6o 



BOOK III. 



also are able to signify the intermediate directions by means of the names of 

 the vi'inds. For instance, if a vein runs from VI east to VI west, it is said 

 to proceed from Subsolanus (east wind) to Favonius (west wind) ; but one 

 which proceeds from between V and VI of the east to between V and VI 

 west is said to proceed out of the middle of Carbas and Subsolanus to between 

 Argestes and Favonius ; the remaining directions, and their intermediates 

 are similarly designated. The miner, on account of the natural properties 

 of a magnet, by which the needle points to the south, must fix the instru- 

 ment already described so that east is to the left and west to the right. 



In a similar way to venae profundae, the venae dilatatae vary in their 

 lateral directions, and we are able to understand from the seams in the 

 rocks in which direction they extend into the ground. For if these incline 

 toward the west in depth, the vein is said to extend from east to west ; 

 if on the contrary, they incline toward the east, the vein is said to go from 

 west to east. In the same way, from the rock seams we can determine 

 veins running south and north, or the reverse, and likewise to the 

 subordinate directions and their intermediates. 



A, B — Venae dilatatae. C — Seams in the Rocks. 



Further, as regards the question of direction of a vena profunda, one 

 runs straight from one quarter of the earth to that quarter which is opposite, 

 while another one runs in a curve, in which case it may happen that a vein 

 proceeding from the east does not turn to the quarter opposite, which is the 

 west, but twists itself and turns to the south or the north. 



