799 



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 production of the peat is intended, 

 and the peat also protected 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. 



2. Ordinary Drams. 



The usual method of draining is to lead the water from 

 the bog in ordinary open drains. It is then essential that 

 some land near the bog is on a lower level than its bed ; this 

 generally occurs. The levels taken of the bog and the 

 immediately surrounding country show the difference of altitude 

 between the lowest point of the bed of the bog and that of the 

 external land, and the gradient of the line joining these two 



* [Cranberry bo;/.-; in N.America are inundated regularly when threatened by 

 :u order to protect the plants. Tr.] 



