Clear Solar Radiometer with Green Base

The Solar Radiometer, also known as a light windmill was invented in 1873 by the English physicist Sir William Crooks. It demonstrates in a simple way how light can be converted into energy and hence motion. The glass globe is sealed with reduced air pressure and the wheel is precisely balanced. Each of the four paddles on the wheel has a shiny metallic side and a dark side. The dark side of the paddle absorbs more light than the metallic side, thus creating pressure and producing motion. The solar radiometer works with warm light, that is sunlight or the light from electric bulbs, but not cold neon lights. Globe diameter approx 60mm Height approx 170mm