Nobody really knows when or where storm glass was invented…
But in the 1800s, a sea captain by the name of Robert FitzRoy* was sailing around South America with Charles Darwin and Robert ran some experiments (or whatever) with storm glasses, the results of which led to the standard formula for making storm glasses today.
The theory is that changes in barometric pressure cause the liquid mixture inside the glass to change between various states and appearances of crystallization, thus predicting impending weather.
The thing about that is that the state of the liquid in the glass does not seem to be a dependable indicator of weather to come. However, they do still look cool sitting on a desk or a bookshelf, so you should buy one for aesthetic purposes now.
*Who makes the rules on capitalization in the middle of a name? Can anyone just decide some letter in the middle of their last name has to be capitalized forever by everyone? Someone explain this please.