156 



NATURE 



{Dec, 13, 1888 



daily temperature and sunshine in London and the suburbs. The 

 monthly values published by the Registrar-General are also 

 appended, and the whole forms a valuable record of the 

 meteorological statistics of England and Wales, issued well up 

 to date. 



At the meeting of the French Meteorological Society on 

 November 6, M. Lemoine presented a summary of the rainfall 

 observations of the basin of the Seine in 1887. He stated that 

 the rainfall was everywhere below the average ; in the Depart- 

 ment of the Seine- Inferieure the totals for the year were the 

 lowest in a series of twenty-one years. M. Renou stated that 

 the late M. Herve-Mangon having expressed the wish that his 

 observations made at Ste.-Marie-du-Mont should be published, 

 Mme. Mangon had handed them over to him for publication at 

 her expense. M. Renou presented a note on the temperature 

 of October at Paris since 1757. He pointed out that during the 

 last 130 years the month of October presented either a low or a 

 high mean every twenty or twenty-five years. Means as low as 

 that for October 1887, viz. 44°'i, were very rare. Since 1757 

 the lowest averages for October had occurred in 1784 (45°"3), 

 and 181 7 (45°"i). 



Biologists will be glad to learn that the posthumous works of 

 the late M. Severtsoffare being issued by M. Menzbier, at Moscow, 

 and that a new part has been added this year to the part which ap- 

 peared in 1886. Severtsoff not only was a first-rnte zoologist and 

 explorer of unbeaten tracts in Turkestan ; he was also a powerful 

 thinker, and everything he wrote about the philosophy of zoology 

 deserves attention. Unhappily, his frequent expeditions to 

 Central Asia rendered it impossible for him to bring to an end 

 the works of a general character which he was preparing. He 

 had begun an "Ornithology of Turkestan," based upon his 

 exceedingly rich collection of birds, which contains no less than 

 from 12,000 to 13,000 specimens. This work will be completed 

 by M. Menzbier, and it could not have been put into better 

 hands. As for the two parts of his "Posthumous Works" 

 {Afemoires de la Soc. des Natttr. de Moscon, vol. xv. fascs. 3 and 

 5), they consist of two papers : one in German, on two in- 

 sufficiently known species of Russian hunting hawks {Hierofalco 

 grebnitzky, n. sp., and Hierofalco nralensis, Sev. et Menzbier) ; 

 and the other, in French, on variations due to age of the Palae- 

 arctic Aquilince, and the taxonomic importance of those varia- 

 tions. The former contains, besides the description of the two 

 species (with coloured plates), a sketch of the geographical dis- 

 tribution of the Icelandian, Norwegian, Uralian, and Labradorian 

 s^ec\t% of Hierofalco. The second paper contains, first, a dis- 

 cussion of some principles of zoological classification, being an 

 answer to Dr. Stebohm's reproach of having "too closely 

 followed the steps of the elder Brehm." and of having aimed at 

 " hitting the happy medium between ' lumpers ' and 'splitters.'" 

 This is followed by a discussion of the natural extent of the family 

 of ^(;^/«7?«^ (which, according to Severtsoff. must include only the 

 three genera, Aquila, Haliactos, and Milvus) ; the geographical 

 distribution of all known species of the Aqtiilina: ; and finally, 

 the description of those species which Severtsoff had himself 

 studied closely in the field, — special attention being given to the 

 variations of coloration dependent upon the age of the individuals 

 Seven beautifully coloured plates accompany the work. 



We have received the twelfth volume of the systematic 

 Catalogue of the Museum of Natural History of the Netherlands. 

 The present volume deals with Mammifers, and has been 

 compiled by F. A. Jentink. No fewer than 5379 individuals, 

 representing 900 species of Mammifers, are enumerated in this 

 Catalogue. M. Jentink hopes that his work may be of ser- 

 vice to zoologists by enabling them to see what rare or inter- 

 esting species are to be found in the National Museum, the 



valije of which, in this particular branch, has not hitherto, 

 apparently, been sufficiently appreciated. 



