any trace of a design, and some old round mirrors without handles, which we have also tried, are, with the exception of one about six inches in radius, and for which the owner asked many pounds, equally unsuccessful. Now this in itself, independently of the erroneous idea regarding stamping, is almost sufficient to negative Mr. Prinsep’s idea ‘‘ that part of the metal was by this stamping rendered in a degree harder than the rest, so that in polishing it was not worn away to the same extent.” Again, it is not that the pattern is less clearly executed on the backs of these choice mirrors, since the better 1878. ] The Magic Mirror of Japan. 143 the mirror the finer and bolder is the pattern, but what is especially noticeable is that every one of these mirrors is as a whole far thicker than an ordinary Japanese mirror, and its surface 1s much less convex. This naturally led us to inquire, how are Japanese mirrors made con- vex ? are they cast so, or do they acquire this shape from some subse- quent process? In the article ‘‘ Miroirs”’ in “ Les Industries Anciennes et Modernes de l’Empire Chinois,”’ nothing is said on this point, and the paper communicated by M. Julien on the Chinese Magic Mirror to the French Academy, is equally silent on this subject. Professor Pepper says, ‘‘ Are the mirrors cast 1 a double mould one side of which is in intaglio and one side in relievo ?’’ but has no information by which he can answer this question. We also were quite unable to gain any assistance from foreign or from Japanese books or manu- scripts regarding the method by which the convexity observed in almost all Japanese mirrors is produced, and were consequently com- pelled to make inquiries ourselves among mirror makers. Now although shops where mirrors are sold are common enough in Tokio, workshops where they are made are very difficult to find. A workshop was said to exist at Oji, but after a long search in this suburb of Tokio we found only one old woman and a little mercury amalgam in a small hovel about six feet by four, as the representative of the mirror in- dustry. As women are supposed to know nothing in Japan, it was useless to make inquiries of her: another search made on a subsequent occasion in a different direction only elicited the information that mirrors were not made at that time of the year, as the moulds were frost- bitten. Mirror-sellers, mirror-polishers we could find, but nobody in Tokio seemed to cast mirrors. We have since found out that this is really the case, since all the common mirrors come from the ancient capital Kioto, about 400 miles to the south of Tokio, and it is only when some special order is given that mirrors are made in the capital. However, at last we lighted on some mirror makers and sellers com- bined, from whom Mr. Kawaguchi (one of the assistants to the Pro- fessor of Natural Philosophy at our College), in the course of many conversations, extracted much valuable information. As a large por- tion of this is not to be found, as far as we aware, in any books, and as it bears upon the explanation of the magic mirror given in this paper, it naturally finds a place here. Composition used in Making Mirrors.—In regard to the composition of the mirrors the following seems to be the metal-mixture employed in Tokio :— Mirrors of First Quality. 144 Profs. W. E. Ayrton and John Perry. [| Dee. 127 Mirrors of Second Quality. Copper...) 4). ) See wae 81°3 parts EDRs ac nied iteraihes egy eae Me sume as BRoyay hue iiyo\shirome yr en (ia ehadepHeBwesis/ a6 Dr Ay meee Mirrors of Third Quality. Copper inthe sce ee ee ert ote 87:0 parts Di dae) cect os a ea re i car k Oi nsiues LE comstabngesit\eray Sc ic 6's 4 oo See Aro. 4.558 Mirrors of Fourth Quality. Copper ys: cesar nurs eck uc cide 81°3 parts. Tori jshiromes hee eeetaee eyes iee: LG Diet ape Tyo Shinome siya gd croc sat otersiets DeAi dee Mirrors of Fifth Quality. COpDeia hier tac biscuits ee teenie, cha. aud 715 parts. Mortis hiro nae ju. vseoeegaikeeoiene ok Eesha eG Tyo shirome is the name given to a natural sulphide of lead and an- timony taken out of the impurities of the lead ore from the mines of the province Iyo, in the island Shikoku. Tori shirome is a shirome containing an admixture of copper. In vol. iv of the ‘‘ Transactions of the Asiatic Society of Japan,’ Dr. Geerts gives the metal-mixture employed in one of the largest mirror foundries in Kioto as foilows :— Mirrors of First Quality. LDC UNA Mee marche eee MER LEE ) parts ARs a NODS SRA a ae Lorre Copper tee ei teh a ee SO Mrs Mirrors of Inferior Quality. ieaidety. AER OLR BORE Ha caae 10 parts ShiromeS Ae MOE eee eee Ee LOC eas Copperctte me riot tis vie ceee ae SO0mie4 MM. Champion and Pellet give as the result of their analysis of the material of Chinese mirrors :— Copper oe eae een ne eects 50°8 parts. ane ee Lee tie a ie eee Cages TUS : VAD Cee OR Oe PAKS n Al chk Binet SDPO i gs 1 WEEKS eri a a tae, aa nics Medi One. ees One of the chief of the Tokio mirror makers tells us he never puts: ordinary lead into the mixture, since he finds this makes the face of 4 1 ‘ . a 1878. ] The Magic Mirror of Japan. 145 the mirror very difficult to be amalgamated ; also that, in casting, the lead comes to the surface and spoils the mixture. Zinc he also finds has the same effect. But as a small amount of lead is required to be inserted in the composition to prevent the metal from becoming too brittle, the shirome or sulphide of lead and antimony is employed. The chief sources of this shirome arranged in order of merit are the provinces in the south of Japan, called— 1. Lyo, in the island Skikokn, 2. Shekishu, 3. Choshu, 4, Tosa, in the island Shikoku, but the shirome coming from the last province, Tosa, cannot be used for mirrors, as it contains too much lead. The mirrors of the first quality are only manufactured on receipt of a special order, and new mirrors of even the second and third qualities are rarely found ready made. The ordinary stock of the shops con- sists of mirrors of the fourth quality, in which there is no tin. The absence of both tin and the Iyo shirome in the composition of the fifth quality is found to make the mirrors give a pale reflection, from the difficulty of amalgamation, and so the fifth composition is not often used. The composition for the common mirrors is made at the copper mines and forwarded to the various mirror foundries. Formerly the metal for mirrors was extensively prepared at Kioto, but the trade is dying out now, and is said to have been slowly diminishing for the last hundred and thirty years, at the commencement of which period it had reached its maximum. Moulds for Mirrors.—The most striking feature of the moulds is that while practically all Japanese mirrors are convex, the surface of each half of the mould is quite flat. The material used for making the mould is a mixture of a special kind of clay (found near Tokio and Osaka) with water and straw-ash. ‘T'wo suitable slabs having been formed from this plastic compound with the aid of wooden frames, a thick layer of half liquid mixture of powdered old crucibles, or of a fine powder called to-no-ko, made from a soft kind of whetstone, is spread on them. The design for the back of the mirror is then cut directly on one half of the mould, or a sketch drawn on paper is first stuck on and used as a guide in cutting the design in the clay. Sometimes, but rarely, the design is stamped in the clay with a pattern wood-block cut in relief hike the proposed back of the mirror. After the design is complete a rim of the same material as that used in the construction of the mould, and having a thickness equal to that desired for the mirror, is attached to one half of the mould. The two halves are then dried in the smoke of a pine tree fire, pressed and tied together, and laid in the casting 146 Profs. W. E. Ayrton and John Perry. [Dee mhz box at an angle of 80° with the horizon, the half of the mould on which the design has been cut being uppermost. Finally, the molten speculum metal is run into a number of moulds at the same time, which, when cold, are broken up and the castings removed. Mirrors cast in a mould, in which the design has been cut by hand, are called ichi mai buki, “‘ mould used once,” and are regarded as “ artists’ proofs,” as the design on the back is well defined. To form subsequent moulds the two halves are pressed, when the clay is wet, on an ichi mai buki mirror, and the pattern is this way transferred, but the designs on the backs of the mirrors cast in such moulds are not as clear as on an icht mat buki mirror, which therefore sells for a much higher price. Curving the Surface-—The rough mirror is first scraped approxi- mately smooth with a hand-scraping tool, and as this would remove any small amount of convexity, had such been imparted to it in cast- ing, it is useless to make the mould shghtly convex. If, however, a convex or concave mirror of small radius is required, then the surface of the mould is made concave or convex. On the other hand, to pro- duce the small amount of convexity which is possessed by ordinary Japanese mirrors the following method is employed, if the mirror is thin, andit is with thin mirrors we have especially to deal, since it is only in these mirrors that the apparent reflection of the back is observed. The mirror is placed face uppermost flat on a wooden board, and then scraped or rather scratched with a rounded iron rod about half an inch in diameter and a foot long, called a megebo, ‘ dis- torting rod,” so that a series of parallel scratches is produced, which causes the face of the mirror to become convex in the direction at right angles to the scratches, but to remain straight parallel to the scratches, in fact 1t becomes very slightly cylindrical, the axis of the cylinder being parallel to the scratches. This effect is very clearly seen by applying a straight-edge in different ways to the face of an unpolished mirror which has received a single set of scratches only. A series of scratches is next made with the megebo in a direction of right angles to the former, a third set intermediate between the two former, and so on, the mirror each time becoming slightly cylindrical, the axis of the cylinder in each case being parallel to the line of scratches, so that eventually the mirror becomes generally convex. Some work- men prefer to make the scratches with the megedo in the form of small spirals, others in the form of large spirals, but the general principle of the method employed with their mirrors appears to be always the same,—the face of the mirror is scratched with a blunted piece of iron, and becomes slightly convex, the back, therefore, becoming concave. After the operation with the “‘ distorting rod” the mirror is very slightly scraped with a hand-scraping tool to remove the scratches 1878. | The Magic Mirror of Japan. 1AT and to cause the face to present a smooth surface for the subsequent polishing. In the case of thick mirrors the convexity is first made by cutting with a knife, and the “distorting rod” applied afterwards. But in connection with this cutting process of thick mirrors there is one very interesting point. If the maker finds on applying from time to time the face of the mirror to a hard clay concave pattern, and turn- ing it round under a little pressure, that a portion of the surface has not been in contact with the pattern, in other words, that he has cut away this portion too much, then he rubs this spot round and round with the megebo until he has restored the required degree of convexity. Here again then scratching on the surface produces convexity. Now, why does the scraping of the “ distorting rod” across the face of the mirror leave it convex? During the operation it is visibly concave. The metal must receive then a kind of “ buckle,” and spring back again so as to become convex when the pressure of the rod is removed. It might in such a case reasonably be expected that. the thicker parts of the mirror would yield less to the pressure of the rod than the thinner, and so would be made less convex, or even they might not spring back, on the withdrawal of the rod, and so remain actually concave. Again, since we find that scraping the face of a mirror is the way in which it is made convex, and the back therefore concave, we might conclude that a deep scratch on the back would make the back convex and the face slightly concave. Such a concavity, as we have proved, would explain the phenomenon of the bright line appear- ing in the reflection of sunlight on the screen which was observed by Professor Atkinson to correspond with the scratch on the back. lt appears then that the magic of the Hastern mirror results from no subtle trick on the part of the maker, from no inlaying of other metals, or hardening of portions by stamping, but merely arises from the natural property possessed by thin bronze of buckling under a bending stress, so as to remain strained in the opposite direction after the stress is removed. And this stress is apphed partly by the ‘* distorting rod,” and partly by the subsequent polishing, which, in an exactly similar way, tends to make the thinner parts more convex than the thicker. Polishing. —After the scratches produced by the megebo are removed the mirror is first polished with a whetstone called either iyodo, ““ whetstone from the province of Lyo,” or shiroto, “ white whetstone.” Afterwards a whetstone called tenshimado, ‘‘ whetstone from the pro- vince T'sushima,” or the powder fo-no-/o, previously described, is used. Thirdly, a piece of charcoal, prepared from the ho tree (Magnolia hypoleuca) is rubbed over the surface. The face now becomes fairly smooth, but it still generally contains some few cavities; these the maker fills up from a stock of copper balls of various sizes which he 148 Dr. Hopkinson on Torsional | Decm2: has at hand, and which are obtained from the cinders of a copper- furnace. The cavities when thus filled up are well rubbed so as to escape notice, but they may usually be detected by looking at the mirror obliquely. It was perhaps the presence of these bits of copper in the mirror which Ou-tseu-hing saw broken up in the 13th century, that misled him into concluding that the phenomenon of the magic mirror was produced by the mlaying of denser copper in a portion of the face exactly corresponding with the design on the back. When the face of the mirror has been made quite smooth, an amalgam consisting, according to the Tokio makers, of half tin and half mercury, with perhaps a trace of lead, or of Tin 69°36 per cent., Mercury 30 ap Lead C2040 according to the analysis of MM. Champion and Pellet (“ Industries de Empire Chinois’’) is rubbed over the surface with a stiff straw brush or with the hand. The mirror is finally wiped clean with a soft kind of paper, mino-gamz, ‘‘ paper from the province Mino,” which is con- sidered to scratch the surface less than silk. Leather was formerly never employed in polishing, as it would have been considered im- pious to pollute so holy a thing as a mirror by touching it with the skin of an animal; for under the old feudal system in Japan, workers in skins, saddlers, and others, belonged to the Hta or pariah class. When mirrors possessed by private people require brightening up, im consequence of the surface tarnishing, the paste produced when razors are sharpened on a hone is usually rubbed over the face of the mirror. qi. “On the Torsional Strain which remains in a Glass Fibre after release from Twisting Stress.” By J. HOPKINSON, D.Sc., F.R.S. Received October 4, 1878. It has long been known that if a wire of metal or fibre of glass be for a time twisted, and be then released, it will not at once return to its initial position, but will exhibit a gradually decreasing torsion in the direction of the impressed twist. The subject has undergone a good deal of investigation, especially in Germany. The best method of approximating to an expression of the facts has been given by Boltzmann (“ Akad. der Wissensch. Wien,” 1874). He rests his theory upon the assumption that a stress acting for a short time will 1878. | Strain in a Glass Fibre. 149 leave after it has ceased a strain which decreases in amount as time elapses, and that the principle of superposition is applicable to these strains, that is to say, that we may add the after-effects of stresses, whether simultaneous or successive. Boltzmann also finds that, if @(t)z be the strain at time ¢ resulting from a twist lastinga very short time 7, at time t=0, A(t) == , where A is constant for moderate values of #, but decreases when ¢ is very large or very small. A year ago I made a few experiments on a glass fibre which showed a deviation from Boltzmann’s law. A paper on this subject by Kohlrausch (“ Pogg. Ann.,”’ 1876) suggested using the results of these experiments to exa- mine how Boltzmann’s law must be modified to express them. Pro- fessor Kohlrausch’s results indicate that in the cases of silver wire and of fibre of caoutchouc Boltzmann’s principle of superposition is only approximate, and that in the case of a short duration of twisting p(t) == where a is less than unity; in case of a long duration of twisting he uses other formule, which pretty successfully express his results, owing in part no doubt to the fact that in most cases each determination of the constants applies only to the results of one dura- tion of twisting. In a case like the present it appears best to adopt a simple form involving constants for the material only, and then see in what way it fails to express the varying conditions of experiment. In 1865 Sir W. Thomson published (‘‘ Proceedings of the Royal Society ”’) the results of some experiments on the viscosity of metals, the method being to determine the rate at which the amplitude of torsional vibra- tions subsided. One of the results was that if the wire were kept vibrating for some time it exhibited much greater viscosity than when it had lone been quiescent. This should guard us from expecting to attain great uniformity in experiments so roughly conducted as those of the present paper. 2. The glass fibre examined was about 20 inches in length. Its diameter, which might vary somewhat from point to point, was not measured. The glass from which it was drawn was composed of silica, soda, and lime; in fact, was glass No. 1 of my paper on “Residual Charge of the Leyden Jar” (‘‘ Phil. Trans.,” 1877. In all cases the twist given was one complete revolution. The de- flection at any time was determined by the position on a scale of the image of a wire before a lamp, formed by reflection from a light con- cave mirror, as in Sir W. Thomson’s galvanometers and quadrant elec- trometer. The extremities of the fibre were held in clamps of cork ; in the first attempts the upper clamp was not disturbed during the experiment, and the upper extremity of the fibre was assumed to be fixed; the mirror also was attached to the lower clamp. This arrange- ment was unsatisfactory, as one could not be certain that a part of the VOL. XXVIII. M 150 Dr. Hopkinson on Torsional Dee: observed after-effect was not due to the fibre twisting within the clamps and then sticking. The difficulty was easily avoided by em- ploying two mirrors, each cemented at a single point to the glass fibre itself, one just below the upper clamp, the other just above the lower clamp. The upper mirror merely served by means of a subsidiary lamp and scale to bring back the part of the fibre to which it was attached to its initial position. The motion of the lower clamp was damped by attaching to it a vane dipping into a vessel of oil. The temperature of the room when the experiments were tried ranged from 13° C. to 13°8° C., and for the present purpose may be regarded as constant. The lower or reading scale had forty divisions to the inch, and was distant from the glass fibre and mirror 38% inches, excepting in Experiment V, when it was at 373 inches. Sufficient time elapsed between the experiments to allow all sign of change due to after-effect of torsion to disappear. In all cases the first line of the table gives the time in minutes from release from torsion, the second the deflection of the image from its initial position in scale divisions. Experiment I.—The twisting lasted 1 minute. Ai Sinn He Ay nga a LD Bo Ao 2 ON eames Seale divisions |. 22° 13" 97 952) 4) 3 Hxperiment I].—The twisting lasted 2 minutes. ONS SRS nee ee eae I 2 8 4 5 7 Oe Ones Scale divisions.. 38 25 18 15 13 10 8 42 34 | Experiment III.—Twisted for 5 minutes. CGO EAE a MOORS Fo Lo as 3 4 aa Scale divisions ........ 64 51 415 35} 32 265 bhatatorreh sume voneks eve ie ceeee 10 159 22 Smale Scale divisions ........ ZS Av wilds ane Experiment 1V.—Twisted for 10 minutes. 1) 0) 9) 73 ae ns Scale divisions.... 106 85 66 57 492 372 81 G ipsa ogy cease eeag 15 25 45 120 170 Scale divisions .... 244 18 13 7 6 Experiment V.—Twisted for 20 minutes. ET TE eT RE a og EE i OM hn Bae PRAY 5 7, LO Scale divisions .... 110 89 75 68 614 52 44 renee e e auven en eh Ny gee 15) © 25) F40i06 OHO Ora RROD Scale divisions..... . Bde 2020 2 vISh dorama 1878.] Strain in a Glass Fibre. 151 Experiment VI.—Twisted for 121 minutes. «Ue Rana yee mee to) | Sh Ae 7 Scale divisions. 191 170 148 136 1264 1192 1084 i eres HO ase) 30. 652" 90) 1200589 Scale divisions. 97 844 632 414 34 28 38 It should be mentioned that the operation of putting on the twist and of releasing each occupied about two seconds, and was per- formed half in the second before the epoch t= 0, and half in the second after or as nearly so as could be managed. The time was taken by ear from a clock beating seconds very distinctly. 3. The first point to be ascertained from these results is whether or not the principle of superposition, assumed by Boltzmann, holds for torsions of the magnitude here used. If the fibre be twisted for time T through angle X, then the torsion at time ¢ after release will be X {y (T+7¢)—w (¢)} where v(t) =So (8) dt. If nwT=4+4+4+... we may express the effect of one long twist in terms of several shorter twists by simply noticing that XV) —VE+T) HAV O—-VE+eyyt+{yG+h)—vi+ats)} +{P(tthth)—Viththt+b)}+, &€.] Apply this to the preceding results, calculating each experment from its predecessor. Let x be the value of y (I+¢)—w (#), that is, the torsion at time ¢, when free, divided by the impressed twist measured in same unit; we obtain the following five tables of com- parison. Results for T=2 compared with those from T=1. t 1 2 o A, 5 7 a2; observed.... 0°00195 128 092 O77 O66 O51 x; calculated... 0°00199 112 082 064 051 040 t Dine veX0 ama ee) #; Observed..... O41 023 018 2, calculated .. 029 O16 Results for T=5 compared with those from T=2 and T=1. t 1 3 4 5) £1 LO a, observed.... 0°00328 262 212 182 164 136 110 a, calculated... 0°00323 233 181 156 186 108 198 t la eh oe OO elo “mooserved.... 0o¢, O72 086 O10 a, calculated... O66 O47 mM 2 152 ie Dr. Hopkinson on Torsional (Dee: 22, Results for T=10 compared with those from T=5. é 1 Us OR OR 7:2) 10 a, observed.... 0°00544 435 838 292 253 192 159) pealculated. « ©, 02.1469 1398 839) 3200/2 sGNnae f 1S es as 6120 ©4170 a, observed.... 125 092 067 036 031 a, calculated... 161 130 088 Results for T=20 compared with those from T=10. t Il 2 5) 4 9) eo IO) a: observed.... 0°00580 470 398 358 3827 276 234 a; calculated... 0°00587 483 430 384 3856 312 266 t ld Zo) 40% 560T aes0i a ale0 a, observed.... 188 140 I111 085 072 066 er calcnlaveds i oliaalors 1 alao a 100 BO S4: Results for T=121 compared with those from T=20. t 4 1 2 3 4, 5 7 2, observed... 0:00979 871 758 697 648 612 556 z; calculated... af 1070 950 880 830 780 °° 730 t 10° 15 230) (65 4) 90 a ORasS a: observed... 497 483 325 212 174 144 18 x; calculated.. 670 600 500 380 3650 In examining these results it must be remembered that those for small values of T are much less accurate than when T is greater, for the quantity observed is smaller but is subject to the same absolute error ; any irregularity in putting on or releasing from the stress will cause an error which is a material proportion of the observed deflection. For this reason it would be unsafe to base a conclusion on the experi- ments with T=1 and T=2. The three last tables agree in indicating a large deviation from the principle of superposition, the actual effect being less than the sum of the separate effects of the periods o stress into which the actual period may be broken up. Kohlrausch finds the same to be the case for india-rubber, either greater torsions or longer durations give less after-effects than would be expected from smaller torsions and shorter periods. 4. Assuming with Boltzmann that w=, we have at time ¢ after termination of a twist lasting time T, a,=A{log (T +1) —log #}, the logarithms being taken to any base we please. 'The results were 1878. | Strain in a Glass Fibre. 153 = plotted on paper, x, being the ordinate and log —— the abscissa; if the law be true we should find the points all ae on a straight line through the origin. For each value for T they do lie on straight lines very nearly for moderate values of ¢; but if T is not small these lines pass above the origin. When # becomes large the points drop below the straight line in a curve making towards the origin. This devia- tion appears to indicate the form oO——, a being less than, but near to, unity. If a=0°95 we have a fairly satisfactory formula. a= A( TTP oP) aihiéte we ahead nei In the following Table the observed and calculated values of a; wher T=121 are compared, A’ being taken as 0°032. t “ il 2 3 4, 5 7 g, observed.... 0°00979 871 758 697 648 612 556 a; calculated... 0°00976 870 755 691 6438 600 550 t Ore lor ah bo 9O™ T2000 589 a; observed.... 497 433 325 212 174 144 18 a; calculated... 498 429 320 ¥Y%18 176 147 42 To show the fact that A’ decreases as T increases if a be assumed con- stant, I add a comparison when T=20, it being then necessary to take A’=0:037. t 1 2 3 A. 5 7 10 paguserved.... 000580 470 398 358 327 2 a; calculated... 0°00607 485 422 370 337 2 t om eczou 405” 60 57805» 100 e@peenved.... 188 140 J1l 085 072 066 g#, ealenlated... 185 125 089 067 052 041 A better result would in this case be obtained by assuming a=0°92, or =0°93 in the former case with A’=0:021. Probably the best result would be given by taking A constant, and assuming that a increases with T. Taking the formula ¢(¢)=- ees experiments give values of A ranging from 0°0017 to 0: we Boltzmann for a fibre, probably of a quite different composition, gives numbers from which it follows that A=0-00386. 5. In my paper on “Residual Charge of the Leyden Jar’ that 154 Rev. 8. Haughton on Physical Geology. [Dec 12, subject is discussed in the same manner as Boltzmann discusses the after-effect of torsion on a fibre, and it 1s worth remarking that the results of my experiments can be roughly expressed by a formula in which oO=—, . For glass No. 5 (soft crown) «=0°65, whilst for No. 7 (light flint) it 1s greater; but in the electrical experiment no sign of a definite deviation from the law of superposition was detected. IV. “ Note in correction of an Error in the Rey. Dr. Haughton’s Paper ‘ Notes on Physical Geology. No. V” (“Proc. Roy. Soc.,” vol. xxv, p. 447). By the Rev. SAMUEL HAUGHTON, M.D., Professor of Geology in the University of Dublin, F.R.S. Received October 9, 1878. In my paper read 20th June last, and published in the “ Journal of the Royal Society,” there is an error in p. 450 which I wish to correct. Referring to the geometrical proof of Mr. Darwin’s theorem, I state that from cusp to cusp of the cycloidal wabble occupies 1523 days; this is an error, as it should be 305 days, as can be shown geometri- cally. Let yz, y’z', be two successive positions of the line joining the axes of rotation and figure; produce them to meet at C, which will be the centre of curvature, because yx and y'w', are normals to the cycloidal are yy’; it is well known that yC, (radius of curvature) is double yw (chord of generating circle) or double y’x; therefore the angle yay’ is double the angle yCy'; but yay’ measures the angular velocity of the wabble, when z is supposed at rest; therefore the angular velocity of yz is only half that of the wabble, if the axis of figure were at rest. Hence in 305 days, yx will turn through 180° only, and not 360°. 1878.] Mr. J. E. H. Gordon on Electrical Constants. 155 This correction, when introduced into my calculation of Mr. Dar- win’s problem, p. 182, will double the result, and give 19,350 years to represent the 19,200 years, found by Mr. Darwin. I would wish to add, that Mr. Darwin, in a letter to myself, pro- poses to call the cycloidal wabble described by him, a “ lopsided wabble,” as distinguished from the simple circular ‘‘ wabble”’ described by me; the one being caused by continuous motion of the axis of figure, and the other caused by sudden displacement of that axis. V. “Measurements of Electrical Constants. No. I]. On the Specific Inductive Capacities of Certain Dielectrics.” Part I. By J. E. H. Gorpon, B.A. Camb. Communicated by Pro- fessor J. CLERK Maxweuu, F.R.S. Received October 21, 1878. (Abstract. ) A paper of mine with the above title was communicated. to the Royal Society by Professor J. Clerk Maxwell, F.R.S., on March 9th, 1878. It was read on March 28th, and an abstract of it appeared in the “* Proceedings.”’* In the course of the summer it was pointed out to me that owing to a mistake in the formula of calculation all the results were wrong. I, therefore, requested permission to withdraw my paper, in order to re- calculate the results. The new values of K arrived at led me to make some determinations of refractive indices and to re-write the theoretical deductions at the close of the paper. I now beg through Professor Maxwell to present the paper in an amended form, in the hope that it may be found not entirely unworthy of the attention of the Royal Society. As it would be impossible within the limits of an abstract to give any intelligible account of the new method of experiment (due to Pro- fessor Maxwell), which has been employed, I will merely give the table of results, reserving all discussion and explanation until the publica- tion of my paper in full. I may, however, state that the method is a zero method, that the electrified metal plates never touch the dielectrics, and that the elec- trification, which is produced by an induction coil, has an electromo- tive force equal to that of about 2,050 chloride of silver cells, and is reversed some 12,000 times per second. * Ante, vol. xxvii, p. 270. 156 Mr. J. E. H. Gordon on Electrical Constants. [Dee. 12, Results. Dielectric. Glass, Slabs about 1 inch Ky thick. Double extra dense flint ........ 3 1639 Chance’s optical ) Extra dense flint............. ...3 0536 glass. hightpeimi hee 4.1. sclecen eect 3 0129 DBLEWRCL. CHO p aN eal eA en eA iy uy on 6, < 3 1079 Common plate, { No. 1 3 2581 2 slabs. No. 2 3 ae)! ie — No. 1 2 °2697 Ebonite, 4 slabs, } No. 2 2 2482 A Tonic, pen 93097 ( ttttettt ees 2 2838 No. 4 2°3077 Bestiquality,euttaspercia i... 0% 1 viele eiaele eee 2 4625 Chattertonss compound 2c... +4. 40 eee 2 5474 lack VF eso aot walle ete ae eee 2 -2200 Andia-mbber : vulcanised’.... cc ¢%.2+ ee ce ocite tee 2°4969 Solid paraffin, sp. ermal. O109s "Now 1 9940 Melting point | No. 2 1 -9784. 68° C. 6slabscut (No. 3 1 -9969 : ea in planing ma- | No. 4 2-0106( MOAR saiiiag chine. Results | No. 5 1 9654 corrected for ca- | No. 6 2 0143 vities. Shellac mew seas as Caen el eee eee 2 7464 Sullolawry Ler ee Rvsicee Cali wesene sehen le Oikege Si erent nea 2 °5793 lByIstll olawKeley OH CERIN 545005 56000000 000 As .0'5 0 1 8096+ The following table compares the refractive indices of the transpa- rent dielectrics with the square roots of the specific inductive capacities. In cases where there is a wide difference » is taken from books on physics; wherever there was a close agreement it was carefully deter- mined by the author, except in the case of paraffin, where the value is that given in Maxwell’s “ Hlectricity.” * Messrs. Gibson and Barclay, “Phil. Trans.,” 1871, using a method entirely different from mine, obtained K =1°977 for paraffin. Correcting for a slight difference of density, I find that if they had used my paraffin their result would have been 1°9833. ft I am not quite certain of the accuracy of this result. 1878.] Mr. J.N. Lockyer. Researches in Spectrum Analysis. 157 ai tl 2 ; Te Nearest value| Ray for which « Dielectric. of pw. is nearest. Double extra dense flint alaska waite ssacet | Lo F783 1-74.60 I ———_——— Band in extreme Extra dense flint....... 1 7474 16757 violet in mag- ———_—_—_—__—_—. =e ———————| nesium spark Sieh Hint 2. +6. 1°7343 1°5113 spectrum. Heardicrown.,........- 1 -7629 1 -5920 Plate glass ............ 1 8009 1 543 Per einin 6 0p On Doe aeeeeoe 1°4119 1-422 Rays of infinite wave length. ST LIONS bo on OO OeOOIOInOE 1 6060 2°115 Bisulphide of carbon.... 1 3456 16114 ) —$<— VI. “Researches in Spectrum Analysis in connexion with the Spectrum of the Sun. No. VII.” By J. N. LockyEr, F.R.S. Received December 11,1878. Read December 12. Discussion of the Working Hypothesis that the so-called Hlements are Compound Bodies. Part I. It is known to many Fellows of the Society that I have for the last four years been engaged upon the preparation of a map of the solar spectrum on a large scale, the work including a comparison of the Fraunhofer lines with those visible in the spectrum of the vapour of each of the metallic elements in the electric arc. To give an idea of the thoroughness of the work, at all events in in- tention, I may state that the complete spectrum of the sun, on the scale of the working map, will be half a furlong long ; that to map the metallic lines and purify the spectra in the manner which has already been described to the Society, more than 100,000 observations have been made and about 2,000 photographs taken. In some of these photographs we have vapours compared with the sun ; in others vapours compared with each other; and others again have been taken to show which lines are long and which are short in the spectra. I may state by way of reminder that the process of purification con- sisted in this: When, for instance, an impurity of Mn was searched for in Fe, if the longest line of Mn was absent, the short lines must also be absent on the hypothesis that the elements are elementary ; if the longest line were present, then the impurity was traced down to the shortest line present. 158 Intensity in Sun o = JQ (ar > Mr. J. N. Lockyer. Researches in Spectrum [Dec. 12, Table I. Final reduction—Iron. Coincidences with Short Lines. i a as A ecoccs|soocesleccocelecce ecccce|seeecslecccceiooe ecccce|seeceslesaccaleecces eececs| ccocse |**22**|ecccce| soccvececeecoceves |eeovesseeves | ooo eee] cooces | ceeocge0e eecccelovovce | 92% **|ecccce |ooeveacvacccvee eoccce|scooce |*oeee%lece ecccce|seccee eceecleccoesl|ecccccsocccsccsvccsceveccossee® |ocoves| oe eccccc|scccee Cel oceves|cccvee| secor-| cee | 4 5 Teo eccceteccecce|eee _ _ Feel sogcee-ereOsccesosecgcor0e® _ _ Gee) # 0880) covvcreeeeoe| .. eee] coe eecccccce SHANE E SUa Na ome les Soteeradsdune tsar toascuasessectcol saaeee | oomet erect eM AREA Amati HOA Ne Aid oN DEAR A ANNOY ac bs A Fok Ete Cr ——__ Pvacveccecc|sccves|cocveteoe — eee ece ccc ecc gcse s FPO 080% | 200 oe 20200000 Coceccovccccececcoceceves occa COOOO OOOO OOOO ii) 1 We etieicc cab abaideca segue sae Seethive ce'ec ote ties cea soweswes’s ebobecionenseabel cases bere ss seep ececestce ee eCenea Cee ee enamel Neanacastiowsessasvons ecaidicegaee recess decele secede scceeea ces ceeces Since ctl secmeeclddcesecoewesseae te ceemmIMIUE 3 00000 009000 008000 G00 000 090000000 099000 090000 000000000008 000000000000 1878.] Analysis in connexion with the Spectrum of the Sun. 159 Table II. Final reduction—Titanium. -,_ |Wave-length PEERS) and length Coincidences with Short Lines. in Sun. of line | | seecee | Pe eeselecsces|coeccs|eeecee Soeees no | | | seeves|caesee|savese| see Peccee| cesece| ceseee|sescce|sosecs|seeese/see _ seosee | cc ece|eascce| eeesce|sesees|eseces oo | | | f sec cceleseccccesene |teesseescces |sesses|esccos|ses no iw acc cccese | ses vcsees coe|sesces|eccces| seeses| sasecsees = c| Becccecesccscessees |seecscsessee |seesesisos “5 (JX) | (vy) on seer ee soevescssses® |seeececessesceseses® |eescssees i) | th Pee eee sere cress eee® [see ceeseseassenseee [Pee eOeSsseeresssesesssseesssesseseee P| . . . ° . ° . ° . . ° . . ° . . . . . . ° ° . . . ° . ° ° ° . . Fee eco secs oseeseceeesessccsesesene longest longest bo The Hypethesis that the Hlements are Simple Bodies does not include ail the Phenomena. The tinal reduction of the photographs of all the metallic elements in the region 39-40—a reduction I began in the early part of the pre- sent year, and which has taken six months, summarised all the obser- vations of metallic spectra compared with the Fraunhofer lines accu- mulated during the whole period of observation. Now this reduction has shown me that the hypothesis that identical lines in different spectra are due to impurities 1s not sufficient. I shall show in detail in a subsequent paper the hopeless confusion in which I have been landed. I limit myself on the present occasion to giving tables show- ing how the hypothesis deals with the spectra of iron and titanium. We find short-line coincidences between many metals the impurities of which have been eliminated, or in which the freedom from mutual impurity has been demonstrated by the absence of the longest lines. Hvidences of Celestial Dissociation. It is five years since I first pointed out that there are many facts 160 Mr. J. N. Lockyer. Researches in Spectrum [Deec. 12, and many trains of thought suggested by solar and stellar physics which point to another hypothesis, namely, that the elements themselves, or at all events some of them, are compound bodies. In a letter written to M. Dumas, December 3, 1873, and printed in the Comptes Rendus, I thus summarised a memoir which has since appeared in the Philosophical Transactions. “Tl semble que plus une étoile est chaude plus son spectre est simple, et que les éléments métalliques se font voir dans l’ordre de leurs poids atomiques.* ‘¢ Ainsi nous avons: “1. Des étoiles trés-brillantes ou nous ne voyons que l’hydrogéne, en quantité énorme, et le magnésium ; “9. Des étoiles plus froides, comme notre Soleil, ot nous trouvons : H+Me+Na H+Mg+Na+Ca, Fe,...; dans ces étoiles, pas de métalloides ; “3. Des étoiles plus froides encore dans lesquelles tows les éléments mé- talliques sont ASSOCIES, ou leurs lignes ne sont plus visibles, et ou nous n’avons que les spectres des métalloides et des composés. “4, Plus une étoile est dgée, plus Vhydrogéene libre disparait; sur la terre, nous ne trouvons plus d’hydrogéne en liberté. “ Tl me semble que ces faits sont les preuves de plusieurs idées émises parvous. J’al pensé que nous pouvions imaginer une ‘ dissociation céleste,’ qui continue le travail de nos fourneaux, et que les métalloides sont des composés qui sont dissociés par la température solaire, pendant que les éléments métalliques monatomiques, dont Jes poids atomiques sont Jes moindres, son précis¢ment ceux qui résistent, méme a la tem- pérature des étoiles les plus chaudes.”’ Before I proceed further, | should state that while observations of the sun have since shown that calcium should be introduced between hydrogen and magnesium for that luminary, Dr. Huggins’ photographs have demonstrated the same fact for the stars, so that in the present state of our knowledge, independent of all hypotheses, the facts may be represented as follows, the symbols indicating the spectrum of. which the lines are visible :— Hottest Stars “S | H+Ca+Mg Sun H+Ca+Mg+Na+ Fe Cooler Stars =" = Me Na Fe Bie Lines o Coolest Fluted bands of | | | | | | Metalloids * This referred to the old numbers in which Mg=12, Na=23. 1878.| Analysis in connexion with the Spectrum of the Sun. 161 Following out these views, I some time since communicated a paper to the Society on the spectrum of calcium, to which I shall refer more expressly in the sequel. Differentiation of the Phenomena to be ohserved on the Two Hypotheses. When the reductions of the observations made on metallic spectra, on the hypothesis that the elements were really elementary, had landed me in the state of utter confusion to which I have already referred, I at once made up my mind to try the other hypothesis, and therefore at once sought for a critical differentiation of the phenomena on the two hypotheses. Obviously the first thing to be done was to inquire whether one hypothesis would explain these short-line coincidences which remained after the reduction of all the observations on the other. Calling for simplicity’s sake the short lines common to many spectra basic lines, the uew hypothesis, to be of any value, should present us with a state of things in which basic molecules representing bases of the so-called elements should give us their lines, varying in intensity from one condition to another, the conditions representing various compoundings. Suppose A to contain B as an impurity and as an element, what will be the difference in the spectroscopic result ? A in both cases will have a spectrum of its own ; B as an impurity will add its lines according to the amount of im- purity, as I have shown in previous papers. B as an element will add its lines according to the amount of disso- ciation, as I have also shown. The difference in the phenomena, therefore, il be that, with gradually-increasing temperature, the spectrum of A will fade, if it be a compound body, as it will be increasingly dissociated, and it will not fade if it be a simple one. Again, on the hypothesis that A is a compound body, that is, one compounded of at least two similar or dissimilar molecular groupings, then the longest lines at one temperature will not be the longest at another; the whole fabric of “impurity elimination,” based upon the assumed single molecular grouping, falls to pieces, and the origin of the basic lines is at once evident. This may be rendered clearer by some general considerations of another order. General Considerations. Let us assume a series of furnaces A... D, of which A is the hottest. Let us further assume that in A there exists a substance a by itself competent to form a compound body £ by union with itself or with something else when the temperature is lowered. 162 Mr. J. N. Lockyer. Researches in Spectrum [Dee. 12, Then we may imagine a furnace B in which this compound body exists alone. The spectrum of the compound f would be the only one visible in B, as the spectrum of the assumed elementary body a would be the only one visible in A. Fig. 1.* TM ET Fess AMAT An HNN ik Ct i CJ ans CJ ato = Cho > A lower temperature furnace C will provide us with a more com- pound substance y, and the same considerations will hold good. _ Now if into the furnace A we throw some of this doubly-com- pounded body y, we shall get at first an integration of the three spectra to which I have drawn attention; the lines of y will first be thickest, then those of 6; finally a will exist alone, and the spectrum will be reduced to one of the utmost simplicity. This is not the only conclusion to be drawn from these considera- tions. Although we have by hypothesis f, y, and 6 all higher, that is, more compound forms of a, and although the strong lines in the dia- eram may represent the true spectra of these substances in the furnaces B, C, and D, respectively, yet, in consequence of incomplete dissociation, the strong lines of 8 will be seen in furnace C, and the strong lines of y will be seen in furnace D, all as thin lines. Thus, although in C we have no line which is not represented in D, the in- tensities of the lines in C and D are entirely changed. In short, the line of a strong in A is basic in B, C, and D, the lines of 8 strong in B are basic.in C and D, and so on. I have prepared another diagram which represents the facts on the supposition that the furnace A, instead of having a temperature sufficient to dissociate 8, y, and 6 into a is far below that stage, although higher than B. It will be seen from this diagram that then the only difference in the spectra of the bodies existing in the four furnaces would consist in the relative thicknesses of the lines. The spectrum of the sub- * The figures between the hypothetical spectra point to the gradual change as the spectrum is observed near the temperature of each of the furnaces. 1878.| Analysis in connexion with the Spectrum of the Sun. 168 stances as they exist in A would contain as many lines as would the spectrum of the substances as they exist in D; each line would in Oam~O0 arv~ Wonw~ urnaces instead of in one or two Ss S turn be basic in the whole series o only. Application of these General Considerations to Impurity Elimination. Now let us suppose that in the last diagram (Fig. 2) the four furnaces represent the spectra of say, iron, broken up into different finenesses by successive stages of heat. It is first of all abundantly clear that the relative thicknesses of the iron lines observed will vary according as the temperature resembles that of A, B, C, or D. The positions in the spectra will be the same, but the intensities will vary ; this is the point. The longest lines, represented in the diagram by the thickest ones, will vary as we pass from one temperature to another. It is on this ground that I have before stated that the whole fabric of impurity elimination must fall to pieces on such an hypothesis. Let us suppose, for instance, that manganese is a com- pound of the form of iron represented in furnace B, with something else; and suppose again that the photograph of iron which I compare with manganese represents the spectrum of the vapour at the tempe- rature of the furnace D. To eliminate the impurity of iron in manganese, as I have eliminated it, we begin the search by looking for the longest and strongest lines shown in the photograph of iron, in the photograph of manganese taken under the same conditions. I do not find these lines. I say, therefore, that there is no impurity of iron in manganese, but although the longest iron lines are not there, some of the fainter basic ones are. This I hold to be the explanation of the apparent con- fusion in which we are landed on the supposition that the elements are elementary. 164 Mr. J. N. Lockyer. Researches in Spectrum [Dec. 12, Application of these Considerations to Known Compounds. Now to apply this reasoning to the dissociation of a known com- pound body into its elements— A compound body, such as a salt of calcium, has as definite a spectrum as a simple one; but while the spectrum of the metal itself consists of lines, the number and thickness of some of which increase with increased quantity, the spectrum of the compound consists in the main of channelled spaces and bands, which increase in like manner. In short, the molecules of a simple body and a compound one are affected in the same manner by quantity in so far as their spectra are concerned ; in other words, both spectra have their long and short lines, the lines in the spectrum of the element being represented by bands or fluted lines in the spectrum of the compound; and in each case the greatest simplicity of the spectrum depends upon the smallest quantity, and the greatest complexity (a continuous spectrum) upon the greatest. The heat required to act upon such a compound as a salt of calcium so as to render its spectrum visible, dissociates the compound according to its volatility ; the number of true metallic lines which thus appear is a measure of the quantity of the metal resulting from the dissocia- tion, and as the metal lines increase in number, the compound bands thin out. I have shown in previous papers how we have been led to the con- clusion that binary compounds have spectra of their own, and how this idea has been established by considerations having for a basis the observations of the long and short lines. It is absolutely similar observations and similar reasoning which I have to bring forward in discussing the compound nature of the chemical elements themselves. In a paper communicated to the Royal Society in 1874, referring, among other matters, to the reversal of some lines in the solar spec- trum, I remarked :*— ‘It is obvious that greater attention will have to be given to the precise character as well as to the position of each of the Fraunhofer lines, in the thickness of which I have already observed several anomales. J may refer more particularly at present to the two H lines 3933 and 3968 belonging to calcium, which are much thicker in all photographs of the solar spectrum [I might have added that they were by far the thickest lines in the solar spectrum] than the largest calcium line of this region (4226°3), this latter beg invariably thicker than the H lines in all photographs of the calcium spectrum, and remaining, moreover, visible in the spectrum of substances con- * “Phil. Trans.,” vol. clxiv, part 2, p. 807. 1878.] Analysis in connexion with the Spectrum of the Sun. 163 taining calcium in such small quantities as not to show any traces of the H lines. ‘“‘ How far this and similar variations between photographic records and the solar spectrum are due to causes incident to the photographie record itself, or to variations in the intensities of the various mole- cular vibrations under solar and terrestrial conditions, are questions which up to the present time I have been unable to discuss. An Objection Discussed. I was careful at the very commencement of this paper to point out that the conclusions I have advanced are based upon the analogies furnished by those bodies which, by common consent and beyond cavil and discussion, are compound bodies. Indeed, had I not been careful to urge this point the remark might have been made that the various changes in the spectra to which I shall draw attention are not the results of successive dissociations, but are effects due to putting the same mass into different kinds of vibration or of producing the vibration in different ways. Thus the many high notes, both true and false, which can be produced out of a bell with or without its fundamental one, might have been put forward as analogous with those spectral lines which are produced at different degrees of temperature with or without the line, due to each substance when vibrating visibly with the lowest temperature. ‘'T'o this argument, however, if it were brought forward, the reply would be that it proves too much. If it demonstrates that the hydrogen line in the sun is produced by the same molecular grouping of hydrogen as that which gives us two green lines only when the weakest possible spark is taken in hydrogen inclosed in a large glass globe, it also proves that calcium is identical with its salts. For we can get the spectrum of any of the salts alone without its common base, calcium, as we can get the green lines of hydrogen withcut the red one. I submit, therefore, that the argument founded on the overnotes of a sounding body, such as a bell, cannot be urged by any one who believes in the existence of any compound bodies at all, because there is no spectroscopic break between acknowledged compounds and the supposed elementary bodies. The spectroscopic differences between calcium itself at different temperatures is, as I shall show, as great as when we pass from known compounds of calcium to calcium itself. There is a perfect continuity of phenomena from one end of the scale of temperature to the other. Inquiry into the Probable Arrangement of the Basic Molecules. As the results obtained from the above considerations seemed to be so far satisfactory, inasmuch as they at once furnished an explanation VOL. XXVIII. N 166 Mr. J. N. Lockyer. Researches in Spectrum [Dee. 12, of the basic lines actually observed, the inquiry seemed worthy of being carried to a further stage. The next point I considered was to obtain a clear mental view of the manner in which, on the principle of evolution, various bases might now be formed, and then become basic themselves. | Tt did not seem unnatural that the-bases should increase their com- plexity by a process of continual multiplication, the factor being 1, 2, or even 3, if conditions were available under which the temperature of their environment should decrease, as we imagined it to do from the furnace A down to furnace D. This would bring about a condition of molecular complexity in which the proportion of the molecular weight of a substance so produced in a combination with another sub- stance would go on continually increasing. Another method of increasing molecular complexity would be repre- sented by the addition of molecules of different origins. Representing the first method by A+ A, we could represent the second by A+ B. A variation of the last process would consist in a still further com- plexity being brought about by the addition of another molecule of B. so that instead of (A+B), merely, we should have A+ By. Of these three processes the first one seemed that which it was pos- sible to attack under the best conditions, because the consideration of impurities was eliminated; the prior work has left no doubt upon the mind about such and such lines being due to calcium, others to iron, and so forth. That is to say, they are visible in the spectra of these substances asarule. The inquiry took this form: Granting that these lines are special to such and such a substance, does each become basic in turn as the temperature is changed ? I therefore began the search by reviewing the evidence concerning calcium, and seeing if hydrogen, iron, and lithium behaved in the same way. Application of the above Calciwm Views to Calciwm, Iron, Lithium, and Hydrogen. Calcium. It was in a communication to the Royal Society made in 1874 (“ Proc. Roy. Soc.,” vol. xxii, p. 380), that I first referred to the possibility that the well-known line spectra of the elementary bodies. might not result from the vibration of similar molecules. I was led to make the remark in consequence of the differences to which I have already drawn attention in the spectra of certain elements as observed. in the spectrum of the sun and in those obtained with the ordinary instrumental appliances. Later (“ Proc. Roy. Soc.,” No. 168, 1876) I produced evidence that the molecular grouping of calcium which, with a small induction coil and small jar, givesa spectrum with its chief line in the blue, is nearly 1878.] Analysis in connexion with the Spectrum of the Sun. 167 broken up in the sun, and quite broken up in the discharge from a large coil and jar, into another or others with lines in the violet. T said ‘‘ another” or “ others,”’ because I was not then able to deter- mine whether the last-named lines proceeded from the same or different molecules ; and I added that it was possible we might have to wait for photographs of the spectra of the brighter stars before this point could be determined. I also remarked that this result enabled us to fix with very consider- able accuracy the electric dissociating conditions which are equivalent to that degree of dissociation at present at work in the sun. In fig. 3 I have collected several spectra copied from photographs, in order that the line of argument may be grasped. _ First we see what happens to the non-dissociated and the dissociated chloride. Next we have the lines with a weak voltaic arc, the single line to the right (W. L. 4226°3) is much thicker than the two lines (W. L. 3933 and 3968) to the left, and reverses itself. We have next calcium exposed to a current of higher tension. It will be seen that here the three lines are almost equally thick, and all reverse themselves. Now it will be recollected that in the case of known compounds the band structure of the true compounds is reduced as dissociation works its way, and the spectrum of each constituent element makes its appearance. If in 3 we take the wide line as representing the banded spectrum of the compound, and the thinner ones as representing the longest elemental lines making their appearance as the result of partial dissociation, we have, by hypothesis, an element behaving like a com- pound. If the hypothesis be true, we ought. tov be able not only to obtain with lower temperatures a still greater preponderance of the single line, as we do; but with higher temperatures a still greater preponder- ance of the double ones, as we do. I tested this in the following manner: employing photography, because the visibility of the more refrangible lines is small, and because a permanent record of an experiment, free as it must be from all bias, is a very precious thing. Induced currents of electricity were employed in order that all the photographic results might be comparable. To represent the lowest temperature, I used a small induction coil and a Leyden jar only just large enough to secure the requisite amount of photographic effect. To represent the highest, I used the largest coil and jar at my disposal. The spark was then taken between two aluminium electrodes, the lower one cup-shaped, and charged with a salt of calcium. In the figure I give exact copies of the results obtained. It will be seen that with the lowest temperature only the single line (2) and N 2 wD ‘uns ot} ut dnodea twmi10[vo oy Jo uoryd.tosqu our, “2 aie Cae, ‘posn ore avf oduey pure [loo o8aey v UoTTM wUMayoods oy, °9 a % ‘pokoydme oav avl Tums pur fio v ueya wnaqoods ayy, *¢ dD ace i rS Ss posvaLoUl SI S][e0 Jo AoquENU oYY MOY ous OT, “P a ‘s[[00 JO ADGUUNU [CUS B TATA ox OLTJOO[O OY UL LUNTOTLO oTT[VJeUI Fo Winayoods oY, “e ‘JUOLAIND POONPUL UB YFTA FU0}FXO FYSTIS BOF PoYVIOOSSIp ST oTNIejOUl punodutod oy} UWO|M Woes [BJOUL OY} Jo OUT OUT, °Z ‘MOOS ILIV VUNTO[VO FO SOUT, OU pUB “pues pet ayy 4B SI UINAJOOdS oY ‘ojo M B SB SoJBIGIA o[NoeTour punoduiod oy} ‘Moy st ongutoeduroy oy} MOY AA ‘“CF[OBO) oUTAOTYD YILM pouTquIoo st wMVTRO “T Researches in Spectrum th the highest temperature only the two more refrangible 1 H Oo Pp 4 A 88 Cas} a ce a Zi = — O YY re | e S) — ro - = fH (2) © {ad} CO H Cc so 2 re eS *SUOTZIPUOD JUOLEAIpP Lopun utNIOTBo Fo uINAPadg ayy Fo pua ong ey, —-E ‘PIT ations was quite changed This proved that the intensity of the vibr in the two experiments. Perhaps it may not be superfluous here to state the reasons which induced me to search for further evidence in the stars. 1878.] Analysis in connexion with the Spectrum of the Sun. 169 It is abundantly clear that if the so-called elements, or more pro- perly speaking their finest atoms—those that give us line spectra—are really compounds, the compounds must have been formed at a very high temperature. It is easy to imagine that there may be no superior limit to temperature, and therefore no superior limit beyond which such combinations are possible, because the atoms which have the power of combining together at these transcendental stages of heat do not exist as such, or rather they exist combined with other atoms, like or unlike, at all lower temperatures. Hence association will be a com- bination of more complex molecules as temperature is reduced, and of dissociation, therefore, with increased -temperature there may be no end. That is the first point. The second is this :— We are justified in supposing that our “ calcium,” once formed, is a distinct entity, whether it be an element or not, and therefore, by working at it alone, we should never know whether the temperature produces a single simpler form or more atomic condition of the same thing, or whether we actually break it up into x+y, because neither x nor Y will ever vary. But if calcium be a product of a condition of relatively lower tem- perature, then in the stars hot enough to enable its constituents to exist uncompounded, we may expect these constituents to vary im quantity ; there may be more of x in one star and more of Y in another ; and if this be so, then the H and K lines will vary in thickness, and the extremest limit of variation will be that we shall only have H representing, say, Xin one star, and only have K representing, say, Y in another. Intermediately between these extreme conditions we may have cases. in which, though both H and K are visible, H is thicker in some and K is thicker in others. Professor Stokes was good enough to add largely to the value of my paper as it appeared in the “ Proceedings’ by appending a note point- ing out that ‘‘ When a solid body such as a platinum wire, traversed by a voltaic current, is heated to incandescence, we know that as the temperature increases not only does the radiation of each particular refrangibility absolutely increase, but the proportion of the radiations of the different refrangibilities 1s changed, the proportion of the higher to the lower increasing with the temperature. It would be in accord- ance with analogy to suppose that as a rule the same would take place in an incandescent surface, though in this case the spectrum would be discontinuous instead of continuous. Thus, if A, B, C, D, E denote conspicuous bright lines of increasing refrangibility, in the spectrum of the vapour, it might very well be that at a comparatively low temperature A should be the brightest and the most persistent: at a higher temperature, while all were brighter than before, the relative 170 Mr. J. N. Lockyer. Researches in Spectrum [Dee. 12, brightness might be changed, and C might be the brightest and the most persistent, and at a still higher temperature H.” On these grounds Professor Stokes, while he regarded the facts I mentioned as evidence of the high temperature of the sun, did not look upon them as conclusive evidence of the dissociation of the mole- cule of calcium. Since that paper was sent in, however, the appeal to the stars to which I referred in it has been made, and made with the most admir- able results, by Dr. Huggins. The result of that appeal is, that the line which, according to Pro- _ fessor Stokes’s view, should have prevailed over all others, as Sirias is acknowledged to be a hotter star than our sun, if it exists at all in the spectrum, is so faint that it was not recognised by Dr. Huggins in the first instance. In Sirius, indeed, the H line due to one molecular grouping of cal- cium is as thick as are the hydrogen lines as mapped by Secchi, while the K line, due to another molecular grouping, which is equally thick in the spectrum of the sun, has not yet made its appearance. In the sun, where it is as thick as H, the hydrogen lnes have vastly thinned. While this paper has been in preparation, Dr. Huggins has been good enough to communicate to me the results of his most important observations, and I have also had an opportunity of inspecting several of the photographs which he has recently taken. The result of the recent work has been to show that H and are of about the same breadth in Sirius. In a Aquile, while the relation of H to his not greatly changed, a distinct approach to the solar condition is observed, K being now unmistakably present, although its breadth is small as compared with that of H. I must express my obligations to Dr. Huggins for granting me permission to enrich my paper by reference to these unpublished observations. Hrs letter, which I have permis- sion to quote, is as follows :— “It may be gratifying to you to learn that in a photograph I have recently taken of the spectrum of a Aquile there is a line correspond- ing to the more refrangible of the solar H lines [that is K], but about half the breadth of the line corresponding to the first H lines. “In the spectra of a Lyre and Sirius the second line is absent.” Professor Young’s observations of the chromospheric lines, to which . I shall afterwards refer, give important evidence regarding the pre- sence of calcium in the chromosphere of the sun. He finds that the H and K lines of calcium are strongly reversed in every important spot, and that, in solar storms, H has been observed injected into the chromo- sphere seventy-five times, and K fifty times, while the blue line at W. L. 4226°3, the all-important line at the arc temperature, was only injected thrice. 1878.] Analysts in connexion with the Spectrum of the Sun. 171 Further, in the eclipse observed in Siam in 1875, the H and K lines left the strongest record in the spectrum of the chromosphere, while the line near G in a photographic region of much greater intensity was not recorded at all. In the American eclipse of the present year the H and K lines of calcium were distinctly visible at the base of the corona, in which, for the first time, the observers could scarcely trace the existence of any hydrogen. To sum up, then, the facts regarding calcium, we have first of all the H line differentiated from the others by its almost solitary existence im Sirius. We have the K line differentiated from the rest by its birth, so to speak, in a Aquilee, and the thickness of its line in the sun, as compared to that in the arc. We have the blue line differentiated from H and K by its thinness in the solar spectrum while they are thick, and by its thickness in the arc while they are thin. We have it again differentiated from them by its absence in solar storms in Fig. 4. SIRIUS which they are almost universally seen, and, finally, by its absence during eclipses, while the H and K lines have been the brightest seen or photographed. Last stage of all, we have calcium, distinguished from its salts by the fact that the blue line is only visible when a high temperature is employed, each salt having a definite spectrum of its own, in which none of the lines to which I have drawn attention appear, so long as the temperature is kept below a certain point. Tron. With regard to the iron spectrum, I shall limit my remarks to that portion of it visible on my photographic plates, between H and G. It may be described as a very complicated spectrum, so far as the number of lines is concerned, in comparison with such bodies as sodium and potassium, lead, thallium, and the like; but unlike them, again, it contains no one line which is clearly and unmistakably re- versed on all occasions. Compared, however, with the spectrum of such bodies as cerium and uranium, the spectrum is simplicity itself. Now, among these lines are two triplets, two sets of three lines each, giving us beautiful examples of these repetitions of structure in 172 Mr. J. N. Lockyer. esearches in Spectrum |Dec. 12, the spectrum which we meet with in the spectra of almost all bodies, some of which have already been pointed out by Mascart, Cornu, and myself. Now the facts indicate that these two triplets are not due to the vibration of the same molecular grouping which gives rise to most of the other lines. They are as follows. In many photographs -in which iron has been compared with other bodies, and in others: again in which iron has been photographed as existing in different degrees of impurity in other bodies, these triplets have been seen almost alone, and the relative intensity of them, as compared with the few remaining lines, is greatly changed. In this these photographs resemble one [ took three years ago, in which a large coil and jar were employed instead of the arc, which necessitated an exposure of an hour instead of two minutes. In this the triplet near G is very marked ; the two adjacent lines more refrangible near it, which are seen nearly as strong as the triplet itself in some of the arc photographs I possess, are only very faintly visible, while dimmer still are seen the lines of the triplet between H and h. There is another series of facts in another line of work. In solar storms, as is well known, the iron lines sometimes make their appear- ance in the chromosphere. Now, if we were dealing here with one molecular grouping, we should expect the lines to make their appear- ance in the order of their lengths, and we should expect the shortest lines to occur less frequently than the longest ones. Now, precisely the opposite is the fact. One of the most valuable contributions to solar physics that we possess 1s the memoir in which Professor C. A. Young records his observation of the chromospheric lines, made on behalf of the United States Government, at Sherman, in the Rocky Mountains. The glorious climate and pure air of this region, to which [ can personally testify, enabled him to record phenomena which it is hopeless to expect to see under less favourable conditions, Among these were injections of iron vapour into the chromosphere, the record taking the form of the number of times any one line was seen during the whole period of observation. Now, two very faint and short lines close to the triplet near G were observed to be injected thirty times, while one of the lines of the triplet was only injected twice. The question next arises, are the triplets produced by one molecular grouping or by two? This question I also think the facts help us to answer. I will first state, by way of reminder, that in the spark photograph the more refrangible triplet is barely visible, while the one near G is very strong. Now, if one molecular grouping alone were in question, this relative intensity would always be preserved, however much the absolute intensity of the compound system might vary, but if it is a question of two molecules, we might expect that, in some of the regions open to our observation, we should get evidence of cases in 1878.] Analysis in connexion with the Spectrum of the Sun. 173: which the relative intensity is reversed or the two intensities are assimilated. What might happen does happen; the relative intensity of the two triplets in the spark photograph is grandly reversed in the spectrum of the sun. The lines barely visible in the spark photo- graph are among the most prominent in the solar spectrum, while the triplet which is strong in that photograph is represented by Fraunhofer lines not half so thick. Indeed, while the hypothesis that the iron lines in the region I have indicated are produced by the vibration of one molecule does not include all the facts, the hypothesis that the vibrations are produced by at least three distinct molecules includes all the phenomena in a most satisfactory manner. Lithium. Before the maps of the long and short lines of some of the chemical elements compared with the solar spectra, which were published in the ‘‘ Philosophical Transactions” for 1873, Plate 9, were communi- cated to the Society, I very carefully tested the work of prior observers on the non-coincidence of the red and orange lines of that metal with the Fraunhofer lines, and found that neither of them were strongly, if at all, represented in the sun, and this remark also applies to a line in the blue at wave-length 4603. The photographic lithium line, however, in the violet, has a strong representative among the Fraunhofer lines. Applying, therefore, the previous method of stating the facts, the presence of this line in the sun differentiates it from all the others. For the differentiation of the red and yellow lines I need only refer to Bunsen’s spectral analytical researches, which were translated in the ““ Philosophical Magazine,” December, 1875. In Plate 4 two spectra of the chloride of lithium are given, one of them showing the red line strong and the yellow one feeble, the other showing merely a trace of the red line, while the intensity of the yellow one is much increased, and a line in the blue is indicated. Another notice of the blue line of lithium occurs in a discourse by Professor Tyndall, reprinted in the “ Chemical News,” and in a letter of Dr. Frankland’s to Professor Tyndall, dated November 7,1861. This. letter is so important for my argument that I reprint it entire from the ‘ Philosophical Magazine,” vol. xxii, p. 472 :— “On throwing the spectrum of lithium on the screen yesterday, I was surprised to see a magnificent blue band. At first I thought the lithic chloride must be adulterated with strontium, but on testing it with Steinheil’s apparatus it yielded normal results without any trace of a blue band. Iam just now reading the report of your discourse in the ‘Chemical News,’ and I find that you have noticed the saine thing. Whence does this blue line arise? Does it really belong to the lithium, or are the carbon points or ignited air guilty of its pro- 174 Mr. J. N. Lockyer. Researches in Spectrum [Dec. 12. duction? I find these blue bands with common salt, but they have neither the definiteness nor the brilliancy of the lithium band. When lithium wire burns in air it emits a somewhat crimson lght; plunge it into oxygen, and the light changes to bluish-white. This seems to indicate that a high temperature is necessary to bring out the blue ray.” Postscript, November 22, 1861.—‘‘I have just made some further experiments on the lithium spectrum, and they conclusively prove that the appearance of the blue line depends entirely on the tempera- ture. The spectrum of lithic chloride, ignited in a Bunsen’s burner flame, does not disclose the faintest trace of the blue line; replace the Bunsen’s burner by a jet of hydrogen (the temperature of which 1s higher than that of the Bunsen’s burner) and the blue line appears, faint, it is true, but sharp and quite unmistakable. If oxygen now be slowly turned into the jet, the brilliancy of the blue line increases until the temperature of the flame rises high enough to fuse the platinum, and thus put an end to the experiment.” These observations of Professors Tyndall and Frankland differen- tiate this blue line from those which are observed at low temperatures. The line in the violet to which I have already referred is again differentiated from all the rest by the fact that it is the only line in the spectrum of the sun which is strongly reversed, so far as our present knowledge extends. The various forms of lithium, therefore, may be shown in the following manner. Fig. 5. FEEBLE SPARK It is remarkable that in the case of this body which at relatively low temperature goes through its changes, its compounds are broken up at the temperature of the Bunsen burner. The spectrum, e.g. of the chloride, so far as I know, has never been seen. Hydrogen. All the phenomena of variability and inversion in the order of in- tensity presented to us in the case of calcium can be paralleled by reference to the knowledge already acquired regarding the spectrum of hydrogen. Dr. Frankland and myself were working together on the subject in 1869. In that year (‘‘Proc. Roy. Soc.,”’ No. 112) we pointed ont 1878.] Analysis in connexion with the Spectrum of the Sun. 175 that the behaviour of the h line was hors ligne, and that the whole spectrum could be reduced to one line, F. “1. The Fraunhofer line on the solar spectrum, named h by Angstrém, which is due to the absorption of hydrogen, is not visible in 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 chromosphere, it follows that the chromo- sphere, when cool enough to absorb, is still of a relatively high tem- perature. “2. Under certain conditions of temperature and pressure, the very complicated spectrum of hydrogen is reduced in our instrument to one line in the green, corresponding to F in the solar spectrum.” As in the case of calcium also, solar observation affords us most precious knowledge. The h line was missing from the protuberances in 1875, as will be shown from the accompanying extract from the Report of the Eclipse Expedition of that year :— “ During the first part of the eclipse two strong protuberances close together are noticed ; on the limb towards the end these are partially covered, while a series of protuberances came out at the other edge. The strongest of these protuberances are repeated three times, an effect of course of the prism, and we shall have to decide if possible the wave-lengths corresponding to the images. We expect @ priori to find the hydrogen lines represented. We know three photographic hydrogen lines: F, a line near G, and kh. F is just at the limit of the photographic part of the spectrum, and we find indeed images of protuberances towards the less refrangible part at the limit of photo- eraphic effect. For, as we shall show, a continuous spectrum in the lower parts of the corona has been recorded, and the extent of this continuous spectrum gives us an idea of the part of the spectrum in which each protuberance line is placed. We are justified in assuming, therefore, as a preliminary hypothesis, that the least refrangible line in the protuberance shown on the photograph is due to F, and we shall find support of this view in the other lines. In order to deter- mine the position of the next line the dispersive power of the prism was investigated. The prism was placed on a goniometer table in minimum deviation for F', and the angular distance between F and the hydrogen line near G, 7.e., Hy, was found, as a mean of several measurements, to be 3’. The goniometer was graduated to 15”, and owing to the small dispersive power, and therefore relatively great breadth of the slit, the measurement can only be regarded as a first ‘approximation. Turning now again to our photographs, and cal- culating the angular distance between the first and second ring of protuberances, we find that distance to be 3' 15’. We conclude, therefore, that this second ring is due to hydrogen. We, therefore, 176 Mr. J. N. Lockyer, Researches in Spectrum [Dee. 12, naturally looked for the third photographic hydrogen line, which is generally called h, but we found no protuberance on our photographs corresponding to that wave-length. Although this line is always weaker than Hy, its absence on the photograph is rather surprising, if it be not due to the fact that the line is one which only comes out at a high temperature. This is rendered likely by the researches of Frankland and Lockyer (‘‘ Proc. Roy. Soc.,” vol. xvii, p. 453). “We now turn to the last. and strongest series of protuberances shown on our photographs. The distance between this series and the - one we have found reason for identifying with Hy is very little greater than that between HG and Hy. Assuming the distances equal, we conclude that the squares of the inverse wave-lengths of the three series are in arithmetical progression. This is true as a first approxi- mation. We then calculated the wave-length of this unknown line, and found it to be approximately somewhat smaller than 3,957 tenth- metres. No great reliance can be placed, of course, on the number, but it appears that the line must be close to the end of the visible spectrum. ‘In order to decide, if possible, what this line is due to, we endea- voured to find out both by photography and fluorescence whether hydrogen possesses a line in that part of the spectrum. We have not at present come to any definite conclusion. In vacuum tubes pre- pared by Geissler containing hydrogen, a strong line more refrangible than H is seen, but these same tubes show between Hy and Ho, other lines known not to belong to hydrogen, and the origin of the ultra- violet line is therefore difficult to make out. We have taken the spark in hydrogen at atmospheric pressures, as impurities are easier to eliminate, but a continuous spectrum extends over the violet and part of the ultra-violet, and prevents any observation as to lines. We are going on with experiments to settle this point. ‘“‘ Should it turn out that the line is not due to hydrogen, the ques- tion will arise what substance it is due to. It is a remarkable fact that the calculated wave-length comes very close to H. Young has found that these calcium lines are always reversed in the penumbra and immediate neighbourhood of every important sun-spot, and calcium must therefore go up high into the chromosphere. We draw attention to this coincidence, but our photographs do not allow us to draw any certain conclusions. “At any rate, it seems made out by our photographs that the photographic light of the protuberances is in great part due to an ultra-violet line which does not certainly belong to hydrogen. The protuberances as photographed by this ultra-violet ray seem to go up higher than the hydrogen protuberances, but this may be due to the relative greater length of the line.”’ In my remarks upon calcium I have already referred to the fact that 1878.] Analysis in connexion with the Spectrum of the Sun. 177 the line which our observation led us to believe was due to calcium in 1875, was traced to that element in this year’s eclipse. The observa- tions also show the curious connexion that, at the time when the hydrogen lines were most brilliant in the corona, the calcium lines were not detected; next, when the hydrogen lines, being still brilliant, the h line was not present (a condition of things which, in all proba- bility, indicated a reduction of temperature), calcium began to make itself unmistakably visible; and finally, when the hydrogen lines are absent, H and K become striking objects in the spectrum of the corona. To come back to h, then, I have shown that Dr. Frankland and myself, in 1869, found that it only made its appearance when a high tension was employed. We have seen that it was absent from among the hydrogen lines during the eclipse of 1875. I have now to strengthen this evidence by the remark that it is always the shortest line of hydrogen in the chromosphere. I now pass to another line of evidence. I submit to the Society a photograph of the spectrum of indium, in which, as already recorded by Thaleén, the strongest line is one of the lines of hydrogen (h), the other line of hydrogen (near G) being absent. I have observed the C line in the spark produced by the passage of an induced current between indium poles in dry arr. As I am aware how almost impossible it is to render air perfectly dry, I made the following differential experiment. A glass tube with two platinum poles about half an inch apart was employed. Through this tube a slow current of air was driven after passing through a U-tube one foot high, containing calcic chloride, and then through sulphuric acid ina Wolff’s bottle. The spectrum of the spark passing between the platinum electrodes was then observed, a coil with five Grove cells and a medium-sized jar being employed. Careful notes were made of the brilliancy and thickness of the hydrogen lines as compared with those of air. This done, a piece of metallic indium, which was placed loose in the tube, was shaken so that one part of it rested against the base of one of the poles, and one of its ends at a distance of a little less than half an inch from the base of the other pole. The spark was then passed between the indium and the pla- tinum. ‘The red and blue lines of hydrogen were then observed, both by my friend Mr. G W. Hemming, Q.C., and myself. Their brilliancy was most markedly increased. This unmistakable indication of the presence of hydrogen, or rather of that form of hydrogen which gives us the i line alone associated into that form which gives us the blue and red lines, showed us that in the photograph we were not dealing with a physical coincidence, but that in the are this special form of hydrogen had really been present; that it had come from the indium, and that it had registered itself on the photographic plate, although ordinary hydrogen persistently refuses to do so. Although I was 178 Mr. J. N. Lockyer. Researches in Spectrum [Dee. 12. satisfied from former experiments that occluded hydrogen behaves in this respect like ordinary hydrogen, I begged my friend, Mr. W. C. Roberts, F.R.S., Chemist to the Mint, to charge a piece of palladium with hydrogen forme. This he at once did; and I take this present opportunity to express my obligation to him. I exhibit to the Society a photograph of this palladium and of indium side by side. It will be seen that one form of hydrogen in indium has distinctly recorded itself on the plate, while that in palladium has not left a trace. I should add that the palladium was kept in a sealed tube till the moment of making the experiment, and that special precautions were taken to prevent the two pieces between which the arc was taken from becoming unduly heated. To sum up, then, the facts with regard to hydrogen; we have h differentiated from the other lines by its appearance alone in indium; by its absence during the eclipse of 1875, when the other lines were photographed; by its existence as a short line only in the chromo- sphere of the sun, and by the fact that in the experiments of 1869 a very high temperature was needed to cause it to make its appearance. With regard to the isolation of the F line I have already referred to other experiments in 1869, in which Dr. Frankland and myself got it alone.* ‘I exhibit to the Society a globe containing hydrogen, which gives us the F line without either the red or the blue one. The accompanying drawing shows how these lines are integrated in the spectrum of the sun. Fia. 6. i IT have other evidence which, if confirmed, leads to the conclusion that the substance which gives us the non-reversed line in the chromo- sphere and the line at 1474 of Kirchhoft’s scale, termed the coronal line, are really other forms of hydrogen. One of these is possibly more simple than that which gives us h alone, the other more complex than that which gives us F alone. The evidence on this point is of such extreme importance to solar physics, and throws so much light on star structure generally, that I am now engaged in discussing 11, and shall therefore reserve it for a special communication. In the meantime I content myself by giving a diagram, in which I have arranged the various groupings of hydrogen as they appear to * See also Pliicker, “ Phil. Trans.,” Part I, p. 21. 1878.] Analysis in connexion with the Spectrum of the Sun. 17‘ exist, from the regions of highest to those of lowest temperature in our central luminary. Fig. 7. A_G F_C«idAT4. D: CHROMCOSPHERE JAR SPARK SPARKwirnourJAR FEEGLEST SPARK AT LOWEST PRESSURE COOLER STILL Summation of the above Series of Facts. I submit that the facts above recorded are easily grouped together, and a perfect continuity of phenomena established on the hypothesis of successive dissociations analogous to those observed in the cases of undoubted compounds. The other Branches of the Inquiry. When we pass to the other possible evolntionary processes to which 1 have before referred, and which I hope to discuss on a future occasion, the inquiry becomes much more complicated by the extreme difficulty of obtaining pure specimens to work with, although I should remark that in the working hypothesis now under discussion the cause of the constant occurrence of the same substance as an impurity in the same connexion is not far to seek. I take this opportunity of expressing my obligations to many friends who have put themselves to great trouble in obtaining specimens of pure chemicals for me during the whole continuance of my researches. Among these | must mention Dr. Russell, who has given me many specimens prepared by the lamented Matthiessen, as well as some of cobalt and nickel pre- pared by himself; Professor Roscoe, who has supplied me with vana- dium and cesium alum; Mr. Crookes, who has always responded to my call for thallium; Mr. Roberts, chemist to the Mint, who has. supplied me with portions of the gold and silver trial plates and some pieces of palladium; Dr. Hugo Miller, who has furnished me with a large supply of electrolitically-deposited copper; Mr. Holtz- man, who has provided me with cerium, lanthanum, and didymium prepared by himself; Mr. George Matthey, of the well-known metal- lurgical firm of Johnson and Matthey, who has provided me with magnesium and aluminium of marvellous purity; while to Mr. Valen- tin, Mr. Mellor, of Salford, and other friends, my thanks are due for other substances. I have already pointed out that a large portion of the work done in. 180 Mr. J. N. Lockyer on Spectrum Analysis. [Dec. 12, the last four years has consisted in the elimination of the effects of impurities. Iam therefore aware of the great necessity for caution in the spectroscopic examination of various substances. There is, however, a number of bodies which permit of the inquiry into their simple or complex nature being made in such a manner that the presence of impurities will be to a certain extent negligable. I have brought this subject before the Royal Society at its present stage in the hope that possibly others may be induced to aid inquiry in a region in which the work of one individual is as a drop in the ocean. If there is anything in what I have said, the spectra of all the ele- mentary substances will require to be re-mapped—and re-mapped from a new standpoint; further, the arc must replace the spark, and photography must replace the eye. A glance at the red end of the spectrum of almost any substance incandescent in the voltaic are in a spectroscope of large dispersion, and a glance at the maps prepared by such eminent observers as Huggins and Thalén, who have used the coil, will give an idea of the mass of facts which have yet to be recorded and reduced before much further progress can be made. In conclusion, I would state that only a small part of the work to which JI have drawn attention is my own. In some cases I have merely, as it were, codified the work done by other observers in other countries. With reference to that done in my own laboratory I may here repeat what I have said before on other occasions, that it is largely due to the skill, patience, and untiring zeal of those who have assisted me. ‘The burthen of the final reduction, to which I have before referred, has fallen to Mr. Miller, my present assistant; while the mapping of the positions and intensities of the lines was done by Messrs. Friswell, Meldola, Ord and Starling, who have successively filled that post. IT have to thank Corporal Ewings, R.H., for preparing the various diagrams which I have submitted to the notice of this Society. December 19, 1878. W.SPOTTISWOODE, M.A., D.C.L., President, in the Chair. The Presents received were laid on the table, and thanks ordered for ¢hem. The following Papers were read :— 1378. | On the Spectrum of the Electric Discharge. 1381 I. “Note of an Experiment on the Spectrum of the Electric Dicchancveny byathe Elon. Sir W. KR. - Grove, WiC, V.P.R.S. Communicated December 19, 1878. The difference between the appearances at the positive and negative terminal which an electric discharge presents in vacuum tubes has struck many observers. The negative terminal is surrounded in what is called an air vacuum with a blue glow extending to a considerable distance from the platinum wire, and is generally bounded by a dark space separating it from the crimson light of the positive wire ; it is affected by the magnet, the light following the direction of the magnetic curves, and a deposit of platinum on the glass tube appears in time in the vicinity of the negative which is absent at the positive terminal. I do not propose to enter more fully on these distinctions which have been largely experimented on by M. Gassiot, Professor Pliicker, and to seme extent by myself. The recent announcement of Mr. Norman Lockyer of observations on the spectra of bodies which were assumed to be elementary, but which showed lines seeming to denote that they were compound, led me to repeat some old experiments of mine on the spectrum of the electric discharge, one result of which I have ventured to communicate to the Royal Society. JI had intended to mention them in the discussion of Mr. Lockyer’s paper, but was not able to be present at it. On November 24th last I examined, with a small spectroscope, by Browning, the electric discharge in some Geissler’s air vacuum tubes, three of which I possessed. In these, which were of different shapes and sizes, the effects were the same. The globes into which the negative wire protruded were filled with a blue light more diffused as it became more distant from the wire. The rest of the tube was filled with a crimson light appearing to issue from the positive wire, and this hight was striated in the narrow parts of the tubes. The spectrum from what I will call the positive light presented a series of numerous and variously coloured bands not greatly differing in brightness, and showing what has been called the fluted or channelled spectrum. The spectrum of the negative light was extremely different. Four bright lines divided the spectrum, viz., yellow, green, blue, and violet respectively, the distance between them increasing towards the violet end. There was also a faint line at the extreme red, and the red end of the spectrum was divided into two different tints, terminating with the bright yellow line. In the positive spectrum there was a wide black band, apparently an absorption band, overlapping the yellow and a portion of the orange space. On looking for a longer time at the spectrum of the negative light, my eye becoming more accustomed to it, I became able to detect other VOL. XXVIII. 