In response to Ned's hand on the lever, the water door closed and thepumps in the next compartment soon cleared not only the sea vestibulebut the tanks of the submarine of seawater.
In a moment the Sea Lion lifted to the surface, and Ned lost no timein relieving himself of his helmet. Then, still attired in the rubbersuit, he hastened to the conning tower, where he found Jack, glass inhand, sweeping the moonlit sea eagerly. There was a faint haze off tothe west, but nothing more. Whatever had passed above the submergedboat, on the surface, had wholly disappeared, though the time had beenvery short.
"What did you see?"
Ned asked the question because Jack's manner indicated excitement, ifnot anxiety.
"Just a shadow," was the reply.
"It might have been a shadow, passing over the moon, the shadow of acloud, or a cloud itself," suggested Frank, sticking his head out ofthe hatchway.
Ned pointed to the sky. There was not a cloud in sight.
"It must have been something of the kind," Jack mused, "for no boatcould get out of sight so soon."
"Not even a submarine?" asked Ned.
"What do you mean by that?"
"Did you see a submarine?"
Both questions were asked in a breath.
"No," replied Ned, "I did not see a submarine, but I don't believe anycloud passing over the sky would drop anything like this."
He passed the knife to Jack and took the glass. Jack opened his eyeswide as he examined the weapon and noted the initial on the handle. Heturned impulsively to Ned.
"Where did you get it?" he asked.
"At the bottom."
"Did you find it lying there?"
"It fell just as I reached the water chamber."
"Then how the dickens did the Diver get away so soon?" demanded theboy.
"It sure did fall from the Diver," agreed Frank, taking the knife andexamining it.
"It would seem so," Ned replied, "but, of course, the initial may bemerely a coincidence."
"I guess we're in for it."
"But how did the Diver get here so soon after our arrival?" asked oneof the boys.
Ned looked grave for a moment, and then replied, his manner showinghow fully he appreciated the importance of his words:
"What I fear is that she got here first."
"And found the wreck?"
"She might have done so."
"Did you see anything of the Cutaria down there?" asked Frank.
"Not a bloomin' thing," answered Jimmie, making his appearance on theconning tower.
"The Diver might have towed it away," suggested Jack.
"Impossible!" cried the others, in chorus.
"Anyway," Jack continued, "we're up against the real goods now. If theDiver is here we'll have a scrap."
"But suppose it should be some other outfit?" asked Frank. "Somepirate outfit after the gold?"
"Still there would be a scrap."
"That's one advantage of goin' with Ned," Jimmie edged in. "You mostalways get into a scrap!"
"Well," Ned said, presently, "we may as well drop down and keep ourlights low. If the Diver is here, the Moores are aware of ourpresence, and we must be prepared for anything."
In ten minutes the submarine lay at the bottom of the sea, with nolights showing, every plate glass window having been shuttered on theoutside by a system of protection which was one of the best featuresof the craft. Then Ned explained that he had seen, at some distance,an apparent elevation rising from the sand.
"That may be the wreck," he said.
"I move we go and see," shouted Jimmie.
"In the darkness?" asked Frank.
"It is as light out there now," Jack declared, "as it will ever be,unless some subterranean volcano lights up and makes fireworks on thebottom, so we may as well be off."
"All right," Ned said, in a moment. "I was meditating a little restto-night, but it may be advisable to get to work at once. For all weknow the Moores may be stripping the wreck, even now."
"What I can't understand," Jack said, sticking to the firstproposition, "is how the Diver got here in such good time."
"As has been said, it may be some other craft," Frank consoled.
"Don't believe it," insisted Jimmie. "The boat that dropped that knifeis a submarine, else how could she disappear so suddenly? She may bewatching us now."
"Or her divers may be prowling around the Sea Lion!" Jack created alittle sensation by saying.
"What would be the use of prowling around outside the boat?" askedJimmie. "They couldn't hear anything, or see anything."
"But a torpedo will act under water," suggested Frank. "Those chapsare equal to anything."
"Shall we go out and look around?" asked Jack.
Ned hesitated. He really was alarmed at the situation. He knew howdesperate the Moores must be, and he had no doubt that in some strangeway the Diver had been brought to the scene of the wreck.
"If you and Frank are partial to a moonlight stroll under sixty feetof water," he finally said, "you may as well put on your water suitsand look around."
"Leave Jimmie here to watch the boat and come with us," urged Jack.
"Go on," Jimmie advised. "I can run this shebang, all right. Go on andsee what you can see."
"If we are going out to-night," Ned said, after reflection, "we may aswell shift the Sea Lion and inspect the bottom over where we saw theapparent elevation."
"Yes; that may be the wreck," Jack admitted.
So the submarine was moved a short distance to the north, about thespace which had seemed to separate the boys from the elevation, andpreparations were made for going out. Jimmie was rather pleased at theidea of being left in charge of the submarine.
