This information on potential answers to Lewis Carroll's riddle was sent to me by Sean K. who said he got it from http://math.smsu.edu/~les/carroll.html
Carroll did not have an answer in mind when he wrote the riddle. He later came up with:
"Because it can produce a few notes, though they are very
flat; and it is nevar put wrong end in front!"
[Note the variant spelling of "never".]
Other authors have come up with:
"Because Poe wrote on both." [Sam Loyd]
"Because the notes for which they
are noted are not noted for being musical
notes." [Sam Loyd]
"Because it slopes with a flap." [Cyril Pearson]
"Because both have quills dipped in ink." [David
Jodrey]
"Because they both have two eyes." [Izumi Yasui]
"Because there is a "B" in both." [E.V. Rieu]
