464 



KNOWLEDGE 



Li.K. 



DR, SIEMENS' SUN THEORY.* 



B\ yi. HiKX. 



' I \) th»t nwst serious otycction presented V.y M. Faye 

 1 agxiust th<' new theory of the conservation of solar 

 ^aergy >'/ Mr. Siemens, another may l)€ added, which is 

 also important This objootion can \«e presented in few 

 words : — 



Then is no agreement at j.resent respecting the real 

 heat ot the sun. Fr. Secchi raised it to millions of degrees. 

 Other physicists, especially in France, lowered it to some 

 twenty tJiousand degrees. According to the magnificent 

 experiments of Mr. Langley (Alleghany) the last-men- 



in any case a minimt 



^Yhat is tlience certain. 



if wo take as our basis the fine labours of our regretted 

 .on/rerr, Henri St. Clair Dcville, on dissociation, is that 

 none of the chemical compounds known to us on earth can 

 exist on the surface of tlie sun. All, even those most 

 stabbom in our laboratories, would be dissociated and 

 reduced to their constituent elements. This, moreover, is 

 what is atlniitt'-d in the actual theory of the sun adopted 

 by M. Faye. 



The natural and direct consequence of this fact is tliat 

 the chemical couipoiiiuls which Mr. Siemens supposes to 

 lie dissociated gradually in space by solar radiation, might 

 well, in returning in the ekuientar)- state under the action 

 of gravity towards the central sun, restore and regenerate 

 the heat ctnployed in di.'?sociating them in space ; but this 

 recombinatioa could only be produced at a consideralile 

 distance from the solar photosphere ; and the compounds 

 thus formed, in falling on the surface of this, would be 

 completely dissociated afresh. This act would, therefore, 

 use up all the heat before developed in the process of com- 

 bination. It follows evidently from this that the return 

 of the elements towards the centre would be of no avail 

 toward.^ tlw conservation, or rather towards the continual 

 reproduction, of the solar temperature. 



It seems to me that Mr. Siemen.s' theory can be sub- 

 jected to another decisive critical test. [What follows is 

 one of tb<' disproofs of Dr. Siemens' theory, which I ha^ e 

 given in my article on " The Sun as a Perpetual Machine, " 

 in the C'lri'hill M'ir/fiziiiy for May or June last; but M. 

 tlim'g mvle of presenting it is neat and effective. — 

 li. A. P.] 



If the solar radiation— let us say the heat, visible or 

 invisible emitted or returned by any star effects in its 

 progress tiie chemical dis-sociation of the hypothetical com- 

 [lounds dis.s<-minated in interstellar space, the intensity of 

 this radiation should necessarily )>c reduced by the actual 

 work done, and all which helps ^in this work is lost to the 

 visibilitj- of the star. 



It foliow.'i, thence, that the brightness of the sun, the 

 stars, the planets, should diminish according to a law 

 ,««/<-.* nujr>; mjnti than that of the inverse square of the 

 distance. I say murh morr rti/nil ; I ought to saj' '■■'- 

 trrm/tltj rny',/1. In fact, from the moment when [we admit 

 thatl the rwombination of the elements at the sun's surface 

 wooM be <^pat>le of restoring the emitted heat, it is evident 

 that all that i-uiittcd heat would in its turn be employed 

 in dtsn>ciati/>g tlie chemi'^1 compounds in space. That the 

 ioin should thus tie continually maintained at its full 

 enerjgr, it would 1»c necessary that the distance at 

 which it is viJiible, far iiide.-d from being illimitable 

 <a% it proVjably is) would be, on the contrary, mode- 

 rat<'. Cor whfirevcr it was still visiVjIe, there would 

 *<r light not enijiloyftl in chemical 'linKOrintion, and, 



• Tra.uUl«4 (by the Editor) from a note oddrcwcd to tlic I'aiis 

 XrwUmf of Seieaoe. 



consequently, tliere would be still a /n.-sible loss defi- 

 nite in amount Nothing in the aspect of the planets 

 and their satellites authorises, it seems to me, the admis- 

 sion that there is any other reduction in tlie brightness of 

 light than that which results from the law of the inverse 

 square of tlie distance from the central orb. We see 

 stars whose light has taken at least three years in reach- 

 ing us ; others whose light has been travelling probably 

 thousands of years. Kono of this light, then, has been 

 employed in chemical dissociation ; none of it can be 

 restored in the way indicatctl liy the theory (otherwise 

 most ingenious*) of Mr. Siemens. 



[The objections thus far formulated do not allcct Mr. 

 Williams's equally ingenious and more original theory : 

 what follows does, 1 think.— R. A. P.] 



May 1 be permitted, in closing this note, to return to the 

 objection foiinulated by M. Faye, and to render it in some 

 sort probable [this, considering what follows, is very good] 

 by a numerical example 1 In an important work which 1 

 am engaged upon, on the " Constitution of Stellar Space," 

 I naturally examine the consequences \\hich the resistance 

 of a gas spread through space would have upon the motions 

 of the planets. 1 extract from this work an example bear- 

 ing on the application of analysis to the motion of our 

 earth. According to Laplace, the diminution or increase 

 which can be ascribed within 3,000 years to the duration 

 of our sidereal year, taking full count of the uncertainty 

 of the observations, would be 90 seconds at the utmost 

 [taking more recent obser\ations and tests of the older 

 observations into account itcan be shown that there certainly 

 has not been a change of one full minute in the length of 

 the year in 3,000 years.— R. A. P. | "Accepting as real a 

 rrdiiriion of this amount, 1 examine what density a gas 

 should have to cause such a reduction, and I show that it 

 would suHice that one kilogramme of matter in the form 

 of vapour should be present in 700,000,000,000 cubic 

 metres, in other words that the density should be 

 0000,000,000,001,43 kg [In our English way of pre- 

 senting this relation we should say that 2 -'0162 13 lb. Av. 

 of vaporous matter would be distributed through 

 24,721,000,700,000 cubic feet, from which (as a standard 

 gallon of water, specific gravity 1, contains 277 '274 cubic 

 inches, and weighs 10 lb. Av.) the careful reader can at 

 once determine the maximum specific gravity of the inter- 

 planetary ether from tlie relation — 



. , 0-22046217x1728 



sp. gr. rcquu-ed = -^_„^2,,0OC,7OO,O0O-^2y7-274 



I lea 



festly not far from 



22040217x1728 



2,472,100,670,000,000,000x277274 

 to work this out, but it will come out mani 



100,000,000,000 X 300,000 

 =•000000000000006 

 wheri' the density of water is 1 ; or roughly about 



•OOOOOOOOOOO.J 

 where the specific gravity of air at 39-2° F., bar. 29-9, is 

 taken as unity. — R. A. P.] We are far, then, it will be seen, 

 from the reduction to a 2,000th, or even to a l,O00,O00tli, 



• M. Ilirn'H little compliment reminds mo of tlio Btory of Cuvier, 

 and the author of tho '" Dictionary of tho Academy " ; -" Yoa UBk 

 mo to K'V' you my opinion of your definition of a crab," ho wrote. 

 " ' A crab i» a nmaH red lish, which walks backwards ; ' it is capital. 

 True, a crab is not a fish, it is not rod, nor necessarily small, and it 

 docs not walk backwards j but in other respects the dodnition is 

 oxccllent." 



