ee ey os ere are eh td ghalh ae Godhead tat < Papa - ns te o Be re et Ue eaten te es) 0): Bae Ge meee ae te Ente A Phew ° re einie tel Mnb-Raiay ght Ge toy ete Oe ¥ + Pee ee Pee nS ee ee iat ¥ Rete Tiedat a tig Gor too e- P OK : ~ o atte three wee mE! ow ; raters Te teti< me were ors by 5 * > i ee ee ee ey ee ae mtn Pan = ptt . te eee A a Tr on ee - ee ee ee ee . & 5 VSL Ota d x . Ooi din a bY Reming tr ithe =e oath nthe Win He ie Oe Fi Devtagid- fg a tee Ree oe qe * o * . - we ® - Fm Ree Wee te ie Og ele ae 9 CNet wth |, pm Bathe hyde ty ww Aue or pO ot~a Ra Bt - 4 Ae Be ee fe a ht hen A> ‘ - - 7 ee ee ee ee ee ee re gn he a er ee . tween Oa cee a Ce ee ee ee > Nat = 92 4 he “ v - ‘ det Brack em ee ee ee . Pl Ae Dialer hin Be he IS 2A Weipa Fit ot at? be: <7 awe ED la te ert cf - Oo adhe Bs bv iu ose Geka ew te eRe y Fo GoW Por tthe in We Be 8.0 RH RE RG tebe Gee ky SoBe . ee a ee ar 4 setae ou8 + ae ret aye ee ee acGuer@ng. et ee es +e we Ee > 4 Ce ee prelboins "s PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON. From April 20, 1882, to January 25, 1883. » VOL. XXXIV. ge NY - LONDON: HARRISON AND SONS, ST. MARTIN’S LANE, Printers in Ordinary to Her Wajesty. MDCCCLXXXIII. LONDON: HARRISON AND SONS, PRINTERS IN ORDINARY TO HER MAJESTY, ST. MARTIN’S LANE. ye cals, ALC cs CONTENTS, VOU. SOCxry: 8 No. 220.—April 20, 1882. Page On the Formation of Ripplemark. By Arthur R. Hunt, M.A., F.G.S..... 1 Note on General Duane’s Soundless Zones. By Dr. John Tyndall, F.R.S. 18 April 27, 1882. On the Attitudes of Animals in Motion. By Eadweard Muybridge, of Mee MGW UU IcPOO ATE OUTIV AA O22. 2 0h bd cc rans eceidae dosacnedeiocsve toocceueh sen sscaugnucseovnse Uosasednstestee 20 Preliminary Account of the Structure of the Cells of the Liver, and the Changes which take place in them under Various Conditions. By J. N. Langley, M.A., Fellow of Trinity College, Cambridge ............cesecees 20 May 4, 1882. Mins OREO TIVERUGL ALCS COL TVCCEION. wchsceceesececsssosccessacsvecsccsvasececesecesesce: cccncoserseevesceces aA On the Specific Resistance of Mercury. By Lord Rayleigh, F.R.S., Pro- fessor of Experimental Physics in the University of Cambridge, and LTE. Ls (SUC SAU GIS at ke hese 6A Sa ee eo cn eo GR a 2] May 11, 1882. pmmieversiom Genérale. Par TS. Vamecek.......:.-.sspsssosossasecssavcnerosacseonens 29 On the Organization of the Fossil Plants of the Coal-measures. Part XII. - eabeceneccon VC. Williamson, WIR.S. ssciccctcheccssenecters snctistesecctecncnctdetovens 31 May 25, 1882. On certain Geometrical Theorems. No.2. By W. H. L. Russell, F.R.S. 35 Note on Mr. Russell’s paper “ On certain Geometrical Theorems. No. 2.” Pe elbiaTM S POLLISWOOMS (Pres. FRG. 1 iol veccacsccscesosecassencsedecsasentcotcggecovesees- ai LV On Effects of Retentiveness in the Magnetisation of Iron and Steel. (Preliminary Notice.) By J. A. Ewing, B.Sc., F.R.S.E., Professor of Mechanical Engineering in the T~iversity Of TOKI0 «0... cesssescesecseeensee On Actinometrical Observations ade in India at Mussooree in Autumn of 1880, and Summer and Autumn of 1881. By J. B. N. Hennessey, F.R.S., Deputy Superintendent Great Trigonometrical Survey of India GET aibe Ue, ices catvcucenccastcaal aredeosa, ante eetanegncet sastes Caste: suaaise sevens css eee On the Causes of the Light Border frequently noticed in Photographs just outside the Outline of a Dark Body seen against the Sky; with some Introductory Remarks on Phosphorescence. By Professor G. G. Stokes, See. HRS. veshesesescteaaeceayecegemge so sdesBereeoagec dacs ceescses shel see ee June 8, 1882. Amnual Meeting for the Election of Wellows) .2.........2...ss0s0cs eee eee Masb Of Presents. ces ceisscesssce.skscncs de, hd Sea Sse Eeeeed bee widow eecee ete eee No. 221.—June 15, 1882. Researches on Spectrum Photography in relation to New Methods of Quantitative Chemical Analysis. By W. N. Hartley, F.R.S.E., &., Professor of Chemistry, Royal College of Science, Dublin ........... cece On the Reversal of the Metallic Lines as seen in Over-exposed Photo- graphs of Spectra. By W. N. Hartley, F.R.S.E., &c., Professor of Chemustry,, Royal College, of, Science, Dublin. ..........2...<.cccsessh eee Experiments on the Value of the Ohm. Part I. By R. T. Glazebrook, M.A., F.R.S., Fellow and Assistant Lecturer of Trinity College, De- monstrator at the Cavendish Laboratory, Cambridge, and J. M. Dodds, B.A., Fellow of St. Peter’s College. Part I].. By R. T. Glazebrook, and EB Sargant, M.A., Trimity College: oun -.......-.c..cocceees On a Deep Sea Electrical Thermometer. By C. William Siemens, MD SCOEL, HRS. sicsecessccescatisestostonsectt encsnnpeassocsiessedee-0u0 lees eee rrr On the Coxal Glands of Scorpio hitherto undescribed and corresponding to the Brick-red Glands of Limulus. By E. Ray Lankester, M.A., F.R.S., Jodrell Professor of Zoology in University College, London .... Note on the Differences in the Position of the Ganglia of the Ventral Nerve-cord in three Species of Scorpio. By E. Ray Lankester, M.A., F.R.S., Jodrell Professor of Zoology in University College, London .... On the Specific Heat and Heat of Transformation of the Iodide of Silver, Agl, and of the Alloys Cu,1,.AgI, Cugl.2AgI, Cu,L,.3Agl, Cu,I,.4AgI, Cu.1,.12AgI, PbI,.AgI. By Professor M. Bellati and Dr. R. Romanese, Professors in the University of Padua «............::csccs-ccecseessececssesesees ee (I.) On a Tangential Property of Regular Hypocycloids and Epicycloids. (II.) On Theorems relating to the Régular Polyhedra which are analogous to those of Dr. Matthew Stewart on the Regular Polygons. Page 39 45 63 69 69 81 84 86 89 95 101 104 By Henry M. Jetlery, BRS. ...c:c.cscescessececacoseaseescntesessossse~-c pepeereaeD eine Du tivtaeey’ & +f Bee Gey eT py 1) a) Aa Fa aahiqets ive wy) Fed ; Egat ws alt "Bsa a aed SHE, in aes Bat liss Shape Seer Het AERA EM adn t™. et {a 4 Biiiiaket oo seig pulhot Gibwiblah get abi Aled eae al oe ok ~ 1 oo A ; 3 Pied zh oliiemy fag GPa ar +? Paar i A? 22 wt) 4ORIs sale Se Reale ee He Prete eet fon, fee ahaa a1 sonehids: sve Bee ike oS re ohh poped try teh 4 + Bais Hie ete eS siete i + yt " = j oan Waly. a | ac a “ie nee - ricies, sg — oy rtd oe Ht Aw ae hasiey se Svt sas shy Fiery up atthe i aatem a Si Bit. fl oj TS ORY) oBipe See Feb 232 Regn BS dante! Seer aa ae Se rea ang a aye ee iti itty saypig' a ib eg Darel ee alee wed fhe fika victor th & WAM At Reread (tae Sk peel gee Ea ' ? sas at ‘outa Ie ‘iy Theta woe + : bs sta 7b ee ae ; he eae! FS Ab res tbat be: unk tie a : Gh @El aan ih tapi a ’ 23 tol ce + hae bes dirs bie ¥A Alivel t% ier a _: « -" = z ere set, i NED SRT Ad tsk apd tae a i. j +4 ral wea TS Ht APR: ie canna a 4 whiney yd oiekt a bet pial ‘ea vee a ¥ Th 7 : sin 1 7 ae a icy or: PROCHKEDINGS OF ek ey SOG LY INN ARAAAARAWANAARANRAIA™ April 20, 1882. THE PRESIDENT in the Chair. The Presents received were laid on the table, and thanks ordered for them. The President condoled with the Meeting on the great loss which Science and the Society had sustained through the decease of their distinguished Fellow, Charles Darwin; and mentioned that a propcsal for interment in Westminster Abbey had been made to the family of the deceased and to the Dean, which he trusted would be brought to pass. The following Papers were read :— I. “On the Formation of Ripplemark.” By ARTHUR ROOPE Hunt, M.A., F.G.S. Communicated by Lord RAYLEIGH, F.R.S. Received March 28, 1882. Read April 20. Fossil ripplemarks are often appealed to by geologists as evidence that the winds and waves that formed them cannot have differed much in intensity from those that produce similar corrugations on the sands of our modern beaches; but, although considerable value is attached to the evidence afforded by these relics of ancient seas, authorities differ much as to their origin. According to Sir Charles Lyell ripplemark originates in the “ drifting of materials along the bottom of the water,” and “is usually an in- dication of a sea beach, or of water from 6 to 10 feet in depth, though this rule he proceeds to say is not without exception, as recent ripple- marks have been observed at the depth of 60 or 70 feet. The crossing of two sets of ripples the distinguished author ascribes to the new direction in which the waves are thrown on the shore consequent on a VOL. XXXIV. B 2 Mir AS elit? [ Apr. 20, change of wind (‘‘ Elements of Geology,” 6th edition, p. 19). Mr. J. Beete Jukes, in the first edition of his ‘‘ Manual of Geology,” states, that current mark or ripple ‘is produced on the sea beach, not in consequence of the ripple of the wave impressing its own form on the sand below, which would be an impossibility, but because the moving current of water as the tide advances or recedes produces on the surface of the sand below the same form as the moving current of air produces on the surface of the water above. A rippled surface, there- fore, to a rock is no proof of its having been necessarily formed in shallow water, though rippled surfaces are perhaps more frequently formed there, but simply a proof of a current in the water sufficient to move the sand at its bottom gently along, at whatever depth that bottom may be from the surface of the water.” Speaking of fossil ripplemarks the same author states that the distance from crest to crest of the ridges varies from half an inch to eight or ten inches, with a proportionate variation in depth between them (Jukes’ “‘ Man. Geol.” p. 172). The article on ripplemark is recast in the third edition, edited by Dr. Geikie and published in 1872, but the views expressed therein are the same. Monsieur Delesse goes far beyond the authorities referred to above, as on the authority of Commandant Cialdi, he states that the move- ment of waves can displace fine sand at a depth of 200 metres in the ocean, and (without giving his authority for the statement) that the undulation of the sea is evidenced by ripplemarks on muddy bottoms down to a depth of 188 metres (‘‘ Lithologie du fonds des Mers,”’ 1871, pp. 110, 111). More recently, Mr. G. H. Darwin has stated that one of the conditions of the formation of many ripples is a great ebb and flow of the tides (‘‘ Nature,” vol. xxv, p. 214). It will be seen from the authorities cited above, that the pheno- menon known as ripplemark is variously ascribed to the action of currents, and to the undulation of waves, and that whereas by some it is considered the result of tidal action in shallow water, by others it. is attributed to the action of waves down to the great depth of upwards of 100 fathoms. I shall endeavour in the present paper to prove that ripplemarks formed under water are, as a rule, completely independent of the rise and fall of tides, of tidal currents, and of sea beaches; and that they have little in common with the current mark, that owes its origin: either to a continuous current of air or of water. , For some years past I have neglected no opportunity of making observations on the action of storm waves on the bottom of Torbay, and of collecting evidence as to the action of waves and currents on the bottom of the English Channel. To Lord Rayleigh J must express my indebtedness for having examined my evidence of submarine wave action from a mathematical standpoint, and for having called my 1882.] On the Formation of Ripplemark. 3 attention to the fact that waves, if they affect the bottom at all, do so by setting up alternate currents:* and that, though at great depths the action is very small, theoretically it has no limit, Having observed that ripplemarks are commonly better preserved in pools between tidemarks than on those parts of the tidal strand left dry at low tide, and that the bottoms of these pools must be in some measure protected from the continuous currents that are com- monly supposed to produce the ripplemarks, it seemed to me probable that they were produced by the alternate action of waves described to me by Lord Rayleigh. One fine and almost calm day in the summer of 1881, being at Broadsands in Torbay, and seeing that the strand was covered with ripplemarks, I proceeded to watch carefully the action of the water with a view of ascertaining, if possible, the process of their formation. Floating in my boat a few yards from the shore in about 18 inches of water, | narrowly scanned the effect of the very gentle swell that was breaking on the beach. I observed that a smail shell lying in one of the furrows instead of being steadily washed shorewards by the in- coming waves, was washed backwards and forwards from one furrow to another; sometimes it would stop on the intervening ridge, and so for the moment help to build it up; at others it would fall over into the furrow towards which for the moment it was being propelled, but in no case did it show any tendency to travel continuously in any particular direction along the bottom. On a subsequent occasion, having to land on the beach at Paignton, and seeing the ripplemarks well developed, I again carefully watched them seawards. At a point where the bottom was too indistinct for me to observe its condition, I could distinguish fragments of sea- weed gently moving backwards and forwards in the direction of the beach, and at right angles to the ripplemark where last visible. This observation was unexpected, as it proved a gentle swinging motion of the water in the vicinity of the shore, when the surface motion was so slight as not to interfere with my landing on a flat open beach from a very small boat. On the 19th October, 1881, there was a strong south-easterly gale in Torbay, and the waves rolled on to the Meadfoot Sands at the rate of 74 per minute. The distance between the southern point of an outlying islet known as the Shag Rock .and the rocks at the western end of Meadfoot Sands (two points in line with the direction of pro- pagation of the waves), 275 yards by the chart, was covered by exactly three waves, so that each one must have measured 275 feet from crest to crest. In midbay this length was probably exceeded. As from the manifest turbidity of the water, the bottom was unques- 7) wins Weyeassocs, i yol, xp. LO (878): 4 Mr. AL ent. [ Apr. 20, tionably much disturbed, I looked forward with interest to ascer- taining by the dredge what effect these waves of known dimensions had had on the bottom. On the 31st of October, nearly a fortnight after the gale, I had an opportunity of going out for this purpose, and in places, in 6 fathoms (at low water spring tides), where the bottom is usually a soft muddy sand that clogs the dredge in a few minutes, the ground proved to be quite hard. One haul of the dredge brought up a Buccinum shell, with the mollusc inside it dead, and two dead ascidians ; and another in midbay, though with 30 fathoms of rope, produced not a shell or a particle of the usual muddy sand, but only a few red seaweeds that must have come from a distance. Never before in my experience had I found the ground so hard in midbay, nor dredged dead molluscs and ascidians. On the llth November the ground was still very hard, both the dredge and a fishing-lead tied to a line bumping along as though over ridges. On the 8th December, more than six weeks after the gale, I again tried the same spot in midbay that proved so hard on the 3lst October : it had now returned to its normal state, and the dredge brought up the usual muddy sand. These dredgings tended to show that the bottom had been violently agitated by the storm, and that as the seas subsided it had become strongly ripple marked. Why it should change from soft to hard and back again to soft is not very clear, but there is no doubt as to the fact. It may be objected that as fossil ripplemarks have been said to be limited to 10 inches, a dredge would scarcely detect modern ripples if not larger than that; but there is no doubt that modern ripplemarks occasionally far exceed these dimensions. I have myself seen them formed in Brighouse Bay, on the coast of Kirkeudbright, fully 24 feet from crest to crest, and deep in proportion.* * Since writing the above my attention has been directed to the following im- portant, though quite incidental, descriptions of wave-marks on the Goodwin Sands by the Rev. John Gilmore, in his book intituled “Storm Warriors, or Lifeboat Work on the Goodwin Sands.” They are as follows :— ‘““On the Goodwins where the force of the sea is in every way multiplied and the waves break and the tide rushes with tenfold power, the little sand-ripples of the smoother shore become ridges of two or three feet high. It is on these ridges that the lifeboat so continually grounds. As the tide rises she is swept from one to the other by the long sweeping waves; she is swung round and round in the swirl of the cross seas and rapid tide, thumping and jerking heavily each time that she strands.” — Op. cit, p. 109. “«, The heavy seas have driven the sands into high ridges, and the gullies between these are waist-deep and full of running water with the sand soft and quick at the bottom ; through these deep gullies the men have to wade.”’— Op. cit., p. 215. “ . At last all are on board, but they cannot yet leave the sands, they must wait until the water is high enough to float the lifeboat over the ridge which surrounds her.” —Op. cit., p. 222. 1882. ] On the Formation of Ripplemark. 5 Feeling satisfied that the bottom of Torbay in about 6 fathoms at low water spring tides was rippled by the swells following the October gales, I proceeded to construct a small tank, about 9 feet by 3 feet by 1 foot, in order to prove experimentally whether subaqueous ripple- marks could be formed at will, and to what extent their dimensions could be controlled. Working on this small scale I experienced no difficulty in forming good ripplemarks varying in size from 3th of an inch to 4 inches from crest to crest. The tank was commonly arranged as follows :— The sand was so piled up at one end that the waves when generated would quickly tear down what they wanted for a strand on which to break, and from that strand outwards the amount of sand used was regulated by the depth of water required for each experiment. The further end of the tank where the waves were generated was kept free from sand so as to have the greatest available depth of water, gene- rally about 9 inches. The waves were generated by a vertical dis- placement of the water, either by means of a V-shaped trough worked by hand or by means of a semi-cylindrical block of wood worked by a small model steam-engine. The following five experiments will show how very rapidly ripple- marks can be formed. (1.) Waves 60 per minute, height trough to crest about 14 inches. Result, 15 inch ripples in water 2 and 3 inches in depth. (2.) Waves 115 per minute, height not measured. Result, $ inch ripples well developed in 2 inch water, and discernible down to 3$ inches deep. (3.) Waves 23 per minute, height not measured. Result, the small ripplemarks now effaced and replaced by others 14 inch in size. In the above cases the experiments lasted exactly one minute each. (4.) Agitated the water at the centre of the tank, gradually getting up an even swing of 15 to the minute. The time was taken alter the water was in full swing, and the experiment may have lasted one minute and a half. Result, ripplemarks were now more or less developed over the whole bottom, the largest being 3 inches in length. (5.) The beach was now removed and the sand levelled over the whole tank. The water was disturbed with an even swing as much as possible. It rebounded from end to end, and dashed over the two ends, which in this experiment were 5 inches above the water-line. The sand being completely stirred up was left a night to settle, and the next day the water being still turbid, it was drawn off. Result, the bottom proved to be strongly but unevenly rippled all over with ripples varying in size from less than 1 inch to over 4 inches; the greatest depression being about 4 inch from trough to crest. In one case a set of ripples had been formed exactly at right angles to a larger set which was nearly obiiterated by them. 6 Mr. A. RS Eni, [ Apr. 20, In a paper published in 1859,* Mr. H. C. Sorby, F.R.S., showed how currents flowing in one direction form the kind of ripplemark or current mark termed by him “rippledrift;” but, as the currents that form the ripplemarks on the sea-shore are alternate and set up no drifting action in the ordinary sense of the word, it seems to me important to distinguish between the current mark that can be seen occasionally on the bottom of running water and the marine ripple- mark that differs from it, both as to its origin and as to its effect. I believe the symmetrical ripplemark of the sea-shore cannot be formed by a continuous current, and that whether recent or fossil ib is as certain an indication of an alternate wave current as the “ripple- drift’ is of a continuous current. Both of these current marks can be readily formed in a round tub of water with a little sand on the bottom. If the water be rotated constant-current ripples or ‘“ ripple- drift ’’ are formed: if the tub be carefully rocked symmetrical alter- nate-current ripples shortly appear. My experiments having satisfied my mind that ripplemark can be formed on sandy bottoms by a slight oscillation of the water, I took - an early opportunity of visiting the shores of Torbay, between Torquay and Livermead Point, for the purpose of ascertaining definitely whether the size and direction of natural ripplemarks bore any rela- tion to the force and direction of the wind. The day selected was the 21st January, 1882, after a week of calm weather, accompanied by the highest recorded rise of the barometer in Britain. There had been very little wind for days, but a slight swell on the 20th, and very low tides promised a well-rippled beach for the 21st. On reaching the sands under Sulyarde Terrace, I observed that they were covered with the most perfect and symmetrical ripplemarks from the south-west, the only direction from which a swell from the sea could reach them, as the new pier. protects that part of the shore from waves coming from any point more to the southward. Proceeding thence along the sands in a westerly direction, I saw the ripplemarks gradually getting effaced, until at a point opposite the Belgrave Road they were completely obliterated, excepting in pools and depressions in the sand, where they were as perfect as before. At this point, which is not protected by the pier and is exposed to the open sea, the direc- tion of the ripples was south-south-east (8.8.H.). In one of the pools they measured 6 inches from ridge to ridge, and the ridges were sharply defined and perfectly angular. Under the Corbons, on a little beach between the rocks, there were some very perfect ripples 13 inches between ridges, and 13 inches in vertical height. Passing on to the next beach, Livermead Sands, I found a large area of sand covered by perfect 6-inch ripples from the south-east, which in their turn were * “On the Structures produced by the Currents present during the Deposition of Stratified Rocks.” ‘ The Geologist,” 1859, p. 137. 1882. ] On the Formation of Ripplemark. t crossed by 2-inch ripples from the north-east. The explanation of these cross ripples was clear. A portion of the sands was raised to such an extent that on the tide retiring an island was formed for a short time. at A 6-inch ripples owed their origin to the swell from the south-east, whilst all the sands were covered, whereas the 2-inch ripples owed theirs to the water running in and out at the back of the emerged sandbank at right angles to the direction of the main swell. On the 23rd January I went over the same ground again, with the following results. Under Sulyarde Terrace I again found the ripples coming from the south-west. Under the Belgrave Road their direc- tion was due south, well developed on flats, but obliterated on slopes towards the sea. In the ‘‘ submerged forest” clay was a round pool, 15 feet in diameter, with its bottom covered with 5-inch ripples from the south-by-east (S.b.H.), crossed by 13-inch ripples from east-by- north (H.b.N.) This was owing to the southern side of the pool drying before the eastern. On a small beach between the rocks, at the western ends of the sands, under the Great Western Hotel, the ripples, of different sizes but averaging about 3 inches, came as nearly as pos- sible from the south-east. Under the Corbons Head I again found the large ripples, the largest being 14 inches between ridges and 2 inches high; they were composed of sand, coarser than at Torre Abbey, and broken shells. At the east end of Livermead Sands there was again an extensive low bank, with pools on the landward side. On the bank were 3-inch ripples from the 8.H., gradually obliterated towards low-water mark, where the sand was quite smooth. One of the back pools was covered with perfect ripples, varying in size from 2 inches (by estimation, as they were inaccessible) to 17 inches by measurement. Direction of all, south-east. The landward slope of the sand-bank was covered with ripples from the south-east, crossed at different places by others from the north-eastward and eastward. At the west end of the Livermead Sands were some large, but not per- fectly preserved, ripples, 22 inches long between ridges and over 3 inches high. These observations prove that ripplemarks are independent of the direct action of wind, for on two separate occasions the Torre Abbey and Livermead Sands could furnish at the same time ripples coming from all points, from south-west to north-east (on the eastern side). They also show what a complicated problem is that of the size of ripplemarks, and how little the geologist can gather from mere size, for on the same beach were ripples ranging from 14 inches to 22 inches, and in one small pool almost every size was represented between 2 inches and 17 inches. Having shown that the conditions requisite for the formation of ripplemarks are alternating currents on a mobile bottom, I will pro- ceed to show that there is good evidence that alternating currents and 8 ir AY ik, ee, [Apr. 20, therefore ripplemarks, occur at much greater depths than is commonly supposed. To do this I must prove that there is occasionally motion at the bottom of the sea, and that this motion does not arise from continuous, but from alternate, currents. I will commence with asimple case, one that I have studied for many years, viz., Torbay. This bay is an inlet rather more than 4 miles in breadth and over 3 in depth, carved out of Devonian and Triassic rocks of varying degrees of hardness, and open to the south-east. In its centre there is a level area of about 5 square miles, round which a line can be drawn so as to include every 6-fathom sounding and to exclude every other. The bottom over this area consists superficially of a very fine sand, of which a sample taken at any spot will represent the whole. After heavy easterly gales, as has been already stated, the water is very turbid, and the slushy bottom occasionally becomes harder. The level surface of the bottom, the uniformity of its mate- rial, the alteration in its character after gales, and the turbidity of the water, all point to one conclusion, viz., that storm waves materially afect the bed of the bay. To the intensity of this action the fauna also bears witness. Shells that inhabit the 5- and 6-fathom areas, such as Thracia convera aud Cardiwm aculeatum are occasionally washed ashore from considerable distances. A valve of a full-grown Thracia conrexa, picked up on Paignton Sands, was some 3,000 yards distant from the only spot where, to my knowledge, that moilusc has been taken alive in Torbay. Specimens of Cardium aculeatum are occasionally washed ashore and sometimes in vast numbers, but they are invariably denuded of their spines. Hven though not washed ashore, thousands are sometimes rolled and killed in the 6-fathom area, Whilst those that survive testify to the severity of the ordeal passed through by the damage done to their shells, and by the repairs effected. The contrast between the old shell denuded of spines and the rim of new growth with spines perfect is often very marked. In one specime. in the museum of the Torquay Natural History Society half the shell is quite smooth and the other half furnished with perfect spines. There are very few genera of molluscs, whether bivalve or univalve, that inhabit the 6-fathom area of Torbay, provided their shells are not internal, whose shells do not occasionally bear upon them the marks of a struggle for existence, more or less severe, with the storm waves of Torbay. The marks of damage to which I allude, when severe, cannot be mistaken for lines indicating cessation of growth from change of tem- perature, lack of food, or other such cause; they do not indicate merely a check in the formation of new shell, but in very many cases the destruction of the old. Nor are these marks confined to indi- vidual shells alone, for they are often common to whole colonies together. If a single cardium be found, with the new shell growing 1882.] On the Formation of Ripplemark. 9 out from under the old, owing to the edges having been too much damaged to admit of continuous shell formation, it may be contended that the individual mollusc had met with some special accident, but when hundreds of cockles are dredged together, showing the same marks of damage, repair, and subsequent growth, it is impossible to escape from the conclusion that they were all subjected together to some serious disturbance of their beds. In a paper read to the Devonshire Association, in 1878,* I showed, from the data furnished me by Lord Rayleigh, that on the 6-fathom area in Torbay a wave 300 feet long and three feet above mean level, if such ever occurred, would cause an alternating current at the bottom with a maximum speed of 3 feet per second. On two occasions (22nd October, 1880, and 4th April, 1881), since then, during easterly gales, I have observed waves with a period of 8+ seconds, and on one occasion, viz., on the 19th October, 1881, waves with a period of 8 seconds. On the last occasion, as has been already stated, I was able, by means of known marks to measure both the wave-length and speed. The leugth where measured proved to be 275 feet and the speed 660 yards per minute, but as the waves, before reaching the shore had to traverse about 1,000 yards of water less than 6 fathoms in depth, their length in midbay probably did not fall short of 300 feet. Their height I had no means of measuring, but at the low computation of one-thirtieth the wave-length, it would be 10, feet, or 5 feet above mean level.+ Leaving Torbay, with its comparatively shallow water, I will proceed to examine the evidence of disturbance at the bottom, in the deeper waters of the English Channel. The evidence at hand is of a varied nature, and includes the testimony borne by the character of the bottom itself, by valves of shells and other inanimate objects dredged up, by the character of the fauna, and by experienced fisher- men. In April, 1880, a large earthenware jar was brought up in the trawl of the Brixham smack ‘ Pelican” about 20 miles south-east of the Start point, where the depth, according to the chart, is about 36 or 3/7 fathoms. Mr. Pengelly, F.R.S., has described this jar with its contents (as received at Torquay) of half-a-pint of sand and gravel, and from the fact that “‘the whole surface of the bottom, as well as about fully one- half of the entire lateral surface ’’ was covered with marine organisms and that the jar was not abraded, arrived at the conclusion “ that the Zu brans: Dev. Assoe:,’: vol. x, p. 192. + On the 25th October, when the weather had moderated, H.M.S. ‘‘ Inflexible”’ left Plymouth for Gibraltar. On her arrival there, Captain Fisher reported having encountered waves 300 feet in length and 24 feet in height.—(‘‘ Western Morning News.”’) 10 Mr. A. R. Hunt. (Apr. 20, jar underwent little or no movement after reaching the sea bottom a a that there was very little movement of the gravel there,” and that ‘‘of storm-wave movement there could have been none, and of tidal-wave movement very little.”* This reasoning seemed to me very difficult to turn aside, until I was told by one of the crew of the ‘‘ Pelican” that the jar contained a quantity of gravel, and that it could scarcely have moved, being so weighted. This point seems to me of so much importance that I recently requested Mr. Hayden, the captain of the ‘“ Pelican,” who did not remember the circumstance, to make further enquiry of the second hand, who had given me the information. He replied as follows :— “ Brixham, Feb. 16th, 1882. ‘“‘ DEAR Srr,—I have been speaking to Mr. Dyer about the jar that we caught, and he says he remembers very well about it, and that it was nearly full of very dirty gravel; and I think the jar did not move on the bottom; when the bottom gets disturbed it must have washed in the jar. Please to excuse my writing to you only I thought you would like to know. I have got a few shells, and I hope by the time Mr. Baynes comes over again I shall have a basketful.—From J. Haypen, Master of smack ‘ Pelican.’ ‘“‘T think the gravel must have been in the jar a very long time, owing to its being so dirty.” I have ascertained by measurement that when the jar is laid on its side, the lower internal lip of the neck is 94 inches above the surface on which the jar is resting. The internal diameter of the neck is less than 2 inches. Through this small hole the gravel that filled it must have found its way; but for it to do this, it was absolutely necessary, either by the motion of the empty jar, or of the gravel, or of both, to get rid of the 94 inches of space that, during times of quiescence, lay between them. Then, again, when found, the jar was half buried in gravel, and this fact also proves sufficient motion at the bottom in 36 fathoms of water to move gravel whose character has been described by Mr. Pengelly, from the sample left in the jar, as “sub-angular and rounded stones, the largest of which scarcely exceeded a hazel nut in size.” . The fact that the jar was half-buried is of importance, as it proves motion of the bottom itself, and is not liable to the objection that might possibly be raised (though there is strong evidence to the con- trary) that the jar was full of gravel when lost. The evidence of motion afforded by the character of the marine fauna, if considered in detail, would require more space than can be * “Trans. Dev. Assoc.,” vol. xii, p. 76. 1882. ] On the Formation of Ripplemark. re afforded in the present paper. A very cursory glance at it must suffice. The character of the fauna of the littoral zone is such that it can be seen at a glance that the chief enemy that has to be contended against is the wash of the waves. Molluscs and crustaceans living on rocks are specially adapted to cling tightly to those rocks, whereas those living on sand have the power of burrowing in the sand. Where the ground is solid, as in the case of rocks, the animals living on it trust to their powers of holding on or of boring into it; where the ground is unstable the animals that frequent it trust to their powers of rapidly shifting their positions. Of the former class the limpet is a good example; of the latter the common razor fish. But if the mollusca of the littoral zone are specially adapted to resist the wash of the waves that would drive them high and dry on shore, it is equally true that many of those living in the laminarian and coralline zones are wonderfully provided against their special danger, viz., the aliernate swing of the waves on the bottom. Living as they do con- tinuously under water, their shells are free to assume the most elaborate sculpture and form, from which the littoral shells are pre- cluded, owing to a compulsory cessation of growth twice a day by retreat of the tide. In many cases the development of the lip, or of the sculpture in the form of spines, supplies exactly what the animal wants, viz., a broad base for a sandy bottom. By the kindness of the Rev. A. Cook I have been able to experiment with a few winged and spined shells from different parts of the world. One experiment with a Murex monodon from Australia, a Pieroceras lambis from the Hast Indies, a Strombus tricornis from the Red Sea, and four speci- mens of Aporrhais pes pelecant from Torbay was very instructive. Placing them all on their backs in my tank, I succeeded on one occasion in fifteen seconds in restoring them all to their proper posi- tions, simply by swinging the water in the tank. Owing to the weight of the foreign shells some difficulty was experienced in getting them in motion, and moreover, with the exception of the Aporrhais and Piteroceras, they were not particularly suitable for the experiment, as they had not wings or spines very largely developed. In the case of the extremely long spined murex, M. tenwispina, though the spines offer great resistance to the animal being overturned, they do not afford any assistance to the animal to recover its balance when once it has lost it. In the best examples of winged and spinous shells, such as Aporrhais and Pteroceras, the alternate current requisite to upset them is very much more powerful than one sufficient to restore them to their normal position. As Aporrhais pes pelecani is a beautiful instance of a gasteropod proof against moderate wave action, so the common Pecten maximus is _ a good example of like protection among the bivalves. Owing to one 12 ‘Mr. A.B. Hunt. [Apr. 20, valve being flat and the other curved it follows that a slight dis- turbance of the water will place it in a stable position. I find that it is quite easy to roll over a full grown P. maximus in my small tank if resting on the convex valve, but to dislodge it when resting on the flat vaive transcends the power of any current I can bring to bear upou it. Owing to the rejection by naturalists of the theory of submarine wave-motion, the fact that certain parasitic sea anemones, such as Adamsia palliata and Sagartia parasitica, commonly choose a shell tenanted by a hermit crab (pagurus) has been a matter of some perplexity. But, given the submarine wave action, and the problem finds its solution. The crab keeps the shell from rolling, and the anemone from being killed. I have taken many young specimens of Sagartia parasitica on living shells of Turritella terebra, but from the state in which I have seen shells of this mollusc damaged by rolling, I cannot conceive the possibility of the young anemones having much chance of surviving the first severe storm. The protection afforded by hermit crabs is no matter of fancy, as anyone can see by gently rocking the water in an aquarium, tenanted by hermit crabs, on a sandy bottom. If the crab happens to be in his shell, the first impulse is to dart out his legs and claws, and hold on to the sand on as broad a base as possible. Huis cousin, the swimming crab (por- tunus), under similar circumstances will burrow, or, if finally dis-, lodged by the shifting of the sand, will dart upwards into the water to escape the commotion. Many of the small fishes, crustaceans, and molluscs that frequent the 6-fathom area of Torbay seem quite on their guard, and prompt in their action when disturbed by oscillating currents in a small aquarium. Want of space precludes the possibility of pursuing this branch of my subject further, and compels me to turn to the next question, viz., the evidence afforded by the shells of molluscs of motion on the sea floor. I have assumed that wave action on the bottom of Torbay will scarcely be denied, and have passed lightly the evidence of the Torbay shells. It now remains to consider the evidence of those found in deeper waters. Among the shells sent me by fishermen who have taken them on the oyster ground off the mouth of Torbay, in about ' 15 fathoms, have been several specimens of Trochus granulatus, an inhabitant of the coralline zone. On a careful examination of eight of these shells, it appears that not one of them has escaped rough treatment more than once in the course of its life, and that one of them has had to repair serious damages nine times, over and above any slight abrasion that did not suffice to interfere with the sculpture and regular growth of the shell. On the 10th February, 1882, I bought three scallops (Pecten maximus) at a fishmonger’s shop, where I was informed they had all been taken .off Berry Head on the 1882.] On the Formation of Ripplemark. 13 previous day. Two of them were nearly the same size and showed several marks of interrupted growth; one of the marks was quite unmistakeable, when the shells were about 15 inches long. I[ measured each of the convex valves of these pectens independently, recording the size of each when the interruptions to growth occurred. The lengths of each were as follows, measured in inches and six- teenths :— rs ° bo mle pole 2 ° ala No. 1. Growth checked when the length of shell was 155 [ou He HH op aloo |. o|"" ” 4¢ Total length 4,3; E i) m —& PB oO w OH DOH ell o| The interest in these pectens lies in the correspondence of their lines of arrested growth, which have clearly been caused by some external agent common to both shells, and are not due to any idiosyncracy. Taken separately both shells are inferior as examples of arrested growth to the specimen of Pecten maximus figured by Mr. Jeffreys on Plate XXV of his “ British Conchology.”’ On the 3rd of March I received the parcel of shells referred to in Hayden’s letter. They were taken whilst the crew of the ‘“‘ Pelican ” were pursuing their ordinary avocation of fishing, and their collection was spread over a considerable time. The exact locality whence came each shell cannot of course be specified, but it so happens that with the shells I received fragments of three of the Channel stones, which the crew of the “ Pelican”’ have been in the habit of sending me for some years past. These stones give us a clue as to the depth of water where the vessel had been fishing. One stone was taken 18 or 20 miles S.S.H. of the Start, another 20 miles S. of the Eddystone, and the third 15 miles 8.E. of the Start. The depth of water at the places indicated is (according to the chart) 38, 41, and 36 fathoms respectively. giving an average of over 38 fathoms. The majority of these shells bear on them marks of arrested growth, not, as a rule, so decided as those from shallower water, but in many cases quite un- mistakeable. Some details of the collection are given in the follow- ing table :— 14 Mr. ‘A. (2 debont: [Apr. 20, Showing Not showing Total number arrested arrested growth f oe growth. oridoubttuly oP otis Pecten opercularis.......... 22 3 25 emma eur Gisieie rs fete aici evi allele ete 6 a 6 Cardium echinatum ........ 2 2 Cardium norvegicum........ 2 2 4 Cyprina islandica......-.... 2 2 4, Tyee WANES oo 66 o950 55 FC 1 iL Solenmensis 3,-2.1 “0 i a Capulus hungaricus......... 8 6 14 Trochus granulatus......... 2 1 3 Trochus zizyphinus ..... i: a BI Mueritella tere bray... le 1-1 26 iL 1 Natica catena.......... 1 1 Buccinum undatum ...... a 2 6 JNU aeNOMS BA Mob Gabo oy oe 3 5) 8 Fusus buccinatus........... 2 2 Scaphander lignarius........ 5) IL 6 58 27 85 Without pretending to affirm that all the cases of arrested growth are due to wave action, it seems to me a significant fact that out of a miscellaneous parcel of shells from the Channel fishing ground, 68 per cent. should show signs of damage caused by some agent external to themselves. Notes on the above shells would be out of place here, but it may be pointed out that the oftentimes damaged state of such a sedentary mollusc as Capulus hungaricus may be owing to the fact that it is frequently found attached to pinna, and that pinna is one of the shells frequently found damaged. The frontispiece to Mr. Gwyn Jeffreys’ second volume of his ‘‘ British Conchology ” depicts a pinna that has received a decided check to its growth, but by no means a severe one. Having shown that disturbance of the bottom is evidenced at depths of a few fathoms by the visible turbidity of the water, and at greater depths by the damage done to shells and by the special pro- vision in their habits and structure to withstand such action, I now turn to the evidence of nautical men as to the existence of submarine wave action, and as to the actual dangers to which vessels are exposed owing to the effects of such action. My first witness will be G. Hayden, the skipper of the Brixham trawler “ Pelican,” and though his evidence amounts to little more than the expression of his opinion, it is the opinion of a man thoroughly acquainted with the subject under consideration. i submitted to him the following queries, to which he appended his replies and attested them by his signature :— (1.) Do you think the bottom on the fishing grounds off the Start 1882. | On the Formation of Ripplemark. 15 is affected by heavy gales P—Yes; I think the ground is very much disturbed by heavy gales. (2.) Do you find the fish act differently after gales, 7.e., swim higher or lie closer >—I think that fish are affected during the gale, but that after the gale they resume their usual habits. Captain Kiddle, of the White Star steamer “ Celtic,” writes (‘‘Nat.,” vol. 13, p. 108) that “‘On George’s Shoals, off Nantucket, during a heavy gale, the New York pilots and masters of coasting vessels assert that sand is frequently left on deck after a sea has broken on board, although the depth of water may be 12 or 14 fathoms. . . . . The shortness of the sea on the banks of Newfoundland, where the soundings are from 30 to 50 fathoms, is noticed by all the navigators of the Western Atlantic, as it reduces the speed of an ocean steamer more than the heavier waves of deeper water willdo. . . . . Inthe gulf stream north of the Straits of Bemine, after a ‘‘norther” has blown a few hours, the surface of the sea is covered with lanes of weed, although only a few patches might have been seen before the commencement of the gale.” Before passing on, it will be well to point out that the disturbance of the bottom on the banks of Newfoundland has strong zoological evidence in its favour. Mr. J. Gwyn Jeffreys, F.R.S., writes as follows of the bivalve Mya truncata. “The cod on the North American fishing banks seem to be equally fond of this mollusc; but it is not so easy to say how they procure it. Mya truncata is often buried from 8 to 10 inches below the sea-bottom; and it does not seem to be capable of changing its habitation.’’* Now, I have taken this very molluse alive in Torbay after easterly gales, and I have taken flat fish that have been feeding on Cardium aculeatwm killed by heavy seas. If channel seas can dislodge Mya truncata from its deep burrow in Torbay, there is every probability that Atlantic seas will dislodge it occasionally on the banks of New- foundland. The seaman's assertion solves the problem that has per- plexed the naturalist, and the fact observed and recorded by the naturalist strongly corroborates the statement and conclusion of the sailor. The evidence hitherto adduced goes far to prove that at depths of about 40 fathoms in the English Channel and of 50 on the Banks or Newfoundland there is not only motion at the bottom, but strong motion, far exceeding the gentle oscillation of the water that is sufficient to ripple a sandy sea-bed. According to Sir Charles Lyell, quoting from the “ Hnceyclopedia Britannica,” a current of but 6 inches per second will suffice to raise fine sand.+ This no doubt refers to constant currents, as it is far in excess of what is sufficient in the case of alter- * “ British Conchology,”’ vol. iii, p. 69. ft “Principles of Geology,” vol. i, p. 348, 10th edition. 16 , Mr. A. RoMebame: [ Apr. 20, nate currents. I found on trial with a small glass aquarium, contain- ing fine blown sand, that an alternating current passing over a space of 2 inches 120 times per minute strongly rippled the sand with ripples varying in size from one inch downwards. Thus an average speed of 4 inches per second sufficed to form ripples so large as one inch from ridge to ridge. It is clear that a much slower current would still suffice to produce smaller ripples. It would be a matter of great interest to know at what depth an Atlantic wave would set up an alternating current of 4 inches per second, for, whatever the depth, it would fall short of that at which ripplemarks might be formed. Although the question of the relation of current ete to depth of water, a to height and length of wave, is one that must be left to the mathematician, and is one with which I cannot pretend to grapple, the following experiments, though on a small scale, may be worth recording :— Dried peas placed on a glass plate in a slight depression on a sandy bottom in 6-inch water were rolled off by waves about 12 inches long, and about 1 inch high. Although the motion was due to the waves, the fact that the peas were ultimately rolled off the plate was due to the difficulty of getting the glass perfectly level under water. Shorter waves 14 inches high had much less effect on them. A little sand that had collected on the glass was beautifully rippled with 3 inch ripples; these were dried and varnished. As it was difficult to discern slight motion of any object owing to the undulation of the water, I proceeded to make a rough indicator, whereby a vane of thin wood placed at the bottom at right angles to the course of the waves would communicate a multiplied motion to a long light needle above the surface. With this rough machine I tried the following experiments :— (1.) Water, 8 inches; to top of vane, 7 inches. Waves, 90 per minute; motion by indicator very marked. (2.) Waves, 115 per minute, half inch high; motion doubtful. (3.) Waves, 86 per minute, 1 inch high; motion at bottom very strong ; index striking both checks. (4.) Waves, 80 to 90 per minute 3 of an inch high; motion at bottom strong. This last experiment was an unintentional one. The larger waves - had made a strand for themselves, and I found that by reducing the displacement of the wave generator, I could make smaller waves that, without altering the mean level of the water, rippled the lower part of the former strand which they by their smaller reflux failed to uncover. Thus by a slight alteration of adjustment of the generator, I could, by varying the height of the waves, form or destroy ripple- marks at pleasure. Whilst making these experiments, I chanced to 1882.] On the Formation of Ripplemark. 7 reduce the number of the low waves to between 80 and 90 per minute. These, though barely over { of an inch in height, immediately affected the submerged vane, and the motion of the index attracted my eye, though I was not attending to it. On a subsequent occasion I found that waves between 80 and 90 per minute, and only 3 of an inch high, moved the index at a depth of 62 inches, and moved flocculent matter on the sandy bottom at a depth of 7? inches. In this experiment motion at the bottom was obtained when the depth was 62 times the height of the wave,.though small in propor- tion to the wave-length. If the evidence of the existence of alternate currents on the floor of shallow seas is strong; the evidence that the currents of power sufficient to roll and damage shells, are not constant currents, is still stronger. Molluscs, such as pinna, and mya, that have little, if any, powers of locomotion, could not coexist with currents capable of transporting in any quantity, even fine sand. Whey would perish, either from the destruction of their beds by the removal of the sand, or from fresh material being piled on top of them. Mr. Godwin Austen has well said, that a ‘‘drift-sand zone-”’ is wholly unfitted for marine life.* But it is the drifting sand that is fatal, not the mere fact that the drift sand zone is the one that “‘ comes within the range of the tidal and wave disturbance of the water.” Off Paignton Sands in Torbay, the very zone described by Mr. Godwin Austen abounds in Oardium tuberculatwm and Donaa vittatus, but owing to the fact that the sands are open to heavy seas from one quarter only, they cannot drift, and the shells mentioned, as.a rule survive the attacks of the waves, though many individuals succumb. As ripple marks are formed under water, so also they can be pre- served under water; and they are more likely to be there preserved than on a sea beach, where on the retreat of the tide, they are liable to be effaced by the very swell that has fermed them. In the case of a lake or sea, subject to slight changes of level, with a river running into it carrying mud or sand, we have all the con- ditions necessary for the formation and preservation of ripplemark. An occasional swell from the lake will ripple the submerged sand in the vicinity of the accumulating deposits brought down by the stream, and these will quietly cover up the ripples without effacing them. A slight rise in the level of the lake will shift the area of deposition further up the stream, and the bed that covered the ripples will in course of time be itself rippled, and in its turn covered up. In this manner a series of ripplemarks and beds of mud or sand often “ false- bedded,” may be rapidly formed, and in the case of increase of current as rapidly destroyed. Ripples that have been left bare by the retreating tide, or possibly * “Natural History of the European Seas,” p. 253. VOL. KXKXIY. C 18 Dr. Tyndall. [Apr. 20, by the sinking waters of an inland lake or sea, may often be distinguished from those that have been formed and preserved under water. The former are usually imperfect through loss of their sharp ridges.* Occasionally in addition to this they form natural channels for surface drainage, and whilst their ridges are levelled, their furrows are deepened. This fact seems to be referred to by Dr. Geikie, in the third edition of his ‘‘ Manual of Geology,” where he points out, that owing to the ridges of fossil ripplemarks being often broad and equabie while the intermediate furrow has a little channel; a cast can be distinguished from an original rippled surface, by the channel in the original surface producing a sharp little crest on the cast (“ Man. Geol.,” Jukes and Geikie, p. 172, 3rd Ed.). The points that I have endeavoured to establish in the foregoing pages may be briefly recapitulated as follows :—Marine ripplemarks are formed by alternate currents set up by waves. Experiments with short high waves on a small scale prove strong action at a depth of half the wave-length, whilst the evidence of the marine fauna, and the testimony of nautical men go far to prove that ocean and channel waves strongly affect the sea bottom to at least the same relative depth. The depth at which proof of wave action can be forthcoming falls far short of that-at which fine deposits can be rippled by currents incapable of leaving permanent traces in the damage done to shells. It is scarcely necessary to point out that the subject treated of in the present paper, namely, the formation of ripplemark, is only one branch of a far wider and more important one, which for the sake of brevity, I have as much as possible kept in the back ground, namely, that of submarine denudation. Il. “ Note on General Duane’s Soundless Zones.” By Dr. JOHN TYNDALL, F.R.S. Received March 21, 1882. In reference to one of the powerful fog-whistles established on the coust of Maine, General Duane remarks as follows :—-‘‘ The most per- plexing difficulties, however, arise from the fact that the signal often appears to be surrounded by a belt varying in radius from 1 to 1$ mile from which the sound appears to be entirely absent. Thus, in moving directly from a statiou the sound is audible for the distance of a mile, is then lost for about the same distance, after which it is again distinctly heard for a long time. This action is common to all ear- * For an illustration of the former class see plate facing page 170 of “The World’s Foundations,” by Miss Agnes Giberne; and, for an illustration of the latter, see page 19 of Sir Charles Lyell’s ‘“ Elements of Geology,” 6th Hdition. A.R.H., 4th May, 1882. 1882. | Note on General Duane’s Soundless Zones. 19 _ signals, and has been at times observed at all the stations, at one of which the signal is situated on a bare rock 20 miles from the main- land, with no surrounding objects to affect the sound.” For a long time past, I have thought that this disappearance of the sound was due to the interference with the direct waves, of waves reflected from the surface of the sea. This explanation is capable of very accurate experimental illustration. Placing, for instance, a sensitive flame at a distance of 3 or 4 feet from a sounding reed, the flame exhibits the usual agitation. Lifting a hight plank between the flame and reed, a position is easily attained where the sound, reflected from the plank, increases the flame’s agitation. Lifting the plank cautiously still higher, a level is attained, reflection from which com- pletely stills the flame. By slightly raising or lowering the plank, or by its entire removal, the flame is once more agitated. In these experiments a high pitched reed was used, so that it was easy to produce by the motion of the plank the retardation of half a wave- length requisite for interference. In General Duane’s case, a fairly smooth sea would be required for the reflection; while the position of the zone of silence would be determined by the height of the signal on the one hand and the height of the observer on the other above the surface of the sea. The position would also, of course, depend on the pitch of the note of the whistle. The preparation of some lectures on the ‘‘ Resemblances of Sound, Light, and Heat,” has recently brought this subject to mind, hence the present communication. 20 Mr. J. N. Langley. pApragis April 27, 1882. THE PRESIDENT in the Chair. The Presents received were laid on the table, and thanks ordered for them. The.Right Hon. Lord Bramwell and Dr. Ramsay H. Traquair were admitted into the Society. The following Papers were read :— I. “On the Attitudes of Animals in Motion.” By EADWEARD MuyYBRIDGE, of Palo Alto, California. Communicated by THE PRESIDENT. Received April 20, 1882. II. “Preliminary Account of the Structure of the Cells of the Liver, and the Changes which take place in them under Various Conditions.” By J. N. LaneiEy, M.A., Fellow of Trinity College, Cambridge. Communicated by Dr. MICHAEL FosTER, Sec. R.S. Received April 24, 1882. I have examined the structure of the liver-cells in the frog, toad, newt, the common snake, the grey lizard, the roach and smelt, the pigeon, and various mammals. In all these the “resting” liver cells have the following common points of structure. The protoplasm is arranged in the form of a network or honeycomb, the meshes or spaces of which are in all parts of the cell of much the same size; the outer parts of the cell are formed of a thin layer of slightly modified protoplasm with which, however, the network is continuous. The spaces of the protoplasmic network are occupied by paraplasm or interfibrillar substance, consisting of (1) spherical granules, pro- bably proteid in nature ; (2) spherical globules of fat; (3) hyaline sub- stance, fillmg up the spaces not occupied by the granules or globules. This substance consists partly of glycogen and in part probably of a proteid. This description differs in several points from those given by pre- vious observers. The account given by Klein* resembles it more * Klein, “ Quart. Journ. Med. Sc.,” N.S., xix, p. 161, 1879. 1882. ] On the Structure of the Cells of the Liver. 21 nearly than any other. Klein described the liver-cells of mammals as consisting of a protoplasmic network and of a hyaline interfibrillar substance ; any apparent granules present he considered to be nodal points of the network. In preparations made after Klein’s methods the granules are in fact with difficulty, or not at all, to be made out. They are, however, very obvious in fresh teased or in osmic acid specimens, especially in such specimens of the liver of the mole. Previous to Klein’s account of the mammalian liver-cells, Kupffer* described the liver-cells of the frog as consisting of a protoplasmic network and of hyaline paraplasm. He figures the network as being very irregular, with small granules in its bars, as being completely absent from considerable portions of the cell, and as having much finer meshes in the outer part of the cell around the nucleus. Kupffer’s observations were made upon the tissue treated with osmic acid or with 10 per cent. salt solution and iodine. In sections of a frog’s liver hardened in osmic acid I find the cells to consist of a slightly stained mass, in which granules and fat globules are imbedded. Treatment with other reagents shows that this slightly stained mass really consists of a network, and interfibrillar substance, the latter not in a granular form, but occupying the spaces in the network unoccupied by the granules and globules. If the liver is exposed for some time before it is placed in osmic acid, the granules are no longer distinct; an irregular network-like structure is formed out of them. This may possibly be the network of Kupffer. Further, in the liver-cells of a healthy, hungry (not fasting) frog the protoplasmic network stretches fairly equally throughout all parts of the cell; in winter frogs which have long fasted (cf. below, p. 22) the network has wider spaces and thinner bars in one part of the cell than in the other; but then the wider meshes are found in the outer, and not in the inner part of the cell and are not absent from any cell region. Lastly, in osmic acid specimens of such cells the outer parts appear homogeneous, except for fat globules, the inner zone is crowded with distinct granules. Hence it is obvious that the network of protoplasm and the para- plasm described by Kupffer do not in the least correspond to the net- work of protoplasm and interfibrillar substance described by myself. Whilst the liver-cells of all classes of vertebrates which I have exa- mined have the above-mentioned common characters in the “‘ resting ” state, they have certain minor distinguishing characters in each class, depending chiefly upon the size of the cells and their nuclei, the posi- tion of «the nuclei, and the relative amount of the various cell- constituents present. Of these, however, I do not propose to give an account here. Hering, in 1867, pointed out that the liver in all vertebrates except * Kupffer, “ Festschrift an Carl Ludwig,” 1875. 22 Mr. J. N. Langley. [ Apr. 27, mammals is an anastomosing tubular gland. Hence we should expect that the changes which take place during digestion in the liver of an amphibian, reptile, fish, or bird should differ somewhat from those which take place during digestion in the liver of a mammal. I have taken the liver of the frog and toad as an example of the tubular gland form, and have made observations on this during the last two years and a half. How nearly the changes which take place in other “tubular” livers resemble those which take place in the “tubular” livers of the frog and toad can of course only be decided by direct observation ; but it seems unlikely that the change should take any very different course, since the resting state of the cells and their arrangement in the gland is so very nearly the same. The Liver of the Frog. The liver of the frog and that of the newt can be observed while the blood continues to circulate through it; in this state nothing is seen in the cells except the fat globules; if a small piece be teased out in salt solution, the faintly outlined granules are seen floating in the fluid; these become obvious on adding iodine. The best method for bringing out the granules and fat globules is to place a small piece of the liver in osmic acid, 1 per cent., fora day, to transfer 1t to alcohol for several days, and then to prepare sections; in such sections the granules and globules appear to be imbedded in homogeneous cell substance. The granules are largest in the liver of the newt, so that the liver of this animal is best adapted to show that the granules are not the nodal points of the network. The network of the cel! is brought out most distinctly by chromic acid, 0°5 per cent.; it can also be seen in specimens hardened in picric acid, alcohol, mercuric chloride, or in teased out specimens of a liver which has been treated with neutral ammonium chromate, 5 per cent. When a section of the liver which contains glycogen, and which has been hardened in acohol or osmic acid, is placed for some minutes in iodine solution, certain parts of the interfibrillar substance of the liver-cells stain red-brown. The substance which is so stained I conclude to be glycogen. By water, even at 30° C., it is only slowly dissolved. Since isolated glycogen is readily soluble in water, this might lead us to think that the red-staining substance is not glycogen ; but we know that glycogen is not readily extracted from the liver by warm water, and hence it seems probable that a large part of the glycogen of the liver exists in it in a form not very soluble in water ; but, whatever may be the condition of glycogen in the liver, I think I am justified in concluding that the red-staining substance in alcohol specimens is glycogen, since glycogen can be extracted from them, since the amount of the red-staining substance varies directly with the amount of glycogen which can be extracted, since the coloration 1882. ] On the Structure of the Cells of the Liver. 3) is just that produced when iodine is added to a little purified glycogen on a glass slide, and since it is rapidly dissolved by amylolytic ferment, such as an aqueous or glycerine extract of the parotid of a rabbit, During the summer months the liver of a hungry frog has granules scattered equally throughout the cell, and there is very little glycogen. During the long winter fast the cells change in appearance; the granules become more and more confined to the inner part of the cell, and form there a marked inner granular zone. The glycogen increases in amount, and is stored up chiefly in the outer part of the cell, where there are no granules. Osmic acid specimens of glands in this condi- tion show two distinct zones, an inner granular one and an outer, apparently homogeneous, one; the nucleus lies at the border of the two, or if the outer zone is large les in it alone. When such a specimen is treated with iodine, all or nearly all of the outer zone stains red-brown; around the granules also a varying amount of red- brown stained substance is found ; the network of the inner zone, the granules, and’ the nucleus stain yellow. In these specimens the network of the outer part of the cell cannot at all, or only very im- perfectly be made ont. It is, however, seen in sections of the gland which have been hardened in chromic acid. It is continuous with the network of the inner part of the cell, but has wider spaces, and its bars are finer. We know that in the csophageal glands of the frog and in such gastric glands as have been investigated on the point, the changes which take place in the cells in fasting closely resemble the changes which take place in them during digestion. So here, in the liver of the frog, the changes which take place when the animal is fed closely resemble those gradually established during the winter fasting period. ‘The extent of the changes occurring in digestion depends greatly upon the state of the liver cells before the animal is fed ; in summer the changes are slight, there is only a slight decrease of granules in the outer part of the cell and a slight increase of glycogen. The changes are much more marked when the cells have to start with a small outer non-granular zone; in such cases in the 6th to 8th hour of digestion the outer zone is large, and in the 24th to 30th the cells become granular throughout. When a frog which has already a large outer non-granular zone is fed the decrease of granules usually lasts a shorter time, and in the 6th to 8th hour of digestion the granules begin to increase. In other words, the using up and formation of granules go on at different relative rates in diiferent nutritive con- ditions of the body. The disappearance of granules and the formation of glycogen which takes place in winter frogs is only partly brought about by the absence of food; it is brought about in part perhaps chiefly by the low temperature. If winter frogs, the liver-cells of which have few 24 Mr. J. N. Langley. [Apr. 27, granules and much glycogen, are kept at about 20° C. for a week to a fortnight, the cells become granular throughout and the glycogen largely disappears ; similarly frogs in spring or autumn, the liver- cells of which have many granules and little glycogen, if kept at a low temperature a week to a fortnight, present in the cells of the liver an outer non-granular zone and an increase of glycogen; in summer frogs the effect is much less. Further, the changes during digestion are slight in winter frogs that have been kept in the warm, greater in spring and autumn frogs which have been kept in the cold. Although, generally speaking, a decrease of granules goes hand-in- hand with an increase of glycogen and an increase of granules with a decrease of glycogen, yet a certain amount of variation in the one may take place without any variation or any corresponding variation in the other. Hence I regard the formation of granules and the formation of glycogen as independent processes. A comparison of the changes which take place in the granules of the liver-cells with the changes which take place in the granules of the salivary, gastric, and pancreatic glands leaves me with-no doubt that the granules of the liver-cells are destined ‘to give rise to some constituent or constituents of the bile, and it seems to me more than probable that by appro- priate chemical treatment, we may obtain from them some one or more of the constituents of the bile-salts. In the account I have just given I have-omitted all mention of the fat globules. These vary so much with different conditions of the body, as yet unknown, that it is extremely difficult to determine what changes in their number and position take place during digestion. It is well known that there is in winter an increase in the amount of fat in the liver. ‘Generally speaking, in summer the fat globules are small, few, and fairly equally scattered throughout the cell, with a tendency to be more numerous around the lumen. In winter frogs the greatest variation occurs, occasionally there are very few, usually there are a considerable number, not unfrequently the cells are crowded with them, this is generally the case with obviously un- healthy frogs. Further, in the most common condition, that in which the fat globules are fairly numerous without being crowded together in the cells, they may occur almost entirely in the inner or almost entirely in the outer part of the cell. In the former case they make a conspicuous fat globule zone about the lumen, in the latter they occur in conspicuous clumps close to the outer cell-border; this is oenerally the case when one has reason to suppose that fat is increasing in the cells. If winter frogs are kept in the warm, the fat globules diminish in number; if summer frogs are kept in the cold for a week to a fortnight there is a slight, but only a shght, increase in the quan- tity of fat. The majority of frogs which are fed in the summer show little or no change in the number or size of fat globules in the liver, 1882. | On the Structure of the Cells of the Liver. 