The words were so faintly printed that it was not surprising that I had not noticed them at first.  Pugh explained.

“I observed that box on a tray outside a second-hand furniture shop.  It struck my eye.  I took it up.  I examined it.  I inquired of the proprietor of the shop in what the puzzle lay.  He replied that that was more than he could tell me.  He himself had made several attempts to open the box, and all of them had failed.  I purchased it.  I took it home.  I have tried, and I have failed.  I am aware, Tress, of how you pride yourself upon your ingenuity.  I cannot doubt that, if you try, you will not fail.”

While Pugh was prosing, I was examining the box.  It was at least well made.  It weighed certainly under two ounces.  I struck it with my knuckles; it sounded hollow.  There was no hinge; nothing of any kind to show that it ever had been opened, or, for the matter of that, that it ever could be opened.  The more I examined the thing, the more it whetted my curiosity.  That it could be opened, and in some ingenious manner, I made no doubt—­but how?

The box was not a new one.  At a rough guess I should say that it had been a box for a good half century; there were certain signs of age about it which could not escape a practiced eye.  Had it remained unopened all that time?  When opened, what would be found inside?  It sounded hollow; probably nothing at all—­who could tell?

It was formed of small pieces of inlaid wood.  Several woods had been used; some of them were strange to me.  They were of different colors; it was pretty obvious that they must all of them have been hard woods.  The pieces were of various shapes—­hexagonal, octagonal, triangular, square, oblong, and even circular.  The process of inlaying them had been beautifully done.  So nicely had the parts been joined that the lines of meeting were difficult to discover with the naked eye; they had been joined solid, so to speak.  It was an excellent example of marquetry.  I had been over-hasty in my deprecation; I owed as much to Pugh.

“This box of yours is better worth looking at than I first supposed.  Is it to be sold?”

“No, it is not to be sold.  Nor”—­he “fixed” me with his spectacles—­“is it to be given away.  I have brought it to you for the simple purpose of ascertaining if you have ingenuity enough to open it.”

“I will engage to open it in two seconds—­with a hammer.”

“I dare say. I will open it with a hammer.  The thing is to open it without.”

“Let me see.”  I began, with the aid of a microscope, to examine the box more closely.  “I will give you one piece of information, Pugh.  Unless I am mistaken, the secret lies in one of these little pieces of inlaid wood.  You push it, or you press it, or something, and the whole affair flies open.”

“Such was my own first conviction.  I am not so sure of it now.  I have pressed every separate piece of wood; I have tried to move each piece in every direction.  No result has followed.  My theory was a hidden spring.”