4o8 



NATURE 



[Feb. 2 1, 1889 



santonate of soda on the perception of colours. As is well 

 known, a distinction is drawn between congenital and acquired 

 anomalies of the colour-sense (colour-blindness) ; of these the 

 first only gives rise to colour-blindness to red or green, while 

 colour-blindness to violet is never observed as a congenital defect. 

 On the other hand, it was supposed that, in the anomalous per- 

 ception of colour which results from the action of santonin or 

 santonate of soda, we had to deal with a typical case of acquired 

 colour-blindness to violet. The speaker had hence been led to 

 make a number of experiments with santonate of soda on himself, 

 and, apart from the fact that as soon as its action is manifest all 

 objects appear of a yellow colour, had established the following 

 phenomena. The spectrum ceases to be visible on the hinder 

 side of the blue, and not a trace of violet is ever visible ; the 

 neutral point, as deduced from closely-agreeing measurements, is 

 situated at wave-length 573 — that is to say, exactly at that point 

 which is complementary to the missing violet. The speaker 

 based upon these observations the conclusion that the visual 

 phenomena which are observed after the administration of 

 santonin are not really of the nature of colour-blindness to violet, 

 but can be completely explained by the assumption that the 

 violet rays are absorbed by those media of the eye which have 

 been affected by the drug. Prof. Preyer was unable to agree with 

 the above conclusion, speaking with the experience of the experi- 

 ments he had himself made with santonate of soda in 1868. The 

 fact that after the administration of the drug the violet part of 

 the spectrum can be seen when it is looked at not directly but 

 indirectly, is opposed to Dr. Konig's views — that is to say, when 

 its image is allowed to fall upon peripheral parts of the retina. 

 Moreover, Prof. Preyer stated that he experienced a distinct 

 sensation of violet when he had taken the drug while his eyes 

 were closed, and then opened them after the action of the drug 

 had become manifest. He believes that the visual phenomena 

 which accompany the action of santonin can only be explained by 

 assuming that it affects the central nervous system, and that this 

 view is supported by the abnormal gustatory, olfactory, and 

 auditory sensations which are simultaneously observed. — The 

 President communicated some instances of the occurrence of real 

 gustatory and olfactory dreams. 



Physical Society, January 25. — Prof, von Helmholtz, Presi- 

 dent, in the chair. — Dr. A. Konig spoke on the dependence of 

 visual acuteness upon the intensity of light when objects are 

 illuminated by spectral colours, his remarks being based upon 

 experiments made by Dr. Uhthoff. Earlier researches have 

 shown that, for red, yellow, and green light, the visual acuteness 

 increases at first very rapidly, then more slowly, and then finally 

 shows scarcely any further change as the intensity of the 

 illumination is increased ; and that the curve of visual acuteness 

 on the abscissae which represent the varying intensity of illu- 

 mination is a parabola, whereas with blue light the curve is a 

 straight line. Dr. Uhthoff had repeated these experiments with 

 spectral colours, taking care that the several lights used were in 

 all cases of equal intensity, a result obtained by altering the 

 width of the slit. The speaker described fully the apparatus he 

 had used, and the series of preliminary experiments he had made, 

 by which he had proved that the narrower the slit is in the 

 screen upon which the spectrum falls, the greater is the acuteness 

 of vision, and that the observations are more trustworthy when 

 a dark mark on a light ground is used as the object whose 

 brightness is to be determined than when a light mark on a 

 dark ground is employed. As regards the apparatus it may be 

 mentioned that the dispersion is produced by a fluid-prism 

 I decimetre in diameter. The result of these experiments, as of 

 former ones, was that the visual acuteness increases with the 

 intensity of light in the blue part of the spectrum. When the 

 visual acuteness is compared in the different spectral colours, the 

 intensity of light being in all cases the same, a curve is obtained 

 with a maximum lying near its centre. When the intensity of 

 the light is less, the curve of acuteness on the abscissae of the 

 spectral colours becomes more pointed, and the maximum 

 moves simultaneously towards the red end. When the intensity 

 of light is the least possible, the maximum for the visual acute- 

 ness coincides with the point of greatest brightness in the 

 spectrum. The above holds good not only for the normal tri- 

 chromatic eye, but also for the dichromatic or red- and green- 

 colour-blind eye. — Prof Kundt exhibited a photograph of the 

 spectrum of cyanogen extending from the line H up to about the 

 line L, which had been sent to him by Prof. Keyser, of Hanover. 

 For size, beauty, and clearness of the several groups of lines, 

 this photograph is scarcely likely to find its equal. 



Amsterdam. 

 Royal Academy of Sciences, January 26. — M. Buys 

 Ballot communicated the results of his observations during the 

 last forty years at the Meteorological Institute at Utrecht, and 

 stated how much temperature, air-pressure, and rain deviated to 

 the right or left from the mean values, and how long this occa- 

 sionally continues on a stretch before compensation comes about. 

