August 29, 1895] 



NATURE 



415 



How was Wallace led to the Discovery of Natural 

 Selection ? 



TiiK reviewer of Osborn's " From the Greeks to Darwin" 

 (antca p. 362) saj's that Marshall quotes the fact of Wallace's 

 Ijeing led " to the discovery of natural selection as he lay ill of 

 intermittent fever at Ternalc," and refers one to the abridi;ed 

 lurm of the "Life and Letters of Charles Darwin" for this 

 statement. Having only the original edition in three volumes, 

 from the year 1887, at my disposal, wherein I cannot find it, I 

 would draw attention to my having published the fact as far 

 back as 1870 ("Charles Darwin and Alfred Russel Wallace. 

 Ihre ersten Publicationen iiber die Entstehung der Arten, nebst 

 einer Skizze ihres Lebens und einem Verzeichniss ihrer Schriften. " 

 Eriangen, E. Besold, Svo, pp. xxiii. and 56, on page xviii. ) 

 The remarks to be found there are based upon a letter of .Mr. 

 Wallace's dated November 22, 1869, and now before me, a 

 passage of which runs thus : — 



"The paper No. 9 ['on the law which has regulated the 

 introduction of new specie;,' -A.N.H. 1855] should be read 

 niong with No. 19 ['on the tendency of varieties to depart 

 indefinitely from the original type" P.L.S. 1858]. When I 

 wrote it I was firndy convinced of the derivative origin of 

 species, but had not arrived at an idea of the process. When I 

 wrote No. 19 at Ternate [in the year 1858] I did not [know] 

 «hat were Mr. Darwin's views or the nature of the work he 

 was engaged on, except generally that it was on ' Variation.' 

 I hit upon the idea of ' NaUiral Selection' (though I did not 

 give it that name) while shivering under the cold fit of ague, 

 and I was led to it by .Malthus' views on population applied to 

 animals. As soon as my ague fit was over I sat down, wrote out 

 the article, copied it, and sent it off by the next post to Mr. 

 [ )arwin. It was printed « ithout my knowledge, and of course 

 « ithout any correction of proofs. I should, of course, like this 

 fact to be stated." 



This I did in my pamjihlet of 1870 on the page quoted, and 

 '>n page 39, and I hope Dr. Wallace will forgive me for now 

 making known the whole of his highly interesting statement 

 /// his tnvn words. Of course I am not sure whether he 

 did not tell or write the same to some one else, though I am 

 not aware that it has been published. 



Ordinary mortals dream nonsense in their fits of fever, a 

 jihilosopher of Dr. Wallace's standing conceives original ideas ! 



A. B. .Mever. 



Zoological Museum, Dresden, August 19. 



The letter to Prof. Newton, published in the abridged 

 ■' Life of Darwin," was written in 1887. I had entirely for- 

 ^iitten lliat I had written on the same .subject to Dr. Meyer in 

 iS6g, or that he had published anything in reference to it. That 

 letter probably contained my earlie.st statement on the subject, 

 ind it agrees substantially with my later statements. — A. R. 

 Wallace. 



A Problem in Thermodynamics. 



Siemens taught us how, by using the heat of the gases escap- 

 ing from a furnace to heat the gas and air before entering the 

 kirnace, we could obtain tem[>eratures limited only by the fire- 

 resisting quality of the materials of which the furnace is con- 

 structed. Now, it occurred to me whether on the same 

 principle very low temperatures might not be reached. My 

 idea is this : If com]>ressed air is expanded to atmospheric 

 pressure, the gas does work in overcoming the resistance of the 

 .itmosphere, and is cooled to a corresponding amount. 



Suppose, for instance, the gas is compressed to I /too of its 

 volume, then I cubic metre would perform, in expanding against 

 I he atmospheric pressure of i kil. per i square centimetre, or 

 10,000 kilos per square metre, an amount of work ecjual to 



10,000 xo'99 = 9900 kilgr. -metres, and absorb ^^ - units of heat. 



'*^4 

 Now, I cubic metre of air weighs I "24 kil., and, having a 

 specific heat of 024, the temperature of the expanded air would 

 be lower 78° than before expanding. 



Now suppose A is a tube of a material impervious to heat — 

 that is, a perfect nonconductor — and B a tube made of a perfect 

 conductor of heat ; the tube .\ being closed at one end, and B 

 having a small opening in the end. 



Now, if a continuous supply of compressed air is kept up in 



NO. 1348, VOL. 52] 



tube B, this air will come down in temjierature, and, passing 

 along between A and B, cools the compressed air before it 

 expands. 



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V///y//y///////yyy^/y/y////y'y//w^'A^w/■■v/W/W.^777r'■, 



I should be glad if any of your readers could give me the 

 theoretical minimum of temperature produced at C. 



Essen-Ruhr, Germany. E. Blass. 



A Remarkable Flight of Birds. 



On September 30, 1894, about 3 p.m., I was observing the 

 sun through an 8-inch telescope. I noticed some dark figures 

 of birds passing, like shadows, across the sun. I was using a 

 dark glass, and the birds were, consequently, only visible when 

 seen against the bright solar disc. The silhouettes of the birds 

 were very sharply and clearly cut. Every few seconds a bird 

 would emerge from the darkness, pass slowly across the sun and 

 disappear on the other side. I watched them for over ten 

 minutes without any decrease in their numbers. The whole 

 number of birds must have been enormous, otherwise it would 

 have been impossible for some of them to have passed as 

 frequently as they did between my telescope and the sun. The 

 birds were flying in a southerly direction, and were quite invisible 

 to the naked eye. I was, therefore, unable to determine their 

 distance, but should think they must have been two or three 

 miles away, for the telescope was in focus for the birds and sun 

 at the same time. I do not know what birds they were. 

 Comparing the spread of tlieir wings with the solar -disc, I should 

 say their wings subtended an angle of about two minutes. The 

 place from which I observed them was Shere, a village between 

 Guildford and Dorking. I am told that such a flight of birds 

 has not before been recorded in this country, and have been 

 urged to publish an account in the hope that other astronomers, 

 H ho may have seen a similar thing, may be led to mention the fact. 



Shere, Guildford. R. A. Bray. 



THE IPSWICH MEETING OF THE BRITISH 

 ASSOCIATION. 



IN our last article we gave a general outline of the 

 local arrangements for the' Meeting. The programme, 

 as a whole, is now fairly complete. .A slight alteration 

 has been made with reference to the soirees ; the first 

 will be given by the Ipswich Scientific Society and the 

 Suffolk Institute of .Architologj' jointly, and the second 

 by the Mayor of Ipswich (Mr. J. H. Bartlet,). The 

 fitting up of the Section Rooms is proceeding rapidly, 

 and arrangements are being made for the darkening 

 of those in which a lantern will be used. In the case 

 of Sections .V and B, which meet in the same building, 

 only the room allotted to Section B will be fitted up with 

 dark blinds and a lantern screen, and the Sections will 

 be asked to exchange rooins on days when papers re- 

 quiring lantern illustration arc read in Section A. The 

 same arrangement will be made as to Sections D and 

 K, which meet in the two rooms at the Masonic Hall. 

 For the President's address in these Sections, the Lyceum 

 Theatre, which is a short distance off, will be placed at 

 the disposal of the Sectional Committees, as the Masonic 

 Hall rooms may be hardly large enough to contain all 

 those who would probably wish to be present on these 

 particular occasions. For a similar reason, Section G, 

 which meets in the Co-operative Hall, will be asked to 

 allow the President's addresses in Sections .Aand-B to 

 be delivered there. A spacious room adjoining the main 



