Porta & Co, c.1810-20.

The edge moulded mahogany case is veneered in a herring bone pattern, outlined with boxwood stringing and fitted with a glazed hinged door, broken architectural pediment and turned cistern cover.
The silvered brass scale is well engraved with a Fahrenheit temperature scale and a mercury filled thermometer along side a 27"-31" scale fitted with a sliding vernier. The dial is engraved with the makers name, 'Porta & Co. Fecit'.
The exposed mercury tube has a glass bulb cistern concealed behind the turned mahogany cistern cover which has an unusual turned collar above and inset with a Mother of Pearl roundel.

Height 39".