She's holding some sort of filter to watch the eclipse. The men are using it as an excuse to ogle at her with a telescope. Don't ask me why anybody would actually look at the eclipse with a telescope.
I'm still mystified as to why people thought that pointy, confierous breasts are more attractive than the lovely, globe-shaped objects that they are naturally? I'm thinking that maybe people didn't get to see naked breasts all that often and had no basis for comparison. Thank goodness we now have the Internet to enlighten everyone.