The Jayotype. "- Mr. Jay: The gentleman is married? - The gentleman: Certainly, but how the devil did you know that? - Mr. Jay: Oh, its that this instrument is perfect, that no curve of the head, no bump on the forehead can escape it. - The gentleman: How ingenious!," plate 60 from Moeurs Conjugales by Honoré-Victorin Daumier
Original public domain image from Art Institute of Chicago