Boxwood differential thermometer by Watkins & Hill

An early boxwood differential thermometer by Watkins & Hill of London, circa 1825.

Signed to the rear of the thermometer scales: WATKINS & HILL 5 CHARING CROSS LONDON.

Both scales divided 50 - 0 – 50.

Height: 37 cm.

Width: 26 cm.

Depth: 14 cm.

The thermoscope, or differential thermometer, used to measure the transmission of heat was invented in the early nineteenth century by the physicist Benjamin Thompson, Count Rumford.

Watkins & Hill, 1818 - 1856, Mathematical instrument maker, Optical instrument maker, Optician, Philosophical instrument maker.

Watkins & Hill traded at 5 Charing Cross, London, England; partnership between Francis Watkins and William Hill (active 1810-47); Firm founded by Francis Watkins (bap. 1723, d.1791, active 1747-84); about 1747 - began trading in own right at Sir Isaac Newton's Head, 4/5 Charing Cross (1747); Charing Cross (1774-82) & 5 Charing Cross (1782-4), London, England; 1758-1761 - agreement with John Dollond (1706–1761); 1763-1774 - partnership with Addison Smith as Watkins & Smith; 1784 - Francis Watkins retired and was succeeded by his nephews Jeremiah Watkins (d. 1810) and Walter Watkins (d. 1798); 1810 - William Hill (d.1847), an employee, ran the business; 1818 - Jeremiah's son Francis Watkins (1800-1847) became a partner and the firm traded as Watkins & Hill; 1856 - acquired from the family by the C A and F H Elliott, sons of William Elliott, a mathematical instrument maker; succeeded by Elliott Brothers and associated with Negretti & Zambra.

Price

This object is eligible for a Certificate of BADA Provenance