Tests—Apparatus—First Messages—Gradual Failing—The “Last Gasp”—Engineering Success—Electrical Failure.
Continuity Tests during Laying.—As previously mentioned, two descriptions of instruments were used on board the ships for testing and working through while laying the cable. These were the “detector” of Mr. Whitehouse and Professor Thomson’s reflecting-apparatus.
The process of testing consisted in sending from one to the other vessel alternately, during a period of ten minutes, first a reversal every minute{145} for five minutes, and then a current in one direction for five minutes. The results of these signals to test the continuity of the line were observed and recorded on board both ships. There was also a special signal for each ten miles of cable paid out between the vessels.
When the splice was made on July 29th, 72 degrees deflection were obtained on the Agamemnon, from seventy-five cells of a sawdust (Daniell’s) battery on board the Niagara, which had previously given 83 degrees. On arrival at Valentia at 6.30 A.M., on August 5th, the deflection on the same instruments (detector and marine galvanometer being both in circuit as before) was 68 degrees, while the sending-battery power on the Niagara had fallen off at entry to 62½ degrees through the marine galvanometer on board that vessel. These figures show that the insulation of the cable had considerably improved by submersion, and when the engineers had accomplished their part of the undertaking, on August 5th, the cable was handed over in perfect condition to Mr. Whitehouse and his electrical assistant.
Apparatus Used in Working.—Unfortunately for the life of the cable, Mr. Whitehouse was imbued with a belief that currents of very high intensity, or potential, were the best for signaling; and he had enormous induction-coils, five feet long, excited by a series of very large cells, yielding electricity estimated at about 2,000 volts potential. The insulation was unable to bear the strain, and thus the signals began to gradually fail.[45]
For something like a week the efforts to work{146} through the cable with the above apparatus proved ineffectual, the power being constantly increased to no purpose. Professor Thomson’s reflecting galvanometer, which had worked so well during the voyage, was then used again with ordinary Daniell cells.
Messages.—In this way communication was resumed, the first clear message being received from Newfoundland on August 13, 1858, and—after considerable delay in getting the American receiving-apparatus ready—on the 16th the following was got through from the directors in England to those in United States:
Europe and America are united by telegraphy. Glory to God in the highest, on earth peace, good-will toward men!
Then followed:
From her Majesty the Queen of Great Britain to his Excellency the President of the United States: