He led us through the passage and out into a dark hall beyond.
“This is where young McFarlane must have come out to get his hat after the crime was done,” said he. “Now look at this.” With dramatic suddenness he struck a match, and by its light exposed a stain of blood upon the whitewashed wall. As he held the match nearer, I saw that it was more than a stain. It was the well-marked print of a thumb.
“Look at that with your magnifying glass, Mr. Holmes.”
“Yes, I am doing so.”
“You are aware that no two thumb-marks are alike?”
“I have heard something of the kind.”
“Well, then, will you please compare that print with this wax impression of young McFarlane’s right thumb, taken by my orders this morning?”
As he held the waxen print close to the blood-stain, it did not take a magnifying
