FOR determination of the air-temperature at great heights, the Berlin Society for Ballooning (we learn from Humboldt) is going to try a method of Herr Siegsfeld, who uses a thermometer, which, by closure of an electric circuit when certain temperatures are reached, gives a light-signal. Small balloons, each containing such a thermometer, will be sent up by night, and the light will affect photographically a so-called "phototheodolite," while the height then attained will be indicated in a mechanical way. It is hoped that more exact formula for the decrease of temperature with height may thus be obtained.

THE rapid decrease in the number of kangaroos is beginning

to attract the attention of scientific Societies in Australia. From the collective reports of the various stock inspectors it was estimated that in 1887 there were 1,881,510 kangaroos. In 1888 the number fell to 1,170,380, a decrease of 711,130. The chief obstacle to the adoption of measures for the effectual protection of the kangaroo is his vigorous appetite. One full-grown Langaroo eats as much grass as six sheep; and graziers-who as a class are not, it is to be feared, readily accessible to the influence of sentiment-find that the food eaten by this interesting animal might be more profitably utilized otherwise. In a communication on the subject, lately submitted to the Linnean Society of New South Wales, Mr. Trebeck suggested that the National Park might be used for the preservation not only of kangaroos but of very many members of the Australian fauna and flora.

Ar the monthly meeting of the Royal Society of Tasmania on September 9, the President (His Excellency Sir Robert G. C. Hamilton) said he desired to bring before the Society a matter relating to the young salmon at the Salmon Ponds. These were the undoubted product of the ova brought out by Sir Thomas Brady, which had been stripped from the male and female fish and artificially fertilized, and the utmost care had been taken to keep them apart from any other fish bred in the ponds. He recently visited the ponds, accompanied by the Chairman of the Fisheries Board, the Secretary, and two of the members, when they carefully examined a number of the young salmon, among which they were surprised to find marked differences existing, not only in size, but in their characteristics. It has often been held that the Salmonide caught in Tasmanian waters cannot be true Salmo salar because sɔ many of them have spots on the dorsal fin, and a tinge of yellow or orange on the adipose fin, but nearly half of the young salmon they examined, which had never left the ponds, had these characteristics. Again, many of them were almost “bull-headed" in appearance-another characteri-tic which is not supposed to distinguish the true Salmo salar. He would suggest to the Chairman of the Fisheries Board, whom he saw present, that the Secretary should be asked to make a formal report of the result of this visit, and to obtain some specimens of the young fish, which could be preserved in spirits, and erhaps sent to Sir Thomas Brady to be submitted for the consideration and opinion of naturalists at home.

AT the same meeting of the Tasmanian Royal Society, Mr. James Barnard read a remarkably interesting paper on the last living aboriginal of Tasmania. It has hitherto been generally believed that the aboriginal Tasmanians are extinct. Mr. Barnard, however, contends that there is still one survivorFanny Cochrane Smith, of Port Cygnet, the mother of six sons and five daughters, all of whom are living. She is now about fifty-five years of age. Fanny's claims to the honour of being a pure representative of the ancient race have been disputed, but Mr. Barnard makes out a good case in her favour. He himself remembers her as she was forty years ago, when there were still about thirty or forty natives at Oyster Cave; "and certainly at that time," he says, "I never heard a doubt expressed of her not being a true aboriginal."

THE Caucasus is a region of great interest in the study of prehistoric times, and a fresh impulse was lately given to its exploration, by Beyern's discovery of an extensive burial-ground south of Kura (in the district of the Anticaucasus). At the recent annual meeting of the German Anthropological Society, Dr. Virchow gave some account of this bed (which Beyern has named after General Repkin). The region is rich in ores, but bronze articles are absent; for, while copper is plentiful, there is no tin. On the other hand, various ornaments of pure antimony have been met with; also antimony buttons (or knobs), like volcanic nature, and many articles of obsidian (chiefly knives those of Beni-Hassan in Egypt. The ground is largely of and arrow-heads) have been found in the graves. One curious find was that of a skeleton having an arrow-head of obsidian in one of the leg-bones, partly overgrown by a callus. The metallic girdles in this burial-ground have figures of animals engraved on them; in the Koban ground, such figures are confined to the clasp, but this, in the Repkin ground, is wanting.

