Unless they are quite new, no two of them write exactly alike.

Some letters get more worn than others, and some wear only on one side.

Now, you remark in this note of yours, Mr.Windibank, that in every case there is some little slurring over of the 'e,' and a slight defect in the tail of the 'r.' There are fourteen other characteristics, but those are the more obvious." "We do all our correspondence with this machine at the office, and no doubt it is a little worn," our visitor answered, glancing keenly at Holmes with his bright little eyes.
"And now I will show you what is really a very interesting study, Mr.Windibank," Holmes continued.

"I think of writing another little monograph some of these days on the typewriter and its relation to crime.

It is a subject to which I have devoted some little attention.