158 THE FORMS OF WATER IN 



a century. But Bordier was at length succeeded by a 

 man of far greater scientific grasp and insight than 

 himself. This was Rendu, a Catholic priest and canon 

 when he wrote, and afterwards Bishop of Annecy. In 

 1841 Rendu laid before the Eoyal Academy of Sciences 

 of Savoy his ' Theory of the Glaciers of Savoy,' a con- 

 tribution for ever memorable in relation to this subject.* 



398. Rendu seized the idea of glacier plasticity with 

 great power and clearness, and followed it resolutely to 

 its consequences. It is not known that he had ever 

 seen the work of Bordier; probably not, as he never 

 mentions it. Let me quote for you some of Rendu's 

 expressions, which, however, fail to give an adequate 

 idea of his insight and precision of thought : — ' Between 

 the Mer de Glace and a river there is a resemblance so 

 complete that it is impossible to find in the glacier a 

 circumstance which does not exist in the river. In 

 currents of water the motion is not uniform either 

 throughout their width or throughout their depth. 

 The friction of the bottom and of the sides, with the 

 action of local hindrances, causes the motion to vary, 

 and only towards the middle of the surface do we 

 obtain the full motion. 5 



399. This reads like a prediction of what has since 

 been established by measurement. Looking at the 

 elacier of Mont Dolent, which resembles a sheaf in 

 form, wide at both ends and narrow in the middle, and 



* ' Memoirs of the Academy,' vol. x. 