0 182 Sir W. R. Grove on an Huperiment on [Deer nos bands between the bright lines, and on attaching a small prism (with which the spectroscope was provided) in front of the slit, so that the separate spectra of the positive and negative lights could be juxta- posed, I could trace several of the bands which appeared quite distinctly in the positive spectrum, into the negative one; but in the latter they were very faint, while the converse case obtained with the four bright lines I have mentioned, which were brilliant in the negative spectrum and faint or normal in the positive. Although the four bright lines standing out in strong relief in the negative spectrum was the more striking phenomenon to the eye, yet the black band in the positive appearing in the space corresponding to the bright yellow hght in the negative spectrum is equally or possibly. more important. . The positive light, far the brightest to the eye, is diffused into a fluted spectrum of substantially equal intensity throughout, while the negative dim hght is concentrated into brilliant ines of intense lumi- nosity. Another tube in which the vacuum was, I have no doubt, produced by the absorption of carbonic acid by potash, and which may be called a carbonic acid vacuum, gave a very different result from the three I have mentioned. In it the light throughout was striated and blue, or bluish, witha slight purple tinge pervading the negative glow. With this tube the spectra were strikingly different from those in the air vacuo. There were in the negative spectrum of this tube six bright lines, viz., extreme red, orange, greenish-yellow, green, greenish- blue, and violet. The same lines with one exception were visible and equally prominent throughout the whole of the tube. That exception, which was noticed by Dr. Frankland, to whom I showed my experi- ments, was the extreme red line which was apparent only in the spectrum from the negative glow. On juxtaposing, by means of the prism, this spectrum with the spectrum of the negative heht in an air vacuum tube, one only of the lines coincided, viz., the green line, the others were in entirely distinct parts of the spectrum ; this was to be expected, as the one tube would give mainly a nitrogen spectrum, the other a carbonic oxide one. I have long been convinced, and this is now, I believe, the prevalent opinion, that the light of the electric discharge is an incandescence of the intermedium through which it passes, and of the terminals themselves (see ‘“‘ Correlation of Physical Forces,” 6th edit., pp. 75, et seq.). If this be so, then, the above experiments, 7.e., those on the positive and negative spectra in the same tube, must be either different spectra of the same incandescent substances, or the attenuated gases must be differently decomposed or united in the different parts of the tube, or a different character of electric polarity must ensue in the positive 1878.] the Spectrum of the Electrie Discharge. 183 and negative portions of the gas. The first of the above conditions can only result from difference of heat, which is known to produce different spectra from the same gas. I do not think the effects are due to difference of temperature. It is true that the negative electrode is more heated than the positive in the electric discharge in vacuo, but the heat disseminated by it throughout the negative glow produces in its totality but a sight rise in temperature throughout the volume of the negative glow. 1st. If it be the effect of heat it must be what may be termed mole- eular heat, as the change in the character of the spectrum being com- paratively sudden between the negative and positive light is against the phenomena being caused by change of temperature throughout. 2ndly. Is it caused by chemical decomposition? This is possible, but a different chemical effect pervading two definite portions of the electric discharge is a new effect and not to be hastily assumed. I have shown (“ Phil. Trans.,” 1852) that the electric discharge has an electro-chemical polarity when acting on attenuated gases, the positive terminal producing an oxidating, and the negative a deoxidating effect ; but this effect in my experiments only manifested itself at the terminals, although it may molecularly pervade the gas. ordly. Is it due to electric polarity ? I incline to think it is, but to a polarity so affecting the molecules of the gas, that, if not actually decomposed, they have something like a chemical polarity impressed upon them. This would to some extent favour Mr. Lockyer’s view, though not supporting it to its full extent. The results may help to explain the phenomena observed in some stars where one or more lines belonging to the spectrum of a given . substance is observed, while others are wanting; and if stars have their atmospheres in a state of electric polarity, as is to some extent the case with this earth, or of electric discharge, as is the case with this earth when the Aurora Borealis or Australis is visible, the spectra would differ more or less from those normally observed here. If the spectrum of the negative light were examined through a series of prisms, there can, I think, be little doubt that the very faint intermediate lines would be obliterated by absorption in passing through the glasses, while the bright lines would remain, and thus the spectrum of a nebula would be presented ; but it would be but a partial representation of the true spectrum, and the line spectrum seen in the nebule may thus be a ‘partial spectrum. P.S. December 23. My attention has been called to Mr. De La Rue’s paper recently printed in the “ Phil. Trans.,” which, although he kindly sent me a copy, I had not read when I made the above communication. He finds 02 184 Mr. G. H. Darwin on [Deer 1a; in the spectra of hydrogen vacua a notable difference in the lines seen in the negative light, sometimes all and sometimes only one of the recognised lines of hydrogen being visible in that, and in many cases not visible in other parts of the tube. I had tried an experi- ment with a hydrogen vacuum tube of Geissler; but in that the difference was but slight between the positive and negative lights, though it was very great between the light in the narrow central part of the tube and in the wide portions on each side of it, the crimson light in the narrow tube giving a brilliant three-line spectrum, and the blue light, both on the positive and negative side, giving a compara- tively dim fluted spectrum of many bands. The difference between the hight of narrow and wide parts of the vacuum tubes has, I believe, been noticed; it is in this case the converse of the effects observed by me in the air vacuum. II. “On the Precession of a Viscous Spheroid, and on the Re- mote History of the Earth.” By GrorcE H. Darwin, M.A., Fellow of Trinity College, Cambridge. Communicated by J. W. L. GLAISHER, F.R.S. Received July 22, 1878. (Abstract. ) This paper is a continuation of a previous one on the bodily tides of homogeneous viscous spheroids (read on May 28rd), and it contains the investigation of the rotation of such a body as modified by the tides raised in it by external disturbing bodies. The earth is taken as the type of the rotating body, and the sun and moon as types of the disturbing ones; this plan not only affords a useful vocabulary, but permits an easy transition from questions of abstract dynamics to those of direct applicability to the physical history of the earth. In the paper on tides it was shown that, if the disturbing influence be expressed as a potential, which is expanded as a series of solid harmonics, each multiplied by a simple time harmonic, then each such term in the expansion corresponds with a tide in a viscous or im- perfectly elastic sphere, which is independent of the tides corresponding to all other terms. Also the height of every such tide is expressible as a fraction of the corresponding equilibrium tide of a perfectly fluid spheroid, and the tide is subject to a retardation which is a function | of the frequency of the generating term, and of the constants ex- pressive of the physical constitution of the distorted spheroid. The case of the moon, supposed to move in a circular orbit in the ecliptic, is treated first. The tide generating potential of that body (of the type cos*—2*) has first to be expanded in the desired form ; * Terms of higher orders are shown to be negligeable. 1878.] the Precession of a Viscous Spheroid, §c. 185 and then a formula expressive of the shape of the distorted spheroid may be at once written down. The spheroid or earth is found to be distorted by tides of seven different periods ; three nearly semi-diurnal, three nearly diurnal, and one fortnightly tide. Hach such tide has a height which is a different fraction of the corresponding equilibrium tide of a perfectly fluid spheroid, and is differently altered in phase. Throughout nearly the whole investiga- tion it is, however, sufficiently accurate, if the three semi-diurnal tides are grouped together, and so also with the three diurnal tides ; by this approximation the earth is regarded as distorted by only three tides. The next process is the formation of the couples acting on the earth, which are caused by the attraction of the moon on the several tidal protuberances. In the development of these couples only those terms are retained which can give rise to secular alterations in the precession, the obliquity to the ecliptic, and the length of day. These expressions are then substituted in the differential equations of motion, and the equations are integrated ; whence follow the correction to the uniform precession of the earth considered as a rigid body, and differential equations expressive of the rate of change of obliquity, and the rate of retardation of the earth’s diurnal rotation. It appears that, if the tides do not lag (as with a perfectly fluid or perfectly elastic spheroid), the obliquity and rotation are unaffected, and, whether they lag or not, the correction to the precession is but a small fraction of the whole precession. Henceforth it is only the changes of obliquity and rotation which are of interest. A second disturbing body—the sun—is now introduced. A new set of bodily tides are of course raised, and the expressions for the couples are augmented by the addition of solar terms, and also by terms de- pending on the attraction of the sun on the lunar tides and the moon on the solar tides. It seems paradoxical that there should be these combined effects, for the sun’s and moon’s periods have no common multiple. But, as far as concerns their interaction, the sun and moon may be conceived to be replaced by two annular satellites of masses equal to those of the two bodies. The combined effects vanish with the obliquity, and depend solely on those tides which run through their periods in a sidereal day, and in twelve sidereal hours. Up to this point all the analysis is conducted so that the solutions may be applied either to a viscous, elastic, or imperfectly elastic spheroid. In the case where the earth is purely viscous a graphical examina- tion of the equation, giving the rate of change of obliquity, shows that the obliquity sometimes tends to increase and sometimes to diminish, according as the obliquity and viscosity vary. There are also a number of positions of dynamical equilibrium, some stable and some unstable ; 186 Mr. G. H. Darwin on [Dec. 19, but it would be necessary to give a figure, and to go into details, to give the results satisfactorily. A similar examination of the equation, giving the retardation of the earth’s rotation, shows that there is not so much variety of result, for the tidal friction always tends to retard the earth. This completes the consideration of the instantaneous effects on the earth, and the next point demanding attention is the reaction, which the bodily tides have upon the disturbing bodies. The problem is solved by the consideration that however the three bodies may interact the resultant moment of momentum of the moon- earth system remains constant, except in so far as it is affected by the sun’s action on the earth. The application of this principle results in an equation giving the rate of increase of the square root of the moon’s distance in terms of the heights and retardations of the several bodily tides on the earth; it appears that all the tides, except the fortnightly one, tend to make the moon’s distance increase with the time, but the fortnightly tide acts in the opposite direction; its effect is, however, in general very small compared with that of the other tides. It is proved, also, that the tidal reaction on the sun, which goes to modify the earth’s orbit, has quite msignificant effects, and may be neglected. T will now show, from geometrical considerations, how some of the results previously stated come to be true. It will not, however, be possible to obtain a quantitative estimate in this way. The three following pr opositions do not properly paléaie to an abstract, since they are not given in the paper itself; Be merely partially replace the analytical method pursued therein. The results of the analysis were so wholly unexpected in their variety, that I have thought it well to show that the more important of them were con- formable to common sense. These general explanations might doubt- less be multiplied by some ingenuity, but it would not have been easy to discover the results, unless the way had been first shown by analysis. Prop. I. If the visvosity be small the earth’s obliquity increases, the rota- tion is retarded, and the moon’s distance and periodic time increase. The figure represents the earth as seen from above the South Pole, so that S is the Pole, and the outer circle the Equator. The earth’s rotation is in the direction of the curved arrow at 8. The half of the inner circle which is drawn with a full line is a semi-small-circle of 8. lat., and the dotted semi-circle is a semi-small-cirele in the same N. lat. Generally dotted lines indicate parts of the figure which are below the plane of the paper. It will make the explanation somewhat simpler, if we suppose the tides to be raised by a moon and anti-moon diametrically opposite to one another. Then let M and M’ be the projections of the moon and anti-moon on to the terrestrial sphere. 1878. ] the Precession of a Viscous Spheroid, &c. 187 If the substance of the earth were a perfect fluid or perfectly elastic, the apices of the tidal spheroid would be at M and M’. If, however, there is internal friction due to any sort of viscosity, the tides will lag, and we may suppose the tidal apices to be at T and T”’. Now, suppose the tidal protuberances to be replaced by two equal heavy particles at T and T’, which are instantaneously rigidly con- nected with the earth. Then the attraction of the moon on T is greater than on T’; and cf the anti-moon on T’ is greater than on T. The resultant of these forces is clearly a pair of forces acting on the earth in the direction of TM, T'M’. The effect on the obliquity will be considered first. These forces TM, T’M’, clearly cause a couple about the axis in the equator, which lies in the same meridian as the moon and anti-moon. The direction of the couple is shown by the curved arrows at L, L’. Now, if the effects of this couple be compounded with the existing rotation of the earth, according to the principle of the gyroscope, it will be seen that the South Pole S tends to approach M, and the North Pole to approach M’. Hence supposing the moon to move in the ecliptic, the inclination of the earth’s axis to the ecliptic dimi- nishes, or the obliquity increases. Next, the forces TM, T’M’, clearly produce a couple about the earth’s polar axis, which tends to retard the diurnal rotation. Lastly, since action and reaction are equal and opposite, and since the moon and anti-moon cause the forces TM, T’M’, on the earth, therefore the earth must cause forces on those two bodies (or on their equiva- lent single moon) in the directions MT and M’T’. These forces are in the direction of the moon’s orbitual motion, and therefore her linear velocity is augmented. Since the centrifugal force of her or- bitual motion must remain constant, her distance increases, and with 188 Mr. G. H. Darwin on [Dec.wb9: the increase of distance comes an increase of periodic time round the earth. This general explanation remains a fair representation of the state of the case so long as the different harmonic constituents of the agegre- gate tide-wave do not suffer very different amounts of retardations ; and this is the case so long as the viscosity is not great. Prop. II. The attraction of the moon on a lagging fortnightly tide causes the earth’s obliquity to diminish, but does not affect the diurnal rota- tion; the reaction on the moon causes a diminution of her distance, and periodic tyme. The fortnightly tide of a perfectly fluid earth is a periodic increase and diminution of the ellipticity of figure; the increment of ellip- ticity varies as the square of the sine of the obliquity of the equator to the ecliptic, and as the cosine of twice the moon’s longitude from her node. Thus the ellipticity is greatest when the moon is in her nodes, and least when she is 90° removed from them. In a lagging fortnightly tide the ellipticity 1s greatest some time after the moon has passed the nodes, and least an equal time after she has passed the point 90° removed from them. The effects of this alteration of shape may be obtained by substi- tuting for these variations of ellipticity two attractive or repulsive particles, one at the North Pole and the other at the South Pole of the earth. These particles must be supposed to wax and wane, so that when the real ellipticity of figure is greatest they have their maximum repulsive power, and when least they have their maximum attractive power; and their positive and negative maxima are equal. We will now take the extreme case when the obliquity is 90°; this makes the fortnightly tide as large as possible. Let the plane of the paper be that of the ecliptic, and let the outer semicircle be the moon’s orbit, which she describes in the direction of 1878. | the Precession of a Viscous Spheroid, Sc. 189 the arrows. Let NS be the earth’s axis, which les by hypothesis in the ecliptic, and let LL’ be the nodes of the orbit. Let N be the North Pole; that is to say, if the earth were turned about the line LL’, so that N rises above the plane of the paper, the earth’s rotation would be in the same direction as the moon’s orbitual motion. First consider the case where the earth is perfectly fluid, so that the tides do not lag. Let mz, ms be points in the orbit whose longitudes are 45° and 135°; and suppose that couples acting on the earth about an axis at O perpen- dicular to the plane of the paper are called positive when they are in the direction of the curved arrow at O. ‘Then, when the moon is at m, the particles at N and S have their maximum repulsion. But at this instant the moon is equidistant from both, and there is no couple about O. As, however, the moon passes to m, there is a positive couple, which vanishes when the moon is at m, because the particles have waned to zero. From m, to ms the couple is negative ; from ms; to m, positive; and from im, to m; negative. Now, the couple goes through just the same changes of magnitude, as the moon passes from ™, to 72, as it does while the moon passes from m, to m;, but in the reverse order; the like may be said of the arcs mgm; and mgr. Hence it follows that the average effect, as the moon passes through half its course, is nil, and therefore there can be no secular change in the position of the earth’s axis. | But now consider the case when the tide lags. When the moon is at m, the couple is zero, because she is equally distant from both particles. The particles have not, however, reached their maximum of repulsiveness; this they do when the moon has reached M,, and they do not cease to be repulsive until the moon has reached Mb. Hence, during the description of the arc mM, the couple round O is positive. Throughout the arc M,m; the couple is negative, but it vanishes when the moon is at m3, because the moon and the two particles are in a straight line. The particles reach their maximum of attractiveness when the moon is at M;, and the couple continues to be positive until the moon is at M,. Lastly, during the description of the arc Mym; the couple is negative. But now there is no longer a balance between the arcs mM, and M.m;, nor between Min and m3My. The arcs during which the couples are positive are longer and the couples are more intense than in the rest of the semi-orbit. Hence the average effect of the couples is a positive couple, that is to say, in the direction of the curved arrow round O. It may be remarked that if the arcs m:M,, m.M2, m;M3, mM, had been 45°, there would have been no negative couples at all, and the positive couples would merely have varied in intensity. 190 Mr, G. H. Darwin on [Deena Now, a couple round O in the direction of the arrow, when com- bined with the earth’s rotation, would, according to the priiciple of the gyroscope, cause the pole N to rise above the plane of the paper, that is to say, the obliquity of the ecliptic would diminish. The same thing would happen, but to a less extent, if the obliquity had been less than 90°; it would not, however, be nearly so easy to show this from general considerations. Since the forces which act on the earth always pass through N and 8, therefore there can be no moment about the axis NS, and the rotation about that axis remains unaffected. This can hardly be said to amount to strict proof that the diurnal rotation is unaffected by the fortnightly tide, because it has not been rigorously shown that the two particles at N and § are a complete equivalent to the varying ellipticity of figure. Lastly, the reaction on the moon must obviously be in the opposite direction to that of the curved arrow at O; therefore there is a force retarding her linear motion, the effect of which is a diminution of her distance and of her periodic time. The fortnightly tidal effect must be far more efficient for very great viscosities than for small ones, for, unless the viscosity is very great, the substance of the spheroid has time to behave sensibly like a perfeet fluid, and the tide hardly lags at all. Prop. III. An annular satellite not parallel to the planet's equetor attracts the lagging tides raised by it, so as to diminish the inclination of the planet's equator to the plane of the ring, and to diminish the planet's rotation. The effects of the joint action of sun and moon may be explained from this. Suppose the figure to represent the planet as seen from vertically over the South Pole S; let LL’ be the nodes of the ring, and LRL’ the projection of half the ring on to the planetary sphere. If the planet were perfectly fluid the attraction of the ring would 1878. ] the Precession of a Viscous Spheroid, Sc. VOLE produce a ridge of elevation all along the neighbourhood of the are LRU’, together with a compression in the direction of an axis perpen- dicular tv the plane of the ring. This tidal spheroid may be conceived to be replaced by a repulsive particle placed at P, the pole of the ring, and an equal repulsive particle at its antipodes, which is not shown in the figure. | Now suppose that the spheroid is viscous, and that the tide lags; then since the planet rotates in the direction of the curved arrow at 8, the repulsive particle is carried past its place, P, to P’. The angle PSP’ is a measure of the lagging of the tide. We now have to consider the effect of the repulsion of the ring ona particle which is instantaneously and rigidly connected with the planet ape’. Since P’ is nearer to the half L of the ring, than to the half L’, the general effect of the repulsion must be a force somewhere in the direc- tion P’'P. Now this force P’P must cause a couple in the direction of the curved arrows K, K’ about an axis, KK’, perpendicular to LL’, the nodes of the ring. The effects of this couple, when compounded with the planet’s rotation, is to cause the pole S to recede from the ring LRL’. Hence the inclination of the planet’s equator to the ring diminishes. Secondly, the force P’P produces a couple about S, adverse to the planet’s rotation about its axis 8. If the obliquity of the ring be small, this couple will be small, because P’ will le close to S. Lastly, it may be shown analytically that the tangential force on the ring in the direction of the planet’s rotation, corresponding with the tidal friction, is exactly counterbalanced by a tangential force in the opposite direction, corresponding with the change of the obliquity. Thus the diameter of the ring remains constant. It would not be very easy to prove this from general considerations. It may be shown that, as far as concerns their joint action, the sun and moon may be conceived to be replaced by a pair of rings, and these rings may be replaced by a single one; hence the above propo- sition is also applicable to the explanation of the joint action of the two bodies on the earth, and numerical calculation shows that these joint effects exercise a very important influence on the rate of variation of obliquity. To return to the paper: the retardation of the earth’s rotation would cause an apparent acceleration of the moon, if that body were unaffected, but this is partly counterbalanced by the true retardation of the moon. We thus have the means of connecting an apparent acceleration of the moon with the heights and retardations of the several bodily tides. I have applied this idea to the supposition that the moon is subject to an L92 Mr. G. H. Darwin on [Dect apparent acceleration of 4” per century, and I found that, if the earth were purely viscous, the moon must be undergoing a secular retarda- tion of 3°6” per century, while the earth (considered as a clock) must be losing fourteen seconds in the same time. The obliquity also must be diminishing at the rate of 1° in 470 million years. Under these circumstances the earth must have so great an effective rigidity that the bodily semi-diurnal and diurnal tides would be quite insensible ; the bodily fortnightly tide would however be so consider- able that the oceanic fortnightly tide would be reduced to one-seventh of its theoretical value on a rigid nucleus, and the time of high water would be accelerated by three days. The supposition that the earth is a nearly perfectly elastic spheroid leads to very different results in this respect, which, however, I will now pass over. From this and other considerations, I conclude that a secular accele- ration of the moon’s motion affords no datum for determining the present amount of tidal friction. Sir W. Thomson has discussed the probable age of the earth from considering the tidal friction, and he derived his estimate of the rate at which the earth’s diurnal rotation is slackening, principally from the secular acceleration of the moon. He fully admitted that his data did not admit of precise results, but, if 1 am correct, it certainly appears that his argument loses some of its force. The differential equations, which have to be solved in order to investigate the secular changes in the configuration of the three bodies, are exceedingly complex, and I was only able to solve them by a labo- rious method, depending partly on analysis and partly on numerical quadratures. The solution was only applicable to the case where the earth is a purely viscous body, and the numerical value chosen for the coefficient of viscosity was such that the changes proceed with about the maxi- mum rapidity. Starting with the present values of the obliquity, day, month, and year, the changes were traced backwards in time. As we go backwards we find the year sensibly constant, but the obliquity, day and month all diminishing—the last with far the greatest rapidity. The changes proceed at a rapidly increasing rate, as in the retrospect the moon approaches the earth. At the point where I found it convenient to stop in the first method of solution, about 56 million years have been traversed backwards, and the obliquity is found to have diminished by 9°, the day is found to have fallen to 6 hrs. 50 mins., and the sidereal month to only 1 day 14 hrs. It is a question of great interest to geologists to determine whether any part of changes of this kind can have taken place during geological history ; and I conclude that it might be so. The physical meaning 1878.] the Precession of a Viscous Spheroid, &c. 193 of the coefficient of viscosity which is used in this solution is as follows :—If a slab of the materials of the earth an inch thick have one face held fixed, and if the other face be subjected to a tangential stress of 134 tons to the square inch for 24 hours, then the two faces have been displaced relatively to one another through one-tenth of an inch. Such a material would in ordinary parlance be called a solid, and in the tidal problem this must be regarded as a moderately small viscosity, whence I conclude that the earth may have been habitable, and yet have undergone these changes. Amongst the conclusions of interest to geologists is the following: namely, that the amount of heat generated in the interior of the earth by internal friction, during these 56 million years, would be sufficient, if applied all at once, to heat the whole earth’s mass 1,755° F., supposing the earth to have the specific heat of iron. If then it is permissible to suppose that any considerable part of these changes has taken place during geological history, the estimate of the age of the earth, which is founded on the assumption that the earth is simply a cooling sphere, would have to undergo modification. A second solution of the differential equations is next given, adapted to the hypothesis that the earth stiffened as 1t cooled; but no definite law of stiffening is assumed. This solution follows a line closely similar to that of the last up to the point where the day has fallen to 6 hrs. 50 mins. The obliquity is, however, found to decrease slightly more than in the previous solution. At this point it was found necessary to abandon the approximation by which the three semi-diurnal and the three diurnal tides are classi- fied together. The problem then becomes much more complex, and a new method of solution is required. It is found that in the retrospect the obliquity will only continue to diminish a little beyond the point already reached; for when the month has become equal to twice the day there is no longer a tendency to diminution, and for smaller values of the month the tendency is re- versed. This shows that for values of the month less than twice the day, the position of zero obliquity of the earth’s axis is dynamically stable. The whole diminution of obliquity, from the initial state back to the eritical point of relationship between the month and day, is found to be 10°. After considering the various discrepancies between the ideal pro- blem solved and the real case of the earth, I conclude that while a large part of the obliquity may be probably referred to these causes, yet that there probably remains an outstanding part which is not so explicable. The obliquity to the ecliptic is now set on one side, and from a consideration of the equation of conservation of moment of momentum, the initial state is determined, towards which the solution has been 194 Mr. G. H. Darwin on Problems connected [Dec. 19, running back. It is found that the initial condition is one in which moon and earth rotate, as though fixed together, in 5 hrs. 40 mins.; and that this condition is one of dynamical instability, so that the moon must either have fallen into the earth, or have receded from it, and have then gone through the changes which were traced backwards. From this and other considerations it is concluded that, if the moon and earth were ever molten viscous masses, then it is highly probable that they once formed parts of a common mass. The rest of the paper is occupied with a number of miscellaneous propositions, and with a discussion of the physical significance of the results obtained. I will here only mention that the case of the Martian satellites appears to me a very striking corroboration of the applicability of these views to the solar system, whilst the Uranian system of satellites is, at first sight, unfavourable. A whole series of problems, some of them of great difficulty, still await solution; and not until they are solved will it be possible either decisively to accept or reject the modified form of the nebular hypo- thesis, to which my results obviously point. (Postscript.) Added November 8th, 1878. A subsequent investigation has shown that, although the amount of heat which might be generated by internal friction in the earth might be very great, yet its distribution would be such that it could scarcely sensibly affect Sir W. Thomson’s investigation of the secular cooling of the earth. Ill. “Problems connected with the Tides of a Viscous Sphe- roid.” By G. H. Darwin, M.A., Trinity College, Cambridge. Communicated by J. W. L. GLAISHER, F.R.S. Received November 14, 1878. (Abstract. ) In this paper certain problems are treated, which were alluded to in two previous papers on the Tides and Precession of a viscous spheroid.* For brevity the spheroid is spoken of as the earth, and the disturbing body as the moon. I. Secular Distortion of the Spheroid, and certain Tides of the second order. The distortion arises from the unequal distribution of the tidal frictional couple over the surface of the spheroid. * Read before the Royal Society on May 23 and December 19 respectively. 1878. ] with the Tides of a Viscous Spheroid. 195 In forming the theory of tides, it was assumed that the action of the tidal protuberance on any element of the surface of the mean sphere was entirely normal to the sphere, and consisted of the weight of the prismatic element of the tidal protuberance, which stands on the element of surface. This is not rigorously correct, because, if it were so, there would be no couples tending to alter the diurnal rotation and obliquity of the earth. The effects of these couples were considered in the paper on “ Precession,” but the tidal protuberance was there assumed to be instantaneously rigidly connected with the mean sphere. The present problem is concerned with the non-rigid attachment of the protuberance to the sphere. A sphere is supposed to be distorted into any form differing in- finitesimally from the true sphere, and to be acted on by any external disturbing potential. It is then found what tangential stress must be supposed to act across the base of any prismatic element of the pro- tuberance, in order that the equilibrium of that element may be main- tained, the pressures transmitted by the four contiguous elements being taken into account. It appears that if the protuberance has the equilibrium form, due to the external disturbing potential, then there is no tangential stress between the true sphere and the pro- tuberance. But since the tides of a viscous spheroid lag, the form of the viscous tidal protuberance is not one of equilibrium, and there is such a tangential stress across the base of each element of the pro- tuberance. It is obvious that these tangential stresses may produce a continued distortion of the spheroid. The problem, as applicable to the earth, is treated in the simple case where the obliquity to the ecliptic is zero, and where there is only one disturbing body or moon. The sum of the moments of the tangential stresses about the axis of rotation gives the tidal frictional couple, and its form is found to agree with that found by a different method in the paper on “ Pre- cession.” When the earth’s rotation is taken into account, it appears that the component along the meridian of tangential stress at any point of the surface is periodic in time; whilst one part of the component perpen- dicular to the meridian is periodic, and the other non-periodic. The periodic parts of the component tangential stresses give rise to small tides of the second order (varying as the square of the tide-generating force), and are neglected, but the non-periodic part gives rise to a secular distortion. Since the earth’s rotation as a whole is retarded, therefore the dis- torting tangential stresses all over the surface constitute a non- equilibrating system of forces, and in order to find the distortion of the globe, they must be deemed to be equilibrated by the effective forces due to the inertia of the slackening diurnal rotation. These 196 Mr. G. H. Darwin on Problems connected [Dec. 19, effective forces give bodily forces in the interior, the sum of whose moments about the axis of rotation is equal and opposite to the tidal frictional couple. The problem is thus reduced to finding the dis- tortion of a sphere subject to bodily force equilibrated by surface action, and it is solved by Sir W. Thomson’s method of finding the internal strain of an elastic sphere under like conditions, although here the bodily force has no corresponding potential function. The solution shows that the distortion consists in a simple cylin- drical motion round the axis of rotation, each point moving from east to west with a linear velocity proportional to the cube of its distance from that axis. The distortion of the surface of the globe consists of a motion in longitude from west to east, relatively to a point in the equator, the rate of change of longitude being proportional to the square of the sine of the latitude. Numerical calculation shows, however, that in the later stages of the earth’s history (the development being supposed to follow the laws found in the paper on “ Precession”’), the distortion must have been very small. With a certain assumed viscosity, it is found that, looking back 45,000,000 years, a point in latitude 60° would he 14’ further east than at present. From this it follows, that this cause can have had little or nothing to do with the crumpling of geological Strata. As, however, the distorting force varies inversely as the sixth power of the moon’s distance, it seems possible that in the very earliest stages this cause may have had sensible effects. It is, therefore, note- worthy that the wrinkles raised on the surface would run north and south in the equatorial regions, with a tendency towards north-east and south-west in the northern hemisphere, and north-west and south- east in the southern one. The intensity of the distorting force at the surface varies as the square of the cosine of the latitude. An inspection of a map of the earth shows that the continents (or large wrinkles) conform more or less to this law. But Professor Schiapparelli’s map of Mars* is more striking than that of the earth, when viewed by the hght of this theory; but there are some objections to its application to the case of Mars. If, however, there is any truth in this, then it must be postulated, that after the wrinkles were formed the crust attained sufficient local rigidity to resist the obliteration of the wrinkles, whilst the mean figure of the earth adjusted itself to the ellipticity appropriate to the slackening diurnal rotation ; also, it must be supposed that the general direction of the existing continents has lasted through geological history. The second question, considered in the first part, deals with the * “Memorie della Societa degli Spettroscopisti Italiani,’ 1878, vol. vil. 1878.] with the Tides of a Viscous Spheroid. 197 non-rigid attachment of the permanent equatorial protuberance to the mean sphere. It is shown thatthe precessional and nutational couples will give rise to certain tides of the second order (varying as the tide- generating force multiplied by the precessional constant), but not to any secular shifting of the surface over the interior, as has been sup- posed would be the case . some writers. Il. Distribution ss Heat. gener ated by Internal Friction, and the secular ott cooling of the Spheroid. Ba the paper on “ Precession” it was shown by the theory of energy, that a very large amount of heat might have been generated inside the earth by friction, but the investigation gave no indication as to its distribution. The problem is here considered by finding the amount of work done per unit of time on each element of the interior inthe course of the tidal distortion. = The aggregate work done on the whole globe is found to be the _ same as that given by simple considerations of energy. The rate of work is equal to the tidal frictional couple multiplied by the relative angular velocity of the moon and earth; but this simple law arises out of a complex law of internal distribution. By far the larger part of the work done, or heat generated, is found to be in the central portion, My first impression was that the large amount of heat, which might be generated, would serve to explain in part the observed increase of underground temperature ; but the solution of a certain problem con- cerning the cooling of an infinite slab of rock 8,000 miles thick, in which heat is being generated according to a certain law of distribu- tion, shows that the frictional heat could not possibly explain a rate of increase of underground temperature near the earth’s surface of more than 1° F. in 2,600 feet. It follows, therefore, that Sir W. Thomson’s investigation of the secular cooling of the earth cannot be sensibly affected by this cause. Ill. The Effects of Inertia in the Forced Oscillations of Viscous, Fluid, and Hlastie Spheres. In the theory of tides used hitherto the effects of inertia have been neglected. It was, however, shown that this defect in the theory could not have an important influence, unless the frequency of the tides was much greater than that of those generated by the moon at the present time. Nevertheless it was desirable to determine what the effect of inertia actually is. This part of the present paper contains a second approximation to the theory of tides of a viscous spheroid. VOL. XXVIII. P 198 Mr. G. H. Darwin on Tides of a Viscous Spheroid. [Dec. 19, The first approximation, being that given in the paper on “ Tides,”’ is here used to give a value to the terms introduced in the equations of motion by inertia. Physically the terms so introduced are equivalent to an addition to the bodily force which tends to produce the tidal distortion. The problem is then treated by a process parallel to that used by Sir W. Thomson in his statical problem concerning the strain of an elastic sphere. The analytical investigation is long and com- plicated, and it will here suffice to state the result with regard to the form of the tidal protuberance, when the tide-generating potential is of the second order of harmonics. It is as follows :—If a be the radius, w the density, g mean gravity, and oe v the “speed ”’ of a the tide, 7 the alteration of phase; so that 7 + v is the “lag,” and v the coefficient of viscosity. Then 7— GONE -sin 7 cos y=arc-tan TSN 150g Sgwa* And the height of tide is equal to the equilibrium tide of a perfectly fluid spheroid multiplied by— 2 COs 7 (1 Hs ie This shows that the defect of the first approximation was such that for a given speed, the lag is a little greater, and for a given lag, the height of tide is a little greater than was supposed. It is then shown that this correction to the theory of tides will scarcely make any appreciable difference in the results of the integra- tion, by which the secular changes in the configuration of the earth and moon, were found in the paper on “ Precession ;” and especially that it makes no difference as to the critical rolhtionshan between the month and day, for which the rate of change of obliquity vanishes. The most important influence of the new theory is on the time, and it appears that the time Seep by the changes, above referred to, is overstated by perhaps 3) th part. A comparison is then arade of the preceding theory with that of the forced vibrations of a fluid sphere. This shows that when 7 is zero (i.e., when viscosity graduates into Hei) the =4°, which occurs in the hap expressions should properly be 3 or =4%. The discrepancy between the 79 and 75 is explained by the fact that in approaching the problem of fluidity from the side of viscosity, we suppose in the first approximation, that the motion of the interior of the sphere is vortical, whereas in reality it is not so. In conclusion, it is proved that analysis, of almost identically the same character as that for the problem of the viscous sphere, is appli- cable to the case of an incompressible elastic sphere, and that inertia has the effect of increasing the ellipticity of the tidal spheroid, as given 1878. ] On the Influence of Light upon Protoplasm. 199 79v? 150(¢+9) to unity, where v is the speed of the tide, and r is the quantity defined in Thomson and Tait’s Nat. Phil., § 840 (28), viz., x the coeffi- 5wa? by Sir W. Thomson’s statical theory, in the proportion of 1+ cient of rigidity. The last part of the paper contains a discussion of results, and a non-mathematical summary of what precedes. IV. “On the Influence of Light upon Protoplasm.” By ARTHUR Downes, M.D., and THomas P. Buunt, M.A. Oxon. Com- municated by J. MARSHALL, F.R.S., Surgeon to University College Hospital. Received October 9, 1878. This paper is in continuation of, and supplementary to, a previous communication* in which we recorded the first part of an investiga- tion on the effect of light upon Bacteria and other organisms associated with putrefaction and decay. The chief conclusions to which those observations led us were briefly as follow :— (1.) light is inimical to, and under favourable conditions may wholly prevent, the development of these organisms; its action on Bacteria being more energetic than upon the mycelial (and torulaceous) fungi which are prone to appear in cultivation-fluids. (2.) The fitness of the cultivation-fluid as a nidus is not impaired by insolation. We found also that tubes, containing a cultivation-fluid and plugged with cotton-wool, when removed to a dark place after exposure to the sun for a sufficient period, remained perfectly clear and free from organisms for months, and we naturally thought that the contents had been reduced to permanent sterility. The following facts, however, compel us to suspend for the present our conclusions on this point. Of the many tubes which we insolated last year we finally kept only three. Two of these—containing Pasteur solution of the composition given in our former paper—had been exposed to sunlight for three weeks in June, 1877; the third tube contained urine and had been insolated for about two months—commencing July 26th. In each case corresponding tubes which were covered with laminated lead, so as to exclude light, had swarmed with Bacteria in the course of two or three days, but the three tubes of which we speak not only were perfectly pellucid at the time they were removed from the light but, although kept in a warm room, remained clear all through the winter. On February 25th, 1878, however,—eight months after we had placed * “Proc. Roy. Soc.,”’ vol. xxvi, p. 488. Pp 2 200 Messrs. A. Downes and T. P. Blunt on =[Dee. 19, them in darkness—the two tubes of Pasteur solution each contained several tiny specks of mycelium. One of the two was on this again exposed to sunlight, and in it the mycelial development was at once stopped; the other tube was left in the dark and the fungus gradually grew till it filled the whole space of the liquid, which on microscopical examination was found to con- tain no other organisms. The tube of urine remained clear till July 15th, 1878,—nearly ten months after imcasement,—on which date two specks of mycelium appeared, and subsequently developed as in the previous case. No Bacteria could be seen on examination with an immersion ;;""._ It is noteworthy that a companion tube to this which was incased after six days of insolation had developed a growth of mycelium in three or four days. It would seem that in the three tubes above mentioned Bacteria, or their “ germs,” had been either wholly destroyed or reduced to so low a state of vitality that they were unable to develope in the fluids in question; while it is evident that the spores of the mould which at length appeared, unless they had been accidentally shaken down from the cotton-wool plugging the tubes, had undergone some change which reduced them to a condition of torpidity from which in process of time they emerged. Such a condition, we may perhaps conceive, might be brought about by any influence causing thickening of the cell-wall of the spore. We hope at a future time to offer some further evidence on this question of revival of dormant germs, which is, we think, of much interest. From a very early period of our inquiry we have set ourselves to the task of investigating the intimate nature of the remarkable action of light upon these organisms, and we have arrived, as we believe, at a satisfactory solution of the problem, but in the first place it will be well to describe some preliminary experiments. An interesting point to be determined was the question,—with what part of the spectrum is this property of light associated. The observations made by us last year indicated that the rays of greatest refrangibility were the most active, but the experiments then made did not warrant any definite conclusions as to the part played by rays of lower refrangibility. The method employed in the more recent experiments was similar to that described in our former paper :— Small test-tubes containing the cultivation-fluid were suspended in deep narrow boxes made of garnet-red, yellow, blue, and ordinary glass respectively. Hach box held about six test-tubes, and corresponding series were incased in laminated lead. A spectroscopic examination of the glass of which these boxes were constructed showed that the yellow and blue were far from being monochromatic. The red was an excellent glass for the purpose. 1878.] the Influence of Light upon Protoplasm. 201 The rays which were found to pass through each glass respectively are given below. Blue.—Violet, blue, some green, broad band in yellow-green, very narrow band in ultra-red. Yellow.—The whole spectrum, except violet and about half the blue. Red.—Red, orange-red. All other rays entirely absorbed. The mean of a number of observations as to temperature showed that, at the point at which we worked, viz., 70°—80° F., the ther- mometer in the red box stood about 2° F. higher than in the lead- incased tubes; between the blue, yellow, and ordinary glass boxes there was but little difference, the blue being about half a degree warmer than the last named. We showed in our former communication that by increasing the density of our cultivation-liquid the development of Bacteria could be proportionately delayed. In this way we have been able to accentuate the differences in the behaviour of the solutions under varying con- ditions of light. Without detailing all the experiments, we may say that the first tubes to become turbid were the lead-incased ; the next, usually in from 24-—48 hours subsequently, the red, followed shortly by the yellow ;* white and blue surviving. The organisms which first appeared in the lead-incased and red were always Bacteria ; in the yellow, usually Torula, or mycelium, with more or less Bacteria,—rarely Bacteria alone; if organisms appeared in the blue or ordinary glass they were torulaceous. Although the blue and yellow glasses were not monochromatic, we think that these results give important indications. That the action is chiefly dependent on the blue and violet rays is shown by the great difference, as compared with those in the blue box, in the behaviour of the tubes in the yellow, in which, as we have already stated, the only rays of the spectrum not admitted were the violet and part of the blue. Moreover, the fact that when the cultivation-finid is of sufficient concentration the red (although the warmer) survives the lead-incased shows, we think, that the red and orange-red rays are not altogether inactive. It is probable therefore that, if the phenomena were represented by a curve, the maximum elevation would be found in or near the violet, a rapid descent occurring in the blue or green, after which the line of the curve is maintained more or less as far as the visible red. The experiments next to be detailed bear upon the part played by the cultivation-fluid in the phenomena under consideration. We had * The only instance out of a large number of observations, in which yellow broke down before red, happens to be the experiment described in our former communica- tion. | 202 Megane A. Downes and T. P. Blunt on =‘[Dec. 19, shown, in our previous paper, that the liquid in tubes which under insolation had remained barren was, nevertheless, not impaired as a nidus for development, for, on removing them to a dark place and inoculating with a drop of ordinary water, they soon teemed with vigorous bacterial life ; the same experiment showing that the survival of the spores of mycelial fungi, as compared with Bacteria, was not due to any change in the cultivation-fluid rendering it noxious to the latter, but not to the former. At the same time, though this was not probable, there might have been a temporary and transient action dependent on some constituent of the cultivation-fluid. We de- termined, therefore, to render the conditions as simple as possible. Tt is well known that all ordinary water, even distilled, teems with the “ germs”’—actual or potential—of various forms of life. We wished to ascertain whether or no sunlight would impair the vitality of, or destroy, ‘‘ germs” existing in ordinary distilled water. Fig. 1. Fig. 2 (reduced). Sealed ends of bulb bent at right angles to facilitate subsequent fracture. We made a number of glass bulbs, of the shape shown in fig. 1, into each was introduced a measured quantity of a very concentrated 1878. ] the Influence of Light upon Protoplasm. 203 Pasteur solution, previously boiled; one end of each was then sealed. They were then placed in a water-bath, with the unsealed end project- ing above the water, and after prolonged and repeated boiling this end also was sealed. The sealed bulbs were then thoroughly washed with distilled water, to remove all traces of Pasteur solution from their external surfaces, and were each finally sealed up in a tube (fig. 2) containing distilled water in such proportion that, when the bulbs were subsequently broken, the mixture produced a fluid of the ordi- nary strength. Four were incased in laminated lead and five in- solated. To prove that the water employed was capable of setting up bacterial or other development, a number of tubes containing Pasteur solution sterilised by repeated boiling and plugged with cotton wool were divided into two series ; to each tube of the one set a few drops of the water were added with a superheated pipette; to the second series no water was added, but, in order to place them under the same conditions, the superheated pipette was successively dipped into each. All of the series inoculated with water speedily teemed with Bacteria ; the second series remained clear. The experiment commenced on April 3rd. About the end of May, the bulb in one of the insolated tubes was accidentally broken, so that the concentrated Pasteur solution of the bulb mingled with the dis- tilled water of the tube. In a few days the mixture became turbid with Bacteria and Torula. We shall again refer to the behaviour of this tube. The remaining bulbs were broken towards the close of July by jerking them against the ends of the tubes. The result was that, with one exception, the mixture in the tubes which had been insolated has remained clear to the date of writing (September Ist), but in each instance the incased tubes became turbid with organisms. In the single insolated tube which broke down nothing could be seen on careful examination with ~,'' but round-celled Torula ; there was a complete absence of all bacterioid life. The incased tubes all contained Torula, Bacilli, Bacteria, in active movement, and, in two instances, a number of short, squarish, highly refractive particles. It is evident, therefore, that light is injurious to ‘‘ germs,” even when contained in ordinary distilled water. There is, however, an important fact in connexion with this which must not pass unnoticed. We have described how a tube in which the bulb had accidentally been broken after exposure to sunlight for six or seven weeks, in April and May, speedily teemed with Bacteria. It happens that, during portions of this time, we had insolated tubes, containing ordinary Pasteur solution, with the result that all bacterial development was prevented by a few days’ exposure to the sun, and organisms, if they appeared alter the tubes had been incased, were torulaceous or mycelial. There 204 Messrs. A. Downes and T. P. Blunt on _—[Dec. 19, appears, therefore, to be a remarkable differenee in the rate of action of light on the germs of Bacteria in water, as compared with its effect on corresponding ‘‘ germs” in the cultivation-fiuid; insolation of, say a week, accomplishing, in the latter case, what nearly two months failed to do in the former. The most reasonable explanation to our minds is the following :—In water destitute of organic matter the “germs” are deprived of the nourishment essential for their growth and development—they are starved; under these conditions their protoplasm reverts to a state of rest and stability, contrasting with that condition of instability which the exhibition of vital energy implies. Possibly they become encysted, the outer portion of the protoplasm being devitalised and protecting the central speck, which may be said to exist rather than to live. When, however, the “germ” finds suitable nourishment, the proto- plasm takes on a higher state of activity and, therefore, ef instability, and we believe that this instability of protoplasm favours the action upon it of light, but that in a condition of dormant vitality it is less susceptible. Numerous other observations of similar character, which we need not here detail, gave the same results, and the following simple ex- periment, repeatedly confirmed, indicates the germicidal action of light when no water, other than the ordinary moisture in air, is present :— April 15th. Four test-tubes are rinsed out with tap-water, inverted to allow the moisture to drain off, and plugged with cotton-wool. Two are covered with laminated lead, and two insolated in the usual way. (Corresponding tubes, charged with Pasteur solution previously sterilised by boiling, speedily became turbid with Bacteria.) May 1st. The four tubes are charged with sterilised Pasteur solu- tion. In about a fortnight the lead-incased tubes both became turbid,* but the liquid in the insolated tubes was still clear on July 16th. We now proceed to give an account of experiments which bear more directly on the intimate nature of the action under consideration. From an early stage in the investigation we felt that the best way of approaching the problem was by examining the behaviour of organic bodies generally when exposed to sunlight. Taking, in the first in- stance, the comparatively simple molecule of oxalic acid as the subject of our experiment, we found that a decinormal solution (‘63 per cent.) was entirely decomposed by sunlight. It was obviously important to ascertain what was the nature of the decomposition, 7.e., whether it were a disintegration of the molecule into water, carbonic acid, and * Subsequent microscopical examination showed that this was due in the one case to a species of Sarcina, in the other to Bacteria, which did not, however, take on a very vigorous development. 1878. | the Influence of Light upon Protoplasm. 205 carbonic oxide, or an oxidation resulting in water and carbonic acid alone. We found that whether oxygen was removed by exhaustion at the Sprengel pump, or by boiling the solution and inverting in mercury without access of air, decomposition was alike prevented. It was evi- dent, therefore, that oxygen was the agent of destruction under the influence of sunlight, for of course the nitrogen of the air may be put out of the question. Ke We’ next experimented on a representative of a most interesting class of bodies, which in the complexity of their composition probably approach protoplasm itself. We refer to the so-called soluble or indi- rect ferments, of which we selected zymase, the soluble ferment of. yeast, as a type. We noticed last year that sunlight had no retarding effect on the action of this class of ferments, but we did not then investigate the effect of prolonged insolation on the ferment itself. Accordingly, on June 25th, some water in which a fragment of yeast had been macerated was thrice passed through double layers of the finest filtering paper. Examined under the microscope, the liquid, which was quite clear, was found to contain no trace of Torula. Salt was then added to satura- tion, in order to avoid putrefaction, and the solution was divided between two series of test-tubes, one series being insolated, and the other incased in the usual way. On July 19th about three drachms of facstily made syrup was placed in each of a number of ¢prowvettes. These were divided into two sets ; to one set was added five grain-measures of the insolated zymase solu- tion, and to the other a corresponding quantity from the incased tubes ; a watch-glass was placed over each, and they were left for some hours. At the end of this time, five grain-measures of the syrup to which zymase from the incased tubes had been added completely reduced an equal quantity of a Fehling’s solution, while no perceptible change was caused by the syrup which had been treated with insolated zymase. It is clear, therefore, that sunlight destroys the specific power of this / ferment for hydrating cane-sugar. We next experimented on zymase in vacuo. On August 16th a solu- tion of the ferment, prepared in the same way as before, was divided between eight tubes, two of which were insolated and two incased. The remaining four were simultaneously* exhausted at the Sprengel pump and sealed. The contents gave a sharp “ water-hammer ”’ click, bearing testimony to the excellence of the vacuum. Two of these tubes were insolated and two incased. On September 5th, eight ¢prowvettes of fresh syrup were inoculated with liquid from each tube as before, and allowed to stand overnight, a * See Appendix. 206 Messrs. A. Downes and T. P. Blunt on —[Dee. 19, corresponding quantity of uninoculated syrup being kept to ascertain if any hydration occurred spontaneously. September 6th.—The uninoculated syrup has no perceptible reducing action on Fehling’s solution, but the contents of all the vacuum-tubes, whether insolated or incased, have produced hydration of the cane- sugar, and there is no practical difference between their effect—as measured by Fehling’s solution—and that of the non-Sprengelised zymase preserved in the dark. At the same time the corresponding solutions of zymase insolated without previous exhaustion have very feeble action indeed. We conclude, therefore, that, as in the case of the oxalic acid, the destructive action of light is by oxidation, for, while the zymase exposed to hght and air was greatly enfeebled, a similar solution in vacuo, although equally insolated, retained its energy apparently unimpaired.* In proceeding to investigate the nature of the action of light upon living organisms, we were met by difficulties, arising from the relation of these organisms to oxygen, which for some time baffled our research ; but these difficulties we have, we believe, sufficiently overcome to be enabled to indicate the fundamental identity of the action of light upon living organisms and upon the typical non-vitalised organic substances selected for our previous experiments. In a postscript appended to our previous communication we stated that in sealed tubes containing urine, which had been exhausted at a Sprengel pump, organisms appeared in incased and insolated tubes alike. We have made many repetitions of these experiments, and we have invariably found that, whenever organisms appeared in the incased exhausted tubes, they were simultaneously present 1y equal amount and vigour in the insolated, contrasting with the difference im beha- viour between corresponding insolated and incased non-exhausted tubes. It seemed, therefore, that in absence of an atmosphere, light (not- withstanding the manifest enfeeblement of life brought about by the * It was our original intention to examine a large number of organic bodies, and to ascertain to what extent this phenomenon of oxidation under sunlight occurred in different classes of organic compounds. The recent researches of M. Chastaing (“ Ann. de Chim. et de Phys.,”’ [5], t. xi) have anticipated us in this. M. Chastaing experimented on such organic compounds as essence of turpentine, essence of lemon, ether, oils, &c., all of which were oxidised in sunlight, the oxidation occurring im all parts of the visible spectrum, but having a maximum in violet and a minimum in red. It is noteworthy to observe how this distribution of the function of oxidation of these substances in the spectrum, according to M. Chastaing, corresponds with that assigned by ourselves on entirely independent grounds to the destructive action of light on Bacteria. We should have stated, also, that, according to our experi- ments, the oxidation of oxalic acid was very active behind blue glass, but feeble behind red. 1878. | the Influence of Light upon Protoplasm. 207 withdrawal of air) failed entirely to produce any effect on such organisms as were able to appear.* Experiments in which nitrogen was admitted into the exhausted tubes before they were sealed gave similar results. The obvious inference that the presence of oxygen is essential to this action of light is confirmed by the following experiment—many times repeated—showing that the effect isin direct relation to the proportion of free oxygen :— A Pasteur solution of half the strength given in our former paper, and therefore, for reasons stated in that paper, difficult to sterilise by insolation, was divided between six tubes. Two of these were simply sealed, and therefore contained an atmo- sphere of ordinary air. Two were exhausted at the Sprengel pump till the gauge stood at a height of 22 inches, when, by means of the apparatus described in the Appendix, nitrogen was admitted, and the tubes being sealed, conse- quently only contained about one-twentieth of oxygen in their atmo- spheres. The remaining two tubes were exhausted thoroughly and pure oxygen admitted in the same manner as the nitrogen. One tube of each series was incased in laminated lead, the com- panion tube being insolated. In two days all the incased tubes were equally turbid with Bacteria. In two days more the insolated tube, with »>th oxygen atmosphere, was turbid with Torula and Bacteria. Next day after this, the insolated tube, with an atmosphere of ordinary air, became hazy with Bacteria. The tube, with an atmosphere of pure oxygen, remained unchanged for some days later, when a deposit of Torula commenced to form at the bottom. We conclude, therefore, both from analogy and from direct experi- ment, that the observed action on these organisms is not dependent on light per se, but that the presence of free oxygen is necessary ; light and oxygen together accomplishing what neither can do alone: and the inference seems irresistible that the effect produced is a gradual oxidation of the constituent protoplasm of these organisms, and that, in this respect, protoplasm, although living, is not exempt from laws which appear to govern the relations of light and oxygen to forms of matter less highly endowed.t A force, which is indirectly absolutely * The commonest form of organism in these exhausted tubes consisted of filaments of varying length, ranging perhaps from 544,” to 34,”, often curvilinear, composed of minute spherules in linear series, with motion usually vibratory and undulating, frequently progressive. + That the amount of free oxygen present need not be large to produce a definite action upon Bacteria is shown by the fact that tubes containing Pasteur solution with a supernatant layer of vaseline, excluding all air, except that previously dissolved in the solution, if encased, in a few days become turbid, but may be kept clear for 208 Messrs. A. Downes and T. P. Blunt on _—[Dec. 19, essential to life as we know it, and matter, in the absence of which life has not yet been proved to exist, here unite for its destruction. The organisms (Bacteria) on which we have mainly experimented, in their ordinary conditions of structure and development, afford an example of protoplasm in a simple and uncomplicated form, but it would be unreasonable to suppose that this protoplasm is so essentially different in its fundamental constitution from all other protoplasm that here, and here only, is this special effect of light to be found. There are, indeed, many facts which prove the contrary, and indicate that we are dealing, not with a special and fortuitous phenomenon, but with a general law. But protoplasm may be very differently circumstanced in its relations both to hght and oxygen, it may be protected. Such pro- tection may be afforded by :— 1. Thickened, or opaque, cell-walls or envelopes. 2. Special colouring matters, which filter out the more injurious rays. 3. Aggregation of cells, whether free or combined into tissue, the inner being protected by the external. 4. Relation of the protoplasm itself to oxygen. The first three are sufficiently obvious, but, as regards the last- named condition of protection, a few words of explanation are necessary. Protoplasm in its relation to oxygen varies widely. In the vast majority of cases, oxygen in its free gaseous state, appears to be absolutely essential for the development and reproduction of proto- plasmic life, but the labours of Pasteur have sufficiently demonstrated the power of some organisms, living in absence of free oxygen, to take it from certain of its combinations. During the present summer we have been continually troubled in our investigation by the fact, that either our materials, or the air in which we worked, had become in- fected with a species of small Torula. Solutions exposed to sunlight would remain clear for a few days—their incased companions in the meantime becoming turbid with ordinary Bacteria—but slowly and gradually a deposit would form at the bottom of the solution, which, on examination, would prove to be the Torula in question. Now, if we consider the rapidity with which Torula removes dis- solved oxygen from water,* and the comparative slowness with which a considerable period by insolation. This fact, as well as others, shows, by the way, that the action does not depend on ozone formed, as Gorup v. Besanez believes (“ Ann. Chem. Pharm.,” clxi, 232) is invariably the case when water evaporates. We have, we may observe, never been able to detect the formation of active oxygen as ozone, or peroxide of hydrogen, in cultivation solutions or in water exposed to sunlight. : * Schtitzenberger, “Fermentation,” pp. 107 and 134. 1878.] the Influence of Light upon Protoplasm. 209 water dissolves that gas, we shall at once see that the Torwla, deriving its respiratory oxygen from the sugar of the solution, is all this time living comparatively in absence of free oxygen, and we understand how the relations of protoplasm to oxygen, by enabling it in some forms to be largely independent of the uncombined gas, may prove a source of protection against the oxidising action of light. In some cases, indeed, the affinity of organisms for oxygen would appear to be so great that, when presented to them in its gaseous and uncombined state, it acts, not as a source of vital energy, but as a poison, and we think that protoplasm will be found to possess varying degrees of tolerance of excess or deficiency of this element. To some forms of life, if Pasteur be right, oxygen is injurious even when diluted as in ordinary air, to others it is hurtful only when oxidation is quickened by some adjuvant force, as, for example, by light. Finally, since light here acts as an oxidiser, it is conceivable that there may exist sluggish forms of protoplasm, whose oxidising pro- cesses, and, therefore, general growth and development, may be favourably augmented by a modified degree of ight. We are not of our present knowledge, however, able to point to such.* In connexion with the subject of this paper, it is an interesting speculation whether any one of the constituent elements of organic bodies is specially subject to oxidation under light. We seem to have obtained some glimpse of a possible answer to this question by a few experiments upon the oxalates. If the constitutional formula C—O—O—H of oxalic acid be rightly represented thus, ||| , a mode of approach to the problem seems to be opened, for should we find on substituting some other element for the hydrogen that decomposition is no longer produced by light, the conclusion would seem inevitable that the destruction of the molecule of oxalic acid was effected through the oxidation of the hydrogen. On July 26th a solution of neutral oxalate of potash of decinormal strength was divided between a number of test-tubes, some of which we incased while some were insolated in the usual way. At the same time a decinormal solution of oxalic acid was similarly treated. August 26th. The insolated oxalic acid solution is completely decom- posed, but the incased oxalic acid solution is unaffected. The solutions of oxalate of potash, both incased and insolated, remain quite un- changed, and are still neutral to test-paper. * From what we have said, it would follow that the organisms most injuriously affected by light would be found to be those whose protoplasm is “unprotected,” having high affinities for oxygen, but yet for the most part requiring it uncombined, and at the same time being so minutely particulate as to offer in point of surface the greatest facility for access both of light and of oxygen, all of which conditions are exemplified by the ordinary forms of Bacteria. 210 Messrs. A. Downes and T. P. Blunt on —‘[Dec. 19, We are justified, therefore, in concluding that, in this case at least, the destruction of an organic body in lght is due to the oxidation of its hydrogen. APPENDIX. Vacuum Apparatus.—In conducting our experiments in vacuo, or in a modified atmosphere, obtained by means of the Sprengel pump, it was necessary to ensure that the tubes compared should be under exactly similar conditions with regard to pressure; and it seemed desirable, therefore, to exhaust the pairs, or double pairs, at one opera- tion. With this object an adapter was contrived, which, though simple in its construction, proved so efficient that it may be worth while to describe it in detail. Fie, 3.—a, “shoulder.” 6, the point of sealing after exhaustion. A piece of glass tubing, 13 inches long, ¢ inch in diameter, and open at both ends, which were slightly lipped, was fitted with two caoutchoue stoppers, one of which, pierced with a single hole, served for connexion 1878. ] the Influence of Light upon Protoplasm. 241 with the entrance tube of the pump, while the other had bored in it four holes into which the ends of the experimental tubes were pushed until the “shoulder” (see fig. 3) was firmly thrust against the india- rubber. All junctions were luted with viscid glycerine, and it was found that a good vacuum could then be produced and maintained for a considerable time. . In order conveniently to seal off the tubes they were again drawn out below the shoulder, so that when complete they had the shape given in the figure (fig. 3). When atmospheres of special composition were required the mode of procedure was somewhat different; one of the four holes in the outer caoutchouc stopper was then appropriated to a gauge, formed of a straight piece of tubing of sufficient length, dipping under mercury : into another hole was fitted a glass tube to which was attached a piece of india-rubber tubing with a clamp. The pump was then worked until the gauge showed the required tension, when the gas was admitted from a small gasholder by attaching the stop-cock of the gasholder to. the india-rubber tubing and opening the clamp. The nitrogen used was prepared by removing the oxygen from atmo- spheric air, either by the prolonged action of alkaline solution of pyrogallic acid, or, in some instances, by the combustion of phos- phorus; in the latter case the oxides of phosphorus were removed by agitating with solution of caustic potash. Our oxygen was made by heating pure chlorate of potash alone in a tube of hard glass; lest any trace of ozone or chlorine should be present the gas was slowly bubbled through solution of iodide of potash; this precaution, however, appeared to be superfluous, the iodide solution remaining colourless. Postscript. Received October 18, 1878. The oxidation of hydrogen by light, demonstrated in the case of oxalic acid, naturally suggests an inquiry into the deportment of oxygen towards hydrogen in sunlight under other conditions. We have not, for the present at least, an opportunity of examining this question in the detail which it demands, but we think that it may be of interest to append to our paper the following brief observations. One of the best known facts in the chemistry of light is the combi- nation effected between chlorine and hydrogen, and in their behaviour towards hydrogen under the influence of light the halogens form an interesting series. Thus, while chlorine and hydrogen unite explosively in sunlight, bromine and hydrogen are with difficulty, if at all, induced to combine, and iodine and hydrogen do not unite at all. Again, water may be decomposed with the aid of sunlight both by chlorine* and by * Cl,+ H.O =2HC1+0. 212 Prof. J. Tyndall on the Influence exercised [Dec. 19 bromine,* but not by iodine. Finally, while hydrochloric and hydro- bromic acid in aqueous solution each resist decomposition when insolated in the presence of free oxygen, it is known that hydriodic acid under like conditions is rapidly destroyed.t This destruction, according to our experiments, is promoted by all the rays, but is mueh less active behind red glass than behind blue. It occurs also, but more slowly, in the dark. Here we appear to have a phenomenon analogous to the oxidation of the hydrogen of oxalic acid. The question arises how far a preliminary dissociation of the con- stituent atoms of the molecule may influence the reaction. It has been clearly shown by M. Lemoine} that hydriodic acid gas is completely dissociated by light; but the same observer states that in aqueous solution no such dissociation in sunlight can be demonstrated—a fact observed also by M. Berthelot. It may be, however, that the phe-. nomena of dissociation and oxidation under light may go on:side by; side, the presence of oxygen promoting the splitting of -hydriodic acid by its determining affinity. In like manner it may be that in the. decomposition of oxalic acid the oxygen plays a simiar part, deter- mining the dissociation of C,O,.H2, and replacing the dissociated , radicle C,0,. The analogy of chlorine, however, leads us to the belief that, in its relations to hydrogen under the influence of light, oxygen may be classed with that element; but the-reactions above noted would seem to indicate that, under these conditions, its affinity for hydrogen is inferior to that of either chlorine or bromine.§ We would note also the following known reactions which occur in air and sunlight : (i) he decomposition of arsenamine with formation of water and deposition of arsenic. (2.) The absorption of oxygen by and precipitation of sulphur from sulphuretted hydrogen ;—reactions which, although coon a in ae dark, are accelerated by sunlight. | V. “Note on the Influence exercised by Light on Organic In- fusions.” By JoHN TYNDALL, D.C.L., F.R.S., Professor of Natural Philosophy in We poe Teenie Received Wecember 7, Nereus. Harly last June I took withane to the Mane 50 small hermetically sealed flasks containing infusion of cucumber, and 50 containing * Bry +H,0 =2HBr+ 0. 4 21h Olay On) eas t “ Annales de Chim. et de Phys.,” [5], t. xi. § Under ordinary conditions the direct combination of oxygen and hydrogen gases does not occur in sunlight. 1878.] by Light on Organic Infusions. 213 turnip infusion. Before sealing they had been boiled for five minutes in the laboratory of the Royal Institution. They were carefully packed in sawdust, but when unpacked the fragile sealed ends of about 20 of them were found broken off. Some of these injured flasks were empty, while others still retained their liquids. The 80 unbroken flasks were found pellucid, and they continued so throughout the summer. All the broken ones, on the other hand, which had retained their liquids, were turbid with organisms. Shaking up the sawdust, which I knew must contain a considerable quantity of germinal matter, I snipped off the ends of a number of flasks in the air above the sawdust. Exposed to a temperature of 70° or 80° F., the contents of all these flasks became turbid in two or three days. The experiment was repeated; and after the contaminated air had entered them, I exposed the flasks to strong sunshine for a whole summer’s day; one batch, indeed, was thus exposed for several successive days. Placed in a room with a temperature of from 70° to 80° F., they all, without exception, became turbid with organisms. Another batch of flasks, after having their sealed ends broken off, was infected by the water of a cascade derived from the melting of the mountain snows. They were afterwards exposed to a day’s strong sunshine, and subsequently removed to the warm room. In three days they were thickly charged with organisms. On the same day a number of flasks had their ends snipped off in the open air beside the cascade. They remained for weeks trans- parent, and doubtless continue so to the present hour. I do not wish to offer these results as antagonistic to those so clearly described by Dr. Arthur Downes and Mr. Thomas Blunt, in the “Proceedings of the Royal Society,” for December 6th, 1877.* Their observations are so definite that it is hardly possible to doubt their accuracy. But they noticed anomalies which it is desirable to clear up. On the 10th of July, for example, they found 9 hours’ exposure to daylight, 3 hours of which only were hours of sunshine, sufficient to effect sterilization; while, on the 29th of July, “a very hot day, with much sunshine,” 11 hours’ exposure, ‘‘9 of which were true insolation,” failed to produce the same effect. Such irregu- larities, coupled with the results above recorded, will, I trust, induce them to repeat their experiments, with the view of determining the true limits of the important action which those experiments reveal. * Vol. xxvi, p. 488. VOL. XXVIII. Q 214 Mr. W. K. Parker on the Structure and _[Dec. 19, VI. “On the Structure and Development of the Skull in the Lacertilia. Part I. On the Skull of the Common Lizards (Lacerta agilis, L. viridis, and Zootoca vivipara).” By, W. K. PARKER, F.R.S. Received October 18, 1878. (Abstract. ) The youngest, and therefore the most important, embryos that have been worked out in this present piece of research, were sent me, with those of the snake, by Dr. Max Braun, of Wirzburg. Other valuable specimens were the gifts of Professor T. Rupert Jones, F.R.S., and Professor Alfred H. Garrod, F.R.S. The three species worked out are closely related, and two of them are native to this country: these familiar Sand Lizards are amongst the smallest, and yet the most highly specialized, types, to be found among the Reptilia. This type may be taken as a sort of “norma,” and by it all the other Lacertilia may be measured, as it were, when their height in the Reptilian scale is to be determined. When such forms as Hatteria and the chameleon are compared with a typical Lacertian, then we see how much there is that is gene- ralized in those outlying species. Putting together what I have learned as yet of the structure of the skull in the true Reptiles, and comparing what is seen in these cold- blooded Sauropsida with what is seen in the hot-blooded bird, I have come to the conclusion that the common lizard is a culminating type. The snake, the tortoise, and the crocodile, notwithstanding their own peculiar specializations, are yet more general in their nature than the nobler and higher kinds of lizards: this is especially shown by the number of characters that are, in the latter, in conformity with those of the bird. And, indeed, with the high or Carinate bird; for the skull of the Ratitee (ostrich and cassowary) does not.undergo, in several things, so much metamorphosis as the skull of the typical lizard; for, as I showed long ago, these birds are not devoid of a Batrachian strain. Of all the hzards known to me the chameleon is the lowest; in some respects the Chelonians come nearer the higher Lacertilia than that bizarre type does. I have carefully worked out the skull in the adult and the ripe embryo of the common kind, and in the adult of the dwarf species. In several things the lizard’s skull is but little modified from that of the snake; this is especially seen in the nasal structure, its glands, | and the bones of its floor; so largely illustrated in my last paper. These things are not repeated in the Chelonia and crocodiles, nor do they exist in the chameleon; but in many birds, especially the 1878.]| Development of the Skull in the Lacertilia. 215 “songsters,” these curious specializations reappear, but the parts are lessened and modified. Even many of those metamorphoses of the skull, which when I worked out that of the chick seemed to me to be peculiarly avian, and indeed not to be found amongst the almost reptilian Ratite, now turn out to be lacertian also. For instance, the separate cartilages that pad the ‘ basi-pterygoid processes” of the skull and the pterygoid bones, at their articulation, these appear in the lizard; and even the division of the septwm nasi from the ethmoidal wall begins in Lacerta, and other lizards. That separation of the two regions has its explanation in the higher birds, whose fore face hinges on the skull; notably in the parrot. In Lacerta it is a mere “ fenestra,” of no use to the creature ; so it is in the semi-struthious Tinamou, and in some low, Southern passe- rine birds, e.g., Grallaria squamigera. But in the huge Ratite it is as absent, as in the Chelonia, and the low chameleon. This latter kind has no column-shaped bone on the pterygoid (‘ epi- pterygoid”); that bone exists but is small and modified in the Che- lonia; in birds, especially the “‘ songsters,” it is manifestly a process of the pterygoid, but I have never seen it as a distinct bone. These are some of the more striking characters in the skull of the adult lizard and its sauropsidan relatives, namely, snakes, tortoises, crocodiles, and birds: the latter, it may be remarked, differ less in their structure from a lizard than many an imago-insect does from its pupa. I have a strong suspicion that the serpent is degraded as well as more ancient and generalized, as compared to the lizard: it has mani- festly lost its limbs, and the correlate of that loss is an arrest of the cartilaginous cranium. The small rudiments of orbitosphenoids and alisphenoids, seen in the snake, are no longer an anomaly and unexplainable: they are patches of the large tracts in the lizard, which has, contrary to what I long believed, a large alisphenoid on each side. This part is not a continuous flap of cartilage: in the bird it is, but it always has a great fenestra in its middle, even in them; in the lizard it is multi-fenestrate—a mere basket-work of cartilage, feebly and partially ossified. In its auditory structures the high Lacertian corresponds very closely with the tortoise and the crocodile, and these three kinds differ only in non-essentials from the bird. The snake and the chameleon lie below them all, but the chameleon is lower than the snake, and has a worse ear than most frogs and toads. The lower jaw of the lizard and the nestling bird agree very closely. ‘The remains of the hyoid and branchial arches are far more ichthyic in the lizard than in the bird. Q 2 216 Mr. W. K. Parker on the Structure and __[Dec. 19, From familiar things I pass to things little known; that is, to the early stages of the lizard. In the early stages I cannot confine myself to the nerve-supporting organs, but, of set purpose, let my work overlap that of my friend Mr. Balfour, who is, to me, the typical embryologist; Mr. Milnes Marshall’s excellent papers, however, are not forgotten. Much that is figured of the earlier stages is not described; my illustrations can, however, easily be compared with those of the chick in Foster and Balfour’s work; and with the copious and exquisite illustrations given in Mr. Balfour’s work on the ‘‘ Hlasmobranchs.” The reader is asked to refer to these works, especially the latter ; that he may see how perfectly my observations on the embryo of the lizard correspond with what Mr. Balfour has discovered in other types. Some of the most important of them relate to structures that must be well understood before we can gain even the most elementary con- ceptions of the morphology of the vertebrate skeleton. These are—the brain and main nerves; the sense-capsules; the respiratory openings (clefts) through the wall of the throat; the “pituitary body,” and its relation to the mouth and brain; and the extension into and subdivision of of the pleuro-peritoneal cavity in the head, even in front of the mouth. The modification of the “segmental” muscular masses in the head ; the difference between the axial structures of the head and the body ; all these things have to be carefully attended to. I will now propound my own theory of the skeleton of the head and throat, as compared with the skeleton of the body generally, namely, the spine and thoracico-abdominal cavity. The undivided condition of the paired tracts, on each side of the notochord, which is so constant in the head, is the original state of things; the head is archaic, the trunk, with its vertebre intercalating © with the muscle-plates, is a much more modern result of evolutional metamorphosis than the undivided head; the lmb-girdles and limbs are the newest of all. Archaic entomocranial Vertebrates, had no vertebree, properly speak- ing; they had a long head, composed of fourteen or fifteen segments ; their throat was a large multiperforate bag; and instead of haying one vagus nerve, they had seven or eight pairs of vagi, forking over al] the respiratory passages, except those supplied by the glosso- pharyngeal and portio dura. Some of them were lke Cecilians; they had long, vermiform bodies, and scarcely any tail behind their anal opening; they had no finished vertebree, but a semi-solid, half-cartilaginous tube, surrounding the notochord. Others were a sort of exaggerated tadpoles; they were the fathers 1878. ] Development of the Skull in the Lacertilia. 