I’ve been trying to finish up Washington Irving’s the Sketch Book of Geoffrey Crayon, and, in the piece devoted to Westminster Abbey (purely by chance I’m reading about the place now, during the upcoming nuptials) I stumbled across the phrase Ocular Demonstration, which I’ve always found odd. It sticks out in my mind – Poe used it at least twice, in the Gold Bug and Hop Frog. The meaning is clear enough, in context, but i’ve never heard anyone use it and cannot think of any other places I’ve read it. It has an air of affected dignity, as if a low-born author is using it in a deliberate attempt to “gussy up” his language, using a ten dollar word where something like “…if they saw it with their own eyes…” would serve, with less pomp.
So I used Google Books N-gram to see how frequently the phrase was used. Not surprisingly, it peaked around Irving’s time, and has been in serious decline since. Most modern usages seem to be quotes from older works, or echoes of them.:
But it appears that my assessment may be wrong. If it was some hundred times more common back then than it is now, it probably was a real phrase, not mock-elegant.