"Of course you'll not touch the machinery," Ned warned. "All you cando is to see that the air pumps are kept going. Any motion of theboat, you understand, might break or disarrange the hose carrying theair to us, so be careful."
"Oh, I guess I don't want to murder any of you," laughed the littlefellow. "Go ahead and I'll run things all right on board the boat. Icould operate her anywhere."
The Sea Lion was lifted only a trifle in order to make the change tothe new location. As she moved along she was not much more than afathom from the level sand below.
This was done by regulating the water in the tanks to the pressure atthe depth it was desired to navigate. The delicate mechanisms designedto show depth, pressure, air value, and all the important details of asubmarine were absolutely perfect.
So the three boys entered the water chamber, leaving Jimmie grinningthrough the glass panel. When the boat was brought to the bottom theyopened the outer door and stepped out.
The Sea Lion had traversed only a short distance, yet the surface uponwhich the lads walked seemed very different from the smooth sand levelNed had seen before. There were now little ridges of sand, and now andthen a pit opened up almost under their feet.
A dozen yards from where they emerged from the submarine they cameupon the elevation which Ned had observed on his first trip out. Itwas not, however, a submerged rock or a bit of harder soil in thedesert of sand. It was the hull of a wrecked vessel.
Ned moved along one side of the wreck, as far as his air-hose wouldpermit him to go, and was satisfied that he had found the lost mailship. The sand was already drifting against her sides, but she wasstill far from buried.
On the port side, about a third of the way to the stern from the bow,the boy discovered the wound which had brought the stately vessel toher present position. She lay, tilted about a quarter, in eighty feetof water.
Ned wondered why passing vessels had not discovered her. The tallstacks had been beaten down, probably snapped off at the collision,but the superstructure was high, and not far below the surface, Nedthought.
After motioning Jack and Frank to remain at the break in the side ofthe ship, Ned clambered up and, being careful to protect his air-hoseand line from the jagged edges of the wound, crept inside. Hiselectric flashlight revealed the interior
only a short distance aheadof him, but at the very outset he saw that some of the air-tightcompartments remained intact.
There was a lifting, swaying motion occasionally which told him thatthere was still air imprisoned in the broken ship. At that distancefrom the surface there would be no wave motion to produce theoscillations he observed.
"It is very strange," he mused, as he clambered over bales, chests andboxes in the hold, "that the ship should have gone down so quickly.Telegraphic reports at the time of the accident--if it was anaccident--stated that she sank slowly. It would require only a littleassistance to bring her to the surface."
The boy made his way as far into the interior as he could with hiscomparatively short air-hose, and then turned back to where he hadleft Jack and Frank. He had found it impossible, on account of theshifting to the prow of the hold cargo, to reach the cabin and thecaptain's offices without entering from the top deck.
As he turned around he stopped an instant, his attention attracted bya sound which seemed to come from beyond the bulkhead back of him. Itsounded almost like the hiss of escaping steam. The lad knew that itmust be a strong vibration which could thus make itself felt at thatdistance below the surface and through the heavy helmet he wore.
The more he considered the matter the clearer became the fact that itwas actually uniform sound he heard. That is, sound brought to hisears by the water.
Some force might be moving the water, and the motion might beconveying to his ears, through the thin sides of the air-hose, thestory of the action of the waves, if waves could be created at thatdepth.
As he listened to the steady beating he became convinced that someunknown power was at work in the wreck. What it was he could not evenguess.
Then he heard sharper sounds which seemed to be created by steelstriking steel. The jar brought the sound waves to his ears quitedistinctly.
"Either I'm going daffy," the boy mused, "or there is some one at workon the wreck."
He left the hold and, without giving the others to understand that hehad discovered anything of importance, began an examination of thesand along the line of the bottom. His air-hose was not long enough toadmit of passing entirely around the vessel, so he motioned to theboys to accompany him and turned back to the submarine.
"Did you hear anything down there?" asked he as soon as the helmetshad been removed.
"What are you talking about?" asked Frank, with a laugh. "Water wouldnot convey sound to the ear."
"But the jar of water would," observed Jack. "I heard a jar while Iwas down there."
"I don't believe it!" Jimmie cut in.
"When in swimming," said Frank, "did you ever sit on the bottom of theswimming hole and pound two stones together?"
"Of course," laughed the little fellow.
"And you heard a noise?"
"I believe I did, but it was not such a noise as one would hear fromthe same cause in the air."
"Well," Ned went on, "I heard noises down there, too, and I'll tellyou right here that I'm alarmed."
"Scared!" roared Jimmie.
"Alarmed at what?" demanded Frank. "I didn't see anything to bealarmed at."
"I have no theory as to what it was I heard," Ned went on, "but I'mgoing to get a longer air-hose, shift the Sea Lion so she will hangover the wreck, and go down again right away."
"I'm ready!" laughed Jack. "I want to hear that noise again."
"Do you think there are men down there removing the gold?" asked Jack.
CHAPTER VIII
ON GUARD UNDER THE SEA