I was refreshing my memory of The Footprints on the Ceiling by Clayton Rawson. First published in 1939. The second of a series of four mystery novels featuring The Great Merlini. (There is also a book collecting 12 shorter stories with the same protagonist.) Merlini is presented to us as a famous stage magician who recently retired from life on the road to run a magic shop in Manhattan. The first-person narrator of these mysteries is Ross Harte, a young journalist who essentially plays the role of Watson to Merlini's Sherlock Holmes.
As you might guess from the title, the plot of this mystery includes the need for an explanation as to how someone left fresh footprints on the ceiling of a room. If you took those tracks at face value, it would appear that a man (or someone or something wearing a man's shoes) had walked up a wall, and then proceeded to walk upside-down along the ceiling until reaching a large, open window which overlooked a forty-foot drop. (No one, dead or alive, can be seen down at the base of the cliff.) Explaining who left those footprints, and how he did it, is not the most urgent problem to be solved -- there are also a few corpses to be accounted for -- but the sight of those footprints prompts Merlini to get nostalgic about something similar in a science fiction story which he had once read. Here is the relevant passage, with Merlini speaking first.
"Years ago," he said reflectively, "when barber shops were supplied with reading matter instead of picture magazines, I ran across a story in one of the weird-story pulps that deserved a better fate. Its hero was struck by a bolt of lightning. Instead of killing him, it played merry hell with his personal gravitational field. Twisted it all around. His friends just managed to get him indoors before he floated off. But they couldn't keep him down. He was, suddenly, the exception that proved Isaac Newton's little rule. The earth repelled rather than attracted him. Awful predicament. They had to screw a table, chairs, and a bed to the ceiling, and he lived there, upside down. For him, the ceiling was the floor, and everything that wasn't fastened down promptly fell up -- to the floor. He had to eat off the underside of his table and drink his coffee with the cup bottomside up. Inconvenient as anything. And the story ended on a lovely little note of horror. Can you guess what?"
"He went to Hollywood," I hazarded.
"Worse," Merlini said. "He looked out the window. Can you visualize what he saw? Trees growing upside down. The earth, solid and heavy, pressing down horribly, close overhead. And below, a sheer, terrifying drop of uncounted millions of light years -- the whole length of the universe! It got him finally. His friends came in one day and found he'd disappeared. The window was open at the top."
Clayton Rawson wrote the Merlini stories and various other works of fiction -- mostly mysteries, which is not surprising when you consider that Wikipedia says he was one of the four co-founders of the Mystery Writers of America -- but he never seems to have written any science fiction or fantasy. (The ISFDB database has never heard of him.) So I don't think he invented the plot he has Merlini describe in the above passage. I consider it far more likely that he was simply summarizing something he had once read in a pulp magazine; possibly but not necessarily having encountered it in a barber shop. Since the book was published in 1939, and Merlini attributes the story to "years ago," I suspect the tale was first published in the 1920s or perhaps the early 1930s.
I don't remember ever encountering that story in any collections of "pre-Golden Age" science fiction, nor in any volumes collecting several short stories by a single author. So I suspect that the author never became a big name in science fiction, but I could be wrong. At any rate, I would like to see the story myself, and find out if the author wrote other stories exploring the logical ramifications of improbable situations. Does anyone recognize this tale from Merlini's summary of how it depicted the problems associated with having your personal gravity reversed?