PROF. EDWIN J. HOUSTON contributes to the November number of the Journal of the Franklin Institute a short paper on a bail-storm at Philadelphia, October 1, 1889. After noting various points common to most hailstones, he refers to a characteristic which he had never before observed. "On some of the hailstones," he says, "though not in the majority of them, wellmarked crystals of clear transparent ice projected from their outer surfaces for distances ranging from an eighth to a quarter of an inch. These crystals, as well as I could observe from the evanescent nature of the material, were hexagonal prisms with clearly-cut terminal facets. They resembled the projecting crystals that form so common a lining in geodic masses, in which they have formed by gradual crystallization from the mother-liquor. They differed, however, of course, in being on the outer surface of the spherules."

A SECOND edition of Prof. Tait's “Light” (A. and C. Black) has been issued. The author says that in revising the work he has made use of various notes jotted down from time to time on his own copy, mainly as the result of questions asked, or of difficulties pointed out, by students who were reading the book with care. Suggestions of this kind he has found to be almost always of value, as they tend to make the book better suited to the wants of the class of readers for whom in particular it was designed.

PERSONS interested in ferneries and aquaria will find much to attract them in a little volume entitled "Ferneries and Aquaria a Complete Guide to their Formation, Construction, and Management," by George Eggett, Sen. This is one of a series of "practical guide-books issued by Messrs. Dean and Son.

THE third volume (new series) of the Reliquary (Bemrose and Sons) has been issued. It opens with an interesting illustrated article on two Assyro-Phoenician shields from Crete, by the Rev. Joseph Hirst. Mr. John Ward contributes three illustrated papers of scientific value-on Rains Cave, Longcliffe, Derbyshire; on relics of the Roman occupation, Little Chester, Derby; and on recent diggings at Harborough Rocks,

Derbyshire.

MESSRS. DULAU AND CO. have sent us a Catalogue of Zoological and Palæontological Works." It includes works on Reptilia and Amphibia, and on Pisces.

THE atomic weight of palladium has been redetermined by Dr. E. H. Keiser (Amer. Chem. Journ.). Among all the atomic weights at present adopted by chemists, that of palladium has been one of the most imperfectly determined, for the discrepancy between the results of the various previous investigations is most unsatisfactory. In 1826, Berzelius obtained the value 113.63 from a consideration of the proportion in which palladium combines with sulphur. Two years later, the same distinguished chemist derived a much lower value from analyses of potassium palladious chloride, 2KCI. PdCl2; known quantities of this salt were heated in a current of hydrogen, and the residuary potassium chloride and reduced palladium weighed. Recalculated by Profs. Meyer and Seubert, utilizing all the refined corrections of the present day, these analyses yield the value 106 2—a number which is almost identical with the atomic weight obtained by Dr. Keiser. In 1847, however, Quintus Icilius also investigated the subject, and, from determinations of the loss in weight which potassium palladious chloride undergoes when heated in a current of hydrogen, obtained the value III 88. No other determinations having since been attempted, | and the number 112 or 113 being certainly too high from considerations of the position of palladium among the metals, the number 106 2 obtained from Berzelius's second analysis recalculated by Meyer and Seubert has been universally adopted. To place the subject out of all doubt, Dr. Keiser has re-examined it from a totally different standpoint. The double chlorides of palladium and the alkalies, such as 2KCI. PdCl and 2NHCl. PdCl2, are found to be unsuitable for atomic weight determinations; they retain water of decrepitation with great tenacity, and, after drying, are too hygroscopic for accurate weighing. On the other hand, the yellow crystalline salt, palladammonium chloride, Pd(NH3)Cl2, is a much more suitable substance. It is eminently stable, can be obtained in a state of practically perfect purity, contains no water of crystallization, does not retain water after drying in a desiccator, and the dried salt is not hygroscopic. Weighed quantities of it contained in a platinum boat were introduced into a combustion tube and heated in a stream of pure hydrogen. The hydrogen was rapidly absorbed, changing the bright yellow colour into black, metallic palladium and ammonium chloride

