At first I thought this Stormglass weather predicting instrument was a joke, reminding me of that old weather device that featured a picture of a donkey whose tail was made of yarn. Its deadpan instructions told us "if tail is wagging, the weather is windy; if tail is frozen, weather is cold; if tail is smoking, weather is hot." Well, this device is not that. It's a bottle full of magic liquid that's said to be able to actually forecast the weather.
The liquid has certain properties that create various types of crystals that correspond with approaching weather. For instance, if the liquid takes on a milky appearance, it will soon rain. If the liquid's clear, that predicts nice weather ahead, and fern-shaped crystals predict windy weather.
Its makers say it was "discovered hundreds of years ago by the early alchemists," but we're at a loss to figure out how this $110 tube of goo works, if it does at all. If it doesn't, at least it can be a fascinating conversation piece, and also amaze you with its growth of various weird-looking crystals.[Weather in a Bottle, via Weather Snob]