One of the best in the tradition of Gardner and Lehrer, those who mixed mathematics with language and had endless fun with both, Lewis Carroll invented a now-common type of puzzle known as the word-ladder, but which he dubbed "doublets." Altering one letter at a time, change one word into another.
Galef, Daniel W.
Word Ways: Vol. 47
, Article 17.
Available at: http://digitalcommons.butler.edu/wordways/vol47/iss3/17