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extolite, molybdite, allanite, tengerite, and a new hydrated therum-yttrium-lead uranate, termed nivenite-have been found. Agether, this is the richest find of rare earths which has been heard of for some time, and will probably exert a fresh impetus upon the attempts to set our knowledge of the rare-earth elements upon a surer foundation.

THE additions to the Zoological Society's Gardens during the a week include a Ring-tailed Coati (Nasua rufa 8) from oh America, presented by Mrs. Petre; a Common Squirrel 18 uras vulgaris), British, presented by Mrs. S. Stutterd; a Short-eared Owl (Asio brachyotus) from Hampshire, presented by Mr. E. Hart, F.Z.S.; two Owen's Apteryx (Apteryx oweni) from New Zealand, presented by Captain C. A. Findlay, R. N.R., K.MSS. Ruapehu; four Common Vipers (Vipera berus) from Harpshire, presented by Mr. W. H. B. Pain; a Marsh IchDeamon (Herpestes galera) from South Africa, purchased; a ·Troupial (Xanthosomus frontalis) from Brazil, received in exchange.

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1) This is described in the General Catalogue as a globular Custer, very bright, small, round, very suddenly brighter in the midle, barely resolvable (mottled as if with stars)." In 1864 Dr. Huggins observed the spectrum, and noted that it was apparently continuous, extending from the orange to the blue, Without any traces of either bright or dark lines. It was again observet by Wislock at Harvard College in December 1868, and strange to say, a bright line spectrum was recorded. "Two distinct bright lines, near each other, and coincident with airlines A 3020 ± and a 4990; a third faint line λ 4900 ± " ("Harvard College Cservations," vol. xiii. Part 1, p. 64). These lines were all probability the three ordinary nebula lines near ▲ 500, 495, md 486. Winlock describes the nebula as planetary, and gives exactly the same co-ordinates as those given by Huggins and in the General Catalogue. If both observers really saw the samt nebula, the results are highly suggestive of variability; but tre then there is the difficulty of the recorded resolvability. It is quite possible that, in the four years which elapsed between the observations, the spectrum changed from an apparently conmora one to a discontinuous spectrum, by some action similar to that producing variability in such stars as Mira, but at the same time a change of brightness would also be expected, and of this there is no record. In any case, the nebula is well worthy

of further examination.

(2) This star of Group II. is interesting, as being a connecting link between stars like a Herculis, in which the bands are very wide and dark, and those like Aldebaran, in which there is a line spectrum with only the remnants of the bands in the red. Luner states that the bands 2-8 are visible, but all of then are narrow and pale. b, and presumably D, are very Strong Further observations, with special reference to the lines of hydrogen, are suggested.

(3) A star, hitherto described as of the solar type, of which the usual observations are required. If the star appears to be of the same type of the sun or Capella, special attention should te directed to the presence or absence of dark carbon flutings. It is highly probable that stars like the sun, in which there is a photographic indication of carbon absorption, will subsequently cool down and become stars of Group VI., in which carbon

absorption is predominant. If this be the case, all the intermediate stages of mixed metallic lines and dark carbon flutings should be represented amongst the stars.

(4) A star of Group IV., of which the usual observations are required.

(5) This is a star of Group VI. The three ordinary bands of carbon are visible, band 6, near λ 564, being rather pale. A study of Dunér's catalogue of the stars of this group shows that some of those in which band 6 is pale give secondary bands, whilst others do not. This appears to be mainly, though not entirely, due to differences of magnitude. Comparative observations with the same telescope and spectroscope, with reference to this point, are suggested.

(6) Gore states the period of this variable as 378 days, and the magnitudes at maximum and minimum as 9'9 and < 13 respectively. The colour is described as trifling, but the spectrum has not yet been recorded. The maximum will occur on December 28. A. FOWLER.

PERIOD OF U CORONA.-Mr. S. C. Chandler (Astronomical Journal, No. 205), from the observations of the period of this star, finds an inequality of the same order as those detected in 1 U Ophiuchi and U Cephei, variables of the Algol type. The period appears to be shortening by 0.0036s. from minimum to minimum. The results depend upon forty-five very unequally distributed minima; thirty-eight, however, lie in the interval 1870-74, and afford a basis to work upon. A larger series of observations is required to elucidate Mr. Chandler's hypothesis, which, however, is quite conformable within the limits of the purely accidental errors of the observations that have been investigated.

