72 Review of the Controversy Regarding the Motion of the Glacier. 



Review of the Present State of the Controversy Regarding the Motion of the 

 Glacier. By Pros'. E. AV. Claypole, B. A., B. Sc. (Lond.), 

 Antioch College, Yellow Springs, Ohio. 



The motion of the Swiss glaciers down their rocky channels had 

 attracted the attention of those who lived in the neighborhood long 

 before it became an subject of study to men of science.Their alternate 

 advance and recession had rendered them, for ages, dangerous ene- 

 mies to the farmer of the upland valleys of Switzerland. 



Sometimes for years they shrunk back into their mountain glens, 

 tempting the villager to undertake the task of removing the huge 

 mounds of snow, and of reclaiming the masses of sterile clay they had 

 left behind them. And again, perhaps in his own life-time, or in that 

 of his son, or grandson, they advanced, and almost before the hus- 

 bandman could reap the profits of his labor, ruthlessly plowed up 

 and swept down before them, crop, and sod, and soil, with the hut of 

 the proprietor, and sometimes the Avhole village to which he belonged. 



When at length awakening science began to ask the cause of this 

 mysterious movement, an easy and obvious answer was found in the 

 natural properties of ice. The glacier slid down the valley. This 

 explanation of the j^henomenon, which is associated with the name of 

 the Swiss naturalist, De Saussure, has maintained its ground for many 

 years, under the name of "the sliding theory of glacial motion," in 

 spite of the manifest difficulty of conceiving how even so slippery a 

 substance as ice could slide down an almost level valley, with a rough 

 or rocky bottom, to which, during some part of the year, at least, it 

 was more or less frozen. In De Saussure's own words — "These fro- 

 zen masses, carried along by the slope of the bed on which they rest, 

 disengaged by the water (arising from their fusion, owing to the natu- 

 ral heat of the earth) from the adhesion which they might otherwise 

 contract to the bottom, sometimes were elevated by the water, must 

 gradually slide and descend along the declivity of the valleys or moun- 

 tain slopes (croupes) which they cover. It is this slow, but continued 

 sliding of the icy masses (glaces), on their inclined bases, which car- 

 ries them down into the lower valleys, and which replenished contin- 

 ually the stock of ice in valleys warm enough to produce large trees 

 and rich harvests."* 



But it can be proven by the principles of mechanics, that a sliding 

 glacier must slide with increasing velocity until it becomes an ava- 

 lanche, and this objection alone may be considered fatal to De Saus- 



* Voyages dans les Alpes, p. 535. 



