Sudden and forceful had been the underwater collision in which the M. N. 1 had participated. Either the lookout, aided though he was by the focused rays of the great searchlight, had failed to notice some obstruction in time to signal to avoid it, or there was an error somewhere else. At any rate the submarine had rammed something--what it was remained to be discovered.

"Bless my shotgun," cried Mr. Damon, "perhaps it was one of those big whales, Ned!"

"It didn't feel like a whale," answered the young financial man.

"And it wasn't!" declared Tom, who was hastening to the engine room. "It was too solid for that."

Following the collision there had been considerable confusion aboard the vessel. But discipline prevailed, and now it was necessary to determine the extent of the damage. This, Tom and his officers and crew proceeded to do.

There were automatic devices in the various control cabins, as well as in the main engine room, which told instantly if a leak had been sprung in any part of the craft. In that serious difficulty automatic pumps, controlled by an electrical device, at once began forcing out the water. Other apparatus rushed a supply of compressed air to the flooded compartment in order to hold out the water if possible. For further security the submarine was divided into different compartments, as are most ships in these days. The puncturing or flooding of one did not necessarily mean the foundering of the craft, or, in the case of a submarine, prevent her rising.

But Tom had sensed that the collision was almost a head-on one, and in that case it was likely that the plates might have started in several sections at once. This he wanted to discover, and take means of safety accordingly.

"How do you make it, Mr. Nelson?" cried the young inventor to the captain in the engine room.

"Only a slight leak in compartment B 2," he answered, as Tom's eyes rapidly scanned the tell-tale gauges. "The pumps and air are taking care of that."

"Good!" cried Tom. "It doesn't seem possible that there isn't more than that, though. We struck a terrible blow."

"Yes, but a glancing one, I think, sir."

"Send for the lookout," ordered Tom. "I can't under stand why he didn't see whatever we've hit in time to avoid it."

The lookout came in, very much frightened, it must be admitted. Only by a narrow margin had all escaped death.

"It was impossible to see it, Mr. Swift," he said. "We had a clear course, not a thing in sight. The bottom was white sand, and I could almost count the fishes. All at once there was a big swirl of water that threw our nose around, and before I could signal to slow down or reverse we were right into her."

"Into what?" asked Tom.

"Some sort of wreck, I took it to be. I shoved the wheel hard over as quickly as I could, and we struck only a glancing blow."

"That's good," murmured Tom. "I thought that must have been the explanation. But what's that about a sudden swirl of water?"

"It seemed to me like a change in the current," the lookout answered. "It threw us right over against the wreck."

"I can very easily imagine something like that happening," admitted Tom. "Well, as long as we're not badly damaged I think we'll go outside and take a look. If we hit a wreck--"

"Bless my looking glass!" cried Mr. Damon, "it may be the Pandora, Tom."

"That's too good to be true!" cried Ned. "Anyhow, let's get out and take a look."

Tom first made sure that the slight leak was not likely to increase, and then arrangements were made for himself, Ned, Koku, and some of the others to go outside in the diving suits. Mr. Damon wanted to be of the party, but Tom was afraid to permit him in that depth of water. Mr. Damon, in spite of his jollity, was not as young as he had been.

Shortly after the collision, which had missed being a disaster by a narrow margin, Tom and his companions were outside the submarine, walking on the white, sandy bottom of the sea. Around them was a myriad of fishes, some of large size, but seemingly harmless, as they scudded rapidly away after a glance at the strange creatures who appeared to have come to dispute with them for possession of Father Neptune's element.

Moving more slowly than usual, because of the greater pressure of water at that depth, Tom and the others made their way around the nose of the submarine. And then, in the glow of the big searchlight, they saw the dim outlines of a steamer, partly imbedded in the sand. Her stern was toward the undersea craft that had rammed her, and the name was not so obliterated but what the young inventor could read it.

"The Pandora!" exclaimed Tom, speaking into his helmet telephone transmitter, the others all hearing him. "We've found the treasure-ship at last!"

And so they had. An accident had brought them to the end of their quest, though it is probable they would have found the Pandora anyhow, since they were making careful circles in her vicinity.