IDENTITY OF BROOKS'S COMET (d 1889) WITH LEXELL'S COMET 1770.-In the same publication as the above, Mr. Chandler gives some most interesting results of an investigation into the orbits of these comets. The following is a summary of the principal conclusions :

(1) The encounter of the comet with Jupiter in 1886 effected a complete transformation of the comet's orbit. Instead of the present seven years' ellipse, it was previously moving in a large one of twenty-seven years' period.

(2) Several months before reaching its perihelion, it passed, near the beginning of 1886, into the sphere of Jupiter's attraction, and was deflected into a hyperbolic path about that planet, and narrowly escaped being drawn into a closed orbit, as a satellite of Jupiter.

(3) At the point of closest approach to Jupiter, May 20, 1886, the comet was distant from it only about nine diameters of the

planet, passing a little outside of the orbit of the third satellite.

(4) In 1779, and not before, the comet must have come so near to Jupiter as to pass under his control and experience a radical change of orbit at the point of longitude where Lexell's comet underwent its notable disturbance in that year. Moreever, the elements of Lexell's comet before the disturbance were strikingly similar to those found for the present comet previous to 1886.

Taking all the points presented into consideration, the argufuller investigation will be made as soon as the observations for ment for the identity of the two comets is overwhelming. A the whole apparition have been received.

SOME PHOTOGRAPHIC STAR SPECTRA.-An examination has been made by Dr. Scheiner of the star spectra photographed at Potsdam (Astr. Nachr., No. 2923). The wave-lengths of lines in the spectra were determined by comparison with the solar spectrum, and as the probable error of the measures is estimated so small as o 005, the identification of the lines seems beyond doubt. The following are some descriptive results :y Cassiopeia. Continuous spectrum; hydrogen lines and D bright.

a Corona. The magnesium line at 448 2 appears as a broad line in this star.

a Lyra. Some fine lines, supposed to be due to iron or calcium, are seen, but have not been measured.

Sirius. 91 similar fine lines to those in the above star have been measured, and 43 ascribed to iron. Even more of these lines occur in Procyon.

a Aquile. The spectrum of this star appears almost identical with that of the sun.

B Orionis. The hydrogen and other lines appear broad, but are not diffused at the edges as in a Lyræ and similar stars. 20 lines have been measured from λ 400 to λ 460.

a Aurige. 291 lines have been measured in the spectrum of this star between λ 410 and λ 470, all of which appear identical with solar lines.

MAGNITUDE AND COLOUR OF ŋ ARGÛS.-Observations of this variable have been made at Cordoba since 1871, and some comparisons made by Mr. Thome (Astr. Nachr, No. 2922) show that it steadily decreased in magnitude until about the end of 1886, when a minimum of 765 was reached, and it is now about 6.6. In 1843, Maclear gave the brightness of Argûs as - 10, or between that of Sirius and Čanopus, so that the variation in magnitude is 8.5, and not 6 as heretofore assumed, this variation, extending over 44 years, gives an average yearly

rate of diminution of o*2.

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It will be seen from the foregoing period, that the comet will be at perihelion again in 1890 January 9.87.

ALGOL.-At the meeting of the Royal Prussian Academy of Sciences, held on November 28, Prof. Vogel gave the results he had obtained from photographs of the spectrum of this variable. Prof. Pickering had pointed out, some years ago, that if the variation in stars of the Algol class were due to the transit of a dark satellite across the disk of its primary, producing a partial eclipse, then since in every case yet known the two bodies must be close to each other, and of not very disproportionate size, the primary must revolve with very considerable rapidity in an orbit round the common centre of gravity of the two; and, therefore, be sometimes approaching the earth with great rapidity and sometimes receding from it. Six photographs of the spectrum of Algol-obtained, three during last winter, and three during the November just past-have shown that before the minimum the lines of the spectrum of Algol are markedly displaced towards the red, showing a motion of recession; but that after the minimum the displacement is towards the blue, showing a motion of approach. Assuming a circular orbit for the star, and combining the details given by the spectroscope with the known variation of the star's light, Prof. Vogel derives the following elements for the system of Algol :