20 In winter the amount of fat in the liver varies so much in frogs appar- ently alike, that I do not feel justified in drawing any conclusions as to the changes occurring in digestion. The only other vertebrates with liver of the tubular type on which I have made a series of observations, are the toad and newt. The changes in the liver of the toad are in all essential respects the same as those I have described for the liver of the frog. In the newt’s liver I have not observed the formation of zones during digestion ; it appears to me to depart largely from the tubular type of gland, and to resemble in structure rather the mammahan than the ordinary amphibian liver. In the snake during the winter’s fast, an outer non-granular zone makes its appearance in the liver tubules; it is, however, much smalier than that in the frog and toad. I may mention that the cells of the frog’s bile-duct, where it runs through the panereas, are ciliated; the pancreatic duct with con- ciliated cells joins it close to the small intestine. The Mammalian Liver. In the mole the granules of the liver are conspicuous, and are pre- served by osmic acid; in the dog, cat, and rabbit the granules are more or less altered, hence I have chosen the mole to make observa- tions upon as to the changes which take place in digestion. In the hungry animal the protoplasmic network stretches throughout the cells with nearly equally sized meshes ; in the spaces of the network is a small amount of hyaline substance, partly glycogen, and embedded in this are rather large granules. When the liver is examined six to eight hours after digestion, there is a greater or less disappearance of granules from the centre of the cell around the nucleus ; the network here has wider spaces and thinner bars, and the spaces are for the most part filled with glycogen. In cases where these changes are most marked, osmic acid specimens treated with iodine show a diffuse reddish stained mass surrounding the nucleus ; at the borders of the cell, the yellow stained network is seen, and one or two rows of granules ; between these a little red stained substance may usually be traced continuous with the central mass of glycogen; the peripheral network and granules make the cell appear at first sight as if it had a very thick cell wall. The network in the central part of the cell is brought out by hardening a piece of the liver in chromic acid and other re- agents. In cells in which the digestive changes are less advanced, the glycogen may only partially surround the nucleus, or may he accumulated more on one side of it than elsewhere. Histological observations on the increase of glycogen in the liver- cells have been made by Bock and Hofmann,* on the rabbit, and by * Bock u. Hofmann, “ Virchow’s Archiy.,” 56, s. 201, 1872. 26 On the Structure of the Cells of the Liver. [Apr. 27, Kayser,* on the dog. Bock and Hofmann found that glycogen accumulated in amorphous form around the nucleus, and stretching out from this as a network towards the periphery of the cell. My own observations confirm this in the main. I regard, however, the glycogen as being stored up in the spaces of a protoplasmic network. Bock and Hofmann also mention granules of the liver-cells which stain yellow with iodine,} but they do not appear to have distinguished between these and the protoplasmic network which likewise stains yellow with iodine. Kayser (loc. cit.) found that glycogen was stored up in the form of “‘Schollen oder Korner ;” these lumps and granules of glycogen I have not seen; an appearance simulating this occurs when the glycogen 1s stored up more in some parts of the protoplasmic network around the nucleus than in others, but these local collections never have, so far as I have observed, sharply marked boundaries. The granules are not distinguished by Kayser from the protoplasmic network; these two together make up,. 1 imagine, the thick peripheral layer of protoplasm described by him as occurring in cells which contain much glycogen. As in the liver of the frog, so in the mammalian liver, I take the granules to be concerned in the formation of some of the substances found in the bile. | * Kayser. Quoted by Heidenhain. “ Hermann’s Hdb.,” Bd. v, Th. 1, s. 221, 1880. + Similar granules were also described by. Plosz.. “ Pfliiger’s Archiv.,” vii, s. 371, 1873. +1882.) On the Specific Resistance of Mercury. rac May 4, 1882. THE PRESIDENT in the Chair. The Presents received were laid on the table, and thanks ordered for them. In pursuance of the Statutes, the names of Candidates recommended for election into the Society were read from the Chair, as follows :— Ball, Professor Valentine, M.A. Godman, Frederic Du Cane, Brady, George Stewardson, M.D., RES: F.L.S. Hutchinson, Professor Jonathan, Buchanan, George, M.D. F.R.C.S. Clarke, Charles Baron, M.A., | Liversidge, Professor Archibald, ELS. F.G.S. Darwin, Francis, M.A., F.L.S. Malet, Professor John C., M.A. Dittmar, Professor William, F.C.S. | Niven, William Davidson, M.A. Gaskell, Walter Holbrook, M.D. Palgrave, Robert Henry Inglis, Glazebrook, Richard Tetley, F.S.S. M.A. Weldon, Walter, F.C.S. The following Paper was read :— I. “On the Specific Resistance of Mercury.” By Lorp Ray- LEIGH, F.R.S., Professor of Experimental Physics in the University of Cambridge, and Mrs. H. Stipawick. Received April 24, 1882. (Abstract.) The observations detailed in the paper were made with the view of redetermining the relation between the B.A. unit and the mercury unit of Siemens, 7.e., the resistance of a column of mercury at 0°, one metre in length, and one square millim. in section. According to Siemens’ experiments, 1 mercury unit='9536 B.A. unit, and according to Matthiessen and Hockin, 1 mercury unit=‘9619 B.A. unit. The value resulting from our observations agrees pretty closely with that of Siemens. We find 1 mercury unit='95418 B.A. unit. 28 On the Specific Resistance of Mercury. [May 4, Four tubes were used to contain the mercury, of lengths varying from 87 to 194 centims.. The diameter of the three first tubes was about 1 millim. and that of the fourth about 2 millims. The final numbers obtained from the several fillings of the tubes are as follows :— “95412 05424 $+ Mean ‘95416 "95436 954.21 r 95386 | : | "95389 "95444: Tbe 1223 ee 95437 Mean +95419 95436 "95424 "95418 : Tibe ile ses -95399 Mean *95416 95425 95440 95415 ae] S (oF (qo) — a — \ Mean -95427 Combining the results of the present paper with our determination of the B.A. unit in absolute measure, we get 1 mercury unit='94130 x 10° C.G.S. 1882. | T. S. Vanecek. Sur Inversion Generale. 29 May 11, 1882. THE PRESIDENT in the Chair. The Presents received were laid on the table, and thanks ordered for them. | The Right Hon. Sir Henry Bartle Edward Frere (elected 1877) was admitted into the Society. The following Papers were read :— I. “Sur VInversion Générale.” Par T. S. VANECEK. Commu- nicated by Dr. Hirst, F'.R.S. Received April 27, 1882. Dans une note “Sur l’inversion générale” qui était publiée dans les Comptes rendus de l’Académie Frangaise,* j’ai exposé Vidée d’une transformation plus générale que celle par rayons vecteurs réci- proques. Dans la note présente je ferai l’extension de cette transfor- mation. 1. Considérons une conique générale C et deux droites L, D. la premiere doit étre transformée par rapport a la droite D, appelée directrice, et 4 la conique C, courbe fondamentale. A un point a de la droite L correspond une polaire A par rapport a C et coupe la droite D enun point a. La polaire A, de ce point coupe la droite A en un point a, qui est le transformé du pointa.t Sa polaire passe par les points aeta,. Les points a, a, a, forment un triangle polaire par rapport a la conique fondamentale C. Quand le point a parcourt la droite proposée L, le point a, parcourt la droite directrice D, et le point a, décrit une conique (a,) qui passe par les points d’intersection des deux droites L, D avec la conique C et par leurs poles /,d.{ Sa polaire A, enveloppe une autre conique (Ay,) qui touche les droites: données L, D et les tangentes a la conique fon- damentale dans les points d’intersection de celle-ci avec les droites i. 2. Supposons que la droite L soit remplacée par une courbe d’ordre m et la droite D par une courbe d’ordre n, la courbe inverse de l’une * Tome xciv, p. 1042 (10 Avril, 1882). + Hirst, “On the Quadric Inversion of Plane Curves,” “ Roy. Soc. Prec.,” (1865), vol. 14, p. 92. + Ibid., p. 95. 30 T.S. Vanecek. Sur (Inversion Generale. [May 11 par rapport 4 lautre est d’ordre 2mn, donée de 2n points d’ordre m et de 2m points de Pordre n. Nous pouvons done énoncer les théorémes suivants : Quand le sommet a dun triangle polaire a, ai, a, par rapport a une conique C parcourt une courbe Li de Vordre m et a, parcourt une courbe D de Vordre n, le troisieme sommet ag decrit une courbe dordre 2 mn qui a 2m points multiples @ordre n et 2n points multiples dordre m qui sont les points d’intersection des courbes Li, D avec la conique OC. Ht réciproquement. Quand le cété A d'un triangle polaire par rapport a la conique C enveloppe une courbe Ly de la classe m, et le cdté A, enveloppe une courbe D, de la classe n, le troisiéme cété A, enveloppe une cowrbe (Ay) de la classe 2mn, douée de 2m tangentes multiples de la classe n et de 2n tangentes multiples de la classe m qui sont respectivement tangentes con- munes des courbes Ly, C et des courbes D,, C. Les courbes (a) et (A,) sont les polaires réciproques par rapport a la conique C. 3. La courbe (a,) est la méme si nous transformous la courbe L par rapport a la directrice D ou cette courbe D par rapport 4 L comme directrice. Considerons la courbe LZ comme dans le paragraphe pré- cédent, d’ordre m, et lacourbe D d’ordre n. les points d’intersection de la courbe I ou D avec la conique fondamentale Cappelons les points fondamentaux. Nous pouvous énoncer les theorémes suivants. Un simple point fondamental de la courbe LZ devient un point multiple d’ordre n de la courbe inverse (ay). Le point fondamental d’ordre m, de la courbe Lest un point multiple d’ordre m, ” de la courbe inverse (a). : Quand les deux courbes LZ, D ont un point fondamental simple a commun, ce point se transforme en un point multiple d’ordre m+n—2 de la courbe (a) et en la tangente de la conique fondamentale C en ce point a, qui fait une partie de la courbe inverse (ag). Le point fondamental a étant un point multiple d’ordre m, de la courbe Let le point multiple d’ordre 1, de la courbe D, ce point se transforme en un point multiple d’ordre. (n— 1) + (M—m,) Ny, et en la tangente A de la conique fondamentale en ce point; la droite A fait une partie de la courbe inverse (a,) et elle est une droite multiple d’ordre m, 7}. Le point multiple a d’ordre m, de la courbe I n’étant pas un point fondamental se transforme en » points multiples d’ordre m, qui se trouvent sur la droite A, polaire du point a. Quand ce point a se réunit avec un point multiple d’ordre n, de la courbe D, il se trans- forme en m points multiples d’ordre m, de la courbe inverse (a), qui sont distribués sur la méme droite polaire A. 1882.] Organisation of Fossil Plants of the Coal-measures. ol D’aprés cela il est toujours possible de déterminer le nombre et lespéce des points multiples de la courbe inverse et aussi l’ordre de la courbe (a) ou la classe de la courbe (A,). Supposons que la courbe inverse (a) d’une courbe L par rapport a une autre courbe D comme directrice soit construite ; la courbe inverse (a,) de la courbe (ag) par rapport a L se décompose en la courbe D et, une autre courbe, dont l’ordre est déterminé, ou réciproquement la courbe (a) a pour courbe inverse par rapport a4 la courbe D directrice une courbe quise décompose en la courbe ZL et en une autre courbe, dont lordre est connu. 4. Le point a de la courbe proposée I a une tangente A’ a cette courbe; cette tangente coupe la conique fondamentale U en deux points t,u. la polaire A du point a coupe la courbe directrice D en n points. La tangente B’ en un de ces points 6 rencontre CV en deux points 2, y, et la droite polaire B du point b coupe la droite A en un point a, qui est un point de la courbe inverse (a,). Considérons le point de contact a comme deux points infiniment voisins; la méme chose a lieu au point bd. A ces points imfiniment voisins correspendent aussi tels points dans la courbe inverse. Ainsi la courbe inverse de l’une des droites A’, B’ par rapport a Pautre, qui est une conique H, a avec la courbe (a,) deux points infini- ment voisins communs. Ces deux courbes ont par conséquent une tangente commune en ce point a,. La conique # est plus que déter- minée par les points 7, wu, #, y eb par a. Quand les peints ¢, wu ou 2, sont imaginaires, ils sont remplacés par la tangente et son point de contact, ou respectivement par deux tangentes et leurs points de con- tact et par le point ay. Le point a, sur la courbe inverse («,) étant donné nous construisons sa droite polaire par rapport a la conique fondamentale C et cherchons le point a sur L et b sur D qui correspondent au point a,. La conique # est alors déterminée et par conséquent aussi la tangente en dy. Il. “On the Organisation of the Fossil Plants of the Coal- measures. Part XII.” By Professor W. C. WILLIAMSON, F.R.S. Received May 4, 1882. (Abstract. ) At the recent meeting of the British Association at York, Messrs. Cash and Hick read a memoir, since published in Part IV of vol. vii of the ‘“ Proceedings of the Yorkshire Geological and Polytechnic Society,” in which they described a stem from the Halifax Carboniferous deposits characterised by a form of bark hitherto unobserved in those rocks. ‘To this plant they gave the name of Myriophylloides William. 32 Prof. W. C. Williamson. [May 11, sonis. It was characterised by having a large cellular medulla, surrounded by a thin vascular zone composed of short radiating lamellae. This, in turn, was invested by a cylinder of cortical paren- chyma from which radiated a number of thin cellular lamine, like the spokes of a wheel, separating large lacune. Hach lamina generally consisted of a single series of cells. At their peripheral end, these laminz merged in a thick, large-celled, cortical parenchyma. The generic name, Myriophylloides, was given to the plant because of the resemblance between sections of its cortical tissues and those of the recent Myriophyllum. ‘Two reasons induced the author to object to this name (‘‘ Nature,’ December 8, 1881, p. 124), and to propose the substitution of that of Helophyton. Such substitution, however, was rendered unnecessary by the discovery, by Mr. Spencer, of Halifax, of some additional specimens which indicate that the supposed new plant was merely the corticated state of the Astromyelon, described by the author in his Memoir, Part 1X.* These specimens showed that the plant was more complex than had been supposed, different ramifications of it having individual peculiarities. In some of the new specimens the vasculo-medullary axes present no differences from those of the Astromyelon already described.. The radiating lines of cells separating the lacune prove to be transverse sections of elongated vertical laminze composed of cells with a mural arrangement, and which separate large vertical lacune of varying lengths ; a type of cortical tissue clearly indicating a plant of aquatic habits. So far as this bark is concerned, all the ramifications of the plant display similar features, but several of the specimens exhibit important variations in the structure of the vasculo-medullary axis. In them the central cellular medulla is replaced by an axial vascular bundle, which has little, or in some examples apparently no, cellular element intermingled with the vascular portions. In some examples this axial bundle is invested by the thick exogenous zone seen in Astromyelon. In others that zone is wholly wanting. Yet there appears to be no reason for doubting that these are but varied states of the same plant which branched freely, the differentiated branches having, doubt- less, some morphological significances, as yet incapable of being explained. That the plant was a Phanerogam allied to Myriophyllum is most improbable. It has several features of resemblance to the Cryptogamic Marsilee, from which it does not differ more widely than the fossil Lepidodendra do from the living Lycopodiacez. The author describes a new specimen of Psaronius Renaultii, found by ‘Mr. Wild, of Ashton-under-Lyne. Those previously described consisted almost entirely of fragments of the bark and its eerial rootlets. The present specimen contains a perfect C-shaped fibro-vascular bundle and a portion of a second one, resembling some of those ~* <“ Phil. Trans, 2878: 1882.] Organisation of Fossil Plants of the Coal-measures. 33 described by Corda, and which leave no room for doubting that our British Coal-measures contain at least one arborescent fern, equal in magnitude to those obtained from the deposits at Autun. In his Memoir, Parts IX and X, the author described under the provisional generic name of Zygosporites, some small spherical bodies with furcate peripheral projections. Similar bodies had been met with in France, and were regarded by some of the French paleontolo- gists as true Carboniferous representatives of the Desmidiacee. The author was unable to accept this conclusion, deeming it much more probable that they would prove to be spores of a different kind. Mr. Spencer exhibited the specimen now described at the York meet- ing. It is a true sporangium, containing a cluster of these Zygo- sporites. Though they undoubtedly bear a close superficial resemblance to the zygospores of the Desmidiz, their enclosure within a common sporangium demonstrates them to be something very different. There is now no doubt but that they are the spores of the strobilus described by the author in his Memoir, Part V, under the name of Volkmannia Dawsoni. Hence the genus Zygosporites may be cancelled. Another interesting specimen found by Mr. Wild is a young Calamite, with a more curiously differentiated bark than any that has hitherto been discovered. The structure of the vascular cylinder and of the innermost layer of the bark differs in no essential respect from those previously described ; but the outermost portion displays an entirely new feature. It consists of a narrow zone of small longi- tudinal prosenchymatous bundles, each one having a triangular sec- tion, the apex of each section being directed inwards, whilst their con- tiguous bases are in contact with what appears to be a thin epidermal layer. As in every previously discovered Calamite in which the cortex is preserved, the peripheral surface of this specimen is perfectly smooth or “entire.” It displays no trace of the longitudinal ridges and furrows seen in nearly all the traditional representations of Calamites figured in our text-books. It has long been seen that the medullary cells of the Lepidodendra, as well as the vessels of their non-exogenous medullary sheaths, steadily ancreased in number as these two organs increased in size correlatively with. the corresponding general growth of the plants. But the way in which that increase was brought about has continued to be a mystery. ‘The author now describes a Lepidodendron of the type of L. Harcourtii in which nearly every medullary cell is subdivided into two or more younger cells, showing that, when originally entombed, the pith was an extremely active form of meristem, though the branch itself had attained to a diameter of at least two inches. The numerous small young cells are of irregular form. Their development by further growth into a regular parenchyma would inevitably necessitate a corresponding increase in the diameter of the branch as a whole; VOL, XXXIV. D 34 Organisation of Fossil Plants of the Coal-measures. [May 11,. and it must have been from these newly-formed cells that the medul- lary cylinder obtained the elements out of which to construct the additional vessels, the increase of which has been shown to be the invariable accompaniment of the growth of the branch. As might be expected, the growth of the vascular cylinder or medullary sheath could only have been a centripetal one. A new form of Halonia from Arran is described. Instead of its central portion consisting, as in previously described examples, of the usual Lepidodendroid medulla, surrounded by a vascular cylinder, it consists of a solid axis of vessels, resembling in this respect all the very young Lepidodendroid twigs previously described from the same iocality. Many recently obtained specimens of lLepidodendroid branches sustain the author’s previous observations that all examples from Arran having less than a certain diameter have the solid axial bundle; whilst all above that diameter have a cylindrical vascular bundle enclosing a cellular medulla. The first type commences with the smallest twigs, and is found increasing gradualiy up to the dia- meter referred to. The second type begins where the other ends, and increases in diameter until attaining the dimensions of the largest stems, in none of which does the solid bundle reappear. Halonial branches have not hitherto been described attached to the branches of any true Lepidodendron, though, in 1871 (Memoir, Part II), the author gave reasons, based upon organisation, for insisting that Halonia was a fruit-bearing branch of a Lepidodendroid tree. This con- clusion was sustained by Mr. Carruthers in 1873 in his description of a branch belonging to a Lepidophloios. The author now figures a magnificent example, from the museum of the Leeds Philosophical Society, of a dichotomous branch of a true Lepidodendron of the type of L. elegans and L. Selaginoides. In this specimen every one of the several terminal branches bears the characteristic Halonial tubercles. The leaf-scars of these latter branches have the rhomboid form once deemed characteristic of the genus Bergeria, whilst those of the lower part of the specimen are elongated as in L. elegans, &e. These differences are not due to their appearance in separate cortical layers of the branch, but to the more rapid growth in length of its lower part compared with its transverse growth. The author throws some additional light upon the structure of Sporocarpum ornatum described in Memoir, Part X, as also upon the nature of the development of the double leaf-bundles seen in trans- verse sections of the British Dadoxylons, described in Memoir IX: After a prolonged but vain search for a similar structure amongst the twigs of the recent Conifers, the author has at length found them in the young twigs of the Salisburia Adiantifolia. Sections of these twigs made immediately below their terminal buds exhibit this geminal arrangement in the most exact manner. Pairs of foliar bundles are 1882. | On certain Geometrical Theorems. 35 given off from the thin, exogenous, Xylem zone which encloses the medulla, whilst at the same points the continuity of the Xylem ring is interrupted, as was also the case with the Dadoxylons, by an extension of the medullary cells into the primitive cortex. Sections of the petiolar bases of the leaf-scales of the bud show that these bundles enter each petiole in parallel pairs, subsequently subdividing and ramifying in the Adiantiform leaf. This curious resemblance between Salisburia and Dadoxylon, accompanied as it is by other resemblances in the structure of the wood, bark, and medulla, suggest the probability that our British Dadoxylon was a Carboniferous plant of Salisburian type, of which Trigonocarpum may well have been the fruit. If so, the further possibility suggests itself that this plant may have been the ancestral form whence sprang the Baieras of the Oolites, and, through them, the true Salisburias of Cretaceous and of recent times. The Society adjourned over Ascension Day to Thursday, May 25. May 25, 1882. THE PRESIDENT in the Chair. The Presents received were laid on the table and thanks ordered for them. _ Mr. Bindon Blood Stoney was admitted into the Society. The following Papers were read :— I. “On certain Geometrical Theorems. No. 2.” By W: H. L. RUSSELL, F'.R.S. Received May 10, 1882. (4.) The following is a short method of determining the conic of 5 pointic-contact with a given curve. Write the conic CA SMSO qe eestor) a then differentiating four times and writing D for oo we have, re- membering that the four first differential coefficients of the two curves “coincide,— adi Bay) =—Dye-Quety ss... = 6), cl ys GAD (Gal) == D7 = 5.278 nae ae Pe (9) Dace ive ONL Ye i), CAD, 2D aD (ay). apne . Diz 36 On certain Geometrical Theorems. [May 209, Be Day A(esai hey) SaaS whence = D°y?D* (ey) — Diy?D° (ay) ne on Diy? Dty—DtyPDty D* (ay) Dty — D*(@y) D°y then pn, v, p are found from (1), (2), (3), and the conic determined. (5.) Let us now endeavour to show how the equation to the cubic with 9-pointic contact with a given curve is to be found. Writing the cubic aya + ba®y + cy? +dy + eay=y? + px? + ve? + puto, we differentiate eight times and obtain five equations from which yn, v, p, « have disappeared. aD*(y?x) + bD4(2?y) +¢Dty? + dD*4y + eD* (ay) = Dty’, with four others obtained by substituting in this equation D°, D®, D7, D® successively for D*. Hence we shall have— ¢ Di(y’x), D*@?y), Dty?, Dty, D*(ay) Di(y’x), D5(a*y), D5y?, D'y, Dé (ay) | a. 3 D6(y2x), D8(a?y), DSy2, Dy, D(ay) ¢ | Di(y’a), Di(a’y), Diy?, Diy, Di(ey) | UD8(y?x), D8(ay), D'y?, D’y, D§(ay)J ( D%(a%y), Diy, Diy, Diy) ) _ pis | Dy), Diy? Diy, De(ay) | | Di (ay), Diy?, D‘y, Di (ey) | D&(a*y), D®y’, D®y, D®(«y) J ae ON ( D*(xy), D4y?, Dty, D4(ay) | , | Di(ey), D®y?, D'y, D&(ay) | + D> 3 9 ? b) i WY) Di(a%y), Diy2, Diy, DiCey) | | D§(a*y), D8y’, Dy, D®(@y) J ( D*(a?y), Dty?, D'y, D*(zy) ) +Dsys 4 DEC) ee aa | Di(a?y), D7y?, Diy, D7(ay) | | De(@*y), Dey”, Dey, D8@y) Di(a*y), Dy’, Dty, D*(ay) | 73 | D°(ay), Dy’, Dey, D°(y) a Ce ee on, ery L pice, D*y?, D®y, D®(ay) J 1882.] W. Spottiswoode. Geometrical Theorems. 37 | Dt(a?y), Dty’, Dty, D*(ay) } , | D°(2y), D*y?, D°y, D°(ay) $7)8 FDNY Do(2y), Dy, D'y, Day) {" L pig), Diy’, D'y, Di(azy) J In the same way 0, c, d, e are determined, and then ug, »y, p, o are known from the third, second, first, and original equations. (6.) In the same way we may proceed to find the 14-pointic contact of a curve of the fourth order. The coefficients will be expressed by series of determinants, each having eight rows and eight columns, divided by a determinant having nine rows and nine columns. And the same method will apply to the general case. II. “Note on Mr. Russell’s paper ‘On certain Geometrical Theorems. No. 2.’” By WILLIAM SPOTTISWOODE, Pres. R.S. Received May 25, 1882. Tf we apply Mr. Russell’s formule to the determination of the sex- tactic points of a curve, we shall have, in addition to the equations (1)—(5), the following — aDiy + pD%(ey)=D5y?; and by elimination of z and # from his equations (4) and (5), together with this latter, we shall obtain as the condition for a sextactic point — D7 Dec ey — Oi as GP a4 5a ts) s, CAE 19 pe ee ee Dy, Dex, D*y?. But Day= y +2Dy, Dezy=2Dy +2D?y, Dezy=3D?y +2D*y, Dtzy=4D*y +2D4y, D°ay=5D*y +2D°*y, Dy? =2yDy, D*y? =2yD°y+ 2(Dy)?, D°y? =2yD°y+ 6DyD*y, Dty? =2yD*y+ 8DyD*y+ 6(D*y)?, Dy? =2yD>y +10DyDty + 20D*yD%y. 38 W. Spottiswoode. Geometrical Theorems. [May 25, Substituting in equation (A), we obtain— D®y, «D®y+3D*y, 2yD*y+ 6DyD2y =) Dty, «Dty+4D%y, 2yD4y+ 8DyD*y+ 6(D2y)?2, D°y, #D°y+5D*ty, 2yD°y+10DyD*y + 20D2yD3y. Whence by obvious inductions— D*y, 3D?y, =0 ye) cep yy Dty, 4D*y, 3D?y, D®y, 5D4y, 10D%y. Also D{4(D37)?—38D*y . Dty}=4D3y . D4y—3D2y . D>y. Hence the equation (B) may also be written thus— (10D?y—3D?y . D){4(D*y)?—3D?y . D4y}=0 . . (GC). And in order to evaluate the expression it will consequently be necessary, in the first instance at least, to calculate only Dy, .. . D4y. The main interest in the problem, however, lies in the determination of the degree of this equation, which has been found by Cayley and myself to be 12n—27. The difficulty hes in getting rid of the ex- traneous factors. In order to effect this, the expression (C) must be transformed by the substitution of —w: v for Dy, and other expressions to be calculated for D’y, ... D*y. If U=0 be the equation to the curve, and if we adopt a usual notation, and put w, v for the first, and w,, w’, v, for the second differ- ential coefficients of V with respect to « and y; also if n Oy ap no) , 2g (v6,—Uw6,) "U0 =v, — 2vuw’ + wv, and similarly for higher powers, 7.e.,if the operative factor (vé;—wué,)’ is understood to affect U only, precisely as if u, v, &c., were constant ; then it is not difficult to show that— —Dy =u: », — D?y=(ve,—ué,)?U : v, — D%y=(vé,—uéd,)U : vt —3 (ew! — wr) (vd —U6,)°U : v°, — Dty=(vé,—wey)"4U : v? —4(ow! —wr,) (vdz—uéy)U : v8 —3{2v(vd,—uby)’?—5(vw’ —uv,)?—v? (uv, —w”) } (voz —Uby)?U : 07. These are the developments by means of which the reduction would have to be made. 1882.] Effects of Retentiveness in Magnetisation of Iron, Sc. 39 Ill. “On Effects of Retentiveness in the Magnetisation of Iron. and Steel. (Preliminary Notice.)” By J. A. Kwine, B.Sc., F.R.S.E., Professor of Mechanical Engineering in the University of Tokio. Communicated by Professor Sir WiuuiAM THOMSON, F.R.S. Received May 6, 1882. The term Hysteresis was introduced in a paper,* recently communi- ated to the Royal Society, to designate a peculiar action which was observed in the inquiry then recorded, and which had also presented itself in an earlier investigation—of the effects of stress on thermo- electric quality.+ It was found that when a stretched iron wire was gradually loaded and unloaded the changes of thermoelectric quality lagged behind the changes of stress, so that curves exhibiting the relation of stress to thermoelectric quality during the putting on and taking off of the load were far from coincident, but inclosed between them a wide area.t In prosecuting those experiments it occurred to me that there is much room for investigation of hysteresis§ in the changes of mag- netisation of iron and other substances produced by (1) change of the magnetic field; (2) change of stress; (3) change of temperature. In (2) and (3) two cases are to be considered :—First, when the substance is exposed to a constant magnetising force; second, when the magneti- sation which is changed is wholly residual. From the known character of residual magnetism we may at once infer that when magnetisation along any axis 1s changed so con- siderably that its sigu is reversed there must be hysteresis, but it is not clear that any such phenomenon need appear when the action 18 confined to one sign. In fact, Maxwell’s extension of Weber's theory of induced magnetism|| assumes that residual magnetism resembles the “permanent set” of a strained solid, and implies that any sub- sequent application of a magnetising force in the same direction with and not exceeding that by which the residual magnetism has been produced, will give changes of a quasi-elastic character not exhibiting the action which I have called hysteresis. By the direct magnetometric method, and also by the ballistic * “ On the Production of Transient Electric Currents in Iron and Steel Con- ductors by Twisting them when Magnetised, or by Magnetising them when Twisted.” “ Proc. Roy. Soc.,” vol. 33, p. 21. + “ Effects of Stress on the Thermoelectric Quality of Metals. Part I.’”’ “ Proc. Roy. Soce.,” vol. 32, p. 399. ~ Since the paper cited was laid before the Royal Society, I have learnt that M. Emil Cohn has anticipated me in the discovery of this peculiar feature of the effects of stress on thermoelectric quality. (‘‘ Pogg. Ann.,” N.F., VI, 385.) § Or effects of retentiveness—Note by Sir William Thomson, May 5, 1882. || “Treatise on Electricity and Magnetism,”’ II, chapter vi. 40 Prof. J. A. Ewing. On Effects of [May 25,. method (as used by Rowland and others), I have examined at great length the changes of magnetisation which occur in iron and steel’ when the magnetising force is progressively increased, diminished, again increased, reversed, and so on. ‘The results show in the most conclusive manner that all changes of magnetisation produced by slow or fast, continuous or discontinuous, changes of the magnetising force exhibit hysteresis. If we carry the metal through any cycle of magnetisation, the curves giving the relation of I (the intensity of magnetisation) to H (the magnetising force) form loops, and it does not appear that the loops are different in any essential respect (except size) when the action is confined to one sign from the loops given when the sign of the magnetisation is reversed. The remarkable feature of the curves is, that when the magnetisa-. tion of iron is conducted in such a manner as to be uniform throughout the piece experimented on, the initial change which occurs when we: pass from increase to decrease of the magnetising force, or vice versé, is indefinitely small relatively to the initial change of the force. In other words, say that we stop decreasing H and begin to increase it,. then a is at first zero. The difference between the curves for mcrease and decrease of the: magnetic force is of a perfectly static character. If it is to be explained by internal friction, the friction is analogous to that of solids, and does not at all resemble the viscosity of liquids. The. phenomenon here described is independent of the quasi-viscous resist-- ance to changes of magnetisation which is due partly to the induction of currents in neighbourig conductors, including the magnet itself). and partly to the thermomagnetic properties of the metal discussed by Sir W. Thomson (“ Phil. Mag.,” vol. v, 1878, pp. 24-25). The influence of those causes disappears when the changes of magnetisa-- tion take place very slowly, or when a sufficient interval of time is: left after each change of magnetic force before a reading of the magnetisation is taken. When any cyclic change of I is made to take place by varying H. cyclically, the area of the loop so formed, or /IdH, is not only pro- portional to, but actually the measure of the work done on the magnet, per unit of volume, in performing the cycle. In cases where changes of the magnetisation take place very slowly this is wholly spent om the maenet itself, and its equivalent is, no doubt, to be found in the heating effect of the cycle. When, however, the changes of maene- tisation take place at a finite rate, this area must of necessity be greater, since the work done in performing the cycle is then greater for two reasons; first, because of the energy expended in inducing currents in neighbourmg conductors; and, second, because of the dissipation of energy involved in the heating and cooling effects. 1882.] Retentiveness in the Magnetisation of Iron and Steel. 41 which Thomson has shown must occur on account of the fact that the susceptibility to magnetic induction is a function of the tempera- ture. I have endeavoured to account for the static hysteresis by sup- posing that the rotation of Weber’s magnetic molecules is opposed by a frictional couple of constant moment, not necessarily the same for all the molecules in a given piece. It seems not unlikely that residual magnetism itself may be due to this frictional sticking of the molecules rather than to the quasi-plasticity suggested by Maxwell. The ex- amination of this theory, as well as the description of the experiments, some of whose results have been briefly mentioned in this notice, will form the subject of a more detailed communication. Another portion of the work has consisted in looking for hysteresis. in the changes of the longitudinal magnetism of iron wires, produced by pulling and relaxing pull, the wires being under the influence of the vertical component of the earth’s magnetic force, which in Tokio: is about 0°34.C.G.8. unit. Sir W. Thomson* has investigated very extensively the general effects of stress on the magnetisation of iron and other metals, in magnetic fields of various strengths, but without special reference to this point. Only in the case of torsion (alter- nately to opposite sides) is mention made of any action of the kind which I have termed hysteresis. His researches were for the most part conducted by the ballistic method,+ by which the currents in- duced in a solenoid surrounding the wire were observed when a single * “ Hlectrodynamic Qualities of Metals,” “ Phil. Trans.,” 1856, 1876, 1879. + [Note by Sir William Thomson of May 3, 1882.—This is not quite so. The- experiments described in §§ 214—244 of my “ Electrodynamic Qualities of Metals,” Part VII (“ Phil. Trans.” for 1879, p. 55), were performed by the magnetometric method. My earlier experiments described in §§ 178—213 (‘“ Phil. Trans.” for 1876, p. 693, and for 1879) were performed by the ballistic method. The following is taken from a preliminary statement (§ 178) :—‘‘ Early in the- year 1874, I made arrangements to experiment on the magnetisation of iron and steel wires in two different ways—one by observing the deflections of a suspended magnetic needle produced by the magnetisation to be tested, the other by observing the throw of a galvanometer needle, due to the momentary current, induced by each sudden change of magnetism. The second method, which for brevity I shall call the ballistic method, was invented by Weber, and has been used with excellent effect by 'Thalén, Roland, and others. It has great advantages in respect of conve-- nience, and the care with which accurate results may be obtained byit; but it is not adapted to show slow changes of magnetism, and is therefore not fit for certain im- portant parts of the investigation. On this account I am continuing arrangements for carrying out the first method, although hitherto I have obtained no good results. by it.” The first method was accordingly followed in all the latter part of my experi- ments on this subject ; not only those described in §§ 214—244 referred to above, but also in further investigations which I have continued up to the present time,. and of which I hope to offer results to the Royal Society before long. | A2 Prof. J. A. Ewing. On Effects of [May 25, weight was put on and taken off. By making several steps, instead of only one, in the application and removal of the load, the existence of hysteresis may easily be demonstrated by this method ; but I have preferred the direct magnetometric method, which has the immense advantage of exhibiting the actual magnetic state of the stretched wire at any time. Each wire was hung vertically with its upper end on a level with a mirror magnetometer. It was then annealed by heating to bright redness with a spirit-lamp, and after it had become cool, weights were progressively applied. During the earliest part of the first loading certain very interesting apparently anomalous effects occur, which will be described in the detailed account. Apart from these, which are easily distinguished, the following is the normal action :— If to the annealed wire any load not exceeding the elastic limit is ‘successively applied and removed (without shock), its application causes a decrease and its removal an increase of magnetisation. The ‘“‘on”’ and ‘‘ off” curves of stress and magnetism are widely different, and afford an excellent instance of hysteresis. Next, let the wire be stretched beyond its limit of elasticity. The stretching is accompanied by a decrease of magnetisation, which continues so long as the wire keeps “running down.” When the load is removed it is found that a great diminution of magnetisation has taken place; but besides this, the wire has undergone a very remarkable change with respect to its subsequent behaviour under stress. For let weights now be gradually appled: they cause at first an increase* of magnetisation, but this passes a maximum and falls off slightly as that value of the load is approached which previously was applied to produce the permanent set. Let the load then be gradually removed: the magnetisation at first increases, passes a maximum (at a considerably lower value of the load than that which gave the maximum during application), and finally diminishes rapidly to its previous value with no load. These effects will be clearly seen by reference to fig. 1, which shows the results of a small part of one set of observations. The ordinates are proportional to the total magnetisation, and the abscisse are the loads in kilogrammes. In this case the wire was of moderately soft iron, 0°79 millim. in diameter, and had a well-defined limit of elasticity at about 10 kilos. The upper part of the diagram shows the effect of gradually apply- * This agrees with Sir W. Thomson’s observation that with low magnetising forces the effect of “on” is to increase, and “off”? to diminish magnetism. The description of the wire examined by him shows that it was in fact in the state de- scribed in the text. (See ‘ Phil. Trans.,’’ 1879, p. 56.) 1882.] Letentiveness in the Magnetisation of Iron and Steel. 43 ing and removing 7 kilos. before the wire had been stretched at all by any greater load. The lower part shows the effect of applying and removing weights nearly equal in all to 16 kilos. after the wire had been previously stretched by thegsame load. The initial magnetism for zero stress had then fallen to 104, but during application it rose to 174 with 10 kilos., and again during removal it rose to 172 with 64 kilos. 4 6 8 [ LOAD IN -KILOS. The series of experiments from which this figure is taken shows that the maximums of magnetisation during loading and unloading (when conducted without shaking the wire) appear only after some permanent set has been given, and that they gradually shift out to the right as the amount of permanent set is progressively increased. A number of other iron wires tested in the same way agree with this one in giving decrease of magnetism for ‘‘ on,” and increase for “off” before stretching beyond their limits of elasticity, and after- wards increase for ‘‘on” and decrease for “ off.” It appears that (at least when the strain has occurred in the circumstances in which it occurs here) this difference of behaviour forms an unfailing criterion by which we may distinguish a piece which has received permanent set from a piece in the annealed state. A careful examination of the initial parts of the curves which are formed when after loading we change (without mechanical dis- turbance) to unloading, or vice versd, has brought out the fact that, calling I the magnetisation and p the stress, = is always initially P At Effects of Retentiveness in Magnetisation of Iron. [May 25, zero. The magnetic rigidity, as the reciprocal of this differential co- efficient might be called, is infinite at the beginning of any change from loading to unloading, or from unloading to loading, provided that the change takes place withoutsagitation of the wire. in the thermoelectric experiments described in my former paper, the beginning of the new curve generally continued to show the same kind of change as had been going on before. The same peculiarity can be reproduced here if the loading or unloading occurs with a slight vibration of the wire, and I now think it almost certain that its presence in the thermo- electric curves was due toa very small amount of mechanical dis- turbance which accompanied the changes of load. On Oo Oo ine) aS fe)) oO oS oO Se eek ol [o] oO Zz ° k < w) ‘a Ww 7? ug < 2 TOTAL When the wire is vigorously tapped during the loading and un- loading, the ‘‘on”’ and “ off” curves so nearly approach coincidence as to lead to the conclusion that a sufficient amount of vibration would destroy the hysteresis altogether. As an instance of this, the full lines in fig. 2 show the changes undergone by another wire (which 1882. | On Actinometrical Observations made in India. 45 had been permanently stretched) when subjected to the cycle 0—8—3—125—0 without vibration; while the broken line is the position in which the “on” and “‘ off” curves very nearly coincided, when the same main cycle 0—12i3—0 was passed through with the accompaniment of violent vibration. Its maximum lies, as regards load, between the two previous maximums, and the whole range of magnetic change is considerably increased. The hysteresis which occurs in the relation of magnetisation to stress is absolutely static. The value of the magnetism associated with any condition (past and present) of stress is reached at once, and remains unchanged for any length of time, when the load is kept constant. A full account of the experiments will be given when they are more complete. They are being conducted in the Laboratory of the Uni- versity of Tokio, with the valuable help of the senior students of physics. IV. “On Actinometrical Observations made in India at Mus- sooree in Autumn of 1880, and Summer and Autumn of 1881.” By J. B. N. Hennessey, F.R.S., Deputy Superin- tendent Great Trigonometrical Survey of India. Received May 2, 1882. [Prate 1.] 1. My last communication dealt with the actinometrical observa- tions made by Mr. W. H. Cole, M.A., and myself in 1879; I have now the pleasure to submit the observations taken in 1880 by Mr. Cole, and in 1881 by Mr. H. W. Peychers* and myself. The former happen to be few in number, but the latter present the longest series I have ever been able to take, extending as they do over thirty-two days. The 1881 observations were moreover made under certain special con- ditions, which are not without interest. Hitherto the two actino- meters used (belonging to the Royal Society) were both} of the kind invented by the Rev. G. C. Hodgkinson, and marked by me A and B. One of these was employed at Dehra, the other at Mussooree, the observations being taken as nearly as practicable at the same moments of time; but, as the former of these stations cannot be considered free from objections, which I have discussed in previous communications, I determined to restrict future observations to Mussooree alone. This * This being the first occasion of mentioning Mr. Peychers’ name, I add, that as he has worked under me for several years, I can vouch for him as an accurate and painstaking observer. + Both these actinometers are still identical in all respects with their condition when rezeived in 1868. As Mr. J. B. N. Hennessey. [May 25, change, moreover, enabled me to adopt the desirable condition that two observers and instruments, placed side by side, should work with one and the same chronometer between them, so that two independent results might be obtained simultaneously. It was under these condi- tions that the autumn series of observations in 1881 were made ; other- » wise, both the summer and autumn series of 1881, as well as the series of 1880, were taken exactly in keeping with the observations of 1879. The procedure followed in the last-named series is fully described in the ‘‘ Proceedings of the Royal Society,” vol. 31, p. 154, to which I may be permitted to refer, instead of making repetitions here, espe- cially since my leisure is at present limited, so that it had perhaps better be devoted to what follows. 2. Returning to the autumn simultaneous observations of 1881, not only were two actinometers employed side by side, but the two instru- ments were of different patterns. One of them was A (Hodgkinson’s), which has been amply described in my previous communications ; the other instrument was one* of those constructed according to designs by Professor Balfour Stewart. It is marked No. 2, and is supplied with two similar tubes, or thermometers, viz., No. 1806 and No. 1307, both of which read from 0° to 100° F., and are graduated on the glass to degree fifths. Tube 1306 alone was employed; it was readily adapted to give readings for so long a time as thirty consecutive minutes of observation, by casting off sufficient mercury into the pear- shaped receptacle above. This was done once for all before the series was begun, and in fact the surplus mercury is still in the receptacle. Otherwise, particular attention was paid to the settings of the ther- mometer, in rotation and depth, and to those of the lens; the latter was kept scrupulously clean, and was used to its full extent, 7.e., no stops were employed. It will thus be seen that the observations were all strictly differential. The graduations were read as usual with a magnifying-glass; the exposures were of sixty seconds alternately in sun and shade, with thirty seconds’ intervals between, so that the instruments were read both at the beginning and end of each sixty seconds’ exposure, all of which is in keeping with what was done during previous work. In point of observers, Mr. Peychers worked A and I used No. 2. 3. My observations before 1881 were restricted to the autumn, but an opportunity occurred in the summer of 1881, which was utilised so long as it lasted. The results are of an unexpected nature. 4. There is another point to be mentioned. Increased experience has suggested keener discrimination in respect to atmospheric condi- tions, and this has called for some concise mode of indication, which I * For the loan of this instrument I am indebted to the kindness of H. F. Blan- ford, Esq., F.R.S., Meteorological Reporter to the Government of India. 1882. | On Actinometrical Observations made in India. 47 designate ‘‘ day letters.” These I briefly explain hereafter, first reite- rating that I never observe when any visible interpositions exist between the sun and me; and, in fact, what can be the use of measuring solar radiation through a visible varying atmospheric umbrella, such as is represented by cloud, mist, haze, dust, and smoke ? I thought of using a Crookes’ radiometer (happening to possess one) as a pioneer to the actinometer, in order to see if the former would suitably indicate when the latter may be employed to good purpose, but the intention unavoidably fell through. 5. Now, in respect to my day letters, the cases I had to provide for were these: the two visible causes of interposition are cloud Gneluding mist) and haze (including dust, smoke, &c.). First as to cloud :— (1.) The whole visible sky may be perfectly clear, or there may be half-a-dozen small patches here and there, but none within 50° or 60° of the sun; for this state my day letter is A. (2.) But sometimes the condition A required qualifying, because of a peculiar cloud behaviour. The sun being due south, small cloud balls, some 2° to 5° in diameter, appeared on the horizon about north- west, and gradually rolled up and eastwards to some 30° short of the sun, where they became invisible. When the circular track, if continued in imagination, passed well wnder the sun, I indicated this by B. (3.) But if the track passed through the sun, the day letter used is C. 6. Then as regards haze: I stood on the outermost mountain range, south of which lie the plains and to the north successive hill ridges, ending in the perpetual snows. No haze is generated on the hills apparently, but is blown up from below, the wind being southerly as a rule: hence (4.) For no haze south or north I use a. (5.) For haze to south only, b (6.) When the haze is both south and north, I infer that I stand in it though it is invisible overhead ; for this I use c. Hence, by using suitable combinations of these letters, the condition of the sky is fairly indicated symbolically, at least for Mussooree. 7. The present series have been reduced in exactly the same manner as those of 1879 were reduced. The individual results are attached, viz. :— For 1880 eben: October 18th to 27th, in T. 1, by Mr. W. H. Cole, M.A. For 1881 Summer, April 25th to May 9th, TW lov a Et, We Peychers and myself. For 1881 Autumn, October 11th to November 11th, in T. 3, by Mr. H. W. Peychers and myself. In these tables the results of A and B are expressed in terms of A, Ag Mr. J. B. N. Hennessey. | May 209, glass off; for those of No. 2 the unit is 0°01 F., assuming a graduation of No. 2 to be 0°2 F. 8. It needs but little familiarity with the two kinds of instruments to decide in favour of that by Professor Balfour Stewart over that by the Rev. G. C. Hodgkinson, a preference which may be greatly in- creased by doubling the sensitiveness of the former. I have accord- ingly converted all my results beginning with 1869, and expressed them in terms of Stewart’s No. 2, or 0°:01 F., which unit is to be understood 7m all that now follows. 9. Again, as the average zenith of distance of the sun durmg my autumn series does not differ greatly one year with another, and as suitable corrections to an adopted zenith distance may be inferred from the long range series (i.e., three or four hours on each side of the meridian) taken at the same season of the year, I have reduced all my autumn results to the zenith distance of 45°. 10. The long range series used are given in T. 4, where it will be seen that the series with A in 1881 is inconsistent, so that I have rejected it. It appears a waste of time to attempt formulating at present the correction from one Z.D. to another; I made several endeavours of the kind with the long series of T. 4, but feeling that the expressions were more pretentious than real, I resorted to the projection shown in the correction Curve C 1: here it will be seen that the two curves, 7.e., of 1879 and 1881, are fairly sdmar, and as the series of 1881 was taken at half-hour intervals instead of the one- hour intervals of 1879, the correction curve I have adopted is made to agree more nearly with the later series. All the reductions to 45° Z.D. have been made with the help of C 1. ll. From T. 4, long series, rejecting the results of A, 1881, we have — | App. time. Defect from noon. h. 1879. 1881. Sith ove yehe Seekers 115 SUES Ne) chy a oot 5 ADS gy rhais- 4 Geen 39 bal OMe en re ei es: 26 1 Oni aie a eRe eRe LO sie a ee 15 10, 039. pee eed lage 5 8 6 oS eee algerie 2s a 6) yA een Dae 4 AL oh nat arate cia HS Tapa Paresh Su thet 6 LO Wok Re) Ae Ree = 0) ou amersibeye manera Gree ce mk Diab ss. alain ois ae BOS Siege aha tah ee cee 18 UL ORME ERPS URE i ico An Deas Seek RMN 29 CO a? RPE see OD i cuats eee D0 ASAIN, GAM haere a dNrte ae 127 where the 1879 series is hourly, and from 8 a.m. to 4 p.m., while the On Actinometrical Observations made in India. i see oe Ht i = “ + 2 GF SACP lUo2z7 IPA SL “ 4 z a “FI . 1B = A aAVuaLGal7 | Zoi0 ae of chanve| t Origin of S Projection VOT). XXXTYV. 50 Mr. J. B. N. Hennessey. _ [May 20, 1881 series is half-hourly, and from 9 a.M.to3 p.m. Taking sums of the defects at the common hourly points, 9h. to 3h., we have— 1879. 1881. Defect pefore Moon, ON—'JzZ 9. OF 966 €- [TF 096 0. 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LE IL “490 Ses ee = es | Ee poe | ee S| a ef i ee PR Pane | [Preis S S 2 oby Sli menoae lroetell: aes F ‘qynq | JOM | “SI | HT cB |'S"ON| “VV "u00u “m00U “m00u “u00u Ne ‘Ss Ss 5° e A 8 eel oon sting ee ‘es Le ai 04 "IOV |'oy | loayy a.lojog RGubatg ILOJOY 5 fe 2 ‘royet JOLY [ea ss Vv ‘unsur| ‘opeys ur jPeNnpet Fy Ny Avg Pee ai 8 son | "(9061 9qn3) "Vy dojatouno But BS a cy wa se eee @ ‘ON * TOJOTLOULLATT, “OLVE | -uoou aye | Z ON dogououNoOy Water Helv, a ‘I8SI S Senne puv atozoq | ————— BS "(Gh JB UWOTVIPRA poqoo1.109 penped ‘mOOU 4V JO UBOT “MOY-Lo}LeNh Lof UOTVIpel UvoT 8 ®, “IS8T UUNyNny ‘oor1oossnyt 1V ‘oGP ‘CZ OF pooupot puv “7 TO..0 = Jruu Z ‘ON Jo suite, ut possordxo ‘Z ‘ON 8.jaRMo4G puv ‘Vy S,Wosurycpop]—siojoumouljoVy OA\y TATA ATSHOoURZ;MUTIS posdOsqo sq[usor A[LBp Jo youlsSayY—'TITA eg, 1882.1 60 | Mr. J. B. N. Hennessey. [May 25, October 11.—Wind in low puffs from S. Air and sky beautifully clear, except occasional small patches of c.c. which kept rising to W., and floating up to some 30° of sun, when they became invisible and could no longer be followed. October 12.—As on 11th; except that the small patches of c.c. passed along a track some 8° to 20° below sun. October 14.—A very favourable day. Light wind from 8. Not even a speck of cloud visible ; light haze towards plains S., and also slightly visible by dimming hills to N. October 15.—A very favourable day and exactly like 14th, with one exception, z.e., small light c.c. floated up from W. in a course passing some 15° to 25° below sun and disappeared when some 30° W. of sun. Wind S., at first very low, later on in somewhat fresh puffs. October 16.—A very favourable day, except that c.c. (from very small up to 10° in diameter) kept passing at intervals in a track 10° to 20° below sun. Haze over plains more than yesterday, but no increase up here. October 17.—A very still day, very clear, but small c.c. keep occasionally floating W. to E. in track about passing through sun ; invisible near sun. Haze over plains rather increased since yesterday ; haze is not visible overhead. October 18.—Sky clear but for small c.c. floating about and disappearing 15° to 40° frum sun ; haze over plains increased. Hills some 30 miles to S. just visible ; to N. view fine and clear. Wind S., in gusts but not strong. it is impossible to say how far, if at all, the clouds interfered. October 19.—Sky beautifully blue and clear, but observation spoiled by a few patches of c.c. floating W. to E. across sun from time to time. Haze to S. over plains. A thunderstorm to N. last evening. Wind 8. and low. October 20.—A very fine day marred by not more than half-a-dozen c.c. floating about, some of which interposed. Sky otherwise blue and clear. All doubtful ob- servations rejected. Wind in rather fresh gusts and southerly. Observations rejected when c.c. visibly interposed. October 22.—A most brilliant day. Sky blue and without cloud or haze. Wind S. and rather fresh. October 24.—Sky beautifully clear, except half-a-dozen small streaks of cir-strati about 10° above S. horizon, far from ©. Wind S. and sometimes in gusts, other- wise day highly favourable. October 25.—Day beautifully fine. Wind S. and in gusts low and fresh. October 26.—Day beautifully fine: two or three (only) small patches of es. moving W. to E. some 25° below sun. Wind S. and in rather strong gusts. October 28.—To-day is peculiar. Strati and cumuli run along horizon for some 10° height from S. by E. and N. to S.E., besides a few small cirri to N. some 60° from sun ; and in addition a few small c.c. kept floating up from W. to some 26° of sun (in track which would pass say 15° to 20° under sun) and then disappeared. Wind 8. and in rather fresh gusts. No visible clouds approached the sun. Sky generally blue and bright. October 29.—Sky deep blue, for about 10° below to 7° above sun. A little haze to 8. over plains, c.c. along horizon from S.E.to N.W. A most perfect day for observations. October 30.—Day beautifully fine. Nota speck of cloud except some cumuli on the snows (N) up to some 4° altitude only. Wind S. and occasionally in fresh gusts. Haze (smoke, vapour, and dust) over plains to S., but hills to N. quite clear. Weight for day 1:0. October 31.—Day beautifully fine, as nearly as possible like yesterday (30th), except wind slightly stronger and haze over plain slightly increased. 1882.] On Actinometrical Observations made in India. Sarl November 1.—Day beautifully fine, ike yesterday ; wind as high, /.e., in fresh gusts, from S. Clouds over snows, and one or two small patches floated a little way upward and disappeared some 60° or 80° from sun. Haze over plains increased slightiy from smoke. November 2.—Beautifully clear, not a cloud anywhere except a very few small ones over the snows. November 3.—Beautifully clear day, perhaps the clearest we have had. Wind 8. and in gusts of greater strength than usual. November 4.—Day beautifully clear in respect to cloud, of which there is a narrow (1°) belt of c.s. some 8° above horizon to S. But as regards haze, this has been increasing (chiefly from smoke) over the plains, and to-day this haze is very slightly perceptible N.E. and W. as well. November 5, 9.0.—Beautifully clear, not a speck of cloud, no wind. Over plains a good deal of haze (smoke), which is slightly visible against distant hills to N. (also H. and W.), so that we are in it. 9.30.—Just as at 9 a.M., except wind rising. 10.0.—As before, wind rising. Good series. 10.30.— Not a speck of cloud, as before. 11.0.—As before. Not aspeck of cloud. Wind rising. Noon.—A highly favourable day excepting the thin smoky haze in which we are imperceptibly enveloped—imperceptibly, 7.e., it does not appear between us and the sun, but it is quite visible over the plains (S.), and appears slightly against distant hills (15 to 50 miles) N.W. and E. Wind in low gusts. 1.0.—Fine, as before. 1.30.—Fine, as before. 2.0.—Fine, as before. 2.30.—Fine, as before. (Observer uncomfortably placed.) 3.0.—Fine, as before. November 6.—Day beautifully clear, except slight (smoke) haze, which is as yesterday or perhaps a trifle less. Wind S. Observations good. November 7.—Day beautifully clear. Smoke haze below to S., but hardly, if at all, visible against hills to N., slightly visible E. and W. Wind S. and low. November 8.—Day beautifully clear now, but up to 8 or 9 a.m. fine strati were over southern sky. Wind S. and low. November 9.—Day beautifully clear, except the smoke haze, which may be a trifle less than yesterday to S.E., S., and N.W. November 10.—Day beautifully fine, and sky blue and clear some 50° around sun. Smoke haze more and we are slightly in it. A very few small patches of c.c. floating about, some perhaps in sun’s track (EH. to W.), others about 25° below sun. Wind S. and in rather strong gusts. November 11.—Day beautifully fine; compared with yesterday there are more small patches of c.c. floating about, but not in tracks leading through sun ; and the nearest disappearance of a patch was not under 25° from sun: there is also more smoke haze, and it is visible all round along horizon, so that we are in it, though it is quite invisible above. Wind S8.E. 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Roy (Ne MSOCHVOULO4 Led . ; = | i ube las = = sie + + Ane i Vi. | NS es oS va ra ee 41879 i ‘es | Autumn - —} (Hodgk mson) | | , Ban ( Stewart) sil ou mora & IES Penumbrx or P ae enumbra or(U+P) curve | Measured from Solar | eqgarives jtaken at Dehra Duin 1887. nit = 40000000 square mules. or U \curve - 14. its 16 wi 18 ne) x : Bato) FET] West Newman & CY Iith Pike - > ‘eorrespondin 71879 Autumn 1879 Audion Kose SS \dt869- Aud xe ss, With Actinometer (Hodgky sen) } he. ( Stewart) J ee — ~ — — Area of Umbra & Penumb or( U4P) carve ut Aree of Penambra or P durve Measured trom Solow Negatives taken at Deliva Du 1881. nit we 40, 000000 dyucre nites oes Be Umbra) or U leurve . is : — i e -) #08 2 ee Weot Newman & 0° [ith 3 1882.] On the Cause of the Light Border in Photographs, §c. 63 VY. “On the Cause of the Light Border frequently noticed in Photographs just outside the Outline of a Dark Body seen against the Sky; with some Introductory Remarks on Phosphorescence.” By Professor G. G. STOKES, Sec. R.S. Received May 20, 1882. An observation I made the other day with solar phosphori, though not involving anything new in principle, suggested to me an explana- tion of the above phenomenon which seems to me very likely to be the true one. On imquiring from Captain Abney whether it had already been explained, he wrote: “ The usual explanation of the phe- nomenon you describe is that the silver solution on the part of the plate on which the dark objects fall has nowhere to deposit, and hence the metallic silver is deposited to the nearest part strongly acted upon by light.”’ As this explanation seems to me to involve some difficul- ties, I venture to offer another. 1. I will first mention the suggestive experiment, which is not wholly uninteresting on its own account, as affording a pretty illus- tration of what is already known, and furnishing an easy and rapid mode of determining in a rough way the character of the absorption of media for rays of low refrangibility. The sun’s light is reflected horizontally into a darkened room, and passed through a lens,* of considerable aperture for its focal length. A phosphorus is taken, suppose sulphide of calcium giving out a deep blue lght,; and a position chosen for it which may be varied at pleasure, but which I will suppose to be nearer to the lens than its principal focus, at a place where a section of the pencil passing through the lens by a plane perpendicular to its axis shows the caustic surface well developed. A screen is then placed to intercept the pencil passing threugh the lens, and the phosphorus is exposed to sunlight or diffuse daylight, so as to be uniformly luminous, and is then placed in position; the screen is then removed for a very short time and then replaced, and the effect on the phosphorus is observed. | Under the circumstances described there is seen a circular disk of blue light, much brighter than the general ground, where the excite- ment of the phosphorus has been refreshed. This is separated by a dark halo from the general ground, which shines by virtue of the * The lens actually used was one of crown.glass which I happened to have; a lens of flint glass would have been better, as giving more separation of the caustic surfaces for the different colours. + The experiments were actually made, partly with a tablet painted with Bal- main’s luminous paint, partly with sulphide of calcium and other phosphori in powder. 64 Prof. G. G. Stokes. [May 25, original excitement, not having been touched by the rays which came through the lens. 2. The halo is due to the action of the less refrangible rays, which, as is well known, discharge the phosphorescence. Their first effect, as is also known, is however to cause the phosphorus to give out light; and if the exposure were very brief, or else the intensity of the discharging rays were sufficiently reduced, the part where they acted was seen to glow with a greenish light, which faded much more rapidly than the deep blue, so that after a short time it became relatively dark. 3. This change of colour of the phosphorescent light can hardly fail to have been noticed, but I have not seen mention of it. In this respect the effect of the admission of the discharging rays is quite different from that of warming the phosphorus, which as is known causes the phosphorus to be brighter for a time, and then to cease phosphorescing till it is excited afresh. The difference is one which it seems important to bear in mind in relation to theory. Warming the phosphorus seems to set the molecules more free to execute vibrations of the same character as those produced by the action of the rays of high refrangibility. But the action of the discharging rays changes the character of the molecular vibrations, converting them into others having on the whole a lower refrangibility, and being much less lasting. 