being formed. The absorption of hydrogen occurred so readily that it was only necessary to warm one end of the boat when the heat of the reaction was found sufficient to complete the reduc tion of the whole. Pd(NH),Cl2+ H2 = Pd + 2NH,CL Afer raising the temperature so as to volatilize the ammoniam chloride, the finely divided palladium adhered together in the form of a porous bar having the shape of the boat. It wa allowed to cool before weighing until just below a red heat in the current of hydrogen so as to prevent oxidation, and afterwards the hydrogen was displaced by dry air to prevent its occlusion Two series of determinations were made, the salt for the second series being prepared from the reduced palladium of the first. The mean of eleven experiments in the first series gave the Dumber 106 352, and of eight in the second series 106 35a The maximum value obtained was 106 459, and the minimum 106 286. The mean result 106 35 practically confirms that obtained by recalculating the results of Berzelius's second analyses.

In our note in these columns three weeks ago (vol. xl. p. 655). upon pinol, the new isomer of camphor, it was pointed out that the nitrosochloride of pinol forms with 8-naphthylamine an interesting base, C20H4NO, isomeric with quinine. This base, how. ever, is not the first isomer of quinine which has been prepared. for an artificially prepared base of the same empirical formula was described by Dr. Kohn, of University College, Liverpool, in the Journal of the Chemical Society for 1886, p. 500.

THE additions to the Zoological Society's Gardens during the past week include three Rhesus Monkeys (Macacus rhesus ¿¿¿) from India, presented respectively by Colonel Cuthbert Larking, Mr. James T. Wilson, and Mrs. Charles Sainsbury; a Hairy-rumped Agouti (Dasyprocta prymnolopha) from Guiant. presented by Mr. Henry E. Blandford; a Common Polecat (Mustela putorius) from Norfolk, presented by the Earl of Romney; a Northern Mocking Bird (Mimus polyglottis) from North America, presented by Miss E. Breton; two White Pelicans (Pelecanus onocrotalus), a Crested Pelican (Pelecanus crispus) from Roumania, a Common Boa (Boa constrictor), a Neck-marked Snake (Geoptyas collaris) from Panama, a Mocassin Snake (Tropidonotus fasciatus) from North America, deposited; two Common Siskins (Chrysomitris spinus), two rufescens), four Snow Buntings (Plectrophanes nivalis), two Twites (Linota flavirostris), two Lesser Redpoles (Linota Knots (Tringa canutus), a Bar-tailed Godwit (Limosa lapponica), British, a Rosy-billed Duck (Metopiana peposaca ¿) from South America, purchased.

is a faint continuous spectrum at the preceding edge of No. 386. The point chiefly requiring attention at present is the character of the line near 500. Many recorded observations describe this line as having a fringe of light on the more refrangible side, whilst others state that it is perfectly sharp on both edges. Low dispersion only should be employed in making this observation. The observation of continuous spectrum in a special part of the nebula 386 is also worthy of attention; the spectrum should be examined for maxima of brightness, as in the case of the nebula in Andromeda.

(2) Duner records this as a star of Group II. (see below), but states that the spectrum is very feebly developed. The star is probably, therefore, either just condensing into a fully-developed star of Group II., or is just passing into Group III. If the former, there will practically be nothing but very narrow bands, and if the latter, absorption lines will accompany the bands. In the earlier stages of this group, the bands in the blue are strongest, whilst in the later stages red bands are strongest, and this point should also receive attention. As a check, the colour of the star should be noted at the time of observation.

(3) This star belongs to either Group III. or to Group V., and the criteria (see p. 20) should be observed in order to determine which.