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It will be seen that the density both of Algol and its companion is much less than that of the sun-less than a quarter, in fact. This is what we might expect, for Algol and all the variables of its class yet examined give spectra of Group IV., and should therefore represent a less advanced stage of condensation than that seen in our sun. This demonstration of the truth of the satellite theory of variation of the Algol type derives also an especial interest from Prof. Darwin's researches on tidal evolution, for assuming, as we well may, that the cause of variation is the same in all members of the class, we now know of nine stars in which a large companion is revolving round its primary at but a very short distance from it, and in a very short space of time. The companion of U Ophiuchi must, indeed, be almost in contact with its parent star.

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GEOGRAPHICAL NOTES.

We regret to have to record the death of Major Peter Egert in Warburton, whose name will always be intimately associated with the history of exploration in Australia. He died at Beaumont, Adelaide, in his seventy-sixth year. His most famous achieve. ment, undertaken in 1873, was the crossing of the continent from a point on the overland telegraphic line to the De Grey River, in Western Australia. Nothing was heard of him for about twelve months, during which he and his party suffered terril 'e privations in their march across the desert. After the expedi tion, Major Warburton visited England, and was awarded a Gold Medal of the Royal Geographical Society for his efforts towards increasing our knowledge of the interior of Australia He received the Companionship of the Order of St. Michael and St. George in 1875.

THE death is announced of Cardinal G. Massaja in his eightyfirst year, at St. Georgio a Cremano. For nearly half a century the name of this distinguished explorer has been intimately as50 ciated with the progress of geographical discoveries in Abys sinia and the surrounding regions. It was at his suggestion that the Italian Geographical Society organized the Antinori Expedi tion to Shoa, which has resulted in the occupation of a va region, and the extension of Italian influence over the whole of Ethiopia. His chief work, "I miei trentacinque Anni ne. alta Etiopia," abounds in valuable geographical, historical, and ethnological information on the East African regions for su many years explored and studied by him. The Cardinal was born at Piovà in 1809, and, in 1846, appointed Vicar Apostolic of the Galla nation.

FROM the Berlin Correspondent of the Daily News we learn that a full account of the ascent of Kilimanjaro by Dr. Hans Meyer and Prof. Purtscheller has been received at Berlin. It is dated "Marangu Jagga, October 9." The journey from Zanzibar to Uawela took exactly a fortnight. On September 25 the tra vellers reached Marangu. On October 2 they encamped, with a Pangani negro, on the ridge of the plateau, at a height of 14.450 feet. At 2.30 a.m. they started for the lava-ribs surrounding the valley of glaciers to the south about 1200 feet above. At 7 o'clock, on the right side of the valley, at in elevation of about 16,500 feet, the first snow was seen under cover of the rocks. The higher they went, the more clefts and fissures the field of ice had. The travellers say :-"After great exertions we reached, at 1.45, the snow-line, and it was seen that the highest peak, which was formed of rocks jutting out of the snow, was about one and a half hour's march to the left After resting a day and a half we set off, on October 5, to bivouac in the Lava Cave, at a height of about 15,200 feet, and on the next day we repeated the ascent. The peaks were gained without particular difficulty, and on the central ani highest one, 19,680 feet above the sea, the German flag was planted." Dr. Meyer proposes to call this peak Kaiser Wilhelm Peak. The view from here on to the Kibbs Crater-which is 6600 feet broad and 660 feet high, and the lower half of which is encased in a mighty belt of ice, whilst a volcanic cone of about 500 feet rises in the centre-is magnificent. The beauties of the landscape in the Kilimanjaro region seem to be quite extraordinary. On October 10 the Kimawensi was to be ascended. The two travellers enjoy the best of health.

