I knew the firm for which this man worked.

Having taken the printed description.

I eliminated everything from it which could be the result of a disguise--the whiskers, the glasses, the voice, and I sent it to the firm, with a request that they would inform me whether it answered to the description of any of their travellers.

I had already noticed the peculiarities of the typewriter, and I wrote to the man himself at his business address asking him if he would come here.

As I expected, his reply was typewritten and revealed the same trivial but characteristic defects.