(4) According to Vogel, the spectrum of this star is of the same type as a Lyræ, i.e. Group IV. The relative intensities of the metallic lines and those of hydrogen, which vary from star to star, should be noted for future classification of the stars of this group according to temperature.

(5) This is a star of Group VI. Danér describes the spectrum as consisting of four zones, the zones being the bright spaces between the dark carbon flutings. The presence of slight traces of carbon absorption in the solar spectrum indicates that stars of this group only differ in temperature from stars like the sun. The passage from one group to the other will probably be found to be very gradual, and the widths of the carbon flutings and the presence or absence of other absorptions should therefore be noted.

16) Period given by Gore as 382 days, and magnitude at maximum (November 13) as 6'9-77. The spectrum has not yet been recorded, and the present maximum may, therefore, conveniently be taken advantage of.

(7) Period given by Gore as 168 days, and magnitude at maximum (November 15) as 8'3-9. Spectrum not yet recorded. Note.-Lockyer's classification will, in future, be exclusively used, so that there will be no necessity for a double reference. The relation of this to Vogel's classification is shown in the following diagram :Group IV. (Class I.a).

Catalogue included 2248 double and multiple stars, and of them, 2130 are shown upon these charts. In addition to this, 275 of the double stars discovered by Mr. S. W. Burnham have been mapped, this being the whole of those included in his first four catalogues, and a selection from his other catalogues. The maps have been drawn to a scale of one-third of an inch to a degree, which is a much larger scale than any hitherto published, and as each map includes but a small portion of the heavens, there is practically no distortion, whilst the epoch being 1890, the positions will hold good, without any serious errors, for fifteen or twenty years beyond that date. The projection is conical, or, in those charts which extend any distance both north and south of the equator, cylindrical. Hence it will be easy to lay down any additional objects that may be required. There is no doubt that these charts will be eminently useful, one of their great advantages being that they will enable possessors of telescopes mounted on altazimuth stands or without circles to find with ease a large number of interesting objects, and thus will help to extend the knowledge of the heavenly bodies and to popularize the most fascinating of sciences. We may say that the publisher of these charts is Edward Stanford, Cockspur Street, S. W., and that the first issue is limited to 200 sets, many of which have been already subscribed for.

BARNARD'S COMET, II. 1889, MARCH 31.-The following ephemeris is given in Astronomische Nachrichten, No. 2931 :

R.A.

h. m. S. I 854

549 2.49

Decl.

1889.

R.A.

h. m. s.

- 16 30 2 Nov. 22... o 28

..

Decl.

2...

7

16372

8

16 43'6

9.

0 59 53

16 49'5

- 17 21'5

4...

813

18

19..

...

32 II ... 30 5 22... 28 2...

- 17 25°4

I... 2...

17 5

15 28 1355

12 25 10 58..

17 216

17 20'0 -17 18:3 -17 16:3

17 14'3

-17 12'0

4 29. -17 44

3 20...17 1'5

THE STRUCTURE OF JUPITER'S BELT 3, III.-This dark band appears under ordinary conditions to be made up of two parallel bands, but Dr. Terby (Astronomische Nachrichten, No. 2928) says this appearance of parallelism is the result of the special structure represented in the accompanying figure, and

LARGE-SCALE CHARTS OF THE CONSTELLATIONS. — Mr. Arthur Cottam has projected a series of thirty-six most excellent charts of the constellations from the North Pole to between 35° and 40° of south declination, and showing stars in half magnitudes down to 6 by disks of various sizes. Although the primary object in constructing these charts was to make them companions to Webb's "Celestial Objects for Common Telescopes" and Smyth's "Cycle of Celestial Objects," their scope has been considerably enlarged, and a number of double, multiple, and variable stars have been laid down which are not included in either of the above-mentioned works. The Earl of Crawford's (Dun Echt) summary of F. G. W. Struve's Dorpat

C

Structure of Jupiter.

