four o'clock
The gentleman in the easy-chair was smoking a meerschaum . As Mr. Carter said those two words , `` four o'clock , '' his teeth made a little clicking noise upon the amber mouthpiece of the pipe . The detective heard the sound , slight as it was , and drew his inference from it . Major Vernon had seen Joseph Wilmot , and knew that he had left the Abbey at four o'clock , and thus gave a little start of surprise when he found that the exact hour was known to others . `` You know where Mr. Dunbar has gone ? '' said Mr. Carter , looking still more sharply at the gentleman in the easy-chair . `` On the contrary , I was thinking of looking in upon him at the Abbey this evening . ''