George Graham (clockmaker)
He was born in Kirklinton, Cumberland. A Friend (Quaker) like his mentor Thomas Tompion, Graham left Cumberland in 1688 for London to work with Tompion. He later married Tompion's niece, Elizabeth Tompion.
Graham was partner to the influential English clockmaker Thomas Tompion during the last few years of Tompion's life. Graham is credited with inventing several design improvements to the pendulum clock, inventing the mercury pendulum and also the orrery. He was made Master of the Worshipful Company of Clockmakers in 1722.
Between 1730 and 1738, Graham had as an apprentice Thomas Mudge who went on to be an eminent watchmaker in his own right, and invented the lever escapement, an important development for pocket watches.
He was widely acquainted with practical astronomy, invented many valuable astronomical instruments, and improved others. Graham made for Edmond Halley the great mural quadrant at Greenwich Observatory, and also the fine transit instrument and the zenith sector used by James Bradley in his discoveries. He supplied the French Academy with the apparatus used for the measurement of a degree of the meridian, and constructed the most complete planetarium known at that time, in which the motions of the celestial bodies were demonstrated with great accuracy. This was made in cabinet form, at the desire of Charles Boyle, 4th Earl of Orrery.
The deadbeat escapement is often erroneously credited to George Graham who introduced it around 1715 in his precision regulator clocks. However it was actually invented around 1675 by astronomer Richard Towneley, and first used by Graham's mentor Thomas Tompion in a clock built for Sir Jonas Moore, and in the two precision regulators he made for the new Greenwich Observatory in 1676, mentioned in correspondence between Astronomer Royal John Flamsteed and Towneley
His major contribution to geophysics was the discovery of the diurnal variation of the terrestrial magnetic field in 1722/23. He was also one of the first to notice that auroras are related to magnetic field variations. The compass needles he produced as an instrument-maker were used by many of contemporary magneticians. Around 1730, George loaned approximately £200 to John Harrison so that he could start work on his marine timekeeper known later as H1. George was commonly known in the trade as 'Honest George Graham'.
Examples of his work
- A 28-day duration longcase regulator with dead beat escapement c. 1745 Moyse's Hall Museum Bury St Edmunds UK
|Wikisource has the text of the 1885–1900 Dictionary of National Biography's article about Graham, George (1675-1751).|
- "DServe Archive Persons Show". .royalsociety.org. Retrieved 15 January 2012.
- Watch-Wiki: George Graham
- Harold Bagust, "The Greater Genius?", 2006, Ian Allan Publishing, ISBN 0-7110-3175-4 (page 15)
- Milham 1945, p.185
- Glasgow 1885, p.297
- "Clocks". Encyclopaedia Britannica, 11th Ed. 6. The Encyclopaedia Britannica Co. 1910. p. 541.
- "Deadbeat escapement". Encyclopedia of Clocks and Watches. Old and Sold Antiques Marketplace. Archived from the original on 20 May 2008. Retrieved 8 June 2008.
- Betts, Jonathan Regulators in Bud, Robert; Warner, Debra Jean (1998). Instruments of Science: An Historical Encyclopedia. Taylor & Francis. ISBN 0-8153-1561-9. p.121
- Flamsteed, John; Forbes, Eric; Murdin, Lesley (1995). The Correspondence of John Flamsteed, First Astronomer Royal, Vol.1. CRC Press. ISBN 978-0-7503-0147-3. Letter 229 Flamsteed to Towneley (22 September 1675), p.374, and Annotation 11 p.375
- Andrewes, W.J.H. Clocks and Watches: The leap to precision in Macey, Samuel (1994). Encyclopedia of Time. Taylor & Francis. ISBN 0-8153-0615-6. p.126, this cites a letter of 11 December, but he may have meant the 22 September letter mentioned above.
- Graham, George (1724): An Account of Observations Made of the Variation of the Horizontal Needle at London, in the Latter Part of the Year 1722, and Beginning of 1723. Phil. Trans. 33, 96–107, doi:10.1098/rstl.1724.0020
- Graham, George (1724): Observations of the Dipping Needle, Made at London, in the Beginning of the Year 1723. Phil. Trans. 33, 332–339, doi:10.1098/rstl.1724.0062
- Graham, George (1748): Some Observations, Made during the Last Three Years, of the Quantity of the Variation of the Magnetic Horizontal Needle to the Westward. Phil. Trans. 45, 279–280, doi:10.1098/rstl.1748.0030
- Britten, Frederick J. (1894). Former Clock and Watchmakers and their Work. London: E. & F.N. Spon. p.89-97