A

that, therefore, the band 3, III., is composed of a lot of dark bands inclined in the same direction. The circular parts A are distinguished by Dr. Terby as emitting a sort of diffused light of an entirely different character from the white equatorial spots, properly so called; these luminous balls seem always to occur at the interval between two of the inclined bands, and touching what is generally their darkest part, B. The brilliant white spots D also appear at the dissolution of two successive bands, and occupy by preference their northern extremities. When the definition was very good, Dr. Terby observed that the interval between two of these fragmentary bands had the appearance of a series of globules, as shown in the figure. The structure appears so general and regular that it may be the means of adding considerably to our knowledge of the physical constitution of this planet.

GEOGRAPHICAL NOTES.

AT the first meeting of the session of the Royal Geographical Society, the paper was on Cyprus, by Lieut.-General Sir Robert Biddulph, G.C.M.G., C. B. The island of Cyprus is the third largest in the Mediterranean, being inferior in size only to Sicily and Sardinia. Its area is 3584 square miles. Its principal

features are two mountain ranges, running pretty well parallel to each other from east to west. The northernmost of these two ranges extends almost the whole length of the island from Cape Kormakiti on the north-west to Cape St. Andrea at the end of the horn-like promontory which stretches for 40 miles from the north-east of the island. This promontory is called the Carpas, and the low mountain chain running through it is called the Carpas range. The westernmost and higher portion of the northern range is called the Kyrenia range, and rises to an altitude of 3340 feet. This range is of a remarkably picturesque outline, in some parts extremely rugged. It is mostly a single ridge without any remarkable spurs, and its summit is about two miles from the northern coast. It can be crossed in many places. The chief mountain peaks of this range are Kornos, 3105 feet; Buffavento, 3140; and Pentedaktylos, 2400. The last named is a remarkably shaped rock in the centre of the Kyrenian range, owing its name to its shape, the word Pentedaktylos signifying in Greek "five-fingered." Beneath this rock there rushes out southward from the mountain side, at an altitude of 870 feet, a torrent of water, which never ceases to flow summer or winter, and which, descending into the great plain in the centre of the island, carries its fertilizing streams to the lands of several villages, its course marked by mills, gardens, and trees, until its water is exhausted by various irrigating channels. A similar stream of water gushes from the northern side, about 12 miles west of the Kyrenia Pass. Smaller streams descend on either side of the range at various places; their waters are used for irrigation in the valleys. The southern range of mountains is of a much more extensive nature than the northern range. The easternmost point of this range is the mountain of Santa Croce, so called from the church of the Holy Cross which stands on its summit. This mountain, which is 2260 feet in height, is of a peculiar shape. Beginning then from this point the southern range rapidly rises to considerable altitudes, finally culminating in Mount Troodos, the highest point in Cyprus, being 6406 feet above the sea-level. The other chief peaks in the southern range, are Adelphe, 5305 feet; and Machera, 4674 feet. But it is not only in altitude that the Troodos range is distinguished; numerous spurs run down to the north and south, and as we proceed further west these radiate out to greater distances, so that half way between Troodos and the sea, the mountain range is not less than 20 miles wide. Here there are very considerable forests, many miles in extent, rarely visited save by wandering flocks and by wood-cutters, and affording shelter to the mouthlon, or wild sheep of Europe, some 200 or 300 of which still roam over these hills. On the map it will be seen that numerous rivers descend from both sides of the southern range. These are mostly dry in summer, but after rain their waters descend with violence, filling up the river-beds in the plains, carryiny away trees and cultivated patches, and often rushing in a turbid stream into the bays of Famagusta and Morphou. Between the two mountain ranges there lies a great plain called the Mesaorea, which is the most fertile part of Cyprus, growing large crops of wheat, barley, and cotton. It was evidently once the bottom of the sea, for in many parts are large beds of marine shells-gigantic oysters and -others-all clustered in masses. A noticeable feature of this plain is the number of flat-topped plateaux of various sizes, where the rock seems to have resisted the action of the water. The tops of these plateaux are clothed with short herbage, affording a scanty provision for flocks, and are usually from 100 to 200 feet above the plain. The rivers which descend from the hills carry down large quantities of alluvial soil, and this forms in the eastern part of the Mesaorea a rich deposit, something similar to the Delta of the Nile. The two rivers which mainly contribute to this plain are the Pedious and the Idalia, the former taking its rise from the northern slopes of Mount Machera, and the latter from the eastern slopes of the same mountain. The beds of these rivers have, however, become so choked up with alluvial deposit towards the end of their course, that their waters overflow the plain and mingle together, so that their separate mouths can with difficulty be distinguished. The normal condition of these rivers is to be without water, but whenever there is a heavy rainfall in the mountains, the river " comes down," as it is called, and runs for one, two, or more days. It occasionally happens that the water descends with great suddenness and violence, causing disastrous floods. Considerable supplies of water for irrigation purposes are obtained by sinking wells. A long chain of wells are sunk at distances of five or six yards apart, and being connected by underground galleries, a channel is thus formed which conveys the water to a reservoir constructed

