CAMPBELL-STOKES SUNSHINE RECORDER by NEGRETTI & ZAMBRA
14-004. English, 2nd quarter 20th century, engraved on the top of the black slate base "NEGRETTI & ZAMBRA, LONDON." This Campbell-Stokes sunshine recorder consists of a 4" diameter glass sphere mounted concentrically in a section of a spherical bowl, the diameter of which is such that the sun's rays are focused sharply on a card held in grooves cut into the bowl. There are three overlapping pairs of grooves, each to take cards suitable in shape for different seasons of the year. The 9" square x 1 1/4" thick base is made of black slate and the frame is made of black painted aluminum, with an adjustable arc under the sphere and bowl to be set to the latitude, between 40 and 60 degrees. As the sun moves across the sky, its focused image burns a trace on the card so that the duration of sunshine is accurately recorded. This attractive sunshine recorder is in very good overall condition. A supply of cards is also included. Campbell-Stokes sunshine recorders were used extensively by the British Meteorological Office throughout the British Empire as well as by many other countries, but have now become very difficult to find.
