Mahogany Deluxe Tendency Barometer

The Mahogany Deluxe model combines all of the best features of the Tendency Barometers and is the top of the line. Functionally, it operates as any of our other tendency barometers. What makes it unique is the beautiful mahogany-stained wooden case with curved glass that encases an aluminum-colored brass faceplate. Additionally, a storm glass is mounted beside the tendency barometer tubes and a hygrometer is mounted above the tubes.

The Tendency Barometer was patented on December 23, 1818, by Alexander Adie. It was used by Ross on his expeditions. 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-shape is open-ended and filled with a red fluid; and one closed thermometer tube is filled with a blue fluid. These two tubes are mounted parallel to each other for easy comparison.

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 millibars/hPa. The overall instrument measures 20 inches tall by 6.7 inches wide and weighs three pounds.