“Then tell Williamson, and have him pass the word on to Eph, that watch ought to be very strictly kept,” answered the young captain.

A few minutes Benson remained on deck, chatting with his chum.  When he at last went below the submarine captain lost little time getting into his berth.

When Machinist Williamson came on deck at midnight a light wind was blowing, but the air was not really chilly.  In his heavy reefer the machinist felt wholly comfortable after he had lighted his pipe and started his slow walk back and forth along the deck.

There did not appear to be overmuch sense in keeping this deck watch.  Only a short distance away lay the United States gunboat “Waverly,” with her alert marine guard.  Though there was no moon, the starlight was bright enough to enable a marine on the gunboat to see anything that might skim over the water toward the “Benson.”

Yet Williamson was on watch, under instructions, and he was a faithful fellow who meant to do his full duty.

“Seems kinder tough, of course, to be so long out of one’s bunk in the middle of the night,” the machinist admitted to himself.

Yet, had his vision been keen enough to know what was happening on shore, almost directly opposite the “Benson,” Williamson would have been tenfold more alert.

Over there on the shore, in a clump of flowering, semi-tropical bushes, crouched two men.  On the ground with them lay a metal cylinder some two feet long and seven inches in diameter.  There was also a coil of wire and a boxed magneto battery.

One of the pair held to his eyes a pair of night marine glasses.  Incessantly this watcher kept his gaze focused on Williamson.

About two o’clock in the morning Williamson found it necessary to go below for a few moments.  After reaching the conning tower he paused, for a few moments, to look keenly all about him.

Yet, look as he would through the night, the machinist’s vision could not see that the bush hidden pair on shore, guessing his intention from his stop by the conning tower, had silently taken to the water.  With them they towed the metal cylinder, which floated.  To the cylinder was attached one end of the light wire.

Some distance out from the shore the pair halted, treading water, only their eyes above the surface.  But Williamson could not make out such small objects at the distance.  Then he went below.

“Now, for it,” breathed one of the swimming pair, tensely.

Both swimmers struck out strongly, yet silently, making fast progress through the water by means of some of the best strokes known to swimmers.

When they reached the port side of the submarine Williamson was still below.  Nor had the attention of the marine guard on the “Waverly” been attracted.

In just another swift instant the swimmers made a dive that carried them and their cylinder below the surface.