336 Professor Forbes's Fourteenth Letter on Glaciers. 



wholly unconnected with the place or parties where and by whom 

 the observations on the motion of the glaciers were made, and there- 

 fore are free from the remotest suspicion of either in any degree in- 

 fluencing the other. 



Table III. 



Mean Temperatures (by periods) on the Centigrade Scale, observed 

 at Geneva and the Great St Bernard. 



A general comparison of the curves of temperature and those of 

 glacier motion (more particularly on the Glacier des Bois) affords a 

 proof of the justness of the principle laid down by me in 1842, that 

 the motion of the ice " is more rapid in summer than in winter, in 

 hot than in cold weather, and especially more rapid after rain, and 

 less rapid in sudden frosts ;"* the evidence of the connection is plainer 

 by mere inspection than any detail could make it. But I request 

 attention to the apparent anomalies of the curves, as affording a 

 stronger evidence of the fidelity with which the measurements have 



* Fourth Letter on Glaciers, Edinburgh Philosophical Journal, Jan. 1843; 

 and Appendix to Travels, 2d Edit., p. 415. 



