A naval barometer is a specialized type of barometer designed for use on ships and in marine environments. It measures atmospheric pressure to help sailors and navigators predict weather changes and enhance safety at sea. Here are some key features and functions of a naval barometer:

Key Features

Robust Design: Naval barometers are built to withstand the harsh conditions of the marine environment, including moisture, temperature changes, and vibrations from the sea.

Aneroid Mechanism: Many naval barometers use an aneroid mechanism, which consists of a sealed, flexible metal chamber that expands and contracts with changes in atmospheric pressure. This makes them more durable and less prone to breakage compared to mercury barometers.

Calibration for Altitude: Some naval barometers can be adjusted for altitude changes, which is particularly important when sailing in areas with varying elevations.

Dual Scale: Many models display pressure in both millibars (or hectopascals) and inches of mercury, making it easier for sailors to interpret the readings based on regional preferences.

Functions

Weather Forecasting: By monitoring changes in atmospheric pressure, sailors can predict weather patterns, such as approaching storms or changes in wind conditions. A falling pressure often indicates deteriorating weather, while rising pressure suggests improving conditions.

Navigation Assistance: Accurate pressure readings can aid in navigation by helping to determine local weather patterns that might affect sailing routes.

Safety Measures: Being aware of changing weather conditions helps mariners make informed decisions, enhancing safety at sea.

In short, Naval barometers are essential tools for navigation and safety in maritime operations. They provide valuable data that can help prevent accidents and ensure successful voyages by allowing crews to anticipate and prepare for changing weather conditions.

This specific mercury barometer is a construction of Vice-Admiral of the British Navy Robert FitzRoy (Robert FitzRoy, 1805 – 1865). He became known as the Commander of the HMS Beagle during Charles Darwin's famous voyage to the Galapagos Islands on that ship. He was the first to issue a weather forecast in a daily newspaper and the first to implement a ban on ships leaving harbors when there was a problem of adverse weather conditions. For this purpose he established a system of hanging storm warning cones on it at the entrances of the ports.