Nothing daunted by these difficulties, our engineers set to work, and commenced the erection of the workmen’s sheds. These were planted on the isle of Bréhat, at about three league‘ distance from the rock. In addition to the fact that this island possesses numerous perfectly sheltered harbours, it is placed by the currents under quite peculiar conditions with respect to the rock of the Héaux: the ebb-tide swings from the island to the rock, and the flood rushes from the rock to the island; and it is exactly at low water that disembarkations must take place. Finally, the island presented all the resources desirable for the accommodation and provisioning of the numerous artificers whose services were called into requisition by so considerable an undertaking. In one of the havens a jetty of rough stones, about 170 feet in length, was constructed, to facilitate the embarkations and disembarkations, which would necessarily be very frequent. The harbour, that of La Corderie, was exactly opposite the Héaux. In addition to the boats which transported to the rock the materials prepared _in_ the island, a very large flotilla was employed in conveying the rough materials, drawn from all quarters, _to_ the island. The granite came from the Ile-Grande, situated about ten leagues to the westward; the lime from the basin of the Loire; Saint-Malo furnished the timber; and, finally, as the wells of Bréhat did not supply sufficient water for the additional population and the uses of the artificers, water, as well as provisions, was obtained from the mainland.