I turned it over and over and cudgelled my brains; and then I had a brilliant idea. Was it a reed pen of which the point had been broken off? I knew that reed pens were still in use by draughtsmen of decorative leanings with an affection for the “fat line.” Could any of our friends be draughtsmen? This seemed the most probable solution of the difficulty, and the more I thought about it the more likely it seemed. Draughtsmen usually sign their work intelligibly, and even when they use a device instead of a signature their identity is easily traceable. Could it be that Mr. Graves, for instance, was an illustrator, and that Thorndyke had established his identity by looking through the works of all the well-known thick-line draughtsmen?