"I cannot say," replied Gerald, still nettled by the failure of his previous conjecture.
"That apparatus gives us warning when we are passing over a submarine cable. It used to be an accepted fact that the insulation of our deep sea cables is so perfect that the 'leakage' is infinitesimal, but by this instrument we can detect their presence in any depth down to one hundred fathoms. This done, it is a comparatively simple matter to grapple for the cable, hoist it to the surface and tap it. The great disadvantage is that the ship must be brought almost to a standstill to enable the 'detector' to act, and, of course, wholly so while the wire is being brought on board."
"Then you tapped the Borkum and Lowestoft cable—I remember the newspaper report stated that it was interrupted."
"No, I did not. If anything went wrong with that cable it was merely a coincidence. What would be the use of tapping a cable if by so doing it was made useless for transmitting messages? No, it was the Middlekerke and Dumpton Gap lines we took on board, and consequently heard the whole of the business concerning the Zietan, and a considerable amount of other intelligence as well. Now I think you have seen all that there is to be seen for the present," continued Captain Brookes, after the engine-room had been inspected. "There is one more marvel, on which I pride myself not a little, but until the finishing touches are completed it would be better to say nothing about it. Some day, and at no distant date, I hope to enlighten you on that subject."
"One question I should like to ask—I hope you will not think me impertinent or unduly inquisitive—that is, where did you obtain your officers?"
The captain pursed his lips for a few moments before replying. "They are, for the most part, gentlemen," he observed. "But, unfortunately, they have fallen in the social scale, and wish to regard their past as a closed book. I can tell you of a few cases, though, of course, in strict confidence. Mr. Palmer, one of our lieutenants, for example, was but a few years ago a commander in the Royal Navy. Ran his vessel full tilt on the rocks, was court-martialled, and 'smashed.' As far as his friends are concerned, Palmer—though that is not his real name—is supposed to be away for a three-years' tour in the Rockies. Then there's White, the surgeon—also an alias, by the bye. He was a well-known country doctor with a good practice till he fell foul of a coroner's court over some trivial detail. It broke him as far as England was concerned."
"And the men?"
"Are mostly the discarded victims of the British Admiralty's short service system, with a sprinkling of merchant seamen who have been ousted by cheap and inferior foreigners."
"Are you not afraid that some of them will desert and reveal the secret of the Olive Branch?"
"It matters little so long as they do not desert in a body; but, thanks to the condition under which they are engaged, I do not anticipate any trouble in that direction. No man is acquainted with the whole of this vessel's mechanism. Even the officers' duties are not entirely interchangeable. For instance, Sinclair, the gunnery Jack, would be helpless on the Z-rays; Taylor—oh! I have forgotten something, after all. With the load of responsibility on my shoulders it's a wonder that I am not even more forgetful. There's Taylor, the scientist; he runs the laboratory with Guy Temple as his assistant. I have not yet shown you his sanctum."