217 of all such as gradually improved into the larval condition (for a long while permanent) of the modern Batrachia, but they were Ametabolous, or arrested. These ancient bull-heads had a huge pharynx, under which, more than behind, a very short abdomen was swung, with a snake-coiled intestine ; their body was a mere lash, like the lash on the tail of the larva of the smooth newt and Dactylethra, and the lash of the tail of the adult Chimera. The forms from which the Marsipobranchii on the one hand, and the Ohimera on the other, sprung, were intermediate between the two extreme forms imagined; they were, however, close akin to the primordial tadpole. What the pituitary body was, at that time, when the meso- cephalic flexure just appeared; how the vesiculation of the neural axis arose; and whether the sense-capsules were at first paired or unpaired; of these things [ will speak when I have obtained more light upon this dark subject. But, even in the foggy illumination of the present, we can make out that even the term ‘‘ the vertebral theory of the skull,” is absurd ; vertebra, as such, are a late specialization of a segmented creature, whose mouth is opposite its nervous axis, and on the same aspect as its main circulating organ (hemostomous). For a long while there was no definite division into head and body; the Selachians show this to this day; their investing mass or parachordal tracts run on from the head into the body without division: the occipito-atlantal articulation is very late in its appearance. Moreover, both the lamprey and Heptanchus show (or indicate) that the head of modern Vertebrates has been greatly shortened— much more than their throat; the cervical vertebra are new segments of the axis, intercalated at that part, to bind the shortening head to the retreating body. This view is curiously strengthened by an observation of Mr. Balfour’s, with regard to the formation of ‘‘somatomes” in the cervical region of the chick; the foremost do not appear first, but the 4th, Sth, 6th, &c., are to be seen first, and then the three front segments. Dr. Milnes Marshall’s observations on the segmental nerves of the chick,* showing that the third, or motor oculi, is as good a segmental nerve as the great oth, or trigeminal, and that the olfactory or first nerve is developed exactly in the same manner as the other cranial nerves, namely, from the dorsal region of the “epiblast;” these discoveries, I think, are of the greatest importance, and are very suggestive. * See “Quarterly Journal of Microscopical Science,” vol. xviii, New Series, Plates 2, 3, pp. 1—3l. 218 Mr. 8S. H. Vines on the - [Deents; Even those who are content to work at the development of the low- lier types, such as the worm and the cray-fish, are helping at this good work, for they are throwing light upon the evolution of the Vertebrates. VII. “On the Chemical Composition of Aleurone Grains.” By SyDNEY H. Vings, B.A., B.Sc., F.L.S8., Fellow and Lecturer of Christ’s College, Cambridge. Communicated by Dr. MIcHAEL Foster, Prelector of Physiology in Trinity Col- lege, Cambridge. Received October 22, 1878. I. The Aleurone Grains of the Blue Lupin. (Lupinus varius.) The proteids stored up in the seeds of certain plants, more especially of Leguminose, have been stated by various observers to exist in the form of the vegetable caseins such as Legumin and Conglutin, and this view has been advocated of late years more particularly by Ritthausen (‘‘ Die Hiweiss-Korper der Getreidearten, &c., 1872”). In 1877, Weyl published some observations (‘“ Zeitschr. fiir Physiol. Chemie, Bd. I), which tend to show that the proteids exist in the seeds of these plants in the form of globulins, and that the caseins, extracted by Ritthausen and others, are the products of the alteration of the globulins effected by the reagents (alkaline solutions) used in their extraction. ; In order to be in a position to form a decided opinion upon the sub- ject, I first repeated Weyl’s experiments, using the seeds of the blue lupin. I found that on treating the ground seeds with 10 per cent. . NaCl solution, I obtained a fluid which gave all the reactions charac- teristic of fluids which hold globulins in solution. On dilution with water it gave a precipitate of a substance soluble in 10 per cent. NaCl solution (vitellin); and on saturating it with NaCl (rock-salt), a substance (myosin) was precipitated which was soluble im 10 per cent. NaCl solution. With the view of ascertaining the value of Weyl’s suggestion, that the casein (conglutin, Ritthausen) contained in the lupin was a pro- duct of the alteration of the globulin under the action of an alkaline solution, I made the following experiment: — About 50 grms. of the ground lupin-seeds were placed on a filter, and 250 cub. centims. O-l per cent. NaHO solution poured over them. The fluid ran through in a few minutes, and was found to give the reactions characteristic of alkaline solutions of vegetable casein (see “‘Sachsse, Chemie und Physiologie der Farbstoffe,” &c., 1877, p. 267). The residue on the filter was then well washed with distilled water until the washings ceased to give an alkaline reaction. It was then treated with 250 cub. centims. 10 per cent. NaCl solution, and on testing the filtrate it was 1878. | Chemical Composition of Aleurone Grains. 219 found to hold much globulin in solution. The residue on the filter was then placed in a beaker with 500 cub. centims. of the 0:1 per cent. NaHO solution, and allowed to stand for twenty-four hours. At the end of that time the alkaline fluid was poured off, and the residue placed on a filter and well washed with distilled water. On treating it with 10 per cent. NaC! solution it was impossible to extract from it more than the merest traces of globulin. It appears, therefore, that the globulin had become altered by the action of the alkaline fluid, that it had in fact become dissolved in it in the form of alkali-albumin. This change probably occurs in the extraction of conglutin by Ritthausen’s method. Moreover, I found that conglutin prepared according to Ritt- hausen’s methods gives reactions which are characteristic of the substances formed when various animal proteids are treated with dilute acid or alkaline solutions (acid-albumin, alkali-albumin), and it does not differ very widely from these substances in elementary com- position. These facts support the view that conglutin is merely a pro- duct of the alteration of the true reserve-proteids. Weyl had already shown that no proteids, except such as are soluble in 10 per cent. NaCl solution, can be extracted from the seeds by treating them with 1 per cent. Na,CO; solution. ‘This proves that conglutin does not pre- exist in the seed. I therefore agree with Weyl in concluding that the proteids stored up in the seeds of the blue lupin consist of globulins (vegetable vitellin and vegetable myosin). Subsequent ohservations, however, assured me that this is not the only form in which the reserve-proteids are present. I found that the 10 per cent. NaCl extract of the seeds contained, in addition to the globulins, a proteid in solution, which was not precipitated by boiling, or by saturation with rock-salt, or by dilution with distilled water. This substance may be isolated by extracting the ground seeds with distilled water ; boiling the extract several times to remove all traces of globulin ; evaporating to small bulk over a water-bath, and allowing the fluid to filter into absolute alcohol. As it drops into the alcohol a dense pre- cipitate is formed. The substance which is thus precipitated is readily soluble in distilled water even after being exposed for months to the action of alcohol. Its solution in distilled water does not become turbid on boiling; it gives a precipitate on the addition of a drop of HNO, which is soluble in excess of acid; it gives the xanthoproteic and Millon’s reactions; it gives an immediate precipitate with acetiv acid and potassic ferrocyanide; and it gives a bright pink colour when treated with excess of strong NaHO solution on the addition of a drop of dilute CuSQ, solution. The substance does not dialyse. These ' properties and reactions indicate that the substance is allied to the peptones. It most nearly resembles the a peptone of Meisoner, or, 220 On the Chemical Composition of Aleurone Grains. [Dec. 19, adopting Kiihne’s nomenclature (‘‘ Verhandl d. Nat.-Med. Vereins zu Heidelberg,” Band I, 1876), the substance to which he gives the name of Hemialbumose; a name which may be provisionally applied to this substance also. The proteids stored up in the seeds of the blue lupin are therefore of two kinds: (1.) Hemialbumose—soluble in distilled water. (2.) Globulins—insoluble in distilled water, but soluble in 10 per cent. NaCl solution. In order to determine the exact distribution of these substances in the cells of the seed, I made a series of micro-chemical observations. Thin sections of the cotyledons were placed for a few minutes in ether and then in absolute alcohol, in order to remove the fatty matters present which would otherwise interfere with the observation. A section examined in a drop of absolute alcohol shows the cells filled with aleurone grains lying in the meshes of a delicate matrix. They are hyaline or faintly granular, and have a yellowish tint. On adding afew drops of distilled water the grains become coarsely granular ; the granules gradually disappear, and then vacuoles make their appear- ance. Further treatment with water produces no apparent change. If now a few drops of 10 per cent. NaCl solution be added, the hyaline vacuolated grains at once disappear, and nothing remains in the cells (when the section is very delicate) but the network of the matrix. A precipitate may be produced in the fluid under the cover-slip by diluting it with distilled water. The precipitate assumes the form of rounded drops of a viscous nature which are readily redissolved on the addition of NaCl (vegetable vitellin). If the section be irrigated with 10 per cent. NaCl solution until the addition of distilled water pro- duces no precipitate, and if it be then well washed with distilled water nothing remains within the cells but the matrix. This is ren- dered conspicuous by adding a drop of solution of iodine which gives it a bright yellow colour. It is well known that aleurone grains consist essentially of proteids, but the nature of these proteids has not as yet been determined. From the foregoing observations it appears that at least one proteid is pre- sent which is soluble in water, and one which is insoluble in water but soluble in 10 per cent. NaCl solution. The preceding chemical expe- riments suffice to prove that the former is hemialbumose, and that the latter includes the two forms of vegetable globulin. My observations on the solubility of the aleurone grains of the blue jupin in water agree in the main with those of Pfeffer (“‘ Unters. tiber Protein-Korner, &c. Jahrb. f. Wiss. Bot.,”” Band VIII, 1872, p. 447), but I have been unable to discover that, as he asserts in the case of Peonia and Cynoglossum at least, long continued exposure to alcohol diminishes their solubility in water. Such treatment affects neither 1878.] ° Phyto-Paleontological Investigations. a the solubility of the hemialbumose in water, nor that of the globulins in 10 per cent. NaCl solution, but it renders the protoplasmic matrix of the cells quite insoluble in dilute alkaline solutions. These facts were established by experiments with grains which had been in alcohol for three months. I have detected the presence of hemialbumose in the seeds of vetches and of the hemp and flax plants, and I propose to study the mode of its occurrence in the seeds of these and other plants, as I have already done in the case of the blue lupin, and further, to determine what is its exact significance in the process of germination. VIII. “Report on Phyto-Paleontological Investigations generally and on those relating to the Eocene Flora of Great Britain in particular.” By Dr. CoNSTANTIN BARON E'TTINGSHAUSEN, Professor in the University of Graz, Austria. Communi- cated by Professor HUXLEY, Sec. R.S. Received December 12, 1878. When, about thirty years ago, I began to direct my attention to the study of the fossil Flora, the knowledge of fossil forms of plants was confined almost exclusively to forms of the Paleozoic formations. Of the Tertiary Flora there existed at that time a very imperfect concep- tion; but few beds of Tertiary plants were known, and these had been only superficially examined. Leaf-skeletons had not been examined, and consequently the characteristic marks upon them were not avail- able for the purpose of instituting a comparison with the fossil leaves. The fossils themselves were only obtained from stones which had been exposed to the air, and were easily split asunder, and it was thus im- possible to arrive at any accurate knowledge of the nature of the old world plants. In fact, parts of one and the same plant were often regarded as plants of different genera. Thus on making a closer and more careful investigation into the Coal Flora of Bohemia, I was able to show that the Asterophyllites are the branches, and the Volkmannie the fruits of the Calamites. It appeared to me, therefore, necessary that I should devote myself to the study of the so-much-neglected Flora of the Cainozoic forma- tions. With this object in view, I determined :— Firstly, to collect fossil plants as completely as possible, in order that my investigation should produce results on which I might entirely rely. Secondly, to improve the method of inyestigation, especially with regard to the working out of the skeletons of the leaves of living plants, so as in that way to acquire sure standpoints from which to determine the species of the fossil leaves. Lhirdly, not to confine the scope of the inquiry within the limits of 222 | Baron Ettingshausen. [ Deez; mere paleontological interest, but above all to extend it to the unveil- ing of the history of the development of the whole vegetable kingdom. As in studying the Eocene Flora of Great Britain I shall follow the path of the inquiry which I originally took, I must begin by giving an account of my method of investigating fossil plants, and I shall then explain the results which I have obtained. I.—The Method of obtaining Fossil Plants. It has been usual to collect fossil plants by splitting the pieces of rocks with ahammer. The more a stone has been exposed to the action of the weather, the easier it is to break it and lay bare what is within. But fossil plants found under such circumstances are no longer in good preservation: they have suffered greatly from exposure to the weather, and generally only the outlines are visible; their structure and the finest veins of the leaf-skeleton are lost. Stone when it has not been exposed to the air is not easily split; the more compact it is the more difficult it will be found to obtain the fossils in this way. Under favourable circumstances only fragments of the fossils are obtained. By the forcible splitting of pieces of rocks with a hammer it is only possible to succeed very imperfectly in obtaining fossil plants, besides which it must always be a lucky chance that the hammer strikes that part of the stone in which the plants he concealed, and that it has not been injured by the blow, for a large number of fossils are lost in this way, or remain undiscovered in the stone. I have found a method by which fossil plants can be satisfactorily got out of the most compact rocks without using a hammer. The pieces of rocks are for a considerable time subjected to a thorough soaking under the pressure of two or three atmospheres. In an iron vessel full of water brought into connexion with a stand-pipe the stones are left lying for half a year (most advantageously in summer- time). In those places where there is a fossil in the stone the material of the stone is not continuous. Thus numerous, often microscopi- cally small, splits and other hollow spaces are found along the fossil plants. These hollow spaces get filled little by little with water. Then the stones which have been treated in this manner are exposed to an intense cold, —15° to 20° C. The water in the hollow spaces is turned into ice, and by this means the stones are burst asunder on the _ spot where there are petrifactions. The stones open of themselves, and show what they contain. The more compact the stone the surer and more complete by this method is the successful acquisition of the fossil plants. They show the original state in which they were pre- served. With very hard stones the soaking and the subsequent freezing must be frequently repeated. On the first action of. the frost the splits and hollow spaces are widened by the formation of ice within them to the surface of the stone. These must be quite filled again with 1878. | Phyto-Paleontological Investigations. 223 water; the stone will thus be raised to a higher temperature and again exposed to the soaking process. The ice formation and the soaking being thus employed alternately, the widening of the splits increases, till at last the stone opens of itself exactly along the enclosed fossil, which then comes to the light of day uninjured and in the best state of preservation. This method offers not only the advantage of securing for investiga- tion the most complete and well preserved fossil plants, but it yields also a much larger amount of material than could be obtained by the old method of forcibly splitting with a hammer. In this way no fossil can be lost. All the fossil plants in the stones are uninjured. Luck and chance are excluded. To obtain an abundant supply of useful material for investigation is of the greatest importance for the study of Phyto-Paleontology and must lead to better and surer results. II.—Method of Investigating Fossil Plants. Phyto-Palzontologists have hitherto made too many species. Un- fortunately authors have been too readily disposed to adopt as a new species every slightly differing form. Consequently not only is science encumbered by a useless burden, but it is itself brought into a discredit which has occasioned serious injury to the progress of this branch of science. The most important way of remedying this evil, lies in procuring abundant material for investigation, showing a series of forms, and thus causing the false species to disappear. A collection of fossil plants acquired by careful study must therefore contain not only rare specimens, but as large a number as possible of a series of forms of common fossils. These series should be divided into two groups, the series of the contemporaneous, and of the non-contemporaneous (genetic) forms. The first is obtained by the bringing together the forms of a fossil out of the extension of one and the same layer (horizontal extension), the second in the searching for a fossil in different horizons (vertical extension). The latter series supplies the material for the phylogeny of the species, the complete elucidation of which is of the highest importance for the history of the develop- ment of the vegetable world. A second way of removing the above-mentioned unsatisfactory state of things would be to put aside certain obsolete notions and prejudices. People are prone to admit mere differences of stratigraphical position as sufficient ground for the acceptance of a particular species, when indeed there appears to be no substantial reason arising out of its distinctive character. Only too often an insignificant difference of form, then re- garded as important, is held to justify the acceptance of a species, if the fossil belongs to another horizon or another formation. My experience, however, has led me to the conclusion, that, in many cases, one species passes through many horizons and indeed through greater periods, 224 Baron Ettmgshausen. , (Dee mms, and that the number of the species is reduced all the more rapidly the more remote the Flora is from that of the present world. But of | this more later on. The method of investigating fossil plants must, above all things, be directed to their exact classification, and consequently to a knowledge of the facts on which the history of the development of the vegetable kingdom is supported. This however is only made possible by most carefully comparing fossil plants with living ones. Unfortunately, in this respect, so many faults and mistakes have been committed, that the greater part of the determinations as yet arrived at require revision and correction. Hitherto the fossils have not been compared accurately enough with the recent vegetable world. It may be frankly said, that most phyto-paleontologists possess too little botanical knowledge; how can it be expected of a novice in botany, that he should classify fossil plants correctly, if he do not thoroughly know the living ones ? The most frequent difficulties arise in classifying the fossil leaves which form by far the greatest number of fossil plant remains. The leaf skeleton which offers the most important marks for their classifi- cation must first be studied with this object, for the systematic botanists have barely regarded this matter at all. I may indeed point out, as a very fortunate circumstance, that exactly at the time I was much occupied with this work, Nature Printing was invented in the State Printing Office, at Vienna (1852), an operation by which the leaves of living plants with all the details of their finest veins were printed off in the most accurate manner. I was permitted to publish a series of works on the leaf-skeleton together with illustrations in nature printing with the object of com- paring them with fossil plants. The marks on the leaf-skeleton were examined and arranged, and at present all the families of living plants which are of importance in relation to the fossil Flora have been already brought into scientific order according to their leaf-skeletons. III.—Object and Plan of the Investigation of Fossil Plants. Fossil plants are often examined only for paleontological or geological purposes, but in the opinion of the author it is also necessary to consider the interests of botany. We must in this always take our departure from the known to discover the un- known. We proceed, therefore, from the Flora of the present world, step by step, to the primeval, and thus have first to investigate the Cainozoic Flora. Only when these have been fully examined and their connexion with the living Flora completely ascertained, can the Mezozoic Flora be so worked out that the genetic connexion of the Cainozoic Flora with the latter will be determined. The final object of these labours will be the investigation of the Paleozoic Flora, 1878.] Phyto-Paleontological Investigations. 225 and through them the question of the origin of the vegetable kingdom will receive such an answer as is open to human inquiry. How is it possible to discover the genetic connexion of Floras following each other in immediate succession ? The successive Floras of different ages are not sharply distinguished from each other, but there are the most manifold transitions between them. These transitions are to be found in the common species. It is therefore desirable closely to examine, in the above-mentioned method, the species most frequently met with, and specially to select from the different varieties the progressive and retrogressive forms. By placing together these with other varieties discovered, in a vertical direction (that is, crossing the horizons lying over each other), the Phylogenetic series are obtained, and therewith also the required connecting links of the Floras. As examples of the Phylogenetic series, only those of the Castanea atavia and of the Pinus palco-strobus*), found by me, are at present known. Other Phylogenetic series which I have discovered will be published at a future time. IV.—Results relating generally to the Tertiary Flora. My method of procuring fossil plants, and the improved method of investigation on the one part, and on the other the direction of the inquiry which I adopted, have led me to results which are very little in harmony with those obtained by the old method. I can only describe most of the previously determined species as being some of them incorrect, and the others of no value, inasmuch as the knowledge respecting them has been derived from insufficient materials. I shall probably, however, not be in a position to adduce special proof of this, and so correctly to determine which the false species are. On account of much new work, I must be satisfied to refer to it generally, and leave it to future specialists to relieve science from the mistakes which have been made. I have found :— Firstly, that all the Floras of the earth stand in genetic connexion with the Tertiary Hlora. These contain the original species of the recent Flora and plant forms of all parts of the globe. The mixing together of forms of plants is clearly shown, especially in the Miocene Flora, as I at first pointed out in the Tertiary Flora of Austria. Secondly, that in each of the recent Floras are to be perceived the elements of their common original Flora. They have, however, been more or less changed, and appear frequently altered into manifold forms. I have given the name of “ Fiorenglieder”’ (members of a Flora) to these extensively-developed Flora elements. The character of a Flora * “ Beitrice zur Erforschung der Phylogenie der Pflanzenarten,” “ Denkschriften der Wiener Akademie der Wissenschaften,’ Band xxxviii. 226 Baron Ettingshausen. } [Dec. 19, has formed itself through the greater development of one element which has become the ‘“ Haupt-Florenglied”’ (principal member of a Flora) ; such as, for instance, has occurred in the Flora of Australia,* and of the Cape.t The rest of the genetic members have remained rudimentary. The Endemic species of Huropean, Asiatic, and Hast Indian genera are, in the above-mentioned Floras, the representatives of these ‘“ Nebenglieder ” (secondary members). Thirdly, that the species of fossil plants inclined much more to the formation of varieties than those of living plants, and that the varieties of the fossil species, for the most part, correspond with the species of existing Flora. I have proved this in the case the Pinus pulco-strobus, the varieties of which so entirely correspond with many of the recent Pinus species, that the former must be recognised as the original forms of the latter. At some future time, I hope to publish a demon- stration of the genetic connexion of the varieties of many other Tertiary plants with species of plants in the living world. V.—Results relating to the Hocene Flora of ‘Great Britain. The very extensive materials which I have had under examination were principally those of the collections of the British Museum and that of Mr. John 8. Gardner, and I have here to express to Mr. H. Woodward and Mr. Carruthers, as well as to Mr. Gardner, my most grateful thanks for their willing aid. I desire, also, especially to acknowledge my deep obligation to the Royal Society, from which I have received a grant for the investigation of the Hocene Flora of Great Britain. Mr. Gardner has gained for himself well deserved acknowledgments for the important services he has rendered in dis- covering and obtaining a vast collection of the Hocene Flora of Great Britain, and it has given me great satisfaction to have been associated with him in the study of this fossil Flora. As the geology of the localities of the Eocene Flora of Great Britain has been already published by Mr. Gardner, I proceed at once to those results which the investigation of this Flora have, up to the present time, produced. These results can only be partially indicated now, as the comparing of the fossil Flora of Great Britain with other Floras will not be published until the investigations are completed. Jor the present, the monographic work of the Filices is finished in manuscript. The Hocene Flora of Great Britain is distinguished by a series of tropical forms of ferns. Of these are especially to be named the pecuhar genera of Podoloma and Glossochlamys, which connect them- selves mostly with tropical forms of Polypodium; then the peculiar genus Menyphyllum most nearly related to the tropical Aspidiacee. * Ettingshausen, “ Die genetische Gliederung der Flora Australiens,” ‘‘ Denk- schriften der Wiener Akademie der Wissenschaften,” Band xxxvii. + Ettingshausen, “ Die genetische Gliederung der Cap-Flora,” “Sitzungsber. der Wiener Akademie der Wissenschaften,’ Band lxxi. 1878.| Phyto-Paleontological Investigations. “O27 In addition may be mentioned forms of Chrysodiwm and Lygodiwm. The appearance of the genus Gleichenia reminds us of the fern Flora of the Cretaceous period, while some species of Pteris and Phegopteris are related to species of the Miocene Flora. One fern, Asplenites alluso- roides Ung, as yet only known in the Fossil Flora of Sotzka, has also here found its predecessor. The species of the Hocene Flora of Great Britain are enumerated as follows :— Filices of the Hocene Flora of Great Britain. Names of Species. Localities. Formation. OrpD. PoLYPODIACER. a. Acrostichacee. Chrysodium Lanzeanum. Vis sp. Studland, Bourne- | Lower and Mid- mouth. dle Eocene. b. Polypodiee. Podoloma polypodioides. Ett. et Gard. . . affine. Ett. et Gard. 5 Glossochlamys transmutans. ét. et Gard... se a ° an Polypodium sp., neartoP. .. ‘ lepidotum. Willd. Bournemouth ...| Middle Eocene. c. Pteridee. Adiantum Carruthersii. Ett. et Gard.. Pteris eocenica. tt. et Gard.. us » Bournemouthiana. Hit.et Gard.. y a ms i » pseudo-penneformis. Lesq. Counter Hill --| Lower Eocene. d. Aspleniacee. Asplenites pre-allusoroides. Hét. et Gard... 36 ar ae se Bournemouth ..| Middle Eocene. e. Aspidiacee. Menyphyllum elegans. Ett. et Gard. Phegopteris pre-cuspidata. Hitt. et Gard .. oe we SC “YC Phegopteris Bunburi. Heer... ” 2 be) ” >) Bovey Tracey Bournemouth OrpD. G-LEICHENIACE®. Gleichenia hantonensis. Wanklyn sp..| Bournemouth OrD. SCHIZHACER. Lygodium Kaulfussi. Heer .. Orv. OSMUNDACER. Osmunda subcretacea. Saporta op mm lignitum. Geb. sp.. Bovey Tracey Bournemouth 228 Presents. [ Dec. 5, The Society then adjourned over the Christmas Recess to Thursday, January 9, 1879. Presents, December 5, 1878. Transactions. Bombay :—Royal Asiatic Society, Bombay Branch. Journal. Vol. XIII. No. 35. 8vo. 1878. The Society. Bordeaux :—Société de Médecine et de Chirurgie. Mémoires et Bulletins. 1877. fase. 1-4. 8vo. 1877. The Society. Briinn :—Naturforschender Verein. Verhandlungen. Band XV. Heft 1, 2. 8vo. 1877. The Society. Brussels :—Société Malacologique de Belgique. Annales. Tome IX. fasc. 2. Tome II (2° Série. Tome I). 8vo. Bruzelles 1876-78. The Society. Cincinnati :—Society of Natural History. Journal. Vol. I. No.1, 2. 8vo. 1878. The Society Davenport (lowa) :—Academy of Natural Sciences. Proceedings. Vol. I. Part 1. 8vo. 1877. The Academy. 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The following Papers were read :-— I. “ Researches on the Absorption of the Ultra-Violet Rays of the Spectrum by Organic Substances.” By W.N. HARTLEY, PF Inst. Chem., F.R.S.E., F.C.8., Demonstrator of Chemistry, King’s College, London, and A. K. Huntineton, F.Inst. Chem., A.R.Sc. Mines, F.C.8. Communicated by Professor G. G. StoksEs, Sec.R.S. Received October 10, 1878. (Abstract. ) Parts I and II. One of the authors of this paper, Mr. Hartley, having studied the researches of the late Dr. W. A. Miller ‘“‘ On the Photographic Trans- parency of Various Bodies,” &c. (“ Phil. Trans.,” 1863, I), and of Pro- fessor Stokes, “On the Long Spectrum of Electric Light” (‘‘ Phil. Trans.,”’ 1863, I), determined to study the action of organic substances on the ultra-violet spectrum. In 1872, the apparatus of Dr. Miller was reconstructed, and some experiments were made which showed that it was capable of some slight improvements. Some time was spent in testing the value of the photographic method of experiment- ing aS compared with that adopted by Professor Stokes, and pre- ference was eventually given to the former, or rather to a combina- tion of both methods, since occasional use was made of a focussing screen either of uranium glass or of white paper steeped in esculine solution and dried. It was soon apparent that a wide field of investigation was opened, and, with the assistance of Mr. Hunt- ington, a systematic course of examination of organic compounds was commenced at the beginning of the present year. In January, 1878, M. Soret published his ‘‘ Recherches sur l’Absorption des Rayons Ultra-Violet par diverses substances” (‘‘ Archives des Sciences Physiques et Naturelies, Genéve”’), which includes the ex- amination of many inorganic and some organic compounds. Though this is a work of very great interest, it does not touch upon the sub- ject of the present investigation, namely, the connexion between chemical constitution and diactinic quality. M. Soret uses a spectro- VOL. XXVIII. S 234 Messrs. W. N. Hartley and A. K. Huntington [Jan. 9, scope of his invention which receives the ultra-violet rays upon a fluorescent eye-piece, and so renders them visible. The Apparatus.—This consisted of a spectroscope attached to a pho- tographic camera, the prism and lenses being of quartz. The electric light consisted of sparks of great intensity passed between metallic — electrodes. To produce the sparks an induction coil, capable of giving a 7-inch spark in air, was excited by five cells of Groves’ battery. A Leyden jar was interposed between the coil and the electrodes, each surface of the foil measuring 72 square inches. The electrodes found to answer best were points of nickel wire, containing a trace of copper. Cells of glass, with quartz sides, were used for holding liquids under examination. These cells were placed behind the slit of the spectroscope, the spark passing in front; volatile liquids were thus prevented from taking fire, and a certain loss of light was avoided. | No condensing lens was used in front of the slit, because occasionally it was found convenient to employ an amalgam, containing zinc, cad- mium, aluminium, and magnesium, dissolved in mercury, in conjunc- tion with a point of iron, and under these circumstances volatilised mercury would condense on the lens. The Photographic Process—It was found by experiment that a wet collodion process, as used by Dr. Miller, was disadvantageous for several reasons, and therefore dry plates were used. A preference was given to gelatine pellicle plates, containing bromide of silver. They are quite sufficiently sensitive, give a very finely defined picture, and do not necessitate a varnishing process. The exposure has generally been about 10 seconds, but on certain occasions plates have been in the camera for an hour and a half. We have found no diffi- culty in obtaining a constant stream of sparks, giving a steady light for three-quarters of an hour without intermission. The Measurement of Absorption-Bands, &c. In order to measure the degree of absorption exercised by different substances the example of M. Soret has been followed, and the. lines of cadmium have been taken for the purpose. M. Mascart has measured the wave-length of these lines both for the visible and the ultra-violet rays. Sometimes measurements on the scale of wave- length have been adopted, but in other cases it has been found more convenient to make use of spectra as photographed. Photographs of different metallic spectra employed are presented. The lines of cad- mium are distinguished by the numbers assigned to them by M. Mas- cart. A comparison is also given of the relative extent of the visible and ultra-violet rays after passage through a prism. The prism was placed at the angle of minimum deviation for the sodiam line D. 1879.] on the Absorption of the Ultra- Violet Rays, 235. The various parts of the apparatus are screwed down so as to be immovable after a proper adjustment. The Hxamination of Organic Substances. Dr. Miller failed to trace any connexion between the chemical com- plexity of a substance and its actinic absorption. With the view of ascertaining whether any such connexion existed an examination was made of the normal alcohols, the normal fatty acids, and a series of ethereal salts. Great trouble was occasioned by the interference of minute traces of otherwise undetected impurities, the presence of which was often unaccountable. Four diagrams, show- ing the relative transparency of different substances, illustrate this part of the paper, and from the results obtained the following conclu- sions have been drawn. (1.) The normal alcohols of the series C,H»,,,OH are remarkable for transparency to the ultra-violet rays of the spectrum, pure methylic alcohol being as nearly so as water. (2.) The normal fatty acids exhibit a greater absorption of the more refrangible rays of the ultra-violet spectrum than the normal alcohols containing the same number of carbon-atoms, (8.) There is an increased absorption of the more refrangible rays corresponding to each increment of CH, in the molecule of the alcohols and acids. (4.) Like the alcohols and' acids, the ethereal salts derived from them are highly transparent: to the ultra-violet rays, and do not exhibit absorption-bands. In order to ascertain whether isomeric bodies exhibited similar or identical absorption spectra a series of benzene derivatives was examined. From the great absorptive power of this class of substances it was found necessary to use very dilute solutions even though the cells holding the liquids were not more than 0°75 inch in thickness. Curves were plotted by taking the proportions of sub- stances in solution as ordinates, and the position of absorption-bands as abscissee, and these curves are highly characteristic features of very many compounds. About twenty diagrams have thus been made. The following is a summary of the chief points of interest apper- taining to benzene and its derivatives. (1.) Benzene, and the hydrocarbons, the phenols, acids, and amines derived therefrom, are remarkable firstly, for their powerful absorp- tion of the ultra-violet rays; secondly, for the absorption-bands made visible by dissolving them in water or alcohol, and. diluting; and thirdly, for the extraordinary intensity of these absorption-bands, that is to say, their power of resisting dilution. (2.) Isomeric bodies, containing the benzene nucleus, exhibit widely 8 2 236 Mr. G. F. Fitzgerald. Electromagnetic Theory [Jan. 9, different spectra, inasmuch as their absorption-bands vary in position and in intensity. (3.) The photographie absorption. spectra can be employed as a means of identifying organic substances, and as a most delicate test of their purity. The curves obtained by co-ordinating the extent of dilution with the position of the rays of the spectrum absorbed by the solution form a strongly marked and often a highly characteristic feature of many organic compounds. There is a curious feature in connexion with the position of the absorption bands; at the less refrangible end they either begin at line 12 Cd or line 17 Cd, and those which begin at 12 end a little beyond Wie No naphthalene or anthracene derivatives have yet been examined, and very few substances of unknown -constitution—hence most iIn- teresting results may be anticipated from a continuation of this research, and this contribution must'be accepted rather as a bare com- mencement of the subject than its conelusion. If. “On the Electromagnetic Theory of the Reflection and Re- fraction of Light.” By Gkrorck FRANCIS FITZGERALD, M.A., Fellow of Trinity College, Dublin. Communicated by G. J. Stonny, M.A., F.R.S., Secretary of the Queen's University, Ireland. Received October 26, 1878. (Abstract. ) The media, at whose surfaces reflection and refraction are supposed to take place, are assumed to be non-conductors, and isotropic as regards magnetic inductive capacity. Some reasons are advanced why the results should apply at least approximately to conductors. In the first part of the paper the media are not assumed to be isotropic as regards electrostatic inductive capacity, so that the results are generally applicable to reflection and refraction at the surfaces of crystals. ZT use the expressions given by Professor J. Clerk Maxwell in his ‘‘ Electricity and Magnetism,” vol. ii, Part IV, chap. 11, for the electrostatic and electrokinetic energy of such media. By assuming three quantities, &, y, and ¢, such that, ¢ representing time, a <4 and “ are the components of the magnetic force at any point, I have thrown these expressions for the electrostatic and electrokinetic energy of a medium into the same forms as M‘Cullagh assumed to represent the potential and kinetic energy of the ether, in “ An Hssay towards a Dynamical Theory of Crystalline Reflection and Refraction,” pub- 1879. ] of the Reflection and Refraction of Light. 234 lished in vol. xxi of the “ Transactions of the Royal Irish Academy.” Following a slightly different line from his, I obtain, by a quaternion and accompanying Cartesian analysis, the same results as to wave propagation, reflection, and refraction, as those obtained by M‘Cullagh, and which he developed into the beautiful theorem of the polar plane. Of course, the resulting laws of wave propagation agree with those obtained by Professor Maxwell from the same equations by a somewhat different method: For isotropic media, the ordinary laws of reflection and refraction are obtained, and the well-known expressions for the amplitudes of the reflected and refracted rays. In the second part of the paper I consider the case of reflection at the surface of a magnetised medium, adopting the expressions Pro- fessor J. Clerk Maxwell has assumed in “ Electricity and Magnetism,” vol. ii, Part IV, § 824, to express the kinetic energy of such a medium. From this, following the same line as before, I have deduced the fol- lowing equations to represent the superficial conditions: In them, ©, 7, €, have the same meaning as before, and the axes are a in the intersections of the plane of incidence and the surface, y in the sur- — face, and z normal to it; a, 8, y, are the components of the eee of the vortex that Professor Maxwell assumes, and Cae 4 gid ae dh dex dy da? which, with these axes, reduces to af tye; K and K, are the elec- a@ trostatic inductive capacities of the two media in contact, and the quantities referring to one of these which is supposed to be non- magnetic are distinguished by the suffix ;; C isa constant, on which the power of the medium to rotate the plane of polarisation of light depends. dE, ag K, ee) —AnCK, An 4 ey J dz, da, Kidz dz es ce mie ~ as +55 As these are unchanged by a simultaneous alteration of the signs of 7 and C, I show that the method adopted in my former paper on Magnetic Reflection in the ‘ Proceedings of the Royal Society,” for 1876, No. 176, is justified, and that it is legitintate to consider an incident plane polarised ray as composed of two oppositely circularly polarised rays, each of which is reflected according to its own laws. From these I further deduce that, when the magnetisation of the medium is all in the direction of 7, there is no effect on reflection or refraction produced by it. I consider next the cases of the magneti- sation being all normal to the surface, and all in the surface and the plane of incidence, and obtain the following result: When the inci- dent ray is plane polarised, and the plane of polarisation is either in or .238 Prof. E. Frankland on Dry Fog. [Jan. 9, perpendicular to the plane of incidence, the effect of magnetisation is to introduce a component into the reflected ray perpendicular to the original plane of polarisation, whose amplitude, c, is given in the several cases by the following equations, in which 7 is the angle of incidence, and 7 of reflection, and /& a small constant depending prin- cipally on C, and the intensity of the incident ray:—1l. When the _ magnetisation is normal to the reflecting surface. If the incident ray be polarised in the plane of incidence— (1+ cos?) sin’z sin 27 ie. i eee sin’ (i+7r) .cos(i—r) If it be polarised in a plane perpendicular to the plane of incidence— cos*7 . sin?7 sin 27 sin7.sin’(i-+r) . cos(i—7) 2. When the magnetisation is parallel to the intersection of the sur- face and the plane of incidence, and the plane of polarisation of the incident ray is either in or perpendicular to the plane of incidence— 7, cosrsin’ésin22 ~ sin?(i+r) cos(i—r) This vanishes at the grazing and normal incidences, and, in the case of iron, attains a maximum at about the angle of incidence i= 63° 20’. I do not obtain any change of phase by reflection in any case; and this is to be expected, as this change of phase probably depends on the nature of the change from one medium to another, which, follow- ing M‘Cullagh, I have unifermly assumed to be abrupt. Apart from this question of change of phase, my results conform completely to Mr. Kerr’s beautiful experiments on the reflection of ight from the pole of a magnet, as published in the Philosophical Magazines for May, 1877, and March, 1878. If. “On Dry Fog.” By E. FRANKLAND, D.C.L., F.B.8., Pro- fessor of Chemistry in the Royal School of Mines. Received October 29, 1878. It has often been noticed, especially in and near large towns, that a foggy atmosphere is not always saturated with moisture: thus on the 17th of October last, at 3°30 p.m., during a thick fog in London, the degree of humidity was only 80 per cent. of saturation; and Mr. Glaisher, in his memorable balloon ascents, observed that in passing through cloud or fog the hygrometer sometimes showed the air to possess considerable dryness. In the ascent from Wolver- r379. | Prof. E. Frankland on Dry Fog. 239 hampton, on July 17, 1862, at an altitude of 9,882 feet, and when passing througha cloud so dense that the balloon could not be seen from the car, the dry bulb thermometer read 37°°8 F. and the wet 30°°2, indicating a dew point 17°-9 below the air temperature. Again, on the 30th July in the same year, when at an altitude of 6,466 feet, between the Crystal Palace and Gravesend, and whilst the balloon was passing through a “ great mist,’ the dew point was 12°:7 F. below the temperature of the air. The following is a tabulated state- ment of other instances in which there was comparative dryness of the air in the midst of cloud or fog :— ; Degree of Date. Place of ascent. pee STEELERS ugintiee 1n feet. of air. : 100 = saturation. 1862. . August 18th | Wolverhampton | 5,922 53°5 F. 61 1863. ,| March 31st| Crystal Palace 3,698 38'5 ,, 62 April 18th i , 9,000 32°5 ,, 52 Se 23 » %) 8,000 34°9 ,, 73 ” ” ” ” 7,000 378 ,, 87 ” ) ” yy) 6,000 41°0 ” 76 »» >» 09 %» 5,000 45'0 ,, 67 June 26th Wolverton 11,000 30°0 ,, 68 »» %9 %9 10,000 31°5 ,, 46 July 11th| Crystal Palace | 3,200 65:2 ,, 57 Rats % ‘ PIG OORAl an sere ion ae 53 i . i WG0On | ft yc 50 » » %» 1,000 G47; 53 1864. April 6th Woolwich 6,000 44-0 ,, 64 ” ” ” 1,000 41°7 ” 75 1865. Feb. 27th A 4,400 42°0 ,, 52 It is thus evident that the air closely surrounding the spherules of water in a mist, cloud or fog, 1s sometimes far from saturated with moisture ; although, as is well known to persons occupied with gas analysis, when a perfectly dry gas is admitted into a moist eudiometer it very rapidly assumes the volume indicating saturation, notwith- standing that the proportion of water surface to volume of gas is obviously far less than that afforded to the interstitial air of a fog. In a special experiment of this kind, it was found that air dried over calcic chloride became completely saturated with moisture in less than one minute and fifty seconds, when it was passed into a moist glass tube three-fourths of an inch in diameter. It appeared to me, therefore, interesting to inquire under what condition the evaporation from the surface of water can be so hindered as to cause this delay in the saturation of the closely surrounding air. Many years ago I became acquainted with the fact, first noticed I believe by Mr. P. 240 Prof. E. Frankland on Dry Fog. [Jan. 9, Spence of Manchester, that the evaporation of saline solutions, kept just below their boiling point in open pans, can be almost entirely prevented by covering the liquid with a thin stratum of coal-tar. It was thus that Mr. Spence effected a considerable saving of fuel in that | part of the process of manufacturing alum in which burnt aluminous shale is digested for many hours with hot dilute sulphuric acid; much less fuel being of course required when the digestion was carried on without evaporation, than when steam escaped from the surface of the hot liquid. This simple though important technical application suggested to me a condition of things under which the existence of so-called “dry fog ’’ would be possible. From our manu- factories and domestic fires, vast aggregate quantities of coal-tar and paraffin oil are daily distilled into the atmosphere, and condensing upon, or attaching themselves to, the watery spherules of fog or cloud, must of necessity coat these latter with an oily film, which would, in all probability, retard the evaporation of the water, and the consequent saturation of the interstitial air. The following experiments were made in order to test the validity of this explanation :— I. Two platinum dishes, containing water and presenting equal surfaces of liquid, were placed side by side in a moderate draught of air ; the water in one being coated by a very thin film of coal-tar. By com- paring the loss of weight in the two dishes, it was found that during twenty-four hours the evaporation was reduced by the film of coal- tar from 7°195 grms. to 1-124 grms. or 844 per cent. II. In a similar experiment, the evaporation during twenty-four hours was reduced from 7986 grms. to 1:709 grms., or 78°6 per cent. In order to imitate more nearly the modus operandi of actual smoke in foggy air, the smoke from burning coal was in the next experiments blown upon the surface of the water in one of the platinum dishes, ~ the dishes being placed as before in a draught niche. III. The evaporation during eighteen hours was reduced from 4:26 germs. to ‘969 grm., or 77°3 per cent. IV. In another experiment, the evaporation during twenty-four hours was diminished from 6°325 grms. to 1:173 grms., or 81°5 per cent., and during forty-two hours from 10°585 grms. to 2'142 grms., or 79°8 per cent. So far the experiments were made in a current of ordinary air of varying humidity; but they were afterwards repeated with the following results, under a large bell-jar, in which the enclosed air was continually dried by a large surface of concentrated sulphuric acid. As in the last two trials, the film was produced by coal smoke. V. During forty-eight hours, evaporation was diminished from 5178 grms. to 737 grm., or 85°8 per cent. 1879.] Prof. B. Stewart. Inequalities of Declination. 24] VI. During twenty-two hours, evaporation was reduced from 2°123 germs. to 668 grm., or 68°5 per cent. VII. During twenty-four hours, the reduction was from 2°460 erms. to ‘180 grm., or 92°7 per cent. VIII. Ina period of seventy-two hours, the reduction was from 7°638 grms. to ‘917 grm., or 88 per cent. IX. In seventy hours, the evaporation was diminished from 7°732 erms. to 2°586 grms., or 66°6 per cent. X. In forty-six hours, the diminution was from 4973 grms. to 1647 grms., or 66°9 per cent. Experiments were also made with single drops of water suspended in loops of fine platinum wire, and placed in the bell-jar filled with dry air; but it was found that the oily film had a strong tendency to leave the drop and run up the platinum wire. In a comparative experiment, in which one of the drops was protected by a coal-smoke film, the unprotected drop lost 90 per cent. of its weight in two and a half hours at 16°°6 C.; whilst the protected drop lost only 37°8 per cent. at 17°°8 C. in the same time. Another drop, protected by a film of coal-tar, lost 37°6 per cent. of its weight in two and a half hours, the temperature being 14° C. in the bell-jar. It is highly probable that if globules of water without any solid support (like those in cloud and fog) could have been operated upon, the retardation of evaporation would have been still more marked, or perhaps altogether arrested ; for in all the above experiments the oily films manifested a tendency to break up and attach themselves to the solid support of the water, leaving the surface of the latter partially unprotected. The results of these experiments point out a condition of very common occurrence, competent to produce “ dry fog,” whilst they also explain the frequency, persistency, and irritating character of those fogs which afflict our large towns; inasmuch as some of the products of destructive distillation of coal are very irritating to the respiratory organs, and a large proportion of them is scarcely if at all volatile at ordinary temperatures. My thanks are due to my pupil, Mr. C. G. Matthews, for his assist- ance in the foregoing quantitative determinations. IV. “ Note on the Inequalities of the Diurnal Range of the De- chnation Magnet as recorded at the Kew Observatory.” By BALFOUR STEWART, F’.R.S., Professor of Natural Philo- sophy in Owens College, Manchester, and Witt1am Dope- SON, Esq. Received November 18, 1878. We are at present engaged in searching for the natural inequalities 242 Sir J. Conroy on 3 [Jan. 9, of the above range, more especially for any of which the period is between 24 and 25 days. We find strong evidence of an inequality of considerable magnitude of which the period is 24-00 days, very nearly. We have also found preliminary evidence of the existence of two considerable inequalites of periods not very far from 24°65 and 24°80 days. These two appear to come together in about 11 years, but we cannot yet give the exact time of this. We have not found a trace of any inequality with a period of 24°25 days. V. “Some Experiments on Metallic Reflexion.” By Sir JOHN Conroy, Bart., M.A. -Communicated by Professor G. G. STOKES, Sec. B.S. Received November 18, 1878. In the experiments made by Sir David Brewster, M. Jamin, Pro- fessor Haughton, and others, on the light reflected by polished metallic surfaces, the reflecting surfaces were in contact with air; and, as far as I am aware, the only observations which have been made when the reflecting surfaces were in contact with other media are those by Quincke, an account of which is given in ‘‘ Poggendorff’s Annalen,” vol. exxvii, p. 541, and in the “Jubelband,” p. 336. He found that he obtained different values for the principal incidence and prin- cipal azimuth, according as the reflecting surface of a film of silver was in contact with air, crown glass, flint glass, water, or turpentine, and that the only connexion between the values of these angles and the refractive index of the medium in which the reflexion took place was, that in general with the same metal, the principal incidence and the principal azimuth became less as the refractive index of the medium increased. I therefore hope that a short account of some attempts that I have recently made to determine the principal incidence for, and the prin- cipal azimuth of, the light reflected by polished surfaces of gold and copper in contact with different media, may be of interest. The experiments are, I regret to say, incomplete, as, finding that my eyes were beginning to suffer, I thought it best, for the present at least, to discontinue them. I used a Babinet’s goniometer, to the arms of which two tubes con- taining nicols were attached, a vertical divided circle being fixed at one end of each, so that the position of the nicols could be read by a vernier to 5’. The goniometer had, in addition to the horizontal stage, a vertical one, so arranged that the reflecting surface could be placed in the axis of the instrument; toothed wheels, working into a pinion rotating on an axis fixed in one of the arms of the divided © circle, were attached to the vertical stage, the position of which could 1879.] | some Experiments on Metallic Reflexion. 243 be read by a vernier to 15”, and to the telescope arm; the ratio of the wheels to the pinion being such that, on moving the telescope arm, the vertical stage also moved in the same direction, but with half the angular velocity; so that when the reflecting surface had been pro- perly adjusted, the hght which passed along the axis of the tube fixed to the collimator arm, was reflected along the axis of that fixed to the telescope arm, at all angles of incidence. A quarter undulation plate was placed at the inner end of the tube fixed to the collimator arm, and a small direct vision spectroscope, with a photographic scale, could be attached to the other tube. The lower edge of the vertical stage being some distance above the gra- duated circle of the goniometer, a cylindrical vessel of thin glass, about 6 centims. in diameter, could be placed on the horizontal stage, so as to surround the lower part of the reflecting surface; this being filled with the liquid, and a narrow vertical slit placed so as to limit the incident light, fairly good observations cquld be made when the reflecting surface was in contact with various liquids. When the principal section of the first or polarizing nicol was in- clined at an angle of 45° to the plane of incidence, and one of the neutral axes of the quarter undulation plate placed in that plane, the transmitted light was elliptically polarized; and at a particular incidence, varying with its refrangibility, it was reflected by the metallic surface as plane polarized light; the plane of polarization being de- termined by the second nicol. Had the retarding plate really been ‘‘a quarter undulation plate” for light of any given wave-length, the angle of incidence at which it was reflected as plane polarized light, and the azimuth of its plane of polarization, would have been .the principal incidence and principal azimuth for light of that refrangibility. The retardation of a given plate varies so much for different por- tions of the spectrum, that even had it been possible to obtain one producing a retardation of exactly 90° for light of any definite re- frangibility, it would have differed greatly from a quarter plate for other portions of the spectrum. Both the neutral axes of the plate were successively placed in the plane of incidence, and the mean of the two values of the angle of incidence taken as the principal incidence. This arrangement is very similar to the one used by Dr. Hilhard Wiedemann in his observations on the light reflected by surfaces of fuchsine and copper, and described in “ Pogg. Ann.,” vol. cli, p. 6. In Dr. Wiedemann’s experiments the angle of incidence remained constant, the position of the quarter undulation plate and of the nicol being varied; whilst in mine, the position of the quarter undulation plate was constant, and the angle of incidence and the position of the nicol were altered. By this means the principal incidence and azimuth 244 Sir J. Conroy on [Jan. 9, were determined directly, but less accurately than by Dr. Wiede- mann’s arrangement, which, however, involves a good deal of cal- culation. The analysing portion of Dr. Wiedemann’s instrument appears to differ merely by the addition of a small direct vision spectroscope from the Elliptic Analyser of Professor Stokes, described in the ‘‘ Report of the British Association for 1851,” Part II, p. 14. The experiments were made with sun-light and with lamp-light ; with the former, the angle of incidence and the azimuth of the ana- lysing nicol were altered till the dark band in the spectrum was most intense at certain definite positions, as measured by the scale of the spectroscope; with the latter, till the light which had passed through a piece of red glass was reduced to a minimum. Numerous measurements were made of both these angles with a plate of gold in air, water, carbon bisulphide, and carbon tetrachloride ; and of copper, in air, water, and carbon tetrachloride; but the results were not very satisfactory. In addition to the difficulty of deter- mining accurately the zero of the nicols, and of placing the neutral axis of the quarter undulation plate in the plane of incidence, I found that very different values were obtained for the principal incidence, according as one or other of the neutral axes of the quarter undulation plate I was using was in the plane of incidence. In all cases, however, the principal incidence which, as is well known, is less for the more refrangible rays, diminishes, and the prin- cipal azimuth increases. with the increase of the refractive index of the medium in contact with the metallic surface; and further, the diminution in the value of-the principal incidence appears to be nearly in proportion to the increase of the refractive index of the surround- ing medium. The decrease of the principal incidence, with an increase in the refractive index of the surrounding medium, is exactly what might be expected to take place if the principal incidence for a metal were the same as the angle of polarization of a transparent substance; that is, the angle whose tangent is equal to the refractive index. If such is the case, the metals must all have very high refractive indices; but some experiments of Quincke’s (“‘ Pogg. Ann.,” vol. exix, p. 379, and vol. cxx, p. 602) appear to show that their refractive indices are less than 1. The following are some results I obtained with a gold plate (formed by soldering a slip of thin sheet gold to a brass plate), in air, with lamp-lght, a deep red glass being interposed; the position of the quarter undulation plate in which the ray polarized perpendicularly to the plane of incidence was retarded relatively to the other, being called A, and that in which the retarded ray was the one polarized in the plane of incidence, B. The signs of the azimuth of the plane of some Hxpermments on Metallic Reflexion. 245 1879.] polarization of the reflected light show which ray is retarded by the plate; and, to confirm this, the light transmitted by the nicol and plate was examined with an Iceland spar, cut to show the rings. The azimuths are reckoned as positive when measured from the plane of incidence in the direction in which the hands of a watch move, to a person supposed to be so placed as to receive the light, whether incident or reflected, into his eye. Quarter Undulation Plate at A. Plane of polarization Principal Principal of incident light. incidence. azimuth. 1s SOON Ty aie te. +36 05 SO oe a eo seo 36 35 SOMA esha s 3D 25 SOO sale hess 36 05 SOW ee stale oiela «4 SOA tae aes —36 50 GOW I sc oaias 34 55 SURO SMTA: Css eis lass 30 40 SO27 ene ee 39 25 Mean..... 510 bio Marek OR ae: 30 52 Quarter Undulation Plate at B. Plane of polarization Principal : Principal of incident light. incidence. azimuth. 4-415, een ilpgort out Snare —34 40 71 08 SooboC se 30 25 Ow livers ree... 34 25 Ths lO) eli AR i A 34 30 Al) ee CO iat cots oats +37 30 0) PR ane ae 36 55 GOO ET ae ens 36 35 MON AON) tatters > 37 55 JUICER RAI 70 45 85 57 Similar measurements were made when the gold plate was in water and carbon bisulphide. The values of the incidences differed greatly according as one or other of the neutral axes of the quarter undula- tion plate was in the plane of incidence, the measurements being about as concordant as those made with the gold plate in air; the means of these determinations were taken as nearest the truth. Since the retardation of the ray polarized perpendicularly to the 246 Sir J. Conroy on [Jan. 9, plane of incidence probably varies more for each degree when the light is incident at an angle greater than that of the principal inci- dence, than when it falls on the surface ata less angle, the mean of these two sets of determinations can only be considered as an approxi- mation to the truth, especially when, as in this instance, the difference between the two values is a considerable one. Mean value, from eight observations, four with the P. S. of the polarising nicol inclined to the right and four with it to the left of the plane of incidence, of the principal incidence and principal azi- muth, for red light, with Quarter Undulation Plate 1. , Gold in aqre i... ses) Res OB. 70 45... Sees ee. 80.13)... ge ssn Meanrvalue. 75 29.23. Soma Plateat A.. 76°46 ....)) 37am Gold in Waer sees . B... 66,46. 3. ease Mean: value. 71 46 .... 36 31 Plate at A.. 76 10 2.5.5 374s Gold in carbon bisulphide. 3. B62 44 eo -Meam: value. 69 27 ..2. 37944 The principal incidence and principal azimuth for gold in air, with red light, were determined with six other quarter undulation plates with the following results; the numbers for Plate 1 being the mean of eight observations, whilst those of the remainder-are the mean of two only, made with the polarizing nicol on either side of the plane of incidence :— Plate 1. Plate 2. Plate 3. Plate 4. cina} {Plate ab A. .. 8013 78 45. 80 Ol) aioe eye . B70 45. 70 12 69 Ai eons eas Mean value.. 75 29 74.28 7A) 5 =euagmem fi ab A... 30 52 36 30 36 12 36 22 Principal azimuth eS By eisdy od 35 40 36 02 35 10 Mean value... 35 54 36 05 36 O7 35 46 Plate 5. Plate 6. Plate 7. Principal incidence me Big 69:56 73 26 73 BS Mean value... 74 56 75 84 75 86 {cm aby Als wen mio oy 0 34 55 84 52 we at A... 7957. 77 430 0 ae Principal azimuth Hi Be teow 35 10 34 42 Mean‘ value... 330) 410 3on02 34 47 =~] 1879. | some Experiments on Metallic Reflexion. 24 In order to ascertain the probable error of the mean principal incidence and azimuth as determined with Plate 1, the measure- ments were repeated with Plate 6; the difference between the two values of the principal incidence, according as one or other of the neutral axes of the plate was in the plane of incidence, being least, and therefore the retardation for red light differing least from 90° for Plates 6 and 7. Quarter Undulation Plate at A. Plane of polarization Principal Principal of incident light. incidence. azimuth. 1 RY Cee) ee +35 0 77 58 Reese 30 35 CARE DA mde Cae ee 39 O05 ot OP pay rae ss 30 40 == 415) 1) ear Eo Ae ee Na is —36 45 GH CA BWR 3c g's, 60 30 30 Ui Msvdcckos, 5 36 15 3S) eerie 36 0 Nica. spss: sieve UOMO SVM) Weed oleate 35 43 Quarter Undulation Plate at B. Ab i A Se ya neta: —34 40 UEMUT Oe Vs wee ep 36 10 SON ts aie sto 39 40 ES OOM ag to sere 309 20 ==4:5) eee TAU! ae ce 6 +35 20 73 0d spe stages 36 05 TESTES aa Oh eae 34 35 GAOT EPR Meera es 35 0 learn tee eae he 73 45 30) 2 Similar measurements, which were about as concordant, were made with the gold plate in water and carbon bisulphide. The numbers in the table being the means of eight observations, four with the prin- cipal section of the polarizing nicol inclined to the right, and four with it to the left of the plane of incidence. Plate at A.. 7803 .... 385 48 Gold in air..... { i, Bese 7345 By AL Mieaniwaluem Uopo4e 2.) 35032 248 Sir J. Conroy on : [Jan. 9, i Seen Ue BO AO Mean value. W260") o. aeeeoeOme el Plate As. 74 460.722 i Semt Goldvin waters... ose : Plate atAn. o7L 387) ode CRS Gold in carbon bisulphide 1 = | Bas 68 +20.) ura Omeles Mean value. 70 Ol” 23a 3Grol The mean values of the principal incidence and principal azimuth obtained with the two quarter undulation plates being different, it was assumed that the errors of the means are as the squares of the small errors of the plates, and that the errors of the incidences in either position of the plate, and therefore the algebraical differences or numerical sums of the errors in the two positions, that is, the differences of the apparent principal incidence in the two positions, as the first powers; and therefore that the errors of the means are as the squares of the difference of incidences in the two positions. Gold in Air. Plate 1. Plate 6. Correction. Principal incidence........ 75 99 .. 75 54) See . azimuth; ,32s... Bo O4 7... “So oc mee Difference of principal inci- , , an ae; ; dence in two positions... 9 28 or 568, 4 18 or 258. Thus the residual corrections to the results got with Plate 6 will be to the difference on the results got by Plate 1 and Plate 6, as 258? to 568°—258?, or as No. log 1:41491 to 1; this gives +6’ and —5’ making the corrected principal incidence and principal azimuth 76° PINGh Bye Pare In a similar manner the means of the results got with the gold plate in water and carbon bisulphide were corrected, the final results being with red light. Principal incidence. — Principal azimuth. Goldin aurea Ae ae 8 76.0 .-- ie ome rs Wi beIeus Sineuarie nis wee 72, 46 Sh 36 23 ‘; carbon bisulphide.... 70 03 Beg 36 48 In order to determine the principal incidence and azimuth for gold by an independent method, the one originally used by Sir David Brewster was adopted; the quarter undulation plate was removed, and a second gold plate attached to the vertical stage in such a manner that, whilst the plates remained parallel to each other, the distance between them could be altered. The plates were so adjusted that 1879. | some Experiments on Metallic Reflexion. 249 when the light was incident upon the surface of the first at angle of about 70°, it was reflected once by either plate. The incident light being polarized in a plane inclined at an angle of 45° to the plane of incidence, the position of the stage and of the analysing nicol were altered till the reflected light was reduced to a minimum. Plane of polarization Principal of incident light. incidence. Azimuth. ih ee TL se Rae LEN 0 HOMOON ap aihas easier x 3 31 30 7) 23 Re eae 31 05 TORO mpegs eee tee: 31 55 = 4" Se Lop OAC aie 3 hee +29 30 (ORONO Tigers 29 50 GOO TL, em RG awh eS 29 05 CORVSIO Rana ad oe? 28 45 LUGS ae eee eas a asd ator, (teats, 30 15 A rectangular glass trough was placed on the horizontal stage of the goniometer so as to surround the gold plates; the trough filled with water, and the principal incidence and the azimuth observed. The ray of light which had been twice reflected by the plates being parallel to the incident ray, and the trough having been placed with its front perpendicular to the direction of the incident light, the polariza- tion of the ray could not be altered in any way by the glass, as indeed was verified by experiment. The light having been twice reflected, the square root of the tangent of the angle which the plane of polarization of the reflected ray makes with the plane of incidence, is equal to the tangent of the principal azimuth. The principal incidence and principal azimuth determined by this method from eight observations, four with the plane of polarization of the incident light on either side of the plane of incidence are— 75 52 37 29, Pe WALL s 3.2 72 28 Rae 37 48 The principal incidences agree fairly well with those obtained by the other method ; but the azimuths are somewhat higher. The following table contains the values of these constants for gold in air, as previously determined by— VOL. XXVIII. r 250 On some Experimants on Metallic Reflexion. [Jan. 16, Sir David Brewster. ( Optics,” ed. 1853, p. 309,811)... 70 45, .. 33 0) foetaeeen Professor Haughton. lers’ gold. (Phil. Trans,” 18635 psilye eee 2G oe ean AiG G. Quincke. (“Pogg. Jubelband,” p. 336) ..... 72 47... 43. 12 fors@ ina Assuming that the tangent of the angle of principal incidence is the index of refraction of the metal for red light, the value of that angie in air, as deduced from the measurements made in water and carbon bisulphide with the quarter undulation plates, is 76°53 and 77°22 instead of 76°. The numbers given by Quincke (“‘ Poge. Ann.,” vol. cxxvii, p. 541) for silver are-— Principal incidence. Principal azimuth. Enpoitit emia rae 74. 19 43 48 ny Wyraber’ sreeyenet vara: 71 28 Eee 44 O3 In turpentine ...... 69-6 43 21 The value for the principal incidence in air calculated according to the same assumption, by multiplying the tangent of the principal incidences in water and turpentine by the refractive indices of these substances, is 75° 55’ and 75° 36’ instead of 74° 19’; in all four cases the value is too high. Although more experiments are required to decide this point, it seems probable that this relationship between these numbers is not merely an accidental one; and if so that there is additional reason for adhering to Sir David Brewster’s opinion that the value of the angle of principal incidence may be taken as indicating the refractive power of a metal. In conclusion, I must express my thanks to Professor Stokes for | much advice and assistance, and specially for pointing out the method for determining the residual corrections to the results obtained with the quarter undulation plates. January 16, 1879. W. SPOTTISWOODE, M.A., D.C.L., President, in the Chair. The Presents received were laid on the table, and thanks ordered for them. The following Papers were read :— 1879.] Dr. G. Thin. Anatomy of the Skin. 251 I. “On some Points connected with the Anatomy of the Skin.” By Grorce Tain, M.D. Communicated by Professor Hux ey, Sec. R.S. Received November 20, 1878. [PuATEs 2 and 3.]| Rollett, in 1858,* in a memoir on connective tissue, described the results of an elaborate investigation into the structure of the corium. Microscopic examination of leather, and of skin tanned by himself, had shown him that the connective tissue bundles of the corium are ‘made up of smaller divisions, and that these latter are again made up of the previously known minute connective tissue fibrille, which are so small that their diameter can only be approximately estimated at 0:0002 to 0°0003 millim. From the connective tissue bundles of the skin of the ox, “‘ treated by lime or baryta water, there can,” he states, “be isolated from each bundle a number of component elements which have a considerably larger diameter than the minute fibres known as connective tissue fibrille.” These elements have, he remarks, in the ox a thickness of 0°003—0:006 millim., and he proposes to call them connective tissue fibres (Bindegewebsfaser). In a plate attached to his memoir the bundles and their divisions are shown in a very dis- tinct manner. This observation of Rollett’s has not arrested the attention of anatomists to the degree which might have been expected, and seems, indeed, to have been to a great extent neglected. ‘Two of the latest standard works may be quoted in illustration of this remark. W. Krause, in a volume on “General and Microscopic Anatomy,” pub- lished in 1876, describes the tissue of the corium proper as being com- posed of “‘a network of strong bundles of connective tissue closely interwoven, the bundles being partly cylindrical, partly flattened.”’ There is nothing said about the subdivision of the bundles, as described by Rollett. The same author, in his chapter on connective tissue, states, “‘ that the ground substance of fibrous tissue consists of closely-packed, very fine, round connective tissue fibrille, measuring 0:0002—0:002 millim.” The larger of these measurements is inapplicable to the fibrilla of Rollett, and is so near that of the subdivision or ‘ fibre” of that author, that it is evident that Krause does not recognise the distine- tion between the fibre and the fibrilla established by the former his- tologist. - In Quain’s “‘ Anatomy ”’+ it is stated, “that the corium is made up of an exceedinely strong and tough framework of interlaced connec- tive tissue fibres with blood-vessels and lymphatics. The fibres are * “ Sitzungsbericht der Kaiserlichen Akadamie der Wissenschaften,” vol. xxx. + Highth edition, edited by Dr. Sharpey, Dr. A. Thomson, and Mr. Schafer ; p. 213, vol. 1. 7 2 252 Dr. G. Thin. Anatomy of the Skin. [Jan. 16, chiefly of the white variety, such as constitute the chief part of the fibrous and areolar tissues, and are arranged in stout interlacing bundles, except at and near the surface, where the texture of the corium becomes very fine.” Neither in the above quotation, nor in the sections of the same volume in which areolar tissue and fibrous tissue are described, can I find anything analogous to Rollett’s de- scription of definite subdivisions of the bundles as distinct from the fibrillee. In a paper presented to the Royal Society in 1875, I stated that in portions of the cutis, macerated for a few days in aqueous humour or blood serum, the tissue is seen to be composed of extremely fine but sharply contoured fibrille, arranged in parallel bands, whose breadth approaches the diameter of a human red blood-corpuscle. These bands are the subdivisions (Abtheilungen) of the bundles described by Rollett, with whose memoir I was not then acquainted. During the interval that has elapsed since I wrote the paper referred to, I have been frequently engaged in examining skin affected by various pathological changes, and I have had occasion to observe that the structure of the “‘ bundle’ of anatomists, as understood by Rollett, 1s sometimes seen very clearly in disease. Its recognition is, as I have elsewhere* pointed out, necessary to a right appreciation of some of the appearances seen in cancer of the skin. It is partly the object of this paper to describe some methods by which this structure of the bundles can be demonstrated, and also to describe some other points in the anatomy of the skin which I have observed whilst studying the tissue by means of these methods. The nomenclature I shall use is the following: By the term bundle or secondary bundle, I designate the ordinary bundle of authors, which is more or less conspicuous in all preparations of skin, and which is analogous in structure and size to the bundles as usually described and figured in tendon-tissue. The element described by Rollett as ‘‘ connective tissue fibre,” I shall describe as primary bundle, to distinguish it more markedly from the fibrille which compose it. When groups of secondary bundles are isolated, each group being composed of several secondary bundles, | term the group a tertiary bundle. These elements can be isolated by first saturating the corium with chloride of gold solution and then macerating the tissue in acids. Portions of skin, with a thick layer of the panniculus adiposus, were taken fresh from the mamma of a middle-aged woman, which had heen removed for a tumour of the gland—the portions of skin chosen being well clear of diseased tissues. The stretched skin was pinned down to a cork beard, the under surface uppermost, and then saturated * “ Trans. Roy. Med. Chir. Soc.,” vol. lix, p. 189. 1879. ] Dr. G. Thin. Anatomy of the Skin. FB) with half.per cent. chloride of gold solution. From time to time different thicknesses of the fatty layer were removed as the solution had had time to penetrate into the tissue, until finally the deeper layer of the cutis proper was laid bare. The tissue, still extended, was then placed in fresh gold solution for several hours. The object of the manoeuvre was to secure the. penetration of the fluid through the bundles, whilst these were still extended in their natural condition. After a due action of the gold, the skin was cut into small pieces, which were then treated by acetic and formic acids in various degrees of dilution. Some of the portions were exposed to sunlight for several days, in water feebly acidulated with acetic acid, and then the strength of the acetic acid was raised to 20 per cent. of the ordinary concentrated acetic acid of commerce. Other portions were treated by formic acid. Some successful preparations were obtained from portions macerated first for afew days in a mixture of one part formic acid, of specific gravity 1:02U, and one of water, and then in the undiluted acid for some days longer, but a strict adherence to these strengths was not found necessary. Portions of the corium thus prepared were teased out in glycerine and examined, directly or after staining by different dyes. Staining by pikric acid I found very advantageous. I was able to isolate, in a condition favourable for study, the primary, secondary, and tertiary bundles. Generally speaking, although not invariably, the tertiary and secondary bundles were best seen in the tissues macerated in acetic acid, and the secondary and primary bundles in those treated by formic acid. _ Numerous elastic fibres were isolated by both methods, the finest fibres more particularly in the formic acid preparations. These fibres were frequently found only partially detached from the bundles, and in such preparations the relations of the fibres to the bundles could be well studied. The primary bundles isolated by these methods were flattened, cylindrical elements, even contoured, homogeneous in appear- ance, and uniform in breadth over the whole length isolated. The difference in breadth between individual bundles was very slight. By measurement, I found that they were from 0:004 to 0:005 millim. broad. The primary bundles were sometimes seen in situ, that is to say, as parts of a secondary bundle, the breadth of the latter being normal. In other preparations the contours of secondary and tertiary bundles were lost, and the microscopic field was filled with a large number of primary bundles, entangled and twisted by the needles used in teasing them out. Sometimes a number of primary bundles, although separated from each other, were yet so placed that I could feel assured that they were the constituent elements of one secondary bundle. Such was the case with the primary bundles shown in fig. 4. 254 Dr. G. Thin. Anatomy of the Skin. [Jan. 16, Various methods have been recommended by histologists for the demonstration of the ultimate fibrille of fibrous tissue, chiefly with reference to those of tendon bundles. If I may judge by my own preparations of skin and by the figures published in histological works, the fibrillee of the cutis bundles are very seldom seen. The appearances usually observed in skin hardened by chromic acid and alcohol are unfitted for a study of the fibrilla. In such specimens the bundles are more or less broken up, but the individual fibrillee are not, as a rule, isolated. I found that they were well shown by the following method:—A portion of fresh skin, with the panniculus adiposus attached, was pinned to a piece of cork, in the manner already described, and treated in the same way, with the exception that this time glycerine, instead “of chloride of gold solution, was used for saturation. When the saturated cutis tissue had been laid bare, the whole was placed in elycerine and allowed to remain in it for several days. Small portions were then teased out in glycerine, stained by picro-carminate of ammonia and examined in glycerine. In such preparations the secondary bundles were found isolated, the contours of the primary bundles not being preserved. In the secondary bundles the fibrille were seen more or less distinctly, in some of them with perfect distinct- ress. (See fig. 8.) In the gold preparations the following facts regarding the disposi- tion of the elastic fibres were noted :— If a portion of skin is hardened in bichromate of potash, and the sections moderately stained by eosin, all the large elastic fibres are stained much more intensely than the bundles, and it is then observed that they le on the surface of the bundles, and run parallel to them. In the gold preparations, after maceration in formic acid, further details regarding the fibres can be detected. It is then seen that there is a close network of minute elastic fibres, of which I have observed no traces in eosin-stained bichromate preparations, on the surface of the bundles, and that at certain points the larger fibres give off branches which join this network. At these points the network is so deuse over a small defined space that the size of the meshes is nearly equalled by that of the fibres. Rollett, in the memoir referred to, states that the bundles are embraced by elastic fibres, and that the latter send branches into the substance of the bundles. Iam able to confirm this statement, and to extend it. In some of the gold and formic acid preparations, I have observed that the elastic fibres which penetrate the bundles enter between the primary bundles, and that the primary bundles are embraced by the fibres which entwine them very closely. I have — never observed an elastic fibre penetrate a primary bundle. ‘The relation of the elastic fibres to the primary bundles is shown in 1879. | Dr. G. Thin. Anatomy of the Skin. 255 fig. 7, but the fibres are in reality more delicate than is shown in the drawing. | The dark very finely granular deposit produced by the reduction of the gold chloride had a special relation to the elastic fibres, which was best observed in portions of skin which had been macerated for a longer period in 20 per cent. acetic acid. This relation will be under- stood by reference to figs. 3, 6, 9, and 10. Strictly defined narrow strips of this deposit were found investing the fibres, and this so closely that it was only at pomts where it had been disturbed in the preparation that the fibre itself could be observed. The appearances reproduced in figs. 3 and 10, in which fibres are seen with deposit still adherent, illustrate this point very strikingly. In gold preparations large flat oval nuclei are sometimes seen adherent to the surface of the bundle. The nuclei have the charac- teristic slate colour, and around the nucleus a small ill-defined patch of gold deposit is seen. This deposit could sometimes be seen to be continuous with that surrounding an elastic fibre. This is shown in fig. 10. There is no reason to believe that in such cases more of the cell than the nucleus has been preserved, or that the gold deposit has any special relation to cellular substance.* The distinctly localised character of the deposit around the elastic fibres supports the idea that the larger ones are surrounded by an albuminous fluid, of a like nature to that shown by gold preparations, to be present between the laminz of the cornea. Isolated tertiary bundles completely surrounded by elastic fibres (fig. 5), are sometimes seen. The “ spiral”’ fibre, as I have seen it on the Based: of the skin, is an elastic fibre that encircles the bundles like a rmg; and it may con- tinue to do so after the ring has been detached from other fibres, none of which, indeed, may be found in the isolated bundle. The nature of the spiral fibre is still considered by some histologists as undecided, and Ranvier regards its behaviour under picro-carminate staining as against the view that it is an elastic fibre. In the prepara- tion drawn in fig. 8, which had been stained by picro-carminate, a typical spiral fibre was distinctly stained yellow by the pikric acid, and was not stained by the carmine, behaving in this respect exactly like any other elastic fibre. Confirmation of Rollett’s views as to the structure of the bundles is occasionally found in bichromate of potash preparations of skin. Part of one of the most demonstrative preparations of this kind * In a paper read before the Royal Society in 1874 (‘ Proceedings,” No. 155, 1874), I followed the view held by some histologists, that the gold deposit in such preparations is indicative of cellular protoplasm, and described and figured (fig. 13) an anastomosis of cells in the skin by means of elastic fibres. As will be observed from the remarks in the text, I now interpret these appearances quite differently. 256 Dr. G. Thin. Anatomy of the Skin. [Jan. 16, which I have met with, has furnished the subject of the drawings in figs. 1 and 2. The specimen is from the skin of the horse, and was thus prepared. A portion of fresh skin, free of panniculus adiposus, was hardened first in weak and then in stronger solutions of the bichromate, and treated by gum and alcohol before being cut. The deep edge of the sections—the part of the tissue that had been in direct contact with the bichromate solution—showed the structure of the bundles best. The transverse sections of many of the bundles were cut up into a mosaic of somewhat rounded polygonal fields (fig. 1b and fig. 2), the measurements across each field varying from 0:0037 to 0:005 millim. Oblique and longitudinal sections of the bundles showed that these fields were sections of primary bundles. The mosaic was not equally distinct in all the bundles, even in parts where the appearance was well brought out. This varying distinctness is seen in fig. 1. The sections of the primary bundles being rounded there are small angular spaces between them. These have not been successfully shown in the drawing. | In this preparation a delicate connective tissue was found between the bundles of the corium ina well marked form. Its extent relatively to the bundles will be best understood by reference to the drawing. As seen in the preparation it was distinctly fibrillar at parts. The cells seen in the preparation were in two positions. Some of them were found in the delicate tissue between the bundles; other cells were found in direct connexion with the bundles. Of the latter cells the greater number seen were applied to the surface of the bundles, but others were found in the substance of the bundles between the primary bundles. These cells were all of the endothelial type. In all of them the cell-contour was clearly marked, and in none of those observed was there a trace of a process, or of ridges and depressions similar to those described by some histologists in tendon. The size and form of these cells is accurately shown in fig. 1, and will be better appreciated by reference to the drawing than by any detailed description which I could give. EXPLANATION OF THE PLATES. (All the figures except figs. 8 and 10 are drawn by camera lucida.) Figure 1. From the corium of the horse, bichromate of potash, gum, and alcohol. Logwood and eosin staining. (a.) Delicate connective tissue between the bundles. (b.) Secondary bundle cut transversely, showing mosaic formed by the sec- tions of primary bundles. (c.) Cells belonging to the inter-fascicular connective tissue. (d, f.) Cells lodged in spaces in the centre of bundles. (e.) Cell applied to the surface of a bundle. x 375. #579. Dr. G. Thin. On Hyaline Cartilage. 