Read it through once

“Now this was a case in which you were given the result and had to find everything else for yourself. Now let me endeavour to show you the different steps in my reasoning. To begin at the beginning. I approached the house, as you know, on foot, and with my mind entirely free from all impressions. I naturally began by examining the roadway, and there, as I have already explained to you, I saw clearly the marks of a cab, which, I ascertained by inquiry, must have been there during the night. I satisfied myself that it was a cab and not a private carriage by the narrow gauge of the wheels. The ordinary London growler is considerably less wide than a gentleman’s brougham.