“I don’t think I will leave it, after all,” he said, slipping the folded paper into his pocket.  “No.  Tell him I called—­Mr. Horace Budge—­and say I will look in again in a day or two.”

The youth watched our exit with an air of perplexity, and he even came out on to the landing, the better to observe us over the balusters; until, unexpectedly catching Thorndyke’s eye, he withdrew his head with remarkable suddenness, and retired in disorder.

To tell the truth, I was now little less perplexed than the office-boy by Thorndyke’s proceedings; in which I could discover no relevancy to the investigation that I presumed he was engaged upon:  and the last straw was laid upon the burden of my curiosity when he stopped at a staircase window, drew the note out of his pocket, examined it with his lens, held it up to the light, and chuckled aloud.

“Luck,” he observed, “though no substitute for care and intelligence, is a very pleasant addition.  Really, my learned brother, we are doing uncommonly well.”

When we reached the hall, Thorndyke stopped at the housekeeper’s box, and looked in with a genial nod.

“I have just been up to see Mr. Barlow,” said he.  “He seems to have left quite early.”

“Yes, sir,” the man replied.  “He went away about half-past eight.”

“That was very early; and presumably he came earlier still?”

“I suppose so,” the man assented, with a grin; “but I had only just come on when he left.”

“Had he any luggage with him?”

“Yes, sir.  There was two cases, a square one and a long, narrow one, about five foot long.  I helped him to carry them down to the cab.”

“Which was a four-wheeler, I suppose?”

“Yes, sir.”

“Mr. Barlow hasn’t been here very long, has he?” Thorndyke inquired.

“No.  He only came in last quarter-day—­about six weeks ago.”

“Ah well!  I must call another day.  Good-morning;” and Thorndyke strode out of the building, and made directly for the cab-rank in the adjoining street.  Here he stopped for a minute or two to parley with the driver of a four-wheeled 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.