Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/156

146 apart from its reasonings and its philosophy, a valuable production. I have not thought it necessary to acknowledge my obligations to it in every particular instance; nor, on the other hand, have I been willing to quote its authority, without verifying it by an appeal to some of my numerous friends among practical miners.

As an appendix, it seemed to me that some account of the veins of certain mines, remarkable either for their peculiarities or some striking geological fact, might therefore be an acceptable addition to the geologist, as well as in corroboration of what has preceded. I have however to express my regret that these relations are imperfect, inasmuch as little is said on the subject of the countries in which these mines lie. For as the information on that head could only be obtained from the practical miner; and as he notices the country merely as respects the ease or difficulty with which his operations are carried forward, or at most no further than regards his three grand distinctions of grouan, killas, and elvan, little or nothing satisfactory could be obtained, on that important part of their history.

Herland and Drannack mines are situated in a hill that rises suddenly on the west for some distance, but which is afterwards nearly on a level for about half a mile, the highest ground being about the center of that vein termed the Manor Old Load, having a gradual fall to the south of the middle mine. The country is schist, but in some places so hard as to require the blast by gun-powder.