484 



NATURE 



[September 15, 1892 



than that polarised parallel to them. The contrary was ob- 

 served in scratched glass gratings, while a scratched metal 

 mirror reflected 4 per cent, more perpendicular than parallel 

 light. — The limiting index of refraction for infinitely long 

 -waves ; transformation of the equations of dispersion, by E. 

 Ketteler. The determination of the limiting coefficient of re- 

 fraction is shown to be impossible, both in practice and by 

 the current theory. Another form of the equation of motion of 

 light is worked out, which promises a solution of the problem. 

 — On the electricity of waterfalls, by Ph. Lenard. Nume- 

 rous observations and experiments concerning the electricity 

 developed by water falling in drops, jets, or waterfalls have 

 led to the following general conclusions : Drops of water falling 

 on to water or a wetted body generate electricity. Water is 

 electrified positively, air escapes negatively electrified from 

 the foot of the fall. Jets breaking up into spray make the 

 electrification more apparent. Slight impurities in the water 

 diminish the effect considerably. Other liquids and gases 

 also produce electrification, but differing in intensity and 

 sign. The essential conditions of electrification are the con- 

 cussions among the waters themselves and against the wet rock. 

 The friction against the rock and the fall of the earth-potential 

 are of secondary importance, while no effect is due to the 

 water's fall through air and its dispersion in it. The author 

 explains these phenomena by the sudden diminution of the 

 water surface, and the convection of negatively charged air away 

 from the foot of the fall, A jet of water falling from an 

 insulated tank into an insulated pail- electrified the latter 

 positively, while the negative electrification of the surrounding 

 air grew to several hundred volts. A steady increase of potential 

 was also produced by drops of water falling at the rate of two 

 per second. Sparks were sometimes obtained from waterfalls, 

 and in all cases the air was found to be negatively charged, 

 though this charge was diminished if air bubbles were driven 

 under water. — Note on a phosphoroscope with spark illumin- 

 ation, by Ph. Lenard. This ingenious apparatus consists of a 

 Ruhmkorff coil with condenser and mercury interrupter, fitted 

 with terminals of strip zinc or zinc wire, in order to produce as 

 much ultra-violet and phosphorescent light as possible. The 

 arm of the mercury interrupter is prolonged, and carries at its 

 end a rectangular shade of black paper, large enough, in its 

 mean position of rest, to hide the spark and the terminals. 

 Hence when the coil is working the sparks are not seen. But if 

 a phosphorescent substance be placed behind the terminals, it 

 continues to glow when the screen is at its highest or lowest 

 position, thus producing the impression as if the screen, which 

 appears perfectly stationary, were only transparent for phos- 

 phorescent light. For lecture purposes the apparatus is placed 

 behind a screen with an opening as large as the black paper 

 shade. The results are in general the same as those of Becquerel's 

 phosphoroscope. A brilliant green light is obtained from 

 pentadecylparatolylketone. The interval between illumination 

 and observation is ^^^ second. — On the production and obser- 

 vation of very rapid electric oscillations (continued), by A. 

 Toepler. — On the use and mode of action of the telephone for 

 electric null methods, by A. Winkelmann. 



SOCIETIES AND ACADEMIES. 

 Paris. 

 Academy of Sciences, Sept. 5.— M, de Lacaze-Duthiers in 

 the chair.— Note on the treatment of cancer and cholera by the 

 testiculary liquid, by M. Brown-Sequard. Some recent results 

 seem to indicate that the testiculary liquid, already proved to be 

 efficacious in cases of pulmonary tuberculosis, leprosy, and other 

 diseases, also exerts a beneficial influence on cancer patients. 

 This is not due to any action upon the microbes producing the 

 disease, but to an augmentation of the powers of the nervous 

 system, which is enabled to resume its normal functions by sub- 

 cutaneous injections of the extract. M. Ouspensky, a military 

 physician sent by the Russian Government to study and cope 

 with the cholera in the Caucasus, is reported to have "cured 

 every patient " by this method. Whether or not this be true, 

 there is no doubt that the injections strengthen the nervous 

 system, which is much exhausted even in convalescents, — 

 Observations of the comet Denning (1892, II,) made at the 

 ^reat equatorial of the Bordeaux Observatory, by MM. G. 

