Well, I guess it blocks a bit of sun, at least:
This lady is my third great-grandmother, Susan William Lee Martin Kennedy. She was the wife of Dr Nathan Blunt Kennedy, one of my Civil War surgeon ancestors. I guess as the spouse of a prominent physician in the Hill County, Texas of the 1800’s, Mrs. Kennedy felt the need for fancy attire for her head!
I don’t want to seem a sexist, so here is a photo of my great-grandfather, Charles Arthur Rogers: