726 DIGGING AND PREI'ARATION OF PEAT. 



1. Qiiaiitittf of Peat. 



The followiii^^ data avc required to estimate the quantity of 

 peat in a bo<,' : the area, depth, amount of shrinkafi^e of the 

 dried peat and the loss of peat during its extraction. 



(a) The area of a hog should be ascertained by surveying it. 



(b) The depth may vary considerably at different points of a 

 bog, which is not unfrequently intersected with one or more 

 layers of sand, loam or trunks of trees. In order to become 

 acquainted with the nature of the bog, it should be divided into 

 a rectangular network, the points of intersection of which 

 may be about 27 yards (25 meters) apart, and are marked 

 by numbered stakes. Three methods can then be followed ; 

 either strong poles are driven down at each numbered point to 

 the bottom of the bog, pits 2 — 3 yards broad are dug or a 

 peat-borer is used. 



Driving poles into bogs may lead to false inferences, if beds of 

 marl or trunks and stumps of trees, &c. are imbedded and 

 prevent the poles from reaching the bottom of the bog. Digging 

 pits is often impracticable owing to the accumulation of water 

 and always involves much labour and expense, but this method 

 affords the best possible insight into the nature of the bog and 

 must be employed to ascertain the quality of the peat. It is 

 best to use the peat-borer, as this generally gives satisfactory 

 results and saves much labour. Since, however, few bogs are 

 level at the surface and their bed is often undulating and 

 irregular, levels should be taken all over the surface of a bog, 

 the levels of the bottom and top of each point of intersection 

 being fixed with reference to a horizontal plane through the 

 highest point in the bog. This levelling will show what is the 

 contour of the bog, a knowledge of which is requisite before its 

 drainage can be undertaken. 



(c) With the help of the above factors, the contents of the 

 peat-bog may be estimated in cubic feet. In order, however, to 

 estimate how much marketable peat there may be, a deduction 

 must be made for shrinkage. For as soon as a bog has been 

 drained, it settles down and shrinks the more, the more thorough 

 the drainage. The amount of shrinkage must be calculated by 

 experiment. 



