Clear view screen
A clear view screen or clearview screen is a glass disk mounted in a window that rotates to disperse rain, spray, and snow. A clear view screen is typically driven by an electric motor at the center of the disk, and is often heated to prevent condensation or icing. Many fishermen call them a "clear sight".
Clear view screens were originally developed in the mid-1930s for automobiles as a better option than standard windshield wipers but were soon found more suitable for small boats and larger ships. On ships, a clear view screen is usually on the bridge and rotates at high speed (~1500 rpm). Clear view screens are also used in locomotives and rail transport.
Sasara Trams of Sapporo Streetcar are equipped with clear view screens