Monday, 16 February 2015

Part one of Part two on the Atlantic Cable

Back on 19th December we published a page about the history of the Atlantic Cable - it was the second half of an article which had appeared in Part 46 of Wonders of World Engineering in 1938.   BUT NOW Part 45 has emerged (with thanks) - so here is the first half of the article ..................

The pioneers of submarine telegraphy had to contend with unprecedented conditions, and it was only after repeated failures that cable communications were established between the Old World and the New.

The experiments which led to the laying of the first submarine cables and the trials and accidents which beset those responsible for them form one of the finest chapters in the history of engineering. The early telegraph engineers had to work in the dark. There had been nobody whose previous experience could teach them, and when they made mistakes they were faced with inevitable and often unmitigated failure.

Cooke and Wheatstone in 1837 built the first practical electric telegraph beside the Great Western Railway from London to West Drayton (Middlesex). They extended it later to Slough, in Buckinghamshire. The simple wire suspended from porcelain insulators was useless for underwater purposes, and for many years electricians had been experimenting with means to convey electric current along a sub aqueous cable. As far back as 1811, Schilling and Sommering had made a trial with a wire cable which was sheathed in rubber.

In 1838 Dr. William O'Shaughnessy (afterwards Sir William O'Shaughnessy Brooke, F.R.S.) conducted an interesting experiment for the East India Company, laying an underwater cable across the River Hooghly at Calcutta. Against the action of the water, he covered his wire with pitch; then he enclosed it within a split cane, finally wrapping tarred yarn round the outside. This system was reinvented, independently, by Wheatstone, sometime later, and he described it in the course of a proposal for a Dover-Calais telegraph, made before the House of Commons.

In 1842 Professor Morse succeeded in transmitting electric current beneath and across New York Harbour. He surrounded his wire with tarred hemp and gave it an outer sheathing of rubber. Three years later came another interesting American experiment. Ezra Cornell laid an electric cable across the Hudson River between New York and Fort Lee. He used two copper wires, enclosed in cotton and insulated with rubber, the whole being contained in a lead pipe. As an experiment, it worked well for a while, but in the following year the cable was damaged beyond repair by drifting ice. In that year, 1846, Charles West succeeded in transmitting telegraph messages to a ship in Portsmouth Harbour through a rubber insulated wire which he paid out by hand. These beginnings may be said to represent the genesis of underwater telegraphy.

The late 'forties saw an important contribution to the science of submarine telegraphy, namely, the application of gutta-percha as an insulating material. Werner von Siemens invented a machine for applying gutta-percha to wire. In 1849 mines were fired in the harbour at Kiel, Germany, by detonators connected with an electric cable enclosed in gutta-percha. Almost at the same time, C. V. Walker, then Electrical Engineer to the South Eastern Railway, laid a two-mile gutta-percha-covered wire through the English Channel to Folkestone, the seaward extremity being on board the cable ship Princess Clementine. The shoreward end was connected up with the railway telegraph, and telegrams were exchanged between Walker in the ship and the telegraph office in London, eighty-three miles away.

A decided fillip to submarine telegraphy was given during 1850-51 by T. R. Crampton's completion of the Dover-Calais cable. Crampton was primarily a railway engineer, being the originator of the Crampton type of locomotive, extensively built in the 'forties and 'fifties. In electrical engineering, too, Crampton was equally resourceful and enterprising. The necessary capital amounted to £15,000, and of this, Crampton himself raised half. In the early 'fifties such an enterprise as this was a speculation of speculations.

Wild-Cat Schemes

THE Crampton cable consisted of four copper wires, each covered with a double layer of gutta-percha, the interstices between the' four being filled up with tarred Russian hemp. These four insulated wires formed the core of the cable. They were armoured on the outside by ten No. 1 gauge galvanized wires wound round the central bundle in a spiral. This was a great advance on previous cables, and became a prototype that stood the test of years. It was one thing to lay a telegraph cable across a harbour or a river, or even across the English Channel. To bridge the ocean in the same way was quite another matter. Yet it is a continual peculiarity of modern engineering that the first successful applications of anything on a small scale are almost immediately followed by similar applications on a large scale.

The steamship was yet quite young when the first Atlantic crossings took place. Trunk railways were being built over long distances only ten years after Stephenson had built the Rocket. Ten years again separated the first flight across the Channel and the first flight across the Atlantic.

The shortest distance between the British Isles and Newfoundland is rather less than 2,000 miles. Soundings and surveys had been taking place over some time, and connecting lines had already been laid on land at both ends of the potential Atlantic cable, when in 1856 the Atlantic Telegraph Company was formed.

Charles Bright was appointed Engineer-in-Chief, with Wildman White- house as Electrician. Bright was almost at once made the target for all the wild and wonderful theories concocted by wiseacres on both sides of the Atlantic. Everybody gave him advice, most of which was bad and even fantastic. Self- styled inventors and "experts" were present in great force. Charles Bright, however, was proof against any wild-cat schemes, though their promoters must have worried him and wasted his time a good deal. He plotted the course of the cable between Valentia Harbour, in the south-west of Ireland, and Trinity Bay, Newfoundland. The distance between these two points is 1,640 sea miles, and Bright 'reckoned that 2,500 miles of cable would be sufficient to cover this gap, allowing for all inequalities of the sea floor. The bed of the Atlantic abounds in banks and huge deeps, beginning, in a westerly direction, with an enormous submarine cliff some distance beyond the west of Ireland.

The far-sighted engineer urged the adoption of a heavy cable, weighing 392 lb. per sea mile, with insulation of the same weight. The company, however, was in a hurry to get the work done and overruled him, so that he had to content himself with a 107 lb. per mile cable with 261 lb. gutta-percha insulation. In the course of ............

The rest of this article is a few pages back on the blog on 19th December entitled 'How it was achieved - information between Europe and America

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