Fri May 07, 2004
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The HMS Beagle became famous through its naturalist Charles Darwin. But equally
important was her captain: Robert Fitzroy, father of the British Meteorological Service.
Hi, I'm Bryan Yeaton for The Weather Notebook.
Among Fitzroy's studies was the application of the various storm glasses in
widespread use during the 1800s to weather forecasting. The first storm glasses likely
appeared around 1750, but their first documented shipboard use dates to the Beagle's
famed 1831-36 circumnavigation.
Storm glasses are hermetically sealed glass tubes containing a supersaturated
mixture of chemicals. The premise of the storm glass is that changing weather affects
the solubility of the mixture. Under changing conditions, users believed, the chemicals
produced crystals in strange, fascinating shapes, or alternately, existing crystals could
melt back into solution. The functioning of the storm glass is, however, not fully
understood even today, and they are now more a curiosity than a practical
Fitzroy found one specific mixture, containing camphor, ammonia, alcohol, potassium
nitrate, and water, most suitable for weather forecasting. In his 1863 Weather Book,
Fitzroy described the various crystal shapes and patterns that would develop within the
storm glass according to different wind directions and weather conditions.
Clear liquid meant bright weather; dim liquid, rain. Large flakes meant overcast or, in
winter, snowy skies. As its name implies, many believed the instrument was especially
sensitive to the coming of stormy weather. Thus, if small stars are seen in dim liquid,
In 1859, violent gales struck the British Isles, causing many marine casualties. Hoping
to prevent further catastrophes, the Crown distributed storm glasses, then known as
Fitzroy's storm barometers, to the many small fishing communities around the British
Thanks to our contributing writer, meteorologist Keith Heidorn. The Weather Notebook
is generously supported by the National Science Foundation and Subaru: Driven By
What's Inside. We are a program of the Mount Washington Observatory, online at
Fitzroy\'s Storm Glass
Admiral Fitzroy\'s Remarks