Lighthouse
The Breakwater thrown across Plymouth Sound is another of the great useful enterprises of Britain. Mr.Rennie was the distinguished engineer appointed to perform this work. He knew that to resist the force of the heavy sea which rolls into the Sound from the south and south-west, a very considerable slope would be necessary for the breakwater, and accordingly, it is so constructed. He also perceived that great masses of stones from one to ten tons each would be required.
The quarries from which these were procured are situated at Oreston on the eastern shore of Catwater; they lie under a surface of about twenty-five acres, and were purchased from the Duke of Bedford for £10,000. They consist of one vast mass of compact close-grained marble, many specimens of which are beautifully variegated; seams of clay, however, are interspersed through the rock, in which there are large cavities, some empty, and others partially filled with clay. In one of these caverns in the solid rock, fifteen feet wide, forty-five feet long, and twelve feet deep, filled nearly with compact clay, were found imbedded fossil bones belonging to the rhinoceros, being portions of the skeletons of three different animals, all of them in the most perfect state of preservation, every part of their surface being entire to a degree which Sir Everard Home said he had never observed in specimens of that kind before. The part of the cavity in which these bones were found was seventy feet below the surface of the solid rock, sixty feet horizontally from the edge of the cliff where it was first begun to work the quarry, and one hundred and sixty feet from the original edge of the Catwater. Every side of the cavern was solid rock, the inside had no incrustationof stalactite, nor was there any external communication through the rock in which it was imbedded, nor any appearance of an opening from above being closed by infiltration. When, therefore, and in what manner these bones came into that situation, is among the secret and wonderful operations of nature which will probably never be revealed to mankind.
M. Dupin, an intelligent observer of our great naval and commercial enterprises gives the following description of the working of the quarries from which the Breakwater stone was procured.
“The sight of the operations which I have just described, those enormous masses of marble that the quarry-men strike with heavy strokes of their hammers; and those aerial roads or flying bridges which serve for the removal of the superstratum of earth; those lines of cranes all at work at the same moment; the trucks all in motion; the arrival, the loading, and the departure of the vessels; all this forms one of the most imposing sights that can strike a friend to the great works of art. At fixed hours, the sound of a bell is heard in order to announce the blastings of the quarry. The operations instantly cease on all sides, the workmen retire; all becomes silence and solitude; this universal silence renders still more imposing the sound of the explosion, the splitting of the rocks, their ponderous fall, and the prolonged sound of the echoes.”
These huge blocks of stone were conveyed from the quarries on trucks, along iron railways, to the quays, and from thence into the holds of the vessels built expresslyfor the purpose. On their arrival over the line of the Breakwater, they are discharged from the trucks by means of what is called atyping-frame, at the stern of the vessel, which, falling like a trap-door, lets the stone into the sea. In this manner a cargo of sixteen trucks, or eighteen tons, may be discharged in the space of forty or fifty minutes. Two millions of tons of stone, and one million sterling in money, was the calculation made at the outset, as requisite to complete this great national work.
Train tunnel