Aneroid* Barometer Development

Posted At : May 3, 2007 10:45 AM | Posted By : name
Related Categories: Meteorological Instrument History

Julien Fiez, founder of Belfort Instrument Company is credited with early U.S. development of the aneroid barograph for the company he founded in Baltimore in 1876. These early devices functioned much the same as bellows type barometers fuction today by measuring the expansion and contraction of a metal bellows device that has a partial vaccuum on the inside and is exposed to atmospheric air pressure on the outside. The bellows contracts with high atmospheric air pressure and expands with low atmospheric air pressure and is mechanically connected to a recording pen or needle indicator.

Belfort Instrument Company still manufactures aneroid barometers that meet stringent U.S. Military Specifications (Mil-B-17089) and National Weather Service Specifications.

*(Aneroid: operating by the effect of outside air pressure on a diaphram forming one wall of an evacuated container)

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Accuracy of The Human Hair Hygrometer

Posted At : April 28, 2007 2:06 PM | Posted By : name
Related Categories: General,Meteorological Instrument History

The human hair hygrometer was invented by H.B. De Saussure in the 18th century and has stood the test of time as a reliable and accurate method of measuring relative humidity, not actual amount of water vapor in the air.

The increase in length of human hair as relative humidity changes from 0 to 100% is 2.5% of the overall hair length. Hundreds of strands of untreated human hair are collected from remote areas of the world, treated to remove fats, washed and dried and used in each Belfort Recording Hygrothermograph to provide a consistent and accurate (1% RH at room temperature) measure of relative humidity over many years of service in museums, library's and industry.

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