Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/134

124 the rod, was followed by him; and the pegs that were inserted in the places his feet had touched proved the circuit he had made. If a vein actually ran in that direction, it is certainly wholly different from that of any known vein. It is almost needless to add, that the discovery of the supposed veins as indicated by the means of the divining rod, was not attempted.

The ancient mode of shoding for tin-veins, consisted in tracing certain stones, of which tin formed a proportion considerable enough to excite attention, and found at or a little below the surface, to the vein from which they had been accidentally detached, so as to have passed in a sort of succession down the side of a hill. Another mode of seeking tin veins is by sinking pits through the superincumbent earth down to the solid rock, and driving a trench from one to another, north and south, so as to meet with every vein in the track through which it passed. This method, which is also esteemed to be very old, is called costeening.

The former of these methods for the discovery of tin veins is now rarely resorted to; but the second, as well as another which differs not much from it, that of working drifts across the country from north to south, is sometimes practised. Many tracts of the mining part of Cornwall are however so amply stored with veins in the direction of East and West, that there is little occasion to employ either of the above mentioned modes of discovery. There are comparatively but few mines which are known to have within their boundary only a single vein; in some there are 5, 6, or even 7. As the driving of an adit home to a vein is one of the first and most important tasks of the miner, he sometimes embraces the opportunity of so doing from a neighbouring valley along a cross course, or North and South vein, and for two reasons; the first, that the expense is less than if he were to drive through the solid