The Adie Tendency Barometer, Thermometer, Hygrometer by D&D is unique. The A38 barometer is mercury free, and consists of two liquid filled tubes. One tube in a U-shaped which is open ended and filled with a red fluid; and one closed thermometer tube filled with a blue fluid, mounted parallel to each other. When the fluid levels are the same, the weather is changing. When the red fluid level is below the blue fluid level, the weather is fair (high pressure pushes the red fluid down in the tube). When the red fluid level is above the blue , stormy weather is predicted (low pressure allows the red fluid to move up the tube). The thermometer measures in Fahrenheit and Celsius and the instrument also has a hygrometer to measure relative humidity. It measures 15.7 inches high by 7.8 inches wide and shipping weight is 3lbs. The frame is simulated burl wood in high gloss with brass trim. The unit comes fully assembled and includes a calibration kit to adjust the unit for altitudes above sea level. Normally ships in 1-3 business days. MSRP: $178.00.

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