Not Mark Twain, but (believe it or not) Dolton Edwards in Astounding Science Fiction, Sept 1946.
"Dolton" was an amusing pseudonym. See this thread from a few years ago:
https://news.ycombinator.com/item?id=23587507
Some (un?)reliable sources on the Internet claim that it was actually written by a man named M.J. Shields and published as a letter to The Economist in the 1940s
Some (un?)reliable sources on the Internet claim that it was actually written by a man named M.J. Shields and published as a letter to The Economist in the 1940s