"I don't claim to be a sea captain," said Andy, "but I once was on a whaling voyage and I learned to sniff ice in the air. I saved the ship from collision with a berg once." "Let me see," began the inventor as the adventurers sat about the supper table after the meal was finished, "who have the watches on deck to-night?" "Washington first and Bill second," replied Jack looking at the chart. "Keep a sharp watch for the icebergs," advised the captain. "If you feel a sudden chill in the air, and see something white, stop the engine at once and call for me." When the _Porpoise_ had been put in shape for the night, and the company, tired out from their labors over a general "house cleaning" which Captain Henderson had insisted on, went to bed, Washington took his place in the conning tower. It was quite cold, but as the temperature for several days past had been steadily falling, nothing was thought of it. "I guess I'll git out my fur-lined sealskin coat," said the colored man to himself as he felt the chill night air, that seemed to increase in frigidity along about eleven o'clock. He went to the cabin to get his overcoat, and, returning on deck prepared to spend the rest of his hour of watch in ease and comfort. He stretched out on the bench in the conning tower, noted that the machinery was working right and that the proper course was being steered, and then he let his thoughts drift to the many adventures he and his employer had gone through of late, and also while on the trip "Through the Air to the North Pole." Washington gave one frightened, startled look, in a few minutes, so comfortable had he fixed himself, but happening to look forward through the glass-covered porthole of the tower, he saw something that made the cold chills run down his back. There, right in front of the _Porpoise_, and not a cable-length away was a tall, mysterious, white thing which was shimmering in the pale light of the moon that had lately risen. Washington gave one frightened, startled look, and then, with a tongue that could hardly move, he yelled out: "De ghost! De ghost! He'll git me suah!" Then the colored man made a dive for the stairway leading to the cabin, but missed it and brought up with a crash on the steel floor of the conning tower. "What is it?" called Professor Henderson, springing out of his bunk. "De ghost!" wailed Washington from the huddled up heap he was in. "Catch him!" yelled the captain. "I dasn't," moaned Washington. The next instant the ship quivered from stem to stern. There was a terrible shock, followed by a grinding, crashing sound. Then the craft seemed to be pressed down by some great weight. It heeled over to one side, and the water began to pour down the open man-hole. "Quick! Clamp on the covers!" shouted Mr. Henderson as he felt the sea dashing into the interior of the boat. Jack and Mark sprang to obey. It took all their strength, for the water was running in like a mill-race.