In viewing the whole of the scenery of this stern coast "it is impossible" says De Luc, "not to be struck with the idea, that _the bed of the sea is the effect of a vast subsidence_, in which the strata were broken off on the edge of what, by the retreat of the sea towards the sunken part, became a _continent_; the many small islands, or rocks of granite, appear to be the memorials of the land's abridgement, being evidently parts of the sunken strata remaining more elevated than the rest." There is a small _Archipelago_ of this kind called the _Long-ships_, at the distance of two miles west of the Land's end; on the largest of these rocks is a light-house, which was erected in consequence of the very dangerous character of the coast, by a Mr. Smith, in the year 1797, who obtained a grant from the Trinity House, and was rewarded for a limited number of years by a certain rate on all ships that passed it. This period having expired, it is at present under the jurisdiction of the Trinity House.[39] The tower is constructed of granite, the stones of which are _trenailed_ on the same plan as that adopted by Smeaton in the construction of the Eddystone light-house. The circumference of the tower at its base is 68 feet; the height from the rock to the vane of the lantern, 52 feet; and from the sea to the base of the light-house it is 60 feet; but notwithstanding this elevation its lantern has been often dashed to pieces by the spray of the ocean during the winter's tempest! The management of this establishment is entrusted to two men, who during the winter are often, for two or three months, confined to this sea-girt prison without the possibility of communicating with the land; they accordingly lay in a store of provisions, as if they were about to embark for a long voyage.