Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/160

 was known to be traversed by numerous lodes, which might be discovered and worked by such an undertaking, and that while a tunnel should be carried in a direction to cross them all, it might make a navigation practicable from the vicinity of Tavistock and the adjacent mines, to the river Tamar where the produce of the neighbourhood is shipped.

In 1803 an Act of Parliament for cutting a canal from the town of Tavistock to Morwelbam, a quay on the river Tamar, was obtained, and the driving the tunnel was immediately begun.

A canal from the north end of it to the town of Tavistock was soon after cut, by which means a copious stream of water was obtained from the Tavy, which was carried across a valley upon an embankment 50 feet high, and afforded the means of working an overshot water-wheel of immense power, which was required for sinking the requisite shafts on the hill through which the tunnel was to pass.

It is unnecessary here to enter into further detail of the nature of the works, as they may be understood from a collection of reports on the subject, which I have formerly laid on the table of the Society; it is sufficient to remark that this tunnel, which was to pass through hard rock for a length of nearly a mile and three quarters, and for the principal part at a depth of about 130 yards from the surface of the hill, was an undertaking of no small enterprize, and that difficulties of various kinds presented themselves in its progress.

The tunnel, as may be seen by the section, is not yet complete, but the obstacles are all surmounted, and nothing now remains to be done but the simple operation of driving. The draining the deep shaft in the centre of the hill, and the ventilation of the tunnel, having been some time since provided for.