Thanks to the growing affordability of cars, more Americans than ever before had access to pools, beaches, and swimming holes. Concerned that the average person couldn't actually swim, inventors developed scores of strange devices to help people develop their form and stay afloat. Pictured left are a pair of flotation devices with propellers attached to them.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.