A great arm, covered with mouths, like the ones the boys had seen absorb the rats, shot out of the sea. Another and another followed it, and hapless Sanborn, screaming in terror, was dragged from the structure of the aeroplane, to which he clung with a drowning man's clutch.

"It's a devil-fish," shouted the boys.

"Fire on the thing," shouted Malvoise, pouring the contents of his revolver down into the fleshy ma.s.s of the octopus.

Instantly a great cloud of inky fluid spread over the waters and into the opaque waves the waving arms sank, dragging with them to the depths of the sea the treacherous mechanic.

Shocked and sickened by the scene, the boys turned away and even Malvoise seemed powerfully affected. He hid his face in his hands as the wounded monster slowly sank without relinquishing its hold on its victim.

As for Constantio and a red-headed bushy-whiskered man, whom the boys learned later on was Sam Wells, one of the three men who helped in working the dirigible, they seemed completely unnerved by the sight they had witnessed. Malvoise's sharp voice recalled them to themselves.

"Come now, collect your wits," he shouted; "poor Sanborn's gone, and we can't save him. Cut loose from the aeroplane and haul up the rope-ladder. Constantio, you take the wheel. Wells, when you have got the ladder aboard, turn to and stow that stuff further aft."

He indicated the pile of treasure sacks.

Wells and two other men who had been standing about the deck instantly busied themselves obeying these orders. It was evident from their implicit obedience that Malvoise was master on the dirigible.

As the engine was set going and the ship forged ahead, leaving behind it the wrecked aeroplane and the watery grave of Sanborn, Malvoise called the boys' attention, in a half-joking way, to the damage Ben Stubbs' bullets had done to the gas-bag.

"However," he went on, "fortunately it does not make so much difference as it would in any other air-craft. After dinner I will send one of the crew aloft to put a patch on the hole and we can then re-inflate that section from one of the hydrogen tubes."

Precarious as their situation was, the boys, whose interest in aeronautics was a sort of ruling pa.s.sion with them, could not but help being interested with the perfect working out of all details aboard Luther Barr's craft. After an excellent dinner, in which fresh meat and vegetables from a well-stocked ice-box formed the staples, they watched with interest the red-headed sailor, Wells, scramble up into the network of the bag and sew a patch over the bullet hole made by Ben Stubbs' shot. The patch affixed, it was coated with a water and gas-proof solution the sailor carried in a small pot suspended round his waist. After an interval allowed for drying, a cylinder of gas was dragged out of the after storeroom where they were kept, and the section which had been injured was refilled by means of its own inflation hose, which was provided with a nozzle adjustable to the mouth of the gas receptacle.

To the boys' surprise, when darkness fell the dirigible still forged ahead and no change of her course was observable. They had imagined that she was on her way to join Luther Barr at some nearby meeting-place, where the Brigand would take the treasure on board, but, so far, her navigators showed no intention of alighting.

At ten o'clock Malvoise stepped up to the three adventurers and said:

"It is a rule on board that all lights shall be extinguished at this hour. If you are ready for bed I will show you to your sleeping place."

He led the way to a small cabin fitted with two bunks and lounge. The boys wanted to ask a score of questions, but knew it would be useless, so remained silent.

"I wish you a good night's rest," said Malvoise as he switched on a tiny electric light with the warning that the dynamo would be cut off in ten minutes' time.

As he closed the cabin door behind him there was a sharp click.

The cabin door was fitted with a stout spring lock.

The adventurers were prisoners a thousand feet in the air.

CHAPTER XXIII.

PRISONERS IN DIRE PERIL.

"Locked in, by gosh!" exclaimed Ben Stubbs, as the lock clicked.

"What can they mean to do with us?" wondered Frank.

"So far we've been treated like lords, but I don't like the idea of being penned up in this cabin," said Harry.

Much more speculation was indulged in by the boys, but without their arriving any further at an accurate idea of what was likely to be their ultimate fate at the hands of Luther Barr's men. While they were still talking the light went out, as Malvoise had warned them it would, and they were plunged in total darkness.

Not being heroes of romance, but just healthy boys, the two lads were asleep a few minutes after they threw themselves in their bunks, which were provided with excellent springs, and bed-clothing of good material. As for Ben Stubbs, as he himself said, he could have slept on a whale's back so long as the animal didn't dive.

How long he slept Frank had, of course, no means of estimating, as it was too pitchy black in the cabin for him to see the dial of his watch, but he opened his eyes with a start and soon found out that he had been aroused by what seemed an unusual disturbance aboard the dirigible.

He heard the trampling of feet as the crew ran to and fro, and the shouting of orders in Malvoise's voice. The cabin port was closed and locked on the outside, although the cabin seemed perfectly ventilated by some other aperture; so it was impossible for Frank to distinguish what was said, but the tones of the Frenchman's voice conveyed intense excitement.

The motion of the air-ship, too, seemed strange.

When they had gone to sleep it seemed as if they were sleeping in a room ash.o.r.e, so perfectly evenly did the ship rush ahead through the night; but now every portion of her frame seemed to be complaining in its own particular voice, and she groaned and strained like a ship in a storm.

Frank aroused Harry, and a few minutes later Ben Stubbs, too, was awakened by the peculiar motion of the ship.

"What's happening?" he demanded, as one of the air sailors ran heavily along the deck overhead.

"I don't know," rejoined Frank; "but it seems to me that we are in a storm of some kind.--Hark!"

As he spoke there was a blue glare of lightning outside, in which the ropes and stays of the ship, seen through the closed port, stood out as in an etching. Simultaneously there came a terrific crash of thunder. They were evidently in a bad storm.

"I wish we were outside instead of cooped up in here," exclaimed Ben.

"I like to be out on deck in bad weather and not penned up in a cubby hole."

"Let's try the door," suggested Frank, "we might be able to force the lock."

But the lock was evidently put on to stay, and tug and strain as they would, they could not budge it an inch.

The motion of the ship by this time was so violent as to make them feel quite seasick. She swayed from side to side and now and then took long dips.

"I know what they are doing," exclaimed Frank as the ship executed the latest of these diving maneuvers; "they are setting their aeroplanes low so as to try and find a smooth current of air."

"They've got a fine chance to, if it's blowing as hard as it seems to be," was Harry's comment.

The uproar on deck grew louder.

They could now hear Malvoise's voice, directing the crew to strengthen this stay or lend a hand on that rudder brace.

The ship was evidently pa.s.sing through a crisis.

It was hard for the boys to remain cooped up in their pen, but deliverance was near at hand.

The door was suddenly flung open, and Malvoise himself stood framed in the square of light from the illuminated saloon behind him.

"You had better come out of there," he said briefly, "we are in a bad storm."

"Are we in danger?" asked Harry.