4, Accordingly when the phosphorus is acted on simultaneously by fight containing rays of various refrangibilities, the tint of the result- ing phosphorescence, and its more or less lasting character, depend materially on the proportion between the exciting and discharging rays emanating from the source of hght. Thus daylight gives a bluer and more lasting phosphorescence than gaslight or lamplight. I took a tablet which had been exposed to the evening light, and had got rather faint, and, covering half of it with a book, I exposed the other half to gaslight. On carrying it into the dark, the freshly exposed half was seen to be much the brighter, the light bemg, however, whitish, but after some considerable time the unexposed half was the brighter of the two. Again, on exposing a tablet, in one part covered with a glass vessel containing a solution of ammonio-sulphate of copper, to the radiation from a gas flame, the covered part was seen to be decidedly bluer than the rest, the phosphorescence of which was whitish. ‘The former part, usually brighter at first than the rest, was sure to be so after a very little time. The reason of this is plain after what precedes. A solution of chromate of potash is particularly well suited for a ray filter when the object is to discharge the phosphorescence of sulphide of calcium. While it stops the exciting rays it is transparent for nearly the whole of the discharging rays. The phosphorescence is 1882.] On the Cause of the Light Border in Photographs, §¢. 69 accordingly a good deal more quickly discharged under such a solution than under red glass, which along with the exciting rays absorbs also a much larger proportion than the chromate of the discharging rays. 5. I will mention only one instance of the application of this arrangement to the study of absorption. On placing before excited sulphide of calcium a plate of ebonite given me by Mr. Preece asa specimen of the transparent kind for certain rays of low refrangibility, and then removing the intercepting screen from the lens, the trans- mission of a radiation through the ebonite was immediately shown by the production of the greenish light above-mentioned. Of course; after a sufficient time the part acted on became dark. 6. I will mention two more observations as leading on to the expla- nation of the photographic phenomenon which I have to suggest. Inadark room, an image of the flame of a paraffin lamp was thrown by a lens on to a phosphorescent tablet. On intercepting the incident rays alter no great exposure of the tablet, the place of the image was naturally seen to be luminous, with a bluish light. On forming in a similar manner an image of an aperture in the window shutter, illuminated by the light of an overcast sky reflected horizontally by a looking-glass outside, this image of course was luminous; it was brighter than the other. On now allowing both lights to act simul- taneously on the tablet, the image of the flame being arranged to fall in the middle of the larger image of the aperture, and after a suitable exposure cutting off both lights simultaneously, the place of the image of the aperture on which the image of the lamp had fallen was seen to be Jess luminous than the remainder, which had been excitea by daylight alone. The reason is plain. The proportion of rays of lower to rays of higher refrangibility is much greater in lamplight than in the light of the sky; so that the addition of the lamplight did more harm by the action of the discharging rays which it con- tained on the phosphorescence produced by the daylight, than it could do good by its own contribution to the phosphorescence. 7. The other-observation was as follows :—The same tablet was laid horizontally on a lawn on a bright day towards evening, when the sun was moderately low, and a pole was stuck in the grass in front of it, so as to cast a shadow on the tablet. After a brief exposure the tablet was covered with a dark cloth, and carried into a dark room for examination. It was found that the place of the shadow was brighter than the general ground, and alsu a deeper blue. For a short distance on both sides of the shadow the phosphorescence was a little feebler than at a greater distance. This shows that, though the direct rays of the sun by themselves alone would have strongly excited the phosphorus, yet acting along VOL. XXXIIT. F 66 Prof. G. G. Stokes. [May 25, with the diffused light from all parts of the sky, they did more harm than good. They behaved, in fact, like the rays from the lamp in the experiment of § 6. The slightly inferior luminosity of the parts to some little distance on both sides of that on which the shadow fell, shows that the loss of the diffuse light corresponding to the portion of the sky cut off by the pole was quite sensible when that portion lay very near the sun. All this falls in very well with what we know of the nature of the direct sunlight and the light from the sky. In passing through the atmosphere, the direct rays of the sun get obstructed by very minute particles of dust, globules of water forming a haze too tenuous to be noticed, &c. The veil is virtually coarser for blue than for red light, so that in the unimpeded light the proportion of the rays of low to those of high refrangibility goes on continually increasing, the effect by the time the rays reach the earth increasing as the sun gets lower, and has accordingly a greater stretch of air to get through. Of the light falling upon the obstructing particles, a portion might be absorbed in the case of particles of very opaque substances, but usually there would be little loss this way, and the greater part would be diffused by reflection and diffraction. This diffused light, in which there is a predominance of the rays of higher refrangibility, would naturally be strongest in directions not very far from that of the direct light; and the loss accordingly of a portion of it where it is strongest, in conse- quence of interception by the pole in front of the tablet, accounts for the fact that the borders of the place of the shadow were seen to be a little less luminous than the parts at a distance. 8. The observations on phosphorescence just described have now prepared the way for the explanation I have to suggest of the photo- graphic phenomenon. It is known that, with certain preparations, if a plate be exposed for a very short time to diffuse daylight, and be then exposed to a pure spectrum in a dark room, on subsequently developing the image it 1s found that while the more refrangible rays have acted positively, that is, in the manner of hght in general, a certain portion of the less refrangible have acted in an opposite way, having undone the action of the diffuse daylight to which the plate was exposed in the first instance. It appears then that in photography, as in phosphorescence, there may in certain cases be an antagonistic action between the more and less refrangible rays, so that it stands to reason that the withdrawal of the latter might promote the effect of the former. Now the objective of a photographic camera is ordinarily chemically corrected; that is to say, the minimum focal length is made to lie, not in the brightest part of the spectrum, as in a telescope, but in the part which has strongest chemical action. What this is, depends 1882.] On the Cause of the Light Border in Photographs, §¢. 64% more or less on the particular substance acted on; but taking the preparations most usually employed, it may be said to lie about the indigo or violet. Such an objective would be much under-corrected for the red, which accordingly would be much out of focus, and the ultra-red still more so. When such a camera is directed to a uniform bright object, such as a portion of overcast sky, the proportion of the rays of different refrangibilities to one another is just the same as if all the colours were in focus together; but it is otherwise near the edge of a dark object on a light ground. As regards the rays in focus, there 1s a sharp transition from light to dark; but as regards rays out of focus, the transition from light to dark though rapid is continuous. It 1s, of course, more nearly abrupt the more nearly the rays are in focus. Just at the outline of the object there would be half illumination as regards the rays out of focus. On receding from the outline on the bright side, the illumination would go on increasing, until on getting to a distance equal to the radius of the circle of diffusion (from being out of focus) of the particular colour under consideration the full intensity would be reached. Suppose, now, that on the sensitive plate the rays of low refrangibility tend to oppose the action of those of high refrangibility, or say act negatively, then just outside the outline the active rays, being sharply in focus, are in full force, but _ the negative rays have not yet acquired their full intensity. At an equal distance from the outline on the dark side the positive rays are absent, and the negative rays have nothing to oppose, and therefore simply do nothing. 9. I am well aware that this explanation has need of being con- fronted with experiment. But not being myself used to photographic manipulation, I was unwilling to spend time in attempting to do what could so much better be done by others. I will, therefore, merely in- dicate briefly what the theory would lead us to expect. We might expect, therefore, that the formation of the fringe of extra brightness would depend :— (1.) Very materialiy upon the chemical preparation employed. Those which most strongly exhibit the negative effect on exposure to a spectrum after a brief exposure to diffuse light might be expected to show it the most strongly. (2.) Upon the character of the light. If the light of the bright ground be somewhat yellowish, indicating a deficiency in the more refrangible rays, the antagonistic effect would seem likely to be more strongly developed, and, therefore, the phenomenon might be expected to be more pronounced. (3.) To a certain extent on the correction of the objective of the camera. An objective which was strictly chemically corrected might be expected to show the effect better than one in which the chemical i 68 Cause of the Light Border in Photographs, § ce. [May 25, and optical foci were made to coincide, and much better than one which was corrected for the visual rays. It is needless to say that on any theory the light must not be too bright or the exposure too long; for we cannot have the exhibition (an the positive) of a brighter border to a ground which is white already. P.S.—Before presenting the above paper to the Royal Society I submitted it to Captain Abney, as one of the highest authorities in scientific photography, asking whether he knew of anything to dis- prove the suggested explanation. He replied that he thought the explanation a possible one, encouraged me to present the paper, and kindly expressed the intention of submitting the question to the test of experiment. I have referred to the photographic action of the more and less re- frangible rays as antagonistic. This is practically true so far as the explanation I have ventured to offer is concerned, inasmuch as the more refrangible rays convert a salt -of silver which is not developed into one which is developable, while the less refrangible convert the latter into one which is not developable. But Captaim Abney has pointed out to me that though the first and third salts cannot be dis- tinguished by appearance, nor by the action of the developing solution, they are nevertheless not the same, so that the two actions of the rays are not, rigorously speaking, antagonistic, inasmuch as the one is not strictly the reverse of the other. Thus with bromide of silver the explanation of the observed phenomena, according to Captain Abney, is that the undevelopable bromide is converted, chiefly by the action of the more refrangible rays, into a subbromide, which is developable ; and this again is converted, chiefly by the action of the less refrangible rays, into an oxybromide, which is undevelopable. As however under the ordinary circumstances for obtaining a good picture the action of the light is chiefly of the first kind, and a much longer exposure would be required to bring out prominently the second kind of action, the explanation I have suggested is not virtually affected, though the two actions could not be prolonged indefinitely, as in the illustrative expe- riment in phosphorescence described in § 6. June 10. The Society adjourned over the Whitsuntide Recess to Thursday, June 15th. 1882.] Election of Fellows. 69 June 8, 1882. The Annual Meeting for the Election of Fellows was held this day. THE PRESIDENT in the Chair. The Statutes relating to the election of Fellows having been read, Professor Francois de Chaumont and the Rev. R. Harley were, with the consent of the Society, nominated Scrutators to assist the Secretaries in examining the lists. 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Danske Videnskabernes Selskab. Oversigt. 1881, No. 3: 1882, No. 1. 8vo. Kjébenhavn. Mémoires. 6e Série. Vol. I. No. 5. 4to. Ajdbenhavn 1881. The Society. Halle: — Naturwissenchaftlicher Verein. Zeitschrift fur die Gesammten Naturwissenchaften. 3e Folge. Band VI. 8vo. Berlin 1881. The Union. Huddersfield :—Yorkshire Naturalists’ Union. The Naturalist. Vol VIL. Nos. 74-82. 8vo. Huddersfield. The Union. Kolozsvar :—Erdélyi Muzeum-egylet. Erdélyi Muzeum. Evfolyam VIII. sz. 6-10: Evfolyam IX. sz. 1, 2. 8vo. Orvos-termé- szettudomanyi Ertisito. Evfolyam VI. 1-3. The Society. Leipzig :—Fiirstlich Jablonowski’sche Gesellschaft. Preisschrift. No. 23. 8vo. Leipzig 1882. Jahresbericht, 1882. 8vo. The Society. London:—British Association for the Advancement of Science. Report, 1881. (York). 8vo. London 1882. The Association. British Museum. Catalogue of the Fossil Feraminifera. 8vo. London 1882. The Museum. Chemical Society. Journal. Nos. 229-234 and Supplementary Number. 8vo.. London. The Society. Photographic Society. Journal and Transactions. New Series. Vol. VI. Nos. 5-7. List of Members. 1882. 8vo. The Society. Royal Agricultural Society. Journal. 2nd Series. Vol. XVIII. Part 1. 8vo. London 1882. The Society. 1882. ] Presents. 17 Transactions (continued). Royal Astronomical Society. Monthly Notices. Vol. XLII. No. 6. Svo. The Society. Royal Institute of British Architects. Proceedings. Nos. 5-14. Ato. London 1881-2. The Institute. Royal Institution. Weekly Evening Meetings. Jan. 20, Apr. 28, and May 138, 1882. 8vo. The Institution. Royal United Service Institution. Journal. Vol. XXVI. No. 114. 8vo. London 1882. The Institution. Society of Arts. Journal. Vol. XXX. Nos. 1520-1539. 8vo. London 1882. The Society. Society of Chemical Industry. Journal. Vol.I. Nos. 3, 4. 4to. The Society. Manchester :—Geological Society. Transactions. Vol. XVI. Parts 6-13. 8vo. Manchester 1881-2. The Society. Munich:—K. B. Akademie der Wissenschaften. Abhandlungen. Phil.-Phii. Classe. Band XVI. Abth 2. Hist. ‘Classe. Band XVI. Abth1. Gedichtnissrede auf Otto Hesse. 4to. Miin- chen 1881-2.. The Academy. Naples :—Zoologische Station. Mittheilungen. Band III. Heft 3. 8vo. Leipzig 1882. The Station. Newcastle-upon-Tyne :—Chemical Society. Vol. V. Part 9. 8vo. The Society. New York:— Academy of Natural Sciences. Annals. Vol. I. No. 14. Vol. II. Nos. 1-6. 8vo. New York 1880-81. Annals of the Lyceum. Vol. VII. 8vo. New York 1862. The Academy. Paris :—Académie des Sciences de l'Institut. Comptes Rendus. Tome XCIII. Tables. Tome XCIV. Nos. 1-20. 4to. Paris 1882. The Academy. Ecole Normale Supérieure. Annales. 2me Série. Tome XI. Nos. 1, 2. 4to. Paris 1882. The School. Société d’Encouragement pour |’Industrie Nationale. Bulletin. 3e Série. Tome VIII. Nos. 95,96. Tome IX. Nos. 98, 99. Ato. Paris 1881-82. Compte rendu. 1881, No. 19: 1882, Nos. 1-8. 8vo. The Society. Société Frangaise de Physique. Séances. Septembre—Décembre, 1881. 8vo. Paris 1881. Résumés des Communications. 8vo. The Society. Penzance :—Royal Geological Society of Cornwall. Transactions. Vol. X. Part 4. Svo. Penzance. The Society. Philadeiphia :—Franklin Institute. Journal. Vol. CXIII. Nos. 676-7. 8vo. Philadelphia 1882. The Institute. Rome :—R. Accademia dei Lincei. Transunti. Series 3a. Vol. VI, Fase. 9-11. 4to. Roma 1882. The Academy. 78 Presents. — [May 25, Transactions (continued). , Shanghai: — North-China Branch of the Royal Asiatic Society. Journal. Vol. I. No. 3. Vol. II. No. 1. New Series. Nos. 9, 12. 8vo. Shanghai 1859-78. The Society. Turin :—R. Accademia delle Scienze. Atti. Vol. XVII. Disp. 3. Svo. Torino. The Academy. Utrecht :—Utrechtsche Hoogeschool. Onderzoekingen gedaan in het Physiologisch Laboratorium. 3de Reeks. VII. Afi l. 8vo. Utrecht 1882. Dr. Donders, For. Mem. R.S. Vienna :—Osterreichische Gesellschaft fiir Meteorologie. Janner- Mai, 1882. 8vo. Wien 1882. The Society. Observations and Reports. Calcutta :—Office of the Inspector-General of Forests. Sugges- tions regarding Forest Administration in the North-Western Provinces and Ondh. folio. Calcutta 1882. Dr. Brandis, F.R.S. Meteorological Office. Registers of Original Observations, re- duced and corrected. Results of Autographic Registration, 1880. Observations. March-June, 1881. 4to. R. H. Scott, F.R.S. Colaba :—Observatory. Report on the Condition and Proceedings of the Government Observatory. 1880-81. folio. The Observatory. Dublin :—General Register Office. Weekly Return of Births and Deaths. Vol. XIX. Nos. 1-19. Quarterly Return and Quar- terly Summary, 188]. 4th Quarter. Yearly Return, 1881. 8vo. The Registrar-General for Ireland. Duan Heht:— Lord Crawford’s Observatory. Circulars. Nos. 45-51. Ato. The Earl of Crawford and Balcarres, F.R.S. London :—House of Commons. Copy of Correspondence... . . respecting the Arrangements to be made for Observing the Transits of Venus, which will take place in the Years 1874 and 1882. folio. 1869. The Speaker. Melbourne :—Department of Mines. Reports of the Mining Sur- veyors and Registrars. Sept. 30, 1881. 4to. Melbourne. The Department. Observatory. Report of the Board of Visitors. 1881. 4to. Mel- bourne. The Observatory. Office of the Government Statist. Statistical Register for 1880. Parts 3-7. 4to. Melbourne. The Government Statist. Paris :—Observatoire. Rapport sur l’état de l’Observatoire, 1881. Ato. Paris 1882. The Observatory. 1882. ] Presents. 79 Observations, &c. (continued). Rome :—Pontificia Universita Gregoriana. Bulletino Meteorologico. Mol XD Nos. 16. -b Voli XX. No. I. Vol. XXII. Nos. 1, 2. Ato. Roma 1880-82. The College. Sydney :—Department of Mines. Geological Sketch Map of New South Wales. Compiled from the Original Map of the late Rev. W. B. Clarke, F.R.S. Four sheets. The Department. 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Vol. XXXV. Nos. 4,5. 8vo. New York 1882. The Editor. Scientific Roll. Vol. I, Nos. 4-7. 8vo. London. The Editor. Van Nostrand’s Engineering Magazine. Vol. XXVI, Nos. 1-5. 8vo. New York 1882. The Editor. Balfour (J. H.), F.R.S. Obituary Notices of Sir Robert Christison, Bart., and Sir C. Wyville Thomson. 8vo. Hdinburgh 1882. The Author. Brongniart (Charles) Sur des pucerons attaqués par un champignon. 4to. Paris. Sur la Structure des Oothéques des Mantes et sur Véclosion et la premiere mue des larves. 4to. Paris. Les Hyménopteres Fossiles. 8vo. Paris 1881. Note sur les Tufs 80 Presents. [May 25, quaternaires de Bernouville. 8vo. Meulan 1880. Observations sur la Clepsine. 8vo. Rennes. The Author, per Dr. H. Woodward, F.R.S. Foster (C. Le Neve) On the Occurrence of Cobalt Ore in Flintshire. 8vo. The Author. Lubbock (Sir John), Bart., F.R.S. Ants, Bees, and Wasps. 8vo. London 1882. Montigny (Ch.) Nouvelles Observations sur les Effets de la Foudre sur des Arbres placés pres d’un Fil Télégraphique. 8vo. Bruzelles 1882. The Author. Packard (A. 8.), Jun. Is Limulus an Arachnid ? 8vo. The Author. Plateau (J.) Sur des Sensations que |’Auteur éprouve dans les Yeux. Svo. Bruzelles. The Author. ~ Purves (J. C.) Sur ia Délimitation et la Constitution de l’Etage Houiller Inférieur de la Belgique. 8vo. Bruzelles 1881. The Author Schieboldt (F. 0.) De Imaginatione Disquisitio ex Aristotelis Libris repetita. 8vo. Lipsie 1882. The Author. Schrauf (A.) Paragenetische Studien im Serpentingebiete des siid- lichen BOhmerwaldes. 8vo. Leipzig 1882. The Author. Von Mueller (Baron F.) EHucalyptographia. Decades VI and VILI. Ato. Melbourne 1880. The Author. Wolf (Dr. Rudolph) Astronomische Mittheilungen. LV. 8vo. The Author. 1882. | On Spectrum Photography. 81 June 15, 1882. THE PRESIDENT in the Chair. The Presents received were laid on the table, and thanks ordered for them. Mr. Gabriel Auguste Daubrée (Foreign Member), Dr. George Stewardson Brady, Dr. George Buchanan, Mr. Francis Darwin, Pro- fessor William Dittmar, Dr. Walter Holbrook Gaskell, Mr. William Davidson Niven, and Mr. Robert Henry Inglis Palgrave were admitted into the Society. The President read a despatch from H.M. Consul-General at Florence, transmitted through the Foreign Office, giving an account of a commemoration in honour of the late Charles Darwin, held in the great hall of the Istituto di Studi Superiori. A preliminary (oral) Statement of Results of observation of the total Eclipse of the Sun on May 17, as seen in Egypt, was made by Mr. J. N. Lockyer, F.R.S. The following Papers were read :— I. “Researches on Spectrum Photography in relation to New Methods of Quantitative Chemical Analysis.” By W. N. HARTLEY, F.R.S.E., &., Professor of Chemistry, Royal College of Science, Dublin. Communicated by Professor G. G. STOKES, Sec. R.S. Received May 19, 1882. Preliminary Note. (1.) Since I perfected the instrument employed by me in investi- gating the molecular structure of organic compounds, I have been engaged in studying the spark spectra of elementary bodies with the object of applying my method of working to the purposes of technical chemical analysis. Progress in the course of this research has proved it to be necessary to investigate all kinds of spectra de novo in the hitherto little explored ultra-violet region. Some fourteen years’ practice in photography has convinced me that when a plate is properly exposed the development of the image is the simplest of all operations; in order, therefore, to simplify spec- troscopic work, I have carefully ascertained the time of exposure required to produce the most characteristic spectra under various VOL. XXXIV. G 82 Prof. W. N. Hartley. [June 15, conditions, such as intensity of spark and conductivity, &c., of the electrodes. This, in the instrument I prefer to use, is generally a period of half a minute. (‘Journal of the Chem. Soc.,” vol. xli, p. 84, 1882.) (2.) A long series of experiments has been made with the object of comparing the spectra of various compounds in solution with those of the elements they contain. In the process of photographing the spectra of solutions it is desirable to eliminate all foreign lines as far as possible, hence the selection of suitable electrodes was a matter of the first consideration, the method of working being almost entirely dependent on this for its accuracy and value. No method like that of Bunsen is convenient, in which charcoal points are employed in conjunction with a spark from a coil without a condenser, by reason of the prolonged exposure rendered necessary, the intensity of the emitted rays being small. LHlectrodes of gold, platinum, iridium, and other metals were used, and those of gold proved decidedly the best, as containing the fewest lines and the metal being a most excellent conductor of electricity. All these metals are, however, useless compared with electrodes of graphite. The spectrum of graphite consists of eleven or twelve in- significant lines due to the carbon, and about sixty-six lines and bands due to air. . The air-lines are easily recognised from their “‘ physiognomie,” as M. Lecog de Boisbaudran calls it, or as I have elsewhere described this peculiarity in relation to spectrum photographs, their ‘‘ graphic character.” Inno case with the intensity of spark which I employ and the normal exposure have I ever been troubled with the presence of such impurities as may be contained in points of good Siberian or Ceylon graphite. Such points have been submitted to the continuous action of a condensed spark for something like ten hours at a time, the same solution being used and the electrodes unaltered. It is usual to take fresh electrodes for each solution. (3.) In comparing the spectra of solutions of salts with those of metallic electrodes, it was found that in almost all cases the lines of metals were exactly reproduced from the solution, the graphic character being retained except in regard to their continuity, Discontinuous but long lines, or in certain cases even short lines, appear as long lines in the spectra taken from solutions. The peculiarities of the spectra of magnesium, of cadmium, and iron, were exactly reproduced, line for line, from the chlorides. An alteration was noticed in the spectrum of graphite, the short lines became long, that is to say, discontinuous became continuous lines, when the electrcdes were wetted with water 66 or acids. An exceptional instance of variation in a spectrum was seen in that of zinc. The pure metal exhibits a series of highly characteristic ex- 1882. | On Spectrum Photography. 83 eessively short lines or dots, which are totally absent from the photo- graphs of solutions of zinc made from the same metal. Certain dis- continuous lines in the spectrum of iridium become continuous when moistened with calcic chloride solution. It has been remarked by me elsewhere (loc. cit.) that the more volatile, aud I may now add, the more unoxidisable a metal, the more continuous are its lines. The compounds in solution are more volatile than the metals, and hence the ereater continuity in the lines. In the case of graphite it is doubtless a volatile carbon compound, either carbon dioxide or a hydrocarbon, which is formed by the heat of the spark when the points are moistened with water. In the case of iridium it is difficult to suppose that the calcic chloride solution forms a chloride by the simple action of heat on such a refractory metal; but this is the only explanation that will account for the greater continuity of the lines. Insoluble compounds give no spectra when mixed with water or glycerine and exposed to the spark. The non-metallic constituents of salts do not yield any marked series of lines, and therefore do not obscure the metallic spectra. The spectrum of aluminium as obtained from perfectly pure solu- tions is free from a group of short or discontinuous lines seen in my published photographs of spectra. By prolonged exposure, as I have elsewhere shown, these lines have been proved to be due to iron. The spectrum of aluminium is thus proved to be a very simple one. In all these spectra the rays lying between 4500 and 2000 on the scale of wave-lengths are completely focussed on one plate, and the relative intensities of the lines exhibit the relative intensities of the rays. Any modification in the relative intensity of a line or in its length is accurately registered on the sensitive plate. As many as fifteen different spectra have been photographed on one plate, and developed by one immersion in the developing solution. It has been proved experimentally that accidental alterations in the period of normal exposure, which are not very noticeable, do not affect the spectra. Any irregularities such as may be unavoidable in the passage of the spark do not alter the normal densities of the images of the various rays. The development of the photographs is completed in about thirty seconds. These points are of vital importance in placing this method of working on such a basis that it may be employed in quanti- tative methods of chemical analysis, for if the intensity of the rays be so great that the period of exposure is rendered much shorter, difficulties would arise in obtaining photographs with neither more nor less than the requisite density. And, again, were the exposure much prolonged the method would become somewhat tedious, or, at least, 1t would be impaired in value. (4.) Of all methods likely to yield results of practical importance in estimating the relative proportions of the constituents of either an (Bi Q) ox 84 Prof. W. N. Hartley. [June 15, alloy or a mineral, only those have recommended themselves to me which depend upon the use of solutions; and for the reason that most alloys are not homogeneous, and the portion of a metallic electrode exposed to the action of the spark is volatilised from one point, and is too minute in quantity to represent the composition of the mass. Now, the composition of a solution represents in every part the composition of the entire mass dissolved; it is, therefore, quite unimportant how small a fraction of it is used for the purpose of obtaining the spectrum of its constituents. It is a remarkable fact that at the present time we know little or nothing of the sensitiveness of the spectrum reaction wnder various conditions, notwithstanding that such knowledge is absolutely neces- sary for the purpose of giving stability to numerous theories and arguments which are based on spectrum observations. J have made some experiments in this direction by determining the extent of dilution which serves to modify in various ways the spectra of solutions of metallic salts, and that which finally causes the extinction of the most persistent line or lines. The sensitiveness of the reaction varies with different elements and with the period of exposure, the intensity of the spark, and other conditions; I have no difficulty whatever, when working in the manner here indicated, in recognising spectra yielded by solutions which contain no more than ;25,th of a per cent. of calcium, silver, copper, and j>5359th of a per cent. of manganese. It is necessary, however, for me to withhold a full account of my experiments until I have determined the wave-lengths of the lines in the various spectra under observation, for it is quite impossible to describe the changes in the spectra without reference to accurate measurements of the metallic lines. For some time past Mr. W. EH. Adeney has been working in conjunction with me at these determinations, and I hope with as little delay as possible to have the honour of submitting to the Royal Society all details here omitted, both with regard to these new methods of analysis, and the wave- length determinations. II. “On the Reversal of the Metallic Lines as seen in Over- exposed Photographs of Spectra.” By W. N. HARTLEY, F.R.S.E., &c., Professor of Chemistry, Royal College of Science, Dublin. Communicated by Prof. G. G. STOKEs, pec. B.S. Received May 19; 18382: In preparing series of photographs of metallic elements when their spectra are obtained by the action of acondensed spark passed between metallic electrodes, I have been very careful to ascertain the exact period of exposure of the sensitive plate to the rays, which will bring 1882.] On the Reversal of the Metallic Lines, &. 85 out the most characteristic lines without the additional diffused rays of the air-spectrum; at the same time very delicate and feeble air-lines are adequately shown. This has always been accomplished by making a series of comparative exposures. With gelatine emulsion dry plates great latitude in exposure is capable of yielding perfectly satisfactory photographs. An under-exposed plate is not easy to develop, in order that the usual density for the strong lines as seen in a good negative may be gained. The air-lines are generally very feeble or altogether * omitted. An over-exposed plate is likewise difficult to develop; it yields a thin flat image, and more or less marked indications of a con- tinuous air-specfrum are seen. Over-exposure, even when not excessive, is liable to cause strong lines to appear reversed. I have mentioned in my paper “ Notes on Certain Photographs of the Ultra-Violet Spectra of Hlementary Bodies”’ (“‘ Journal of the Chemical Society,” vol. xli, p. 89, 1882), that sometimes lines appear reversed in one photograph, but not in another. This did not seem at all likely, or even possible, to be caused by over-exposure, because the two periods differed only by a minute; but I have small doubts now on the matter. The conversion of what is called a negative into a positive image by excessive exposure has been already noticed by Mr. C. Bennett (“‘ British Journal of Photography,” 1878), by Captain Abney, who investigated the nature of the change (** Phil. Mag.” [5] 10, p. 200), occurring in the sensitive film, and by M. Janssen (“‘ Comptes Rendus,” 90, pp. 1447—1448). In illustration of this phenomenon, I may mention a remarkable result I obtained on one occasion when photographing a landscape. I endeavoured to secure a picture with detail in a shaded foreground, and a direct view of the setting sun, with mountains in the middle ‘distance, and strongly illuminated as well as dark clouds. In one case I succeeded remarkably well, but in another plate the foreground was good, but the sun was completely reversed. The negative image was clear glass and the sun printed black. What should have been a negative in the strong lights became a positive. Again, by exposing a plate to the cadmium spectrum, the whole of the metallic lines were rendered distinctly, but with a flatness and want of density, the whole of the strong air-lines at the least refrangible end of the spectrum were, however, completely reversed. Any strong lines may be reversed by over-exposure without materially altering the appearance of the rest of the spectrum. This is particularly the case with the lines of the metals magnesium, aluminium, and indium, but particularly so with magnesium. The reversal takes place in the centre of the line, that is to say, where the radiation is most active. Hxcept by the method of comparative exposures, which I have always employed, it would be impossible to say whether a reversal was due to an absorbed ray or an over-exposed plate. 86 Experiments on the Value of the Ohm. [June 15, M. Cornu’ has shown that the quadruple group of rays in the magnesium spectrum may become quintuple or sextuple, according to the increased intensity of the spark employed. This is precisely what might happen if one reversal by over-exposure were followed by a second. Such reversals might be looked for 1f under the conditions of the stronger spark the exposure of the plate were not shortened, because the first and third of the four lines are stronger than the other two, and they would therefore be the first and second to suffer reversal. The reversal would split the lmes in two, and hence produce the appearance of a sextuple group. In order to ascertain whether this might readily occur in the magnesium spectrum, some observations were made with plates containing several photographs obtained by different periods of exposure. Thus the first spectrum was the result of ten seconds, the second of half a minute, and others various times extending to half an hour. The quadruple group was not affected in the way observed by M. Cornu, from which fact it would appear that the division of the lines was caused by a reversal which was the result of absorption of the central portion of the ray or rays. In the two photographs obtained by the longest exposures, especially in the last, the triplet b' between K and L became a quadruple group: by reason of the most refrangible line being split into two by a reversal, the cause of which was nothing more than over-exposure. In the quadruple group previously mentioned the lines were totally reversed or not at all. This subject of reversal by over-exposure is. one well deserving the attention of those who are engaged in the study of solar physics. Comparative exposures should be methodically employed to confirm the accuracy of observations made entirely by the aid of photographic representations of spectra. specially is this desirable when gelatine or other dry plates containing organic matter are 1n use. III. “ Experiments on the Value of the Ohm.” PartI. By R. T. GLAZEBROOK, M.A., Fellow and Assistant Lecturer of Trinity College, Demonstrator at the Cavendish Laboratory, Cambridge, and J. M. Dopps, B.A., Fellow of St. Peter's College. Part Il. By R. T. GuAzEBROOK, and EH. B. SARGANT, M.A., Trinity College. Communicated by LorD: RAYLEIGH, F.R.S. Received May 24, 1882. (Abstract. ) The method of the experiments is a modification of those of Kirch-. hoff and Rowland. Two coils of copper wire of about 25 centims. radius, each containing 1882. | Experiments on the Value of the Ohm. 87 about 780 turns, were placed with their mean planes parallel and at a known distance apart. The coefficient of mutual induction between the two can be found from the geometrical data; let this be M. Let one of the coils be connected in circuit with a ballistic galvanometer, and let R be the resistance in centimetres per second of the circuit. Let a steady current of intensity 7 be circulating in the other coil—the primary. On reversing this current an induction current, of which 2Mi the amount is R? is produced in the secondary circuit, and the galvanometer needle is disturbed from rest; if 8 be the first throw of the needle, T the time of a complete vibration, X the coefficient of damping, 7 that of torsion, G the galvanometer constant, and H the horizontal intensity of the earth’s magnetism, we have 2M:__H(1+7) T (a T (a *) a8 = eee eg es The galvanometer was then connected in series with a large re- sistance coil, in our case of about 3,000 ohms; let S be the resistance of the galvanometer and this coil. The two extremities of the re- sistance S were connected with two points in the primary circuit, the resistance between which was about 1 ohm; let this resistance be V. Ms 2, 1s transmitted a through the galvanometer, and if « be the deflection of the needle, we have Then of the primary current 7, an amount Wi wala! +7) =0.- n=A, PiPpoPsPs= mea +potp3t+p,)* ; 53 2 N=9, ae 38 =) (5). “ Consequently by differentiating with respect to @ (the inclination of a perpendicular on a tangent to the initial line) in the several cases. on both sides (Besant, ‘On Roulettes,” § 7) — If n=, cot a, + cot a,+cot a,=3 cot a, VV = 4, > cot af cot a, n=, > cot sy oe = cot a, where d is a constant, and , a, ... a denote the angles made by the tangent with the vectors from the cusps and centre. 5. In the epicycloid the same polygon of reference is used. 3 If ue 10°p =p the unicuspid cardioid, 4 n=2, 40D) Pg — 33 n=3, 30°P Do 2Ps=55P° —qa*p® le za =) Consequently,if n=1, cot a, =3 cota, n=2, cot a, +cot 2,=4 cot z. The general theorems will now be established. 6. Let these perpendiculars from the cusps be expressed by tan- gential polar coordinates, when the initial line is drawn from the centre to a cusp :— PiPo +» Pa=(p—acos 0)¢ —acos( = -- 0). \p—a cos (P+ 0). nu The artifice used by Gregory in a kindred-question (‘‘ Math. 1882. ] On bic oe Epicycloids, and Polyhedra. 107 Journ.,” vol. iii, p. 145) is here adopted. Let 2?+7?’=p, 2xy=a. Cotes’ ee is thereby applicable to determine the product. er $ 42% — Dery” Cos nO= (a? —2xy cos 0+ y") 1 a? — 2ay COs (FZ+ 0) \ ate n We must next express x??+7?" in terms of p,a. The expression,. which is closely allied to the expansion of cosn@, is given in Tod- hunter’s ‘“‘ Theory of Equations,” p. 183. = (1-20?) (1—zy?) =1—z(e? +y?—20%y?), if we take the logarithm of both sides, and select the coefficient of z”, Qn Die ara peep (iad e n—2Q ae ho eee n(5)2 bineig2. 2) 2 It is also necessary to obtain the ascending series— na pi 2 a\” . ‘a\"-2 2 me2(n2—22 n—4 4. ee aw) -G) eG) (6) +t aaa) @)--- if m be an even integer, m-\ n—-3 3 2 1 2n Qn) — Pp mG? life =) ) EO +y)= (5) Ceri a 5 if m be an odd integer. 7. The polar tangential equations to the regular hypocycloids and epicycloids are Teer) ree &: ) neal n —+0}, a 1 ee n+ 2 aT where a is the radius of the fixed circle, and bears to the radius of the rolling circle the ratio n: 1 (Besant, ‘“‘ On Roulettes,” § 14). If we take the upper sign, and write— sin y=? where (n—2)x=n (- 0). n—2 z Hence —2 cos n@ =2 cos (n—2) (7x) — 9) i= k = (2 sin x)”"?— (n—2) (2 sin y)?-*#+ Rio eee Sn) al = ia - oni 1 aa} Hence the general theorem is established for hypocycloids. 108 Mr. H. M. Jeffery. [June 13, nos reer) “ir (eP-eone) “(ier (seg NED} 4 The series ends with the term involving p? or p‘, according as n is odd or even, as may be seen by examining the expansion of cos”@ in an ascending series. 8. The equation to the regular epicycloid is ee aon , where (n+2)x=n C + 0). Hence the formula for this epicycloid is z n+2 Grips pe=(Ea) wre—(5) anf (+2)( Fa) 1] ane +2 ay" oe n re \ +(5) >" iS hi AGO n (8 ns f @+2)(n—2)(n—3) ae a a “ (syer{ Gs) ie 2 (ii, Ti eae By reversing the order in expanding cosn@, it appears that no terms involving p, p, p® occur. 12. Proof of Stewart’s theorems. Since the formule of § 6 are general, they apply to a parallel line, -on which the perpendiculars are drawn. (Pi +%)(Pot#) --- (Pet) =(pta)"—n (5) (p+ayr*+ (eee (5) (o+2)*4— Se n+2 The sums of the several powers of p,, po, . . . are obtained by taking ‘the logarithm, and differentiating on both sides— gS PE Sl ost t a : “ x 2 a’ H Cc (This last quotient is remarkable, as it shows the matrix out of which these theorems of Dr. Stewart arose. ) =) HG) oF Gea +r le ot oF 1882. | On Hypocycloids, Epicycloids, and Polyhedra. 109: AY eC et 2 2 (a? n 3p 4.3 p i e LO ee Dir +5 | ae Fle S i= Sip pO ee Gaels tare We By equating the several powers of igs the several sums of powets are aw found. Z(peynanipn 4 MD) m—2 ee m—4gy A 1 |. This is the dual of Stewart’s Prop. 40. 13. If in § 12 the line touch the circle, so that p= =a, =(p,)™ be- ner Dan os eure os Pron 29 m(m—1)...2.1 eg uae Lemma.—KEvery product of consecutive factors can be expressed as a sum of a product of lower consecutive factors. comes Tiksis 11 157(@e ae) rat a ea ee» Ta re —4) (n—5)(n—6) (n— 7) _n(n—1)(n—2) (n— ge) 1.2.3.4 Deo Seay as appears by the equating coefficients of #* in the identity (_+2)"4@+1)4=(1+2)”. Hence when p=a in § 12, nmcom(m—l1),, , m2 4 4, BP Ete 2 8) i Siem Te ea +. =14m{1+(m—1)} +) + 2(m—2) + Sy hoy eas = ail: 3... (2m—1),,, =P+(7) + + me pee ti To .m rok 14. Dr. Stewart’s ee theorem (Prob. 42) follows from the same formula as the former. Il. On Theorems relating to the Regular Polyhedra, which are analogous to those of Dr. Matthew Stewart on the Regular Polygons. 1. These two general propositions may be thus stated in the dual form :— 110 Mr. H. M. Jeffery. [June 15, (A.) Let there be a regular polyhedron of (7) faces, inscribed in a sphere of radius (a). If from the summits and centre there be drawn P1> P27 + ++ Pa p perpendiculars on any plane (exterior to the solid, if (m) is odd), the sum of the (m)th powers of the perpendiculars from the summits is a function of the aa etn from the centre. =(pr)"= ACB ah Gs (Pee) ae 2(m ‘ l)a This formula is applicable to all five Platonic bodies, if m be 1, 2, 3; if m be 4, 5, and not larger, it is restricted to the dodecahedron and icosahedron. (B.) Under the same conditions as in (A), if there be taken any point, whose distance from the centre is (v), the sum of the (2m)th powers of the distances of this point from all the summits will be a function of its distance from the centre. . 2m — , Qt ee —— 7, \2m+2 =(d;) ce {(w+a) (v—a) if 2. Following the analogy of plane geometry, I propose to consider a group of five surfaces, whose orthogonal projections are the tricuspid and quadricuspid hypocycloids, and which have the property, that the product of the perpendiculars drawn on any tangent plane from all the summits of one of three regular polyhedra (which are cuspidal points on those surfaces), is a function of that perpendicular only which is drawn on the same tangent plane from the centre of the sphere circumscribed about the polyhedron. These three surfaces are defined by tangential polyhedral coordi- nates referred to the three first of the regular polyhedra. (1) piPoPsP, =p*. (2) pie + - - Pe=po—a"p*. (yy Foo 6 66 (4) pipo.-. Pp=p?—+a2pS. (5) P1P2+- + Ps=p”. 3, By generalising the results of examination in each case of the regular polyhedra, it is found that the continued product of the per- pendiculars drawn from all their summits on any plane may be thus expressed in terms of that drawn from the centre— — re 1 Q,nn—2 1 1 n” W\ 4 nA Pn EEE oes ee +4" —b nt Subsequent terms would involve the inclinations of lines and planes. But the following scale is found to exist :— 1882. | On Hypocyeloids, Epicycloids, and Polyhedra. 111 1—(n—2) f?+ (n—4)92—(n—6)hett+ .. =(l—nfe? + ngzt—nhab+ ...)A +422? 442442264 ...) where f, g, i are found to have the preceding values : 2f=4 : 4g=}fn—1: and 6h would be 4gn—4fn+}. (: is written in brief for 4 P 4. For the continued product of the perpendiculars on a parallel plane— Corte) (p.+2) ..- (pate) =@+2)"—s—ane(ptayeet .. SU. The sums of the several powers of , p.,... are found by taking the logarithm, and differentiating on both sides. ie | 1 il ae ler 0) WX, +2) SByt 6 = n ii 1 — 1+? Se gt 5 0c \ eal 3 (p+2)? (p+wx)* na 3 p? LOLA |S) a en ete Bs isnt +351 3 oe je! |e (0 es (Pen \ a cee? fear aaa By equating the coefficients of like powers of a, S(t oe =e, mma MUA oe (m—2)¢ a T SIeaesapy Cul eas Ca atts ‘where m is restricted not to exceed 5. Thus is established the first proposition (A) of § 1. 5. Proposition (B) of § 2 is proved as in § 4. The form, being universal, is equally applicable, when pj, po -- - are used to denote the constants in the expression for distances, such as— 6° =a? + v? —2av cos x. Write in this form— 112 On Hypocycloids, Epicycloids, and Polyhedra. [June 15, a+? for p, © 2av fora, © -0),(057, 1. On LOE Py) ye | ae (6? +2) (6.2+2)... (242) +(@+e +2) 9 nah +02 +2)? +e =(8,)2"= Wy { (va)? (y—a)*2}, 4(m-+1)av 6. Discussion of the first surface of the group. i Pi P2PsPa=P =F Pi + Pat Pst Ps)” It satisfies both the required conditions of § 2; and no other surface formed from the regular tetrahedron satisfies the tests. Its quadri- planar equivalent in point-coordinates is of the tenth order. The orthogonal projection on any face from its quadrantal pole, whose equation is Pe=4(P1 + Pat Pst Ps)=3(Pi + Pot Ps), gives the tricuspid hypocycloid (see § 4 of Memoir I) i x PiP2P3>= as(P1 + po+p3)? =p. b2c? —4ac? —44°d + 18abed —27a2d?=0, where a=aB 6, b= Byétayd+ ..., cmaBtayt..., d=a+tB+q+6. To ascertain its form two sections have been taken, (1) by a face, (2) by a plane through an edge and a centre. From (1), when é=0, b?(c?— 4bd) =0, that is, a BP? (V (By) + A (ya) + ¥ (2B) $=0. The first factors denote the three edges, which are conjugate double lines, the last a tricuspid hypocycloid. (2) Let y=6, or the surface be intersected by a plane AOB, which passes through the edge AB, and bisects the edge CD perpendicularly. This would give the sections of greatest'and least curvature; another such section superimposed vertically would give a clear conception of the surface. The surface consists of six lobes, which are arranged in pairs, each pair being touched by the same asymptotic cone. The edges of the asymptotic tetrahedron are conjugate lines, as is also the great circle at infinity. 7. In the same way the other surfaces are discussed and exhibited. The property (B) of Memoir I has its analogues on this group of sur- faces and their duals. 1882. | On the Critical Point of Mixed Gases. PHS IX. “On the Critical Point of Mixed Gases.” By GERRARD ANSDELL, F.C.S. Communicated by Professor JAMES Dewar, M.A., F.R.S. Received June 8, 1882. Having on two previous occasions communicated to the Society papers on the physical constants of liquid hydrochloric acid gas and liquid acetylene, under which head I include the coefficients of compres- sion and expansion, the critical points, and the volumes and tensions of the saturated vapour, it naturally led up to what promised to be along investigation into the similar constants of other gases; and, amongst other things, the behaviour of two or more gases in presence of each other, more particularly with regard to the alteration of the critical point, appeared to me of especial interest. These experiments, which I commenced nearly two years ago, were unavoidably interrupted at the time, and I have only now been able to resume them. This subject has latterly engaged the attention of many physicists and chemists, and, amongst others, both Andrews and Cailletet have examined to a certain extent the behaviour of gaseous mixtures, the former finding both the critical point and vapour-tension of carbonic acid considerably modified by the introduction of a small quantity of pure nitrogen, and the latter (‘“‘ Compt. Rend.,” 90, 210) noting the peculiar behaviour of carbonic acid with one-fifth its volume of air, the former appearing to mix completely with the latter at 130 atmospheres pressure and 5°°5 C., forming a homogeneous mixture. More recently Amagat (‘‘ Compt. Rend.,”’ 89, 1879) and Roth (‘“‘ Wiedemann,” N.F., 2, 1880) have contributed exhaustive papers on the deviation of gases from Mariotte’s law. Clausius and Van der Waals have introduced vew formule for calculating the critical point, Winkelman (Berichte, N.F., 2, 1880), Hannay (“* Proc. Roy. Soc.,” vol. 33) and others have been examining the rela- tion between the different states of matter,and Ramsay and Pawlewski have investigated the behaviour of different liquid compounds with regard to their critical points, &c.; the former took equal weights of pure benzene and ether, and found that the critical temperature and pressure of the mixture was just between those of the individual bodies, but as he evidently experimented with only the one mixture, his results do not bear much upon the present problem, for which these experiments were undertaken, namely, the variation of the critical points of different percentage mixtures of two or more gases. Pawlewski’s results, which seem to have an important bearing on the subject, I shall refer to more fully afterwards. Before selecting any particular gases for investigation, there were VOL. XXXIV, : I 114 Mr. G. Ansdell. _ [June 15, several important points to be considered. In the first place, it was advisable to select those gases which could not only be easily prepared, but whose physical constants had been thoroughly investigated ; it would be an advantage to use gases having comparatively low critical points, as the temperature would be much more easily kept constant, and would consequently contribute to the accuracy of the results; but above all those gases should be chosen which would not be likely to react upon each other in a liquid state, or at high temperatures and pressures, for this would modify the results considerably, from the probable formation of new compounds, &c. That this is likely to occur is shown in Professor Dewar’s experiments on the behaviour of carbonic acid in presence of other bodies (‘‘ Proc. Roy. Soe.,”’ 1880), where the carbonic acid often appeared to exist in a liquid state far above its critical point. This was no doubt due to the formation of a new compound; at least, as 1t could not be pure carbonic acid, we can only regard it as acompound of some kind formed under particular con- ditions of temperature and pressure, and this supposition seems to be confirmed by the experiment of carbonic acid in presence of camphor, where the camphor undoubtedly formed a new body, for we know how readily it combines with numerous substances such as hydrochloric acid, &c., to form unstable compounds. For these reasons I chose car- | bonic and hydrochloric acid gases, as they could be easily prepared, and their critical points had been very accurately determined, the former by Andrews, the latter by myself, besides being bodies most unlikely to be decomposed in each other’s presence, more especially as they are chemically saturated bodies, and therefore according to the new chemical theory, most unlikely to form any addition or molecular com- pound. The following method was adopted in the experiments, the Cailletet pump being used as described in my former papers. The carbonic acid was made by dropping pure strong sulphuric acid into a saturated solution of potash bicarbonate, being afterwards washed with distilled water, and dried by passing through four (J-tubes with pounded glass and sulphuric acid. To check the readings of the air manometer (which was the same used in my former experiments) and also the purity of the gas, a tube was filled with the pure gas alone, and the tensions at different temperatures and the critical point were found to agree very well with Andrews’ results. The hydrochloric acid gas was prepared by the action of strong sulphuric acid on pure chloride of ammonium, as described in my last paper (‘‘ Proc. Roy. Soc.,” vol. 30), and was washed and dried with the usual precautions ; a tube was also filled with the pure gas to begin with, and the critical point and tensions of the saturated vapour agreed as nearly as possible with those obtained by myself two years ago. The purity of the individual gases and the accuracy of the air mano- 1882.] On the Critical Point of Mixed Gases. 115 meter having thus been proved, an ordinary Cailletet tube was chosen, having a capillary part about 2 millims. in diameter, and a total capacity of about 50 cub. centims. This was accurately calibrated, and then filled with the hydrochloric acid gas, by passing it through in a regular stream for about four or five hours; after sealing off, the bent end was placed under pure dry mercury, under the receiver of an air-pump, and a sufficient quantity of the gas withdrawn to make room for any amount of carbonic acid gas required to be introduced ; the introduction was effected by passing a very fine capillary tube, bent at a particular angle and through which pure carbonic acid was stream- ing, round the bend of the tube while it remained under mercury, great care being taken to prevent the slightest trace of air from getting in. When sufficient carbonic acid had been introduced the tube was transferred to one of the iron bottles containing pure dry mercury, which was connected with another iron bottle containing the air manometer, and with the pump in the usual way. The critical point of the mixture was first determined, and then the tensions of the saturated vapour at different temperatures, together with the fractional volume to which the gas was reduced at the point of liquefaction, and also the relation between the liquid and gaseous volumes at different heights in the tube. At the end of the experiments the tube was carefully lifted out of the bottle, the outside of it well cleaned and dried with bibulous paper, and the end of it placed under distilled water. The small quantity of mercury in the bend of the tube was shaken out, and the water allowed to rush up the tube and absorb the hydrochloric acid gas; the solution was afterwards made up to 500 cub. centims. with distilled water, and 50 cub. centims. titrated with standard nitrate of silver, which gave the quantity of chlorine equal to the amount of hydrochloric acid in the tube. The small residue of mercury was dried and weighed, and the space it occupied subtracted from the total capacity of the tube, the remainder, after correction for tem- perature and pressure, being of course the volume of the mixed gases ; from this was subtracted the volume of the hydrochloric acid gas calculated from the amount of chlorine obtained by titration, the remainder being carbonic acid, with, of course, any slight pe of air or other inert gas that might be present. The following tables give the tensions of the saturated vapour, at different temperatures, of the different percentage mixtures of pure hydrochloric acid and carbonic acid gases. They are also plotted in the form of curves on Plate I. 12 I II TTT. wv: at: P: 1. P: i P: T B. 04 Ye27S4 0 .. 28°86 0 saa 31-89 15 4066 133... 3986 . 163.. 50°09) S902 Sie 27 5422 25°5.. 52°77 25-4.. 63°98 25 60°46 37°5.. 70°28 38:0... 67°36 340-.. 77-02 46 82°26 440.. 7623 43:2... 90°03 C.P.=47-2.. 92°21 45°5.. 8052 45-1 39°5 .. 80°28 v VI. Vil T PB. T EB; a PB: 05 eet eae On) hts jes Ones 34°65. 7D t2. ens 19:8 1.282 Si bore 1Gsak 56-44 266) «25 opst (GEL 25°5 65°68 24:9 67°27 35°0 .... 76°64 SCO fone tomes ©-P.=38'0 «2.22.7 8b385 Soro | clea x: ae 324 .... 7723 I=mixture containing 17-18 per cent. CO . ie = epee yi a : 1B " * 25°48 ; = iVv= 42-44 5. = 3 zs 45°67 5 9 a “5 ~- 74:18 ss ‘5 va — - = 82°14. te ~ T=temperature of mixed gases. P=pressure in atmospheres. C. P=critical point. The critical points of the different mixtures are also plotted asa curve on Plate II, where the ordinates represent the percentage amount of carbonic acid in the mixture, and the abscisse represent the temperature in degrees (centigrade). Now Pawlewsk, in a short abstract of a paper (“‘ Berichte,” No. 4, 1882), describes a number of experiments he had made with the isomeric ethers, the alcohols, &c., and gives an equation to represent the critical point of mixtures of two or more liquids belonging to the same class of organic bodies, in terms of their respective critical points and relative weights, from which it would appear that the critical pomt of mixed bodies is directly propor- tional to the percentage composition of the mixture, when the origin of temperature taken is that of the body having the lowest critical point. He also mentions that this would probably be the case with the liquid form of substances which are gaseous at ordinary temperatures; but from our knowledge of liquefied gases, their physical constants are so much exaggerated with regard to their compression and expansion, &c., 1882. | On the Critical Point of Mixed Gases. 117 and the variation of their critical points is so much affected by small quantities of impurity, that we might naturally suppose gases having low critical points would not altogether follow this law, and the | ae Bee) | A’liele.V- | f I results of my experiments seem to confirm this view. li will be seen from the diagram, Plate II, that instead of descending in a straight line as it ought to do, according to Pawlewski’s formula, it forms a 118 On the Critical Point of Mixed Gases. [June 15, very regular curve, all the values being below those of Pawlewski’s,. until a point is reached where the mixture contains about 17 per cent. of carbonic acid, within which limit it evidently approaches to Paw- lewski’s values. The reason for this apparent anomaly can only be explained by the assumption that a small trace of air or other impurity was present in the tube, for we know from Andrews’ and my own experiments, that; even the =3,5th part of air makes a considerable: difference both in the critical point and tension of a gas. It is also conceivable that a trace of air may have more effect in a mixture of two gases, than upon either individually, and this would consequently complicate matters considerably, when a mixture of several different gases is used. It was principally on this account that tensions of the saturated vapour of the mixture at different tem- peratures was taken, so as to judge of the amount of pee in the gases, and whether it materially affected the results. The curves on Plate I represent these tensions, the ordinates being the pressure in atmospheres, and the abscisse the temperature in degrees C. The corresponding curves for pure hydrochloric acid and carbonic acid are also shown, but although all the curves for the different mixtures, except one, fall between the two, still the distances. are evidently not strictly proportional to the percentage composition, which can only be explained by the presence of a small quantity of air; now, as this impurity must have been infinitesimal, it is inte- resting and curious to see how much it has modified the tensions of the saturated vapour. No. III should, of course, have come between No. Il and No. IV, and must have had rather a larger amount of impurity than the others, and this is also the case in No. VII, which actually shows a tension higher than that of the most volatile constituent of the mixture, which, of course, is unpre- eedented. Having satistied myself that these apparent anomalies were really due to impurity, I filled another tube with extreme care, which con- tained the same relative proportions of the gases, within °2 of a per cent. as No. VII, and found that it now assumed its proper place below the curve for carbonic acid, the critical point, however, being scarcely altered at all, showing that an amount of impurity, sufficient to materially modify the tensions of the vapour, had very little effect on the critical point. The present position of the question therefore appears to be, that the critical points of mixtures of liquefied gases cannot be expressed by Pawlewski’s formula, the maximum difference between his cal- culated value and mine, which occurred in a mixture of equal volumes of the gases, being as much as 3°°6 C. This is *2 or 25 per cent. of the whole difference between the critical points of the two gases, hydrochloric acid being 51°°25, and carbonic acid 31° C. 1882.] On an Arrangement of the Electric Arc, &c. 19 But although these experiments seem to lead to this conclusion, more extended researches with other gases of the same nature, using the same precautions, will have to be made, before the real form of the curve can be ascertained. This investigation has been carried out in the Laboratory of the Royal Institution. X. “On an Arrangement of the Electric Arc for the Study of the Radiation of Vapours, together with Preliminary Results.” By G. D. Liveine, M.A., F.R.S., Professor of Chemistry, and J. Dewar, M.A., F.R.S., Jacksonian Pro- fessor, University of Cambridge. Received June 8, 1882. In previous papers* we have described various devices for facilitat- ing the study of the reversal of the lines of metallic vapour. The first series of observations were made by examining the spectrum of the interior of iron or porcelain tubes filled with vapour and heated to the highest temperature of a coke furnace, the subsequent series being eye or photographic records of the radiation of the electric arc surrounded by metallic vapour in the middle of blocks or tubes of lime or magnesia. By inclosing the arc in a crucible of lime or magnesia we have found its steadiness very greatly increased, and the mass of metallic vapour which can be maintained at a temperature approaching to that of the are much enlarged, but it cannot be said that that tem- perature is at all under control, and the walls of the crucible are almost always cooler than the contents. By the arrangement we have now to describe we are able to make observations through a long range of temperature, as the temperature rises and as it falls, and so to trace the influence of temperature in many cases in which the extent of that influence was before doubtful. The temperature attainable is doubtless far below that of the arc, but still it is quite sufficient to maintain iron and aluminium in the state of vapour, and show the reversal of the lines of these elements with singular sharp- ness. The temperature of the interior is sufficiently high to transform the diamond into coke, even in a current of hydrogen, and the result may be taken as proving that the temperature is above that of the oxyhydrogen flame. . The apparatus employed is thus constructed: A rod of carbon, @ in the figure, 15 millims. in diameter, perforated down its axis with a cylindrical hole 4 millims. in diameter, is passed through a hole in a lime * “Proc. Roy. Soc.,” ‘On the Reversal of the Lines of Metallic Vapours,” vols. 28, 29, 32. 120 Profs. G. D. Liveing and J. Dewar. [June 15, block d, and is connected by means of a copper clip with the positive electrode of a Siemens dynamo-electric machine; another carbon rod b, unperforated, is passed into the lime block through a second hole at right angles to the first, so that the end of the rod b meets the rod a in the middle of the block of lime. The rod b is connected with the negative electrode of the dynamo machine, and after contact is made between the two carbons is raised a little so that the are discharge continues between the two carbon rods within the block of lime or magnesia. In this way the outside of the rod or tube, a, becomes intensely heated, the heat is retained by the jacket of lime, and the interior of the tube gradually rises in the central part to a very high temperature. By stopping the arc it can be made to pass through the same stages of temperature in the inverse order. Observations are made by looking down the perforation. When the light issuing from the tube is projected by a lens on to the slit of a spectroscope, the heated walls of the tube give at top and bottom a continuous spectrum, against which various metallic lines are seen reversed, while in the central part, when the tube is open at the farther end, the spectrum is discontinuous, and the metallic lines seen reversed against the walls at top and bottom, appear as bright lines. By passing a small rod of carbon ¢ into the perforation from the farther end, a luminous background can be obtained all across the field, and then, as the walls of the tube are hotter than the metallic vapours between them and the eye, the metallic lines are only seen reversed. A very slight alteration in the position of the carbon rod makes the lines disappear, or reappear, or show reversal, and as the core is adjusted by eye observation before photographs are taken, ali the conditions of the experiments are thoroughly known and are 1882. ] On an Arrangement of the Electric Are, &c. 121 under easy control. We have taken photographs of the violet and lower part of the ultra-violet spectrum given by the tube at succes- sive intervals while the temperature was rising, and noted the follow- ing results. When commercial carbons were used the first lines to be seen as the temperature rose were the potassium limes, wave-length 4.044—6, next the two aluminium lines between H and K became con- spicuous, then the manganese triplet about wave-length 4034, and the calcium line, wave-length 4226, then the calcium lines near M and an iron line, probably M, between them, and then gradually a multitude of lines which seem to be all the conspicuous iron lines between O and h. At this stage, when the small rod ¢ is used to give a back- ground, the bright continuous spectrum is crossed by a multitude of sharp dark lines, vividly recalling the general appearance of the solar spectrum. In the higher region the continuous spectrum extends beyond the solar spectrum, and the magnesium line, wave-length 2852, is a diffuse dark band, while all the strong iron lines about T, and the aluminium pair near §S, are seen as dark lines. The be- haviour of the calcium lines H and K is peculiar. These lines are often absent altogether, when the line wave-length 4226 and the two near M are well seen, and when the two aluminium lines between them and many of the iron lines are sharply reversed. Even the introduction of a small quantity of metallic calcium or calcium chloride into the tube did not bring them out reversed. They were only seen as bright lines, not very strong, when the small rod ¢ was removed. In some of the photographs H is visible as a bright line without K. We have formerly observed that K shows reversal in the electric are spectrum taken in a lime crucible on the addition of aluminium, when H remains bright, and such a condition as that shown by the hollow carbon tube where H is present without K, might legitimately have been predicted. The lithium lines at 4603 and 4131 are often bright when many other lines in the neighbourhood are reversed, and must, there- fore, be regarded as relatively difficult of reversal. As a rule the lines less refrangible than 4226 are balanced as to their emissive and absorptive power, and, therefore, disappear, while the more refrangi- ble are reversed. The cyanogen group at 3883 remain bright when the iron lines on either side are reversed; they often, however, dis- appear on the continuous spectrum. Many lines about P and Q of the solar spectrum are reversed. The cyanogen band above K is generally to be found in the photographs of the spectrum when only air is in the tube. It is then very faint, and is the only cyanogen group visible. If ammonia is passed into the tube the fine set above K, the N group, and, although less plainly marked, the set at 4218, appear. In one plate the three lines at 4380 and the group of seven at 4600 appear along with the blue hydrocarbon set. It is well 122 On the Ultra-violet Spectra of the Elements. [June 15, known that ammonia reacts on carbon at a white heat, producing cyanide of ammonium and hydrogen, so that the genesis of the cyanogen spectrum under the present conditions isa crucial test of the validity of our former observations on this subject, which are, however, in marked disagreement with the results obtained by Mr. Lockyer, in his review of the same field of investigation. Both the indium lines 4101 and 4509 are persistently reversed, together with several lead lines. Tin gives flutings in highly refran- gible portions of the spectrum, and silver gives a fine fluted-looking spectrum in the blue. Chloride of calcium gives a striking set of six or seven bands between L and M, which may be seen both bright and reversed. When the small rod ¢ is removed, it is easy at any moment to sweep out the vapours in the tube by blowing through it; it is equally easy to pass in reducing or other gases. Ammonia introduced seems to facilitate the appearance of reversed lines. On passing this gas through a tube containing magnesia, the set of lines just below J, which we have always found to be associated with the presence of magnesium and hydrogen, and is most probably due to some com- pound, instantly appear. The above is a brief abstract of the few observations we have been able to make as a preliminary to a more thorough research, and we feel warranted in thinking that the method promises to solve some intricate spectroscopic problems. When we can command several electric arcs to heat a considerable length of carbon tube, and are enabled to examine the radiation of a powerful arc passing through vapours in the tube, valuable results may ke anticipated. XI. “ On the Ultra-violet Spectra of the Elements. Part I. Tron.” By G. D. Liverne,. M.A., F-.R.S.. Protessenien Chemistry, and J. Dewar, M.A., F.R.S., Jacksonian Pro- fessor, University of Cambridge. Received June 8, 1882. (Abstract. ) By means of photographs taken with a Rutherford grating of 17,296 lines to the inch, the authors have determined the wave-lengths of ninety-one of the most prominent lines in the spark spectrum of iron between wave-lengths 2948, the termination of Cornu’s map of the solar spectrum, and 2327, and also of fourteen of the strongest lines in the spark spectrum of copper beyond that up to the wave- length 2155. Using these lines as lines of reference they have, from photographs taken with calcite prisms, deduced the wave-lengths of 584 more lines in the are and spark spectra of iron within those 1882. | On the Spectra of Carbon and rts Compounds. 