Astronomical Regulator(s): Shelton


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John Shelton was a famous London clockmaker who made five astronomical regulators for the Royal Society for timing the transits of Venus in 1761 and 1769.

Their exact history is complex. One arrived at the Observatory in Greenwich in 1922. On the Observatory’s demise in 1998, it passed into the care of the National Maritime Museum (Object ID: ZBA1765). One or more of the others also spent time at the Observatory at an early date.

The history of the Shelton Regulator(s) at Greenwich is in the process of being unravelled. What follows below is currently in the form of working notes.


1922 28 Nov, 'per Hydrographer' and placed in Clock Room (1911 Inventory: RGO39/4/61)
1924 From the 1911 Inventory (RGO39/4/61)
Fitted with contact work to give hourly signal & apparatus fo correcting by solenoid & permanent magnet (order no.299 of 9 Jan)
15 Oct, Set of weights acquired for adjusting rate of the clock
18 Nov, Transferred to Abinger  for Time Signal service
'Condensor Order No 507 of 25/11/24 included in circuit'
1926 At Abinger Magnetic Station (1926 Inventory: RGO39/5/22)
1931 30 Apr, overhauled and cleaned (order 272). (1926 Inventory: RGO39/5/22)
1932 27 Feb, overhauled and cleaned (order 469). (1926 Inventory: RGO39/5/22)
1933 16 Sep, overhauled (order 821). (1926 Inventory: RGO39/5/22)
1948 In the reporting year 1947 to 1948, the clock was still in use in the Abinger Magnetic Station was sent to Bradford on Avon where it was thoroughly overhauled and subsequently re-intalled at Abinger (1948 Annual Report). The report continues: 'The clockwork drives for the slow and quick run magnetographs, which have proved troublesome in operation are at present being reconstructed in the watch repair shop'


In addition to the Shelton Regulator, the Royal Observatory at Greenwich owned four other pendulum clocks by Shelton. Referred to as journeyman, assistant or secondary clocks they were used alongside the other regulators. Click here to read about them.



Confusingly, the Inventory of 14 December 1774 (which comes in a number of slightly different versions (RGO6/21/133, RGO4/309/2, RGO/309/4, RGO4/309/5)) lists three clocks that specifically refer to Shelton. One was a journeyman or assistant clock in the Great Room (Octagon Room). The others are both described as 'A month clock with a compound pendulum, by Shelton, with new Ruby Pallets'. One was in the Transit Room, and appears to be being used as the Transit Clock. The other was in the East Dome (formerly the Eastern Summerhouse). It is likely that the former was the regulator now known as Graham 3 and that the other was probably Graham 2 which was absent from its normal location in the Quadrant Room. The reason for believing this is that in the preface to his first volume of observations, Maskleyne descibes the clock now known as Graham 3 as 'an excellent Astronomical clock made with a gridiron pendulum, made by Mr John Shelton under the direction of Mr Graham, and fixed up in the transit-room'.