Thanks, everybody. Sissi is the person I was thinking of.

Last weekend I went to visit a man who collects, restores, and sells magnificent clocks called Vienna Regulators. (see snclocks.com) On three of the clocks were faces of a woman wearing a certain kind of bonnet. I thought they might be images of Sissi, but I couldn't remember her name.

I'm going to see if there are any paintings of her with a bonnet like that.