The Bat Clock (Apr, 1933)
LIGHT PRINTS TIME ON CLOUDS
Once engaged in the development of a death ray for possible military use, H. Grindell-Matthews, British inventor, has developed a new gun for projecting light rays. A motor carriage supports the cannon-like projector, which is designed to throw signs upon clouds miles away, and is an improved model of one he demonstrated in New York City not long ago. By inserting a special clock with a transparent face and opaque hands and figures in the projector, the correct time is also thrown on clouds.