John Russel Barometer.
Description from owners (Hotspur Ltd) of barometer: "Known as his famous Royal Wheel Barometer, the painted white dial with gilded bevelled edges, presents two subsidiary indexes, having cut steel hands, signed 'J Russell, Falkirk inv't et fecit - watchmaker to R H the Prince Regent' contained in a mahogany case edged with gilt metal rope twist mounts, having two "verre eglomise" panels above and below the dial delicately executed in gold on a black ground; the thermometer above set on a silvered brass plate engraved with three scales, Reaumer, Fahrenheit and the Royal Society, with Russell's signature at the bottom right hand corner of this plate. The case in surmounted by a fine gilt metal Prince Of Wales feather finial."
This photo is not scanned. You can see the original in the Archives in Callendar House