at the foot of the last well, and it is thence raised to the surface by a water-wheel; or in some cases the level of the groun! admits of the channel being brought out on the surface. In way the town of Nicosia is supplied with excellent water, which is brought in two aqueducts from a distance of some mile Larnaca and Famagusta and other towns have similar aqueducts. Closely connected with the water supply is the forest question Sir Robert Biddulph then entered into detail with reference ** the denudation of Cyprus of its forests, and the great locusplagues which have been so successfully treated since the Briti occupation.

THE FLORA OF CHINA.1

SINCE the last meeting of the British Association, two ad fi tional parts of the "Index Flore Sinensis" have bee published, bringing the enumeration of known, and the description of new, species as far as the Loganiacea. The Committee now, therefore, look forward with some confidence to the com pletion of their labours at no distant date.

Further extensive and valuable collections have been received from China in aid of the work, more especially from Dr. Auguitine Henry, late of Ichang. The novelty and richness of the material obtained by this indefatigable botanist far exceeds any expectations the Committee could have formed. It is to be re gretted that his duties as an officer of the Chinese Imperial Maritime Customs have necessitated his removal to Hainan. 1: is probable, however, that he had practically exhausted the immediate neighbourhood of Ichang, and that without opportunities of travelling over a wider radius, which the Committee regret they were unable to procure for him, he would not have been able to add much of material novelty to the large colle tions already transmitted by him to Kew.

The Committee have met with the kindest sympathy and assistance in their labours from Dr. C. J. de Maximowicz, of the Académie Impériale of St. Petersburg, who has long been engaged on the elaboration of the collections made by Russian travellers in China, and from M. Franchet, of the Museum d'Histoire Naturelle at Paris, who is describing and publishing the extremely rich collections made by the French missionaries in Yunnan.

The Committee have received striking proofs of the appreciation of their labours by botanists of all countries. They permit themselves to quote the following passage from a letter receivei early in the present year from Baron Richthofen, than whom to one is more competent to estimate the value of work connected with the scientific exploration of China :

"It is of great value to have, now, a Flora of China, embolying all the species known from that country. You have evidently succeeded at Kew in getting a very complete collection. At the same time, in looking over the localities mentioned in the book, it strikes me that large portions of China are stili unexplored botanically. There remains a splendid field for a good collector in the Tsingling Mountains, the province of Sz'chuen, and chiefly its elevated region west of Ching-tu-fu. Work in those parts will be greatly facilitated by the solid foundation laid through the work of Forbes and Hemsley."

The Committee derive an independent existence as a SubCommittee of the Government Grant Committee of the Royal Society. They are at present in possession of sufficient funds to enable them to carry on the work. They do not therefore ask for their reappointment at the hands of the British Association.

SCIENTIFIC SERIALS.

