The emergence of the Stormglass was clearly associated with weather forecast. The Stormglass was not just a figment of imagination, but a product that was supposed to solve a complex task of predicting what the weather would be like in the next few days in the 19th century. It was indeed so, when the glass enjoyed unprecedented popularity, especially in England, thanks to its promotion by an English Admiral R. Fitzroy. He wrote the following relations between what was happening in the Stormglass and the upcoming weather.
The Admiral describes:
"As the atmospheric current veers toward, comes from, or is only approaching from the polar direction, this chemical mixture - if closely, even microscopically watched, - is found to grow like fir, yew, fern leaves, or hoar frost - or like crystallisations. As the wind, or great body of air, tends more from the opposite quarter, the lines or spikes - all regular, hard, or crisp features, gradually diminish till they vanish. Before and in a continued southerly wind the mixture sinks slowly downward in the vial, till it becomes shapeless, like melting white sugar."
Thus begins the passage from the "Weather Book: A Manual of Practical Meteorology" by Admiral Fitzroy, which appeared in the mid-19th century. The Stormglass was then the centre of interest, because weather forecast was based on empiricism and there was some indication of exactness here. Although, the Admiral himself was not satisfied that he did not learn anything about the strength of wind. In his writings, he also mentions:
"The chemical mixture in a so-called Stormglass varies in character with the direction of the wind - not its force, specifically (though it may so vary in appearance only) from another cause, electrical tension."
Robert Fitzory under study of Stormglass
But let us look into other long-forgotten sources. A. Delenius said in the book "30,000 of the latest discoveries, recipes, generally useful practical knowledge and contemporary researches" (published in Moscow in 1885) not only a quantitative composition of the mixture in the Stormglass, but also changes of the vial's contents depending on the weather, which were supposedly derived by Admiral Fitzroy himself:
Clear liquid portends clear weather, cloudy means rain
Cloudy liquid with small stars indicates storm
Small dots indicate fog and raw weather
Large flakes in winter mean snow and in summer overcast and heavy air
Threads near the top of the liquid predict wind
Crystals at the bottom indicate thick air, frost and cold
Small stars on a clear day in winter mean that snow will come on the second or third day
The higher the crystals rise in winter, the stronger the frost will be
The question is whether these relations were derived in collaboration with Admiral Robert Fitzroy, or were based on another of his unpublished writings.
When a severe storm hit British Isles in 1859, the British Royal Court distributed Stormglasses, known as "FitzRoys StormBarometers", among many small fishing communities around the British Isles. These Stormglasses were to be used for weather forecasts and to subsequently inform ships before leaving the port.
People tried to read and predict what the weather would be based on what they saw in the Stormglass. They became witnesses to a variety of crystalline formations that grew as if "out of nothing". Then also came the days when the glass did not show anything special. These anomalies occupied their minds so much that they related the behaviour of the Stormglass with the upcoming weather, and were thus able to "predict" what the weather would be.
Nearly 200 years passed and it is no different. Many people still believe that weather can be predicted with the Stormglass. They do not realize that the main driving force of what is happening in the Stormglass is probably temperature changes in the environment. They are undoubtedly related to weather, but it is impossible to think that we will be able to guess what weather awaits us from what we see in the Stormglass.
What we are able to determine from the contents of the Stormglass is something called "thermal history". If the Stormglass contains new crystalline formations, compared to the last observation, we can say that there have been downwards temperature fluctuations in the last hours or days. If we observe a gradual dissolution - "disappearance" of crystal units, it is a sign that there have been upward temperature fluctuations. This is basically in line with what Japanese authors observed and described in 2008 in their article "Pattern formation of crystals in storm glass" published in the Journal of Crystal Growth.
But the Stormglass still retains its mystery and the fact that some were said to actually use it to predict weather. The above mentioned Admiral Fitzroy, who led thorough records of the changes inside the Stormglass in connection with the upcoming weather, conducted most of these observations using a microscope or strong magnifying glasses. It is therefore possible that changes, which are imperceptible to the naked eye and may be associated with the weather, can be observed at the microscopic level. These microscopic changes can lead to a better understanding of how it actually is with the Stormglass and weather forecasting.