How does an aneroid capsule barometer function?

The function of an aneroid capsule barometer is based on the use of a near vacuum capsule, which is sensitive to changes in atmospheric pressure. This capsule is constructed from thin, flexible metal that expands or contracts with variations in pressure. When atmospheric pressure increases, the capsule is compressed; when it decreases, the capsule expands.

The movements of this capsule are then transmitted through a mechanism that translates these movements into a dial reading. A leaf spring is often incorporated to provide a restoring force, allowing for a more accurate return to the neutral position when pressure changes occur. This mechanical setup is efficient as it allows for the direct measurement of pressure changes without the use of fluids, thus providing a compact and portable design suitable for various applications.

This understanding is central to recognizing how aneroid barometers have become widely used for measuring atmospheric pressure without the bulkiness of liquid-based instruments.