 — M. Beyerinck spoke on a method of determining the action of 

 different substances on the growth and on some other vital 

 functions of micro-organisms, and illustrated his assertions by 

 preparations. The method consists in applying small quantities 

 of various substances on gelatine plates, either pure or prepared 

 for the purpose, and infected with yeast or Bacteria of some 

 kind or other, and then watching if the micro-organisms in the 

 centres of diffusion of those substances — whether remaining pure 

 or meeting each other on their way — multiply or not, or if they 

 do so in a greater or less degree. 



BOOKS, PAMPHLETS, and SERIALS RECEIVED. 



Electrical Trades Directory and Hand-book, 1889 (Electrician Ofl5ce).-The 

 Elementary Principles of Electric Lighting, 2nd edition : A. A. C. Swinton 

 (Lockwood). — A Dictionary of Photography : E. J. Wall (Hazell). — A 

 Manual of Cursive Shorthand : H. L. Callendar (Clay).— The Chemical 

 Analysis of Iron : A. A. Blair (Whittaker). — Hourly Readings, 1886, Part i, 

 January to March (Eyre and Spottiswoode). — Greek Geometry from Thales 

 to Euclid : G. J. AUman (Longmans). — Challenger Report, Zoology, vol. 

 xxix. Text, 2 Parts (Eyre and Spottiswoode). — The First Ascent of the 

 Kasa'i : C. S. L. Bateman (Philip]). — Therapeutics ought to become a Science : 

 Dr. W. Sharp (Bell). — Therapeutics can become a Science: Dr. W. Sharp 

 (Bell).— The Great Lake Basins of the St. Lawrence: A. T. Drummond.— 

 La Penetration de la Lumiere dans les Lacs d'Eau Douce: Dr. Forel 

 (Leipzig, Engelmann). — Die Zusammendriickbarkeit des Wasserstoffes: S. von 

 Wioblewski (Wien, Tempsky)— Eskimo of Hudson's Strait: F. F. Payne 

 (Toronto).— The Navajo Tanner : R. W. Shufeldt.— Journal of the Anthro- 

 pological Institute, February (Triibner). — Natural History Transactions of 

 Northumberland, Durham, and Newcastle-upon-Tyne, vol. x. Part i 

 (Williams and Norgate).— Journal of the Royal Microscopical Society, 

 December 1888 to February 1889 (Williams and Norgate). — Rendiconto dell' 

 Accademiadelle Scienze Fisiche e Mathematiche (Sezione della SocietaReale 

 di Napoli) Serie 2a, vol. ii. Fasc. 1° to 12° (Napoli). 



CONTENTS. PAGE 



The Illustrated Optical Manual 385 



General Astronomy 386 



An Index-Cataloguge. By Dr. A. T, Myers .... 387 

 Our Book Shelf:— 



Spencer : ' ' The Anatomy of Megascolides australis 



(the Giant Earthworm of Gippsland) " 387 



Strachey : " Lectures on Geography, delivered before 



the University of Cambridge." — F. Grant Ogilvie 388 

 Hiorns : " A Text-book of Elementary Metallurgy for 



the Use of Students" 388 



Letters to the Editor: — 



Weismann's Theory of Variation. — Prof. J. T. Cun- 

 ningham 388 



Mr. Ho worth on the Variation of Colour in Birds. — 



Prof. Alfred Newton. F.R.S 389 



Currents and Coral Reefs. — Captain David Wilson- 

 Barker, R.N • 389 



The Earthquake in Lancashire. — T. R. H. Clunn . 390 



Can Animals count ?— G. A. Freeman 390 



Weight and Mass.— Prof. A. G. Greenhill, F.R.S. 390 



Detonating Meteor. — W. H. G. Monck 390 



Ice Planed. — R. M. Deeley 391 



Repetition of Hertz's Experiments, and Determina- 

 tion of the Direction of the Vibration of Light. 



{Illustrated.) By Fred. T. Trouton 391 



The School of Forestry at Dehra Doon, India , . . 393 

 The Giant Earthworm of Gippsland. {Illustrated.) . 394 



Notes 395 



Our Astronomical Column : — 



The Multiple Star C Cancri 398 



Astronomical Phenomena for the Week 1889 



February 24— March 2 399 



Geographical Notes . . 399 



Notes on Meteorites. VIII. {Illustrated.) By J. 



Norman Lockyer, F.R.S 400 



The Forces of Electric Oscillations treated accord- 

 ing to Maxwell's Theory. By Dr. H. Hertz . . . 402 



University and Educational Intelligence 404 



Scientific Serials 404 



Societies and Academies 405 



Books, Pamphlets, and Serials Received 408 



