Mouth Blown Glass Lichtmühle, or Light-Mill

Whilst at first glance this might be mistaken as some kind of perpetual motion machine it is in fact a kind of heat engine reliant on a carefully judged partial vacuum to reduce resistance and facilitate the necessary thermodynamic processes. Fascinating and mesmerising the rotation can also be used as a quantitative measure of electromagnetic radiation, especially in the visible and infrared spectra. Hang near a window, and watch as the relative brightness of the day affects the speed at which the internal fins rotate. Mouth blown and assembled in small lamp workshops in Lauscha, Germany. Approximately 8cm diameter.