“And you will try to get those things, won’t you?” pleaded Loewe.

“I will think over the case.  But you understand, or Mr. Marchmont does, that this is hardly in my province.  I am a medical jurist, and this is not a medico-legal case.”

“Just what I told him,” said Marchmont.  “But you will do me a great kindness if you will look into the matter.  Make it a medico-legal case,” he added persuasively.

Thorndyke repeated his promise, and the two men took their departure.

For some time after they had left, my colleague remained silent, regarding the hat with a quizzical smile.  “It is like a game of forfeits,” he remarked at length, “and we have to find the owner of ‘this very pretty thing.’” He lifted it with a pair of forceps into a better light, and began to look at it more closely.

“Perhaps,” said he, “we have done Mr. Loewe an injustice, after all.  This is certainly a very remarkable hat.”

“It is as round as a basin,” I exclaimed.  “Why, the fellow’s head must have been turned in a lathe!”

Thorndyke laughed.  “The point,” said he, “is this.  This is a hard hat, and so must have fitted fairly, or it could not have been worn; and it was a cheap hat, and so was not made to measure.  But a man with a head that shape has got to come to a clear understanding with his hat.  No ordinary hat would go on at all.

“Now, you see what he has done—­no doubt on the advice of some friendly hatter.  He has bought a hat of a suitable size, and he has made it hot—­probably steamed it.  Then he has jammed it, while still hot and soft, on to his head, and allowed it to cool and set before removing it.  That is evident from the distortion of the brim.  The important corollary is, that this hat fits his head exactly—­is, in fact, a perfect mould of it; and this fact, together with the cheap quality of the hat, furnishes the further corollary that it has probably only had a single owner.

“And now let us turn it over and look at the outside.  You notice at once the absence of old dust.  Allowing for the circumstance that it had been out all night, it is decidedly clean.  Its owner has been in the habit of brushing it, and is therefore presumably a decent, orderly man.  But if you look at it in a good light, you see a kind of bloom on the felt, and through this lens you can make out particles of a fine white powder which has worked into the surface.”

He handed me his lens, through which I could distinctly see the particles to which he referred.

“Then,” he continued, “under the curl of the brim and in the folds of the hatband, where the brush has not been able to reach it, the powder has collected quite thickly, and we can see that it is a very fine powder, and very white, like flour.  What do you make of that?”

“I should say that it is connected with some industry.  He may be engaged in some factory or works, or, at any rate, may live near a factory, and have to pass it frequently.”