"It doesn't seem to be here," he announced.
"What! the negative plate remover not there?" cried the professor. "Why, it must be. It is one of the new tools we got, and it has not been used for anything; has it?".
"Oh, by Jinks!" cried Jack suddenly.
"What's the matter?" asked his chum.
"That plate remover! Don't you remember you and I had it when we were fixing the pipes outside the projectile, when we had the other breakdown? We must have left it back there on the ground."
Jack and his chum gazed blankly at each other.
"I guess we did," admitted Mark dubiously.
"And it is the only one we have," said Mr. Roumann. "We need it very much, too, for the projectile can't very well be moved without it."
"How can we get it?" asked Jack. "I'm sorry. It was my fault."
"It was as much mine as yours," asserted Mark. "I guess it's up to us to go back after it. It isn't far. We can easily walk it."