"Yes, that's the Pandora," said Ned. "And now the thing to do is to find out if she really has any treasure on board."

"That's what I'm going to do," declared Tom. "But first I want to investigate this queer current. We can't feel it here, but we may if we get out beyond the wreck. We don't want to be swept off our feet."

"Yes, we had better be careful," said one of the officers.

Accordingly they proceeded with caution along the length of the sunken Pandora. And as they neared her bow they all began to feel some powerful force in the current.

"This is far enough!" said Tom. "Don't get out beyond the protection of the hull. I see what it is. The steamer has drifted here from where she was originally sunk. And here two currents meet, forming a very strong one. It was that which threw us off our course. As long as we remain behind the wreck we'll be safe. But beyond her we may be in danger. She's firmly held in the sand, or, at best, is drifting only slightly. She'll be a sort of undersea breakwater for us. And now to see if we can get on board!"

This proved comparatively easy. Several lengths of chain and one iron ladder were over the stern, evidently having been used when the crew abandoned the ship in the storm that destroyed her. By means of these Tom and his companions gained the main deck near the stern.

The Pandora was a typical tramp steamer. She was high in the bows and stern and low amidships, and it was evident that the quarters of the officers and passengers, if any of the latter were carried, were in the stern. Tom was glad to find the vessel thus comparatively easy of access.

She lay on an almost even keel, and all he and his companions had to do was to walk along the deck and enter the cabins. As they did not have to look out for life lines or air hose they could enter, and even go below decks, in comparative safety.

"Well, here's for it," said Tom to the others. "Let's go in.

"Where would the treasure be, if she had any?" asked Ned.

"Captain's cabin or the purser's strong room, I imagine," Tom answered. "Hardley didn't actually see it, but he said those two places were constantly guarded. I'm inclined to think the purser would have charge of the gold. But we'll try both places."

It was easy to learn which had been the commander's cabin. It had the name "Captain" on a brass plate over the door. Tom and Ned entered. The place was in confusion, and confusion not all caused by the ocean currents. A small safe in the room stood with rusted door open, and the contents of the strong box were gone. Drawers and lockers, too, were opened and empty.

"I guess the captain took as much with him as he could when he got into his boat," commented Tom.

"And the gold, too," added Ned, pointing to the empty safe.

"That wouldn't have held two million dollars in gold," Tom retorted. "I believe the purser's cabin is the place to look."

Making sure they were not missing anything in the captain's room, they came out, to find Koku and the others waiting for them on deck.

"Nothing there," Tom reported. "Did any of you locate the purser's strong room?" One of the men pointed to an open door to the left.

"That's it!" exclaimed Tom. "Yes, and there's a safe here big enough to hold gold for all the revolutions in South America," he added. "I guess we're on the right track at last."

It needed but a look to show them that they had at last reached the place of the treasure. The great safe stood open, and piled inside were a number of small boxes, such as are generally used to ship gold in. Ned, from his bank experience, recognized them at once.

"There's the gold!" he exclaimed. "We've found the treasure!"

"They tried to take some of it with them," said one of the submarine officers, pointing to some opened boxes which were floating near the cabin ceiling. They were caught on some projections which had prevented them from being washed out.

"Maybe they looted the whole safe," suggested Tom. "We'd better have a look."

He tried to pull out one of the many boxes set in tiers in the safe, but it was beyond his strength.

"Me do!" murmured Koku.

It was easy for the giant to pry out one of the boxes with his iron bar, and with another blow from his bar he opened the cover.

"Gold!" cried Ned, as he saw a gleam of yellow showing in the glow from his torch. "There's the gold!"

There was a table in the purser's cabin, made fast to the floor so it had not floated away. At a sign from Tom, the giant turned the box bottom side up on this table.

And then a murmur of wonder came from all who saw the result. For aside from the top layer of gold pieces, the box was filled with iron disks cut to the size of twenty-dollar gold pieces. In an instant it was borne to all what this meant.

"A fake!" exclaimed Tom Swift. "If all the boxes are like this there isn't enough gold on the treasure ship to pay the expenses of this trip! Somebody has been fooled! Open another box, Koku!"