"No particular harm is done to the projectile, but I am afraid that, with the plates in his possession, the man may discover the secret of the power that I use. Oh, I should have locked them up, but I thought they would be safe."
"What has happened?" asked Mr. Henderson, entering the machine shop at that moment. The scientist told him, and expressed his fear.
"Do you really think there is any danger that the man, whoever he was, will learn how to use the plates?" inquired the professor.
"Perhaps, and then, again, perhaps not. I think it will be very difficult for him to work out the secret of the power from the plates, for they are only a small part of the mechanism. Still, he may do so. I am convinced now that this man is either the same one of whom I stand in fear, or he is some one hired by him to steal my secret."
"Then we had better notify the police," suggested Mark.
"No, that would never do," answered Mr. Roumann. "I would have to describe the plates, in order to have the authorities identify them in the possession of the thief, and I do not care to do that. No; the best plan will be to hasten work or the Annihilator, and start for Mars before the thief can gain any advantage from the plates. If he should succeed in discovering from the plate how to make the power that is discharged in wireless currents, it will take him a long time, and we can be away before then. Let us hasten our work and start for Mars."
"You say you have duplicates of the plates?" asked Jack.
"Yes. I was afraid lest something happen to one set, so I made three. Well, it will do no good to worry, but I wish I had the plates back."
"I don't see how he got them," observed Mark. "There doesn't seem to be anything broken, to indicate how the thief got in, and he certainly didn't touch Professor Henderson's live wire."
Not a window or a door had been forced, and the two machinists, who slept in the shop, declared they had heard no suspicious sounds during the night. It was a mysterious theft, and there seemed to be no means of solving it.