A GEORGE II MAHOGANY MONTH-GOING LONGCASE REGULATOR

JOHN ELLICOTT, LONDON, CIRCA 1755

細節

A GEORGE II MAHOGANY MONTH-GOING LONGCASE REGULATOR
john ellicott, london, circa 1755
The silvered regulator dial with shallow arched top centered by a pendulum regulation ring with a blued steel hand flanked by the signature Ellicott, London, the regulator dial with outer Arabic minutes, large diameter seconds ring below 60 with observatory markings and Roman hour aperture below the centre, all hands finely sculpted of blued steel, latches to the dial feet and to the six large baluster pillars for the massive movement with shouldered plates, end-capped wheel train with six crossings, Graham-type deadbeat escapement with jewelled pallets, Ellicott's own gridiron pendulum, the massive brass bob with central glazed compensation viewing aperture and flanked by twin calibrated rating nuts with blued steel pointers, steel wishbone suspension spring with a brass pointer swinging against the original calibrated paper beatscale, bolt-and-shutter maintaining power, Ellicott's security winding device employing a brass bar positioned below the backplate, the well-proportioned case with caddy top, brass-lined reeded pilasters flanking the hood door and glazed sides, chamfered angles to the arched trunk door, the plinth with raised octagonal panel above the double-skirted foot with carved apron

來源

The collection of the late David P. Wheatland, Curator, Harvard University Collection of Historical Scientific Instruments

出版

Tom Robinson The Longcase Clock, Woodbridge, 1981, pp. 387-393, pls. 11/4-12
R. W. Symonds, A Book of English Clocks, London, 1947, pl. 69

拍品專文

John Ellicott, F.R.S., 1706-1772 is considered one of the greatest 18th. century British clock and watch makers. His highly successful career was attributable to his scientific invention and the consistant high quality of all of his work which can only be said of the great clockmakers. Ellicott is principally remembered for two things, the development of the ruby cylinder escapement and his experiments on the pendulum - in particular the gridiron. In 1752 he presented a paper to the Royal Society Contrivances for preventing the Irregularity of Pendulums Asising from Temperature, published in the Philosophical Transactions. In it he claimed to have originated the principle of compensation. John Harrison, 1693-1776, had the same claim but stated that his idea was first. It was also claimed that George Graham, 1675-1751 was the first. Finally it was adjudged that Graham was the first inventor but that Harrison had constructed a pendulum on a similar principle quite unaware of Graham's own invention. It was further adjudged that Ellicott's version had no resemblance to either of them and was a great improvement!
Despite the excellent results from his pendulum few were made in comparison to the number of regular gridirons used by other contemporaries such as Mudge or Graham. The reason was presumably the cost, for the the bobs were constructed to the most exacting measurements and the micrometer adjustment device was a work of art in itself which one might fancifully like to believe is why Ellicott designed it with a glazed portal.
A similar, slightly later example, was sold in these rooms, The Samuel Messer Collection, 5 December, 1991, lot 35 for £77,000