164 THE FORMS OF WATER IN 



ice with its motion in glaciers. It is foanded on the 

 observation, made by Mr. Faraday in 1850, that when 

 two pieces of thawing ice are placed together they 

 freeze together at the place of contact. 



413. This fact may not surprise yon ; still it surprised 

 Mr. Faraday and others, and men of very great distinc- 

 tion in science have differed in their interpretation of the 

 fact. The difficulty is to explain where, or how, in ice 

 already thawing the cold is to be found requisite to freeze 

 the film of water between the two touching surfaces. 



41 4. The word Regelation was proposed by Dr. Hooker 

 tc express the freezing together of two pieces of thawing 

 ice observed by Faraday ; and the memoir in which the 

 term was first used was published by Mr. Huxley and 

 Mr. Tyndall in the Philosophical Transactions for 1857. 



415. The fact of regelation, and its application irre- 

 spective of the cause of regelation, may be thus illus- 

 trated : — Saw two slabs from a block of ice, and bring 

 their flat surfaces into contact ; they immediately freeze 

 together. Two plates of ice, laid one upon the other, 

 with flannel round them overnight, are sometimes so 

 firmly frozen in the morning that they will rather break 

 elsewhere than along their surface of junction. If you 

 enter one of the dripping ice-caves of Switzerland, you 

 have only to press for a moment a slab of ice against 

 the roof of the cave to cause it to freeze there and 

 stick to the roof. 



416. Place a number of fragments of ice in a basin of 



