“Exactly. The idea crossed my mind. But we found the knife some feet away from the body, so that seems impossible. Then, of course, there are the man’s own dying words. And, finally, there was this very important piece of evidence which was found clasped in the dead man’s right hand.”

From his pocket Stanley Hopkins drew a small paper packet. He unfolded it and disclosed a golden pince-nez, with two broken ends of black silk cord dangling from the end of it. “Willoughby Smith had excellent sight,” he added. “There can be no question that this was snatched from the face or the person of the assassin.”

Sherlock Holmes took the glasses into his hand, and examined them with the utmost attention and interest. He held them on his nose, endeavoured to read through them, went to the window and stared up the street with them, looked at them most minutely in the full light of the lamp, and finally, with a chuckle, seated himself at the table and wrote a few lines upon a sheet of paper, which he tossed across to Stanley Hopkins.