"If the tenant of New Inn was John, then Jeffrey must be elsewhere, since his concealment at the inn was clearly impossible. But he could not have been far away, for he had to be producible at short notice whenever the death of Mrs. Wilson should make the production of his body necessary. But if he was producible, his person must have been in the possession or control of John. He could not have been at large, for that would have involved the danger of his being seen and recognized. He could not have been in any institution or place where he would be in contact with strangers. Then he must be in some sort of confinement. But it is difficult to keep an adult in confinement in an ordinary house. Such a proceeding would involve great risk of discovery and the use of violence which would leave traces on the body, to be observed and commented on at the inquest. What alternative method could be suggested?
"The most obvious method is that of keeping the prisoner in such a state of debility as would confine him to his bed. But such debility could be produced by only starvation, unsuitable food, or chronic poisoning. Of these alternatives, poisoning is much more exact, more calculable in its effect and more under control. The probabilities, then, were in favour of chronic poisoning.
"Having reached this stage, I recalled a singular case which Jervis had mentioned to me and which seemed to illustrate this method. On our return home I asked him for further particulars, and he then gave me a very detailed description of the patient and the circumstances. The upshot was rather startling. I had looked on his case as merely illustrative, and wished to study it for the sake of the suggestions that it might offer. But when I had heard his account, I began to suspect that there was something more than mere parallelism of method. It began to look as if his patient, Mr. Graves, might actually be Jeffrey Blackmore.
"The coincidences were remarkable. The general appearance of the patient tallied completely with Mr. Stephen's description of his uncle Jeffrey. The patient had a tremulous iris in his right eye and had clearly suffered from dislocation of the crystalline lens. But from Mr. Stephen's account of his uncle's sudden loss of sight in the right eye after a fall, I judged that Jeffrey had also suffered from dislocation of the lens and therefore had a tremulous iris in the right eye. The patient, Graves, evidently had defective vision in his left eye, as proved by the marks made behind his ears by the hooked side-bars of his spectacles; for it is only on spectacles that are intended for constant use that we find hooked side-bars. But Jeffrey had defective vision in his left eye and wore spectacles constantly. Lastly, the patient Graves was suffering from chronic morphine poisoning, and morphine was found in the body of Jeffrey.
"Once more, it appeared to me that there were too many coincidences.
"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.
"The spectacles were of a rather peculiar pattern. The frames were of the type invented by Mr. Stopford of Moorfields and known by his name. The right eye-piece was fitted with plain glass, as is usual in the case of a blind, or useless, eye. It was very much shattered, but its character was obvious. The glass of the left eye was much thicker and fortunately less damaged, so that I was able accurately to test its refraction.
"When I reached home, I laid the pieces of the spectacles together, measured the frames very carefully, tested the left eye-glass, and wrote down a full description such as would have been given by the surgeon to the spectacle-maker. Here it is, and I will ask you to note it carefully.
"'Spectacles for constant use. Steel frame, Stopford's pattern, curl sides, broad bridge with gold lining. Distance between centres, 6.2 centimetres; extreme length of side-bars, 13.3 centimetres.