126 Mr. H. H. HowoRTH on 



Saussure called glaciers of the second order, and he 

 especially experimented on a small glacier perched on a 

 kind of niche, in the northern face of the SchonhOrn, about 

 an hour's steep climb above the hospice of the Simplon. 

 These experiments proved that the conclusions as to 

 plasticity drawn from the larger glaciers were amply borne 

 out by the smaller ones, the only difference being that 

 the amount of movement is correspondingly smaller 

 {Phil. Trans. 1846). 



The first person to scientifically estimate the rate of 

 motion of glaciers was Hugi, on the Aar Glacier, between 

 1827 and 1836. He shewed that where the measurements 

 were made, the rate of movement was about 2, i; id feet per 

 annum. Forbes's own measurements were eventually sup- 

 plemented by those of his Swiss assistant, Balmat, who, in 

 1844 and 1845, finally put to rest the question as to the 

 movement taking place both in winter and summer. Four 

 posts were inserted in four different positions, with the 

 following result : — 



1234 

 Motion for 365 days, Nov., 1844, ^^^*' 



to Nov. 1845 847-5 220-8 657-8 489-1 



Inches. 



Mean daily motion 27*8 7-3 21-6 i6-i 



Mean daily motion, summer 



period, April to October... 37-7 9*9 28*0 22-2 

 Mean daily motion, winter 



period, October to April... 19-1 47 ^^'^ i°'7 



Ratio summer to winter motion 2-0-12-1-7 1-8 -i 2'i - i 



Forbes says justly that these figures, compared with the 

 records of temperature as observed, confirm his conclusions 

 of 1842, that the movement of the ice is more rapid in 

 summer than in winter, in hot than in cold weather,, 

 and especially more rapid after rain and less rapid in sudden 

 frosts ; and he further urges that the velocity of a glacier is- 

 largely dependent upon the completeness of its infiltration. 



