"From the top of her periscope to the bottom of her keel,"

replied Captain Nicholson, "the Y-3 displaces exactly 20 feet.

It will be ticklish work to navigate in those six and a half fathoms (39 feet) without being drawn down by suction and striking bottom so hard as to rebound up to the surface, where the Turks are sure to see us."

At 4:30 o'clock in the morning there was light enough to make out the small gray fort guarding the entrance to the Euphrates. The submarine did not lie more than a mile away.

"It's up to us to get out of sight before the fort watchers see us," said Captain Nicholson.

Being satisfied of how far his run should be and verifying his course by the compa.s.s while still on the surface, Captain Nicholson quickly ordered the vessel trimmed down to a depth of 60 feet, and then started forward at about four knots--as low a speed as was consistent with good handling.

"Lucky it's high tide; just beginning to ebb," said Captain Nicholson. "We'll find all the water on the bar that is ever there."

There was to be no more sleep now on the Y-3. From the gunner's mate down every man of the crew was on the qui vive.

As the submarine neared where the bar was charted, it came up till the pressure gauge showed only ten feet of water above.

"Ten feet to hide us from the forts' lookouts and guns,"

explained Captain Nicholson.

Suddenly there was a jar that stirred all on board off their feet. There was a sensation of sinking. As previously instructed, the diving rudder man immediately gave the submarine up-rudder. Captain Nicholson ordered full speed ahead, although he knew it would mean that the vessel's periscope would show, giving the enemy a good look at the vessel.

"If we hadn't come up," said Captain Nicholson, "we would have been sucked down solidly into the sand, and good-bye to our chances at those men-o-war inside."

He was silent a moment and then added: "This is what I call tough luck. We shall have to porpoise."

In a second the submarine was again down in the deep basin beyond the bar. The vessel hadn't been up long enough for the commander even to get a look around.

"Here's where we get busy," said Captain Nicholson. "It's up to us to rush the work along before the men in the fort, who must have seen us, can take measures against us."

The submarine ran along at a speed of ten knots at a depth of forty feet and in almost no time at all had covered the mile from the entrance to where the men-of-war lay.

"Now's the time," said Commander Nicholson.

Quickly the torpedoes, 18-inch superheaters, were placed in the tubes. It only remained to arise, sight the enemy and fire.

Quickly the little vessel rose until her periscope gave the commander a view of the first Turkish cruiser. The commander gave the word for a quick rise and the submersion, and took a firm grip on the periscope.

Through the spray that broke, the keen eyes of the commander made out the form of his first target. There, on the port side of the submarine, was a large Turkish cruiser, stern to.

Midstream, to starboard, lay a light cruiser of the first cla.s.s, and 800 yards up the basin, between the two, a small armored cruiser.

The flat country was thickly veiled with mist and a drizzling rain. A choppy sea added to the chances of making the first attack on the Turks un.o.bserved.

Captain Nicholson steered a course straight to the starboard side of the first Turkish cruiser, to launch the torpedo just forward of amidships at a distance of about 300 yards.

The lookout on the cruiser had not picked up the submarine.

Captain Nicholson saw an officer at the stern, sighting the fort with his gla.s.s. The Y-3 crept on unnoticed.

Suddenly a seaman on the forecastle of the cruiser made out the periscope of the submarine, waved his cap frantically and ran toward an officer.

All this, as it progressed, Captain Nicholson repeated to the lads, who stood just behind him.

Jack glanced at the range scale. It read 349 yards.

The cross wires of the periscope were on her middle funnel.

Captain Nicholson jerked the firing valve for No. 1 torpedo.

There was a hiss of air and a rush of water.

The first torpedo had been launched!

CHAPTER XXV

A SUCCESSFUL RAID

Without pausing to learn the effect of the first shot, Captain Nicholson sent the submarine below with a lurch, ordered the helm hard a-starboard and made for mid-channel, where he knew the second first-cla.s.s cruiser lay at anchor, stern to and nosing the strong ebb-tide.

All members of the crew, as well as Frank and Jack, were jubilant. The men insisted that they had heard a roar that meant the explosion of the cruiser, though this was highly improbable.

Jack and Frank had heard nothing, and they turned to Captain Nicholson.

"Did you hit her, sir?" asked Jack eagerly.

"Sure," was the reply. "The shot couldn't have failed to go home."

But the work was only one-third done, even less than that, when the fact that the submarine had to get out of the harbor again is considered.

The submarine, well down, now ran across the harbor at an angle, aiming to come up to the starboard of the second cruiser.

Captain Nicholson explained his reason for doing this:

"I figure they will expect us on the side nearest the first cruiser," he said. "Therefore, I believe we stand a fair chance of surprising them by attacking on the starboard. At the same time, we will have our movements masked from the third and smaller cruiser by our second victim itself."

This sounded reasonable to the two lads, but they made no comment.

To foster an appearance of an attack off the second cruiser's port side, Captain Nicholson let go a decoy periscope to float with the tide's decided sweep to the left sh.o.r.e and draw the fire of the enemy in that direction.

Slowly the submarine advanced, and presently those on board could hear the unmistakable boom of heavy guns. The ruse had succeeded, and the cruisers and guns of the fort were aiming at the spot in the water where the decoy periscope led them to believe the submarine was floating.

The submarine rose so that the periscope took in the scene above the water. Captain Nicholson, glancing through the instrument, saw that he was at least 500 yards to the starboard of the second cruiser. Under full speed, the Y-3 ran straight up to her enemy's bow.

The periscope, protruding above the water, was quickly sighted by the cruiser, but before the vessel's guns could be brought to bear, Captain Nicholson released the second torpedo. Immediately the Y-3 dived again.

But before the submarine had entirely disappeared under the water, there came a loud roaring boom. The second torpedo had gone home.

"Magazine must have gone too," said Captain Nicholson briefly.

Frank and Jack glanced curiously at the members of the crew.