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1.
Introduction
Thank you for your purchase of the Fischer Instruments 1508BTH-45 5" Brass Barometer with
Temperature & Humidity. The following is a guide for preparation, care and operation of your marine
weather instrument.
Note:
Some of the images are generic and may not match your exact model.
2.
Care and Cleaning
Avoid use of harsh household cleaners and coarse paper towels, which can scratch the bezel or lens.
Fingerprints and dirt may be removed the lenses and bezels with a soft cloth lightly dampened with a
mixture of water and mild dishwashing liquid. Be sure to dry the lens and bezel with a soft cloth
after cleaning.
3.
Barometer Operation
Figure 1
A
Barometer Mechanism Case
B
Barometer calibration set screw
3.1 How the aneroid barometer works
An aneroid barometer uses a small, flexible metal box called an aneroid cell. This aneroid capsule
(cell) is made from an alloy of beryllium and copper. The evacuated capsule is prevented from
collapsing by a strong spring. Small changes in external air pressure cause the cell to expand or
contract. This expansion and contraction drives mechanical levers such that the tiny movements of the
capsule are amplified and displayed on the face of the aneroid barometer. This model includes a
manually set gold needle which is used to mark the current measurement so a change can be seen. It
