BOOK V.
103
divide it obliquely; however, my discourse is now concerned mainly with vena profunda, but most of all with the metallic material which it contains.
![](http://upload.wikimedia.org/wikipedia/commons/thumb/f/f0/Book5-1.jpg/430px-Book5-1.jpg)
Three vertical shafts, of which the first, A, does not reach the tunnel; the second, B, reaches the tunnel; to the third, C, the tunnel has not yet been driven. D—Tunnel.