BOOK V.

147

not yet pierced between the miners who on opposite sides are digging onthe same vein, or cross-stringers, or two veins which are approaching oneanother.

But I return to our mines. If the surveyor desires to fix the boundariesof the meer within the tunnels or drifts, and mark to them with a sign cut in therock, in the same way that the Bergmeister has marked these boundariesabove ground, he first of all ascertains, by measuring in the mannerwhich I have explained above, which part of the tunnel or drift liesbeneath the surface boundary mark, stretching the cords along the drifts toa point beyond that spot in the rock where he judges the mark should becut. Then, after the same cords have been laid out on the surveyor’s field,he starts from that upper cord at a point which shows the boundary mark,and stretches another cross-cord straight downward according to the sixth

A—Needle of the

INSTRUMENT. B —ITS TONGUE. C, D, E —HOLES IN THE TONGUE.