Tendency Barometer Admiral Fitzroy Storm Glass Hygrometer Historical Weather Instrument

The Model A053 combines all of the best features of the Tendency Barometers and is the top of the line. It functionally operates as any other of our tendency barometers. The beautiful mahogany stained wooden case with curved glass has an aluminum colored brass face plate with a Storm Glass mounted beside the tendency barometer tubes and a hygrometer mounted above the tubes. The Tendency Barometer was patented on December 23, 1818 by Alexander Adie. It was used by James Clark Ross on his expeditions to Antarctica. He is quoted in his diary as saying " the advantage of the tendency barometer to a mercury barometer is as big as having a mercury barometer to having no barometer at all." It 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 both Celsius and Fahrenheit and the barometer measures in millbars/ hPa. The overall instrument measures 20 inches high by 6.7 inches wide and weighs 3 pounds. This tendency barometer is an absolutely beautiful presentation piece that will last for generations.