"I merely wanted to inquire when you and Mark thought of resuming your
studies at college," said the aged man, "but, since this matter has
come up, it will be just as well if you do not arrange to resume your
lessons right away."

"We can study while making the trip to the moon," suggested Mark.

"Not much," declared Jack, with a laugh. "There'll be too much to see."

"Well, we'll discuss that later," went on Mr. Henderson. "Practically
speaking, I think the voyage can be made, and, the more I think of it,
the better I like the idea. We will look over the projectile in the
morning, and see what needs to be done to it to get it ready for
another trip through space."

"Not much will have to be done, I fancy," remarked the German
scientist. "But I want to make a few improvements in the Cardite motor,
which I will use in place of the Etherium one, that took us to Mars."

A little later there came a knock on the rear door of the rambling old
house where the professor lived and did much of his experimental work.

"I'll go," volunteered Jack, and when he opened the portal there stood
on the threshold a small boy, Dick Johnson, one of the village lads.

"What is it you want, Dick?" asked Mark.

"Here's a note for you," went on the boy, passing over a slip of paper.
"I met a man down the road, and he gave me a quarter to bring it here.
He said it was very important, and he's waiting for you down by the