There are now at Hayle two very extensive Iron Founderies, in which are cast the largest engines which have been hitherto erected on mines. They are wrought partly by water, and partly by Steam Engines. Near the Copper House the traveller will not fail to notice the fine back-water dam, which was constructed about thirty years since, for the scouring out of the harbour. The effect has been a considerable reduction of the sand which forms its bottom, so that ships of much greater burden may now enter it. The plan and execution of this work, which was undertaken at the expense of the then existing Hayle Copper Company, reflect great credit on the late _John Edwards, Esq._, who first conceived its practicability and advantage, and under whose direction it was completed. A phenomenon occurred at these works some years ago which afforded a curious illustration of the secret and destroying agency of Galvanic electricity. The flood gates were found to undergo a very rapid decay, which was perfectly inexplicable, until the engineer ascertained that it depended entirely upon the contact of iron and copper bolts and braces, which had been introduced into the different parts of the frame work. The country around Hayle is entirely desolated with sand, consisting of minutely comminuted marine shells, and which, with some few interruptions extends all along the coast, from Saint Ives to near Padstow, and in many places is drifted into hills of sixty feet in elevation. There can be but little doubt that this sand was originally brought from the sea side by hurricanes, but not even a popular tradition remains of the time or manner of this extensive devastation, which has reached, with some distinct intervals, nearly forty miles in length. Some allusion to this event has been supposed to have been discovered amongst the ancient records of the Arundel family, fixing the period about the twelfth century; but _Mr. Boase_ observes, that the fact of the churches still remaining more or less ingulphed, the age of which does not much exceed three centuries, decisively refutes such a conjecture. On the other hand, it would appear that in the _liber valorum_ of Henry the Eighth, the living of _Gwythian_ was estimated far above its proportion to adjoining parishes. By the shifting of the sand by high winds, the tops of houses, and the ruins of ancient buildings, may be occasionally seen at this very day; and in some places a great number of human bones have been discovered, derived from the cemetries which have been formerly inundated. The farther progress of the sand flood is at length arrested by extensive plantations of the _Arundo Arenaria_, or common sea rush.[79]