WORK ON THE GLACIER. 301 



ance of M. Henri Coulon in the long and 

 laborious excursions required for this part of 

 the work. 



This is not the place for scientific details. 

 For the results of Agassiz's researches on the 

 Alpine glaciers, to which he devoted much of 

 his time and energy during ten years, from 

 1836 to 1846, the reader is referred to his 

 two larger works on this subject, the " Etudes 

 sur les Glaciers," and the " Systeme Glaciaire." 

 Of the work accomplished by him and his 

 companions during these years this slight sum- 

 mary is given by his friend Guyot. 1 " The 

 position of eighteen of the most prominent 

 rocks on the glacier was determined by care- 

 ful triangulation by a skillful engineer, and 

 measured year after year to establish the rate 

 of motion of every part. The differences in 

 the rate of motion in the upper and lower 

 part of the glacier, as well as in different sea- 

 sons of the year, was ascertained ; the amount 

 of the annual melting was computed, and all 

 the phenomena connected with it studied. All 

 the surrounding peaks, the Jungfrau, the 

 Schreckhorn, the Finsteraarhorn, most of them 



1 See Biographical Sketch, published by Professor A. 

 Guyot, under the auspices of the United States National 

 Academy. 



