1845.] DE SAUSSURE'S THEORY DEFINED. 99 



glissement etait favorise par les eaux au fond de leur lit. C'etait 

 1'opinion de Saussure.*" 



Martins' account : 



" De Saussure, Escher de la Linth, Andre de Luc, attribuent 

 cette progression au poids des glaces et a 1'affaissement produit 

 par la fonte de la face inferieure qui repose sur le sol.f " 



Studer's account : 



" Die bisher fast allgernein herrschende Theorie erklarte die 

 Bewegung der Gletscher aus der Schwere allein. Es soil die 

 Gletschermasse als starrer Korper auf ihrer Felsgrundlage, wie auf 

 einer schiefen Ebene, theils durch ihr eigenes Gewicht theils durch 

 dem Druck der hoheren Eis-und Firnmasse herunter gleiten 

 (Grimer, Ramond, Kuhn, De Saussure, Escher) 4" 



This last testimony of the most exact and most learned of 

 the living Swiss geologists as to the sense in which De Saus- 

 sure's theory has always been understood, is so important that 

 I shall add a translation : " The hitherto generally prevailing 

 theory explains the movement of the glaciers by gravity alone. 

 The glacier masses are considered as rigid bodies, which slide 

 down over their rocky beds partly by their own weight, partly 

 under the pressure of the higher ice and neve." My interpre- 

 tation of the views of De Saussure as regards the rigidity of the 

 glacier ice is thus borne out by an independent authority, for 

 M. Studer's work and my own appeared simultaneously. It is 

 further confirmed by private communication with another 

 eminent Swiss naturalist nearly connected by relationship with 

 De Saussure himself, who is more intimately acquainted with 

 the opinions and writings of his illustrious kinsman than any 

 other person now alive, and who considers that De Saussure's 

 views were confined to the general analogy of the glaciers to 

 solid masses sliding down inclined planes, and that the effects 

 of the inequalities of the channels and forms of the ice-basins 

 were not comprehended in his theory. 



* Etudes sur les Glaciers, p. 152, published 1840. 



f Sur les Glaciers de Spitzberg. Bibliotheque Universelle, 1840, torn, xxviii. 

 p. 166. \ Lehrbuch der pbysikalischen Geographic und Geologic, 1844. 



f [M. Necker-de-Saussure is here referred to.] 