251 Figure 2. Part of a bundle hanging loosely on the free under edge of the same sec- tion from which fig. 1 is drawn. The mosaic of primary bundles is un- usually well marked. x 375. Figure 3. Elastic fibre, with patches of chloride of gold deposit adherent. Isolated from adult human skin. Gold saturation and maceration in 20 per cent. acetic acid. x 340. Figure 4. Isolated primary bundles. Human adult skin. Gold saturation and maceration in formic acid. x 340. Figure 5. Tertiary bundle entwined by elastic fibres. Human adult skin. Gold saturation ; maceration in acetic acid. x 340. Figure 6. Gold deposit on a large elastic fibre, and a small elastic fibre on the sur- face of a bundle almost completely ensheathed in gold deposit. Human adult skin. Gold saturation ; maceration in acetic acid. x 340. Figure 7. An isolated secondary bundle, in which the contours of the primary bundles are visible. The latter are entwined by minute elastic fibres. Human adult skin. Gold saturation: maceration in formic acid. x 340. Figure 8. Bundle showing fibrille, and snared by an elastic fibre (spiral fibre). Human adult skin. Saturation with glycerine ; picro-carminate staining. (Hartnack, Objective No. 8; Eye-piece No. 3; Tube in.) ’ Figure 9. Lines of gold deposit on bundles, following the course of elastic fibres. Human adult skin. Gold saturation: maceration in acetic acid. x 340. Figure 10. Elastic fibre with a nucleus adhering to it, and a streak of gold deposit partially detached from the fibre. (Hartnack, Objective No. 8; Hye- piece No. 3.) II. “On Hyaline Cartilage and deceptive appearances produced by Reagents, as observed in the examination of a Cartila- ginous ‘Tumour of the Lower Jaw.” By GrorcEe THI, M.D. Communicated by Professor Huxury, Sec. R.S. Received November 25, 1878. [PuatE 3.] The following paper is written with a twofold object: firstly, as a contribution to the histology of hyaline cartilage; seccndly, to illus- trate how much the apparent structure of a tissue which is being examined microscopically depends on methods of preparation. A portion of a large tumour of the lower jaw, believed from its naked eye appearances by two experienced surgeons to be sarcomatous in its nature, was given me for examination. Although I was struck by the peculiar kind of resistance it offered to the knife, J did not imagine at the time, any more than did the surgeons who excised it, that the tumour was cartilaginous. This is to be explained by the fact that the cartilaginous substance which had been growing with extreme rapidity was of a low type. In order to determine the structure of the gr owth, I hardened por- 258 Dr. G. Thin. On Hyaline Cartilage. [Jan. 16, tions of itin different solutions, and then made sections which I stained with various colouring agents. The sections thus prepared differed from each other in a remarkable manner. Sections from a portion which had been placed for two days in solution of bichromate of potash were stained by logwood, picro- carminate of ammonia, and eosin respectively. In all of them the ground substance of the tumour appeared as structureless, and through- out it were interspersed a large number of rounded nuclei. In the carmine-stained preparations many of the nuclei were immediately surrounded by this homogeneous substance, without any appearances of what might have been considered as cell-substance or as cell-pro- cesses being observed. In some instances a scant, faintly granular stained substance tapered for a very short distance from opposite poles of the nucleus, producing the appearance of a spindle or fusiform cell. More rarely a long slender stained projection tapered gradually from one of the poles of the nucleus to a considerable distance, and seemed to end in a fine colourless fibre. The appearances were such as have been often described as indicative of cells with branching protoplasmic processes. For example, some of these apparent cells resembled accu- rately the smaller of the coloured figures described by Ranvier in the omentum as ‘‘ vaso-formative cells.” The sections stained in eosin solution showed somewhat the same appearances, although in a more exaggerated form. A homogeneous unstained ground substance was permeated by process-like prolonga- tions of a finely granular stained substance which surrounded the nuclei, the prolongations from adjoining cellular centres anastomosing. The distribution of these cell-like masses of stained matter was an exact copy of the appearances seen in a cornea stained by gold chlo- ride when what has been called the “ positive image” is successfully produced, and would certainly quite recently, if not now, have been described by some histologists as a highly developed protoplasmic network of branching cells (fig. 14). In the logwood sections the nuclei alone were stained, but stretching in various directions from the nucleus strong tapering colourless fibres appeared to be given off. A system of branched cells, in which the protoplasm was very scant, and the processes highly developed, was exactly simulated. This appearance was the more deceptive, as when the tissue was broken up with needles, numbers of these apparently branched cells with broken processes were found free in the finid (fig. 13). Slices of the tumour had been placed fresh in solution of purpurine (Ranvier’s formula), and had been allowed to remain in it for several days. The surfaces of the slices were well stained, but the colouring action of the dye had not penetrated deeply. Thin sections were made from the stained surfaces and examined in glycerine. The 1879. ] Dr. G. Thin. On Hyaline Cartilage. _ “59 nature of the tumour was at once apparent. Instead of the homo- geneous ground substance seen in the other preparations, a typical hyaline cartilage, with a large proportion of so-called cartilage cells, was brought into view. The nuclei were well stained, but the carti- lage substance proper was only very faintly coloured. In every part of all the purpurine sections the cartilage structure was perfect Got). The purpurine solution contains one-third per cent. alum, and one- fourth its bulk of methylated alcohol; and it is to this composition probably more than to the staining that the preservation of the un- stable cartilage substance was due. Portions of the tumour which had been placed in half per cent. solution of osmic acid were teased out, stained in logwood and ex- amined in glycerine. Indications of the cartilaginous structure could be detected, but the preparations were chiefly valuable as demonstrating the nature of the cells. The cell-substance was stained a darkish brown colour, the nucleus was well stained by logwood, and the ground substance was very feebly stained. The outlines of the cells could thus be observed i situ, as well as studied in isolated cells, many of the latter floating free in the fluid. All the cells observed were flattened, rounded, or somewhat poly- gonal bodies, with round nuclei (fig. 12). Their contours did not correspond exactly with those of the rounded cartilage “capsules ” in which they lay. In order to study the structure of these so-called ‘‘ capsules,” por- tions of the purpurine preparations were broken up. Considerable fragments with even surfaces were thus obtained, with rounded nuclei on the surfaces. In some of these there was no trace of the capsule formation. In other fragments a long piece of cartilaginous ground substance gave off laterally small curved projections, the size of the projection and degree of the curvature showing that they formed parts of a capsule. ‘But in no instance was an entire capsule isolated. On the other hand, a curved projection could sometimes be traced round one side of a capsule, encircling nearly one-half of it, and then passing onwards to form the bent wall of another capsule. I never observed these projections doubling back round the capsule (fig. 15). The examination of this tumour has thus shown that most delusive appearances as regards the nature of cartilage cells may be sometimes produced by staining and hardening agents. Carmine and eosin by staining an unformed substance that exists in the structure in de- fined tracts, may simulate branched protoplasmic cells, and bichro- mate and logwood preparations, either in sections or teased out, ray as closely simulate cells with fibre processes. These facts justify serious doubts as to the correctness of interpre- tation in all cases in which histologists have described branched cells 260; Dr. F. W. Pavy on | [Jan. 16, in hyaline cartilage, whether the latter existed as a normal structure, or as a pathological growth. They further show that, taken alone, carmine or eosin staining should not be held as conclusive evidence of the existence or limits of cellular protoplasm in any animal tissue. EXPLANATION OF THE PLATE. (Ail the figures are drawn by camera lucida; magnifying power x 260.) HYALINE CARTILAGE. Figure 11. The normal structure of hyaline cartilage. Purpurine. Figure 12. Isolated cells. Osmie acid. Figure 13. Isolated nuclei adherent to portions of cartilage substance, simulating branched cells with fibre-processes. Bichromate of potash; logwood. Figure 14. Stained substance in the cartilage simulating branched cellular proto- plasm. Bichromate of potash ; eosin. Figure 15. Fragments of cartilage substance separated by needles. Purpurine. Ill. “ Volumetric Estimation of Sugar by an Ammoniated Cupric Test giving Reduction without Precipitation.” By F. W. Pavy, M.D., F.R.S. Received December 5, 1878. To be able to effect the quantitative determination of a body with accuracy and facility is an important matter looked at in relation to the study of its bearings. In the case of sugar there are no reliable means of precipitating and weighing it, either alone or in combina- tion, and thus in the chemical estimation of this principle an indirect method has to be resorted to. The only property upon which depend- ence can be placed, for the purpose of chemical quantitative analysis, is its reducing action, under the influence of heat, upon certain metallic oxides, and that of copper is the one which general experience shows to answer best. In the ordinary volumetric application of the copper test, the pre- cipitation and diffusion of the reduced suboxide through the lquid interferes with the clear perception of the precise point of complete decoloration, and thus detracts from its delicacy. For purposes where minute accuracy is of no moment, a sufficiently approximate result can be obtained, but for physiological investigation, and in other cases where precision is indispensable, the process is quite unfit for employment. With the view of obtaining increased accuracy, chemists have had recourse to the plan of collecting the precipitate of reduced suboxide and weighing it as such or after reconversion into the oxide. From the difficulty, however, that exists in procuring the metallic oxide in a pure and uniform state, and from the impossibility of completely freeing the filter paper used from adhering surplus copper solution, some uncertainty is given to the results obtained by this method. To Proce. Roy. Soc. Vol.28 PU.2Z. West Newman g C° imp. no t Jey! UO. Fuoy. Soc Vel 2s. West Newman % C2 imp G.Thin od. nat. dei. 1879. | Volumetric Estimation of Sugar. 261 obviate the difficulty here presented, I suggested, in a communication published in the ‘‘ Proceedings of the Royal Society ” for June, 1877, that the precipitated suboxide should be collected and dissolved, and the copper subsequently thrown down by the agency of galvanic action upon a platinum cylinder, as is now frequently done in the assaying of copper ores. The process has been found, as shown by the closeness observable in the results of counterpart analyses, to admit of the greatest precision, and I have turned it to extensive account in some recent physiological investigations I have conducted. In its application to such a purpose, it may be held that time and labour should be considered as of no moment, but it frequently happens that a more ready process of estimation is needed than the gravimetric supplies, and on this account a volumetric method, free from the objection I have pointed out as belonging to the ordinary plan, constitutes a desideratum. A few years back Bernard introduced, for physiological purposes, a modification of the ordinary volumetric process, which is attended with reduction and the non-precipitation of the reduced oxide. The process involves the employment of a large quantity of caustic potash, _and the presence in the product to be tested of extraneous organic matter. Under these circumstances it happens that the reduced sub- oxide is held in solution instead of beig allowed to fall, and thus decoloration without precipitation occurs and enables the point of disappearance of the colour of the test to be ascertained with pre- cision. Bernard, in his remarks upon the test, simply made mention of the fact that under these conditions, reduction without precipita- tion took place, but Dr. d’Arsonval,* his Préparateur at the College of France, refers the effect to the solvent influence of the extraneous organic matter in presence of the alkali. Whilst engaged upon an inquiry into the merits of this test, the conclusion suggested itself to me that the agency preventing the deposition of the suboxide was the development of -ammonia. With an absolutely pure solution of sugar, such as may be obtained by inverting the ordinary crystallized cane sugar (refined loaf sugar) no amount of potash will hinder the instantaneous precipitation of the suboxide. With commercial grape sugar, however, and in a still more marked manner with honey, interference with precipitation is temporarily exerted, and this, I am led to conclude, is due to the action of the potash in producing ammonia from the small quantity of nitrogenous organic matter incidentally present. With this before me, the idea presented itself of resorting to the direct employment of ammonia for attaining the same result. It is well known to chemists that ammonia is a powerful solvent of the suboxide of copper, leading to the production of a perfectly colourless — * “Gazette Hebdomadaire de Médecine et de Chirurgie,” Sept. 14, 1877, p. 454. 262 Dr. F. W. Pavy on [Jan. 16, liquid; and this, from the facility with which it absorbs oxygen, quickly assumes a blue colour under exposure to air from the recon- version of the cuprous into the cupric oxide. If ammonia be added to the ordinary Fehling’s solution, a liquid is obtained which is rendered colourless by boiling with a sufficiency of sugar to effect the complete reduction of the cupric oxide present to the state of suboxide. As the saccharine product is dropped in the blue colour gradually fades, without any occurrence of precipitation to interfere with the perception of the precise moment when the point of complete decoloration is attained. The ammonia exerts no in- terference with the process of reduction, but simply dissolves the reduced oxide, leading, when complete decoloration is effected, to Lae production of a perfectly colourless, limpid quid. Enough ammonia must be present to secure that the suboxide is held in solution, and precaution must be taken that whilst the analysis is being performed the reduced oxide does not become reconverted into the oxide by exposure to the air. To obviate this the operation should be conducted in a flask instead of an open capsule. The appliance that naturally suggests itself as most suitable for employment is a flask of about 80 cub. centims. capacity, with a cork inserted into the neck, through which a delivery tube from a Mohr’s burette, graduated in tenths of a cub. centim., passes for dropping in the product to be examined. Through the cork, also, there must be an exit tube for the escape of air and steam from the flask. Should it be desired to avoid the impregnation of the surrounding atmosphere with ammonia, the exit tube may be connected by vulcanized tubing with a U-shaped tube containing fragments of pumice stone moistened with water or a weak acid. The burette being fixed in the stand, the flask is allowed to hang suspended, so that there may be nothing to obstruct the full view of its contents. The heat is applied by means of the flame of a spirit lamp, and the best position for watching the disappearance of colour is by the light reflected from a white back- ground specially provided for the purpose. It is convenient to have another burette, graduated in cub. centims., and of 100 cub. centims. capacity, fixed in the stand for holding and delivering the ammoniated copper solution. Messrs. Griffin, of Garrick Street, have constructed an arrangement adapted to meet the requirements. I at first took it for granted that in the action occurring the same relation existed between the amount of oxide of copper reduced and that of sugar oxidised, as under the employment of the copper test in the ordinary way, viz., that 5 atoms of oxide of copper were reduced by 1 atom of sugar, and the liquid I first employed was prepared by adding to 100 cub. centims. of Fehling’s solution 300 cub. centims. of strong solution of ammonia (sp. gr. °880) and 600 cub. centims. of distilled water. The liquid thus made contained one-tenth of 1879. | Volumetric Estimation of Sugar. 263 Fehling’s solution, and if it comported itself in the same manner as the latter, 10 cub. centims. of it would stand equivalent to ‘005 grm. of grape sugar. In working with this liquid the results obtained were so accordant in relation to each other that I had no misgiving about its uniformity of action; but I felt that before being definitely accepted they ought to be checked against known amounts of sugar. The accomplishment of this proceeding, however, is not altogether unattended with difficulty, on account of the uncertainty of obtaining grape sugar free from impurity and in a perfectly dried state. The method I have adopted has been to operate upon weighed amounts of cane sugar and produce inversion by boiling with an acid. I first found that the cane sugar, which is sold in coarse colourless erystals—that which is known as “ white crystal,’ and used for sweetening coffee—stood the test on examination for purity with Laurent’s polarimeter. A weighed quantity was taken, and, after being inverted by boiling with hydrochloric acid, the acid neutralised, and the liquid brought to a known volume, subjected to treatment with the ammoniated copper liquid. Repeated trials were made with varying quantities, and it was found that the results stood in har- monious relation to each other, but that the amount of sugar indicated was larger than the calculated amount of invert sugar from the weighed quantity of cane sugar taken. At first I was at a loss for an explanation of this result, but subsequent observation has revealed that in the case of the ammoniated liquid, 6 atoms of oxide of copper are appropriated by 1 atom of sugar, instead of 5, as in that of Fehling’s solution used in the ordinary way. When the reckoning is made upon this basis the results exactly correspond with the actual amount of sugar known to be present. Moreover, with solutions of ordinary grape sugar and diabetic sugar, examined comparatively with Fehling’s solution used in the ordinary way and the ammoniated copper liquid, the results exactly accord under the reckoning that 5 atoms of oxide of copper are appropriated in the one case and 6 atoms in the other by 1 atom of sugar. To be quite satisfied upon this point, a large number of observations * under varying conditions have been made, and whilst what I have stated holds good for the ammoniated copper liquid prepared from. Fehling’s solution, without any further addition of alkali, and with the addition of potash to the extent of 1 grm. to 20 cub. centims. of the ammoniated test, yet a larger quantity of potash alters the action, and with 5 grms., and anything beyond, the behaviour is brought to the same as that of Fehling’s solution used in the ordinary way, viz., 5 atoms only of oxide of copper are appropriated by 1 atom of sugar. With quantities of potash between the 1 and 5 grms., the results stand between the 5 and 6 atoms of cupric oxide. I may mention that observation has further shown that whilst 264 On Volumetric Estimation of Sugar. [Jan. 16, glucose prepared from starch behaves like other varieties of grape sugar, there is an intermediate product formed before the completion of the process of conversion, which behaves in a different manner from invert sugar, grape sugar, and sugar of diabetes. Hstimations made with the ammoniated copper liquid coincide with those made with Fehling’s solution without the presence of ammonia, and the addition of potash to the ammoniated liquid produces no modification of the result. In order that the ammoniated copper liquid may be brought to the same standard of sugar value as Fehling’s solution, and it is desirable that this should be the case, the proportion of copper must be in- creased so as to give 6 atoms against 5. By taking 120 cub. centims. of Fehling’s solution, 300 cub. centims. of strong ammonia (sp. gr. °880) and making up to a litre with distilled water, the proper pro- portion is obtained, and the ammoniated liquid gives results corrobo- rated in accuracy by the balance, and coinciding with those obtained by Fehling’s solution employed in the ordinary way. As a minor point it may be remarked that the diluted state pre- sented by the ammoniated liquid offers an advantage by diminishing the liability to error arising from any want of absolute precision in measurement. Twenty cub. centims. of the ammoniated copper solution, corre- sponding with ‘010 grm. sugar, having been run in from the burette containing the test, the flask is adapted to the cork attached to the delivery tube of the other burette containing the saccharine product for examination. The flame of a spirit lamp is then applied under: neath, and the contents of the flask brought to a state of ebullition and allowed to boil for a few minutes in order to get rid of the presence of air. The saccharine product is now allowed to drop from the burette until the blue colour of the test is just removed, and a perfectly colourless limpid state produced. On account of the ammoniated copper solution used being only equivalent to 2 cub. centims. of Fehling’s solution, it is necessary ‘that the product to be examined should not be in too concentrated a form. For delicate observation it is convenient that the dilution should be such as to require the employment of from about 10 to 20 cub. centims. to decolorize the 20 cub. centims. of the ammoniated copper solution. The ammoniated copper solution enjoys the advantage of possessing a self-preservative power. It is well known in the case of Fehling’s solution that, in the course of time, not only does the liquid become impaired in stability, but actually reduced in strength, by the spon- taneous deposition of a certain amount of suboxide. Not so, how- ever, with the ammoniated liquid. Here the conditions are such that under exposure to air the copper cannot fail to remain in solution and 1879.] —-~Dr. Ord. ‘Structure of the Spinal Cord. 265 to be maintained in a fully oxidized state. A further advantage is given by the influence of the presence of ammonia on the colour of the test, for, in proportion to the height of colour of a volumetric liquid, so is its degree of delicacy as a reagent, and the effect of the addition of ammonia to the ordinary copper test is to considerably increase the blue colour belonging to it. Seeing that the test here proposed acts with equal efficiency either in the presence or absence of extraneous organic matter, it is alike adapted for employment by the chemist, the physiologist, and the medical practitioner in relation to diabetes. IV. “On the Effect of Strong Induction-Currents upon the Structure of the Spinal Cord.” By Witu1Am MILLER ORD, M.D., F.L.S., Fellow of the Royal College of Physicians, Physician to St. Thomas's Hospital. Communicated by J. Simon, C.B., D.C.L., F.R.S. Recerved December 17, 1878. (Abstract. ) The results of a series of experiments are related. They were founded upon considerations offered by chorea, tetanus, and similar diseases ; certain clinical facts and post-mortem observations having led the author to suppose that the occurrence of protoplasmic convul- sion or spasm in the grey matter of the nervous system was con- sistent with the morbid appearances and with the history of cases. The present series of observations was made upon adolescent dogs. The spinal cord was the part selected for experiment. The dogs were ' killed by chloroform, and the cord, rapidly exposed, was galvanized for different periods and in different directions. In all cases parallel experiments were made with dogs of the same age and size, all points of the operation being carried out in the same way, save for the appli- cation of the galvanic currents. The following effects were observed :— 1. Broadening of the cord in parts through which currents had been passed longitudinally, narrowing where transverse currents had been applied. 2. In the narrowed parts a great diminution in the sectional area of the grey matter with retraction of the posterior horns. 3. In the same parts a remarkable dilatation of the central spimal canal, and an infiltration of myelin and leucocytes into the cavity. 4. The production of spaces around corpuscles, vessels, and nerve- bundles by the retraction of the protoplasmic matter. Such spaces were often found filled with débris, containing coagula, myelin, and vacuoles. They corresponded in appearance with the “ perivascular erosions ” of Dickinson. VOL. XXVIII. U 266 Mr. G. J. Romaneson [Jan. 16, 5. The contraction of nerve-corpuscles, which, being much more marked between their branches, gave them a scalloped appearance. Vacuoles were formed within them, and in the spaces formed by their retraction, and by the retraction of surrounding parts. 6. In some places rupture of nervous tissue was observed. 7. In longitudinal sections nerve-fibres were found flattened and varicose, the flattening resembling that described by Hlischer in fibres of median nerve in chorea. | Conclusions.—1. That, in young dogs, the protoplasmic constituent of the grey matter contracts en masse under the influence of strong faradaic currents. 2. That it contracts unequally and irregularly by reason of its un- equal and irregular sectional area, causing thereby condensations at certain points—notably in the anterior horns and around the central canal—and rarefaction at others—notably in the middle of each crescent; such rarefaction going on sometimes to rupture of tissues. 3. That nerve-corpuscles contract in various degrees according to the strength and duration of currents, and that while they tend in contraction to become spherical they also tend to become vacuolated. 4, That the vessels are in some places strongly contracted and empty; in others dilated and filled with blood clot, having the appear- ance of embolus. 5. That the appearances correspond so decidedly with appearances in chorea and tetanus as to give ground for the supposition that con- tractions, such as are produced by electricity, do actually occur during life under the effect of nervous shock, and may be phenomena causal or associate of disease. V. “Concluding Observations on the Locomotor System of Meduse.” By Grorce J. Romanes, M.A., F.L.S. Com- municated by Professor HUXLEY, Sec. R.S. Received De- cember 30, 1878. (Abstract. ) The principal bulk of the paper is devoted to a full consideration of numerous facts and inferences relating to the phenomena of what the author terms ‘artificial rhythm.” Some of these facts have already been published in abstract in the ‘“ Proceedings of the Royal Society”? (vol. xxv), and to explain those which have not been published would involve more space than it is here desirable to allow. The tendency of the whole research on artificial rhythm, as produced in various species of Meduse, is to show that the natural rhythm of these animals (and so probably of ganglio-muscular tissues in general) is due, not exclusively to the intermittent nature of the ganglionic 1879. | the Locomotor System of Meduse. 267 discharge, but also in large measure to an alternate process of ex- haustion and restoration of excitability on the part of the responding tissues—the ganglionic period coinciding with that during which the process of restoration lasts, and the ganglionic discharge being thus always thrown in at the moment when the excitability of the respond- ing tissues is at its climax. Light has been found to stimulate the lithocysts of covered-eyed Medusz into increased activity, thus proving that these organs, like the marginal bodies of the naked-eyed Meduse, are rudimentary organs of vision. The polypite of Awrelia aurita has been proved to execute move- ments of localization of stimuli, somewhat similar to those which the author has already described as being performed by the polypite of Tiaropsis indicans. Alternating the direction of the constant current in the muscular tissues of the Meduse has the effect of maintaining the make and break stimulations at their maximum value; but the value of these stimulations rapidly declines if they are successively repeated with the current passing in the same direction. In the sub-umbrella of the Medusz waves of nervous excitation are sometimes able to pass when waves of muscular contraction have become blocked by the severity of overlapping sections. Hxhaustion of the sub-umbrella tissues—especially in narrow con- necting isthmuses of tissue—may have the effect of blocking the passage of contractile waves. Lithocysts have been proved sometimes to exert their ganglionic influence at comparatively great distances from their own seats—con- tractile waves, originating at points in the sub-umbrella tissue remote from a lithocyst, and ceasing to originate at that point when the lithocyst is removed. A nervous connexion of this kind may be maintained between a lithocyst and the point at which the waves of contraction originate even after severe forms of section have been interposed between the lithocyst and that point. When the sub-umbrella tissue of Aurelia is cut throughout its whole diameter, the incision will again heal up, sufficiently to restore physiological continuity, in from four to eight hours. January 23, 1879. W. SPOTTISWOODKE, M.A., D.C.L., President, in the Chair. The Presents received were laid on the table, and thanks ordered for them. v2 268 Prof, E. J. Mills and T. U. Walton. [Jan. 23, The following Papers were read :— I. “ Researches on Chemical Equivalence. Part I. Sodic and Potassic Sulphates.” By Epmunn J. Miuts, D.Sc., F.R.S.. “Young” Professor of Technical Chemistry in Anderson’s College, Glasgow, and T. U. Watton, B.Sc. Received October 16, 1878. The conception of a chemical equivalent as employed in these researches corresponds to a definition first given* by one of us, viz., that the chemical equivalent of a body is that weight of it which does - the unit of work. We do not therefore use the term in its ordinary sense; as, for example, when it is said that H is “equivalent” to Cl, Na, &. The following experiments were arranged with the view of determin- ing the effect of potassic and sodic sulphates on the rate of formation of ammonia, when nascent hydrogen is made to act on potassic nitrate. Judging from their behaviour in other cases, it was expected that in this instance, also, their action would be one of retardation. Hxperi- ment, however, has proved the reverse, on the whole, to be true. The extremely delicate nature of the reaction, which is liable to be spoiled by the accidental falling in of a single speck of dust, or by slight variation of temperature, or unequal exposure of the different solutions to light, rendered the attempt to measure the effect a matter of peculiar difficulty. At first, common sheet zinc, thoroughly cleansed from grease, was placed in a solution of potassic nitrate and hydrate, and the amount of ammonia formed during periods varying from twenty-four hours to one week was measured. But the results were very irregular and unsatis- factory. Galvanic couples seemed to be established at certain points on the surface of the zinc, probably due to the presence of iron or lead as impurities. Thin zinc foil was next tried, but with little better result; neither were any alterations in the shape or disposition of the foil attended with success. Fresh experiments were also undertaken with sodium amalgam instead of zinc and potassic nitrate; but the action, though rather more uniform, was still very uncertain. It was found impossible to obtain a perfectly homogeneous solution of sodium in mercury, entirely free from sodic oxide and hydrate; and this seriously impaired the accuracy of measuring out the amalgam. The only plan which was found to give results at all comparable with each other, was using zinc amalgam and potassic nitrate. The experiments were performed in wide-mouthed glass-stoppered bottles of cylindrical shape, having an internal diameter of 60 mm., and a total capacity of 815 cub. centims. Each bottle contained 1 grm. * “ Philosophical Magazine,” [5], i, 14. 1879.] On Chemical Equivalence. 209 potassic nitrate, 1 grm. potassic hydrate (prepared from the sulphate by means of baryta water), and a quantity of anhydrous alkaline sulphate, varying from 0 to 1 grm.; the whole being dissolved in 150 cub. centims. of distilled water, very free from ammonia. The reagents had been carefully purified. 380 cub. centims. of amalgam, prepared by dissolving 10 grms. zinc in 10 kilogs. mercury, were then added, and the “system” was preserved from dust and light. After twenty hours, the amount of ammonia was estimated by Nessler’s method. Traces of this substance were occasionally present in the solutions employed, and a corresponding correction had to be made. In every experiment, nine solutions were prepared at the same time—three free from sulphate, three containing sodic sulphate, and three potassic sulphate; and the mean of each three was taken as the true value for that particular experiment. Fifteen comparisons of each of nine solutions, arranged in this way, were made with different quantities of sulphate. The temperature was taken at the beginning, in the middle, and at the conclusion of the experiment; the tempera- ture at night being registered by one of the automatic thermometers sold by Negretti and Zambra. Owing to the extreme delicacy of the reaction and the slight causes which suffice to interfere with it, the numbers obtained from single experiments are not sufficiently reliable to measure the precise amount of change caused by varying the quantity of alkaline sulphate. Hvery comparison, however, though made with a different weight of sulphate from that employed in the others, involved equal weights of potassic and of sodic sulphate; and hence the relative effect of those two bodies has been very clearly approximated to. The following table gives a summary of the observations made :— Ratio. Grm. Mean | @?m. ammonia AAA sulphate Seay formed in the , Experiment | Experiment added. P-™* | plank (150 c.c.).| Blank. | with sodic |with potassic, salt. salt. O'1 18-4 0 0000432 100 102 2 99°5 Ont 14°6 0 -0000135 100 99-1 88 °8 0-2 13 °4 0 0000424. 100 100-1 103 -2 0°3 16 °4 0 0000459 100 SS: 79°5 0°3 14:1 0 -0001200 100 103 °9 102 °0 0 *4: 15-6 0 -0001350 100 105 °4 109 °5 *0°5 15 °6 0 -0000655 100 108 °5 97 °7 *0°D 16 °3 0 -0000493 100 TOR 96-6 0°6 18 °4 0 0000391 100 99 °5 105 1 0°6 22°6 0 -0000445 100 1O9E7 107 °8 Oh gel 0 -0000431 100 104 °8 104 °8 0°8 15 °2 0 -0000670 100 113 °8 113 °2 0°9 15 *4: 0 -0000679 100 ROO" 113 °4 a O 12°3 0 -0000359 100 WIDE Bi 129-8 LO Ne facO 0 -0000456 100 E27 114°9 270 Prof. E. J. Mills and J. Hogarth. [Jan. 23, The ratio of the working effect of sodic to that of potassic sulphate, as calculated from the numbers given above, is 100°16 : 100, with a probable uncertainty of 1°3 per cent. This is the mean value, reckoned by the method of least squares, from the whole of the observations. The rejection of the four experiments marked with an asterisk, which differ somewhat widely from the rest, would give the ratio 99°53 : 100, with a probable uncertainty of 0°73 per cent.; while the probable error of a single observation would then be reduced from 5:02 to 2°4 per cent. [Owing to the number of determinations made, any error in the result is but very slightly affected by error in the ammonia estimation. | The conclusions which we think may fairly be drawn from these numbers are :— (1.) That sodic and potassic sulphates have a well-marked influence on the reaction to which we have referred ; (2.) That as more sulphate is added, the reaction is accelerated ; (3.) That equal weights of sodic and potassic sulphates have as nearly as possible the same working effect. The last conclusion may be otherwise expressed thus :— Tf we represent our equivalent of potassic sulphate by a number, then the equivalent of sodic sulphate is represented by the same number. II. “ Researches on Chemical Equivalence.” Part II. Hydric Chloride and Sulphate’ By Epmunp J. Mis, D.Sce., F.R.S., and JAMES HoGartH. Received December 4, 1878. While carrying out our researches on lactin,* it struck us that use might be made of it to compare the dynamical equivalents of acid bodies. We accordingly selected hydric chloride and hydric sulphate for the measurements in question, and prepared solutions of these acids, containing respectively 73 grammes hydric chloride (2HCl), and 196 grammes hydric sulphate (2H.SO,) per litre. An experi- ment was first tried with 5 grammes lactin and 10 cub. centims. of the hydric chloride solution in a total volume of 70 cub. centims. At a temperature of 17° C. there was no change of rotation in twenty- four hours. In a second experiment a similar solution was raised for an hour to 40° C., and then for an hour to 60° C.; but without effect on the rotatory power. The temperature of 100° C. was finally adopted, the change at that point taking place at a rate admitting of accurate measurement. The method of experiment was as follows :— A measuring flask was made marked to contain 60 cub. centims.; in this were placed 50 cub. centims. of a 10 per cent. solution of lactin (i.e, 5 grammes), the acid measured in, and the volume made up to * Post, p. 2h: 1879. ] On Chemical Equivalence. Dia the mark. To prevent evaporation during heating, the neck of the flask was left long, and a narrow bent tube attached by an india- rubber joint. The time was accurately noted when the flask was placed in the bath. After half an hour, the flask was taken out quickly, plunged into cold water, and the contents when cold trans- ferred to the polarimeter tube. The tube used in the researches on lactin had to be modified in these experiments, the cement not being able to withstand the action of the acid. In its altered form, the plate glass covers were secured by two screw rods and nuts, a thin washer of gutta-percha tissue being placed between the ends of the tube and the plates. This washer did not materially affect the length of the column, and made the tube perfectly tight. The length of the tube was thus reduced to 216 millims. The results of these experiments are given in the following table. The quantity of acid is the only varied condition of experiment. Action of Hydric Chloride and Hydric Sulphate on Lactin. Total volume in each case 60 cub. centims. =5 grammes. Weight of Lactin Hydric chloride. Hydric sulphate. Half- hee Nowa Now 2s |) (Nowe |) Nos 4e leiNo: 5. |” Not Gs) Nowy. erva's-! 4cub. | 4 cub. |7°5 cub.| 8cub. | 4ecub. | 4cub. |7°5 cub. centims. | centims. | centims. | centims. | centims. | centims. | centims. 0 9-565) |, 9-565 | 9°565 | 9-565; 9-565 | 9565 | 9-565 1 1Ocs2@ | LO197-| 10;767 | 10°77 |) 10)-320) | 10-278 | 10848 2 10-812 | 10°670 | 11°383 | 11°340 | 10°974 | 10°720 | 11:°423 3 2S) | Tl OVO) 1-790) |) La s633" |) 119°203) | 11-035 | 11°643 4, ANON EBay. |) Wes8aO") Mie 742) ya 355: | 11286: |) 1-850 5 11-490 Gi.” tes ae 11 °852 | 11°754 11 °445 | 11 °850 i 8 11°770 | 11°670 111°854 | 11-607 9 10 iat 11°765 | 11-715 The equation A is deduced from the average of Nos. 1 and 2 by the method of least squares, the probable error of a single comparison of calculated and experimental numbers being ‘0653. The equation B is similarly deduced from Nos. 5 and 6, its probable error being °0587. C is the equation to No. 3 with a probable error -0818 Dey ” No. @ 9 ” ” 1063 ” ” No. 4 ,, ” » 0848 272 On Chemical Equivalence. [Jan. 23, Hquations. TQ Se holes oa: y=9 6785+ °56035e— 0362127. Bieta y=9 6500+ °638271e— 046902". CS Sete y=9 6827+1 04941ea— 116352". ILD HS, Svea. eaten y=9 °7283+41 :00775a— °110902". HL RES Bites y=9 “6889+ °9895la— "109312". In each equation y is the rotation in degrees, # is the time in half- hours. By placing = =( in each equation, we find the value of « when & y has its highest value. The corresponding value of y is thence calculated by substitution in the equation considered. We thus find data for the comparison of the two acids. HCl H.SOx Net ste w=7°74, y=ll-846 | B...... 2=6°74, y=11-780 OR ks a=4'51, y=12.-048 Ds area wad 54, -y=12)-0m7 2HCl H,SO, : i x=4-53, y=11-928 | B...... 2=6°74, y=11-780 These results show that though 2HCl may be the “equivalent” of H,SO, in weight for saturation (7.e., in the ordinary sense), it certainly is not the equivalent in the dynamical sense. They also render it highly probably that HCl is equal dynamically to H,SO,. Ostwald,* by a method based on the alteration of the specific volume of solutions, eon a result which our numbers, though not as perfect as we could wish, nevertheless strongly con- firm. has shown that the ratio * “ Journ. Prakt. Chem.,” N.F. xvi, p. 419. + If the curve equations be examined, it is found that the highest value of y is practically the same in each. By taking the average value =11°'924, and calculat- ing to specific rotation (assuming that the action involves no change of weight), the number 73°78 is obtained. This falls short of the specific rotation of galactose (83°), and seems to point to the dual nature of lactin mentioned in the researches on lactin ; probably at this point the sugar in solution is Fudakowski’s lacto-glucose. (“ Deut. Chem. Ges. Ber.,” ix, 42-44.) 1879. | Researehes on Lactin. Vile III. “Researches on Lactin.” By Epmunp J. Mis, D.Sc., F.R.S., “ Young” Professor of Technical Chemistry in An- derson’s College, Glasgow, and JAMES HoGARTH. Received December 4, 1878. Although lactin, or sugar of milk, has been investigated by nume- rous chemists, there are many problems connected with it which still await solution. We have accordingly undertaken a series of experi- ments in connexion with this remarkable compound, in the hope, not only of obtaining special results, but such as may be made available in studies of a more general nature. As our work throughout has been for the most part optical as well as chemical, we have first to state our methods of obtaining the constant of Jellett’s polarimeter, the instrument employed in our investigations. 7 I. Determination of the Polarimeter’s Constant.—a. By quinine sul- phate. 5°5412 grms. of the sulphate were dissolved in water acidu- lated with hydric sulphate, and the solution made up to 100 cub. centims. The average of five readings gave a solution of —25°73, equivalent to a specific rotatory power of —232°:16. De Gris and Alluard* give —255°'6, a number which is to our experimental num- ber as 1:10096 to 1. _ ~. By cane sugar. Three sets of experiments on solutions contain- ing respectively 16-3500, 8°1750, and 4:0875 germs. in 100 cub. centims., and embracing five, four, and four readings, gave a general mean reading 21°°74, equivalent to a specific rotation 66°°48. This is to the generally accepted number (73°'8) as 1 to 1°11011. y. By salicin. T'wo sets of experiments with solutions containing respectively 4°9156 and 2°4578 grms. in 100 cub. centims., and each embracing three readings, gave a general mean reading 4°°92, equal to a specific rotation 50°-046. Bouchardat} gives 55°°832, which is to the number got by Jellett’s instrument as 1:11561 to 1. The average of the three numbers, 110096, 1:11011, and 1°11561, gives 1°10889 as an experimental factor for converting our Jellett readings into ordinary readings. The relation of the two scales may also be seen by examining the arc divided to read percentages of cane sugar with a solution contain- ing 16°35 grms. in 100 cub. centims. In the Jellett instrument, an are of 21°-666 is divided into hundredths for this purpose; and as 16°35 grms. pure cannose read 100 on this scale, the specific rotation * “ Compt. rend.,”’ lix, 201. + “Compt. rend.,” xviii, 298. 274 Prof. E. J. Mills and J. Hogarth. [Jan. 23, is 66°:256, which is to 73°°8 as 1 to 1:11386—a factor wheehl differs from the above experimental one by 0°45 per cent. All the specific rotations given by us are corrected by this factor, and are comparable with those in general use. | In all our experiments the specific rotation is calculated by the formula lal . Where [a|= specific rotation, a = the reading in degrees, V the volume of solution containing the weight p, and 1 = the length of the column in decimeters (in the above experiments, II. Determination of the Permanent Specific Rotation of Lactin—The | lactin was purified by filtration through animal charcoal, and two or three crystallizations, after which it left no sensible residue on ignition in-air. Five sets of readings were made :— ty) (1.) Average of 5 readings. Specific rotation 52°84 (2.) 99 99 99 99 99 53 23 (3.) 99 >) : 99 2) 39 53 ‘37 (4.) 99 3 yb) oP] 9 53°04 (5.) 39 99 +9 99 99 53 0% The general mean of these numbers is 53°°12, which, multiplied by the factor 1:11386, gives 59°-17 as the permanent specific rotation of lactin. The number given by Berthelot* is 59°°3. In every experi- ment, care was taken that the rotatory power of the solution had become constant. Three different samples of lactin were employed. Experiments (1), (2), and (8), were on sample I, (4) on sample II, and (5) on sample III. As the samples were prepared at different times, and by a method varying slightly each time, the very small differences in the results show that the lactin contained little or no impurity. : Til. Hxamination of the Law for the Change of Rotation m a freshly prepared Solution of Lactin.—If the rotatory power of an aqueous solution of lactin be examined at short intervals of time, it soon becomes apparent that a change is taking place, the angle through which the plane of polarization is rotated becoming gradually less. The object of the following experiments is to quantify the phenomenon in question. | 3 Five grms. of lactin were dissolved as rapidly as possible (time taken, 1 hour 15 minutes) in cold water, and the solution made up to 100 cub. centims. The polarimeter tube (2 decims. long) was filled with the liquid, and a first observation taken 15 minutes after com- plete solution, or 13 hour after first contact. Succeeding readings * “ Ann. Ch. Phys.,” [3], liv, 82; lx, 98. ee ay > poe eS SS, o4 + S + a he Se aT 57 a ss 1 aa ‘C 3 i - - : et oh A 7 | ae cs q i hs hp § 4 ene ae a _ 4 - 14 4 a < x j - 7 ‘ \ + ue } ‘ 3 t = ‘ : : . Ie , ° a . ~All : aay ei _ “fe la nf Y \ . a) le ve - : Aqueous. 1879. ] Researches on Lactin. 275 were made at intervals of 2 hours, the results bemg given under Table I, No. 21. See Table I. In order to increase the total change and lessen proportionally the error of experiment, it became necessary to use a stronger solution, to increase the length of column, and to reduce the interval elapsing between first contact and first observation as far as possible. To attain these conditions the following method was adopted :—About 10 grms. of powdered lactin were rubbed in a mortar with about 60 cub. centims. of water for half an hour, the solution filtered, and the first observation taken one hour after first contact. The metal tube belonging to the polariscope was also discarded, and a glass one constructed from a piece of tubing 17 millims. wide, by sealing ona side piece for the introduction of a thermometer, and grinding the ends carefully until it measured 242 millims., the greatest length admitted by the polarimeter. Two glass disks were cemented on the ex- tremities, and the tube covered from end to end by a helix of thin tin tubing, through which a current of water might be passed to keep the temperature constant; to guard further from variations in temperature the tube was covered with cotton wadding. With these precautions three experiments were made (Table I, Nos. 1, 2, 3), the result being that the total change was nearly doubled. In all the other experi- ments the method was slightly varied, the lactin being placed in a bottle with a ground glass stopper, 60 cub. centims. water placed on it, and the whole shaken vigorously at intervals for half an hour, filtered, and the first observation taken as before. Hach experi- ment extended over six hours, and included ten observations. For each observation. three or four readings were made, and the average taken. In Nos. 4, 5, 6, 7, 8, 9, 13, 14, 15, 16, 17, 18, 19, 20, of the accompanying table, varying weights of sodic and potassic chloride were introduced. In every experiment the thermometer was read at the same time with the rotation; and the average temperature, as _ well as its extreme variation, is given in thetable. That the different experiments might be compared, we have expressed them by the - equation— y=atbet+ cz’, in which y is the angle of rotation, z the time in half-hours, counting from the first contact of the lactin with water, and a, b, and ¢, are constants. The values of a, b, and c, were calculated by the method of least squares. In Table II are given the equations, accompanied by the probable error of a single comparison of the calculated and experimental values of y. The sum of the + actual errors is in nearly all cases zero. Table I.—Resnlts of Experiments on Lactin. ii Sod. Chior. in | Containing 1 gramme Pot. Chior. in Containing 5 grammes Pot. Chlor. in | Containing 6 grammes Sod. Chior. in | 10 grammes} 10 grammes Nature of Solution Aqueous. SE ea es oe Bie T60'Ge: Aqueous. Eaee (calc: Ser etreat Pot. Chior. | Sod. Chlor. : o) ° Avorago:Teinpornturo ves 10-3 166 ito Wwe 101 122 10° 1 13a 10°1 12'9 14 1351 118 12 1r7 129 1r9 15 nme 12075 12:750 13-333 14070 1147 14°823 13°523 14190 17/033 15-460 16:012 13°730 14-633 15°317 167483 14-083 Fy 12°87 12270 19157 13:487 13°712 14202 13:07 13:600 16435 14847 15°503 13'350 14035 14717 15:087 13°50 | 4 12/087 11388 | 12.583 13050 13°262 13°833 12°640 13°040 15'880 14312 14-954 12877 13°590 14085 15°480 19°263 6 weno | iac7 | 12:078 12°567 12831 13°367 12240 12'547 15433 13°887 14505 12537 13°193 13'690 15:053 12:863 6 11-300 nis 11-707 12230 121485 13°00 11873 12147 15:017 13-380 14:037 121197 12'793 13:203 14650 12°607 1 1100 10'833 12050 1vsi7 11330 11:935 12°143 12675 11617 11843 14633 13-073 13'747 11930 12525 12'950 14290 8 10018 187 ives 11-070 11540 11:850 12:37 11340 11:867 14-270 12-737 13'333 11°667 12-253 12°65 13°943 12°063 0 10°40 10 10510 10226 11327 Ieiio 10-683, 11133 11405 11'810 10763 10:933 1-147 13°768 12/220 12'857 11172 11:833 12/223 13°320 11°600 Nl 10:026 12 10210 9'838 11-007 10-713 10-447 10787 11077 11:503 10 390 10°647 10°733 13278 11620 121453 10°785 11463 11:852 11210 13 | 9'083 | u | 9860 0517 10°85 10392 10-218 10°547 10727 17 10:190 10°257 10583 13:00 11-477 12'167 10'513 11-140 11660 12/533 10°873 Pormanont Rotations! 8083 wiz | su04 10148 9625 9770 9:620 10:340 9°380 9-198 9:898 11783 10°667 11083 9:332 10:140 10°780 10:923 0-507 “ ; Bi hacloe totta ludaeaiieliencantall cotimite intense lees a ee = Peete | i ind oes any a Extromes of Temperature | OSto1ls | 9'F tolls | 1d to ILS | 15 to 12) P41 to 10d | ALG to 18S 1s to 125] g's tors | 11-5 to 6 | 1310 116 11-4 to 11°8 | 121 to 143 | 11°6 to. 120 | gs to 10-3 | 1f5 to 14 | 185 to 13-2 | 1i3 to 17 {<= aS | el ! fe as =| Number... ee 2 3 4 5 6 7 8 9 10 n 12 13 M4 15 16 7 18 19 20 Le Re EY bee NES = No. 21. | 3 Een 7 ih ll 15 19 23 | 27 Permanent. | Rotation = 9°250 S117 767 TUT 6'875 6700 | 6550 e417 276 Prof. E. J. Mills and J. Hogarth. [Jan. 23, Table IT. Number. Equation. Probable error. 1 .... y=13 °9002— -485482+4+ 0143302? .... 0315 2 y= 14 °13825— °569192+ -017755a7 «2... 0423 3 y=13 6284— -494762+ °0146292? .... 0323 A .... y=15:4100— °62775a@+ 02171227 .... “0316 5 secs. Y=14°6188— 4986624 °0188332? .... O1738 6 y=15 0692— "71727e+ 0269590? .... 0519 7 y=15 1537— *60585a+ °0199432? .... 0269 8 .... y=15'1654— °54298x%+ 0163872? .... +0232 9 .... y=15°8792— 58006a+ °01740207 .... 0263 10: ....6 y=l4 5430— -567/024- 0184592" -. 2. e022e 11 4... «y= 14°6154— -562402+ 01838827 .... 0368 12 2... y=ld5 '3747— °668602+ 0235140? .... 0380 13 .... y=18'2142— °6525407+ 0201090? .... 0224 14 4... . y=16 6262— ‘6d51d5024 (0205402* ©. ROS 15 1... y=17 -2230— -64521e+ 0204480 .... 0227 16 .... ys 14 6339— -482322+ 0184740? .... “0177 V7 2-0: y= ld 5954— *5625224 0177962" oo 18 .... y=16°4546— °654177+ (0221412? .... 0455 19 ....; Y=17, 9923 — 58714e-+- 01613 le?) eee 20 ..02, y=l4 9011— -45421¢4 -012057e_ (2.3. Zap By the aid of these equations we can now calculate the initial specific rotation of lactin, or the rotation when x=0 calculated to unit of weight. When «=0, y=a; and the permanent rotation being known, ax 59-17 permanent rotation the values found, the chloride experiments being averaged by them- selves. the initial specific rotation = The following are Average of Nos. 1, 2, 3, 10, 11,12........ 93°98 i 53 INOS: 450536 Cee Bae ae 91-90 A jy UNGSA ARS V9 2 Eee ae eee Seer ‘ jp INOS. WMA) 15 es See ee 91-87 ne oy INOS SO ndis 8 tte 91 -37 Single experiment, Nos LO fjca-.- eee 95 30 as FP Nov 20: sco sees 92 16 Average of the twenty experiments, 92°63. On differentiating the equations, putting al and calculating the Ab , values of x and y, we find that the values of y thus got do not corre- spond to the permanent rotation, but are always greater; showing that the change in rotatory power does not progress according to the 1879. ] ; Researches on Lactin. 207 same law throughout, but that, at the point referred to, a new reaction begins. This value of y is proportional to the amount of lactin in solution, indicated by the permanent rotation; and the specific rota- tion calculated from it in the different experiments is practically constant, its average value (from twenty experiments) being 64°°8. The following are the values of « and y when — a Table ITT. No. Hoe Y Specific rotation. ee. fe iN OS: one eee ie 66 “71 Dis << «Bes GRO ata, ONG anilecy. « 66°14 BH tana ale NG Gy even UMASGeasd.. 64°95 AA sca, « Se ACA Oye a ea eieee ORS AA acta. « 63 °42 5 ec WS CAB s « vatets NO A ee. 65 ‘11 Otnst s eae OG ub apeiestaie NO Saad. - 63°31 7 Coe PSO Ase « TOES SS es 63 °91 Sipe dara. IGS EG) ie ne ORO OME ssadeis 5 65 63 ger area HOE OOOrS 2 sik TOA BOs Ah a 63 °22 OS PS. OES SS9 | Ses 1 NORA SRM, ctae. 64 -20 11 Me MO GLO 2 st LOM oS meee. 42% 66 °39 ae e's TAQ) Atte MONG22 Here. 0: 200 63°53 OMe. MG 225 2 eee: 12 O20 eras 0 64 ‘88 12 11S) Seton ri seni bcA oleh). 2508 63°57 | Ge anak esa LSM OW MPa ets EL ZIRSS el Mel, 2h 64°78 Go Ab AL, ESS Sse on LOM SONG ea 65°41 JL ae PS, BOA manages Lele AO terse ute - 60°06 Sy Le. PASH 2WUES Mae AM O22 Wakes 63°79 RO Te hs, SIT OOM sey PAV 25 Oni ge Sate 66 36 BOREAS, NSESSOR A See. MOOD Aas 87.558 65 ‘71 This break in the change seems to point to the dual nature of lactin mentioned by I‘udakowski,* whose experiments show that lactin, like cannose, gives two glucoses—-lacto glucose ana galactose. An increase of temperature evidently hastens the change; but the exact relation of temperature to the rate of change has not been dis- covered. The presence of sodic or potassic chloride increases the amount of lactin in solution, but has no apparent effect on the rate of change. IV. Action of Hydric Nitrate on Lactin.—We made an attempt to trace this action, but did not succeed in overcoming experimental difficulties. The first of these was the impossibility of completing the action with the quantity of acid required for the first change. If a * “ Deut. Chem. Ges. Ber.,” ix, 42—44. 278 Researches on Lactin. [Jan. 23, larger quantity of acid were used, the first changes were so rapid as to evade measurement; moreover, the oxalic acid formed, by crystallizing in the acid liquid, made accurate observation impossible. By adding the acid in small successive portions, we nevertheless succeeded in obtaining an outline of the reaction, of which the curve drawn below is an accurate general expression. Rotation. Hydric Nitrate. Dubrunfaut, who has also examined this action,* asserts that the rotatory power first rises to +3 of the original amount, then falls gradually to zero, again rises to $ of the original rotation, and once more falls to zero: the highest rotation corresponding to galactose, the first point of inactivity to mucic acid; the second rise probably to dextro-tartaric acid; and the second fall to the formation of oxalic acid. Our experiments show the formation of a levo-rotatory sub- stance, perhaps levo-tartaric acid. The general form of the curve constitutes it an interesting and novel addition to chemical curves. V. Note on Solubility. —The mutual relations of water and lactin in solution undergo a change upon which the change of rotation most probably depends. Water shaken with a large quantity of very finely powdered lactin at a temperature of 17° C., takes up a quantity of lactin corresponding to a solubility of 1 part lactin in 10°64 parts water. With four hours’ contact, the solubility increases to 1 part lactin in 7:49 parts water. The permanent solubility got by the analysis of the mother-liquor of lactin crystallized over oil of vitriol is 1 part lactin in 3°23 parts water. In the solution of the lactin a fall of temperature of 0°45 C. was observed. Pohl+ also found a de- pression of temperature (0°88 C.); while Dubrunfaut alleges that heat is evolved. Conclusions. I. The initial specific rotation of lactin is 92°°63. II. The permanent specific rotation of lactin is 59°°17. * “Compt. rend.,”’ xlii, 228. + “Journ. Pr. Chem.,” lxxxii, 154. 1879.] Mr. J. B. Hannay. On the Microrheometer. 29) III. The change of rotation of a solution of lactin can be expressed by a mathematical equation. TY. When the specific rotation 64°°8 is reached, the law of change must be expressed by a different equation. V. The initial solubility of lactin is 1 part lactin in 10°64 parts water. VI. The permanent solubility is 1 part lactin in 3:23 parts water. IV. “On the Microrheometer.” By J. B. Hannay, F.R.S.E., F.C.S., lately Assistant Lecturer on Chemistry in the Owens College, Manchester. Communicated by H. E. Roscog, LL.D., F.R.S., Professor of Chemistry in the Owens Col- lege, Manchester. Received December 11, 1878. (Abstract. ) In this paper the author reviews the work done by chemists and physicists in determining the relation between the chemical composi- tion of a liquid and its rate of flow through a capillary tube. Poiseuille* ascertained, in a very accurate manner, all the physical laws relating to the rate of flow, as regulated by temperature, pressure, and dimen- sions of the tube; but on examining saline solutions he could make nothing of the numbers presented, because he used percentage solutions instead of solutions proportional to the equivalent of the body dissolved. Graham,} noticing that Poiseuille had discovered a hydrate of alcohol by running various mixtures of alcohol and water through the tube, examined mixtures of the various acids with water, and found that the hydration proceeded by distinct steps of multiple proportions. Several others, notably Guerout,t have since worked on the same subject, but as they have only worked on organic liquids, and have done all the rates at the same temperature, the results throw no lght on the phe- nomena. Thus water runs about five times as quickly at 100° as at 0°; and in a series of alcohols, such as Guerout experimented upon, the differences between their boiling points were very great, so that, their vapour tensions or molecular mobilities being quite incomparable while at the same temperature, the experiments do not admit of any real interpretation. The author reserves the organic part of the in- vestigation, which requires the determination of vapour tensions, till a future paper, and in the present deals with saline solutions. The phenomenon of the flow of liquids through capillary tubes has * « Ann. de Chim. et de Physique,” [8], t. vii, 50. 4 < Phill Trans:;,’ 1861; p- 373: t “Comptes rendus,” xxix, p. 1201; lxxxi, p. 1025. 280 Mr. J. B. Hannay. On the Microrheometer. [Jan. 23, been called in this country transpiration, while in other countries no distinct name has been adopted ; and as the English word is already in use in French for another purpose, and properly applies to gases (the laws relating to which are quite different), the author proposes to use for liquids the term ‘ Microrheosis,’”’ from pxpes and pew, the instrument being called the microrheometer. The form of apparatus which the author finally adopted is figured in the paper, and is so arranged that when the liquid is introduced, as many experiments as may be desired may be tried, and the pressure and temperature, as well as the atmosphere in which the experiment is conducted, may be varied, while the thermometer indicating the temperature is at the mean point of the system. The author gives a curve for water from 0° to 100°, the differences of rate being smaller as the temperature rises. Various salts are then examined, being dissolved to form ‘“‘ normal” solutions; but as the solubility of some salts is too low for such solu- tions, fhe effect of the amount of salts dissolved is determined. This is found to be directly proportional to the amount of salt in solution. Values for many salts in solution are then given, each number being the mean of ten experiments, and the probable error of the mean is calculated in each case. The conclusions arrived at are these. The rate of flow does not depend on any of the “mechanical” features of the salt, such as erystalline form, specific volume, solubility, &e.; but upon the mass of the elements forming the substance and the amount of energy expended in its formation. Each element has a value of its own, which is contirued in all its compounds. Thus all the salts of potassium and sodium formed by the same acids have a constant diffe- rence. In hke manner each metalloid and acid radicle has a value which is continued in all its combinations. Then the greater the com- bining value of an element the quicker is its microrheosis; thus potassium has a higher rate than sodium, barium than strontium, strontium than calcium, and so on. The microrheosis also varies with the amount of energy in the compound; thus nitrates stand highest, as they contain most energy; then chlorides; and, lastly, sulphates, which are exhausted compounds. The instrument, bringing to light as it does the fundamental rela- tions of combining weight and energy in chemical action, will be of the utmost importance in chemical physics, as by its use, not only will the amount of energy evolved in reactions be determined, but the mass combined ; or, in other words, the chemical equivah of the elements involved will be found. 1879.] Limestone as an Index of Geological Time. 281 V. “Limestone as an Index of Geological Time.” By T. ~ MeLLARD READE, C.E., F.G.S., F.R.I.B.A. Communicated by A. C. Ramsay, D.C.L., F.R.S., Director-General of the Geological Survey of the United Kingdom. Received December 24, 1878. (Abstract. ) The geological history of the globe is written only in its sedi- mentary strata, but if we trace its history backwards, unless we assume absolute uniformity, we arrive at a time when the first sedi- ments resulted from the degradation of the original crust of the globe. There is no known rock to which a geologist could point and say “ that is the material from which all sedimentary rocks have been derived,” but analogy leads us to suppose that if the earth had an igneous origin, the original materials upon which the elements first began to work were of the nature of granite or basalt. From a variety of considerations drawn from borings, mines, faults, natural gorges and proved thicknesses of the strata of certain moun- tain chains, the author arrives at the conclusion that the sedimentary erust of the earth is at least of an average actual thickness of one mile, and infers from the proportionate amount of carbonates and sulphates of lime to materials in suspension in various river waters flowing from a variety of formations, that one-tenth of the thickness of this crust is calcareous. Limestone rocks have been, geology tells us, in process of formation from the earliest known ages, but the extensive series of analyses of water made by Dr. Frankland for the Rivers Pollution Commission, shows that the later strata in Great Britain are much more calcareous than the earlier. The same holds true of the continent of Hurope, and the balance of evidence seems in favour of the supposition that there has been on the whole a gradual progressive increase or evolu- tion of lime. The ‘‘ Challenger” soundings show that carbonate of lime in the form of tests of organisms is a general deposit character- ising the greater part of the ocean bottoms, while the materials in suspension are, excepting in the case of transport by ice, deposited within a distance of 200 miles of land. This wider distribution in space of lime, the author thinks, must also profoundly influence its distribution in time, and he shows this by example and illustration. It can also be proved to demonstration that the greater part of the ocean bottom must at one time or another VOL. XXVIII. Xx 282 Limestone as an Index of Geological Time. [Jan. 23. have been land, else the rocks of the continents would have become gradually less, instead of more, calcareous. Thus the arguments drawn from the geographical distribution of animals are reinforced by physical considerations. The author goes on to show that the area of granitic and volcanic rocks in Europe and the part of Asia between the Caspian and the Black Sea, as shown in Murchison’s map of Europe, is two-twenty- fifths (,2;) of the whole; much of this is probably remelted sediments and some of the granites the product of metamorphism. From considerations stated at length it is estimated that the area of exposures of igneous to sedimentary rocks would be for all geo- logical time liberally averaged at one-tenth (;1,) of the whole. These igneous rocks are either the original materials of the globe protruded upwards, or they are melted sediments or a mixture of the two. The only igneous rocks we know of are of the nature of granites and traps. If these rocks do not constitute the substratum of the earth, and all known rocks, igneous as well as sedimentary, are deriva- tive, either geological time is infinite, or the rock from which they are derived is, so far as we know, annihilated geologically speaking, and we have no records of it left. If we assume the latter as true, the past is immeasurable, but in order to arrive at a minimum age of the earth, the author starts from the hypothesis that the fundamental rocks were granitic and trappean. From eighteen analyses by Dr. Frankland, it is shown that the water flowing from granitic and igneous rock districts in Great Britain con- tains on an average 3°73 parts per 100,000 of sulphates and carbonates of lime. The amount of water that runs off the ground is given for several of the great continental river basins in Hurope, Asia, ‘Africa, and America. The annual depth of rain running off the granitic and | igneous rock areas, taking into consideration the greater height at which they usually lie and the possibility of greater rainfall in earlier ages, is averaged at 28 inches, aud the annual contribution of lime in solution in the forms of carbonates and sulphates at 70 tons per square mile. With these elements, and giving due weight to certain physical considerations that have been urged in limitation of the earth’s age, the author proceeds to his calculations, arriving at this result, that the elimination of the calcareons matter contained in the sedimentary crust of the earth must have occupied at least 600 millions of years. The actual time occupied in the formation of the groups of strata as divided into relative ages by Professor Ramsay, is inferred as follows :— 1879. ] Mr. J. N. Lockyer. On Chromospheric Lines. 283 Millions of years. Laurentian, Cambrian, and Silurian ....... S 200 Old Red, Carboniferous, Permian, and New Red 200 Jurassic, Wealden, Cretaceous, Eocene, M1- ocene, Pliocene, and Post-pliocene ...... 200 The concluding part cf the paper consists of answers to objections. The author contends that the facts adduced prove geological time to be enormously in excess of the limits urged by some physicists, and ample to allow on the hypothesis of evolution for all the changes which have taken place in the organic world. VI. “Preliminary Note on the Substances which produce the Chromospheric Lines.” By J. Norman Lockyer, F.R.S. Received December 24, 1878. Hitherto, when observations have been made of the lines visible in the sun’s chromosphere, by means of the method introduced by Janssen and myself in 1868, the idea has been that we witness in solar storms the ejection of vapours of metallic elements with which we are familiar from the photosphere. A preliminary discussion of the vast store of observations recorded by the Italian astronomers (chief among them Professor Tacchin1), Professor Young, and myself, has shown me that this view is in al] probability unsound. The lines observed are in almost all cases what I have elsewhere termed and described as basic lines; of these I only need for the present refer to the following :— b; ascribed by Angstrom and Kirchoff to iron and nickel. by i Angstrom to magnesium and iron. 5268 by Angstrém to cobalt and iron. 5269 ss JST = aa Be tr < SN & s Hz. 4 ae a NaS Se ~ \ Sg Se Sen SS 8 ai iS Sor eels 3 8 t Koy ‘ ge IN Sais Ns SSN SONS GN 1S ox ig. te OS ER SEN Ra Res * AS AN Se as tS ss) BSR eis SR RS i eee ee le Sis te ee i qag7F= =. aH EF 2 co Fig en SOC. Vai Dy Wine LUSTRE Seem a asi afesaiG ro iQ Hi et) ie a AT Td K\ TUT col Th c & WO OF) OC LEIILETUS. L_ Bell crank: lever. B _ Tension screw. C Carlow discs A. — Sensitive strip. B._ Tension screw- 1._ Insulated pulley L._ Lever. D._ Datum pencil P. _ Movable pencil. C.— Clockwork. R. _ Friction rollers. sie 9: | Presents. 297 aR ! WD / Sy 1 | S and (C07) =(1" —T-T + T)2=(T"—T)5, but for small differences of C’’ and C’ we may put (C'2—C”) =20"(C’—C’'), that is to say, small variations of current will be proportional to the variation in the temperature of the strip. In order to facilitate the process of determining the value of a diagram in webers or other units of current, it is only necessary, if the variations are not excessive, to average the ordinates, and to determine their value by equation (1), or from a table prepared for that purpose. The error committed in taking the average ordinate instead of the absolute ordinates, when the current varies between small limits, is evidently small, the variation of the ordinates above their mean value averaging the variations below the same. 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Report of the Meteorological Council to the Royal Society for the period of ten months ending 31st March, 1878. 8vo The Office. 1879.] Presents. 303 Reports, &c. (continued). Rome :—Triplice Omaggio alla Santita di Papa Pio IX, nel suo giubileo episcopale offerto dalle tre Romane Accademie Ponti- ficia di Archeclogia, Insigne delle Belle Arti, Pontificia de’ Nuovi Lincei. Scienze. 4to. Roma 1877. The Accademia Pontificia de’ Nuovi Lincet. Arya Bhatta. The Hlements of Plane Geometry in 48 propositions, from the Sanscrit text, edited on the principle of Euclid, by Jasoda Nandan Sircar. 12mo. Calcutta 1878. The Editor. Brongniart (Ch.) Note sur un nouveau genre d’Orthoptere fossile de la famille des Phasmiens. 8vo. Paris. Note rectificative sur quelques Dipteres tertiaires. 8vo. Lille 1878. The Author. Fayrer (Sir Joseph) F.R.S. On the Bael Fruit and its Medicinal Properties and Uses. 12mo. London 1878. The Author. Hooker (Sir J. D.), F.R.S. The Flora of British India. Part 5. 8vo. London 1878. The India Office. Lubbock (Sir John), F.R.S. Pre-historic Times, as illustrated by Ancient Remains and the Manners and Customs of Modern Savages. Fourth edition. 8vo. London 1878. The Author. Matton (L. P.) Quadrature du Cercle, son existence prouvée. 4to. Iyon 1878. Polysection et Polysectrices. 4to. 1878. The Author. Mourek (V. H.) A Dictionary of the English and Bohemian Languages. 12mo. Prague 1879. The Author. Roscoe (H. H.), F.R.S., and C. Schorlemmer, F.R.S. #42) and ff 2) are zero when — is zero, and unity when — is infinite. s s s = Oy All these functions varying continuously between the limits here ascribed. Also— X; depends on the nature of the surface of the tube, but not upon the nature of the gas, while A, and A3; may depend both upon the gas and the surface. From this equation, which is the general equation of transpiration. the experimental results, both with regard to thermal transpiration and transpiration under pressure, are deduced. Impulsion. In dealing with the second case, that in which the isothermal] surfaces are curved, the three conditions—steady density, momentum, and energy—are all of them important. These conditions reduce to an equation between the motions of the gas the variation in the absolute temperature and the variation in the pressure, with coefficients which involve the ratio of the mean range to the dimensions of the radu of curvature of the surfaces. The equation corresponds to the equation of transpiration, and as applied to the casein which heat is being conducted through a gas which is constrained to remain at rest, the equation beeomes— P ~ 7 dx M, : : —all or taking S= Varo, ale pep CgetaME dP =e Pe eee (i p—P. being the excess of pressure in the direction of, and due to, the variation of temperature. In the abstract of a paper read in April last, Professor Maxwell gives an equation which, transformed into my symbols is— Pp a dz which only differs from mine in the coefficient —3. As Professor Maxwell indicates that he has obtained his result without taking account of the tangential stresses, this difference is not a matter of surprise. Besides the broad lines of the investigation which have been men- tioned in this abstract, there are many minor points of which it is 1879.] Properties of Matter in the Gaseous State. - 8l9 impossible to convey any adequate idea without going fully into the subject. Some idea of the scope of the investigation may be gathered from the last section in the paper, which is accordingly introduced here. Section XITI.— Summary and Conclusion. Article 125. The several steps of the investigation which have been described may be enumerated as follows :— (1.) The primary step from which all the rest may be said to follow is the method of obtaining the equations of motion so as to take into account not only the normal stresses which result from the mean motion of the molecules at a point, but also the norma! and tangential stresses which result from a variation in the condition of the gas (assumed to be molecular). This method is given in Sections VI, WIT and VIII. (2.) The method of adapting these equations to the case of tran- spiration through tubes and porous plates is given in Section IX. The equations of steady motion are reduced to a general equation expressing the relation between the rate of transpiration, the variation of pressure, the variation of temperature, the condition of the gas, and the lateral dimensions of the tube. In Section X is shown the manner in which were revealed the pro- bable existence (1) of the phenomena of thermal transposition, and (2) the law of correspondence between all the results of trauspiration with different plates, so long as the density of the gas is inversely propor- tional to the linear lateral dimensions of the passages through the plates; from which revelations originated the idea of making the ex- periment on thermal transpiration and transpiration under pressure. (3.) It is also shown in Section X that the phenomena of transpi- ration resulting from a variation in the molecular constitution of the gas (investigated by Graham) are also to be deduced from the equation of transpiration. (4.) The method of adapting the equations of motion to the case of impulsion is given in Section XI. In Section XII is shown how it first became apparent that the ex- tremely low pressures at which alone the phenomena of the radiometer had been obtained were consequent on the comparatively large size of the vanes, and that by diminishing the size of the vanes similar results might be obtained at higher pressures, whence followed the idea of using the fibre of silk and the spider-line in place of the plate vanes. (5.) In Section XII it is also shown that while the phenomena of the radiometer result from the communication of heat from a surface to a gas, as explained in my former paper, these phenomena also depend on the divergence of the lines of flow, whence it is shown that all the peculiar facts that have been observed may be explained. VOL. XXVIII. es % 320 Prof. QO. Reynolds on certain Dimensional _ [Feb. 6, (6.) Seetion II, Part I, contains a description of the experiments undertaken to verify the revelations of Section X respecting thermal transpiration, whieh experiments establish not only the existence of the phenomena, but also an exact correspondence between the results for the different plates at corresponding densities of the gas. (7.) Section III contains a description of the experiments on trans- piration under pressure undertaken to verify the revelations of Sec- tion X with respect to the correspondence between the results to be obtained with plates of different coarseness at certain corresponding densities of gas, which experiments proved not only the existence of this correspondence, but also that the ratio of the corresponding densities in these experiments is the same as the ratio of the corre- sponding densities with the same plates in the case of thermal trans- piration—a fact which proves that the ratio depends entirely on the plates. (8.) Section TV contains a description of the experiments with the fibre of silk, and with the spider-line undertaken to verify the reve- lations of Section XII, from which experiments it appears that, with these small surfaces, phenomena of impulsicn, similar to those of the radiometer, occur at pressure but little less than that of the atmosphere. Conclusion. Article 126. As regards transpiration and impulsion, the investiga- tion appears to be complete; most, if not all, the phenomena pre- viously known have been shown to be such as must result from the tangential and normal stresses consequent on a varying condition of a molecularly constituted gas; while the previously unsuspected phe- nomena to which it was found that a variation in the condition of gas must give rise, have been found to exist. The results of the investigation lead to certain general conclusions which lie outside the immediate object for which it was undertaken; the most important of these, namely, that gas is not a continuous plenum, has already been noticed in Article 5, Part I. The Dimensional Properties of Gas. Article 127. The experimental results considered by themselves bring to light the dependence of a class of phenomena on the relations between the density of the gas and the dimensions of the objects owing to the presence of which the phenomena occur. As long as the density of the gas is inversely proportional to the coarseness of the plates the transpiration results correspond; and in the same way, although not so fully investigated, corresponding phenomena of im- pulsion are obtained as long as the density of the gas in inversely proportional to the linear size of the objects exposed to its action ; > . 1879.] Properties of Matter in the Gaseous State. 321 in fact, the same correspondence is found with all the phenomena investigated. We may examine this result in various ways, but in whichever way we look at it, it can have but one meaning. If ina gas we had to do with a continuous plenum, such that any portion must possess the same properties as the whole, we should only find the same properties, however smal! might be the quantity of gas operated upon. Hence, in the fact that we find properties of a gas depending on the size of the space in which it is enclosed, and on the quantity of gas enclosed in this space, we have proof that gas is not continuous, or, in other words, that gas possesses a dimensional structure. In virtue of their depending on this dimensional structure, and having afforded a proof thereof, I propose to call the general pro- perties of a gas on which the phenomena of transpiration and impul- sion depend, the Dimensional Properties of Gas. This name is also indicative of the nature of these properties as deduced from the molecular theory ; for by this it appears that these properties depend on the mean range, a linear quantity which, ceteris paribus, depends on the distance between the molecules. In forming a conception of a molecular constitution of gas, there is no difficulty in realizing that there must exist such dimensional pro- perties; there is, perhaps, greater difficulty in conceiving molecules so minute and so numerous that in the resulting phenomena all evidence of the individual action is lost; but the real difficulty is to conceive such a range of observational power as shall embrace, on the one hand, a sufficient number of molecuies for their individualities to be entirely lost, while, on the other hand, it can be so far localized as regards time and space, that, if not the action of individuals, the action of certain groups of individuals, becomes distinguishable from the action of the entire mass. Yet this is what we have in the phe- nomena of transpiration and impulsion. Although the results of the dimensional properties of gas are so minute that it has required our utmost powers to detect them, it does not follow that the actions which they reveal are of philosophical im- portance only; the actions only become considerable within extremely small spaces, but then the work of construction in the animal and vegetable worlds, and the work of destruction in the mineral world, are carried on within such spaces. The varying action of the sun must be to cause alternate inspiration and expiration, promoting continual change of air within the interstices of the soil as well as within the tissue of plants. What may be the effect of such changes we do not know, but the changes go on; and we may fairly assume that, in the processes of nature, the dimensional properties of gases play no unimportant part. AN pe 322 Dr. A. Smith. Absorption of Gases by Charcoal. [Feb. 6, II. “ Absorption of Gases by Charcoal. Part Il. On a new Series of Equivalents or Molecules.” By R. ANGUS SMITH, ~Ph.D., F.R.S. Received January 30, 1879. (Abstract. ) In the ‘“‘ Transactions of the British Association,’’ 1868, Norwich, on page 64 of the ‘‘ Abstracts,’ there is a preliminary notice of an in- vestigation into the amount of certain gases absorbed by charcoal. I made the inquiry from a belief previously expressed in a paper of which an abstract is in the ‘‘ Proceedings of the Royal Society,” page 425, for 1863. I said in that paper that the action of the gas and charcoal was on the border line between physics and chemistry, and that chemical phenomena were an extension of the physical; also that the gases were absorbed by charcoal in whole volumes, the exceptions in the numbers being supposed to be mistakes. The results given were :— EL yEOREN ~ foaat reas ce Reese ne eee 1 Oxy PCW esters ceceed ce te ae ene 799 CacvonmCOxile: sc... ce cee oe eee ; 6°03 Carlonic acid’ * sos Soca. eee tee oa per © tae iMarsh=eas sos fs.sss ss sss ot eee eee 10°01 INGLrOuS Oxde .c. 5 daca ee ces rete PA 12°90 Sulphurous’acid.. 5: -1.225.es ss cscs ; Sowa rnrOmen fy taniete = alee seam a. Sybase 427 It was remarked that the number for nitrogen was probably too low; I had some belief that the charcoal retained a certain amount which I had not been able to estimate. . For common air, the number 40°065 crept into the paper or abstract instead of the quotient 7:06. I considered the numbers very remarkable, but was afraid that they would be of little interest unless they could be brought more easily under the eyes of others; my experiments were somewhat laborious; the exact numbers were seldom approached by the single analysis, but were wholly the result of a series of irregular averages and apparently irregular experiments. The cause of this was clear, as I believed, namely, the irregular character of the charcoal with which I had to deal. The experiments which I had published were forgotten, I suppose, by most men, but the late Professor Graham told me that he had repeated them with the same results which I had given. I might have considered this sufficient, but waited for time to make a still more elaborate investigation of the subject, and to — take special care with oxygen, in the belief that, the rule being found, 1879.] Dr. A. Smith. Absorption of Gases by Charcoal. 323 the rest of the inquiry would be easy ; this was extended to nitrogen, but not by so many experiments as with oxygen. I am now assured of a sound foundation for inquiries, which must take their beginning from the results here given. It is found that charcoal absorbs gases in definite volumes, the physical action resembling the chemical. Calling the volume of hydrogen absorbed 1, the volume of oxygen absorbed is 8. That is, whilst hydrogen unites with eight times its weight of oxygen to constitute water, charcoal absorbs eight times more oxygen by volume than it absorbs hydrogen. No relation by volume has been hitherto found the same as the relation by weight. The specific gravity of oxygen being 16 times greater than hydro- gen, charcoal absorbs 8 times 16, or 128 times more oxygen by weight than it does hydrogen. This is equal to the specific gravity of oxygen 2 squared and divided by two 2 , or it is the atomic weight and specific gravity multiplied into each other, 16 x 16, and divided by two 290198, 2 Nitrogen was expected to act in a similar way, but it refused. The average number of the latest inquiry is 4°52, but the difficulty of removing all the nitrogen from charcoal is great, and I suppose the correct number to be 4°66. Taking this one as the weight absorbed, 2 14x 4°66=65°3, or it is = Oxygen is a dyad; nitrogen a triad. We have then carbonic acid not divided, but simply 22 squared =484. Time is required for full speculation, but the chemist must be sur- prised at the following :— Saroommeroxtde es eke. ots 6 volumes. @aroomeacia, CO, s.92.. 605. 6+16 A = 22 Mlemsitecise lg 6 soc ase 6 oe, 2s 6+4 te ==ili() Protoxide of nitrogen, NO...... 8+4°66 (N) (49) 12-466. These four results belong to the early group not corroborated lately, but so remarkably carrying out the principle of volume in this union giving numbers the same as those of weight in chemical: union, that they scarcely require to be delayed. Iam not willing to theorize much on the results; it is here suffi- cient to make a good beginning. We appear to have the formation of a new series of molecules made by squaring our present chemical atoms, and by certain other divisions peculiar tothe gases themselves. Or it may be that the larger molecule exists in the free gas, and chemical combination breaks it up. These new and larger. molecules may lead us to the understanding of chemical combinations in organic chemistry, 324 Dr. A. M. Marshall on the Olfactory Nerve [Feb. 13, and whenever there is union not very firm, and may also modify some of our opinions on atomic weights and the motion of gases. Of course, I cannot pretend to give the result of these results; but as we have here the building up of a molecule by volumes, so as to form an equivalent of physical combination analogous to the chemical equivalent, it is impossible to avoid seeing that it indicates the possibility of our present equivalents being made up in a similar. manner. I did not expect these numbers; but [ certainly, as my previous paper showed, had in full view a necessity for some connexion between physical and chemical phenomena more decided than we possessed. February 13, 1879. W. SPOTTISWOODEH, M.A., D.C.L., President, in the Chair. The Presents received were laid on the table and thanks ordered for them. The following Papers were read :— I. “ Note on the Development of the Olfactory Nerve and Ol- factory Organ of Vertebrates.” By A. MILNES MARSHALL, M.A., D.Sc. Fellow of St. John’s College, Cambridge. Communicated by W. 8. Savory, F.R.S., Surgeon to and Lecturer on Surgery at St. Bartholomew’s Hospital. Re- ceived January 30, 1879. In the course of an investigation into the development of the cranial nerves of the chick, certain facts came to light indicating that the olfactory nerve, instead of being, as usually described, a structure differing totally in its mode of origin from all the other nerves in the body, in reality ‘‘ exactly corresponds in mode of development and in appearance with the other cranial nerves, and with the posterior roots of the spinal nerves.”’* The present paper contains the results of further investigations on this point; it deals also with some features in the development of the vertebrate olfactory organ; and with certain questions of a more general nature affected by the conclusions arrived at. * “Proc. Roy. Soc.,” vol. xxvi, p. 50, and “ Quarterly Journal of Microscopical Science,’ January, 1878, pp. 17-23. 1879.] and Olfactory Organ of Vertebrates. 325 The Development of the Olfactory Nerve. ~ For the sake of clearness the more important conclusions are stated in the form of propositions :— a. The olfactory nerves do not arise from the cerebral hemispheres, but from the single unpaired forebrain. ) In chick embryos of about the fiftieth hour, or a little older, the olfactory nerves can be clearly recognized arising from the upper part of the sides of the forebrain. At this stage there is no trace whatever of the cerebral hemispheres. The olfactory nerves then come into existence before the cerebral hemispheres, and therefore cannot be derived from them. The hemispheres are developed in the chick as lateral outgrowths from the upper part of the forebrain; at first the olfactory nerves have no connexion with them, beyond that of close proximity ; but very soon the hemispheres, by their rapid growth forwards, drive the nerves down to the base of the brain, and so make the nerves appear to arise from their under and anterior part. This account is confirmed in all points by observations on duck embryos, which show clearly that the connexion of the olfactory nerves with the cerebral hemispheres is not of a primary but of a secondary or adaptative nature. In the dogfish (Scylliwm) the forebrain is, as has been already shown by Balfour,* single and unpaired up to stage O, presenting till then no trace whatever of a division into cerebral hemispheres : the olfactory nerves are, however, well developed structures by stage M; at which period they can be seen, in transverse sections through the anterior part of the head, arising from the upper part of the sides of the forebrain and running downwards to the olfactory pits. The nerves can be recognized, though with less distinctness, at still earlier stages. The olfactory nerves of the salmon and of the trout can, in a similar manner, be identified before the cerebral hemispheres have come into existence; and the same statement applies to the axolotl. b. There is no trace of an olfactory lobe in the early stages of develop- ment of the olfactory nerve. Since the olfactory lobes are commonly described as “hollow out- growths of the cerebral hemispheres,” and the olfactory nerves have just been shown to arise quite independently of the cerebral hem1- spheres, this second proposition is in reality already proved by the first. However, as the existence of olfactory lobes has been supposed to separate the olfactory from the other cranial nerves, it becomes necessary to investigate carefully the time and conditions of their appearance. _ In the chick the olfactory nerve is in its early stages solid, and * “ Hlasmobranch Fishes,” p. 178, 326 Dr. A. M. Marshall on the Olfactory Nerve [Feb. 18, from a histological point of view differs in no appreciable respect from the other cranial nerves at corresponding stages of their develop- ment. At the end of the sixth day of incubation the nerve, which is now of some length, has acquired its secondary connexion with the cerebral hemisphere in the manner described above; yet the nerve is still solid along its whole length, and presents no trace whatever of an olfactory lobe, or hollow outgrowth from the brain. By the end of the seventh day a very small conical pit is visible in the wall of the cerebral hemisphere at the point of origin of the olfactory nerve. This pit, which is the earliest rudiment of the olfactory lobe, is formed almost entirely at the expense of the inner wall of the hemisphere, so that there is hardly any corresponding projection on the outside of the brain. The development of the olfactory lobe in the dogfish closely resembles that in the chick: at stage M there is no trace whatever of © a lobe, though the olfactory nerves are large and conspicuous struc- tures. Ata stage a little younger than Balfour’s stage O, the first rudiment of an olfactory lobe appears, as a slight lateral bulging of the side of the forebrain, at the point of origin of the olfactory nerve: this increases rapidly, much more so indeed than the nerve itself ; by stage O it is a tolerably prominent structure, and in the later stages it becomes considerably larger than the nerve proper.