he
next morning when he entered the office.

"No! You're jesting," I answered, convinced, at the same time, that he
was in earnest.

"I'll soon show you," was his exultant response.

"How was it you struck the key?"

"That is hard to tell, more than you can explain how it is, after you
have puzzled your brain for a long time over an arithmetical problem, it
suddenly becomes clear to you."

He sat down by my desk.

"I figured and studied, and tried those letters every way I could think
of until midnight, and was on the point of going to bed, when the whole
thing flashed upon me. You know, Mr. Melville, that in trying to unravel
a cipher, the first thing necessary is to find the key-word, for it must
be there somewhere; and if you look sharp enough it will reveal itself.
One single letter gave it to me."

"How was that?"

"If you will look at the telegram," said Ben, spreading it out before me,
"you will notice that in one instance only is a single letter seen
standing by itself. That is the letter 'b,' which I concluded must stand
for the article 'a,' for I know of no other, unless it is 'I.' Now, the
letter 'b' is the second one in the alphabet, and stands next in order to
'a.' If this system is followed throughout the cipher, we have only to
take, instead of the letters as written, the next in order as they occur
in the alphabet. But when I tried it on the following word, it failed
entirely. Luckily I tested the second in the same manner, and I was
surprised to find it made a perfect word, viz.: 'chance.' The third came
to naught, but the fourth developed into 'your.' That proved that every
other word of the message was constructed in this manner, and it did not
take me long to bring them out into good English. This was a big help, I
can tell you, and it was not long before I discovered that in the
alternate words the system reversed; that is, instead of taking the
letter immediately succeeding, the writer had used that which immediately
precedes it in the alphabet. Applying this key to the telegram, it read
thus:

"'Must wait till fall; Sam has a better chance south. Your bank will
keep.'"

"Now," added Ben, who was warranted in feeling jubilant over his success,
"that is a very ordinary cipher--one which hundreds would make out
without trouble. Had the writer run his letters all together--that is,
without any break between the words--I would have been stumped. Besides,
he uses no blind words, as he ough