American Journal of Science, October. -Assuming that the earth's crust rests on a layer of liquid as a floating body, Mr. Le Conte here offers an explanation of normal faults. The crust is supposed to be raised into an arch, by intumescence of the liquid, caused by steam or hydrostatic pressure; it is thus broken by long more or less parallel fissures into oblong prismatic

Third Report of the Com nittee, consisting of Mr. Thiselton-Dyer (Secretary), Mr. Carruthers, Mr. Ball. Prof. Oliver and Mr. Forbes, ap pointed for the purpose of continuing the preparation of a Report on our present knowledge of the Flora of China.

blocks, which, on relief of the tension by escape of lava or vapour, are readjusted by gravity, in new positions. The blocks may be rectangular in section, but are more likely to be rhomboidal or wedge-shaped; giving level tables with fault cliffs (as in the plateau region) in the one case, and tilted blocks with Formal faults (as in the basin region) in the other. The author considers the Sierra and Wahsatch to have been formed by Interal crushing and folding; and the region between to have been arched, broken, and readjusted, as described, in the end of the Tertiary.-Two determinations of the ratio of the electromagnetic to the electrostatic unit are furnished from the Johns Hopkins University; one made this year, by Mr. Rosa, by Maxwell's method of measuring a resistance, the other ten years ago, by Messrs. Rowland, Hall, and Fletcher, by measuring a quantity of electricity electrostatically, and then measuring it electromagnetically with a galvanometer. The former gives v = 2 9903 x 1010 centimetres per second; the latter, 29815 × 1010 centimetres. It seems certain, according to Mr. Rosa, that vis within a tenth per cent. of 300 million metres per second.-Mr Long continues his account of the circular polarization of certain tartrate solutions; and his experiments point to a law that the rotation of a double tartrate may be made to approach that of a neutral tartrate of either of the metals present, by addition of a sa of that metal (the effects being apparently explained by abstitution).-Mr. Eldridge proposes a new grouping and nomenclature for the middle Cretaceous in America. There are alse papers on the gustatory organs of the American hare (Mr. Tackerman); on the output of the non-condensing engine, as a function of speed and pressure (Mr. Nipher); and on some Ficrola Miocene (Mr. Langdon).

SOCIETIES AND ACADEMIES. LONDON.

Physical Society, November 1.-Prof. Reinold, F. R.S., President, in the chair.-The following communications were Fead-On a new electric-radiation meter, by Mr. W. G. Gregory. The meter consists of a long fine platinum wire attached to a delicate magnifying spring of the Aryton and Perry type, and stretched within a compound tube of glass and brass. At the junction between the wire and spring a small mirror is fixed. When the tube is placed parallel to a Hertz's oscillator in action, the mirror is turned in a direction indicating an extension of the wire. The arrangement is so sensitive that an elongation of of a mm. can be detected, and when placed at a distance of 4 metres from the oscillator the apparent extension is such as would correspond to a change of temperature of 0° 003 C. By its aid the author has roughly verified Hertz's statements that at considerable distances the intensity of radiation varies as the inverse distance; but before he can proceed further it is necessary to greatly increase the sensibility of the apparatus ; and with a view of obtaining some suggestions in this direction, he exhibited it before the Society. Prof. Perry asked if the E. M. F. required to produce the observed results had been calculated; he also believed that the sensibility might be increased by using copper instead of platinum wire, and replacing the spring by a twisted strip. Mr. Blakesley inquired whether the effect of .ncreasing the capacity of the ends of the wire had been tried. Mr. Boys said that if the observed effect was due to rise of temperature he would like to see it measured thermally. He also thought the effect might be due to extension caused by rapid electric oscillations in some such way as the elongation of an iron bar caused by magnetization. In answer to this, Prof. S. P Thompson said the matter had been investigated experimentally, but with negative results. Prof. Herschel suggested the use of a compound spring such as is used in Breguet's metallic thermometers. In reply, Mr. Gregorv said he had estimated the E.M.F. by observing that a Leclanche cell through 50 ohms produced about the same result. No improve ment in sensitiveness was obtained by using copper wire or by increasing its capacity, and attempts to measure the rise of temperature by an air thermometer had been given up as hope

