Answer: Rotating Glass Disk

If you’ve never heard of this innovation, then prepare to have your mind blown by the sheer novelty of it. Back in the mid 1930s, automotive designers came up with a clever windshield design: a glass disk mounted in the main windshield, like a port hole, that (driven by an electric motor) rotated rapidly to fling rain, sleet, and snow right off. The example shown here is from the December 1934 issue of Popular Mechanics and features a British test driver demonstrating the design in action.

As clever as the design was, it proved to be impractical for use in mass-produced automobiles. Today, the design, commonly called a clear view screen, isn’t used on any cars, but is commonly found on the windshields of large ships, locomotives, and some public transport vehicles like streetcars and trams. In those applications, especially in keeping the glass clear on a ship in inclement weather, it’s an invaluable and cleverly designed tool.