The bull's-eyes were closed, the lights switched on, and then, speeding the engine almost to the top notch the captain steered the submarine straight for the war-ship. He had carefully noted her direction before starting his own craft, and he resolved to do a little manoeuvering that would still further astonish the visitor. By careful reading of the different gages Mr. Henderson was able to come to the surface right in front of the _Sylph_, to the no small astonishment of the men on the deck of the vessel. Then, just to show what the _Porpoise_ could do, the inventor darted around the war-ship in a circle. He sunk below the surface, went under the keel of the _Sylph_ and came up on the other side. Then he went the whole length of her, under water, starting at the stern and ending at the bow, where he brought the submarine to a rest in a smother of foam. "Great! Wonderful! Surprising!" were some of the adjectives Lieutenant Muchmore used as he stepped from the conning tower, with Captain Henderson, onto the deck. At the appearance of the officer and the inventor a group of those on the _Sylph_ gave three cheers for the little vessel. "Is she for sale?" asked Captain Wackford. "No, thank you," replied Mr. Henderson with a laugh. "Because if she is I'll give you free passage to England with her, on my ship," went on the commander. "My government would give a fortune for a boat that can do what yours does." "It is not for sale," repeated Mr. Henderson, "but I have some one on board who would appreciate a free passage to England, or any northern port." "Who is it?" asked Captain Wackford. "A Mrs. Johnson and her daughter." CHAPTER XXIII CAUGHT IN AN ICE FLOE Mr. Henderson soon explained the finding of the lady and the little girl, and Captain Wackford readily agreed to give them passage to New York, as the _Sylph_ was to call at that port. So Nellie and her mother were put aboard the warship, after bidding farewell to the captain and crew of the submarine. Mr. Henderson and the boys promised to write to them as soon as they got back from their voyage to the south pole, and, amid a chorus of good-byes the _Porpoise_ resumed her journey. For several days the submarine forged to the south, and the weather became noticeably cooler. Some of the nights were chilly, and those on watch were glad of the heavy coats they had brought along. One morning, after a week of travel, when no interruptions had occurred by reason of accidents, old Andy came up on deck, and sniffing the air, said: "We'll sight ice before night, or I'm a Dutchman." "What makes you think so?" asked Jack. "I can smell it," replied the hunter, whereat Jack, and Mark who had joined him, laughed. "That is no joke," put in Professor Henderson, who, coming up the companionway heard what was said. "Old sea captains will tell you they can smell an iceberg long before they can see it."