Engineering Wonders of the World
Volume I

378 ENGINEERING WONDERS OF THE WORLD. Fig. 18.—bishop rock iron lighthouse (Douglass, 1847). Fig. 19.—bishop rock lighthouse (Douglass, 1858). to shocks of exceptional severity from waves which sometimes rise fifty feet above the summit of the rock. Hence it was thought best to build the iron lighthouse illustrated in Fig. 18. Work was commenced in 1847, under the direction of Mr. N. Douglass, then the super- intending engineer to Trinity House. The cast-iron columns, strength- , J**00 ened by wrought-iron cores Lighthouse _ . . ° of 1847. and bracmg> were sunk deep and keyed into the solid rock, the general idea of the design being to offer the least possible resistance to the onward sweep of the waves, whose extreme height would be well below the living rooms situated under the lantern, and the central column was made hollow, so that it might afford means of access to the upper part of the lighthouse. The difficulties attending the erection of this structure were many and great. On one occasion an iron column weighing three tons was landed, but as the weather proved too severe for its immediate erec- tion, one end was hauled and pushed into a safe sconce on a rocky ledge, where it was secured by a heavy chain attached to eyebolts let into the solid granite, while the other end was lashed to the main frame of the lighthouse tower. Three days later, when the sea had moderated, Mr. Douglass was able to approach the rock in a boat, and saw that the lower end of the column had been torn away and “ tossed up twenty feet on to the top of the rock,” where it was “ swaying about horizontally like a piece of timber, being held only by the lashings at its upper end.” On landing at the rock some days later the engineer found, among other evidences of the tremendous power exerted by the waves, that a blacksmith’s anvil weighing 1A cwt. had actually been washed out from a hole 3 feet 6 inches deep and 2 feet in diameter, where it had been deposited for safety! At last, after a battle with the sea lasting for four seasons, the tower was finished ready for the installation of the lantern and lighting apparatus. The structure was left in this condition in the autumn of 1849, and every one thought it would resist safely the winds and waves of the coming winter. This con- fidence was rudely destroyed during the month of February 1850. One night a great storm arose, and when morning dawned the rock was seen to be bare, nothing remaining of the tower but some short fragments of the main columns. Still undaunted, the Corporation of Trinity House once more decided to build a lighthouse on the sanio sit©, and. this time they determined upon the construction of a granite tower with