Storm Glass is an instrument developed for forecasting weather and used by Vice Vice-Admiral Robert FitzRoy Royal Navy (5 July 1805 – 30 April 1865), the captain of the H.M.S. Beagle while Charles Darwin was on board. Fitzroy was one of the first weather forecasters and became the first head of what would later become England's Meteorological office.
HOW IT WORKS
A storm glass, also called a weather glass or camphor glass, is a glass tube containing a mixture of ammonium chloride, potassium nitrate, camphor, water, and alcohol, making a normally clear liquid in which different types of white crystals periodically grow and dissolve. The idea is that the mixture is so finely balanced that minor fluctuations in atmospheric conditions will change the solubility of the chemicals and produce a wide variety of crystal shapes, from tiny floating flakes to large masses of feathery fans. Each supposedly predicts a certain type of weather.
How to Interpret the Storm Glass
‧ Clear liquid : Bright, sunny, good weather
‧ Liquid is cloudy : Cloudy Weather
‧ Small dots in liquid : Humid or Foggy
‧ Cloudy with small stars : Thunderstorms
‧ Small stars on sunny winter days : Snow
‧ Crystals at the bottom : Thick air, frost
‧ Threads in upper tube : Windy Weather