Engineering Wonders of the World
Volume III

370 ENGINEERING WONDERS OF THE WORLD. Fig. 23.—UNSHACKLING A BUOY (PREVIOUS TO PICKING UP AND GETTING IN BOARD). Let us now follow up in closer detail the programme which has just been briefly forecast. At each landing-place the end of the line is taken into a previously erected hut fur- nished with electrical instruments. These are for testing the cable whilst it is being sub- Testing=Hut. merged, exchanging signals through the line with the testing-room aboard ship, and subsequently from one shore to the other, previous to connection being estab- lished with the telegraph office in the town for the regular transmission of messages. Fig. 24 serves to illustrate the sort of erec- involved in cable work, we are now in a position to deal with the actual laying of the line between two given spots. Programme vesgej retained for the a work first proceeds to the landing-place selected for one end of the cable. When the circumstances warrant such an arrangement, it is customary for a small auxiliary vessel to be retained for the landing of the shore ends. Be this as it may, one shore end is first landed, and its seaward extremity buoyed at a distance of about two miles, till a depth of some twenty fathoms has been reached. The vessel now proceeds towards the landing-place selected at the other side, to land the cable there.* This end is also buoyed at a suit- able point, unless, in the absence of an auxil- iary vessel, the same ship is to lay the main cable. On the first supposition, the big vessel picks up the second buoyed end, splices on either intermediate or main type cable, and lays the entire line up to the farther buoyed end. This is then picked up whilst still hanging on to the main cable already laid, and after a splice has been effected between the two, the bight of cable is slipped, thereby completing the work. * A supplementary series of soundings is often taken en route. tion usually set up as a testing-hut—very commonly a corrugated-iron building about twelve feet square, sent out from home in parts and put together on the spot. The ship that is about to land the shore end anchors opposite, and as close as pos- sible to, the site selected for the testing-hut. A boat is then lowered and a light Manilla line run ashore PreParations to the hut. The trench for f°rIanding Cable, embedding the cable under the beach, if not > previously opened out, should now be dug to a depth of some three Fig. 24.—TESTING-HUT ASHORE.