THE double number of the Bollettino of the Italian Geogra phical Society for October and November, which appears some weeks behind time, is largely devoted to African subjects, and more particularly to the north-eastern region, which is rapidly becoming an "Italian colony." Captain D. Stasio publishes a summary of Don Francesco Alvarez's "Travels in Ethiopia" in the sixteenth century, enriched with valuable notes and additions. Alvarez, a priest attached to an embassy forwarded by Portugal, in 1520, to the Emperor of Abyssinia, shows himself a careful observer of men and things, and his work, which was included in Ramusio's "Navigationi et Viaggi" (Venice, 1588). abounds in details regarding the political, social, and economic relations of that region in the sixteenth century. Grulio D. Cocorda brings to a conclusion his important series of papers

on the South African gold-fields, which include much informaLon on the present condition of the whole of South Africa as far north as the Zambesi. The observer points out that, while the Delagoa Bay and other lines of communication are much Incussed, the fine artery of the perfectly navigable Limpopo is canrely neglected, notwithstanding Captain Chaddock's navigation of it a few years ago. The writer remarks that "this river mainly through regions under the influence or protectorate England; the Transvaal people on the one side, and those of Matabeleland on the other, would certainly be glad to avail themselves of this outlet for their produce. As it traverses only a sall tract of Portuguese territory about its estuary, I hope and leieve that Portugal will not be allowed to treat the Limpopo she is now attempting to treat the Zambesi. The subject is of such importance that it cannot fail soon to be brought before the Brush Parliament." Referring to the negotiations at present going on in connection with the Swaziland question, he observes, in the same spirit :-"The Swazi people must, sooner or later, yield either to the Transvaal or to England, and if to the former, it must be to the entire detriment of British interests. England, as the suzerain power in South Africa, should be the first in the field, both in her own interest and in that of her other colonies and subjects. If she does not assume the protectorate of Swaziland, besides losing the control of a vast and La mineral district, she will deprive the colony of Natal of all farther hope of expansion. If she ignores her responsibility in this matter, and allows the Transvaal Republic to absorb SwaziLand, she will add another to the long list of blunders that ten to destroy all prospect of consolidating a dominion as Large as Canada, and may end disastrously for British interests in South Africa."

A FRENCH traveller has just achieved a feat of great interest. Captain Trivier, equipped by the newspaper La Gironde, started *me eighteen months ago for the Congo State.

He went up

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the river to Stanley Falls, and thence proceeded to Central Africa and the Lake region, accompanying caravans. just arrived at Mozambique.

Ghar reports that during the past summer M. Thoroddsen, well known student of Iceland, has carried out a journey in Lac waste region known as Fiskivötn, lying between Hecla and

Jokul, which has hitherto been unvisited for the most In by any inquirer. To the east and north of Hecla he disWered a new obsidian region. Crossing the Tunguaa, he

to the Fiskivatn group of lakes, all true crater lakes. The dinct between this and the Vatna Jökul has absolutely no plaat nie watever; it consists of lava-fields, and plains of voleric sani. In it be found a lake, Thorisvatn, the second argrat in the island. Thence, after a day's journey through an herly desolate district, he reached the hitherto unknown source of the Tungua. To the south of this he discovered, between hree ranges of hills, previously unknown, a new and very long

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MR. DAUVERGNE has, says the Times of India, completed an adventurous journey in the regions of North-West Cashmere. Hi course was from Leh northwards to the Kilian Pass, in Kobgaria, and then northwards across the Pamir to the Upper Oxus. He reached Sarhad in safety, and after six days' halt there, crossed the Hindu Kush by the Baroghil Pass, as he did not wish to visit Chitral. He then turned eastwards, and after a trying journey through the snow, crossed the Ishkaman Pass, worth of Yasin, Thence he travelled southwards by the Karambar Valley, and eventually reached Gilgit, a short time after Captain Durand had started for Chitral. Mr. Dauvergne reports that the Russian explorer, Captain Grombchevsky, whose attempt to reach Kafiristan was noticed some time ago, was stopped at Kila Panjah on the Oxus, by the Afghan

authorities.

THE ST. PETERSBURG PROBLEM. THIS celebrated problem, which is first mentioned before 1708 in a letter from the younger Nicholas Bernoulli to Montmort, has been frequently discussed by Daniel Bernoulli (1730) and other eminent mathematicians. It may be briefly stared as follows:

A tosses a coin, and undertakes to pay B a florin if head omes up at the first throw, two florins if it comes up at the second, foar florins if it be deferred until the third throw, and so on. What is the value of B's expectation?

