Durand, Loyal, Jr. (ed.) / Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume XXXI (1938)
Whitney, Lester V.
Continuous solar radiation measurements in Wisconsin lakes, pp. 175-200 PDF (7.7 MB)
176 Wisconsin Academy of Sciences, Arts, and Letters ords of solar energy both in air and in water at various depths. With such records, the total solar energy delivered to the surface of the lakes, and its transmission to various depths, could be found under all conditions normally present in summer. The central part of the apparatus was a Cambridge Double Recorder which measured continuously the solar energy received by several thermopiles or Photox cells. In 1935 records were made on four lakes of different color and transparency; these were Trout, Crystal, Boulder, and Muskellunge. The records were checked and standardized with records of solar energy made by an automatic Kipp Solarimeter with a Richard Recorder. The Kipp Solarimeter in turn was calibrated in terms of the standard solarimeter used by the United States Weather Bureau in Madison, Wisconsin. In 1936 the work was confined to Trout Lake, - but Photox cells as well as thermopiles were used, continuous records being taken at greater depths than before. The apparatus was set up so that it could be readily moved from lake to lake. The recorder itself was supported by a - strong wooden frame solidly bedded on the sandy shore of the lake. It was covered by a tent, but for special protection a large wooden case covered the recorder and its frame. The purpose of the case was to protect the recorder if a wind storm should carry the tent away. Happily no such storm occurred; the recorder functioned perfectly throughout both summers. It should be added that the -recorder was received by the Survey in August 1934. The general arrangement of recorder and thermopiles was worked out and the apparatus set up on Trout Lake at that time by Mr. Donald Kerst. The instrument came at so late a date in August that records for only a few days could be made. The recorder itself consists essentially of two galvanometers so arranged that a continuous record can be made on a rotating drum by arms which extend out from the galvanometers. Below the ends of these arms and just above the drum is an inked thread. A chopper bar descends once a minute, pressing the arms and thread against the paper, leaving dots on the record. The galvanometer swings freely between readings. Just after the dots are made, automatic switches are thrown, connecting the galvanometers to other thermopiles or Photox cells. At the same time a different colored thread is moved under the chopper
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