August 10, 1882] 



NATURE 



343 



offer of his proposition deserves to be regarded as a valid one, it 

 will not only avoid the necessity of any more experimental evi- 

 dence than we already posses; of the nature of gravitative action, 

 but it will also afford at the same time a satisfactory confirma- 

 tion of the kind of ethereal explanation of gravitation of which 

 M. Pictet is in search. 



I have been delayed hitherto in publishing my views of the 

 primary character of thermo-dynamical principles by difficulties 

 which at the outset attended their applications to explain the 

 experimental phenomena of conduction and radiation. These 

 difficulties, however, and others naturally incident to the deve- 

 lopment of a new physical conception, I believe that I have 

 satisfactorily mastered and overcome. But I anticipate the needs 

 of much greater expansions in the theory before it will avail as 

 completely as in those important cases, to include and demonstrate 

 properties of specific and latent heats, and of dilatation, and the 

 other thermal phenomena of fusion and evaporation, and of 

 vapour tension, to which M. Pictet has found for his theory such 

 useful applications. 



Taking his departure from an entirely different common 

 principle of thermal actions from that with which I set out, the 

 results of M. Pictet's researches will yet, I believe, accord inti- 

 mately, wherever the two parallel methods have a common 

 meeting-point, with my own deductions. I accordingly enter- 

 tain great hopes of recognising among his examples of con- 

 formity to a common law and method, links and steps of 

 demonstration in a complete theory of the properties of heat, in 

 phases of its action where physical axioms not exactly akin to 

 his own fail to furnish me with sufficient explanations of them ; 

 in the same way that it has afforded me great plea-ure to offer 

 full corroboration of M. Pictet's views, from my own inquiries, 

 at a point where his theoretical hypotheses have proved insuffi- 

 cient to cope with an exceedingly extensive and general provision 

 of kinetic laws, much more comprehensive in its physical rela- 

 tions than those mechanical deportments of which we observe 

 the properties and laws in ponderable matter, when it is not 

 under the more profoundly modifying and affecting influence of 

 the all-energising power and all-pervading agency of heat. 



Collingwood, Hawkhurst, July 29 A. S. Kerschel 



M. Cailletet's Pump for Condensing Gas 



At page 308 of your last number you mention a pump in- 

 vented by M. Cailletet for condensing gases, in which he uses 

 mercury as a fluid piston, in order to fill every interstice of the 

 pomp barrel, and so expel the last atom of gas ; of course, in 

 this case, he would use an ordinary plunger pump, with both the 

 inlet and outlet valves at the top, and the proper quantity of 

 mercury in the barrel, so as to fill it completely in the down- 

 stroke of the plunger or piston. 



It is curious that a similar pump is figured in the first volume 

 of the Mechanics Magazine, 1823, page 232, as invented by 

 Henry Russell ; and I have always understood that a modifica- 

 tion of this was used by David Gordon at the unfortunate " Port- 

 able Oil Gas Co.", to condense gas into the reservoir from 

 which his lamps were filled. The patents are Gordon and 

 Heard, 4391 — 1819, and David Gordon, 4940 — 1S24 ; a com- 

 pany was formed at the time for using his lamps, and was worked 

 for a few years, but the royalties having much exceede I the 

 profits, the Compa iv came to grief. Rout. J. Lecky 



3, Lorton Terrace, Nutting Hill, August 2 



Spectrum of the Light of the Glowworm 



When the suhject of the phosphore-cence of the Lauipyridre 

 came under discus-ion at the meeting of th; Entomological 

 Society of London on February 4, 1SS0 (Pros. Ent. Soc, 1880, 

 p. iii.) Mr. Meldola stated that "Some years ago he had 

 examined the spectrum of the glowworm, and found that it was 

 continuous, being rich in blue and green rays, and comparatively 

 poor in red and yellow." This substantially confirms the obser- 

 vation of Sir John Conroy, although Mr. Meldola gives no 

 measurements. JOHN Sril.LER 



Canonbury, August 5 



White Ants' Nests 

 I observe in Nature, vol. xxvi. p. 72, from line 13 to 35 

 inclusive, some remarks regarding the composition of the inner 

 of the two distinct structures composing an ant hill, and that 



though the composition of the inner parts was chemically the 

 same as wood, it was structureless, and its origin not known or 

 understood. 



I believe it is simply composed of the txerrteH refuse of the 



White ant-hill, part laid open. 



wood on wl.i;h they feed, and formed into sub-spherical com is 

 in which the young are generally found. The walls of the ant 

 hill are of pure clay perforated with passages; towards ;ht; 

 centre there are large chambers in which these combs r.re 



B — Part of clay walling, full of passages. 



constructed, and they are full of passages and small chambers, 

 the walls about I -20th of an inch thick. I send some rough 

 Sketches that may serve to illustrate these, in case they may be 

 worth insertion. 



It is no wonder these combs are structureless and yet of the 



C — Pari, of a comb, fall uf chamber 



same chemical composition as wood. If a box full of papers 

 or books is attacked the results are only too well known to 

 those living in the tropics. 



Asam, June 18 S. E. Teal 



Voice in Lizards 



I have been much surprised to see by the recent letters in 

 Nature that there was any doubt as to the lizard having a 

 voice. I have so often heard and seen a lizard uttering its peculiar 



