Sunshine or solar recorder, Campbell-Stokes, glass / metal, used at Sydney Observatory, made by Rudolf Fuess, Steglitz, Berlin, Germany, 1895-1905
A sunshine or solar recorder consisting of a glass sphere mounted on a brass quadrant with a latitude adjustment; this is set for Sydney's latitude. The quadrant also supports a curved brass card or form holder that sits directly behind the glass sphere. The quadrant is mounted on a rectangular cast alloy base.
In use, a card is inserted each day, its position being selected according to the season (as the sun is higher in the sky in summer than in autumn or spring, when it is higher than in winter). Whenever the sun is shining, the glass sphere focuses its rays onto the card, which changes colour at that spot as a result of charring. The resulting trace, which is continuous on a sunny day and discontinuous if there are periods of heavy cloud, can be used to assess the number of hours of sunshine.