It was apparent to him that this strange old man had read the secret and method of the murder at a glance. Not two minutes had he been in the room, and the tone of his involuntary exclamation announced that he had solved the riddle.
How had he done it? What magic was there in this old man’s vision that was lacking in his own? He had marked in his mind every movement, every glance of Soft Sam—the door that had hardly arrested his slow walk into the room, the fire-place he had only touched, and finally, the window where the exclamation had taken place.
What was there so noticeable about the window to excite the old man? He went towards it, and looked it over carefully. Four squares of glass, two in each sash, secured by a common window-fastener, that was now closed, as Police-Constable Hobbs had always seen it.
He opened the window, and scrutinized it carefully.
What were these two small lines that cut the paint of the lower bar of the upper sash, immediately under the fastener?
He looked at them carefully. At the edges the cuts were deeper. They were such marks as are seen on the tops of corks of lemonade bottles. And the marks were recent.
“That’s it!” cried Hobbs, joyfully. “That’s what he saw! What a fool I was never to have opened the window! They are hardly to be seen when it is closed.”
But his triumph was only for a moment. These marks may have explained everything to the old man; they were so far silent to Constable Hobbs. He had, however, found a clue, and he started to think to put this and that together.
The window had, so far, never entered his calculations; there were so many objections to be overcome in that direction. Nevertheless, putting them aside, he devoted all his thought to the window and its lock. Drawing out his pocket-knife, he found it was an easy job to press back the little brass bar when it was open. He remembered doing the same trick as a boy, when he happened to be locked out of his own home. But with the knife he found it quite impossible to shut the lock again from the outside.
Descending to the kitchen of the house he procured a piece of very fine wire, and, having borrowed a ladder, mounted to the window from the outside. He had previously again closed the window. He now readily opened it as before, with his knife pushed up between the junction of the two sashes and pressed sideways. Raising the lower sash and bending his wire in the form of a loop, he was able with a little dexterity to pass it over the knob of the catch; holding the two ends of the wire in one hand he drew down the lower sash, and then by a sideway pull easily pulled the little brass bar out again.