384 SYLVA AMERICANA. 



medium quality, the age of ten or twelve years may be attained 

 by the young trees before thinning is necessary; but should 

 fifteen years elapse before the trees demand thinning, it will be 

 found that the plantation has been imperfectly formed. 



No certain rule can be given to determine the number of trees 

 to be thinned out periodically, which will apply to all plantations 

 and to every kind of forest tree in them. A well-grounded 

 knowledge of the principles of vegetable physiology, and of the 

 habits of trees, is absolutely essential, to execute with success this 

 very important branch of arboriculture. 



The proper season for cutting down timber trees is that in 

 which the sap is most quiescent, viz., midwinter and midsummer; 

 but particularly the former. Trees whose bark is valuable 

 require to be felled before the complete expansion of the leaf. 

 From the last of April to the end of June is the proper time 

 for the oak ; the larch should be peeled ealier. The birch 

 having a tough outer cuticle of no use to the tanner, and as this 

 is more easily separated from the proper bark after the sap has 

 partially circulated in the leaves, it is generally left standing until 

 the other species of trees are felled and barked. 



The process of barking is, in general, well understood. The 

 harvesting of the bark is of the greatest importance, for if it be 

 suffered to heat or ferment, it loses its color, becomes mouldy 

 and of little value. The best mode is to make what the foresters 

 term temporary lofts of about two feet in width, and of a length 

 sufficient to hold a day's peeling of bark. These lofts are formed 

 by driving forked stakes into the ground for bearers, about three 

 feet in height in the back row, and two and a half feet in the 

 front ; a sloping floor is then constructed by laying loppings 

 between the forks of the bearers. The bark is then placed on 

 the sloping floor with the thick ends towards the top or higher 

 side, the smaller bark is laid on to the depth of six or ten inches, 

 and the broad pieces placed over the whole as a covering to 

 carry off the wet, should rain happen before the bark is sufficiently 

 dry to be stacked. In three or four days it should be turned to 

 prevent heating or moulding, and in ten days, more or less, it 

 will be sufficiently dry to be stacked until wanted for the tanner. 



