Nixie waited, gave him a lick on the face to check his sleeping, then moved to his end of the bed. Mrs. Vaughn said to Mr. Vaughn, "Charles, isn't there anything we can do for the boy?"

"Confound it, Nora. We're getting to Venus with too little money as it is. If anything goes wrong, we'll be dependent on charity."

"But we do have a little spare cash."

"Too little. Do you think I haven't considered it? Why, the fare for that worthless dog would be almost as much as it is for Charlie himself! Out of the question! So why nag me? Do you think I enjoy this decision?"

"No, dear." Mrs. Vaughn pondered. "How much does Nixie weigh? I...well, I think I could reduce ten more pounds if I really tried."

"What? Do you want to arrive on Venus a living skeleton? You've reduced all the doctor advises, and so have I."

"Well...I thought that if somehow, among us, we could squeeze out Nixie's weight -- it's not as if he were a St. Bernard! -- we could swap it against what we weighed for our tickets."

Mr. Vaughn shook his head unhappily. "They don't do it that way."

"You told me yourself that weight was everything. You even got rid of your chess set."

"We could afford thirty pounds of chess sets, or china, or cheese, where we can't afford thirty pounds of dog."

"I don't see why not."

"Let me explain. Surely, it's weight; it's always weight in a space ship. But it isn't just my hundred and sixty pounds, or your hundred and twenty, not Charlie's hundred and ten. We're not dead weight; we have to eat and drink and breathe air and have room to move -- that last takes more weight because it takes more ship weight to hold a live person than it does for an equal weight in the cargo hold.