“Our friend seems to have put you out,” he remarked.

“He put me out literally.  If I had stayed much longer I should have punched his head.”

“In that case,” said Thorndyke, “I am glad you didn’t stay.  But come down and let me introduce you.”

“No, thank you.  I’ve had enough of him for the present.”

“But I have a very special reason for wishing to introduce you.  I think you will get some information from him that will interest you very much; and you needn’t quarrel with a man for being of a cheerful disposition.”

“Cheerful be hanged!” I exclaimed.  “I don’t call a man cheerful because he behaves like a gibbering idiot.”

To this Thorndyke made no reply but a broad and appreciative smile, and we descended to the lower floor.  As we entered the room, the stranger rose, and, glancing in an embarrassed way from one of us to the other, suddenly broke out into an undeniable snigger.  I looked at him sternly, and Thorndyke, quite unmoved by his indecorous behaviour, said in a grave voice: 

“Let me introduce you, Jervis; though I think you have met this gentleman before.”

“I think not,” I said stiffly.

“Oh yes, you have, sir,” interposed the stranger; and, as he spoke, I started; for the voice was uncommonly like the familiar voice of Polton.

I looked at the speaker with sudden suspicion.  And now I could see that the flaxen hair was a wig; that the beard had a decidedly artificial look, and that the eyes that beamed through the spectacles were remarkably like the eyes of our factotum.  But the blotchy face, the bulbous nose and the shaggy, overhanging eyebrows were alien features that I could not reconcile with the personality of our refined and aristocratic-looking little assistant.

“Is this a practical joke?” I asked.

“No,” replied Thorndyke; “it is a demonstration.  When we were talking this morning it appeared to me that you did not realize the extent to which it is possible to conceal identity under suitable conditions of light.  So I arranged, with Polton’s rather reluctant assistance, to give you ocular evidence.  The conditions are not favourable—­which makes the demonstration more convincing.  This is a very well-lighted room and Polton is a very poor actor; in spite of which it has been possible for you to sit opposite him for several minutes and look at him, I have no doubt, very attentively, without discovering his identity.  If the room had been lighted only with a candle, and Polton had been equal to the task of supporting his make-up with an appropriate voice and manner, the deception would have been perfect.”

“I can see that he has a wig on, quite plainly,” said I.

“Yes; but you would not in a dimly lighted room.  On the other hand, if Polton were to walk down Fleet Street at mid-day in this condition, the make-up would be conspicuously evident to any moderately observant passer-by.  The secret of making up consists in a careful adjustment to the conditions of light and distance in which the make-up is to be seen.  That in use on the stage would look ridiculous in an ordinary room; that which would serve in an artificially lighted room would look ridiculous out of doors by daylight.”