_Pioneering._--The main feature and accomplishment in connection with the second and third Atlantic cables of 1865 and 1866 was, without doubt, the recovery of the former in deeper water than had ever been before effected, and in the open ocean; just as in the first 1858 line it was the demonstration of the fact that a cable could be successfully laid in such a depth and worked through electrically. In the interval between the two undertakings cable repairs had certainly been carried out in the Mediterranean in 1,400 fathoms. Moreover, the recovery and repair of a cable from the depths of the open ocean are now matters of ordinary every-day occurrence, forming part and parcel of cable operations generally. These facts should not, however, in any way detract from the greatness of the achievement at that time in so vast and boisterous an ocean. _Working the Two Lines._--Professor Thomson's reflecting-apparatus for testing and signaling had been considerably improved since the first cable. In illustration of the degree of sensibility and perfection attained at this period in the appliances for working the line, the following experiment is of striking interest: Mr. Latimer Clark, who went to Valentia to test the cable for the "Atlantic" Company, had the conductor of the two lines joined together at the Newfoundland end, thus forming an unbroken length of 3,700 miles in circuit. He then placed some pure sulfuric acid in a silver thimble,[68] with a fragment of zinc weighing a grain or two. By this primitive agency he succeeded in conveying signals twice through the breadth of the Atlantic Ocean in little more than a second of time after making contact. The deflections were not of a dubious character, but full and strong, the spot of light traversing freely over a space of twelve inches or more, from which it was manifest that an even smaller battery would suffice to produce somewhat similar effects. Again, in testing these cables it was found that if either was disconnected from the earth and charged with electricity, it required more than an hour for half of the charge to escape through the insulating material to the earth. This speaks well for the electrical components assigned to the two lines, and for the arrangements adopted in working them. It also shows the benefit derived from seven years' extra experience in manufacture, backed up by the previously mentioned exhaustive Government inquiry thereon. Notwithstanding the dimensions of the core, these cables were worked slowly at first, and at a rate of about eight words per minute. This, however, soon improved as the staff became more accustomed to the apparatus, and steadily increased up to fifteen--and even seventeen--words per minute on each line, with the application of condensers.