Admiral Fitzroy's Stormglass

Well, my latest toy arrived by UPS yesterday afternoon. And I am sitting here and still trying to puzzle out Admiral Fitzroy's stormglass.

Or, as it's sometimes called, a stormbottle. (Stormbottle— I love that word!) Talk about a funky weather forecasting device! Brass, nearly six inches tall. Chemicals sealed in a glass tube. The whole thing weighs about one pound. And it's supposed to give you a fairly reliable forecast of weather over the next 24 to 48 hours.

Surfing around, we learn that the stormglass dates back to around 1750. Nobody knows who invented it, but by around that time such devices were for sale at a shop called "Under the Goat and Compasses" at Old London Bridge. The stormglass was popularized during the 1800s by Admiral Fitzroy (1805-65), commander of the HMS Beagle— it was one of the devices Fitzroy used during the Darwin Expedition.

The liquid in the glass is a mixture of distilled water, ethanol, potassium nitrate, ammonium chloride, and camphor. To be lazy and lift the rest of my homework straight from Wikipedia:

During the historic voyage, FitzRoy carefully documented how the storm glass would predict the weather:

• If the liquid in the glass is clear, the weather will be bright and clear.
  
• If the liquid is cloudy, the weather will be cloudy as well, perhaps with precipitation.
  
• If there are small dots in the liquid, humid or foggy weather can be expected.
  
• A cloudy glass with small stars indicates thunderstorms.
  
• If the liquid contains small stars on sunny winter days, then snow is coming.
  
• If there are large flakes throughout the liquid, it will be overcast in temperate seasons or snowy in the winter.
  
• If there are crystals at the bottom, this indicates frost.
  
• If there are threads near the top, it will be windy.

A storm glass works on the premise that temperature and pressure affect solubility, sometimes resulting in clear liquid; other times causing precipitants to form. However, the method by which this works is not fully understood. Although it is well-established that temperature affects solubility, sealed glasses are not exposed to the pressure changes that would account for much of the observed behavior.

My stormglass was made in Denmark by E.S. Sørensen. I'm still trying to dope out certain points from the often obscure and sometimes contradictory material I've been finding online. (Don't you just love the cacophony that is cyberspace?!) In particular, you'll see I've installed my stormglass just inside my (north-facing) kitchen window, as some sites recommend; I suspect I ought to (as other sites recommend) move it outside, where I should hope the alcohol content will keep it from freezing.

Oh well. Mechanical ingenuity and I do not mix. This is what they call a "learning experience"...