This is the brass desktop stormglass that predicts the weather just like its ship-mounted predecessors that explorers used to help navigate storm-ridden seas. Used since 1750 when it was employed by soon-to-be Admiral FitzRoy, captain of the HMS BEAGLE, when he and passenger Charles Darwin, voyaged to the Galapagos Islands in 1831, its function remains a mystery even though its ability to predict atmospheric change is well documented. One theory states that the stormglass responds to electromagnetic fluctuations caused by weather and solar storms. The contained liquid—a mixture of distilled water, potassium nitrate, ammonium chloride, alcohol, and camphor—appears cloudy when precipitation is approaching; when crystals are visible in the liquid, humid or foggy weather can be expected; a cloudy glass with small stars indicates thunderstorms; a clear glass predicts calm weather. The hermetically sealed glass chamber is housed in a handcrafted brass cylinder. Includes a chart to interpret stormglass readings and hardware for wall mounting. Presented in a velvet-lined box. 6 1/2" H x 2 3/16" Diam. (12 oz.)