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Airpressure compensation:
Because its period of oscillation increases when the air pressure rises, the pendulum is additionally equipped with a barometric-error compensator. The compensation is achieved by aneroid capsules and a weight, which moves upwards or downwards according to the respective changes of air pressure, thus preventing a change of the oscillation period.

Amplitude:
The angle through which a pendulum moves from is central position to one extreme. On the pendulum scale you can read the amplitude in minutes of arc.

Aneroid barometer compensation:
Device to compensate for the influence of the changing air pressure on the accuracy of a clock.

Anodise:
Electro-chemical treatment of aluminium. Surface is treated in acid-bath. The result is a very durable oxidation layer.

Arbor:
Shaft in a movement.