A barometer is an instrument that measures changes in the atmospheric pressure and, by extension, in the weather. There are two types of barometers: liquid-based and mechanical. The main component of the mechanical barometer is a metal box with thin corrugated walls that is filled with rarefied air. Changes in the atmospheric pressure cause the box to expand or contract, thus impacting the spring attached to it. As the spring transforms, changes in values can be determined using the barometer’s dial. To this end, mechanical barometers are fitted with two arrows, with one indicating the current atmospheric pressure, and the other, adjustable one, being used for tracking changes in weather conditions. If you point the adjustable arrow to the same position as the main one and wait for an hour, the main arrow will move, while the adjustable one will still be showing the last measurement.

The liquid-based version of the instrument uses a tube of mercury that is tightly sealed at the top and sitting in a vessel at the bottom. When the atmospheric pressure goes down, the mercury column falls accordingly.

Instruments for measuring the atmospheric pressure and predicting the weather first appeared several centuries ago. In the merchant’s drawing room of the Tomsk History Museum, you can find a device that combines a thermometer with a barometer. It operates using the same principle as a standard mechanical barometer. The instrument’s body is made of natural wood decorated with carvings, while the mechanism and the dial were produced from metal at a factory. The dial has English labels used for indicating the current weather conditions: “rain, ” “fair, ” “very dry, ” “stormy.” However, this barometer is believed to have been manufactured in Germany since many similar devices were produced there around the same time.

Instruments like this one were quite common among merchants, bourgeois, and the intelligentsia: doctors, teachers, writers, and scientists. In affluent households, barometers were used as wall decorations for drawing rooms or studies, where they served as interior design elements on par with guest silverware, family photographs, clocks, figurines, and paintings.