Three scientific instruments

74 Three scientific instruments

A Regency flame mahogany stick barometer by Cary.

The ogee pediment is set over a glazed, finely engraved silvered brass register plate incised with a scale from 27 to 31 degrees and ‘Fair, Change and Rain’. The trunk has ebonized stringing and terminates with the original concealed barometer cistern tube within the turned cistern cover. Signed ‘Cary London’. English, circa 1820. William Cary (1759-1825) was an English instrument maker who trained under Jesse Ramsden. Working from premises in The Strand from 1789, he produced mechanical calculators, measuring instruments, telescopes, microscopes, navigation and survey equipment, which were used as far afield as Russia and India. He often collaborated with his brother John, the renowned cartographer, to make some of the most exceptional globes of the late 18th and early 19th centuries.

Height: 37 ½ in (95cm) Width: 5 ¼ in (13.5cm)

A George III mahogany thermometer by John Dollond. It is of slender rectangular form, the top of the frame is removable to aid the cleaning of the glass. The silvered register is engraved with the temperature to 220 degrees (rather than the usual 110) and ‘Temperate, Spits, Summer Heat, Blood Heat, Boil and Water Boil’, signed ‘Dollond London’. English, circa 1790.

Height: 23in (58cm) Width: 2¼in (6.5cm) A bow-front marine barometer by John Dollond. It is of slender cylindrical form with a silvered register plate enclosed by a hinged thermometer flap and mounted on a plain shaft. The brass gimbal weighted reservoir has pierced sides on the mounting. The plate engraved ‘Very dry, Set Fair, Fair, Rain, Stormy, Dolland London’. English, circa 1820.

Peter Dollond (1731-1820), the son of the Huguenot silk weaver John Dollond, set up as an optician at the age of 20 and became the most eminent optical instrument maker of the late 18th century. Such was his success that his father gave up the silk industry and joined him in 1752. The Dollonds became notable for the quality of their optical products. John Dollond was appointed optician to King George III and the Duke of York and Albany, who granted him ‘His Majesty’s Royal Letters’ for his refracting telescope. Other customers included Captain Cook, Vice-Admiral Lord Nelson, Frederick the Great and Thomas Jefferson. At the Great Exhibition of 1851, the Dollonds were awarded a medal for excellence. In 1763, Peter invented the apochromat and began the manufacture of bifocal spectacles in 1781. Dollond & Co merged with Aitchison & Co in 1927 to form Dollond & Aitchison, the well-known British chain of opticians.

Height: 35in (89cm) Width: 2½in (6.5cm) Max depth of gimbal: 8½in (21.5cm)