594 



N.-l TURE 



[OcTOBKR 17, 1895 



LETTERS TO THE EDITOR. 

 [ Tkt Editor dots not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part or Nature. 

 No notice is taken of anonymous communications. ] 



The University of London. 



I HAVE lx;en away from home, ami have only now seen Mr. 

 Thiselton-Dycr's letter of August 23. 



My previous letters were, I thought, quite clear : but as he 

 asks me to do so, I write to explain that my two statements 

 which he quotes, viz. : (I) " I am not asking that any privilege 

 which they do not at present possess should be conferred upon 

 my constituents, but only supporting what is now their legal 

 right. . . . This right I know they highly value" : and (2) " It 

 is the law at present," had reference to the present right of veto 

 possessed by Convocation. 



As regards the vote being taken as at a senatorial election, so 

 -far from stating that this was at present the law, the very terms 

 «)f my letter implie<l that it was a change. 



Whether it would be "radical" or "revolutionary" is, of 

 ■course, a matter of opinion, but I certainly did not make the 

 suggestion with the object attributed to me ; nor do I share my 

 /fiend's opinion that the graduates would take a course which, 

 to quote his words, " would destroy the prospects of .\cademic 

 stufly in I-ondon." John Libbock. 



High Elms, October 8. 



Sir Robert Ball, and "The Cause of an Ice Age." 



Mr. Tames Geikik has recently brought out another edition 

 of his " Ice Age," a well-known ami influential work. In this 

 book he quotes freely from Sir Robert BalTs " The Cause of an 

 Ice .\ge, which a]>|X?ared in 1891, and which w.is remarkable 

 as the first work written by a professed astronomer in which an 

 astronomical cxplanatiun of an Ice age was put forward and 

 defended. .\s the influence of these l»oks ujwn popular 

 opinion, and even ))erhaps ui»n some scientific men, may prove 

 very misleading and mischievous, |ierhaps you will allow me a 

 little space in which to discuss Sir Robert IJall's work. 



The txjok was preceded by much advertisement, in which we 

 were told not only that it contained an entirely new view of the 

 ■.ubject, but that an astronomical basis of the Ice theory was at 

 last securely established. 



When the book itself was published, it appeared also that the new 

 matter in it consisted of "a law, hithcrtounsvispected, regidating 

 ihe distribution of heat between summer and winter in either hemi- 

 sphere.' Thus on page 113 the author says : " I disccnvrcd \\\ii 

 law of distribution of sun heat on a hemisphere 1>ulween the two 

 seasons into which the year is divided by the e<iuinoxes." Again 

 he says : "/ enumerated and proved \\\a\. law of the distribution 

 ■of sun heat Ixtween the two sea.sons, w hich I have already referred 

 10 as the carilinal fe.itures of this little Imok " (op. cit. 113.) 

 .\gain, in the appendix he says : ' ' The following is the c.tlculalion 

 often referred to in this IxKik, and in which /<!/•///<■ //«/ time, 

 -SO far as I know, the astronomical facts relating to Ice ages have 

 Ijcen correctly given." IjLstly. he Siiys: " If ii should prove 

 that Ihe facts which these numbers imply have not Iwen given by 

 any jirevioiis writer, then their announcement is the novelty in 

 this book, the oiu central feature by which it is to be judged.^'' Sir 

 koliert Ball afterwards s|>caks slightingly of Herschel and Croll 

 for having ignored this law. 



It wxs very soon pointed out in a review of his book that this 

 mrticular law which Sir K. Ball claimed to have discovered had 

 lieen alrca'ly enunciated and published by Wiener. 



This fact might easily have cscapeil any one else but a writer 

 who wa-s himself a mathematician writing expressly on this very 

 (mini, which was the justification of his liook. Let that pass, 

 however. 



It sccm» to some of us that when the Astronomer Royal for 



''•'■■■' ' ■■' '■■■' this pointed out to him, he oupht at once 



'lir scienlific papers correcting his mistake, 



' ihc real discoverer of the law, and that the 



not have Iwen issued .igain without this 



.' in it, for the publication of the supposed 



fftrf of the Ixjok. 



Iiav hap|x:ncd, however, and the only 



>".t 1 V* of the mistake liy its author is in an 



MiitroHomical hooV |niblishcd in 1893, entitled "The Story of the 



J^'o- '355. VOL. 52] 



Sun," in which no reference whatever is made to the claims set 

 up in 1S91, but the law in question is simply referred to as 

 " Wiener's law," as if everybody in the world must know that 

 Wiener and not B.tJ1 had discovered it. Meanwhile, " The 

 Cause of an Ice Age " is not cancelleil or w ithdraw n or corrected, 

 but is being continually issued with all its exploded claims. 



