Robert C. Atherton didn't only hire well known illustrators to handle the story assignments in Cosmopolitan. He hired lesser known and entirely unknown artists as well. For instance, I'm willing to bet that, like me, most of Cosmo's readers had never heard of Henry Koerner.
But just because he is unknown to some of us doesn't mean he wasn't well known to many others. Koerner was a fine artist and an illustrator and had a long and storied career. A thorough biography and some examples of his work can be found here.
Not long after Robert Atherton hired him for this assignment in Cosmo, Koerner began doing covers for Time magazine - and this online archive of Koerner's cover illustrations is well worth taking a look at.
If you'd like to take a closer look at these pieces, you'll find full size versions in my Henry Koerner Flickr set.