“How convenient it would be,” Lady Muriel laughingly remarked, _à propos_ of my having insisted on saving her the trouble of carrying a cup of tea across the room to the Earl, “if cups of tea had no weight at all! Then perhaps ladies would _sometimes_ be permitted to carry them for short distances!”
“One can easily imagine a situation,” said Arthur, “where things would _necessarily_ have no weight, relatively to each other, though each would have its usual weight, looked at by itself.”
“Some desperate paradox!” said the Earl. “Tell us how it could be. We shall never guess it.”
“Well, suppose this house, just as it is, placed a few billion miles above a planet, and with nothing else near enough to disturb it: of course it falls _to_ the planet?”
The Earl nodded. “Of course—though it might take some centuries to do it.”
“And is five-o’clock-tea to be going on all the while?” said Lady Muriel.
“That, and other things,” said Arthur. “The inhabitants would live their lives, grow up and die, and still the house would be falling, falling, falling! But now as to the relative weight of things. Nothing can be _heavy_, you know, except by _trying_ to fall, and being prevented from doing so. You all grant that?”
“Well, now, if I take this book, and hold it out at arms length, of course I feel its _weight_. It is trying to fall, and I prevent it. And, if I let go, it falls to the floor. But, if we were all falling together, it couldn’t be _trying_ to fall any quicker, you know: for, if I let go, what more could it do than fall? And, as my hand would be falling too—at the same rate—it would never leave it, for that would be to get ahead of it in the race. And it could never overtake the falling floor!”
“I see it clearly,” said Lady Muriel. “But it makes one dizzy to think of such things! How _can_ you make us do it?”
“There is a more curious idea yet,” I ventured to say. “Suppose a cord fastened to the house, from below, and pulled down by some one on the planet. Then of course the _house_ goes faster than its natural rate of falling: but the furniture—with our noble selves—would go on falling at their old pace, and would therefore be left behind.”
“Practically, we should rise to the ceiling,” said the Earl. “The inevitable result of which would be concussion of brain.”