12 TRANSACTIONS OF ROYAL SCOTTISH ARBORICT7LTTJRAL SOCIETY. 



points are carefully attended to, they constitute frequently the 

 only preservative that the timber requires. The bark should also 

 be removed before being used underground ; and if this be done, 

 there is less liability for the timber to rot, and the decay, -when 

 it sets in, is more easily detected." Creosoting has, he observes, 

 the disadvantage that it renders the timber more inflammable, 

 while it also diminishes its strength. 



The dimensions and rates above given may prove a useful guide 

 on estates where the preparation of pit-wood has not yet been 

 attempted. On properties which are favourably situated, this 

 trade might become very profitable, as, owing to the shortness of 

 the rotation (which, in the case of pines and firs need not exceed 

 thirty -five or forty years), the returns are comparatively early and 

 the risk is proportionally reduced ; while, up to that age, dense 

 crops, even of Scots fir, can be maintained ; and there can be pro- 

 duced, on each acre of ground, a large number of the tall, straight, 

 clean and cylindrical poles, such as will yield the best possible 

 class of timber for use in mines. Props sawn from larger stems 

 of the rough quality grown in open crops of greater age, are not 

 nearly so much liked, on account of the splinters from them which 

 injure the miners' hands. 



Even where the production of pit-wood does not form the main 

 object of management, it is likely that, in many localities, the 

 thinnings made between the ages of about thirty to forty-five 

 years or more, in coniferous woods with a higher rotation, may be 

 profitably disposed of for this purpose; and crops which have 

 been destined to stand for a longer period, but which are found 

 at these ages in an unpromising condition, might, in some casep, 

 be cleared off and sold to the pit- wood merchants. 



When considering the relative merits of the Scots fir and the 

 spruce for use in mines, it should be remembered that, although 

 the wood of the former is moi'e resinous, and consequently more 

 durable than that of the latter, spruce trees grown in dense crops, 

 having narrow annual rings, yield timber of a much more durable 

 quality than is ordinarily raised in open woods ; and that the 

 tendency of the spruce to throw out strong side-branches in youth 

 being much less than that of the Scots fir, clean poles can be more 

 easily grown of the former than of the latter species. At the 

 same time, owing to the shade -bearing properties of the spruce, a 

 considerably larger number of stems of that tree can stand in a 

 healthy condition on an acre of ground than in the case of the 

 light-loving Scots fir. 



