"I don't know yet. If it doesn't blow any harder we may be able to weather it."

"And if not?"

"If not, we may go to the bottom."

"Is anything wrong with the ship?" was Frank's next question.

"Yes, the engine is not working right. It is not developing enough power to keep us driving against the storm. I am afraid it may strike us broadside on and tear the cabin and decks loose from the gas-bag,"

replied the Frenchman.

As the boys and Ben gained the deck, the storm struck them in its full fury. It was not cold, they were too far south for that, but the wind fairly drove their breath back down their throats.

"Say, let's grab on to a stay or something," gasped Harry, "I don't want to get blown overboard."

They fairly fought their way to the edge of the navigating deck, which was swaying in a sickening fashion, and clung to one of the stout mainstays of the stressed and storm-driven gas bag above them.

Far below, the sea roared and its wave crests gleamed with phosph.o.r.escent light, as the furious wind ripped off their tops and sent them scurrying over the heaving waters.

But, bad as the wind was, a far graver peril menaced the dirigible, and the boys knew it. The lightning was zipping and ripping across the sky in every direction, and, in the event of a bolt striking the craft to which they clung, the boys knew that they might as well be sitting on a keg of exploding dynamite. There would a blinding crash as the gas exploded, and then oblivion.

As they hung on for dear life, Malvoise, his face gleaming white in the glare cast from one of the cabin ports, came up to them.

"Do you think you can take the wheel for a while?" he asked Frank.

"What with fear and exhaustion Constantio is almost unable to stand up."

Frank agreed, and, followed by the others he entered the pilot-house.

With the exception of the binnacle light above the compa.s.s and a small shaded incandescent that shed a glow on the height indicator, the place was as black as a well.

"How is she doing now?" the boys heard Malvoise ask the inventor.

"Ah, senor, poor thing, she is torn and strained in every direction.

My heart bleeds for her!" exclaimed the Spaniard.

"Yes--yes," broke in Malvoise impatiently; "but can she last out?"

"I do not know," came the reply of the other. "It is much to ask of any dirigible to last out such a storm. See," he turned the light on to the wind-gauge--it showed a pressure of sixty miles an hour, "it is a wonder to me she has not been torn apart," he declared.

"Well, you'd better go and get some sleep now," said Malvoise abruptly, "one of these boys here will take care of the ship while you nap."

"Very well," said the Spaniard, "do not drive her too hard against the wind, senor, but rather let the wind drive her. Good-night."

He staggered out on to the swaying, plunging deck and vanished. Frank had taken the wheel as the Spaniard relinquished it and he was astonished to find how, in spite of its gears, the wind-stressed rudder tore and tugged at the spokes.

"The strain on the rudder must be terrific," he thought to himself; "it's a wonder it has held out as long as it has."

Taking a casual glance at the height indicator, Frank gave a start. It indicated twelve thousand feet. It was higher than the boy had ever been before.

For several minutes he was too busy easing the dirigible through a blast that seemed as if it would rip her apart to notice the gauge again. When he had an opportunity to do so, he gave a whistle of surprise.

The dirigible had now climbed on the wings of the storm to an alt.i.tude of fourteen thousand feet.

Glancing through the pilot-house window the young helmsman saw tattered shreds of storm clouds driven by at a terrific speed; but fast as they went, the dirigible was hurried along with them at an equal speed. The rapid motion had a tendency first to exhilarate and then to turn dizzy those who partic.i.p.ated in it.

All at once a sharp whistle sounded from a tube placed so that it was close to the helmsman's ear.

"A signal from the engine-room," cried Malvoise, "answer it."

"Hullo!" called Frank, turning back the whistler at the mouth of the tube. Then he placed his ear to it.

"Two cylinders are missing fire," came the hail, "to make repairs we shall have to stop the engine."

"Keep on with what power you have," shouted back Frank. "We've got to keep going."

There was no need to explain to the others what the bad news from the engine-room was. They had guessed from his reply.

And still the dirigible rose.

She was now at an alt.i.tude of fifteen thousand feet, and even as Frank gazed at the indicator she soared higher.

It grew bitterly cold.

"Something will have to be done," he shouted to Malvoise, "if we keep on going higher the air will soon be so rarefied that we shall be unable to breathe."

"Set your dropping planes," shouted Malvoise, above the turmoil.

"I have tried to," yelled back Frank, "but she won't drop unless the engine forces her ahead faster. The wind is stronger than we are."

"Let out the gas," suggested Harry.

Frank shook his head.

"I don't want to do that except in case of actual necessity," he said.

"We may need all we have before long."

"I can feel an awful pressure on my ear drums!" suddenly exclaimed Harry.

"No wonder," was Frank's rejoinder; "look at that."

He pointed to the gauge.

The dirigible had now been driven to a height of eighteen thousand five hundred feet, and breathing was really becoming painful.

Desperately Frank struggled to get the sinking planes to act, but the wind pressure on the bag counteracted all his efforts in this direction. So fast was the hurricane now driving the gas-bag ahead that the sub-structure lagged behind, straining at its confining stays and braces.

All at once Harry gave a cry and sank to the floor of the pilot-house.

Malvoise, the next instant, hastened to the deck and cried:

"Air, air!"