Unusual 6.5-inch [165mm] diameter brass-cased aneroid barometer. c1870 
Unusual 6.5-inch [165mm] diameter brass-cased aneroid barometer. The engraved silvered brass dial with central cut out, revealing the aneroid movement, bearing twin curved mercury Fahrenheit and alcohol Centigrade/Réaumur thermometers and protected by bevelled plate glass. The case profile exaggeratedly dished. The barometer was sited on the bulkhead of a steam ship, as evidenced by the traces of the four added mounts on verso.