♦ KNO^VLEDGE ♦ 



[July 31, 1885. 



T/.c ic/.n; i, not re^ponsMc fo) ti 



All Ramttances, Cheques, and F: - 



pavahle to llFsbRS. W\MAN i, So^!>. 



TEE RUDDY ECLIPSLD MCiON. 



still 



[1839]— Referring to Mr Proctor's papers on this snbie 

 fail to nnderstand how the "very own sun" can be a« refracted 

 and all be brought ronnd and above the earth's horizon, and all 

 thus seen from the moon, as shown in his diagram, spots and all, 

 without radiating to the moon his normal amount of luminous and 

 calorific energy, minus, of course, that intercepted by our atmo- 

 sphere. The sun being thus optically removed from behind the 

 earth, there would be no more solid earth shadow throw n upon 

 the moon than upon a terrestrial object when we see the sun 

 just above onr horizon. If Mr. Proctor i- iiL'lit the atcivtfd 

 explanation of lunar eclipse, as due to the sh.n 



nthe; 



.s all w 



ong. 



rt of the 



the earth (from the lunar standpoint) 



My version of the accepted explanation is that given by Sir John 

 Hersctel, wlo (" Outlines of Astronomy," section 424) ascribes the 

 mddy hue of the moon to the twilight glow of our atmosphere, the 

 lowermost strata of which, he says, " impart to all the rays they 

 transmit the ruddy hue of sunset, only of double the depth of 

 tint which we adiiire in our glowing sunsets, by reason of the 

 rays having to traverse twice as great a thickness of atmosphere." 

 I quoted these words, and maintained (I do so still) that, ac- 

 cording to the explanation they expound, the moon should have 

 been excessively ruddy on Oct. 4 last, when " the ruddy hue of 



I see now by Mr. 

 he has come to the same couluubiuu na n 

 Magazine of November, 1844, where 1 said 

 is greedily appropriating the red rays whicl 





lem for colouring itself by intt 

 ■ • n of such 

 vidently v 



relicctii 



it from 



Here M:.. _ .. ..^ ... , , ' ^ ■■ ' 



the accepted theory as expressed by Sir John Herschel, a 



confirming my exposition of one part of the subjcst. 



On page 45, Mr. Proctor asks whether I have ever tried the 

 experiment of heating a tufaneons surface to redness. My reply is 

 that I have witnessed the experiment (of my own and others 

 making) many thousands of times. When engaged as chemist to 

 one of our largest iron works, I had continually before me puddling 

 furnaces, reheating furnaces, steel melting furnaces, regenerative 

 furnaces, &c., the efficiency of every one depending on the remark- 

 able facility with which a tufaceous surface such as that of 

 ganister, fire-clay, "bull-dog," ic, absorbs radijnt heat, becomes 

 red hot, yellow hot, or white hot thereby, and at the same moment, 

 and with corresponding facility, re-radiates this heat on the steel 

 or iron to be fused or welded. 



Every reader of Knowledge has seen the same, on a smaller 

 scale, every time he has turned his eyes towards an ordinary 

 English fireplace lined with fire-clay. The most instructive are 

 those ill-constructed examples where the back is tufaceous and the 

 sides metallic. There, the radiations from the same burning coals 

 make the tufa red hot while the iron remains black. 



As to " the cxcecdinglv rapid radiation " whicl. Mr, Proctor seems 

 to suppose refutes my idea of the heating of the lunar surface, he 

 surely understands that such radiation is the correlative of absorp- 

 tion. The exceedingly rapid radiation proves a corresponding 

 rapidity of absorption, and the active absorption which I claim for 



the tufaceous surface assumes, as a matter of course, the active 



ladiatiou. The law ot "exchanges" — one of the broadest and 



boundcst generalisations of physical science — teaches us that when 



tiMi I idiatiiig biirlirs .»(■ ojpiisid to each other, both absorb and 



1 ' 1 1 t t 1 ♦ tl ' ' I's, tho absorption will vary 



■' 'v, with their respective tern- 



I >ays, " heat will be lost by 



1 flies till thermal equillibrium 



.\s Ml PiMtirMill fnUtn understand the basis of my estima- 

 mation of lunar surface temperature, 1 must surely have failed to 

 nuikc It L'encrallj intelligible, and mil therefore state the numerical 

 (linioitsot the problem, but in doing so will take the figures of 

 tl ' who, like Mr Proctor, dtny the extension of ordinary atmo- 



1 I M matter thioughont sjiace. The temperature of space, 

 hug to these is -273'- C or -45913- Fahr. (I estimate it 

 degrees higher, but this goes against myself, as will 

 1 ip-eiitly seen). Therefore all the difference between this an4 

 (lui terrestrial temperatures (neglecting stellar radiation) is dne 

 to solar radiations. Under a ti epical sun at sea level a spherica) 

