Solar Radiometer keyring Inside are a set of

Inside are a set of metal vanes which are mounted on a spindle

Shadow box dimensions: 20 x 18 x 3

Butterfly specimen (Papilio oribazus

Tanzania) mounted in a double-glass black wooden standing vitrine

Butterfly specimen (Philaetria dido - verso - Peru) mounted on acid-free paper in a black wooden shadow box

Solar Radiometer keyring Inside are a set ofInvented in 1873 by chemist & experimenter Sir William Crookes, the solar radiometer was the first way in which man could demonstrate light as an energy source. The radiometer consists of an airtight glass bulb, containing a partial vacuum. Inside are a set of metal vanes which are mounted on a spindle. When exposed to sunlight, artificial light, or infrared radiation, the vanes turn with no apparent motive power, the dark sides retreating from the