of
many critical communications, and had shown great ingenuity in
devising and unravelling ciphers. On this subject a somewhat
protracted discussion arose. I inclined to the doctrine of Poe, that
no cipher can be devised which cannot be detected by an experienced
hand; my friends indicated simple methods of defeating the processes
on which decipherers rely.

"Poe's theory," said the Major, "depends upon the frequent recurrence
of certain letters, syllables, and brief words in any given language;
for instance, of _e_'s and _t_'s, _tion_ and _ed_, _a_, _and_, and
_the_ in English. Now it is perfectly easy to introduce abbreviations
for each of the common short words and terminations, and equally easy
to baffle the decipherer's reliance thereon by inserting meaningless
symbols to separate the words; by employing two signs for a common
letter, or so arranging your cipher that no one shall without extreme
difficulty know which marks stand for single and which for several
combined letters, where one letter ends and another begins."

After some debate, Colonel A---- wrote down and handed me two lines in
a cipher whose character at once struck me as very remarkable.

"I grant," said I, "that these hieroglyphics might well puzzle a more
practised decipherer than myself. Still, I can point out even here a
clue which might help detection. There occur, even in these two lines,
three or four symbols which, from their size and complication, are
evidently abbreviations. Again, the distinct forms are very few, and
have obviously been made to serve for different letters by some slight
alterations devised upon a fixed rule. In a word, the cipher has been
constructed upon a general principle; and though it may take a long
time to find out what that principle is, it affords a clue which,
carefully followed out, will probably lead to detection."

"You have perceived," said Colonel A----, "a fact which it took me
very long to discover. I have not deciphered all the more difficult
passages of the manuscript from which I took this example; but I have
ascertained the meaning of all its simple characters, and your
inference is certainly correct."

Here he stopped abruptly, as if he thought he had said too much, and
the subject dropped.

We reached New York early in the morning and separated, having
arranged to visit that afternoon a celebrated "spiritual" medium who
was then giving _seances_ in the Empire City, and of whom my friend
had