This is the tale of a quasi-mechanical word puzzle propounded by Sam Loyd, a famous British puzzler, to Henry Ernest Dudeney, another famous British puzzler, around the turn of the century. Dudeney is best known for his work in the field of mathematical recreations, but he was also interested in word curiosities, and the Switch Puzzle is one of many included in his book, The World's Best Word Puzzles, published by the "Daily News" Publications Department, London, 1925.
Bergerson, Howard W.
"Dudeney's Switch Puzzle,"
Word Ways: Vol. 1
, Article 5.
Available at: http://digitalcommons.butler.edu/wordways/vol1/iss1/5