= 
Geology and Natural History. 381 
’ : z 
the appropriate heads in the following chapters, where are given 
merous practical exercises in the subjects of “Mechanics of 
vestigations,” Many a teacher will thank him for an indispensable 
aid in his work, and many a student will derive from it an en- 
1. Results of the Earth’s contraction from Cooling.—On ar, 
172 of this volume I have attributed a principle connected wit 
Xxxi, p. 392), in which he brought out the whole principle in 
the form presented by LeConte (except his adopting Hall’s eh 
of subsidence from the gravity of accumulating sediments), bot 
gt I 
‘ontraction to finish the folding. One of its paragraphs reads as 
“The accumulation of a great thickness of sediment along a 
