Bill was back by that time and I sent him out with another gadget.
We kept on like that for quite a while and Bill was beginning to get disgusted with me. But finally I sprinkled the dirt and it stayed.
“Bill,” I said, “you remember the last thing you took out?”
“Sure.”
“Well, go out and bring it back again.”
He got it and, as soon as he reached the door of the den, the dirt disappeared.
“Well, that’s it,” I said.
“That’s what?” asked Helen.
I pointed to the contraption Bill had in his hand. “That.
Throw away your vacuum cleaner. Burn up the dustcloth.