"In case the balloon does go up, it would be better to have a backup American officer."

You'll have to keep half an eye on him when the balloon goes up.

"You know, I don't think this balloon is going to hold us both up."

Last week a balloon went up, from the other side of the river.

There'd be plenty of light to see by once the balloon went up.

Think how short a time it's been since the first balloon went up back on Earth.

Well, he thought, the balloon would go up soon enough.

"If the balloon goes up, I want to be ready."

It is the jet you are most likely to face if the balloon goes up.

Then wait - and if I call you over to me, let the balloon go up.