“The question as to whether Graves and Jeffrey were identical admitted of fairly easy disproof; for if Graves was still alive, he could not be Jeffrey. It was an important question and I resolved to test it without delay. That night, Jervis and I plotted out the chart, and on the following morning we located the house. But it was empty and to let. The birds had flown, and we failed to discover whither they had gone.

“However, we entered the house and explored. I have told you about the massive bolts and fastenings that we found on the bedroom doors and window, showing that the room had been used as a prison. I have told you of the objects that we picked out of the dust-heap under the grate. Of the obvious suggestion offered by the Japanese brush and the bottle of ‘spirit gum’ or cement, I need not speak now; but I must trouble you with some details concerning the broken spectacles. For here we had come upon the crucial fact to which, as I have said, all sound inductive reasoning brings one sooner or later.