123. limits. These lines are mapped on the same scale as Angstrém’s and Cornu’s maps of the solar spectrum. The paper describes the method of taking the measures, and gives in detail the quantities observed and the data on which the calculations are founded. Part II. Received June 15, 1882. (Abstract.) In the second part of this paper the authors have given a map of the ultra-violet lines of potassium, sodium, lithium, barium, strontium, calcium, zinc, mercury, gold, thallium, aluminium, lead, tin, antimony, bismuth, and carbon, as developed in the arc. They point out that in several cases the lines are in all probability harmonically related, as shown by the repetition of similar groups of lines at regularly dimi- nishing distances, the groups being alternately sharply defined and diffuse, and becoming more diffuse as they die away at the end of the series. They had previously called attention to this kind of relation- ship between the visible lines in the spectra of the alkalies and of magnesium. The like relationship holds good in the ultra-violet spectra of those metals, and is strongly marked in the cases of calcium and zinc, less strongly in some other metals. XII. “ General Observations on the Spectra of Carbon and its Compounds.” By Professor G. D. Livetne, M.A., F.R.S., and Professor JAMES Dewar, M.A., F.R.S. Received June US S2. In our two former papers on the spectra of the compounds of carbon with hydrogen and nitrogen (“ Proc. Roy. Soc.,” vol. 30) we described the results of a long series of synthetical and analytical experiments which had enabled us to trace satisfactorily a fluted band spectrum which occurs in the arc and spark discharge in many com- pounds of carbon, and generally when carbon poles are used to transmit the current of the arc or spark in air, to the compound substance cyanogen. This led to a further investigation of the carbon ultra- violet line spectrum in order to complete the series of simple vibra- tions which originate from this substance. Afterall this work a great deal remains to be ascertained regarding the conditions which cause a variation of intensity in the different series of carbon flutings which originate from cyanogen, and also their persistency and development. The present paper is a short record of the particular variations in _ the carbon groups which are revealed in the different photographs of the spectrum of the arc discharge that we have had occasion to take: 124 Profs. G. D. Livemg and J. Dewar. [June 15, for other purposes, together with some new observations on the ‘genesis of the cyanogen spectrum during combustion. The remarkable discovery of Dr. Huggins, regarding the occur- rence of two of the most marked series of cyanogen bands in last year’s comet, adds considerable interest to this question, and has induced us to make a further study of the chemical reactions in flames which cause this particular spectrum to appear at a relatively low temperature. ectric Discharge between Carbon Poles in different Gases. Hlectric Discharge bet Carbon Pol d tG In order to facilitate reference the general appearance of the portion of the cyanogen spectrum to which we shall refer is given in the following diagram :— 1882. | On the Spectra of Carbon and its Compounds. 125 The apparatus used in the experiments has been already described in our paper on the spectrum of the compounds of carbon with hydrogen and nitrogen (“ Proc. Roy. Soc.,” vol. 30). No attempt was made to use perfectly pure gases or to remove all traces of nitrogen from the vessels employed; the object being to study the variation of the groups of lines, perfect purity in the gases was not required. The are discharge between graphite poles in carbonic acid shows the triple set, beginning about 4380, with traces of the other sets of cyanogen bands at 4218 and 3883. If the carbonic acid gas is dis- placed by air, the triple set are very much weakened and are some- times invisible, while the other fluted series at 4218 and 3883 are greatly strengthened. The spark discharge does not show the cyanogen sets in carbonic acid, but a series of five groups appear between the limits of the lines S and N of the solar spectrum, which may possibly be due to carbonic acid or carbonic oxide. The carbonic oxide flame, however, does not show this set. If the spark discharge is taken between graphite poles in nitrogen all the cyanogen series appear; but in hydrogen they sometimes disappear. As a rule, however, they remain faint even when a current of the gas is kept continuously passing through the bulb in which the discharge is taken. With the are discharge in hydrogen the triple set are well marked, while the series at 4218 dis- appear, and the ultra-violet group are just visible; the hydrocarbon set, however, at 4310 come out strong. In order to ascertain how the pressure of the surrounding atmos- phere affected the emissive power of the cyanogen produced synthe- tically in the arc discharge, a series of observations on the spectra obtained under diminished pressure of the gaseous atmosphere was undertaken. The pressure in different gases was reduced to a mean value of about 1 inch of mercury, and under such conditions the intermittent discharge of the De Meritens machine was examined. The are in air, under these circumstances, showed the blue hydro- carbon set; all the cyanogen series of bands together with a nitrogen series near H. Carbonic acid at the same pressure had the triple set of lines strongly marked, while the others were decidedly weaker, as in the experiments with the gas at atmospheric pressure. | In hydrogen, at equal pressure, the triple set disappear, and the hydrocarbon set at 4310 occur, which series is not generally seen in the photographs of the arc spectrum. But what is very remarkable is the appearance of two lines of carbon, viz., 2836°5 and 2857°2 (also 2506 and 2508) in the spectrum of the discharge, whereas these spark lines are not generally found in the are spectrum. The following lines of carbon have been observed in the are dis- charge of the Siemens continuous current machine, as well as in that 126 Profs. G. D. Liveing and J. Dewar. [ June 15, of the De Meritens intermittent current, taken in air. We have observed in previous experiments that the De Meritens are in hydrogen produces a sufficient temperature to render the C line of hydrogen permanently visible. The continuons Siemens current, under the same circumstances, only shows this line when the are is produced by breaking the contact of the poles, not with the steady Bie, Approximate Wave-lengths of Carbon Arc-lines. 2434°3 absent from spark. 2478°3 strongest line. 25066. 25141. 2515°8. 2518°8. 2523°9. 25281. 2881'1 not in spark. We have here another instance of the lines of high refrangibility appearing, under certain circumstances, when no trace of strong lines belonging to the less refrangible portion of the spectrum can be detected. ‘Thus the strong carbon line in the blue at 4266 does not appear in the photographs of the arc spectra. Of course it is possible that a very long exposure of the photographic plate might reveal some of the missing lines, as we have shown in other cases. The presence of these carbon lines is a proof that carbon vapour of a definite, but probably low, tension exists in the are discharge, and this is doubtless the reason why under such conditions carbon combines with hydrogen and nitrogen with such facility. By a careful series of experiments carried out at different pressures with varying electric power we hope to ascertain with greater precision the variations in the carbon line spectrum. Hye Observation of Spectra. When the spectrum of different parts of a magnified image of the electric arc is examined, all the more refrangible cyanogen groups may be seen near the positive pole, together with a series of channellings in the red. When the arc is steady the cyanogen spectrum is per- manently visible at the negative pole, when no trace of the hydro- carbon series can be seen. In the same way the arc in the middle of a magnesia crucible often shows ro trace of the hydrocarbon set, although the cyanogen are strong. If, however, puffs of air or carbonic acid are passed into the arc, the hydrocarbon lines are pro- duced. There is always, under these circumstances, far greater 1882. | On the Spectra of Carbon and its Compounds. 127 variation in the brightness of the hydrocarbon series than of the cyanogen, in fact, the presence of magnesia rather favours the steady formation of cyanogen. When the hydrocarbon spectrum is strong the brilliancy and number of the cyanogen groups that are visible are undoubtedly increased, so that the one variety of vibrations seems to affect the other. This is easily accounted for by the chemical inter- action which takes place between acetylene, nitrogen, and hydrocyanic acid. The hydrocarbon spectrum is brought out at once im the magnesia crucibles by moistening one of the poles. All such actions seem to show that hydrogen is essentially connected with the produc- tion of this fluted spectrum just as nitrogen is with the cyanogen series. Arc Discharge in Fluids. The De Meritens arc, taken in water, shows the hydrocarbon spectrum alone; no cyanogen bands can be seen by eye cbservation, even when ammonia or nitrate of potash is added to the water. In this case the observations are rendéred uncertain from the great intensity of the continuous spectrum. If glycerine is used instead of water no cyanogen groups of lines can be recognised, but on adding a little nitrobenzol the set of three lines (about 4380) peculiar to the cyanogen spectrum appear, this being the only group which can be detected by the eye on the continuous background. This result sup- ports the observations on the varying intensity of this group in different gaseous media, and seems to show that conditions can be found where it is the most characteristic group of cyanogen. These three lines are easily seen in the spectrum of the arc taken in carbonic acid. although they disappear from the spectrum of the arc taken in air. Vacuwm Tube Spectra. In our former experiments with vacuum tubes we did not use a capil- lary glass tube, but preferred to examine the photographic spectrum obtained from a short spark taken between platinum wires. Objec- tion has been taken to this plan of working on the ground that, as the capillary form of vacuum tube increases the brilliancy of the spectrum, particular lines or groups of the spectrum which otherwise would be missed, might be revealed in them, and such tubes ought, therefore, to have been employed. In order to answer this objection we have pre- pared and examined vacuum tubes of this kind containing benzol and benzol with naphthalene in solution, using all the precautions to avoid the presence of nitrogen formerly described, and have always found such tubes free from any trace of the cyanogen spectrum. When such tubes are, however, examined daily, the cyanogen bands often appear after a time, and this can be traced in all such cases to a leak or crack at the point where the platinum is sealed into the glass. No per- 128 Profs. G. D. Liveing and J. Dewar. (June 15, fectly pure hydrocarbon gives the series of bands we attribute to cyanogen.” Observations on Flames. The temperature produced by the combustion of hydrocarbons and other non-nitrogenous organic bodies well supplied with oxygen, is not sufficient to induce the combination of nitrogen with carbon, so that the cyanogen spectrum is absent from such flames. We know, how- ever, that hydrocyanic acid is often produced in the oxidation of organic bodies containing nitrogen, and that ammonia reacts with. carbon at a white heat, producing hydrocyanic acid and hydrogen. Such actions led us to expect that the cyanogen spectrum ought to appear in the flames of organic compounds containing nitrogen, pro- vided the temperature were sufficient to render the radiation of this substance sufficiently intense. Our first experiments did not succeed. The most careful examination by the eye of the spectrum of a hydrogen flame which had passed through a solution of hydrocyanic acid or of a flame of alcohol containing nitrobenzol or nitrite of ethyl, did not result in any recognition of the strong cyanogen groups. This failure led to a chemical examination of the composition of the gases withdrawn from the interior of such flames, in order to ascertain the combustible mixtures which react during combustion to produce hydrocyanic acid. The gases were extracted from the flame with an apparatus similar in principle to that employed -by Deville in his ‘“‘Chemical Researches on Flame.” When coal gas is passed through a solution of ammonia and burnt, the flame gases contain hydrocyanic acid and acetylene, but if oxygen is well supplied to the flame no cyanogen reaction is given by the extracted gas. Car- bonic oxide mixed with ammonia in the same way gave no trace of hydrocyanic acid during combustion: even when a large quantity of the mixture was burnt and the flame gases continuously withdrawn no appreciable cyanogen reaction could be detected. Similarly hydro- gen mixed with a little carbonic acid and ammonia gave no cyanogen reaction. When hydrogen is passed through ammonia solution mixed with chloroform, tetrachloride of carbon, bisulphide of carbon, * Tt is worthy of note that the strong carbon line wave-length 2478°3 present in both the are discharge and in the spark discharge in carbon compounds at atmo- spheric pressure, is not found in the spectrum of the spark in cyanogen at low pressure. We have tried to obtain a photograph of it from a “ Plicker” tube fitted with a quartz end, and placed end-on in front of the spectroseope, but found no trace of it. As this line appears in the spectrum of the flame of cyanogen, its absence from the spark discharge in cyanogen of low tension seeras intelligible only on the supposition that the discharge is selective in its course, and lights up only certain of the substances present, or else that the quantity of carbon vapour present at any instant is so minute, as to produce no sensible effect on the photo- graphic plate-—July 10, 1882. 1882. ] On the Spectra of Carbon and its Compounds. 129 or picoline, cyanogen can always be recognised in the flame gases. ‘Chloroform under such circumstances yields the largest amount. When a mixture of carbonic oxide and ammonia is passed through a porcelain tube heated in a furnace, large quantities of hydrocyanic acid are produced, especially when the moist gases are employed. Ammonia passed over perfectly pure graphite at a white heat produces hydro- cyanic acid, and the vapour of chloride of ammonium is equally efficient in bringing about this reaction. It appears to result from the experiments that hydrocyanic acid can always be separated from the interior of flames such as we have employed, provided that portion of the flame which, in carbon compounds, is characterised as reducing, be selected. That stage of combustion during which free carbon or dense hydrocarbon vapours containing very little hydrogen are formed, is favourable to the formation of hydrocyanic acid, as ammonia can at this stage react on the carbon. It is quite possible, however, that hydrocyanic acid may exist in small quantity in some of the flames which tested according to this method appear to contain none, and that notion is favoured by the consideration of the dissociation phenomena which are known to occur in flames. ‘This led us again to spectroscopic examination as the most delicate test for the presence of cyanogen, but instead of trusting to the eye as in former experiments, photographs were taken of the spectra of flames by means of a quartz and calcspar train, and the exposure of the plate purposely prolonged. Thus examined, it was found that coal gas well supplied with oxygen gave only the hydrocarbon groups, together with the two interesting additional lines first discovered by Dr. Huggins, having the wave-lengths 3872 and 3890; but when the coal gas passed through ammonia the photographs revealed the characteristic cyanogen groups at 3883 and 4218, the most refrangible group being the strongest. The cyanogen spectrum can then be pro- duced synthetically from nitrogen compounds in flames along with the hydrocarbon spectrum, so that the appearance of the groups of cyanogen is not always associated with a very high temperature such as we have in the electric arc. Cyanogen once formed gives its pecu- har spectrum at the relatively low flame temperature produced by burning cyanogen mixed with carbonic acid. Of course the mean tem- perature of a flame is very different from the temperature of individual molecules, and this complicates the problem we are discussing. The thermal equivalents of cyanogen and acetylene being highly negative, it is certain that these substances yield on combustion the highest tem- perature of any two compounds burning in oxygen; and we have shown in a former paper that burning cyanogen in nitric oxide gas, which probably induces a still higher temperature, does not bring about any marked change in the character of the spectrum. Spectroscopic analysis can thus detect very small quantities of cyanogen under VOL. XXXIV. K 130 Lord Rayleigh. [June 15,. widely different physical conditions. As the temperature of the fame of cyanogen probably approaches the temperature of the carbon poles. of the electric arc, and as we have shown that carbon undoubtedly exists in the form of vapour in the are discharge, from the fact of the ultra-violet line spectrum being present, the question naturally arises, is carbon present in the form of vapour in the cyanogen flame ? In order to answer this question we have taken photographs of the ultra-violet spectrum of the cyanogen flame fed with oxygen, and with long exposures have had no difficulty in detecting one of the strongest carbon lines, viz., that at 2478°3, along with a trace of what may be the pair of lines at 2837, but more probably is a mercury line. No- other carbon line was found in the photographs. It seems, therefore,. proved that carbon vapour does exist in the flame of cyanogen, although to a much smaller extent than in the are discharge. Observa- tions must be made on the spectra of flames under high pressures, in order to solve many problems connected with spectroscopic enquiry, and this subject we hope to discuss in a future communication. XII. “Further Observations upon Liquid Jets, in continuation of those recorded in the Royal Society’s ‘ Proceedings’ for March and May, 1879.” By Lord RAYLEIGH, F.R.S., Pro- fessor of Experimental Physics in the University of Cam- bridge. Received June 8, 1882. The experiments herein described were made in the spring and summer of 1880, with the assistance of Mrs. Sidgwick. Section 2 was indeed written out as it now stands in August of that year.. There were some other points which I had hoped to submit to: examination, but hitherto opportunity has not been found. On some of the Circumstances which influence the Scattering of a nearly Vertical Jet of Liquid. § 1. It has been already shown that the normal scattering of a nearly vertical jet is due to the rebound of the drops when they come into collision. It, by any means, the drops can be caused to amalga- mate at collision, the appearance of the jet is completely transformed. This result occurs if a feebly electrified body be held near the place of resolution into drops, and it was also observed to follow the addition of a small quantity of soap to the water of which the jet was com- posed. In trying to repeat the latter experiment in May, 1880, at Cambridge, I was astonished to find that even large additions of soap failed to prevent the scattering. Thinking that the difference might -1882.] On Liquid Jets. Teli be connected with the hardness of the Cambridge water—at home I had used rain water—I repeated the observations with distilled water, but without finding any explanation. The jet of distilled water scattered freely, both with and without soap, and could only be pre- vented from doing so by electricity. Hventually the anomalies were traced to differences in the character of the soap. That used at Cambridge up to this point was a clarified specimen prepared for toilet use. On substitution for it of common yellow soap, the old effects were fully reproduced. Further experiment seemed to prove that the real agent was not soluble soap at all. If water impregnated-with the yellow soap was allowed to stand, a white deposit separated, after which the super- natant liquid was found to be inactive. But after shaking up the same effects were produced as at first. The addition of caustic potash to the unclarified soapy mixture destroyed its power. On the other hand, sulphuric acid rendered the clarified soap solution active. The natural conclusion from these facts would be that the real agent is unsaponified greasy matter distributed through the liquid; and this view is confirmed by the striking results which follow the addition of small quantities of milk. The experiment may be made conveniently by connecting a Woult’s bottle with the water tap by a rubber tube fitted to one tubulure, while the vertical nozzle is in con- nexion with another tubulure. Ii a little milk be placed in the bottle, the jet of opalescent liquid apparently coheres, and passes the summit in one unbroken stream. After a time the milk is gradually washed out, aud the scattering is re-established. About one drop of skimmed milk per ounce of water is sufficient to produce the effect. I must not omit to mention that on several occasions distinct evidence was obtained that it is possible for soap to be*in excess. With a large quantity the coherence of the jet was imperfect, and was improved by dilution. The complete elucidation of the subject pro- bably requires more chemical knowledge and experience than is at my command. Of the various other substances which have been tried, such as olycerine, sugar, gum arabic, alcohol, sulphuric acid, none have been found active. Vertical fountains of mercury were found not to scatter. The head was about 15 inches, and various glass nozzles were used from #4, inch to 3, inch in diameter. Also a nozzle terminating in an amalgamated brass plate, through which a hole of #5 inch was pierced. In all these cases the drops of mercury coalesced at collision, behaving in the same way as drops of milky water issuing from the same nozzles. Fountains of clean water issuing from these nozzles under the same pressure scattered freely. When the diameter of the nozzle from which a water jet issues is K 2 132 Lord Rayleigh. [June 15, reduced to below 535 inch, the scattering cannot be completely prevented by the presentation of an electrified body. One possible reason for this is evident. The mutual repulsion of the similarly electrified drops increases rapidly relatively to the masses as the size is reduced, and thus it may happen that before the differential electrification sufficient to rupture the separating envelope at contact is arrived at, the repulsion may be powerful enough to prevent most of the drops from coming into contact at all. In connexion with this it may be remarked that two perfectly equal and equally electrified spheres would repel one another at all dis- tances; but that if there be the slightest difference in the size or electrification, the repulsion will be exchanged for attraction before actual contact is attained. T'his attraction will be local, and thus the opposed parts of the surfaces may come into contact with considerable violence, even when the relative motion of the centres of the masses is small. It is easily shown experimentally (see § 4) that violence of contact tends to promote coalescence, so that we have here a possible explanation of the action of electricity. With respect to the persistent scattering of very fine jets, however, it would appear that the principal cause is simply that many of the fine drops fail to come into contact in any case. The capillary forces act with exaggerated power, and doubtless impress upon the minute drops irregular lateral velocities, which may easily reach a magnitude sufficient to cause them to clear one another as they pass. At any rate little difference is observable in this respect between a fine jet of clean water under feeble electrical influence, and one to which a little milk has been added, but without electrification. With a suitable jet, say from a nozzle about =, inch diameter, and rising about 2 feet, the sensitiveness to electricity 1s wonderful, more especially when we remember that the effect is differential. I have often caused a jet to appear coherent, by holding near the place of resolution a brass ball about 1 inch in diameter, supported by a silk thread, and charged so feebly that a delicate gold-leaf electroscope would show nothing. Indeed, some care is necessary to avoid being misled by accidental electrifications. On one occasion the approach of a person, who had not purposely being doing anything electrical, invariably caused a transformation in the appearance of the jet. The jets hitherto under discussion are such as resolve themselves naturally into drops soon after leaving the nozzle, or at any rate before approaching the summit of their path. If the diameter be increased, we may arrive at a condition of things in which the undis- turbed jet passes the summit unbroken. In such a case the addition of milk, or the presentation of an electrified body, produces no special effect. One interesting observation, howeyer, may be made. By the action of a vibrator of suitable pitch, e.g., a tuning-fork, 1882. ]- On Liquid Jets. 133 resolution on the upward path may be effected. As the vibration gradually dies down, the place of resolution moves upwards, but it cannot pass a certain point. When the point is reached, resolution into actual drops ceases, the upper part of the jet exhibiting simple undulations, when viewed intermittently. The phenomenon is in perfect harmony with theory. As it leaves the nozzle, the jet is un- stable for the kind of disturbance imposed upon it by the vibrator. The subsequent loss of velocity, however, shortens the wave-lengths of disturbance, until at length they are less than the circumference of the jet, after which the disturbance changes its character from unstable to stable. The vibrator must evidently produce its effect quickly, or not at all. Influence of Regular Vibrations of Low Pitch. § 2. Towards the close of my former paper on the capillary phenomena of jets, | hazarded the suggestion that the double stream obtained when an obliquely ascending jet is subjected to the influence of a vibration, an octave graver than the natural note, is due to the compound character of the vibration. At the time of Plateau’s researches the fact that most musical notes are physically composite was much less appreciated than at present, and it is not surprising that this point escaped attention. I have lately repeated Plateau’s experiments under improved conditions, with results confirmatory of the view that no adequate explanation of the phenomena can be given which does not have regard to the possible presence of overtones; and I have added some observations on the effects of the simultaneous action of two notes forming a consonant chord. In order to make a satisfactory examination of it, it is necessary to employ some apparatus capable of affording an intermittent view of the jet in its various stages of transformation. In the experiments formerly described I used sparks from an induction coil, governed by the same tuning-fork which determined the resolution of the -jet. This has latterly been replaced by a perforated disk of black card- board, driven at a uniform speed by a small water-motor. The diameter of the holes is one-fifth of an inch—about that of the pupil of the eye, and the interval between the holes is about four inches. Hxamined under these conditions the jet and resultant drops are sufficiently well defined, and there is abundant illumination if the apparatus is so arranged that the jet is seen projected against the sky. The speed of the motor is regulated so that there is one view through the holes in about one complete period of the phe- nomenon to ke observed. If the power is a little in excess, the application of a slight friction to the axle carrying the disk renders the image steady, or, what is better, allows it to go forwards through its phases with moderate slowness. 134 Lord Rayleigh. [June 15, . Although the multiple streams are better separated when the jet is _ originally directed upwards at an angle of about 45°, I preferred to use a horizontal direction as giving simpler conditions. The velocity and diameter are then practically constant throughout the transfor- mation, and may be readily calculated from observations of the head and of the total quantity of fluid discharged in a given time. The reservoir consisted of a large glass bottle, provided with a tubulure near the bottom. Into this was fitted a l-inch brass tube, closed at the end by a flat plate, in which a circular aperture was pierced of about 4, of an inch in diameter. If h=head, d=diameter of jet, v=velocity of issue, V=volume discharged in unit time, then ird’v=V, v= V/(2gh). Again, if N' be the frequency of the most rapid vibration which can influence the jet, we have by Plateau’s theory— pana ADS yee Med gd 2S (tV) 27 (rV) | If N be the frequency of the principal note of the jet, then, as explained in my former paper, _ 3142 N’. 4°508 In the present experiment it was found that 1050 cub. centims. were discharged in four minutes, and the head was 7# inches, so that in C.G.S. measure— ye OOk pipe Ode eon 240 whence N37 IN 2.59; As sources of sound tuning-forks, provided with adjustihble sliding pieces, were employed, except when it was important to eliminate the octave as far as possible; the vibration was communicated to the reservoir through the table on which it stood. The forks were either screwed to the table and vibrated with a bow, or mounted on stands (resting on the table) and maintained electrically. The former method was quite adequate when only one fork was wanted at a time. { With pitches ranging from 370 to about 180, the observed phenomena agreed perfectly with the unambiguous predictions of theory. From the point—decidedly below 370—at which a regular effect was first 1882. ] On Liquid Jets. 135 obtained, there was always one drop for each complete vibration of the fork, and a single stream, every drop breaking away under the same conditions as its predecessor. After passing 180 it becomes a question whether the octave of the fork’s note may not produce an effect as well as the prime. If this effect be sufficient the number of drops is doubled, and unless the prime be very subordinate indeed, there is a double stream, alternate drops taking sensibly different courses. In these experiments the influence of the prime was usually sufficient to determine the number of drops, even in the neighbour- hood of pitch 128. Sometimes, however, the octave became pre- dominant, and doubled the number of drops. It must be remembered that the relative intensities with which the two vibrations reach the jet depend upon many accidental circumstances. The table has natural notes of its own, and even the moving of a weight upon it may change the conditions very materially. When the octave is not strong enough actually to double the drops, it often produces an effect which is very apparent to an observer examining the trans- * formation through the revolving holes. On one occasion a vigorous bowing of the fork which favours the octave, gave at first a double stream, but this after a few seconds passed into a single one. Near the point of resolution those consecutive drops which ultimately coalesce as the fork dies down, are connected by a ligament. If the octave is strong enough this ligament breaks, and the drops are separated, otherwise the ligament draws the half-formed drops together, and the stream becomes single. The transition from the one state of things to the other could be watched with facility. In order to get rid entirely of the influence of the octave a different arrangement is necessary. It was found that the desired result could be arrived at by holding a 128 fork in the hand over a resonator of the same pitch resting on the table. The transformation was now quite similar in character to that effected by a fork of frequency 256, the only differences being that the drops were bigger and twice as widely spaced, and that the spherule, which results from the gathering together of the ligament, was much larger. We may conclude that the cause of the doubling of a jet by the sub-octave of the note natural to it is to be found in the presence of the second component, from which scarcely any musical notes are free. When two forks of pitches 128 and 256 were sounded together, the single or double stream could be obtained at pleasure by varying the relative intensities. Any imperfection in the tuning is rendered very evident by the behaviour of the jet, which performs evolutions syn- _ chronous with the audible beats. This observation, which does not require the aid of the revolving disk, suggests that the effect depends in some degree upon the relative’phases of the two tones, as might be expected @ priori. In some cases the influence of the sub-octave is ‘ 136 Lord Rayleigh. [June 15, shown more in making the alternate drops unequal in magnitude, than in projecting them into very different paths. Returning now to the case of a single fork screwed to the table, it was found that as the pitch was lowered below 128, the double stream was regularly established. The action of the twelfth below the principal note (853) demands special attention. At this pitch we might in general expect the first three components of a compound note to influence the result. If the third component were pretty strong it would determine the number of drops, and the result wouid be a three- fold stream. In the case cf a fork screwed to the table the third component of the note must be extremely weak, if not altogether missing; but the second (octave) component is fairly strong, and in fact determines the number of drops (1902). At the same time the influence of the prime (854) is sufficient to cause the alternate drops. to pursue different paths, so that a double stream is observed. By the addition of a 256 fork there was no difficulty in obtaining the triple stream, but it was of more interest to examine whether it were possible to reduce the double stream to a single one with only 854 drops per second. In order to secure as strong and as pure a fundamental tone as possible, I cause it to act in the most favourable manner upon the jet, the air space over the water in the reservoir was tuned to the note of the fork by sliding a piece of glass over the neck so as partially tocover it. When the fork was held over the resonator thus formed, the pressure which expels the jet was rendered variable with a frequency of 854, and overtones were excluded as far as possible. To the unaided eye, however, the jet still appeared double, thongh on more attentive examination one set of drops was seen to be decidedly smaller than the other. With the revolving disk, giving about eighty- five views per second, the real state of the case was made clear. The smaller drops were the spherules, and the stream was single in the same sense as the streams given by pure tones of frequencies 128 and 256. The increased size of the spherule is of course to be attributed to the greater length of the ligament, the principal drops being now three times as widely spaced as when the jet is under the influence of the 256 fork. With still graver forks screwed to the table the number of drops continued to correspond to the second component of the note. The double octave of the principal note (64) gave 128 drops per second, and the influence of the prime was so feeble that the duplicity of the stream was only just recognisable. Below 64 the observations were not carried. Attempts to get a single stream of 64 drops per second were unsuccessful, but it is probably quite possible to do so with vibrations of greater power than I could command. In the case of a compound note of pitch 64 a considerable variety of effects might ensue, according to the relative strengths of the 1882. ] On Liquid Jets. 137 various components. Thus, the stream might be single (though this is unlikely), double, triple, four-fold, or even five-fold, with a corre-. sponding number of drops. Observations were next made on the effects of chords. For the chord of the fifth the pitches taken were 256 and 2x256. The two forks could be screwed to the table and bowed, or, as is preferable (especially in the case of the chords of the fourth and third to be spoken of presently), maintained in vibration electromagnetically by a periodic current from a break-fork of pitch 854, standing on another table. The revolving disk was driven at such a speed as to give about eighty-five views per second. As was to be expected, the num- ber of drops was either 256 in a triple stream, or 3 X 256 in a double stream, according to the relative intensities of the two vibrations. With the maintained forks the phenomenon is perfectly under control, and there is no difficulty in observing the transition from the one state of things to the other. In ike manner with forks 256 and #256, driven by fork 64, and with sixty-four views per second, the stream is either triple or quad- _ruple; and with forks 256 and + x 256, we get at pleasure a four-fold or five-fold stream. To obtain a good result the intervals must be pretty accurately tuned. In the case of electrically maintained forks, the relative phase remains unchanged for any length of time, and the spectacle seen through the revolving holes is one of great beauty. The actual results obtained experimentally by Plateau differ in some respects from mine, doubtless in virtue of the more composite character of the notes of the violoncello employed by him, but they are quite consistent with the views above expressed. The only point as to which I feel any difficulty relates to the single stream, which occasionally resulted from the action of the twelfth below the principal note. It seems improbable that this could have been a single stream of the kind that I obtained with some difficulty from a pure tone; indeed the latter would have been pronounced to be a double stream by an observer unprovided with an apparatus for intermittent views. I should rather suppose that the number of drops really corresponded to an overtone, and that from some accidental cause the divergence of what would generally be separate streams failed to be sensible. The Length of the Continuous Part. When a jet falls vertically downwards, the circumstances upon which its stability or instability depend are continually changing, more especially when the initial velocity is very small. The kind of disturbance to which the jet is most sensitive as it leaves the nozzle is one which impresses upon it undulations of length equal to ahout four and a-half times the initial diameter. But as the jet falls its velocity increases (and consequently the undulations are lengthened), 138 Lord Rayleigh. [June 15, and its diameter diminishes, so that the degree of instability soon becomes small. On the other hand, the kind of disturbance which will be effective in a later stage is altogether ineffective in the earlier stages. The change of conditions during fall has thus a protective influence, and the continuous part tends to become longer than would be the case were the velocity constant, the initial disturbances being unaltered. I have made many attempts to determine the origin of the dis- turbances which remain in operation when the jet is protected from ordinary tremors, but with little result. By suspending the reservoir with india-rubber straps, &c., from the top of a wooden tripod, itself resting upon the stone floor of one of the lower rooms of the Cavendish Laboratory, a considerable degree of isolation was attained. A stamp of the foot upon the floor, or the sounding of a note of suitable pitch of moderate intensity in the air, had no great effect. Without feeling much confidence I rather incline to the opinion that the residual disturbances are of internal origin. As the fluid flows up to the aperture along the inner surface of the plate which forms the bottom of the reservoir, eddying motions are almost certainly impressed upon it, and these may very possibly be the origin of the ultimate disin- tegration. With the view of testing this point, I arranged an experiment in which the velocity of the fluid over the solid walls. should be as small as possible. AB (fig. 1) represents a large brass tube, to which a smaller one is soldered at B, suitable for india-rubber connexion. The bottom of 1882. | On Liquid Jets. 139 the large tube consists of a carefully worked plate in which is a circular hole of 4 inch diameter. When the rubber tube is placed in connexion with the water supply, a jet drops from A, and may be made exceedingly fine by regulaton of the pinch-cock C. By turning off the supply at C altogether, the jet at A may be stopped, without emptying the vessel. The stability, due to the capillary tension of the surface at A, preponderates over the instability due to gravity. By this device it is possible to obtain a jet whose velocity is acquired almost wholly after leaving the vessel from which it issues. In this form of the experiment, however, the jet is liable to disturbance ‘depending upon the original velocity of the fluid as it passes through the comparatively narrow rubber tube, and when I attempted a remedy by suspending a closed reservoir (fig. 2), in which the water might be allowed first to come to rest, other difficulties presented themselves. The air confined over the surface of the water acts as a spring, and the flow of water below tends to become intermittent, when rendered sufficiently slow by limiting the admission of air. A definite cycle is often established, air flowing in and water flowing out alternatively at the lower aperture. The difficulty may be over- come by careful manipulation, but there is no easy means of making an adequate comparison with other jets, so that the question remains undecided whether the residual disturbances are principally of in- ternal or of external origin. Collision of two Resolved Streams. §4. In the case of a simple vertical fountain, when the scattering is prevented by electricity, there is every reason to believe that the action is differential, depending on a difference of potentials of colliding drops. The principal electrification, however, of the successive drops must be the same; and thus, sensitive as it is, this 140 Lord Rayleigh. [June 15, form of the phenomenon is not by any means the best calculated to render evident the smallest electrical forces. As was shown in my former paper, it is far surpassed by colliding jets, between which a difference of potential may be established, a subject to which we shall return in § 5. It is possible, however, to experiment’ upon the collision of two distinct streams of drops, which are differently,—if we please, oppositely—electrified from the first. Apart from electrical influence, the collision of such streams presents points of interest which have been made subject of examination. Two similar brass nozzles, terminating in apertures about 5 inch in diameter, were supplied from the same reseryoir of water, and were held so that the jets rising obliquely from them were in the - same plane and crossed each other at a moderate angle. The jets were resolved into regular series of drops by the action of a 256 fork screwed to the table and set in action by bowing. The periodic phenomenon thus established could be examined with facility by intermittent vision through a revolving perforated disk (§ 2), so arranged that about 256 holes passed the eye per second. When the angle of collision is small, the disposition of the files of drops may be made such that they rebound without crossing, fig. 3; more often, however, the drops shoulder their way through after one or more collisions, somewhat as in fig. 4. In both cases the presentation of an electrified body to one place of resolution will determine the amalgamation of colliding drops, with of course com- plete alteration of the subsequent behaviour. By judicious manage- ment a feebly electrified body may be held in an intermediate position 1882. ] On Liquid Jets. 141 between the two points of resolution so as not to produce the effect, confirming the view that the action is differential. At a somewhat higher angle of collision amalgamation will usually occur without the aid of electricity, but the fact may easily escape recognition when intermittent vision is not employed. ‘The streams do not usually join into one, as we might perhaps expect, but appear to pass through one another, much as if no union of drops had occurred. With the aid of the revolving disk the course of things is rendered evident. The separating layer is indeed ruptured at con- tact, and for a short time the drops move as one mass. There is, however, in general, considerable outstanding relative velocity, which is sufficient to bring about an ultimate separation, preceded by the formation of a ligament (fig. 5). In certain cases, although after contact a lhgament is formed, the relative velocity is insufficient to overcome its tension, and the drops draw again together and ulti- mately cohere. If the impact is very direct, so that the relative velocity is almost entirely in the line of centres, the drops may flatten against one another and become united without the formation of a ligament. In order to determine how small a difference of potential would be effective in causing the coalescence of streams of drops meeting at a small angle, the two places of resolution were enclosed in inductor- tubes, between which with the aid of a battery a difference of potential could be established. The arrangement is shown in fig. 6. One of the inductors is placed in connexion with the earth, with the reservoir from which the water comes, and with one pole of the battery. By operating a key, the other inductor may be placed at pleasure in communication with the first inductor, or with the other pole of the battery. In the first case the battery is out of use, and in the second the difference of potential due to the battery is established between the two inductors. 142 Lord Rayleigh. [June 15, Experiment showed that the effect depends a good deal upon the exact manner of collision. In almost all cases twenty cells of a De la Rue battery sufficed to produce amalgamation, with subsequent replacement of the original streams by a single one in a direction bisecting the angle between the original directions. With a less battery power the result may be irregular, some of the drops coalescing and others rebounding. When the collisions are very direct, even four cells will sometimes cause a marked transformation. The complete solution of the problem of the direct collision of equal spheres of liquid, though probably within the powers of existing mathematical analysis, is not necessary for our purpose; but it may give precision to our ideas to consider fora moment the case of a row of equal spheres, or cylinders, with centres disposed upon a straight line, and so squeezed together that the distances between the centres must be less than the original diameters. By the symmetry, the common surfaces are planes, and the force between contiguous masses is found by multiplying the area of the common surface by the internal capillary pressure. When the amount of squeezing is small, the internal capillary pressure is approximately unaltered, and the force developed is simply proportional to the area of contact. In the case of the cylinder the problem admits of very simple solution, even when the squeezing is not small; for, as is easily seen, the free surfaces are necessarily semicircular, and thus the condition of un- altered volume is readily expressed. It will of course be noticed that as regards lateral displacements the equilibrium is unstable. Collision of Streams before Resolution. § 5. The collision of unresolved streams was considered in my former paper. It appeared that the electromotive force of a single Grove cell, acting across the common surface, was sufficient to deter- 1882. | | On Liquid Sets. 143 mine coalescence, and that the addition of a small quantity of soap made rebound impossible. Moreover, the ‘coalescence of the jets would sometimes occur in a capricious manner, without the action of electricity or other apparent cause.” As in many respects this form of the phenomenon is the most instructive, I was desirous of finding out the explanation of the apparent caprice, and many experiments have been made with this object in view. The observations on fountains recorded in § 1 having suggested the idea that the accidental presence of greasy matter, removable by caustic potash, might operate, this point was examined. “ July 8, 1880.*—Colliding Jets—Two large glass bottles, with holes in the sides, close to the bottom, were fitted by means of corks with glass tubes, drawn out to nozzles of about 3, of an inch in diameter. The bottles were well rinsed with caustic potash, to remove any possible traces of grease, and filled with tap water. The colliding jets coalesced in a manner apparently entirely capricious, the only prin- ciple observable being that they coalesced even more readily with high pressures (12 inches) than with low, and with lower pressures would stand collision at greater angles. The addition of caustic potash suffi- cient to give a very decided taste to the water, produced no apparent effect.”” Subsequently the water used was boiled with caustic potash, but without success. / “July 27, 28, 29, 30.—On the theory that when the jets collide without uniting there is between them a thin film of air, which would be very liable to be sucked up by water not saturated with air, we tried jets of water through which a stream of atmospheric air had been passed for several hours. We tried it three times. The first time the jets seemed very decidedly less lable to unite capriciously. The second time they behaved even worse than ordinary tap water usually does. The third time we thought it rather better than tap water usually is, but not materially so.” Jets of hot water, and of mixtures of alcohol and water in various proportions, were also tried at this time, but without obtaining any clue as to the origin of the difficulty. IT had begun almost to despair of success, when a determined attempt to conjecture in what possible ways one part of the stirred liquid could differ from another part suggested the idea that the anomalies were due to dust. “‘ Aug. 1880.—We tried dropping dust on to the colliding jets just above the point of collision, and found that union was always pro- duced. The following powders were tried—powdered cork, sand, lycopodium, plaster of Paris, flowers of sulphur, sugar, dust that had accumulated upon a shelf, and later emery and putty powder. The lycopodium was a little more uncertain in its action than the others, * Mrs. Sidgwick’s “‘ Note Book.” 144 On Liquid Jets. | [June 15, but apparently only because, owing to its lightness, it was difficult to ensure its falling upon the jets. Whenever we were sure it did so, union followed.” When mixed with the water, powders acted differently. Hmery and putty powder were not effective, but sulphur caused immediate union. Much probably depends upon the extent to which the extraneous matter is wetted. A precipitate of chloride of silver, formed in the liquid itself, seemed to be without influence. Acting upon this hint, Mrs. Sidgwick made an extended series of observations upon the behaviour of jets composed of water which had been allowed to settle thoroughly, and which were protected from atmospheric dust. For this purpose the jets were enclosed in a beaker glass, the end of which was stopped by a plug of boxwood, fitted air- tight. Through the plug passed horizontally the two inclined glass nozzles, and underneath a bent tube serving asa drain. The results, observed under these circumstances, were such as to render it almost certain that dust is the sole cause of the capricious unions. The pro- tected jets of settled water were observed for a total period of 246 minutes, during which the unions were at the average rate of one in ten minutes. The longest intervals without unions were thirty-four minutes and twenty-nine minutes. Comparative experiments were made upon the behaviour of jets from the same nozzles under other conditions. Thus jets of unsettled water, but protected from atmo- spheric dust, united on an average twenty-four times in ten minutes. With unsettled water the protection from atmospheric dust is not of much use, as unprotected jets of the same water did not unite more than twenty-six times in ten minutes. On the other hand, jets of settled water, not protected from the atmosphere, united only twelve times in ten minutes. Although, no doubt, somewhat different numbers might be obtained on repetition of these experiments, they show clearly that the dust in the water is the more frequent cause of union under ordinary circumstances, but that when this is removed the atmospheric dust still exerts a powerful influence. The difficulty of getting water free from dust is well known from Tyndall’s experi- ments, so that the residual tendency to unite under the most favour- able conditions will not occasion surprise. Although there is no reason to suppose that any other cause than dust was operative in the above experiments, it remains true that very little impurity of a greasy character will cause immediate union of colliding jets. For this purpose the addition of milk at the rate of one drop of milk toa pint of water is sufficient. It may be noticed too that the effect of milk is not readily neutralised by caustic potash. With respect to the action of electricity, further experiments have been made to determine the minimum electromotive force competent to cause union. The current from a Daniell cell was led through a 1882.] Ona Collection of Rock Specimens from Socotra. 145 straight length of fine wire. One end of the wire was connected by platinum foil with the liquid in an insulated glass bottle, from which one of the jets was fed. The glass bottle supplying the second nozzle was similarly connected with a moveable point on the stretched wire. The electromotive force necessary to cause union, as measured by the distance between the two fine wire contacts, though definite at any one moment, was found to vary on different occasions, possibly in conse- ‘quence of forces having their seat at the strfaces of the platinum oil. From one-half to three-quarters of the whole force of the Daniell was usually required. With a view to further speculation upon this subject, an important question suggests itself as to whether or not there is electrical contact between colliding and rebounding jets. To solve this question it was only necessary to introduce a fine wire reflecting galvano- meter into the arrangement just described, taking care that the electromotive forces employed fell short of what would be required to cause the union of the jets. Suitable keys were introduced for more convenient manipulation, and sulphuric acid was added to the water, in order to make sure that absence of strong galvanometer deflection could not be due merely to the high resistance of the thin columns of water composing the jets. Repeated trials under these conditions proved that so long as the jets rebounded their electrical! insulation from one another was practically perfect. As to the explanation of the action of electricity im promoting union, it would be possible to ascribe'it to the additional pressure called into play by electrical attraction of the opposed water-surfaces, acting as plates of a condenser. But it appears much more natural to regard it as due rather to actual disruptive discharge, by which the sepa- rating skin is perforated, and the equilibrium of the capillary forces is upset. A small electromotive force, incapable of overcoming the insulation of the thin separating layer, is without effect. XIV. “On a Collection of Rock Specimens from Socotra.” By Professor T. G. Bonnzry, M.A., F.R.S., F.G.8. Received June 12, 1882. ! (Abstract. ) In the spring of 1879 the island of Socotra, which lies off the north-east corner of Africa, about 140 miles from Cape Gardafui, was visited by Professor Bayley Balfour. Landing at the north-west extremity, he traversed the northern side of the island up to the eastern end, then returning by a more central course to the sea, he VOL. XXXIV. I 146 Prof. T. G. Bonney. [June 15, crossed the Haggier Mountains to the southern coast, and returned again to Hadibu, on the north side, by a route lying further to the west. During this journey, in addition to extensive botanical and zoological collections, Professor Balfour obtained about 500 rock specimens illustrative of the geology of a considerable portion of the island. These were sent to the author for examination. A consider- able number of them, as was to be expected, were more or less weathered, and so were*not in a very favourable condition for precise: description; but about eighty of the best preserved specimens have been examined microscopically; from the study of which, and of the remainder the following sketch of the geology of the island may be given. The north-west, inland from Gollonsir Bay, consists of a plateau of limestone resting unconformably upon a group of highly crystalline eneisses, associated with diorites, which correspond in general cha- racter with the Hebridean series of north-west Scotland. The latter group is frequently exposed in the beds of the valleys, the uplands on either side being formed of the limestone. The elevated district traversed between Gollonsir and Kuhmeh Bays is similarly consti- tuted, but it is probable that some true granite also exists among the older series; the limestone extends all along the coast of the latter bay, having its usual foundation, and eres is evidence that felsites occur somewhere in this district, most probably inland from the eastern shore. In this part are basalt dykes, which cut the limestone as well as the older rocks. Near the coast of Hadibu Bay, west of that town, we have limestone,. eonglomeratic at base, resting on an indurated shale or argillite, together probably with an intrusive rock approaching kersantite in character. The argillite is also found inland beneath the limestone, south-east of Hadibu. The Hageier mountains, a fine chain forming a sort of back- bone to the island, consist of felspathic granites, varying from coarse to fine, the former containing little besides quartz and felspar (the variety pegmatite), through which have broken minette, basalt, and felsite; the limestone may be traced some distance up their flanks. Hast of the Haggier, the granite rock continues, but quartz-felsites, and even rhyolites, appear to become more common, and an epidotic quartzite gives an indication of the occurrence of the metamorphic eroup. Granite and felsites form the inland district traversed by the river which passes Maaber, as well as the eastern half of the Hageier mountains. The district in the neighbourhood of the coast between this and the next river to the east, consists of granite cut by felsites, rhyolites, and diorites, or dolerites. Possibly the gneissic series reappears here. Further east yet we obtain clearer indications of the latter, overlain as before by an extensive capping of limestone. Thus, the main axis of 1882.] Ona Collection of Rock Specimens from Socotra. 147 the northern part (if not of the whole island), appears to consist of granitoid gneiss, replaced towards the centre by granite. The granitic, felsitic, and rhyolitic rocks must occupy a consider- able breadth of the island from north to south, for there are many specimens from districts traversed on the return journey from the eastern promontory, in which Prof. Balfour, after keeping parallel to the southern coast for some miles, struck inland in a north-west direc- tion. Thus measured, there must be an area some ten miles across occupied by these rocks; and judging from the specimens, one would say that this was one of the chief centres of ejection of rhyolitic lavas ; this is near that part of the island covered by the final A in SoxoTRa on the map. In crossing back to the north shore along the course of the Haggier river granites, basalts, felsites, and rhyolites, as might be » expected, were collected. The conglomerates of felsite and rhyolic pebbles picked up on the Nowkad Plain, approaching the southern. coast, show that there must be a large mass of these rocks somewhere on the south flank of the Haggier range. The limestone is generally of a yellowish or whitish colour, compact in structure, and often not unlike the dolomites of the Italian Tyrol, in the hand specimen. Microscopic examination shows that it is some- times partially dolomitized. It contains numerous foraminifera amphistegina, globigerina, textularia, rotalina, &c. The first of these shews that it is probably of Middle Tertiary age, and thus rather later than the limestone of the Sinai Peninsula. The author’s investigations lead then to the following conclusions : That the oldest rocks in Socotra are gneisses, hornblendic, and grani- toid, belonging, like those of the north-west of Scotland, of North- east America, &c., to the earliest Archean age. That these, as at Sinai, are broken through by granites, some of which resemble much those of Serbal and Jebel Musa, and that these are cut by later granites, felsites, and greenstones, together with basalts, the last pro- bably of rather recent date. On the southern flank of the Haggier range, there must have been a rather extensive volcanic disturbance, from which rhyolitic lavas, often showing marked fluidal structure and scoria were ejected. The date of these eruptions cannot be fixed, but it was prior to the deposition of the limestone, and may be much older, except locally, where there is a little sandstone possibly repre- senting the Nubian sandstone (Carboniferous) of Sinai, and the argillite. What is now Socotra, would appear to have been a land sur- face from very early times, until the submergence in the Miocene period, when the great masses of limestone were deposited. It is, however, quite possible that the peaks of the Haggier range may have remained above water even during that time. Since its elevation, great denudation has doubtless taken place, including the definition of the island, and the sculpturing of the valleys in the limestone La 148 Dr. W. Huggins. On the [June 15, district. During this period, there have been some disturbances of a voleanic nature, as the limestone is cut by dykes of basalt, and of com- pact trachytes which, however, differ considerably from the purplish rhyolites already mentioned. As there is a possibility of this island having remained above water from a very remote antiquity, the in- vestigation of its flora and fauna will possess a peculiar interest. XY. “On the Photographic Spectrum of Comet (Wells) I, 1882.” By Wiuu1am Hueecins, D.C.L., LL.D., F.R.S. Received June 15, 1882. On the evening of Wednesday, May 31, I obtained a photograph of the spectrum of this comet with an exposure of one hour and a quarter. A spectrum of a Urs Majoris was taken through the other half of the slit, on the plate, for comparison. The photograph shows a strong continuous spectrum extending from about F to a little beyond H. In this continuous spectrum I am not able to distinguish the Fraunhofer lines. In this comet therefore, at this time, the original light giving a continuous spectrum must have been much stronger relatively to the sunlight reflected than was the case in the comet of last year. It should be stated that the greater faintness of the present comet made it necessary to use a more open slit, which would cause the Fraunhofer lines to be less distinct; but the lines G, H, and K are to be clearly seen m the star’s spectrum taken under the same conditions. Eye observations by several observers on the visible spectrum of the comet had already shown that this comet for the first time since spectrum analysis was applied to the light of these bodies in 1864, gives a spectrum which differs essentially from the hydrocarbon type to which all the comets previously examined spectroscopically (about twenty) belong. In the visible spectrum bright lines, presumably of the vapour of sodium, and some other bright lines and bright groups of lines have been seen. The hydrocarbon bands in this part of the spectrum have been suspected to be present by some observers. The photographic spectrum differs greatly from that of the comet of last year.* Jam not able to see the cyanogen group in the ultra- violet beginning at wave-length 3883, nor are the other two groups between G and h and between hk and H to be detected. The continuous spectrum which extends from below F to a little distance beyond H, contains at least five brighter spaces, which are doubtless groups of bright lines. though it is not possible in the pho- * “ Proc. Roy. Soc.,” vol. 33, p. 1. 1882.] Photographic Spectrum of Comet (Wells) J, 1882. 149 tograph to resolve them into lines. These places of greater brightness can be traced beyond the border of the continuous spectrum on the side which corresponds to the coma of the comet on the side next the sun. The light from this part of the comet gave a very much fainter continuous spectrum, for on the photographic plate it appears to be almost wholly resolved by the prism into these bright groups. One or two fainter groups are suspected to be present, but they are too indistinct to admit of measurement. The five stronger bright groups are too faint at the commencement and ending of each group to permit of more than a measurement of the estimated brightest part of each bright space. The positions of these brightest parts are— 150 Mr. G. F. Dowdeswell. Action of Heat [June 15, n 4769, » 4634, » 4507, r 4412, 4253. Professor A. Herschel and Dr. yon Konkoly pointed out long ago that the spectra of periodic meteors belonging to different swarms differ from each other, and the meteorites which come down to us differ greatly in their chemical constitution. It is not surprising to find the matter of the nucleus of this comet to exhibit a chemical difference from that of other comets. In the diagram, the width of the continuous spectrum corresponds to the diameter of the nucleus. The bright bands extend into the coma on the side next the sun. XVI. “On the Action of Heat upon the Contagium in the two forms of Septichemia known respectively as ‘ Davaine’s’ and ‘ Pasteur’s.” By G. F. DOWDESWELL, M.A. (Cantab.), F.L.S., F.C.8., &. Communicated by J. BURDUN SANDER- son, M.D., LL.D., F.R.S., &c. Received June 15, 1882. Professor Rosenberger, of Wiirzburg, has recently published the results of experiments,* by which he claims to have effectually sterilised by heat, the blood and exudation fluids of the rabbit in the two forms of septichemia, known as those of Davaine and Pasteur; ‘and he states that these fluids so sterilised, upon injection into other animals, were found to be infective, reproducing the disease with the recurrence of the specific organisms which characterise it: he there- fore regards these organisms as having no causal connexion with the affections in which they are found, but as merely secondary or epiphenomenal. That this would be the necessary deduction from the experiments mentioned, if it were proved that-the fluids had been effectively sterilised, is obvious; but the account published contains no details whatever of the methods employed, nor protocol of the ex- periments, so that it is impossible either to discuss them or to form a judgment as to the correctness of the conclusions. They, however, involve a question so important in respect to the theory of contagium vivum—the relations of these micro-organisms to disease—that it was determined to work out the subject on the basis indicated in Professor Rosenberger’s paper, adopting such methods and precautions as appeared necessary. * “ Centralb. f. d. Med. Wiss.,” 1882, No. 4, pp. 65-69. 