June 6, 2011

Ship's Hull Tendency Barometer

You can forecast weather just like 17th Century mariners did with this wall mounted Ship's Hull Tendency Barometer. Glass tubes are positioned above a model sailing ship's wooden hull. We understand that barometers measure atmospheric pressure, but what exactly is a tendency barometer?

The tendency barometer was patented on December 23, 1818 by Alexander Adie, a Scottish optician, calling it a Sympiesometer. Sir James Clark Ross used it on his expeditions. The tendency barometer consists of two liquid filled tubes mounted parallel to each other. The barometer tube is in a U-shape, which is open-ended and filled with a red fluid, and a closed thermometer tube is filled with a blue fluid. You can predict the weather with glance across the room:

When the fluid levels are equal, the weather is changing.
When the red fluid level is below the blue fluid level, the weather is fair since high pressure pushes the red fluid down in the tube.
When the red fluid level is above the blue, stormy weather is predicted as low pressure allows the red fluid to rise in the tube.

The Ship's Hull Tendency Barometer would make a tremendous Father's Day gift. It comes fully assembled on a frosted-glass frame and sturdy hanging hardware is included.

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Posted by Molly & Jessie at June 6, 2011 12:52 AM