A better place to effect the capture of the submarine could hardly be found, for the depth shelved gradually from twenty feet close inshore to forty along a line joining the extremities of Penlee and Picklecombe Points.
The after-decks of the two surveying vessels were buried beneath piles of nets composed of three-inch tarred rope intermeshed with flexible steel wire. These could be "paid-out" with considerable rapidity, and being buoyed and weighted would sink automatically till their upper edge was ten feet below the surface and their lower edge the same distance from the bottom. Both vessels were to start simultaneously from the western extremity of the Breakwater and head for Penlee and Picklecombe Points respectively, where strong parties of seamen were ready to haul the ends of the nets ashore.
At half-past five Captain Tarfag gave the order to commence paying out the obstructions, and at a steady six knots the "Investigator" steamed ahead, her consort, being a slower vessel, having to take the shorter distance--that between the Breakwater and Picklecombe. Precisely at five minutes to six the shoreward ends of the nets were secured.
"If Captain Restronguet keeps his promise he is already safe in the net!" exclaimed Lieutenant Egmont. "You see, there is nothing to prevent him from giving his signal at the appointed time. There are no vessels in the bay, and no aircraft overhead."
"It will be a nasty shock to those craft if he fires a rocket over their heads," remarked Arnold Hythe, indicating the crowd of small vessels that, in spite of the picquet-boats, were continually edging nearer and nearer in the desire of their occupants to see more of the promised "fun." "But what is going to happen when we trap the submarine?"
"Oh, Captain Tarfag and I have already settled about that," replied the navigating lieutenant confidentially. "As soon as we are certain that the submarine is in the bay parties of men ashore will drag in the nets, till the craft is either stranded or her propellers are hopelessly entangled in the rope and wire strands. But stand by! It's close on six."
A hush fell on the assembled multitudes. Every face was turned in the direction of the tranquil bay, where, save for a slight ground-swell, the water was unruffled.
The crowds were not kept waiting. Punctually to the minute, at less than four hundred yards from shore and almost abreast of the little village that gives the bay its name, a green and white flag, hanging limply from a staff by reason of the saturated state of the bunting, rose above the surface. Then urged by some unseen power the flag-staff ripped its way through the water, throwing the spray in silvery cascades. Then it described a circle of less than a hundred yards in diameter, then as abruptly as it appeared the emblem of the mysterious Captain Restronguet vanished beneath the surface.
"We've got him, by Jove!" shouted Captain Tarfag.
Four blasts in rapid succession from the "Investigator's" syren was the signal for the men ashore to haul away.