What I have just written refers merely to a claim to have 

 discovered a law which was discovered liy some one else, 

 and to the amenities which generally regtdate our conduct when 

 we are shown in such a case to have done another man an in- 

 justice. But this is a very small matter. A much more im- 

 portant matter remains. 



The law which Sir R. Ball claimed to have discoveretl is an 

 indisputable one. No one doubts it, or could doubt it. What 

 most people who have examined the problem say, however, is 

 not that the law is not a perfectly good one, but that it has 

 nothing whatever to do with the question of an Ice.ige. The law 

 in question is briefly, that the quantity of heat received by either 

 hemisphere of the earth in summer is to that it receives in winter 

 in the ratio of 63 to 37. This is an invari.ible ratio, true at all 

 times, and true under all conditions of eccentricity of the orbit. 

 It never varies. It was the same millions of years ago, so far as 

 we know, as it is now, and so it will remain. It is therefore a 

 constant factor in the problem, and being a constant factor it 

 cannot be the cause of variability of climate. If, as we are told 

 in the book over and over :igain, tliis partiodar proportion is 

 the cause of an Ice age, we must be living in an Ice age now, and 

 we must always have been in an Ice age. Therefore the law in 

 question was not only not new, but it is .an absolutely irrelevant 

 law so far as the problem at issue is concerned. Whether the \xi\- 

 ticular numerical ratio was present to the minds of I lerschel and of 

 Croll when they wrote on the problem, is quite immaterial ; and 

 being so. the whole raison tfi'trc of Sir R. Ball's bovik is gone, and 

 so far as we know there is not a single material factor of the prob- 

 lem discussed by Sir Robert Ball which was not present to Croll 

 when he wrote " Climate and Time " and his other works. 



I^astly. Sir Robert Ball, following in the wake of Croll, 

 has subjectetl the various facts and conditions, both .astronomical 

 and meteorological, which in his view induced an Ice age to 

 analysis, and has reached certain conclusions which he has 

 emphasised in his later work, " The Story of the .Sun." This 

 analysis has been criticised and examined by more than one 

 person, but with especial closeness of reasoning ami conclusive- 

 ness by one of Sir R. Ball's own pupils, a distinguished Kellow 

 of Trinity College, Dublin, Mr. Culverwell. His criticisms have 

 appeared in Nai I'RE ami in the Geological .Magazine. 



In the view of those who have read these criticisms, they are 

 simply crushing. No more complete and acute ilisseclion and 

 destruction of a scienlific argument has appeared for many 

 years. 



This criticism was originally read at the British .\ssociation, in 

 the presence of Sir R. Ball himself, who made no attempt what- 

 ever to answer it, but (mistaking his audience) merely gave vent 

 to some joctdar remarks. The Low ndean I'rolessor at Cambridge 

 cannot turn the flank of serious criticism by ill-timed jokes. 

 Since then he has not. so far as I know, answered his critits in 

 any w.ay, or tried to justify his riddled arguments, and the books 

 in which they are contained are being sold, and their conclusions 

 are being qur)te(l as if they were sound instead of being absolutely 

 untenable. 



If Sir R. Ball were an ordinary ))cr-on, a free lance in 

 literature and science, he might s.iy anything and jiublish anything 

 with impunity, and might refuse to answer criticism Irom any 

 quarter; but he was once -Vstronomer Royal for Ireland. He 

 now fills the chair at Cambridge once occupied liy .\dams. He 

 cannot write without in some way committing that chair and 

 that University by his opinions: and his principal critic is not .an 

 obscure scribbler, but a mathematician as acconi|ilishcd as him- 

 self. Is it right or ilecent that, under these circumstances, he 

 should continue 10 publish, with his name on the title-pages, 

 works such .as those I have desciibcd ? Ought he not either to 

 at once confess his mistakes, to answer his critics; or if he 

 cannot do ihis, to wilhilraw books which have done some harm 

 to thoughtless jieople, which have brought no cre<lil to the chair 

 he fdls, nor to the I'niversity of which he is a I'rofessor ; and 

 which have given rise to a goo<l deal of angry ci>nimenl among 

 those who do not understand a man of science, of real 

 distinction, remaining, for a day limger ihan he can help, the 

 foster-father of what has lx:en shown to be wrong either in fact 

 or in argument ? 