1882.] upon Contagium in two Forms of Septichemia. 151 . Part I.—EHuaperiments wpon Pasteur’s Septicheemia in the Guinea-Pig. Guinea-pig No. 1.—0°7 cub. centim. of putrid ox-blood was injected with a Pravart’s syringe, into the peritoneal cavity of a full-grown guinea-pig, which the next morning was found recently dead, rigor not having set in: round the place of injection there was some sub- cutaneous exudation, with destructive inflammation of the tissues of the abdominal wall, sections of which showed numerous Bacilli and Microccecci in the layers of connective tissue between the muscles. Acute peritonitis was found with a large exudation of serous fluid containing some extravasated blood-corpuscles, and deeply stained with their colouring matter. The fluid in this case was not very coagulable, differing in this respect from some cthers. ‘The same day 0°5 cub. centim. of the peritoneal exudation fluid of No. 1 was injected into the subcutaneous tissue of the abdomen of guinea-pig No. 2, which, as the following day was Sunday, was not examined till Monday morning, when it was found dead, and in a much more advanced stage of decomposition than would have occurred normally in the same period. In all forms of septichemia this rapid decom- position is invariably found. Guinea-pig No. 3 then received in similar manner 0°5 cub. centim. of the diluted subcutaneous exuda- tion fluid of No. 2, which, likewise, was not coagulated. On the following morning No. 3 was found dead but still warm ; the abdomen was infiltrated with a large quantity of subcutaneous exudation fluid, deeply stained with hemoglobin, and containing some extravasated blood-corpuscles, as well as numerous active Bacilli and some Micro- cocci or spores. The serous fluid was not very coagulable; of this a portion was mixed with equal parts of normal saline solution, freshly made and boiled, containing in addition 1 per cent. of potassic car- bonate, to render the serum alkaline and prevent coagulation upor boiling, which it did effectually. Vacuum tubes of about 10 millims. diameter and 10 centims. long, previously prepared, were then par- tially filled with this liquid by breaking their points under its sur- face ; these were then placed one by one in a small flask of salt solution, to avoid frothing and splashing; this was then heated, and when the liquid was boiling freely, the tube enclosing it was resealed by the blow-pipe. The tubes were then placed in the hot air chamber, the temperature of which was gradually raised to 140° C., and maintained at nearly that point for one hour. No coagulation occurred upon heating, but it was found in subsequent experiments, that, inasmuch as the degree of dilution and alkalinity required to prevent this, varied in different cases, both with exudation serum and with blood, it was necessary in every instance to determine this point experimentally. The same evening guinea-pig No. 4 received by subcutaneous injection 0°3 cub. centim. of the exudation fluid of 152 Mr. G. F. Dowdeswell. Action of Heat [June 165,. No. 3, diluted and prepared as above mentioned, but unheated, while guinea-pig No. 5 received in similar manner 0°3 cub. centim. of the same fluid superheated and cooled. The following day, twenty-five- hours after injection, No. 4 was prostrate, in a state of collapse, and the next morning was found dead with the same symptoms and micro-. organisms aS in previous cases, while No. 5 was quite unaffected, feeding heartily and with temperature unaltered. This animal remained healthy and unaffected for some days, and subsequently died from an accidental cause. On examination no symptoms what- ever were found, either of septichemia or peritonitis; there was no exudation of any sort and the blood was free from organisms. The following day the exudation fluid of No. 4 was diluted and rendered alkaline in the same manner asin the previous experiments, enclosed. in tubes and superheated as before; of this 1:0 cub. centim. was injected into the subcutaneous tissue of guinea-pig No. 6, which, not- withstanding the large quantity it received, remained totally un- affected and was ultimately killed. Some cultivation experiments were then made in different nutrient fluids, both with the sterilised and the unsterilised exudation serum, the result was that in all cases excepting one, in which there was. reason to believe that the result was due to accidental contamination, no development of organisms occurred with the sterilised fluid, which it invariably did with the unsterilised. In the septichemia of Pasteur, the characteristic organism is a Bacillus, somewhat similar morphologically to the B. anthracis, and one of the forms of the hay Bacillus, B. subtilis of Cohn, the ubiquitous organism which developes so readily and constantly in most organic: infusions, from atmospheric or other contamination, and until the specific morphological characters of these organisms are better discriminated than they are at present, that is probably until there is a further substantial advance in our optical appliances, it is scarcely safe to draw any conclusion from their occurrence in cultivations,. unless these are numerous and repeated, with rigorous control experiments. In this case, 7.e., Pasteur’s septichemia, or the malignant cedema of Koch, in the guinea-pig, I have invariably found both in this, as in other series of experiments, that in animals examined immediately upon death there are none of the specific organisms (the Bacillus. described,—which is so large that it can scarcely be overlooked) to be: found in the blood, or in any of the organs of the infected animal, and that the blood is not infective. After death, however, they speedily invade the organs of the animal, the kidneys and the spleen. being apparently the first attacked; hence the necessity in all these cases of examining the subject immediately after death. 1882.| upon Contagium in two Forms of Septichemia. 153: Part I].—EHzperiments upon the blood of Rabbits in the form of Septicheemia known as that of Davaine. This form of septichemia in the rabbit, which has attracted so much attention, and been the subject of so many experiments since those first published by Davaine and by MM. Coze and Feltz, in 1869, is originated by the subcutaneous injection of a small quantity —a few drops—of putrid blood, usually that of the ox. Infection with the specific disease in this case, as in the parallel one of septi-. cheemia in the mouse, is somewhat uncertain, and the law on which it depends has not been clearly determined. Usually, however, blood which is only a few days old,—three or four—is, as originally stated by Davaine, the most readily infective, but by no means constantly so. In the following experiments all the rabbits employed were young, and nearly of the same age and size, not quite full grown. The septichemic blood used for injection was always diluted, generally with. an equal bulk of freshly prepared and boiled normal saline solution ; the quantities of blood given as injected, unless otherwise stated, are always those of the blood itself which was used, and not of the solution. No. 1.—0°2 cub. centim. of putrid ox-blood some days old was. injected into the subcutaneous tissue of the back of rabbit No.1. In forty-eight hours afterwards the rectal temperature was found to be 106° F., and the animal died on the third day. In the blood from the heart, examined immediately after death, a few of the organisms. characteristic of the disease* were found, and preparations made and stained by the Weigert Koch method, gave the same result. Two hours after death 0-1 cub. centim. of the blood of No. 1 was injected into rabbit No. 2. Twenty hours afterwards the rectal tem- perature was 104° F'., and the animal expired in my presence twenty- three hours after injection. Section was made almost immediately, within about five minutes after death, but the blood was found already partially coagulated in the cavities of the heart and in the vessels. The. blood which remained fluid was quickly mixed with two parts normal. saline solution, with the addition of 3 per cent. pot. carb., and 0°3 cub. centim. of this solution (=0°1 cub. centim. blood) was injected into: the subcutaneous tissue of rabbit No. 3, which died just within twenty hours after injection. A portion of the dilute alkaline blood was then placed in tubes, by breaking their points, sealed at a red heat, underneath the fluid; they were then immersed in a small flask of saline solution, sealed while boiling, and placed in the hot air oven,. the temperature of which was gradually raised to 140° C., and slowly * These are fully described in the forthcoming number (for June, 1882) of the: “Journ. Royal Micros. Society.” 154 Mr. G. F. Dowdeswell. Action of Heat [June 15, cooled ; it was maintained at a temperature of over 100° C. for upwards of one hour. It being then late in the evening, rabbit No. 4 was on the next morning injected with a Pravart’s syringe full of the dilute superheated blood. This animal survived and was but slightly, if at all affected, notwithstanding the very large quantity of fluid injected. The following day there was no appreciable disturbance whatever, but on the third day slight pyrexia occurred, the animal’s skin felt hot to the touch, and the rectal temperature rose to 100°0° F., which, however, sometimes occurs normally in rabbits kept in confinement. Subsequently, it remained totally unaffected for several days, as long -as observed, and was then destroyed. Some days afterwards, the blood of another rabbit of a subsequent generation of the same infection, immediately upon death, was mixed with two parts normal saline solution, and 2 per cent. pot. carb., this was inclosed in tubes, boiled, sealed, and heated to 120° C., in the same manner as before. . Of the alkaline dilute blood (unheated) further diluted up to 100,000,000 times, 0°6 cub. centim. (=*000000006 cub. centim. of lood) was injected into the back of rabbit H, which died of septi- -cheemia within twenty hours. Of the dilute superheated blood, 0°6 cub. centim. (=0°2 cub. centim. blood) was injected into rabbit F, which the next day was apparently unaffected, but died with the usual symptoms of septicheemia the following day, 7.e., thirty-nine hours after injection. In the blood were found the characteristic Bacteria, and it proved to be infective when injected in a small quantity into another rabbit. Upon this, the ‘same day, a further portion of the same superheated dilute alkaline blood was injected in the same quantity (0°6 cub. centim.) into | rabbit G. This rabbit remained totally unaffected, and survived as long as observed, twenty days after, although it had received upwards -of 30,000,000 times the quantity of blood which had proved lethal to rabbit E within twenty hours. Cultivation experiments have been made both with the superheated blood and with that in the natural state, taken upon death; but as it was found that the Bacterium which occurs in these cases refuses to germinate in any of the various cultivating media employed, except- ing only in the serum of ox-blood, and in that very sparsely and uncertainly, they were inconclusive; and the greater part of the cultivating glasses inoculated with blood of both sorts, after bemg kept several days in the incubator at temperatures between 30° and 40° C., unstable as the solutions are, remain to this day—a month subse- -quently—perfectly pellucid and unaltered, save from some loss by evaporation. On considering these results, it appeared possible that, in the case -where the superheated blood proved infective, from the method of 1882.] upon Contagium in two Forms of Septichwmia. 155 filling the vacuum tubes, portions of the dilute blood drying on their sides, might have escaped perfect sterilisation by heat; it was there- fore determined to repeat the experiments with tubes filled by a method which should avoid this possible source of error. Tubes were made of thick German glass, about ‘3 inch internal diameter, closed at one end and slightly drawn out three or four inches from the bottom ; then the blood of rabbit H, which died in my presence, of transmitted infection, was immediately collected and mixed with three times its bulk of normal saline solution with the addition of | 3 per cent. potassic carbonate. In this instance it was found that a less degree of either alkalinity or dilution would not prevent coagula- tion on heating. Of this blood further diluted up to the ten- thousandth degree, 0°6 cub. centim. (=*00006 cub. centim. of the un- mixed blood) was injected into the back of rabbit I, which died of septicheemia in twenty-seven hours; the characteristic organisms were found in the blood, which on inoculation into another rabbit proved to be infective. A portion of the same alkaline dilute blood was then placed in the tubes above-mentioned, 2 to 3 cub. centims. in each, by means of a capillary pipette introduced to the bottom, con- tamination of the sides being avoided; the tubes were then drawn out by the blow-pipe to a capillary point, boiled in salt solution and sealed while boiling. One tube that was heated separately to 140° C. burst, as had been the case in several other experiments previously ; the remainder were thereupon heated to fully 100° C. for six hours, when the temperature was raised to 130° C., were maintained at that for one hour, and then gradually cooled. Of this dilute superheated blood, rabbit K received by subcutaneous injection in the back 0:6 cub. centim. (=0°15 cub. centim. blood), and rabbit L received 1:1 cub. centim. of the same (=0°275 cub. centim. blood), that is nearly five thou- sand times as much as rabbit I had received of the unheated blood. Both these rabbits K and L were unaffected in any manner whatever : there was no appreciable variation of the rectal temperature; they continued to feed well, and did not lose flesh. They were killed ten days subsequently ; and no material inflammation at or around the place of injection, and no thickening whatever of the tissues which occurs so markedly in all cases of infection could be observed; there was only a slight stain, as if by the colouring matter of the blood, in the subcutaneous tissue near the spot of injection. From the result of these experiments I conclude that the active virus of infection, both in the case of Pasteur’s septichemia—the malignant oedema of Koch—in guinea-pigs, and in Davaine’s septi- chemia in rabbits, is destroyed by the prolonged action of a suffi- ciently high temperature; that blood or exudation fluid so treated is not infective, nor in any appreciable manner toxical, when injected in moderate quantities (up to 1 cub. centim.) into other healthy L5G. EK. Nunn. On the Development of [June 15, animals, while the same fluids unheated, are invariably and fatally infective in infinitely smaller quantities. In Davaine’s septichzemia in the rabbit, I have found throughout. these experiments that the period of incubation is remarkably constant,. death, after the first generation of infection by putrid blood, almost invariably occurring from about twenty to twenty-five hours, and con- sequently that if it does not occur within about that period, it may be concluded that infection has failed; it may die subsequently, as rabbits. in confinement constantly do, more especially under the conditions in which they are kept in laboratories; but unless within about the period specified they do not die infected with specific septichemia, the characteristic organisms are not found in the blood, nor is that blood infective; hence it is not necessary to observe such animals for more than a few days after inoculation. These experiments were conducted in the laboratory at University College, with the co-operation of Dr. Burdon Sanderson, and at his. suggestion. XVII. “On the Development of the Enamel of the Teeth of Ver- tebrates.” By Emity Nunn. Communicated by Professor Hux ey, F.R.S. Received June 14, 1882. [PuLatEs 2-4. | The question of the origin of the enamel of the teeth in vertebrate animals has been the subject of much discussion. It has been held— Ist, that the enamel results from the calcification of the enamel cells. (Tomes, Waldeyer, Edwards) ; 2nd, that it is formed by excretion from those cells (K6lliker, Hertwig, Leydig) ; and, 3rd, that it is not formed by these cells at all, but has the same origin as the dentine, whatever that may be.* Again, there are numerous opinions concerning the nature and origin. of the cuticula dentis :—1, that the cuticula is the persistent basement membrane itself (Huxley, Hertwig, Leydig) ; 2, that it is the altered enamel membrane; 3, that it is the external layer of cells of the enamel organ (Waldeyer); 4, that it is the metamorphosed sératwm untermedium of the enamel organ (Lowve); 5, that it is the ends. (Deckeln) of the cells of the enamel membrane (K6llman) ; 6, that it is a dermic structure (Tomes) ; 7, that it is an excretion of the cells of the enamel membrane (Kolliker). * Huxley, “ Tegumentary Organs,” “ Encyclopedia of Anat. and Phys.,” vol. v,, Sup., gives reasons for considering the whole tooth ecderonic, but adds, ‘“ All these points can only be decided by a much more extensive series of investigations.” 1882. | the Enamel of the Teeth of Vertebrates. 157 The existence of a basement membrane or membrana preeformativa, said by some to cover the tooth papilla, is generally considered doubtful. It is asserted, lst, that the newly-formed layer of enamel has been mistaken for it (Waldeyer) ; 2, that the first-formed layer of dentine has been mistaken for it (Léwve); 3, that the “appearances described are capable of a different interpretation ” (Tomes). The present investigation was undertaken at the suggestion of Professor Huxley with the hope of determining—or at least of getting more light upon—firstly, the history of the various membranes—the euticula dentis, the so-called newly-formed layer of enamel, the mem- brana preeformativa, and the first-formed layer of dentine; secondly, the origin of the enamel. The present paper gives the results which have heen arrived at concerning these points. The nature of dentine will form the subject of a second paper. Since it is well established that the teeth and placoids of the Plagiostomi are. homologous with the teeth of the higher vertebrates, illustrations from these will be used as well as from mammalian teeth, adult and embryonic. The drawings described have been made by the aid of the camera. 1. The Cuticula Dentis—A membrane covering the enamel of young teeth has been repeatedly described as homogeneous and reticu- lated, or with “ zellzeichnungen,” supposed to have been made by adjoining cells. Huxley* says of this membrane: “It is perfectly clear and transparent, and under a high power exhibits innumerable little ridges upon its outer surface, which bound spaces sometimes oval, sometimes quadrangular, and about ; 4, of an inch in diameter. In the frog its surface is in parts reticulated as in man; in the mackerel and skate I have been unable to find any such reticulation. In the calf a similar membrane may be demonstrated, but it is much more delicate, and I have not seen the peculiar areole on its surface.” This account agrees with the description given by other writers of a membrane found lying upon the enamel, as also with my own observations. The membrane, then, may be reticulated, entirely, in parts only, or not atall. It varies in thickness in the same animal, and as well as in different animals, and may be thick or delicate. It has been found by myself, as well as by other observers, upon the young tooth, both before and after its eruption. Hitherto it bas not been figured,+ neither has its history been determined; hence the various opinions as to its nature and origin. Waldeyerf{ declared it to be the newly- * Huxley, “ Quarterly Journal of Microscopical Science,” 1853, pp. 157, 158. + A drawing, by Nasmyth, has since been found, of the inner surface of this membrane, showing the impressions of the enamel prisms. ~ Waldeyer, “ Handbuch,” 1869. 158 E. Nunn. On the Development of [June 19, formed layer of enamel. Huxley * considered it as the persistent basement membrane. Fig. 1, A, Pl. 2, is a drawing en face of this membrane as seen upon the molar of a young rabbit: it was taken from the tooth below the gum. The areole, upon its outer surface, were perfectly clear and transparent, as has been described, and a side view (fig. 1, B) showed them to be elevated into ridges. But the spaces or disks which they bounded were granular and were found to stain slightly with carmine. In this preparation they were round, but in some they are distinctly polygonal, while in others they are faintly seen and their outlines. cannot be definitely traced. In the part of this membrane exposed above the gum, which appeared perfectly homogeneous, they could not be detected at all. While this membrane still covers the embryonic tooth ‘it may be that a few of the elongated cells of the organon adamantine adhere to it.’”’+ This may be the case even when the membrane has been well washed with a camel-hair brush previously to being hardened, as. mone, 1, B: This preparation clearly shows the reticplation to corre- spond in position to the cell-wall of the overlying cells and the enclosed spaces to the protoplasmic contents. The different structure of the clear colourless glassy areole and the granular slightly coloured disks, proves the reticulation to be something more than the impression of adjoining cells, as it has been described to be. The frequently granular character of the disks is rarely so distinct as in the present preparation, generally requiring a high power of the microscope for its demonstra- tion, and it seems previously to have escaped observation. The ridges, always upon the outer surface of the membrane, appear to be the walls of the cells, broken off a little above the extreme end of the cell, and in many preparations they occupy a larger relative space in the membrane than is shown in fig. 1. Tt would seem as if the cell-wall were thickening about this end of the cell, or the protoplasm were undergoing a differentiation into a substance similar to cell-wall. The ends of the cells of the overlying enamel membrane frequently appear jagged (fig. 2), as also the surface of the membrane directed toward them, while its other surface, or that directed towards the enamel, is perfectly smooth, as is the case with the surface of the enamel, when the tooth has been sufficiently care- fully and gradually decalcified. In the upper part of fig. 2, where the tissues have not been separated, no membrane can be detected, the line between enamel cells and mem- brane not being a sharp one; but when the former are torn away, the latter is isolated (fig. 2, c), and a front view showed it to have the appearance of fig. 1, save that the disks are polygonal (fig. 2, B). A similar structure on the tooth of the thornback is shown in fig. 3. * Huxley, Jc. + Huxley, l.c. p. 157. 1882]. the Enamel of the Teeth in Vertebrates. 159 Here, as is frequently the case, the ends of the cells appear broken or vacuolated, or striated, and with high power the strize can be distinctly seen in transverse section on the edge of the membrane, which in all stages, being much more tenacious than the enamel cells, generally adheres to the enamel when the cells are removed, and may be raised up by the use of acid. Asarule, the older the tooth the more com- pletely the reticulations or the cell-markings are obliterated, and the more resisting is the membrane, so that by maceration, as well as by the help of an acid, it may be taken off entire from the surface of the young tooth. It has been isolated by myself in this way, as also by Hertwig, who asserts it to be the ‘‘derb”” basement membrane, and the “ zellzeichnungen”’ upon it to be simply the impressions of adjoin- ing cells. Preparations similar to fig. 3 clearly disprove this, and the basement membrane, when it can be demonstrated, is far from a “‘derb” structure, as will be shown further on. Kolliker* says—‘‘ The ends of the enamel cells taken from the enamel present different appearances. Some are simply cut off squarely, others possess smaller (myself, Hertz) or larger (Waldeyer) clear layers of the same breadth as the cells (the enamel fibres in process of formation), still others, finally, have pointed ends, with or without such layers (Tomes, Waldeyer, Hertz). I consider these ends, which I also have seen, as artificial products—that is, as accidentally detached parts of the yet unfinished enamel fibres.” If Kolliker had seen them on the firm dense membrane, as in fig. 3, or fie. 2, he could not have held this opinion. An extended and careful study leaves no room for doubt that this membrane, forming in many cases the cuticula of placoids and the cuticula dentis of both mam- malia and fishes, is made by the metamorphosed ends of the enamel cells. But the cuticula has not always precisely this structure either upon the tooth or on the placoid ; apparently more or less of the gso- called enamel cells may enter into its formation. This, at least, is certain, the cuticla, or “ Schmelz oberhiutchen,” may not only have upon its surface the “cell markings,” but it may be formed of entire cells (or at least of enough to include the nuclei) which have under- gone a greater or less differentiation into horny tissue, obscuring more or less completely the outlines of the nuclei. Such a cuticula is shown wm situ on the placoid represented in fig. 4. It is entire upon the under surface of the scute, which is more protected; upon the upper side fragments only are left. A high immersion lens showed distinctly on parts of the membrane, the outlines of cells and their nuclei (fig. 5) and the membrane could be traced into the columnar layer of epithelial cells at the base of the spine. The cuticula of the mammalian tooth has several times been found * Kolliker, “‘ Handbuch der Gewebelehre,” p. 385. 160 E. Nunn. On the Development of [June 15, to have the same structure, and it has been possible, in transverse and longitudinal sections, to trace the gradual transition of the enamel cells into a perfectly homogeneous membrane (figs. 6 and 7, Plate 3), the cylindrical cells growing shorter as they approach the crown of the tooth, until, instead of being columnar, they are almost square, and finally flattened, and at last the outlines of the cells quite disappear, and there is left a perfectly homogeneous membrane. These changes are not easy to follow; im many preparations it is impossible to make anything out, and the drawings+have been made from most fortunate preparations selected from some thousands of sections prepared in various ways. The cuticula dentis, then, is formed by the metamorphosis of more or less of the enamel cells, and this metamorphosis may begin before any calcification of the underlying dental tissues. In this stage it has been frequently taken for the ‘‘ newly-formed layer of enamel,” for the ‘‘basement membrane,” and for the ‘“ first-formed layer of dentine.” 2. The Basement Membrane and Membrana Preeformativa. The mucous membrane of the Plagiostomes immediately under the epithelium is frequently more or less laminated, and one of these laminz bounding the surface of the mucosa has often been described as the “derb” basement membrane. But being only the outer one of a series of lamin, it represents the basement membrane as simply the margin of the mucosa, with no definite and special structure of its own. In order to get at the special structure of the surface of the derma supposed to be bounded by a basement membrane, it is well! first to examine portions which have a cellular rather than a distinctly laminated structure, and it is absolutely necessary that the sections should be perfectly vertical to the surface of the derma, the study of which will be much facilitated if the epithelial cells have, for the most part, been previously washed away. Fig. 8 is a vertical section of the dermis and of the base of a young tooth of the skate. The section being very thin and perfectly ver- tical, the structure of the cellular eanalae dermis stands ont in strong contrast to the perfectly clear and dense basement membrane, brought into even greater relief by the cleft (cl.), and by its absence from a part of the derma where it has been accidentally torn away. The basement membrane runs up from the derma over the surface of the young tooth, which, as yet, has no calcitic deposit, though there is a thick dentinal basis under the basement membrane, much thicker than the future enamel. It is finely granular throughout, showing no differences of structure in different parts, no signs of tubules, though 1882.] the Enamel of the Teeth in Vertebrates. 161 there is generally a faint granular striation running from the surface of the pulp to the basement membrane. Fig. 9 is a portion of a vertical longitudinal section of the young tooth of a thornback hardened in alcohol. The basement membrane could be traced from the derma quite up to the apex on one side; it was quite invisible upon the other side, which was cut slightly obliquely to the surface of the tooth. The series of sections, how- ever, furnishing the requisite conditions showed it to be there also. But in this section (fig. 9) not the slightest trace of it can be detected, and, but for subsequent sections, one could declare it did not exist. If, at any time before calcific deposit, a young tooth* be carefully cut out, with a portion of the surrounding derma, and the cells of the enamel organ be washed away, examination with the microscope will show its outer surface to be quite smooth and dense,+ and a clear strong homogeneous membrane, enveloping granular and cellular contents, can be pretty clearly made out. Pressure of the coverslip, causing the membrane to split, will bring out still more clearly the different structures of the perfectiy clear granular transparent dense membrane, and the enclosed cellular pulp or granular dentinal basis upon its surface. If the tooth be now hardened in alcohol and cut into thin sections, those which are perfectly vertical will show the basement membrane of the small portion of adherent dermis to run up over the tooth as shown in fig. 8. It is exceedingly delicate and perfectly transparent, and when the surfaces of the tissues are cut at all obliquely, it is as invisible as a thin film of glass. Hence it can seldom be followed over the entire surface of even the most perfect section, and it cannot, like the cuticula in a somewhat older tooth, be separated by the use of acid. When a small bit is fortunately torn away with needles, it shows no “cell markings” upon it, but is per- fectly smooth. If a young tooth papilla be treated in this way, the basement mem- brane will be found quite upon the cellular pulp, a few cells of the enamel membrane frequently adhering to its surface. If the section be teased slightly and the membrane broken, the short outlines of its ends, sometimes standing out alone (Plate 4, fig. 19, b. m.), and its clear dense structure appears in marked contrast with the granular underlying pulp. When the teeth, im situ, have been treated with chromic acid for a week or more, as is generally done, and then imbedded, and cut very much at random as is necessarily the case, 1t is a great chance if any trace of basement membrane can be seen. The enamel * A small tooth of one of the Plagiostomes answers best—say of the thornback. + At this stage the cuticula, if its formation be begun, is generally brushed off along with the enamel cells. VOL. XXXIV. M ole a E. Nunn. On the Development of [June 15, cells may appear to lie quite upon the cellular pulp; but if the section be good and sufficiently thin, a close examination will often reveal the membrane upon some part or other of the surface of the pulp. Fig. 11 represents a section of a tooth papilla a little more advanced. A thin layer of dentinal basis (neither dentine nor enamel) covers the © surface of the pulp, and over all is the basement membrane which, in one part, has fortunately been torn away with needles, and is shown to have a very different appearance from the cuticula, which later is developed above it, and can easily be isolated or “raised up ” by acid. In the Plagiostomes the soft dentinal basis under the basement membrane increases in thickness to a considerable depth before the beginning of calcific deposit, and thus affords a better opportunity for the study of the behaviour of the basement membrane, as well as for that of the formation of enamel and dentine, than is met with in mammalian teeth. It frequently becomes two or three times as thick as the future enamel will be before the occurrence of any calcification, which at last begins at the surface and proceeds inwards. The base- ment membrane of the derma can readily be traced running up over the surface of the young tooth at all stages, while the tissues are still soft. But its fate, after calcification begins, is more difficult to follow ; whether it calcifies or remains uncalcified, cannot of course be deter- mined from acid preparations, and from these alone it would seem that thin sections could be made. Hxperiment has proved, however, that alcoholic preparations of considerably calcified young teeth can, by sacrificing a razor for each section, and coming first upon the soft parts, then upon the hard, be cut into fine sections. These sections throw great light upon the manner of calcification and the relation of the soft and hard parts; they show, too, that after the removal of the cuticula no wncealcified membrane remains upon the surface of the tooth, but owing to the great refractive power of the calcified portion, it seemed impossible to demonstrate a thin membrane on its margin. The strong appearance of a membrane might still be simply the re- fractive lines. The persevering and careful use, however, of diluted nitric acid added under the coverslip, brings clearly into view the base- ment membrane upon the outer surface of the tooth; it is not “raised up,” however, as is the case with the cuticula, if it has not been pre- viously removed, and is an altogether different and much more delicate structure than the latter membrane. Fig. 12 is a section prepared in the way just described, showing the basement membrane, and at one place a fragment of the cuticula adhering toit. Teeth far enough developed to show a distinctly differentiated enamel layer with a broad band of dentine underneath, can, with sufficient skill, be cut into the thinnest sections; and, if these are vertical, the basement mem- brane may always be demonstrated on their surface or under the cuticula if it remain adherent. 1882.] the Enamel of the Teeth in Vertebrates. 163 Thus the basement membrane may be demonstrated running up from the surface of the dermis over the tooth papilla and young tooth in all its stages. The whole tooth is formed under the basement membrane and the entire growth is from the side of the pulp. The calcification begins at the surface of the tooth, and there is no addition made outside the part already calcified, no “newly formed layer of enamel” appearing as a membrane on the surface, the tooth receiving its additions from the side of the pulp only. 3. The Origin of the Enamel. In its early stage the enamel cannot be distinguished from the dentine. It is formed by a later differentiation of a dentinal basis, which is the same for both dentine and enamel, and the nature of which can be best made out by teasing out, in salt solution, the young still soft tooth of some Plagiostome—say ofa skate. It will then be found that the granular basis is formed by the regular arrangement side by side of the slender processes of the odontoblasts (fig. 13), and that they extend right up to the basement membrane, occupying the place of the future enamel as well as of that of the dentine; and it is these regularly arranged processes which cause the striz often de- scribed. If the tooth be quite young, the processes are easily sepa- rated and seen in connexion with the cell from which they proceed, and they are frequently branched. If the tooth be left in ammonium bichromate for a few hours. or even in salt solution, the processes, as well as the cells, can be more readily isolated. Indeed, on simply breaking through the basement membrane many of them escape and will be found outside. When the tooth becomes a little older, and the basis thicker, the processes appear glued together by an intercellular matrix as it were, so that the whole basis appears as one mass, the constituent parts of which are separated with difficulty, and only by prolonged maceration in ammonium bichromate. But, by this time, the deposition of calca- reous Salts begins ; and, soon after, the differentiation of the mineralised portion into dentine and enamel. The fact that the processes of the odontoblasts extend quite up to the basement membrane, occupying the place of the future enamel, admits of only one view with regard to the origin of the enamel, and explains the existence of tubules which have often been described as extending into it, and continuous with the dentinal tubules. The mode of calcification and the nature of dentine will be discussed in a future paper. The results arrived at in this paper may be summed up as follows :— 1. The cuticula dentis is formed by the metamorphosis, either in whole or in part, of the enamel cells, which have nothing whatever to do directly with the formation of the enamel. In its early stages M 2 164 E. Nunn. On the Development of [June 15, the cuticula has frequently been considered as “the newly-formed layer of enamel” and also as the basement membrane. 2. The basement membrane may be demonstrated upon the surface of the tooth-papilla and upon the tooth in all stages of development. It becomes calcified with the other hard tissue of the tooth and cannot be separated by acid. 3. The enamel, like the dentine, owes its origin to the odontoblasts, the processes of which, in an early stage, may be traced quite up to its outer edge. EXPLANATION OF FIGURES. The same letters have been employed to mark corresponding structures in the whole series of figures. The figures were drawn by the aid of the camera. b. m. Basement membrane. ce. Cuticula dentis. cal. Limit of calcification. cl. Cleft formed by pressure of coverslip, dissecting needle, &e. d. Dentine. der. Derma. di. Disks. e. Enamel. e. c, Enamel cells. e. m. Enamel membrane, ep. Epithelium. e. 1. External layer of the enamel organs. e. 0. Enamel organ. _ f. Dentinal basis. i. l. Intermediate layer of the enamel organ. in. Involution of epithelium (enamel organ). j. Jaw. j.¢. Cartilage of jaw. n. Neck of enamel organ. o. Odontoblasts. p. Pulp. pr. Processes of odontoblasts. r. Reticulation. ri. Ridges. s. Space left by shrinkage of tissues. t. p. Tooth papilla. t. Tubule. uw. Limit of enamel layer. Zeiss Oc. III was employed for ali the sections. The objective is stated for the different figures. Figure 1. Membrane lying between enamel and enamel cells of molar of rabbit. A. En face view, the membrane is seen to be not homogeneous, but the reticulation and enclosed disks have a different structure. B. Side view which shows the reticulation to be elevated into ridges. Two enamel cells and portions of others remain attached, fitting in be- tween the ridges. Obj. ~ immersion. cae West New A ‘ eens ra a vas uo » it Vol. 3 4. PL, : ‘baie ey * , ; io! nian Ait h : Proc. Roy. Soe. West Newmam & C° Ga. ti . ‘ \ ' ~ . 1 i J OU. Soc. V ue poe Meeeess ees (E =. -——— pr. _— OD ” West Newman & iG 1882. | the Enamel of the Teeth in Vertebrates. 165 Figure 2. Part of transverse section of lower incisor of rabbit, showing the mem- brane (cuticula dentis) lying between enamel and enamel cells. B. shows an en face view of a portion of c. Obj. 4; Immersion. Figure 3. A portion of vertical section of young tooth of an adult Raia clavata (thornback), showing the formation of the cuticula by the ends of the enamel cells. Obj. ;4¢ immersion. Figure 4. Longitudinal section of spine from a fin ray of the thornback, showing the cuticula entire upon the under surface of the spine, with only frag- ments left upon its upper surface. Obj. 2 inch. Figure 5. A portion of the cuticula of fig. 4, showing the outlines of the cells and their nuclei. Obj. ~; immersion. Figure 6. A portion of a transverse section of the lower incisor of rabbit, a short distance below the gum. The enamel extends over the side of the tooth no farther than wv. A thick layer covered the front of the tooth which, except at one point, has disappeared. Obj. 4 immersion. Figure 7. A portion of a longitudinal vertical section of the upper small incisor of a rabbit. e¢.m., 1, 2, 3, 4, 5, are cells of the enamel membrane drawn at intervals, showing their gradual change as they approach the crown of the tooth until, on its exposed portion, they form a homogeneous mem- brane. Obj. F. Zeiss. (The following seven sections were from teeth preserved in alcohol, without acid.) Figure 8. Vertical section of dermis and young tooth of Raia batis (skate). The basement membrane upon the derm stands out remarkably clearly, and could be seen running up over the young tooth quite to its apex. Obj. F. Zeiss. Figure 9. The apex of vertical longitudinal section of tooth of a thornback, showing the basement membrane upon that edge which was cut exactly vertical to the surface of the tooth. No basement membrane can be distin- guished upon the other edge, it being cut obliquely to the surface. Obj. F. Zeiss. Figure 10. A portion of a vertical longitudinal section of a tooth papilla of a young skate. The cellular pulp still extends quite up to the basement membrane, which is more marked as the lines of the cells of the pulp appear to run at right angles to it. Obj. F. Zeiss. Figure 11. Portion ofa vertical section of a tooth papilla of a thornback, in which a thin layer of dentinal basis is seen under the basement membrane, a small piece of which has been fortunately torn away with needles. Obj. F. Zeiss. Figure 12. Portion of section of a tooth of the skate. Calcification has proceeded from the surface as far as cal. The cracks in the calcified portion are produced in cutting. Most of the dentine is still uncalcified. Nitric acid was added under the coverslip and has brought out more clearly the basement membrane, which, however, never in any stage of the tooth can be raised up by acid, as can the cuticula which lies over it, a fragment of which adheres atc. Obj. F. Zeiss. Figure 13. A portion of young tooth of a thornback, teased out in salt solution, showing the dentinal basis to be formed by processes of the odonto- blasts arranged closely side by side. Obj. F. Zeiss. Figure 14. Part of one of a series of vertical sections of tooth papilla of skate. In B, cut vertically, the basement membrane 6. m. is distinctly visible. In A, cut more obliquely, it is not seen. Obj. F. Zeiss. 166 Mr. A. V. Harcourt. [June 15, XVIII. “On an Instrument for Correcting Gaseous Volume.” By A. VERNON Harcourt, M.A., F.R.S. Received June 13, 1882. This instrument has been devised in order to facilitate the correc- tion of the observed volume of a mass of gas, measured at any common temperature and pressure, to the volume the gas would occupy if measured under standard conditions. A reading of the instrument furnishes a number which serves for the making of this correction, and stands instead of readings of the barometer and of the thermometer, and a reference to a table of the tension of aqueous vapour at different temperatures. Ve 'O aa \o oo o The instrument consists of two small glass tubes standing side by side; the one is open above, having been drawn out and bent down- 1882.] Onan Instrument for Correcting Gaseous Volume. 167 wards to exclude dust; the other tube terminates in a bulb, whose capacity is about four and a half times that of the tube. The two tubes are connected below by means of caoutchouc tubing with a small cylinder containing mercury, closed above by a leather cap, which can be pressed down by a button attached to a screw moving in a fixed socket. When the screw and button are lowered the mercury rises in both tubes. The ends of the tubes and the reservoir of mercury are contained in a square box, upon the bottom of which they rest, and whose top carries the socket in which the screw turns. At the back of the box is a wooden upright which supports the tubes. The tube which terminates in a bulb is graduated and figured so as to mark the capacity of the bulb and tube, down to each line of graduation. In technical measurements of coal gas it is still customary to take for the standard conditions an atmospheric pressure equal to 30 inches of mercury and a temperature of 60° F. The instrument here figured has been made for correcting to these conditions. The capacity of the bulb and stem down to the first line is 3:1 cub. centims., and that of the graduated portion of the stem is 0°7 cub. centim. The bulb and stem have been charged first with a minute drop of water and then with a quantity of air, occupying under standard conditions 31 cub. centims., the stem below this level being filled with mercury. This volume is marked on the instrument as 1000, the unit taken being. 54, cub. centim. The top line of the graduation marks a capacity of 3:1 cub. centims., and is figured 930, this being the smallest volume to which the inclosed air is likely to be reduced by low temperature and high atmospheric pressure. The maximum volume to which the inclosed air is likely to be expanded may be taken at 3°8 cub. centims., and accordingly the lowest line of graduation marked on the stem is 1140. To use the instrument the pressure of the screw on the mercury is increased or relaxed until the level of the mercury is the same in both tubes. A reading is then made on the graduated stem, and represents the volume occupied at the actual atmospheric pressure and temperature by a mass of air in presence of water which, under standard conditions, occupies a volume 1000. Any volume of gas measured in a gasholder or registered by a meter, under the same conditions, may be corrected to its true volume, under standard con- ditions, by multiplying by 1000 and dividing by the number read upon the instrument. When the standard conditions adopted are 0° C. and 760 millims. pressure the bulb is made somewhat larger, so that the 1000 gradua- tion comes near the top of the stem, and the graduations are continued downwards to 1230. The name proposed for this instrument which serves to correct the measure of a gas, is aerorthometer. 168 [June 15, XIX. “Sunspots and Terrestrial Phenomena. I. On the Varia- tions of the Daily Range of Atmospheric Temperature, as recorded at the Colaba Observatory, Bombay. II. On the Variations of the Daily Range of the Magnetic Declination, as recorded at the Colaba Observatory, Bombay.” By C. CHAMBERS, F.R.S., Superintendent of the Colaba Observa- tory. Received May 30, 1882. [Publication deferred. | XX. “Ona Method of Tracing Periodicites in a Series of Ob- servations when the Periods are unknown.” By VINAYEK NaRAYEU NENE, First Assistant at the Colaba Observatory, Bombay. Communicated by C. CHAMBERS, F.R.S. Re- ceived May 30, 1882. [Publication deferred. ] XXI. “On the Causes of Glacier Motion.” By W. R. BROWNE, M.A., late Fellow of Trinity College, Cambridge. Com- municated by Professor STOKES, Sec. R.S. Received June 1, 1882. [Publication deferred. ] XXII. “The Life History of the Rmgworm Fungus (7Trico- phyton tonsurans).” By M. Morris and Dr. G. C. HENDER- soN. Communicated by Professor J. 8. BURDON-SANDERSON, M.D., F.R.S. Received June 12, 1882. [Publication deferred. | XXIII. “On the Nerves of the Epiglottis.” By WILLIAM Sriruine, M.D., Sc.D., Regius Professor of the Institutes of Medicine (Physiology) in the University of Aberdeen, and G. Durrus. Communicated by Professor T. H. HUXLEY, F.R.S. Received June 14, 1882. [Publication deferred. ] 1882.] Presents. 169 XXIY. “On the Action of certain Reagents on Coloured Blood Corpuscles. Part I. Blvod Corpuscles of the Frog and Newt.” By WiLLiAM StTiRuine, M.D., Sc.D., Regius Pro- fessor of the Institutes of Medicine (Physiology) in the University of Aberdeen. Communicated by Professor T. H. Huxuery, F.R.S. Received June 14, 1882. [Publication deferred. | The Society adjourned over the Long Vacation to Thursday, November 16th. Presents, June 15, 1882. Transactions. Ballaarat :—School of Mines. Annual Report 1882. 8vo. Ballaarat 1882. The School. Berlin:—K. P. Akademie der Wissenschaften. Sitzungsberichte. I-X VII. 8vo. Berlin 1882. The Academy. Cambridge (U. 8S.) :—Museum of Comparative Zodlogy. Memoirs. Vol. VII. No. 2. Part II. 4to. Cambridge 1882. Bulletin. Vol. IX. Nos. 6-8. 8vo. Cambridge 1882. The Museum. Catania:—Accademia Gioenia di Scienze Naturali. Atti. Serie 3°. Tomo XV. 4to. Catania 1881. The Academy. Emden :—Natuforschende Gesellschaft. Jahresb. LX VI. 1880-81. 8vo. Hmden 1882. The Society. Falmouth :—Royal Cornwall Polytechnic Society. Annual Report. 1881. 8vo. Falmouth. The Society. Florence:—R. Istituto di Studi Superiori. Pubblicazioni. Il Commento di Sabbatai Donnolo sul Libro della Creazione. Castelli. 8vo. Firenze. 1880. The Institute. Frankfurt-a-Main :—Senckenbergische Naturforschende Gesell- schaft. Abhandlungen. Band XII. Heft. 3-4, 4to. Frankfurt-a- Main. 1881. Bericht. 1880-81. 8vo. Frankfurt-a-Main 1881. The Society. Gottingen :—K. Gesellschaft der Wissenschaften. Abhandlungen. Band XXVIII. 4to. Gottingen 1882. The Society. Graz :—Naturwissenschaftlicher Verein fiir Steiermark. Jahrg. 1881. Mittheilungen. 8vo. Graz 1882. The Union. Hamburg :—Verein fiir naturwissenschaftliche Unterhaltung. Verhandlungen, 1877. 8vo. Hamburg 1879. The Union. Heidelberg :—University. 19 Inaugural-Dissertationen, &c. Ato. and 8vo. Anzeige der Vorlesungen, 1881-2. 8vo. Heidelberg. The University. 170 Presents. [June 15, Transactions (continued). London :—Anthropological Institute. Journal. Vol. XI. Ne. 4. Svo. London 1882. The Institute. Chemical Society. Journal. No. 235. June 1882. 8vo. The Society. Kast India Association. Journal. Vol. XIV. No. 2. 8vo. London 1882. The Association. Institution of Civil Engineers. Private Press. 1881-2. Nos. 5-14. Svo. The Institution. Pharmaceutical Society. Pharmaceutical Journal. January to 1882. The Society. Royal Geographical Society. Proceedings. January to June 1882. 8vo. London. The Society. Royal United Service Institution. Journal. Vol. XXV. Appen- dix. Vol. XX VI. No.115. 8vo. London 1882. The Institution. Society of Antiquaries. Archzologia. Vol. XLVII. 4to. London 1882. The Society. Society of Arts. Journal. Vol. XXX. Nos. 1540-42. 8vo. London 1882. The Society. Manchester :—Geological Society. Transactions. Vol. XVI. Parts 14, 15. 8vo. The Society. Moscow :—Société Impériale des Naturalistes. Bulletin. 1881. No. 3. 8vo. Moscow 1882. The Society. New York:—American Geographical Society. Bulletin. 1882. No. 1. 8vo. New York. The Society. Paris :—Ecole Normale Supérieure. Annales. 2me Série. Tome XI. No. 3. 4to. Paris 1582. The School. Muséum d’Histoire Naturelle. Nouvelles Archives. 2me Série. Tome IV. 4to. Paris 1881. The Museum. Philadelphia :—Academy of Natural Sciences. Proceedings 1881. Parts 1-3. 8vo. Philadelphia 1881-2. The Academy. American Philosophical Society. Proceedings. Vol. XIX. No. 109. 8vo. Philadelphia 1882. The Society. Franklin Institute. Journal. Srd Series. Vol. LXXXIII. No. 6. 8vo. Philadelphia. The Institute. Rome:—Accademia Pontificia. Atti. Anno XXXIV. Sessioni IV eV. 4to. Roma 1881. FProcessi Verbali. Anno XXXIV. Sessione 6. Anno XXXY. Sessioni 1-5. 8vo. The Academy. R. Accademia dei Lincei. Transunti. Vol. VI. Fasc. 12. 4to. Roma 1882. The Academy. Turin: —R. Accademia delle Scienze. Atti. Vol. XVII. Disp. 4. Svo. Torino. The Academy. Vienna :—Anthropologische Gesellschaft. Mittheilungen. Band XI. Heft. 3-4. 4to. Wien 1882. The Society. 1882.] Presents. 171 Transactions (continued). K. K. Geologische Reichsanstalt. Abhandlungen, Band XII. Heft 3. 4to. Wren 1882. Jahrbuch. Band XXXII. No. 1. Svo. Wiew 1882. Verhandlungen, 1882. Nos. 1-7. 8vo. The Institution. Osterreichische Gesellschaft fiir Meteorologie. Zeitschrift. Band XVII. Juni-Heft. 8vo. Wien 1882. The Society. Wellington :—Colonial Museum and Geological Survey. Manual of the Birds of New Zealand. 8vo. New Zealand 1882. Annual Report of the Museum and Laboratory, 1880-1. 8vo. New Zealand 1882. The Museum. Observations and Reports. Bristol :—‘‘ Dockismg River Avon.” Reports by T. Howard, R. Rawlinson, H. J. Marten, and G. J. Symons. | Mr. G. J. Symons, F.R.S. London :—Meteorological Office. Daily and Weekly Weather Reports. January to June, 1882 (in separate sheets as published) and Volume for July to December, 1881. The Office. Royal Mint. Annual Report of the Deputy-Master, 1881. 8vo. London 1882. The Hon. C. W. Fremantle. Malta:—Public Library. Report on the Phceenician and Roman Antiquities in the Group of the Islands of Malta. 4to. Malta 1882. The Library. Milan :—R. Osservatorio di Brera. Pubblicazioni N. XX. 4to. Milano 1882. The Observatory. Moscow :—Observatoire. Annales. Vol. VIII. Livr. 1. 4to. Moscow 1882. The Observatory. Paris :—Ecole des Ponts et Chaussées. Observations sur les Cours d’Kau et la Pluie. 1880. folio. Versazlles. Résumé des Obser- vations Centralisées. 1880. 8vo. Versailles 1882. M. le Directeur. Prague :—K. K. Sternwarte. Beobachtungen. 1881. 4to. Prag. The Observatory. Sydney :—Observatory. Results of Rain and River Observations. 8vo. Sydney 1882. The Observatory. Upsala :—Observatoire Meétéorologique de VUniversité. Bulletin Mensuel. Vol. XIII. 4to. Upsal 1881-82. The Observatory. Vienna:—K. Akademie der Wissenschaften. Anzeiger. Jahrg. 1881. Nrs. 14—28. Jahrg. 1882. Nrs. 1—9. 8vo. The Academy. 172 Presents. [June 15, Journals. American Journal of Otology. Vol. III. Nos. 3, 4. Vol. IV. Nos. 1, 2. 8vo. New York and Boston 1881-2. The Editor. American Journal of Science. January to May, 1882. 8vo. New Haven 1882. Analyst. January to June, 1882. 8vo. London 1882. The Editors. Annales des Mines. 8e Sér. Tome I. Livr. 1. 8vo. Paris 1882. L’Ecole des Mines. Atheneum. January to June, 1882. 4to. London. The Editor. Builder. January to June, 1882. folio. London. The Editor. Chemical News. January to June, 1882. 8vo, London. The Editor. Educational Times. January to June, 1882. 4to. London. The College of Preceptors. Electrician. January to June, 1882. 4to. London. The Editor. Electrical Review. January to June, 1882. roy. 8vo. London. The Editor. Electricien. Tome II. Nos. 13-24. 8vo. Paris 1881-82. Mr. W. Spottiswoode, P.R.S. Hodrological Journal. January to June, 1882. The Editor. Indian Antiquary. Vol. XI. Part 132. 4to. Bombay 1882. The Editor. Journal of Science. Vol. III. Nos. 95, 96. Vol. IV. Nos. 97-102. Svo. London. The Editor. Mondes (Les). Janvier—Juin, 1882. 8vo. Saint-Denis. M. Abbé Moigno. Nature. January to June, 1882. 4to. London. The Editor. Notes and Queries. January to June, 1882. 4to. London. The Editor. Observatory. January to June, 1882. 8vo. London. The Editors. Oxford University Gazette. Supplement to No. 425, containing Report on the University Observatory. The Savilian Professor of Astronomy, Revue Politique et Littéraire. Janvier-Juin, 1882. 4to. Paris. The Director. Revue Scientifique. Janvier-Juin, 1882. 4to. Paris. The Directors. Scientific Roll. Vol. I. Part 1. Nos. 1-6. 8vo. London. Mr. W. Spottiswoode, P.R.S. Scottish Naturelist. No. 46. 8vo. Edinburgh. The Editor. Symons’s Monthly Meteorological Magazine. January to April, 1882. 8vo. London. The Editor. Van Nostrand’s Engineering Magazine. June, 1882. 8vo. New York. The Editor. 1882.] | On the Propagation of Heat by Conduction, &c. 173 Carvallo (J.) Loi des Nombres Premiers. 8vo. Meulan. The Author. Gladstone (J. H.) F.R.S. Michael Faraday. Autorisirte Ueber- setzung. 8vo. Glogau. The Author. Haupt (Ottomar) Bi-metallic England. 8vo. Paris 1882. The Author. Jackson (B.D.) Vegetable Technology. 8vo. London 1882. Mr. G. J. Symons, F.R.S. Kalischer (S.) Ueber die Molecularstructur der Metalle und ihre Beziehung zur elektrischen Leitungsfahigkeit. 8vo. The Author. Leeds (A. R.) Relative Purity of the City Waters in the United States. 8vo. New York. Upon the Compounds of the Aromatic Bases with Metallic Salts, with a Note upon Thiocarbanilide. 8vo. New York. The Author. Leeds (A. R.) and Edgar Everhart. A Method for the Analysis of Mustard. 8vo. New York. The Authors. Quatrefages (M. de) For. Mem. R.S. Note sur Charles Darwin. 4to. Paris. The Author. Russell (H.C.) Transit of Mercury. 8vo. Sydney 1882. The Author. Steel (James) The Exact numerical Quadrature of the Circle effected regardless of the Circumference. 8vo. London 1881. The Author. Lacaze-Duthiers (H: de) Histoire de la Laura Gerardie. 4to. Paris 1882. The Author, per Professor Huxley, F.R.S. “Experimental Researches on the Propagation of Heat by Conduction in Bone, Brain-tissue, and Skin.” By J. S. LomBarp, M.D., formerly Assistant Professor of Physiology in Harvard University. Communicated by Dr. Brown- SEQUARD, F.R.S. Received October 1. Read November 17, 1881. Introduction. The question of the precise degree of the conductivity for heat of the tissues lying between the surface of the brain and the onter sur- face of the integument is, of course, of the first importance in study- ing the possible effects on the exterior of the skin of changes of temperature occurring in the superficial layers of the cerebrum; and the question of the degree of conductivity of brain-tissue itself is of great importance with reference to the extent to which propagation through the cerebral mass of thermal changes occurring in a single point or tract of the brain may take place. _ ‘ 174 Dr. J. S. Lombard. On the Propagation of Many years ago the writer made a few (not, however, very exact) experiments on the conductibility of bone, which did not lead him to anticipate any serious obstacle in the skull to the outward transmission of heat from the brain. Moreover, the experiments of Professor Tyndall on conduction in elephant’s tusk, whalebone, cow’s horn, &c., pointed to tissues of this nature as being better conductors than sealing-wax and bees’-wax, on both of which substances the writer had made many experiments, and which he knew would conduct suffi- ciently well to enable one, with delicate apparatus, to appreciate a slight change of temperature through a thickness of them greater than the average thickness of the skull. In order to make the theoretical conditions of transmission to the outer surface as unfavourable as could, with any justice, be warranted, the writer selected the conductivity of paraffine as the representative of the conductivity of bone and skin combined, and founded on this basis his line of reasoning respecting the effect of slight variations of the temperature of the surface of the brain on the temperature of the exterior of the skin. But in June, 1880, M. Francois Franck, in a communication made to the Société de Biologie, gave the results of experiments made by him on the conductivity of bone, skin, and brain-tissue, which placed the whole subject in a new light.* M. Franck stated that a difference of temperature of 1° C. failed to make itself felt at the end of fifteen minutes through 3 millims. of bone, using a thermometer detecting 0°°05 C. With 2° C. difference of temperature a doubtful change of 0°:05 C. was obtained; indeed, it required a difference of 4° C. to effect a change of 0:2°. Using thermo-electric apparatus detecting 0°°01333 C. (75), M. Franck failed to find any indication of a transmission of heat with a difference of temperature of 1° C. Skin he found to conduct about the same as bone, while on the contrary, through 30 millims. of brain-tissue transmission readily took place. As it is difficult to conceive of rises of temperature in the brain, due to changes of mental activity, measured by whole degrees Centi- grade, M. Franck’s experiments on bone and skin, if correct, would peremptorily end all question of the possibility of changes of tempera- ture in the superficial layers of the brain, arising from psychical pro- cesses, affecting directly the outer surface of the scalp. So able an experimenter as M. Franck making the above statements, the writer felt himself obliged to go over the whole ground thoroughly, although convinced at the outset that, as regards bone at least, M. Franck was in error. Accordingly, the writer devoted himself for the space of nearly six months entirely to the experimental examination of the conduction of heat in the tissues in question, drawing his * “ Gazette Médicale,’ July 3, 1880. Heat by Conduction in Bone, Brain-tissue, and Skin. 175 resuits from over 700 experiments picked out from a still larger number. It will be seen that M. Franck is quite correct as regards the comparatively good conductivity of brain-tissue, but in error as concerns the conductivity of bone and skin.* In approaching this subject, we have at the start, to take into con- sideration what rises of temperature are likely to occur in the brain as the result of increased mental action of different kinds. The only direct information in our possession concerning the pro- duction of heat in the brain during increased cerebral activity is furnished by the well-known admirable experiments of M. Moritz Schiff.t As M. Schiff did not reduce his results to a thermometric standard, we are left wholly in the dark as to the degree of the rises of temperature noted by him. It has been rather gratuitously assumed, because M. Schiff did not calculate the thermometric values of the deflections of his galvanometer, that, therefore, these values must have been exceedingly small—too small, in fact, to be easily estimated—and, consequently, that the rises of temperature in the brain were propor- tionally feeble. But a knowledge of the general nature of the galvano- meter and thermo-piles employed by M. Schiff, together with a careful study of the experiments themselves, have failed to prove to the writer that M. Schiff was experimenting with any extraordinary degree of delicacy. To begin with, the electromotive force of the piles employed was not great. Although M. Schiff mentions certain alloys of Rollman, all the results of his experiments on the brain appear to have been obtained with single pairs of either the antimony-bismuth, copper- bismuth, or platinum-German silver combinations. Now the electro- motive forces of these combinations may be expressed by 35, 24, and 4°5 respectively, while the electromotive forces of the combinations principally used by the writer are represented by 119°5 and 210. The galvanometer used by M. Schiff was a combination of the principles of the Meyerstein and Wiedemann instruments. These instruments are certainly not superior, even if they are equal, in sensitiveness to the Thomson galvanometer, which the writer has usually employed. The perturbations, arising from external causes, mentioned by M. Schiff, may occur when instruments of the kind are not adjusted to any very great degree of delicacy, and therefore are not necessarily proofs of high sensitiveness. But the principal proof that the galvanometric deflec- tions did not represent very minute values of temperature is to be found in the account of the experiments themselves. It is there stated that with single pairs of German silver and platinum, implanted in * The question of the specific heat of the tissues has been purposely omitted, as nothing definite is known on this important point. Yet the writer is strongly in- clined to believe that the differences in the rate of thermal transmission in these tissues are in part owing to differences in their specific heats. + “Archives de Physiologie,” t. III, 1870, p. 6. 176 Dr. J. 8. Lombard. On the Propagation of corresponding points of the two hemispheres of large dogs, the perma- nent galvanometric deflections, showing the difference of temperature between the two points, were about 15° of the scale, which was divided into millimetres.* Now it is very unlikely that the temperatures of two points of opposite sides of the brain would, on an average, approxi- mate each other nearer than by 0°03 C.,—this after making full aliowance for the good conductivity of brain-tissue. In practice it is difficult to find in the different tissues, unless the points examined are within a centimetre of each other, a nearer approach to equality than’ the difference just given. Of course, still smaller differences may be met with by accident, but one cannot count upon finding them ata venture. The dogs are specified as large, and, indeed, in one place,+ M. Schiff gives the distance between the two points examined. In this case each pile was 15 millims. from the longitudinal median line ; the two points examined were consequently at least 30 millims. apart. We may assume then that the 15° of the galvanometer did not repre- sent less than 0°03 C.; therefore 1° of the galvanometer was equal to 0°-002 C. Now the simple odour of food with these animals caused deflections of 6° or 7°, equal to 0°°012 U. to 0°-014 C.,+ and the masti- cation of food increased these figures to 12° and 14° of the galvano- meter, equal to 0°:024 C. and 9°:028 C. It must, however, be borne in mind that these deflections did not by any means represent the total rise of temperature, but only the difference of rise between the two points examined. All M. Schitf’s results are in fact relative, based on the assumption that one of the two points examined would rise in tem- perature more than the other. ‘The use of the second pile with him was, in fact, principally for the purpose of keeping the primary deflec- tion of the galvanometer within the field of division on the scale, this pile thus serving as a compensating element. Now if a difference of rise of temperature of from 0°:012 C. to 0°:028 C. can be produced in the two hemispheres of the dog by the feeble cerebral action excited by the means given, it is certain that the thermal effects of the active exercise of the intellectual and emotional faculties of man may be estimated in, at least, tenths of a degree Centigrade. In the case of the experiments on fowls, we have further and still stronger proof, both that the apparatus was not excessively delicate, and also that the alterations of temperature were not so very small. In these experiments the thermo-electric arrangement was a small bar of bismuth 4 to 5 millims. long, in the two ends of which copper wires were buried to a depth of 1 millim., thus forming a thermo-electric junction at each end. As the copper wires were embedded in the bismuth to a depth of 1 millim., the two junctions were only from 2 to * Loc. cit., pp. 205, 207. 7 Beciicit.. peal. ft Loe. cit., p. 210. Heat by Conduction in Bone, Brain-tissue, and Skin. 177 3 millims. asunder. This close proximity of the two junctions must have very greatly diminished the delicacy of the arrangement, as a change of temperature at one junction would speedily be propagated to the other, setting up a reverse current in the latter.* Moreover, considering how good a conductor the brain-tissue is, a slight change of temperature in the point of brain in contact with one junction would very quickly be felt in the point in contact with the other junction, only 4 or 5 millims. of tissue intervening. Again, the galvanometer appears to have been less sensitive in these experiments than in those first cited. Yet M. Schiff obtained deflections of 12° to 14° from the insignificant psychical processes awakened in these animals by the exhibition of coloured papers, &c. It is very evident that, under such adverse circumstances as those specified, the absolute vise of temperature must have been considerable to have given any sort of a balance to one point over the other. Weighing all the evidence, then, there does not appear to the writer, to be the slightest reason why rises of temperature as high as 0°-3 C. should not occur in the brain of man during mental activity ; and elevations of 0°2 C. are certainly admissible; but the results which will be given in this paper are based on values of only 0°1 C. In the present experiments, instead of making use of differences of temperature of 1° C., or more, fractions of a degree have been em- ployed, as furnishing more conclusive proof of the possibility of the transmission of small differences of temperature, than could be afforded by the mere reasoning from larger to smaller values. We will consider first the apparatus employed, and then the methods of experimenting. Apparatus Hmployed. The instruments employed in testing the conductivity of the tissues under consideration, were as follows :— First.