Jess

The President, in thanking the author ior his paper, congratulated him on the ingenuity and courage displayed in producing an apparatus to measure such microscopic quantities as

are

here involved.-On a method of driving tuning-forks electrically, by Mr. Gregory. In order to give the impulses about the middle of the stroke, the fork is arranged to make

and break the primary circuit of a small transformer, the secondary circuit of which is completed through the electromagnet actuating the fork. The prongs of the fork are magnetized and receive two impulses in each period. Another device was suggested, where the prongs respectively operate contacts which successively charge and discharge a condenser through the coils of the actuating magnet. Prof. S. P. Thompson said the methods, if perfect, would be of great service, and suggested that a fork so driven be tested optically by comparison with a freely vibrating one. He regarded the mercury contacts used as objectionable, for their capillarity and adhesion would probably cause the impulses to lag behind the appointed epochs. Prof. McLeod remarked that Lissajous' figures gave a satis factory method of testing the constancy of period, and could be readily observed without using lenses, and in reference to liquid condensers suggested by the author for his second device, said that platinum plates in sulphuric acid were found to disintegrate when used for this purpose. He thought lead plates would prove suitable. Prof. Jones, who read a paper on a similar subject in March last, said he now used bowed forks, with which to synchronize the speed of the disk there described, and the frequency is determined by causing the disk to complete the circuit of his Morse receiver once each revolution. On a physical basis for the theory of errors, by Mr. C. V. Burton. After pointing out that the law of error for any particular measurement depends on the nature of the conditions governing such measurement, the author considers several simple cases, and deduces their curves of error. A kinematic method of combin ing two or more independent errors, each following known laws. is then described and applied, and the general formula obtained leads to Laplace's law of error in the case of an infinite num ber of similar errors. Referring to Most Advantageous Combinations of measures, it is shown that the method of least squares is only a particular solution of the general equation, and is derived by assuming the individual errors to conform to Laplace's law. Subjective errors are next considered, and ir conclusion the author says that "the law of error in a set of observations depends on the nature of each special case, and what may be called the probable law of error is determined by our knowledge of the conditions. The combination of three or more sources of error of comparable importance gives in general a law not seriously differing from that of Laplace, so that the method of least squares will be practically the most advantage. ous, except where a single source of error with a very differen law is predominant above all the rest."-A note on the behaviour of twisted strips, by Prof. J. Perry, F.R.S., had been prematurely announced by mistake, and he accordingly gave only a brief outline of the paper. In a previous communication, Prof. Ayrton and the author enunciated a working hypothesis in which the strips were imagined to be split up into pairs of filaments, each pair acting as a bifilar suspension. The resulting formula for the rotation produced by a given load did not agree with experiment, and quite recently the author had recognized why the formula was incorrect. The bifilar law they had assumed was only true for small twists, but he now saw another method of treatment by which he hoped to verify the formula derived from experiment before the next meeting. Prof. Fitzgerald reminded Prof. Perry of a method of attacking the problem suggested by the speaker some time ago, in which each filament was supposed to be wrapped round a smooth cylinder : and said that on working it out the formula was found to be very complicated. Mr. Trotter thought the pairs of strips might be regarded as twisted ladders, and Mr. Gregory said this suggestion reduced the problem to a series of bifilar suspensions which had already been worked out.-On electrifications due to contact of gases and liquids, by Mr. J. Enright. For some time past the author has been studying the electrical phenomena attending solution, by connecting an insulated vessel in which the solution takes place with an electrometer. As a general rule, no effect is observed if nothing leaves the vessel, but when gases are produced and allowed to escape the vessel becomes charged with + or - electricity, depending on the nature of the liquid from which the gas passes into the air. As an example, when zinc is placed in hydrochloric acid, the deflection of the electrometer is in one direction whilst the liquid is chiefly acid, but decreases and reverses as more and more zinc chloride is produced. From such observations the author hopes to obtain some information relating to atomic charges. Owing to the lateness of the hour, the latter portion of the paper and the discussion on it were postponed until next meeting.