"That's what I thought. Let's call Mr. Henderson. The machinery may need adjusting." Jack started from the engine room to do this, and as he paused on the threshold there was a sudden crash. Part of the air pump seemed to fly off at a tangent, and a second later had smashed down on the Cardite motor. This stopped in an instant, and the projectile began falling. Fortunately it was but a short distance above the moon's surface, and came down with a jar, which did not injure the travellers. But there was sufficient damage done to the machinery, for with the breaking of the air pump the water apparatus also went out of commission, and together with the breakdown of the Cardite motor had fairly stalled the _Annihilator_. "What's the matter?" cried Professor Henderson, running in from the pilot-house, for an automatic signal there had apprised him that something was wrong. "There's a bad break," said Jack ruefully. "A bad break! I should say there was," remarked the scientist. "I think we'll have to lay up for repairs." And he called Mr. Roumann. CHAPTER XXIII LOST ON THE MOON Notwithstanding that they were somewhat accustomed to having accidents happen, it was not with the most pleasant feelings in the world that the moon travellers contemplated this one. It meant a delay, and a delay was the one thing they did not want just now. They desired to get to the other side of the moon while the long period of sunshine gave them an opportunity for observation. True there was some time yet ere the long night of fourteen days would settle down, but they felt that they would need every hour of sunshine. "Well, it's tough luck, but it can't be helped," said Mark. "No, let's get right to work," suggested Jack. They got out their tools and started to repair the two pumps. It was found that the Cardite motor was not badly damaged, one of the negative electrical plates merely having been smashed by a piece of the broken connecting rod of the air pump. It was only a short time before the motor was ready to run again. But it could not be successfully operated without the air and water pumps, and it was necessary to fix them next. New gaskets were needed, while an extra valve and some sliding gears had to be replaced. "It's an all day's job," remarked Professor Henderson. But many hands made light work, and even Washington and Andy were called upon to do their share. By dinner time the work was more than half done, and Professor Roumann, announced that he and Mr. Henderson would finish it if Jack and Mark would take a look at the exterior of the projectile, to see if any repairs were needed to that. The boys found that some of the exterior piping had become loosed at the joints, because of the jar of the sudden descent, and, taking the necessary tools outside, while they stuck their life-torches upright near them, they labored away.