* Stage O in the development of a dogfish embryo corresponds to about the sixth day in the chick, so that there is a close agreement in time as well as in mode of development of the olfactory lobe in these two types. In the dogfish, however, the olfactory lobes appear before the cerebral hemispheres are differentiated, and consequently arise ‘from the forebrain ; while in the chick the hemispheres are developed rather earlier, and the olfactory lobes arise as direct outgrowths from them, and not from the original forebrain. In the salmon and trout, from the earliest period at which the existence of an olfactory nerve can be recognized up to the time of hatching, and indeed for some little time afterwards, there is no trace of an olfactory lobe. The existence of an olfactory nerve without any trace of an olfactery lobe has also been established in the earlier embryonic stages of the axolotl, of the common frog, and of the green lizard. The olfactory nerve of an adult vertebrate is commonly described as consisting of three parts, a proximal element or olfactory tract, an intermediate olfactory bulb, and a distal olfactory nerve proper, the two former of these corresponding to the olfactory lobe or vesicle of the embryo. From the descriptions given above it would appear that the * Cf. Balfour, op. cit., p. 178, and Plate 15, figs. 2 and 8a. Balfour has not ob- served the olfactory nerves earlier than stage O, and therefore describes them as outgrowths from the olfactory lobes. 1879.] and Olfactory Organ of Vertebrates. 327 third of these elements—the olfactory nerve proper—is the earliest to be developed, and that the olfactory tract and bulb, when present at all, do not appear till an exceedingly late period of development— a period so late indeed that their ultimate presence affords no ground whatever for separating the olfactory from the other cranial nerves. c. The olfactory nerve is a primary nerve, comparable to the segmental cranial nerves. Certain of the cranial nerves, ¢.g., the facial and glossopharyngeal, have long been recognized as possessing segmental value. These seg- mental nerves in the early stages of their development possess certain characters in common, which serve to distinguish them sharply from other nerves or branches of nerves; of these characters the following are the most important :—(1) They appear very early; (2) they arise (at least in the chick) from the neural ridge on the mid-dersal surface of the brain; (3) shortly after their appearance their roots undergo a shifting downward of their points of attachment, so that they no longer arise from the dorsal surface, but from the sides of the brain; (4) they present, at least in their early stages, ganglionic enlargements on, or close to, their roots of origin ; (5) their course is at right angles to the longitudinal axis of the head; (6) and, finally, they have very definite relations to the segments as indicated by the visceral clefts, each nerve supplying the two sides of a cleft. In all these points the olfactory nerve agrees very closely with the segmental nerves :—(1) It appears very early in all the types examined, and in the chick it seems to be one of the very first nerves in the body to be developed; (2) there is also strong reason for thinking that, in the chick, the olfactory nerve is developed from the neural ridge ;* (3) its point of attachment to the brain undergoes a shifting of pre- cisely similar nature to that presented by the segmental nerves; (4) its direction is at right angles to the longitudinal axis of the head, so that were the cranial flexure to be corrected, and the head straight- ened out, the course of the olfactory nerve would be parallel to that of the segmental nerves; (5) it possesses a ganglionic enlargement at its point of origin from the brain; (6) and, finally, an attempt will be made in the second part of this paper to show that it supplies the two sides of a visceral cleft. Since, then, the olfactory nerves do not differ embryologically in any material respect from the segmental cranial nerves, they must be regarded as the first or most anterior pair of true segmental cranial nerves. The Development of the Olfactory Organ. This will, in the absence of figures, be treated very briefly; those * For a discussion of this point, wde “ Quart. Journ. Micro. Science,” January, 1878, pp. 18, 19. —— 328 On the Olfactory Nerve, §c., of Vertebrates. [Feb. 13, points only being noticed which are of special interest in connexion with the conclusions arrived at in the preceding part of the paper. The olfactory pits appear at almost the same time as the visceral clefts; or, to speak more accurately, they first become conspicuous objects at, or very shortly after, the time when the anterior visceral clefts become open to the exterior. This occurs about stage K in the dogfish, and about the fiftieth hour in the chick. In their early stages the olfactory pits present a striking resem- blance to the visceral clefts in position, shape, size, and general rela- tions; their external apertures elongate and become slit-like, and the direction of the slit, like that of the visceral clefts, is at right angles to the longitudinal axis of the head. These facts are best illustrated by the study of whole embryos, and of longitudinal vertical sections.* They come out with great clearness in all the types of vertebrates examined, but with especial distinctness in the axolotl and salmon. The development of the Schneiderian folds presents several points of great interest, which can be most favourably studied in the Hlasmo- branchs. Attention has already been directed by Balfour} to the very early appearance of these folds. The important point, so far as the present question is concerned, is that these Schneiderian folds appear at the same time as, or very shortly after, the first rudiments of the gills. In addition to this identity in time, there is also identity in structure ; in both cases development consists in the formation of a series of equal, closely apposed folds, mainly epithelial, but involving the underlying mesoblast to a certain extent. These folds are in the two cases—gills and Schneiderian folds—of the same width, the same distance apart, have epithelium of the same thickness and same histological character, involve the mesoblast to exactly the same extent, and in exactly the same manner; in a word, are structurally identical. In the later stages the Schneiderian folds, like the gills, receive a very abundant supply of blood-vessels; and the relations of these vessels to the folds, which are very peculiar and characteristic, are identical in the two cases. Hven in the adult Hlasmobranch there is a remarkable histological resemblance between the gills and the nose, The facts above recorded concerning the development of the olfactory nerve and olfactory organ point towards the same conclusions as to morphology of these structures, viz., that the olfactory organ is the visceral cleft; that the olfactory nerve is the segmental nerve supply- ing that cleft in a manner precisely similar to that in which the hinder * For figures of whole embryos illustrating the points referred to, vide Parker, “On the Structure and Development of the Skull in Sharks and Skates,” “Trans. Zool. Soc.,” vol. x, part iv, 1878, Pl. 25, fig. 1; Pl. 39, figs. 1 and 2; Pl. 40, fig. 1 and Balfour, op. cit., Pl. 7, Stage L. + Op. cit., p. 184, and Pl. 44. fig. 14. Maga) | On the Skull and ite Nerves in the Green Turile. 329 clefts are supplied by their respective nerves; and that the Schneiderian folds are gills.* These conclusions, if accepted, will considerably simplify our con- ception of the segmentation of the vertebrate head. As there are no nerves or clefts in front of the olfactory segment, the olfactory nerve must be taken as the most anterior nerve, and the nose as the most anterior cleft. The next cleft is that in front of the maxillo-palatine arch, of which a part probably persists in the adult as the lachrymal duct: the segmental nerve corresponding to this cleft is the third, or oculomotor nerve. Next comes the mouth cleft, supplied by the ji/th, or trigeminal, nerve ; and then in succession the clefts supplied by the facial, glossopharyngeal, and pneumogastric nerves. This view of the constitution of the vertebrate head is found to accord well with the later researches of Professor Parker on the morphology of the skeletal elements of the head. Some at least of the labial cartilages will probably prove, on this view, to be homologues of the extrabranchials, a comparison that has already been made by Professor Parker.t If the olfactory organs are visceral clefts, they must originally have - communicated with the mouth cavity. Indications of a former con- nexion of this kind are by no means wanting; thus in salmon embryos the alimentary canal extends forwards, so as to underlie the nasal sacs : as development proceeds, this anterior prolongation of the mouth cavity gradually shrinks; it persists for a short time as a pair of cecal diverticula, which ultimately disappear altogether. In conclusion, it may be noted that the Schneiderian folds afford an instance, on the theory here maintained, of structures originally hypo- blastic in nature becoming, from changed circumstances, epiblastic. Il. “On the Development of the Skull and its Nerves in the Green Turtle (Chelone midas), with Remarks on the Seg- mentation seen in the Skull of various types.” By Pro- fessor W. K. PARKER, F.R.S. Received February 3, 1879. In the first paper on the development of the skull of the Vertebrata, published in ‘‘ Phil. Trans.,” I figured and described certain modifica- tions of the skull in the embryos of the African ostrich, which have only received their explanation lately, and this has become possible through what I see in the embryos of the green turtle. For these embryos 1 am indebted to two of our Fellows, namely, * Cf. Dohrn, “ Ursprung der Wirbelthiere,” p. 23, + “Proc. Zool. Soe.,” vol. x, part iv, 1878, p. 212. 330 Mr. W. K. Parker on the Development of the [Feb. 18, Sir Wyville Thomson and Mr. H. N. Moseley; the latter (who made the collection in the Island of Ascension), sending me the smaller specimens, and the former the ripe, and nearly ripe young. Through the liberality and kindness of these gentlemen, I am put in possession of aninvaluable series of specimens, several dozens in number ; the smallest being only half an inch long measured along its curve. Sir Wyville Thomson, having accepted my offer of the memoir I am preparing on this type of reptile for the ‘‘ Challenger ”’ Series of papers, I am anxious to lay before the Royal Society some at least of the results which I have obtained ; so that there may be a connexion kept up between my papers, and this slow ingathering of results be garnered in known places, for the benefit of those who will sift and use them. I have for many years been familiar with the existence of both paired and unpaired elements in the spine and hinder part of the skull: and also with the three cartilages that build up the fore part of the chondro-cranium. | My attention, however, having been directed most to the symme- trical pro-chordal bands,—the middle and fore part of the trabeculee cranii,—the anterior azygous cartilage, although always before my eyes, has never, until lately, received the attention it deserves. In my first paper (on the skull of the ostrich tribe) I held views with regard to the trabecule which I hold now; but there has been an intermediate period in which I have fallen into, what I must now consider to be a serious error. This error lay in the placing, both by Professor Huxley and myself, of the trabecule cranii in the category of visceral arches. Both of us have known for many years that the hinder part of the trabeculee of the newt are para-chordal, and I more recently discovered that the hinder part of the basi-cranial plate is developed separately in the Amphibia. Professor Huxley restricts the term “ para-chordal ” to these hinder plates; I am satisfied that the term must have a wider application. Nevertheless, what the Selachians, and all types above the Ichthy- opsida show, satisfies me that Rathke was right in considering the trabeculee to be mere continuations of the moieties of the basal plate or “investing mass.” I quite agree with Mr. Balfour in looking upon the whole of these tracts, right and left, to be the undivided representatives of the paired © neural arches of the spinal region, where, as a rule, they are distinct from each other, and are developed between the spinal nerves, being inter-segmental. I am satisfied that dying out of the notochord in front does not affect the real nature of the pro-chordal tracts, Until I understood the development of the pituitary body. its rela- 1879. ] Skull and its Nerves in the Green Turtle. 331 tion to the notochord was considered by me to be that of direct obstruc- tion to the forward growth of that rod. I now, see, however, that this azygous structure, the true skeletal axis, which is early separated from the hypoblast, begins to starve at its fore end, béfore the pituitary body is formed. The main part of the hypoblast, as a rule, is arrested just behind the oral involution; and above that point the notochord ceases to grow. At first, as Mr. Balfour shows, this rod is hooked downwards in front, for it follows exactly the curve of the mid-brain. There is, however, at the time of its arrest, no physical obstacle to stop its growth still further forwards beneath the fore-brain, to the utmost limit of the frontal wall of the embryo. Thus the primary skeletal axis stops and shrinks by what may be calied an anticipation of the obstructing wall that will be. Here is something in morphology resembling hereditary instinct in zoology. _ The segmentation of the embryo is at first altogether that which is. seen in the somatomes, and after these have become converted into the muscle-plates a new alternating segmentation takes place, so that the short muscular bands can work and produce the vermicular con- tractions of the embryo. The tissue which becomes the vertebre is primarily marked out into serial parts in conformity with the segmental cell masses that form the muscle-plates. Very soon, however, a new segmentation takes place, and the primordial vertebre are intermediate to the muscular masses. This secondary, intercalary vertebrate segmentation is very slightly: developed in the head. For a good while in all the Vertebrates, and permanently in some, the mesoblastic sheath of the notochord becomes a continuous carti- lage; in all but the lower forms this undergoes segmentation to form the ‘‘ bodies” of the vertebree. In the head, as a rule, this second sheath of the notochord is but little developed, and has a very slight degree of separateness from the investing paired cartilages—para-chordals, and hinder part of the tra- beculee. In the Selachians, however, it 1s well developed, and in them the distinction between head and body by means of the occipito-atlantal articulation is /ate; in some Batrachians, notably in the huge tadpoles of Pseudis paradoxa, before the limbs are grown, this cartilaginous sheath of the notochord is large and thick. The distinction between the hind and fore parts of the skull is greater by far than the distinction between the vertebral column and the hind part of the head. 332 Mr. W. K. Parker on the Development of the [Feb. 13, For this latter region has, in common with the spine, the notochord, its mesoblastic sheath, paired neural and hemal elements, besides a hypoblastic lining to the digestive tube beneath. Moreover, there is a great tendency to produce vertebree in the hind part of the head in some Vertebrata; in several of the Urodelous Am- phibia there are three rudimentary vertebree in front of the “atlas.” Thus the scant growth of the hypoblast in the cephalic region of the blastoderm, would appear to be one of the causes of the extreme modification of the head as compared with the spinal column.* We shall have made a great stroke in embryology when we have explained the peculiar behaviour of the epiblastic covering of the fore- part of the head. | There, the oral involution, which is formed from epiblast, turns inwards and upwards into the fore-part of the hollow under the mid- brain, and grafts itself upon the back of the down-turned fore-brain, itself of epiblastic origin; thus the pituitary body is formed. In all available interspaces the mesoblast of the fore half of the head grows in and forms the supporting structures, and the vascular supply. But now there arises this question—are the mesoblastic structures of the cranium in the pro-chordal region perfectly homologous with those in the pera-chordal, whether cephalic or spinal P In endeavouring to answer this question, I must return to the point at which I started, where it was mentioned that there existed an un- paired pro-chordal cartilage between the symmetrical trabecule. This, in the fore-part of the chondro-cranium, is a familiar part— pre-nasal rostrum (‘‘Ostrich’s Skull,” Plate 7, p, n); its largest development is in the skate, saw-fish, and whale. | But the perpendicular ethmoid and septum nasi are, in reality, other parts of the same azygous cartilage (see “ Frog’s Skull,” Plate 6, figs. 9, 10); in the Batrachia I have studied the development of this median part in a large number, both of individuals and species. But its real character is best seen in my second and third stages of the embryos of Chelone midas ; these measured along their curves are respectively two-thirds of an inch and one inch and a quarter in length. In the younger of these the trabecule are like those of the frog and Selachian, but they stop short and end in a somewhat out-turned “cornu” behind the nasal sacs; they are flat in front and rounded behind. * Since the above was written, Dr. Milnes Marshall has shown me that in the embryo of the salmon the hypoblast, a¢ first, runs forwards to the nasal sacs, and ends in a blind cavity behind the frontal wall in the fore part of the palate. One of my own figures shows this (“Salmon’s Skull,’ Plate 2, fig. 10); I noticed and figured this upper pre-oral recess, but could not interpret its meaning. 1879.] Skull and its Nerves in the Green Turtle. 333 Between these there is another (azygous) rod; this passes between the trabecule behind, it lies on a lower plane, and ends where the front of the pituitary body will be, for this part is only forming as yet. In front this rounded rod runs forwards to the anterior wall of the head; not so the trabecule, for they, unlike what is seen in the Batrachia, are behind the nasal sacs, and never pass far into that region. In the frog, and his congeners, they form a broad floor to the nasal labyrinth. At any earlier stage than this the notochord with at least a film of mesoblast, ensheathing the intrinsic sheath, might have stretched itself to the point where this pre-pituitary rod ends behind ; but it took an upward course, and, following the curve of the mid-brain, turned down again, and then stopped short. I cannot see what other explanation of this solid rod can be given than that it is the true homologue of the mesoblastic cartilaginous sheath of the notochord ; it is solid because it has nothing to enclose. Mr. Balfour is quite right in saying that the mesocephalic flexure is only apparently recovered from; the head, indeed, has its axis per- manently shortened by this bend of the mid-brain on itself. Indeed, the skull is shortened by this, as a dress is shortened by having a “tuck” taken up in it; or as a river shortens itself when it cuts out a new channel at the base of a sharp bend. The “ post-pituitary wall ”’ lies in the axis of the arched space formed by the bend of the mid-brain on itself; it is extremely large in the embryo of the green turtle. It must be considered that the frontal wall is not the organic end of the embryo, but the upper surface of that end. The fore-brain looks directly downwards, and even a little back- wards; the olfactory nerves arise from its anterior (= superior) sur- face, and the ‘infundibulum ”’ buds out to meet the oral involution on the posterior (= inferior) surface of the fore-brain. We thus see that the true organic punctum terminale must lie between these two parts, the olfactory nerve and infundibulum, and therefore it looks downwards, and a little backwards. So when the trabeculee cranii grow to the frontal wall they in reality turn upwards, and embrace the dorsal region of the front of the head. Thus, it is evident that if we can trace the notochord to the back of the pituitary body, we have found it reaching, very nearly, the fore-end of the embryo. Now, in my third stage of Chelone midas the notochord turns round in the post-clinoid upgrowth of the basal plate, and the sheath in its descending part becomes solid, and ends behind the lobules of the rudimentary pituitary body as a tear-shaped drop or lump of car- tilage. 334 Mr. W. K. Parker on the Development of the [Feb. 13, If the head had been straight, this drop of cartilage would have reached its fore-end directly below the first nerves. I shall return to this part of the subject in the latter half of my paper. The visceral or inferior arches of the head are as diverse from the costal arches as the axial parts of the head are from those of the body. That splitting of the mesoblast, which forms the “ body-cavity,” runs- high up into the muscle-plates; but this upper part of the cavity closes again, whilst, below, the ventral wall is permanently divided into ‘“‘ splanchnopleure ” and ‘‘somatopleure.”’ I have corroborated Mr. Balfour’s account of the extension of this cavity into the head of the embryo of the Selachians by demonstrating it in the head of the embryo lizard and turtle. To me this ‘“ head cavity” appears to be the equivalent of the temporary upper part of the body cavity; this cephalic extension of the cavity is also temporary. The cells lining these cavities in the head become transformed into muscular fibres. Thus, there is a reversion of the ventral wall of the head into a generalised condition before the visceral rods are developed. In the trunk the axial skeleton* is formed inside the upper diver- ticulum of the body cavity, and therefore in the splanchnic layer; of course the costal arches pass over the permanent body cavity into the somatic layer. Mr. Balfour’s view with regard to the visceral arches and branchial pouches is, that they are all formed in a tract equivalent to the somatic layer of the body. e Yet the difference between the costal and visceral arches is very great; and the fact that there are two sets of them, external and internal, separated by a large branchial space, does not lessen the diffi- culty of harmonising these two sets of arches, the costal and the visceral. We may, however, keep the term plewral for both, and divide this ‘‘oenus”’ into two “ species ”—visceral and costal—and the visceral into two varieties, namely, external and internal. I suspect that there has been a secular differentiation of these regions, and that the order in time has been—first, ‘‘ extra-branchials ” round the huge branchial pharynx; then the trabecule as a support to the swelling neural axis; then the paired neural cartilages of the spine; after these, the intra-branchials ; then the costal arches; and, last of all, the limb-girdles and limbs. These deductions are not made at random, but by reflection upon * See Balfour, ‘‘ Elasmobranchs,” p. 133. 1879. ] Skull and tts Nerves in the Green Turtle. 33D the order of time in the appearance of these parts in the quasi-ancient stages of the early embryos of existing, but low, vertebrate types. The ventral wall of the head undergoes dehiscence in three places, on each side, in front of the tympano-eustachian, or so-called first cleft. The right and left clefts directly in front of that open freely into each other below; they form the angles of the opening mouth. Another cleft, the lacrymal, is formed in the region over which the third nerve forks; this nerve, the motor oculi, is a true segmental nerve, but is specially devoted to the eyeball. The eyeball forms for itself a nest above and in front of the mouth, and this cupped orbital space is permanently open antero-inferiorly. In the turtle, at my second stage, the maxillo-palatine fold is very large, is dilated at both ends, and pinched in the middle; in the hind part there is for a time, as I have showed in the lizard, an extension of the pleuro-peritoneal cavity. This is the only one of the head cavities which opens into its fellow of the opposite side; the presence of this cavity is as sure a sign of segmentation as the forking of a segmental nerve over the space in front of and above it. The thick front part of the visceral fold between the lacrymal and nasal clefts does not acquire a cavity. The whole of this double fold over and in front of the mouth cleft is largely aborted in the Selachians by a foregrowth of the mandibular fold; but in some sharks, as in Notidanus, and in all rays, a true palatine cartilage is developed in that part of the face which is be- tween the lacrymal and nasal clefts.* Between the lacrymal and oral clefts, and therefore between the hinder fork of the third nerve and the true anterior fork of the fifth nerve, a visceral cartilage appears in several types. In Scymnus, among the sharks, in Menopoma and Siredon, among the Urodeles, in nearly all lizards, and in the Chelonians, a separate cartilage appears in the hinder lobe of the maxillo-palatine fold, after the disappearance of the head cavity. In the lamprey, and the larvee of the Batrachia, the extreme forward * This cartilage is distinct also in all the Urodeles; and in the species of the genus Bufo, after metamorphosis, and in all the rest of the Batrachians as a very definite region of the swb-ocular arch. In the salmon, among the Teleostei, this cartilage is separately developed at first, and this is evidently the rule in the Order. In the Siluroids (Doras, Clarias) this becomes a straight rod of bone, carrying the tentacle-bearing, minute maxillary, in front, and lying over the pterygoid, and mesopterygoid behind ; with these it never unites. Tn lizards, and many birds, there is a very definite palatine cartilage which appears between the lacrymal and nasal clefts; it remains cartilaginous in the former, but in many birds (Musophaga, Dicholophus, Diomedea, &c.) acquires its own bony centre. VOL. XXVIII. 2B 336 Mr. W. K. Parker on the Development of the [Feb. 13, extension of the dorsal part of the mandibular arch suppresses the pre-oral cartilages ; in the Selachians—sharks especially—this is done by the pterygoid outgrowth of the same element. In the first case, the whole mouth is dominated by the suctorial car- tilages; in the second, the immense development of the pterygoid process of the manibular pier, antagonising the movable lower jaw, eauses the great suppression of the proper maxillo-palatine fold. Whilst I consider the trabecule to be axial, or rather newro-axial, I am very familiar with the rudiments of a visceral arch growing from their fore ends. I first saw this in metamorphosing larve, and adult, bull-frogs ; afterwards Professor Huxley found and described them in Rana tem- poria (‘‘ Encye. Brit., vol. ix, Art. Amphibia, p. 755). Since then, T have found them in many kinds of Batrachia; in some Urodeles; in the embryos of the dog-fish (Scyllwum canicula) ; in passerine birds ;. and in the Mammal. Their largest development, however, is in the ‘‘ Holocephalous ” fishes—Chimera and Callorhynchus. These three pairs of rudimentary pre-oral arches are like the first post-oral of the Mammal, non-segmented; they are sometimes. direct outgrowths of, and at others are formed separately from, the basal bar (trabecular). I cannot see that these cartilages are anything else than arrested representatives of the large, fully developed post-oral arches; they correspond, however, only with the upper or suspensorial segment. The great difference between the head and body in existing Verte- brates is shown in every part composing these two regions. Therefore, any impatient premature attempt to make a perfect har- mony between the parts that form the axial, the neural, and the hemal regions of each, will end in disappointment. Embryology must show us how true is the deep, essential, primary homology of these parts; but morphology must come in and demon- strate the great and inherited differences, slowly arising, no doubt, that are to be seen between the two regions. There is a real generic likeness between the axis, the upper and lower arches, and the overlying parts in the cranial and spinal regions ; let these be computed at their true worthin any comparison of the two categories one with another. Thus, the divided basi-neural regions of the body are comparable with the continuous basi-neural regions of the head, and the visceral arches may be likened to ribs. The “‘uncinate processes” of the ribs of certain reptiles (Hatteria and the Crocodilia), and in all birds, except Palamedea, are com- parable to the branchial “rays” of Selachians; and the overlying “‘extra-branchials”’ are not void of a true similitude to the girdles of 1879. | Skull and its Nerves in the Green Turtle. 307 the outgrowing limbs. I suspect, indeed, that they are their true serial homologues. In this latter case, the splitting of the mesoblasts into several strata in the throat, on the one hand, and in the thoracic and pelvic regions of the body, on the other, are strictly comparable morphological changes. I strongly suspect that if we could bridge over the gulf between the lancelet and ‘the lamprey, we should find in these “ connecting links ” that the head was not a mere repetition of the body. Somatomes we should find ; but the intercalary skeletal parts would be found, I believe, to run into each other frem the first, and the hasi- neural cartilages of the head might be seen, in time, before the distinct neural arches of the spine. I must now recapitulate a little. After carefully considering the views and studying the researches of Huxley, Gegenbaur, Balfour, and Milnes Marshall, I am satisfied that, in spite of the doubling up of the basis cranii, at the time of its ereatest flexure, there are rudiments of three pre-oral arches, related tu two pre-oral clefts, namely, the lacrymal and the nasal. That the mouth is caused by the blending together of a right and left cleft is the view held (1 find) by Dr. Allen Thomson; this view, also, is held by Dr. Dohrn. (See “ Balfour’s Hlasmobranchs,” p. 15.) . The horseshoe fold of the mid-brain, the formation of the large hollow bed for the eyeball, and the special function to which the true segmental motor oculi nerve is confined, are all correlates of the special development of those wild branches of the trigeminal and facial nerves, namely, the ophthalmic and Vidian. This is tantamount to saying that the hypertrophy of the first and second vesicles of the brain, and the large size of the optic vesicles which are outgrowths from the first of these, with all the enfoldings and complications necessary to complete the eyeball have, together, dominated all the surrounding parts, causing them to do many strange things, so to speak, vicariously. Milnes Marshall finds that the olfactory nerves are solid until the seventh day of incubation in the chick; in embryos of the green turtle of the size of a horse-bean, I find the nerves still solid. When the embryos are two or three times that size, these nerves each acquire a large cavity proximally, from the fore-wall of which the branches seem to spring. The foremost of these branches spring from the top of the vesicle; they arose at first from the top of the fore-brain. Both in the chick and embryo of the turtle, the fourth nerve, as soon as it can be found, runs a course so directly athwart the first branch of the fifth as to suggest its non-segmental nature. 2B 2 338 Mr. W. K. Parker on the Development of the [Feb. 13, The sixth nerve, or abducens, certainly arises from the ventral surface of the hind-brain; this being so, it manifestly corresponds to the anterior root of a spinal nerve; and as Milnes Marshall suggests, it may belong to the trigeminal, to the facial, or to both of these nerves. Tf low forms should turn up, in which the optic nerves were truly segmental, and not direct vesicular outgrowths of the fore-brain, that would only affect the classification here suggested, by showing that our present Vertebrata have lost a segment through the extreme specialization of the optic nerves. As matters stand at present, we have, then, the nasal, lacrymal, oral, tympanic, and branchial clefts; of these we see that there are three in front of the tympanic, and there may be eight behind it. Thus we get four pre-auditory and eight post-auditory clefts, with their nerves ; if we add the twelfth (hypoglossal) of the ‘‘ Amniota,”’ we have obtained signs and proofs of thirteen cranial (segmental) nerves, all of these, except the last, forking over visceral clefts, and hedged in, all but the last, by visceral bars. The first of the bars is in front of the first or nasal cleft, the last, or thirteenth, is the hinder bar of the lamprey’s branchial basket work. Of course in this classification I do not mention, for the time, the distinction between the deep and superficial cartilages. In the lowest kind of chondro-cranium known to us, namely, that of the sucking-fish and the larvee of the Batrachia, the first post-oral arch is not only very largely developed, but is also carried forwards directly to the front of the head; it does not of itself form the skeleton of the oral opening, but carries the large cartilages that form the peculiar suctorial mouth. Hence, in the lamprey and in the Batrachia, whilst they are in the larval condition, the pre-oral visceral bars are arrested in their growth; in the adult of the latter types, when the permanent mouth is formed, then two (of the three possible) visceral arches are developed. Not only in low forms are the anterior visceral arches arrested, or even suppressed, but the visceral clefts also, in front of the mouth as well as the one immediately behind it, are often imperfectly developed, or even suppressed. The nasal cleft does not remain open inwards until we get to the Dipnoi and Amphibia, and the lacrymal cleft not until we get to the Amniota. No one has seen a first post-oral or tympanic cleft in the lamprey, and its second post-oral, discovered a few years ago by Professor Huxley (‘“‘ Proc. Roy. Soc.,” vol. xxiii, p. 129), in the larva, or Am- mocete, is very small, and apparently has no external opening. In all the Urodeles, and in the lower and more generalized Anura, 1879. ] Skull and its Nerves in the Green Turtle. 339 the first post-oral or tympanic cleft is either suppressed or forms a very slight inner pouch ; it never opens externally in the Anura. In most of the Ganoids, as in the Selachians, the first post-oral cleft persists as the spiracle, but in osseous fishes it is a very temporary structure. T have long suspected that the archaic (entomocranial) Vertebrata were often supplied with a perfect circlet of branchial filaments around their mouth. We know the first post-oral cleft to be a branchial cleft with several branchial filaments; Dr. Milnes Marshall’s researches show that the nasal folds of the embryo Selachian are developed in precisely the same manner as the external branchials of the spiracular opening. These filaments become converted into a pseudo-branchia; the natural suggestion is that the nasal folds, having the same structure, and being formed in a homologous space, are indeed nothing more, even in the adult, than a modified pseudo-branchia. Further Remarks on the basi-neural Plates of the Skull. I have latterly come back to the same view as to the meaning of the “trabecule cranii,’ as was first propounded by Rathke, namely, that they are there extensions forward of the basal plates or ‘“‘ invest- ing mass.” Professor Huxley’s term ‘‘para-chordal” is as applicable to the hind half of the trabecule, in embryos of Selachians and Amphibians, as to the pair of plates behind the trabecule, or “ para-chordals’”’ proper. Moreover, in several kinds of Urodeles, namely, (Spelerpes, Desmog- nathus, Sc.,) there is a hindmost pair of para-chordal cartilages in front of the functionally first vertebra. It behoves us, therefore, not to be led astray by mere words; I should prefer to call the paired cartilages of the notochordal region of the head basi-neural; this term would satisfy not only some of the best authors, such as Goette and Balfour, but it also expresses what I conceive to be the actual nature of the parts. These right and left tracts of cartilage that form the main part of the base or skull floor, and grow, more or less, over the overgrown neural axis, are divisible into two regions, the hind region, which is para-chordal, and the fore-part, which is pro-chordal. These essentially continuous tracts were, I suppose, developed, first, as a support to the increasing fore end of the neural axis, and from the first were not clearly divided into intercalary (inter-neural) tracts ; and moreover, as I take it, they solidified earlier than the inter-neural tracts of the spinal region. That these latter, even, were not always from the first developed 340 Mr. W. K. Parker on the Development of the [Feb. 13, into separate tracts the existing skates and rays show; as the tissue became more and more solid, it became, in relation to the action of the muscle-plates, differentiated into a paired chain of pieces of solid cartilage for the origin and insertion of the segmental muscles. The “ basi-neural” tracts of the head in existing Vertebrata are developed very differently in different types, some parts forestalling others in chondrification, and yet not similarly in all. In the Salachians (Scylliwm, Raia, Pristiurus, see “Trans. Zool. Soc.,” vol. i, Part IV, Plates 33-42) these tracts are very broad, and there are three regions made evident by the earlier or later time at which they become converted into hyaline cartilage. The middle region chondrifies first; this extends from the nasal sacs to the middle of the auditory capsules, and answers to the “‘trabecule ” without their “ cornua.” The next tract is behind the trabeculae; it does not end close behind the exit of the vagus, but runs on for a considerable distance into the spine, without any sign of segmentation. The last to solidify its embryonic, into hyaline, cartilage, is the inter- nasal; this tract is, at an early stage, narrow, for the nasal sacs are immense; afterwards these structures get much further apart, and allow of the free development of the intervening cartilage. This overshadowed, pinched tract of the skull, breaks out into three parts in front of the nasal sacs,—a pair of bilobatea, ‘“‘ cornua tra- becule,” and the azygous “ pre-nasal”’ rod. ; That rod is the fore part of the :nter-trabecular tract; 1t is but little evident between the nasal roofs, and between the eyes only forms the thinner middle part of the cranial floor. But the azygous cartilage, behind the pituitary body, forms the un- divided, secondary (mesoblastic) sheath of the notochord ; in the early embryos it runs on from the pituitary space to the end of the body: afterwards, it is segmented at the occiput, and behind that region becomes segmented (more or less) into “‘ centra.”’ Yet in the rays a large post-occipital tract 1s continuous, perma- nently; and in both rays and sharks it shows at first siqus of ex- tensive segmentation in the head, for the notochord at its fore end becomes “‘moniliform.” I find jive joints or beadings in Pristiurus, and eight in Scylliwm. In the Urodeles (‘‘ Skull of Urodeles,” Plate 22, fig. 1, ¢r), for in- stance in the axolotl-embryos at the time of hatching (my second stage), show a pair of broad para-chordal cartilages that embrace the fore half of the relatively huge notochord. These grow in front ot that rod as small rounded horns, embracing the sides of the fore-brain below. Afterwards these rods grow up to, and then between, the nasal cap- 1879.] Skull and its Nerves in the Green Turtle. 341 sules, and then spread into dilated out-turned “cornua.”’ By that time another pair of para-chordal cartilages has appeared behind the first, and in several species of Urodeles a much smaller pair behind them. I do not find more than a very delicate layer of mesoblast sheathing, the cephalic part of the notochord ; and the inter-tra- becular cartilage in front of it merely fills the interspace of the tra- beculz in the nasal region; only in Siren and Salamandra do I see a short ‘‘ pre-nasal”’ rod. In most of these types the two last-mentioned being exceptional, the para-chordal part of the trabeculz is absorbed, and only a selvege of the para-chordal, proper, remains inside the ear-capsules, and at the occipital condyle. In these types the basal cartilage does not grow up into the cavity of the mid-brain as a “ post-clinoid ” wall, but this wall is very well seen in the dog-fish (Scylliwm). In the Batrachia (‘‘Anura’”’) the trabecule embrace the apex of the notochord less, and develop their cornua sooner; the rest of the basal plate, behind, is somewhat later in its appearance. They have a continuous growth of the inter-trabecular band, which is a flat floor finishing the skull below; between the eyes, and between the nasal sacs it grows into a wall; in front, this tract fills in the angle between the trabecular cornua, and often (as in the tree-frogs) sends forth a distinct pre-nasal rod, like that of the sharks. The Anura have a slight post-clinoid wall; their skull on the whole, when finished, is intermediate between that of the Selachians and the Urodeles. Goette mentions the cartilaginous sheath of the cranial notochord in Bombinator; I find it very massive in the larve of Pseudis (when the limbs are just appearing); but, as a rule, this sheath is very thin in tadpoles. In Teleostei (‘‘ Salmon’s Skull,’’ Plates 1—8) the investing mass chondrifies first, and is relatively much larger than the trabecule: they are only sub-distinct, and soon coalesce; the trabecule grow very rapidly, so that at the time of hatching there is a very massive pro-chordal tract. By the middle of the second week after hatching the pro-chordal tracts are quite distinct from the para-chordal, and he on them obliquely. By the middle of the first summer the tracts show, as far as I can see, no sign of their separation; but in the adult salmon the trabecule only reach to the front of the pituitary space, whilst the anterior half of the para-chordal cartilage receives its bony matter from their “ prootics.”’ In the salmon the middle ethnoid is at first feebly developed, growing down, as a keel, from the ‘‘ tegmen cranii;’’ and in the adult all we see of the inter-trabecular point is a short wall between the lateral 342 Mr, W. K. Parker on the Development of the [Feb. 13, ethnoidal masses; for, further forwards, at the mid-line, there is a large cavity filled with fat.* In front the trabecule end in two short cornua, but there is no ‘‘ pro-nasal’”’ rod. In the snake (‘‘ Snake’s Skull,” Plates 27—33) the cranial part of the notochord shortens rapidly, and is invested with a very thin secondary sheath. The trabecule are manifestly merely fore-growths of the para- ehordal tracts: there is no inter-trabecular tract, and even the “septum-nasi”’ is formed by the two trabecular crests uniting with the inner edge of each nasal roof. The snake has a post-pituitary wall, which is well developed in all the “ Sauropsida.” In the high-skulled lizards the inter-trabecular cartilage appears, and largely contributes to the formation of the partition wall in the fore part of the head ; it does not, however, appear, wedging in between the trabecule below, as in the Chelonians, nor has it any pre-nasal growth in any kinds I have worked out. But the Chelonians shed most light upon these parts, and my recent work at this type has made many things clear to me that for a long time have remained unexplained. The segmentation of the pro-chordal from the para-chordal region is both secondary and temporary: it did not exist in my jirst stage, and had vanished in the fourth, namely, in embryos three-parts ripe; these, which were the size of a horse-bean (third stage), corresponded with what is seen in the adult salmon. The embryos of Struthio camelus come very close to Chelone as to the inwedged position of the inter-trabecular tract, which appears below, and makes the base of the orbital septum carinate. This is not seen in the other ‘‘ Ratite ” nor in the “ Carinatee;”’ but I find it in the ethnoidal region in the chick (‘‘ Fowl’s Skull,” Plate 81). Also in having large orbito-sphenoids the African Ostrich comes nearest to Chelone. Neither of these types, nor the other “ Ratitee,” show the segmentation of the perpendicular ethnoid from the septum nasi, which is constant in the “ Carinate,”’ and is seen to begin in Lizards. In Mammals (Pig’s Skull, Plate 28, fig. 8), the para-chordals chondrify before the pro-chordals ; the latter, however, are never sepa- rated from the former. The “ inter-trabecular”’ wall dominates in the front of the pituitary space, but the thin, flattened, vertical tra- becule diverge at a certain point to form the huge orbitosphenoids, exactly as in Chelone (Plate 33, fig. 6). The shortening of the skull by the fold of the mid-brain, and the high post-clinoid wall growing up into the hollow, are just alike in the turtle and the pig. * Dr. Milnes Marshall has shown me that the want of symmetry seen in my salmon embryos was artificially produced by the spirit; they should have been re- moved from the egg before they were preserved. S79. | Skull and its Nerves in the Green Turtle. 343: On the Organic and Actual Fore End of the Head. When the cephalic fold of the embryo is formed, the fast-growing cerebral bulbs hang over the yolk; the brain at this stage, by its own bulk and weight, hangs down like a gourd. Of necessity, this throws together parts that would be at some con- siderable distance from each other; also the organic end is not the actual end of the head, as I have mentioned before: that is formed by the mid-brain; the fore-brain, or terminal vesicle, looks downwards. and backwards. In this piece of morphology, as in studying the “receptacle of the fig-tree,” we have to distinguish between the apparent apex and the: true apex. But if organs have to be supported, the morphological force must make good that which is thrown out of gear by this special hyper- trophy of parts, and the beams and rafters must be eked out. For this heavy nodding bend of the growing brain so doubles up the undergrowths of the skeletal rudiments, that both the paired and unpaired parts are stopped very near to the retral organic apex. Also the nasal sacs and optic vesicles, attached to, or growing from, the fore-brain, are in a new position, and not, as they should be, in the old straight line. Indeed, the axis of these skeletons grows up far into the hollow bend of the mid-brain, and the notochord turns over somewhat, and then loses itself in the mesoblastic sheath, which gets very close to the organic end of the brain. | The paired tracts (para-chordals, both trabecular and_ post-tra- becular) grow up into that hollow, and there stop; their new out- growths (or eking out of the basi-neural tracts) begin again at the base of this ascending wall. Also the middle (wnpaired) part begins again directly, in Chelone, and in embryos (two-thirds ripe), in which the notochordal sheath was ossifying to form the beginning of the “ basi-occipital” and ‘‘ basi-sphenoid,” the cephalostyle passed at once from the noto- chordal sheath to embrace and ossify the “‘inter-trabecular ” bar, close below the pituitary body. That part of the basi-sphenoid which lies in front of and below the pituitary body is formed by ossification, directly from the cepha- lostyle, of the unpaired solid pro-chordal tract of mesoblast ; after- wards the bony matter spreads into the paired bars (trabecule). But that middle bar came short of the pituitary space in the earlier stages; for there the oral fold grew up to graft itself upon the fore- brain, close behind (or below, organically), the true apex or end of the: brain. . Hence we see, that if the pituitary body were formed in an wnbent (4 344 Mr. W. K. Parker on the Development of the [Feb. 18, embryo, it would be close below, and only a little behind, the fore end of the creature ; in this supposed type the notochord would be only a little behind the punctum terminate. Now the fore and mid brain have at present only yielded to embryo- logists one pair each of segmental nerves growing from their dorsal region; the hind brain is a serves of enlargements. The two great pre-aural segmental nerves (5th and 7th) by the overfolding of the brain, are enabled to send on to the front of the head their special branches, needed there, because of the specialization (for motion) of the third, and the specialization (for sensation) of the first nerve. Thus these three-branched nerves have grown in harmony with the paired and unpaired basi-neural cartilages, and there is a due exten- sion forward of cartilages to the partially straightened skull, and a due supply of nerves from behind. But in spite of all the metamorphoses of these parts, neural and skeletal, if Dr. Milnes Marshall’s observations (with which mine accurately accord) be true, then we still have two true segments in point of the cleft (oral) which is forked over by the 5th nerve. It could not be expected that the visceral arches and intervening clefts would be otherwise than greatly modified and masked in the fore part of the head, with its huge nervous centres, and highly complex organs of special sense. The larvee of the Amphibia, especially of the ‘‘ Anura,” have been very carefully studied by me, as likely to throw light upon the order of development of the cranial-facial skeleton; the lamprey, also repre- senting those larve permanently, has been the subject of much thought, as a sort of practical pattern of those larve. In these forms the ewtra-visceral skeleton of the head is much developed, and only part of the true visceral (internal arches) appear. For the mouth in these forms is terminal, and its skeleton is made up of sub-cutaneous cartilages, the serial homologues of the subcu- taneous basket-work of the large respiratory pharynx of the lamprey. In that form the only true visceral arches developed are the mandi- bular and the hyoid; a basal rudiment of the internal branchial arches exists as the ‘ lingual cartilage.” The free mandible of the lamprey is packed up, and apparently functionless, close behind the postero-superior “labial;” the quad- rate portion of the “‘ suspensorium,” is a mere point or aide, with no condyle. This suspensorium throws a fold of cartilage over the second branch of the 5th nerve and the temporal muscle; this is not the pterygoid cartilage, and is only seen in this type, in tadpoles, and in some chondrosteous Ganoids, e.g., Planirostra, as shown by Mr. Bridge. £379. | Skull and its Nerves in the Green Turtle. 345 Also the epi-hyal is in a low state of development; there is a cerato-hyal and a basi-hyal piece, growing forward below, in front of the large lingual (‘“‘basi-branchial ’’) cartilage. But there is a copious growth of external cartilage both around the terminal mouth and around the huge branchial pharynx; the cranial box is at a low state of development, and the fore part of the head shows no trace of a pre-oral arch. In tadpoles we have a very similar state of things, but there is a real ascent; the suspensorium develops a quadrate condyle, and on this the passive mandible is hinged. Round the mouth, cartilages quite like those of the lamprey, are developed, but they are smaller; and there are only four bars (pouches) in the walls of the pharynx; rudiments of four true intra- branchials also, are developed. A fifth subcutaneous cartilage appears during metamorphosis, belonging to the mandibular arch; it becomes the cartilaginous “ annulus tympanicus.” After it has appeared the ‘“‘styloid cartilage” of the lamprey (“epi-hyal”’) is, in them, slowly developed, and becomes the “‘colu- mella auris.” Also, during metamorphosis, the rudiment of a “‘ palatine”’ visceral arch appears, and in the genus Bufo becomes a large distinct pre-oral cartilage. After metamorphosis, another cartilage appears on each side, within the nasal cleft, the ‘‘ pro-rhinal.”’ My idea of the order, in time, of the skeletal elements is as fol- lows :— First. The superficial cartilages of the mouth and respiratory pharynx. Secondly. Basi-neural, and then, afterwards, going from them, visceral cartilages, in the inner layer of the walls of the mouth and throat. Thirdly. After that, selection of dermal scutes, first as scales and afterwards as splint-bones (“ parostoses’’), to supplement, for support- ing purposes, the chondro-cranium. Fourthly. A gradual arrest, and then more or less of suppression, of the chondro-cranial parts, and the increased use of subcutaneous investing bones, at times in conjunction with remnants of the old primary superficial cartilages. The development of the spine has been, I believe, a thing of later date; and the limb-girdles and limbs newest and latest of all. The brain, mouth, and throat, with coiled intestines, whose outlet is very little behind the occiput, make up all that is of any con- sequence, in such a form as the gigantic tadpole of the paradoxical frog (Pseudis); whose post-cranial segments have evidently been super-additions, developed for the sake of locomotion—to form a mere swimming organ. 346 Mr. J. E. H. Gordon on Electricity and Light. [Feb. 13, Behind the head, the segments for free motion cannot be moved by . the developing segmental muscles until an intercalary segmentation has taken place; hence the vertebral segments which come between the ‘“‘muscle-plates ’ and spinal nerves. The head, eschewing such mobility, has developed an axial box for the brain, and beneath this firm structure, the mobile and distensible mouth and throat are swung. II]. “On an Extension of the Phenomena discovered by Dr. Kerr and described by him under the title of ‘A New Relation between Electricity and Light.” By J. E. H. Gorpon, B.A., Assistant Sec. of the British Association. Communi- © cated by Professor TYNDALL, F.R.S. Received February 10, ILS) In November, 1875, Dr. Kerr announced in the “ Philosophical Magazine,” that he had discovered a new relation between electricity and light. He showed that when glass is subjected to an intense electrostatic stress, that a strain is produced which causes the glass to act like a crystal upon polarized light. On Wednesday, February 5, 1879, | was working at this experiment in the Royal Institution, and endeavouring, by means of the electric light, to project the effect on a screen, in preparation for a lecture on the next day. In the experiment as described by Dr. Kerr, and which was shown plainly on the screen, on February 6, the light is extinguished by the Nicols, and reappears when the coil is set going. In the projection experiment a patch of moderately bright white light, about 3 inches diameter, appeared on the screen when the coil was worked. The images of the points inside the glass were about 14 inches apart. On Wednesday, however, the electrostatic stress was accidentally allowed to become strong enough to perforate the glass. Immediately before perforation there occurred the go which are the subject of the present communication. First appeared a patch of orange-brown light about 6 or 7 inches diameter. This at once resolved itself into a series of four or five irregular concentric rings dark and orange-brown, the outer one being perhaps 14 inches diameter. In about two seconds more these vanished and were succeeded by a huge black cross about 3 feet across, seen on a faintly luminous ground. The arms of the cross were along ~ the planes of polarization, and therefore (the experiment being arranged according to Dr. Kerr’s directions) were at 45° to the line of stress. 1879. | On Electrical Insulation in High Vacua. 347 The glass then gave way, and all the phenomena disappeared except the extreme ends of the cross, and the discharge through the hole, where the gluss had been perforated, was alone seen. The phenomena were seen by Mr. Cottrell, by Mr. Valter (the second assistant), and by myself. A fresh glass plate was at once drilled in hopes of repeating the phenomena in the lecture next day, but owing to sparks springing round we did not succeed in perforating the glass, and therefore saw only the faint return of light described by Dr. Kerr. 7 Some more glasses have been prepared and their terminals in- sulated, and I now propose to make another attempt to repeat the new effects before the Royal Society. February 20, 1879. THE PRESIDENT in the Chair. The Presents received were laid on the table, and thanks ordered for them. The following Papers were read :— I. “On Electrical Insulation in High Vacua.” By WILLIAM CRooKES, F.R.S. Received February 6, 1879. The experiments here described were tried nearly two years ago. They were suggested by some observations | was then making on the passage of an induction current through highly exhausted tubes. The main branch of the research being likely to occupy my attention for some time, I may be unable to return to these less important off- shoots. I have ventured, therefore, to embody them in a short note for the “ Proceedings of the Royal Society.” A pair of gold leaves were mounted, as for an electroscope, in a bulb blown from English lead glass tubing. The leaves were attached to a glass stem and the lower part of the bulb was drawn out for sealing to a Sprengel pump as shown at fig. 1. A stick of ebonite excited by friction was generally used as the source of electricity, but any other source will do equally well, provided it is not too powerful. No special attention was paid to the action of electricity on the leaves in air or at moderate vacua, as it agreed with what is already well known. The exhaustion was pushed to a very high degree (about the millionth of an atmosphere), when it was found that the excited 348 Mr. W. Crookes on [Feb. 20, ebonite had a much greater effect on the gold leaves than at a lower exhaustion ; for a long time however I was not able to charge the leaves permanently, in consequence of their falling together as soon as the source of electricity was removed. Diels ab When a hot substance was brought near the bulb facing a gold leaf, so as to warm the glass, molecular repulsion took place, and the leaves retreated from the warm spot, standing out at an angle of about 45°. As the glass cooled the leaves resumed their former vertical position. While the leaves were repelled from the hot glass, the excited ebonite had a very powerful action on them, and if it were brought near hastily, the leaves flew off to the side of the glass, destroying the apparatus. By careful management and repeated trials, however, the ebonite could be brought near the warm spot of glass, the leaves suddenly extending at an angle to each other. The appearance was as if a spark had been able to pass across the bridge formed by the line of advancing and retreating molecules connecting the hot glass with the gold leaves. On the ebonite being removed and the glass allowed to cool, it was found that the repulsion of the leaves was permanent. The rubbed ebonite would attract and repel them as 1t was moved to and fro, but the angle formed by the leaves with one another re- mained unchanged. A warm body brought near the glass opposite one leaf would repel the pair as a whole; on then warming the opposite side of the glass repulsion on that side took place, the angle of the leaves being somewhat diminished, but on cooling the leaves opened again to their former extent. When the glass bulb was strongly heated by a spirit flame the leaves suddenly discharged and fell together. Another bulb (fig. 2) was prepared, containing a plate of mica, a, which could be suddenly placed between the gold leaves, bb. The 1879. | Hlectrical Insulation in High Vacua. 349 plate of mica was longer and wider than the gold leaves, and was con- nected with a small piece of iron wire, capable of moving up and E14. 2. down a tube sealed into the top of the bulb. By means of an outside magnet the mica plate could thus be lowered between the gold leaves or raised out of their way, as desired. The tube was exhausted to about the millionth of an atmosphere, the mica plate being held quite above the leaves. One side of the bulb was then heated, and the Eia. 3. 3950 Mr. W. Crookes on [Feb. 20, leaves permanently charged by means of the excited ebonite. The mica plate was now carefully lowered. As it came between the gold leaves they diverged further apart, and kept so as long as the mica plate was between them. On removing the plate the leaves reassumed their former divergence. This could be repeated any number of times. A similar piece of apparatus (fig. 3) was made, only instead of a mica plate coming between the leaves, a mica cylinder, a, capable of being raised and lowered outside the divergent leaves, was employed. I was not able to get entirely concordant results with this, owing to the friction of the mica developing electricity on the inner surface of the elass tube; but in all cases, when the cylinder was raised until it covered the electrified leaves, it had the effect of diminishing the angle which they formed with each other. The following experiments were also tried:—the leaves being separated about 160°, as at fig. 4, A, one side of the tube was slightly Fig. 4. heated by a spirit flame. The leaf on that side fell to a vertical position, and remained so when all was cold, the other leaf sticking out as before, as at B. This would seem to show that the divergence of the leaves in this case was not so much due to their mutual repulsion, as to an attraction exerted on each of them by the inner surface of the glass tube. The remaining divergent leaf could be slightly lowered when the glass tube above it was warmed with a bunch of cotton wool dipped in hot water. On cooling the leaf rose again to its original position. When this side of the tube was also heated with a lamp, the leaf was repelled down, but not so readily as the other had been, and when the tube got cold, it rose to nearly its former position. This was repeated several times with uniform results. When the leaf was repelled down, the vertical leaf also 1879. | Electrical Insulation in High Vacua. 351 moved away, so as to keep the same angle between them. It is = RE fore evident that the leaves themselves were also charged. Fie. 4. Fig. 4, C, shows the two positions of the leaves, aa before applying heat to the side c of the tube, and 0b after heating the glass at c. The tube was now heated on both sides, causing the leaves to come nearer together as shown at fig. 4, D. While the glass was warm the cylinder was raised so that it surrounded the leaves: this caused them to get a little closer together, and they kept in this position, shown at H, after the whole apparatus was quite cold. After remaining thus for some time, the cylinder was lowered, and the leaves widened out and took up the position shown at Dd, fig. 4, C. They did not return to the position aa, showing that their divergence was now owing to their own mutual repulsion, and not to an attrac- tion of one or other to the electrified glass. In December, 1877, I totally immersed one of these exhausted glass bulbs in a vessel of water; the gold leaves having previously been charged, and standing at an angle of 112° from one another, as at fig. 5. The water was connected electrically with “earth,” and the whole was set aside in a cabinet on the Ist of January, 1878. At the present time, after having remained in this condition for thirteen months, the leaves form exactly the same angle with one another which they did when they were first put in the cabinet. VOL. XXVIII. 2 ¢ 352 Profs. Livemg and Dewar [ Feb. 20, Fie. 5. From this experience | think we may consider that at an exhaustion of a millionth of an atmosphere, air is an absolute non-conductor of statical electricity. It is, therefore, legitimate to conclude that the vacuum of interstellar space offers equal obstruction to the discharge of electrified bodies, without necessarily interfering with their mutual repulsion if similarly electrified. It is possible that im these facts an explanation may be found of some obscure celestia] phenomena. II. “On the Reversal of the Lines of Metallic Vapours.” No. IV. By G. D. Livertne, M.A., Professor of Chemistry, and J. Dewar, M.A., F.R.S., Jacksonian Professor, University of Cambridge. Received February 12, 1879. In the experiments described in the following communication, instead of introducing the substances to be observed in the metallic form into our tubes, we have endeavoured to overcome, to some extent, the diffi- culty of the presence of impurities by making use of reactions which should generate the metallic vapours within the tubes. For this purpose we have generally employed the great reducing power of carbon and of aluminium at high temperatures. In a former communication (“ Proc. Roy. Soc.,” vol. xxvii) we described the reversal of the two blue lines of cesium and the two violet lines of rubidium by the vapours of those metals, produced by heating their chlorides with sodium in glass tubes. It might be doubtful from these experiments whether the absorption were due to the metals or to the chlorides. To decide this question, we first tried exsium chloride by itself, heated in a tube such as we used before. No absorption lines could be seen, although a good deal of the chloride had been vaporized and distilled to the cool part of the tube. The experiments were next repeated, both with rubidium and cxsium ? 1879.] on the Reversal of the Lines of Metallic Vapours. 353 chlorides along with metallic lithium. The two violet lines of rubidium and the two blue lines of cesium were reversed, as when sodium was used instead of lithium, and as the lithium gave no sensible vapour, the observations could easily be continued for a much longer time with the same tubes. No other absorption lines could be discerned. It may be observed, however, that it is not easy to obtain a source of light sufficiently rich in the least refrangible red to allow of observations on the absorption of light so little refrangible as the red rubidium lines. A platinum wire, heated nearly to fusion by an electric current, appeared to give the brightest light in this part of the spectrum, but of that light no definite absorption by the rubidium could be observed in the red. We then had some mixtures of carbonate of caesium with carbon, and of carbonate of rubidium with carbon, prepared by charring the tartrates; and observed the results of heating these mixtures in narrow porcelain tubes, placed vertically in a furnace, as described in our first communication on this subject (‘‘ Proc. Roy. Soc.,” vol. xxvii). A small quantity of the cesium mixture, intro- duced into a tube at a bright red heat, showed instantly the two blue lines reversed and so much expanded as to be almost in contact. The width of the dark lines decreased as the caesium evaporated, but they remained quite distinct for a very long time. A similar effect was produced by the rubidium mixture, only it was necessary to have the tube very much hotter, in order to get enough of violet light to see the reversal of the rubidium lines. In this case the two lines were so much expanded as to form one broad dark band, which gradually resolved itself into two as the rubidium evaporated. The reversal of these lines of cesium and rubidium seems to take place almost or quite as readily as that of the D lines by sodium, and the vapours of those metals must be extremely opaque to the light of the refrangibility absorbed, for the absorption was conspicuous when only very minute quantities of the metals were present. The red, yellow, and green parts of the spectrum were carefully searched for absorption lines, but none due to cesium or rubidium could be detected in any case. It is perhaps worthy of remark that the liberation of such extremely electro-positive elements as cesium and rubidium from their chlorides by sodium and by lithium, though it is probably only partial, is a proof, if proof were wanting, that so-called chemical affinity only takes a part in determining the grouping of the elements in such mixtures; and it is probable that the equilibrium arrived at in any such case is adynamical or mobile equili- brium, continually varying with change of temperature. Our next experiments were with charred cream of tartar in iron tubes, arranged as before. In this case a broad absorption band appeared, extending over the space from about wave-length 5,700 to 45,775, and in some cases still wider, with edges ill-defined, especially the more refrangible edge. By placing the charred cream of tartar in 2c 2 304 Profs. Livemg and Dewar [Feb. 20,. the tube before it was introduced into the furnace, and watching the increase of light as the tube got hot, this band was at first seen bright on a less bright background, it gradually faded, and then came out again reversed, and remained so. No very high temperature was required for this, but a rise of temperature had the effect of widening the band. Besides this absorption, there appeared a very indefinite faint absorp- tion in the red, with the centre at a wave-length of about 6,100, and a dark band, with a tolerably well-defined edge on the less refrangible side, at about a wave-length of 4,850, shading away towards the violet. A fainter dark band was sometimes seen beyond, with a wave-length of about 4,645; but sometimes the light seemed abruptly terminated at about wave-length 4,850. It will be noticed that these absorptions are not the same as those seen when potassium is heated in hydrogen, nor do they correspond with known emission lines of potassium, although the first, which is also the most conspicuous and regularly visible of these absorptions, is very near a group of three bright lines of potassium. It seemed probable that they might be due to a combination of potassium with carbonic oxide. We tried the effect of heating potassium in carbonic oxide in glass tubes, but, though the potassium united readily with the gas, the compound did not appear to volatilize at a dull red heat, and no absorption, not even that which potassium gives when heated in nitrogen under similar cireum- stances, could be seen. We then tried induction sparks between an electrode of potassium and one of platinum iu an atmosphere of carbonic oxide. The usual bright lines of potassium were seen, and also a bright band, identical in position with the above-mentioned band, between wave-lengths about 5,700 and 5,775. This band could not be seen when hydrogen was substituted for carbonic oxide. A mixture of sodium carbonate and charred sugar, heated in an iron tube, gave only the same absorption as sodium in hydrogen. There were also no indications of any absorption due to a compound of rubidium or of czesium with carbonic oxide. The experiments of Mallet (Chem. Soc. J.,” 1876) on the vola- tility of calcium, strontium, and barium, and the reducing action of aluminium on the oxides, especially in the presence of carbonate of sodium, induced us to try similar mixtures in our tubes. A mixture of barium carbonate, aluminium filings, and lamp-black, heated in a porcelain tube, gave two absorption lines in the green, corresponding in position to bright lines seen when sparks are taken from a solution of barium chloride, at wave-lengths 5,242 and 5,136, marked a and f by Lecog de Boisbaudran. These two absorptions were very persistent, and were produced on several occasions. A third absorption line, corresponding to line é of Boisbaudran, was sometimes seen, and on one occasion, when the temperature was as high as could be obtained in the furnace fed with Welsh coal, and a 1879.] on the Reversal of the Lines of Metallic Vapours. 300 mixture of charred barium tartrate with aluminium was used, a fourth dark line was seen with wave-length 5,535. This line was very fine and sharply defined, whereas the other three lines were ill-defined at the edges; it is, moreover, the only one of the four which corre- sponds to a bright line of metallic barium. Repeated experiments with charred tartrates of calcium and of strontium mixed with aluminium gave no results, but on one oc- casion, when some sodium carbonate was used along with the charred tartrate of strontium and aluminium, the blue line of strontium was seen reversed, and on another occasion, when a mixture of charred potassium, calcium, and strontium tartrates, and aluminium was used, the calcium line, with wave-length 4,226, was seen reversed. The fire in this case was fed with gas retort carbon, and the tem- perature such that iron tubes, though well coated with fire-clay, gave way in a few minutes. It appears, therefore, that the blue line of strontium, and the above-mentioned violet line of calcium, are rever- sible by this method, but not so easily or so certainly as the lines of barium or its compounds above mentioned. Tn order to obtain higher temperatures than we could obtain in the furnace used in our former experiments, we have made preliminary experiments with lime crucibles heated (1) by a jet of coal-gas and oxygen ; (2) by the electric arc. For this purpose a block of chalk or lime had a vertical tubular hole bored into it about 6 or 7 millims. in diameter, and for the gas jet a second lateral boring, meeting the other boring at the bottom (fig. 1). For the electric are two lateral Tube bored OU yy borings are made on opposite sides of the block, meeting the vertical boring at its bottom (fig. 2). Above the crucible we place a mirror inclined at 45°, so as to reflect the light from the vertical boring on to the slit of a spectroscope, a plate of mica being interposed between the mirror and crucible to deflect the stream of hot gas and 356 Profs. Livemg and Dewar [Feb. 20, catch the smoke, which would otherwise soon dim the surface of the: mirror. Carbon Carbor ‘Electrode Electrode With the jet of coal-gas and oxygen the usual green and orange bands of lime and the violet line of calcium (wave-length 4,226) were seen bright on the continuous spectrum, and on dropping in some aluminium their brightness increased at the same time that a dark line appeared in the middle of both the orange and green band. This dark line speedily disappeared in the case of the orange band, but lasted longer in the green band. When some lithium carbonate was: put into the crucible and the coal-gas turned on so as to be in excess, the red lithium line was reversed, appearing slightly expanded with a black line down the middle. For the electric arc 25 Grove’s cells were used, and the carbon poles introduced through the lateral openings, so as to meet at the bottom of the vertical boring of the lime crucible. A very brilliant spectrum of bright lines was produced on bringing the poles in con- tact, while a copious stream of vapours ascended the tube. On © drawing apart the poles, which could be done for nearly an inch without stopping the current, the calcium line (wave-length 4,226) was seen reversed. On dropping some aluminium into the crucible the calcium line just mentioned was very much expanded, and appeared with a broad black line in the middle. The other calcium lines in the neighbourhood on the less refrangible side were also ex- panded considerably, but were not seen reversed. The more refran- gible lines (Fraunhofer’s H), however, remained sharply defined, and did not appear sensibly expanded or reversed. On introducing some strontia the blue strontium line (wave-length 4,607) was immediately seen reversed, appearing as a broadish bright band, with a dark line in the middle. There were no indications of the reversal of any other strontium line, though the more refrangible: lines were conspicuously bright. ——._ ee). eo ea ee ee ee ee a —_— =. 1879.] on the Reversal of the Lines of Metallic Vapours. 357 When lithium carbonate was introduced the, red line was at once seen reversed, but not much expanded. When some aluminium was added, the lithium blue line (wave-length 4,604) was seen with a dark line in the middle for a short time only. The green line of lithium was very bright indeed, and appeared somewhat expanded on the addition of aluminium, but showed no reversal. On putting some baryta into the crucible the line with wave-length 5,935 was reversed, appearing very black but narrow. No other barium line could be seen reversed in that crucible, but in another crucible into which magnesia had been introduced, a dark line, with wave-length about 4,930, was observed, which may probably be ascribed to barium. With magnesia and aluminium the least refrangible of the b group was seen reversed, all the b group being expanded. When silver was introduced, on drawing the poles apart, both the brightest green lines (wave-lengths 5,464 and 5,209) were seen for a short time with a black line down the middle. Frequently on parting the poles, whatever might be the substance in the crucible, the whole of the brightest part of the spectrum, from the orange to the blue, appeared filled with dark lines, all equidistant and eqnally dark, like a fine grating. With a high dispersion these lines are seen to be ill-defined at the edges. We can only suppose them to be a banded spectrum of some compound of carbon. The lime crucibles are very quickly destroyed, but we hope to get some more compact lime than we have hitherto had, and to employ a more powerful electric current. The use of carbon or magnesia for crucibles will, we anticipate, enable experiments of this kind to be extended much further, and applied to various reactions taking place at the temperature of the arc. In the case of carbon crucibles the block of carbon itself will form one electrode, the other electrode Hia. 3. Sectzon of Carbon Cruczale a, (27 bon L£lectrode Tube bored WAL Copper plate 358 Messrs. W. H. Preece and A. Stroh. [Feb. 27, passing through a tybe of lime as in (fig. 3). It is our intention to try a combination of the electric arc and induction spark in these crucibles. It is hardly necessary to note that the projection of the reversals of the lines of metallic vapours may be effected by this method better than by any method heretofore in use. February 27, 1879. : THE PRESIDENT in the Chair. The Presents received were laid on the table, and thanks ordered for them. Major-General Thuillier (elected 1869) was admitted into the Society. The following Papers were read :— I. “Studies in Acoustics. I. On the Synthetic Examination of Vowel Sounds.” By WiLiIAM HENRY PREECE and AuGuUs- TUS STROH. Communicated by the PRESIDENT. Received February 17, 1579. [PLates 6, 7. ] 1. The authors of this paper have devoted much time during the past twelve months to a study of sonorous vibrations and the reproduc- tion of speech. The invention of the phonograph has proved a great stimulus to this study. Many have worked in the same field, and many of the facts elicited by the authors have been anticipated by those who have been able to give more continuous study to the subject. Nevertheless, the mode of enquiry, the apparatus employed, and the results obtained are thought to be of sufficient novelty to justify their being brought before the Royal Society. 2. The curves traced by the vibrating disk of the phonograph on tinfoil, whether examined microscopically or reproduced by a species of pantelograph, were soon found to be insufficiently delicate to give the nicer shades of sound, and to fail to indicate the true curve of vibra- tions in all cases. This-is shown by the imperfect reproduction of speech by the phonograph itself ; the merging of the labial and dental sounds into one another, and the absence of all the sibilants and generally of the “noises” of speech. ‘The phonograph is in reality a very imperfect speaker, and it requires the aid of much imagination and considerable guessing to follow its reproductions. It produces 1879. ] Studies in Acoustics. 359 music with wonderful perfection, but it fails to reproduce most of the “noises”? of which speech is so largely made up. The telephone is also deficient in this respect, though to a much less degree. 3. The first object of the authors was to find a disk which would vibrate to the finest shades of sonorous vibrations, and which would be free from those characteristic and “‘ personal” partials which are nearly inseparable from all vibrating disks, and which interfere with their true action. After innumerable experiments, on almost all known forms and substances, a stretched membrane of thin india-rubber rendered rigid by a cone of paper, was found to give the best effects. Sach a disk was applied to the telephone and the phonograph with fair results, and the apparatus shown in fig. 1 was then constructed to record its vibrations. To the centre of the cone ab, shown in perspec- tive and section in fig. 1, which was placed in a mouthpiece similar to that of a phonograph, was attached an extremely fine glass tube (q), which acted as a pen. The ink employed was aniline dye, and it was drawn through the pen by the very slight friction exerted between its point and the paper. The paper (p) on which the curves were to be drawn was the broad band frequently used for telegraphic purposes, and it was moved under the pen by mechanism similar to that used in the Wheatstone automatic telegraph apparatus, at a speed which could be varied at will from 1 to 18 inches per second. 4, In this way curves were obtained illustrating the sonorous vibrations due to the tones of speech, but their form was not so perfect as could have been wished, due to the imperfections of the disk, as well as, perhaps, to the friction of the pen failing to indicate the higher upper partials. Run at a slow speed, this instrument records the variations of air pressure in front of the lips; run at a high speed it records both air pressure and sonorous vibrations. It thus combines the functions of Barlow’s logograph and Leon Scott’s phonautograph. 5. It is intended, in this paper, to confine our observations to those facts illustrating vowel sounds, a graphic representation of which, drawn by the new phonautograph, is given in the following sketch (fig. 2). 6. Helmholtz’s theory of vowel sounds is this:—Vowels are compound musical tones, or resultant sounds formed by the combination of certain components or simple tones called partials. The first partial, which determines the pitch of the whole, is called the prime, and the others its upper partials. The partials depend upon the reinforcements due to the cavity of the mouth. Vowels do not depend upon the pitch of ‘the prime alone, or on the grouping or harmony of the partials alone, but on both. The ear must distinguish each component; it must recognise the kind of cavity producing the reinforcements, and there- fore it determines the different vowels. This theory has been partly 360 Messrs. W. H. Preece and A. Stroh. [ Feb. 27, confirmed recently by Messrs. Fleeming Jenkin and Ewing, by an analytical examination of phonographic tracings, fully described by them in a paper read before the Royal Society of Edinburgh. 7. The principal vowel sounds are— Ah, as in ve an .. path A * a SA es, hay E - sis Bu ie, ane O a ee oe cya sole 00i,, 755 a0 se Se OOGE There are several others which are modifications of these five, such as uh as in gut; d@ as in bad; aw as in law, &e. The diphthongs are :— 1 which is compounded of ah and e. u is e and oo. y - Ay oo, ah, and e. 8. The cavity of the mouth changes during the articulation of these diphthongs—it remains constant during the articulation of vowels. It is thought that the influence of the first emission of breath in dis- tinguishing the character of the vowels has been lost sight of, and that in addition to the influence of the cavity of the mouth, some allowance must be made for the increment and decrement of the sonorous vibrations, as well as for the variation of air pressure at the commencement and completion of a vowel sound. Helmholtz has acknowledged the influence of these operations in consonants and compound musical tones generally, but he has not considered them in vowel sounds. The previous diagram (fig. 2) shows what an essential feature they bear on vowel sounds. 9. The manner in which vowel sounds blend into each other is strikingly shown in the way in which different dialects deal with different vowels. Thus, what a London man calls subject a Lancashire man calls soobject; a Londoner says Mdnchester, a Lancashire man Mawnchester, a Scotchman Monchester. Under is often pronounced Onder. We need not, however, examine different dialects to discover this curious blending of vowel sounds; it is found in inhabitants of the same district to a greater or less extent. Thus with the word Manchester, Londoners often say Menchester, Manchester, or Marnchester. In every case which the authors have investigated, this change of vowel sound, due to dialect, is simply due to the shifting or lowering of the upper partials. 10. The order of the principal vowels, which is given above, does not follow any theoretical principle. It would seem that a better order to follow would be one dependent on the pitch of the partials as given by Helmholtz. 1879.] Studies in Acoustics. d61 All the subsidiary vowels, such as uh, aw, a, take up intermediate positions in this scale, so that, in fact, we may say that there is a vowel spectrum, in which the different sounds merge into each other by almost imperceptible gradations, and hence, probably, the difference in dialectical pronunciation. 11. In the following investigation, a method opposite to that of Messrs. Fleeming Jenkin and Ewing has been adopted, i.e., the question has been attacked by the method of synthesis. It has been assumed that vowels are compounded of a prime sound and certain upper partials, and the number of these partials has, for convenience, been taken as 8, although there are many more. Indeed, we have taken in some cases, the 10th, 12th, and 16th. Now, since each partial can be considered as a simple harmonic curve, if we assume the pitch of a prime to be constant, then it would be possible, by means of a machine, to represent and vary each partial in phase and in amplitude. For this purpose an instrument was constructed, which we call “the synthetic curve machine,” in which a number of toothed wheels, A, B, C, D, E, F, G, H, &. (figs. 8 and 4) are mounted on steel pins or axes rigidly fixed on a board, so that they will revolve together, and the numbers of their teeth are so calculated that during one revolution of the wheel A, B will make two, C three, D four, H five, F six, G seven, H eight revolutions, and so on. The wheel I has, on its prolonged axis, a small crank, by means of which the whole system of wheels can be rotated. On the same axis is a pinion I’, gearing into the wheel J, which, by means of a _ chain T, gives motion to a sliding table R. Hach head of the pins on which the eight wheels revolve, has, in its centre, a small pit or hollow, in which rest the pointed ends of eight steel rods (one of which B’ only is represented in fig. 4), held in position by eight springs b. To the rod on the wheel A is attached, near its point, one end of a silken thread b', passing over the roller N’, the other end being attached to the rod on wheel B. The rods on wheels C and D, K and F, Gand H are similarly connected. The four rollers N are mounted on two levers U and U’, and these are connected by links to the lever V, which is finally lmked to the lever P. This lever P is pivoted at p, and by means of the spiral spring S keeps the levers, links, and silk threads in a state of tension. On the longer end of the lever P is pivoted another lever Q, which carries at its shorter end 362 Messrs. W. H. Preece and A. Stroh. [Feb. 27, a small counterbalancing weight (W), and at its longer end a glass pen (Q) containing suitable ink. On the table R is placed a piece of paper or smoked glass, which is held there by two spring clamps. Hach of the eight wheels has on its face a number of small holes or pits, into which the points of the rods B’ can be placed, and these are arranged in eight rows radiating from the centre. When one of the rods, for instance that belonging to the wheel B, is placed in position B”, as indicated by the dotted lines, and motion is given to the wheels by means of the crank on the axle belonging to the wheel I, the crank- like movement of the rod B’ will, by means of the silk thread J’, roller N’, levers U, V, and O, cause the pen Q to move to and fro with simple harmonic motion, while the table R will move longi- tudinally, the pen thereby writing on the paper a simple harmonic curve. This can be done with each of the eight rods separately, the result being in each case a simple curve. Should, however, two or more rods be placed on the faces of the wheels, the result will be a curve compounded of the sum of the several simple curves. In order to increase or decrease the amplitude of a curve, the steel rods are placed further from, or nearer to, the centre of the wheels. Difference of phase is obtained by shifting the rods to the different radial rows of hoies on the face of the wheels. Three additional wheels, K, L, M, have been fitted, making 10, 12 and 16 revolutions respectively, to one turn of the wheel A, and the rods belonging to neighbouring wheels are so arranged that they can be borrowed for the use of these smaller wheels if desirable. 