According to Negretti and Zambra’s 1878 catalogue;
This instrument consists of a mercurial tube on the syphon principle; one side of the syphon, the closed end, being about 33½ inches long, and the other only a few inches in length. To this short end, or leg, is joined a length of glass tubing of a much smaller (internal) diameter; both legs being of equal length, the smaller tube is filled with a fluid many times lighter in terms of specific gravity than mercury ; the rising and falling of the mercurial column in the large tube having a lighter fluid to balance, and that dispersed over a larger space by reason of the difference in the diameter of the two tubes a longer range is obtained, due to the unequal capacity of the two tubes and the difference in the specific gravity of the mercury and the second fluid employed.
This barometer has a rate of expansion of six inches to one inch of the ordinary mercurial barometer. The catalogue further states that this form of long range barometer is not of any scientific value, but is merely a curiosity a a weather indicator.
This magnificent barometer is offered for sale in excellent original condition, the gothic styled case with well-carved fretwork below the silvered register plates. The pink fluid makes for very easy pressure readings from a distance. It is also fitted with a mercury thermometer.
The firm Negretti and Zambra (active 1850 – c. 1999) were opticians and scientific instrument makers to Her Majesty Queen Victoria, Prince Albert and Edward VII of the United Kingdom, the Royal Observatory and the British Admiralty.
Guaranteed for 3 years.
Price includes delivery within mainland UK.
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