"Whew!" gasped Ned, as he stood beside Tom in the bow of the airship. "What's that choking us, Tom?"

"Sulphur, I guess, and gases from the volcano. The wind blew 'em over this way. They're not dangerous, as long as there is no carbonic acid gas given off, and I don't smell any of that, yet. Say, Ned, it's erupting all right, isn't it?"

"I should say so!" cried his chum.

"Put us a little to one side, Mr. Damon," called Tom to his friend, who was in the pilot house. "I can't get good pictures through so much smoke. "It's clearer off to the left."

"Bless my bath robe!" cried the odd man. "You're as cool about it, Tom, as though you were just in an ordinary race, at an aeroplane meet."

"And why shouldn't I be?" asked our hero with a laugh, as he stopped the mechanism of the camera until he should have a clearer view of the volcano. "There's not much danger up here, but I want to get some views from the level, later, and then--"

"You don't get me down there!" interrupted Mr. Nestor, with a grim laugh.

They were now hovering over the volcano, but high enough up so that none of the great stones that were being thrown out could reach them. The column of black smoke, amid which could be seen the gleams of the molten fires in the crater, rolled toward them, and the smell of sulphur became stronger.

But when, in accordance with Tom's suggestion, the airship had been sent over to one side, they were clear of the vapor and the noxious gas. Then, too, a better view could be had of the volcano below them.

"Hold her down!" cried Tom, as he got in a good position, and the propellers were slowed down so that they just overcame the influence of a slight wind. Thus the Flyer hovered in the air, while below her the volcano belched forth red-hot rocks, some of them immense in size, and quantities of hot ashes and cinders. Tom had the camera going again now, and there was every prospect of getting a startling and wonderful, as well as rare series of moving pictures.

"Wow! That was a big one!" cried Ned, as an unusually large mass of rocks was thrown out, and the column of fire and smoke ascended nearly to the hovering craft. A moment later came an explosion, louder than any that had preceded. "We'd better be going up; hadn't we Tom?" his chum asked.

"A little, yes, but not too far. I want to get as many near views as I can."

"Bless my overshoes!" gasped Mr. Damon, as he heard Tom say that. Then he sent some of the vapor from the generating machine into the gas bag, and the Flyer arose slightly.

Ned looked in the direction of the town, but could not see it, on account of the haze. Then he directed his attention to the terrifying sight below him.

"It's a good thing it isn't very near the city," he said to Tom, who was engaged in watching the automatic apparatus of the camera, to see when he would have to put in a fresh film. "It wouldn't take much of this sort of thing to destroy a big city. But I don't see any streams of burning lava, such as they always say come out of a volcano."

"It isn't time for that yet," replied Tom. "The lava comes out last, after the top layer of stones and ashes have been blown out. They are a sort of stopper to the volcano, I guess, like the cork of a bottle, and, when they're out of the way, the red-hot melted rock comes out. Then there's trouble. I want to get pictures of that."

"Well, keep far enough away," advised Mr. Nestor, who had come forward. "Don't take any chances. I guess your rivals won't get here in time to take any pictures, for they can't travel as fast as we did."

"No," agreed the young inventor, "unless some other party of them were here ahead of us. They'll have their own troubles, though, making pictures anything like as good as we're getting."

"There goes another blast!" cried Ned, as a terrific explosion sounded, and a shower of hot stuff was thrown high into the air. "If I lived in Arequipa I'd be moving out about now."

"There isn't much danger I guess, except from showers of burning ashes, and volcanic dust," spoke Mr. Nestor, "and the wind is blowing it away from the town. If it continues this way the people will be saved."

"Unless there is so much of the red-hot lava that it will bury the city," suggested Tom. "I hope that doesn't happen," and he could not repress a shudder as he looked down on the awful scene below him.

After that last explosion the volcano appeared to subside somewhat, though great clouds of smoke and tongues of fire leaped upward.

"I've got to put in a new reel of film!" suddenly exclaimed Tom. "While I stop the camera, Mr. Damon, I think you and Mr. Nestor might put the airship down to the ground. I want some views on the level."

"What! Go down to earth with this awful volcano spouting fire?" cried Mr. Damon. "Bless my comb and brush!"

"We can get well down the side of the mountain," said Tom. "I won't go into any danger, much less ask any one else to do so, and I certainly don't want my ship damaged. We can land down there," he said, pointing to a spot on the side of the volcanic mountain, that was some distance removed from the mouth of the crater. It won't take me long to get one reel of views, and then I'll come up again."

The two men finally gave in to Tom's argument, that there was comparatively little danger, for they admitted that they could quickly rise up at the first sign of danger, and accordingly the Flyer descended. Tom quickly had a fresh reel of film inserted, and started his camera to working, standing it on a tripod some distance from the airship.

Once more the volcano was "doing its prettiest," as Tom expressed it. He glanced around, as another big explosion took place, to see if any other picture men were on hand, but the terrible mountain seemed deserted, though of course someone might be on the other side.

"What's that?" suddenly cried Ned, looking apprehensively at his chum. At the same time Tom jumped to his feet, for he had been kneeling near the camera.

"Bless my--" began Mr. Damon, but he got no farther, for suddenly the solid ground began to tremble and shake.

"An earthquake!" shouted Mr. Nestor. "Come, Tom! Get back to the ship!" The young inventor and Ned had been the only ones to leave it, as it rested on a spur of the mountain.

As Tom and Ned leaped forward to save the camera which was toppling to one side, there came a great fissure in the side of the volcano, and a stream of molten rock, glowing white with heat, gushed out. It was a veritable river of melted stone, and it was coming straight for the two lads.

"Run! Run!" cried Mr. Nestor. "We have everything ready for a quick flight. "Run, Tom! Ned!"

The lads leaped for the Flyer, the molten rock coming nearer and nearer, and then with a cry Koku sprang overboard and made a dash toward his master.