Astronomical Regulator: Graham 3

 

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Bought from George Graham in 1750, this clock remained at the Observatory until its closure in 1998. It is now in the care of the National Maritime Museum (Object ID: ZBA0709).

 





1771 July 9: (From Greenwich Observations): 'In the Afternoon the [transit] Clock was taken down, to have Ruby Escapements applied to the Pallets. In the mean time, till the clock is set up again, the Observations are continued by the time of the Assistant-Clock standing in the same Room, which had been previously brought to keep time with the Transit-Clock. Whenever this is wound up, to prevent its losing time, the Wheels are kept going round by pushing the Second Hand forward with the Finger, which answers the Purpose very well.' In the published observations, Maskelyne records on 15 July, that 'The Observations are now continued by the Time of the Transit-Clock, as usual, which was set up again Yesterday about Noon, having been cleaned and had a Pair of highly-polished hard Ruby Escapements applied to the Pallets by Mr. JOHN ARNOLD, Watchmaker, which it is apprehended will require no Oil, and produce a much more regular Going of the Clock.'
1779 On 20 Jan, the clock was taken down to have some alterations made. It was replaced on 28 Feb, having had: 'a new steel Swing-wheel applied to it; the Pivot Holes of the Pallets and Swing-wheel jewelled; the Support of the Pendulum strengthened by brass pieces; and a perpetual Ratchet added to keep the Clock going in winding up, instead of the former machinery for that purpose, which had been found to fail for some Time. The whole by Mr. Arnold. From Greenwich Observations, p.145 & p.148
1780 On 13 Jan, 'taken down from the Wall on the South Side of the Room, to which it was fixed by Pieces of Wood let in, and was fixed up to a new stone pier lately built for it, nearer to the Transit Instrument. The pendulum is fixed to the Pier, independent of the Clock-case, by Means of a large and strong Plate of Brass, to which the Pendulum is attached, and which was firmly wedged in the Pier by running in melted Pewter. The new Clock [?] was fixt up in the former Place of the Transit Clock, and the Observations will be made by it for a few days till the Transit Clock is brought to keep sidereal Time.' On 8 February, Maskelyne records that in its new position, the clock was found to be going very irregularly 'owing to the Spring having got bent, which gave the Pendulum a wabling Motion.' The 'new Clock' was therefore used for the transit observations until a new Spring could be fitted. Observations using Graham 3 restarted on 22 Feb. From Greenwich Observations, p.167 & p.169 & 170. The clock referred to as the 'new Clock' was probably one of the two Arnolds Arnold 1 or Arnold 2. These were ordered in 1773 for installation in the East and West Domes (formerly the East and West Summerhouses). Although they had been present in the domes for a while, by 1779 they were still awaiting the installation of proper fixings to secure them to. This was probably because the two Equatorial Sectors that they were supposed to be used with which were supplied by Sisson in 1773 were deemed unusable on account of structural weaknesses
1911 In Ball Lobby (at foot of stairs leading to the Octagon Room). The 1911 Inventory (RGO39/4) lists it as the Ball Clock
1926 In Astonomer Royal's Office in the north wing on the main floor of the South Building. Cleaned and overhauled (Order No. 938 of 3 Sep). (1926 Inventory: RGO39/5)
1927 Cleaned and overhauled (Order No. 245 of 14 Oct). (1926 Inventory: RGO39/5)