Nichols radiometer

A Nichols radiometer is the apparatus used by Nichols and Hull in 1901 for the measurement of radiation pressure. It consisted of a pair of small silvered glass mirrors suspended in the manner of a torsion balance by a fine bolometer when it was first used. With this apparatus the experimenters were able to obtain an agreement between observed and computed radiation pressures within about 0.6 %. The original apparatus is at the Smithsonian.