—Thermo-electric piles of from one to four pairs, composed of the antimony-zinc-cadmium alloy of Professor Moses G. Farmer, joined to bismuth as the other metal. The general construction of these piles has been fully described elsewhere,t and the only point of difference to which special attention need be called here, is, that whereas, in the description referred to, the conducting wires are represented as composed of copper strands, in the present instance they consisted of single fine copper wires 0:011 inch in diameter,—con- * See the writer’s remarks on reverse currents in piles, in “ Regional Temperature of the Head,” p. 6. It would have been almost utterly impossible to have tested the thermometric values of a pile so constructed,—at least such is the writer’s experience. + See the writer’s work “ Regional Temperature of the Head,’ p.19. The par- ticular alloy referred to above is the one designated “ No. 1.” VOL. XXXIV. N 178 Dr. J. S. Lombard. On the Propagation of ductors of this size and character being more manageable in packing the pile in paraffine in the manner to be described further on.* Second.—The writer’s rheostat and keys.+ Third.—Sir William Thomson’s galvanometer and scale. The greatest precaution must be taken to guard against the development, in any part of the apparatus, of accidental currents due to external thermal influences. Jor this reason, not only should every exposed junction of dissimilar—or even similar—metals be thoroughly protected with cotton-wool, but also the whole rheostat and the keys should be covered over with several layers of flannel, the plugs and keys being manipulated through a single thickness of the cloth, the other layers being momentarily raised for this purpose, and only at the very point concerned. Moreover, besides covering thickly with wool the binding screws of the Thomson galvanometer, the whole brass back of the instrument should be covered with flannel extending over the top and sides of the box containing the coil, and leaving only the glass front exposed. Methods of Hxperimenting. In earlier experiments (1867-68), in the case of bad conductors generally, provided the substances were of sufficient density, a form of apparatus similar to that used by Professor Tyndall in like investi- gations was employed;{ but in later, including the present, experi- ments, the methods adopted were different, anc in the present instance were of two kinds, both, however, the same in principle, and differing only in detail. The fundamental principle of both methods was the determination by means of a thermo-pile applied to one surface of the substance under examination,—say, for example, a piece of bone,—of the rapidity and extent of the change of temperature induced by conduc- tion in this surface by the contact of the opposite surface with a mass of water of a temperature differing in a slight but definite degree from that of the air in the immediate neighbourhood. At the outset, the whole of the piece of bone and the pile, if properly protected, will be at the temperature of the surrounding air; and when contact of one surface of the bone with the water takes place, this surface, assuming the temperature of the water gives rise to a thermal movement across the bone proportional to the difference of temperature between its two surfaces, and as these two surfaces are now respectively at the tem- peratures of the air and of the water, the movement is proportional to the difference between the latter two temperatures. * All possibility of currents caused by vibration of the conducting wires must be guarded against, hence larger wires than those specified, unless flexible like strands, are unsafe. + Op. cit., p. 22: t ‘ Heat considered as a Mode of Motion,” American ed., p. 233. Feat by Conduction in Bone, Brain-tissue, and Skin. 179 The first important points of the methods, are, therefore, the deter- mination and regulation of the differences between the temperatures of the air and the water. ‘These differences were determined by ther- mometers and thermo-piles (the latter being included in a circuit distinct from that of the pile used in testing for conductivity, and having their own galvanometer) placed in and near the water, the thermo-piles giving differences of 0°-02C. In practice it was found that, with care and patience, a difference of about 0°-125 C. between the air and water could be pretty steadily maintained long enough for the purposes of the experiments. It is, however, as a rule, better to reverse the ordinary order of things, and to take heat from the bone instead of furnishing heat to it, that is to say, it is better to have the temperature of the water lower by the desired amount than that of the air, than to have it higher, for the temperature of the water is more easily main- tained at a point differing slightly from the temperature of the air when the former is the lower of the two. If the temperature of the room in which the experiment is made be carefully watched, we may be certain that the temperature of the water will not exceed that of the air; the principal difficulty will be to keep the temperature of the water from falling too much below that of the air, and this end is best attained by withdrawing by suction, through a long tube held in the mouth, a small quantity of the liquid, and then returning it after a longer or shorter stay in the mouth.* A little practice will enable one to graduate, in this simple manner, with great nicety, the tempera- ture of asmali mass of water. ‘The amount of water usually employed was about one quart contained in an earthen vessel, exposing no more surface of water to the air than was necessary for the intro- duction of the different appliances used in the experiments. We have next to attend to the manner of applying the thermo- pile to the surface of the substance examined, and the precautions necessary in so doing; and here the two methods diverge, the one being applicable to the case of bone, and the other to that of brain and skin. We will consider each method in turn, taking first that which concerns bone. Bone. To begin with, the closest possible contact between the face of the pile and the bone must be aimed at. To this end, the surface of the bone is filed smooth, and the face of the pile having been accurately fitted to it, the two are closely and permanently attached to each other by means of a thin layer of shellac varnish applied to the face of the pile and to the surrounding ebonite casing. Firm and steady pressure must be maintained until the shellac is quite dry, as the interposition * Care must be taken not to alter sensibly the level of the water by withdrawing too large an amount, for reasons to be seen further on. N 2 180 Dr. J. 8. Lombard. On the Propagation of of minute bubbles of air will be fatal to successful experimenting. The pile and bone thus constitute a single piece. The next step is to isolate, as far as possible, the whole pile from all external thermal influences, except such as act through the piece of bone, or through the conducting wires of the pile. To effect this, the pile is enveloped in its whole length, and beyond to a distance along its conducting wires of several times its length, in layers of fine cotton-wool, which latter are afterwards steeped in melted paraffine. The casing thus formed extends laterally beyond the edges of the surface of the bone to which the face of the pile is attached. The first layer of cotton-wool is applied loosely, and the paraffine is com- paratively cool when poured upon the wool. The result of this is that the paraffine does not penetrate very deeply into this first layer, thus leaving a mass of loose wool, next the pile, entangling a certain amount of air, and this latter furnishes a strong safeguard against external influences. Of course, care must be taken that the attach- ment of the face of the pile to the bone be not broken by the heat of the paraffine. When all is complete the whole arrangement consists of a mass of paraffine-soaked cotton-wool some 60 millims. in length, one end of which is terminated by the piece of bone which protrudes from the centre of this end,* while from the other end emerge the conduct- ing wires of the pile, the pile thus forming the core of the mass, and being shut off laterally and at its upper end from the exterior by from 20 to 40 millims. of envelope. Two narrow strips of pasteboard, bound tightly by means of strips of flannel, on opposite sides of the mass, near its upper end, and brought together and tied so as to form a sort of arch above this end, furnish a handle by which the mass can be held vertically, with the exposed bone downwards, by the claw of a horizontal arm working up and down a perpendicular metallic rod fitted into a small but steady stand placed on the table, which supports the vessels containing the water, and the thermometers and thermo-electric appliances used in testing the differences of temperature between the air and the liquid. Brain and Skin. The fundamental principle was—as has been said—the same here as in the case of bone, but, as the substances could not with safety be brought into immediate contact with the water, the following special arrangements were adopted: A box of thin pasteboard 50 millims. deep by 85 millims. square was used as a mould, and was filled with melted paraffire. After solidification had taken place, a space was cut * One must be sure that the paraffine does not extend down the sides of the piece of bone so as to touch the water when the under surface of the bone is brought in contact with the liquid,—as paraffine will conduct sufficiently well to introduce errors into the results if the above precaution be not taken. Heat by Conduction in Bone, Brain-tissue, and Skin. 181 out in the centre of the mass, extending from the upper surface to the pasteboard bottom ; at and near this latter point the area of the space was just large enough to accommodate the piece of tissue to be tested. The pasteboard bottom under the space was next cut out, and its place supplied by a copper plate less than 0°5 millim. in thickness, which was closely and exactly fitted in, melted paraffine being used on the inside to secure it. The substance to be tested, when in position, therefore rested on the thin copper plate, and was surrounded by paraffine walls.* The pile (enveloped at the end near its face in only a thin layer of parafline-soaked wool, so as not to touch the surrounding walls of paraffine) was pressed down firmly upon the substance lying on the copper plate, and was kept in position by wedging with cotton- wool the space between its envelope, near the upper end of the latter, and the paraffine walls. The reason for preventing the envelope of the pile near its face from touching the surrounding parafiine walls, is that the latter are, at the bottom of the box, in almost direct contact with the water ; and as paraffine conducts about as well as the substances tested, a thermal movement might possibly take place directly, between the face of the pile and the water, through the paraffine walls. The intervention of an air-space between the envelopes of the! pile and the paratiine wall, not only in the neighbourhood of the face of the pile, but extending to a point far beyond the entire length of the latter, rendered any such thermal movement impossible. Two strips of pasteboard were fitted to the sides of the box, in the same way as in the case of bone. ‘These strips, moreover, served as supports for a mass of cotton-wool, which covered the top of the box, in order to cut off communication between the air imprisoned in the box and the ex- ternal atmosphere through any chance crevice in the cotton-wool wedges holding the pile in place. The prepared bone, or the paraffine box containing the piece of brain or skin, having been attached to the claw of the sliding arm mentioned on page 180, by means of the pastehoard strips, is brought over the surface of the water, and then carefully lowered until the under surface of the bone or the copper plate in the bottom of the box is just ummersed, and no more, in the liquid.tf When this is effected the sliding arm is made fast, and the bone or box removed by raising the whole arrangement, as one piece, by means of the perpendicular rod * Tn comparing bone with brain and skin, it was found that the interposition of the copper plate had no effect on either the rapidity or the extent of the thermal transmission. This was proved by covering the under surface of a piece of bone, previously tested, with a copper plate of the thickness of that used in the experi- ments on brain and skin, when it was found that the conductivity remained un- changed. + The necessity of the caution contained in the note at the bottom of page 180 will now be obvious. 182 Dr. J. S. Lombard. On the Propagation of of the stand. The wet surface of the bone or box is next carefully dried with cotton-wool, and protected from external disturbing in- fluences by an enclosure of thick pasteboard placed near the vessel containing the water. If now, at a given moment, we wish to commence an experiment, we have merely to raise the whole arrangement, as was done when we removed the bone or box, bring the latter over the water, and then set the stand down again. As the distance between the water and the substances to be brought in contact with it was previously accurately determined, and the necessary adjustment made with the sliding arm, we may be certain that the proper degree of immersion is ensured. Moreover, as in experiments of this kind a second’s time is of import- ance, and as the above procedure can be timed so as to bring the surface of the bone or box in contact with the water at a given second (and that, too, without the necessity of the observer taking, for a moment, his eyes off the scale of the galvanometer or the timepiece, as the movements necessary can be performed without looking when once their direction and extent are appreciated), it fulfils another important requisite in this portion of the work.* Before adopting this simple procedure the writer made many experiments with more or less complicated apparatus; but all these appliances were, one after another, thrown aside as introducing troublesome, and often dangerous, complications. It must be remembered that the exposed surface of bone, or copper bottom of the box, must be protected, when not immersed, from radiation, possible currents of air, &c., otherwise, thermal exchanges will take place through the exposed surfaces, and —using such delicate means of investigation as we are now treating of —the index of the galvanometer will not be steady for a moment; this being the case, the bone or box cannot be simply suspended, in free air, over the water, to be lowered upon the latter when the appointed time comes; and all attempts to protect them properly, while thus sus- pended, have led to difficulties, brimging with them, among other evils, delays in the removal of the protections, and, therefore, errors of time. It remains now to describe the manner in which the observations were made. In the first place, the deflections of the galvanometer were noted regularly every fifteen seconds, commencing from the second at which contact between the bone or copper plate and the water took place, up to six minutes. If, however, as sometimes happened, the first sign of the thermal movement showed itself before the first fifteen seconds had elapsed, of course that particular movement was also noted. After the sixth minute the deflections were noted every half minute or every * Tt is hardly necessary to say that the possibility of currents caused by vibration of the conducting wires of the pile in the movements in question, was fully appre- ciated, and negatived by direct experiment. Heat by Conduction in Bone, Brain-tissue, and Skin. 183 minute according to the rate of movement of the index of the galva- nometer, which was usually much diminished by this time, the per- manent thermal condition, or state of thermal equilibrium, being now, as a rule, not very far off. The readings of the thermometers and of the thermo-electric apparatus used in testing the differences of tempera- ture between the air and the water, were noted every half minute. As it was not the rule—even when the greatest care was used—to find the index of the galvanometer at 0° of the scale at the start, it was almost always necessary to add to or subtract from the readings of the thermometers the thermometrical value of the deflection at the moment when the instrument began to show the first sign of the thermal trans- mission. Thus, suppose the thermometers to show a difference between the air and the water of 0°:125 C. in favour of the former, and the index of the galvanometer to be 5° of its scale on the cold side of 0°. If the galvanometer be set to show 1° deflection as equal to 0°-0006742 C., we must deduct 0°-003371 C. (5 x 0:0006742) from the 0°:-125 C. difference between the air and the water, since the surface of bone or brain or skin in contact with the thermo-pile is already cooler than the air by 0°:003371 C. The true thermometric difference between the two surfaces of the substance under examination is, there- fore,. 0°-121629 C. Heperiments on Bone. The bones examined were the skull and long bones of sheep, and the ribs of oxen. In the experiments on the skull, pieces of various thicknesses and areas were taken from different parts, but the results to be given here were obtained with fresh pieces of the parietal and occipital bones 75 millims. in thickness, and 21°5 millims. by 15 millims. in area. . We have three principal poimts for consideration, namely, as follows :— (a.) The time required for the first sign of the change of tempera- ture to show itself through the bone. (v.) The degree of change of temperature produced at certain measured intervals of time. (c.) The maximum of the change of temperature produced, when the permanent thermal condition is attained. Taking the above in the order in which they are set down, we have first to consider the question indicated under the heading “a.”’ To begin with, the degree of difference of temperature to which the bone was subjected must be taken into account. The average degree of difference of temperature was 0°129 C., the maximum being 0°-147 C., and the minimum 0°:1136 C. Under these conditions, the average time required for the first appearance through the bone of the thermal change, with the apparatus set to detect 0°-0006742 C., 184 Dr. J. S. Lombard. On the Propagation of was 28'4 seconds. In 53°333 per cent. of the cases it was 23 seconds; in 26°667 per cent. it was 38 seconds; and in the remaining 20 per cent. it was 30 seconds. If the results of the different experiments are calculated for 0° 1 C. difference of temperature, on the basis that the time required would be inversely proportional to the degree of difference of temperature, the average time is found to be 37°3 seconds, the maximum and the minimum being respectively 55°86 and 26°29 seconds. The average rate of the thermal transmission is, therefore, 1 millim. per 4°9733 seconds, the maximum and the minimum times being, respectively, 7448 and 3°5053 seconds. (b.) Degree of change of temperature produced at certain measured intervals of time. We will examine the changes produced at the end of 1 minute and 15 seconds, 2 minutes, 4 minutes, and 6 minutes, respectively, measured from the moment when the bone touched the water. We will take simply the averages and extremes of the changes due to the differences of temperature given under the preceding heading, having first, how- ever, reduced all the results to values representing the effects of 0°°1 C. difference. Table I gives these averages and extremes in both galva- nometric and thermometric figures. The galvanometric deflections, it will be seen, indicate the steps towards equalisation of the tem- peratures of the two surfaces of the bone at the several periods: thus, as 0°°1 C. is equal to 148°316° of the galvanometer,* and as O°-1 C. represents the difference of temperature between these two surfaces at the start, the steps towards equalisation are measured by the approximation of the figures of the galvanometric degrees to 148°316. Table I.—Effects of 0°°1 C. difference of temperature through 7:5 millims. of sheep’s skull. 1° of galvanometer is equal to 0°-0006742 C.; and 0°1 C. is equal to 148°°316 of galvanometer. | Time from the | | Averages. Maxima. | Minima. moment of | 4") 5; | Decrees Degrees Degrees contact of bone of Thermo- Vhermo- . Thermo- and water. metric i metric metric galyano- galvano- galvano- values. values. values. meter. meter. | meter. At the end of—: | 1 min. 15 sec. | 23°864° | 0°01609° C.| 34°916° | 0°02354° C.| 13°058° | 0:°00845° C, Ong) SALTO. 1003652 74°720 | 0°05038 30°470 | 0°02054 0 ,, | 88°804 | 0°05987 115°485 | 0°07786 49-000 | 0:02696 >» O ,, (LIG476. |'@O7853 135°384 | 0°09127 687504 | 0°04618 * 1° C. is equal to 1483°16 of the galvanometer; hence 1° of the galvanometer is equal to 0°:0006742 C. Feat by Conduction in Bone, Brain-tissue, and Skin. 185 Percentages of heat transmitted, deduced from the above values. Times. Averages. Maxima. Minima. 1 min. 15 sec.....} 16°090 per cent. 23°541 per cent. 8°804 per cent. Pea On sss aa | Oo a 50°378 > 207543 53 ey see al OO Oe 5 77864 i 26°969 # Gm 0) (arses oa] > Loam lar, 91:287 a 46°187 3 This table shows that already by the end of one minute and a quarter the thermal transmission was, on an average, very marked, and that at the end of the sixth minute, 784 per cent. of the initial difference of temperature had been made up. It will further be seen that these results are widely at variance with those of M. Franck, the latter having failed to obtain, at the end of fifteen minutes, using thermometers detecting 0°05 C., any indication of conduction through only 3 millims. of bone, with a difference of temperature of 1° C.; while, according to the table, a change of nearly 0°°06 C. was found, at the end of four minutes, through 7°5 millims. of bone, with a difference of only 0°°1 C. (c.) The maximum change of temperature produced when the per- manent thermal condition is attained. We have under this heading to consider the thermal condition of the bone at the time when the flow of heat through it has settled into a regular and steady movement, in which each cross section of the conductor receives and transmits equal quantities. We have first to inquire how long a time is usually occupied in the attainment of this condition. With the differences of temperature specified under the heading (a) the time ranged from 9 minutes to 11 minutes 30 seconds, the average of all the times being 9 minutes 53 seconds. In 42°857 per cent. of the cases it was 9 minutes, in 28°572 per cent. it was 10 minutes, in 14-285 per cent. it was 11 minutes 30 seconds, while the remaining 14-286 per cent. was divided equally between 11 minutes and 10 minutes 30 seconds respectively. Table II gives the effects of the transmission at this period, reduced to values representing 0°-1 C. difference of temperature. 186 Dr. J. S. Lombard. On the Propayation of Table I1.—Permanent thermal condition effected by 0°1 C. through 7°5 millims. of sheep’s skull. 1° of galvanometer is equal to 0°:0006742 C., and 0°1 C. is equal to 148°°316 of galvanometer. \ Degrees of Thermometric Percentages of galvanometer. values. heat transmitted. PAWeTADOS #26 6. «« 127-431° 0°08591° C. 85°918 per cent. WLR 45 Bo nolo 138 333 0°09326 93°269 * Mit a yes etaie le 104°800 0.07065 70°659 * We find from the above table that in the permanent thermal state— reached in the majority of cases, as we have just seen, by the tenth minute—the initial difference of temperature of 0°-1 C. between the two surfaces of the bone is, on the average, reduced to 0°:01409 C., nearly 86 per cent. of the excess of heat on the warmer of the two surfaces being now transmitted to the cooler surface. Heperiments on Brain-Tissue. The brain-tissue used was that of the sheep, and was in a fresh condition. Pretty much the whole of the brain was examined, and blocks of different thicknesses and areas were employed, but the expe- riments with which we are at present concerned were made on pieces cut from the upper surface of the cerebrum, 75 millims. in thickness and of an area of 21°5 millims. by 15 millims., being thus identical im dimensions with the pieces of skull already treated of. A preliminary series of experiments had, however, to be made to determine whether the dura mater opposed any noteworthy barrier to thermal transmis- sion. This question was decided in the negative, it being found that the resistance of the membrane in question was so slight that it could safely be disregarded. We will examine the results obtained on the pieces of brain in the same manner as was adopted in the case of the skull. (a.) The time required for the first sign of the change of tempera- ture to show itself through the piece of brain. The average degree of difference of temperature to which the brain- tissue was subjected was 0°:13116 C., the maximum being 0°1513 C. and the minimum being 0°1202 C. With these differences, the average time elapsing before the first appearance on the upper surface of the piece of tissue of the thermal change (the apparatus having the same delicacy as in the experiments on the skull) was 30°83 seconds. In 44444 per cent. of the cases it was 23 seconds, in 27°777 per cent. ~ Feat by Conduction in Bone, Brain-tissue, and Skin. 187 it was 38 seconds, in 22°223 per cent. it was 30 seconds, and in the remaining 5556 per cent. 1t was 53 seconds. If all the individual results are reduced to values representing 0°-1 C. difference of temperature, the average time becomes 40°49 seconds, the maximum and the minimum being respectively 63°706 and 27°646 seconds. The average rate of the thermal movement is, therefore, 1 millim. per 90°3986 seconds, the maximum and the minimum times being respectively 8°4941 and 3°6853 seconds. There appears indeed from these figures to be but little difference at this period between brain and skull. (b.) The degree of change of temperature produced at certain measured intervals of time. Proceeding in precisely the same manner as in the case of the skull, we arrive at the results set forth in Table III. These results are evi- dence of the accuracy of M. Franck in attributing a high conducting power (comparatively speaking) to brain-tissue; for the values given in the table approximate closely, especially in the earlier periods, to those contained in Table I for the skull. If we take the differences between the thermometric values at the same periods in the averages of the two tables, we find that the superiority of bone over brain- tissue is represented, even at its greatest, by only a little more than the one-hundredth of a degree Centigrade. The average degree of supe- riority of the bone over the cerebral tissue in point of conductivity at the different periods will be seen below :— Table I1l.—Effects of 0°-1 C. difference of temperature through 7:5 millims. of upper surface of cerebrum of sheep. 1° of galyanometer is equal to 0°'0006742 C.; and 0°1 C. is equal to 148°°316 of gal- vanometer. moment of Game from the | Averages. | Maxima. | Minima. contact of copper | | late, on which | Degrees Degrees Degrees P 4 5 | Thermo- a. Thermo- o. | Thermo- the piece of of : ot Ast" PbO =| : - | metric metric metric brain rested, | galvano- | i a galyano- sate galvano- ae : ‘ st. aiues. 5 with the water. | meter. | & = meter. meter. At the end of— | 1 min. 15 sec. | 21:036° | 0°01418° C.| 32°445° | 0°02187° C.| 6°370° | 0°00429° C.| ree 0. | 42°721 _0:02880 59°068 | 0-:03982 | 19°379 =| 0°01806 4 , O.,, | 74840 |0-05045 103°200 |0°06957 | 32558 | 0°02195 Ge O--,, | 99-075 | 0-06679 136°000 |0°09169 | 49°612 (003344 188 Dr. J. 8. Lombard. On the Propagation of Percentages of heat transmitted, deduced from the above values. Times. Averages. Maxima. Minima. 1 min. 15 sec. ..] 14°176 per cent. 21°875 per cent. 4-294 per cent. Zs nO Msi sil =25'80a 08 9,5 39'825 ,, 13066 ___,, ee Op ogee he 6958 21951, Gree iesO) Ls, OG SOn se SIEGIoMnma. 33°450 sy, Thermometric degree | Percentages of degree Times, of average superiority | of average superiority of skull over brain. of skull over brain. I yraveoty 15) Helebo 5 Soc 0:00191° C. 1914 per cent. Qin ig Onetstne creative 0°00772 7-720 s AAS OW ee 0:00942 9415 6 OP oerckecn 001174 11°733 5 Comparing the maximum values of the two tables (land IIT), it will be noticed that at the end of the sixth minute the brain-tissue exceeds the skull by 0°-00042 C. (c.) The maximum change of temperature produced when the permanent thermal condition 1s attained. First, as to the time required to reach this condition, with the differences of temperature set down under the heading (a), the range was from 9 to 11 minutes, the average of all the times being 9 minutes 52°5 seconds. In 50 per cent. of the cases it was 9 minutes, in 37°5 per cent. it was 11 minutes, and in the remaining 12:5 per cent. it was 10 minutes. In Table IV we have the results of the transmission at this period, reduced, as in the case of the skull, to values representing 0°-1 C. difference of temperature. Table IV.—Permanent thermal condition effected by 0°-1 C., through 7°5 millims. of cerebrum of sheep. 1° of galvanometer is equal to 0°-0006742 C., and 0°1 C. is equal to 148°°316 of galvanometer. Degrees of Thermometric Percentages of galvanometer. values. heat transmitted. Averages... ss.t oe vs 113°029° 0:07620 C. 76°208 per cent. WiEpahiblo 6 Gannloo oe 138°888 0°09364 93°638 . IW GneneTeh ein co do oooe 72:000 0:04854 48°545 p Heat by Conduction in Bone, Brain-tissue, and Skin. 189 Comparing the above table with Table II, we find that the average difference in the conducting powers of skull and brain-tissue is now reduced to 0°:00971 C., in tavour of the bone; but if we take the maximum values, the conductivity of brain-tissue slightly exceeds that of skull, namely, by 0°-00038 C. Hzperiments on Skin. The skin experimented on was fresh sheep’s skin; and, in the par- ticular experiments with which we have now to deal, pieces of the shaven scalp 3 millims. in thickness, and of the same area as the pieces of skull and cerebrum already described, were employed. Following the course adopted with skull and brain-tissue, we have the same points as before to consider. (a.) The time required for the first sign of the change of tempera- ture to show itself through the piece of scalp. The average degree of difference of temperature to which the scalp was subjected was 0°°12957 C., the maximum and the minimum being, respectively, 0°-1645 C. and 0°:125.C. With these differences the time required for the first sign of the change of temperature to manifest itself, on the upper surface of the piece of skin—with the apparatus set, as before, to detect 0°'0006742 C.—was 17°6 seconds. In 60 per cent. of the cases the time was 19 seconds; while the other 40 per cent. was divided equally among 23, 16, 15, and 8 seconds. Reducing all the results to values representing 0°1 C. difference of temperature, the average time is found to be 22°88 seconds, the extremes being 29°417 and 10 seconds. The average rate of the thermal movement is consequently 1 millim. per 76267 seconds, the maximum and the minimum times being, respectively, 9°8057 and 33333 seconds, The average rate of the thermal transmission per millimetre for 0°1 C. difference of temperature appears, therefore, to be lower, at this period, in scalp than in bone or brain-tissue ; and the _ lowest rate in scalp is below the corresponding rates in bone and brain-tissue; but on the other hand, the highest rate is found in scalp, although the degree of superiority is insignificant. In Table V the results obtained on the three tissues, at this period, are brought together for comparison. ) (b.) The degree of change of temperature produced at certain measured intervals of time. | 190 Dr. J. S$. Lombard. On the Propagation of Table V.—Comparison of times required for the jirst sign of the ther- mal change to show itself through 7-5 millims. of sheep’s skull, 7-5 millims. of sheep’s brain, and 3 millims. of sheep’s scalp, respec- tively, with apparatus detecting 0°-0006742 C. Degrees of difference of temperature to which the several tissues were subjected. | | Bone. Brain. Skin. i / | | ars | WtAverares 22092 00% ORIG Pe arin 07129577 C. | Maxima ..........---| 0°1470 0-15130 0716450 WOMinima....cs-----.64|,, Olas 0:12020 0-12500 | With the above differences of temperature the times required for the first appearance through the tissues of the thermal change were as follows :— | Bone. Brain. Skin. | aa aa htAweriges oo. 0 eee | 28'4 seconds. | 30°88 seconds. 17°6 seconds. | i? Maxima... J2:.2 | 380 3 53°00 3 23-0 = | cas 2. ee eee 23:00, $0, Percentages of the frequency of occurrence of the different times noted. | Bone. Brain. Skin. - | - | : | | Times. Percentages.| Times. Percentages. Times. Percentages. 23 seconds 53°333 | 23 seconds 44-444 | 19 seconds | 60°000 abate 26667 | 38 ,, 27-777 | 23 . | 10-000 B00 ag oe A) BOD FBO ot) Hope22ete IdaGge & 10-000 | ee 5556 | 15. 10-000 eee eae 10-000 Times calculated for 0°1 C. on the basis that the time required would be inversely proportional to the degree of difference of temperature. Minimise eters: | .| ewer ae | 97646 =» | 10000 ,, | | Bone. | Brain. | = Averages ............| 37°30 seconds. | 40-490 seconds. | 22-880 seconds. Maxims. ...::c-..-|. 5586 4, |) 637065... | sean Heat by Conduction in Bone, Brain-tissue, and Skin. 191 Times required to traverse 1 millim. of each of the tissues, calculated for a difference of 0° 1 C. PAMETA EES tate laie 4-15 = == So ee eEenae or Boos |) TTY Seance ae Brain. 5°3986 seconds. 84941, 36853, Table VI gives the results obtained at the end on the several times adopted in the preceding tables as bone and brain. Table VI.—Effects of 0°°1 C. difference of temperature through millims. of sheep’s scalp. 1° of galvanometer is equal to 0°:000674 C.; and 0°-1 C. is equal to 148°°316 of galvanometer. 3 2 | 63°884 | 0°04307 Averages. Maxima. Minima. Time from the ie 7 moment of contact of copper er Payee | plate, on which cue T hermo- yes Thermo- | ieee Thermo- the piece of skin 1 metric metric | metric galvano- ; galvano- 'galvano- rested, and water. values. values. | values. meter. meter. meter. At the end of— | { 12min. 15 sec. | 17°191° | 0°01159°C.} 21°120° | 0°01424°C.| 10°576° | 0-:00713° C. Pt OL 5, 31°241 | 0°02106 38°808 |0:02616 | 20°898 | 0-:01409 Ae te OF 59-208 | 0°03992 83°952 | 0°05660 30°861 | 0°02417 Gea nO. 55 80°766 | 0°05445 96°492 | 0°06505 Percentages of heat transmitted, deduced from the above values. Minima. | Times. Averages. Maxima 1 min. 15 sec......| 11°597 per cent. 14239 per cent. 7-137 per cent. | Pe |, 21-063, 96165 ,, 14090, | i a 39921 |, 56603, 24179, 6-53 if 54452 65058, 43-070 ~,, | _ It will, at once, be evident, that, although the pieces of skull and of cerebrum are two and a-half times thicker than the pieces of skin, yet the amount of heat transmitted by the latter is considerably less than the amount transmitted by the former, with the exception, that the minimum values of scalp are higher than the corresponding values of brain-tissue, and approach somewhat closely to those of skull. 192 Dr. J. 8. Lombard. On the Propagation of If we should apply the well-known physical calculations of Fourier and others, and through them seek to determine the changes of tem- perature which would exist if the piece of skin were increased in thickness to 7°5 millims., the inferiority of the tissue in conducting power compared with bone and brain-tissue, would become much more striking ;* but unfortunately, not only theory—based upon the lack of homogeneity in these structures—but also a large number of direct experiments made by the writer, show that such calculations are not to be relied upon. In the case alone of the hard tissue of bone, it has sometimes happened that the results of the mathematical calculations and those of the experiment have partially agreed. We cannot, then, with any certainty, reason from one thickness of bone, brain, or skin to another. To have reduced the bone to 3 millims. in thickness to correspond with the skin, would have entailed serious risks of error in the method of experimenting adopted.t The thickness of bone chosen was a natural thickness of the skull often found in the animal experi- mented on, and the same is true of the thickness of the scalp. (c.) The maximum change of temperature produced, when the permanent thermal condition is attained. With the differences of temperature given under the heading (aq), the permanent thermal condition was reached in a time ranging from 11 to 15 minutes, the average being 12 minutes 15 seconds. In 50 per cent. of the cases the time was 11 minutes, and the other 50 per cent. was divided equally between 12 and 15 minutes. In Table VII we see the effects of the thermal movement at this stage, reduced as before to the basis of 0°'1 C. difference of tempera- ture. Table VII.—Permanent thermal condition effected by 0° 1 C. through 3 millims. of sheep’s scalp. 1° of galvanometer is equal to 0°-0006742 C.; and 0°:1 C. is equal to 148°-316 of galvonometer. Degrees of Thermometric Percentages of galvanometer. values. heat transmitted. FAVONAGES! slate! wie 100°155° 0:06751° C. 67°514 per cent. Ma sci ayes avelsccree eens 117°480 007920 79°209 4 Wikia sce oe eee 82°104 0°05535 55°3804 * * The application of these formule sweeps away the whole of Table VJ, as according to them, even at the end of the sixth minute no sign of the transmission would be found through 7°5 millims. of scalp. + By exchanges between the face of the pile and the water through the paraffine envelope (see note, p. 181), which latter would, with the above thickness of bone, be in dangerous proximity to the liquid. a Feat by Conduction in Bone, Brain-tissue, and Skin. 193 Placing the above beside Tables II and IV, even leaving out the question of relative thickness, the inferior conducting power of skin, compared with bone and cerebral tissue, is again manifest, although the degree of this inferiority is diminished. Thus, taking the averages at the end of the sixth minute, the skin falls below bone by 24-08 per cent., and below brain-tissue by 12°347 per cent.; while now these differences are reduced, respectively, to 18404 per cent., and 8694 per cent. If we take the maximum values, the skin is inferior to bone (the maximum value of the latter being a trifle lower than that of brain-tissue) by 26°229 per cent. at the end of the sixth minute, and by 14:06 per cent. in the permanent thermal condition. With regard to the minimum values, they are now, as at former periods, higher in skin than in brain-tissue. Conduction in Bone and Skin combined. Let us now suppose the 3 millims. of scalp to be lying upon the 7°5 millims. of bone, as in life, and a rise of temperature of 0°-1 C. to occur on the cerebral surface beneath. We have seen that the dura mater offers no appreciable resistance, and have, therefore, simply to deal with the compound conductor of bone and skin. We will first estimate how long a time would elapse after the rise of tem- perature in the brain before 0°-0006742 C. difference would be found on the outer surface. Now it has been shown that the average time required for 0°1 C. to traverse the bone is 37°3 seconds, while the average time required for the same difference of temperature to tra- verse the skin is 22°88 seconds; the total time would therefore, be 60°18 seconds, the shortest time would be 36°39 seconds, and tue longest time 85°277 seconds. Next, with regard to the amount of heat which would be trans- mitted through the compound conductor. Looking at Table I we see that the bone has transmitted, at the end of 1 minute 15 seconds, 16°09 per cent. of the heat received, and from Table VI we learn that, during the same time the’ skin has transmitted 11:597 per cent. ;* therefore, the skin receiving from the bone 16°09 per cent. of the original amount of heat would transmit 11°597 per cent. of these receipts, or 1°86395 per cent. of the original amount; hence the change of temperature observed on the outer surface of the scalp, at this period, would be 0°-001866 C. Table VIII gives the results, for the several periods of time, deduced in the above manner from Tables I and VI. These results show that, in spite of the decided resistance introduced by the skin, there would not be the slightest difficulty in detecting, with delicate apparatus, at an early period, on * Averages. VOL. XXXIV. 0 194 Dr. J. 8. Lombard. . On the Propagation of the outer surface of the scalp, a change of 0°-1 C. on the surface of the brain, in the animal in question. Table VIII.—Effects of 0°°1 C. difference of temperature through 7°5 millims. of sheep’s skull and 3 millims. of sheep’s scalp, taken to- gether. 1° of galvanometer is equal to 0°:0006742 C.; and 0°-1 C. is equal to 148°°316 of galvanometer. Averages. Maxima. Minima. Times. Degrees Decrees Degrees er Thermo- en Thermo- ee Thermo- metric metrie metric galvano- Baers galvano- bias galvano- nn 5 meter. ; meter. ; meter. ‘ At the end of— 1 min. 15 sec.| 2°767° |:001866°C.| 4°971° | -003352° C.| 0°931° | -000628° C. 2 , O.,, | 11-409 |:007692 | 19°550 |-013181 4-293 |-002894 4 , 0 .,, | 35:450 |-023902 | 65°367 | -044073 9-671 |-006520 6 , 0 .,, | 63424 |:042762 | 88-083 |-059389 | 29°504 | -019892 Percentages of heat transmitted. Times. Averages. Maxima. Minima. 1 min. 15 sec. ..... 1°866 per cent. 3352 per cent. 0°628 per cent. ie SN Oe aE de GoO2T 13181 _,, 28945 hy, aceon Eee 23902, 44-073, 6520 ,, Gh Beep Ons verter tile Aen Gam | 59°389 _ ,, 19°892 ss, Coming to the permanent thermal condition of the compound con- ductor, we can estimate, in the same manner as we have just done, from the separate tables for bone and skin, the amount of heat which would be transmitted when this condition is reached. Table IX gives the results of these estimates. Here, again, we have evidence that— although diminished—the external manifestations of 0°-1 C. change at the cerebral surface would still be amply great to admit of detec- tion by much coarser instruments than those we are employing. Supposing the rise of temperature at the cerebral surface to be only 0°-01 C., instead of 0°'1 C., it would still be plainly visible at the exterior at the end of the fourth minute; for the percentage of trans- mission at this period would give a galvanometric deflection of 3°°545, equal to 0°:00239 C., while when the permanent thermal condition was attained, the deflection would be 8°°603, equal to 0°-0058 C. But, as was stated in the introduction, there is no reason whatever why Heat by Conduction in Bone, Brain-tissue, and Skin. 195 rises of temperature of 0°°2 C., and even 0°°3 C. may not occur in the brain of man, and perhaps in the brains of other of the higher animals, during intellectual and emotional activity, with, consequently, de- cidedly greater external manifestations than those given in our calcu- lations. Table IX.—Permanent thermal condition effected by 0°'1 C. through 7°5 millims. of sheep’s skull and 3 millims. of sheep’s scalp, taken together. 1° of galvanometer is equal to 0°°0006742 C.; and 0°1 is equal to 148°°316 of galvanometer. Degrees of Thermometric Percentages of galvanometer. values. heat transmitted. PNMETACES 25 2/2 ac - 86°033° 0-058006° C. 58°006 per cent. Meama, .2).68 6)". 119°572 0:073877 73°877 53 MINA) 6c aie vie) = 58:010 0:039112 39°112 i With regard to the effect of the blood circulating between the surface of the brain and the outer surface of the skin, the only way in which this liquid could check the outward thermal propagation would be by virtue of its specific heat. The writer has considered this question at some length in the work already cited,* and he sees no reason now to depart from the line of argument there followed. If, as was there done, we allow a loss of 50 per cent. of the initial rise of temperature to satisfy the capacity for heat of the blood (and we are really not warranted in granting such a loss) our 0°°1 C.—now reduced to 0°:05 C.—would still show itself at the outer surface, at the end of the second minute, by a galvanometric deflection of 5°°704, equal to 0°:003846 C. We have next to see how far the good conductivity of brain-tissue would act to prevent localisation at the outer surface of the scalp of changes of temperature in a narrowly circumscribed area of the cerebral surface. Imagine, as before, a point of the cerebral surface to have its tem- perature raised 0° 1C. Now, setting out from this point, the excess of heat would be transmitted to points in the surrounding cerebral mass situated at a distance of 7°5 millims., in the proportions shown in Tables III and IV. What the transmission to a point of the external surface situated directly over the focus of heat would be we have just seen. We have, then, merely to take the temperatures contained in Tables III and IV, and using the percentages of transmission through * Op. cit., pp. 115, 118. co) bo 196 Dr. J. 8. Lombard. On the Propagation of skull and scalp combined, given in Tables VIII and IX, to calculate the temperatures which would be found at a point of the outer surface lying over the point of cerebral surface situated 7°5 millims. from the focus of heat. For example, Table III shows us that, at the end of the sixth minute, a point of the brain, situated 7°5 millims. from another point heated 0°-1 C., would have its own temperature raised, by conduction, 0°:06679 C., and Table VIII shows us that the trans- mission through skull and scalp combined (which would, of course, be proceeding coincidently) is, at this time, 42°762 per cent. ; hence the temperature of the outer surface would be 0°02856 C. Tables X and XI show the effects of vieLs indirect transmission to the outer surface. Table X.—Effects produced through 7°5 millims. of sheep’s skull and 3 millims. of sheep’s scalp, taken together, lying over a point of cerebral surface 7°5 millims. distant from another point of this same surface, the temperature of which latter point is raised 0°:1 C. The results are calculated from Tables III and VIII. This table is for comparison with Table VIII where the effects of the direct transmission from the heated point are given. 1° of galvanometer is equal to 0°-0006742 C.; and 0%1 C. is equal to 148°°316 of gal- vanometer. Averages. Maxima. | Minima. Times. eee Tae Wee Theene Degrees Phere: 1 metric : metric metric Balrano || values: (oon elon aepaltues) dh) oceans meter. ; meter. 5 meter ; At the end of— 1 min. 15 see. | 0°392° | :000264°C.| 1:087° | -000738°C.| 0:040° | :000027° C. Zt oh Ons, 4°873 | °003286 7786. | 005249 0°560 | -000378 AIM CD a 17°888 | -012060 45°483 | “030664 27122 |:001430 Ginsy | MORE, 42°360 |°028560 70°769 | 047712 9°868 | 006633 Percentage of heat transmitted. Times. Averages. Maxima. Minima. | } oe ts oe 1 min. 15 sec. ..... 0:'264, per cent. 0°733 per cent. 0-027 per cent. COR te eg 3286 uie 5249, 0378 1% panier ov 12060 _,, 30664 ,, NEZEY) 6 28560, AT712 ~—, 6633 __,, Feat by Conduction in Bone, Brain-tissue, and Skin. 197 Table XI.—Permanent thermal condition effected through 7°5 millims. of sheep’s skull and 3 millims. of sheep’s scalp, taken together, lying over a point of cerebral surface 7°5 millims. distant from another point of this same surface, the temperature of which latter point is raised 0°10. The results are calculated from Tables TV and IX. This Table is for comparison with Table 1X, where the effects of the direct transmission from the heated point are given. 1° of galvanometer is equal to 0°:0006742 C.; and 0°-1 C.is equal to 148°°316 of galvanometer. Degrees of Thermometric Percentages of galvanometer. values. | heat transmitted. AVERAGES . 0. +e + 65°563° 0:044202° C. 44°202 per cent. Maxima . 202.6 si00s 102°606 0:070176 70'176 5) Minima.......++. 28°160 0018985 18°985 bb) Plainly, if it were a question of mere conduction alone, and if the skull and skin at the several points were of equal thickness, and possessed of the same conductivity, it would be easy to locate on the outer surface, within a radius of 7°5 millims., a change of 0°1 C. occurring on the cerebral surface. The following are the differences of temperature in favour of the point of surface lying directly over the focus of heat, which would be found under the circumstances we are considering :— Permanent thermal condition. Average differences a. of temperature P ; Differences of temperature. 1 min. 15 sec.... 0:001602° C. Averages ss<)...5 5% 0:013804° C. 7 Tose ee (0) sea Renee 0:004406 Wibebinvhon pred oo 0:003701 Are OP see's 0°011842 Minimum*...... 0:020127 Gee OL i ys) 5st 0°014202 But, in truth, in the case of the tissues concerned, we are not, in the first place, dealing with simple homogeneous conductors of uniform thicknesses. Hven within the narrow area specified, the bone or skin may exhibit decided differences of conductivity, due to slight varia- tions of structure or composition. That this may be the case, the writer has over and over again proved by direct experiment. As the * Tt will be noticed that the least difference is found with the maximum of trans- mission, and the greatest difference with the minimum of transmission. 198 On the Propagation of Heat by Conduction, &c. ‘propagation of heat by conduction is not rectilinear, a slight alteration | of texture or composition might easily deflect the path of transmission in such a way as to wholly change the relative temperatures of the outer surface which we have given. Differences of thickness, also small, but sufficient to overthrow our calculations—may exist. Lastly, the circulation of the blood, already alluded to, although incapable of checking the outward transmission, might yet, within such narrow limits, bring about a confusion in the external manifestations of the interior change of temperature. It is only when areas of much greater dimensions—for instance, of 50 or 60 millims. square —are taken, that we can look with any degree of confidence to the relative external temperatures as furnishing a key to the relative temperatures of the underlying tracts of cerebral surface.* Moreover, in increased mental activity—whatever may be its kind—the change of tempera- ture on the outer surface of the head is of widespread extent, and not confined to such lmited areas as those on which our calculations are based. * See the writer’s “ Regional Temperature of the Head,” pp. 119 and 209. On the Variation of the Electrical Resistance of Glass, §ce. 199 On the Variation of the Electrical Resistance of Glass with Temperature, Density, and Chemical Composition.” By THomas Gray, B.Sc. F.R.S.E. Communicated by Pro- fessor Sir WILLIAM THOMSON, F.R.S. Received December 28,1881. Read January 12, 1882.* The following paper is a description of the methods adopted, and ot the results obtained, in a series of experiments on the specific resist- ance of glass. These experiments were performed in the Physical Laboratory of the Imperial College of Engineering, Tokio, Japan. An account of some preliminary experiments on this subject was communicated by the author of this paper to the ‘‘ Philosophical Magazine” for October, 1880. In that paper attention was specially directed to the change of resistance with change of temperature, and to an apparently permanent change in electric quality which the glass underwent when subjected to a high temperature. Subsequent experiments have served to confirm the results there given, but show that if the glass be newly made very little, if any, permanent change is brought abous by heating. In the experiments just referred to a current of electricity was kept flowing either continuously or at short intervals during the heating. As this might produce effects which would not be caused by heating alone, it was thought desirable to test one or two specimens for resistance at as low a temperature as possible, and then again, after the glass had been heated to between 200° and 300° C., and cooled to the same temperature. Experiments performed in this way have shown an exactly similar change to that previously obtained. It appears, therefore, that the change previously observed was due to heating. The fact that the permanent change produced by heating to a high temperature was markedly greater in specimens of old than in specimens of new glass, rendered it probable that the change was due to some previous change in the opposite direction, which goes on slowly at the ordinary temperature. In order to put this conjecture to the test of experiment, advantage was taken of several specimens of newly-manu- factured glass which had just been obtained from the Government Glass Works, Shinagawa, Tokio. The results of tests made on three speci- mens of that glass are given in the following table. The first two specimens were lime glass, while the third was a white semi-opaque flint glass, containing arsenic. In the first column the number of the specimen is written; in the second the resistance in ohms between two opposite faces of a cubic centimetre; in the third, the temperature at * For abstract see ante, vol. 33, p. 256. VOL. XXXIY. P 200 Mr. T. Gray. which the resistance was measured; in the fourth, the density of the glass; and in the fifth, the date at which the resistance was measured. Na. ae Specific resistance ; | | Tempera- . eneeinies: in ohms per eae) Density. Date. cub. centim. | if on ee i 1 146 x 1010 40° C. 2°57 May 3, 1880. 122 x 101° as December 9, 1880. 24x10 | 40°C, 2-53 May 3, 1880. ! 2 17 x 10" - December 10, 1880. 12 x 10! | be May 8, 1881. 3 41 x 101! 140° C 3°07 May 17, 1880. 17 x 10}! | i. November 17, 1880. | These results show a very considerable increase of conductivity with age, and also show a marked difference in the variation of different specimens. The number of experiments is not sufficient to give much information regarding this time change, but the fact that they give evidence that such a change takes place seems to warrant the publication of these preliminary results. The measurements of resistance described in this paper were, like those in the previous paper above referred to, for the most part made by means of an astatic galvanometer of high resistance and great sensibility. The galvanometer used had an internal resistance of 10,000 ohms, and one Daniell’s element produced a deflection of one division when a resistance of about 10" ohms was in the circuit. The great advantage of the galvanometer over the electrometer method of measurement is its simplicity ; the deflection being independent of the capacity of the circuit, provided no change is taking place in that capacity. In many cases, however, the resistance of glass at low temperatures cannot be measured by the galvanometer, and in these cases, the most convenient instrument is a Thomson’s se een elec- trometer. The method adopted in the galvanometer measurements was that of direct deflection, the current being produced by fifty Daniell’s ele- ments, placed on a table well insulated with ebonite supports, kept dry by being enclosed in boxes containing sulphuric acid. The main difficulty in this method is to ensure absence of leakage currents through the galvanometer. The test used for the absence of such currents was to insulate the electrode of the inside coating of the glass vessel, and then close the key. If there was no deflection, it was assumed that the circuit was sufficiently insulated. Several measurements were made by means of the quadrant elec- trometer, and in that case the method adopted was to connect one coating of the glass, one pair of quadrants, and the case of the elec- On the Variation of the Electrical Resistance of Glass, fc. 201 trometer to earth; while the other coating of the glass and the remaining pair of quadrants were connected together but insulated. The resistance was then calculated from the capacity of the glass vessel and electrometer quadrant, and the rate of loss of charge. The conducting coatings for the glass were generally made by partly fillmg the vessel to be experimented on with mercury, and then immersing it in another vessel of mercury until the surface of the mercury inside and outside the vessel was at the same level. In order to avoid leakage over the sides of the vessel, it and the mercury were made thoroughly dry by heating, and when sufficiently cooled, a coating of paraffin was run over the surface of the mercury and the vessel. Through this coating of paraffin a fine glass tube, well dried and paraffined, was passed, thus furnishing at the same time a passage, and more thorough insulation against surface leakage for the elec- trode which made contact with the mercury. This explanation will be more readily understood by the aid of fig. 1, which shows the arrange- ment for measuring the resistance of a glass globe, the galvanometer, battery, and key being shown symbolically. In the figure SM repre- Mave} dl sents the surface of the mercury, Sp the surface of the paraffin, and ¢ the fine tube through which the electrode, /, passes. The tube, ¢, and the neck of the globe were in such a case coated with paraffin. The precautions against leakage here described are more necessary when the resistance at ordinary temperature is to be measured, but even in other cases it was found advisable to begin with this, and simply allow the paraffin to evaporate at high temperatures. The sur- face of the hot glass remained afterwards perfectly dry. Sulphuric acid was sometimes used instead of mercury, and answers perfectly if the temperature does not require to be high. If, however, P2 202 Mr. T. Gray. the temperature requires to be raised until the acid evaporates, it becomes extremely disagreeable. The acid has the advantage that it keeps the vessel dry, and hence is to be preferred for low temperature measurements. Abridged tables of results for a few characteristic specimens are annexed, and serve to illustrate the very wide range of resistance which may be obtained by using different specimens of glass. The variation with temperature of several specimens is illustrated by means of curves. These curves only show the variation with tempera- ture through a small range, as 1t was found almost impossible to include both a number of curves and long range of temperature in the same diagram. It will be observed on examining these curves that the rate of variation with temperature is very nearly the same, not only for different specimens of the same kind of glass, but for all the kinds of glass there figured. Other specimens, not included in this diagram, gave a very similar variation. On an average it may be said that the specific resistance of glass is halved for every 8°°5 C. rise of tem- perature.* In the tables of results the density of each specimen is recorded, and in some cases the chemical composition also. The chemical analyses were performed in the Chemical Laboratory of the Imperial College of Engineering, Tokio, by Messrs. Fujii and Shimidzu, under the superintendence of Dr. Edward Divers, to whom the author is much indebted for the great interest he has taken, and assistance he has given, in the carrying out of these experiments. It is very interesting to notice how very closely a change of density in flint glass agrees with a change of electrical resistance, and also that the electrical resistance of this kind of glass increased regularly until the density reached that point at which the composition of the glass was almost exactly that required for a trisilicate of lead, potash, and silica. The very high density of lead oxide causes the density of the glass to be an indication of the quantity of lead present, and * Note added April 26, 1882.—-Although the fall of resistance with rise of tem- perature generally follows very nearly the logarithmic law, the results show varia- tions from that law which I am not yet able to explain. The resistance at high temperatures is generally higher than would be inferred from the resistance and rate of variation at low temperatures. It is remarkable that specimens which had a high resistance gave results more nearly in agreement with the logarithmic law than specimens of comparatively low resistance. The resistances quoted in the tables are those calculated from observations after one minute’s electrification, the direction of the current being alternately in opposite directions, and only allowed to flow for about one minute at each observation. The method of observation was thus similar to that described as “ the first method” in my paper in the “ Philosophical Magazine” above referred to. (See “ Phil. Mag.,” October, 1880, page 227.) On the Variation of the Electrical Resistance of Glass, &¢c. 203 hence the density in this case serves as a guide to the electrical quality of the glass. A specimen of glass containing too much lead for a pure silicate has not yet been experimented on, but the result of such an experiment would be of great interest in furnishing evidence as to whether purity of chemical composition and high electrical resistance go together. When we turn to lime glass, however, we find that the density is no guide to the electrical quality. Specimens having nearly the same density vary enormously as to their electrical resistance. This, how- ever, is to be expected, as the density may change but little, even when the chemical composition is greatly altered. Lime glass gene- rally contains both soda and potash, and the ratio of these two bases may influence considerably the density, while the glass remaining a good glass the electrical conductivity may not be much affected. So far as the results of chemical composition go, however, it appears that in the case of lime glass also, a glass which would be pronounced good from a chemical point of view is also relatively good from an electrical point of view. On the other hand a glass which would be pronounced bad chemically is also bad electrically. In the following tables the resistance at various temperatures of six specimens of lime glass and two specimens of lead glass are given. The first column contains the temperature, the second the resistance in ohms of a cubic centimetre, the third the density, and the fourth the chemical composition in those cases where it was determined. Specimen I. (Bohemian glass tubing.) Owes tes eo 4 COLO re aes 2, 43 MOOR 8 eos. 20x10 1.30) oe ee 20 x 1010 LGD) oh aioe scene oe 24 x 109 le 2h 87 x 108 Specimen IJ. (Test-tube.) 30 (CO ee DIO SOU) a Tah) 2 °458 OO) sec dr BOODGNOe ose s. 7a a GUO” a keen JI) eS eee Ome lee 2a wr aa 12). ane G2 CHOR eae Specimen III. (Japanese lime glass tubing.) neenera GAO SiO li te 255 2. Silhea ae geek sn se obs 30 Poe 99 KOLO A a oy Rotasheame.. . 2. 22,9 52 Se 00h 102 oo ae -- Lime, &c., by diff. 15-8 75 rae Oi LOSI Ve etye we — 85 OK LOR a sl 100 ‘0 204 | Mr. T. Gray. Specimen IV. (Japanese lime glass tubing.) BRC TS KOI: Gor (OE AGT GiiCa: oan 57-2 55 Be PH sO ve 2 -aPotashi see ee Dd) Le) | 75 2 61x 1010) 8. 1 airinme, des, (oy, cation 85 COG SOM OLO ction nates Besa 95 fe LEED SOUQLONe, aaNet ee 100-0 The analyses of the last two specimens are only approximate, having been made previous to the electrical experiments, and for a different purpose. The composition differs very widely from that which is required for a pure silicate, and the electrical resistance is also found to be very low. Specimen V. (French flask.) AD? Os 0) B27 TOM 45° 2"533) e PSilica 2s. 3. eee 70 05 55 ee les ieog JOY a - Soe Se Ae 10°33 65 09 02 E tae Oy _. | Ineadvoxide =.) aeaee 2°70 75 eae PAOZES CIO Ie © Sho Se Sodan aa a sae +. Ase 86 Be avec US ne i. Potash! 224 ee eee 1-44 95 SSO Ton Say ale fe .. | Magnesia 9:@a= anes 0-10 108 TCS EHOS a ee ae .. Alumina, iron oxide, 117 er COOL eae ena ane manganese oxide. 1°45 100°39 With regard to this specimen, Dr. Divers writes as follows :— “This seems to be a soda lime glass mixed with a little potash lead glass ; the latter having been thrown in as cullet. Assuming this to be the case, we will have approximately— Potash lead elassesy.1: 21s ssa 8 Soda Sa Wa deiidce eiete eicdara ike ae eae 91 Slicer: Bye ko ue paemlameere, onal re ee 1D) 2 O Dyn cate paunae ray i etn ane ny nO LYN Uren ee BRR 11 °4 Soda Le LA an ees car tata 15 °9 On the Variation of the Electrical Resistance of Glass, &e. 205 Apparently the best glass has the formula— Sillicamey a: fone Ca0.8,0,810=4 iimmve;s vs 3: Lie? 6 SOdaiasee: 13 0 100 -0 “Tf this is deviated from an increase in the proportion of soda to lime requires a considerable increase in the proportion of silica to base. The flask is therefore defective, for not only is the soda in excess to the lime, but the silica is deficient. I calculate that from 20 to 25 parts of silica should be added to 100 of that glass to counteract the excess of soda. Such a glass would be— STILE ine) SI eo aC eg 775 rete eer s et tence uv EE Le 9°5 SHOTS Es et ae, ae RG a er ne 13°0 “‘ However, too little is yet known of the relations of composition to quality of glass to admit of positive statement. “The empirical formula 2CaO,Si0, + yNa,0,SiO, seems to me 5 to be a tolerably accurate expression of the various kinds of good glass, provided xz and y are not very different from one another. When equal, the glass is certainly excellent.” Specimen VI. (Bohemian beaker.) meme O 7x LOU. (275877... Silica. 2. 2.55.5.» 75 65 88 S25 x LOL” _ Me ep MU MAINUL GN 8% che Succ: Sesiie esas 8°48 110 SOc re ee Potasir ses oe. 8 C92 132 ae DEO ca Cae ames ie aS OGL AS sot e etree aca Ecnek Son oes 6 92 150 oA < LOS", ie he) Maomesiay cis 05. c- 0 36 170 me ay Xx VOR *. oe .. Alumina, iron and ISB: OS UO a ae manganese oxides. 0-70 100 -03 Assuming the formula K,0,CaOQSi0, + Na,O0,CaO,Si0,, as giving Bre. 6 the best composition, we should have — Eo er eo Sodate ah 13-0 MG TTINE? Lock nee IDE RD) iiainieiys es ye one es is? Silico eit ete Se ee 70 °6 Sikieay we es oe Fis) 3: 206 Mr. T. Gray. The mean of which would give— ORAS. boa be eee 9-2 SOCAL esata, soz acl Reitleo ere 6. ime. ha ek Gale eee eee 1S Siltear 20". oan’. Ge eee 730 The alkali is therefore slightly in excess, but to compensate that, there is an excess of silica, the result being a very good glass, both chemically and electrically. Specimen VII. (Arsenic-enamel glass.) AO?G. 2 140 x10 Pat S507) OL So Sihicat See eee 54 °2 105 .. 230K TOU”... ok) Die eiteadtoxidee aaa 23 °9 115 aoe, LOI CHOU ae ee eae ce *10°5 125 oe “AD LOM ot ees ee eda 429 Nae 135 .. 22x 10M: ye. a. veoh mers eee 0°3 Magnesia i... ... 2 0-2 Iron and manganese oxide andalumina 0 °‘4 Arsenic oxide by diff. 3°5 100 0 In this glass we have an excess or alkali for the lead oxide, and a deficiency of silica; the composition is rendered complicated, how- ever, by the presence of the arsenic. Specimen VIII. (Thomson’s electrometer jar.) 100°. Cs... 2060x102... Sve)... ~ Silieal eee 55 18 120 AOS <0E ae i :. lead oxmde ganar 31 Or 140 ae, BOOS MOE yee oe. Potash. ee 13 -28 160 se 2AS SOLO ee ae .. ames. =e oe 0 35 180 £6) 1 LODO LORE bs .. Magnesia <2) ease 0-06 200 #) 12x 10 3. a .. Alumina, iron and manganese oxides. 0°67 100 55 The formula PbO,K.0,Si0,, gives— 6 Silica 2004 she eee Sore iiead oxide.) wise eee Ba Potash’... est eee ee eee 13 °9 * Ratio of potash to soda may be too high. On the Variation of the Electrical Resistance of Glass, &c. re 2: Ee ECE REE ene Selene wo cit Ay He eel le e ae ee Air te | Sey seat | JiMGaalBite eam ee aA Allowing the lime, magnesia, &., to replace one equivalent of lead oxide, this glass very nearly agrees with the above theoretical com- position. This therefore ought to be anexcellent glass, and so it turns out to be electrically. So far as these results go then, the evidence is in favour of an exact chemical compound for a glass of low con- ductivity. In the following table, the resistances at 60° C. of numbers of different specimens of lime glass are given, together with their densities. The first column tells the kind of vessel experimented on ; the second the resistance in ohms of a cubic centimetre, and the third the density. 208 Mr. W. R. Browne. Resistance in ohms Description of glass vessel. per cub. centim. Density. Bohemian tubing.... 605 x 100 a eth 2°430 © beaker.... 425 x 10! Toc 2-427 3 PM ere 542 LOU 2 A454 5 speek eed 715 x10"! 2587 Florence flask....... 