A random word-related experience to pass along. My daughter, for her 11th-grade literature class, is reading a novel written in the 1930s. She came across the phrase tail of her eye, and said she hadn't come across it before; I said that it seemed a bit old-fashioned but that I was familiar with it. She surmised that it had gone out of usage at some point, which makes sense. And she pointed out that we could easily check.
So we pulled up a Google ngram for it.
Yep. The phrase tail of his/her/my/your/the eye is never as common as corner of his/her/my/your/the eye but in 1920 the ratio of corner/tail is about four-to-one, and by 1940 it's down to ten-to-one, and by 1960 it's more like 25-to-1. Confirmed!
I don't have anything interesting to say about corners or tails of eyes, or why one phrase briefly is in moderately common use and then dies out. Or for that matter why the shape of the curve for corner is so volatile after 1960. What's interesting to me is that we could, in fact, easily check on that sort of thing, without even leaving our seats.
It's a brave new world that has such tools, innit?