George Graham 倫敦，機芯號 756，高 1875 mm，約 1737
George Graham, London, Movement No. 756, Height 1875 mm, circa 1737
An important, in museum quality precision regulator with grid iron and brass pendulum and date - 30 days power reserve
Case: oak. Dial: regulator dial aperture for digital hours, silvered, winding hole with bolt and shutter. Movm.: hexagonal brass full plate movement, numbered, Graham escapement, brass pendulum bob, knife edge suspension, winding stop device.
George Graham (1673-1751) is famous as a maker of superior clocks but it is little known that he also built excellent mathematical and astronomical instruments. Graham was an avid astronomer himself; we owe it to him that we know of two transits of Mercury, several eclipses and new stars. In 1725 he designed and built a mural quadrant at the Royal Ovservatory in Greenwhich for Halley, which enabled him to observe two changes in the position of fixed stars. In addition to building several quadrants, Graham is known for creating a number of large zenith sectors; he delivered astronomical instruments to France that were used in research on the shape of the earth carried out in the North. These instruments were technological prototypes and England soon became a production centre for astronomical and other instruments – it remained so for the rest of the century. In Europe Graham was much better known for his scientific instruments than for his clocks. In 1720 he became a Fellow of the Royal Society, where he held lectures on his various inventions.
It was Graham who developed the crucial technical details for precision clocks that were taken up and developed further by other great makers such as Thomas Mudge, John Arnold, John Ellicott and Thomas Earnshaw. Before Graham began making precision clocks, regulators were rather inadequate because there were so many unknown factors with regard to accuracy. Graham used his enormous knowledge to go further than ever before and he built a perfect standard regulator that became famous for its easy to read dial, the simple but elegant case and the top quality movement. A simple and clear-cut design that nevertheless was the most advanced construction of its time. It was a symbol for everything the "honest" clockmaker George Graham stood for.
Regulators in plain oak cases were usually built for use in observatories. They normally had a power reserve of one month and this extra complicated movement meant that the buyer had to pay a few guineas more – the movement needed an additional wheel. The movements had solid high rectangular brass plates with chamfered edges at the top, six heavy, locked baluster pillars, bolt and shutter locking devices, stop work and a screwed-on square 10 – 10.5 inch dial that usually had an upwardly curved aperture for the hours; each of the four dial feet was usually fixed on the front plate with three screws. For over 50 years Graham's regulator movement design was used to build this type of clock and even John Arnold used it in the early days.
Graham was the first to develop and build precision pendulum clocks (astronomical long case clocks), so-called (long case) regulators which at the time were used in many European observatories. The Royal Observatory in Greenwich was the first to acquire two of these clocks in 1725 and 1750.
Research on Graham's astronomical long case clocks showed that after the first delivery of the "Graham 1" = No. 621 and the "Graham 2" = No. 675 in 1725 to the Greenwich observatory, three other clocks were delivered to Vienna, one around 1737, one around 1740 to the private observatory of Johann Jakob Marioni (1676–1755), mathematician to the Viennese court, and a third one in 1738 to the new Jesuit observatory in Vienna. Marinoni's enthusiasm for accurate time measurement not only ensured that the Vienna observatories had excellent instruments and tools at their disposal, in 1745 it also produced a nearly 300 page paper entitled "De astronomica specula domestica et organico apparatu astronomico", where he describes the equipment in his observatory in incredibly detailed engravings.
Other observatories in Europe such as Uppsala and Paris only acquired Graham regulators after 1740. We know of only 10 astronomical regulators signed by Graham and of those only very few have survived, such as no. 756.
The 1738 annals of the Jesuit observatory state that "other new equipment includes a Newton telescope 5 feet long and a very accurate pendulum clock from the workshop of the famous English engineer Graham, tested by Graham himself in London. Both instruments together cost 370 Rhenish thaler." This means that the clock could be used for the first meteorological observations in 1738. Later annals confirm that in addition to the two Graham clocks in Marinoni's observatory, the Jesuit observatory owned a Graham regulator without compensation pendulum that would eventually be fitted with a gridiron pendulum, from around 1738 on.
Franz Xaver Freiherr von Zach, director of the Seeberg observatory in Gotha and publisher of the magazine Monatliche Correspondenz (Monthly Correspondence) writes in 1801: "[…] When P. Liesganig [director of the Jesuit observatory] was commissioned in 1772 by the government to draw a map of Galicia and Lodomeria, he had several astronomical instruments from the former observatory of the Jesuit College brought to Lviv, where he planned to set up a new observatory. [...] Liesganig brought several of the clocks from Vienna, one by Graham [the Jesuit observatory only had one], to which he had added a gridiron pendulum; one by Vötter, and others that had been constructed in the Vienna Jesuit College. If I remember correctly, the collection also included a clock by Le Paute with a second strike [a so-called "Durchgangsuhr"]".
After the suppression of the Jesuits the observatory in Lviv was shut down and shortly afterwards von Zach wrote about a visit to Lviv "[...] There is no shortage of astronomical pendulum clocks, among them a beautiful English one by Graham; however, the clocks are not being observed and they serve no purpose. These clocks have been spread among the professors and only serve to decorate their rooms. [...] As there are [on September 16, 1801] so many excellent astronomical instruments and clocks: it is a shame that these are rust away in chests and crates and are not being used but eaten up by green rust, [...]"
This was lucky for science and research – and especially for Graham's clock no 756. It is this clock that was delivered in 1738 to the Jesuit observatory in Vienna. Marioni's book of 1745 shows one of the Vienna Graham clocks in great detail as in design drawings. There are excellent illustrations of the movement without the dial from all sides, even the position and the environment are shown as well as the complete case and its dimensions. The drawings also show that a pendulum without compensation was used at the time and the case door was kept closed. No. 756 was also originally constructed in that manner. Its authenticity is proved by an embossed number "756" in the door jamb.
Source (and kind assistance): Jürgen Ermert: Vol. 1 of the series "Präzisionspendeluhren in Deutschland von 1730 bis 1940, Observatorien, Astronomen, Zeitdienststellen und ihre Uhren" (Precision Pendulum Clocks in Germany from 1730 to 1940 - Observatories, Astronomers, Standard Time Agencies and their Clocks)
George Graham (1673-1751) is sometimes referred to as the most famous clockmaker in history. However, his importance as a maker of clocks as well as fine scientific instruments was recognised even in his life time - James Bradley (1693-1762), an English clergyman and astronomer wrote in a letter in 1748: "For I am sensible, that if my own endeavours have, in any respect been effectual to the advancement of astronomy; it has principally been owing to the advice and assistance given me by our worthy member Mr. George Graham; whose great skill and judgement in Mechaniks, join'd with a complete and practical Knowledge of the Uses of Astronomical Instruments, enable him to contrive and execute them in the most perfect manner." ("A letter to the Right Honourable George Early of Macclesfield concerning an Apparent Motion Observed in Some of the Fixed Stars." Philosophical Transactions, Vol. 45.)
錶殼 非常好, 維護, 整修過
錶盤 非常好, 維護
机蕊 非常好, 維護, 走動正常
錶盤 非常好, 維護
机蕊 非常好, 維護, 走動正常