"Oh, that's impossible. Do you know what a glass eye is like?"
"Well, no, I have never seen one, unless fixed in a person's head."
Striver laughed. "I had the same idea about a piece of paper," he explained carefully, "and went to an optician in Tarhaven to examine an eye. I suppose you think--as I did--that an artificial eye is the shape and size and the fatness of an almond."
"Something like that," I admitted, "with the paper enclosed within."
Striver laughed again. "It's shaped exactly like a small sea-shell: simply a curve of thin glass, convex and concave, and fits into the socket like a--a--what shall I say?--like a cupping-glass."
"Humph! In that case, it would be impossible to conceal a piece of paper behind it without damage."
"Of course, taking also into consideration the smallness of the eye. The only thing I can think of," he added, half to himself, "is that there is a plan or some writing on the back part, which reveals the whereabouts of this money."
"But there's no space to write in," I objected, considerably interested.
"Why not. Writing done with a magnifying-glass, you know. I have seen the Lord's Prayer written on a sixpence."
I nodded. "There may be something in what you say," I admitted, "and, as it appears that Mrs. Caldershaw was murdered for the sake of the eye, it must have some value. Perhaps," I added with a brilliant afterthought, "she hid a diamond behind it."