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Scientific "Hygro-Meter" from Phila. Thermo Co. Phila.,Pa.
Really Cool Rolling Scale inside Glass Cylinder !
Scientific Hygro-Meter marked "Patent Pending" from the Phila. Thermo Company, Philadelphia,Pa.
A Hygrometer is an instrument used to measure the moisture content or the humidity in the air. The best known type of hygrometer is the "dry and wet-bulb psychrometer", best described as two thermometers, one with a wetted base, one with a dry base. The water from the wet base evaporates and absorbs heat causing the thermometer reading to drop. Using a calculation table, the reading from the dry thermometer and the reading drop from the wet thermometer are used to determine the relative humidity.
Plaque Measures 8 1/2 inches High, 4 inches Wide, and 1 1/2 inches Deep.
Weighs 11.4 Ounces.
Condition : Both Temp tubes go from 25 to 120 degrees Fahrenheit, and are Fine and Read accurately ,the Calculator Cylinder Spins freely, but the "Wet Bulb Container" is missing from the lower clip.
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