"But very superficial," said Holmes. "We come now, however, to a point which is of importance. You may not be aware that the deduction of a man's age from his writing is one which has been brought to considerable accuracy by experts. In normal cases one can place a man in his true decade with tolerable confidence. I say normal cases, because ill-health and physical weakness reproduce the signs of old age, even when the invalid is a youth. In this case, looking at the bold, strong hand of the one, and the rather broken-backed appearance of the other, which still retains its legibility, although the t's have begun to lose their crossings, we can say that the one was a young man, and the other was advanced in years without being positively decrepit."
"There is a further point, however, which is subtler and of greater interest. There is something in common between these hands. They belong to men who are blood-relatives. It may be most obvious to you in the Greek e's, but to me there are many small points which indicate the same thing. I have no doubt at all that a family mannerism can be traced in these two specimens of writing. I am only, of course, giving you the leading results now of my examination of the paper. There were twenty-three other deductions which would be of more interest to experts than to you. They all tended to deepen the impression upon my mind that the Cunninghams, father and son, had written this letter.
"Having got so far, my next step was, of course, to examine into the details of the crime and to see how far they would help us. I went up to the house with the Inspector, and saw all that was to be seen. The wound upon the dead man was, as I was able to determine with absolute confidence, fired from a revolver at the distance of something over four yards. There was no powder-blackening on the clothes. Evidently, therefore, Alec Cunningham had lied when he said that the two men were struggling when the shot was fired. Again, both father and son agreed as to the place where the man escaped into the road. At that point, however, as it happens, there is a broadish ditch, moist at the bottom. As there were no indications of boot-marks about this ditch, I was absolutely sure not only that the Cunninghams had again lied, but that there had never been any unknown man upon the scene at all.