Radiometers were conceived in the 1870s by British physicist William Krux as an experimental instrument to convert light energy into kinetic energy. The speed of rotation varies depending on the light intensity and the light source. Place it near a window or incandescent lamp and enjoy the movement of its thin metal fans.

Made of handblown glass. There may be individual differences such as small scratches and chips. 

The radiometer will rotate when exposed to light rays including infrared rays (heat rays), such as sunlight and incandescent lights, but there is no reaction if it is a light such as fluorescent lights and LEDs.

In rare cases, the black paint on the metal plate inside the glass ball may peel off. Please note that there is no problem with the product quality.

Measures 3" x 6.3" (8.0 × 16.0cm).