469 x 10° 2-523 French eRe ee 996 x 10° 2 533 Japanese globe...... ZLOR< Ole 2°510 Test-tube: <.<:¢s2.<- 144 x 10° 2 Be 2 435 Pe ee oy he 350 x 10? G13. 16 2 44 . io2 ee RR eee 285 x 101° 2 °458 sp.) Site SER RARE eae 125 x 10° 2 467 Fr oo cw Be ec taae ae Ei teas 147 x 10° 2-499 Say ai Rates © te mueee 364 xX 108 2°53 B SoBe ae eee eee ees 155 x 109 2°55 ean ag ees 8740109. <1.) ae 55 1 eRe PRA ORES GG 10 ori 2°667 * , 933 x 10° ‘ese 2 547 The specimens marked (*) were of Japanese manufacture; the first four being potash lime glass, and the last soda lime glass. The other test-tubes were supphed from England, and were probably German white glass. 7 The next table contains a similar comparison for a few specimens of flint glass. The columns have the same meaning as in the last table. Tumbler of toughened glass... 622x10!9 .. 2-670 Piece of tubing. =... 22:6: «2: BOOK 10M ers Japanese globes «i: ec: o6 as. 120 x 10! p35 e240 Cylindrical cup with hemi- spherical base of arsenic- enamel ‘olass. teen eee sc 302 x10? Soa A Thomson’s quadrant electro- MMOGEL falc. eae Vee uate ire 102x108 7 aaa “Qn the Causes of Glacier-Motion.” By WALTER R. BROWNE, M. Inst. C.E., late Fellow Trm. Coll., Cambridge. Com- municated by Professor STOKES, Sec. R.S. Received June l. Read June 15, 1882. The question of the causes which produce the movement of glaciers, which was at one time so eagerly discussed, would appear to have -slumbered for the last ten years. This cannot be said to arise from On the Causes of Glacter-Motion. 209 the fact that a perfectly satisfactory theory has been developed, and recognised as such by all inquirers. The ambiguous allusion to the subject in Sir John Lubbock’s presidential address to the British Association is an evidence that such certainty has not been attained. It is, indeed, generally supposed that the fact of the melting- point of ice being lowered by pressure is somehow at the root of the matter ; but a full explanation of the origin of this pressure in the case of glaciers, and of the mechanical features of the problem, has yet to be given. I may, therefore, be pardoned if I draw attention to a different solution, proposed not by myself but by one of the greatest of English mechanicians. My apology for doing so is that I approach the question as an engineer, not as a physicist; and that it is in its essence, as will be shown immediately, a mechanical rather than a physical problem. The following are leading facts of glacier-motion which must be accounted for by any valid theory on the subject :— (1.) The phenomena of the movement of a glacier are simply those of a solid body in a state of flow. (2.) The present glaciers of Switzerland or Norway, which are the only ones which have been critically examined, are mere shrunken fragments of the glaciers of the Great Ice Age. To take one instance, the present glacier of the Rhone is about 6 miles long and perhaps 500 feet deep ; but the old glacier of the Rhone, which abutted against the Jura, was 120 miles long and must have been 2,000 to 3,000 feet deep. The movement of such glaciers as this must also be accounted for in any satisfactory theory. (3.) The glaciers of the present day are not confined to the tempe- rate region; they are found in much larger numbers and of much greater size in the Arctic regions. (4...) Both in the temperate and in the Arctic regions glaciers move im winter as well as in summer, and by night as well as by day. That a glacier is in a state of flow was first proved by Forbes, and has since been confirmed by the measurements of Tyndall and others. Whilst the whole mass moves downwards, the top moves faster than the bottom and the sides than the middle; the upper layers must therefore be continually shearing over the lower, and the medial over the lateral. WRONG LGN.” len = ev. cient OO) limreNt Sten) ld eNMiReR IR OUIOLleN one LAER ULaN tas ONT SN LON LON ON @N ELON] ONY SOLON LN LEN 3) Date of new | moon begin- ning lunation. 7 5 Jan. 11,1861 Dec. 27 Dee. 24 Feb. 22 Sept. 1 Oct. 14 Nov. 13 Dec. 12 Feb. 10 | | | No. of luna- tion (111) (1 12) 113 114, (161) 162 163 164 165 166 167 HH ODOOOANDDAAMD OOM AAHODMODAMNHHOMOHMSOTHOSOPEODHOSCHOEEORAAANAHTONARDOANH NAD HOWRAH HID TAA DONOR HG DDD HOhNON OHA OAAOTONOAADOHNASCCAONHOR ited ee et oS el Sseaqeeeae ete Se cn A HL lo oo OO ce Oe | Siw HODOFRKNONADA DODO AH ONDAAN OOM AA OMOFARAAHANAVAAHABSSOOH ANAT BV Hy 10 19 DO HED DID AH ODN ODA HIGH HANA DONNS DODO DAA AW ON AY H19 4 DM IGNO ee eS Sees eqeae ee Vr Saal mil Smal Srl dat] Ssseaaet Veo ibys tL fe afeel bal NOAH D1 1D HAHAHA ARABDONAOGOBABAAAAD HORDES MWDADEOMDOGOCHADOHSOMOOHDAWDH HO HOANDON NONI OH HHH DA AOMODADGOSAOVOADONAVGSHOANGMOVODA HOI OIG HO HNN OS Tr os oo oo See Ss SSeS SoS se ne DO DNO ON AHODNOEN DA HOWOSOM MARA TAO ANOSOARADADAWAAOKH AHHH HONS O19 OW HHO HHAH ASCO MOA MISHA I OSCHON DOW GGAAIGONAHANKOOAAASOSOMNHS Sees ee Fert Lesa Deal Semmall Lema Wyma l Lymn fee SSeS Se Te ce FN es Us ce sO Oe | 12 -0° ne © a — Mr. C. Chambers. moon begin- Date of new ning lunation. 240 No. of luna- tion. HOOHMMOAMDMDADOONHNONNARAEADANDMMMOAAAODAMWANRDOANODHAOMANDAANSAP HH Om We BOON 19 DWH 6919 HH OMODNKNONAOA MPHOONH MON DAHHHHNTHOOMONIMDOANATHIBONS tral rant Lr Te Oe OL Vm fre Aral Seml Aeemelolaemtl treet Yl Ce Oc ce UN oF Fa cn | Ce ha fl com om Os ro DON ANH GOOCDHDENDOAHAGAAANOHFH DADO OSAORNAROOOHVSOHDHAANOHONASH NHAAOGGAATHAOASCOAM NOOB GSA SOOOHAGHHAANGAOOOOAIAAANANSCHAOONS Fr rc oc Viral bert Areal Seal (3 I Treerl tral fo SSS St St Sea SSS SS OOO VDOADN DOOD HAD ON HDANKOAAHONHDHDODON HM HOO MNOOPOHHOMAAAIOOA DOD QAP OMOHAGH HOV AAOOON GAN FAA AONNAGCHAFONCHINOMAGATIIIVROAMMBS CH of oD SS et a et nee aa Vet Lat ee rent ema Leal hime 10 MOOR OD HMIDANAHODODOAAKRMOMHOODNARHAAHHOKMHOOHDOONMHAMNAD = SS mor ol Ten lk cen fs fl ce oes ee On | tc coe Ose Ok co FL cs ce Oo | |e Ok ce OE ce ces ON ce Oe ce ce | mment nae es = nN oD _ 10 Yo) a) To) Yo) oO Ca A @ RS Aa SR Ree i NW ar Cure Gey Cie tas = AIRY Cy EC Eee SF ae Ea hE ECE EN ENC olin Chota EN tS EN TERT CS ro rt rei ro ra TOO DDOMAHANNHODORDKHKRMAMAHHDDADROOHAHMHMHADEDOOWHNHHROABMOKRWMMAMAHO aay st Ean MANMNNANNANNANN AAR AR AA AAA MNUNNANANANAAIAA HE mob eek sd Gc kB ho hese es Go eh eo me ae sg oR mS hee a es do ke mS ed €@aaegdaeesos oss aaaergasteoag Seared sasaseasoeSgdtiaarsssrassxysos ag eae sgas & ey ey D } BO 4 — =] o ' Ci Oe Sie SS o ' we est eters let te oO bk CO et Se OD (oy Bde ADROZAAR HAT ARR ANOFZAR HATA RANOAAR HATA R HR ANROOAZARRATARKIAD an: ee DOOaAADEIOCHRDDOAABDAOOR DHOHARDHPOONDAOAARMADOSORDRAOAAMHAMOnRDASCIAH OCORRKRRRK RRR RD DDHDDDD DD DDAMRAAAMBARHADTASDOCODOOCDOSCCO OCA an ten RRR HANNAN ase Hee nent Re RD RRA TD TD A RA RTD RRR RAP RR TAT NANNNANNANNANNANNANNANANNANANAANATNANANAN SS a eed e"“rY a a Nee Ne Ne ee Se” — VSS ew a ee ee } | j | | | 241 Sun-spots and Terrestrial Phenomena. a ee eS | fo) TS TH OM SDM OAHMAWMONOBDGONGHMGODAGSOAEEADHBABOWNMNMDONMAM MIO DOHOMADD OO HH HAVA AR IG HOH HAG NOD DOGO BADIA IODOGHNDDADANOANOOROR IAA HOOH lnal Leal Smal Yred Smal bol Seeqeae Ss ae Sseqeae es S&S Seaseeesesa Ss (allot Seal Simul 1D HOD AMOGOWGOMOHNA DOONAN AROON SAN MANOCONMANDOHODNOHFOMNMOANHONOO BASH IAPOOPOAAHAAAAHOMWOOOGOAUA GS AAAAGHFOOMAHASCSOODONMBOFANBOOR SS SS Frond yal deal Set Lal tom SS el et Sse xqene Ss S&S trl ml trond Leal PAOP MGI O GON DH GOO AANHAOOAGHOHHONNADOHODAWSOHHODHAMHDODOODHOAHN HO ASH MD SASCOHOHN ADHD HAMDOAD OW MM OMANCOAABOW MN DHANHOOHDNOMOHNOHHORD SS) et Vial Lemtl Veal Lreetl Luoal Ima Ss ea ere Soeaeqeeee ss Grott Vametl Aemett Veet Veet Lieu a eee PPR SO Mea Pga tap arpanreomintpe myst SGP ER LO Spo eareginy Up Pect tee tre Cio iGo) GAGES re LR TOGO) SSP GD AO a ea) ew mies ne AS Omen MC ace Oo M10 THADOWMOAMDAMMARMRHDAHOHMAMNHHARDRODDOHNHHMARDE apc al ° NO APSAODAAFASMOMON AAW MORAN SOHOOSHO DE ADDO ON IW OHANON ORONO AD Aw AANA ID DOIDODAHHDMODRDERRHOONHMHNHRDRMERDOHNANDDDOO = SS el SS eee nO Oc cD ed stl FOOONOAHAID 1 12 No. of | Date of new luna- tion. moon begin- | (0). ning lunation. ome ~oOon Ree Re enee ee tome Ne ewe Pe econ ps teeta Me Gee RM EMIS SSH ro else P90, PACO CONG) 0 ADCO SACS \rth oo nncnnee SHAH ASCSCHAHOOHOHAHHARAOENMOHHHARNODOMN DONNA OMMDHAROMIONE |e A coe cen ON ce ce Oe | | A es ce cs oe | [en Al co Bk coe oe Ol | oes oe es ce oe | ae D4 09 09D Or oo ese a ea ge ts. i a NP AVG WI GON OANFOSPMSOAACH DG AD HON AOANN OA MDOOCH RH ANANDROVFOANADAR OY HOF HYD OID IDNA HANA HMDA DO OH OCO ARAN OOHNDNOOHOBANMNDOD 10 Sead | aad =p Yet OM NARA eR LOD ADP OGOHOADHOOODANH FN OOP AGAIN GOHHANADANNENOOHHRANANDAOOARD Vi] HD OTH ODMNANAN HORA DO GHNHHONNANCAAROOMNHHANWOHAALE eetreee oN ef co a Fc BN Ff | ceo fe BON OC AES at) SOOOIARONASD 10 Ne} ~ ee en = ide) ide) a pl ite ide} cc I™ (2 OF ATU OY UE Rt A Se OEE a SI at a Sie a ad PAA MGR Age mesa em I SPRL ESS RS WOO), TN Siu gal Gees RE SRS NN) IO) ae as pane BS Mrs RES NOISY a ES ro ro rm rt rr roa DOOM IDNIOHHMNOBDDKRROHOWMWANNHRDRDODOICOMHAMNCONDOOHHMHANS ra) , SARA AAA AAAS GO) GU GM GaUGNT GCG GU GU GU GU GO GU malice) et el rod el cl ey tice) OS Ore : Ae sey fee we tobacco C5 mai Ae SAT [rr akeb} ee OAT [ft eel b Tem ee ie a ae Lerma i et «bday 5 os BESPokkPahwse se Si oH HRS hws se so HR me oe se SG HR mo hee ee gg oe! SSSESG RISES OSS OS ASAD SS RS SSAC SASHES SRS SS ACE APES a as 68d BBE. OFA RA TARR ANOAZAR RATES 4 ROAAB RSIS ADOFAS He dee ae Ona ses aa SON NON ON ON SN OSS NDS ON NNN SNS NN —_——~ WOMDRAONAMWAHDONRDROHAMHDONRDACHAMHMORDAOHANMHIORDOS a RAN NN & 99 69 00 09 09 00 99 G9 OO HH A HH OH SH SG 10 10 10 18 10 18 1319 1 DO OCH OOO SORRNARNERE RR DS BN EE STS NN PLS VIBENAA AANA MAAAAAANAANNANAVANAIAAN NNN AN Mr. C. Chambers. a 242 BH AMTODAOAADOOANDAOAHHASONDOMBPHAOAON FANNON OOH AFM AGH OOWAHHOGHOR DH KW OMDANHNOMRMOHLrONMUODNAMMVNADDATDODEWOEMEVMAMANOHDDHDOWMNEROANAMOANCAM10COWMDON H Ssqnenee broth Neoal Apa Spat femal tral Sat fecal rool Seok Seal Seal Se eS et et et aere Ee SS in ll aN ca aR NT Si ft AE Pi a eT ae hE SIE ie nlc aan WG Lal L HOOD HA HAFOOMAAANOGORSOOGOHOFVDANDAGGOM ADDON AOA AGO A VGH NAD = B10 99 09 210 Ir OPMOORDNATANMDMDADDOMODAANT TATA AMOOMANMNNDOCODOAORPCONTFTANMDE-DOWEDAAN Ciel (retl Ureral (teal feet! Lee Grab Seal traah Seal tral eal Smal foal Seo Goad Smal Saal ema fal See Se Lo oi NOROGADHA HON OH AN HAOMOGCACNOADONAOMAHBOOHFOHAN FOO ANAOOOAHFONAHAN OPM OOMNAAOCDOOACHDHAOCNTATAOMRDOMOODMIAADRBOAMOAPOUVTAHKNMNNDODOEHNHNDODANM frat Gp rool math freeal Apmal Vd re Vet! Umm Srmtl Smal Seoul \roeal trail Ypetl frm re hal eel et rt re) WASCSCOSPA HOP AON DY AM WM SOAANAM INO DM BOMAAAHDOAN HAHN AGOOAOMAHOA HOM DIDO DIS DWDNOMARWAROMOLPNOMMMIARDDOAOMOAOHACDHADOAMMIOTFWNAN ODDWM10 DM AAW (rail Scott Losoth Sil Sr) eal pil Aemal Srl Sima Tene Peer ree ted yet ree Viooatt Vmotl Yomtt Lett teatl dpmatl Troee Ds Fi fl | SERRE RRRSSSESESSIS AS SASSSSEC IES SSSI ACCEL SETAC SSC onES DID KE RRAANNOARDDMOOOHOCHHMDMNORDOAOLAMRAODCORWDOM MM OMAMAHNBHDMOAY-OnAM dane aaa doy dee SHA eS qe DAD AD DGOWANAOGOHOHOD ANGI NOGA OOM OH ND HAH GGSOOHDNOAROOOHAONOA YAN ONN DOOIDDDNOAHODEMOOKNHAHTAAMODORDMMDAAMAMNOCOHBWMWMOAAODNAMANOCOHAMCINOM eS Stott Simal Sell Steel Sree I Vtootl Grectl feel Staple ool Frmal Tesctl Val Vom] yi 1G 6D) OO) OO) sre eal re) OSES) 6) Es al OD) lI) LTC (SSD S> CONG Ds Ire iti 00) G10) GN 6) QOD SE em ODED NN Se Oe Se Ss DAFONAANODOAWNDD AN AADKEADOMAOMOHMOA HOMO AMON BDONNNANDORNADOONSA ND Sead qo aad 4 aoa eed A Sea —$———— ; DW ADDOIANDADOMOHHHHDODHNNAMND MON OM ON MOEEEEDHROMEAMEMNDDADROSCHANDH iS DEX HiDDHONDMANOCHDKR EWE AHONWMMOHRDEMOODMOHHHODAEMMOEAAAAMOCOROMODOONH Saoqgeee aod dade saeoeee eS Soret el . rq ON on H i fl = i~ I~ I~ ™~ E SRO COuRceinase atin NO UA ita RERUN Ruin RUNG) Rm ROAR Rann OR A 8 ROO AD Ay AR RER DURE ROR RCO R A Rate kena als (ab) i " « n a HO SRDOMMOANATDHAAOBRDKROMANNSCARDHHOMOANHNAHOCODNOHDEOMAHTDAADOCODNRDOOAMNOOAND oe DAANANANNANNNANNA AA eae DONNANANNANNAANAD AAR AR AAA Ae o Rm : ' . cS owe 6 i= o . : Oo hel 0) ss . a a ® OAD : # 2 o bBo bape > oo Om ol elem eaeiteloy=) Ge eS hy ae fae, By Peet sr POG Ho me Peoe se S a HE b bs op b As SASPRSSSASS ASA TA AS SSAC RASHES SRS OSU AOS AS EEE SS OS ROE ASE eS 8 ; SSK AROZAR HATE KR ANOFZAR HATA RANOFAAAR HATA KHRANOAARR HAATARHANROAA Gy — o a ¢ DRESS NROARSFOSOHDASAAHDHFRSKDDSO YG AHH 19 OH HAS AA 416 ON HDS AAG FH 19 © tr SHS | DBHDDHDHHDLAAARABBRARABSDODCOCSOSOOOTG AAA AAA ANNA AA A A A A OD 09 09:00 09 OD Cd OD 09 Cae NAN ANNA AA AA ALAA ALALALA AI 00 OO OO 00 GOOD DFO OD BO OD 1D OD OD OD OD OD BD TD 0D AD OD OD OD OD CD CD OD CD CD OO CD 9D GD CD OO CH OD OD pa ro ee ee ee we Ne ee ee wa SS ee Se ee eS” Nee ee SS SN es Ne” we ee eer ee ee” 243 Sun-spots and Terrestrial Phenomena. —_ it~ SS AON AL AAA DADA DDGHOANAAHFHAONAOADOAH HAMA DA RAAAHOOFENASOOAG HAYA DI GOM MOG HATH GOO ODAGAAAAOAAEM NOVA AUNSOHOOGMORAS A Gro ao rw see aee SS Foe oe On Lest) (rex! tral Ll mal Lm Tc oe | a ei aaa SS ELI Te ae ie Rae OE ee Pe ee re ee ee fp eo) Pa Tike) Wo) Wo) far) ) oN) Lo) Yo) sil ip) Yen) SSN] Cah ail No Mer NE NCHS teal Not SS ale 21102) pil or) Coos) Nts) CIOS sil oe) he) 9s 0) ro oN DADO DOOMOSCABANG AH SwHNHOUNUOANAOOM NODS CDAMAARDAErUUDHTWMOMNAANTHD®@®Or Sseanneaee es Ser at Seal Il Sool beetle) al teal td Ts cs De eee ee ee ——— oe (5). Rig DWOADOAM DDH AAAADHOAADTODADOSODOHAANHODHLHFAODAOPSAONOHN WD QOAADOGMOAGAAAGCAOMOOW ANA IANGHAOMWAAGAAYAGAOMOMSSBAAATAMOT Seen et Great Got Lert feet Goal Leal Lol ool (eal fal teal Yall seoesetae ee eS RO 191 HOOARKNODAARATDOHHDADOMAGAAAOWORONMDAAOADO OH WH O19 168 HAD AOBASD AOSCOAOOOOAHHDHOCAARCGOOGOOON MD GHA OAHDOMOGOWHANADGANRHANAMOSHAAHOONO. saad Do nD | SsetanAe es S Str bet el Lema! Ltt Lom Lrtl Unt tl DOA MD OCOOOW DAN OMADWHAWOWOWOAAHAAOWMOSOONMNH AM OWNS AADDOMIDOR WOO Ow OCOD OOD ROR HANH ADADDN OMAN AMANOARMORNRDDASCNHHHOHDOMWOARHAHANDNDORMDOWO eo Ssqaane Co Ln OL I See eS SS Foe Ln Lt es J ee 0808 600 060 Le ea osm i me CRAPAMKAAHAN DEW OH OHAMKRKNOMONDASCHOOOCONANAPAOGHDNSONMHNOAANOONH | HD AY ACADOPAABUHAGCAD AL WOGOODA GG AI GOD HOWDHAGATAGARMOMGAAY YA AO rw Fon (| fl al tal tal i! Ce EA tL coda | senna SA ean Se ee UU E UE EnEE EEE SEEEEEEEenne Date of new No. of “—~ = wa moon begin- ning lunation. luna- tion. MAL OAAOOHOBDOSCAARAVASCHODODOOSCHAAEOWOAHFOAAAAROANDOOGOAFANATOVSARAVT ANN YASH DMD FAO HAVSCHO ODM WOK AA PAAVSCDSODHNHNSN AA AADBODO TANG IAA SO w See See SS eS Un Ic Oe on soeqnqnqee Ssqeqnee et ts Meee SE eae ee en ee oo HAOAAW HOON FON AFAOMNMHMOADHARBONDHON OH ASCSOWARDHAPHMBWLWHOSOAANADAGO STS HAN O DDR OODONDANNRADKROOKNOHHMANADDAOKDNRONGAAHAHHORHDHONDHADONACANE Sse sqnnre Soret ee ere Fes en ces ce oO | ese se ae estas es Ne) CO ~ ore) fer 5 5 5 Sone 5 Bn SS Re QTR aa PR NRE CC GMa Si Ce GN oN ie BAY BNE US SA FRE RS RER RY a IN EEN rene cre ro (rl re rd ri MOD O10 FM AADADDO MOAN AIDA DKO WPM MHHAKKWMHATMAHSOOHOOHMANAHIHOD Fe eee OCH OS LNT onl ORT ed et et a ee MANANNANNANAANANA SS De eo bo betes eS Gente bso Prep os) sie keel oor ens , SoHo mo So bes PSH eS AGRE RETR P RS SSAC ER EET RSS SEG SRS ED ERS SSAC RASH EASES SBOE oS BS Le bt ‘ vu o x | o g Bes aS Fees BORA ees 4865 48 OZ A656 RS 425540 0OF ASRS AHS ARORARRATABK ae em eR Src sh Sn ca «gee a se nS al lh tng kt NNN LON NN OS NN ONS [NN ON EN ENS RN INS CDRA OSRDAOAAMPROLRDDOANMAH WON DRO AA Hr ON DBSAAD HW ORMDRBOANNTES ROT GSS GSS SSS ww oO TOSSOSSDOOSCHEREEEEEERDHHOHHHHDHNDRABRRS QD GD OO, CO, C9, 9 C9, OD GD GD GD GD CD GO, 09 CD C9 OD OO CD CD CD CD GD GD CD OD CO GO CO LO OD Me CD CD GD OD OO Ca Ce ew C OS ee Sas 244 Mr. C. Chambers. No. of | Date of new luna- |- moon begin- || (0). | (@). 12) 176). @: Os O)r ae tion. | ning lunation. —— | | | fl | | (396) | Aug. 18,1879} 6°3°| 5:9°] 68°] 7-72! 6-8°] 7-1°] 8-3°| 8-7° 397 | Sept. 16 ,, Seay 17 Oy FSM ATS a 78 e700” | om mel 398 Oct wo... 10-5 | 12°27) 12-85) 13-0") 12-3) TOS | W2Se GEO 399 INovae law. 14°7 | 13°8 | 138°5 | 14°6 | 16°6 | 15:1 | 13°6 | 15-0 400 Dec. 13 ,, 15-1 | 13>) 15667) 15-4 WS | 42) Ae alia 401 Jan. 12) 1880) 13-4 | 13°87) 12°61 15°6 | 17-6 | 15:0) | Lamy ais 402 Hebe Om. 14-4) V2 21 |) 13-2 14-2 | d48e Zoe ais (403) | Mar.11 ,, | 11-3] 11-5 | 10-4 | 9-4 | 10-9 | 12°83 | 12°5 | 11-5 (404) | April 9 , | 10:0] 8-8] 9-9] 10-6] 10-1] 9:7] 9-9 | 10-0 (405) || May 9 5, | 9-5 | 94l)| 9-3) %9-3)|%o-0 | 16-47) ze on mer (406) | Juno 8 , |. 9:0] 79) 75/ 7-8) 8-7) 82) 6:6) (6% (407) | July 7 ,, 7-15) 6°99") 16°07) 07-8) 16:9 |. 6.36). 7 O56n aaa (408) | Aug. 6 ,, | 96°51) 6-2) 651 16-81''8-0 | 6-4) na conmaee (409) | Sept. 4 ,, | 7-1| 8:3) 9:0] 66| 6-2] 7:4) 752) 77 8. The whole series of 409 lunations gives the following result :— Bhaserotunationy-cc-ccsssnsecs se | (0) (1) (2) (3) (A) (5) (6) (7) 10°69 | 10°67 | 10°67 | 10°73 | 10°77 | 10°66 | 10°61 | 10°66 |} (A) Walulelot rane emenes-eecee-eocee eee A series which, like that found by Dr. Stewart from the Kew tem- perature-ranges, has two maxima and two minima, but every turning- point in the Bombay series occurs somewhat later on in the lunation than the corresponding turning-pointin the Kew series, and the range — (0°-16) of the Bombay series is less than that (0°46) of the Kew series. The sum of the four left-hand numbers (42°76) is also larger, as in the Kew series, than the sum (42°70) of the four right-hand numbers. Series (A) is curved in fig. 2. Dividing the whole series into two parts, we obtain— | iaserotlumeatlonsenecenescsraces (0) | (1) | (2) (3) (4) | (5) (6) | (7) Range (1847°75 to 1863°75) ...} 11°32 | 11°36 11°42 \'11°53 | 11°49 | 11°32 | 11:30 | 11°25 | (B) (1863°75 to 1880°75) ...| 10°10 | 10°01 7 9 +96 : 9-98 | 10°10 | 10°05 | 9-96 | 10°11 | (C) Upon which it may be remarked that, though possessing, of neces- sity, points of similarity to the series (A), these two series are far from being identical with it or with each other. D. Semi-annual Lunar Variation. 9. In dividing the lunations into winter and summer lanations, we had inadvertently chosen the 21st March and 23rd September, instead of the 3lst March and 30th September, as the dates between which, Sun-spots and Terrestrial Phenomena. 9AD if the middle of a lunation occurred, the lunation should be considered a summer lunation, and the serial numbers of such lunations in Table III are enclosed in parentheses to distinguish them from the others, which are to be considered as those of winter lunations. The average date of new moon will be about the 22nd of each month, and, accordingly, in eliminating the residual effect of the annual variation upon the lunar variations for the winter and summer half-years, the beginnings of the several months have been taken to correspond with the average time of first quarter of the moon, and the respective half- years have been made to commence after the lapse of three-quarters of the months of September and March. The numbers at the foot of Table Ia having been curved on a large scale, the ordinates of the curve were measured for every eighth of a month, and the averages were taken of the six sets of eight numbers corresponding to the winter lunations, and of the six sets corresponding to the summer Iunations. These were then multiplied by 1:069, the ratio of the average scale of the 409 lunations to the scale of the period 1873 to 1880 (that is, of Table Ia), and the variations were then taken—with the results that will now be made use of. The values of temperature-range found for the eight phases of the winter lunations, of which there are 199, are— 1 ! Phase of Iunation ............... (0) (1) (2) (3) (4) | (5) (6) | (7) NGAI ANI OC Wee wacsseacceascesecoes 12°50 | 12°54 | 12°73 | 12°89 | 18°00 | 12°92 | 12°91 | 13°02 | (D) Correction applicable to win- ETEMLONMBMSH Steere vac acc esecce-ne<0 +°33 | +°25 | +°13 | —-01 | —°09 | —°15 | —°20 | —°24] (E) Correct value of winter lunar MAN ROP ease ee nese secs decscnescees Pe) || WAC) eseetoy 3) PACs si Trae || Tae re |) MPACTal Ny PAGrisy || (1) and for the eight phases of the summer lIunations, of which there are 210, they are— | | Phase of lunation ............... (0) (1) (2 | (3) (4) (5) CG) a) Weanlrange .....0<..-<. SaabonCadoar 8°98 8°89 8°72 | 8°69 8°66 8°52 | 8°42 J 8-43 | (G) Correction applicable to sum- | | | cna wat ee —°30 | —21 | —-12 | —-04 | +04 | 4°12 | +°20} +°27 | (H) _ Correct value of summer | | | UT ANTAN GE: (eases ceescss ses sce: 8°68 | 8°68] 8°60 | 8°65} 8-70 8:64 || 8:62)|| S270) || () Fig. 5 represents the corrected variation for the summer months, and fig. 4 for the winter months. The winter curve, like that of Kew, is mainly a single period curve, and its maximum and minimum phases both occur somewhat later than at Kew. The summer curve is of smaller range; again, lke the corresponding curve at Kew, but unlike the latter, it is a very regular double period curve. 10. The excesses of the two series (F') and (1) above the series (A), that is, the semi-annual inequalities of the lunar variations, are— JAG Mr. C. Chambers. ? hase of lunationy sess see (0) (1) (2) (3) (4) | (5) (6) (7) Winter inequality ........... ... +2°14 | 4+2°12) +2°19] +2°15 | +2°14) +2°11] +2°10] +2°12) (J) —2-02| —1-99] —1-96| (K) Summer inequality............... —2°01} —1 ss] —2:°07 | —2°08 | —2°07 ! Curves representing the series (K) and (J) form figs. 7 and 8 respectively, and they are, necessarily, nearly opposite to each other in character, and, like those of Kew, they are in the main single period waves, but with the maximum and minimum phases occurring later at Bombay than at Kew. li. The next two series (lL) and (M) are the winter lunar varia- tions for the periods 1847°75 to 1863:25 (sixteen winters), and 1863°75 to 1880°25 (seventeen winters) obtained in the same manner as series (Ff). They are curved in figs. 5 and 6, which though possessing little likeness to each other, have, of course, each points of similarity with fig. 4. Phase of lunation .......0...... (0) (1) (2) (3) (4) (5) | (6 (7) uaniher ee 16 years...) 13°43 | 13°58 | 13°69 | 13°79 | 13°62 | 13°43 | 13°46 | 13°36 | (L) variation. Last 17 years...) 12°26 | 12°03 | 12°06 | 12°01 | 12°23 | 12°15 | 12°00 | 12-23 | (M) It may be noted that the series (L) and (M) bear nearly the same relation to the series (I) that the series (B) and (C) respectively bear to the series (A), a fact which, combined with the knowledge that the summer lunar variation is of small extent, implies that the winter months contribute nearly the whole of the irregularity which distinguishes one half of the period of thirty-three years from the other. Hi. Possible Variation of the Lunar Effect with the Sun-spot Period. 12. In order to examine the relation of the winter lunar variation to the sun-spot period, the winters chosen as corresponding to the minimum and maximum respectively, of solar activity, are 1854-55 to 1856-57, 1861-62 to 1866-67, 1872-73 to 1874-75, and 1857-58 to 1860-61, 1867-68 to 1871-72. These groups of winters give results as follows :— Phase of lunation ............... | (0) (1) (2) (8) (4) (5) (6) (7) Winter variation (minimum |, period) corrected for (I)...... 12°90 | 12°67 | 12°49 | 12°85 | 12°54 | 12°62 | 12°71 | 12°89 IDXELGNDKOLG, (12) soaoosccacdooedseoo00 080086 12°83 | 12°79 | 12°86 | 12°88 | 12°91 | 12°77 | 12°72 | 12°78 Supposed effect of solar WOUUAWUONYPEON Cosgonnoopagcoddednenbot +:07 | —°12 | —°37 | —*53 | —*37 | — ‘ld “00 +11 ) (N) Sun-spots and Terrestrial Phenomena. 247 and Phase of lunation ............... (0) | (1) (2) | (3) | (4) (5) (6) | (7) | Winter variation (maximum | period) corrected for (E)...... 12 A L2cs oer ol aroha i 2eee W222) 12204 \ 12-15 MCCUICH(E) scscscccscsscctecssscuseane 1QES3a) 2M eeSonlecssn ele OL (Laci |) Teil 12-48 Supposed effect of solar | RUM AKMNNILIM = Sic cance ccesseiscecss see —°69 | —°44 | —°35 | —°57 | —°47 | —°55 | —°67 | —°63 | (P) i 13. For the sake of comparability with Dr. Stewart's results for Kew, which may possibly refer to winters a year later in every case than those named above, we have repeated these calculations on that supposition, and have obtained, in lieu of series (N) and (P) the following :— | Phase of lunation ............... (0) (1) (2) (3) | (4) (5) (6) (7) Supposed effect of solar MIMMMMETNELIYE <5 cso. o0-eeaeeesee--s =10 |) wil || Bee Se |) ee || es ci 00 | (N’) Supposed effect of solar PRL AKAMTINY, oo.6n.s.3-2ncn5-0enees = FS |) = CF el RN) sy) SRY as) cay | (024 | The series (N), (N’), (P), (P’) are curved in figs. 9 to 12. Con- trary to the Kew series, they show that the temperature-range is somewhat less when sun-spots are excessive than when they are defective, the mean values of the several series being —‘17, —-21, —‘54 and —°50 respectively. Figs. 9 and 10 are much alike, and imply that the general winter lunar variation found in this way is subject to a pronounced change of character during the time of deficient sun-spots, having superimposed upon it a variation of single period and of greater range than its own. This affords a partial explanation of the great difference between the curves of winter lunar variations for the first sixteen and last seventeen years (figs. 5 and 6), the latter period being made up of years of deficient sun-spots in greater degree than the former period. “Sun-spots and Terrestrial Phenomena. II. On the Variations of the Daily Range of the Magnetic Declination, as re- corded at the Colaba Observatory, Bombay.” By CHARLES CHAMBERS, F'.R.S., Supermtendent. Received May 30. Read June 15, 1882. The present, like the preceding, investigation is on the model of one by Dr. Balfour Stewart, dealing with similar records obtained at the VOL. XXXIV. S 248 Mr. C. Chambers. Kew Observatory.* The records extend, in the present case, from June 1, 1847, to December 31, 1872, and consist of differences (always taken to be of positive sign) between the highest and the lowest values of easterly declination observed by Grubb’s declination mag- netometer} on every observation day of the period. Until the end of the year 1865 the observation day was the Gottingen astronomical day ; after that time it was the Bombay civil day. The daily differ- ences were obtained from hourly observations made on all days except Sundays and a few holidays in each year. Grubb’s declination magnetometer is of the well known form described in the Report of the Committee of Physics of the Royal Society, 1840 (p. 13). Up to 1868-00 each individual entry in the register of the scale-reading of the instrument was at once converted into easterly declination in minutes, and the daily ranges are the differences of such converted readings, but after the date named the differences of the scale- readings were first taken, and then converted into minutes. The ranges include the effect of disturbance. A. Annual Variation of Declination-Range. 2. The year being divided into forty-eight equal parts, commencing with the midnight between the 3lst December and Ist January,{ means. were taken of the ranges for the fifteen days preceding and fifteen days following the nearest midnight to the commencement of each A8th part of the year. Attributing four of the 48ths of a year to each month, and designating as ‘“‘monthly means” the thirty-day means thus obtained, the following table exhibits each of the forty-eight results for each year, and on the average of all the years:—(See pp. 250 and 251). The numbers in the last column are taken to represent the annual variation-—combined with the annual mean value—of declination- range. B. Variation of Long Period. 8. Proceeding now on Dr. Stewart’s hypothesis as to the relation between declination-range and solar activity, we divide the numbers in each line of Table I by the mean number (an the last column) of that line, and multiply the quotient by 1000, thus obtaining a table “exhibiting the monthly means of declination-range (forty-eight points to each year), the mean value of the range for the whole series * Proc. Roy. Soc.,” vol. 26, p. 102. + On the rare occasions when this instrument was under adjustment, the blanks in its register were filled up from the register of a small declination magnetometer which was used as a subsidiary instrument. { Leap-years were taken to contain 366 days, and other years 365 days. GNI l Phenomena. ta restr Sun-spots and Ter Qe Sorts ae O481 e428 12et e981 v9Bl £58) 2981 198) O98! 6G&8i 8561 498) 8) 666) +401 E581 GSHL 1ho1 O56) bol Obul ZPel ™ op) 250 Mr. C. Chambers. Table I.—Containing Monthly Means (48 to the year) of the Diurnal which the Middle Date is the very commencement of the Year, 1847. | 1848. | 1849. | 1850. | 1851. |: 1852. | 1853. | 1854. | 1855. | 1856. | 1857. | 1858. January (0)...... | 4-22 | 3:20 | 2-62 | 3°04 | 2-56 | 2-80 | 3-05 | 2-45 | 2-85 | 2-44 | 3°37 di (Gd ganes 3°50 | 3°54 | 2-98 | 3°30 | 3°15 | 2°87 | 3-22 | 2°51 | 2°99 | 2°58 | 3-28 B (2)eeee 3°72 | 3°81 | 8°11 | 3°29 | 3°11 | 2°86 | 3-27 | 2°50 | 3°02 | 2°49 | 3-38 a (3) nee 3°65 | 3°85 | 3°91 | 3°34 | 3°19 | 2°79 | 2-96 | 2°53 | 2°80 | 2°43] 3-01 February (0)......! 3°87 | 3:75'| 3°85 | 3°07.) 3°26. 1 2:70 | 2-91 | 2-49 | 2°58. 2°45 | 265 uae (1)..e4e4| 3°45 | 3°65 | 3°56 | 2°81 13°45 | 2°65 | 2°70 | 2°47 | 2°30 | 2°48 | 2°74 (OW es 3°20 | 3°77 | 8°33 | 2°50 | 3°31 | 2°47 | 2°72 | 2-41 | 2-24 | 2-39 | 2-74 :, (Geant 3°25 | 3:76:| 2°55) 2°47) 3-51 | 2°47 | 2:67 | 2°47 | 2-17 | 2-22) ) 9-09 March (0).. 3°67 | 3°86 | 2°80 | 2°65 | 3°52 | 2°66 | 2°58 | 2-64 | 2°18 | 2-04 | 3°58 ae (eeu 3°96 | 3°98 | 3°11 | 2°86 | 3-31 | 2°95 | 2-68 | 2°61 | 2°36 | 2°19 | 3°85 ce (2) eee 4°42 | 4°31 | 8°57 | 3°19 | 3°63 | 3°27 | 3°04 | 2°96 | 2°56 | 2°29 | 4:06 A: Gee 4:69 | 5°10 | 4°01 | 3°55 | 4:06 | 3°87 | 3°44 | 3°45 | 3°35 | 2°56 | 4°53 April (sseaee 4°66 | 5°52 | 4°89 | 3°92 | 4-37 | 4°57 | 3°87 | 3°57 | 3°91 | 2°91 | 4°69 ay ali) 4°66 | 5°70 | 4°65 | 3°99 | 4°80 | 4°71 | 4:39 | 4°27 | 4:21 | 3°26 | 4-78 e (2s 4°91 | 5°45 | 4°67 | 4°08 | 5:41 | 4°92 | 4°37 | 4°40 | 4°17 | 3°67 | 5°03 As (Brace. 5°28 | 5°15 | 5°11 | 4°34 | 5°43 | 4°86 | 4°61 | 4°60 | 3°91 | 4°10 | 4:97 May (O)nee 5°49 | 5°13 | 5°49 | 4°41 | 5°37 | 4°56 | 4-84 | 4°82 | 3°57 | 4°58 | 5-07 Es Gye 5°45 | 5°57 | 5°56 | 4°42 | 5°57 | 4°93 | 4°86 | 4°69 | 3°60 | 5°02 | 5°36 Fs (2)nee 5°45 | 5°75 | 5°94 | 4°82 | 5°33 | 4°96 | 5°09 | 4°51 | 3°72 | 5°03 | 5-49 be (3).. 5°45 | 6°11 | 5:79) 5°00 | 5°35 | 5°13 | 5°11 | 4°58 | 3°80 | 4°88 | 5-42 June (O)enees 5°39 | 6°13 | 5°67 |.5°11 | 5°51 | 5°65 | 4°99 | 4°41 | 3°90 | 4°73 | 5-12 ma (GD nase 5°52 | 5°84 | 5°75 | 5-45 | 5-48 | 5°57 | 4:90 | 4°39 | 3°98 | 4°18 | 4°85 ie (Outen 5°46 | 5°78 | 5°78 | 5°72 | 5°42 | 5°86 | 4°78 | 4°60 | 4°20 | 4°23 | 5:02 ” (3). 5°55 | 5°53 | 5°81 | 5°75 | 5*39 | 5°94] 4°89 | 4°65 | 4°04 | 4°34 | 5°16 July (soneen 5°92 | 5°80 | 5°97 | 6:00 | 5-20 | 5°78 | 4°86 | 4°42 | 4:06 | 4°37 | 5-33 ee Gee 6°24 | 5°78 | 5°81 | 5°85 | 5°40 | 5°89 | 4°62 | 4°42 | 4°26 | 4°52 | 5-42 Ms (2) 6°40 | 5°89 | 5°65 | 5°45 | 5°38 | 5°82] 4°57 | 4°21 | 4°30 | 4°26 | 5-48 A @osnee 6°68 | 6°10 | 5°52 | 5°10 | 5°37. |.5°95 | 4:44 | 4°12 | 4°58 | 4°30 | 5-44 Anteust, (O)seece 6°62 | 5°90 | 5°20 | 4°75 | 5°74 | 5:97 | 4:43 | 4-23 | 4°90 | 4°30 | 5°84 i (yee 6°71 | 6°11 | 5°37 | 4°81 | 5°86; 6:24 | 4°74 | 4°31 | 4°97 | 4°58 | 6°16 es (2). 6°88 | 6°21 | 5°43 | 5°10 | 5-95 | 6-44 | 5-02 | 4-53 | 5-00 | 4°93 | 6-21 BS (3) 8 7°01 | 6°26 | 5°91 | 5°60 |} 6:18 | 6°91 | 5°18 | 4°88 | 5°47 | 5°82 | 6°32 September (0)...... 7°21 | 6°37 | 6°10 | 5°58 | 5-98.| 7-09-| 5-22 | 5-62 | 5°51 | 5°70 | 6°22 Mh (UW) eeesee 6°86 | 6°16 | 6:40 | 5°88 | 5°14 | 6°88 | 5°15 | 5-91 | 5°49 | 6°06 | 6°06 i (Qe 6°52 | 6709 | 6°18 | 5°63 | 4-89 | 6:42 | 5°05 | 5°48 | 5°25 | 6°12 | 6°02 A (3) 6°00 | 5°47 | 5°74 | 5°42 | 4-19 | 5-38 | 4-61 | 5°13 | 4-40 | 5°67 | 5°59 October (0)... 5°49 | 4°89 | 4:90 | 5:00 | 3°57 | 4°34 | 4:02 | 4°16 | 3°71 | 4°87 | 5°02 rs (1) 4°98 | 4:13 | 4°05 | 4°61 | 3-55 | 3-41 | 3-74 3°59 | 3°09 | 3°95 | 4°24 , (2) 4*11 | 3°29 | 3°48 | 3°54 | 3-27 | 2°75 | 2°85 | 3°09 | 2°52 | 3°14 | 3°71 ” (3) 3°34 | 2°66 | 2°78 | 2°87 | 2-96 | 2°64 | 2-41 | 2°74 | 2°86 | 2°28 | 3°26 November (0) 2°58 | 2°50 | 2°56 | 2°63.| 2-84] 2°54 | 2:14 | 2°55 | 2°05 | 2°18 | 3°03 as (1) 2°76 | 2°37 | 2°37 |2202 |.0-54 1948 19-04 | 2°38 | 1-89 | 2-80 | 2°98 ” (2) 2°89 | 2°80 | 2:18 | 2°89 | 2°52 | 2°36 | 2-16 | 2-39 | 2:00 | 2°80 | 2"bb ” (3) 3°11 | 2°93 | 224°) 2:00'| 2-74 | 2'44-),9'-34 | 2-33 | 2°28 | 2°50 | 2°48 December (0) 3°17 | 2°84 | 2-81 | 2-42'| 3-15 | 2-52 | 2-45 | 2-49 | 2-89 | 2-82) | 2°39 uy (1) 2°88 | 2°79 | 2°38 | 2¢272) 8°10 | 2°55 | 2°40 | 2°40 | 2-40 | 2-76 | 27382 ms (2 2°76 | 2°39 | 2°72 | 2°38 | 3°17 | 2°63'| 2°35 | 2°47 | 2°38 | 2°98 | 2°68 us (3) 2°93 | 2°49 | 2°76 | 2°41] 3°09 | 2780 | 2°26 ; 2°81 | 2°50 | 3°24 | 2°98 Sun-spots and Terrestrial Phenomena. 251 Declination-Range, thus:—January (0) gives the Monthly Mean of January (1) that for one Week after the commencement, and so on. 1859. | 1860. | 1861. | 1862. | 1863. | 1864. | 1865. | 1866. | 1867. | 1868. | 1869. | 1870. | 1871. | 1872. | Mean. BelgamerOS 26a} 25791) 2091 (22145) 300" 27s) 2738 2-00) 2482 |) 3-28 |). 3.715 | 2°92) 2-84 3°42 | 3°09 | 2-90 | 2°70 | 2°96 | 2°41 | 3°15 | 2-95 | 2°90 | 1°82 | 2°69 | 2°96 | 3°28 | 2°99 | 2-96 3°60 | 3°18 | 3:05 | 2°89 | 3°02 | 2°53 | 3°34 | 2°88 | 2°84 | 1°90 | 2°94 | 2°95 | 3°32 | 3°08 | 3°04 3°39 | 3°19} 3-05 | 3-19 | 3:02 | 2°66 | 3-24 | 2-93 | 2-79 | 2-13 | 2:97 | 2-86 | 3°21 | 3°89 | 3-08 3-44 | 3-20 | 3°02 | 3:29 | 2°85 | 2°82 | 2°95 | 2-90 | 2-75 | 2-09 | 3:03 | 3°21 | 3-24 | 3-97 | 3:03 3°30 | 3°19 | 2°86 | 3-05 | 2°72 | 2°66 | 2°94 | 2-98 | 2-29 | 2-21 | 2°69 | 3°36 | 3°07 | 3°90 | 2:94 3:12 | 3:04 | 2:97 | 2-97 | 2°65 | 2°69 | 2-69 | 3:10 | 2:06 | 2°17.| 2°48 | 3:40 | 3-18 | 3°96 | 2°86 3°15 | 3°26 | 2-95 | 2°53 | 2°60 | 2°69 | 2°50 | 2°83 | 2°18 | 2-04 | 2°39 | 3°36 | 3°32 | 3°42 | 2°79 SEaimiesesOnina 20) | 2-51 | 2-60 | 2°87 |) 2-53 1) 2-87 | 2-13 | 2-30.) 2-60) | 3-12 | 3-40 | 3°62 |-2)-92 3°81 | 3°61 | 3°54 | 2-99 | 3-07 | 3°17 | 2-83 | 2:92 | 2°20 | 2°52 | 2°84 | 3-48 | 3:90 | 4°25 | 3°16 4°33 | 4°35 | 3°90 | 3°72 | 3°17 | 3°28 | 3-13 | 3-13 | 2°84 | 2-85 | 3°35 | 3-93 | 4°43 | 4°66 | 3°53 4°83 | 4°63 | 4°58 | 4°30 | 3°31 | 3°84 | 3-35 | 3°56 | 3°07 | 3°45 | 3°86 | 4°75 | 4°73 | 4°41 | 3-97 5°37 | 4:96 | 4-72 | 4-84 | 3°79 | 4°10 | 3-62 | 4-08 | 3°44 | 3-81 | 4°39 | 5°31 | 5-18 | 4°68 | 4°35 6°14 | 5°12 | 4°80 | 4-88 | 4°11 | 4°23 | 3-86 | 4:12 | 3°97 | 4°60 | 4°75 | 5°57 | 5°76 | 4°98 | 4°65 6°29 | 5°15 | 4°84 | 4°75 | 4°23 | 4°44 | 4-30 | 3°93 | 4°12 | 5-09 | 4°57 | 5°66 | 5-98 | 5°41 | 4°79 7°00 | 5°46 | 4-77 | 4-66 | 4°82 | 4°33 | 4-67 | 3-96 | 4°43 | 5-11 | 4°52 | 5°24 | 6-01 | 6°06 | 4-94 6°98 , 5°77 | 4°80 | 4:28 | 4°97 | 4°25 | 4-73 | 3°81 | 4°46 | 5°05 | 4°94 | 5°37 | 5°86 | 6°27 | 4°99 6°87 | 6:01 | 5°09 | 4°47 | 5°19 | 4°42 | 4-75 | 3-76 | 4°38 | 4-82 | 5°21 | 5-61 | 5°82 | 6°33 | 5°11 6°88 | 5°99 | 5-10 | 4°78 | 5°56 | 4°94 | 4°68 | 3°93 | 4:21 | 4°55 | 5°49 | 6°05 | 5-85 | 6°43 | 5°22 6755 | 9°97 | 5°83 | 5-11 | 5°57 | 5°37 | 4°60 | 3:98 | 4°14 | 4°73 | 5°77 | 6°32 | 6-21 | 6°07 | 5-2 6°34 | 5°90 | 5°75 | 5:41 | 5°42 | 5°72 | 4°66 | 3-90 | 4°03 | 4°99 | 6°01 | 6°50 | 6°52 | 6°04 | 5-35 6°05 | 6°13 | 5°80 | 5-42 | 5°11 | 5°91 | 4°75 | 4°04 | 4°11 | 4°88 | 6°11 | 6°55 | 6-17 | 5°83 | 5°31 6°17 | 6°77 | 5°70 | 5-64 | 5°02 | 5°47 | 4°93 | 4-05 | 4°29 | 4°86 | 6°15 | 6°71 | 6°51 | 5°85 | 5-37 5°77 | 7°05 | 5-78 | 5-42 | 5°15 | 5°35 | 4-98 | 3-90 | 4°37 | 4-60 | 6-09 | 6-68 | 6-26 | 5°49 | 5-36 5°88 | 6°74 | 5°85 | 5-31 | 5°22 | 5°18 | 4-60 | 3-79 | 4°50 | 4°35 | 5°86 | 6°60 | 6-01 | 5°54 | 5°32 5°84 | 6°69 | 5°57 | 5-13 | 5°37 | 4°87 | 4°38 | 3°73 | 4°59 | 4°22 | 6°01 | 6°94 | 6-44 | 5°58 | 5°34 5°84 | 6°34 | 5°76 | 5-00 | 5°46 | 4°67 | 4°16 | 3°58 | 4°76 | 4°15 | 6°10 | 6°67 | 6-31 | 5°85 | 5-26 5°55 | 6°50 | 5°98 | 5°10 | 5°23 | 4°63 | 4-45 | 3°57 | 4°62 | 4-06 | 6-09 | 6°96 | 6-09 | 6°16 | 5-28 5°31 | 7°52 | 6°05 | 5:47 | 5°31 | 4°87 | 4°71 | 3°62 | 4°49 | 4°14 | 6°33 | 7°03 | 6°55 | 6°28 | 5-40 5°65 | 7°99 | 6°62 | 5°84 | 5°05 | 5°23 | 4°95 | 3-71 | 4°62 | 4°68 | 5°85] 7°19 | 6-82 | 6°23 | 5-59 6°48 | 8°47 | 7:04 | 5-80 | 5°12 | 5°82 | 5-01 |. 4°13 | 4°50 | 5°25 | 5°92 | 7-62 | 7-13 | 6°46 | 5-85 8°81 | 8°36 | 7°15 | 6:08 | 5°18 | 6°06 | 4°76 | 4°39 | 4°70 | 5°90 | 5°93 | 7°70 | 7-45 | 6°46 | 6-16 9°00 | 7°67 | 7°11 | 6:01 | 5°19 | 6°18 | 4:77 | 4:43 | 4°72 | 6°36 | 6°25 | 7-60 | 7-44 | 6°61 | 6-25 8°82 | 7°12 | 7°05 | 5-82 | 4°96 | 5°92 | 4-82 | 4-59 | 4°47 | 5°83 | 6°35 | 7°64 | 6-87 | 7°07 | 6°15 6°84 | 6°63 | 6°41 | 5°40 | 4°62 | 5°45 | 4°82 | 4-09 | 4°16 | 5°31 | 5°89 | 7-45 | 6-38 | 6°95 | 5-79 5°56 | 6°14 | 5°62 | 5°20 | 4°29 | 4°61 | 4°50 | 4-15 | 3-80 | 4°94 | 5°50 | 6°86 | 5:82 | 6°45 | 5-28 5°06 | 5°82 | 4°90 | 4°60 | 3°67 | 3°82 | 4-25 | 4°01 | 3°36 | 4°16 | 4°30 | 6-27 | 5-04 | 5°98 | 4°64 4°65 | 5°02 | 3°83 | 4°13 | 3°46 | 3°17 | 3°84 | 3°75 | 3-19 | 3°70 | 3°59 | 5°37 | 4-47 | 5°18 | 4:07 A-AL | 4°02 | 3°29) 3°68 | 2°98 | 2-87 | 3-33 | 3°56 | 3°03 | 3°18 | 3:21.| 4°55 | 3-94 | 4°25. | 3-48 4°00 | 3°34 | 2°93 | 2°85 | 2°67 | 2°63 | 3:24 | 3°14 | 2°63 | 2°45 | 2°71 | 4°22 | 3-53 | 3°62 | 3°C0 See eenenl eZ 269) 2°62 ||) 21d (2-40) || 3-18) |) 2°82 | 2:07 |218 4) 2-53) 8283) || se17) || 81a 12-72 2°89 | 2°52 | 2°60 | 2°34 | 2°49 | 2-12 | 2°87 | 2°51 | 2°21 | 2°11 | 2°53 | 3°48 | 3:00 | 2°74 | 2°54 2°66 | 2°35 | 2°40 | 2°30 | 2°58 | 2-03 | 2-71 | 2°51 | 2°33 | 2°14 | 2:40 | 3°11 | 2-83 | 2°66 | 2-48 2-78 | 2-21 | 2°34 | 2°41 | 2°65 | 2-13 | 2°39, | 2-59 | 2°39 | 2°31 | 2°45 | 2°76 | 2°50 | 2°75 | 2°51 3°24 | 2°37 | 2°53 | 2°43 | 2°62 | 2-26 | 2-21 | 2°62 | 2°35 | 2°45 | 2°57 | 2°48 | 2-48 | 2°72 | 2°58 o4d | 2°42) 2-81 | 2°51 | 2°45 | 2-54 | 2-27 | 2°49 | 2-41 | 2-29 | 2-70 |2°46 | 2-47 | 2:94 | 2-62 3°90 | 2°45 | 2-89 | 2°64 | 2°27 | 2°56 | 2-41 | 2-36 | 2:09 | 2°17 | 2°91 | 2°51 | 2°47 | 8:08 | 2°65 aoz | 2°64 | 2-89 | 2°67 | 2:15 | 2-95 | 2-59 | 2-26 | 2-00 } 2:34 | 3-32 | 2°7 | 2-76 Qe 252 | Mr. C. Chambers. for each point being’ reckoned =1000,” which table contains in all 1,225 numbers. A second table is formed from this by taking the mean of twelve successive numbers and moving onward a step (2.e., by one number) after each operation : a third table is formed from the second by taking means of pairs of successive numbers: the third table contains 1,213 entries, or six less at the beginning and six less at the end than the first table: the numbers in the third table—called ‘“‘three-monthly values ’’—will be made use of further on, in the inquiry into planetary variations. Next all the numbers in the third table, except those opposite to the divisions (0) of the several months, being rejected, the means are taken of sets of three of the 304 remain- ing numbers, selected in the following manner, viz.:—the means of the lst, 4th, and 7th entries, of the 2nd, 5th, and 8th entries, and so on, the result being placed opposite the middle number of the three in each case. Finally, means are taken of pairs of the successive numbers thus found, the final means being called ‘ nine-monthly values,” and corresponding in time to the division (2) of the several months. These final means are shown in Table II, in which the entries are reduced to 297. Table II.—Declination-Range, Nine-monthly Values. Qi = ee eS ie bs @ as 5 2 LY Be = 2 Year. b = & & < & a 3 ¢ , a 2 =) =) van _ Se > nee Ss o 2Q =} ma (S | co) by a Oo o o q a m = re rs Ja s 3, 2 S S) 3 ® Ss 3 > (3) ° D 5 = < = 5 5 < wn fo) A a ISK, ceopaqcsonsopan aoe oe neh nod) Yi sabe and see nae O80 500 1153 | 1168 SA Sivecseecscees 1176 | 1170 } 1166 | 1160 | 1144 | 1130 | 1123 | 1122 | 1134 | 1160 | 1182 | 1181 ee) Se pdedcadnaadan 1171 | 1165 | 1161 | 1155 | 1141 | 1118 | 1089 | 1061 | 1052 | 1053 | 1041 | 1085 NSO OMe ac cccee se 1036 | 1043 | 1050 | 1047 | 1048 | 1038 | 1018 | 1017 | 1017 | 1003 981 963 IUSBY Gecpeqeanbeneds 1028 | 1081 | 1031 | 1034 | 1027 | 1015 | 1010 | 1010 | 1001 | 984) 9771 973 IESG} So asenoesdesco 974 | 995 | 1016 | 1020 | 1013 | 1008 | 1013 | 1019 | 1022 | 1015 | 997 ; 976 NODA eis senteetenees 957 | 945 | 938 | 927 | 910 | 892] 884] 883] 873] 862] 857} 860 SUSI) scqcbcaGsecade6 865 | 863} 859] 855} 857 866 | 876] 887 | 891 882 | 878 | 878 UES) 0) eeasoaseroaadec 869 | 853} 842] 836] 822] 806) 809] 817] 821] 824; 819} 815 LIST Rear eence enone 815 | 815} 819} 823 | 833 | 844] 863); 905] 935} 953] 983 | 1010 TSO Sie iecsnes neces 1025 | 1025 | 1036 | 1047 | 1041 | 1044 | 1043 | 1033 | 1039 | 1056 | 1083 | 1114 USS }8)) Seeeanbcccasiads 114] | 1153 | 1151 | 1169 ; 1193 | 1200 | 1207 | 1202 | 1179 | 1159 | 1159 | 1167 USGO) os cseeesesents 1161 | 1157 | 1172 | 1181 | 1187 | 1189 | 1175 | 1152 | 1134 | 1122 | 1109 | 1079 IiSKOI Ease aaacoeacac 1047 | 1028 | 1027 | 1045 ; 1062 | 1065 | 1060 | 1050 | 1048 | 1045 | 1039 | 1025 IRSKIPA seabepodocconb 1003 | 993 | 992 | 990; 988 | 984] 980; 977 | 976; 975} 965) 957 1tetTB) ponbaebasaseoss 959} 961 | 960) 953°) 937 | 926 | .928 | 927) 918h)" 911) 906 900 USO4 eee cwecsenant 908"). (9277) 9347) 9325 9383) | 9838) |) 927" 1929" |) S43 Osan OTe oc: LUSK opecepuonendce 918 | 914} 916} 910; 896 | 892} 898) 905} 914) 922 | 929) 926 US} Shoanencoaseeee 919 | 906} 872); 838; 821} 818} 821} 821 | 825) 829] 834; 850 USOT eeaese anes 864 | 867} 856} 833 | 812] 807} 819} 822}; 806) 797} 801} 818 PS OS Mei cae se ncnct 830 | 843} 842] 839 | 854] 874] 888] 892] 887 | 883] 891] 910 TESteR) easedradosnae 929 | 9491 977 | 998 } 1009 | 1014 } 1020 | 1033 | 1042 | 1047 | 1051 | 1054 ISU ese anpononaaca 1065 | 1094 | 1130 | 1163 | 1189 | 1219 | 1230 | 1216 | 1207 | 1204 | 1200 | 1191 HUSH pachobbestenoda 1181 | 1169 | 1152 | 1151 | 1162 | 1170 | 1164 | 1140 | 1134 | 1145 | 1148 | 1147 IRS (7Asseeianoctincdode 1146 | 1140 | 1135 | 1140 ; 1160 | 1166 | 1148 i USS) ae sasene nanee 956 | 957 | 959] 958; 958 | 957 | 957} 963] 978 | 1000 | 1006 } 1013 | The numbers in the table are curved (in a strong line) in fig. 1, and the comparable numbers obtained by Dr. Stewart* for Kew and * “ Proc. Roy. Soc.,” vol. 26, p. 109, and vol. 28, p. 84. Sun-spots and Terrestrial Phenomena. AD a: Trevandrum are curved onthe same form—the former in a weaker and the latter in an interrupted line. 4. On these curves we may remark that they present such a general correspondence of movement, and approach to simultaneity, that any conclusions as to the relations of the declination-range to solar activity that may be drawn in respect of one of them will apply generally in respect of the others also. The sun-spot period is distinctly followed by them all—three showing the maximum of 1859-60, and two the minima about 1856 and 1866-67. The general correspondence of the curves will perhaps be most readily apprehended by noting the most marked cases of departure from it : these are—(1) that the elevation, in the middle of 1859, in the Kew and Bombay curves, has no counterpart in that of Trevandrum, but only a slight inflection of a continued rise; (2) that the depression, at the beginning of 1861, at Trevandrum and Bombay, is all but absent at Kew; and (3) that the elevation, near the end of 1862, at Kew and Trevandrum, has no counterpart at Bombay. Features of the Trevandrum and Bombay curves that are perhaps worth noting are that the great rise from 1856 to 1860 begins earlier and ends later at Trevandrum than at Bombay, that it begins lower and ends higher, and that the turnings at beginning and end are sharper in the same case. C. Lunar Annual Variation. D. Semi-annual Lunar Variation. 5. The processes by which the lunar variations of declination-range ave been brought out were the same as were applied to the tempera- ture-ranges in paragraphs 7 to 13 of the preceding investigation ; but the observations made use of in the case of the declination-ranges are those for the twenty-five winters and twenty-five summers em- braced between 1847°75 and 1871°75. In this case a lunation was taken to be a winter one if the middle of it occurred between the Ist October and Ist April, and the remaining lunations were taken as summer ones; and—in correspondence with this—the elimination of the part of the winter or summer lunar variation due to the annual variation of the declination-range was effected by the same division of the year in respect of summer and winter. The following table shows the mean values of the declination-range for'each of the eight phases of each of the 309 lunations of the period, and the summer lunations are distinguished in it by having their serial numbers enclosed by parentheses. Q54 Mr. C. Chambers. Table I1J.—Hxhibiting the Declination-Ranges grouped according to Lunations. Run Lunation commencing ning LOM ON On| Oey Gy) @ oe 1 | October 8: ~1847......... 5489 | 4-126 | 3-542 | 3-617 | 4-937 | 4-029 | 3-005 | 2-850 DleNovember dl, 1uy ep hse 2°553 | 2-439 | 2-352 | 2-393 | 3-651 | 4-309 | 2-758 | 2-215 SuleDecembervs eee 2°587 | 2-774 | 3-285 | 7-905 | 7°108 | 2-747 | 2-719 | 3°331 4 | January 6, 1848......... 3-187 | 3-613 | 3°989 | 4-656 | 4-046 | 3°594 | 3-519 | 2-850 Be iimebruanys,, nae 3-011 | 2-630 | 2°621 | 3:441 | 4-544 | 4-744 | 2-576 | 2-702 6 | March 5, , seaeeeeee| 3°228 | 3°359 | 4°183 | 4-498 | 5-218 | 5-407 | 4-714 | 4-133 (7) | April 3, yy) ceseeeeee] 4171 | 47203 | 4-326 | 4-646 | 5-592 | 5-248 | 5-316 | 5-654 (8) | May 2, St (ke Ces 5482 | 5-706 | 5-774 | 5242 | 5-642 | 5-087 | 5-051 | 5-528 (9) | June 1, Siler ae OE 6°134 | 5-453 | 5-037 | 4-986 | 4-905 | 5-900 | 5-614 | 5-446 | (10) 5 0, jy evseesee| 67009 | 5°866 | 6-004 | 6-118 | 6-542 | 7-096 | 6-616 | 6-296 (11) | July 29, Ee SN 6°519 | 7°376 | 6:195 | 5-941 | 7-342 | 8-571 | 6-822 | 6-840 (12) | August 28, Rates 7°440 | 6908 | 7-171 | 6°772 | 7-079 | 7°307 | 5°758 | 5-454 13 | September 26, 5, ........ 6-022 | 5-687 | 5-242 | 4-409 | 4-057 | 4-945 | 3-989 | 3-257 ia Octoperi2Gu mas eee 3211 | 2-398 | 1-940 | 1-827 | 1-907 | 2-343 | 4-029 | 3-639 15 | November 25, ,, .........| 3°457 | 3-102 | 2-589 | 2-867 | 2-787 | 2-294 | 2-575 | 3-022 16 | December 25, .,, sss... 2-521 | 2-913 | 3-348 | 3-490 | 3-194 | 2-940 | 4-298 | 4-413 17. | January 23, 1849......... 4°304 | 4°052 | 3-732 | 3-619 | 3-422 | 3-104 | 2-953 | 3-890 18 || Rebruary22, oe. 4°628 | 4°512 | 3:966 | 3°639 | 3-570 | 3:245 | 3-663 | 4°578 (19) | March 24, REE ERAGE 4°985 | 5-488 | 6-296 | 6-908 | 6-370 | 5:402 | 5-053 | 5°150 (20) | April 22, ey eer 5-322 | 4:951 | 4-635 | 5-034 | 5-569 | 5-957 | 5:116 | 5-096 (21) | May 21, Baek 7°034 | 6°833 | 5°417 | 5°372 | 7-148 | 6-908 | 5-093 | 5°417 (22) | June 20, oy eeseeseee| 6°042 | 5°775 | 5°186 | 5-262 | 6-136 | 5-797 | 6-135 | 6-099 (23) | July 19, ee eer Te 6249 | 5-562 | 5-276 | 5-563 | 6-319 | 6-496 | 5°574 | 5-671 (24) | August 17, EUR Be: ' 5986 | 6-427 | 6-078 | 6°127 | 6-484 | 6-854 | 6-061 | 5-701 (25) | September 16, ,, ......... 5°564 | 6-256 | 6°307 | 5°329 | 5-150 | 4-368 | 3°411 | 3-474 268 |October To. fey meee 3°153 | 3-090 | 2-964 | 2-605 | 2-468 | 1-871 | 1-752 | 2-678 27 | November 14, 5)... 2°816 | 2-486 | 2°483 | 4°161 | 4-268 | 2°567 | 2-236 | 2-420 28 | December 14, 4, .......-- 2328 |-2-357 | 2-419 | 2-823 | 2-706 | 2-454 | 2-534 | 2-483 29 | January 13, 1850......... 3°284 | 3°598 | 3-559 | 3°757 | 3-519 | 3-282 | 5-699 | 4-921 B00 Hebruanys tla ain eee | 2-758 | 2-288 | 2-437 | 3°179 | 2-506 | 2-182 | 2-494 | 3-066 31 | March 13, tp 3°439 | 4-127 | 4-006 | 3°941 | 4-326 | 3-639 | 4-142 | 5151 (32) | April 12, SUT, 5°265 | 4-635 | 4-407 | 4°865 | 4-578 | 4°710 | 5-413 | 6-066 (33) | May 11, Sepak: | 6-994 | 6-547 | 5-013 | 5-162 | 5-746 | 5-851 | 5-894 | 5-449 (34) | June 9, i eh aR | 5-472 | 6-071 | 5°803 | 5-665 | 5°757 | 5-975 | 5-826 | 5°576 (35) | July 9, a 6°558 | 6-261 | 6-124 | 5°442 | 4-887 | 5-563 | 5-608 | 4°725 (36) | August 7, si see 4°888 | 5°501 | 5°442 | 4-715 | 5-574 | 5-940 | 6-089 | 6°427 (37) | September 5, ., ........ 6°839 | 6-964 | 6-249 | 6-593 | 6-249 | 6-032 | 5-230 | 4°732 | 38 | October 5, Laat a: 4892 | 3-948 | 3-410 | 2-964 | 2-952 | 3-117 | 2-906 | 2-663 39 | November 3, ,, ....-.00 2-413 | 1-944 | 2-018 | 2-328 | 2-231 | 1-648 | 2-059 | 2-458 limeconm| December) aun ues 2°437 | 2-025 | 2-174 | 2°857 | 2-770 | 2-643 | 3-392 | 3-605 41 | Januaryl, 1851......... 2-691 | 2°842 | 3-536 | 3-694 | 3-336 | 3-462 | 3-783 | 3°530 42 tse Vitae a enn ae tc 3-101 | 2-666 | 2-557 | 2°374 | 2-609 | 2-689 | 2-323 | 2-582 43 | March 2, eel 2-649 | 2°528 | 2-614 | 2-856 | 3-330 | 3-406 | 3-582 | 3-479 (44) | April 1, “ ...| 37902 | 3°694 | 4-057 | 4-429 | 4-910 | 4-429 | 3:560 | 3:937 (45) oy 80) Seen 4143 | 4-543 | 5-242 | 4-910 | 4-898 | 4:120 | 3-754 | 5207 (46) | May 30, se em 6-146 | 6-085 | 5-528 | 5-273 | 5-287 | 5-356 | 4-887 | 5°322 (47) | June 28, sy ee 7°348 | 7-406 | 5-860 | 5-493 | 5-298 | 5-986 | 4-395 | 5-082 (48) | July 28, eat TONER 5°654 | 5°173 | 4-234 | 3-765 | 4-875 | 5-310 | 4°475 | 5°122 (49) | August 26, Cast ola 6°376 | 6676 | 5-482 | 5-825 | 5-883 | 5°597 | 5-608 | 5-974 50 | September 24, ,, ........- 5°860 | 5°675 | 5-530 | 4-658 | 4-040 | 3-674 | 3-159 | 2-980 51 | October 24, 4, eveseeee 2928 | 3-185 | 2-759 | 1-751 | 2-226 | 2-661 | 2-255 | 2-530 52 | November 22, ,, 2°907 | 2°571 | 2-209 | 2-306 | 2-775 | 2-402 | 1-808 | 1-895 53 | December 22, ,, ......--. 2-224 | 3-158 | 2-849 | 2-470 | 2-676 | 2-334 | 3-009 | 4°024 54 | January 20, 1852......... 4-223 | 3-239 | 2-884 | 2-610 | 2-702 | 2-495 | 2-953 | 5-150 55 | February 19, ,, ........ 4°887 | 2-679 | 2-439 | 3-434 | 3-674 | 3-077 | 3-400 | 3°903 (56) | March 20, Sea ese 3°788 | 3°571 | 3°823 | 4-037 | 5-379 | 5-013 | 4-772 | 5°026 (57) | April 19, nA Age 5-373 | 6-242 | 6-243 | 5-788 | 5-561 | 5-533 | 4-383 | 4-664 (58) | May 18, rit, Aes on 5°837 | 6-215 | 5-601 | 5-379 | 5-299 | 5-459 | 4-818 | 5°63] (59) | June 17, Sb bela 6-415 | 5-700 | 5-139 | 5-288 | 5-357 | 5-343 | 4-876 | 4-452 (60) | July 16, Se new 5339 | 6°270 | 67123 | 5:054 | 4-854 | 4-904 | 5-711 | 6°375 (Glial Atuieistidion ) nena een 6°479 | 6°810 | 6°672 | 5°503 | 5-402 | 6123 | 5-551 | 57494 (62) | September 13, ,, ......... 5-444 | 5-063 | 3-731 | 3-777 | 4-017 | 3-828 | 3°576 | 3-955 G50 POctobers2 uu eae 2-666 | 2-993 | 3-799 | 3-319 | 2-998 | 2-460 | 2-300 | 2-211 64 | November ll, ,, ......... 2.°335 | 2-280 | 2-380 | 2-678 | 2-678 | 3-387 | 3°124 | 3°525 [65 December 10, 3-994 | 2-994 | 2-162 | 2-513 | 3-722 | 3-599 | 2-815 | 3-035 eGGHe| anuiciny Aon achat 2-723 | 2°431 | 2-656 | 2-816 | 3-360 | 3-249 | 2-633 | 2-761 GTM ncoruany 7) ee 2°278 | 2-164 |-2-610 | 2-484 | 2-188 | 2-383 | 2-657 | 2789 68 | March 9, ain en 3°365 | 2-815 | 2-907 | 3-873 | 4-137 | 3°262 | 3-445 | 4-884 (69) | April 8, oer ree 5°872 | 5°590 | 5-109 | 4°715 | 4-263 | 4-147 | 4-726 | 5°424 (70) | May 7, sie dene 4°727 | 3°857 | 4-441 | 5-699 | 5-928 | 5-310 | 4-840 | 5°184 (71) | June 6, pe Obie 5-299 | 6:037 | 6°357 | 6°191 | 5-917 | 5°755 | 5-894 | 5-895 (72) | July 5, Ae EO: 5°580 | 5°688 | 5-688 | 5-919 | 6-363 | 5-315 | 5-184 | 6-237 Sun-spots and Terrestrial Phenomena. Lunation commencing new moon. August 4, September 3, October 2, Piel al, November 30, December 29, January 28, February 26, March 28, April 26, May 26, June 25, July 24, August 28, September 21, October 21, November 19, December 19, Japbuary 17, February 16, March 17, April 16, May 15, June 14, July 13, August 12, September 10, October 10, November 9, December 8, January 7, February 5, » 3, August 29, September 28, October 28, November 27, December 26, January 25, February 24, March 25, April 23, May 23, June 21, July 20, August 19, September 17, October 17, November 16, December 15, January 14, February 13, March 15, April 13, May 12, June 11, July 10, August 8, September 7, October 6, November 5, December 4, January 3, February 2, August 27 September 26, ot Oo PP OOOUPWWWNNWOOHDOTROB ENN PWNAGE PENN NNNNWUPWWWERNNWNNWAKRKRKRONUONNNNNNUOTEP HEP RWNNWWNHNWaD (1) PWR PTAUDWWWNNWHTP ROR PHN NN AOIWERWENENWNENUPWWWRNNWNNWOP PEER ENNNNNEP UTP EOP ENDS PWNND OUUMUMNANIUTINWWNNWOAHATEPOOWNWNNNE EEE WEWNNNNHENUTNWWWANNNNNNUTPWEPERWNNNYNEP PERU RWWPENYNwWAd Bn Osa Ose at ROS Oa Cee eet hot at) eae! iD Oi AOOeGS Rat VeOOseaswSeeGeksAeSsSHhHsessee sae [op) — nN aS © rs NTIMAAWIATINWNNWUNAHANTITPWWNNHE POPP ROWE NNN NDP E BR ENNWNNNEOPOWOPNNNYNNWOATPOPNWWNNnnNnan DR SO Oy Se tty a oy ey ey Oe i eas ee ae a ae ier Oa ROO RC er Oo Oe Ore =~] fp) On lop) NSS xe) WIM TONE WWNNEARMAMDTPERWNNNHE RANT UONENNNENAUOPEWNHNWNNNMNWOPREP EPP ENNNNYNTIAOMAOPNWWNNNoana ©) EFNE EPP WWWNHNMDNENWOW EE RPWNNDNRE RENE EWE PENNNNNNOOD Fi Se GS Gos oo AeoeS ROS eseSASASGSROSCeSSSSSS to pa iw) 1 ~] bo ANAM A EWE WHWOTIOIAOTBROWNERNNWODP PP Oto DD SOS PASSO SSSSSSRES SRS HS 6SR9 ERG 4° (ee) — 478 iS }S rs iw) WONO PNM TINWWENUIHUINBEUIAWNHENNWHWEWORWNDNENN EPP BR PWWPRNHWENWOWWEPWWNNRPRE NYP EPWRORPWNNNPE NON 256 ; Mr. C. Chamb ers. 2°222 2°698 2°480 3 °318 4°103 6 °288 5°170 3 °899 o*1lll 4197 2°836 202 January 8, 1864......... 203 February 7, Sy heeescesons 204 March 7, Sk welactoancs (205) | April 6, Sgnurenicte ewes (206) | May 5, ane gece sae (207) | June 4, ia uaheceeanes (208) | July 3, sats, (seeks aces (209) | August 2, dy Mise weakest 2 4 4 6 rs) 3) +) oD 3 2 201 December10: ).4 3-28 peek 3 3 4 4 6 0) 4 Sy We asc ere 6 39 ? 22 211 September 30, ,, .........| 3 212 | October 30, Sengenseorce 2-470 MiSs NOVEM ET 2 85) mea a nes 1°669 | Run : P | = Lunation commencing | , iS nie Siete GaOGh | (0) (1) (2) (3) (4) (5) (6) 150 October 25, 1859 oeeeess 3°802 | 3°819 | 3°282 | 2°710 | 3:030 | 2-658 | 2-302 151 INovemben 245) 55) cs.c2. 5: 2°653 | 2°573 | 2°298 | 3-361 | 3°8538 | 5°284 | 4-289 152 WecembernZs,m asa aceese- nes 8°114 | 2°621 | 3°376 ' 3°28] | 2-744 | 3°076 | 3-454 153 January 22, | 1860.......- .| 8°213 | 8°1383 | 3°327 | 3°142 | 3-259 | 3°541 | 2°813 154 | February 21, ,, ......- 3°143 | 2-470 | 2-209 | 3-310 | 4-693 | 4-700 | 3-476 (155) | March 22, ape ee ee | 4-769 | 4-914 | 5-467 | 5-751 | 5-037 | 4-858 | 4-803 (156) | April 20, fiadcetal de | 57082 | 5-216 | 5-799 | 5-947 | 6-199 | 6-261 | 6-124 (157) | May 20, Sah ayeacesseee ' 5°846 | 4°859 | 5°635 | 6:035 | 6°610 | 6°450 | 5-684 (158) June 18, 99 d6dbe005e 1 6°370 | 7-274 | 7°525 | 8-289 | 8°657 | 7°045 | 5-167 (159) | July 18, Rann ed, | 6-256 | 6-908 | 5-867 | 6-560 | 7-095 | 8-242 | 9-320 (160) | August16, 7” .........| 8-440 | 8-166 | 8-097 | 7-918 | 9-057 | 8-462 | 7-399 (161) | September 14, ,, ......... | 5-410 | 5-833 | 6-713 | 6-805 | 6-427 | 6-461 | 4-620 soon October 14. 1 eres 4278 | 4-008 | 3:170 | 2-610 | 3°306 | 3-418 | 2-425 163 INO MTA ae US 55 SasSsocee | 2°005 | 2-018 | 2°196 | 2°375 | 2°498 | 2°197 } 2-071 164 iDecempberd2y, wwe 1 2°710 | 2-306 | 2°539 | 2°553 | 2°649 | 2°832 | 2-855 165 JanuaryalOs se! (6s cee 2°723 | 2°928 | 3°191 | 3-786 | 3°374 | 3°054 | 2-776 166 February 9, 5 ueeasesese 2°699 | 2-618 | 2°733 | 2:902 | 3-416 | 3°691 | 3-065 i t67 March 11, San caoea tenses 3°651 | 37923 | 3°705 | 4°186 | 5°404 | 5°404 | 5-730 (168) | April 9, nA asscoodat 4°677 | 4-318 | 3°792 | 4°584 | 5°329 | 5°352 | 4-963 (169) | May 9. Bh, Ned 4-483 | 4-426 | 4-643 | 5-078 | 6-299 | 6°385 | 5-665 (170) | June 8, A ERTE He | 5°158 | 5-855 | 6°106 | 5-523 | 6-186 | 6°026 | 5-032 (171) | July 7, aah: | 6°719 | 7-554 | 5°653 | 4°312 | 4:904 | 5°600 | 5-851 (172) | August 6, eee ak eee : 67939 | 6-964 | 6-585 | 5-341 | 7-436 | 8-228 | 7-509 (178). | September 4, ,, ......... | 7-520 | 6-683 | 5-895 | 6-690 | 7-041 | 67539 | 5-580 174 October 3, An GEOR on | 4-394 | 4-670 | 3-937 | 3-093 | 2-853 | 2°372 | 3-057 175 |November2, ,, ....-.-.- 1 2-758 | 3-030 | 2-825 | 2-276 | 2-481 | 2°154 | 2-161 176 December 1, a auhissee ce 2°684 | 3°331 | 2°984 | 3-064 | 3°190 | 3°373 | 2-154 U7 a Oo RE ene Gaacasaee 2°684 | 3-046 | 2°733 | 2°56] | 2°584 | 2°469 | 3-178 178 Januany,295) | 18625..---- 3°075 | 3°853 | 3°980 | 3:373 | 2°607 | 1°976 | 2-104 179 HebDiWanyacespe ceseccesee ee 2°909 | 2-662 | 2°264 | 2°374 | 3°361 | 38°727 } 4-093 (180) | March 29, sannessisaeees 5°225 | 4°994 | 4°607 | 5-483 | 5-995 | 4 "966 | 47198 : (181) | April 28, FORE A 4-665 | 4-814 | 4-151 | 4:007 | 4-038 | 4°887 | 4-981 | (182) | May 28, el conten 5°812 | 5-637 | 5°465 | 5°499 | 5-293 | 4°857 | 5-077 (183) | June 26, ih ee 6-254 | 6-329 | 4:985 | 4-857 | 4-709 | 4°786 | 4-447 (184) July 26, aa brpeeneae cae 6°471 | 6°071 | 4°745 | 4°870 | 5°955 | 67151 | 5°511 (185) | August 24, ES a 6-574 | 5-891 | 5°594 | 5-584 | 6-661 | 6-089 | 5-396 186 NEpLEembersZ oe see eee 5°d11 | 4°762 | 3°544 | 5°639 | 5°589 | 3°485 | 2-948 187 October 22, Shi tsesoeee ve 3°814 | 2-710 | 2-492 | 2-206 | 2-378 | 2-206 || 2-332 188 | November21, ,, ......--. 2°355 | 2-218 | 2-321 | 2-790 | 2-447 | 2°149 | 2-367 189 WecembernZ0w sees ce 2°732 | 2°893 | 3°241 | 2-621 | 2-543 | 2°806 |} 3-190 190M) |danuany 190 TS63e.e-22-e 2°916 | 2°868 | 3°022 | 3-110 | 2°584 | 2°579 | 2-481 i 191 Bebruany ds, o, pee ee 209 | 2-538 | 3°010 | 2-819 | 2°640 | 2°250 | 2-367 | (192) | March 19, ee geete ties °013 | 4°253 | 3°704 | 3-480 | 2°986 | 3°032 | 3-853 (193) | April 17, BHP sapceneos | “977 | 5-156 | 5°065 | 3-921 | 4°665 | 5°397 | 5°705 (194) | May 17, Sn es "167 | 6-082 | 5°774 | 5-118 | 5-374 | 5-737 | 4-643 (195) | June 15, esas a "396 | 5-145 | 4°482 | 4-706 | 4-985 | 5°529 | 6-059 (196) | July 15, te hie a: ‘282 | 5-877 | 4-882 | 4-692 | 5-510 | 5-133 | 4-836 (197) | August 14, ee ee "453 | 5-365 | 4°390 | 4-116 | 5-488 | 5-872 | 5-424 (198) | September 12, |, ........ “511 | 5-044 | 3-727 | 3-853 | 4-413 | 4-150 | 3-796 TON JhOveeeee | 3-253 | 2-387 | 2-630 | 2-758 | 2-424 | 2-344 | 2-629 200 November 10; (5.04.0. | Po Craresy || COT | 7 “481 | 2-648 | 2°790 | 2°895 | 2-973 2-515 | 2- 2° 2° 3° 3° 4: 3° 3° 4° 5° D° 4° 4s O° (A 6 6 ef 2° 3: Ih . 2 . 3° 3° 3° PAS ike ae 239 3° 4- 4: 4° 4° 4° 4° O° D° 4° 5° Dia 4° Tae 3% 2 . 2 . RPE NOR ROR PN EWN NNN D OOOH HW DD bo ony He “ 072 | 2°538 | 2°100 2°275 222 035 195 | 3°110 | 3°236 | 2°755 214 Wecemper cout sae 2°182 759 471 | 3°178 | 3°807 | 3-461 215 January 26, 1865......... | 2 °866 312 358 915 | 2°058 | 2°832 | 3-392 216 | February 25, ,, ....-..-. 1-838 | 1-880 | 1-989 | 2-675 | 3-430 | 3-279 | 3-830 (217) | March 26, yy weescssee] 27858 | 2-881 | 2-893 | 3-647 | 4-196 | 4-418 | 4-413 (218) | April 25, SR Eee | 5°740 | 4-528 | 4-047 | 4-836 | 4-745 | 4-569 | 4-825 (219) | May 24 Sipe ene j 4°913 | 4-885 | 4°061 | 4-253 | 4-893 | 4-950 | 4-665 (220) | June 22, SSP ities 5042 | 5-385 | 4-493 | 4-791 | 4-642 | 4-002 | 3-602 221) | July 22, GaN lp teh. 4-002 | 4°253 | 5-419 | 5-968 | 5°442 | 5°351 | 4-447 (222) | August 20, (280) +196 +234 | — 38 262 Mr. C. Chambers. Table V.—Period of Mercury about the Sun (0° denotes Perihelion). 104 periods. |First 52 periods.) Last 52 one Between O° and 30°...... —1133 — 64 — 1069 4 BO gsc wOOl area — 538 +193 = 73 PSO. GOO ee a) SeeammeT +155 — 192 | ‘i 907s aL 2Oene + 142 — 230 + 372 | eal 20at = ThOP ieee + 843 —167 + OO mea ber | DO sh COM mame + 953 —117 +1070 =| EON go..) toto Me) Tlie Saris —176 + 688 | i Pe DUOra, 9.240 yea teres + 375 oe Ty ee | Le NA) Ae O VO tees = 22 +179 — 201 Be 70") BOOMs ee — 484, +175 — 659 SU MBOOM EE. M880" RES: — 389 + 63 — 455 ob MBO ire pBOGO uae ven — 828 +138 — 966 Table VI.—Period of Conjunction of Mercury and Jupiter (0° denotes Conjunction). 102 periods. |First 51 periods.|Last 51 periods. Between O°’ and 30°...... — 84 + 50 | — 84 it S0InS ¥ CO ras —130 — 223 + 93 u GO a5.) tOOnk wee py —602 +378 i O00 2) W20n ee — 395 — 628 +2338 | Rb U0 TO. Nee +285 +163 +122 | AN. IB OUBLAN TM SOn Rin has —350 +132 — 482 Fe ASO Nee onl eee —651 70 —661 | | O10 240 ete = ye +158 = pik OU Mic eens +401 +818 + 88 Ae O70) be heS OLA en +690 +291 +399 #800! a0alea0 bemete +415 +389 4 OG J. |-830)h) 860 meneen ye | +136 — 79 The numbers in the several columns of Tables IV, V, and VI are graphically represented by figs. 11 to 19 in order. 10. The most marked feature in the Venus and Mercury period i 1S a treble wave which repeats itself consistently in both halves of the series of observation, and has one of its maximum values at the time of conjunction. The variation given by the solar period of Mercury is nearly all due to the last 52 periods: it is represented by a single wave, which is similar to the corresponding Kew curve when inverted. The curves of the first 51 and last 51 periods of the conjunction of Mercury and Jupiter are very unlike each other, and they are also unlike the corresponding curves for Kew and Trevandrum. The several curves in weak and interrupted lines for Kew and Trevandrum repectively are made for comparison with those for Bombay, which are drawn strong. In the planetary results 1t must 3 ~~ ~ S ~ al Co S S ~~ ib) re Ss 8 a) q ~~ % > S So nD | and -spots Sun Hs WAIHI HL Pe BRAGABLOREREGERR Wo Cees VOL. XXXIV. 264 Sun-spots and Terrestrial Phenomena. ieee Ws Re Ps a SSS, 2s 5 a ea eee ee ee San ed Game) es eae eee ERS GME SSeS PS de a ee ee es ee Sie Bos ee 2 Ee i a es De a ee Se ae ee ee ee be observed that the variations are for different numbers of periods at the different stations as follows :— Bombay. Kew. | Trevandrum. | | : | | Mercury and Venus.........| 62 39 | Mercury. ite ees S) ) o rb) Se dee el ede leet ee a ee eel S| ° O° ° fo} fo} ie} 1°) ie} (o} ° Oo ° ie ° ae | 1844 | 1845 |+ 1-1]+ 1°6/+ 1°8/+ 10/4 3°5|+ 2-0/+ 3-8]+ 2°8/+ 2°9/+ 2-2/4 1-:1)— 0°5/+ 23°3| 41-9] 1846 |— 1:4]/— 0:2|+ 3°1)+ 32/4 3:°7/+ 4°8/— 0-9/4 3°7|/+ 2°6/+ 20/4 2-6/4 0-8/4 24°0 42-0 1847 |+ 0°8/+ 2°2}4+ 0'4)/+ 0°6)/+ 1°3/+ 5°4/4+ 2°3/4+ 3:°4)/4+ 1°3!+ 0°2/4 0°5/+ 0:2/+ 18°6| 41-6 | 1848 |— 0°3/— 1:3|+ ro|+ 2°6/+ 5-6/4 2°9|+ 31/4 2:9/4+ a5]+ 1:7/— os|— 0-214 20:0) 41-7 1849 |— 0-7|+ 0-2/+ 2°0|+ 16/+ 2°3/+ 5°5/+ 3°9]— 0°8}/+ 0°8|— 14/4 1:°5|/— 0°8]+ 14:1 ae 1850 |— 1:6/— 3°0]— 0°6/— 0°3/+ 0-4)+ 21/4 12/4 2:3)+ 1:2]+ 09/4 0-2/— 1:8]+ ro] +01; 1851 /= 7-3 O6)/— L1l)+ 4154 2°3/4+ 2°5/4+ 3°:0/+ 2°6/+ 2°8]/+ 2:°0/+ 3:0/+ 1°3/4+ 20°6] +1°7 1852 |— 2:0|+ 0:3 O3/+ 15 /+ 2°5/+ 1°5]4+ 11)+ 2°5|/+ 3°4|/— 16/— 0°8/— 1:8\+ 6°3 oe 1853 [+ 2:3/+ 30/+ 21/+ 19/+ 2:5)+ 24/4 20/+ 2:0/+ 2°0]+ 0°8/+ g0]+ 4:3/+ 28-3] +2°4| 1854 O-2]+ O-6|— O-L/+ 1:9)+ 2-5/4 11]+ 2°9/+ 0°5|/+ 3°4]/+ 3:°0/4 4:4/— 0:8/+ 19:2] +1°6 1855 |+ 7°8|+ 5°6/+ 3°0/+ 2°0/+ 1:6]+ O°8]4+ 2°7|/+ 2°9/+ 3°0/+ 4:3/+ 2:2}4+ 2-0/4 37-9] +3-2 1856 + 2-0/— O-7/+ 2°5/+ 3°8/4+ 2-2/4 2-9/4 13/4 3-1/+ L'l]+ 2°6/+ 4:1]/+ 0°8}/+ 25°47 a 1857 1858 + 14/+ 3°3|— 2°5|/+ 16/+ 11)+ 2-2/4 18]+ 17/4 03/+ 47)+ 2°3}+ 16/4 200] +17 | 1859 FeLO)— VOl4 UT U2) + OLl+ 21/4 Bie Bal Be 86) Aa tel eel aes 1860 |+ 1-4|— O-1/+ 0°6/+ 1°2/+ 1°3}+ 2-0/4 1:9]+ 1°6/+ 3°3/+ O°7/4+ 4:5/+ 2:1)+ 205] +17} 1861 |— 0°5|— 1:°0/— 0:1)/+ 3°5|— 0°5|}4+ 2-2/4 2:1/+ 0°9/+ 1:7/+ 2°9}4+ 3°0/4+ 05/4 14°7 +12) 1862 |+ 1:8]+ 2°2)+ L1)+ 0°9)+ 0-9)+ 1-9/+ 1:0/+ 3-0/4 I-1]+ 2°4/+ 2°8)/— 0-1]+ 190] +16] 1863 0°5|/+ 05/4 O°9)+ 2°0|+ 1:4)/+ 2-7/4 44]+4+ 2°3/4+ 61]+ 2°6/+ 2°6/+ 1°8]+4+ 26°83] +2°2i 1864 |+ 2°6/+ O-8/+ 1-4/+ 2°4/+ 4:1)/+ 15/4 0°2}/4+ 3°7/+ 2°7]+ 13/4 1:0/+ P7|+ 2374 +2-0| 1865 |+ 1°4)/+ 11/4 2:2|— 0-7|+ 3:-4/+ 3-7/4 1-9]/+ 1°8/+ 0°9/+ 2°7|— 1-8/4 0-7/4 17-3] 41-4 | 1866 |4 0°3| oo|— 0:7/-+ 0°5|+ 0°5|+ 0-2/4 2°6/+ 0-8/+ 0-3/+ 3-0/4 1°8|/4+ 18/4 arr] +0°9 | 1867 |— 2°0|— 0°2)— 0-7}— 1:0)+ 0O-1]+ 1:8)+ 2°9/— 0°6|+ 1°3}— 0°3/4+ 2°3)/— 11]4+ 2°75 a, 1868 |— 1:2/— 1-7/4 0°5|— O-1/+ 0-9} .0-0/— 1:0|— 0-2;+ 0-9/+ 21/4 0-8/— 11/— or) 0-0) 1869 |— 1-1|+ 0°5]+ 1-2|— 1°6/+ 0°8]+ 0-2|— 1:2/+ 0-7|— 3:1]+ 2-2/4 22/— 0-9/— or} 0-0! 1870 | 1871 |+ 2°0/— 2°3)— 0°2)— 0-4/4 1-4/+ 1:0/+ 0°5|/— 0-9/4 2°8/+ 2°0)+ 4:8/— 15/4 9:2] +0°8 | 1872 |— 1:°6|— 1°5|+ 1-9/4 0:2/+ 2°6/+ 0-8/4 2°0/+ 2:3/+ 2:5/+ 2-1/4 9:3/— 1:2]+ 104] +0-9| 1873 |+ 0°4/+ 1°3)— 0°8}+ 1:0/+ 1°8}4+ 0°3/)4+ 0°9}+ 1:9/+ 15/4 5°8/+ 0-2/4 2°3/+ 16°6 +1-4 | 1874 |— 0°5/+ 1:1]— O°7/— 0°3}+ 1°6)4 3°2)/4 1-1[+ 1°5)4+ 1:4]+ 2°0/+ 40/4 3°8/+ 18-2] +15! 1875 |— 1°5]/+ 2°8]/+ G5/4+ 1:3/+ 15]+ 2°4)/4 2-7/4 2:1/+ 2°5]4+ 25/4 3:1]/— 1:0|/+ 18-9] +16 1876 + 21)— 0:3/+ O6)+ L9l+ LO}+ 14) + O-8/+ 2°0;+ 2:1]/+ 3°2/4 1:-4]/— 0°7/+ 16-4 ae 1877 |+ 0°9/+ O-8]+ L:1/+ 8°0}+ 11/4 0°8)+ 2°8}+ 2°2/4+ 4:5/+ 3°0/+ 1:9]+ 0°4/+ 22°5] 419; 1878 |+ 1°8/— 0-9/+ 3°4}/— 1:1]+ 3°4]4+ 1°3)+ 3°0/+ 1°8)/+ 2°6]/+ 4:1/+ 2°7/+ 3°0|/+ 2571 +21 | 1879 |+ 3:0] O-°O]+ O°7/+ 3°2/+ 2°4/+ 16/4 0°5/+ 1:7)4+ 1:°4/+ 4:2/4 3°0]/+ ro|+ 22°7 +1-9 | EOE TN at A io ae Sums. |+17°7|+12°5|+25°9|+42°6|+62°2|+67°2) +5974 |+60°6 | +67°4|+73°5 |+68°6/+18'4|+576°0 | Means| +0°5 | +0°4| +0°8| +1°3| +1°9| +2°0) +1°8 +18 420 +2°2} 4271] +406] ... 415! During the years 1844, 1857, and 1870 the observations of Thames temperature were incomplete, the results for those years have in consequence been altogether omitted. The monthly values in different jigures are estimations, inserted in order to complete the numbers for the particular years in which they eceur for the prrpose of taking meane. 1882.] Temperatures of the Water of the Thames, Sc. 283 Table [V.—Monthly Mean of the Diurnal Range of the Temperature of the Water of the Thames at Greenwich. : p Ses Ta ° ° mer ° 1844 1845 0°38 0°4 1:0 1:0 1846 22 ak J9 2 1847 1°6 15 0°6 0-7 MeronemsOn}) 1-5 |) 15 | a1 ee ommecG eG |) 15) | > 3:7 1850 Pare 3°] 3°3 3°3 1851 3°6 37 3°53 3°5 1852 2°3 dl 2°0 2°0 1853 0°6 0-9 24 1°8 Hepa 4160 | 1:8 |" 2°77 | 34 easel ica) |) 2:0) || 2:5 1856 HF 1:9 1:2 3°0 1857 1858 0-7 0°8 1:0 3°2 1859 0-0 0°3 075 0°8 i600" 1:8 1 1°81 12 1861 1:0 1:0 1:0 1:0 1862 3°0 23 2°8 Die, 1863 ef 2-5 2°95 7PM 1864 3°2 32 a2 31 1865 1°6 1O7/ 1:0 1:0 1866 272 2°70 10 1:2 1867 2°4 2°4 2°8 2°6 1868 1°6 1°3 16 1°8 1869 i7/ 1°8 15 2°3 1870 AS7Aleeso 3:5) 3:1 | 38 1872 Die, 2°0 Be 2°8 1873 Zell 2°0 2°4 atl 1874 2°3 2°4 ZAI | 371 Laie ooo 2:0} 19 | 22 1876 ies 1°8 1°8 ZarUf 1877 2°4 1:9 2°3 ane 1878 2°3 7 2°3 2°6 1879 1°8 23 2°3 27 Sums | 63°7 | 64°4 | 64°8 | 75°3 Means} 1°9 20 2°0 | 2°3 During the years 1844, 1857, and 1870 the observations were incomplete, the results for those years 79°5 Month. a Sees ge Sy eB We cena (eso eal mealenllr acon ial 0°8 0°3 0°4 1°3 1°3 Uo? 36 41 1°6 0-9 1-0 HP} 2°3 ae, pera 4:0 3°5 34 3°83 20 ae 2°6 PHA 3°3 alta) 22200 (ease 3°4 371 3°2 374 2°9 21 3°6 2°8 2°6 2:2 3°0 2°8 19 19 13 1:0 1°0 1:0 1:0 1°0 170 Dae, al 252 22 ie 22 1°9 2:0 HE@) 10 0°5 0°3 1-2 0-9 0°8 1°8 2°0 1:9 1°4 0°5 13 a) aie, 1°6 371 3°5 30 2°38 2:9 25 2°5 al 19 1°8 1°8 19 1°8 HE? 16 2°8 2°5 2°5 2°5 Pal 19 2°3 2°5 2°5 31 26 | 2°8 74°2 | 6971 | 65°0 ines Zeek 2-0 2°4 September. ° 2°6 21 63°2 19 6571 Seas aed Stele es Soa |enaa | a A n Hom hee ornihi tot | iol Zp 92 ite, 26 | 23°8 0-7 Tell 18°4 2°5 34 | 192 31 325) ||| 23070 3°5 3°4 | 4078 PAH PUL MI) Yep Ih TES eZ Ore I°5 1-3 | 21°5 2°0 Gy |! Bie 3°2 ZU | Bure 1s) ||° 18) |) Asia 0°2 070 | 20°5 0-1 0:0 10°9 1-C 10 14°2, 59 3°9 23) 2°3 3:0 | 28°8 2°2 Pe) | Paypal 1°3 1:3) | 2770 1°8 U3 |) 3 ae, ron |e Lia ae 2-0) |) Z0r2 16 18 17°0 14 20 | 21°7 3°3 27 | 3974 ZAG 2 Ae 202 3°0 2°3 | 284 TO 21s 2539 1°8 18 | 23°5 2°4 2°71 | 28:0 2°0 2:1 | 25°8 2°3 2°5 | 28°9 25 | 25 | 308 69°5 | 68°7 | 822°5 2a all 2:0 21 have, in consequence, been altogether omitted. The monthly values in different figures are esti- mations, inserted in order tocomplete the numbers for the particular years in which they occur, for the purpose of taking means. 284 Temperatures of the Water of the Thames, &c. | Nov. 23, Table V.mMonthly Mean of the Diurnal Range of Atmospheric Temperature at the Royal Observatory, Greenwich. Year. 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 Sums Means Month. ~ a . : : : 7 F E : 2 : Sums. : 3 ES S = o oS = = 8 S © o a SPS Ey Si GEE ee a SN es Ss g 5 fe = < ==) 5 = < 0) fo) Z iS = “oO ° a rh are hens PN rT Ge). 6 | a UZ 9-4) 15-1} 15°8) 138°9] 18:0} 141) i145) 16°9] 13°6} 10°7} 10°0} r59°2| 13°38 7:0 78} 12°38}: 13:2] 1970} 23:3) 20°8) 16°75] 19°0 9°6 U3 63] 16271) 13°5 FG LOsd |. THO Loss. Ose) AAA eo) iG osGq, 1250) a0 6°8} 167°1| 13°9 8-1) 10°9| 15:0) 19°3] 27:0} 18°2} 20°6| 1771} 2071) 141) 18°4 9:9} 19377) 1671 I16} 14:5] 13:2 16°9| 15:4] 20°6] 24:5] 19°7/ 16-6] 15:4] 12:5 9:2} 1g0°r| 15°8 8:8] 11:4) 16:2) 17°3) 18°9} 23°2}- 19:5} 18°9) 17:0} 14:0] 11°4 85) 185°1| 15:4 10:3 13:4) 12:31) AG6:7)) 20:3) 21e6}) W759) 19-8) 920;2 Ass es 81} 185°0] 15°4 11-7} 18°31 16°38} 23°6) 18°9 18°4' 25°5| 18°6) 16°5) 14°6 9:7 9:2| 19673} 16°4 8:7; 10°6| 16°3| 1471) 20°0| 19°70} 16:1; 18:1} 18°6} 14:7] 12°4 8-9} 17775] 14°8 T2255) W925 | 22:4) > 201) TSO} OG. Z2z8i) Zo3 | NA 21 O22) ear RO S| 10:01) 1425) 26 eal 2058) AO So 9 s8i ars 9°3 9°38] 18270) 15:2 8:6| 10-0] 18°8) 18°5| 16:6] 20°8; 20°8} 18°9] 15:9} 138°9} 12°3 9-1) 1792) 14:9 WISE ATES iy ASEG| > LO leo V25e 222512228 eS Saloon ellen 852) 207-6) ies 10:5) Y5:7) TST Vie7|) 19:6) 210) 244) 21) WO)” 1359) 1853) eL0s0 | 168:8) Ee lGr6 978i, V4! 1359) V9) 19:9) 1625) 19:0} W576)" V8r2)) 4) 0r6 79!) 198-7) 14 9| TAEO} = WLM MGs aS 22:0 a OaT le SO) eeZs 1975] 15°8} 13:2} 10°5| 198°3] 16°5 9:4} 10-1] 11:7] 16°8| 18°5) 18:1] 20°5}. 