I tried to create a perpetual motion machine out of Capsela when I was 9 by connecting a propeller to the wheels, so the propeller turns when the wheels move. I

I tried to create a perpetual motion machine out of Capsela when I was 9 by connecting a propeller to the wheels, so the propeller turns when the wheels move. I was really puzzled when it didn't work! But I still remember that machine clearly 30 years later.