Barometers Realm

This impressive Rodenstock Weather Station, dating from around 1890 and manufactured by the renowned German company Rodenstock, is a sophisticated ensemble of meteorological instruments: a barometer, a thermometer, and a Mithoff’s hygrometer, mounted on a carved wooden case with detailed weather instructions.

The case, measuring 33 by 62 centimeters, is made of walnut and richly adorned with elegant carving in the form of scrolls, volutes, and foliage. The central area is occupied by a large sheet of aged paper, protected by flat glass, containing extensive information about the instruments and how to interpret weather conditions. The sheet is beautifully illustrated with woodcut engravings depicting allegorical wind figures: to the right, a male head with puffed cheeks blows forcefully, emitting stylized streams of air resembling branches, leaves, and flowers — a classical representation of the warm southern wind; to the left, a stern male face with tense cheeks exhales sharp, straight gusts of air cutting through the space — a typical image of the cold and severe northern wind.

It is appropriate to quote here in full the original text that explains the function of each instrument:

Rodenstock’s Weather Station

Explanation of the Instruments

The barometer of this newly improved design is equipped with a pointer that has two indicating tips.

The needle-shaped tip on the right side of the scale shows air pressure in millimeters: on the inner semicircle — the absolute (local) pressure; on the outer arc — the sea-level–corrected pressure, which is essential for comparison with meteorological reports.

The left-hand side of the barometric scale — where inscriptions such as “Fair” or “Rain” typically appear — is divided into two main fields by color: the lower zone, representing falling pressure, is marked in blue; the upper, for rising pressure, in yellow.

The needle-point of the blue pointer indicates on this scale. A manually adjustable brass pointer (mounted on the glass) serves as a trend indicator, making it easy to observe pressure changes.

The mercury thermometer shows temperature both in Réaumur and the hundred-point Celsius scale.

The hygrometer indicates the moisture content of the air as a percentage of relative humidity. In dry conditions, the needle points to the yellow field; in humid air — to the blue; and at moderate humidity — to the white field.

This latter condition is considered the most beneficial for health, particularly in living spaces and hospital rooms. This instrument is especially useful for forecasting storms and night frosts.

Rules for Weather Prediction

1. Fair weather is to be expected when the barometer shows high pressure (the needle tip lies in the yellow field) and the hygrometer indicates low air humidity.

2. If the barometer is high but humidity is also high, then fog may form with a slight drop in temperature, and depending on the location, brief precipitation is likely.

3. Rapid rise or sudden drop in the barometer suggests unstable weather; slow changes, in contrast, indicate stable conditions.

4. In winter, a rising barometer indicates frost; falling pressure — thaw.

5. At medium barometric readings — between the yellow and blue zones, marked “Changeable” — if the hygrometer shows high and rising humidity, brief precipitation is likely.

6. A falling barometer with southeast to southwest winds and low humidity (as shown by the hygrometer) predicts overcast weather; rain or snow follows only after a sharp increase in humidity and a shift of wind to the west or north.

7. A sudden drop in barometric pressure with a western wind heralds a storm from the northwest, north, or northeast.

8. A very rapid drop of the barometer in summer, under high heat and humidity, usually means a thunderstorm — especially if humidity continues to rise; otherwise, expect strong wind.

9. If the barometer is high in the morning (between 8 and 11 AM) but falls slightly, it indicates a change in weather — likely rain or wind.

10. If the barometer is low but rises slightly during the afternoon, expect a change — likely for the better.

The hygrometer dial bears the inscription “D.R.P. No. 16568”, referring to the German patent granted to Otto Mithoff, an engineer from Berlin, in 1881. The patent, titled “Hygroskop aus der inneren Haut der Eierschalen hergestellt”, describes the use of the inner membrane of an eggshell — specifically the thin film between the shell and inner albumen — as a hygroscopic measuring element. As seen in the photos, the hygrometer retains its original dial, though in poor condition; it was replaced with a printed version of the same scale but simpler design. It is likely that the company itself offered such replacement dials as part of regular servicing.

A distinctive feature of this barometer’s movement is the final stage of motion transmission from the aneroid capsule’s walls to the indicator hand. Typically, such movements use a fine steel chain composed of numerous tiny links, resembling a miniature bicycle chain. However, in this particular barometer, a simple thread is used instead. It runs directly from the small lever at the bottom to the pointer shaft, winding or unwinding around it as the atmospheric pressure changes.

The Rodenstock Weather Station stands as a rare example of a meteorological compendium, comparable to the well-known “Weather Telegraphs” produced by the Lambrecht company.