cape cod Marine Barometer Installation and Operation Manual

Cape Cod

®

Marine Barometer

Installation and Operation

The Cape Cod

®

Marine Barometer features a precision, German-made, aneroid movement housed in a solid brass case. The temperature-compensated movement is designed for use at altitudes from sea level up to 2,000 feet.

Installation: The barometer is attached to the wall, or a wooden plaque if desired, using the three brass wood screws enclosed. Before mounting, the movement should be set to compensate for your altitude by turning the set-screw on the back with a small screw driver. The barometer is set at the factory for the reading at sea level, so if you are located at or slightly above (<100 feet) sea level, little or no adjustment should be necessary.

To set the barometer, obtain the current barometer reading from your local weather forecast or from one of the many web sites devoted to weather, then turn the set-screw until the black pointer matches that reading.

Once the barometer has been properly set, no further adjustment will ever be needed, unless it is relocated to a different altitude.

The exact reading is not critical; much more important is whether the barometer is

rising or falling, and how fast that change is occurring.

After setting the barometer, attach it to the wall or mounting surface by drilling three small holes, aligned with the holes in the brass case, then attach the barometer with the three brass wood screws.

Operation: Barometers measure air pressure by one of several means. By far the most common type is the

“aneroid” barometer, which uses an air-tight chamber and a series of levers and linkages to record changes in pressure. As the air pressure changes, the chamber expands or contracts, moving the levers, which in turn rotate the black pointer up or down the dial. The

Cape Cod

®

Marine Barometer uses this highly accurate method.

Å Set-screw

To assist in following the movement of the pointer, the Cape Cod

®

Marine Barometer has a set-hand that is controlled by the small brass knob in the center of the glass dome. Turn the knob so the gold set-hand aligns with the black pointer. The next time you check the barometer, tap the glass gently to release any built-up tension in the movement. By then comparing the position of the pointer to that of the set-hand, you will be able to determine whether the pointer has risen or fallen and by how much.

Air pressure is designated by various units of measurement, the most common being “inches of Mecury” (“Hg”). Barometric pressure typically ranges between 28 and 31 inches of

Mercury. The outer scale on the face of the Cape Cod

®

Marine Barometer denotes inches of

Mercury. A second unit of measurement is “millibars,” with a range of 950 to 1050 millibars being typical under normal weather conditions. The inner scale around the face of the Cape

Cod

®

Marine Barometer is in millibars.

The words “Foul,” “Change,” and “Fair” on the face of the dial provide a general guide only.

Usually, when the barometric pressure is low, the weather is wet, while high pressure usually indicates dry weather. However, there are many exceptions to these generalizations. It is not at all unusual for it to be raining when the barometer is high, particularly during the warmer months when precipitation often is associated with thunderstorms and frontal passages, rather than strong low pressure systems.

It is also quite common for the barometer to change very little for long periods of time.

Again, this is especially common during the warmer months when air pressure tends to be very steady. The vast majority of the time, the barometer will read between 30.00” and

30.30.” If you are concerned that your barometer has not changed for a long period of time, you can easily check it by monitoring the readings for a few days and comparing them to the readings given on your local weather forecast.

The Cape Cod

® Μarine Barometer requires no maintenance and should provide many years of trouble-free operation. If servicing is ever needed, package the instrument carefully and return it, with a note enclosed, to the manufacturer at the address below.

335 Lower County Road

P. O. Box 454

Harwich Port, MA 02646

Web site: www.capecodwindandweather.com

Phone: 508-432-0970

Toll-free: 877-438-2294

Fax: 508-430-6020

E-mail: service@ capecodwindandweather.com

- Keeping an eye on the weather since 1939! -