128 Mr. H. H. Howorth on 



Universelle de Geneve^ for 1845, p. 347, as follows: — M. 

 Agassiz considere le glacier comme forme d'un assemblage 

 de fragments angulaires de glace, entre lesquels circule de 

 I'eau dans laquelle on voit nager les animalcules vivants. 

 Si Ton jette sur le glacier des liquides colories on les voit 

 apparaitre a de grandes distance au fond des crevasses, 

 mais lis ne peuvent p^netrer dans I'interieur des fragments 

 de glace. La quantity cTeau qui gorge le glacier parait 

 itre la cause de son mouvement^ en raison de la pression 

 hydrosiatique qtCelle exerce sur la masse. En eflfet ce mouve- 

 ment devient plus rapide lorsque I'eau abonde, et il se 

 ralentit lorsqu'elle vient a diminuer par une cause quel- 

 conque ; par exemple une chute de neige pendant trois a 

 quatre jours de gelee, ce qui oppose a ce que I'eau arrive a 

 la surface du glacier : pendant ce temps il se vide d'eau 

 comme une eponge pressee." 



As Forbes says, this passage clearly shows that Agassiz 

 had abandoned the dilatation theory, and accepted that 

 according to which a glacier is a compound of ice and water 

 moving under the impulsion of its own hydrostatic pressure, 

 a view which Forbes himself had constantly pressed as 

 explaining the cause of viscosity in glacier ice. As he says : 

 ^' The hydrostatic pressure within the veins and crevices 

 of the glacier itself can only produce motion by a plastic 

 change in the figure of the mass, and the ductility of the 

 glacier on the great scale becomes a corollary from the 

 admission of internal pressure as a cause of motion" {id. 

 XL. 1 54— 157). 



Forbes, meanwhile, continued to press fresh experiments 

 into his favour. M. Person is quoted by him as having shewn 

 and published in the Comptes-Rendus for April 29th, 1850, 

 that ice does not pass abruptly from the solid to the fluid 

 state ; that it begins to soften at a temperature of 2° centi- 

 grade below its thawing point ; that consequently between 

 28-4 and 32° of Fahrenheit, it is actually passing through 



