The balloon seemed scarcely to move, though it was slowly sinking toward the ocean of white clouds which hung between it and the earth.

The two inmates of the car were insensible; their faces were bloodless, their cheeks sunken. They were both young and handsome. Harry Johnston, an American, was as dark and sallow as a Spaniard. Charles Thorndyke, an English gentleman, had yellow hair and mustache, blue eyes and a fine intellectual face. Both were tall, athletic in build and well-proportioned.

Johnston was the first to come to consciousness as the balloon sank into less rarefied atmosphere. He opened his eyes dreamily and looked curiously at the white face of his friend in his lap. Then he shook him and tried to call his name, but his lips made no sound. Drawing himself up a little with a hand on the edge of the basket, he reached for a water-jug and sprinkled Thorndyke's face. In a moment he was rewarded by seeing the eyes of the latter slowly open.

“Where are we?” asked Thorndyke in a whisper.

“I don't know;” Johnston answered, “getting nearer to the earth, for we can breathe more easily. I can't remember much after the professor fell from the car. My God, old man! I shall never forget the horror in the poor fellow's eyes as he clung to the rope down there and begged us to save him. I tried to get you to look, but you were dozing off. I attempted to draw him up, but the rope on the edge of the basket was tipping it, and both you and I came near following him. I tried to keep from seeing his horrible face as the rope began to slip through his fingers. I knew the instant he let go by our shooting upward.”

“I came to myself and looked over when the basket tipped,” replied the Englishman, “I thought I was going too, but I could not stir a muscle to prevent it. He said something desperately, but the wind blew it away and covered his face with his beard, so that I could not see the movement of his lips.”

“It may have been some instructions to us about the management of the balloon.”

“I think not—perhaps a good-bye, or a message to his wife and child. Poor fellow!”

“How long have we been out of our heads?” and Johnston looked over the side of the car.

“I have not the slightest idea. Days and nights may have passed since he fell.”

“That is true. I remember coming to myself for an instant, and it seemed that we were being jerked along at the rate of a gunshot. My God, it was awful! It was as black as condensed midnight. I felt your warm body against me and was glad I was not alone. Then I went off again, but into a sort of nightmare. I thought I was in Hell, and that you were with me, and that Professor Helmholtz was Satan.”

“Where can we be?” asked Thorndyke.

“I don't know; I can't tell what is beneath those clouds. It may be earth, sea or ocean; we were evidently whisked along in a storm while we were out of our heads. If we are above the ocean we are lost.”

Thorndyke looked over the edge of the car long and attentively, then he exclaimed suddenly:

“I believe it is the ocean.”

“What makes you think so?”

“It reflects the sunlight. It is too bright for land. When we got above the clouds at the start it looked darker below than it does now; we may be over the middle of the Atlantic.”

“We are going down,” said Johnston gloomily.

“That we are, and it means something serious.”

Johnston made no answer. Half-an-hour went by. Thorndyke looked at the sun.

“If the professor had not dropped the compass, we could find our bearings,” he sighed.

Johnston pointed upward. Thin clouds were floating above them. “We are almost down,” he said, and as they looked over the sides of the car they saw the reflection of the sun on the bosom of the ocean, and, a moment later, they caught sight of the blue billows rising and falling.

“I see something that looks like an island,” observed Thorndyke, looking in the direction toward which the balloon seemed to be drifting. “It is dark and is surrounded by light. It is far away, but we may reach it if we do not descend too rapidly.”

“Throw out the last bag of sand,” suggested the American, “we need it as little now as we ever shall.”

Thorndyke cut the bag with his knife and watched the sand filter through the bottom of the basket and trail along in a graceful stream behind the balloon. The great flabby bag overhead steadied itself, rose slightly and drifted on toward the dark spot on the vast expanse of sunlit water. They could now clearly see that it was a small island, not more than a mile in circumference.

“How far is it?” asked Thorndyke.

“About two miles,” answered the American laconically, “it is a chance for us, but a slim one.”

The balloon gradually sank. For twenty minutes the car glided along not more than two hundred feet above the waves. The island was now quite near. It was a barren mound of stone, worn into gullies and sharp precipices by the action of the waves and rain. Hardly a tree or a shrub was in sight.

“It looks like the rocky crown of a great stone mountain hidden in the ocean,” said the Englishman; “half a mile to the shore, a hundred feet to the water; at this rate of speed the wind would smash us against those rocks like a couple of bird's eggs dropped from the clouds. We must fall into the water and swim ashore. There is no use trying to save the balloon.”

“We had better be about it, then,” said Johnston, rising stiffly and holding to the ropes. “If we should go down in the water with the balloon we would get tangled in the ropes and get asphyxiated with the gas. We had better hang down under the basket and let go at exactly the same time.”

The water was not more than forty feet beneath, and the island was getting nearer every instant. The two aeronauts swung over on opposite sides of the car and, face to face, hung by their hands beneath.

“I dread the plunge,” muttered Thorndyke; “I feel as weak as a sick kitten; I am not sure that I can swim that distance, but the water looks still enough.”

“I am played out too,” grunted the American, red in the face; “but it looks like our only chance. Ugh! she made a big dip then. We'd better let go. I'll count three, and three is the signal. Now ready. One, two, three!”

Down shot the balloonists and up bounded the great liberated bag of gas; the basket and dangling ropes swung wildly from side to side. The aeronauts touched the water feet foremost at the same instant, and in half a minute they rose, not ten feet apart.

