12 



JVA rURE 



[January 26, 1893 



to move. The photographs show the successive phases of one 

 entire motion of the fins, which consists of a wave-like motion 

 beginning in front. Shortly after the anterior portion has been, 

 lifted it is depressed, the motion being meanwhile propagated 

 to the lateral portions, and growing in amplitude as the fin grows 

 in breadth. Just before the movement dies out near the tail the 

 process recommences in front. The periodic time was o"8 

 seconds. The photographs show a striking likeness to those 

 obtained by chronophotography applied to the flight of birds. 

 M. Marey intends to study the mechanical effect of the action 

 of the fins upon the water, also by the aid of photography. — 

 Microscopic researches on the contractility of the blood-vessels, 

 by M. L. Ranvier. The perioesophagian membrane of the frog 

 was placed on the disc of the slide-cell in one or two drops of 

 peritoneal serum. It was kept extended by a platinum ring ; 

 electrodes of tinfoil were placed in connection, and a cover glass 

 was fixed over the whole with paraffin. Thus mounted, the 

 smooth muscular fibres and the internal elastic sheath are well 

 seen. On connecting the induction coil with the electrodes, the 

 muscular fibres contract as soon as the current is strong enough. 

 At the same time, the folds of the internal sheath become more 

 pronounced and finally touch, thus effacing the passage through 

 the small artery. On breaking the current, the artery gradually 

 regains its original diameter. If the current is not sufficiently 

 strong for producing a regular contraction, some of the segments 

 contract, while others are at rest. But the zone of contraction 

 is never displaced, and, if interrupted, will reappear at the same 

 place on reestablishing the current. Nothing corresponding to 

 a peristaltic motion can be produced by direct electrical 

 excitement. In none of the experiments, even with the strongest 

 currents, was it possible to detect any signs of contraction in the 

 capillaries. — On the sum of the logarithms of the first numbers 

 not exceeding x, by M. Cahen. — On differential equations of a 

 higher order, the integral of which only admits of a finite number 

 of determinations, by M. Paul Painleve. — On linear differential 

 equations with rational coefficients, by M. Helge von Koch. — 

 Electric waves in wires ; depression of the wave propagated in 

 conductors, by M. Birkeland (see Wiedemann's Annalen, ab- 

 stract). — On the minimum perceptible amount of light, by M. 

 Charles Henry. This was estimated by Aubert at Tj^th of 

 the light of the full moon. This is about a thousand times 

 too great, as proved by some measurements made with the zinc- 

 sulphide (phosphorescence) photometer previously described. 

 The corrected formula for the rate of loss of luminosity of the 

 sulphide is i'<'-5 {t - 18-5)= 1777-8, which agrees even with the 

 longest observations, and is theoretically justified by M. Henri 

 Becquerel. The minimum perceptible amount of light was 

 determined by noticing the time at which the eye, previously 

 kept in the dark for one hour, could only just distinguish the 

 light emitted by the phosphorescent substance, taking care to 

 test for illusions by the successive interposition of ground-glass 

 screens. The time thus found was four hours, giving an amount 

 of light of 29 X io"S standard candles at i m. If the eye is 

 previously kept in the dark during varying periods, the mini- 

 mum varies inversely as the square of the time during which it 

 is kept dark. — On phosphorescent sulphide of zinc, considered 

 as a photometric standard, by the same. Careful tests showed 

 that the light emitted by zinc sulphide at a given instant is 

 independent of the distance of the illuminating magnesium 

 ribbon, of the time of illumination, and of the thickness of the 

 layer, and is also uniform in samples prepared under different 

 conditions, thus exhibiting all the requisites of a secondary 

 photometric standard. — On an acid plato-nitrite of potassium, 

 by M. M. Vezes. — Decomposition of chloroform in presence of 

 iodine, by M. A, Besson. — On some ethers of homopyro- 

 catechine, by M. H Cousin.— On the determination of phos- 

 phorus in iron and steel, by M. Adolphe Carnot. The new 

 method, based like most others on the employment of am- 

 monium molybdate, differs from them in the mode of separation 

 of the silicon, which is effected by sulphuric acid ; in the 

 process of destruction of the carbon compounds, brought about 

 by chromic acid ; and in the nature of the final compound, 

 which is not magnesium pyrophosphate, but dry phospho- 

 molybdate of ammonia, which only contains i '628 per cent, of 

 phosphorus, thus ensuring a greater accuracy in the quantita- 

 tive estimation. — ^Losses of nitrogen in manure, by MM. A. 

