﻿THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



FEBRUARY 1871. 



XIII. On the Cause of the Motion of Glaciers. 

 By John Ball, F.R.S.* 



HAVING been absent from England, I have but lately seen 

 the interesting paper by Mr. James Croll in the last vo- 

 lume of this Journal, wherein, continuing the discussion respect- 

 ing the theory of glacier-motion put forth by the Rev. H.'Moseley, 

 he has done me the honour of replying to the remarks made by 

 me on the same subject in July last, and at the same time has 

 developed rather more fully the views previously published by 

 himself, which may for brevity be designated the molecular theory 

 of glacier- motion. 



I must, in the first place, confess that, in the few pages pub- 

 lished in this Journal for last July, I gave a very incomplete 

 statement of my own opinions in regard to the cause of the mo- 

 tion of glaciers. My object was to state very briefly what 

 seemed to me insurmountable objections to the arguments used 

 by Mr. Moseley ; and even in this respect I fear that I have failed 

 to express myself with the requisite fulness and precision. I 

 now beg permission partially to supply the deficiency, and at the 

 same time to explain why I think it unnecessary to supplement 

 the received theory of glacier-motion by a hypothetical assump- 

 tion as to the molecular condition of the ice in a moving glacier, 

 and to what extent I think that theory does require modification. 



I am happy to find myself in full agreement with Mr. Croll 

 respecting the so-called t{ crawling w theory of Mr. Moseley, of 

 which no defender has been found amongst men familiar with the 



* Communicated by the Author. 

 Phil. Mag. S. 4 Vol. 41. No. 271. Feb. 1871. G 