“Now for it,” sputtered Johnston, shaking his bushy head like a swimming dog. “Look, the shore is not very far.” Thorndyke was saving his wind, and said nothing, but accommodated his stroke to that of his companion, and thus they breasted the gently-rolling billows until finally, completely exhausted, they climbed up the shelving rocks and lay down in the warm sunshine.

“Not a very encouraging outlook,” said Johnston, rising when his clothing was dry and climbing a slight elevation. “There is nothing in sight except a waste of stone. Let's go up to that point and look around.”

The ascent was exceedingly trying, for the incline was steep and it was at times difficult to get a firm footing. But they were repaid for the exertion, for they had reached the highest point of the island and could see all over it. As far as their vision reached there was nothing beyond the little island except the glistening waves that reached out till they met the sky in all directions. High up in the clouds they saw the balloon, now steadily drifting with the wind toward the south.

“We might as well be dead and done with it,” grumbled Thorndyke. “Ships are not apt to approach this isolated spot, and even if they did, how could we give a signal of distress?”

Johnston stroked his dark beard thoughtfully, then he pointed toward the shore.

“There are some driftwood and seaweed,” he said; “with my sun-glass I can soon have a bonfire.” He took a piece of punk from a waterproof box that he carried in his pocket and focussed the sun's rays on it. “Run down and bring me an armful of dry seaweed and wood,” he added, intent on his work.

Thorndyke clambered down to the shore, and in a few minutes returned with an armful of fuel. Johnston was blowing his punk into a flame, and in a moment had a blazing fire.

“Good,” approved the Englishman, rubbing his hands together over the flames. “We'll keep it burning and it may do some good.” Then a smile of satisfaction came over his face as he began to take some clams from his pockets. “Plenty of these fellows down there, and they are as fat and juicy as can be. Hurry up and let's bake them. I'm as hungry as a bear. There is a fine spring of fresh water below, too, so we won't die of thirst.”

They baked the clams and ate them heartily, and then went down to the spring near the shore. The water was deliciously cool and invigorating. The sun sank into the quiet ocean and night crept on. The stars came out slowly, and the moon rose full and red from the waves, adding its beams to the flickering light of the fire on the hill-top.

“Suppose we take a walk all round on the beach,” proposed the Englishman; “there is no telling what we may find; we may run on something that has drifted ashore from some wrecked ship.”

Johnston consented. They had encompassed the entire island, which was oval in shape, and were about to ascend to the rock to put fresh fuel on the fire before lying down to sleep for the night, when Thorndyke noticed a road that had evidently been worn in the rock by human footsteps.

“Made by feet,” he said, bending down and looking closely at the rock and raking up a handful of white sand, “but whether the feet of savage or civilized mortal I can't make out.”

Johnston was a few yards ahead of him and stooped to pick up something glittering in the moonlight. It was a tap from the heel of a shoe and was of solid silver.

“Civilized,” he said, holding it out to his companion; “and of the very highest order of civilization. Whoever heard of people rich enough to wear silver heel-taps.”

“Are you sure it is silver?” asked the Englishman, examining it closely.

“Pure and unalloyed; see how the stone has cut into it, and feel its weight.”

“You are right, I believe,” returned Thorndyke, as Johnston put the strange trophy into his pocket-book, and the two adventurers paused a moment and looked mutely into each other's eyes.

“We haven't the faintest idea of where we are,” said Johnston, his tone showing that he was becoming more despondent. “We don't know how long we were unconscious in the balloon, nor where we were taken in the storm. We may now be in the very centre of the North Polar sea—this knob may be the very pivot on which this end of the earth revolves.”

The Englishman laughed. “No danger; the sun is too natural. From the poles it would look different.”

“I don't mean the old sun that you read so much about, and that they make so much racket over at home, but another of which we are the original discoverer—a sun that isn't in old Sol's beat at all, but one that revolves round the earth from north to south and dips in once a day at the north and the south poles. See?”

The Englishman laughed heartily and slapped his friend on the shoulder.

“I think we are somewhere in the Atlantic; but your finding that heel-tap does puzzle me.”

“We are going to have an adventure, beside which all others of our lives will pale into insignificance. I feel it in my bones. See how evenly this road has been worn and it is leading toward the centre of the island.”

In a few minutes the two adventurers came to a point in the road where tall cliffs on either side stood up perpendicularly. It was dark and cold, and but a faint light from the moon shone down to them.

“I don't like this,” said Johnston, who was behind the Englishman; “we may be walking into the ambush of an enemy.”

“Pshaw!” and Thorndyke plunged on into the gloomy passage. Presently the walls began to widen like a letter “Y” and in a great open space they saw a placid lake on the bosom of which the moon was shining. On all sides the towering walls rose for hundreds of feet. Speechless with wonder and with quickly-beating hearts they stumbled forward over the uneven road till they reached the shore of the lake. The water was so clear and still that the moon and stars were reflected in it as if in a great mirror.

“Look at that!” exclaimed Thorndyke, pointing down into the depths, “what can that be?”

Johnston followed Thorndyke's finger with his eyes. At first he thought that it was a comet moving across the sky and reflected in the water; but, on glancing above, he saw his mistake. It looked, at first, like a great ball of fire rolling along the bottom of the lake with a stream of flame in its wake.