With this taken care of, the boys were anxious to board the _Carefree_ and see if her interior were as strange and unusual looking as her outer hull. They removed their bulky magnetic shoes and entered the air lock of the _Carefree_. Captain Eaton first explained the purpose of the webbing that lined the walls of the tube. “As you boys saw us move in, you probably know that this is the rear of the ship, and this tunnel is in the center. It goes the full length of our ‘tin can’ and comes out front into the flight deck. We have to leave and enter the ship through the rear end of this tube. Understand?” “Yes, Sir,” the boys answered together. “The outer round surface of our ‘tin can’ revolves around this center tube as though it were a wheel around an axis,” the captain went on. “By so doing, an artificial gravity is induced along the inside rim of the ‘can.’” Captain Eaton frowned. “Am I getting too deep for you?” “I don’t think so, Sir,” Garry replied. “The gravity you are talking about is the result of centrifugal action—the same action that makes a ball swing out on the end of a string when a person swings it around his head. It’s the same kind of artificial gravity they use on the manned space stations.” “You’re pretty sharp, son. I like a boy who doesn’t think that facts belong only in a schoolroom.” “I’ve always been very interested in space, Sir,” Garry said. “I’ll bet I’d surprise you with all I know about it.” “I’m sure you would,” Captain Eaton admitted. “Say, I don’t even know your names. I’ve told you mine. Now let’s have yours.” “I’m Garry Coleman,” Garry answered, “and this is my best friend, Patch Foster.” Since the center tube of the _Carefree_ was not affected by the centrifugal force of the rotating “tin can,” its gravity was zero. For that reason the webbing was used to pull oneself along with and not really for the purposes of climbing and descending. Captain Eaton turned around on the webbing so that he could lead the way along the tunnel into the living quarters of the _Carefree_. His slim, agile legs swung free in the zero gravity as he made the turn. Glossy black space boots covered his feet. The captain showed Garry where to pull a lever which closed a series of air-lock doors between the _Carefree_ and the taxi. The ship’s master and the boys pulled themselves along the tunnel. Then Captain Eaton stopped and said, “Hold on tightly, fellows. We’re going round and round for a few turns.” He pushed a lever beneath the webbing, and Garry felt the tube begin to revolve slowly. “Hey, what’s happening?” Patch called out. “I had to set the tunnel in rotation so that it could catch up with the rest of the ship, which is always turning. As soon as you’ve become used to the spinning, we’ll go into the ship.” When the boys said they thought they could navigate, the captain pointed to an open hatch that had appeared in the wall near them.