19:1] 17°0] 14-4) 11-1 9°5| 176°2| 14:7 TO25 | L381 V9:0) 2078)" 29)" US 2523) 1925) EO WS ON eS a0 so) pa oo sal mtars 9-9) Te P58) 16s, VO5 i 208i) 625261) s28c5)|h ieS) | 4s?) 2 9:2] 195°6| 16°3 S363) LOs6 1) A227) 2459) 2078) 24 eS) 5 1925) 23: Ole GES) eles OA Z05 931 (elim 11:2) 12-5) 14:0] 18:5) 21:0) 21:2) 19°8} 17:0} 18:1) 138°5 2-2) IL-3] 185-3) 15:4 VO) V0} 12:7) TEs6| 20:2) 20:7) W9:9)) 2023) List L522 ASO: 0) Perso ret lor GEO TBI TG) TURES PT BASH | 27st Palo) eran MWA gpa 9°7} 210°8| 17°6 LOD 223) 126i LOO eile 20 rTee2oe2 en 20g eel elon a mente 8:7] 186°7} 15°6 8-0; 13:2) 17-2) 17°8| 22:2} 18:1] 19°6; 25°4) 16°8/ 15:5} 10:9 8°3} 193°0| lol ORS PA USS AOE ener aI Ite ei) ADP TAs IS) aye al 9°6 8:4] 195°0} 16°2 8°6 8°7| 16°6| 19:7) 19:7; 19°0| 23:5} 19°6) 19°4) 16:1) 0-8] 10-7} 1924) 16-0 TRAN IBIS ae PANES BILE) AG) POZE) PAC INS) astay|| 1 7/ 779} 204°1] 17:0 9°4 9:2) 3:9) 20:4) 2227 20:0) A728) 92020)| Soi L297 97 8:9} 183°2}] 15°3 V3) LOs6\) F425)" Ob) 227 2s a 24-9) | 23 4 GS) eel C i al Ok 77) 195°4| 16°3 ei 2 ASO W522) lcOleZovol Ocoee Os) taal Oe sii Oxo melo 96} I91°9} 16°0 9°7 O56) A4ST Lio Gol 20245 | Osa elie) el GeO) lame acd 9-1 8:9} 175°7] 146 6°2 Sri P49 WEF SZ 2 eG sO) pall os Oe 2s Ciel OG: 9:9} 162°7| 13°6 31671 | 379°1| 495°6| 610°5 | 655°3| 674°9] 698°6| 647°6) 596°2] 471°8| 371°5 | 301°3 | 6218°5 9:6), DIGS 15:0) 18:5) | 19-9 20rd 2le2 19-6 18:1) 14°38; 11°3) 91 ees 15°7 The results for the years 1844, 1857, and 1870, have been omitted, in order to render the table entirely comparative with that giving ranges of Thames temperature. 1882. | R. Shida. Magnetic Susceptibility. 285 Il. “ Experimental Determinations of Magnetic Susceptibility and of Maximum Magnetisation in Absolute Measure.” By R. Supa, Thomson Experimental Scholar, University Glasgow. Communicated by Sir Wiliam Thomson, F.R.S. Received October 10, 1882. (Abstract. ) This paper contains the results of a series of experimental de- terminations of the magnetisation, magnetic susceptibility, &c., of different specimens of iron and steel, in centimetre gramme second units, by means of the direct magnetometric method shown to me by Sir Wiliam Thomson, as founded upon a method originated by Coulomb ‘and mathematically discussed by Green. A number of thin wires (from No. 20 to 22 B.W.G.) of soft iron and steel were tried in the first elaborate series of investigations. The experiments were varied by varying the strength of the mag- netising force through a wide range; and for each magnetising force, and for each wire, the experiment was commenced by subjecting the wire to the application and removal of a longitudinal stress a certain number of times in succession (that is, ‘‘ons and offs”’), while the magnetisation and magnetic susceptibility of the wire were deter- mined for each degree of magnetising force, and both while the wire was actually under the influence of a constant pull (a case to be denoted by ‘‘on”), and while it was free from a pull (a case to be denoted by “off”). In the case of soft iron wires, the effects of suddenly reversing the magnetising force, and of ‘“‘ ons and offs” after , the reversal of the force, were also investigated. Some interesting and remarkable results followed from these experiments; and the evaluations, made from these results, of the intensity of magnetisa- tion and magnetic susceptibility, are carefully tabulated, and also represented graphically, for the sake of comparison, in two sets of curves—one, which shows the intensity of magnetisation, that is to say, in which the abscissee are proportional to the magnetising force and the ordinates to the intensity of magnetisation; and the other, which shows the magnetic susceptibility, that 1s to say, in which the abscissz and ordinates are respectively proportional to the force and. the susceptibility. The curves of the intensity of magnetisation show that the effects of “ons and offs,” in augmenting the magnetisation of soft iron wires, are astonishingly great for low magnetising forces, and that, as the latter is gradually increased, the wires seem to lose their reten- tiveness gradually, so much so, in point of fact, that when the magnetising force exceeds a certain value (60 c.g.s. or so) the operation of ‘ons and offs” produces no permanent magnetisa- 286 R. Shida. Determinations [Nov. 23, tional effect ; whereas, for a magnetising force below that value, the simple reversal of that force is not so effective as to annul the per- manent effects of ‘‘ons and offs,” or even to reverse the magnetic polarities of the wires. But anequally,if not more, remarkable result is found in the fact that the intensity of magnetisation of soft iron wires is greater or less while it is pulled than while it is unpulled, according as the magnetising force is below or above a certain critical value—a result which confirms that given in Sir William Thomson’s paper on the “ Electrodynamic Qualities of Metals,” Part VII. It is quite evident, however, that this critical value is different, not only for different kinds of soft iron wire, but for different amounts of the pull to which the wire is subjected. The singularity of the existence of a critical point in a soft iron wire is only intensified by the fact that, whilst the permanent magnetisational effects of “ons and offs” on a wire of soft iron and of steel (pianoforte wire at least) are similar in kind, there is found no such thing as a critical point in the latter, in which the magnetisation is greater in the case of “‘ off” than in the case of ‘“‘on”’ for every degree of magnetising force. For high magnetising forces the curves of the intensity of mag- netisation all become asymptotes parallel to the line of abscisse,. proving that there is a hmit to the magnetisability of iron and steel, wus was first shown by Joule. In the case of “off,” the maximum intensity of magnetisation is found to be approximately 1420, both in the soft iron wires and in the steel pianoforte wire, and in the cases of ‘on,’ it is more or less below that value, the minimum magnetising force corresponding to that magnetisation being in each case roughly 80 units; while in the glass-hard-tempered steel wire, to which no weight was applied at all, the maximum magnetisation is found to be slightly lower. The steepness of the commencement of the curves of magnetic sus- ceptibility in the case of the soft iron wires is striking, owing to retentiveness; indeed, the magnetic susceptibility of these wires varies through a vast range. Taking, for example, the case of the soft iron wire of No. 22 B.W.G., in which the weight used for “ons and offs” is 8 kilos., the susceptibility for the magnetising force (about °545) of the earth’s vertical component; is roughly 730 for “on” (8 kilos.) and 330 for “ off,” it is about 65 at the critical point (about 15), while it is only about 17 and 174 in the cases of ‘‘on” and ‘ off” respectively for the minimum magnetising force (about 80) corresponding to the maximum magnetisation. On the other hand, the susceptibility-curves for the steel wires are neither so steep nor so regular as those for the iron wires, but have a few maxima and minima; it is, however, all but certain that by using a heavier weight than the one actually used for ‘‘ons and offs,’ these irregularities in the curves can be got rid of, and at the same time, the magnetic sus- 1882.] of Magnetic Susceptibility. 287 ceptibility of the steel wires for low magnetising forces can be greatly increased. Further details regarding these interesting points are difficult to describe in a few words, but can readily be understood on reference to the paper itself. The results of the experiments performed upon the magnetisation of somewhat thick bars (from °9 to °95 square centim. in section) of malleable iron, hard-tempered steel, and cast-iron, are also recorded fully in this paper. The intensity of magnetisation of each bar for various magnetising forces under different circumstances, is shown by means of curves, of which the “ direct-curves ”’ represent the results. obtained by beginning with a low magnetising force, which was gradually increased to such a high degree of strength as to magnetise the bar to saturation ; while the ‘“‘ return-curves’”’ represent the results arrived at by coming down from a large magnetising force te smaller and smaller forces, passing through the zero, and gradually going up to a large magnetising force on the negative side of the zero. The direct-curves prove that the intensity of magnetisation of the steel bar is slightly greater, at least for high magnetising forces, than that of the cast-iron bar, but is vastly smaller than that of the malle- able iron bar for all magnetising forces. The maximum intensity of magnetisation of the soft iron, steel, and cast-iron bar, is found to be approximately 1,330, 860 and 770 respectively ; while the smallest magnetising force giving that magnetisation is roughly 190, 400, and 400 respectively. ‘The difference in the intensity of magnetisa- tion of these bars is, no doubt, due to the fact that the soft iron bar is far superior in respect to magnetisability to both the hard-tempered steel bar and the cast-iron bar; although the difference that exists between the soft iron bar and the wires in the intensity of magnetisa- tion for all magnetising forces is probably due mainly to the effects. of the dimensions of the bar, as has been mathematically demonstrated by Green. But the chief point of interest hes in the return-curves ; they show that in the case of each bar the magnetisation does not reverse until the magnetising force exceeds a certain negative value, and that this value is considerable even in the case of the softiron bar, considerably greater in the case of the cast-iron bar, and still greater: —enormously greater—in the case of the steel bar. An illustration of the beauty of this magnetometric method by means of curves showing the change in the distribution of magnetism in a wire corresponding to the change in the magnetising force to which it is subjected, draws the paper to a close. The curves. decidedly show that the magnetisation of the wire for a low magne- tising force is far from being solenoidal, being stronger towards the centre, but that as the magnetising force is made higher and higher the distribution of magnetism in the wire tends more and more to uniformity, until it attains nearly, if indeed not quite, a solenoidal state 288 Prof. A. R. Forsyth. [Nov. 23, when the magnetising force is so high as to give the wire the maxi- mum magnetisation ; thus confirming beyond all doubt what has been pointed out theoretically by Thomson (“‘ Hlectrostatics and Magne- tism,” § 667) and indicated experimentally by Rowland. III. “On Abel’s Theorem and Abelian Functions.” By A. R. ForsytTu, B.A., Fellow of Trinity College, Cambridge, Pro- fessor of Mathematics in University College, Liverpool. Communicated by Professor CAYLEY, F.R.S. Received October 28, 1882. (Abstract. ) The present paper is divided into two sections. The object of Section I is to obtain an expression for an integral more general than, but intimately connected with, that occurring in Abel’s theorem. The latter, as enunciated by Mr. Rowe in his memoir in the Phil. Trans., 1881, is as follows :—If x(@, y)=9 be a rational algebraical equation between « and y, then an expression -can always be found for where (a) is a function of z only, U isa rational algebraical integral function of « and y, and the upper limits of the series of integrals are the roots of the eliminant with regard to y of x(a, y)=0 and a fune- ‘tion O(a, 7). In the case here considered two equations of the degrees m and nm respectively between three variables Fra, Y; z) =0 eae iO) -are given (these alone being treated, as subsequent generalization to the case of + equations between r—1 dependent variables and one independent is obvious) ; and an expression is obtained for S | Udz Bin, Bn p@a(aB) the upper lhmits of the integrals pee given by the roots of the -equation arrived at by the elimination of « and y between Fy, Fy, .and an arbitrary equation dae) =O) 1882. | On Abel’s Theorem PpApe lend Hunctione. 289 or, what is the same thing, by the co-ordinates # of the points of intersection of the three surfaces represented by Fin, Fn, Hp. Some preliminary considerations (An connexion with §§ 92 sqq. of Salmon’s Higher Algebra) are adduced in reference to the eliminants of the three equations in each of the variables; thus if X be the equa- tion in w obtained by eliminating z and y, it is expressed in the form x Bilin se BaF, ar BoE), which afterwards proves useful. Then the ordinary case (above referred to) of Abel’s theorem is treated on the lines laid down in Clebsch and Gordan’s treatise on the Abelian functions; and under the guidance of this the more general form is investigated with the result Udez aremiols =>. lop Lio, © being the symbol introduced by Boole. The remainder of the section is occupied with the discussion of two examples of this theorem. In Example I, by the assumption of suit- able forms for F’,, F,, Fy, it is proved that 8k°A BC E(u) +E H(u,) — EK w ( v (tg) ts ( 3) (uy oF Ug + U3) = Gen 26 C2)? + Ad; Ade2 A2C2 where H is the second elliptic integral and A, B, C are given by As, + Be, +Cd,=1, As,+ Be,+Cd,=1, As,+ Be,+ Cd,=1, and s, c, d stand for sn u, cn u, dn u respectively. The corresponding expression for the third elliptic integral is stated. In Example IT an expression is obtained for H@y ua =). -Eu,). In Section II the addition theorem for the functions presented in Weierstrass’s memoir in Crelle, t. lii (1856), p. 285, is investigated. It may be pointed out that the fundamental equations in the theory occur as natural examples of the more general form of Abel’s theorem proved in Section I; but the equations so obtained are identical with those used by Miceli and this case, therefore, does not belong distinctively to the form of Abel’s theorem connected with the curve of double curvature. On this account the simpler form is used on the two occasions (in §§ 14, 19) when required. The theory is worked out at considerable length, and the necessary 290 On Abel’s Theorem and Abelian Functions. [Nov. 23, formuls are obtained in a manner somewhat different from that of Weierstrass. The fundamental equations being p—P(2)=y?—(@—a) (way)... (va) =0, 2 — Q(x) =2?— (@— ap 41) (@—Gpyg) » - (Uap) =0, 0O=My-+ Nz where M=ae+M,eet+ .... +M,.%-+Mbp, BSS) eis oo, AEE the equation giving the roots z is M?y? —N?2?=0. The Sp roots are denoted by a), 2, - . - 5 %as &, fs = > 15 Gace p; and there are obviously p relations between them. Writing R(z)=P@)Q(); ai — P@)dz NCS ANNO im bole and = A=1 and v,w corresponding functions of £, p, it is shown that Un + Up + w=. Writing, with Weierstrass, p(x) = (@—%) (@—a) .. . . (@— ap), —Q(a,) =, G25 eee le (Gn tery (G1 2h 5 oo 5 ase ll). then 2p+1 of the functions of the theory are given by l,al,*=(a;) for values 1,2,....,2p+l ofr. Then if Wears ‘ Bae A=1 | aA Vv R(a) it is proved that piu’ » Chl PG) ae If V, W are respectively the same functions of the é’s and p’s as U is of the z’s, then the theorem U+V+ W'S) t—aln(u)aln(r)aln(u+0) is obtained in § 21, a verification being furnished by expansion in 1882.] On the Recent and Coming Total Solar Eclipses. 291 terms of the w’s and v’s. From this equation is deduced the addition- theorem for the functions. In §§ 25 and 26 is given the discussion of a particular case of the above, viz., that in which the functions are of the order 2, the fifteen functions being the quotients of all but one of the double theta- functions by that one. The addition-theorem in these functions has already formed the subject of a paper by Cayley in Creile, t. Ixxxviii (1878), p. 74. IV. “Note on the Recent and Coming Total Solar Eclipses.” By J. NorMAN LocKYER, F.R.S. Received November 17, 1882. The following note has been drawn up in anticipation of the detailed accounts of the work done by me in Egypt on the eclipsed sun of 1882, May 17, which I am preparing to lay before the Royal Society, because as the next total eclipse occurs next May, there is no time to be lost if any attempt is to be made to secure observations, and I am of opinion that such observations are most important. I have prefaced the statement of the work done by a reference to the considerations which led me to undertake it, and I have added a scheme of observations which, in the present state of our knowledge is, | think, most likely to produce results of value. 1. In order to understand the recent change of front in solar research which has followed the introduction of the view of the possible disso- ciation of elementary bodies at solar temperatures, and suggested the later laboratory, and especially the later eclipse’ observations with which we are now chiefly concerned, we must first consider what facts we may expect on the two hypotheses. In this way we can see which hypothesis fits the facts best, and whether there are any inquiries possible during eclipses of a nature to throw light on the question. 2. On the old hypothesis the construction of the solar atmosphere was imaged as follows :— (1.) We have terrestrial elements in the sun’s atmosphere. (2.) They thin out in the order of vapour density, all being repre- sented in the lower strata, since the solar atmosphere at the lower levels is incompetent to dissociate them. (3.) In the lower strata we have especially those of higher atomic weight, all together forming a so-called “reversing layer” by which chiefly the Fraunhofer spectrum is produced. 3. The new hypothesis necessitates a radical change in the above views. According to it the three main statements made in para- graph 2 require to be changed as follows :— 292 Mr. J. N. Lockyer. [Nov. 23, . (1.) If the terrestrial elements exist at all in the sun’s atmosphere they are in process of ultimate formation in the cooler parts of it. (2.) The sun’s atmosphere is not composed of strata which thin out, all substances being represented at the bottom; but of true strata like the skins of an onion, each different in composition from the one either above or below. Thus, taking the sun in a state of quiescence and dealing only with a section, we shall have (as shown in fig. 1) C say containing neither D nor B, and B containing neither A nor C. Fre. 1. : pe x iy) LF OO Ly Yj (3.) In the lower strata we have not elementary substances of high atomic weight, but those constituents of all the elementary bodies which can resist the greater heat of these regions. 4, The conditions under which we observe the phenomena of the sun’s atmosphere have not, as a rule, been sufficiently borne in mind, and it is quite possible that the notion of the strata thinning out has, to a certain extent, been based more upon the actual phenomena than upon reasoning upon the phenomena. 5. Take three concentric envelopes of the sun’s atmosphere, A, B, C (fig. 2), so that C extends to the base of A, and B also to the base of A, that is, in both cases to the photosphere. Then, whether we deal with the sphere or with a section of it, the lengths of the lines in the spectrum of the strata C, B, A will give the heights to which the strata extend from the sun, and show where B and A respectively thin out. As the material is by hypothesis continuous down to the 1882.] On the Recent and Coming Total Solar Eclipses. 293 Hie. 2. sun, the lines will be continuous down to the spectrum of the sun seen below as shown. 6. Now take three concentric envelopes, A, B, C (fig. 3), so that only A rests on the photosphere, B rests on A, and C on B. The Fie@. 3. \ Da ae SN eh Se een aa. Att. Pe < Ae \ ©\ phenomena wiil in the main be the same as in the former case, 7.e., the line C will still appear to rest on the spectrum of the photosphere, for it will be fed, so to speak, from C’ and C”, though absent along the Ime CBA at Band A. So also with B. 7. Thus much having been premised with regard to the observations as conditioned by the fact that we are observing a sphere, we can now proceed to note how the two hypotheses deal with the facts. Old Hypothesis. New Hypothesis. 1. The spectrum of each ele- The spectra should not resemble ment as seen in our laboratories each other. should be exactly represented in the solar spectrum. 294 Mr. J. N. Lockyer. [Nov. 23, Fact.—There is a very wide difference between the spectra. 2. Motion in the iron vapour, €.g., i a Spot or a prominence, should be indicated by the con- tortion of all the iron lines equally. Motion should be unequally indicated, because the lines are due to divers constituents which exist in different strata according as they can resist the higher tem- peratures of the interior regions. Fact.—The indications show both rest and motion. 3. The spectrum of iron in a prominence should be the same as the spectrum of iron in a sun- spot. The spectrum of iron in a pro- minence should be vastly different from the spectrum of iron in a sun-spot, because a spot is cooler than a prominence. } Fact.—The spectra are as dissimilar as those of any two elements. 4, The spectra of spots and pro- minences should not vary with the sun-spot period. The spectrashould vary, because the sun is hotter at maximum. Faot.—They do vary. 5. The spectrum of the base of the solar atmosphere should most resemble the ordinary Fraunhofer spectrum. The spectrum of the base should least resemble the Fraunhofer spec- trum, because at the base we only get those molecules which can resist the highest temperatures. Fact.—-As a rule the lines seen at the base are either faint Fraunhofer lines, or are entirely absent from the ordinary spectrum of the sun. 6. Quad the same element the lines widest in spots should always be the same. (ud the same element the lines widest in spots should vary enor- mously, because the absorbing material is hkely to originate in and to be carried to different depths. Facr.—There is immense variation. 7. The spectra of prominences should consist of lines familiar to us in our laboratories, because solar and terrestrial elements are the same. The spectra of prominences should be in most cases unfamiliar, because prominences represent out- pourings from a body hot enough to prevent the coming together of the atoms of which our chemical elements are composed. 1882.] On the Recent and Coming Total Solar Eclipses. 295 Fact.—When we leave H, Mg, Ca, and Na, most of the lines are either of unknown origin or are feeble lines in the spectra of known elements. 8. From the above sketch, hasty though it be, it is I think easy to gather that the new view includes the facts much better than the old one, and in truth demands phenomena, and simply and sufficiently explains them, which were stumbling blocks and paradoxes on the old one. This being so, then, it is permissible to consider it further. 9. Let us first suppose, to take the simplest case, that the sun when cold will be a solid mass of one pure element, 7.c., that the evo- lution brought about by reduction of temperatures shall be along one line only. Let us take iron as the final product. Then the sun’s atmosphere on the new theory qua this one element may be represented as follows :— Fia. 4. Strata of Lncandescent Almosplere ee ee ee i Assume strata A—L. Then— (1.) The Fraunhofer spectrum will integrate for us the absorption of all strata from A to L. (2.) The darkest lines of the Fraunhofer spectrum will be those absorbed nearest the outside of the atmosphere. (3.) We shall rarely, if ever, see the darkest lines affected in spots and prominences. VOL. XXXIV. x 296 Mr. J. N. Lockyer. [Nov. 23, (4.) The germs of iron are distributed among the various strata according to their heat-resisting properties, the most complex at L, the least complex at A. (5.) Whatever process of evolution be imagined, as the temperature runs down from A to L, whether A, 2A, 4A; or A+B, 2[2(A+B)], or X+Y+4Z, the formed material or final product is the work of the successive associations rendered possible by the gradually lowering temperature of the successive strata, and can therefore only exist at L. 10. Now at this point a very important consideration comes in. It was stated (in 6) while discussing the conditions of observation, that whether we were dealing with strata of substances extending down to the sun or limited to certain heights, the spectral lines would always appear to rest on the solar spectrum, and that the phenomena would in the main be the same. : 11. This, however, is true in the main only, there must be a difference, and this supplies us with a test between the rival hypotheses of the greatest stringency. The stratum B, being further removed from the photosphere than the stratum Dd bob veer Oder ereeceeseeerocce toes Ceccrcccccce rrr} sorinuuy *quag aed e AAG AT Pp & | § 334 ‘pung foyay oiquoroy ne ee C88 “SpUngy psn4y Trust Funds. 1882.] O 4 OLF O 4 OLF 0G ceo evans tue snnonersossavacuanesensoree vocebssres G0BH00000500500000 aouneg “ De eC a eee eres ZS8T SDE eG & ray Z ce SDOCRASOOROOSCASOOaG ZSSI “jeyIdso pL sulfpunoy 0} quoude gq kg (0) Zz GE POOR TOTOOOOEE HEHE SEE H OS OHEHO EOE EEEEEES CHEE eeeseserOsesesers [S81 dOUBlC OT; De Si op (DS Gs "sfosuog, 006 TF “pung woybursquryy 0 OL eZ CO Oe rece rece eerecesesnrorevevecs Are49.1009 USTIOL0 7 0} quourkeg kg | 0 OL eZ eececcces Cote oe rccccvcrecescereceneeeceesetecnresns vane ZS8L ‘spuepratq OL, ps F Ds F "0048 aMyuUsqoq “yuoy red F Kemprey purlpryT O0OF ‘gsanbag yoay oY, Gr OF LSI. 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SF DoS la “S[OSMOD “SEL CEECF “pung profunayr [Nov. 30, Trust Funds. 336 6 GL 699 6 GI 6S9F GO Zope bee ee cones senbvecsvereesesserssesenecy Soe eerernssssccvone ooweled 66 one eee scevecececssssocecsce Heeseeveeeceees eeveseces spuopliA(y 6c 9 PL 967 Odo oer error eenrcoesevoeseveues "999 TULULOD MOY, 04 syuow An Ag 6 a) LST Cece eeea ener ee ewrens OOo tne see ee eset eecasersbasasees SH eeeeeersreresens aour/eq OL, D'S ¥ pas ee ‘s[OsMOZ “quen 10d ¢ 006% ‘spuog uolyesiaty welpery QOO‘OLE: “JSNAT, JOISSDD AT, O SG TAF OF Gee SANa: 0 6L 8kI eeneee eee eeeeeecsvecenes Seen eeveeaerceneeeseeeensesepeaees ee eeesenees aouvleq 66 Zz 9 Ze eee eee ee eee eeee ner tecs ones eseee sess eeserete sess eeesesseneeeseeeees . spueput(] (13 0 9 Pa aan: eee teneeee peevecers Coe eeeeeeeprospess pereereres eee Iepe plop kg OL SI SEL Pere receecececccececsssescrecees Seer enrerersreetaesresererresseseoes seoee eourleq OL ‘Pp oy + ‘Pp “Ss F "yo0}g Avmyrey “quop toed ¢ pooqueien4y svipvyy, O9OF "pung jopayy hang 9 LI SF 9 LAL SF 6 SI Zz Dorcccvcccccvcccvecccecs ““sueroisky jo eYsie) BKeY@) OQ 943 kq a1q2 6 SL Z en ceveresres Coe eeevesrreeeriecceeceessessereccconcrencce leereeesceceses . SOULTV “ -fed °‘ TEL Maecieaa 3 998}8q jo quoyy jo BOs ou() 6c 6 812 G0000000000 OoD00000 90060 0060000000 900000000 aisrerelereceele\ers ‘ QInqoory WeIL00aD kg CA ig PROBE ICE BOE EAT IIE ALCO AEIEE EEO fof | ‘Qousleg OL, 7 aS oop (PS os “puny athpaT upwmoosg Trust Funds. 307 1882. | G LI S6VF | Gg LI ove G LI S6Z Peco ce oecocrscevercceer sesso ceeorsceseeae poccccescrerccescessesered ° souRleg (13 ‘ (6) (6) G6L cece ccc scccce ccc occcs cer ccccccerecesesesaseserscscesesassseserenee ° (Z88T) I 61 PPP ee Seas aes age id co veereccccseee 20 soreres 000 eoreveveccoes spuoprAl(y qunoo0 Vv [eteue £yer0g pesory 0} pottofsuRty kg P SI SF RDORDOAARODODOI00 eccccccccess ose secscecsacscoersovsscersecee (1881) eouRleq OL Fe | [DS =F. ‘peqtury ‘Auedmo0g puvy yLomgIy M O47 Ul soreyg porpunyy OMT, -gomnqueqaq ‘yueg dod F Avmprey Utoyso yy YON puv UopuoT OOO'LE ‘quag ted $¢ sjosuog uvqjodoepy OSS TF ‘puny UorInpay aT @ GL Tel “ yunoooy yer0ueH fyo1w0g jesoy 0} PoLloFsUVry eS YO SG; : "yooyg “queg tod ¢ MON “POT “SPL G8LSF "PUNT 19POL UL 9 I LLI cece ces iovcesccervrescserers se cece pung uoryeno(gy 04 porrogsueay Ag 9 it baat socccceerceeseoescesce eee crevcececs . eesevorecsrosce dc cerevecve oe 2881 ‘gspuopral(y p 8a 5 ps & : ps ‘poonpey, “6 “SL, LOS ‘pung ha,punyyT 338 Appropriation of the Government Grant. [ Nov. 30, Account of the appropriation of the sum of £4,000 (the Govern- ment Grant) annually voted by Parliament to the Royal Society, to be employed in aidmg the Advancement of Science (continued from Vol. XXXIII, p. 76.) 1882. A. Macfarlane, for a Quantitative Research on the Con- ditions of Discharge of Electricity of high Potential...... H. 8. Hele Shaw, for the construction of an Improved Anemometer; three diagrams and photograph........... B. Stewart, for the expense of an Assistant in inves- tigating the Inequalities of Sun-spots, and their Terrestrial WMC CES fue oie Fhe ies ns opie Wels ee Wea ele ne eho e eee eee J. N. Lockyer, for Spectroscopic Researches in connex- zon with the Spectrum of mthewSun. 0. eee eee ee Thos. and Andrew Gray, for continuation of Experi- ments on the Specific Resistance and Specific Inductive Capacity of different) kinds of Glass. 2): tee ee J. Kerr, for continuation of Experiments in Electro- and Mapneto-Optiesiinic....c28 ily. Ca elcbantee ic eae eee eae Prof. W. N. Hartley, for continuation of Researches on Wiltra- Violet. Spectrar. i. os Pe. cli. «ec eee eee H. Tomlinson, for Investigations on the Influence of Stress and Strain on the Action of Physical Forces...... T. Stevenson, for the Reduction and Discussion of Meteo- rological Observations made from June to October, 1881, at Fort William and on the top of Ben Nevis........... Kk. Neison, for continuation of Computations in the Lunar Vheory 2 3.14 66g. Bia Gace. Ge Relies ae ek eee Prof. G. D. Liveing, for defraying the cost of Apparatus and Material used by him in Spectroscopic Researches... . C. Michie Smith, for Spectroscope and Apparatus suitable for observing and photographing the Spectrum of the Zodiacal Tight .):)..cien.5 Gee ee eee eee C. Michie Smith, for an Hlectrometer for observing Atmospheric Hlectrietty .:.)... 24 22k © laces eee A. Mallock, for continuing his experiments on the ruling of large Difiraction-cratings ©2206. s7en ee eee G. F. Rodwell, for the construction of an Apparatus for determining with accuracy the Coefficients of Expansion Carried storwardene. le one £1,045 0 0 80 100 50 50 50 200 50 20 120 — 1882. ] Appropriation of the Government Grant. Brouedattoravandere ws. 260s « aul, and Contraction of Bodies at temperatures far exceeding lO Oloaaittinad Ah mM omer Danae bBo e rhe caer cary nasi smh a G. R. Vine, for fmdhon Investigation of the Morpho- logical Structures of the Organisms found in the Wen- "OCIS SSINGIGSISST oe pane ah Re) be Aero Cre re mare Dr. C. Callaway, for eontinimation of ieyestipatiend of the Relation between the newer Gneissic Series of the Highlands and the Fossiliferous Ardovician Group ...... Rev. O. P. Cambridge, for Investigation, under high Microscopic Power, of the Palpi, Palpal Organs, and other Genital Parts and Processes, external and internal, of mporaersrand other Arachnida...) ....0c5.ei-cecoresosedeve io lotets lalla of) Prof. W. C. Williamson, for extension of the Resee rele into the Fossil Plants of the Coal-Measures to a Sys- tematic Study of the Microscopic Aspects of the chief Coals from all the Coal-Fields of the World............. H.:C. Rye, in aid of the Publication Fund of the Zoo- me ociealulvecOGd Association. aks 2).lPi.0 Ch. teks ele leh late! ee Dr. R. Braithwaite, for aid in Pulpit a Work ¢ on the Praise MMOS Sa EOLA joo, 21-05 0.01.) «) ovniabelateit iors. ofatatt: ails, wll oataldterst ele G. E. Dobson, for coniindation of his Allnetietent Manos graph on the Anatomical Structure, Systematic Position, and‘ Geographical Distribution of the Species of the Order | OROCIEIT ORAS © 0 Oe ae aoe ARP Se ge oe W. Topley (in inatalmenta), fon the Preparation and Publication of a Geological Map of Europe, and the adjacent parts of Asia and Africa, under the authority of the international Geological Congress. ...........2.200. Dr. J. Hamilton, for continuation of Researenes on Topographical Anatomy of the Brain ................... Dr. Ferrier, for the purchase of Monkeys and other Animals to be used in an Experimental Investigation of some points in the Physiology of the Brain and Spinal res BD os 8 ao el oi elo octets Seat iinion «sal ale 9 e/a Slave os a Chas. Roy, for the construction of Apparatus for photographing the Movements of a Lippmann’s Galvano- LEWEE « 9 oo 05.6 BID GRIDER DIO Gio CRIS Canis PSC eam Pian ra Apa Prof. J. Struthers, for the expense of Investigations into the Anatomy of the Greenland Right Whale............ Rey. A. EH. Eaton, to defray further the cost of printing and publishing a descriptive Monograph of the Ephe- UGG 23g ae oe O.o'd io bing Ins es dorocine nis Dorie, eee 309 045 0 0 88 10 9g 25 0 @ 510 0 0 25 0 0 00 0 @ 150 0 0 50 0 0 100 0 0O 150 0 0 7s 03.0 50 0 0 30 0 0 25 0 0 100 0 O Carried forward............ £2,018 10 0 340 Appropriation of the Government Grant. [Nov. 30, Brought 'torywarde i... +r £2,018 10 i#. A. Letts, fra Materials and Assistance required in Experiments on the Organic Compounds of Phosphorus eed Slo lanai te Ley isla echt KPO RS EB, ae 4.0 L. T. Thorne, for Investigation of the Character and Mode of Formation of an Anhydrous. Substance obtained by the Distillation of Hthylacetopropionic Acid.......... 30 H. B. Dixon, for aid in a Research on the Phenomena of the Combustion of Gases in closed Vessels............ 150 Prof. J. S. Humpidge, for the expense of Materials and Apparatus to be employed in the extraction of metallic Glucinum in the compact form, and for Investigations of the Metal, if obtained. Bes ton Reno iren )() C. Schorlemmer, for dontinuation of restanclios into (l) Aurin; (2) the Normal Paraffins; (8) Suberone ......... 100 Erode Tilden and Shenstone, for assistance in continuing a research into. the Constitution of Solutions and the Phenomena of Supersaturation and Superfusion........ 50 ' Dr. B. Brauner, to defray the cost of a Platinum Tube and other Platinum Apparatus for Investigation of the Anhydrous Fluorides by a new Method.................. 30 Prof. M. F. Heddle, for continuation of a Research con- nected with the Scientific Mineralogy and Geognosy of Scotland—£100 for analyses, £100 personal............. 100 Spencer U. Pickering, for continuation of a. Research imto Molecular.Conbimations: 275.0)... ee re cee 50 W. Saville Kent, for a renewal of former grant to aid him in a further heaaae of the Protozoa and allied (Syeegeh (ahs (0 ee ee ee eer eas Gath 5 \n)a)o/01o\4. 0 o0 100 C. Lapworth, for assistance in Studying the detailed Geology of the Lower Paleozoic Rocks of Britain, and describing the Graptolites they contain ................ 150 Prof. W. K. Parker, for assistance in his Researches into the Morpbology of the Vertebrata, more especially of 0 the Skull.c. cee rece e aw ete cane ced dn ee dice «orem 300.0 0 £3,168 10 0 1882.] Account of Grants from the Donation Fund. 341 Dr. Cr. Lai) Suva: Se) Smee To Balance on hand, Nov. 30, By Appropriations, as MSE es soo g 5,0 Sie vetstoehsic) Styl AEG OS above.....<...... 3,168, 10 © To Balance of Administrative Printing, Postage, Ad- EIRPENSCB asec sce eeselssseecie ©) 200) Ld vertising, and other Interest on Deposit............ 22 7 0 Administrative Hx- Moiety of Treasury Grant...... 2,000 0 0 PENSES! esis seas 09-10). 9 Balance on hand, Nov. SOMLSSZin sui, lee | ZOO NLS. 7, £3,488 14 4 £3,488 14 4 Dec. 1, 1882. GEE ai ie wey To Balance, and Moiety receiva- ble from the Treasury...... £2,260 13 7 Account of Grants from the Donation Fund in 1881-82. Silvanus P. Thompson, for the cost of Experiments in the con- struction of Polarising Prisms of large aperture (of angle)... £12 D. Mackintosh, for a Systematic Series of Observations in North Wales on the Positions of Boulders, relatively to the Forms of the Natural Surfaces on which they rest, with a view to throw light on the approximate date of the final disappearance Omelacionsiand Mloating Lee... 6... ee ee ne ee cite os 7 Dr. A. Downes, to study further the Influence of Inght on low forms of Life, with especial reference to (1) the Behaviour of such Organisms in various Media; (2) the question of their Destruction, or reduction to astate of dormant Vitality, by Light 10 Profs. Reinold and Riicker, for continuation, with improved Apparatus, of Researches on the Electrical Properties of Thin PA MAA UPR De fet cS) fs 8 5c dS ahs slat ais ee Sie 4k eo ae dusts § olerel 8 ofises 30 J. N. Langley, for Observations on the Changes which take place in the Cells of the Liver during Secretion ; and Observa- tions on the Liver, and on the Gastric Glands of Birds during MORTEM MEM yon fel eva ats, A's Gis sje sists wr as STA AUS sah 8S we, * 4 39 H. D. Archibald, for experimental Researches into the Physics of the Atmosphere and its Meteorology by means of Kites...... 20 Carricdctonwande vis) 5 64 £109 342 Account of Grants from the Donation Fund. [Nov. 30, Brought storwant ee as oe £109 R. Etheridge, Jun., and P. H. Carpenter, for aid in the further preparation of their Monograph of the Blastoidea, es- pecially of British species, with their Morphology ............ 30 Dr. De Burgh Birch, for a bs aa Research into the Grrowbh Ol vBone j,i. 2:2 5s se hom Gels Meee eh eee ee 10 A. M. Worthington, for Apparatus for measuring Photographs of Pendent Drops, and for investigating the fluence of Hlec- trical @haree on Surtace! Pension 2.0 ..04. 2. ete eee 20 W. T. Dyer, for aid in preparation of an Illustrated Mono- graph of Cycadza...... Spagieke Lpotabetoar ae ie leo dae Sa eam 20 £189 1882.] Report of the Kew Committee. 343 Report of the Kew Commuttee for the Year ending October 31, 1882. The operations of the Kew Observatory, in the Old Deer Park, Richmond, Surrey, are controlled by the Kew Committee, which is constituted as follows: General Sir H. Sabine, K.C.B., Chairman. Mr. De La Rue, Vice-Chairman. | Vice-Adm. Sir G. H. Richards, Capt. W. de W. Abney, R.E. C.B. Prof. W. G. Adams. The Harl of Rosse. Capt. Sir F. Evans, K.C.B. Mr. R. H. Scott. Prof. G. C. Foster. Lieut.-General W. J. Smythe. Mr. F. Galton. Lieut.-Gen. R. Strachey, C.S.1. Mr. H. Walker. The work at the Observatory may be considered under seven heads :— Ist. Magnetic observations. 2nd. Meteorological observations. ord. Solar observations. 4th. Experimental, in connexion with any of the above depart- ments. Stk. Verification of instruments. 6th. Aid to other Observatories. 7th. Miscellaneous and financial. I. MacGnetic OBSERVATIONS. The Magnetographs have been in constant operation throughout the year. In March a new suspension pulley was fitted to the Bifilar magnet in order to reduce the distance between the suspension wires from 6°8 millims. to 5°5 millims., and thus to increase the sensibility of the instrument. This change was recommended by Professor W. G. Adams, in order to make the scale-value about -0005 millim. mgrm. for 1 millim., as suggested in his Report to the British Association last year. Dr. Wild, of St. Petersburgh, also recommends that all observatories should adopt as far as possible the same uniform scale VOL. XXXIV. 2A d44 Report of the Kew Committee. for their instruments, and suggests that the scale-values should be as follows :— For the Declination 1 mm. 6D=1’. Bialar 1 mm. 6H=0:0005 mm. mer. units. » Balance 1 mm. 6V=0:0005 iS us The following are the values of the ordinates of the various photo- graphic curves as determined at the various dates stated :— Declination 1 inch=0° 22’04. 1 mm.=0° 0”87. Bifilar Jan. 3, 1882, for 1 inch 6H=0:0450 foot grain units. » fmm. , =0'0008 mm, mer, anise > Mar. 27, ,, Linch’, =0;0222 toot oramimices » Lmm. ,, =0:0004 mm, mers umes Balance Jan. 6, ,, ,, Linch 6V=0-0341 foot grain units. 5 Lmm.. ,, =0:0006 mm. mer. ‘units: The Committee having been asked by the Secretaries of the eee national Polar Commission to furnish that body with copies of their hourly determinations of the magnetic elements, recommenced the tabulation of the curves which had been suspended in 1879. (See Report for 1880, p. 4.) With a view, however, of reducing the labour of tabulation, it was decided that a sufficient degree of accuracy and greater rapidity would be obtained by reading the curves by the unassisted eye, without the aid of the tabulating frame and vernier hitherto employed. Scales eraduated on glass plates have therefore been prepared, and the curves tabulated from August Ist up to the present date by this means; the declination being recorded to a tenth of a minute of arc, and the force-traces to the tenth of a millimetre. In order to obtain a record of the more rapid changes which take place during magnetic storms, a trial has been in progress since July 4 of the highly sensitive argentic gelatino-bromide photographic paper prepared by Messrs. Morgan and Kidd. The results of the experiment show that the paper indicates clearly small movements of the magnet which the waxed paper is unable to register, and also that less gas-light is needed for the purpose of illu- mination. Three magnetic storms, or periods of considerable disturbance of the needles, have been registered during the year; viz., on April 17th and 20th and on October 2nd. All were accompanied by auroral displays, but these were only observed in this country on the last date. The Committee have to acknowledge with thanks the receipt of photographic copies of traces during those magnetic disturbances from the Observatories at the Mauritius, Melbourne, Toronto, = Batavia. Report of the Kew Committee. 345 The monthly observations with the absolute instruments have been made regularly, and the results are given in the tables forming Appendix I of this Report. The magnetic instruments have been studied, and a knowledge of their manipulation obtained by— M. Puiseux. Captain Dawson, R.A., and 3 of his assistants. Dr. Ristori. Mr. Dallas. Information on matters relating to terrestrial magnetism and various data have been supplied to Professor W. G. Adams, J. H. H. Gordon, Dr. Stewart, Messrs. Tate, Zambra, Professor McLeod, The Hydro- graphic Department of the Admiralty, the Director-General of the Chart Depot of the French Marine, Lieutenant Chadwick, the Naval ‘Attaché from the United States, and others. The following is a summary of the number of magnetic observations made during the year :— Determinations of Horizontal Intensity........ 33 Me Dior ate yor siece hones Bene 138 i Absolute Declination........ 28 At the request of the Polar Committee of the Royal Society a number of old magnetic instruments were removed out of store, and after repair, packed and delivered to Captain Dawson, R.A., who has been intrusted by the Government with the charge of a tem- porary observatory established in connexion with the International system at Fort Rae, Great Slave Lake, N.W. America. Other instruments were lent to the Rev. S. J. Perry, F.R.S., for use during their residence in Madagascar for the observation of the transit of Venus by a party under his direction ; and a third set were prepared for Dr. Ristori, who projected an expedition to Iceland, but — has not yet started for that country. (See Appendix III.) A Dyp-eircle was also lent to the Austrian expedition to Jan Mayen, to replace one mislaid at the time of sailing of the vessels; this, however, having been recovered by the expedition, the Kew circle has been returned. II. MereoROLOGICAL OBSERVATIONS. The several self-recording instruments for the continuous registra- tion of atmospheric pressure, temperature, and humidity, wind (direc- tion and velocity), sunshine, and rain, respectively, have been main- tained in regular operation throughout the year. The tube of the wet bulb thermograph was accidentally broken on June 30 by a workman engaged in painting the exterior of the building. A spare tube was substituted for it, and only a few hours’ PAIS, 346 : Report of the Kew Committee. trace lost. The scale value of the curves has been altered, and new tabulating scales are accordingly being constructed at the Meteorolo- gical Office. The standard eye observations made five times daily, for the con- trol of the automatic records, have been duly registered through the year, together with the additional daily observations at 0 h. 8 m. p.m. in connexion with the Washington synchronous system. The tabulation of the meteorological traces has been regularly carried on, and copies of these, as well as of the eye observations, with notes of weather, cloud, and sunshine have been transmitted weekly to the Meteorological Office. The following is a summary of the number of meteorological obser- vations made during the past year :-— Readings of standard barometer .............. 1929 A dry and wet thermometers........ 4358 * maximum and minimum thermo- MELOTA! pK Shes cic meine eee 930 RX radiation thermometers .......... 706 3, PAIN AUGER Kos. sc’ eso eke eee 730 Cloud and weather observations .............. 1929 Measurements of barograph curves............ 9125 ‘ dry bulb thermograph curves... 9125 5 wet bulb thermograph curves.. 6850 5; wind (direction and velocity)... 17480 " raintall ‘curves <2. 20.0 eee 809 zs sunshine traces......- eee 22.62 In compliance with a request made by the Meteorological Council to the Kew Committee, the Observatories at Aberdeen, Armagh, Falmouth, Glasgow, Oxford (Radcliffe), Stonyhurst, and Valencia, lave been visited as on former occasions, and their instruments inspected by Mr. Whipple during his vacation. With the concurrence of the Meteorological Council, weekly abstracts of the meteorological results have been regularly forwarded to, and published by “The Times,” ‘“ The Illustrated London News,” “The Torquay Directory,” and “‘ The Torquay Standard,” and data have been supplied to the editor of ‘“‘Symons’s Monthly Meteorological Magazine,” the Secretary of the Institute of Mining Enginetrs, Messrs. Gee, Greaves, Gwilliam, Mawley, Rowland, and others. Electrograph.—This instrument has been in continuous action through the year. In August it was dismounted, and a fresh supply of acid placed in the jar, the charge-keeping properties of which had become slightly deteriorated. Report of the Kew Committee. 347 With a view of investigating the effect of locality upon the indi- cations of the electrograph, a Thomson’s portable electrometer has been employed, with a burning-match collector to make occasional observations around the exterior of the building. These observations are at present suspended, on account of an accidental derangement of the instrument which has necessitated its return for a time to the hands of the maker. The curves have been tabulated up to the end of 1881, and a report on the working of the instrument has been submitted to the Meteorological Council. Mr. W. L. Dallas of the Meteorological Office, having recently been appointed Scientific Assistant to the Meteorological Reporter of India, received instructions in the use of meteorological instruments prior to his departure to that country. ITI. Sonar OBSERVATIONS. The only solar work done at Kew during the past year has been the regular maintenance of the eye observations of the sun, after the method of Hofrath Schwabe, as described in the Report for 1872, | in order to preserve the continuity of the Kew records of sun-spots. These have been made on 197 days. The sun’s surface was found to be free from spots on three of those days. A small portable 2? inch refracting telescope, with a magnifying power of 42 diameters, was used by the observer till July 3rd, since that date the observations have been made by means of the Photo- heliograph, which was removed from the Loan Collection at South Kensington for that purpose, and reinstated on the pedestal in the Dome, a position which it occupied prior to its being sent to the Royal Observatory, Greenwich, in 1873. The spots are now drawn by the Observer, as they appear pro- jected upon the focussing screen. The measurements and reductions of sun-spot positions, as deter- mined by means of the Kew photoheliograph, from 1864 to 1872, having been completed for Mr. De La Rue, he has deposited the manuscript with the Council of the Royal Society. The correction of area measurements, for foreshortening, still remains to be applied to the reductions for the last two years, but this work is now being rapidly pushed forward. Transit Observations.—One hundred and twelve observations have been made of sun-transits, for the purpose of obtaining correct local time at the Observatory ; 168 clock and chronometer comparisons have also been made. Shelton’s Clock, K.O., has been fitted up in the pendulum room, in a convenient position for observing, and a hearing tube led to the side of the transit instrument, so that its errors may be determined 348 Report of the Kew Committee. without the intervention of a chronometer. It has accordingly been made the standard timepiece of the Observatory, instead of Shelton R.S. No. 35 fixed in the computing room, which has hitherto been so employed. A redetermination has been made of the value of the scale divisions of the level of the transit instrument. The De La Rue Micrometer has been recently employed by Dr. Schuster in the measurement of his photographs of the comet observed during the eclipse of last May. TV.. EXPERIMENTAL Work. Exposure of Thermometers.—The observations, made on the lawn of the Observatory, with the view of determining the relative merits of different patterns of thermometer screens were discontinued in November, 1881, the Wild’s screen and the De La Rue portable screen being dismounted and returned to the Meteorological Office. The Stevenson’s screen was, however, purchased by the Committee, and remains standing in-situ for the purpose of exhibition to visitors, and also in order that occasional thermometric experiments may be conducted in it. An exhaustive discussion of the twenty-eight months’ observations has been made by the Superintendent, and submitted to the Meteoro- logical Council, at their request. It may, however, be stated here, that the results show that the obser- vations of air temperature in the thermograph screen, attached to the Observatory building, only differ in the daily mean from those in a freely exposed Stevenson screen 4 feet above the ground by 0°:4, and from a similarly placed Wild’s screen, 10 feet above the surface, by 0O°'l. The extreme variations observed have, however, occasionally reached several degrees. Glycerine Barometer.—This instrument, although still standing in the Library, has not been read since December last. No results having as yet been published of the comparisons made for Mr. Jordan, the inventor, the Committee are unable to form any opinion of the scientific value of the instrument. Pendulum Hxperiments—The pendulum operations in progress at the date of the last Report were terminated in November, 1881, by Major Herschel, R.H., and the instruments he employed (see Appendix III, p. 24) were conveyed by him, first to the Royal Observatory, Greenwich, and subsequently to a house near Portland Place, London. Series of observations were made in both those places, and it is hoped that by this means data will have been obtained, which will serve to reduce to a common standard the deter- minations of gravity made by Kater, Airy, Sabine, and others. Report of the Kew Committee. 349 On the conclusion of these experiments, Major Herschel conveyed the pendulums, clock, &c., to America, where, after making a series of observations at Washington, he handed them over to the officers of the United States’ Coast Survey Department, in whose charge they now remain. Actinometry——At the request of the Meteorological Council, the actinometer devised by Professor Balfour Stewart, and described in the Report of the Committee on Solar Physics, 1880, Appendix H, has been obtained on loan from South Kensington, and erected on a suitable stand on the Observatory Lawn. Numerous observations of solar radiation have been made by it during the past summer, and also several comparative observations have been made with the Hodgkinson’s Actinometers belonging to the Royal Society and to the India Office. At the request and cost of the Indian Government, Sergeant Rowland, R.E., who has since proceeded to India with a view of observing, by means of Stewart’s instrument, the solar intensity at Leh, for a period of three years, has received special instruction in the use of these actinometers. The Committee have had under consideration the desirability of continuing the observations on the actinic power of daylight, which ceased in November, 1875, on account of the unsatisfactory per- formance of the first photometer constructed. The instrument being now made in the improved form suggested by Captain Abney, R.H., is not liable to the derangements experienced by that formerly employed. hating of Chronometers and Watches.—The Superintendent having, from time to time, been requested to certify as to the going of chro- nometers, has been in communication with the Directors of the Observatories at Bidston, Geneva, Neuchatel, and Yale, where arrangements exist for the testing and rating of chronometers and superior watches. The Committee, after receiving his reports upon the subject and also a favourable expression of opinion from the British Horological Institute, considered, however, that the funds at their disposal were insufficient for the present to allow them to extend their operations in this direction. Water-surface Temperature.—At the request of Mr. C. Greaves, C.E., several series of observations were taken at frequent intervals during last summer of the temperature of the surface‘of the pond, a quarter of a mile distant from the Observatory. More recently a float has been moored in the centre carrying maximum and minimum thermometers immersed just below the water-line. Thisis hauled to the shore every morning at 9 A.M.,and the temperatures recorded. The cost of the experiment is defrayed by Mr. Greaves. 390 Report of the Kew Committee. Nocturnal Radiation—Professor Tyndall having suggested the desirability of making a series of experiments on the fall of tem- perature near the surface of the ground at the time of sunset, a scheme was organised and apparatus devised by Mr. F. Galton, by means of which thermometers suspended at heights of 2 feet, 4 feet, and 20 feet could be rapidly read and their indications compared with those of a thermometer placed on swans’ down on the surface of the ground. The apparatus employed is conveyed into the open park to some distance from any building or trees, and the thermometers read at five- minute intervals from about half-an-hour before sunset until one or two hours after. The cost of these experiments will be defrayed by a grant from the Meteorological Council. V. VERIFICATION OF INSTRUMENTS. The following magnetic instruments have been verified, and their constants have been determined :— 1 Unifilar Magnetometer for Negretti and Zambra. 2 Unifilar Magnetometers for Elliott Brothers. 2 Dip Circles for Elliott Brothers. 1 Dip Circle for Casella. There have also been purchased on commission and verified :— A Unifilar Magnetometer for the Toronto Observatory. A Unifilar Magnetometer for the Zi Ka Wei Observatory, China. 2 Dip Circles, with tripod stands, for Dr. Neumayer, Hamburg. 1 Dip Circle, with tripod stand, for Professor Brioschi, Naples. | eee » tor M. Snellen, Utrecht. AL aes » tor Dr. Hann, Vienna. eit, 5, tor Dr. Wild, St. Petersburg. 1 ara », tor Professor Nordenskiold, Helsingfors. A Vertical Force Needle for Dr. Viegas, Coimbra. A Deflection Bar and Pair of Magnetizing Bars for Dr. Rijke- vorsel, Rotterdam. A Pair of Dip-circle Agates for Senhor Capello, Lisbon. The number of meteorological instruments verified continues still to merease, having been in the past year as follows :— Barometers, Standard .(..:..%.0'.2..9 4g 0%h 2 48 35 Marine and Station............ 105 Aneroids........ OSS. he eRe, BIE a Sanaa TOGA sci olay sheceaieesee 183 Report of the Kew Committee. 301 Thermometers, ordinary Meteorological ..... 1518 - s eU Standards on wae tes ot. koe 166 _ Mountamiern sen es oF WS 3 69 * Wlinircaleicae.trstas oie estates: 4 5365 35 Solar radia tiomeme ete. «oe 143 Wo tallags stajaessaxbeore'= DTPA Besides these, 27 Deep-sea Thermometers have been tested, 2 of which were subjected in the hydraulic press, without injury, to pressures exceeding three and a half tons on the square inch, and 73 Thermometers have been compared at the freezing-point of mercury, making a total of 7361 for the year. Duplicate copies of corrections have been supplied in 145 cases. Eleven Standard Thermometers have also been calibrated and divided, and supplied to societies and individuals during the year. The followimg miscellaneous instruments have also been verified :— 2 J/CUDIOCUSIS Ae Oise eR Ee eae re 195 PRMCUMOMMELCTS SIs Hope ae sei ote, oon so tS 12 Jena (GIGI NE dEIS) gee ana a el ae ea ee 4 BCOCOMLES Ths ects oe © oe ie wee ceases oie oie a SSSI ie RRR ea 36 Index Glasses for ditto, unmounted......... 2 Horizon _,, ae A Sapa Pe ee 2 Ecismatic Wompasses. s....5¢-+.+ssase re «« 4 There are at present in the Observatory undergoing verification, ¢ Barometers, 160 Thermometers, 10 Anemometers and 7 Sextants. A Barograph and Thermograph have been examined, and had their scale values determined for the Government Astronomer, Adelaide, South Australia; and a Standard Barometer has also been com- pared for Professor Tacchini, of the Italian Meteorological Service. A Redier Barograph, purchased by Mr. Dowson at the suggestion of the Superintendent, was put up at the Observatory, and its per- formance tested for a fortnight before being forwarded to him. Dr. Siemens having placed one of his Electrical Thermometers at the disposal of the Meteorological Society for their observations of the temperature at the summit of Boston Church Tower, 270 feet high, this instrument was tested for a few days at the Observatory and found to work satisfactorily. Sextant-testing.—A report upon the errors of Sextants, based upon the comparisons made at the Observatory since the introduction of the present system in 1865, has been submitted to Mr. Galton, at his request. O52 Report of the Kew Committee. With a view of checking the values given by means of the Cooke Collimators, a series of angles subtended by various distant well- defined objects at a point at the Observatory, have been carefully determined. The number of surveying instruments tested has satisfactorily increased during the past year. Standard Barometers—From time to time comparisons have been made between the two Welsh Standard Barometers and Newman No. 34, the working Standard of the Observatory, and their relative values have been found to remain unchanged. Standard Thermometers.—Dr. Waldo, Director of the Thermometric Bureau of the Winchester Observatory, United States of America, has visited the Observatory, and selected several standard thermometers | for use in that establishment in the verification of American thermo- meters, and for comparison with other instruments purchased of Continental makers. Experiments have been made, but hitherto without complete success, for the direct comparison of chemical thermometers at high tempera- tures, an operation for which a demand has recently arisen amongst those who supply these instruments in commerce. VI. Aip TO OBSERVATORIES. Wazed Papers, &§c., swpplied.-Waxed paper has been supplied to the following Observatories :— Coimbra, Vienna, Valencia, Colaba, Batavia, and to the Meteoro- logical Office. Photographic Material, &c., has been also procured for, and trans- mitted to, the Coimbra Observatory. Anemograph Sheets have been sent to the Coimbra Observatory, and Blank Magnetic Observation Forms have been supplied to Mr. W. N. Shaw, Cavendish Laboratory ; Professor Mohn, Christiania ; Dr. Lodge, Liverpool Science College ; Captain Dawson, R.A., Circumpolar Expedition ; The Toronto Observatory ; and to Messrs. Casella, Elliott Brothers, and Negretti and Zambra. At the request of the Crown Agents for the Colonies, a copy of the apparatus used at Kew for measuring the areas of sun-spots has been procured for the Mauritius Observatory. A Standard Barometer has also been obtained for the same Observatory. A request has been received from the Director of the Lisbon Obser- vatory for an Hlectrograph similar to that employed in the Observa- tory. The instrument is now in course of construction. Report of the Kew Committee. 353 Tn accordance with instructions received from the Council of the Royal Society, ten volumes of miscellaneous registers, principally of magnetic observations made at Toronto during the years 1840-49, which were deposited in the Magnetic Office of General Sir HE. Sabine, in the Observatory, have been returned to Canada, in order that they may be utilised by Mr. Carpmael, the Director of the Toronto Obser- vatory. Particulars as to the method employed for testing sextants at Kew have been forwarded at his request to Dr. G. Neumayer, Director of the Deutsche Seewarte, Hamburg. VII. MiscELLANEOUS AND FINANCIAL. Tenure of the Observatory.—In January last an inquiry was insti- tuted by Her Majesty’s Commissioners of Works and Public Buildings as to the conditions under which the President and Council of the Royal Society occupied the Observatory building, and it was dis- covered that through inadvertence no intimation had been made, in 1872, to their office of the transfer of the building from the British Association to the Royal Society. Steps were immediately taken to rectify the omission, and in May Mr. Mitford, Secretary to the Office, informed the Secretary of the Royal Society that Her Majesty’s sanction had been obtained for the continuance of the occupation of the Royal Observatory at Kew by the Royal Society upon the following conditions :— Ist. The occupation shall be only during the pleasure of Her Majesty and of the Department. 2nd. The internal repairs, painting, papering, and whitewashing shall be done by the tenants once at least in every seven years, the external works being executed by the Department. srd. No structural alteration shall be effected without the consent of the Board. The above conditions were submitted by the President and Council to the Kew Committee, who have agreed to the terms laid down. The Secretary of State for the Colonies having consulted the Com- mittee as to the equipment of the new Observatory at Hong Kong, has been advised by them as to the instruments they would recommend as desirable for use at that Institution. The Committee have also recommended the establishment at the Royal Observatory at the Cape of Good Hope of a set of self- recording magnetographs. Complete specimen sets of curves from the various photographic and autographic instruments in use at the Observatory have been prepared and forwarded to the exhibitions of the Society of Arts, London, and the Royal Cornwall Polytechnic Society, Falmouth. A number of anemometers and other instruments of interest were 304 Report of the Kew Committee. also exhibited at the Anemometrical Exhibition of the Meteorological Society, held in the rooms of the Institution of Civil Engineers in March. By the censent of the Committee the Superintendent, in conjunction with Mr. Baker, submitted the following paper to the Meteorological Society, which has been published in the Quarterly Journal (Vol. Warts: 198) Barometric gradients in connexion with wind velocity and direction at the Kew Observatory. Tibrary.—During the year the Library has received, as presents, the publications of 26 English Scientific Societies and Institutions, and 91 Foreign and Colonial Scientific Societies and Institutions. Cbservatory and Grounds.—The buildings and grounds have been kept in order throughout the year, and portions of the exterior as well as the interior have been painted by Her Majesty’s Commissioners of Works, &c. They have also fitted stoves in the Superintendent’s room and Library, and re-covered with sheet zinc the roof of the sun-room. The footpath and entrance to the Old Deer Park still remain in an unsatisfactory condition, no action having been taken by Her Majesty’s Commissioners of Woods and Forests in the matter. PERSONAL ESTABLISHMENT. No changes having taken place during the year, The staff employed now is as follows :— G. M. Whipple, B.Sc., Superintendent. T. W. Baker, First Assistant. J. Foster, Verification Department. H. McLaughlin, Librarian and Accountant. F. G. Figg, Magnetic Observer. E. G. Constable, Solar Observations and Tabulation of Meteorological Curves. T. Gunter C. Taylor W. Boxall, Photography. HK. Dagwell, Office duties. J. Dawson, Messenger and Care-taker. With the view of exhibiting the financial position of the Observa- tory during the first decade of its operations under the present Com- mittee, a summarised statement is appended of the receipts and disbursements during the ten years 1871-1881. (Appendix IV.) An appendix is also given showing what instruments belonging to the Observatory are out of the custody of the Superintendent on loan, at the present time. t Verification Department. “AaTddIHM ‘W‘°D = (pousig) "2881 ‘LT waquianonr SS Se Sees ereeregs ———— I 9 8LLe HB) th /h; 02 seeesearerceroversoerer eNOIUBI[OOSITA, PUB [BJUOUTTLOAK GT 8) te3} ; mores STOTOULOULLOU, PABpuUByys Po) Sy Hieron ony gaaut UOLVOUTO A. 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BOO OE ETH E OEE EET OOS OHH OOD syuowseg BAGX ae 96F Poe eoeres eenegeosees er ecererees . oreereee (4snJ, JOIssey)) A401009 [whorl OL Ol PEOlLF POCO ES OHHH OEE OHE HEH OHHH HE OHH OHE EHS OED EOHYHHS HS OEE OOD ESE SHH THE EEE SOTBVS Ag I aGi PO OOOOH OHHH He OOE OE EHH OEE OH THEE EEE SEED HH OHH OHHH EH OOS OHEEED OES T8-O0881 LWCon as oouRleg OL iti) ‘SINGWAV dE ‘BLIdIHOUN MT Z 4aqueaon mouf Junovp spuaewlvg pun sydrovag hwoqoasasgqy avy *4o0NgSQT Cg ER, ee © Or lor) Report of the Kew Committee. APPENDIX I. Magnetic Observations made at the Kew Observatory, Lat. 51° 28' 6" N. Long. 0° 1" 1551 W., for the year October 1881 to September 1882. 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 Magnets N D and N EH being employed for the purpose. The Dip observations were made with Dip-circle Barrow No. 33, the needles 1 and 2 only being used; these are 33 inches in length. The results of the Snes vations of Deflection and Vibration 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 « is (000194. The correction of the magnetic power for temperature 7, to an adopted standard temperature of 35° 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°38 feet, are 1:000075 feet and 1°300097 feet respectively. The times of vibration given in the Table are each derived from the mean of 12 or 14 observations of the time occapied 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 vibration, these being always very small. The value of the constant P, employed in the formula of reduction at =) is —0-00109. b. GEO. In each observation of absolute Declination the instrumental read- ings have been referred to marks made upon the stone obelisk erected 1,250 feet north of the Observatory as a meridian mark, the orientation of which, with respect to the Magnetometer, was determined by the late Mr. Welsh, and has since been carefully verified. The observations have all been made and reduced by Mr. F. G. Figg. Report of the Kew Committee. 307 Observations of Deflection for Absolute Measure of Horizontal Force. Distances oe. of Tempe-| Observed Log —- Month. G. M. T. Centres of | rature. | Deflection. x Magnets. Mean. 1881. da) hem: foot. as zi ee? Gieropee)......2| 26 12 80em| 1-0 51-6 | 15 28 52 13 ak (5 ie) Grea ee. 235 , 1-0 s1-7 | 1527 19 | ~ 12639 13 ae 658 3 November......| 25 12 37 P.M. 10 55°6 UG Baie) 13 59 GEsSu1 st len 230 , 1-0 54-7 | 15 26 46 | 2 12618 13 an 6 57 58 December......| 23 12 32 P.M. 1:0 BOIL 15 29 59 13 ve Gigoneen 219 , 1-0 34°9 | 15 29 15 | 9 12600 jee 13 mt 6 59 14 January........| 2612 30R.m) 1-0 35:0 | 15 29 31 13 ets: G50) |, 232 ,, 1:0 35°9 | 15 98 40 | 9°12591 13 Hig 6 58 57 February ......| 28 12 27 P.M. EO 49°1 15 26 30 13 Wes EG Ay lee 240 ,, 1-0 B15 | 15 25 54 | 2 12648 il 3 eeee 6 57 33 Marc es. 24 12 S4earl: 10 57-7 | 15 27 ‘0 13 ath RES GS 5) AG, 1-0 pera | talon 4 | 27008 13 ah. 6 57 31 April..........| 25 12 43pm} 1-0 57:2 | 15 2717 13 i Grsswe ie DED 1-0 54-2 | 15 26 43 | 2°12632 13 ate 658 7 May ..........| 26 12 34P.m. 1:0 68 °5 15 23 51 13 a GEsGeat me Durst. 1-0 66-5 | 15 23.293 | 9 12558 13 es 6 56 40 mace. ol 27 12, 34 PM. 1:0 ley 15 25 18 13 oR: BiG] aS ee Ds 1-0 73°8 | 15 23 35 | 9°12627 13 Ae 6 56 31 July ..........| 2612 29em.| 10 67-7 | 1524 6 13 ny 6 57. 0 . 2135) 1-0 69°6 | 15 22 57 | 9°12960 13 iy ps 6 56 20 August ........| 3012 48p...| 1-0 66:8 | 15 23 50 13 Mie 6 56 48 : DG | 1:0 68:7 | 15 22 41 | 912589 13 sbi 6 56 12 September......; 2712 31pm] 1-0 59°6 | 15 25 22 3 ue 6 by oa | OOO, ue 1:0 57-8 | 15 2430 | 9°12558 1.75" gare 6 57 5 | 358 Report of the Kew Committee. Vibration Observations for Absolute Measure of Horizontal Force. Tempe- | . pane oe Log mX.| Value one | rature. Vaboae Mean. of m.t Month. 1881. Octobers.<... 60. i Secs. 50°8 46483 51:9 46465 | 0°30915 | 0°52212 November........ 54:3 46510 5471 4°6502 | 0°30883 | 052177 December........ 30°2 46438 36-4 | 46448 | 0°30876 | 0°52165 1882. January......--0- 33°1 4°6427 86:0 | 46425 0:30918 | 0°52184 Hebruaiy ryt 47-9 46468 51:9 46499 0°30903 Oreetes) Marcle ile. 56°3 46536 56°6 46495 0°30880 | 0°52172 ANN ooadogo0d566 | 57°6 46540 52°7 | «446485 0°30877 | 0°52184 WI Gd 6db405 doce 68:2 4°6557 68°3 46548 0°30885 | 0°52145 71:5 4°6579 748 4:6578 030866 | 0°52176 EIR ayn tS: 67:4 | 46535 701 46535 0°30918 | 052166 August ....+..... 65°5 | 4°6551 69°6 4°6526 0°30904 | 0°52145 September....... 59°77 =| 46550 60°1 4°6513 0°30870 | 0°52133 * A vibration is a movement of the magnet from a position of maximum displace- ment on one side of the meridian to a corresponding position on the other side. + m=magnetic moment of vibrating magnet. 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