6l2 



NA TURE 



[Oct. 25, 1883 



panted by a decided deficiency of the band on the green side, 

 called by Piazzi Smyth "the low sun band." Hence we have 

 less red than usual and more green. This i; due, in part at 

 to the sunlight passing through a more than ordinary 

 dense stratum of aqueous vapour, for we know that the thicker 

 the stratum of vapour the more is the red light absorbed. But 

 this is not all, for we have quite as much vapour without this 

 green colour, but in these cases the sun, I believe, is not seen at 

 all, but we get strip; of green sky which are often seen. The 

 atmosphere then, I believe, contains at present a large amount 

 of vapour existing actually as vapour, and not condensed into 

 clouds ; hence even a great thickness of it is transparent except 

 to those particular rays which aqueous vapour absorbs. The 

 green colour can be seen only at a particular altitude, for only 

 there is the thickne s sufficient to produce the necessary absorp- 

 tion. At higher altitudes the peculiar pale silvery white is 

 exactly what we are to expect. 



Will you allow me to submit to the further consideration of 

 the competent whether this phenomenon, seen at approximately 

 the same time in Southern India, Ceylon, and the West Indies, 

 could be due solely to the presence in the atmosphere of the 

 vapour of water. Is not the air in the.-.e regions normally sur- 

 charged through a considerable period of every year with vapour 

 of water? And yet not only is this an unusual appearance, but 

 it has excited, wherever observed, both wonder and some alarm. 

 In one respect the observation from Ceylon (Nature, vol. 

 xxviii. p. 597) is the most noticeable we have had yet, inasmuch 

 as, even when the sun had attained "the very zenith," his light 

 is said to have continued blue. My doubt is whether a pheno- 

 menon so rare could be due solely to a cause so everywhere 

 common. Henry Cecil 



Bregner, Bournemouth, October 22 



P.S. — When Mr. Lockyer saw his green sun through the 

 steam on the boat, were there not also mingling with the vapour 

 sulphurous fumes from the funnel ? 



[The sun has been seen green through mist on the Simpl )U. 

 —ED.] 



Snake Poison 



Touching the effect of Crotalus venom on vegetable life, I 

 am anxious to repair an error which appears on p. 552 of my 

 work on "Snakes," where Dr. Mitchell is made to affirm that 

 some healthy vegetables inoculated with the poison were 

 "withered and dead next day, as if scathed by lightning." In 

 some notes which I made many years ago on a too cur.vory 

 reading of Dr. Mitchell's paper, 1 I omitted the inverted commas, 

 which denote that the experi tuent was tried by Dr. Gillman of 

 St. Louis, in 1854, but which Dr. Mitchell thought was too 

 limited and wanting in detail to be of scientific value. I had 

 overlooked Dr. Mitchell's comments and his own experiments 

 on vegetable life, by which he was driven to the conclusion that 

 the plants were injured by mechanical wounds, and not by the 

 venom inserted into them. When writing my chapter under 

 pressure of time long afterwards, I trusted too confidently to those 

 careless notes, and to an impression gained through the old 

 Virginia writers that venom is injurious to vegetable life. 



But in a most interesting series of experiments twenty-five 

 years ago Dr. Weir Mitchell found that the venom did not inter- 

 fere, nor did it arrest alcoholic fermentation and its accompanying 

 growth of sporules. To test it on the higher vegetable life he 

 wounded plants in various parts of their stem and in various 

 ways, taking three or four plants of similar size and growth — 

 geraniums, tradescantia, and others — both succulent and of 

 woody fibre, inserting venom into some and not into the others 

 which were identical in character, and carefully noting the effects 

 on each, which, for the most part, were similar in the inoculated 

 and the merely wounded plants, the symptoms being such as were 

 produced from the injury to the tissue, the leaf, or stem, as might 

 be. " In many successive efforts to poison other plants with 

 venom," says Dr. Mitchell in summing up the results, " 1 1 failed 

 in every instance." 



