The following lix, Dick stopped on the ramp to the machinery hold to listen. McCarthy was humming the tune of a song that had been the rage at home, but the words were "chicki-boo--chicki-boo--chicki-boo." Barrow smiled as he approached, but the big Irishman didn't realize the reason. He was almost bursting with news. "I've got it, Dick! I've found the key! Don't laugh, but I've discovered the working principle of this little machine, and it will lead to the secret of all others. In a month I'll know how this crate runs." "Don't worry, I'm not laughing, John. I think it's great that you've got this far. I only wish the others would show as much interest. Not one of them has been down here for more than a few minutes, and they know little more than when we started." "Aw! Don't take it that way, Dick. It isn't their fault. Didn't you ever see their _wives_? Those women won't let the men out of their sight for three minutes. Your wife and mine are different--they _trust_ us! If we tell 'em the ship's okay, it's okay; but _them_--say, they can't tell their wives anything. The women in their families do _all_ of the talking." Dick laughed, but knew that it was close to the truth. The other men in the party _were_ tied to their wives' apron strings. Aside from Dolores and Eileen McCarthy, none of the women trusted the space ship. They were afraid it might fly to pieces at any moment, although they had overcome their fear enough to find means of entertainment. Small devices in the cabin showed miniature movies, with words in the tongue of the dome cities. Discovering this created desire to understand the language, and they eagerly attended the classes. One lix Dick found Jerold Brown examining a piece of machinery. A few lix later Andrew Smith had joined him. Soon every earthman was spending his time in the machinery hold, with McCarthy acting as instructor. He would accept no excuse for being late at his classes--and they all arrived on time! * * * * * Weeks slipped by as the ship drove on through space. The earthmen learned to admire the men from Jupiter for their constant good-nature, although they were slightly childish. The crew of engineers were slowly learning the rudiments of Jupiter's science. Barrow through his study of the domes, and McCarthy through study of the machines, far surpassed the others. At times both men spent hours in the model room, at others Dick examined the machines beside the Irishman. They compared notes until each knew the other's findings. Dick took all the men into the model room once every third lix, and spent four hours instructing them in the civilization. Each man had his own set of maps, and marked down facts about his future location. Dick copied their notes on a large map, that covered all the cities. They used numbers to signify different mechanisms, to make it easier to describe equipment that was duplicated in more than one dome.