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Hence the total value of B's expectation is an infinite series, each term of which is a shilling, or it is infinite.

This result of the theory of probability is apparently directly opposed to the dictates of common-sense, since it is supposed that no one would give even a large finite sum, such as £50, for the prospect above defined.

Almost all mathematical writers on probability have allowed the force of the objection, which they have endeavoured to evade by various ingenious artifices all more or less unsatisfactory. The real difficulty of the problem seems to lie in the exact meaning of infinite and value of the expectation.

Since the infinite value of the result is only true if an infinite number of trials are paid for and made, all such considerations as want of time and the bankruptcy of A or B are precluded by the terms of the question.

The value of B's expectation is frequently confused with how much he can or ought to pay for it; thus Mr. Whitworth ("Choice and Chance," p. 234) finds that if B have 1024 florins, he may give very little more than 6 florins for the venture. This ingenious, solution seems to have no reference to the original problem, which has been modified by Mr. Whitworth's introduction of the word "advantageously " (p. 232).

B can pay for his expectation in three ways: (i.) a sum before each toss; (ii.) a sum before each series of tosses ending with head; (iii.) a sum for the total result of A's operations.

Mr. Whitworth apparently assumes the first method of payment, and shows that the larger B's funds are the more he may safely pay for each toss, since he can continue to play longer. Many mathematicians take the second method of payment. 'However large a fee I for each of these sets, I shall be pay sure to make it up in time" ("Logic of Chance," p. 155). It is easy to show in this case also that what may be safely paid before each series increases with the number of series.

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Suppose a very large number of tosses made, about half would come up heads and half tails; each head would end a series, when a fresh payment must be made by B. Suppose the tosses limited to one series, if B pays one florin he cannot possibly lose, if he pay anything more he may lose by head coming up the first time, and the more he pays the greater will his chance of loss be, since the series of tails must be longer to cover it. But, however large a finite sum he pays, he is not certain to lose, e.g. head may not come up till the hundred and first toss, when he would receive

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2100 1,267 650,600 228,229 401,496 703,205 376 florins. If the sets are limited to one hundred, about

50 heads would probably come up the Ist toss.

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£50 per set, we must expect a number of sets represented by 301 figures.

Lastly, what is the value of B's expectations if A's operations are continued indefinitely. With great deference to contrary opinions, I believe this to be the correct meaning of the problem in its original form. The theoretical result is in this case easily realized by the aid of the following illustration. Suppose the person A replaced by an automatic machine similar to that used for weighing sovereigns, which tosses continuously ten times per minute. On the average of a large number of tosses, B cannot receive less than one shilling a toss, I every two minutes, or £720 a day for ever. If the current rate of interest be 3 per cent., he may safely pay for this perpetual annuity £8,760,000. Suppose, instead of this comparatively slow rate, the machine increased the rapidity of its operations indefinitely, the sum to be paid for the result would also increase indefinitely, or the expectation would become infinite.

SYDNEY LUPTON.

UNIVERSITY AND EDUCATIONAL

INTELLIGENCE.

CAMBRIDGE.-The Newall Telescope Syndicate has drawn up a scheme for building a dome for the telescope on a site adjoining the present Observatory, with an observer's house; and they recommend that an observer be appointed, at a stipend of £250 per annum, with a house, to devote himself to research in stellar physics, under the general direction of the Director of the Observatory.

The results of this year's commercial examination, held by the School's Examinations Board, are satisfactory. Geography was still very imperfect. Elementary mechanics has now been added to the list of compulsory subjects.

An influential syndicate has been appointed to consider the question of the mechanical workshops, their management and utility.

SOCIETIES AND ACADEMIES.
LONDON.

Royal Society, December 12.-" An Experimental Investigation into the Arrangement of the Excitable Fibres of the Internal Capsule of the Bonnet Monkey (Macacus sinicus)." By Charles E. Beevor, M.D., F.R.C. P., and Victor Horsley, B.S., F.R.S. (from the Laboratory of the Brown Institution).

