T H E 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



JANUARY 1845. 



I. On the Motion of Glaciers^ 

 By W. Hopkins, Esq., M.A., F.Ii.S., 4-c. 



To the Editors of the Philosophical Maga:tine and Jmirnal. 

 Gentlemen, 

 ^I'^HE interest which the phaanomena of glaciers has recently 

 JL excited induces me to offer for insertion in your Journal, 

 a somewhat detailed discussion of the causes of glacial motion. 

 In doing this I shall confine myself to the sliding theory^ 

 with which we usually associate the name of De Saussure, and 

 to that which has recently been propounded by Prof. Forbes, 

 and which attributes the motion of glaciers to the viscosity of 

 glacial ice. I shall omit all consideration of those theories 

 which refer the motion in question to the freezing and conse- 

 quent expansion of water contained within the mass of the 

 glacier, because I believe there are at present in this country 

 tew persons who have sufficient confidence in those theories to 

 feel much interest in the discussion of them. 



Prof. Forbes's theory has been some time before the public 

 in his excellent work on the Alpine regions, and in various 

 letters addressed to Prof. Jameson and others; and in the 

 Transactions of the Philosophical Society of Cambridge there 

 are two memoirs of mine, the object of which is to explain the 

 nature and causes of the motion of glaciers according to the 

 sliding theory. In my present communication I propose to 

 embody the more important parts of these memoirs, and to 

 add to them some further investigations, which render the ana- 

 lysis of the problem more complete. I shall also offer some 

 critical remarks on the theoretical views of Prof. Forbes. In 

 certain stages in the progress of any branch of science the dis- 

 cussions connected with it will necessarily assume more or less 

 of a controversial cliaracter. Such is the case in glacial theo- 

 ries at the present time. In the memoirs, however, just re- 



Phil. Mag. S. 3. Vol. 26. No. 170. Jan. 1845. B 



