Model 240-1070 -Campbell-Stokes Sunshine Recorder (3075)

The 240-1070 Campbell-Stokes Pattern Sunshine Recorder employs a glass sphere to focus the sun`s rays to an intense spot, which will char a mark on a curved card mounted concentrically with the sphere. As the earth rotates, the position of the spot moves across the card. When the sun is obscured, the trace is interrupted. At the end of the day the total length of the trace, less gaps, is proportional to the duration of sunshine.