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very important factor controlling the work of underground waters. 
Again, this same process demands, first the development of a compres- 
sional condition in the limestone, followed later by a period of tensional 
stresses as the rock cools. Accordingly, the compressional phase 
advances like a wave normal into the limestone, followed by a tensional 
phase which tends to produce fissures. This accords with the facts 
observable at limestone contacts. Chap. ix deals with the conditions of 
the formation of ice. 
The handling of the problems in each case is highly mathematical as 
the title of the book would suggest, but the results obtained may be 
somewhat readily applied to many concrete cases in geological science. 
W.. Le 
