Decorative mercury-filled thermometer on an ivory scale (calibrated from -5 to 125 degrees Fahrenheit) set within a gilded Baroque-style wooden frame.
Dimensions: Frame 20" x 5.5" (51.0 cm x 14.5 cm), ivory scale width 1.1" (2.7 cm)
The scale is marked at certain values: Temperate (55 deg F), Summer heat (76 deg F), Blood heat (98 deg F), Fever heat (112 deg F).
Thomas Rubergall was an optician and instrument maker of mathematical and philosophical devices, active in London from 1802-1854. He made instruments for the Duke of Clarence and King George III, as shown by a surviving copy of his trade card at the Science Museum, London (object number 1934-121/100).
For further details see the following references:
Edwin Banfield (1991), ‘Barometer makers and retailers, 1660-1900’, Baros Books, p.189.
Nicholas Goodison (1977), ‘English Barometers 1680-1860: A History of Domestic Barometers and Their Makers and Retailers’, Antique Collectors’ Club, pp. 85, 91, 92.