no FROM AN EASY CHAIR 



masses, destined to evaporate completely under the 

 continued remorseless operation of increasing tempera- 

 ture. On the contrary, it appears that, though there 

 are not accurate records and measurements as to past 

 centuries as there will be as to present and future 

 years, yet there is abundant evidence that Alpine 

 glaciers have grown longer in some centuries and re- 

 treated in others. The period of alternate extension 

 and retraction has not been ascertained with accuracy, 

 but by some geologists it is supposed to be about fifty 

 years. The retraction or shrinking is not due to a 

 continuous increase of the temperature of the earth's 

 atmosphere or of this hemisphere but to contending 

 causes which operate alternately towards increase and 

 towards decrease when one or two hundred years are 

 considered. Such are the greater or less rainfall and 

 snowfall over a very large area, and the formation and 

 persistence of clouds, concerned with which are probably 

 those varying quantities the spots on the sun. 



The simple proof that glaciers have extended and 

 again retreated within historic times is furnished by the 

 fact that in some parts of the Alpine range the retreat 

 of a glacier has uncovered ancient miners'* excavations, 

 which must have been worked when the glacier did not 

 reach the spot excavated. Subsequently the glacier 

 advanced, and now after some hundreds of years it has 

 again retreated and exposed the ice-covered borings and 

 workings. The tradition of a glacier-enclosed village 

 in the Zermatt mountains, shut off from the world by 

 the advance of glaciers, lost and mysterious, is evidence 

 that such advance has been observed by the native 

 population. 



The natives who live near glaciers know that they 

 advance and retreat, but the fact that the whole glacier 

 is really a slowly flowing viscous mass a sort of frozen 

 but not immobile river was only established by scientific 

 observation in the last century. The frozen river is fed 



