Mr. W. Mathews on Glacier-motion. 415 



Taking, then, for granted that we have here arrived, in part 

 at least, at a solution of the source of nervo-motor power, I look 

 upon the sympathetic nerve, its branches and ganglia, not as a 

 separate or isolated system, but merely as a constituent part of 

 the general nervous system — a part, however, to which is assigned 

 the function of guiding and regulating the movements of invo- 

 luntary muscular fibre, receiving from the common source its 

 nervo-motor power, but moulding it to its own purposes and re- 

 quirements ; while I think it not at all impossible that in the 

 great serous cavities of the body (the peritoneum, pleura, peri- 

 cardium, and in those of the encephalon) we may find an ar- 

 rangement to exist in many respects analogous to Leyden jars. 



These ideas may appear to many crude and imperfect ; but the 

 subject is still being investigated, and in a future Number ad- 

 ditional facts shall be communicated. 



15 Newton Terrace, Glasgow, 

 September 4, 18/1. 



LIII. On Canon Moseley's views upon Glacier -motion. 

 By William Mathews, President of the Alpine Club*. 



THE argument by which Canon Moseley attempts to prove 

 that the descent of glaciers by their weight alone is a 

 mechanical impossibility, as contained in his communication to 

 the Royal Society, read January 7, 1869, may be stated in the 

 following propositions : — 



1. In every transverse section of a glacier every particle of ice 

 is, at the same moment of time, moving over and alongside its 

 neighbours. 



2. The absolute motion of any point in the surface of a glacier 

 is proportional to its distance from the nearest side, and to its 

 height from the bottom of the channel. 



3. This differential motion can only take place by the process 

 which, in mechanics, is known by the name of shear. 



4. The resistance which ice offers to shearing, or its shearing- 

 force, as ascertained by experiment in the shearing-apparatus 

 devised by Canon Moseley, is not less than 75 lbs. per square 

 inch. 



5. But in order that the Mer de Glace may descend by its 

 own weight, at the rate at which Professor Tyndall observed it 

 descending at the Tacul, its shearing-force per square inch can- 

 not be more than 1*3193 lb. 



I propose in the present communication to examine these pro- 

 positions. 



* Communicated by the Author. 