After an historical introduction, the authors proceed to describe the method of investigation, which was conducted as follows. The animal being narcotized with ether, the internal capsule was exposed by a horizontal section through the hemisphere. By means of compasses the outline of the basal ganglia and capsule were accurately transferred to paper ruled with squares of one millimetre side, so that a projection of the capsule was thus obtained, divided into bundles of one millimetre square area. Each of these squares of fibres was then excited by a minimal stimulus, the same being an induced or secondary interrupted current. The movements were recorded and the capsule photographed.

In all forty-five experiments were performed, and they are arranged in eight groups, representing eight successive levels (i.e. from the centrum ovale to the crus) at which the capsule was investigated.

Before the results are described in detail a full account is given of previous investigations, experimental, clinical, and anatomical, on the arrangement of the internal capsule.

The anatomy of the part and the relation of the fibres to the basal ganglia are then discussed, and a full description given of each of the groups examined.

The general results are next given at length, of which the following is a résumé.

Firstly, the rare occurrence of bilateral movement is discussed, and the meaning of the phenomenon defined. Secondly, the lateral arrangement and juxtaposition of the fibres are considered. Thirdly, the antero-posterior order in which the fibres for the movements of the different segments are placed is described, and

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head.

tongue.

mouth.

upper limb (shoulder preceding thumb trunk.

lower limb (hip preceding toes).

The character or nature of these movements is set out in 1 table giving the average localization of each segment. Speak generally, it may be said that the movements are arranged a the same way as has already been shown by the authors to e in the cortex (vide previous papers in Phil. Trans., 1887, 18, viz. that the representation of extension is situated in front flexion for the segments of the upper limb, while for the toes flexion is obtained, as in the cortex, in front of extension. Numerous tables and diagrams are appended, showing extent of appropriation of fibres for each movement.

86

Physical Society, November 15.-Prof. Reinold, F.R., President, in the chair.-Mr. Enright resumed the reading his paper on the electrification due to contact of gases w liquids. Repeating his experiments with zinc and hydrochler acid, the author, by passing the gas into an insulated metal vessel connected with the electrometer, proved that it was alwa charged with electricity of the opposite kind to that of the i tion. The electrical phenomena of many other reactions have been investigated, with the result that the gas, whether H. CC. SO, SH, or Cl, is always electrified positively when escaping from acids, and negatively when leaving a solution of the sta In some cases distinct reversal is not obtainable, but all the seem explicable by considering the solubility and power diffusion of the resulting salts. Various other results given the paper tend to confirm this hypothesis. Seeking for explanation of the observed phenomena, the author could arri at no satisfactory one excepting contact" between gases liquids, and if this be the true explanation he hoped to prove it directly by passing hydrogen through acid. In this, however, he was unsuccessful, owing, he believes, to the impossibility bringing the gas into actual contact with the liquid. True contact only seems possible when the gas is in the nascent stat Some difficulty was experienced in obtaining non-electrified ga for the charge is retained several hours after its production evt if the gas be kept in metallic vessels connected to earth. Sac vessels, when recently filled, form condensers in which the electricity pervades an inclosed space, and whose charge is avul able on allowing the gas to escape. Soap bubbles blown with newly generated hydrogen were also found to act as condensers the liquid of which, when broken, exhibited a negative charge. This fact, the author suggested, may explain the so-called "fire balls," sometimes seen during thunderstorms; for if, by any abnormal distribution of heat, a quantity of electrified air becomes inclosed by a film of moisture, its movements and behaviour would closely resemble those of fire-balls. A similar explanation was proposed for the phenomenon mentioned in a recent number of NATURE, where part of a thundercloud was seen to separate from the mass, descend to the earth, and ris again. The latter part of the paper describes methods of measuring the contact potential differences between gases and liquids, the most satisfactory of which is a "water dropper, and by its means the P.D. between hydrogen and hydr chloric acid was estimated to be about 42 volts. Prof Raber asked if the experiment with zinc and hydrochloric acid could te started in the second stage by having the acid partly saturated with salt. Dr. C. V. Burton thought it probable that contac could be made between a gas and a liquid by shaking them as together in a bottle. In reply, Mr. Enright said the experiment could be started at any stage, and reversal effected as often as desired by adding either acid or a solution of salt to the generaling vessel.-Mr. Herbert Tomlinson, F.R.S., read a paper the effect of repeated heating and cooling on the electrical resist ance and temperature coefficient of annealed iron. In a paper recently presented to the Roval Society, the author has brought forward an instance of an iron wire, which when subjected to magnetic cycles of minute ange alternately at 17° and 100°C, had its molecular friction and magnetic permeability reduced respectively to about one-quarter and one-half their original values The present experiments were undertaken to see whether by

