DRAINAGE OF BOGS. 729 



peat vary in different parts of the bog, it is rare that working 

 plans for a bog take into consideration its reproduction. It is, 

 therefore, considered sufficient to prepare a plan for from 50 to 

 100 years, according to the extent of the bog, the demand for the 

 peat and amount of labour available ; a fixed quantity of peat 

 is thus supplied annually, whilst the cutting proceeds in a 

 proper direction. In the latter respect, it is customary to com- 

 mence operations at the highest part of the bog, if it is intended 

 that the peat shall be reproduced, and thence to proceed gradually 

 to its lower parts. 



Section IV. — Drainage of Bogs. 

 1. General Account. 



Peat can be utilized only after a bog has been partially drained. 

 It is chiefly small bogs resting on a sloping bed which can be 

 worked without draining. Drainage is always necessary in the 

 case of large bogs. The object is not to drain the entire bog, 

 but only that portion which it is intended to work immediately' 

 and to such an extent that the peat may be readily dug and 

 dried. The remainder of the bog should be kept thoroughly 

 wet in all cases where the reproduction of the peat is intended, 

 and also to protect the peat from being frozen * ; this is also 

 frequently useful when the land already freed from peat is to be 

 cultivated. 



All parts of the bog which are not being utilized should be 

 kept thoroughly wet during winter, or the peat will be seriously 

 injured by frost. When wet or damp peat is frozen it does 

 not become compact again on being dried, but crumbles. If 

 the cleared bog is to be planted with trees or converted into 

 meadow-land, it is not advisable to drain the bog completely, but 

 only to remove the superfluous water. 



The method of draining a bog depends essentially on its 

 situation and nature ; one or other of the following methods 

 being adopted : — leading water away in drains, cutting off the 

 water-supply, collecting the water in drains or tanks, or causing 

 the water to sink through an impermeable subsoil. 



* [Cranlieny bogs in N. America are regularly inundated when threatened by 

 frost, in order to protect the plants. — Tii.j 



