The development of the barometer had its origins in Torricelli’s 1644 experiment that identified atmospheric pressure. Many changes in design have since taken place in order to produce instruments that are:
- Simpler to use and read.
- More compact and transportable.
- More sensitive and accurate.
Examples of barometer design include:
- Water-based barometers indicate changes of atmospheric pressure by the motion of a column of water instead of mercury. Though often a beautiful and functional piece of home decor with surprising accuracy, water barometers are delicate and somewhat impractical for general use.
- Mercury barometers are still used for scientific purposes, mainly in laboratories and weather offices. They tend to be expensive and require training and skill to operate properly. In addition, given the risk of breakage and exposure to toxic mercury, health and safety regulations means that this type of barometer is increasingly unavailable to the general public.
- Aneroid barometer design was perfected and patented by Vidie in 1884 and this type of barometer is still in widespread use today and considered by many to be the ‘classic’ barometer design.
- These barometers employ the use of a strong spring and a small, flexible metal box called an aneroid cell (also called chamber or capsule) in which a partial vacuum is produced. Changes in air pressure results in contraction or expansion of the chamber and movements are transmitted to a needle (pointer) by mechanical means.
- Are read by setting a large needle and tapping the barometer lightly to reveal whether the pressure is falling or rising. Many aneroid barometers have 2 needles: one that automatically follows the changes in atmospheric pressure while the other remains fixed until moved by hand. Most aneroid barometers on the market require a calibration curve to yield accurate pressures.
- Compare favorably to electronic instruments regarding keeping a Headache Diary. They typically have a large and clear display making reading of measurements a simple and straightforward process.
- Analogue weather stations typically consist of an aneroid barometer, thermometer and hygrometer (humidity). Theses typically come in two styles:
- Traditional ‘banjo’ style, where the barometer is mounted in a central position and is the largest dial of the three instruments, or
- Contemporary style, where the three instruments are smaller but equal size and arranged on a rectangular wooden frame that can be either horizontal or vertically mounted.
- Barographs are used to record atmospheric pressure as a graph utilizing a rotating drum and aneroid barometer mechanism.
- Other types and variations of barometer include the Shark Oil Barometer, Basin Barometer, Wheel Barometer, Fortin Barometer, Hooke’s Otheometer, Cistern Barometer, Stereometric Barometer, Siphon Barometer, Balance Barometer, Multiple Folded Barometer and Collins Patent Table Barometer.
- Digital equipment.
- An economical alternative to a precision aneroid barometer is an electronic barometer. Professional versions have the ability to record and offer digital output, allowing uploading to PCs and various software applications.
- Digital weather stations can include temperature, barometric pressure and humidity readouts. Though usually less precise than a dedicated digital barometer, professional versions still offer a high degree of accuracy and some may include data loggers and the ability to connect to a PC.
- As technology progresses, wrist watch equipment is becoming increasingly available. Aside from barometric readings, some also include altimeters and thermometers. Higher end models are accurate enough for keeping a headache diary and provide the ultimate in terms of convenience.