SUBMARINE TELEGRAPHS.
from The Electric Telegraph: Its History and Progress (1852)
[p.157] In 1849, an English Company obtained a charter from the French Government, which granted to them the exclusive right for 10 years of sending electro-telegraphic intelligence between England and certain defined points on the French coast. This right was granted on condition that certain requirements were complied with, and the work carried out within a given period.
The first line laid down consisted of one copper wire simply covered with gutta percha. This wire was laid across the Channel in August, 1850.
The covering of the gutta percha was 1/4 of an inch thick. The wire remained perfect, however, only a few hours, as the action of the sea rolling it about on the sharp rocks at once destroyed the covering and rendered the wire useless.
In September, 1851, another line of telegraph was laid across the English Channel. This consisted of four copper wires, each encased in gutta percha, and then enclosed in a rope of galvanized iron. The length of rope made was 24 miles. It weighed when finished 180 tons. The plan adopted in the manufacture of this telegraph cable was as follows:
A copper wire (No. 16 wire gauge) was first carefully covered with gutta percha; upon this coating of gutta percha a second covering was laid: the copper wire was thus thoroughly well insulated. Four of these insulated wires were then bound together with spun-yarn and hemp, saturated with tar.
This bundle of insulated wires with its hempen covering was then surrounded by ten galvanized iron wires, each wire being 5/16ths of an inch in diameter. The insulated wires [p.158] thus formed the core of a large wire-rope; the whole process and the principle employed being both exactly the same as those patented by the author in 1850.
As this telegraphic wire-rope came from the machine, it was formed into a large coil 30 feet in diameter. Each of the external and internal wires were in one unbroken length. The several smaller lengths of the external wire, as manufactured, were welded together, and the inner ones soldered.
The making of the rope occupied twenty days.
The annexed drawing shows a portion of the rope as finished.
The machine which laid the iron wires around the insulated ones, made, when working freely, about 18 revolutions per minute, and completed about 11 inches of the cable in that time.
This huge wire-rope was then shipped on board the ‘Blazer,’ an old war steamer, which the Admiralty placed at the disposal of the Company. The machinery of the steamer, together with the funnel, had all been previously removed in order to obtain sufficient space in the hull for the coil of the cable.
The ‘Blazer’ was then towed from London to Dover.
On the 25th of September, 1851, the work of paying out the cable commenced. Steam-tugs were placed by the Admiralty at the command of the Company. The ‘Blazer,’ with her cargo, was then towed from Dover to the South Foreland, and one end of the rope conveyed on to the English shore. After this the vessel was towed in the direction of Cape Grinez.
During the process of paying out the rope, it appears that many kinks or bends occurred, and the covering was every now and then torn off the insulated wires as the rope went through the opening made for it in the vessel. So great was the damage done at one time, that it was thought that the inner telegraphic wires were greatly injured. On the testing of [p.159] them, however, the insulation was found to be perfect. It is hoped that time may not reveal the fact of the insulating covering having in any way been seriously injured.
The distance between the extreme points on the two coasts between which the cable was to extend, was 20 miles. An extra length of 4 miles of cable was made to allow for undulations and sinuosities. In consequence of the manner in which the cable was put on board the steamer and afterwards payed out, and the sinuosities of the course traversed by the vessel (which at one time broke away from the steamtugs), the extra length of 4 miles of rope, as allowed in its length, was found to be too little. The end of the 24 miles of rope would not reach its destination by about half-a-mile.
After temporarily connecting the wires in the cable to some spare wire simply covered with gutta percha, and thereby passing a few complimentary messages from coast to coast, operations were suspended until more cable could be manufactured. Another mile of the same kind of cable was made, spliced to the end of the old one, and then laid down in the sea.
On the 18th of October the communication was found to be perfect.
The cost of the cable is said to have been £20,000, and the whole expenses of the Company no less than £75,000.
Arrangements are being made for trying, through the instrumentality of the submarine telegraph, some remarkably curious astronomical experiments, and it is considered that facilities for sidereal observation on all parts of the Continent will be greatly increased by means of it. The South-Eastern Railway Company, have, it is said, with a view to the promotion of this object, consented to carry a wire or wires from their telegraph to the Observatory at Greenwich, so as to connect it with the submarine wires, and thus with the Observatory at Paris, so that simultaneous observations may be made between the Astronomer Royal here and Professor Arago in Paris. The transit of a star over the meridian of London and [p.160] Paris can thus be made notified in an instant, and with it the exact time of its transition. The longitude of both places, and of different places on the Continent, can also be easily obtained, and the most accurate records of comparative astronomy be recorded and preserved.
The working of these submarine wires has hitherto proved very satisfactory — and, it is stated, highly remunerative to the proprietors.
A second rope is now under construction for laying down between England and France, as a duplicate to the first one.
Another telegraphic rope is about to be laid down between England and Ostend: an exclusive permission to do so has already been accorded to the principal proprietors in the submarine telegraph from England to France. A third rope is also to be submerged between England and Holland.
