An otheoscope Size:L: 80 x 60cm the print is embossed 'Charles

the print is embossed 'Charles Spencer

View of London from One-Tree Hill in Greenwich Park

'A Hint to Louis Napoleon'

much to the amusement of the men near by

yer honour-r

An otheoscope Size:L: 80 x 60cm the print is embossed 'CharlesAn otheoscope with fixed vanes of oxidised copper and coloured disc above it. An instrument designed for measuring the mechanical effect of radiant energy, a modification of the radiometer. Mounted in a partial vacuum, the central rotor spins when the vanes are exposed to light. Chemist William Crookes (1832 1919) initially believed the vanes with black surfaces were pushed around by pressure from light radiation. This was incorrect and other theories