METHODS OF HARVESTING PEAT. 727 



Thus pieces of peat of the ordinary dimensions are cut from 

 several trenches and thoroughly dried, their volumes being cal- 

 culated before and after drying and the difference between them 

 being the amount of shrinkage. This is generally from 30 to 

 50% of the volume of freshly cut peat. 



(d) Finally the loss of peat during extraction must be 

 estimated : this varies in quantity according to the skill of the 

 workmen, the quantity of stumps or stems of imbedded trees 

 and the cohesiveness of the peat ; the better kinds of peat are 

 much more brittle than inferior fibrous peat. 



During frosty weather in winter, the walls of the open peat- 

 trenches frequently crumble considerably ; besides this waste, 

 ridges of peat remaining between the trenches cannot frequently 

 be utilized. Thus a loss of peat occurs, often 25 or 507o of its 

 whole volume. If, however, this otherwise wasted material can 

 be moulded into turves, no loss need accrue. 



2. Quality, 



The quality of the peat is ascertained in the above-mentioned 

 manner, both as regards its efficiency as fuel, and the possibility 

 of thoroughly draining the bog. 



It has already been remarked that the quality of the peat 

 varies in the difierent strata of the bog, the best j^eat being, as a 

 rule, at the base of the bog and the inferior kind at its surface. 

 In order to ascertain the nature of the peat throughout the bog, 

 several experimental trenches are dug : the refuse is set aside 

 and the fibrous peat stacked apart from the black peat, the 

 relative proportion of each kind being calculated ; the muddy 

 peat at the base is then dredged out and each kind analysed. 



As the value of peat depends on the quantity of combustible 

 matter in it, which is greater the less water or ash the peat con- 

 tains, the analysis is chiefly directed to ascertaining the quantity 

 of water and ashes in the peat. The contents of the peat in 

 bituminous substance and uncombined carbon, which is always 

 a test of its value, may be found by extracting them with 

 ether. 



The value of a peat-bog also depends on the possibility of 

 draining it. If a bog can be thoroughlv drained within a vcar 