 Muntz and A. Ch. Girard. — Researches on the localisation of 

 the fatty oils in the germination of seeds, by M. Eugene 

 Mesnard. It appears that, except in the grasses, the fatty oil 



NO. 1213, VOL. 47] 



is not specially localised. It is in all cases independent of the 

 starch and the glucose, but it appears superposed upon the 

 albuminoid materials in the reserves of ripe seeds. 



Berlin. 



Physical Society,* December 16, 1892. — Prof. Kundt, 

 President, in the chair. — Dr. Lummer spoke on the prin- 

 ciples involved in the use of half-shade polarimeters. He showed 

 that the difference in brightness of the two halves of the field of 

 the instrument depends first on the angle between the two 

 polarising prisms, the less this is the greater being the difference 

 produced by a minimal rotation of the analyzer, and secondly on 

 the power of perceiving minute differences of brightness. In 

 connection with the latter he had made some changes in the 

 Lippich instrument which presented some distinct advantages. 

 — Prof. Goldstein gave an account of some experiments made 

 many years ago, but not yet published. He first dealt with the 

 light which appears at the anode, and which, as compared with 

 that of the kathode, has as yet been but little investigated. As 

 is well known, a kathode consisting of two metals emits rays of 

 different brightness from its two parts, thus for instance the 

 aluminium emits brighter rays than does the silver. When this 

 electrode is used as an anode, the reverse holds good, inasmuch 

 as the anodic light of silver is brighter than that of aluminium. 

 The difference is, however, only observed in rarefied oxygen, 

 and does not exist in a hydrogen tube, and is hence due to 

 oxidation of the silver. The second set of experiments dealt with 

 Crookes' supposed reciprocatory deflection of kathodic rays of 

 similar direction. The speaker had shown, by shielding one of 

 the electrodes, that the deflection is apparent, not real. The 

 change in the path of the kathodic radiation is due entirely to th e 

 effect of the second electrode upon the rays emitted by the 

 first. 



CONTENTS. PAGE 



Modern Advanced Analysis. By P. A. M 289 



The Darwinian Theory 290 



Ferns of South Africa. By J. G. Baker, F.R.S. . . 291 

 Our Book Shelf:— 



Vogel : " Newcomb-Engelmann's Populiire Astro- 

 nomic, Zweite vermehrte Auflage. " — A. T . . . . 291 

 Saunders : "The Hemiptera Heteroptera of the British 



Islands."— W. L. D 292 



Treves :" Physical Education " 292 



Letters to the Editor: — 



The Geology of the North-West Highlands. — Sir 



Archibald Geikie, LL.D., F.R.S 292 



The Identity of Energy.— Prof. Oliver Lodge, 



F.R.S. 293 



A Proposed Handbook of the British Marine Fauna. 

 Prof. W. A. Herdman, F.R.S. ; W. Gar- 



stang 293 



Fossil Plants as Tests of Climate.— Chas. E. De 



Ranee 294 



Racial Dwarfs in the Pyrenees. — R. G. Haliburton ; 



Wm. McPherson 294 



British Earthworms. — Frank J. Cole 295 



Dante's "Quaestiode Aqua et Terra." {With Diagrams.) 



By Edmund G. Gardner 295 



Morocco 298 



The Rate of Explosion in Gases. Prof. Harold B. 



Dixon 299 



Notes 300 



Our Astronomical Column:— 



Comet Holmes 303 



Comet Brooks (November 19, 1892) 304 



Photographic Absorption of our Atmosphere .... 304 



Harvard College Observatory 304 



Solar Observations at Rome . 304 



The Total Solar Eclipse, April 15-16, 1893 .... 304 



Geographical Notes 304 



The Approaching Eclipse of the Sun, April 16, 1893. 



M. De la Baume Pluvinel 304 



Memorial of Sir Richard Owen 307 



Scientific Serials 309 



Societies and Academies 310 