A PAPER on "Energy and Vision," by Prof. S. P. Langley, 

 was read by abstract before the American National Academy of 

 Sciences on April 19 last. This paper was printed in the 

 November number of the A?nerican Journal of Science, and has 

 now been separately issued. The writer does not profess any 

 competence in physiological optics, and points out that his obser- 

 vations, and the conclusions reached from them, are both to be 

 understood from the purely physical point of view. This being 

 premised, he summarizes the paper in the following conclusions : — 

 " The time required for the distinct perception of an excessively 

 faint light is about one half-second. A relatively very long time 

 is, however, needed for the recovery of sensitiveness after ex- 

 posure to a bright light, and the time demanded for this restoratior» 

 of complete visual power appears to be the greatest when the 

 light to be perceived is of a violet colour. The visual effect pro- 

 duced by any given, constant amount of energy varies enor7nously 

 according to the colour of the light in question. It varies consider- 

 ably between eyes which may ordinarily be called normal ones, 

 but an average gives the following proportionate result for seven 

 points in the normal spectrum, whose wave-lengths correspond 

 approximately with those of the ordinary colour divisions, where 

 unity is the amount of energy (about it^Vt ei"g) required to make 

 us see light in the crimson of the spectrum near A, and where 

 the six preceding wave-lengths given correspond approxi- 

 mately to the six colours — violet, blue, green, yellow, orange,, 

 red. 



Colour. Violet. Blue. Green. Yellow. Oranue. Red. Crinis_ 



M M M M M M ^ 



Wave-length "40 -47 -53 -58 '60 '65 ■75 



Luminosity i,fioo 62.000 100,000 28,000 14,000 1200 1 

 (visual effect). 



Since we can recognize colour still deeper than this crimson, it 

 appears that the same amount of energy may produce at least 

 100,000 times the visual effect in one colour of the spectrum that 

 it does in another, and that the vis viva of the waves whose 

 length is 075'', arrested by the ordinary retina, represents work 

 done in giving rise to the sensation of crimson light of 

 O '0000000000003 horse power, or about O'ooi of an erg, 

 while the sensation of green can be produced by o"ooooooo» 

 of an erg." 



A NEW and highly interesting method of obtaining gaseous 

 carbon oxysulphide, COS, perfectly pure and in large quantities, 

 has been discovered by M. Arm and Gautier. The methods of 

 preparing this gas already known are somewhat difficult to- 

 carry out, and the only effectual means of purifying it from the 

 persistent presence of carbon disulphide vapour with which we 

 have been hitherto acquainted, is by utilizing the fact that carbon 

 disulphide is absorbed by triethyl phosphine, a most costly re- 

 agent. M. Gaulier's new method is extremely simple. A large 

 porcelain tube is partially filled with calcined kaolin, the purest- 

 variety of natural silicate of alumina, and heated to whiteness in 

 a good furnace. The air having been first expelled by means of 

 a current of carbon dioxide, a gentle stream of dry carbon dis\il- 

 phide vapour is allowed to slowly pass through the tube. The 

 mixture of gases which issues from the tube is found to consist 

 of a little over 60 per cent, of carbon oxysulphide, and about 

 35 per cent, of carbonic oxide, together with traces of carbon 

 dioxide and sulphuretted hydrogen, and a slight excess of vapour 

 of carbon disulphide. This mixture is now passed (i) through a 

 fla-^k half filled with iced water, in which is deposited the greater 

 portion of the excess of carbon disulphide ; (2) through a wash- 

 bottle containing potash solution, which absorbs carbon dioxide 

 and sulphuretted hydrogen ; (3) through a solution of cuprous 

 chloride in hydrochloric acid, which removes the carbonic oxide ; 

 (4) through an alcoholic 12 per cent, solution of aniline, which 



