ing that if Mr.
Douglas defended himself with the hammer, he might have left his mark
upon the murderer before he dropped it on the mat. But there was no
stain."

"That, of course, proves nothing at all," remarked Inspector MacDonald.
"There has been many a hammer murder and no trace on the hammer."

"Quite so. It doesn't prove it wasn't used. But there might have been
stains, and that would have helped us. As a matter of fact there were
none. Then I examined the gun. They were buckshot cartridges, and, as
Sergeant Wilson pointed out, the triggers were wired together so that,
if you pulled on the hinder one, both barrels were discharged. Whoever
fixed that up had made up his mind that he was going to take no chances
of missing his man. The sawed gun was not more than two foot long--one
could carry it easily under one's coat. There was no complete maker's
name; but the printed letters P-E-N were on the fluting between the
barrels, and the rest of the name had been cut off by the saw."

"A big P with a flourish above it, E and N smaller?" asked Holmes.

"Exactly."

"Pennsylvania Small Arms Company--well-known American firm," said
Holmes.

White Mason gazed at my friend as the little village practitioner looks
at the Harley Street specialist who by a word can solve the difficulties
that perplex him.

"That is very helpful, Mr. Holmes. No doubt you are right. Wonderful!
Wonderful! Do you carry the names of all the gun makers in the world in
your memory?"

Holmes dismissed the subject with a wave.

"No doubt it is an American shotgun," White Mason continued. "I seem
to have read that a sawed-off shotgun is a weapon used in some parts of
America. Apart from the name upon the barrel, the idea had occurred to
me. There is some evidence then, that this man who entered the house and
killed its master was an American."

MacDonald shook his head. "Man, you are surely travelling overfast,"
said he. "I have heard no evidence yet that any stranger was ever in the
house at all."

"The open window, the blood on the sill, the queer card, the marks of
boots in the corner, the gun!"

"Nothing there that could not have been arranged. Mr. Douglas was an
American, or had lived long in America. So had Mr. Barker. You don't
need to import an American from outside in order to account for American
doings."

"Ames, the butler--"

"What about him? Is he reliable?"

"Ten years with Sir Charles Chandos--as solid as a rock. He has