-box is usually coated."

Fanferlot listened with open mouth to this explanation. At the last
words, he slapped his forehead violently, and cried--of
himself--"Imbecile!"

"You are right," replied M. Lecoq--"imbecile. What! With such a guide
before your eyes, you neglected it and drew no conclusion! This is the
one clue to the affair. If I find the guilty one, it will be by means
of this mark, and I will find him; I am determined to do it."

When away from Lecoq, Fanferlot, nicknamed the Squirrel, often
slandered and defied him; but in his presence he yielded to the
magnetic influence which this extraordinary man exercised upon all who
came near him.

Such exact information and such minute details perplexed his mind.
Where and how could M. Lecoq have gathered them?

"You have been studying the case, master?"

"Probably. But as I am not infallible, I may have let some valuable
point escape me. Sit down, and tell me all that you know."

One could not prevaricate with M. Lecoq. Therefore Fanferlot told the
exact truth,--which was not his custom. However, before the end of his
recital, his vanity prevented him from telling how he had been tricked
by Mademoiselle Nina Gypsy and the stout gentleman.

Unfortunately, M. Lecoq was never informed by halves.

"It seems to me, Master Squirrel," he said, "that you have forgotten
something. How far did you follow the empty cab?"

Fanferlot, despite his assurance, blushed to his ears, and dropped his
eyes like a schoolboy caught in a guilty act.

"O patron," he stammered, "you know that too? How could you have--"

Suddenly a thought flashed through his brain: he stopped, and bounding
from his chair, cried, "Oh, I am sure--that stout gentleman with the
red whiskers was you!"

Fanferlot's surprise gave such a ridiculous expression to his face
that M. Lecoq could not help smiling.

"Then it _was_ you," continued the amazed detective, "it was you, that
fat man at whom I stared. I did not recognize you! Ah, patron, what an
actor you would make if you pleased! And _I_ was disguised also!"

"But very poorly, my poor boy, I tell you for your own good. Do you
think a heavy beard and a blouse sufficient to evade detection? But
the eye, stupid fellow, the eye! It is the eye that must be changed.
There is the secret."

This theory of disguise explains why the official, lynx-like Lecoq
never appeared at the police office without his gold spectacles.

"But then, patron," contin