THE ARTIFICIAL PRESERVATION OF MINE TIMBERS 



By Dr. Friedrich Moll 

 Abstracted from the German by F. W. Haasis 



According to recent estimates, about a tenth of the timber 

 annually produced in the world is used for mine-timbering. On 

 tlie one hand, the application of wood in mining is extraordi- 

 narily varied, because for many purposes wood forms the only 

 suitable material of construction. On the other hand, the life of 

 wood in the mine is very limited and the yearly demands for the 

 replacing of rotten wood are greater than in any other wood-using 

 industry. 



Opinions differ greatly as to what ought to be included under 

 the term mine timbers (Grubenhols). In the narrower sense, no 

 wood is considered except what is used in the finishing of mines, 

 such as stulls, slabs, caps, points {Spitzen), and lagging planks. 

 In a broader sense, however, there may also be considered as 

 mine timbers all wood that is used in the mines from day to day, 

 such as the wood for props at the starting of shafts, for the shaft- 

 timbering, for sheds, etc. In deciding upon a definition of mine 

 timber, one prevalent notion, especially in the case of private 

 owners of forest land, must be debarred, namely, that waste 

 wood is "mine timber," and that all wood which cannot be used 

 for lumber or telegraph poles is "mine timber." The great re- 

 quirements for safety and economy which are placed on the use 

 of mine timbers permit the employment of only good, sound 

 material. Oak, which formerly was used almost exclusively, to- 

 day has largely disappeared from mines. This followed the 

 realization that so far as strength and warning of failure are 

 concerned, pine is fully as valuable as oak. Moreover, pine, like 

 coniferous woods in general, is very much lighter and easier to 

 work than oak, and the tree has a smooth, symmetrical bole. 

 These advantages, together with its low cost, far outweigh the 

 chief advantage of oak, namely, its greater natural durability. 



The German mining industry used in the year 1912 about 200 

 million cubic feet of mine timbers (1,024 cubic feet in the aver- 

 age per 1,000 tons of coal, and 440 cubic feet per 1,000 tons of 

 ore). 



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