12. Besides assuming the pitch to be constant, it has also been assumed that each octave of the partial, to maintain equal loudness of sound, must diminish one half in amplitude as it rises. Thus the First Octave is 3 the amplitude of the prime. 1 Second 3 4 9 3 p= a a Third >) 8 oh) 39 - 1 Fourth 33 IT6 35 bb) ; The intermediate notes, such as the third and the fifth, decrease i intermediate ratio. 13. This instrument enables us to form synthetically all the curves produced by vowel tones, and to show how these tones are com- pounded of primes and harmonic upper partials. It shows how simple tones can be produced by simple harmonic curves, and compound tones by the simultaneous action of several simple tones. ' The following figure (fig. 5), shows the simple harmonic curve produced by each wheel, and several examples of curves formed by different components. In this way curves have been reproduced as shown in fig. 6, representing the vowel sounds based on Helmholtz’s theory, as indicated by Mr. Ellis in a tabular statement, at page 181 of his translation of Helmholtz’s work. aa oe 1879. | Studies in Acoustics. 363: Figs. 7 and 7a show reproductions of the vowel O, sung at different pitches, as determined by Messrs. Fleeming Jenkin and Ewing. 14. [It is worth remarking parenthetically, that one interesting fact arising from the operation of this machine, was that curves could be so constructed as to give a stereoscopic effect. One curve was drawn simple, and the other, drawn in the same line—at the proper distance from it to fit a stereoscope—was made compound, by the addition of a partial of low amplitude. The result of the combination by the eye in a stereoscope of these two curves, was to produce a perspective effect. By this means curves have been drawn which in- terlace amongst each other, giving stereoscopic effects in a manner which is uuique and interesting. This has no bearing whatever on the investigation, and is only adduced as a scientific toy arising out of the enquiry. | 15. Having thus studied the formation of vowel sounds, and having a means to reproduce the compound curves which graphically represent the motions which the air particles assume under their influence, the authors determined to try to reproduce these vowels by superimposing partials on to a given prime. Since vowels are produced by a prime and its upper partials, and as the upper partials diminish so rapidly in amplitude, the idea arose that these vowels might be reproduced by sounding a prime and one of its partials alone. This was done by means of an electro-magnet H, fic. 8, vibrating an armature (A) with a moveable spring (S) attached to it in such a way that the vibrations of the armature could produce a given prime, while the vibrations of the spring, by varying its length, could also be adjusted to any particular partial. 16. The result was to roughly reproduce the principal vowel sounds, but the effect not being by any means perfect (due to the absence of the other upper partials), a machine was made on the principle of the synthetic curve machine, which would, instead of drawing curves on paper, reproduce eight partials by transferring the vibrations of the intermediate wheels to a vibrating diaphragm. ‘This machine consists of eight wheels fixed on the same axis, the periphery of the wheels being cut into teeth of sucha number as to represent the eight partials. Each tooth is a simple harmonic curve, and each wheel represents one partial. The axis can be rotated by a crank at any given velocity. By depressing a key a spring can be brought into contact with the edge of each wheel, and be thus vibrated. The vibrations of these springs are transferred by thin cords and intermediate linking to a diaphragm of ebonite. Each spring can be depressed separately or simultaneously with others, and the disk will vibrate to the resultant effect of all the vibrations. Thus, notes and chords can be sounded. 17. Here again, though the vowels were fairly reproduced, some- 364 Messrs. W. H. Preece and A. Stroh. [| Feb. 273 thing was wanting in their clearness. This instrument proves to be an excellent syren, and all the facts iulustrated by the apparatus of Cagniard de la Tour and others can be equally illustrated by it. Moreover, it forms the basis of a new musical instrument which there has been no time as yet to mature. 18. In the hope of getting more perfect definition, another machine was now made upon which disks were fitted, whose peripheries were cut in exact copy of the curve produced by the synthetic curve macbine. These curves were transmitted by vibration to the receiving diaphragm of a phonograph, and really formed an ‘‘ automatic phono- graph.” The automatic phonograph consists of an axle A, fig. 9, about 6 inches long, one end of which carries a fly-wheel B, and the other end a grooved pulley C, round which a band or gut passes from a driving wheel D, fitted with a crank handle EH. On rotating the driving wheel, the long axle is caused to make about three revolutions to one of the wheel. On the long axle are placed, in such a manner that they can easily be removed and replaced by others, a number of brass wheels or disks, a, a, a, a, the circumferences of which have been cut by a machine especially devised for that purpose into the different curves corres- ponding exactly to the curves obtained by the synthetic curve machine, but on.a much reduced scale. A diaphragm G with spring and frame H, similar to that im a phono- graph, is so fitted that it can be shifted from one disk to another, and the sounds produced by the different curves can be readily compared. The number of periods or resultant vibrations recurring on each wheel or disk has for convenience been taken at thirty. Thus, when the driving wheel is rotated about twice per second, 180 to 200 vibrations are caused, resulting in a note at f or g in the musical scale. A number of combinations of curves has been cut on the circum- ferences of the brass disks, representing each vowel sound with certain variations of the partials, as experience determined. These disks were then placed on the axle, and the sounds most resembling the vowel sounds of the human voice were easily recognised. 19. In this way it was found that from about f to b in the musical scale, the sound oo consists mainly of the first partial or prime. But to maintain the oo character descending the scale, the second and third partials became slightly necessary. 20. The prominent partial in the vowel sound O at tlie same pitch is the second, while the first can be reduced considerably. The third and fourth partials have to be used as the sound descends the scale, otherwise what is O at say b flat, will become oo an octave lower. 21. The vowel sound ah is the easiest to reproduce. It consists chiefly of the third, fourth, fifth, and sixth partials at the above pitch, the first and second partials being only slightly represented. A little 1879. | Studies in Acoustics. 365 more prominence to the second, third, and fourth partials will result in aw, while a bright ah is obtained by increasing the amplitude of the fifth and sixth partials. 22. A very good and full ah is obtained by having all the partials equally represented, from the first to the eighth; and this really pro- bably takes place when the human voice pronounces this vowel, as, in so doing, the mouth cavity is fully opened, so as to favour most of the partials. 23. The vowel sounds @ and ee, when reproduced by most of the ordinary phonographs, resemble respectively more 0 and 00. Also the curves for a and ee, obtained by the phonautograph, fig. 2, resemble those for 0 and oo. This shows, in the first instance, that neither instrument is sensitive to the higher upper partials; and, secondly, that the lower partials for a must be similar to those in O, and the lower partials for ee must be the same as in 00. To prove this, two disks were cut, one with a curve composed of the first, second, and eighth partials, and the other of the first, third, and eighth partials. The former, when sounded, produced a sound like ee, and the latter more like a. 24, The best ee has been obtained from a curve composed of the best first, second, eighth, and sixteenth partials; and @ from a curve composed. of the first, third, and sixth or eighth partials; but this last curve can hardly be called satisfactory. 25. Diagram 10 graphically illustrates the above facts, and the following table gives them ina tabulated form :— Vowels. Partials with their Intensities. oo lhe 2 3. iit) Tailor NO) Oe ah it. ep ae A. TaaEg SRE mt DO: 0) Is 2 3. 4. 5) Gam toe [Oe | go (2 WRT Teds Orne a ike 3 8. mf. mf. fie ee... oe ie 2. Se wiles mf. p: jOb oy Laake Hence, although the reproduction of vowels was good, it was imper- fect. This is due probably to the absolute impossibility of repro- ducing the noises that accompany the last two vowels. 26. One very curious result arising from the experiments with the automatic phonograph was to show that, by varying the pitch, the vowel sounds could be shifted, 7.e., the curve which produced vo at a low velocity becomes approximately O at ahigher velocity. O similarly becomes ah, ah becomes 4G, and 4, éé. 366 Studies in Acoustics. : [Feb. 27, 27. It follows from this investigation as far as it has gone, that our knowledge of vowel sounds is not perfect. The principal proof of this is the fact that vowels cannot be reproduced exactly by mechanical means. Something is always missing—probably the noises due to the rush of air through the teeth, and against the tongue and lips. 28. The curves (fig. 10) arrived at synthetically do not differ very materially from those arrived at analytically by Helmholtz (fig. 6). They principally differ in the prominence of the prime. But the prime can be dispensed with altogether. Curves produced by the synthetic machine, compounded of the different partials without their prime, show that there exist beats or resultant sounds. A vowel sound of the pitch of the prime may be produced by certain partials alone, without sounding the prime at all. The beat in fact becomes the prime. This point is clearly illustrated, orally, by the automatic phonograph, and graphically by the sketch (fig. 11), drawn by the synthetic curve machine. In fact, every two partials of numbers indivisible by any common multiple, if sounded alone, reproduce by their beats the prime itself. Thus, the third and the fifth partials, or the second and the third, &c., will result in the reproduction of the prime. In fact, fig. 11 illustrates not only this, but it shows that when the number of partials introduced is increased, the beats become more and more pronounced. I1.—The Loudness of Sound. 29. Another point remaining for investigation arising out of this _ inquiry, is the true theory of the loudness of sound. It is thonght by the authors that loudness does not depend upon amplitude of vibration only, but also upon the quantity of air put into vibration ; and, therefore, there exists an absolutely physical magnitude in acoustics analogous to that of quantity of electricity or quantity of heat, and which may be called the quantity ofsound. This can be shown experimentally by con- structing three disks like those in fig. 1, whose diameters increase in arithmetical ratio. When these disks are vibrated by the same curve by the automatic phonograph, or when they are thrown into vibra- tion by tuning forks, it will be found that the intensity of sound increases in a surprising ratio. The amplitude remains just the same; the area under vibration alone increases. Thus, in the automatic phonograph, for two notes, one of which is an octave higher than the other, the area ought probably to be diminished one-half for the higher to produce equal loudness. Similarly for the same note, if we increase the area to be vibrated im its reproduction, it will be found that, as the area increases, so does the loudness of the sound emitted. In fact, in the automatic phonograph the diameter of the sounding disk ought, if it were possible, to vary with the pitch of each note, to produce equal intensity of sound. lal 0 EEPCCGE, C6 FB! 6 Freece & Stroh ER Se QD $$ PVA IT A VI IARI DPD 6 trv HVS th ——_ eee A NI IANS ONLI LINN 2IC8B If Sav{[J a aa VXI4S ETS oof ey Fig. 5. Vowel 0. ESE eo a NY ERI AIAG AG WAN WAS CAI VAIN Fig.7. Vowel 0). Y ffs SGD To, 1879.] On the Reversal of the Lines of Metallic Vapours. 367 The authors are now engaged in pursuing this inquiry into the con- sonantal sounds. II. “On the Reversal of the Lines of Metallic Vapours.” No. V. By G. D. Liveine, M.A., Professor of Chemistry, and J. Drwar, M.A., F.R.S., Jacksonian Professor, University of Cambridge. Received February 20, 1879. Since our last communication we have continued our experiments, using the electric arc as a source of heat, in lime and in carbon cru- cibles as described before. Success depends on the geiting a good stream of vapour in the tubular part of the crucible. This is easily attained in the lime crucibles, which quickly reach a very high tem- perature, but are very soon destroyed; not so certainly in the carbon crucibles, which are good conductors of heat. The latter, however, last for a very long time. In our experiments with tubes heated in a furnace we used a small spectroscope with a single prism, which gave a good definition and plenty of light; but in the experiments here described we have used a larger spectroscope by Browning, with two prisms of 60° and one of 45°, taking readings on a graduated circle instead of on a reflected scale. met Both in the lime and in the carbon crucibles we have found that the finely channelled spectrum, extending with great uniformity from end to end, always made its appearance so long as the poles were close together. A few groups of bright lines appear on it. We have not at present investigated this remarkable spectrum further. In several cases we have observed the absorption lines of the metals put into the crucibles on this channelled spectrum as a background, but generally when the vapours in the crucibles become considerable, the channel- lings give place to a spectrum of bright lines on a much less bright continuous background; we have used generally thirty cells in the galvanic battery, sometimes only twenty-five, once forty. The calcium line with wave-length 4,226 almost always appears more or less expanded with a dark line in the middle, both in the lime crucibles and in carbon crucibles into which some lime has keen in- troduced; the remaining bright lines of calcium are also frequently seen in the like condition, but sometimes the dark line appears in the middle of K (the more refrangible of Fraunhofer’s lines H), when there is none in the middle of H. On throwing some alumi- nium filings into the crucible, the line 4,226 appears as a broad dark band, and both H and K as well as the two aluminium lines between them appear for a second as dark bands on a continuous background. Soon they appear as bright bands with dark middles; eradually the dark line disappears from H, and afterwards from K, — VOL. XXVIII. 2p 368 Profs. Liveing and Dewar — | Feb. 27, while the aluminium lines remain with dark middles for a long time. When a mixture of lime and potassium carbonate (to produce a stronger current of vapour in the tube) was introduced into a carbon crucible the calcium (?) line with wave-length 4,095 was seen strongly reversed, and the group of three lines with wave-lengths 4,425, 4,434, and 4,454 were all reversed, the least refrangible being the most strongly reversed, and remaining so the longest, while the most refrangible was least strongly reversed and for the shortest time. Besides these reversals, which were regularly observed, the following were noticed by us as occurring in lime crucibles but with less certainty, perhaps only at the highest temperatures. Dark bands appearing for a short time and dwindling into sharp dark lines with wave-lengths about 6,040 and 6,068 (perhaps due to the oxide); a dark line replacing the most refrangible of a well-marked group of several bright lines with wave-length 5,581 (or possibly the. brighter line 5,588) ; and the lines with wave-lengths 6,121 and 6,161 reversed simultaneously for an instant and reappearing bright immediately ; and the line with wave-length 5,188 reversed. When aluminium was put into the crucible only the two lines of that metal between H and K were seen reversed. The lines at the red end remained steadily bright. When some magnesium was put into a lime crucible, the b group expanded a little without appearing reversed, but when some alu- minium was added, the least refrangible of the three lines appeared with a dark middle, and on adding more magnesium the second line put on the same appearance ; and lastly, the most refrangible was reversed in like manner. The least refrangible of the three remained reversed for some time; and the order of reversibility of the group is the inverse of that of refrangibility. Of the other magnesium lines, that in the yellowish-green (wave-length 5,527) was much expanded, the blue line (wave-length 4,703), anda line still more refrangible than the hitherto recorded lines, with wave-length 4,354, was still more expanded each time that magnesium was added. These last two lines expanded much more on their less refrangible than on their more refrangible sides, and were not seen reversed. The bright blue line (wave-length 4,481) seen when the spark is used, was not visible either bright or reversed ; and this seems to be in agreement with Capron’s photographs, which show this line very strong with the spark but not with the are. The following experiments were made in carbon crucibles :— When strontia was put in the lines with wave-lengths 4,607, 4,215 and 4,079 were all seen with dark lines in the middle, but no reversal of any strontium line less refrangible could be seen. After adding some aluminium and some potassium carbonate to increase the current of vapour, no reversal of any strontium red line could be detected, though momentary cloudy dark bands were seen in the red when 1879.] on the Reversal of the Lines fo Metallic Vapours. 369 fresh strontia was thrown in. ‘Two dark lines were seen in the extreme red, which proved to be the potassium lines reversed (wave- lengths 7,670 and 7,700). With a mixture of barium and potassium carbonates the line with wave-length 5,535 was strongly reversed, and that with wave-length 4,933 distinctly so. When barium chlorate was dropped into a cruci- ble, the four lines with wave-lengths 4,553, 4,938, 5,535, and 5,518, were reversed, and as they remained so for some time, it is probable that the action of the oxygen of the chlorate had nothing to do with the result, The last-named line (5,518) was the least strongly reversed. To observe particularly the effects of potassium a mixture of lime and potassium carbonate previously ignited was thrown in. Theviolet lines of potassium, wave-length 4,044, came out immediately as a broad black band, which soon resolved into two narrower dark bands having wave-leneths nearly 4,042 and 4,045. On turning to the red end the two extreme red lines were both seen reversed. No lines of potassium between the two extremes could be seen reversed, but the group of three yellow lines were all expanded though not nebulous, and other lines in the green were seen much expanded. These observations on potassium were more than once repeated with the same results. Using sodium carbonate only the D lines were seen reversed though the other lines were expanded, and the pairs in the green had each become a very broad nebulous band, and D almost as broad a black band. When sodium chlorate was dropped into a crucible, the pair of lines with wave-lengths 5,681, 5,687, were both momentarily reversed, the latter much more strongly than the former. © When a very little charred rubidium tartrate was put in, the two violet lines were sharply reversed, appearing only as black lines on a continuous light background. Turning to the red end, the more refran- gible of the two lines in the extreme red (wave-length 7,800) was seen to have a decided dark line in the middle, and it continued so for some time. The addition of more rubidium failed to cause any reversal of the extreme red line, or of any but the three lines already mentioned. On putting some lithium carbonate into the crucible, the violet line of lithium appeared as a nebulous band, and on adding some aluminium this violet band became enormously expanded, but showed no reversal. The blue hthium line (wave-length 4,604) was well reversed, as was also the red line, while a fine dark line passed through the middle of the orange line. On adding now a mixture of aluminium filings, and carbonates of lithium and potassium, the red line became a broad black band, and the orange line was well reversed. The green line was exceedingly bright, but not nebulous or reversed, and the violet line still remained much expanded, but unreversed. With regard to the green lithium line, we may remark that we have no doubt what- ever that it belongs to lithium, and that there must have been some 3700 Profs. Liveing and Dewar _ [| Feb. 2%, mistake in Thalén’s observation, which ascribed it to cesium. We have never detected this line with cesium, which, on the other hand, seems always to give the characteristic blue lines, both in the spark and in the flame, as well as to give the same lines reversed when its vapour is used as an absorbent. When metallic indium was introduced into the crucible, both the lines with wave-lengths 4,101 and 4,509 were at once seen strongly reversed, and so continued for some time. No other absorption line of indium could be detected. It is apparent that the expansion of lines, so often observed when fresh materials are introduced, must be ascribed to increase in the density of the vapours, not to any increase of temperature. Moreover, the length of tube which reaches a very high temperature in the expe- riments above described is very short in the lime crucibles, and still shorter in the carbon crucibles, so that the reversing layer is also short in many cases. We are, therefore, directing our attention to the means of heating up a longer length of the tubes, either by introducing oxy- hydrogen jets, or additional electric arcs one above another; and also to the introduction of reducing gas (hydrogen or carbonic oxide) to counteract the oxidising action of the air which is drawn in through the lateral openings. The curious behaviour of the lines of different spectra with regard to reversal has induced us to compare the bright lines of the chromo- sphere of the sun, as observed by Young, with those that are reversed in our crucibles. It is well known that some of the principal lines of metals giving comparatively simple spectra, such as lithium, aluminium, strontium, and potassium, are not represented amongst the dark lines of Fraunhofer, while other lines of those metals are seen: and an examination of the bright chromospheric lines shows that special rays highly characteristic of bodies which appear from other rays to be present in the chromosphere are absent, or are less frequent in their occurrence than others. In the following tables the relation between our observations on reversals and Young’s on the chromospheric lines is shown. } | | Taree | Frequency | Behaviour. ats ait | in chromo-, ‘Reversal in our Remarks. ! ae a | sphere. | tubes. 7 Sodi ‘Te Weaearoal ey Gali ee i, Se eee | OE pee } 0 | Expanded. | | D 50 | Most easy..........|. Principal ray. | ae 3 2 | Difficultly reversed. | Ee | | ones MW 2 Very diffused. | pS II | 4,983 | 0 | | | 4,982 +B) ” 1879.] on the Reversal of the Lines of Metalhe Vapours. Teresi Frequency Behaviour. in chromo- Reversal in our wave-lengths. Le rane sphere. ubes. Lithium. 6,705 | 0 iheversed lien atee eer. 6,101 3 Difficultly reversed. 4,972 O 0) 4,603 0 Readily reversed. 4,130 0 Very diffused. 32... Magnesium 5,527 40 Expanded. b, 5,183 50 INE VEESCG jertc's «s/o sie 6 bo 5,172 | 50 ar SE aa bs 5,167 30 Difficultly reversed .. 4,703 0 Much expanded. ? 4,586 10 is 5 Son- 4,481 0 Notseen either bright or reversed. Barium... 6,677 25 0 6,496 18 0 6,140 25 5,534 50 Readily reversed .... 5,018 15 Reversed. 4,933 30 nk a eae ee 4,899 30 0 4,583 10 Pretty readily re- | versed. Strontium. 6,677 25 | 0 6,496 18 4,607 0) Readily and strongly | reversed. 4,215 40 | Readily reversed .... 4,077 25 » %) Calcium... 6,161 | 8 Reversed difficultly .. 6,121 9 > %» 5,087 | 2 Doubtful reversal. ass). 10 Reversed. 4,587 2 0 4,576 4 0 4,453 ) Readily reversed. 4,435 1 ” » 4,425 | 2 ee 4,226 3 Most easily reversed . 4,095 (?)| 0 Strongly reversed. 3,968 |! 75 Well reversed. 3,933 50 Rather more readily than the last. Aluminium. 6,245 8 0 6,237 8 0 3,961 0 3,943 Remarks. Most characteristic, at low temperature and low density. Described by Bois- baudran. : Most characteristic. Doubtful whether due to magnesium. Characteristic of spark absent in are. May be either Ba or Sr. May be either Ba or Sr. Most persistent. Well-marked ray. May be Sr or Ba. 3) 3) bP) Most characteristic. Well marked. 9 9 Very bright. Very characteristic. Strong lines. Strongly reversed.... Very marked. atl 372 Presents. : [Feb. 6, Tikes Gi Frequency Behaviour. ‘ | eg eT in chromo- Reversal in our Remarks. seuss sphere. tubes. Poteniom 760 ne | aaa a 7700 0 Strongly reversed....| Chief rays. a 3 SGlob bo coo odd 6a doo] \iVelll tina sack Cesium.... 5,990 10 OS 4,555 10 Strongly reversed....| Most marked. In a subsequent communication we intend to examine carefully the contents of the preceding table. In the meantime we may remark that the group calcium, barium, and strontium, on the one hand, and sodium, lithium, magnesium, and hydrogen, on the other, seem to behave in a similar way in the chromosphere of the sun. Presents, February 6, 1879. Transactions. Freiburg im Breisgau :—Naturforschende Gesellschaft. Berichte tiber die Verhandlungen. Band VII. Heft 2. 8vo. 1878. The Society. Leipzig :—Firstlich Jablonowski’sche Gesellschaft. Preisschriften. XXI. Dr. Péhlmann, Die Wirthschaftspolitik der Florentiner Renaissance und das Princip der Verkehrsfreiheit. roy. 8vo. 1878. The Society. Melbourne :—Royal Society of Victoria. Transactions and Pro- ceedings. Vol. XIII, XIV. 8vo. 1878. The Society. Modena :—Societa dei Naturalisti. Annuario. Anno 12. disp. 3-4. 8vo. 1878. The Society. Nijmegen :—Nederlandsche Botanische Vereeniging. Nederlandsch Kruidkundig Archief. Verslagen en Mededeelingen. Tweede Serie. 2° Deel 4° Stuk; 3° Deel 1° Stuk. 8vo. 1877-78. The Society. Stockholm :—Kongl. Vetenskaps Akademie. Ofversigt . . af For- handlingar. 35te Arg. No. 3-5. 8vo. 1878. The Society. Plymouth :—Plymouth Institution and Devon and Cornwall Natural History Society. Annual Reports 1855-56, 1856-57. Annual Reports and Transactions 1857-58, 1859-60, 1861-65. Vol. II, ITI, IV, V, VI. Part 1. 8vo. 1855-78. The Institution. 1879. | Presents. 373 Transactions (continued). Wirzburg :—Physikalisch-Medicinische Gesellschaft. | Verhand- lungen. Neue Folge. Band XII. Heft 1-4. 8vo. 1879. The Society. Reports, &e. Brussels :—L’Observatoire Royal. Annuaire, 1879. 12mo. Bruzelles. 1873. The Observatory. Brighton :—Record of the Sub-Wealden Exploration. 8vo. 1878. H. Willett, F.G.S. Cambridge [U.S.]:—Museum of Comparative Zoology at Harvard College. Annual Report of the Curator for 1877-78. 8vo. . 1878. The Museum. Leeds :—Philosophical and Literary Society. Annual Report for 1877-78. 8vo. 1878. The Society. London :—General Medical Council. Minutes of the Executive Committee and of the Branch Councils, from May 1 to July 18. 1878. 8vo. The Registrar. Manchester :—Twenty-sixth Annual Report to the Council of the City of Manchester, on the Working of the Public Free Libraries. 1877-78. 8vo. 1878. The Committee. Montreal :—MceGill College. Annual Calendar, Session of 1878-79. Svo. 1878. The College. Paris :—Bureau des Longitudes. Annuaire pour An 1879. 12mo. . The Bureau. Washington :—United States Geological and Geographical Survey of the Territories. Bulletin. Vol. IV. No. 4. 8vo. 1878. Tenth Annual Report, by F. V. Hayden. 8vo. 1878. Mis- cellaneous Publications. No. 11. Birds of the Colorado Valley, by Elliott Coues. Part 1. 8vo. 1878. Preliminary Report of the Field Work, by F. V. Hayden. 8vo. 1878. Article from the “ American Naturalist.” 8vo. 1878. Prof. Hayden. Duveau (A.) Les Travaux Publics du Vingtiéme Siecle. 8vo. Beaufort 1878. The Author. Hall (Townshend M.) A Sketch of the Geology of Devonshire. roy. 8vo. Sheffield 1878. The Author. Hayter (H. H.) Victorian Year-Book for 1877-78. 8vo. Melbourne 1878. The Author. Moseley (H. N.) F.R.S. Notes by a Naturalist on the ‘“ Challenger,” being an account of various observations made in the years 1872- 76. 8vo. London 1879. The Author. 374 Presents. [Feb. 13, Plantamour (E.) Résumé Météorologique de l’année 1877 pour Genéve et le Grand Saint-Bernard. 8vo. Genéve 1878. - The Author. Rogers (H. RB.) New and Original Theories of the great Physical Forces. 8vo. New York 1878. (2 copies.) The Author. Schiaparelli (G. V.) 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F.L.S. 1879.] Physiology of the Nervous System of the Crayfish. ate Henry Bessemer, Assoc. Inst. C.E. Henry Francis Blanford, F.G.S. George Stewardson Brady, M.D., F.L.S. Prof. Alexander Crum Brown, D.Sc., M.D. Walter Lawry Buller, F.L.S. Charles Creighton, M.D. William Sweetland Dallas, F.L.S. George Howard Darwin, M.A. Francis Stephen Bennet Francois de Chaumont, M.D. John Dixon, C.H. Sir George Duckett, Bart. Prof. Joseph D. Everett, M.A., D.C.L. William Galloway. Henry Haversham Austen, Lieut.-Col. Prof. Thomas Minchin Goodeve, M.A. Charles Alexander Gordon, M.D., C.B. Charles Graves, Bishop of Lime- rick. Townshend F.G.S. John Harley, M.D., F.L.S. John Deakin Heaton, M.D. Henry M. Jeffery, M.A. John Edward Lee, F.S.A., F.G.S. D:Se., Godwin- Monckton Hall, Prof. George Downing Liveing, M.A. George Matthey, F.C.S. William Munro, General, C.B., F.L.S. Charles Henry Owen, Col. R.A. William Henry Preece, C.H. Charles Bland Radcliffe, M.D., iH, KCB. John Rae, LL.D. George Banks Rennie, C.H. Prof. J. Emerson Reynolds, M.D. George F. Rodwell, F.C.S. George John Romanes, M.A. Sir Sidney Smith Saunders, C.M.G. Arthur Schuster, Ph.D., F.R.A.S. Michael Scott, M.1.C.E. | Prof. Harry Govier Seeley, F.L.S. John Spiller, F.C.S. Bindon Blood Stoney, M.1.C.H. Sir Henry Thompson, F.R.C.S. William A. Tilden, D.Sc. Alfred Tribe, F.C.S. James Clifton Ward, F.G.S. Benjamin Williamson, M.A. Charles R. Alder Wright, D.Sc. Prof. Edward Percival Wright, M.D., M.A., F.L.S. Thomas Wright, M.D., F.R.S.E., F.G.S8. M.A., The following Papers were read :— I. “ Observations on the Physiology of the Nervous System of the Crayfish (Astacus Fluviatilis).” By JAMES Warp, M.A., Fellow of Trinity College, Cambridge. Communicated by MIcHAEL Foster, M.D., F.R.S., Prelector of Trinity College, Cambridge. Received February 17, 1879. I. When one of the supra-wsophageal commissures is divided, the whole body of the crayfish on the injured side is more or less enfeebled, with AAD 380 Mr. J. Ward. On the Physiology of the Nervous [Mar. 6, the exception of the swimmerets and possibly the gnathites. The change is most marked in the antenne and eye-stalks, which barely respond to considerable excitation; and after these perhaps in the abdomen, the power of swimming or turning over being generally entirely lost. The muscles connecting the abdominal segments on the injured side are relaxed, and the tail-fin appendages on that side are no longer spread out in the normal manner, but remain more or less overlapping and hang down like broken limbs. This leads to a want of symmetry which is most conspicuous during movement: it almost disappears when the nervous connexion with the abdomen is entirely severed by a cut between the first and second segments. No clear difference is discernible in the pinch of. the two chelew, but in prehension and locomotion all the limbs on the side of the injury are weakened. In consequence of this, when walking forward the course taken is towards the sound side, in backing the course is towards the injured side. The chele during progression show a bias towards the sound side ; that is to say, when the right commissure is cut, they are both directed towards some position on the animal’s left, and vice versa when the left commissure is cut. There is a tendency when walking to flop suddenly forwards, and in some cases to “ wabble” from side to side. II. So long, however, as the other commissure remains intact, there is no lack of spontaneity and purpose in the movements of the cray- fish; but when this too is severed, that is, when both cominissures con- necting the supra- with the sub-cesophageal ganglion are divided, every- thing of the kind disappears, save that occasionally the antenne are waved about in the normal fashion, though much more feebly. The animal lies on its back, the maxillipedes, the chelz, and the first three pair of legs, for the most part, swinging slowly to and fro in perfect tenypo; not, however, as the swimmerets do, both sides synchronously, but with the movements of one side alternating with those of the other. On a very slight disturbance, and at intervals, without any obvious cause, this rhythmic swing gives place to feeding or ‘‘ preen- ing’”’ movements, the last being chiefly confined to the fourth pair of legs, which take no part in the rhythmic swing. The feeding move- ments are a perfect mimicry of the movements made when food is actually seized. These last appear to be in all respects perfectly co- ordinated; so much so, indeed, that the chelate legs will wait their turn to pass their morsel to the mouth when scraps are placed in all of them at once. But neither they, nor the chele, nor the posterior maxillipedes, show any selective power, even the animal’s own antenne being seized: the first evidence of taste appears when the food gets within the cape of the mandibles. When placed on a table, the ambulatory legs are straightened out so as to lift the body as if upon stilts, the half flexed abdomen barely £879. | System of the Crayfish (Astacus Fluviatilis). 331 touching the ground with the tail-fin. In this position the animal will remain for a minute or so, one or more cf the chelate legs engaging in feeding movements, while the last pair are doing their best to preen the abdomen. At length there is an attempt at locomo- tion, the limbs being moved slowly and in a tottering fashion, though with fair co-ordination, till after a few steps, having no power to recover its equilibrium, the animal rolls over helplessly on to its back. In some cases the chelee were folded rigidly across each other so as to render locomotion impossible. III. When both commissures are divided behind the sub-cesophageal ganglion, the antenne are moved more frequently and more vigorously than in the last case: the eye-stalks too ‘are oftener in motion. The rhythmic swing is not infrequent in the posterior maxillipedes, but very exceptional and of very short duration elsewhere. Preening movements are more common than under the last head, and in these all four pairs oftener take part; but feeding movements, save after external excitation, are quite exceptional. Then, however, they are vigorous enough, but the chelate legs are very uncertain in their aims at the mouth, do not loose their hold of the food when they get it there, and all of them attempt to crowd food into the mouth together. But the food is frequently rejected : in two cases ont of three in which the experiment was tried, this “‘sulkiness”’ disappeared on dividing the supra-cesophageal commissures. On the table these crayfish are unable to support themselves, the chelze sprawl helplessly on either side and the legs are for the most part doubled up under the body. The posterior maxillipedes alone retain their wonted strength, and by means of these the cephalothorax is raised from the ground two or three times a minute till they are exhausted ; the antenne too being waved vigorously all the time. IV. In three cases in which a longitudinal division of the supra- esophageal ganglion was accomplished fairly satisfactorily, the animal assumed the stilted position above described, but the abdomen, instead of being bent sharply downwards, was alternately elevated to the utmost and then depressed and sometimes curved rigidly backwards for a minute or more: at which times, owing to the rigor of the chelee, it was possible to make the animal stand upon its head. These animals had considerable power of maintaining equilibrium and were active in the water, making, however, very pronounced “ circus-move- ments.” Their ambulatory legs were always obedient to the impulse to walk, and never betook themselves to feeding or preening move- ments at such times. From the foregoing it may perhaps, with more or less probability, be inferred :— ) (a.) That there is no decussation of the longitudinal fibres in the nervous system of the crayfish. 382 Physiology of the Nervous System of the Crayfish. [Mar. 6, (b.) That on the presence of the supra-cesophageal ganglion depend (1) the spontaneous activity of the animal as a whole, or what might be called its volitional activity; (2) the power to inhibit the aimless and wasteful mechanical activity of the lower centres; (8) the power to maintain equilibrium; and (4) the use of the abdomen in swimming. (c.) That the sub-cesophageal ganglia are the centres for co- ordinating (1) the locomotive* and (2) the feeding movements, and (3) for the rhythmic swing described under II. (The stilted gait in II and the vigour of the posterior maxillipedes in III, the limbs connected with the other centres being then disabled for locomotion, seem to show that the sub-cesophageal ganglion is the source of a considerable amount of motor energy.) (d.) That there is much less solidarity, a much less perfect con- sensus, among the nervous centres in the crayfish than in animals higher in the scale. The brainless frog, e.g., is motionless except when stimulated, and even then does nothing to suggest that its members have a life on their own account; whereas the limbs of a crayfish - deprived of its first two ganglia, are almost incessantly preening, and when feeding movements are started, the chelate legs rob, and play at cross purposes with, each other as well as four distinct individuals could do. (e.) That some stimulus from other centres is more or less necessary to the activity of any given centre. This conclusion is rendered, at all events, probable (1) by a comparison of the activity of the antennz and eye-stalks in I, II, and II]; (2) by the diminution in the spon- taneous feeding movements in III; and (38) by the simultaneous increase 1n the preening movements—the excitations from the tail-fin region having no longer a counterpoise. (f.) The “natural” discharge of a ganglionic centre (not ex- hibiting “ volition”) appears to be of a rhythmic kind; the rhythmic movements becoming converted into varied movements by temporary augmentation or inhibition. It remains to mention one or two outlying points. There is much in the action and inaction of the mandibles, to suggest very consider- able independence between the centre for their movements and that for the movements of the maxillipedes—which last is doubtless situated in the sub-cesophageal ganglion. Thus the mandibles in several cases lost the power to move while the maxillipedes continued unaffected, and * Tn further proof of this position it may be added that, when the commissures are divided behind the second thoracic ganglia, the animal crawls with extreme difliculty by alternate advances of the chele alone; and that when they are divided behind the third it walks by alternate advances both of the chele and the first pair of legs: the other legs in each case being rucked together in confusion. + Is there such a rhythm at the bottom of “volitional”? movements ? 1879.] On the Comatulee of the “ Challenger” Hxpedition. 383 they never, at any time, participated in the rhythmic swing or feeding movements of these last. Gentle pressure on the anus or the sexual organs excites or inhibits the swimmerets, according as they are already at rest or in motion, and leads, where possible, to a folding of the abdomen. The feeding and preening movements are also, as a rule, brought to a complete standstill by slight irritation of the anus, the after movements being in all cases more violent. So long as the nervous connexion with the tail-fin remained intact, the swimmerets can be excited to considerable activity by touching this region, but when this connexion is destroyed, it is with difficulty they are made to move at all. The experiments, of which the above is a brief and preliminary account, were carried on at the Physiological Laboratory, Cambridge. II. “ Preliminary Report upon the Comatule of the ‘Challenger ’ Expedition.” By P. HERBERT CARPENTER, M.A., Assistant Master at Eton College. Communicated by Sir WYVILLE THOMSON, F.R.S. Received February 18, 1879. Published by permission of the Lords Commissioners of the Treasury. The collection of Comatule made by the staff of the ‘‘ Challenger ”’ includes specimens from 45 different localities, but few of which are deep-water stations. 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Some spectra are full of doublets: sodium and potassium, as ordinarily mapped, may be said indeed to consist .ex- clusively of doublets; others, again, are full of triplets, the wider member being sometimes on the more, sometimes on the less, re- frangible side. Doublets and triplets, as a rule, reverse themselves more freely than the irregular lines in the same spectruam—which particular doublet or triplet will reverse depending upon the tem- perature, as if the cooler vapour to which the reversal is due varied as in the case of fractional distillation. Some lines are clean cut in their reversal ; others, again, to use the laboratory phrase, are fluffy to a degree that must be seen to be appreciated, so much so, that when photographed they appear merely as blurs upon the plate. . The above results, which have been foreshadowed in my previous papers, have led me to examine especially the intensities of the various Fraunhofer lines, and to compare the intensities of the metallic lines confronted with them in are and sun photographs. I have done this because it is worse than useless to proceed with this construction of the large map now that four years’ work has shown that the method of impurity elimination has proved insufficient, until some other method, embodying a higher law, can be used; and to get this we want work over the whole field. This examination I am making, not only from K to G, over which my own photographs extend, but even to b, by means of another series taken by Professor Roscoe, which he has allowed me to inspect. In short, in this survey I have about 300 photographs to work upon. T exhibit several of these photographs to the Society in anticipation of a further communication. The upshot of this inquiry even already is as follows:—The dis- crepancy which I pointed out, six years ago, between the solar and terrestrial spectra of calcium is not an exceptional, but truly a typical case. Variations of the same kind stare us in the face when the minute anatomy of the spectrum of almost every one of the so-called elements is studied. If, therefore, the argument for the existence of our terrestrial elements in extra-terrestrial bodies, including the sun, is to depend upon the perfect matching of the wave-lengths and in- tensities of the metallic and Fraunhofer lines, then we are driven to the conelusion that THE ELEMENTS WITH WHICH WE ARE ACQUAINTED HERE DO NOT EXIST IN THE SUN. 1879.| Organization of Fossil Plants of the Coal Measures. 445 March 27, 1879. THE PRESIDENT in the Chair. The Presents received were laid on the table, and thanks ordered for them. The following Papers were read :— I. “On the Organization of the Fossil Plants of the Coal Measures. Part X.” By W. C. WiLLIAMson, F.R.S., Pro- fessor of Natural History in Owens College, Manchester. Received March 5, 1879. (Abstract. ) The still existing differences of opinion respecting the botanical affinities of the Sigillariz give value to every new fact calculated to throw light upon the question. In 1865, Edward Wunsch, Hsq., of Glasgow, made a discovery, which proves to have an important bearing upon it. He found, at Laggan Bay, in Arran, a series of rather thin Carboniferous strata, separated by thick beds of voleanic ash, and in one of the Carboniferous shales especially, he discovered the bases of the stems of numerous very large trees, standing perpendicularly to the shales. These trees have been referred to by several authors as Sigillarian. In the summer of 1877, Mr. Wunsch and I employed quarrymen to make extensive excavations amongst these strata, for the purpose of adding to the extensive series of specimens which he had obtained, and the whole of which he kindly placed in my hands. The aggregate result of these explorations was to show that the con- clusion previously arrived at, viz., that the stems had belonged to a grove of Sigillarian trees was unsupported by a solitary fact. These stems were of very large size, showing that they had belonged to fully grown trees. None of them displayed any traces of leaf-scars, having outgrown the stages at which such scars would remain visible. Their outer surfaces were scored with deep irregular longitudinal fissures, resulting from internal growth and consequent expansion, and which appear to have been mistaken for the longitudinal grooves and ridges of a Sigillarian bark. Such, however, they certainly were not, since, in every instance, the surface bark had been entirely thrown off, and the fissures entered deeply into the subjacent bark layer. In most of the stems, this comparatively thin bark layer was the only one that re- mained, the greater portion of the inner bark and the central vascular axis having disappeared, leaving a large cylindrical cavity, which was 446 Prof. W.C. Williamson. On the Organization [Mar. 27, filled up with volcanic ash. These stems failed to display a single feature, justifying the conclusion that they were Sigillarian. In two of them the central cavity, instead of being filled with ash, was filled with miscellaneous heaps of vegetable matter, amongst which were large fragments of the vascular axes of various plants, such as Lepidodendra and Stigmaric, but in one of the largest stems were five or six decorticated vascular cylinders of Diploxyloid stems, of the largest size, and which, though arranged parallel to the long axis of the cylinder which enclosed them, obviously did not belong to them, but had been floated in from without. The sup- position that these had been young stems that had grown within the hollow protecting cylinders, from spores, accidentally intro- duced, is wholly untenable, since each one of these several vascular axes has been the centre of a stem fully as large as that within which we found them aggregated. Of course, these Diploxyloid vascular axes had the organization which Brongniart and the younger school of French botanists which still upholds his views on this point, believe to be characteristic of true Sigillarizs—a conclusion from which I have long dissented. The only fragment we found, that threw any light upon the character of the leaf-scars that had indented the nities of these fully grown stems, was a well-defined example of the Lepidodendroid type. We directed careful attention to the nature of the smaller fraements of branches and foliage which abounded in the volcanic ash with which the large stems were overlaid. These consisted of Lepido- dendroid branches and twigs of all sizes and ages, and no doubt was left upon my mind that they were really the disjecta membra of the stems around which they were so profusely scattered. The only fruits that have been obtained from the same locality are Lepidostrobi, most of which contain macrospores and microspores. Unless weare prepared to believe that this Arran deposit contained, on the one hand, numerous stems without branches, and, on the other, yet more numerous branches without stems, we must recognise in these specimens the comple- mentary elements of a grove of Lepidodendroid trees. One specimen found is a very important one. It has a mean diameter of six inches, and is either a small stem or a very large branch. Internally it exhibits the same structure as all the smaller Lepidodendroid branches, except so far as it is modified by size and age. But in addition to its other features, it exhibits a very narrow exogenous ring surrounding the ordinary Lepidodendroid one, thus giving some clue to the size attained by such branches before the internal organization passed from the Lepidodendroid to the Sigillarian type. I have at last succeeded in obtaining the Strobilus, to which the remarkable macrospores and microspores figured in my last memoir 1879. ] of the Fossil Plants of the Coal Measures. 447 belong. It unexpectedly proves to be a very small one, being little more than an inch in length. Further specimens have shown that the abnormal peduncles of the macrospores shown in Plate 23, fig. 64, are wholly due to the partial collapse of the spore-wall. Further specimens have also been obtained of the Strobilus and its spores represented in Plate 22, figs. 38-57. These examples possess the central vascular axis in a perfect state, which portion was lacking in the previously known examples. It proves to have an individuality as distinctive as that of the spores and sporangia which it bore. The important discovery by Mr. D’Arcy Thompson, of Hdinburgh, of young branches of Ulodendron with reproductive cones actually attached to the scars characteristic of the genus, finally settles the nature and functions of these scars, showing that they mark the positions from which bilaterally arranged deciduous organs of fructifi- cation have fallen. The structure of Calamostachys Binneyana has had further hight thrown upon it, sustaining my previously expressed convictions that it had a triquetrous axis, and that consequently its affinities were with Asterophillites and Sphenophyllum, and not with Calamites. A specimen demonstrates that the six vascular bundles going to the six fertile sporangiophores were given off in pairs from the three truncated angles of a triangular vascular axis—an orientation absolutely identi- cal with that represented in similar sections of stems of Sphenophyllum, published by M. Renault. The recent discovery by Herr Stur, of Vienna, of a plant in which Sphenopbylloid and Asterophyllitean leaves are found upon a common stem, establishes the correctness of my previous conclusions as to the very close affinities of these two genera. | Two new fern petioles or stems have been obtained from Halifax, to which I have given the name of Lachiopteris robusta and R. insignis. In one specimen of the latter, the large vessels of the central bundle are full of Tylose cells, whilst a second example exhibits no trace of them. This shows the existence or non-existence of Tylose to bea characteristic having no specific value. Since my last memoir was written I have obtained several new forms of cryptogamic conceptacles—similar to those previously de- scribed under the generic name of Sporocarpon—as well as been able to throw additional light upon some of those previously described. No clue has yet been obtained as to the plants to which these very remarkable organisms belonged. ; A large series of specimens from Oldham and Halifax has enabled me to investigate in detail the very curious objects to which Mr. Carruthers gave the name of Traquairia, and which that observer believes to be a form of Radiolarian life. Their very elaborate orga- nization can scarcely be made intelligible without the aid of plates. Ina 448 Organization of Fossil Plants of the Coal Measures. [Mar. 27, previous memoir (“ Phil. Trans.” 1874, p. 56), I ventured to doubt the correctness of Mr. Carruthers’ conclusions, and expressed my conviction that these objects resembled spores rather than protozoan skeletons. Further study of their details of structure has only strengthened this opinion which has also received the important support of Professors Heckel and Strasburger, of Jena, both of whom have carefully studied my collection of specimens. These objects are small spheres—the sphere-wall of which is prolonged into a series of long radiating tubes not unlike the muricated spines of a Cidaris. In their young state each murication gives off a delicate thread or threads, which ramified freely in an apparently mucilaginous or gelatinous, structureless, in- vesting magma. In older specimens these threads developed into branching and radiating cylindrical tubes which, like the primary ones, had very thin walls. Within the outer sphere-wall, which consists of the coalesced bases of these branching tubes, were at least two other thin layers of membrane, and in several of the specimens the interior of the capsule is filled with cells, exactly like those seen in the corre- sponding cavities of Lycopodiaceous macrospores found in the Halifax deposits from which the finest Traquairie have been obtained. ‘These objects differ considerably from all known reproductive structures ; but I agree with Professor Heckel in his very decided rejection of them from the Radiolarian group of organisms, and with his conclusion ° that they are vegetable and not animal structures. Professor Stras- burger thinks it most probable that their affinities are with the macrospores of the Rhizocarpee. In my previous memoir I gave three very small figures of some minute objects, which exactly resemble, in their minutest details, the zygospores of some of the Desmidiacee. Many additional examples of these objects have been discovered, enabling me to throw further light upon them. Their resemblance to these zygospores has been made increasingly obvious, but I dare not venture to assign to them a Desmidiaceous origin, since the most extended research, and the re- sulting discovery of large numbers of these organisms, haye yet failed to bring to light the faintest trace of a true Desmid. Under these circumstances I have assigned to several species of these organisms the generic name of Zygosporites. The seed described in my last memoir but one, under the name of Lagenostoma ovoides, always exhibited a thick carbonised testa, in which no structure could be observed. I have now discovered that the thick outer layer consisted of very hard cubical or shghtly oblong schlerenchymatous cells, whilst a thin and delicate inner membrane was composed of small spiral prosenchymatous ones. An additional specimen of the woody axis of Dadozylon exhibits the paired divergent structures passing outwards to the back in the shape of two large, radial prolongations of the cellular pith; and which 1879.] Physiology and Histology of Convoluta Schultz. 449 must obviously have gone off the branches—either to ordinary ones or to pairs of fruit-spikes. Myriads of the vegetable fragments both from Oldham and Halifax are drilled in all directions with rounded insect or worm borings, and. further traces of these xylophagous animals are seen in innumerable clusters of small Coprolites of various sizes; the size of those com- posing each cluster being uniform. Desirous of verifying Count Castracane’s alleged discovery of Diatoms in coal, specimens of twenty-two examples of coal from various localities in Yorkshire, Lancashire, and Australia were reduced, after the Count’s method, to a small residue of ash. This work was done for me in the chemical laboratory of Owens College through the kindness of Professor Roscoe. Like Mr. F. Kitton, of Norwich, the Rev. E. O’Meara, of Dublin, and the Rev. G. Davidson, of Logie Cold- stone, I have failed to discover the slightest trace of these organisms in coal. The last objects described are some minute organisms from the Car- boniferous limestones of Rhydmwyn, in Flintshire, and which were supposed by Professor Judd to have been siliceous Radiolarians from which the silica had disappeared and been replaced by carbonate of lime. I fail to find any confirmation of this conclusion. The objects ‘appear to me to constitute an altogether new group of calcareous spherical organisms that may either have been allied to the Foram- nifera, or have had some affinities with the Rhabdoliths and Coccoliths. I have proposed for several species of the organisms the generic name of Calcisphera. Myriads of objects of similar character, but of larger size, constitute the greater portion of a Corniferous limestone from the Devonian beds of Kelly’s Island, U.S.A. | II. “Observations on the Physiology and Histology of Convoluta “Schultzu.” By P. GEDDES. Communicated by J. BURDON SANDERSON, M.D., F.R.S., Professor of Physiology im University College, London. Received March 10, 1879. Parr I.—Physiology. Chlorophylloid green colouring matters are known to exist in the tissues of a not inconsiderable number of animals belonging to very various invertebrate groups—Protozoa, Porifera, Coelenterata, Vermes, and even Crustacea ;* but all information as to the function of chloro- phyll in the animal organism is wanting. Wohler, it is true, found many years ago that Chlamydomonas, Huglena, &c., evolve oxygen in sunlight, and Schmidt prepared from Huglena viridis a body isomeric % See list in Sach’s “ Botany,” Eng. ed., p. 687, note, A50 Mr. P. Geddes. Observations on the [ Mar. 27, with starch, though of widely different properties, his paramylon ; * but these facts seemed as much to point towards the algoid nature of these long disputed organisms + as to warrant our supposing a more or less vegetable mode of life in animals so well organised, and so evidently carnivorous as Ceelenterates and Turbellarians, especially as the only recorded experiment, that of Max Schultze on Vortex viridis, yielded a totally negative result. Some such hypothesis, however, can hardly help recurring to the observer of the light-seeking habit of Hydra viridis, Last spring, when at the Laboratoire de Zoologie Expérimentale of M. de Lacaze-Duthiers, at Roscoff, I was much interested by the green Rhabdoccele Planarian,§ Convoluta Schultzii, O. Schm., crowds of which, lying at the bottom of the shallow pools left by the retreat- ing tide, resembled at first sight patches of green filamentous alge. Their abundance in fine weather on the surface of the white sand, covered only by aninch or two of water apparently to bask in the sun, was very striking, at once suggesting that their chlorophyll thus so favourably situated must have its ordinary vegetable functions. I accordingly returned to Roscoff in the autumn to make experiments. The mode of procedure was evidently to expose the Planarians to sunlight to observe whether any gas was evolved, and if so to analyse it qualitatively and quantitatively. After one or two trials a form of apparatus—the simplest possible—was found, which answered admir- ably. It merely consisted of a couple of the round shallow glass dishes used in the laboratory as small aquaria, the edge of one fitting as nearly as possible, when inverted, into the bottom of the other. Into the larger vessel were put Planarians enough to cover the bottom ; it was then gently sunk in the pneumatic trough (a tub of sea water), and the smaller, also full, inverted into it. The apparatus.was then placed on a shelf in the sunshine, and left to itself. The movements of the animals were greatly accelerated by the exposure, and in a quarter of an hour minute bubbles of gas were to be seen in the film of mucus plentifully secreted by the Planarians. These bubbles rapidly increased in number and volume until they buoyed up the whole sheet of mucus with its entangled Planarians and grains of sand to the top of the water in the inverted dish. Here the evolution of gas continued more actively than ever, until the animals had disengaged themselves and descended to the bottom, there to recommence as before, the mucus _ meanwhile dissolving and allowing the bubbles freely to unite. Thus the first half of the inquiry was answered in the affirmative. * Gorup Besanez, ‘ Traité d’ Analyse Zoochimique,” p. 127. + Euglena is claimed by both Sachs and Claus in their manuals of Botany and Zoology respectively. { “ Beitraige zur Naturgeschichte der Turbellarien.” § “Neue Rhabdocelen.” Wiener Sitzungsb., 1852. 1879.] Physiology and Histology of Convoluta Schultz. 451 The determination of the nature of the evolved gas was readily effected. On transferring the quantity produced in one or two vessels to a small test-tube, and plunging into it a match with red hot tip, there was to be seen the white glow characteristic of dilute oxygen. A large glass tube of tolerably even calibre, about 75 centims. long, was sealed at one end, and bent at about two-thirds of its length from that point at an angle of 60°. It was then filled with water, and the water in the long sealed arm almost entirely replaced by gas at the pneumatic trough. This comparatively large quantity of gas, about 60 centims. cube, was obtained by exposing a dozen or so of apparatuses exactly similar to that described, except that bell-jars, sealed funnels, &c., sometimes replaced the upper flat dish, and white soup plates the lower. They were set agoing about noon, and the abundant gas yielded by thus exposing a surface of nearly a third of a square metre covered with Planarians was collected at sunset. On agitating the gas with a solution of potassic hydrate a barely appreciable absorption of carbonic anhydride took place, but on the addition of pyrogallic acid with renewed agitation, the intense brown coloration, with rapid and considerable ascent of the fluid in the long arm of the tube, confirmed the presence of a large percentage of oxygen. The results of many experiments varied from 43 to 52 per cent. of oxygen ; the higher number representing the amount of gas given off by freshly collected Planarians, and the lower that yielded on the ~ second or third day of their subjection to experiment. In order to judge of the degree of accuracy which I could obtain by this rough method of analysis, I estimated by it the oxygen of common air, and obtained 19-9 per cent. instead of 20:9. Allowing for this loss of about © per cent., it may safely be asserted that the gas evolved by these animals does not contain less than from 45 to 55 per 100 of oxygen. : The Planarians are little the worse after a 24 hours’ journey from Roscoff to Paris, and when placed in an aquarium they instantly betake themselves to the side next the window, and live there resting on the bottom or clinging to the side for four or five weeks without food. They certainly diminish considerably in size, yet I have little doubt that they go on decomposing CO, and assimilating the carbon even in the dull winter daylight, for when kept in darkness they generally died much sooner. The conspicuousness of the Planarians on the sandy beach, far from the shelter which rocks or alge might afford, has been already men- tioned, and at first sight one is apt to think that they must be the easy prey of all the larger shore-frequenting animals, and to wonder that so many escape. But the observation made by Wallace and Belt for so many higher animals—that conspicuously coloured forms are 452 Mr. P. Geddes. Observations on the [ Mar. 27, nauseous and uneatable—holds good here. So strong and disagreeable is the odour, to which the taste doubtless corresponds, that this alone might be relied upon as a protection against the least fastidious of fishes or Crustaceans. The chemical examination of the animal yields results of interest. Treated with alcohol, a yellow substance, contained in small elongated vesicles, aggregations of which are dotted over the integument, dis- solves out very rapidly, yielding a golden solution without definite spectrum. This has of course nothing to do with xanthophyll. Con- tinued treatment with alcohol dissolves out the chlorophyll, of which the magnificent green solution is tolerably permanent. As former observers have shown, it has a red fluorescence, and gives a spectrum closely resembling that of vegetable chlorophyll. Knowing that these animals decompose carbonic acid, and evolve oxygen, one naturally enquires whether they do not still more com- pletely resemble green plants in fixing the carbon in the same way. To answer this question, the,residue of the Planarians, coagulated and decolorised by repeated treatment with alcohol and ether, was boiled with water, and filtered off. The clear solution gave with iodine solu- tion a deep blue coloration, which disappeared on heating, and reap- peared on cooling, indicating the presence in quantity of ordinary vegetable starch. To separate and purify this starch on a large scale, some hundred grammes of Planarians were repeatedly boiled in water. The solution (which had an intensely alkaline reaction) was treated with four or five times its bulk of strong alcohol, and allowed to stand for some days. The flocculent precipitate was collected, decolorised with ether, and washed with cold water. A great part of it dissolved, leaving the starch behind, and the filtered solution gave with iodine the red-brown coloration characteristic of dextrine. To ascertain whether this dextrine was naturally present, or had merely been pro- duced at the expense of the starch by boiling in alkaline solution, fresh animals were treated with cold water, but the solution contained no dextrine. Treatment of a fresh microscopic preparation with iodine showed the presence of glycogen, in the colourless amceboid cells of the mesoderm, but there is no chemical means of separating glycogen from starch. Probably the best way of obtaining pure starch from these animals would be by imitating the mechanical process of the potato mill. The intense alkalinity of the animals is very striking. Even in the fresh state, but still more when dried in the warm chamber, they give off vapours with an odour resembling that of trimethylamine, and in such abundance as to cause neighbouring solutions to yield the reac- tions of an alkaloid. A quantity of animals was distilled, and the alkaline fumes received in dilute hydrochloric acid. The resultant salt 1879.] Physiology and Histology of Convoluta Schultzu. 453 was purified by repeated solution and recrystallization in absolute alcohol. With PtCl, it yielded a precipitate, which was kindly analysed for me by Dr. Magnier de la Source, and found to be the platino- chloride of methylamine: however, it is very probable that the volatile alkaloid was really more complex, but broke up in the distillation. The subject would repay the attention of a chemist. Trimethylamine has been obtained from many animal sources, and the production of this, or some nearly allied body, in such remarkable quantity by Convoluta seems to be a protective specialisation. The ash of the Convoluta contains iodine, another analogy to the aloe. As the Drosera, Dionea, &c., which have attracted so much atten- tion of late years, have received the striking name of Carnivorous Plants, these Planarians may not unfairly be called Vegetating Animals, for the one case is the precise reciprocal of the other. Not only does the Dionwa imitate the carnivorous animal, and the Con- voluta the ordinary green plant, but each tends to lose its own normal character. ‘The tiny root of the Drosera and the half-blanched leaves of Pinguicula are paralleled by the absence of a distinct alimentary canal and the abstemious habits of the Planarian. It still remains to ascertain the’ behaviour of other green animals, and I hope to begin with Hydra and Spongilla,* as soon as the season permits. Part II.—Histology. The general characters of the animal have been already given by Schmidt, and I need only add that I have succeeded in making out the mouth, which lies, as usual in this genus, a little way behind the otolith. It is not a mere transverse slit, but is surrounded by a lip capable of slight protrusion, which evidently corresponds to the pro- trusible pharynx of higher Planarians. When feeling its way the animal has a curious habit of sharply retracting the terminal point of the anterior ends of the body, the head thus becoming bilobed, with a central depression. Hach lobe becomes a sort of temporary tentacle, and these may be compared with the blunt permanent head lobes of allied forms. So too the animal ‘‘ when extremely contracted” throws its smooth dorsal integument, not into irregular wrinkles, but into - rounded papille, which remind one of the permanent dorsal papille of other Planarians. I will first notice an interesting point in the histology of the ciliated ectoderm. In teased preparations, kept cold, the ciliated cells often become amoeboid, some of the cilia changing into slender finger-lhke or stout fusiform pseudopodia. These often retain their curvature parallel * Sorby has suggested the probably partial vegetal mode of life of S. viridis, and resultant analogy to Dionea. (“ Quart. Journ. Micro. Sci.,” 1875, p. 51.) 454 Mr. P. Geddes. Observations on the [Mar. 27, to the unaltered cilia, and I have even seen the finer pseudopodia con- tracting gently in time with the cilia of the same cell, thus establishing’ a complete gradation between the rhythmically contractile cilium and the amceboid pseudopodium through what is really arhythmically con- tractile pseudopodium. Heckel and others have accumulated many instances of the transformation of ciliary movement into amceboid and vice versa, but I only know of one case in which the passage-form, the cilium-like pseudopodium, has been actually observed. Lankester,* speaking of developing spermatozoa of Tubifex, describes ‘‘ very large active fusiform masses, exhibiting very rapid movements hke a cilium, and possessing at the same time the character of a pseudopodium.” It is important that Lankester’s passage-form occurred during the trans- formation of amceboid movement into ciliary, while I find exactly the same thing during the reverse change; and it is not improbable that such ciliary pseudopodia may transitorily occur in many cases. Perhaps no animal structure has received more varied and contra- _dictory interpretations than the rod-like bodies (Stabchen, baguettes) of the Planarian integument. ‘“‘ Max Schultze holds them for end-organs of nerves, Leuckart and many others for nettle-capsules, Schneider for spicula amoris, Keferstein for mucous glands, Graff for more or less developed nematocysts.”f Two distinct kinds of organ exist in Convoluta and other Rhabdocceles, and have been confused under the same name; first, the heap of coloured rod-shaped bodies, the original “Stabchen” of Max Schultze, which furnish in Convoluta the yellow solution already referred to, and, secondly, large and long spindle- shaped bodies, generally arranged singly, each containing a sharp brittle needle, of which the point lies close under the apex of the spindle. In a teased preparation they are generally empty, showing the tube in which the arrow lay, and with a little granular protoplasm hanging round the mouth like the smoke of the explosion. The dart is gene- rally propelled for some little distance, but sometimes sticks in the mouth of the tube. Graff's view { is certainly the right one, that these are offensive weapons, but they are constructed on so distinct a plan from those of Ccelenterates, that they might better be called sagittocysts than nematocysts. True nematocysts have been described in some other Planarians. Below the epidermis lie the circular and longitudinal muscles, and beneath them comes the layer of chlorophyll-containing cells. These are clear and semi-fiuid, more or less irregular in shape, but becoming spherical when separated.. The chlorophyll is not collected into eranules as in the higher plants, nor into drops as in the green cells of Vortex viridis, but ‘is diffused throughout the whole pro- * “ Quart. Journ. Micro. Sci.,” 1870, p. 292. + Minot, “Studien an Turbellarien,” “Semper’s Archiy,”’ III, 4, 1877. ft “Zeitsch. f. w. Zool.,”’ xxv, p. 421. 1879.] Physiology and Histology of Convoluta Schultzii. 455 toplasm of the cell, which is thus very intensely coloured. One, or sometimes two, nuclei are present, besides an irregular heap of granules. It was very difficult to break up the cell completely, and so liberate the granules, but in one or two fortunate preparations treated with iodine, the blue coloration assumed by many of these _ granules proved that we have here an actual deposit of starch, quite like that which Sachs has shown to take place within the chlorophyll granules of the plant. These starch granules are many of them so minute as to show Brownian movements; the larger are quite amorphous, and consequently exhibit no polarisation. Deeper than the green layer, lie colourless granular nucleated cells, which may be spherical or branched. These yield with iodine the red-brown reaction of glycogen very conspicuously indeed. All the internal tissues of the animal are bathed in that abundant slimy protoplasm which-has been so often adduced in evidence of the infusorian affinities of the lower Turbellaria. It exudes from all points of the body of a squeezed Convoluta in hyaline drops, which generally enclose a heap of cells of all sorts, and which often show amceboid movements. This semi-fluid protoplasm oozing through the loose cell meshes with every movement of the body may well serve instead of a special circulatory fluid. Digestion may also be effected by the amceboid protoplasm, for it is easy to confirm the statements of Claparéde, Metschnikoff,* Ulianin,+ and Graff,t as to the absence of any distinct alimentary canal. The development of the generative products is of interest. An apparently ordinary mesoderm cell enlarges and divides into an oval mass of about 12—16 segments. The granular protoplasm of these is gradually drawn out into the very long spermatozoa, and thus each testicular mass is transformed bodily into a bundle of neatly folded spermatic filaments. The ova are also developed by the division of a mesoderm cell. There are no separate vitellaria, but the yolk granules seem to arise in the finely granular amoeboid protoplasm of the developing ovum. The “ otolith” is transparent and Stamey refracting. It is loosely contained in a capsule and shaped like a plano-convex lens, but with the plane under surface very rugged. I can form no hypothesis as to its function. In some forms what appears to be a nucleus is present, and the body is probably a modified epithelial cell. Everywhere imbedded in the mesoderm are numerous small colour- less cells scarcely so big as a frog’s red blood corpuscle. These are more or less pear-shaped, with a large central cavity; and lining one * “ Zoologischer Anzeiger,” 1878, p. 387. + “Die Turbellarien vom Bucht von Sebastopol.’ Moscow, 1870. ~ “Kurze Ber. iiber fortgesetzte Turbellarienstudien,” Zeitch. f. w. Zool., xxx, Supp., p. 463. 456 Physiology and Histology of Convoluta Schultz. [Mar. 27, side of the interior of this cavity and parallel to the long axis of the cell, are a number of distinct transparent homogeneous filaments in- serted above and below into the ordinary granular protoplasm which constitutes the remainder of the cell. This division of the cell into a granular and a fibrillated portion is similar, as Dr. Malassez suggested to me, to that which obtains in the developing muscular cell of a tadpole’s tail, and though also somewhat remotely, to the structure described by Lankester in the heart of Appendicularia.* In a teased preparation, some of these cells are easily found in a state of rapid rhythmical contraction, giving as many as 100—180 energetic beats per minute. The form of the cell alters with every pulsation, shortening and broadening like a contracting muscle. This change of form is simply impressed upon the cell body by the contraction of the internal fibres, and does not therefore truly correspond to that observed in a muscle. Some cells also of extreme curvature (for hardly any two are quite alike) bend sharply and return with a spring. The movements soon become slow and inco-ordinate, and waves can be seen passing along the separate fibres independently of each other. The movement stops altogether and the cell bursts, but the fibres resist for some time longer the destructive action of the water. I have never been able to observe any rhythmical contraction, but at most a feeble quivering within the cell while in the body of the animal, nor to make out any trace of definite arrangement. Max Schultze has described how the alimentary canal of the higher Pla- narians swarms with Opaline, and it is possible that these so singular structures may be excessively modified parasitic Infusoria. In any case, the main histological interest lies in the fact that these pulsatile cells cannot be classified either with ciliary or amceboid, with plain or striated muscular cells, but present a distinct type of contractile structure. Tn one of these bodies, which had come to rest in the characteristic curved pear-like form, the nucleus-like body, which is often to be seen at one side, was distinctly seen to be in motion. It slowly dived under the contractile filaments, and moved steadily towards the opposite side, displacing the fibres slightly as it pushed its way. When it had reached the middle the cell had straightened into a per- fectly symmetrical pear-shape, and by the time it had reached the opposite side the cell had curved to the same side. Aftera momentary pause it commenced to go back again, and the oscillation of this singular body along the transverse diameter of the cell, with the accompanying changes of form of the whole, continued with perfect steadiness for at least half an hour, enabling me to draw all the phases again and again. One whole oscillation occupied a little over a minute. * «© Ann, and Mag. Nat. Hist.’’ 1873, p. 88. + Figures will be published in the “ Archives de Zoologie Expérimentale.” 1879. | Presents. 457 IT must express my warmest thanks to M. de Lacaze-Duthiers, in whose laboratories at Roscoff and Paris I have received the greatest hospitality. 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Proceedings. 1878. No. 7-8. .8vo. The Society. Calcutta:—Geological Survey of India. Records. Vol. XI. Part IV. 4to. 1878. The Survey. Hdinburgh:—Royal Society. Transactions. Vol. XXVIII. Part IT. Ato. 1878. Proceedings. Session 1877-78. 8vo. 1878. The Society. London :—Odontological Society. Transactions. Vol. X. No. 8. Vol. XI. No. 1-3. 8vo. 1878-9. The Society. London:—Royal Astronomical Society. Monthly Notices. Vol. XXXVIII. No. 9. Vol, XXXIX. No. 1-4. 8vo. 1878-79. The Society. 460 Presents. [ Mar. 27, Transactions (continued). ? Montreal :—Natural History Society. Canadian Naturalist and Quarterly Journal of Science. New Series. Vols. VII-VIII. Svo. 1878. The Society. Paris:—Muséum d’Histoire Naturelle. Nouvelles Archives. 2° Série. Tome I. Fasc. 1-2. 4ito. 1878. The Museum. Toronto :—Canadian Institute. Canadian Journal of Science, Literature, and History. Vol. XV. No. 8. 8vo. 1878. The Institute. Toulouse :—Académie des Sciences, Inscriptions et Belles Lettres. Mémoires. 7° Série. Tome X. 8vo. 1878. The Academy. Carruthers (Rev. G. T.) New Solar Element. 8vo. Nagpur 1879. The Author. Harris (John.) Two Lectures on the Circle and the Straight Line. Lecture I. 4to. London 1879 (two copies). Geometrical Demonstra- tion of the Ratio of the Circle’s Circumference to the Diameter. 4to. 1879 (two copies). The Author. McCoy (F.) Prodromus of the Paleontology of Victoria. Decade V. roy. 8vo. Melbourne 1877. The Geological Survey of Victoria. Wartmann (H.) Rapport du Président de la Société de Physique et d’Histoire Naturelle de Genéve, pour la période du 1° Juillet 1877 au 31 Décembre, 1878. 4to. The Society. Presents, March 27, 1879. Transactions. Batavia :—Bataviaasch Genootschap van Kunsten en Wettens- chappen. Verhandelingen. Deel 39. Stuk 1. roy. S8vo. 1877. Tijdschrift voor Indische Taal-Land-en Volkenkunde. Deel 24. Afl. 4-6. Deel. 25. Afl. 1. 8vo. 1877-78. Notulen van de Algemeene en Bestuurs-Vergaderingen. Deel 10. No. 1-4. Deel 16. No. 1-2. 8vo. 1877-78. Gedenkboek van het 100 jarig Bestaan van het Genootschap. Deel 1. 4to. 1878. Feestverslag. 4to. 1878. Tweede Vervolg-Catalogus der Bibliothek. 8vo. 1877. The Society. Berlin :—Koniglich-Preussische Akademie der Wissenschaften. Politische Correspondenz Friedrich’s des Grossen. Band 1. Ato. 1879. | The Academy. Brussels :—Musée Royal d’ Histoire Naturelle de Belgique. Annales. Tome I. JDescription des Ossements Fossiles des Environs d’Anvers, par P. J. van Beneden. 1° partie (avec un Atlas.) 1879. ] Presents. AGL Transactions (continued). Tome II. Faune du Calcaire Carbonifére de la Belgique, par L. G. de Koninck (avec un Atlas.) Folio. Bruwelles 1877-78. The Museum. London :—Physical Society. Proceedings. Vol. II. Part V. 8vo. SVE The Society. Paris :—Société Francaise de Physique. Séances, Juillet-—Décem- bre 1878. 8vo. The Society. Trieste :—Societa Adriatica di Scienze Naturali. Bollettino. Vol. IV. No. II. 8vo. 1879. The Society. Reports, &c. London :—Army Medical Department. Report for the year 1877. Wolk XiExX. Svo, 1879. The Department. Paris :—Bureau des Longitudes. Connaissance des Temps pour |’an 1880. 8vo. 1878. Annuaire. 1879. 12mo. The Bureau. Loewy (M.) Ephémérides des Etoiles de culmination lunaire et de Longitude pour 1879. 4to. Paris 1878. The Author. et I’. Perrier. Détermination Télégraphique de la différence de la Longitude entre Paris et Observatoire du Depot de la Guerre 4 Alger (Colonne Voirol). 4to. Paris 1877. The Authors. et — Stephan. Détermination de la Différence des Longitudes entre Paris-Marseille et Alger-Marseille. Paris 1878. } The Authors. Siragusa (fF. P.C.) L’Anestesia nel Regno Vegetale. 8vo. Palermo 1879. The Author. April 3, 1879. THE PRESIDENT in the Chair. The Presents received were laid on the table, and thanks ordered for them. The Right Hon. Richard Assheton Cross, whose certificate had been suspended as required by the Statutes, was balloted for and elected a Fellow of the Society. Pursuant to notice, Arthur Auwers, Luigi Cremona, Jean Louis VOL. XXVIII. 2M 462 On the Thermal Conductivity of Water. [ Apr. 3, Armand de Quatrefages, Georg Hermann Quincke, Theodor Schwann, and Jean Servais Stas were balloted for and elected Foreign Members of the Society. The following Papers were read :— I. “On the Thermal Conductivity of Water.” By J. T. Bort- TOMLEY, Lecturer in Natural Philosophy and Demonstrator in Experimental Physics in the University of Glasgow. Communicated by Professor Sir WILLIAM THomson, LL.D., F.R.S. Received March 11, 1879. (Abstract.) The experiments described in this paper were undertaken at the instance of Sir William Thomson and by a method devised by him. The liquid whose thermal conductivity is to be determined is heated from above, to avoid convection currents. Two methods of heating have been used. In one, a horizontal steam chamber is applied at the top of the water or other liquid ; and, steam being continuously passed through the heating chamber, the surface of the liquid under experi- ment is kept at a very high temperature, and heat is conducted from above downwards. In the other method a large quantity of very hot water is deposited on the top of a mass of cold water, mixing being prevented by a simple contrivance; and the heat of this super- incumbent layer is conducted downwards through the colder water below. The experiments have been carried on in very large vessels, or tanks, in order to avoid disturbance by means of loss of heat at the sides. It is intended, at the suggestion of Professor Clerk Maxwell, to observe the loss of heat by the sides under given circumstances, and to estimate, from results of such experiments, the probable error due to this loss. In the experiments three principal thermometers are employed; together with a fourth, whose object is merely to show when heat begins to be lost at the bottom of the layer of fluid experimented on. When this loss commences the experiment is at an end. The other three thermometers are used thus :—First there is a thermometer with a bulb 30 centims. long. It is placed vertically; and its object is to show the average temperature from top to bottom of the layer of fluid bounded by horizontal planes passing through the top and bottom of its bulb. The rise of this thermometer in any time shows the quantity of heat that has passed into the stratum occupied by it in that time. The other two thermometers are placed with their bulbs horizontal, and one at a known distance vertically above the 1879.] Mr. G. Matthey. On the Platinum Serves. 463 other. They indicate the temperatures of the layers in which they are placed. Now, if we know the difference of temperatures of two sides of a stratum of a liquid during any time, and the quantity of heat con- ducted across the stratum during that interval of time, we can calculate the thermal conductivity of the liquid by means. of a well- known formula. The result arrived at by the experiments described, is that the thermal conductivity of water may be taken at from ‘0022 to ‘00245 in square centimetres per second. Some experiments have been made on the thermal conductivity of solution of sulphate of zinc, a solution which happened to be con- venient for preliminary trials. The specific heat of solution of sulphate of zinc at different densities, which it is necessary to know for comparison as to thermal conductivity of that. liquid with water, has been determined. Experiments are now being: carried on on this subject with the assistance of a grant from: the Government Fund of 4,000J. II. “The Preparation in a State of Purity of the Group of Metals known as the Platinum Series, and Notes upon the Manufacture of Iridio-Platinum.” By GrorceE MarTtTHEy. Communicated by F. A. ABet, C.B., F.R.S. Received March 19, 1879. In this paper it is not my intention, nor should I be able, to refer generally to the results of work in the various branches of platinum metallurgy carried out by my firm, who, as is well known, have been associated with the development of this special field of industry from its earliest infancy; but I shall confine myself simply to that section of it upon which my personal attention has of late years been speci- fically concentrated in order to.meet and comply with the requisition of the Bureau Internationale des Poids et Mesures, the Section Frangaises de la Commission Internationale du Métre,. and of lAsso- ciation Géodésique Internationale (all of them important scientific committees, formed with the object of arriving at an accurate and definite solution of the long agitated question of standard weights and measures), and also.at the demand of the French Minister of War, for an alloy the best adapted for the manufacture of the international metre and kilogram standard, and the geodesique rule; and in my endea- vour to solve this difficult problem I have had the great advantage of being able to consult those distinguished men, M.M. Henri Sainte Claire Deville and Henri Debray, of Paris, and have also had the 22 464 Mr. G. Matthey. On the Preparation of the [Apr. 3, benefit of the excellent and valued advice of M. Stas, the celebrated Belgian chemist, to all of whom the scientific world owe so much, and to whom I desire to offer my warmest thanks. In a paper of this kind it would be superfluous for me to enter into any of the already published details concerning the existence and collection of what is known as platinum-dust or mineral. It is suffi- cient for me to observe that the six metals (of which platinum is the chief) usually found more or less in association in their native state, present characteristics of interest beyond their metallurgical utility, which are, perhaps, worth alluding to en passant. It is, for instance, a curious fact that the group should consist of three light and three heavy metals, each division being of approximately the same specific gravity—the heavier being (in round figures) just double the density of the lighter series. Thus we find osmium, iridium, platinum forming the first division, of the respective specific gravities of 22°43, 22°39, 21-46; whilst ruthenium, rhodium, and palladium are represented by the figures 11:40, 11°36, 11, the average densities of the heavy and light divisions thus being respectively 22°43 and 11°25. But a more interesting and important classification is what I may designate as a first and second class series, from the more important view of their relative properties of stability. Thus platinum, palla- dium, and rhodium form the first or higher class, not being volatiliz- able in a state of oxide ; iridium, osmium, and ruthenium forming the second or lower class, their oxides being more or less readily volati- lized, The oxide of iridium is affected at 700 to 800° C., and entirely decom- posed at 1,000°, whilst osmic and hyporuthenic acids are volatilized at the low degree of 100°, the latter exploding at 108°. The chlorides of these metals can be sublimed at different temperatures (as also the protochloride of platinum). I now propose to give a short description of the methods I have employed for preparing the pure platinum and iridium necessary for the manufacture of the alloy, which I call “ iridio-platinum,” and it is upon the distinguishing characteristics above-mentioned that my method of separation is chiefly founded. Platinum. The preparation of this metal to a state of purity is an operation of extreme delicacy. I commence by taking ordinary commercial platinum ; I melt this with six times its weight of lead of ascertained purity. and, after granulation, dissolve slowly in nitric acid diluted in the proportion of 1 volume to 8 of distilled water. The more readily to ensure dissolution, it is well to place the granulated alloy in porcelain 1879. ] Group of Metals known as the Platinum Series. — 465 baskets such as are used in the manufacture of chlorine gas for holding the oxide of manganese. When the first charge of acid is sufficiently saturated, a fresh quantity should be added until no more action is apparent; at this stage the greater part of the lead will have been dissolved out together with a portion of any copper, iron, palladium, or rhodium that may have been present. These metals are subsequently extracted from the mother-lquors, the nitrate of lead by erystallization, and the remaiming metals. by well-known methods. The metallic residue now obtained will be found in the state of an amorphous black powder (a form most suitable for further treatment), consisting of platinum, lead, and smal! proportions of the other metals originally present—the iridium existing as a brilliant crystalline sub- stance insoluble in nitric acid. After digesting this compound in weak aqua regia, an immediate dissolution takes place of the platinum and lead, leaving the iridium still impure, but effecting a complete separation of the platinum. To the chloride of platinum and lead after evaporation is added sufficient sulphuric acid to effect the precipitation of the whole of the lead as a sulphate, and the chloride of platinum after dissolution in distilled water is treated with an excess of chloride of ammonium and sodium, the excess being necessary in order that the precipitated yellow double salt may remain in a@ saturated solution of the pre- cipitant. The whole is then heated to about 80°, and allowed to stand for some days; the ammonio-chloride of platinum will settle down as a firm deposit at the bottom of the vessel, whilst if any rhodium, as is generally the case, is present, the surface liquor will be coloured a rose tint, occasioned by a combination of the salts of the two metals. The precipitate must be repeatedly washed with a saturated solu- tion of chloride of ammonium and subsequently with distilled water charged with pure hydrochloric acid. This is necessary for its puri- fication. The small quantity of the double salt which will be taken up and held in solution is of course recovered afterwards. Rhodium may still exist in the washed precipitate, which must therefore not be reduced to the metallic state until its separation is completed, and this is best effected by mixing with the dried compound, salts of chloro-platinate and chloro-rhodiate of ammonia, bi-sulphate of potash with a small proportion of bi-sulphate of ammonia, and subjecting to a gradual heat brought by degrees up to a dull redin a platinum capsule, over which is placed an inverted glass funnel. The platinum is thus slowly reduced to a black spongy porous condition freed from water, nitrogen, sulphate of ammonia, and hydrochloric acid, the rhodium remaining in a soluble state as bi-sulphate of rhodium and potash, which can be dissolved out completely by digesting in boiling distilled water ; a small quantity of platmum will have been taken up in a state of sulphate, but is regained by heating the residue (obtained 466 Mr. G. Matthey. On the Preparation of the [Apr. 3, on evaporation) to redness, at which heat it is reduced to the metallic condition, the rhodium salt remainmg undecomposed. By the method above described the platinum is freed not only from rhodium, but from all other metals with which it may have been con- taminated, and is brought to a state of absolute purity, of the density 21:46, the highest degree obtainable. Iridium. In the preparation of this metal when intended to be used for the ~manufacture of iridio-platinum alloy, I have arrived at freeing it to the utmost possible extent from all its associate metals, except plati- num, disregarding the presence of the latter ; the proportion of which, once determined, would only form matter of calculation in the final operation of mixing my alloy. In practice, the purest iridium which can be obtained from its ordinary solution (deprived of osmium by long boiling in aqua regia and precipitated by chloride of ammonium) will almost invariably contain traces of platinum, rhodium, ruthenium, and iron. I fuse such iridium in a fine state of division with ten times its weight of lead, keeping it in a molten state for some hours, dissolve out the lead with nitric acid, subject the residue to a prolonged digestion im aqua regia, and obtain a crystalline mass composed of iridium, rhodium, ruthenium, and iron, in a condition suitable for my further treatment. By fusion at a high temperature with an ad- mixture of bi-sulphate of potash, the rhodium is almost entirely removed, any remaining trace being taken up together with the iron in a later operation. The iridium so far prepared is melted with ten times its weight of dry caustic potash, and three times its weight of nitre, in a gold pan or crucible; the process being prolonged for a considerable time te effect the complete transformation of the material into iridiate and ruthenate of potash, and the oxidation of the iron; when cold, the mixture is treated with cold distilled water. The iridiate of potash of a blue tinge will remain as a deposit almost insoluble in‘ water, more especially if slightly alkaline, and aiso the oxide of iron. This precipitate must be well washed with water charged with a little potash and hypochlorite of soda until the washings are no longer coloured, and then several times with distilled water. The blue powder is then mixed with water strongly charged with hypochlorite of soda, and allowed to remain’ for a time cold, then warmed in a distilling vessel, and finally brought up to boiling point until the distillate no longer colours red, weak alcohol acidulated with hydrochloric acid. The residue is again heated with nitre and potash water charged with hypochlorite of soda and chlorine, until the last trace of ruthenium has disappeared. 