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CHAPTER III. 



GLACIAL MOTION. 



That glacial ice actually moves after the analogy of a 

 semi-fluid has been abundantly demonstrated by observa- 

 tion. In the year 1827 Professor Hugi, of Soleure, built 

 a hut far up upon the Aar Glacier in Switzerland, in 

 order to determine the rate of its motion. After three 

 years he found that it had moved 330 feet; after nine 

 years, 2,354 feet ; and after fourteen 

 years Louis Agassiz found that its 

 motion had been 4,712 feet. In 1841 

 Agassiz began a more accurate series 

 of observation upon the same glacier. 

 Boring holes in the ice, he set across 

 it a row of stakes which, on visiting 

 in 1842, he found to be no longer in 

 a straight line. All had moved down- 

 wards with varying velocity, those 

 near the centre having moved farther than the others. 

 The displacements of the stakes were in order, from side 

 to side, as follows : 160 feet, 225 feet, 269 feet, 245 feet, 

 210 feet, and 125 feet. Agassiz followed up his observa- 

 tions for six years, and in 1847 published the results in 

 his celebrated work System Glaciere. 



But in August, 1841, the distinguished Swiss investi- 

 gator had invited Professor J. D. Forbes, of Edinburgh, to 

 interest himself in solving the problem of glacial motion. 

 In response to this request, Professor Forbes spent three 

 weeks with Agassiz upon the Aar Glacier. Stimulated 



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Fig. 16. 



