ed cab, whom he finally commissioned to convey us to a shop
in New Oxford Street. Having dismissed the cabman with his blessing and
a half-sovereign, he vanished into the shop, leaving me to gaze at the
lathes, drills, and bars of metal displayed in the window. Presently he
emerged with a small parcel, and explained, in answer to my inquiring
look: "A strip of tool steel and a block of metal for Polton."

His next purchase was rather more eccentric. We were proceeding along
Holborn when his attention was suddenly arrested by the window of a
furniture shop, in which was displayed a collection of obsolete French
small-arms--relics of the tragedy of 1870--which were being sold for
decorative purposes. After a brief inspection, he entered the shop, and
shortly reappeared carrying a long sword-bayonet and an old Chassepot
rifle.

"What may be the meaning of this martial display?" I asked, as we turned
down Fetter Lane.

"House protection," he replied promptly. "You will agree that a
discharge of musketry, followed by a bayonet charge, would disconcert
the boldest of burglars."

I laughed at the absurd picture thus drawn of the strenuous
house-protector, but nevertheless continued to speculate on the meaning
of my friend's eccentric proceedings, which I felt sure were in some way
related to the murder in Brackenhurst Chambers, though I could not trace
the connection.

After a late lunch, I hurried out to transact such of my business as had
been interrupted by the stirring events of the morning, leaving
Thorndyke busy with a drawing-board, squares, scale, and compasses,
making accurate, scaled drawings from his rough sketches; while Polton,
with the brown-paper parcel in his hand, looked on at him with an air of
anxious expectation.

As I was returning homeward in the evening by way of Mitre Court, I
overtook Mr. Marchmont, who was also bound for our chambers, and we
walked on together.

"I had a note from Thorndyke," he explained, "asking for a specimen of
handwriting, so I thought I would bring it along myself, and hear if he
has any news."

When we entered the chambers, we found Thorndyke in earnest consultation
with Polton, and on the table before them I observed, to my great
surprise, the dagger with which the murder had been committed.

[Illustration: THE ALUMINIUM DAGGER.]

"I have got you the specimen that you asked for," said Marchmont. "I
didn't think I should be able to, but, by a lucky chance, Curtis k