BOOK V. 



125 



thickness, and high enough that their ends, which are cut square, almost 

 touch the top of the tunnel ; then upon them is placed a smaller dressed cap, 

 which is mortised into the heads of the posts ; at the bottom, other small 

 timbers, whose ends are similarly squared, are mortised into the posts. At 

 each interval of one and a half fathoms, one of these sets is erected ; each one 

 of these the miners call a " little doorway," because it opens a certain amount 

 of passage way ; and indeed, when necessity requires it, doors are fixed to the 

 timbers of each little doorway so that it can be closed. Then lagging of 

 planks or of poles is placed upon the caps lengthwise, so as to reach from one 

 set of timbers to another, and is laid along the sides, in case some portion of 

 the body of the mountain may fall, and by its bulk impede passage or crush 

 persons coming in or out. Moreover, to make the timbers remain stationary, 

 wooden pegs are driven between them and the sides of the tunnel. Lastly, 

 if rock or earth are carried out in wheelbarrows, planks joined together are 

 laid upon the sills ; if the rock is hauled out in trucks, then two timbers 

 three-quarters of a foot thick and wide are laid on the sills, and, where they 

 join, these are usually hollowed out so that in the hollow, as in a road, the iron 

 pin of the truck may be pushed along ; indeed, because of this pin in the 

 groove, the truck does not leave the worn track to the left or right. Beneath 

 the sills are the drains through which the water flows away. 



A — Posts. H — Caps. C — Sills. D — Doors. E — Lagging. F — Drains. 



Miners timber drifts in the same way as tunnels. These do not, however, 

 require sill-pieces, or drains ; for the broken rock is not hauled very far, nor does 

 the water have far to flow. If the vein above is metal-bearing, as it sometimes is 



