Dawn found all in readiness, and at the summons of the bugle all lined up before Ensign Hargreaves to receive their orders. To the submarine were assigned Merritt and Donald, besides Mr. Barr, Ensign Hargreaves, and the prisoner Barton. The _Viper's_ crew was captained by Tubby, a capable motor boat engineer, and Hiram and the others. When this had been done, Barton was led before Ensign Hargreaves. "Barton," said he sternly, "you have acted the part of a scoundrel and should be behind the bars now. But I need you for work, and upon the manner in which you perform it, will depend just how severe your punishment will be. Cast him loose, men, and take him into the engine room of the submarine. You are to stand by for orders." "I'll try to do my best, sir," rejoined Barton in a soft tone of voice, very unusual for him. "I'm sorry, sir, for what I did, but I was led astray by promises of money." This change in the man was almost startling. From a sullen, morose fellow he had suddenly, or so it seemed, become a dutiful, attentive man, willing to obey orders and do his best. Was all this genuine? We shall have to go further to see. There being no excuse for delay, and as all were anxious to get off as quickly as possible, the two craft were boarded. The hatch of the submarine was left open for the present, for it was the intention of the ensign to run "awash," as it is called. The motor boat running very nearly as fast as the submarine, they kept each other company down the coast with little difficulty. It was fine, exciting sport in the motor boat as it cut its way over the swells, hurling spray and water out to either side of its sharp bow. If only the boys had had Rob with them, they would have enjoyed it much more, though. All that was visible of the submarine was the top of her conning tower, and the slender, needle-like "eye" of the periscope. The water surged round her conning tower as she rushed along, for all the world like some sea monster speeding on an errand of destruction. She was not going full speed, for the ensign wished to keep company with the motor boat. At noon, just as the lads on the motor boat were settling down to lunch cooked on a blue-flame stove, a head was thrust out of the conning tower. It was that of Mr. Barr. "We are going to run under the surface in a short time," he said; "just follow your same course, and you'll pick us up when we rise again." "All right," shouted Tubby, his mouth full of ham sandwich, which he held in one hand, while with the other he clasped a big wedge of pie. The hatch on top of the conning tower closed shortly after with a metallic "clang." The next instant the craft vanished from view in a swirl of water. For a time the tip of the periscope tube, which was twenty-five feet long, projected above the surface; then that, too, vanished, and the motor boat was alone on the ocean.