Not at all nervous themselves, they were nevertheless surprised at the apparent coolness of the British sailors.

Captain Nicholson noticed the expression on their faces, and took time to remark:

"I suppose we should all be thinking with pity of the dead and dying above us, but when you're a hundred feet or so below, the shots and cries of battle are neither exciting nor gruesome."

The gallant commander was now steering a course for the third of the Turkish cruisers.

"Guess I won't go so close this time," he remarked. "I'll fire at longer range, so we won't have so far to go among the wreckage of all three when we leave."

Ten minutes, later the submarine came within the desired range, un.o.bserved by the cruiser, which was lowering her boats to go to the help of the others. Captain Nicholson stood with his hand on the toggle of the firing valve, reading the range scale.

Suddenly there was a terrific shock. Every man on board the submarine was knocked off his feet, and the submarine went rapidly to the bottom. Jack was knocked unconscious by the suddenness and force of the shock.

When he opened his eyes again, Frank was bending over him.

"What's the matter?" he gasped.

"Shot hit us, I guess," was Frank's calm reply.

The lad was right. Two small Turkish gunboats, whose presence in the harbor was not known to Captain Nicholson, had approached the scene of battle, and making out the submarine's periscope, had opened on her with the big guns. One shot had gone true, and it was this that had sent the Y-3 careening to the bottom.

"Are we going to sink?" asked Jack.

"We've already sunk," replied Frank. "Whether we'll get to the surface again or not I don't know."

The lads heard the hiss of air through the vent in the manifold.

Brown was letting water into the ballast tank to keep the submarine down. He turned as Captain Nicholson walked over to him.

"They got our periscopes, I think," he said coolly. "But our torpedo went just the same!"

Sure enough the tube was empty. The force of the shock had caused Captain Nicholson to launch the torpedo before he was ready, and there was no knowing whether it had been aimed true or not.

The commander now took account of the casualties. One of the men had an ugly gash across his forehead from being thrown against a stanchion, another had a bleeding and probably broken nose.

Brown applied first aid to the injured, while Captain Nicholson got the submarine under way again and headed for the mouth of the harbor.

"I wonder if that last torpedo went home," said Frank. "Do you suppose it did, captain?"

"I don't know," was the reply. "We are blind now, our periscope having been shot away, and there is no way of telling without going to the surface and exposing ourselves to gunfire."

"Is there any danger of our being sunk?" asked Jack.

"Danger!" he repeated. "You bet there's danger. Still, thanks to a tight hull and a true compa.s.s, we have a fighting chance."

The Y-3 was now making ten knots, for, as Captain Nicholson said, "there was no use wasting time and giving the enemy time to plant a barrier."

Still five hundred yards from the sandbar which must be crossed, there was a jar, a moaning, grinding sound, and the motors went instantly dead. From the battery compartment there was a rush of water into the living quarters.

It was but the work of a moment for the crew to "dog down" the doors of that compartment to segregate the damage and prevent the flooding of other compartments. But even then, the Y-3 was in a bad way, and all on board realized it.

"I guess we are gone this time," said Frank quietly to Jack.

"Looks like it," was Jack's cool reply. "However, while there is life there is hope."

Captain Nicholson noticed the look of anxiety on the lads' faces.

"Don't you worry," he said cheerily. "We'll get out of here yet."

But now the deadliest foe of the submarine was at work--chlorine gas. The action of the salt water on the sulphuric acid of the battery cells was generating it with fatal quickness.

Already the boys could feel a deadly burning sensation in their throats and noses.

Fifteen minutes of that atmosphere would have left all on board the submarine gasping and stifling sixty feet below the fresh air that meant life. There was but one thing to do--come to the surface and run for it in the face of the fort.

Captain Nicholson realized that it would be the end if the upper exhaust of No. 3 cylinder failed now, for with the electric engines gone, running on the surface with the Diesels was the only hope. He acted on the instant.

The submarine rose rapidly to the surface, and when well awash, the engines were started at full speed. The hatches were opened and the ventilating fans started, blowing out the gases and letting in the cold, damp air. All on board drew a breath of this invigorating air, and then Captain Nicholson turned his attention to escaping from beneath the big guns of the fort.

From his place in the conning tower he cold plainly see the activity of the fort when the lookout made out the submarine.

Now the two lads, at a sign from the commander, joined him.

Glancing in the direction he pointed, they made out the fighting tops of the first two cruisers, victims of the submarine's daring raid, just reaching out of the water. The third cruiser was afloat, but from her heavy list to starboard, it was plain that she was badly damaged and sinking fast.

The fort was getting the range now, and sh.e.l.ls fell all around the Y-3. One struck the water nearby, hurling water over the conning tower and drenching the three who stood there.

"Well," said Captain Nicholson, "they may get us, but we got three of them."

"And there is some satisfaction in that, anyhow," said Frank.

"You bet there is," Jack agreed.

The submarine was halfway across the bar, and had not been hit, and every instant meant that much more chance for life. The helmsman stuck n.o.bly to his post, head down, and without a look at the fort. The submarine shook and trembled with the vibrations of the hard-pushed engines, straining to get the submarine to deep water.

The gallant lads in the engine-room were doing their best. A sh.e.l.l from long range, with most of its force expended, glanced off the port bow of the submarine, carrying away the towing pennant. The nose of the Y-3 ducked under a bit, but came up serenely in half a second.

The commander of the vessel, perceiving deep water ahead, encouraged the helmsman with a cry. Already the vessel was almost over the bar.

The fire from the fort was decreasing. Only the longer range guns could come into play now.

Looking back, the lads saw two destroyers racing in the wake of the submarine, preceded by a small gunboat.

The first sh.e.l.ls of the gunboat whizzed by the submarine.

Captain Nicholson slammed down the hatch.

"Water armor for us!" he cried.

A moment later the submarine was on the safe haven of the bottom with 100 feet of solid protecting water between it and hostile sh.e.l.ls.

"That was pretty ticklish," said Frank, drawing a breath when they were out of reach of the gunboat's fire.

"It was," was the commander's response, "and we are not safe yet by any means."