Two "Private Eyes" in The Valley of Fear

The September 1961 issue of The Baker Street Journal, then edited by Dr. Julian Wolff of happy memory, makes an interesting observation in "From the Editor's Commonplace Book." Accompanied by the logo above are these words (among others):

"It is probably not necessary to inform our readers that the only use of the term "private eye" in the Canon occurs in The Valley of Fear. We all recall the statement in the note that Inspector MacDonald received from White Mason: "This note is for your private eye." Of course that's why he took it to Sherlock Holmes."

Oddly enough, Dr. Wolff didn't make the second connection between The Valley of Fear and the term "private eye." It's a strong one.

As every good mystery fan should know, the first private eyes were the sleuths of the Pinkerton National Detective Agency. That nickname came from the wide open eye with Pinkerton's "We Never Sleep" motto. And Birdy Edwards, the hero of the second half of The Valley of Fear, is a Pinkerton man. So he was indisputably a private eye, even though the term is used in that book only in a wholly different sense.