A Traveler in Time by August Derleth

"Tell me what time is," said Harrigan one late summer afternoon in a Madison Street bar. "I'd like to know."

"A dimension," I answered. "Everybody knows that."

"All right, granted. I know space is a dimension and you can move forward or back in space. And, of course, you keep on aging all the time."

"Elementary," I said.

"But what happens if you can move backward or forward in time? Do you age or get younger, or do you keep the status quo?"

"I'm not an authority on time, Tex. Do you know anyone who traveled in time?"

Harrigan shrugged aside my question. "That was the thing I couldn't get out of Vanderkamp, either. He presumed to know everything else."

"Vanderkamp?"

"He was another of those strange people a reporter always runs into. Lived in New York—downtown, near the Bowery. Man of about forty, I'd say, but a little on the old-fashioned side. Dutch background, and hipped on the subject of New Amsterdam, which, in case you don't know, was the original name of New York City."

"Don't mind my interrupting," I cut in. "But I'm not quite straight on what Vanderkamp has to do with time as dimension."

"Oh, he was touched on the subject. He claimed to travel in it. The fact is, he invented a time-traveling machine."