1879. | Group of Metals known as the Platinum Series. 467 Further, to carry out the purification, the blue powder (oxide of iridium) is re-dissolved in aqua regia, evaporated to dryness, re-clis- solved in water, and filtered. The dark-coloured solution thus obtained is slowly poured into a concentrated solution of soda and mixed with hypochlorite of soda, and should remain as aclear solution without any perceptible pre- cipitate, and subjected in a distilling apparatus to a stream of chlorine gas, should not show a trace of ruthenium when hydrochloric acid and alcohol are introduced into the receiver. In this operation the chlorine precipitates the greater part of the iridium in a state of blue oxide, which after being collected, washed, and dried, is placed in a porcelain or glass tube, and subjected to the combined action of oxide of carbon and carbonic acid obtained by means of a mixture of oxalic with sulphuric acid gently heated. The oxide of iridium is reduced by the action of the gas leaving the oxide of iron intact, the mass is then heated to redness with bi-sulphate of potash (which will take up the iron and any remaining trace of rhodium) and after subjecting it to many washings with distilled water, the residue is washed with chlorine water to remove any trace of gold, and finally with hydrofluoric acid, in order to take out any silica which might have been accidentally introduced with the alkalies employed or have come off the vessels used. The iridium after calcination at a strong heat in a charcoal crucible, is melted into an ingot, and after being broken up and boiled in hydrochloric acid, to remove any possible trace of iron adhering to it through the abrasion in breaking up, should possess if perfectly pure a density of 22°39; but, as iridium prepared even with the utmost care will still contain minute though almost inappreciable traces of oxygen, ruthenium, rhodium, and possibly iron, the highest density I have yet attained is 22°58. Alloy of Iridio Platinum. This compound metal possesses physical properties of great value, forming a beautiful example of the effect of a careful combination of the opposite characteristics of its component parts. Thus, the extreme softness and expansiveness of pure platinum and the brittle- ness and excessive hardness of pure iridium, produce, by combination in judicious proportions, a perfect and homogeneous alloy, possessing the necessary mean of these properties to render it suitable for many important purposes, amongst others that of the special object to be attained to meet the requirements for an unalterable standard meial, for which it is peculiarly adapted. In the manufacture of the prototype metres and the geodesique rules (each 4 metres in length) ordered from my firm by the Comité Internationale des Poids et Mesures, the Association Géodésique In- 468 Mr. G. Matthey. On the Preparation of the [ Apr. 3, ternationale, and the French Minister of War, I proceeded in the following manner with the platinum and iridium prepared as described above. Operating upon a charge of 450 ounces of platinum and 55 ounces of iridium, I commenced by melting these metals together and casting into an ingot of suitable shape, which I then cut into small pieces with hydraulic machinery. After re-melting and retaining in a molten condition under a powerful blast of oxygen and common gas for a considerable time, I re-cast and forged at an intense white heat under a steam hammer, the highly polished surfaces of which were cleaned and polished after each series of blows—when sufficiently reduced it was passed through bright polished steel rollers, cut into narrow strips, and again slowly melted in a properly shaped mould, in which it was allowed to cool. I thus obtained a mass of suitable shape for forging, perfectly solid, homogeneous, free from fissures or air-holes, and with a bright and clean surface at bottom and sides as at top. At the first forging a bar was obtained 35 centims. long, 7°5 wide, 2°5 thick, which weighed— Iki G02 S Gono dckodoosddo 40 15°105 grms. inewiater iat (Oa ejects 14405 ,, Showing a density at zero of 21°522 A third of the bar was cut off and the larger portion again forged to a length of 95 centims., width 2°5, thickness 2:0, which weighed— DSA epee och Sit cs arane tence stele ere 10°814 grms. In water at 60° Fo... 2... 1OSi57 Showing a density at zero of 21°648 This was then passed through highly polished rolls until of a length of 4,010 centims. 21 millims. in width, and 5 millims. thick, to which a perfectly rectangular form was subsequently given by draw- ing it through a series of plates, and thus prepared the rule was in a . condition to receive the beautiful polish of which this alloy is sus- ceptible. , After passing it through each hole the metal was annealed by means of a jet of gas and oxygen to a heat just below melting point, and each time throughout after forging, rolling, and drawing was exposed to the action of melted borax, and boiled in concentrated hydrochloric acid to reniove any possible trace of adherent iron or other impurity. A piece cut from the end and presented to the French Academy of Science gave the following results :—~— Weight im air. 354.12: 116°898 grms. 55 water vesss | TLA69) ae Showing a density of.. 21°516 1879. ] Group of Metals known as the Platinum Series. 469 thus proving that the necessary processes of annealing at a high temperature had caused it sensibly to resume its original density. The analysis gave— nie 2 Plot, es Fas. 89°40 89°42 br rehiormy eF ahs) Ee 10°16 10°22 no dinamyh yes 2) 2 us" 0:18 0°16 Fmrbhenivem: sa s)2. 6 ; 0-10 0°10 irom Pea ds Ses 0-06 0:06 99:90 99°96 From which is deduced :— Proportion. Density at zero. Volume. Tridio-platinum, at 10 per cent. 99°33 21 °575 4: -603 evetum, 1m OXGeSS ../.62 05.3.6 0:23 22380 0-010 12) C17 370 a ses UA ee a ae 0°18 12 :000 0-015 Femuhemtuml se esels ee oe ee 0-160 12-261 0-008 rons. 2) Serenity aU cs Ma 0-06 7° 700 0-008 99-90 4.- 64.4; Density at zero, calculated after No. 1 analysis....21°510 Density at zero, calculated after No. 2 Kd kare FONE ay thus coinciding perfectly with the practical results obtained. Messrs. Leon Brunner Brothers, of Paris, who had submitted this material of the géodésique rule to a great number of mechanical experiments, communicated the result of their observations to M. H. Sainte-Claire Deville, thus :— Paris. 27 Aouv, 1873s ‘** MoNnSIEUR, “La division de la régle géodésique, que nous faisons pour |’As- sociation Géodésique Internationale, est terminée depuis quelques jours. “« Nous avons pensé que vous ne seriez pas mécontent d’apprendre que cette operation a parfaitement réussi, et que c’est au métal que nous attribuons la facilité avec laquelle nous avons pu lexécuter. ** Le platine iridié de M. Matthey est incontestablement supérieur au platine ordinaire, pour la confection des régles divisées. I] est exempt de ces pailles qu’on rencontre toujours dans ce dernier, et se laisse polir au charbon. On peut, sans danger, enlever les rébarbes des traits et les conserver trés beaux. Le platine ordinaire ne peut-étre poli qu’au papier a émeré, et lon est toujours exposé a gater la division quand on procéde a l’ébarbage. C’est:l4 un inconvénient trés-grave. “Nous ne pouvons que vous remercier, Monsieur, d’avoir mis a notre disposition un metal qui modifie singuliérement les difficultés 470 Mr. G. Matthey. On the Platinum Series. —_ [Apr. 3, qu’on rencontre dans la fabrication d’une régle géodésique, et nous vous prions de recevoir l’assurance de nos sentiments les plus dis- tingues. ‘* BRUNNER FRERES.” In the year 1876 the suggestion was made to supersede the rec- tangular form by a tubular one, and I was requested to produce one of the following dimensions: Length, 1,002 centims.; exterior diameter, 37 millims.; mterior diameter, 35 millims.; with rounded ends, one having an extension of small tube 4 millims. exterior diameter, 2 millms. interior diameter, 40 millms. long, which I did by the system of tube making with autogenous joints adopted by me with excellent results for the last 20 years, employing for the purpose an alloy prepared as above described. These proved to be so satisfactory that I have since made others, both round and square, of various dimensions, as lately shown at the Paris Exhibition. | Tridio-platinum alioy has now been proved to possess the following among many advantages for standard rules and weights :— It is almost indestructible, has extreme rigidity, especially in the tube form, and a most beautifully polished surface can be obtained upon it; its coefficient of elasticity is very great, whilst for standard weights its high density is a valuable quality, and for these I should indeed recommend an alloy of not less than 20 per cent. of iridium. I lately made at the request of M. H. Sainte-Claire Deville a cylinder 40 millims. by 40 millims. of such an alloy, which showed by analysis the following proportions) :— Platinum 72 eee sees 80-6600 ridin fe teste ee eee eee 19 ‘0786 Rhodium: eee ene -1220 Rathemumi is). eee -6460 Teron AaCoAe Ee Ree eee eas °0980 100° 0046 and gave the density of 21°614. With such a high density its coefficient of elasticity is 22°200000, one of the highest known, whilst its malleability and ductility are almost without limit. The volume of the kilogram thus prepared is only 46°266 cub. cemtims., it displaces 2-267 cub. centims. less than the kilogram of the archives of France, and on this account, as on many others, is of course preferable. The results I have arrived at in preparing alloys of higher grades, viz., 25—30—40 and 50 per cent. of iridium, are as follows :— The alloy of 20 per cent. iridium is, as I have stated already, mal- leable and ductile. 25 per cent. can only with great difficulty and waste be worked 1879.] On the Reversal of the Lines of Metallic Vapours. AT1 into sheet and wire when heated at low temperature. 30 per cent. and 40 per cent. with great difficulty only at a temperature little less than melting point, being brittle when cold, but with a groan of great beauty and Hagges. 50 per cent. I have as yet failed to work up into forms other than castings beyond what I can effect by pressure when in a semi-fused condition. The general results of my work on this alloy would lead me, there- fore, to make the following recommendations. For the manufacture of standard rules to use an alloy of not less than 85 per cent. platinum and 15 per cent. iridium, adopting the tubular form. For tke standard weights to use an alloy of not less than 80 per per cent. platinum and 20 per cent. iridium, adopting the form now generally made. Finally, following the expression of the great French chemist, M. Dumas, I hope by these labours “ d’avoir enriché l’outillage scientifique d’un alliage doué des propriétés précieuse.” III. “ On the Reversal of the Lines of Metallic Vapours.” No. VI. By G. D. Litvetne, M.A., Professor of Chemistry, and J. Dewar, M.A., F.R.S., Jacksonian Professor, University of Cambridge. Received March 27, 1879. The experiments described in the following communication were made with the electric arc, and in lime crucibles,* or in crucibles of a highly calcareous sandstone, kindly supplied to us by Messrs. Johnson, Matthey, and Co., as described in our fourth communication on this subject; but for some of them we used, instead of a galvanic battery, a magneto-electric machine producing a much more powerful current and a much longer arc. The experiments with this machine were made, through the kindness of Dr. Tyndall, at the Royal Institution, and we are indebted to Messrs. Siemens both for the working of the machine and for sparing to us the services of a skilled engineer, in * In our first paper on this subject, communicated in February, 1878, when re- ferring to the experiments of Lockyer and Roberts (‘‘ Proc. Roy. Soc.,’’ xxiii), we mentioned that they employed the combined action of a charcoal furnace and an oxy hydrogen blowpipe, but omitted to mention that they used a lime chamber after the model of Stas. Referring to fig. 1 in our communication of February 12, 1879, where the use of an oxyhydrogen blowpipe in a lime block is represented, we disclaim any novelty in the use of lime; the difference between our experiments and theirs con- sisting in this, that we use the continuous spectrum from the hot walls of our cruci- ble, instead of an external independent source of light, as a background against which the absorbent action of the vapours is seen, in the same way as we had previously used iron tubes, and now use the electric are. 472 Profs. Liveing and Dewar [ Apr. 3, the person of Mr. Oscar Doermer, whose assistance was most valuable. We wish to express our thanks to all these gentlemen for the facilities they so readily granted to us. The results obtained with the powerful current from the magneto- electric machine did not differ at all in kind from those obtained with the battery, and much less in degree than we had expected. We had really but one day’s work with this machine, which we can only regard as a preliminary trial of it, and, in the meantime, until we have the opportunity of a longer series of experiments with it, we communicate the results obtained to the Royal Society. Copper Electrode ji cere WY), Y Yj eS S -S OS) 1 Pubber tube Carbon i [i Hid roger? eames ss Alectrode In some cases we have introduced a current of hydrogen, or of coal-gas, into the crucibles by means of a small lateral opening, or by a perforation through one of the carbon electrodes ; sometimes the perforated carbon was placed vertically, and we examined the light through the perforation (see diagrams). When no such current of gas is introduced, there is frequently a flame of carbonic oxide burning at the mouth of the tube, but the current of hydrogen produces very marked effects. As a rule, it increases the brilliance of the con- tinuous spectrum, and diminishes relatively the apparent intensity of the bright lines, or makes them altogether disappear with the exception of the carbon lines. When this last is the case, the reversed lines are seen simply as black lines on a continuous background. The calcium line with wave-length 4226 is always seen under these circumstances as a more or less broad black band on a continuous background, and when the temperature of the’ crucible has risen sufficiently, the lines with wave-lengths 4434 and 4454, and next that with wave-length 4425, appear as simple black lines. So too do the blue and red lines of lithium, and the barium line of wave-length 5535, 1879.] on the Reversal of the Lines of Metallic Vapours. 473 appear steadily as sharp black lines, when no trace of the other lines of these metals, either dark or bright, can be detected. Dark bands also frequently appear, with ill-defined edges, in the positions of the well-known bright green and orange bands of lime. In the case of sodium, using the chloride, we have repeatedly reversed the pair of lines (5687, 5681) next more refrangible than the D group. In every case the less refrangible of the two was the first to be seen reversed, and was the more strongly reversed, as has also been observed by Mr. Lockyer. But our observations on this pair of lines differ from his in so far as he says that “the double green line of sodium shows scarcely any trace of absorption when the lines are visible,” while we have repeatedly seen the reversal as dark lines appearing on the expanded bright lines; a second pair of faint bright lines, like ghosts of the first, usually coming out at the same time on the more refrangible side. Using potassium carbonate, besides the violet and red lines which _had been reversed before, we saw the group, wave-lengths 5831, 5802, and 5782, all reversed, the middle line of the three being the first to show reversal. Also the lines wave-lengths 6913, 6946, well reversed, the less refrangible remaining reversed the longer. Also the group, wave-lengths 5353, 5338, 5319 reversed, the most refrangible not being reversed until after the others. Also the line wave-length 5112 reversed, while two other lines of this group, wave- lengths 5095 and 5081, were not seen reversed. Using hthium chloride, not only were the red and blue lines, as usual, easily reversed, and the orange line well reversed for a long time, but also the green line was distinctly reversed; the violet line still unreversed, though broad and expanded. Had this green line belonged to cxsium, the two blue lines of that metal which are so easily reversed could not have failed to appear; but there was no trace of them. In the case of rubidium, we have seen the less refrangible of the red lines well reversed as a black line on a continuous background, but it is not easy to get, even from the arc in one of our crucibles, sufficient light in the low red to show the reversal of the extreme ray of this metal. With charred barium tartrate, and also with baryta and aluminium together, we have obtained the reversal of the line with wave-length 6496, besides the reversals previously described. The less refrangible line, wave-length €677, was not reversed. With charred strontium tartrate, the lines with wave-lengths 4812, 4831, and 4873, were reversed, and by the addition of aluminium, the line wave-length 4962 was reversed for a long time, and lines wave-lenoths 4895, 4868, about, were also reversed. On putting calcium chloride into the crucible, the line wave-length 474. On the Reversal of the Lines of Metallic Vapours. [Apr. 3, 4302 was reversed, this being the only one of the well-marked group to which it belongs which appeared reversed. On another occasion, when charred strontium tartrate was used, the line wave-length 4877 was seen reversed, as well as the strontium line near it. Also the lines wave-lengths 6161, 6121, have again been seen momentarily reversed. | With magnesium, no new reversals of the lines of the metal have been observed by us; but when a stream of hydrogen or of coal-gas was led into the crucible, the line wave-length 5210, previously seen by us in iron tubes, and ascribed by us to a combination of magnesium with bydrogen, was regularly seen, usually as a dark line, sometimes with a tail of fine dark lines on the more refrangible side similar to the tail of bright lines seen in the sparks taken in hydrogen between magnesium points. Sometimes, however, this line (5210) was seen bright. It always disappeared when the gas was discontinued, and appeared again sharply on re-admitting the hydrogen. These effects were, however, only well-defined in crucibles having a height | of at least 3 inches above the arc. On putting a fragment of metallic gallium into a crucible, the less refrangible ne, wave-length 4170, came out bright, and soon a dark line appeared in the middle of it. The other line, wave-length 4031, showed the same effect, but less strongly. In the cases of cadmium and copper, though we have made no thorough examination of them, we can corroborate the results arrived at by Cornu. We noticed particularly the disappearance in the arc of the cadmium lines, with wave-lengths 5377 and 5336. On the addition of aluminium to either copper or silver in our lime crucibles, we noticed that the copper or silver lines which had been previously predominant, almost faded away, while the calcium lines came out instead with marked brillianey. In no case could we detect the red lines of aluminium in the arc. With a view to re-introduce into the arc the magnesium line wave- length 4481, we tried the action of an induction spark in a lime crucible simultaneously with the arc, but without success; for the conducting power of the hot walls of the crucible, and the highly expanded gases within it, caused the resistance to be so much diminished, that the spark passed as in a highly rarefied medium. In order to succeed with this experiment, it seems plain that it must be made in an apparatus which will allow of its being performed under a pressure of several atmospheres. Reviewing the series of reversals which we have observed, we may remark that in many cases the least refrangible of two lines near together is the most easily reversed, as has been previously remarked by Cornu. Thus, in the case of barium (though there is no very distinct grouping of the lines of that metal) taking the rays in order, we have 1879.] On the unknown Chromospherice Substance of Young. 475 the line wave-leneth 5535 readily reversed, while that with wave- length 5518 is less easily reversed; the line wave-length 4933 ig comparatively easily reversed, whereas that with wave-length 4899 has not been reversed by us. On the other hand, the line wave-length 4553 has been reversed, but not the line wave-length 4524, In the case of strontium, the lines wave-length 4831 and 4812 have been reversed, but not the line wave-length 4784, and the two lines wave- length 4741 and 4721 remain both unreversed. In the group of five lines of calcium, wave-length 4318 to 4282, it is only the middle line wave-length 4302 which has been reversed. Of the potassium groups of lines wave-length 5831 and 5782, 5802, 5782 are reversed, the line wave-length 5811 has not been reversed, and of the others the line wave-length 5802 is the first to appear reversed. It is worthy of remark that the first of these lines is faint and the last is the brightest of the group. The group wave-length 5355, 5336, 5319 have been all reversed, but the last of the three (5319) was the most difficult to reverse: it is also the feeblest of the group. In the more refran- gible group, wave-length 5112, 5095, 5081, the least refrangible is the only one reversed. Making a general summation of our results respecting the alkaline earth metals, potassium, and sodium, and having regard only to the most characteristic rays, which for barium we reckon as 21, for strontium 34, for calcium 37, for potassium 31, and for sodium 12, the reversals in our experiments number respectively 6, 10, 11, 18, and 4. That is in the case of the alkaline earth metals about one-third, and these chiefly in the more refrangible third of the visible spectrum, the characteristic rays remaining unreversed in the more refrangible part of the spectrum being respectively 2,5, and 4. In the case of potassium we reversed two in the upper third, all the rest in the least refrangible third. These experiments relate to mixtures of salts of these metals combined with the action of reducing agents. In a future communication we will contrast these results with those of the isolated metals, calcium, strontium, and barium. IV. “ Note on the unknown Chromospheric Substance of Young.” By G. D. Livetne, M.A., Professor of Chemistry, and J. Dewar, M.A., F.R.S., Jacksonian Professor, University of Cambridge. Received March 27, 1879. In the preliminary catalogue of the bright lines in the spectrum of the chromosphere published by Young in 1861, he calls special attention to the lines numbered 1 and 82 in the catalogue, remarking that “‘they are very persistently present, though faint, and can be dis- tinctly seen in the spectroscope to belong to the chromosphere, as such, not being due, like most of the other lines, to the exceptional elevation 476 On the unknown Chromospheric Substance of Young. [ Apr. 3, of matter to heights where it does not properly belong. It would seem very probable that both these lines are due to the same aepaianeS which causes the D, line.”’ Again, in a letter to ‘‘ Nature,” June, 1872, Young says, “I confess I am sorry that the spectrum of iron shows a bright line coincident with 1474 (K); for, all things considered, I cannot think that iron vapour has anything to do with this line in the spectrum of the corona, and the coincidence has only served to mislead. But there are in the spectrum many cases of lines belonging to the spectra of different metals coinciding, if not absolutely, yet so closely, that no existing spectroscope can separate them, and I am disposed to believe that the close coincidence is not accidental, but probably points to some phy- sical relationship, some similarity of molecular constitution perhaps, between the metals concerned. . . . So, in the case of the green coronal matter, is it not likely that though not iron it may turn out to bear some important: relation to that metal?” In 1876 he proves that the coronal line 1474 is not actually coincident with the line of iron. In the catalogue of bright lines observed by Young at Sherman in the Rocky Mountains, to which we have directed special attention in one of our previous communications, it appears that the above-men- tioned lines 1 and 82, along with D;, were as persistently present as hydrogen, the only other line approaching them in frequency of occur- rence being the green coronal line 1474 of Kirchhoff, which was present on 90 occasions out of 100. It has occurred to us that these four lines may belong to the same substance. An analogy in the ratio of the wave-lengths of certain groups of lines occurring in diffe- rent metals has been already pointed out by Stoney, Mascart, Salet, Boisbaudran, and Cornu; and without any special reductions, or claims to an exact ratio in whole numbers, the following analogies are worthy of note :— Hydrogen. Lithium. Magnesium. ee ae Wave-length :— (1) 6563°9 (1) 6706 (1) 5183 (1) 7055 * (2) 4862-1 (2) 6102 (2) 3837°8 (2) 5874°9 (3) 4340 (3) 4970 (3) 3335 (3) 5315°9 (4) 4102 -4 (4) 4604 (4) 4471-2 (5) 4130 Ratio of wave-length of— HM Q6¢4 |0@e6 | OO ® 1M @&@ Ph aa) A) Oy | Eo 20 26°9 31°6 20) 127 $31 20 26°5 31°6 * This wave-length is not so accurately known as the other rays belonging to the chromosphere. O79.) Molecular Physics in High Vacua. ATT The ratio of the wave-lengths of F to G of hydrogen ((2) to (3) in the table above) is nearly identical with the ratio of D; to the coronal green line ((2) to (3) in table above). This near coincidence in the ratios of certain lines of hydrogen, lithium, and magnesium, substances belonging to the same type, com- bined with a similar ratio in. the wave-lengths of the nearly equally persistent lines of the chromosphere, greatly strengthens the probability of the assumption that these lines belong to one substance. The fact that the two less refrangible rays have no representative in the Fraunhofer lines, is by no means opposed to their belonging to one substance, since we know that aluminium behaves in a similar way in the atmosphere of the sun; and in the total eclipse of 1875 the hydrogen line # was not visible in the chromosphere, that is, we suppose, was on the limit between brightness and reversal; and during the late eclipse the two most refrangible rays of hydrogen were not detected from the same cause. Until our knowledge of the order of reversibility of lines belonging to different types of metals has been extended, it would be rash to infer the group of metals to which it belongs, or its probable molecular weight. V. “Contributions to Molecular Physics in High Vacua.” By WILLIAM CROOKES, F.R.S. Received March 27, 1879. (Abstract. ) This paper is a continuation of one ‘‘ On the Illumination of Lines of Molecular Pressure, and the Trajectory of Molecules,” which was read before the Royal Society on the 5th of December last. The author has further examined the action of the molecular rays electrically pro- jected from the negative pole in very highly exhausted tubes, and finds that the green phosphorescence of the glass (by means of which the presence of the molecular rays is manifested) does not take place elese to the negative pole. Within the dark space there is absolutely no phosphorescence ; at very high exhaustions the lammous boundary of the dark space disappears, and now the phosphorescence extends all over the sensitive surface. Assuming that the phosphorescence is due either directly or indirectly to the impect of the molecules on the phosphorescent surface, it is reasonable to suppose that a certain velocity is required to produce the effect. The author adduces arguments to show that within the dark space, at a moderate ex- haustion, the velocity does not accumulate to a sufficient extent to produce phosphorescence, but at higher exhaustions the mean free path is long enough to allow the molecules to get up sufficient speed VOL. XXVIII. 2N A78 Mr. W. Crookes on [Apr. 3, to excite phosphorescence. Ata very high exhaustion there are fewer collisions, and the initial speed of the molecules close to the negative pole not being thereby reduced, phosphorescence takes place close to the pole. Experiments are described in which a pole folded into corrugations is used at one end of a tube, the pole at the other end being flat set obliquely to the axis of the tube, and having a plate of mica in front pierced with a hole opposite the centre of the pole. The questions which © this apparatus was designed to answer are:—(1.) Will there be two sets of molecular projections from the corrugated pole when made negative, one perpendicular to each facet, or will the projection be perpendicular to the electrode as a whole, 7.e., along the axis of the tube P (2.) Will the molecular rays from the oblique flat pole, when this is made negative, issue through the aperture of the screen along the axis of the tube, 7.c., direct to the positive pole, or will they leave the pole normal to the surface and strike the glass on its side? With the corrugated pole experiment shows that at high exhaustions molecular rays are projected from each facet to the inner surface of the tube, where they excite phosphorescence, and form portions of ellipses by the intersection of the planes of molecular rays with the cylindrical tube. When the oblique flat pole is made negative, a stream of molecules shoots from it nearly normal to its surface, and those which pass through the hole in the plate of mica strike the side of the tube, forming an oval patch of a green colour. The oval patch in this apparatus happens to fall on a portion of the glass which has previously had its phosphorescence excited by the molecular discharge from the other corrugated pole. The phospho- rescence from this pole is always more intense than that from the flat pole, and the glass, after having been excited by the energetic bom- bardment, ceases to respond readily to the more feeble excitement from the flat pole. The effect, therefore, is, that when the oval spot appears, it has a dark band across it where the phosphorescence from the other pole had been taking place. The glass recovers its phos- phorescent power to some extent after rest. In this apparatus a shifting of the line of molecular discharge is noticed. If the coil is stopped and then set going repeatedly, always keeping the oblique pole negative, the spot of green light occurs on the glass at the spot where it should come supposing the discharge were normal to the surface of the pole. But if once the flat pole is made positive, the next time it is made negative the spot of hght appears nearer the axis of the tube, and instantly shifts to its normal position, where it remains so long as its pole is made negative. There seems no limit to the number of times this experiment can be repeated. A suggestion having been made by Professor Stokes that a third, idle, pole should be introduced between the negative and positive elec- #5 (9.| Molecular Physics in High Vacua. 479 trodes, experiments are described with an apparatus constructed ac- cordingly. The potential of the idle poles (of which there are two) at low exhaustions is very feebly positive; as the exhaustion gets better the positive potential increases, and at a vacuum so good as to be almost non-conducting, the positive potential of the idle poles is at its greatest. The result is that anidle pole in the direct line of fire between the positive and negative poles, and consequently receiving the full impact of the molecules driven from the negative pole, has a strong positive potential. It is found that when the shadow of an idle pole is projected on a _ phosphorescent screen, the trajectory of the molecules suffers deflection when the idle pole is suddenly uninsulated by connecting it with earth. The same result is produced by connecting the idle pole with the negative wire through a very high resistance, such as a piece of wet string, instead of connecting it with earth. A tube, which has already been described in a paper read before the Royal Society on December Sth last, is used to illustrate this deflection. The shadow of an alumi- nium star is projected. on a phosphorescent screen. So long as the metal star is insulated the shadow remains sharp, but on uninsulating the star by connecting it with an earth wire the shadow widens out, forming a tolerably well-defined penumbra outside the original shadow, which can still be seen unchanged in size and intensity. On removing the earth connexion the penumbra disappears, the umbra remaining as before. It is also found that the shadow of the star is sharply projected when it is made the positive pole, the negative pole remaining un- changed. These experiments are explained by the results just mentioned, that the idle pole, the shadow of which is cast by the negative pole, has strong positive potential. The stream of molecules must be assumed to have negative potential; when they actually strike the idle pole they are arrested, but those which graze the edge are attracted inwards by the positive potential and form the umbra. When the idle pole is connected with earth, its potential would become zero were the dis- charge to cease; but inasmuch as a constant supply of positive elec- tricity is kept up from the passage of the current, we must assume that the potential of the idle pole is still sufficient to more than neutralize the negative charge which the impinging molecules would giveit. The effect, therefore, of alternately uninsulating and insulating the idle pole is to vary its positive potential between considerable limits, and consequently its attractive action on the negative molecules which graze its edge. The result is a wide or a narrow shadow, according to circumstances. After a definite shadow is produced, it is found that increasing the exhaustion makes very little change in the umbra, but it causes the 2N 2 A480 © Mr. W. Crookes on [Apr. 3, penumbra’ to increase greatly in size. Experiments recorded in the paper already quoted have proved that the velocity of the molecules is greater as the vacuum gets higher, and consequently the trajectory of the molecules under deflecting action, whether of a magnet or of an insulated idle pole, is flatter at high than at low vacua. An experiment is next described, having for its object to ascertain whether two parallel molecular rays from two adjacent negative poles attract or repel each other. I+ is considered that if the stream carries an electric current, attraction should ensue, but if they are simply streams of similarly electrified bodies, the result would be repulsion. Experiment proves that the latter alternative happens, lateral repulsion taking place between two streams moving in the same direction. Many experiments are given to illustrate the law of action of magnets on the molecular stream, but the results are of too compli- cated a character to bear condensation without the diagrams accom- panying the original paper. The molecular stream is sufficiently sensitive to show appreciable deflection by the magnetism of the earth. The author, after numerous experiments, has succeeded in obtaining continuous rotation of the molecular stream under the influence of a magnet, analogous to the well-known rotation at lower exhaustions. Comparative experiments are given with a “high vacuum” tube, where no luminous gas is visible, but only green phosphorescence on the surface of the glass, and a “low vacuum” tube, in which the induction spark passes in the form of a luminous band of light joining the two poles. These two tubes are mounted over similar electro- magnets, the direction of discharge being in a line with the axis of the magnet. Numerous experiments, the details of which are given in the paper, show that the law is not the same at high as at low exhaustions. At high exhaustions the magnet causes the molecular rays to rotate in the same direction, whether they are coming towards the magnet or going from it; the direction of rotation being entirely governed by the magnetic pole presented to the stream. The north pole rotates the molecular discharge in a direct* sense, independent of the direction in which the induction current passes. The direction of rotation impressed on the molecules by a magnetic pole is opposite to the direction of the electric current circulating round the magnet. These results offer an additional proof that the stream of molecules driven from the negative pole in high vacua do not carry an electric current in the ordinary sense of the term. The author, after giving details of experiments in which platinum and glass are fused in the focus of converging molecular rays projected from a concave pole, describes observations with the spectroscope, * Like the hands of a watch. ES79. | Molecular Physics in High Vacua. A481 which show that glass obstinately retains at even a red heat a com- pound of hydrogen—probably water—which is only driven completely off by actual fusion. The permanent deadening of the phosphorescence of glass is shown by projecting the shadow of a metal cross on the end of a bulb for a considerable time. On suddenly removing the cross, its image remains visible, bright upon a dark ground. One of the most striking of the phenomena attending this research is the remarkable power which the molecular rays ina high vacuum have of causing phosphorescence in bodies on which they fall. Substances known to be phosphorescent under ordinary circumstances shine with great splendour when subjected to the negative discharge in a high vacuum. Thus Becquerel’s luminous sulphide of calcium has been found invaluable in this research for the preparation of phosphorescent screens whereon to trace the paths and trajectories of the molecules. It shines with a bright blue-violet light, and when on a surface of several square inches is sufficient to faintly light a room. The only body which the autbor has yet met with which surpasses the laminous sulphides, both in brilliancy and variety of colour, is the diamond. Most diamonds from South Africa phosphoresce with a blue light. Diamonds from other localities shine with different colours, such as bright blue, apricot, pale blue, red, yellowish-green, orange, and pale green. One very beautiful diamond in the author’s collection gives almost as much light as a candle when phospho- rescing in a good vacuum. Next to the diamond alumina and its compounds are the most strikingly phosphorescent. The ruby glows with a rich full red, and it is of little consequence what degree of colour the stone possesses naturally, the colour of the phosphorescence is nearly the same in all cases; chemically prepared and strongly ignited alumina phosphoresces with as rich a red glow as the ruby. The phosphorescent glow does not therefore depend on the colourmg matter. HE. Becquerel* has shown by experiments with his phosphoroscope, that alumina and many of its compounds phosphoresce of a red colour after insolation. Nothing can be more beautiful than the effect presented by a mass of rough rubies when glowing ina vacuum; they shine as if they were red hot, and the illumination effect is almost equal to that of the diamond under similar circumstances. Masses of artificial ruby in crystals, prepared by M. Ch. Feil, behave in the vacuum lke the natural ruby. In the spectroscope the alumina glow shows one intense and sharp red line less refrangible than the line B, and a faint continuous spec- trum ending at about B. The wave-length of the red line is 6895. * “ Annales de Chimie et de Physique,” 3rd series, vol. lvii, p. 50. 482 Profs. Livemg and Dewar. [Apr. 3, The paper concludes with some notes by Professor Maskelyne, on the connexion between molecular phosphorescence and crystalline structure. The crystals experimented on have been the diamond, emerald, beryl, sapphire, ruby, quartz, phenakite, tinstone, hyacinth (zircon), tour- maline, andalusite, enstatite, minerals of the augite class, apatite, topaz, chrysoberyl, peridot, garnet, and boracite. Of these, the only crystals which give out lght are diamond, ruby, emerald, sapphire, tinstone, and hyacinth. The light from emerald is crimson, and is polarised, apparently completely, in a plane perpendicular to the axis. Sapphire gives outa bluish-grey and a red light polarised in a plane perpendicular to the axis. The ruby light exhibits no marked distinction in the plane of its polarisation. Among positive crystals tinstone glows with a fine yellow lght, polarised in a plane parallel to the axis of the crystal. So far the experi- ments accord with the quicker vibrations being those called into play, and therefore in a negative crystal the extraordinary, and in a positive crystal the ordinary, is the ray evoked. Hyacinth, however, intro- duces a new phenomenon, being dichroic, the colours, in three different crystals, being pale pink and lavender—blue, pale blue and deep violet, and yellow and deep violet-blue, polarised in opposite planes. The only conclusion arrived at is, that the rays, whose direction of vibration corresponds to the direction of maximum optical elasticity in the crystal, are always originated where any light is given out. As yet, however, the induction on which so remarkable a principle is suggested, cannot be considered sufficiently extended to justify that principle being accepted as other than probable. VI. “Note on a Direct Vision Spectroscope after Thollon’s Plan, adapted to Laboratory use, and capable of giving exact Measurements.” By G. D. Livetne, M.A., Professor of Chemistry, and J. Dewar, M.A., F.R.S., Jacksonian Pro- fessor, University of Cambridge. Received April 3, 1879. Having seen in the “Journal de Physique” for May, 1878, the account of M. Thollon’s ingenious direct vision spectroscope, it occurred to us that by a little modification we could adapt his plan so as to produce an instrument well fitted for the work in which we were engaged, combining the advantage of excellent definition, which his plan secures, with the means of getting exact measurements with the least possible chance of errors of adjustment or inequalities in the working of the automatic system. The principle consists in having two prisms only (half prisms as M. Thollon calls them), of which one is fixed, and receives the light from the collimator by a reflecting 1879. | On a Direct Vision Spectroscope. 483 prism and transmits it in a plane at right angles to the axis of the collimator to the second prism. This second prisim is moveable about an axis parallel to its edge and to the axis of the telescope, and has a right angled reflecting prism attached to it, so that the light after traversing this prism twice passes the second time through the fixed prism and so by reflection into the telescope. The lever carrying the second prism with its reflecting prism is moved by a micrometer screw, by the head of which the movement of the prism is read. We placed the design in the hands of Mr. Hilger, some time since, and we now exhibit the instrument to the Society. In the last number of the ‘“ Journal de Physique,’ M. Thollon describes some modification of his instrument, but it does not seem that his modified plan is so well adapted to the ordinary use of a chemical laboratory as ours. The accompanying diagram represents a section through the prisms at right angles to the axis of the collimator and telescope. April 24, 1879. THE PRESIDENT in the Chair. The Presents received were laid on the table and thanks ordered for them. The Right Hon. Richard Assheton Cross, Secretary of State for the Home Department, was admitted into the Society. The following Papers were read :— 484 Mr. H. T. Butlin. [Apr. 24, I. “On the Nature of the Fur on the Tongue.” By HENRY TRENTHAM BUTLIN, F.R.C.S. Communicated by J. Burbon SANDERSON, F.R.S., Professor of Physiology in University College, London. Received March 26, 1879. [Prates 10—13. | The fur on the tongue is generally stated to consist chiefly of epithelial cells, usually sodden and granular. But several observers have described fungi as existing in it, or in the buccal mucus. Robin, for instance, describes a form of Leptothriv (L. Buccalis) in the mouth, and particularly in and between the teeth. Kolliker mentions, as of constant occurrence, masses or dark-brown bodies (which had previously been described by Miquel and Neidhardt, as occasionally present) having a granular aspect, which he believed to be of the nature of a fungus, similar if not identical with the fungus affecting the teeth. Billroth speaks of finding in the white fur of himself and of several patients, exquisite palmelloidal forms of Ascococcus and Gleecoccus colonies. The object of this paper is to show that schizomycetes form the essential constituent of the fur, and to explain, as far as possible, some of the laws which govern the formation of fur. The tongue is kept clean by free movement and by being rubbed against the interior of the mouth, the gums, and the teeth; but fur almost always exists upon its surface, both in health and in disease. The fur is generally thickest in the morning before food is taken, and during illness, when the necessary cleansing is not properly performed. It occurs, too, most abundantly in the centre and back part of the tongue, covering a triangular area immediately in front of the circum- vallate papille, for this part of the tongue is most difficult to keep clean. It occupies the papillary surface of the tongue, scarcely ever extending beyond it, and is, therefore, not found posterior to the circumvallate papille. It does not form a continuous layer unless it is exceedingly thick, but lies upon the tops of the filiform and some of the fungiform papilla. In children the fungiform papille are usually quite free from fur, but in adults the difference between the fungiform and filiform papille is not nearly so well marked, and, with the exception of those situated near the apex of the tongue, the fungitorm papille are frequently coated. Fur forms upon the filiform papille, because these papille are rough and possessed of longer or shorter epithelial processes, to which foreign matters cling readily, and from which it is very difficult to dislodge them. The fungiform papille, on the contrary, are usually smooth and rounded on the summit, and even when large are easily kept clean. nd 1879. ] On the Nature of the Fur on the Tongue. 485 The accompanying tables refer to the constancy of the presence of fur, to its thickness in health, and to its relation to the papille. Analysis of Cases examined. On 68 healthy tongues—fur on all except one. On 178 tongues of persons suffering from disease or accident—fur on all except two. Table showing relation of fur to papille on 62 healthy tongues, with remarks on the age of the persons and the characters of the papille. ng Position of Fur. he Age of Patients. Remarks on Papille. On filiform papille | 41 | 22 under 20 years of only. age. On filiform and some | 18 | 17 over 20 years of | In all cases fungiform fungiform papillee. age—l1 et. 15. papule small—in 14 cases difficult to dis- tinguish. Equally on filiform and 3 | All over 20 years....| Fungiform papillee fungiform papille. small or indistin- guishable. 62 Table of thickness of the fur on 68 healthy tongues, with remarks on the papille and the nature of the tongue. “| No. of Quantity of Fur. cay Papille. Condition of Tongue. IN@MIO.5 G04. cee 1 | Scarcely any........| Tongue very smooth | and supple. Mivieryetbim.. .. 2... 17 | Scarcely any in 12...| Verysmooth and supple \) appro a2: (innit ee ae eee 38 | | Moderately thin... 10 | Large and distinct | ' ; in 8. D EMVGle. a0) a 2 | Large and distinct...| Infirm old people, et. | 80 and 95. | Thick............05- O | | 68 | | } When thin the fur can only be scraped off with difficulty, and always brings with it numerous fragments of the hair-like processes which form the terminations of the filiform papille. But, when thicker, soft, and moist, it can be removed in considerable quantity with ease. A486 MroH? PButim: | [Apr. 24, Microscopical examination of the results of such scraping gives, in nearly every instance, the same results. 1. Débris of food and bubbles of mucus and saliva. 2. Epithelium. 5. Masses which appear at first to consist of granular matter, but which are the gloea of certain forms of schizomycetes. When large and closely packed they are of yellow or yellowish-brown colour, but when smaller and more loosely held together are almost colourless. They are generally attached to portions of the hair-like processes which have come away with them, on account of the tenacity with which they adhere to the processes. Vertical sections of hardened tongues show the relation of these masses to the filiform papille better than mere scrapings of the surface of the tongue. The filiform papille, instead of exhibiting fine, clean, tapering processes, terminate in processes which are uneven, tuberculated, or beaded, and blunted at their ends, owing to the presence of these bodies. Around the masses float free fungi, often exhibiting very active movement. The relative proportion of the three constituents of fur varies under certain conditions. The quantity of débris of food and bubbles is much greater during or immediately after eating than during fasting, although there is no corresponding increase of the fur at such times. The epithelium is much more abundant in thin fur than in thick far, its quantity depending rather upon the vigour with which the tongue is scraped than upon the amount of fur present. It can be obtained im just as great quantity where no fur is present, provided the tongue be closely scraped. The schizomycetes are found in every case in which there is fur upon the surface of the tongue, and I have even found a little of the gloaa where no fur was perceptible to the naked eye. The quantity of gloea depends roughly upon the quantity of fur. The position of the gloa corresponds with the position of the | fur. The fur dots the tops of the filiform papille, and the gloea is attached to the processes of these papille. Fresh scrapings of fur show this relation of the gloea to the filiform papille, but vertical sections of hardened tongues show more than this. They show that the filiform papille are the sole seat of the gloea, which does not exist between the papille, and seldom upon the fungiform papille. Again, the colour and appearance of the thin grey fur corresponds with the colour and appearance of the thin grey pellicle which forms upon the surface of Bacterium-producing fluids, and as the latter becomes whiter and more opaque as 1t becomes thicker, so does the fur become whiter and more opaque with increased thickness. A modification of colour is, however, frequently produced by the yellow or brownish- yellow tint of the gloea. In order to ascertain the true nature of the gloea, and to obtain it in a much purer form than that in which it exists naturally upon the 1879. | On the Nature of the Fur on the Tongue. A87 surface of the tongue, I cultivated it upon a warm stage. Minute portions of fur from different tongues were placed in a drop of aqueous humour, and kept at a temperature of 30° to 33° C. Free erowth and development took place, but instead of the single fungus I had expected several fungi were found. Only two forms, however, were present in every instance, namely, Micrococcus and Bacillus, and, from a comparison of the natural fur with results obtained by artificial cultivation, I think there can be little doubt that the fur consists chiefly or essentially of these two fungi. Micrococcus existed in every case examined, small spherical bodies generally in pairs or groups of four, but often forming chains. Upon the warm stage rapid multiplication took place with the production of pairs, fours, long and short chains often twisted and looped, and small and large colonies. When these colonies reached a large size (which happened in the course of a few hours) they presented a granular appearance and assumed a yellow or brownish-yellow colour, and all movement ceased in them.* The development of Micrococcus occurred abundantly and rapidly in all the experiments made with the exception of one, in which so rapid a formation of Bacterium termo took place, that in the course of a few hours the whole of the fluid was clouded and obscured by its presence. Usually the development of other fungi did not interfere with that of Micrococcus. Comparing the masses or colonies produced by cultivation with the granular masses of which the fur chiefly consists, the chief constituent of each appears to be the Micrococcus sphere. The natural colonies are, of course, not often so pure as those produced artificially, but still not uncommonly these natural colonies present the same regularity of structure as the colonies figured in sketch 5. The other form, Bacillus, was also present in every case examined, but unfortunately development seldom or never occurred, being apparently prevented by the presence of other fungi. I+ consisted of slender rods, having a well-marked double contour and a light interior. Their length varied much, but was always many times their breadth. There were no defined contents within the rods, except in some of the longer and broader of them, which contained highly refractive spherical bodies which appeared to be spores. The shorter rods moved actively about the field of the microscope, and even some of the longer rods (looking when magnified 450 times from $ inch to 1 inch long) moved slowly from place to place. The rods were generally straight, but some of the longer ones were curved or bent. They often formed short chains or occurred in pairs, but did not form colonies, although they sometimes occurred in great number and of large size in the Micrococcus colonies. They showed very little * IT never observed any lengthening into rods, or the development of any other form from these Micrococci. 488 On the Nature of the Fur on the Tongue. — [ Apr. 24, change in appearance for many hours, sometimes for two or more days, after which they usually became granular and degenerated. These bodies are apparently identical with the Leptothrix buccalis of Robin. But I think they would be more rightly called Bacillus subtilis. Their length, their slender form, the conditions in which they occur, and the fact of their non-development in the presence of other fungi point to this conclusion. I made many attempts to separate them in order to produce the fungus in a purer form by cultivation, but did not succeed in doing so. Although this fungus did not develop under artificial conditions in the presence of Micrococcus and other fungi it is highly, probable that its development takes place freely upon the surface of the tongue. Its habitual presence there, generally in tolerable abundance, and the occurrence of spore-bearing filaments may be adduced as evidence in favour of this view. Besides these fungi Bacteriwm termo existed In some of the furs examined, and twice developed with such rapidity that the whole of the fluid was crowded with these organisms to the exclusion of every other form. Pairs, chains, and colonies were formed. Sarcina ventriculi was frequently present and generally developed quickly. It usually occurred in pairs or fours, and was easily recognisable by its large size, compared with the other organisms present, by the square or oblong form of its nuclei, by their faint yellow or red tint, and by the area of protoplasm surrounding the nuclei. The groups of two or four moved slowly about the field of the microscope, but the large masses which were formed remained ‘quite motionless. The masses attained so large a size as seriously to interfere with the growth of some of the other organisms, and when large showed a decided yellow, or brownish-yellow colour. In two or three of the specimens there occurred rapid and very abundant development of a form of Spirillum, which appeared from the double twist which it exhibited, and from its extreme tenuity, to be Spirocheta plicatilis. Its growth took place from exceedingly small portions of the organism, and continued only at one end, which was in constant motion, whilst the other end remained stationary ; and as the growth progressed, large masses were formed which soon became so dense that it.was impossible to discern the nature of the organism of which they were composed. This Spirocheta did not occur in most of the specimens examined. A larger form of Spirillwm was also occasionally present, but was not seen in the act of developing. Although TF believe the fur consists chiefly of Micrococcus and Bacillus subtilis, | think it is probable from the results obtained in the experi- ments upon which the foregoing observations are founded, that the development of these other forms (Bacterium termo, Sarcina ventri- Proc. Roy Soc. Vol. 28. Pl. 10. ) FLT Sutin del. Waw imp. Newman & C2 7 West Vedley M PAE RE Me ‘ : West Newman Gimp. Fig.1. Constituents of healthy fur. (low power . Fig.2, 3s highly magnified. (<450,) : ae —— “SENS SW) ee py a Proc. Roy. Soc. Vol. 28. Pl. 12. tis AOAC nY 7 A, / | ON Vi y \ OS Cy fj) SSSSSZ Tee o oY oe Ongar HT Butlin del. imp. Gos Nevanon 2 ( West WL Wesley lith, (oc.3., obj.4) of Fapillee with fur upon them. (x 240.) illee ctions of Epidermis-fur on filiform papi Se Portions ae: ° marp. — AR AWS OOSASS, ™ Sar CaS6) CNSD > a a GErase'S aS ; Ky coe Scago8s ‘ SS SECYe/S0 sie N aoe ( : ~ ISS) SE vesoiegQy me & E ee z OSS | ia FS ms 12 : CQ KOS) oe" = 8 = j S nS : @ ‘2 ) ae 3S il g Py € = c Ae) iS) US) ~ (SO s < 3 = a0) cs 3 fr Ee is : 0/ ERQ Sot Ss OS a ey : : S = Sea, oe © Oo OS IF >. a= D & Se i us "G SS S x) = a oy = iD RG, S es 9 S iS © ro) a i. @ iS Se ay SS pr IN a, 3 ze. NN earere \ Oo SS \ Wa N Cy (2) ae \ } \ \ ~ 4 pee ie $= z, Ya \ vA /\ wn ZA vA >) \ E : \ N —_— NS v S Vy, SQ / UY SN \ Wj WA INN iS i, He S 5 J ‘ NN C2 : \ \ S } J / / (aa ° AY lA Y ee NG V 3 : \ Coes ce Rw f We fm § Sook gis 8 S | : ae Pe af oS Ee eas e Se 8 ep x o S “= X iS) <= ~S ~ ~ a) = >) ~ ~ ~ iv) S ~ ~ S S 1879.] 492 Dr. J. B. Hicks. On the Supplementary Forces [Apr. 24, the button in the centre attached to the tambour fairly touching the abdominal wall. On revolving the drum attached, a well marked tracing is obtained, showing the respiratory wave; more marked in the male, but almost always well pronounced in the female. The height of these waves, of course, marks the difference of the elevation of the centre of the area and the circle described by the three legs before mentioned, the amount indeed of the bulging of that portion. By this arrangement the effects of the various movements of the body can be also registered with great ease, so far as these movements compress the walls of the abdominal cavity. But although the abdominal walls in front yield, yet the descent of the diaphragm, which accompanies the inspiratory act, must put pressure on the contents of the abdomen: and thus tension is created, which is in a certain degree lessened—Ist, by the yielding of the walls just mentioned, and, 2ndly, by the escape of blood from the vessels within the cavity of the abdomen; and this would be more marked in the case of the venous blood. In the case of the arterial bloud, the pressure would tend both up- wards and towards the heart, and downwards towards the lower ex- tremities and. the abdominal walls. The movement towards the thorax would probably be but slight, yet it would to a certain extent add somewhat to the arterial tension, noticed as commencing at the be- ginning of inspiration. The other, the downward movement, acting in the direction of the arterial current, would increase also the arterial tension in the lower extremities and abdominal walls. But upon the venous system the effect would be greater. 1st. Upon the systemic its effects would be cut off in the downward direction by the valves, though this woul tend to increase the venous tension in the lower extremities. But this probably would be socn neutralized, or nearly so, by the freedom which the incipient vacuum caused by the expansion of the chest gives the blood to enter the heart. But the pressure caused by the descent of the diaphragm tends to press the blood in the vena cava also upwards, thus facili- tating the flow in the natural direction; but any tension to which the vessel is subjected is probably immediately or simultaneously relieved by the suction-action of the chest, which is well known to diminish considerably the blood-pressure in the large veins close to the thorax during the inspiratory movements. That this pressure of the dia- phragm on the abdominal contents nearly if not quite balances the suction-action, is shown hy the fact that in the sciatic vein the diminution of the blood-pressure during inspiration is not observed. 2nd. The portal system is subjected likewise to pressure, and its contained blood would tend to both its incipient and terminal capil- laries ; and the resultant would be to facilitate its movement towards the area of least resistance, namely, towards the hepatic veins. 1879.] concerned in the Abdominal Circulation in Man. 493 In computing the effect of the descent of the diaphragm we must always bear in mind the effect of the expansion of the lower part or base of the thorax; for this by lifting off as it were the pressure of the abdominal muscles attached to it from the viscera beneath, lessens the effect of the descent of the diaphragm. Notw Chetan this there is a notable residuum of force. The effect of expiration on the abdominal circulation would be pro- bably to gradually permit a restitution of the balance interfered with. The elasticity of the walls would sustain, to a considerable degree, the pressure ; the portal vein and vena cava would gradually accumulate blood, and this in coincidence with an increment in that of the superior cava and right cavities of the heart till the irritation of its presence causes another inspiratory act. It may be noticed that the tension of the arterial pulse would be naturally increased during the expansion of the lungs, because of the greater supply of blood to the left half of the heart shortly after the commencement of the inspiration, and thus the resistance to the flow of venous blood through the lung capillaries is lessened ; and this action it is impossible to ignore when we are discussing the effect of the incipient vacuum on the venous blood-pressure during inspiration. The same method of registering the effect of the respiratory move- ments on the abdomen also is applicable to marking the effects of the general movements of the body. The elevation of the arm or the leg, coughing and laughing, &c., are easily seen to compress the abdomen. It would be beside the intention of this note to discuss the manner in which this effect of movements of the body is produced ; but I may point out that in the act of coughing and laughing we have, as indeed might be expected, evidence not only of high pressure (shown by the sudden elevation of the wave), but also a tendency to vacuum, as illustrated by the sudden descent of the wave below the line. These actions must tell violently on the blood-current of the abdo- men, and tend to force it out of this cavity; and, as before remarked, the resultant of this must be to facilitate the current in its normal direction. The same effect must be produced on the other fluids in the abdomen, and mustassist the movement of the secretions contained in the ducts of the various organs, notably that of the liver. (Received April 16.) In the foregoing note no calculation has been made as to the amount of the forces produced by the descent of the diaphragm in ordinary respiration. Its extreme violent action has been calculated by Professor Haughton at 20 lbs. on the square inch ; but the amount of pressure on the contents of the abdomen must vary much, accord- ing to the resistance exerted by the parietes. When the intestines are empty of gaseous contents, and the previously over-distended abdomen VOL. XXVIII. 20 494. On Ausiliary Forces concerned in the Circulation [Apr. 24, is suddenly emptied, as immediately after delivery in woman, this resistance is at the lowest, consequently the effect of descent of the diaphragm on the circulation is but slight, compared with that state which obtains when the parietes are in a high state of health, and the intestines are fully distended with gas, &c. It must be evident that the amount of blood contained in the vessels within the abdomen must vary much, according to the tension of the parietes; but this matter does not belong to the subject of this note. UI. “Note onthe Auxiliary Forces concerned in the Circulation of the Pregnant Uterus and its Contents in Woman.” By J. BRaAxton Hicks, M.D., F.R.S., F.L.8., &e. Received March 26, 1879. Whatever view we may take of the structure of the placenta, it is generally admitted that both in the large sinuses in the walls of the pregnant uterus, and also in the decidual processes in the placenta as well as in the intervillal spaces the motion of the fluids can be but very slow, that 1s, if the circulation wholly depended upon the maternal cardiac impulse. However, in 1871,* I pointed out a fact which had not been before observed, that the uterus was in the habit normally of alternately re- laxing and contracting every five, ten, or twenty minutes during the whole of the pregnancy from the earliest period, at least from the second month, and not as had before been believed only under irrita- tion, and towards the end of gestation. This movement is doubtless homologous with the peristaltic movements in the uteri of the lower animals. In that paper I pointed out—Ist, that these movements of the uterus. provide for the frequent movement of the blood in the uterine sinuses and the decidual processes; and, 2ndly, that they facilitate the move- ment of the fluid in the intervillal space of the placenta, or in that which has been called the placenta sinuses, and I remarked, “ What- ever view we may hold of the structure of the placenta, whether on the one hand there be blood amongst the villi in maternal sinuses, or on the other merely a serous fluid, in any case it is through one or the other medium the villi absorb the material for the aération of the foetal blood; and there can be no doubt that from its position it must be in a more or less stagnant state. It is not difficult, therefore, to recognise the effect which the change in the solidity and shape must produce on the fluids in the placenta, as well as in the uterine walls. * © Obst. Trans. Lond.,” vol. xii. ‘On the Contractions of the Uterus during Pregnancy : their Physiological Effects and Value in the Diagnosis of Pregnancy.” 1879.] of the Pregnant Uterus and its Contents in Woman. 495 In other words, these contractions of the uterus act as a kind of sup- plementary heart to these fluids.” To this force I have now to add the effect of the respiratory move- ments on.the grayid uterus and its contents. Any one who places his hand on the abdomen of a pregnant woman over the centre of the uterus will be conscious of the projecting forward of the uterine wall. But I presume this has been supposed hitherto to be merely the pro- jection of the uterus en masse. Admitting that a slight portion of the movement is ewing to that, I shall endeavour to show that the much greater portion of the movement is due to the bulging out of the walls by the downward pressure on the fundus during inspiration. This is best demonstrated by a cardiograph constructed with a button tam- bour, supported by three legs, capable of being adapted by screws to the proper length; these should be as far apart as possible, four inches orso. The patient should be placed on her back, and the tambour tied gently on to the abdomen by a tape passed round the back. The drum being set revolving, the respiratory movement is traced. The respiratory markings are very regular considering the circumstances, interrupted at irregular intervals by the foetal movements, coughing, and other movements of the body. Normal Respiratory Wave over Pregnant Uterus. The swb-readings depending probably on arterial impulse of mother; and of the feetus. Now, it is clear that the readings express the difference of elevation of the uterine wall between the tambour button and the circle enclosed by the legs; in fact, the amount of the bulging of the wal! within 202 496 On Auailiary Forces concerned in the Circulation [Apyr. 24, that area. If it were not so, and but the pushing forward of the mass, no difference would exist, and, consequently, no reading obtained. And this is proved by observing the effect on the readings when the uterine contractions occur, to which I alluded at the commencement of this note; for, when these supervene, we find the respiratory readings reduced almost to nothing, and, instead of the high elevation waves of the tracing, well shown before, the line is nearly level. Thus, when the uterus, in consequence of the increased firmness of its walls, cannot be impressed nor can bulge, we have the effect of the descent of the diaphragm to a similar extent reduced. This being admitted, it is clear that every respiratory action causes a movement of the fluids contained within the uterus, thus assisting the circulation in a part apparently removed from the maternal cardiac impetus. It may be worthy of notice, that at the earlier period of pregnancy, the uterine walls are less yielding, and, therefore, less influenced by the . respiratory act, but then the assistance this renders at a later period is not so much required, because neither are the sinuses so large nor the decidual processes with their sinuses so deep, nor the thickness of the placenta so great. Gradually as the uterus increases, its walls are more yielding and the force of the respiratory movement more felt within. uterine contraction. As 5 I inst MS CPS Sx we aX. contraction subs iding : SS Be NY ot bs RE EN ie PA aS contraction passed of f. The effects of Uterme Contractions during Pregnancy in reducing the height of the Respiratory Wave is seen by comparing the first line with the last. This tracing was taken with a smaller instrument. There are other points of interest in this registration of the respiratory movements of the abdomen, which do not belong to the - subject under consideration, and are, therefore, omitted here. But there are other accessory forces to be noticed which act on the , surface of the pregnant uterus, tending to the movement of the fiuids within; namely, the muscular movements of the body, tending to cause a change of shape of the thorax or abdomen. These are quickly shown by the same arrangements as that by which the crdinary respiration is shown. The elevation of the arm, a hoist of the body, and, in particular, coughing, show a much greater force than is exerted by inspiration. Hence, one might fairly infer that exercise 1879.| of the Pregnant Uterus and its Contents in Woman. 497 in general in moderation will expedite the flow of the fluids in the uterine vessels, d&c., and, also, that a sudden severe action will tend to urge it forward so quickly, before the vessels can convey it onward, es D = c<) So € & 3 interrupted by movements of arm, leg, and of coughing. 4 a * \ Tracings from Abdomen over the Uterus Pregnant at 9th month, showing the ordinary Respiratory Wave, that their rupture would result and effusion of blood be a natural consequence :—a result which experience shows actually occurs under such circumstances. 498 Dr. W. Marcet on the Function of Respiration at [Apr. 24, IV. «A Summary of an Inquiry into the Function of Respiration at Various Altitudes on the Island and Peak of Teneriffe.” By WiuutAM Marcet, M.D., F.R.S.. Received March 31, 1879. Qn the 19th March of last year, I presented to the Royal Society a short summary of an inquiry on the function of respiration at various altitudes in the Alps. The principal resuit obtained was that a greater quantity of carbonic acid was formed in the body and exhaled at the higher than at the lower stations. Thus, after experimenting on a spot near the Lake of Geneva, at an altitude of 1,230 feet, and ‘at the summit of the Breithorn, at an altitude of 13,688 feet, there was found to be an excess of 15 per cent. for the carbonic acid expired at the highest station. I had come to the conclusion that the increased formation of carbonic acid in the body at certain altitudes in the Alps appeared necessary, as a means of resisting the influence of cold which is occasionally very great in high Alpine regions. The question which now offered itself for inquiry was whether, on rising to a considerable altitude above the sea in a warm climate, there would be, as] had found in the Alps, an increase of the carbonic acid expired. After some consideration, the Peak of Teneriffe, in north latitude 28°, was selected as the place best calculated for investi- gating the subject. The advantages of this site were manifold. First, a mean temperature in the day time, which proved to be not lower than 64° in the shade, could be secured at an altitude above 10,000 feet; next as the mountain rose from the sea, various stations, beginning at the seaside, might be selected ; then fine weather could be relied upon in June and July, on the Island of Teneriffe ; finally, the spot was situated at an accessible distance from England. It took me three weeks to collect the necessary instruments, among which was a wooden shed, taking to pieces and made to pack in a comparatively small space. It consisted of six deal boards constructed so as to fit side by side with overlaping edges; when mounted, they formed a flat square roof. The four corners of this roof were sup- ported by four poles held upright by tent ropes and pegs;. broad strips of canvas were nailed to two opposite sides of the roof and spread out, being held in position by strmgs and pegs. The boards covered a square of 6 feet on each side and the sheltered area was much increased by the canvas. The shed was placed lengthways as nearly as possible in the direction of the course of the sun, and by this means we could work all day long in the shade, a necessary condition for the success of the inquiry. My experimental baggage included two large baskets holding about 150 bottles of a capacity of rather more than 100 cub. centims. each, 1879.] Various Altitudes on the Island and Peak of Teneriffe. 499 and full of a titered solution of barium hydrate, in addition to which there were a number of empty bottles of the same size. The bottles holding the alkaline solution were carefully corked and the corks sealed with paraffin. I must also allude to two strong deal boards or rocking-boards, 6 feet in length and supplied with two iron sockets midway between the two ends; the sockets fitted upon an iron bar raised a few inches high on a firm wooden stand. Two square open wooden boxes were made to fasten at one end of each board respec- tively, and could be filled with stones or sand up to a given weight. The use of these boards will be explained in the course of the present communication. In addition to the above apparatus I carried with me a balance and everything required for determining the moisture expired from the lungs. My experimental baggage used in the Alps was also included, together with every requisite for camping out on the Peak for about three weeks. My Chamounix guide, Edouard Cupelin, who has accompanied me for the last ten years in the Alps, and is thoroughly used to the mani- pulations connected with my experiments, came out with me to Teneriffe. He not only assisted me most effectually, but also sub- mitted himself to experiment. We arrived at the Island of Teneriffe on the 25th of June last, and after landing at Santa Cruz, proceeded at once to Puerto de Orotava, at the foot of the Peak. Three principal stations were selected, two at different altitudes on the Peak, and one at the seaside; while from the highest station instruments could be carried to the foot of the terminal cone, and also to the summit of the Peak 12,200 feet above the sea, where I proposed making a few experiments. We remained eleven days at the lowest station on the Peak, at an altitude of 7,090 feet, and ten days at the higher station 10,700 feet above the sea. The characters of the stations bearing on my experiments were :— 1. The topographical position and atmospheric pressure. 2. The temperature of the air. 3. The hygrometric state of the atmosphere. Ist. The position and atmospheric pressure. My lowest station on the Peak, that of Guajara, was situated on a sandy plateau at the foot of Mount Guajara, known from Professor Piazzi Smyth having esta- blished an astronomical station at the summit in 1856. The moun- tain rose 1,800 feet above my station in the §$.W., while in the opposite direction for 200 or 300 yards, there spread a patch of white sand mixed with clay, and baked by the sun. Beyond that could be seen a bank of blocks of lava tumbled over each other, which formed the edge of an upper undulating level reaching the foot of the actual Peak at a distance of two or three miles. The heat of the sun at 500 Dr. W. Marcet on the Function of Respiration at [Apr. 24, that station was intense, as my tent was erected in a hollow, and the sand became so hot in the afternoon that the hand could not bear being kept in contact with it. The mean of twenty-two readings of a Fortin barometer, by Casella, compared with the observations of Professor Smyth, taken at sea near the coast of Teneriffe, in 1856, at a similar time of the year, or nearly so, gave an altitude of 7,090 feet above the sea for that station. The stations in the Alps where my former experiments had been carried out, and corresponding in altitude with my Guajara station on Teneriffe, were the Riffel (8,425 feet) and St. Bernard (8,115 feet), these however being rather over 1,000 feet higher. The highest of my principal stations on Teneriffe was that of Alta Vista, where Mr. Piazzi Smyth also resided in 1856. This was near the summit of the Peak ona small “plateau,” occurring in a break between lava streams. This station faced an easterly aspect; im the evening a cold westerly wind often blew, sweeping down from the summit and feeling exceedingly chilly. The altitude of this station according to Piazzi Smyth, is 10,702 feet. An accident to my barometer just before leaving Guajara put an end to barometrical readings, but an observation as to the temperature of boiling water at Alta Vista gave me exactly the height as determined by Professor Smyth. This altitude compares well with that of St. Theodule, 10,899 feet, one of my stations in the Alps. The N.E. trade winds cause a belt of clouds to hover over the island ; I entered this layer of fog at an altitude of 3,200 feet, and left it at 5,500 feet, its thickness amounting therefore to 2,300 feet. My stations on the Peak were of course above the clouds; on one occasion only did I see them from Alta Vista make an irruption into the wide plateau at the foot of the peak between 6,000 and 7,000 feet high, but they soon withdrew. Qnd, Temperature.—The sky was cloudless till the last day, when a few light clouds appeared overhead, and the sun being nearly vertical at noon, in July, its direct heat was very great, although the air was much less warm in the shade; on the other hand the cold was very sharp at night. While the sandy surface of the soil was so hot at two or three o’clock in the afternoon, that the hand could not bear to be pressed against it, water left outside the tent in a bucket or in plates was on several occasions found frozen next morning just before sunrise. I had no black bulb thermometer in vacuo for observing the solar radiation, but Professor Smyth found on the summit of Mount Guajara over 180° F., with such an instrument by half-past nine o’clock in the morning, and he concludes that on August 4th, the black bulb temperature in the sun must have been 212°-4, the thermometer reading in the shade being only 60°, thus leaving the enormous quantity of 152° for the effect of sunshine at 1879.] Various Altitudes on the Island and Peak of Teneriffe. 501 a height of 8,900 feet. a Smyth—“ Teneriffe—an Astronomer’s Hixperiments.’’) Although my first station was 1,810 feet below that at which Piazzi Snayth’s observations were readies I cannot think the direct solar heat was notably less. I procured at Puerto a large box, and had it perforated with many holes on every side to allow of free access of air into it. This box was used as a screen for my thermometers ; if I mistake not, a similar plan had been adopted by Professor Smyth. The screen was placed under my wooden shed, and thereby sheltered from the sun. While on my Alpine stations, 1 was working under a mean temperature of 39° at St. Theodule, and 52° and 43° at the Riffel and St. Bernard respectively, my atmospheric temperature on the Peak of Teneriffe was from 65° to 69° in the shade, and rose in the sun much higher than on the Alps; in fact I was throughout the day time exposed to a climate much warmer than at my Alpine stations; so far, therefore, my object, in going to Teneriffe, of avoiding cold at eomparatively great altitudes above the sea was attained. ard, Moisture-—The great dryness of the air in the daytime was very remarkable, the total mean difference between the dry and wet bulb readings at Guajara (7,090 feet) being 25°°6, and at Alta Vista (10,700 feet) 19°°7; while at Puerto de Orotava, at the seaside, the difference fell to 8°-7. I was never conscious of perspiring, and my skin was always very dry, with the throat parched at times. The evaporation from the skin must have been very great so high above the sea, in such dry air and under so powerfula sun. The inquiry may be divided into three parts: The first refers to the respiratory phenomena at the various stations while in the sitting posture. The second, to the respiratory phenomena observed while engaged upon a definite amount of muscular work. The third, to the amount of watery vapour expired sitting at my different stations. I shall beg to commence with the experiments relating to the breathing while in the sitting posture. The method adopted in these experiments was precisely the same as that I had made use of in the Alps, with this very slight difference, that instead of cooling the air expired into the bag, to the temperature of the water in the aspirator, where it was treated with the solution of barium, I noted the temperature of the air in the bag immediately after fille it, and drew the air at once from the bag into the aspirator or tube, recording its temperature in the tube. In nearly every case the temperature in the tube was rather lower than in the bag, so that a contraction took place; the degree of contraction was duly taken into account in the calculations of the analysis. I also used common water instead of a solution of salt for aspiring the air for analysis into the tube. 502 Dr. W. Marcet on the Function of Respiration at [Apr. 24, The air from the lungs was expired into a strong india-rubber bag of a known capacity under a pressure of one inch of water. The bag used in nearly every experiment sitting held 39°3 litres of air under that pressure; and in the experiments made while engaged with a measured amount of muscular work, a bag holding 68:4 litres of air under the same pressure was employed. The tube into which the expired air was drawn for analysis was supplied with the india-rubber diverticulum described in my former communication, and I made occasional use of it to take out small quantities of air and test them with a solution of barium hydrate. I thus observed that a continued agitation of five minutes sufficed for the entire combination of the carbonic acid. In every experiment the agitation was continued for six or seven minutes or longer, by the watch. ‘The bottles, into which the fluid was drawn after agitation, were well corked, and their necks dipped into melted parafiin. Although large enough for somewhat more than the bulk of the fluid they contained, the empty space was too small for the air it held to affect the alkaline solution. My Chamounix guide was practised in the mode of breathing into the bag, so that I could rely upon his doing this in a perfectly natural way, and without the loss of any of the air expired; he was also in the habit of counting his expirations while so engaged. We assisted each other mutually ; one of us keeping an eye on the stop-watch and the bag, while the other was breathing into it. After sitting quiet for a few minutes, the mouth was applied to the mouthpiece, and at the very beginning of the first expiration, a sign was made and the stop-watch started. When the bag was nearly full, the water in the gauge began to rise, and the instant it attained the height of one inch, the watch was stopped. The time to fill the bag was then read off, and the temperature of the air in the bag ascertained, both observations being immediately noted. Without any loss of time the air was at once aspired into the cylinder, and its temperature within the cylinder again read off by means of a thermo- meter run through the india-rubber stopper. Then followed the introduction of the normal alkaline solution, the agitation and the bottling; a whole experiment took from thirty minutes to forty-five or fifty minutes. The total number of my Teneriffe experiments on respiration, including the determination of the carbonic acid expired, amounted to 157. The Chamounix guide is a tall and very powerful man of 38 years of age; I found him to measure round the bare chest at the nipples, 3 feet 5 inches. His height, in boots with moderately thick soles, is 6 feet 04 inch, and he subsequently found his weight to be 89 kilog., —exactly 14 stone, I am 50 years of age, measure 2 feet 104 inches round the bare 1879.| Varicus Altitudes on the Island and Peak of Teneriffe. 