Explorations and field-work of the Smithsonian Institution in .. . Fig. 3.—Smithsonian solar \ atnry, Mount St. Katherine, 8,500 feetaltitude. Sun rays reflected into the basement laboratory are observed withthe bolometer, an electrical thermometer sensitive to a millionth of a Fig. 4.—The coelostat for reflecting sun rays constantly northward horizontallyinto the observing laboratory. SMITHSONIAN EXPLORATIONS, 1933 . -^^^^

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Keywords: ., bookcentury1900, bookdecade1910, booksubjectscienti, bookyear1912