n. Knowing my methods as
you do, you were, of course, conscious of the somewhat clumsy water-pot
expedient by which I obtained a clearer impress of his foot than might
otherwise have been possible. The wet, sandy path took it admirably.
Last night was also wet, you will remember, and it was not
difficult--having obtained a sample print--to pick out his track among
others and to follow his movements. He appears to have walked away
swiftly in the direction of the vicarage.

"If, then, Mortimer Tregennis disappeared from the scene, and yet some
outside person affected the card-players, how can we reconstruct that
person, and how was such an impression of horror conveyed? Mrs. Porter
may be eliminated. She is evidently harmless. Is there any evidence
that someone crept up to the garden window and in some manner produced
so terrific an effect that he drove those who saw it out of their
senses? The only suggestion in this direction comes from Mortimer
Tregennis himself, who says that his brother spoke about some movement
in the garden. That is certainly remarkable, as the night was rainy,
cloudy, and dark. Anyone who had the design to alarm these people
would be compelled to place his very face against the glass before he
could be seen. There is a three-foot flower-border outside this
window, but no indication of a footmark. It is difficult to imagine,
then, how an outsider could have made so terrible an impression upon
the company, nor have we found any possible motive for so strange and
elaborate an attempt. You perceive our difficulties, Watson?"

"They are only too clear," I answered with conviction.

"And yet, with a little more material, we may prove that they are not
insurmountable," said Holmes. "I fancy that among your extensive
archives, Watson, you may find some which were nearly as obscure.
Meanwhile, we shall put the case aside until more accurate data are
available, and devote the rest of our morning to the pursuit of
neolithic man."

I may have commented upon my friend's power of mental detachment, but
never have I wondered at it more than upon that spring morning in
Cornwall when for two hours he discoursed upon celts, arrowheads, and
shards, as lightly as if no sinister mystery were waiting for his
solution. It was not until we had returned in the afternoon to our
cottage that we found a visitor awaiting us, who soon brought our minds
back to the matter in hand. Neither of us needed to be to