124 BOOK V. 



are arranged on two different systems ; for either the square ends of the 

 timbers, which reach from the hangingwall to the f ootwall, are fixed into corres- 

 ponding square holes in the timbers M^hich he along the hanging or footwall, 

 or the upper part of the end of one and the lower part of the end of the other 

 are cut out and one laid on the other. The great weight of these joined 

 timbers is sustained by stout beams placed at intervals, which are deeply set 

 into hitches in the footwall and hangingwall, but are incUned. In order that 

 these joined timbers may remain stationary, wooden wedges or poles cut 

 from trees are driven in between the timbers and the vein and the hanging 

 wall and the footwall ; and the space which remains empty is filled with loose 

 dirt. If the hanging and footwall rock is sometimes hard and sometimes soft, 

 and the vein likewise, solid joined timbers are not used, but timbers are 

 placed at intervals ; and where the rock is soft and the vein crumbling, 

 carpenters put in lagging between them and the wall rocks, and behind these 

 they fill with loose dirt ; by this means they fill up the void. 



When a very deep shaft, whether vertical or inclined, is supported by 

 joined timbers, then, since they are sometimes of bad material and a fall is 

 threatened, for the sake of greater firmness three or four pairs of strong end 

 posts are placed between these, one pair on the hangingwall side, the other 

 on the footwall side. To prevent them from falling out of position and to 

 make them firm and substantial, they are supported by frequent end plates, 

 and in order that these may be more securely fixed they are mortised into 

 the posts. Further, in whatever way the shaft may be timbered, dividers 

 are placed upon the waU plates, and to these is fixed lagging, and this 

 marks off and separates the ladder-way from the remaining part of the shaft. 

 If a vertical shaft is a very deep one, planks are laid upon the timbers by the 

 side of the ladders and fixed on to the timbers, in order that the men who are 

 going up or down may sit or stand upon them and rest when they are tired. 

 To prevent danger to the shovellers from rocks which, after being drawn up 

 from so deep a shaft fall down again, a little above the bottom of the shaft 

 small rough sticks are placed close together on the timbers, in such a way as 

 to cover the whole space of the shaft except the ladder-way. A hole, 

 however, is left in this structure near the footwall, which is kept open so that 

 there may be one opening to the shaft from the bottom, that the buckets 

 full of the materials which have been dug out may be drawn from the 

 shaft through it by machines, and may be returned to the same place again 

 empty ; and so the shovellers and other workmen, as it were hiding beneath 

 this structure, remain perfectly safe in the shaft. 



In mines on one vein there are driven one, two, or sometimes three 

 or more tunnels, always one above the other. If the vein is solid and 

 hard, and likewise the hanging and footwall rock, no part of the tunnel 

 needs support, beyond that which is required at the mouth, because at that 

 spot there is not yet solid rock ; if the vein is soft, and the hanging and 

 footwall rock are likewise soft, the tunnel requires frequent strong timbering, 

 which is provided in the following way. First, two dressed posts are erected 

 and set into the tunnel floor, which is dug out a httle ; these are of medium 