A more careful perusal of Dr. S. W. Mitchell's paper now 

 enables me to offer this explanation of the misrepresentation of 



1 "On the Venom of the Rattlesnake." by Dr. S. Weir Mitchell, 

 •■Smithsonian Contributions to Knowledge." vol. xii. i860. Washington, 

 DC, United Stales.) 



those exceedingly interesting experiments, fully detailed in 

 vol. xii. of the "Smithsonian Contributions." 



Cleveland, Ohio " Catherine C. Hopley 



Simultaneous Affections of the Barometer 



My thanks are due to Dr. Balfour Stewart for his kindly 

 pointing out that simultaneous movements of the barometer, like 

 those I hid described in my paper of January last, and also in 

 the " Brief Sketch of the Meteorology of the Bombay Presi- 

 dency in 18S1," written in August, 1882, were first observed by 

 the late John Allan Broun. Owing to my connection with 

 meteorological work being short — of only fourteen months' 

 duration — my attention had not before been drawn to this fact. 

 It is to me interesting to learn also that the late John Allan 

 Broun considered that there was a connection between these 

 movements and the earth's magnetism. 



The Proceedings of the Manchester Literary and Philosophical 

 Society for the last few years do not appear to have been received 

 in Bombay, but they have now been applied for. 



A. N. Pearson 



Meteorological Office, Bombay, September 14 



Table of Different Velocities 



In reading over the interesting table of velocities drawn up 

 by Mr. James Jackson, and published in Nature to-day (p. 604), 

 there is one item omitted, which the author may like to add to 

 his list, viz. the rate at which detonation travel-, as exemplified 

 by a train of compressed gun-cotton. This has been computed 

 by Abel and Njbel to be between 17,000 and 19,000 feet per 

 second, or rather more than 200 miles in a minute. In Mr. 

 Jackson's table, therefore, the detonation of gun-cotton would 

 come in somewhere between the velocity of sound in water and 

 the velocity of electricity. H. Baden Pritchard 



Woolwich, October 18 



OSWALD HEER 



\X7'E briefly announced last week the death, on Sep- 

 * " tember 27, at Lausanne, of Dr. Oswald Heer, Pro- 

 fessor of Botany in the University of Zurich, aged 

 seventy-four years and twenty-seven days. He was born 

 at Nieder Uzwyl, Glarus, Switzerland, August 31, 1809. 

 His whole mind seems to have been imbued from an 

 early age with an intense love of nature, and his devotion 

 to it led him to prefer its study to the discipline of the 

 Church, which he had entered. Heer's early reputation 

 was made as an entomologist, and from 1834 forwards he 

 published many works and papers ©n entomology, chiefly 

 on Swiss insects, and more especially on Coleoptera, most 

 of which treated exhaustively on the vertical distribution 

 of species in the Alps. Possibly he is best known (as an 

 entomologist) in this country by his monographic work on 

 the beetles of Switzerland, which appeared in 1838-41. 

 In this work he did for the Coleoptera of that country 

 what Frey has more recently done for the Lepidoptera, 

 but, of course, lapse of time has rendered Heer's labours 

 out of date as compared with Frey's. This monograph 

 appeared in two forms, but that which is best known was 

 styled " Fauna Coleopterorum Helvetica," and extended to 

 over 600 pages. But his attention was soon attracted, per- 

 haps by some fortunate chance, towards the remains of 

 plants which were being disinterred from the Tertiaries 

 to the north of Lausanne and elsewhere on the Lake of 

 Geneva, and his whole energy became absorbed in un- 

 ravelling and restoring the vegetation of the past, and 

 continued so until the close of a laborious life. In 1855 

 appeared the sumptuous " Tertiary Flora of Switzerland," 

 a work which at once placed him in the first rank as a 

 specialist ; and being a prolific and imaginative writer, 

 untiring industry, he has since contributed to palae- 

 ontology a nearly uninterrupted series of works on his 

 favourite subjects, terminating but last year with the sixth 

 volume of the " Flora Fossilis Arctica." Few earnest 

 workers have lived to see their work more highly appre- 

 ciated, and the gratification he must have felt at the sub- 



