Denis Crutch (Jabberwocky, Winter 1976) reported an astonishing discovery. In the 1896 edition of Alice, Carroll wrote a new preface in which he gave what he considered the best answer to the riddle: “Because it can produce a few notes, tho they are very flat; and it is nevar put with the wrong end in front.” Note the spelling of “never” as “nevar.” Carroll clearly intended to spell “raven” backwards. The word was corrected to “never” in all later printings, perhaps by an editor who fancied he had caught a printer’s error. Because Carroll died soon after this “correction” destroyed the ingenuity of his answer, the original spelling was never restored. Whether Carroll was aware of the damnage done to his clever answer is not known.
Lewis Carroll; Martin Gardner. The Annotated Alice, The Definitive Edition. New York, W. W. Norton & Company, 2000. Chapter VII: A Mad Tea-Party; note 5 (p. 72).