 body with a tufaceous surface (represented by the blackened 

 bulb of a thermometer) rises when exposed to the sun to 150° or 

 18U° Fahr , and even higher iu the course of a terrestrial day. 

 (On Saturday last the sunshine thermometer at Greenwich reached 

 155 5°. On Monday, 101 3° ; the highest in the shade, 87°.) 

 Taking the lowest figure, the total heat received is 459-1-150 = 

 GO'J°. According to some authorities our atmosphere arrests one- 

 third of the solar radiations Others estimate double as much. 

 Calling it one-half the absolute temperature of a spherical tufaceous 

 surface if exposed freely to the sun without atmosphere obstruction, 

 as at the moon, would thus be 1218°; or 1218-459 = 759° Fahr., 

 1 e. 159' higher than my oiigmal estimate of GOO". This when only 

 exposed for the period of teirestial daylight. I need not here 

 discuss the question of how much the temperature would be 

 augmented by the greater period of lunar exposure, though I have 

 considered the effect of this, and may find occasion to explain it 

 hcieafter. At picscnt I studiously limit myself to accepted figures, 



1 have httledoubt that mr present heresy concerning the tem- 

 peratuiE of the moon will, iii due course, share the fate of a closely 

 resembling hcresj which I perpetrated about seventeen years ago, 

 and published in " The Fnel of the Sun " — viz., that of concluding 

 on the basis of purely physical data that Jnpiter, Saturn, Uranus, 

 and Xeptune are incandescent gaseous orbs like the sun, and enve- 

 loped in an atmosphere of cloud matter. Mr. Proctor and others 

 have accepted this, as they will presently accept my red-hot 



As regards this same " Fuel of the Sun," 19-20ths of which Mr. 

 Proctor says is out of the pale of science, I may add that in this 

 conclusion he note stands nearly alone arjiong those who havereadit. Sir 

 Charles Lyell, Sir William Grove, Sterry Hunt, and many others 

 have estimated it very differently. Sir Charles Lyell was very earnest 

 concerning it, making his friends promise to read it all througli. 

 He knew, as I knew well enough when I published it, that a book 

 of such pretensions, written by an unofficial theorist, would not be 

 looked at by the average scientific official, who is too -wise (in his 

 own conceit) to be instructed by an outsider. 



An amusing example of this prejudice was afforded by a well- 



■, and c 



who E 



3 by i 



= Kev 



refused to look at the book on account of its " seuEational title." 

 Presently an old forgotten essay, by Sir Isaac Xewton himself, is 

 unearthed by Sterry Hunt, in which my sensational title is used 

 by this great authority, and not only this, but my fundamental 

 heresy — that of the universal diffusion of atmospheric matter — is 

 propounded by Newtcn ; and worse still, the primary idea which 

 the whole of the twenty-twentieths of the book is devoted to 

 working out was prophetically suggested by Sir Isaac Newton as 

 that which should be thus worked out in solving the great mystery 

 of the "solary fuel." 



I thus lose some of my claim for novelty, though none for 

 originality. This loss is more than compensated by such flattering 

 evidence of intellectual sympathy with so great a man, to whom I 

 am thereby impelled to say, as jack Falstaff said to Prince Hal, 

 " I shall think better of myself and thee during my bfe." 



W. Mattieu Williams. 



EVOLUTION. 



[1810]— It is d 



iiake out what "Commentator" really 

 crs, which would almost require a com- 

 mentary written on them to be properly understood, have a strong 

 flavour of mysticism and quite a theological odour. Timeo Danaos ! 

 Overlooking apparent inconsistencies and inaccuracies, the letters 

 appear especially to involve misconceptions as to the nature of 



