A CONCRETE ISLAND.

Wairarapa Age, Volume XXVIII, Issue 8100, 21 March 1906, Page 7

A CONCRETE ISLAND.

Arrangements are being made for the construction of a novel lighthouse off Cape Hatteras, on the coast of Massachusetts. The shoals off this Oape have taken a terrible toll of ships year after year ever - since the sea traffic commenced. Fourteen miles off the shore the Gulf Stream sweeps northward at a rapid Dace, and vessels going south have to use a six mile strip of water between this powerful current and the sands. IN HEAVY WITHER it is easy for a vessel to get too near the shoals, and then destruction is almost certain*. It is quite impossible to place a lightship on the spot, as though there is from twelve to twenty feet of water under ordinary circumstances, in storms the •sana itself is often laid bare. A VESSEL* IS LIFTED thirty or forty feet high by the great waves and then allowed to fall on the shoal with shattering force. The next wave completes the destruction. A special Bill has, theretore, been pat through Congress to provide for the ereotion of a lightbouse on the shoals. The foundation will be of massive steel caisson in the form of a lower portion of a oone. This will be divided into oompartments by horizontal partitions, and will be towed by a tug to the locality. There it will be allowed to rest on the sand, its top projecting above the water. The weight of the caisson will cause it to sink into the sand a few feet. Then compressed air will be pumped into the Jower compartment to FORCE OUT THE SAND AND WATER and men will be sent down to dig out the sand below. The caisson will thus gradually sink down into the shoal, and when twenty feet of its base are in the sand, the whole ereotion will be filled up with concrete. The caiison will be 108 feet in diameter at the bottom, and 50 feet at the top and will for in a solid island upon which the lighthouse proper will be built. The structure will be further strengthened by rouks being piled around it, and the engineers claim that it will be able to withstand easily the tremendous onslaught of the waves.