"Good!" ejaculated the professor. "Had you looked outside the box you would also have observed two long slender arms pivoted close together, their outer and longer extremities being united, and carrying a small needle which travels, point downwards, along the arc of a circle. Now the action of the instrument is this. Supposing that you wish the ship to travel along, say, a southerly course, you manipulate the helm in the usual manner until the south point of the compass-card swings round to the lubber's mark. The moment that these two accurately coincide you pull toward you a small lever within easy reach of your hand, and the two arms glide in through the slit in the side of the compass-box, passing one on each side of the needle on the edge of the card, and your apparatus is then connected up ready for action. Now, so long as the ship's bows remain pointed accurately to the south, the south point on the compass-card continues coincident with the lubber's mark, and nothing happens. But should the ship deviate ever so slightly from her proper course the heavy, yet sensitive, compass needle at once swings round in sympathy; the small needle on the edge of the card moves the two slender arms which embrace it; the downward-pointing needle at the further extremity of these arms travels along the arc; and electric communication is at once established with the steering machinery, which promptly acts in such a way as to bring back the ship to her original course." "Capital! Admirable!" ejaculated Sir Reginald and the lieutenant together, the former continuing: "Upon my word, professor, you are a veritable wizard--a magician with powers exceeding those of the most potent of your brethren referred to in the `Arabian Nights.'" The professor made a laughing disclaimer. "No, no, my dear sir," said he, "I am no magician, but only a poor scientist. Nevertheless, the wonders of science far exceed those of the `Arabian Nights,' and will well repay the man who cares to patiently study them." Enlivened by conversation of a character so interesting to all present, the sitting was prolonged to quite an inordinate length, and though no one, except perhaps the professor, noted the fact, it was past midnight when the adventurous quartette rose from the table, and taking their wine and cigars with them, moved into the music-room, at the same time dismissing the patient George for the night.