503 chest, have a height in boots with moderately thick soles of 5 feet ¢ inches, and weigh 70 kilog., say 11 stone. We are both in the enjoyment of very good health. It will be observed that we lived precisely in the same way, were exposed to the same kind of atmospheric influence, and ate the same kind of food, although from the weight of his body, the guide con- sumed more than I did. The amounts of carbonic acid we expired could therefore be fairly compared with one another. The mean weight of carbonic acid expired from sixty experiments for myself, and fifty-five for the guide, both sitting, and at the same stations respectively, was in my case, 472 mgms. per minute, and in that of the guide 604 mgms., or on 100 kilos. weight of my body, I expired 674 mgms. of carbonic acid per minute, and the guide also on 100 kilos. weight, 679 mgms. Thus it was found that we both gave out at the lungs an amount of carbonic acid propor- tional to the weight of our body. This is an interesting, though not unexpected result, which appears to me to give much weight to the correctness of the investigation, and consequently to the reliability of the conclusions. Another circumstance in connexion with the present work still more deserving of notice than the former, was the fact that while we were engaged raising at each step a weight of 59°5 lbs. with the feet, on rocking boards, at the rate of 45 steps per minute, as will be sub- ‘sequently described, a mean amount of carbonic acid was expired by each of us respectively, again proportional to the weight of our body. In these experiments, the mean weight of carbonic acid obtained for myself from eighteen experiments, six at three different stations, was 1011 grms. per minute, and for the guide from the same number of experiments at the same stations 1:269 grms., giving for myself for 100 kilos. of body, 1:444 erms., and for the guide for 100 kilos. of body 1:426. Nothing can be more conclusive; we again produced within our bodies as nearly as possible the same amount of carbonic acid proportionally with our weight. These figures also show that the method adopted was well calculated to give reliable results, while engaged in a definite amount of muscular exercise. Amount of Carbonic Acid expired at the different Stations. The mean amount of carbonic acid expired at the several stations by both of us in the sitting posture, was found, to a great extent, to be influenced in a similar way by the food taken. In both cases, with but one exception, the greatest amount of carbonic acid expired was ‘during the first or second hour after eating, and the quantity ‘diminished as time elapsed from the last meal taken.* The exception * Dr. Edward Smith’s (“‘ Phil. Trans.,”’ 1859) experiments show that a minimum -amount of carbonic acid expired is obtained while fasting, beyond which continued fasting, within certain hmits, produces no further reduction. 504 Dr. W. Marcet on the Function of Respiration at [Apr. 24, refers to the guide at Puerto, where his maximum is found to be during the third hour after a meal. The fluctuations in my case may be said to follow closely those formerly reported from my experiments. in the Alps. The subjoined table shows at a glance the variation of the mean amount of carbonic acid expired during each successive hour after food, the fifth or sixth hour being grouped together for want of a sufficient number of experiments. Table showing the Influence of Food on the Expiration of Carbonic Acid at the various Stations (in the sitting posture). Self sitting. Alta Vista. Guajara. Puerto. Hours after Food. | CO; expired per | CO ; expired per | CO, expired per minute. minute. minute. Otolhour .........-| 07534 (8) 0-374 (1) 0-467 (3) ge 2 vhours 6) ais lhe 105021 (8) 0:497 (6) 0-496 (5) Bs ee ee ey OA T2 TG) 0486 (4) 0-498 (6) By Oa eee eal ee 0-424 (6) 0448 (4) | AigGhaes i 0-435 (4) { 0-398 (2) 0-384 (2) | Cupelin sitting. Otolhour . . = 0°560 (2) No experiments. eee hon ee \ ee) { 0-609 (5) 0-684 (5) Dense ey Oil Use aOL S08 (7) 0-560 (6) 0-711 (6) Br aun Geka | te 10595 aC) 0-565 (4) 0 684 (5) AMO) hog veers ij eo oxkcie No experiments 0°489 (4) 0°609 (2) The figures between brackets refer to the number of experiments. One experi- ment, at 5.48 a.m. at Guajara, not included. If the figures reported in this table be taken into consideration together with the corresponding results obtained in the Alps, it will appear that the maximum amount of carbonic acid is expired rather earlier after a meal on the mountains than in the plains, which would show that there is apparently a tendency to a more rapid digestion and assimilation of food in the mountains than near the sea level. As in the case of my former investigation, I have neutralised as much as possible the influence of food on the results of the experi- ments, by conducting the inquiry at all times of the day between breakfast and bedtime. Influence of Temperature on the Carbonic Acid expired.—So far, to my knowledge, the only series of observations we possess on the influence of tropical climates on the functions of the human body, are those of Dr. Rattray, Surgeon R.N., who has clearly taken great pains to investigate the subject; he concludes that :— ‘The three marked tropical phenomena, viz., diminished lung 1879.] Various Altitudes on the Island and Peak of Teneriffe. 505 vascularity, slower respiration, and gentler breathing are closely related, and together indicate reduced lung work, the reverse for the temperate zone marking an increased function,* &c.” Dr. Rattray infers, without apparently making any actual deter- mination of carbonic acid in the air expired, that there is a larger amount of carbon thrown out by the lungs in temperate than in tropical climates. . The consideration of the mechanical action of heat, with reference to the functions of the body, had led me long ago to adopt the same views; and previous to my Teneriffe experiment, I had believed that where the heat of the sun was in excess, less heat _ was required to be manufactured by the body for the due performance of its functions, and, consequently, less carbonic acid was formed and given out. Iam now compelled, however, to alter this view, and to conclude that more carbonic acid is formed in the body under a tropical or nearly tropical sun than under temperate latitudes. In order to make the subject perfectly clear, I have placed, in a tabu- lar form, the figures showing the amount of carbonic acid expired, as found by direct experiments both in my Alpine and southern stations. Table showing comparatively the Weights of Carbonic Acid and the Volumes of Air (reduced) expired per minute by myself and guide in the Alps and at Teneriffe. Self sitting. Volume air expired CPeene. CO, expired. Bas min. (reduced Number of ‘ to 32° and seaside experiments. | pressure). | Increase for Increase for | Gm. ‘Teneriffe. | Litres. Teneriffe. | Per ct. Per ct. PANGAN VAISEA) sv 6 o's o's | 0 °486 5°14 20 Breithorn and St. | ; 13°8 ; ; Aes } { Theodule.. -| 0-419 4°74 | OB: Guajara. . .| 0°458 5°47 20 Riffel and. ‘St. ‘Ber: | ; 9°6 } 16-1 TAT as js s .| 0-414 463 29 Serie eucrto - | Oui ae j 8S ayes j | 20 Lake of Geneva... 0°383 4 5°14 Tag | 37 Cupelin sitting. Alta Vista.. 7 yee 6°24 37 Guajara........ ue ° ‘ea Nil | | 5-8 St. ieee y 0 °565 5°88 A WerbOnceie. ce ..-- || 0-685 17-5 { ae 23-7 { 18 St. eenacd’y. 0 °565 5°88 i 4 The figures for the weights of CO, expired in the Alps have undergone a correc- tion. See foot-note, page 507. * “ Proc. Roy. Soc.,’’ vol. xxi, 1872. 506 Dr. W. Marcet on the Function of Respiration at [Apr. 24, It will be observed in this table, that, in my case, when approxi- mately equal altitudes in the Alps and on the Peak of Teneriffe are compared as to their influence on respiration, at the highest stations there is an increase of carbonic acid expired by 13°8 per cent. for Teneriffe; at the stations next in altitude, the increase is by 9°6 per cent. for Teneriffe, and at the seaside, compared with the shores of the Lake of Geneva, the enormous increase for Teneriffe of 18°7 per cent. is noted. As to my guide, I have, unfortunately, but few experiments on the carbonic acid he expires on the Alps, which only amount to four in number. They show for approximately equal altitudes no increase of carbonic acid expired on the Peak of Teneriffe ; but at Puerto de Orotava I find him to give out a very large quantity of carbonic acid in excess of that he expired in the Alps, amounting to as much as 175 per cent. There are no determinations of the carbonic acid expired by the guide at the altitude of Geneva, to compare with those obtained at the seaside on the Island of Teneriffe, but the increase at Teneriffe is greatly beyond any result that might have been expected at the lowest northern station. If my excess of carbonic acid expired on the Peak of Teneriffe, over the amount expired in the higher Alps amounts to 13°8 per cent., while there is no increase in the case of the guide, this is probably owing to the guide apparently perspiring much more freely than I do, and to the circumstance that his home is in the mountains, while I am accustomed to a residence at the sea level. This fact, that an excess of carbonic acid is expired in hot climates over that given out in temperate zones, is to me so unexpected, and, indeed, so different from what might have been anticipated, that I feel bound to give every possible proof of the accuracy of my work. An objection might be raised to the correctness of the analysis from changes occurring in the normal solution of barium from the action of the carbonic acid of the air. This was carefully guarded against; the whole contents of one small bottle were used for each analysis, thus avoiding the necessary introduction of air in opening the bottle had the stock of the alkaline solution been carried in a single large flask. The normal solution was seen to be perfectly clear when poured into the 100 cub. centim. pipette, although it had travelled all the way from London to Teneriffe, and been carried on mule-back to near the summit of the Peak. But a circumstance still more con- vincing of the satisfactory state of the solution of barium was derived from the examination of a bottle of this solution, which had accidentally escaped being used at Teneriffe, and was found after my return on unpacking the basket. The solution in this bottle exhibited a small number of white specks at the bottom, there were so few that on shaking the solution looked clear: on standing the specks re- appeared. I subjected this fluid to a careful analysis. 25 cub. centims. 1879.] Various Altitudes on the Island and Peak of Teneriffe. 507 mixed with 100 cub. centims. of distilled water gave, in order to neutralize 5 cub. centims. of the oxalic acid solution, 9°00 cub. centims. as the mean of six determinations. My normal solution of barium, analysed in London before leaving for Teneriffe, had yielded 8°92 cub. centims.; the difference was only by 0:08 cub. centim. This result would give a very slight deficiency of carbonic acid, but the error might be expected to correct itself in a number of experiments. Finally, it might be objected that, in my Alpine experiment, a loss of carbonic acid had been experienced from the india-rubber bag into which the expired air was collected. In these experiments a certain time elapsed after filling the bag previous to the air it contained being introduced into the tube; this lapse of time ranged between a few minutes and thirty-five or forty minutes, and was required to allow the air in the bag to cool down to the temperature of the water in the tube. No doubt, after a certain time, an escape of carbonic acid might be expected to take place through the substance of the india-rubber bag, but no such escape, in any appreciable degree, could have occurred during the above-mentioned period. This I determined experimentally by subjecting a sample of expired air to analysis immediately after filing the bag, and another sample of the air from the same bag some time later. The results from four analyses made at Cannes in February (1879) were as follows :— E . CO, expired Ties Wes Wes CO, found | Difference per ixperiment. eleg exposed to the | 364. waiti per minute. ne alter waiting. cent. eee 0 °451 25 minutes 0° 454: 0-66 more 7 oN 0°411 ef hah} 0-407 0:97 less. Di iss 0-382 SO rive; 0380 Op525e) At: 0 462 SOnmE 0° 469 1°5 more It is, therefore, obvious that, in my experiments on the Alps, no appreciable loss of carbonic acid through the substance of the bag took place previous to the air being subjected to analysis.* * Tn the whole of these experiments the air had been aspired into the tube for analysis by means either of a nearly saturated solution of common salt or of water. It had not occurred to me, at first, that the fluid adhering to the inside of the tube would have a material influence on the volumetric analysis which was to follow. I determined the mean volume of fluid thus left in the tube, from 14 experiments, to amount to 3°3 cub. centims.; an error thus crept into the analysis, which, though not interfering with the results as to the carbonic acid expired in the Alps, relatively to each other, had, however, to be corrected when these results were compared with those obtained at Teneriffe. It was calculated for every experiment separately both in the Alps and at Teneriffe, and the correction was made accordingly. This work proved very laborious, and delayed considerably the completion of this paper. There is another probable slight source of error to be noticed in the analysis con- 508 Dr. W. Marcet on the Function of Respiration at [Apr. 24, It is known, from Dr. Rattray’s important researches, alluded to above, that the body loses weight by a change from a temperate to a tropical climate, and recovers its weight on returning into a colder latitude, the loss appearing independent of the amount of food taken. This falling off in the substance of the body, attended, as I have shown, by an increased formation and expiration of carbonic acid, must be due to increased combustion or excessive oxidation. It is difficult to offer a theory to explain this phenomenon in our present knowledge of the action of heat on the iving body. Cold we know to increase the amount of carbonic acid formed in the body, the object of which is clearly to keep up animal heat to its normal standard; it is odd indeed that an increase of external heat should exert a similar influence. I do not think it necessary to do more than allude to a tendency to looseness of the bowels I had while on the Island of Teneriffe, which I ascribe to the heat of the climate; the guide informs me there was an opposite disposition with him at Puerto, on the seaside. These minor circumstances interfered in no way with our health, which was quite good, and our work was con- tinued nearly daily, and all day long, during our stay at Teneriffe. The following table gives the result, in a condensed form, of the whole of my inquiry on respiration at Teneriffe, in the sitting posture. (See p. 509.) The chronological order of my visits to the several stations was—. 1. Guajara. 2. Alta Vista. 3. Foot of Cone. 4, Puerto de Orotava (seaside). The number of experiments made sitting amount, for myself, to 65, for the guide to 55, making altogether 120, and, in each of them, a sample of air expired during from four to six minutes was analysed. — The titrations were subsequently all made by myself near Geneva, in the open air, on a balcony, and in order to guard against any acci- dental mistake in the calculations of the analysis, they were all done by myself and an assistant conjointly. There was but a very slight increase in the carbonic acid expired at the two highest stations beyond the amount given out at the seaside, and it bore no comparison with the excess of carbonic acid expired at a similar altitude above the sea in the Alps. The mean excess of the nected with the Alpine experiments, though not with those of Teneriffe, and owing to the circumstance that the solution of common salt used, probably contained a small quantity of alkaline sulphate, the alkali set free by the action of the barium exerted an influence on the titration, apparently increasing the amount of carbonic acid present. Experiments made with three different samples of common salt showed me that the error may safely be limited to 3 per cent., and is certainly much less in many instances. . 1879.] Vartous ‘Altitudes on the Island and Peak of Teneriffe. 509 8T £0-1 6.2 9:0 TZ 4 TS: 8 6SE-0 | $89-0 | &-9L es reese SQYOUT BZG.66 |*''* opisvos ‘oz1ong 1K 18-0 | 9-01 7 10-9 | SP8 ¢8z-0 | 09¢-0 0. 69 060° ‘SUL J66.e¢ “UUM FEg |r tt ee ** vavleny - » Ar i 4 ! ¢ ». S 9T 96-0 | 9-01 aig Li.9 61-0f | 062-0 | 89&-0 | ¢-99 | OO4‘OT | ‘SUI eT¢.0g “TUT Egg | *8" 8 * VISTA BIV Lay ‘uajadngy | "(ge uoxe9) = , 0Z 64-0 L.L TP 78. P-9 662-0 | TZP-0 L. GL a "SUI GZ6.66 “Ut QOL |**** Oprsves ‘ojtong G18) noe é 1G L9.0 VIL GV LY. 69: £ VES. 0 8cP- 0 9.69 0604 "SUL 168.6 “MU FEg | it's vceleny ‘(qydurg tzerg) 0G TZ.0 FIL 8.7 FI-G 10-8 cye.0 | 647-0 6: 19 OOL‘OT | “SUE E1¢.06 “tur [gg | 8 VISTA VITV : - (poumsse) g 18-0 0-01 6-1 66-7 70. 8 662-0 | TLP-0 ¥9 GPL TL | ‘SUL 226-61 “wut gog |****** eUOD Jo Joo Seg “OTT, “SOIT | *SOmgITT | ‘O1QIT ‘STIQ) , “AYBiT "199. ® iB Sty Oty | 42 bg fo) a aes ® ® ct Be (SES EET | ERT |ESS| SPS |EES|ESS|SER| & ho | ¢fe | See EAS esa | see | 228 | Ss8 | Bok eg Bo aon | See | ots | eek | eob | es] Pag | Bae yb ie Z 5 Es S B Bee estos ye Sos || eRe mo |e eae “a ‘gnssoid o1eydsouryy *SULOT}eIG ct Ph @ =e ce oF} ro’ ; Sy OD me ® 10 oo =s OD FR =e 4 2 ec e iee vee OES ie | oe as sae a ; (42) 9°) va . [or e 4 iS) = ‘OINYSOT SUIYIG oY} UI Offt19ue J, 9e syuowTIedxG WoAT Sy[Nsey UWS 9Y}..cULMOYS o]QeV, 510 Dr. W. Marcet on the Function of Respiration at [Apr. 24, two highest stations on Teneriffe, above the amount expired at the sea- side, is only 1:2 per cent., which is so small as to be hardly worth recording. In the Alps, at altitudes somewhat corresponding with those of the Teneriffe station, but in a much colder climate, the excess of carbonic acid expired at the highest over the lowest station was 15 per cent., while, if the mean of the four high stations over the fifth or lower station be taken, it will give an excess of 8°1 per cent. | In the case of the guide, there is not only no increase of carbonic acid expired in the high stations, but we find a considerable increase at the lowest station (above the two others), where the heat felt, and consequently absorbed, was the greatest; this increase amounts to 17°8 per cent. ) The mean volume of air expired, reduced to 32° and the seaside pressure, was observed in my case to fall by 14°5 per cent. from the lowest to the highest station. With the guide there is also a decrease of air expired under similar circumstances by 16-1 per cent. I find the percentage of carbonic acid in the air expired to increase in my case from 4:1 per cent. at the lowest station to 4°9 per cent. at the highest, while with the guide the proportion of carbonic acid in the air exhaled is nearly the same at his three stations. The frequency of my respiration undergoes a marked reduction at the seaside, though nearly the same at my three high stations; the reduction amonnts to no less than 31°2 per cent. In the case of the ouide, the mean number of respirations per minute is exactly the same at his two high stations, but also falls off at the seaside by 25°5 per cent. 3 In all these experiments air was breathed through a mouth-piece, and on that account the rate of breathing was a little slower and apparently rather deeper than if no mouth-piece had been used. The same method was pursued in every experiment, so that the results may be compared with each other with all due regard to strict accuracy. Respiration during a Measured Amount of Muscular Hzereise. In my former communication, I related a certain number of experi- ments referring to the increased expiration of carbonic acid while in the act of ascending. Since then it occurred to me that an inquiry into the amount of carbonic acid expired during a well-regulated walking exercise would yield interesting results. From the difficulty of regulating exactly the degree of muscular power exerted while walking, it occurred to me that some arrangement, on the principle of a tread-wheel, was more likely to answer my purpose, and I finally adopted the tread-boards or rocking-boards described at the beginning of the present communication. While using these boards we raised a weight of 39:5 Ibs. forty-five times per minute, as measured by a metronome, to a height of 5:06 inches for every step. 1879.] Various Altitudes on ihe Island and Peak of Teneriffe, 511. Before collecting the air expired, the boards were worked at the rate of forty-five steps per minute for a short time, in order to bring the body thoroughly under the conditions of the experiment. The 68-4 litre bag connected with the water gauge was held by the hand in the proper position, and at the same time as the first expira- tion into the bag was commenced a preconcerted signal caused the assistant to start the time-piece. A little practice made it quite easy to step in time with the beats of the metronome, counting the number of expirations. As soon as the water gauge showed a pressure of one inch, the watch was stopped and the number of expirations imme- diately recorded. The experiment was then completed as usual. Six experiments were made by each of us at the different stations, and the results are entered in the following table :—(See p. 512.) On considering in this table the amount of carbonic acid exhaled, it will be observed to vary but little at the different stations for both myself and the guide respectively. In my case the amount expired at 10,700 feet and seaside is nearly the same, while there is a moderate increase at Guajara, the intermediate station. In the case of the guide the amount expired at the two highest stations is much alike, and there is a moderate decrease at the lower station. The proportion between the mean carbonic acid expired sitting and en the rocking-boards for each of us respectively at the various stations were:— _ For myself. For the guide. 5 Nenlsto 20a 4.25.3 Eto 22a ee), ae DOSS a ae I 2s PTC HMO eco tts ops Fo cles «83 os 1 OO a de ee NSS Mean, ..<.. NaS a sae IGS Ty secre Consequently, the proportion of CO, is a little higher for both of us at the intermediate station, while the total mean in each case is as near as possible identical, and may be safely considered as the same. These figures show, moreover, that while engaged with the regulated work on the tread-board, we each of us expired nearly twice as much carbonic acid as in the sitting posture. The mean yolume of air expired per minute, reduced, is for myself considerably smaller at the highest station than at the two others; while in the case of the guide we observe a slight falling off in the volume of air expired at the middle station. If the relation between the volume of air and weight of carbonic acid expired for each of us at all the stations be calculated, it will be found that for myself 1 grm. of carbonic acid (expired on the tread- 2 P a é [Apr. 24, tion a of Respira ton O Dr. W. Marcet on the Funct 512 94-1 0-6 &. 4 PP-PL. | 88. ST 229-0 T2-E | 0-G4 | Spsveg | Zz6.6e [rrr ** tt * * oyong OF. T 9. ZT L¢@ | ¥1-8T eF- 8ST 699-0 GTé-T | ¥- PL 0604 £68.86 [rrrrtt ete? erelensy &6-T g- II G- L2-¥1 90- 8% L¥9-0 O48-— | - 19 OO4‘OT | STS-06 [°° °"**** BISTA PITY ~uyadnyo 12. T §- 11 0-% 98-21 | 09-&T P6F- 0 TL6-0 | 8-94 | opiseog | 2z6.63 [o**t tt tt ee *soqtong Lg-T 6-21 ¥-P 09. ST £9. LT LVS. 0 910-1 | 9-54 060°4 168-86 jrerree sees ereleny AL-T 0-8f 1 | 4-6 PI- ST Z0S-0 986-0 | 19 | OO4‘OT | eTg-08 |******** BISIA PITY SP9 O14] | "SorquT | “SOLgIT *O1qT “STL "IYCT 190 7 *soTOUT a's. Bo a8 | Bo < pic. 3 oa > ® ch ts kG ee eee ee eke (eee eee eee | les ee es | ct ib Weel | fee | she Bee = ae Bees See Sok | SBE Ba B Bo & SEER | BES B a o 8 Ss eK & i ae eo = ae ® of ‘ aged B< B 'g.09 28 ee as QO se fee ‘ a TOES ones wo | @ee ee Peas a © Fo | fe 8 : = o ee Ow e @ oS a : & ‘SprvOq-SUIYxIOY oY} UO ope syUOTMIIedxH WOAZ SI[NSoY UEP OY} GUIMOYS 9[q* J, 1879.] Various Altitudes on the Island and Peak of Teneriffe. 518 boards) corresponded to 1:20 litre of air, while with the guide 1 grm. of carbonic acid corresponded to 1°48 litre. As the mean results obtained for the amount of carbonic acid expired sitting and while on the tread-boards, agrees so well with both of us respectively, I have thought it worth while to calculate the mechanical power developed by the combustion of the amount of carbon burnt while working the tread-boards, in excess of that con- sumed in the sitting posture. 17°92 kilos. were raised to a height of 128°5 millims., 45 times per minute. Per 100 kilos. Mean carbonic acid per minute on the tread-board 1 °435 ” ”? sitting co cer cceee 0°676 Excess » expired on the tread-boards...... 0 °759 grm. Corresponding to 103°6 kilogrammetres (0°1285 x 17°92 x 45=103°6) of work done, or 0°00733 (103°6 : 0°759=1: x) CO, expired, was equal to an oxidation of 0°002 grm. carbon, capable of raising 1 kilo. to 1 metre. From Watts’ Dictionary of Chemistry (vol. 111, pp. 105 and 129) the mechanical action of one unit of heat=423°5 gramme-metres, and one gramme of carbon yields by its combustion 8080 units of heat. Therefore, 1000 grammes carbon=8080000 units of heat yielding (8080000 x 423°5) 3421880000 gramme-metres or 3421880 kilogram- metres for the mechanical action of 1 kilogramme of carbon. _ The relation between the above theoretical mechanical power of burning carbon and the actual mechanical power found to be evolved in my experiments was as follows :— 1000 grms. : 3421880=0:002: x. x =6°84, Therefore we only applied =) or 0147 of the power the carbon we burnt on the tread-boards (in excess of that consumed sitting) was theoretically able to exert.* _ As to the percentage of the carbonic acid in the air expired, while on the tread-boards, it increases at the highest station in my case, and this increase is somewhat gradual from the lowest to the highest Station. With the guide the maximum percentage is met with at the middle station. The frequency of the respiration increased in my case from the lowest to the highest station, while with the guide it is slightly. in- _ * There is so little carbonic acid present in the atmosphere, especially at some altitude above the sea (M. P. Truchot, ‘“ Compt. Rend. de l’Académie,” vol. Ixxvii, 1873), that its presence in the air breathed has not been taken into account in- this calculation. 514. Dr. W. Marcet on the Function of Respiration at [Apr. 24, creased at the middle station, undergomg a marked and sudden reduc- tion at the seaside. Water Hxpired from the Lungs at the Various Stations. The third part of my paper refers to the moisture exhaled. It was apparent at the outset that a falling off in the atmospheric pressure, from rising above the sea, would be attended with a corre- sponding increase of evaporation from the lungs, and a proportional cooling effect on the respiratory organs. The apparatus used for the inquiry was disposed as follows :— A tube drawn out at both ends was loosely filled with fragments of calcic chloride; it was large enough to ensure. the absorption of the whole of the vapour expired in three minutes. One end of the tube was connected with one of my large india-rubber bags, while the other end had a ring of vulcanised india-rubber fixed round, to which the mouth was applied. A delicate spring valve (by Coxeter) was fitted into the neck of the tube next the bag, and was weighed with the tube; it effectually prevented any admission of air into the tube except that given out from the lungs. Hither the tube or the bag was placed in communication with a water gauge by a neck and india- rubber tubing. Every now and then the calcie chloride was tested as to its power of retaining all the moisture; this was done by con- necting another similar tube with it and weighing it after breathing through them both. No mouthpiece was used in these experiments, as moisture was found to deposit on anything interposed between the mouth and tube. The air breathed was inspired through the nose only while the whole of the air expired was driven through the tube, the nose being kept closed with the thumb and index. I found no difficulty in doing this with accuracy; great care was taken to keep the saliva from flowing into the tube together with the air expired. Except in the case of a few experiments at the summit of the Peak, I alone submitted myself to this part of the inquiry. The experiments were made by series of usually three at a time, the figures given in my table are the means of those of the different series. The numbers actually obtained gave, of course, the weight of the moisture evaporated from the lungs, together with that of the atmo- spheric humidity of the air exhaled; a correction had, therefore, to be made. I determined the atmospheric humidity by means of dry and wet bulb thermometers, and the corresponding weight of moisture in a given bulk of air was taken from Glaisher’s yoo tables ( Gfth edition). The results from these experiments have been condensed in the following table :— { | 1879.] Various Altitudes on the Island and Peak of Teneriffe. 515 Moisture Expired less Atmospheric Humidity Inhaled. Mean Moisture Barome- | Number | correction| ‘°*P ired | Moisture Stations. trical of experi- for corrected: |(conneeted) pressure. | ments. | humidity for atmo- | expired soy edie spheric per litre. f humidity. Inches. Self. Summit of Peak,| 17°993.| . 3 0-043 0°324 0--0339 12,200 feet. ae Vista, 10,700 | 20°513 38 0" 036 0°314 0:0330 eet. Guajara, 7,090 feet | 23-397 22 0::040 .0°247 | No deter- ; mination. Puerto, seaside ...| 22°922 36 0°05 0°183 . 0 :°0237 | Cupelin. s | Summit of Peak, | 17-993 3 0-066 0 °459 0 -0348 ; 12,200 feet. It was not without some trouble that a few successful determina- tions of the moisture expired were obtained at the highest point of the Peak, 12,200 feet above the sea. This summit is a cup-shaped depression, about half a mile in diameter, volcanic rocks towering round it. The depth of this crater does not appear to exceed 30 or 40 feet, and there is no difficulty in walking across it in any direction. The floor of the crater consists of’ a light white sandy material mixed at places with crystals of sulphur, while recks crop ont here and there. There was a great difficulty in finding a spot sheltered from the sun where I could place my balance and sit down to breathe through the tube, At last some shade was obtained for the balance by means of a blanket, and we managed to creep into a narrow place between two rocks, where the sun’s rays could not penetrate. The heat was intense, the sun pouring down upon the Peak from a perfectly clear sky, aud everything being nearly too hot to be touched, notwithstanding the intense terrestrial radiation at that altitude. Apparently every circumstance combined to baffle my experiments; the balance would not remain ina horizontal position ; a light breeze kept blowing the fine sand about, and I had constantly to remove the beam of the balance to wipe the points of suspension ; then the blanket would not keep in its required position; and I had to lay down at full length on the hot sand without any shelter from the sun to get through the weighings. * Calculated from Glaisher’s Hygrometrical Tables, 516 Dr. W. Marcet on the Function of Respiration at [Apr. 24, The few experiments I succeeded in completing at that spot, showed an evaporation of water from the lungs above that expired at the sea- side, equal to 0'141 grm. per minute, or 43°5 per cent. If the weight of moisture expired at the three principal stations be considered together with the altitudes of the stations, a certain relation will be found to exist between them; this relation is established in the following table, showing what the proportions of humidity expired would amount to if calculated with reference to the barome- trical pressures. These figures are entered in the column of the following table headed Theory. Water Hxpired. , ‘ | Barometer. Theory. Found. Difference. Puerto....760 wmillims.} 0°183 grm. 0°183 grm. |. Guajara...594°4 ,, 0°234 ,, 0:°247 ,, 5 per cent. Alta Vista.521°4 ,, 0-267 ,, 0-314 ,, gui The results obtained show, therefore, that the evaporation of moisture from the lungs increases as the barometer falls. The ratio is, however, no more than approximate. 1 question whether a similar result would be obtained in the Alps, where the cold at certain heights must exert a considerable influence on the evaporation from the lungs and air passages. fesults from the Investigation. Tke results I have obtained from my experiments on the Island of Teneriffe may be expressed as follows :— 1. The mean of the whole amount of the carbonic acid expired at the three stations (the experiments at the foot of cone not included ) in the sitting, posture, and determined from 60 experiments in my case and 55 in that of the guide, was proportional to the weights of our bodies respectively, and amounted to 676 mgms. per 100 kilos. ~ for each of us. 2. The mean weight of the whole carbonic acid ed heal at the three stations while eneeed with the same amount of measured muscular work, and determined from 18 experiments for each of us, was respectively proportional to the weights of our bodies. 3. The mean weight of carbonic acid expired by both of us (with one exception only) was highest during the first or second hour after a meal, while it diminished by degrees as time elapsed since food was taken. This agrees with my results obtained in the Alps. 4, The mean weight of carbonic acid expired by myself on the 1879.] Various Altitudes on the Island and Peak of Teneriffe. 517 Island of Teneriffe is greater than it had been in the Alps, and, more: over, this same result holds good for corresponding altitudes. The mean excess for all the experiments on Teneriffe in the sitting posture, amounts for myself to 14°0 per cent. It was at the seaside that the increase in my case reached the maximum, 18°7, when com- pared with the weight of carbonic acid expired near the Lake of Geneva, I have only four experiments to place on record made on the guide in the Alps (St. Bernard) ; these compared with the means of the experiments to which he subjected himself at the seaside, Teneriffe, gave for the latter station an increased expiration of car- bonic acid by 17°5 per cent. There was, however, no increase for the higher stations at Teneriffe. 5. While, in the Alps, the maximum quantity of carbonic acid was expired by myself at the highest station, 13,685 feet above the sea, where the body underwent the greatest degree of cooling, especially from the low temperature of the air; on the Peak of Teneriffe, the weight of carbonic acid I expired at the various stations differed but little. 6. The weight of carbonic acid expired in a given time by myself on the Peak of Teneriffe varies but little from one station to another, although I show a tendency to give out slightly more of this gas at the two highest stations—mean altitude 11,222 feet—than at either 7,090 feet high, or the seaside. The increase for the mean of the two highest stations above the amount expired at the seaside is only 1:2 per cent. In the Alps, the excess of carbonic acid I expired at 13,685 feet, over the amount given out near the Lake of Geneva at 1,230 feet, or for a difference of altitude of 12,455 feet, amounted to 15 per cent. This result is accounted for from the temperature of the air, which was much colder in the Alps than on the Peak of Teneriffe. In the case of the guide, a great deal more carbonic acid was expired at the seaside on the Island of Teneriffe than on the Peak, the excess amounting to 17 per cent.; while I expired about as much carbonic acid at every altitude on that Island. This occurred appar- ently because the guide perspired more than I did at the higher stations; moreover, I am accustomed to live at the sea level, while the guide had never been away from the Alps, and his life, in summer, is spent, in a great measure, accompanying tourists to the highest peaks and passes in the Alps; his home at Chamounix is 3,451 feet above the sea. 7. The volume of air I expired per minute reduced to 32° F. and seaside pressure decreased gradually from the seaside to an altitude of 11,745 feet, the difference for the two extreme stations amounting to 14°6 per cent. This result agrees to some extent with that obtained in the Alps, although the Alpine decrease amounted only to 5°6 per 518 Dr. W. Marcet on the Function of Respiration at [Apr. 24, cent. The volume of air expired in the case of the guide exhibits a similar change, amounting to 22°6 per cent., but the decrease stops at Guajara, the intermediate station. The total mean volume of air expired per minute, at every station (the foot of the cone excepted), while in a sitting posture, was for myself 5°36 litres, and for the guide 6°75 litres. 8. The percentage of carbonic acid in the air expired exhibits nearly the same changes on the Island of Teneriffe as in the Alps. At Teneriffe it rose from 4:1 per cent. at the seaside to 4:9 per cent. at 11,945 feet, while, in the Alps, the proportion had varied from 38 per cent. at 1,230 feet to 4°7 per cent. (St. Bernard) at 9,403 feet. If the total mean proportion of carbonic acid in the air expired, reduced, for the three stations of Alta Vista, Guajara, and Puerto be calculated, it will be found to amount, for myself, to 4°4 per cent. and for the guide to 4°6 per cent., or to be nearly the same. The mean from the eighty-nine experiments I made in the Alps, in the sitting posture, yielded 4°2 per cent. of carbonic acid expired. 9. The frequency of the expirations fell considerably in both cases at the seasidé, or increased on rising above the sea, but was much the same for each of us respectively at the different stations on the Peak. The reduction at the seaside, from the mean frequency of respiration at the upper stations, amounted for myself to 31°2 per cent., and for the guide to 25°5 per cent. In the Alps there had been a somewhat gradual rise of the frequency of the respirations between the lowest and highest stations, equal in my case to 34°9 per cent. 10. While raising with the feet a weight of 39°5 lbs. to an senate of 5:06 inches forty-five times per minute, we both expired the least amount of carbonic acid at the lowest station, and the most at the intermediate station, 7,090 feet high. The fluctuation between the various stations was much the same for each of us respectively, although the actual amount expired by each of us differed in a marked degree. The mean relation for both of us respectively, between the carbonic acid expired sitting and on the rocking-boards, was found to be the same, and a trifle over twice the weight of the carbonic acid expired sitting. The volume of air breathed while at work was decidedly less in my case at Alta Vista than at the two lower stations, with the guide there was a falling off in the air expired at Guajara. The mean volume of air expired per minute, in all the experiments on the rocking-boards, was for myself 11°56 litres, and for the guide 13°96 litres. ? The general result obtained, with reference to this subject, was that the relation between the volumes of air expired while sitting, and while engaged with a regulated amount of muscular work, was the same as the relation found to exist between the weights of carbonic acid expired under such circumstances, and moreover that these pro- 1879.1 Various Altitudes on the Island and Peak of Teneriffe. 519 portions were practically the same for both of us. The relations are as follows :— Sitting. Rocking-board.| Relations. Self Air expired...........| 5°36 litres 11°56 litres Lee216 Carbonic acid expired..| 0°469 grm. 1011 grms. I ALS Gclin PAE CMPITE Ws oe exci cy. « 6°72 litres 13°95 litres a ta ag Carbonicacicexpired| 0°603 grm. 1:269 grms. tia ZalO As to the frequency of the respiration, while at work on the rocking- boards, it was the greatest with me at the highest station, and with the guide at the intermediate station; in both cases it was the lowest at the seaside. The mean frequency amounted, in my ease, to 12°4 per minute against 10°2 sitting, giving a relation of 1:22; or for 1 respiration (expiration) sitting, I took 1°22 respiration on the tread-board. With the guide, the corresponding figures were 11:0 against 9°/7, and the relation 1:13; so that for 1 respiration sitting, the guide took 1:13 respiration on the tread-board. His breathing while taking muscular exercise was, therefore, relatively rather slower than mine had been under similar circumstances. 11. The results obtained from the determination of the water expired, or evaporated from the lungs and air-passages, show distinctly that the moisture exhaled increases as a person rises above the sea. On the Island of Teneriffe, where the temperature in the shade is com- paratively high, even at great altitudes, there is a tendency to the degree of evaporation being in an inverse ratio to the atmospheric pressure. It is very obvious that this increased evaporation as altitude increased must have caused a corresponding loss of heat, or cooling of the lungs and air-passages; I felt this very much at night, when the temperature of the air frequently fell below freezing outside my tent. Of course, no number of blankets on our beds could check that source of cold. The amount of water evaporated from my lungs and air-passages during twelve hours of daytime, calculated from the above data, would be— At Alta Vista ae ‘ir 226°1 grms. At Guajara .. ‘ iP WATT Re mss At Puerto lacey’. Hip SS oss The correction to be applied from the moisture present in the air breathed increased, of course, very much at the seaside, where it formed a considerable proportion of the moisture actually present in the air expired. 520 Dr. F. W. Pavy on the [ Apr. 24, V. “Further Researches on the Physiology of Sugar in relation to the Blood.” By F. W. Pavy, M.D., F.R.S. Received April 3, 1879. The results brought forward in this communication are supplemen- tary to those published in the ‘‘ Proceedings of the Royal Society ” for June, 1877 (vol. xxvi, pp. 314, 346). The first of these communications was devoted to the consideration of the quantitative determination of sugar for physiological purposes. Some important physiological conclusions had been drawn by Bernard from the results obtamed through a modified method introduced by him of employing Fehling’s solution. I pointed out the manner in which I considered the process in question to be open to fallacy, and showed that the results yielded by it differed to a marked extent from those yielded by a gravimetric method, which I described, of using the copper test. I have since continued my investigations, and have now results to bring forward obtained by another process, which I described in a com- munication read at the Royal Society, January 16, 1879, and published in the “ Proceedings,” vol. xxviii, p. 260. This process does not differ in principle of action from Bernard’s, and if there were no fallacy in either case involved, the results yielded by the two should agree. In both the reduction of the oxide of copper 1s made to occur without the precipitation of the reduced oxide, so that the change to be watched in the action of the test is a progressive decoloration, unobscured by the presence of any deposit. In Bernard’s process this result is brought about by the action of potash in a concentrated form upon the organic matter incidentally present in the product prepared for exami- nation, and the agency in force is, according to the view I have expressed, the development of ammonia. In my own process, for particulars regarding which I must refer to the published communica- tion in the “‘ Proceedings,”’ ammonia is added to the test, and no fixed alkali employed beyond that present in Fehbling’s solution. By means of this new process an opportunity is afforded of ascer- taining on which side the fault lies in the disagreement between the results obtained by Bernard’s and the gravimetric method, The accompanying table contains the results given by the applica- tion of the three processes to six specimens of blood, The figures in the first two columns are derived from the analyses resect conducted with the use of potash (Bernard’s plan) and ammonia, and with the adoption of Bernard’s proposition that the liquid obtained from equal weights of blood and sulphate of soda measures, in cub. centims., four-fifths of the (OR weight in grammes of the sulphate of soda ind blood taken. 1879. ] Physiology of Sugar in relation to the Blood. 521 The figures in the next two columns represent the results given by the same two processes of analysis applied to the product obtained after the plan adopted for the gravimetric process. The blood is treated with sulphate of soda, filtered, the coagulum thoroughly washed to extract all the sugar, and the filtrate and washings brought to a known volume. The last column furnishes the mean of two gravimetric analyses carried out upon two portions of the blood distinct from that employed for the analyses in columns 3 and 4, Results given by Bernard’s, the Ammoniated Cupric, and the Gravi- metric Processes for the quantitative determination of Sugar in Blood. Sugar per 1,000 parts. With Bernard’s formula | Preparation of blood for estimating volume| product by the pro- Source. of liquid derived from| cess employed for the the blood. gravimetric method. Gravimetric process. Mean of two Bernard’s |Ammoniated| Bernard’s |Ammoniated ES potash cupric potash cupric process. process. process. process. I, Sheep.... 0°930 0 °560 0 842 0°571 0°589 IT. Bullock .. 1-212 0°901 0-980 0-650 0°735 IIT. Bullock .. 1-568 1-130 1 °240 0-896 0-921 TY, Sheep... 0-888 0 °579 0°905 0 °567 0 °533 V. Bullock .. 0°816 0°534 0-839 0°559 0°511 VI. Sheep,...| 0°879 0-635 0-945 0-650 0°631 On looking at the results the first point to which attention may be directed is that evidence is supplied showing that reliance cannot be placed upon the formula adopted by Bernard for calculating the volume of liquid derivable from the weight of blood taken for analysis. The figures in columns 3 and 4 were drawn from direct observation, and if the formula supplied correct information, the results in columns 1 and 3 and 2 and 4 should respectively coincide. It is noticeable, however, that whilst in some instances they approach closely towards agreement, in others there is a pretty wide divergence. In the second place it is seen that the results obtained by the method of analysis involving the employment of the potash stand considerably higher than those yielded by the ammoniated form of the test. It may be assumed that in the action of the potash on the incidental organic matter present to give rise to the required condition for main- 522 Dr, F. W. Pavy on the | oy pelvagors: eo taining the suboxide in the dissolved state, a reducing substance becomes developed, or else that the amount of oxide of copper appro- priated to the oxidation of the sugar becomes altered in the presence of the large amount of potash which it is necessary to employ. Lastly, it may be observed that a close conformity exists between the figures in columns 4and 5. The results obtained by the gravi- metric method are thus confirmed by the volumetric results obtained by means of the ammoniated form of the cupric test. Seeing that separately prepared specimens of the respective samples of blood were submitted to the two kinds of analysis, the conformity is certainly striking, and gives strong weight to the validity of the results yielded by the gravimetric method. One of the points referred to in my second communication * is the spontaneous disappearance of sugar from the blood after withdrawal from the body. It is a part of Bernard’s doctrine that the natural seat of destruction of sugar within the system is in the systemic capillaries, and if it can be shown that an active disappearance of sugar occurs in the blood after removal from the vessels, support is given to his proposition. I cited the observation which has been adduced by Bernard to illustrate that a marked aptitude exists for the disappearance of sugar under the circumstances named. According to this observation, a reduction from 1:070 to 0-880 parts per 1,000 occurred during the first half-hour, and at the end of 24 hours the analytical result obtained is represented as standing thus—0-000. I stated that my own experience furnished evidence of a widely different nature, and introduced the figures yielded by five observations in proof of this assertion. The gravimetric process is only suited for the examination of blood before decomposition has set in, as the result would be vitiated by the presence of ammonia as a product of decomposition, the effect being an interference with the deposition of the cuprous oxide, With the ammoniated cupric test, however, any state is suitable; and since my communication of June 21st, 1877, was published, I have applied this process, as well as Bernard’s potash process, to blood which has been kept for lengthened periods, instead of limiting the examination, as I had previously done, to the first twenty-four hours. The results obtained were quite unlooked for, and quite irreconcileable with the representation in Bernard’s observation, which has been referred to, that at the end of twenty-four hours the blood ceased to give any indication of the presence of sugar. _[ have before me a large amount of recorded experience, but need only select a few illustrative examples, for the information supplied is of the:same nature throughout. In no case, although the blood had acquired a highly offensive character from putrefaction, has it failed to *® © Proc. Roy. Soce.,” vol. xxvi, p. 346. 2879.) Physiology of Sugar in relation to the Blood. 523 exercise a decided amount of reducing power over the copper test. It will be seen in the succeeding observations that there is a period during the first few days when the reducing power undergoes a pretty sudden fall, and that it afterwards remains nearly stationary. If the reducing action is to be attributed to sugar, and sugar only, it would have to be said that sugar can exist in a mass of putrefied blood without under- going destruction. It seems to me, and this view is supported by evidence to be presently adduced derivable from the addition of sugar to decomposing blood, that there is another reducing substance present besides sugar which is not affected in a similar manner by contiguous decomposition. The period of sudden fall, it appears, may be taken as corresponding with the disappearance of sugar, and this, it will be noticed, presents a variation within certain limits. In the observations at the top of the list the period is more prolonged than in those lower down. It is possible that this may have arisen from the atmosphere of the laboratory having become influenced by the presence of decom- posing samples of blood. The earlier observations were conducted with the application of Bernard’s process only, as it was not until June, 1878, that I began to apply the ammoniated cupric liquid. In the employment of this liquid the same product prepared from the blood was used as for Bernard’s mode of testing. It is noticeable that the results yielded by the two processes differ from each other in the manner that has been already commented upon. Decomposition of Blood in relation to Sugar. Reducing action, expressed as sugar per 1,000 parts. | Boraarta Ammoniated process. ig process. I, Blood of bullock. Wawygoriwithadnawal, sya .cci- eile crs e+ +e oe 00 02 1 -066 SEG AWS ALLOVWVA TOS ters oxs) oyopeir core (ersia-s)oevere-a'0 0 ‘987 4 ,, 5 5 0-808 B04; * 0-215 , II. Blood of sheep. Wimorewithdrawal J. ..5-.6cc08es ss se asecne 0-909 Sdlavs alberwards 00). 005 ene cle wel pee sowie 0°325 ae " ; 0-308 8 oy) 9 0 283 2) if Upc, SNe ST Ee4 9 50) 4% rs fected bap: ek beipay enie eee 0-242 | III. Biood of bullock. remot wih Gaya “cleraa « «)) love alsa.» +) +1) ie! ebellen 1°333 | Mmelay ea LeU VyA COS) isle Ualelial= Jo) cls custete\>leiekale nel) eee 0 °365 | Aoays ihn 0 :353 gee % 0-259 30 ,; A 0-242 524 . Dr. F. W. Pavy on the — - [Ape 2s Reducing action, expressed — as sugar per 1,000 parts. Bernard’s | Ammoniated process. Wig oe process. IY. Blood of bullock. Daysor watlicnawal eee sa ate e inact eietteceie 1°600 1 day afterwards ,.,...... 2605902030795 (1°311 2 days 5 DIP OO 0906 Se Bow 085 0°816 Ag, sso) i eeeeece Bioneiieinn apes otis 0°740 (eer 5 Malehetec te ehaleie ia es ee 0°392 17 aR ee tes nT ene Pa 0 +322 26 = : cere cees 0°273 VY. Blood of ‘sheep. Dayor wathdrawalvi wl siee ate ele > niece 0-898 He GaygatteRwoatG Simcielyairetetsiti ttt tial 456 0-851 2 days as g elsaroltete ia etetoloseestsucr ueveseteteie 0 °328 as oeisier 1°418 Tent 1 day afterwards goss. c-<. cle sme este ue) om Om Oily 2 days 9 {p00 d00d00 838090056540 0° 869 0 °545 Sys +, Bek eaneier: iis ici ee ates 0°369 0-294 In the following series of experiments sugar was added to blood at different periods after withdrawal. The results furnish the same kind of evidence as that obtained through the previous observations. A marked descent is noticeable in the reducing power until a certain point is attained, after which but little change occurs, however long the blood may be kept, and however putrid it may become. It seems, therefore, as already suggested, that there is a reducing agent in the blood which comports itself differently from sugar. If the reducing action were due solely to sugar, it is not intelligible that there should be a more or less sharp descent to a certain point, and then thai 1879.] Physiology of Sugar in relation to the Blood. 025 the condition should remain comparatively stationary. There is no reason that the last portion of sugar should behave differently from the first. Something having a reducing power, on the other hand, appears to exist which possesses a stability greater than that enjoyed by sugar, and which, thus resisting the influence of the changes of decomposition, produced the reducing effect on the test exerted by the blood after keeping for thirty days. Observations on the Blood after the addition of Sugar. Reducing action, expressed as sugar per 1,000 parts. B ; Ammoniated ernard’s : ? cupric process. process. I. Blood of sheep, in fresh state. . : 0:919 0°723 After the addition ‘of sugar 4-210 3°921 On the following day .. edie he 1°481 1-419 Ghapt lier anda chy, Vet clers ise ai cree © « 0-409 0-267 On the 5th day 0°250 0°175 Il. Blood of bullock, 4th day after withdrawal .... 0°351 0°317 After the addition of sugar ...... 1°481 1 SIBY0) On the 3rd day se EET 0-800 0°725 On the 4th day es wae O88 0-293 Onbtle Sth day rrseieclaiti< -- + « 0 °333 0°279 IE Blood of bullock, in fresh state ......c.sece0 1:000 0°776 After the addition of sugar ...... 4, 4.4.4, 3 636 On the following day........... 3 478 2°811 On the 3rd day : 1 °052 0°296 | On the 6th day ...... 0 °363 0 °228 . The original blood to which no sugar had been added, examined on the 6th day . 0-310 0° 225 | IV. Blood of bullock, in fresh state ...... Sanus 1-000 0°776 | ieeers the addition of sugar. 2 666 2°105 On the following day .. oe 2 °285 1°960 Oiin tov Gixel Ceiy og goon coon Gocdr 1°176 0:980 On the 6th day 0°298 0 :238 VY. Blood of sheep, in putrid state. 0°234 After the addition of sugar 0 °834 On the following day . is Sa 0 :476 On'the ord day 0 so sicaseseso<- 0 °330 VI. Blood of sheep, in putrid state ............5. After the addition of sugar ......| +. .. eat On the following day ............] +. 56 0 °434 Oni the Srdudayae vada eceaen sete 0 5.5) Kee es es 0°300 On the Athy dayiy. recite ss sit seme] ae ve 0° 256 VOL. XXVIII. . 2° Q 526 Dr. F, W.. Pavy on the [ Apr. 24, Reducing action, expressed as sugar per 1,000 parts. Beraardc Ammoniated cupric process. process. VII. Blood of sheep, in putrid condition..........] .«. ore 0°330 After the addition of sugar ......| «. 56 1°616 On the following day, the tempera- ture having been meanwhile main- bast. Be SO ING none vane bo sase 0°250 On the 3rd day 8 0-257 VIII. Blood of sheep, in putrid state..............) «- te 0° 225 After the addition of sugar Bn 1-960 On the 3rd day : 0 °325 In a further series of experiments, blood with added sugar was subjected to the influence of a current of different gases. I was desirous of ascertaining if oxygen promoted the disappearance of sugar, and counterpart observations were made with carbonic acid and hydro- gen. ‘The results obtained afford no evidence of any chemical action being exerted. Whatever slight effect occurred, I think, may be assumed to have arisen from increased molecular action excited by the transit of the gas. Passage of Gases through Blood in relation to the disappearance of Sugar. | Sugar per 1,000 parts. By ammoniated cupric process. | I. Blood from sheep, in fresh state with sugar added 0-865 | After standing 2 hours at the ordinary tem- | perature .... 0 °855 After the pass sage ‘of oxygen ‘for 2 hours at | ordinary temperature. . ae Ht 0°844 | II. Blood from sheep, in fresh state, with sugar added 1°634 After standing 23 hours at 100° F.. 1 °459 After the passage of ee for 25 hours at 100° F. 1 °285 After the passage of carbonic acid for 2h MOTI CHO INS AA oo nondse da 65 qe so 0408 1:100 III. Blood from sheep, in fresh state, with sugar added 1 667 After standing 7 hours at 100° F. ....... ; 1°342 After the eee of oxygen for 7 hours a 100° F.. , 0-992 After the “passage of carbonic acid for 4 OUTS Tat) LOO GE Te oreertetetchareelelendntr terete 1° 042 1879.] IV. Blood from sheep, in fresh state, with sugar added After standing for 7 hours at sents raised temperature | After passage of oxygen for " “hours at slightly raised temperature ..... After passage of carbonic acid for7 hours at slightly raised temperature ..... After passage of hydrogen for 7 hours at slightly raised temperature .........0.0. V. Blood of sheep, in fresh state, with sugar added After standing 63 hours at 100° F......... After the Bee of oxygen for 6% hours at 100° F.. After the passage of carbonic acid for 6h hours at 100° F.. SHO OU Ou bIdGooe VI. Blood from sheep, in fresh state, with sugar added ... Masood 66 After standing an hours at 100° F.. After the ee of ee for 63 hours at 100° F. After the passage ‘of carbonic acid for 63 ounsat LOOM ys. aje'eo) sell oe ob 60tooC be VII. Blood from sheep, in putrid state, with ee added .... ceelscicae After sti mding 6 hours at 100° F. .. After the pate of oxygen for 6 hours at P 100° F. After the passage ‘of carbonic acid for 6 InoustatilOOMH n tttecignic «eis ses «\s)o.510 VIII. Blood from sheep, in putrid state, with sugar added ..... als/e}/eye\lela) elellois After standing Ghours st 100° F. ........ After the eee of cee for 6 hours at LOO; i)”. Physiology of Sugar in relation to the Blood. ~ 3) 27 Sugar per 1,000 parts. By ammoniated cupric process. L 1 L 1: iL° 1 1 Se & Oj "850 550 °025 525 570 “475 “324 134 -209 ‘775 567 475 492 324 -667 606 654 551 218 °233 The following conclusions may be expressed as constituting the issue of the results recorded in this communication :— That the results bearing on the physiology of sugar in relation to the blood derived from the application of the gravimetric process, and given in my former communication to the Royal Society (vol. xxvi, p. 3846), are confirmed by those yielded by the ammoniated cupric test, described by me in the “ Proceedings,” vol. xxviii, p. 260. That the disappearance of sugar from the blood after withdrawal from the system takes place in the gradual manner that might be expected from the effect of ordinary decomposition, and presents nothing to support any conclusion regarding the destruction of sugar in the blood as a physiological phenomenon. 292 528 (Presents. | [Apr. 3, That there appears to exist a reducing substance besides sugar in the blood which is of a sufficiently stable character to resist the effects of advanced putrefaction. Expressed as sugar, it amounts to from ‘200 to *300 per 1,000. These figures, therefore, would appear to require to be deducted from those which have been given as repre- senting the amount of sugar present in the blood. That the passage of a current of oxygen through the blood does not exert any appreciable effect in the direction of oxidation of the sugar. Presents, April 3, 1879. ‘Transactions. Devonshire Association for the Advancement of Science, Litera- ture, and Art. Index to tenth volume of the Transactions. 8ve. The Association. London :— Institution of Civil Engineers. Minutes of Proceedings. Vol. LY. Session 1878-79. Part1l. 8vo. London 1879. The Institution. Moscow :—Société Impériale des Naturalistes. Bulletin. Année 1878. No. 3. 8vo. The Society . Rome :—R. Comitato Geologico d’Italia. Bollettino. Anno 1879. No. le2. 8vo. Roma. The Institution. Tubingen :—K. Hberhard-Karls-Universitat. Festschrift zum vier- hundertjahrigen Jubilaum, von Walter Funke. roy. 8vo. Berlin 1877. . The University. Turin:—R. Accademia delle Scienze. Atti. Vol. XIV. Disp. 1. 8vo. Torino 1878. | The Academy. Reports, &c. Cambridge [U.S.] :—Museum of Comparative Zoology at Harvard College. Bulletin. Vol. V. No. 8-9. 8vo. 1878. The Museum. Kiel :—Sternwarte. Astronomische Nachrichten, begriindet yon H. C. Schumacher, herausgegeben von OC. A. F. Peters. Band LXXXVITI—XCIII. 4to. Kiel 1876-78. The Observatory. Journal. s Zeitschrift fiir die gesammten Naturwissenschaften; redigirt von C. G. Giebel. 3° Folge. 1878. Band III. 8vo. Berlin 1878. The Editor, a 1879. ] Presents. 529 Donnadieu (A. L.) Université Catholique de Lyon. Organisation du Service de la Zoologie 4 la Faculté des Sciences. 8vo. Paris 1879. The Author. Hooker (Sir J. D.), F.R.S., and J. Ball, F.R.S. Journal of a Tour in Marocco and the Great Atlas. 8vo. London 1878. The Author. Luvini (G.) Una Sperienza di Magnetismo. Nota. 8vo. Firenze 1878. Intorno alla Induzione Elettrostatica Sperienze e ragionamenti. 8vo. Firenze 1&78. The Author. Marriott (W.) Sur le Psychrométre. 8vo. Paris 1877. The Author. Presents, April 24, 1879. Transactions. zi Hdinburgh :—Royal Scottish Society of Arts. Transactions. Vol. Ie Part >. Vol, X. Part 1. 8vo. 1878. The Society. Frankfort-on-Main. Senckenbergische Naturforschende Gesell- schaft. Abhandlungen. Band XI. Heft2~-3. 4to. Frankfurt-a- Main 1878. Bericht. 1876-1877, 1877-1878. 8vo. The Society. Graz :—Naturwissenschaftlicher Verein fiir Steiermark. Mittheil- ungen. Jahrgang 1878. 8vo. 1879. The Society. London :—National Association for the Promotion of Social Science. Transactions. Cheltenham Meeting, 1878, 8vo. 1879. The Association. Zoological Society. Transactions. Vol. X. Part 10-11. 4to. 1879. Proceedings of the Scientific Meetings, 1878. Part 4. 8vo. The Society. Observations, &c. Cape of Good Hope:—Royal Observatory. Results of Astronomical Observations made in the years 1859, 1875. 2 vols. 8vo. 1875- 1877. The Observatory. Coimbra :—Observatorio Meteorologico e Magnetico. Observagoes Meteorologicas e Magneticas. 1878. Folio. The Observatory. Greenwich :—Royal Observatory. Astronomical and Magnetical and Meteorological Observations made in the year 1876, under the direction of Sir George B. Airy, K.C.B. 4to. London 1878. Nine-year Catalogue of 2,263 Stars tor 1872. 4to. Astronomical Results. 1876. 4to. Magnetical and Meteorological Observa- tions. 1876. 4to. Reduction of Meteorological Observations. 530 Presents. Observations, &c. (continued). : Barometers, 1854-1873. Air and Moisture Thermometers. 1849-1868. Earth Thermometers. 1847-73. 4to. 1878. The Admiralty. Madrid :—Cartas de Indias; publicalas por primera vez el Ministerio de Fomento. Folio. 1877. The Spanish Minister. Washington :—United States Naval Observatory. Astronomical and Meteorological Observations made during the year 1875. Ato. 1878. The Observatory. Clebsch (A.) Legons sur la Géométrie, recueillies et complétées par F. Lindemann, traduites par A. Benoist. Tome I. 8vo. Paris 1879. Cunningham (D. D.) On certain effects of Starvation on Vegetable and Animai Tissues. 4to. Calcutta 1879. ‘The Author, Dunkin (H.), F.R.S. Obituary Notices of Astronomers: Fellows and Associates of the Royal Astronomical Society. 8vo. London 1879. The Author. Guthrie (Francis). Continuous Girders, Arched Ribs, and Tension Circles. 8vo. Cape Town 1879. The Author. Henle (J.), For. Mem. R.S. Handbuch der Nervenlehre des Menschen. 8vo. Braunschweig 1879. The Author. Jackson (lL. d’A.) Canal and Culvert Tables, based on the Formula of Kutter, under a modified classification, with explanatory text and examples. 8vo. London 1878. The India Office. Jousset de Bellesme (Dr.) Travaux Originaux de Physiologie com- parée. Tome I. Insectes. 8vo. Paris 1878. The Author. Lewis (T. L.) The Microscopic Organisms found in the Blood of Man and Animals, and their relation to Disease. 4to. Calcutta 1879. The Author. Oppert (G.) On the Classification of Languages: a contribution to Comparative Philology. 8vo. Madras 1879. The Author. Preston (T. A.) Wiltshire Rainfall. 1878. 8vo. Marlborough 1879. The Author. Stevenson (David). Life of Robert Stevenson, Civil Engineer. Ato. Edinburgh 1878. The Author. INDEX to VOL. XXVIII. Abdominal circulation, forces concerned in (Hicks), 489. Acoustics, studies in: I. On the syn- thetic examination of vowel sounds (Preece and Stroh), 358. Aleurone grains, on the chemical compo- sitiow of (Vines), 218. Anatomy of the skin, on some points connected with the (Thin), 251. Anniversary meeting, 30th November, 1878, 42. Astacus fluviatilis, physiology of nervous system (Ward), 379. Auditors, election of, 1; report of, 42. Auwers (A.), elected, 461. Ayrton (W. E.) and Perry (J.). The magic mirror of Japan. Part I, 127. , the contact theory of voltaic action: No. III, 421. Balance, on a method of using the, with great delicacy, and on its employment to determine the mean density of the earth (Poynting), 2. Balance-sheet, 70. Blunt (T. P.) and Downes (A.) on the influence of light upon protoplasm, 199. Bonney (Rev. T. G.), admitted, 1. Bottomley (J. T.) on the thermal con- ductivity of water, 462. Brongniart (A. T.), obituary notice of, iv. Butlin (H. T.) on the nature of the fur on the tongue, 414. Candidates for election, list of, 6th March, 1879, 378. Carpenter (P. H.), report on the Coma- tule of the “ Challenger ’’ expedition, 383. Cartilage, on hyaline, and deceptive appearances produced by reagents, as observed in the examination of a car- tilaginous tumour of the lower jaw (Thin), 257. “ Challenger’ expedition: report on Comatule (Carpenter), 383. Charcoal, absorption of gases by (Smith), 322. Chelone Midas, 329. Chemical composition of aleurone grains (Vines), 218. Chemical equivalence, researches on: Part I. Sodic and potassic sulphates (Mills and Walton), 268; Part II. Hydric chloride and sulphate (Mills and Hogarth), 270. Chromospheric lines, preliminary note on the substances which produce the (Lockyer), 283. , Young’s list of, discussed, No. I (Lockyer), 432. Clarke (G. 8.) and McLeod (H.) on the determination of the rate of vibra- tion of tuning-forks, 291. Clarke (Rev. W. B.), obituary notice of, i. Coal-dust, its influence in colliery explo- sions, No. II (Galloway), 410. Coal-measures, organisation of the fossil plants im (Williamson), 445. Cockle (Sir J.) admitted, 102. Colliery explosions, influence of coal- dust in, No. IL (Galloway), 4:10. Comatule of the ‘‘ Challenger ”’ expedi- tion, report on (Carpenter), 383. Conroy (Sir John), some experiments on metallic reflexion, 242. Contact theory of voltaic action: No. IV (Ayrton and Perry), 421. Convoluta Schultzii, physiology and his- tology of (Geddes), 449. Copley medal awarded to J. B. Bous- singault, 13. Crayfish, physiology of the nervous sys- tem (Ward), 379. Cremona (L.) elected, 461. ; Crookes (W.) on repulsion resulting from radiation: Part VI, 35. , on the illumination of lines of mole- cular pressure and the trajectory of molecules, 1038. , on electrical insulation in high vacua, 34:7. , contributions to molecular physics in high vacua, 477. Cross (Right Hon. R, A.) elected, 461; admitted, 483. Cupric (ammoniated) test for sugar (Pavy), 260. 532 Darwin (G. H.) on the precession of a viscous spheroid, and on the remote history of the earth, 184. , problems connected with the tides of a viscous spheroid, 194. Davy medal awarded to L. P. Cailletet and R. Pictet, 68. Declination magnet, note on the inequa- lities of its diurnal range, as recorded at| the Kew Observatory (Stewart), 241. (magnetic), a comparison of the variations of the diurnal range of, as recorded at the observatories of Kew and Trevandrum (Stewart and Mo- risabro Hiraoka), 288. Dewar (J.) and Liveing (G. D.) on the reversal of the lines of metallic vapours : No. IV, 352; No. V, 367; VI, 471. on a direct-vision spectroscope, 482. Dielectrics, on the specific inductive capacities of certain: Part I (Gordon), 155. Donation fund, account of grants from the, in 1877-78, 75. Downes (A.) and Blunt (T. P.) on the influence of light upon protoplasm, 199. Earth, on a method of using the balance with great delicacy, and on its em- ployment to determine the mean den- sity of the (Poynting), 2. , on the remote history of the (Darwin), 184. Elder (H. M.) and Rodwell (G. F.) on the effect of heat on the di-iodide of mercury, Helo, 284. Electric currents, on certain means of measuring and regulating (Siemens), 292. discharge, note of an experiment on the spectrum of the (Grove), 181. Electrical constants, measurements of : No. II. On the specific inductive capa- cities of certain dielectrics: Part I (Gordon), 155. insulation in high vacua (Crookes), 347. Electricity, influence of, on water-drops (Rayleigh), 406. and light, on an extension of the phenomena discovered by Dr. Kerr (Gordon), 346. Electro-magnetic theory of the reflection and refraction of light (Fitzgerald), 236. Elements, discussion of the working hy- pothesis that the so-called, are com- pound bodies (Lockyer), 157. Eocene Flora of Great Britain (Ettings- hausen), 221. INDEX. Equations, machine for the solution of simultaneous linear (Thomson), 111. Ettingshausen (Baron), report on phyto- paleontological investigations gene- rally, and on those relating to the Eocene Flora of Great Britain in par- ticular, 221. Explosions (colliery), influence of coal- dust in: No. II, (Galloway), 410. Fellows, deceased, 42 ; number of, 69. Financial statement, 70. Fitzgerald (G. F.) on the electro-mag- netic theory of the reflection and re- fraction of light, 236. Flora (Eocene) of Great Britain (Ettings- hausen), 221. Flow of water in uniform régime in rivers and other open channels (‘Thom- son), 114. Fog, on dry (Frankland), 238. Foreign members elected, 462. Fossil plants of the coal-measures, orga- nised (Williamson), 445. Frankland (E.) on dry fog, 238. Fries (HE. M.), obituary notice, vii. Fur of tongue, its nature, 484. elected, 43 ; Galloway (W.), influence of coal-dust in colliery explosions: No. II, 410. Gas, on an extension of the dynamical theory of (Reynolds), 304. Gaseous state, on certain dimensional properties of matter inthe: Parts I, IL (Reynolds), 304. Gases, absorption of, by charcoal: Part IT (Smith), 322. -——, experimental researches on thermal transpiration of, through porous plates (Reynolds), 304. Geddes (P.), physiology and histology of Convoluta Schultzvi, 449. Geological time, limestone as an index of (Reade), 281. Geology (Physical), notes on: No. V, note in correction of an error in (Haughton), 154. Glass fibre, on the torsional strain in a, after release from twisting stress (Hopkinson), 148. Gordon (J. E. H.), measurements of electrical constants: No. II. On the specific inductive capacities of certain dielectrics: Part I, 155. , on an extension of the phenomena discovered by Dr. Kerr, and described by him under the title of “A New Relation between Electricity and Light,” 346. Government fund of 4,000/., account of the appropriations from, in 1878. 77. INDEX. Government grant of 1,000/., account of the appropriation of,‘in 1878, 75. Grove (Sir W. R.), note of an experi- ment on the spectrum of the electric discharge, 181. Hannay (J. B.) on the microrheometer, Hartley (W. N.) and Huntington (A. K.), researches on the absorption of the ultra-violet rays of the spectrum by organic substances, 233. Haughton (Rev. 8.), note in correction of an error in his paper, ‘‘ Notes on Physical Geology, No. V,” 154. Heat, effect of, on the di-iodide of mercury, Hel, (Rodwell and Elder), 284. Hicks (J. B.), supplementary forces con- cerned in abdominal circulation in man, 489. , auxiliary forces concerned in the circulation of the pregnant uterus in woman, 494. Hogarth (J.) and Mills (EH. J.), re- searches on chemical equivalence: Part If. MUHydric chloride and sul- phate, 270. , researches on lactin, 273. Hooker (Sir J. D.), President’s address, 43 ; resignation, 63. Hopkinson (J.) on the torsional strain which remains in a glass fibre after release from twisting stress, 148. Huntington (A. K.) and Hartley (W.N.), researches on the absorption of the ultra-violet rays of the spectrum by organic substances, 233. Huxley (T. H.), characters of the pelvisin mammalia and conclusions respecting the origin of mammals, 395. _Hyaline cartilage, on, and deceptive ap- pearances produced by reagents, as observed in the examination of a carti- laginous tumour of the lower jaw (Thin), 257. Hydric chloride and sulphate, researches on chemical equivalence: Part II (Mills and Hogarth), 270. Induction-currents, on the effects of strong, upon the structure of the spinal cord (Ord), 265. Infusions (organic), note on the influ- ence exercised by light on (Tyndall), 212. Jackson (Dr. J. H.), admitted, 1. Japan, magic mirror of: Part I (Ayr- ton and Perry), 127. Kerr (Dr.) on an extension of the pheno- mena discovered by (Gordon), 346. VOL. XXVIII. D309 Kew committee, report of the, 80. Kew observatory, magnetic observations made at, 1877-78, 89. , note on the inequalities of the diurnal range of the declination magnet as recorded at the (Stewart), 241. Kew and Trevandrum observatories, a comparison of the variations of the diurnal range of magnetic declination as recorded at (Stewart and Morisabro Hiraoka), 288. Lacertilia, on the structure and develop- ment of the skull in the: Part I. On the skull of common lizards (Parker), 214. Lactin, researches on (Mills and Ho- garth), 273. Light, electromagnetic theory of the reflection and refraction of (Fitz- gerald), 236. , influence exercised by, on organic infusions (Tyndall), 212. influence of, upon protoplasm (Downes and Blunt), 199. Limestone as an index of geological time (Reade), 281. Lindsay (Lord), admitted, 102. Linear equations, machine for the solu- tion of simultaneous (Thomson), 111. Lines of metallic vapours, on the re- versal of the (Liveing and Dewar) : No. IV, 352; No. V, 367. of molecular pressure, on the illumi- nation of (Crookes), 103. Liveing (G. D.) on the wiknown chro- mospheric substance of Young, 475. and Dewar (J.) on the reversal of the lines of metallic vapours : No. IV, 352; No. V, 367; No. VI, 471. , on a direct vision spectro- scope, 482. Lizards, on the skull of the common (Parker), 214. Jiockyer (J. N.), researches in spectrum analysis in connexion with the spec- trum of the sun, 157. , preliminary note on the sub- stances which produce the chromo- spheric lines, 283. , some spectral phenomena observed in the are produced by a Siemens’ machine, 425. , on some phenomena attending the reversal of lines, 425. , discussion of “ Young’s List of Chromospheric Lines :” No. I, 432. Locomotor system of Medusz, conclud- ing observations on the (Romanes), 266. 2 1 = o34 McLeod (H.) and Clarke (G. 8.) on the determination of the rate of vibration of tuning forks, 291. Machine for the solution of simultaneous linear equations (Thomson), 111. Magic mirror of Japan: Part I (Ayrton and Perry), 127. Magnet (declination), on the inequalities of the diurnal range, as recorded at the Kew observatory (Stewart), 241. Magnetic declination, comparison of the variations of the diurnal range, as re- corded at the observatories of Kew and Trevandrum (Stewart and Moris- abro Hiraoka), 288. observations made at Kew observa- tory, 89. Mammalia, characters of the (Huxley), 395. Mammals, on the origin of (Huxley), 395. Marcet (W.), inquiry into the functions of respiration at various altitudes in Teneriffe, 498. Marshall (A. M.), note on the develop- ment of the olfactory nerve and olfac- tory organ of vetebrates, 324. Matter, on certain dimensional proper- ties of, in the gaseous state: Parts I, II (Reynolds), 304. Matthey (G.), on the preparation of the group of metals known as the platinum series, 464. Medals, presentation of the, 63. Meduse, concluding observations on the locomotor system of (Romanes), 266. Mercury, di-iodide of, Hgl., on the effect of heat on the (Rodwell and Eider), 284. Metallic reflexion, on (Conroy), 242. vapours, reversal of their lines (Liveing and Dewar): No. IV, 352; No. V, 367; No. VI, 471. Microrheometer, on the 2 Dal). Mills (H. J.) and Hogarth (J.), researches on chemical equivalence: Part II. Hydric chloride and sulphate, 270. , researches on lactin, 273. Mills (HE. J.) and Walton (T. U.), re- searches on chemical equivalence: Part I. Sodic and potassic sulphates, 268. pelvis some experiments (Hannay), Mirror (magic) of Japan: Part I (Ayrton and Perry), 127. Molecular physics in high vacua (Crookes), 477. pressure, on the illumination of lines of, and the trajectory of mole- cules (Crookes), 103. Morisabro Hiraoka and Stewart (B.), a comparison of the variations of the INDEX. diurnal range of magnetic declination as recorded at the observatories of Kew and Trevandrum, 288. Obituary notices :— Brongniart (A. T.), iv. Clarke (Rev. W. B.), i. Fries (H. M.), vu. Olfactory nerve and olfactory organ of vertebrates, note on the development of the (Marshall), 324. Ord (W.) on the effect of strong in- duction currents upon the structure of the spinal cord, 265. Organic infusions, note on the influence exercised by light on (Tyndall), 212. Parker (W. K.) on the structure and development of the skull in the Lacer- tilia: Part I. On the skull of the common lizards, 214. , on the development of the skull and its nerves in the green turtle (Chelone midas), with remarks on the segmentation seen in the skull of va- rious types, 329. Pavy (F. W.), volumetric estimation of sugar by an ammoniated cupric test, giving reduction without precipitation, 260. , physiology of sugar in relation to the blood, 520. Pelvis in mammalia, characters of (Hux- ley), 395. Perry (J.) and Ayrton (W. E.), magic mirror of Japan: Part I, 127. , contact theory of voltaic ac- tion: No. IIT, 421. Physical geology, notes on: No. V, note in correction of an error in (Haugh- ton), 154. Phyto - paleontological investigations, report on, generally, and on those re- lating to the Eocene Flora of Great Britain in particular (Httingshausen), 221. Platinum series, preparation of the group of metals (Matthey), 464. Poynting (J. H.) on a method of using the balance with great delicacy, and on its employment to determine the mean density of the earth, 2. Preece (W. H.) and Stroh (A.), studies in acoustics: I. On the synthetic examination of vowel sounds, 358. Presents, lists of, 98, 228, 297, 372, 457, 528. President’s address, 43; resignation of Sir J. D. Hooker, 63; election of W. Spottiswoode, 69. Protoplasm, on the influence of lilt upon (Downes and Blunt), 199. . INDEX. Quatrefages (J. L. A. de), elected, 461. Quincke (G. H.), elected, 461. Radiation, repulsion resulting from : Part VI (Crookes), 35. Rayleigh (Lord), influence of electricity on colliding water-drops, 406- Reade (T. M.), limestone as an index of geological time, 281. Reflexion (metallic), some experiments on (Conroy), 242. Repulsion resulting from Part VI (Crookes), 35. Respiration at various altitudes in Tene- riffe (Marcet), 498. Reversal of lines, phenomena attending the (Lockyer), 428. Reynolds (O.) on certain dimensional properties of matter in the gaseous state: Parts I, I, 304. Rivers, on the flow of water in uniform régime in, and other open channels (Thomson), 114. Rodwell (G. F.) and Elder (H. M.) on the effect of heat on the di-iodide of mercury Hgl,, 284. Romanes (G. J.), concluding observa- tions on the locomotor system of Me- dusze, 266. Royal medal awarded to J. Allan Broun, 65; to Dr. A. Giinther, 66. Rumford medal awarded to A. Cornu, 67. Schiifer (EH. A.), admitted, 1. ‘Schwann (T.), elected, 462. Siemens (C. W.), on certain means of measuring and regulating electric cur- rents, 292. Skin, on some points connected with the anatomy of the (Thin), 251. Skull and its nerves in the green turtle, on the development of the (Parker), 329. Smith (R. A.), absorption of gases by charcoal: Part Il. On a new series of equivalents or molecules, 322. Sodice and potassic sulphates, researches on chemical equivalence: Part IL: (Mills and Walton), 268. Spectral phenomena in the are produced by a Siemens’ machine (Lockyer), 428. Spectroscope, direct vision (Liveing and Dewar), 482. Spectrum analysis, researches in, in con- nexion with the spectrum of the sun (Lockyer), 157. ef the electric discharge, note on an experiment on the (Grove), 181. , researches on the absorption of the ultra-violet rays of the, by organic substances (Hartley and Huntington), 233. radiation : D390 Spheroid (viscous), on the precession of a, and on the remote history of the earth (Darwin), 184. , problems connected with the tides of a (Darwin), 194. Spinal cord, on the effect of strong in- duction currents upon the structure of the (Ord), 265. Spottiswoode (W.), elected President, 69. Sprengel (Dr. P. H.), admitted, 113. Stas (J. 8.), elected, 462. Stewart (B.), note on the inequalities of the diurnal range of the declination magnet as recorded at the Kew ob- servatory, 241. and Morisabro Hiraoka, a com- parison of the variations of the diurnal range of magnetic declination as re- corded at the observatories of Kew and Trevandrum, 288. Strain (torsional) which remains in a glass fibre after release from twisting stress (Hopkinson), 148. Stroh (A.) and Preece (W. H.), studies in acoustics: I. On the synthetic ex- amination of yowel sounds, 358. Sugar (physiology of) in relation to blood (Pavy), 520. , volumetric estimation of, by an amimoniated cupric test, giving reduc- tion without precipitation (Pavy), 260. Sun, researches in spectrum analysis in connexion with the spectrum of the (Lockyer), 157. Teneriffe, respiration at various altitudes (Marcet), 498. Thin (G.) on some points connected with the anatomy of the skin, 251. , on hyaline cartilage and deceptive appearances produced by reagents, as observed in the examination of a car- tilaginous tumour of the lower jaw, 257. Thomson (J.) on the flow of water in uniform régime in rivers and other open channels, 114. Thomson (Sir W.), on a machine for the solution of simultaneous linear equa- tions, 111. Thuillier (Major-General H. E. &.), admitted, 358. Tides of a viscous spheroid, problems connected with the (Darwin), 194. Tongue, nature of the fur, 484. Torsional strain which remains in a glass fibre after release from twisting stress (Hopkinson), 148. Trajectory of molecules (Crookes), 103. Trust funds, 72-74. Tumour (cartilaginous) of the lower jaw, examination of (Thin), 257. 536 Tuning forks, on the determination of the rate of vibration of (McLeod and Clarke), 291. Turtle (green), on the development of the skull and its nerves in the (Parker), 329. Tyndall (J.), note on the influence ex- ercised by light on organic infusions, 212. Ultra-violet rays of the spectrum, re- searches on the absorption of the, by organic substances (Hartley and Hun- tington), 233. Uterus (pregnant), forces concerned in the circulation (Hicks), 494. Vacua (high), electrical insulation in (Crookes), 347. , molecular physics in (Crookes) 477. Vertebrates, note on the development: of the olfactory nerve and olfactory organ of (Marshall), 324. Vibration of tuning forks, on the deter- mination of the rate of (McLeod and Clarke), 291. Vice-Presidents appointed, 102. Vines (S. H.) on the chemical compo- sition of aleurone grains, 218. Viscous spheroid, on the precession of a, and on the remote history of the earth (Darwin), 184. INDEX. Viscous spheroid, problems connected with the tides of a (Darwin), 194. Voltaic action, contact theory of: No. IV (Ayrton and Perry), 421. Volumetric estimation of sugar by an ammoniated cupric test, giving re- duction without precipitation (Pavy), 260. Vowel sounds, on the synthetic exami- nation of (Preece and Stroh), 358. Walton (T. U.) and Mills (H. J.), re- searches on chemical equivalence : Part I, sodic and potassic sulphates, 268. Ward (J.), physiology of the nervous system of the crayfish, 379. Water, flow of, in uniform régime in rivers and other open channels (Thom- son), 114. , thermal conductivity of (Bottom- ley), 462. — drops, influence of electricify on colliding (Rayleigh), 406. 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When Mr. Clarke set out on his explorations there was no other means of travel but horses, with pack-horses for provisions, tents, and instru- ments. In some parts of the country there were no roads or land- marks of any kind, and the maps of the district were nearly useless, as being only skeleton outlines of boundaries. He had to carry on his work single-handed, and gradually to form his own library. Mr. Clarke’s travels extended to Tasmania, Victoria, and Queens- land, and he has written various exhaustive reports relating to these countries. His writings have guided persons to various profitable gold mines, and the successful tin industries of Australia and Tasmania have been commenced from indications furnished by him. In 1863 the Legislature of New South Wales voted Mr. Clarke £3,000, at a time when his various ailments seemed coming to a head, to enable him to secure a little comfort in his old age; but since that time his “pen of a ready writer” has never been weary; and we are almost tempted to say that his latter years have surpassed the former, for his facts seemed to have accumulated more quickly, and his experience being, of course, more matured, enabled him to seize upon the more salient points of the geology of the country. The fruit of his labours during this part of his life consists of a geological map of the whole colony, which has been compileu from his note-books and memoranda. Up to 1870 he never ceased from the work of his sacred calling, even when on his explorations; but on Ist October of that year, his in- creasing infirmities obliged him to retire from his parochial labours. He was thus in a position to avail himself of the improved locomotion afforded by the railways to revisit his old haunts, and to visit other places of interest, so as to fill up gaps in his former works. He was an indefatigable observer of meteorological facts and of general natural history. Mr. Clarke was elected F.G.S. in 1826. He was a member of the Geological Society of France, and held a diploma from the Imperial and Royal Geological Institution of Austria, F.R.G.S., and one of the early Fellows of the Zoological Society. Mr. Clarke contributed largely to the periodical literature of England prior to 1839, and his poetical effusions are by no means un- deserving of praise. In 1876 he was elected F.R.S., and in 1877 he was awarded the Murchison Medal of the Geological Society of London. The terms in which the award was made express the results of his geological labours in Australia. The excessive heat of March, 1878, combined with the labour of preparing a new edition of ‘Sedimentary Formations of New South Wales,” proved too much for Mr. Clarke’s strength. He was seized with paralysis on the 16th of that month; and though he rallied, so lv that he was able to move about without help, and to arrange and label fossils recetved from Professor de Koninck on the 15th June, he was seized with a violent pain in the heart on the morning of the 16th, and before medical aid could be procured he was called to his long-earned rest. It is proposed by the Government to purchase his collection of minerals, fossils, hbrary, and geological maps, and with them to form a nucleus, under the name of the ‘Clarke Collection,” of a grand Mining Museum. a aia sol | i? Pen oir a Pglbecars: CONTENTS (continued) “% ». : | March 20, 1879. “4 4 a ‘PAGE I. Note on some Spectral Phenomena observed in the Arc produced by a: Siemens’ Machine. By J. Nonman Lockyer, F.R.S. . . 425 II. Note on some Phenomena attending ie Reversal of Lines. By rs 3 Norman Locxyer, F.RS. . : - - : - . 428 — III. Discussion of Young’s List of Chromospheric Lines. (Note 1.) - By | 5 J. Norman Lockyer, F.R.S. (Plate9.) .-. -. 9. 3 eee > March 27, 1879. - 4 4 I. Onthe Organization of the Fossil Plants of the Coal Measures. Part XK. i By W. C. Wittiamson, F.R.S., Professor of Natural History in One a College, Manchester » 445 IT. Observations on the Physiology aa d Histology ae Cone se Schult. a By P. Geddes : ee List of Presents ; : : Sere oe : ep i 457° Obituary Notice :— ne Rey. WItLiaM BRANWHITE CLARKE. . : age ee : * Ty PHILOSOPHICAL TRANSACTIONS, Se : 4 Part II (1878), price £3, ready for delivery. ae 29 ae Separate copies of Papers in the Philosophical Transactions, commencing rae 1875, 4 may be had of Triibner and Co., oO Ludgate Hill. } . ro CATALOGUE OF SCIENTIFIC PAPERS COMPILED BY THE ROYAL — SOCIETY. Published by Her Majesty’s Sidtioney Office. 5 8 nee Sg On Sale by Murray, Albemarle Street, and Triibner and Co., Indgate H Hill. Per yol.: 20s., cloth ; 28s., half-morocco. Vol. 8, a continuation of the work (1864-1873) is now in the press. HARRISON AND SONS, 45 & 46, ST. MARTIN’S LANE, Woe AND ALL BOOKSELLERS. at - PROCEEDINGS OF aot ROYAL SOCIETY. VOL. XXVIII. | on Ogee. - \ Ep 26. Se gq 2 CONTENTS. ” 1879 April 3, 1879. PAGE I. On the Thermal Conductivity of Water. By J. T. Borromuey, Lecturer in Natural Philosophy and Demonstrator in Experimental Physics in the University of Glasgow . ; : : . ; j ; : . 462 Il. The Preparation in a State of Purity of the Group of Metals known as _ the Platinum Series, and Notes upon the Manufacture of Iridio-Platinum. By GzoreGe Marruzy . . : ; : ; : 3 . 463 _ IIL. On the Reversal of the Lines of Metallic Vapours. No. VI. By G. D. Liveine, M.A., Professor of Chemistry, and J. Dewar, M.A., F.R.S., ay Jacksonian Professor, University of Cambridge. : 5 : . 471 IV. Note of the unknown Chromospherie Substance of Young. By G. D. By Livrine, M.A., Professor of Chemistry, and J. Drwar, M.A., F.RBS., Jacksonian Professor, University of Cambridge . F : : . 475 _ Y. Contributions to Molecular See in uy Vacua. By WILLIAM Crooks, F.RS. .. . -. Sg ee ae VI. Note on a Direct Vision Spectroscope after Thollon’s Plan, adapted to Laboratory use, and capable of giving exact Measurements. By. G. D. -Lrverne, M.A., Professor of Chemistry, and J. Dewar, M.A., F.RB.S., April 24, 1879. I. On the nature of the Fur on the Tongue. By Henry TRENTHAM Borin, F.R.C.S. (Plates 10-13). : \ : : : : . 484 II. Note on the Supplementary Forces concerned in the Abdominal Circula- tion in Man. By J. Braxton Hicks, M.D., F.RS. : 5 : . 489 III. Note on the Auxiliary Forces concerned in the Circulation of the oe nant Uterus and its Contentsin Woman. By J. Braxton Hicks, M.D., E.R.S., F.L.S., &e. : : : - ; : . . 494 For continuation of Contents see 4th page of the Wrapper. . Price Four Shillings and Stapence. _ dacksorian Professor, University of Cambridge. : : . 482. - fe CONTENTS (conan). IV. A Summary of an Inguiry into the Function of Respiration at V Altitudes on the Island and Peak of Teneriffe. eles M M.D., F.R.S. "By F. W. Pavy, MD., F.B.S. Obituary Notices :— . ADOLPHE THEODORE BRONGNIART Exias Maenus FRIES. ‘ Contents and Index . s > F é ; k : E ; : ; 531 GOVERNMENT GRANT OF £1000. © A Murrine of the Government-Grant Committee will be held in F Rene It is requested that applications to be considered at that Meeting be forwarded the Secretaries of the Royal Society, Burlington House, before = 31st ee mi 1879. aa GOVERNMENT FUND OF £4000 FOR THE PROMOTION OF SCIENTIFIC RESEARCH. 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