My knowledge of the history of word ladders comes from two books "The Magic of Lewis Carroll" by John Fisher (1973), and "The Oxford Guide to Word Games" by Tony Augarde (1984). It is not necessary to describe word ladders to the readers of Word Ways; in any event the concept should be ovbious from the examples. Carroll started writing about what he called Doublets in 1879; he had originally called them Word Links. The idea, of course, is to find the shortest ladder between a pair of words.
Gordon, Leonard J.
"Lewis Carroll's Word Ladders,"
Word Ways: Vol. 22
, Article 10.
Available at: http://digitalcommons.butler.edu/wordways/vol22/iss4/10