Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/36

the south of the west, at a certain point, whence they run together for about fifty fathoms. The united lode is about twelve feet wide, and takes a direction nearly east. The underlay^[1] of these lodes is north; the Great Gossan Lode about two feet, the Muttrell Lode one foot ten inches, and the united lode one foot nine inches, in the fathom. The two lodes are about thirty-seven fathoms apart at fifty fathoms west of the point where they meet; from which place they have been worked, respectively, the Great Gossan Lode about two hundred and thirty fathoms, and the Muttrell Lode seventy fathoms, at the adit level.^[2] They afterwards run on together about forty fathoms in Huel Gorland mine, and further east form a valuable part of the rich and extensive mine called Huel Unity. Huel Gorland is in granite.

In that part of the mine where the two lodes are separate, the adit is fifty fathoms from the surface, but after they have run together some distance, it is only forty fathoms, the descent of the hill being towards the east. The adit being nearer on a level than the surface of the country, it is, therefore, in noticing the depths of different parts of a mine, most correct to date from the adit level, as is the practice of miners. The depths hereafter given are so dated.

In the two lodes, the red oxyd of copper was found under very different circumstances. In the Great Gossan Lode it occurred

1. The generality of the lodes in Cornwall run nearly east and west; their downward direction is not quite perpendicular, but generally more or less to the north on south. This inclination is called the underlay of the lode.
2. It is the first object of a miner, in the working of a mine, to drive a passage or adit from the nearest low ground or valley to meet the shaft, for the purpose of conveying of the water, which is raised to the adit level by the means of the steam engine. It will therefore be obvious that the depth of the adit from the surface of the mine, must depend on the height of the ground in which the mine is, and the depth of the neighbouring valley.