 Rayet, L. Picart, and F. Courty, reported by M. G. Rayet. — 

 Observations of the planet Mars, by M. Perrotin [see p. 482]. 



— Reappearance of the leafy celandine of Pumeterre, by 

 M. D. Clos. — Observations of the new comet Brooks (C. 

 1892), and of the new planet Wolf, made at the Obser- 

 vatory of Paris (west equatorial), by M, G. Bigourdan. — 

 Observation of the comet Brooks (August 28, 1892), made 

 with the Brunner equatorial (o'i6) of the Lyons Observatory, 

 by M, G. Le Cadet. — On the calculation of inequalities of a 

 high order, by M. O, Callandreau. — On a new form of induc- 

 tion apparatus, by M. J. Morin, The induction coils usually 

 employed in electrotherapy are constructed with two cylindrical 

 and concentric bobbins, sliding one over the other, and giving 

 the maximum effect when the coils coincide along their whole 

 length. There is a difficulty in reaching the zero by a regular 

 diminution of the current. This is obviated in the apparatus 

 as constructed by M. Morin. The conducting wires are wound 

 on two flat concentric rings provided with channels of appro- 

 priate form. When an intermittent current is sent through the 

 outer ring induced currents will be obtained from the inner 

 ring. The effect will be greatest when the two rings are in the 

 same plane. If one of these rings be turned round a diameter 

 common to both the induced current will gradually diminish, 

 and will vanish when the one ring is at right angles to the other. 

 This arrangement could be employed for obtaining alternate 

 currents by sending a continuous current through one of the 

 rings and rotating the other. A sinusoidal current would be 

 thus generated, the effects of which have been lately much 

 appreciated in electrotherapy. For electric lighting the number 

 of alternations might be increased by transforming the currents 

 into induced currents of a higher order, by Prof. Henry's 

 method, utilized recently by M, Tesla, — Removal of the thyroid 

 in the white rat, by M. H. Cristiani (Geneva). The apparent 

 immunity of the rat from the fatal effects of the removal of the 

 thyroid is shown to be due to the rapid regeneration of this 

 organ. If the extirpation is total, death, otherwise inevitable, 

 can be averted by grafting the organ in the peritoneum, 



CONTENTS. PAGE 



New Contributions to the Biology of Plants. By 



D. H. S 461 



The Geography of Labrador 462 



The Sanitary Institute and its Transactions in 



Review ,, 463 



Our Book Shelf:— 



North : " Gooley's Cyclopaedia of Practical Receipts " 463 



Fabre : " Traite Encyclopedique de Photographic " , 464 

 Letters to the Editor : — 



The Mustakh Exploration. — H. H. Godwin- 

 Austen 464 



Nebular Spectrum of Nova Aurigae. — Ralph Cope- 

 land 464 



Daytime Seeing at the Lick Observatory. — Henry 



Crew 465 



Ridgway on the Humming-birds. — R. W. Shufcldt 465 

 "The Limits of Animal Intelligence." — Dr. St. 



George Mivart, F.R.S • .... 466 



The Theory of the Telephone.— Fred, T, Trouton 466 

 Crater-like Depressions in Glaciers. — R. von 



Lendenfeld 466 



Cholera : Prevention and Vaccination 466 



The Planet Venus, {Illustrated.) By W. J. L. . . . 468 



Notes 471 



Our Astronomical Column: — 



Discovery of a New Satellite to Jupiter 476 



Variation of Latitude 476 



Bright Streaks on the Full Moon . 476 



Nova Aurigse 476 



New Observatories 476 



Solar Observations at Rome 476 



Geographical Notes 476 



International Congress of Physiologists 477 



Electro-Metallurgy. By J. Wilson Swan 478 



Mount Milanji in Nyassaland . 482 



Observations of the Planet Mars. By M, Perrotin . 482 



Scientific Serials 483 



Societies and Academies 484 



NO. I 194, VOL. 46] 



