538 THE LIFE OF JAMES D. FORBES. [APPEND. 



first quotation which Professor Tyndall has made from Eendu, 

 and the inferences which he has drawn from it. It embraces, 

 however, the real gist of the matter, and the only other quota- 

 tion to which I must refer need not occupy us long. 



7. Professor TyndaWs Second Extract from JRendu examined. 



Quotation B (Glaciers of the Alps, pp. 305-6). It appears 

 unnecessary to repeat the first portion of Professor Tyndall's 

 second quotation from Rendu, as it merely contains in general 

 terms an assertion of the analogy of the movement of a glacier 

 to a river, the modifications of its velocity and depth depending 

 on the width and slope of the valley. No one who reads the 

 extracts which I have already given from my ' Travels ' will douht 

 that I have given M. Beiidu entire credit for this generally 

 accurate anticipation. I also ascribed due merit to our coun- 

 tryman Captain Basil Hall (whose prior claim is not alluded 

 to by Professor Tyndall) for his sagacious anticipation, ' point- 

 ing to the conception of a semi-fluid glacier.' * I further 

 explicitly stated, that ' the idea of comparing a glacier to a 

 river is anything but new, and I would not be supposed to claim 

 that comparison or analogy as an original one ; ' that ' such 

 analogies had no claim to found a theory ; ' that ' the onus of 

 the proof lay with the theorist.' 2 The latter sentences of Pro- 

 fessor 'Tyiidall's quotation from Eendu, restored to the original 

 French, are as follow : - 



*Ce n'est pas tout, il y a entre le Glacier des Bois et un fleuve une 

 ressemblance tellement complete qu'il est impossible de trouver dans celui-ci 

 une circoiistance qui ne soit pas dans 1'autre. Dans les courants d'cau 

 la vitesse n'est pas uuiforme dans toute la largeur ni dans toute la pro- 

 fondeur ; le frottemcnt du fond, celui des bords, 1' action des obstacles, font 

 varier cette vitesse, qui n'est entiere que vers le milieu de la surface.' 

 KENDU, p. 96. 



The quoted extract terminates abruptly (again with four 

 dots, ....), and there is a manifest incompleteness in the 

 sense. For the introduction, ' Ce n'est pas tout/ shows that 

 the writer is going to explain an additional analogy of the gla- 

 cier to a river. But in the preceding extract it is evident that 

 only the conditions of river motion are noted, and that the 

 analogues of glacier motion, which ought to follow, do not 

 appear. 



On turning up Rendu's TMorie for the context, I found the 

 missing member of the analogy. It is as follows : 



' Or, la seule inspection du glacier suffit pour prouver que la vitesse du 

 milieu est plus grande que celles des rives. La surface entiere est coupee par 



i Trawls, first edition, pp. 3S2, 3S3. 2 Ibid. 