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cheatings and coolings the temperature coefficient of iron and be brought down to something approaching the number ven by Matthiessen for most pure metals." The wire expericalon was first annealed by heating to 1000° C. for several rs and allowing to cool slowly in a furnace placed at right cies to the magnetic meridian; the process was repeated three

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Afterwards the wire was covered with paper and wound (only into a coil. This coil was inclosed in a water-jacketed Cumber, and connected with a sensitive Wheatstone bridge. ro-electric and Peltier effects were eliminated by always ing the galvanometer circuit closed. By repeated heating

C. and cooling to 17° C. for long intervals, the specific stance at 17° C. was reduced from 11,162 to 10,688 G. units, after which the operations produced no further trage At the same time the temperature coefficient inm the proportion of 1: 1'024. From careful determinathe resistance at different temperatures, the formula = R(1+0.0051312 +0'000008152) was deduced, whilst that from Matthiessen's results for pure iron annealed in hyrogen is R=R1+00054251+000000832). Taking his own ermination of specific resistance of impure iron as correct, pled with Matthiessen's law connecting the resistances and perature coefficients of metals and their alloys, the author Lat the specific resistance of pure iron deduced from Thiessen's results is from 4 to 5 per cent. too high. In conCarm. Mr. Tomlinson expresses a hope that the B.A. Electrical andards Committee may be induced to determine the absolute dance and temperature coefficient of the pure metals which reir ordinary use. Prof. Ayrton thought Matthiessen's results were expressed in B. A. units, and hence might appear 1 or 2 jer too great. Mr. Tomlinson, however, believed the Tomber he took were expressed in legal ohms. Dr. Walmsley ked for what value of the magnetizing force the permeability of The fron mentioned in the beginning of the paper was determined; which Mr Tomlinson replied that they were much smaller han the earths horizontal component.-Dr. Thompson's paper geomeinical optics was postponed.

EDINBURGH.

Royal Society, December 2.-Sir Douglas Maclagan, VicePudent, in the chair.-Prof. Tait communicated a paper by Dr. Gr. Flarr, on the transformation of Laplace's coefficients.Mr. A. C. Mitchell read a preliminary note on the thermal concavity of aluminium. A comparatively rough first experiment Dows that this metal slightly exceeds good copper in conducactivity-Dr. John Murray discussed the question of the origin and nature of coral reefs and other carbonate of lime formations in rent seas. He first referred to experiments which have recently been made regarding secretion and solution of carbonate

me. Carbonate of lime remains are found in great abundace at the sea bottom in shallow waters, but the amount adily diminishes as the depth increases, until at 4000 fathoms laust every trace has disappeared. This is due to solution, as organisms slowly fall to the bottom. Everywhere within 500 fathoms of the surface the ocean teems with life.

The

reely Expedition was starving within ten feet of abundant food which might have been obtained by breaking a hole through the ke and using a shirt as a drag.net. Dr. Murray then proceeded dass his theory of the formation of coral reefs, bringing rward in reply to objections by Dana and others, some recently ramed facts regarding the existence of shallow regions in what on the whole, deep water. He showed that carbonate of he is continually produced in great quantity in warm tropical water by the action of sulphate of lime in solution on effete procs. This explains the great growth of coral in tropical regions. The absence of coral on certain shores in tropical districts is plained by the uprise of cold water due to winds blowing off His paper was illustrated by an elaborate series of e-light diagrams,

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PARIS.

