“So it is. What on earth can it be doing out here? Wait a jiffy, I’ll go below and get the glasses.”

Joe, now fully recovered, dived into the after cabin and soon reappeared with a pair of powerful binoculars.

Nat focused them on the distant object, which, by this time, was visible, even to the naked eye, and reported it to be a small boat, painted white, and looking like a ship’s dinghy, or small lifeboat.

Excitement ran high on board the Nomad when Nat proclaimed that he was almost certain he had seen an arm wave from the small craft.

“I couldn’t be quite sure, though,” he admitted. “Here, Joe, you take a look.”

The chubby-faced Joe now bent the glasses on the object of their scrutiny.

He gazed intently for a minute, and then uttered a shout.

“By ginger, Nat, you’re right!” he exclaimed. “There is someone on board. There must be something the matter with them, though, for they seem to be collapsed in a kind of bundle on the thwarts.”

“We must make all speed to their aid,” said Nat, signaling for more power. “Poor fellows, if they have been adrift in all that flare-up, they must be about dead.”

“I should say so,” agreed Joe.

As they neared the boat, Nat began blowing long blasts on the electric whistle, to let the occupants know that aid was at hand. In response, a figure upreared itself in the drifting craft, waved feebly once or twice, and then subsided in a limp-looking heap.

“I reckon we’re only just about in time,” said Nat grimly, coaxing another knot out of the Nomad.

As they drew alongside the boat, they saw that not one but two persons occupied it. The one who had signaled them from a distance proved to be a short, stocky little man, with a crop of brilliant red hair and a pair of twinkling blue eyes. The merry flash in those optics had not been dulled, even by the terrible ordeal through which, it was apparent, he and his companion had passed.

“Hullo, shipmates! Glad to see you!” he chirruped, grinning up at the boys on the bridge with a look of intense good humor.

His white duck clothes were scorched, and his rubicund hair, on close inspection, proved to be singed, but nothing appeared capable of downing his amiability.

His companion was of a different character entirely. He was dressed in duck trousers and black alpaca coat. White canvas shoes adorned his extremely large feet. But it was his face that attracted the boys’ attention. It was large, round and learned looking, with a thin-lipped mouth cutting the lower part of it like a gash. Above this, a huge, bony nose protruded, across which was perched a pair of big, horn-rimmed spectacles. A crop of sparse gray locks crowned his high forehead and was scattered sparingly over his large, but well-shaped head, which was bare.

“God bless my soul, George Washington Tubbs, but I’ve lost my hat again!” he exclaimed to his companion, as the Nomad drew alongside.

“We’d have lost more than that, I fancy, if it hadn’t been for this here craft,” observed George Washington Tubbs, with a wink at the boys. “We’d have been a pair of buckwheat cakes, well browned, professor, when they found us.”

“I wish I could find my hat,” muttered the spectacled individual in a contemplative tone, peering about under the seats.

“It was blown off when the island busted up,” rejoined Mr. Tubbs. “But we’re keeping these gentlemen waiting. I presume,” he went on, addressing the boys, “that it is your intention to rescue us?”

Nat could hardly keep from laughing. His first impression was that they had encountered a pair of harmless lunatics. But something in the manner of both men precluded this idea almost as soon as it was formed.

“Won’t you come aboard?” he said politely.

It seemed as inadequate a remark as Stanley’s famous one to Livingston in the wilds of Africa; but, for the life of him, Nat couldn’t have found other words.

“Thanks; yes, we will,” responded Mr. Tubbs, with decisive briskness. “Oh, by the way! Don’t move! Don’t stir! Just as you are, till I tell you!”

Nat’s suspicions of lunacy began to revive.

Mr. Tubbs bent swiftly, and picked up what looked like a large camera from the bottom of the boat. Only it was unlike any camera the boys had ever seen. It was a varnished wooden box, with a big handle at the side. Mr. Tubbs gravely set it up on its tripod and began turning the handle rapidly.

“Now, you can move about! Let’s get action now!” he shouted, waving his free hand.

“This will be a dandy film!” he continued, addressing the world at large. “Gallant rescue of Professor Thaddeus Grigg and an obscure individual named Tubbs, following the disappearance of the volcanic isles.”

In good-natured acquiescence to Mr. Tubbs’ orders, the boys began bustling about. Ding-dong Bell, who had come on deck when he got the signal to stop his engines, was particularly active.

“Now, then, professor,” admonished Mr. Tubbs, “up with you.”

“Without my hat?” moaned the professor; but he nevertheless clambered over the side of the Nomad, the boys helping him, while Mr. Tubbs kept up a running fire of directions.

“Keep in the picture, please. Look around now, professor. Fine! Good! Great!”

These last exclamations came like a series of pistol shots, and seemingly proclaimed that the speaker was well satisfied with the pictures he had made. The professor being on board, Mr. Tubbs followed him, the boys helping him up with his machine, and with a box which, so he informed them, contained extra films.

Professor Grigg, as the red-headed, moving-picture man had called him, was too much exhausted to remain on deck, but retired to the cabin escorted by Ding-dong. As he went he was still murmuring lamentations over his hat.

“It’s his weakness,” explained Mr. Tubbs, who seemed to be in no wise the worse for his experience, “he’s lost ten hats since we left ’Frisco in the Tropic Bird.”

The name instantly recalled to Nat an item he had read in the papers some months before, concerning the setting forth on a mysterious expedition of Professor Grigg of the Smithsonian Institute and one George Washington Tubbs, a moving-picture photographer of some fame. The object of the expedition had been kept a secret, and the newspapermen could elicit no information concerning it. It had been rumored, however, that its purpose was to record the volcanic phenomena of the South Pacific.

“Is—is that the Professor Grigg?” asked Nat, in rather an awestruck tone.

“It is,” responded Mr. Tubbs, “and this is the Mr. Tubbs. I’ve taken moving pictures of the Russo-Japanese war, of the coronation, of the Delhi Durbar, of the fleet on battle practice, of—of everything, in fact. I’ve been up in balloons, down in submarines, sat on the cowcatchers of locomotives, in the seats of racing automobiles, hung by my eyebrows from the steel work of new skyscrapers; but I’ll be jiggered if this isn’t the first time I ever took a moving picture of an island being swallowed up alive—oh, just like you’d swallow an oyster.”

“Then the island was swallowed?” asked Joe, with wide-open eyes.

“Swallowed? I should say so. And with a dose of boiling water, too. But I got my pictures! I got my pictures!” concluded Mr. Tubbs triumphantly.

“But where’s your schooner? How did you come to be drifting about in an open boat?” inquired Nat.

“Ah, as Mr. Kipling says, ‘that’s another story,’” said Mr. Tubbs. “I guess I’ll have to leave that part of it to the professor. But—hullo, here he comes now. I guess he’s feeling better already. Possibly he’ll tell you the story for himself.”

“I shall be very glad to,” said the professor, who, after partaking of some stimulants from the Nomad’s medicine chest, already felt, as he said, “much revived.”

“You see in us, young men,” he continued, “the sole members of the volcanic phenomena expedition of the Smithsonian Institute and the British Royal Geographical Society, who adhered to the duty before them. Would you care to hear how we came to be adrift as you found us?”

“Would we?” came in concert from the boys.

“Then I——” began the professor, and then broke off and felt his bare head. “Can—can any one lend me a hat?” he asked.