26o 



NATURE 



\Aug. I, 1872 



forms altogether a most attractive gift-book for an intelli- 

 gent child. 



Aninial Record of Science nnd Indiisliy for 1 87 1 . Edited 

 by Spencer F. Baird, with the assistance of eminent 

 men of science. (New York : Harper and Brothers, 

 1872.) 



The Americans are more fortunate than ourselves in 

 possessing a Year-Book of Science edited by a scientific 

 man whose name is a guarantee for the accuracy and 

 value of its contents. The various items of information 

 are arranged under thirteen heads, viz. (i) Mathematics 

 and Astronomy; (2) Terrestrial Physics and Meteorology ; 

 (3) Electricity, Light, Heat, and Sound ; (4) Chemistry 

 and Metallurgy ; (5) Geology and Mineralogy ; (6) Geo- 

 graphy ; (7) General Natural History and Zoology ; (8) 

 Botany and Horticulture ; (9) Agriculture and Rural 

 Economy; (10) Mechanics and Engineering ; (11) Tech- 

 nology ; (12) Materia Mcdica, Therapeutics, and Hygiene; 

 and (13) — a very small one — Miscellaneous, with a very 

 brief Necrology appended. To each paragraph is added 

 the indispensable reference to the authority. Prof Baird's 

 position as Secretary of the Smithsonian Institution at 

 Washington has given him unusual facility for consulting 

 all the leading magazines, and other scientific publi- 

 cations of Great Britain, France, Germany, Holland, and 

 America, of which he has availed himself to the full. An 

 account of the discoveries made in Italy, Sweden, Russia, 

 and other countries of Europe, some of which are daily 

 rising into more and more importance, has been obtained 

 only second-hand. The whole is prefixed by a general 

 Summary of .Scientific and Industrial Progress for the 

 year 1S71, occupying sixteen pages, wherein the more 

 noteworthy incidents in each department of science are 

 briefly chronicled. The work is the result of great labour; 

 and, as far as we have been able to test it, presents a very 

 fair and accurate record of the progress of science during 

 the year. To those who desire to possess such a record 

 for handy reference, we can confidently recommend Prof 

 Baird's Year-Book as the best and most complete work 

 in the language, and decidedly preferable to anything 

 published in this country. 



LETTERS TO THE EDITOR 



[ The Editor does not hold himself responsible for opinions expressed 

 by his correspondents. No notice is taken of anonymous 

 communications. ] 



Atmospheric Effect 



An atmospheric effect, which is sometimes observed in 

 England, displayed itself here in great beauty yesterday. The 

 western sim had been cut off from iis by an intervening ridge, 

 while the upper atmosphere was still filled with his light. There 

 was a good deal of opalescent haze in the atmosphere, which, had 

 the sun shone upon it uniformly, would have presented a tolerably 

 uniform hue. But besides the haze, small detached clouds floated 

 in the air, and behind each of them was a sheaf of shadow, drawn 

 through the haze. The density of tliese shadows varied with 

 that of the clouds which jiroduced tliem, nor was the density | 

 uniform for all parts of the transverse section of the same shadow. 

 The parallel liars of graduated shade thus produced converged, 

 through an effect of perspective, to a point in the cost, exactly 

 as if the sun were going to rise there. The display of the con- 

 vergent glory was strikingly beautiful. 



The same effect showed itself at Oran during one of the even- 

 ings spent there by the Eclipse Expedition. I have seen it two 

 or three times in England (always, I think, near the coast), the 

 last occasion being in company with Mr. Hirst at Margate. 



Faraday, if I remember aright, has described this effect. There 

 was also, I believe, a question asked regarding it some montlis 

 ago in Nature. This brief account may interest the questioner. 



Bel Alp, July 22 John Tyndall 



Spectrum of Aurora 



In the article on the Aurora Borealis of I-'cIj. 4, a transUticm 

 of which appears in your issue of April 25, Prof. Kespighi men- 

 tions having noticed the green line of tlie aurora when observing 

 the zodiacal light ; also, that Oiis line was visible — more or less 

 defined — from horizon to zenith, in every part of the heavens. 



In 1S67, when Angstrom observed the green line in the spec- 

 trum of the zodiacal light, he .also detected its jiresence in all 

 jjarls of the sky. Froui his own and Angstrom's observations, 

 the Professor demonstrates the identity of the zodiacal light and 

 the aurora. This appears to me, at the least, jiremature. Mad 

 the spectrum appeared only where the zodiacal light was jicrcep- 

 tible to the naked eye, there would have been reason for believ- 

 ing it due to that light ; but, be it noticed, the green line is 

 everywhere seen as bright as in the zodiacal light itself We 

 have only to suppose that in both cases auroral phenomena, im- 

 perceptible to unaided vision, were present, and the spectra seen 

 1-iy Angstrom and Respighi are at once accounted for. 



With all due deference to the great authorities just named, I 

 may state that at Mr. Pockyer's request I have been observing 

 the zodiacal light with a spectroscope since last December, and 

 brilliant as tlie ])henomenon has frequeently been, I have hitherto 

 failed to detect the slightest appearance of bright lines or bands. 

 A faint diffuse — to use Capt. Herschel's nomenclature — spectrum, 

 about as intense as that of a bright portion of the "milky way" 

 is all I have yet obtained. 



The spectroscope used is one of Browning's 5 prism ones. 



G. II. Pringle 



Camp Charmadi, South Canara, June 23 



Kinetic Energy 



If the loss of kinetic energy in water which has flowed from 

 lower to higher latitudes is due to friction, and represents work 

 consumed in overcoming friction, as Mr. CroU maintains, how is 

 the gain of kinetic energy in water which has flowed from higher 

 to lower latitudes to be accounted for ? 



Mr. CroU's answer to this question will be awaited with 

 interest. J. D. Everett 



Belfast, July 27 



Bree on Darwinism 



I AM very much obliged to Mr. Alfred R. Wallace for point- 

 ing out some errors of the press, and some of hasty writing which 

 were not corrected in the proofs, of my work upon the " Fallacies 

 of Darwinism." 



I do not think, however, he has adduced anything which justi- 

 fies his virulent condemnation of a work which he has not 

 ventured to criticise, and I do not, however, write for the purpose 

 of making any complaint. I hope to have the opportunity of 

 answering his remarks upon j.'.iOi.ier occasion. 



My object in writing is, however, to request you will 

 give me the opportunity of pointing out tiiat no blunder 

 which I have made is so great as tnat committed by Mr. 

 Wallace himself, when he states that Darwin's imaginary human 

 ancestor with cocked ears and a tail should have been evolved 

 after tlie incoming of catarrhine monkeys, which creatures, by 

 what I presume some might call anticipatory retrogression of 

 development, have actually been placed by Mr. Darwin in the 

 human pedigree, and separated from their congeners the platyrrhine 

 or new-world monkeys, because they had so far reached the 

 human goal to which they were tending as to lose their tails. 



Also according to Mr. Wallace the cocked-eared creature 

 must have not only re-evolved a tail, but have gone so far back- 

 ward as to lose the human-shaped, and gain the canine-like 

 '■ cocked ear." C. M. Bkee 



Colchester, July 27 



Volcanoes and Earthquakes 



It is generally admitted that an earthquake is due to the 

 passing of a sensible wave through the earth's crust. It has also 

 been observed that the occurrence of earthquakes is generally 

 associated with eruptions from volcanic vents, usually in the 

 neighbourhood, but not unfrequently at considerable distances. 

 Now it is evident — and it has struck all observers — that there 



