n,
sprang up and into the room once more, all with the energy of the
hunter who is at the very heels of his quarry. The lamp, which was an
ordinary standard, he examined with minute care, making certain
measurements upon its bowl. He carefully scrutinized with his lens the
talc shield which covered the top of the chimney and scraped off some
ashes which adhered to its upper surface, putting some of them into an
envelope, which he placed in his pocketbook. Finally, just as the
doctor and the official police put in an appearance, he beckoned to the
vicar and we all three went out upon the lawn.

"I am glad to say that my investigation has not been entirely barren,"
he remarked. "I cannot remain to discuss the matter with the police,
but I should be exceedingly obliged, Mr. Roundhay, if you would give
the inspector my compliments and direct his attention to the bedroom
window and to the sitting-room lamp. Each is suggestive, and together
they are almost conclusive. If the police would desire further
information I shall be happy to see any of them at the cottage. And
now, Watson, I think that, perhaps, we shall be better employed
elsewhere."

It may be that the police resented the intrusion of an amateur, or that
they imagined themselves to be upon some hopeful line of investigation;
but it is certain that we heard nothing from them for the next two
days. During this time Holmes spent some of his time smoking and
dreaming in the cottage; but a greater portion in country walks which
he undertook alone, returning after many hours without remark as to
where he had been. One experiment served to show me the line of his
investigation. He had bought a lamp which was the duplicate of the one
which had burned in the room of Mortimer Tregennis on the morning of
the tragedy. This he filled with the same oil as that used at the
vicarage, and he carefully timed the period which it would take to be
exhausted. Another experiment which he made was of a more unpleasant
nature, and one which I am not likely ever to forget.

"You will remember, Watson," he remarked one afternoon, "that there is
a single common point of resemblance in the varying reports which have
reached us. This concerns the effect of the atmosphere of the room in
each case upon those who had first entered it. You will recollect that
Mortimer Tregennis, in describing the episode of his last visit to his
brother's house, remarked that the doctor on entering