"Then what can we do?"
"The only thing left for us to do is to escape."
"Escape? You mean leave the projectile?" asked Mr. Henderson.
"No, I mean escape in the Annihilator. There is no reason why we should stay here any longer. We have what we came to seek, and though I should like to make some further scientific observations, we will have to forego them. We will start the atmospheric motor, and leave Mars."
"That's the stuff!" cried Jack. "Back to earth for ours! It's nice up here, when you don't do something they don't like, but the earth is good enough for me!"
"That's what I say," added Mark.
The Martians were hurrying their preparations to blow up the projectile. Perhaps they guessed that they must act promptly, or they may have had an intimation that something was going to happen, when the ports of the electric cannons were closed.
The shutter of the observation tower was sealed, all openings were well fastened, and, just as the mine was completed and the explosive was about to be put in, Mr. Roumann started the atmospheric motor, and the projectile left Mars with a rush.
Of course, the travelers could not see the blank looks of astonishment on the great faces of the Martians, but they could imagine them, as they shot away from the queer little planet at the rate of sixty miles a second.
"Well," remarked Mr. Roumann as he went to the pilot house, after seeing that the motor was working well, "we got to the place we set out for, and we secured some Cardite, which is what I wanted. I am now able to repay you for building this projectile, Professor Henderson, you need never worry about money again."