Map of early transatlantic telegraphs
Posted inDaily News

Speed over Cables

One of the essential features of a submarine cable is the speed of signaling. In operating long cables delicate instruments are required, and the currents arriving at the receiving end are feeble in comparison with those employed in land-line signaling. The longer the cable, naturally, the feebler the impulses arriving at the receiving end.

A short cable, a cable of under 1,000 miles being generally considered a short cable, gives a speed of signaling amply sufficient for all purposes, with a conductor weighing about 100 pounds to the mile, surrounded by an insulating envelope of gutta-percha weighing about an equal amount, says Scribner’s Magazine. When we come to a cable of about twice this length it is found necessary, In order to get a practically unlimited speed — that is, a speed as high as the most expert operator can read at — to employ a core of 650 pounds of copper to the mile, insulated with 400 pounds of gutta-percha to the mile.

Posted inEngineering Iron & Steam

The Atlantic Telegraph Cable

The last steamer from England brings the following:

The shore end of the Atlantic cable was landed and successfully connected with the instruments on board the Great Eastern. The Knight of Kerry invoked success on the undertaking, and in conclusion called on Sir Robert Peel, who made an admirable address. Cheers were then given for the President of the United States, when paying out of the heavy shore end of the cable commenced. The splice was completed in the most successful manner, and the cable worked perfectly. The gunboats Terrible and Sphynx accompanied the Great Eastern. A telegram from Valencia, dated the 24th of July, says : “Insulation defects took place on Monday afternoon. The mischief is supposed to exist three miles west of the shore-end splice, and it is believed that it was caused by too much strain from the Great Eastern. She hove too [sic] ten miles from the shore. The Caroline is picking up and underrunning the splice and repairing the fault. It is expected that the damage will be rectified immediately.