Dad Had These on Every Car He Owned in the 1950s. But….Why?

My Dad had these on every one of his cars when I was growing up in the1950s.  My brothers and sisters and I thought they were radio antennas that picked up the car radio!  We use to "flick" them to see if they made a noise, and of course we would get yelled at!

Dad swore by these weird things.  Anybody got a clue what they were used for?