been found on the soft ground. The man didn't have wings;
he walked; but he walked on the gravel which left no impression of his
tread. The gravel has, in fact, been trodden by many other feet, since
the path is the most direct way between the pavilion and the chateau.
As to the thicket, made of the sort of shrubs that don't flourish in the
rough season--laurels and fuchsias--it offered the murderer a sufficient
hiding-place until it was time for him to make his way to the pavilion.
It was while hiding in that clump of trees that he saw Monsieur and
Mademoiselle Stangerson, and then Daddy Jacques, leave the pavilion.
Gravel has been spread nearly, very nearly, up to the windows of the
pavilion. The footprints of a man, parallel with the wall--marks which
we will examine presently, and which I have already seen--prove that he
only needed to make one stride to find himself in front of the vestibule
window, left open by Daddy Jacques. The man drew himself up by his hands
and entered the vestibule."

"After all it is very possible," I said.

"After all what? After all what?" cried Rouletabille.

I begged of him not to be angry; but he was too much irritated to listen
to me and declared, ironically, that he admired the prudent doubt
with which certain people approached the most simple problems, risking
nothing by saying "that is so, or 'that is not so." Their intelligence
would have produced about the same result if nature had forgotten to
furnish their brain-pan with a little grey matter. As I appeared vexed,
my young friend took me by the arm and admitted that he had not meant
that for me; he thought more of me than that.

"If I did not reason as I do in regard to this gravel," he went on, "I
should have to assume a balloon!--My dear fellow, the science of the
aerostation of dirigible balloons is not yet developed enough for me to
consider it and suppose that a murderer would drop from the clouds! So
don't say a thing is possible, when it could not be otherwise. We know
now how the man entered by the window, and we also know the moment at
which he entered,--during the five o'clock walk of the professor and his
daughter. The fact of the presence of the chambermaid--who had come to
clean up The Yellow Room--in the laboratory, when Monsieur Stangerson
and his daughter returned from their walk, at half-past one, permits
us to affirm that at half-past one the murderer was not in the chamber
under the bed, unless he was in c