Academy of Sciences, December 9.-M. Hertnite in the -On the nitrification of ammonia, by M. Th. Schlosing. lă a recent communication (September 9) the author described three experiments on the nitrification of ammonia in vegetable raus, tending to prove that this phenomenon is accomplished without any appreciable loss of nitrogen liberated in the gaseous e. He now reports the results of two other experiments, howing that this is no longer the case when a larger proportion 4 ammonium carbonate is introduced into the soil.-Correction

in the tables of Jupiter's movement worked out by Le Verrier, by M. A. Gaillot. Comparing the secular terms of the eccentricity and perihelion of Jupiter's and Saturn's orbits as determined by Le Verrier, Hill (Astronomical Journal, No. 204) came to the conclusion that there must be an error of sign in the terms of the second order relating to Jupiter's orbit. M. Gaillot has now gone over the calculations again, and finds that Le Verrier's manuscript is correct, but that, as conjectured by Hill, a misprint of a sign occurs in the published work. In vol. x. p. 242, the sign appears instead of before the term o"015,5548' cos().-On the characteristic temperatures, pressures, and volumes of bodies, by M. Ladislas Netanson. These researches tend to show that for every gas there exists an infinite number of characteristic values, t, p, v, which, being adopted as units of the general variables t, p, v, have the remarkable property of eliminating all difference in the characteristic equations of the different gases. The systems usually employed in measuring temperatures, pressures, and volumes, having nothing in common with the intimate nature of the bodies themselves, give rise to differences in the equation F(t, p, v) = 0, which disappear when for each body the physicist employs a special system in accordance with its properties.-On the localization of the interference fringes in thin isotropic plates, by M. J. Macé de Lépinay. In studying the exact conditions of the fringes in thin prismatic plates, the author finds a complete verification of the general theory expounded by him in a previous communication (Comptes rendus, July 22, 1889). The consequences of the theory may be considered as entirely verified by these experiments.-On the want of accuracy in thermometers, by M. E. Renou. On a recent occasion (July 1) M. Cornu remarked that hitherto these instruments have been liable to an error of from 0° 2 to 0°3. It is now shown that observations hitherto recorded may give rise to the greatest inconvenience, more perhaps in future than at present. These remarks were supplemented by M. Cornu, who pointed out that errors in the mercury thermometer as great as o°2 or o°3 occur only in observations taken at considerable intervals of temperature and with instruments not sufficiently tested. -Variations in the mean temperature of the air at Paris, by M. Renou. Twenty years ago the author attempted to show that severe winters return in groups of five or six every forty-one years. This somewhat elastic period is perhaps reproduced better in groups of years than in single years. It also appears that the Observatory of Paris gives a mean temperature higher by o°7 than that of the surrounding rural districts-10°7 as compared with 100 of the Parc Saint-Maur Observatory.-On the observations of temperature on the top of the Eiffel Tower, by M. Alfred Angot. These observations, begun on July 1, are being still continued with a Richard registering thermometer, placed 336 metres above the sea, and about 301 above the ground. Compared with those of the Parc Saint-Maur (50 metres) they show that the normal decrease of about 1° for every 180 metres is greatly exceeded in summer and during the day (means of the maxima), and correspondingly diminished in winter and at night (means of the minima); or there is generally even an inversion in the temperatures, the air being then warmer at 300 metres than near the ground.-Papers were submitted by M. Raoul Varet, on the ammoniacal cyanides of mercury; by M. L. Prunier, on the simultaneous quantitative analysis of sulphur and carbon in substances containing sulphur; by M. E. Guinochet, on an acid isomerous with tricarballylic acid; by M. C. Tanret, on two new sugars extracted from quebracho (Aspidosperma quebracho); by M. Arnaud, on carotine, its probable physiological action on the leaf; and by MM. André Thil and Thouroude, on a micrographic study of the woody tissues of native trees and shrubs, prepared for the special exhibition of the Forest Department.The sealed paper, by M. A. Joannis, on compounds of potassium and sodium with ammonia gas, was opened by the Secretary.

BERLIN.

Physical Society, November 22.-Prof. du Bois Reymond, President, in the chair.-Dr. Lehmann spoke on the nature and distribution of the Babylonian metrical system. He expressed his desire to lay before the competent judgment of the Physical Society, the results of his most recent archæological researches, so far as they are of direct physical interest, and then proceeded to describe the numerical system employed by the ancient Baylonians, explaining that it consisted of a sexagesimal system with decimal subdivisions. The unit of time, the double

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