“Oh, I see .”

“Practically we shall be able to tack about in space just as we wish. Get attracted by this and that.”

“Oh yes. That’s clear enough. Only⁠—”

“Well?”

“I don’t quite see what we shall do it for! It’s really only jumping off the world and back again.”

“Surely! For example, one might go to the moon.”

“And when one got there! What would you find?”

“We should see⁠—Oh! consider the new knowledge.”

“Is there air there?”