(Waywiser)

DOLLOND, Peter

Editore: London, 1800

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A mahogany and brass-mounted waywiser, the wheel with iron tread and six rounded spokes, 31¾ in. (80.5 cm.) diameter. Surmounted by a circular engraved silvered-brass dial inscribedÂDollond London,Âenclosed by a hinged glazed door complete with clasp. The dial has two hands and records yards, poles, miles and furlongs. This instrument is used to measure distances, most usually roads and dates back to the roman period. It was re-introduced into Europe in the seventeenth century. The outer rim, or tyre, may measure 36, 72 or 100 inches, which gives wheel diameters of about 11.5, 23 and 32 inches. The revolutions of the wheel are recorded in the large dial mounted in a box below the handle. The face identifies the maker as Dollond. Noted makers 'included Heath, Heath & Wing, Martin, Adams, Dolland, Cary and W & S Jones' (Turner). The wheel usually measures 8.25 feet in circumference [as here], such that two revolutions equal one pole. The larger hand on the dial makes one sweep per mile (320 poles or 8 furlongs). The shorter hand indicates the number of miles travelled.ÂThe famous firm called Dollond began with John Dollond (1706-61). His father was involved in silk weaving, and John followed in the same trade. Because his father died when John was young, John's formal education was cut short. He managed to teach himself Greek and Latin, and various branches of science and mathematics. Astronomy and optics became a hobby of his. However, it was his son Peter (1730-1820) who after working as a silk weaver with his father, opened and opticians in 1750 in Kennington, London. After two years, his father also gave up the silk trade and joined Peter.John Dollond was a brilliant theorist and experimenter. His greatest achievement, by far, was the invention of the achromatic lens. For a century, it had been believed that all lenses - and therefore all telescopes - caused some degree of colour distortion. John Dollond first showed how to compensate for those distortions, and then demonstrated how they could be altogether eliminated, disproving one of Isaac Newton's theories of optics. The first telescopes without colour distortions were produced in the Dollond shops. Peter Dollond lacked theoretical knowledge, but he had enormous practical skill. In his workshop, he designed and built precision devices for astronomy and celestial navigation. He produced countless refracting and reflecting telescopes and, with his father, built three-foot-long telescopes that could do the work of older telescopes that were 45 feet long. When John Dollond died in 1761, Peter Dollond took on his brother as a partner. When that brother died, Peter Dollond started working with his nephew, George Huggins, who changed his name to George Dollond.George Dollond (1774-1852) had both his uncle's mechanical skill and his grandfather's grasp of theory. He built numerous precision astronomical instruments with exacting attention to detail. He also invented an 'atmospheric recorder' by which continuous measurements of temperature, wind, rainfall, humidity, pressure and other weather data were printed on rolls of paper. After Peter Dollond died in 1820, George Dollond ran the family business until his own death, on 13 May 1852, which marked the end of the remarkable Dollond century (The Vauxhall Society). Provenance: Christie's, Glasgow, 14.4.1994 lot 173. Turner (1998) p. 45. Warner (2019); Worms & Baynton-Williams (2011).

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Dati bibliografici

• Titolo: (Waywiser)
• Editore: London
• Data di pubblicazione: 1800
• Rilegatura: No binding
• Cataloghi dei venditori:
  • Natural History, Decorative & Science