The submarine waited for nightfall before it made the plunge that would start its journey in the same direction pursued by the aircraft on high.

Porus-Tabia battery, on the European shore of the straits, stands close to the ruins of the ancient stone fort, Bokal-Kale, from where there is a submarine cable that connects it with Nagara on the Asiatic shore.

This was the cable that the military promoters of the submarine journey proposed to sever, if they got near enough to it.

The aviators were to play into the scheme in some manner yet to be developed. It would not be Johnson or Freeman if their long heads failed them on this or any other occasion. It was a safe wager that they had some sort of working plan up their sleeves, and the two boys in their company were certainly ready to produce a vote of confidence.

The lay of the land here is an elevation, not approachable from the front without sure discovery, but some opportunity for concealment at the rear—more favorable, for example, for a drop-down party to operate and escape immediate detection.

Four aviators, at least, were taking the chance of a night prowl here, after coming down at dusk, with muffled motors, behind a clump of trees, and within fairly easy reach of the ruins of the ancient fortress.

“Now, my hearties,” advised Captain Johnson, when the four edged against a clammy stone wall for council, “this is only a two-gun battery; the garrison is not expecting company at the back door, and for this reason it’s a fair shake that we might be able to attend to a little business here and get away with it.

“The active end of this position, further up,” he continued, “I propose to visit a little later on, and it is a crawling contract all the way. I feel sure that the two guns here are in need of repair, and I guess I’ll have to fix them!”

The captain mixed a chuckle with these concluding words, and set a deep bite in a lengthy plug of tobacco.

“What’s the object, anyhow, of this cable-cutting business?” asked Billy, who liked to dig at the roots of anything that puzzled him.