Astronomical Regulator: Graham 2


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George Graham. Oil on canvas by Thomas Hudson, c.1739. The Board of Trustees of the Science Museum. Reproduced under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 Licence (See below)

Edmond Halley in about 1736. Engraving by William Thomas Fry from an original picture ascribed to Dahl in the possession of the Royal Society. From Portraits of Eminent Men, Society for the Diffusion of Useful Knowledge, C Knight, London, 1845

Delivered in the mid 1720s, numbered 675 on the backplate, and known as Graham 2 since the mid 1830s, this regulator by George Graham remained on the inventory of the Observatory until 1998 when it was transferred to the National Maritime Museum on the Observatory's closure (Object ID: ZBA2212). Over the years, it has been put to a wide variety of uses and much modified.


Graham's numbering system

When the great English clock maker Thomas Tompion died in 1713, his business partner George Graham (1673–1751) and his wife (Tompion's niece) inherited the business. Rather than start afresh with new sequences of serial numbers, Graham decided instead to continue with those that were already in use. As a result, the movements of his clocks have serial numbers that go from about 585 to 780. Sometimes the case was stamped with the same number and sometimes the winding key too (examples of which can be seen in and clock 590 and clock 707).

None of Graham's business ledgers are known to have survived and few clocks have come to light that can be dated with certainty. One that can is clock. 681 (1728), for which the original receipt survives.

The dates attributed to many of Graham's clocks seem entirely speculative and it is not clear on what basis each attribution has been made. It is possible that some dates were based on incorrect information published by Howse about the Greenwich clocks in his book Greenwich Observatory (1975). More on this below.

Graham supplied the Observatory with a total of four clocks. The first three were ordered by the second Astronomer Royal, Edmond Halley, in the early 1720s. The fourth was ordered by his successor James Bradley in the late 1740s.

Halley's three clocks consisted of a 'plain' week clock with a simple pendulum (last recorded in the 1818 inventory), and two 'plain' month clocks which also started life with simple pendulums. The clock supplied to Bradley originally had a grid-iron pendulum.  None of the three surviving clocks are numbered on the dial (as was the norm) and only the two month clocks supplied to Halley are numbered on the backplate, the numbers not being visible in normal use.

The simple pendulums of Halley's two month clocks were replaced by gridirons in the 1740s. Ruby pallets were fitted to both clocks in the 1770s followed by a re-casing in the 1790s. The clock supplied to Bradley was also fitted with ruby pallets in the 1770s. If the cases of the month clocks supplied to Halley were ever numbered, that information is now lost.


The naming of the Graham Clocks at Greenwich.

Prior to Airy's arrival as the sixth Astronomer Royal in 1835, the three surviving Graham clocks at Greenwich were typically given the same description in the inventories. It was perhaps in order to remove this ambiguity that Airy decided to allocate a number to each of the clocks – the two month clocks supplied to Halley becoming known as Graham 1 and Graham 2, and the one supplied to Bradley as Graham 3. All three are now in the collections of the National Maritime Museum.

Airy described the clocks as being 'marked' Graham 1, Graham 2 and Graham 3. He also used the word 'marked' when describing the other clocks. Although the word 'marked' was used in the introduction to all the volumes of observations from 1836 up to 1909, exactly how the Graham clocks were marked remains unclear as there is no mention of any form of mark in the Museum's records. All the other clocks are known to have been 'marked' on the dial - either originally, or perhaps after Airy's arrival in the case of the two Arnolds.

The ambiguities in the inventories taken prior to Airy's arrival make it is impossible to be absolutely certain that the two clocks Graham 1 and Graham 2 were never swapped over with one another and the information not recorded.

Graham 1 carries the number 621 on the backplate & Graham 2 the number 675. When Airy assigned the clocks numbers it is not at all clear that he was aware of the numbers on the backplates.

Although Howse was aware of the movement numbers of Graham 1 and Graham 2, for reasons that are unclear, he mistakenly dated them both to 1725. The frame numbers would suggest that they were in fact made several years apart, and this would seem to be borne out by other evidience.


The history of Halley's clocks prior to 1750

Following the death of John Flamsteed on 31 December 1719, Halley was appointed as his successor – the Royal Warrant confirming his appointment being dated 9 February 1720. Halley however was unable to move into the Observatory straight away as Flamsteed's widow, Margaret, was still there. When he finally took possession on 7 March he found the Observatory stripped of all its instruments. Initially, the Board of Ordnance fought to have them returned, (despite the fact that they had either been provided by Flamsteed himself or gifted to him).

At some point, it's not known when, Halley managed to obtain a sum of £500 to re-equip the Observatory. The report presented to Council of the Royal Society by the committee that carried out the Visitation in 1726 ought to have told us the exact date the money was promised; but due to an oversight, the date was never added as intended to the minutes:

'we desire leave first to acquaint you, we are informed the Dr [Halley] upon his humble petition to his Majesty before mentioned, obtained of him for the said purposes the sum of £500; & we have seen the Warrant of their excellencys the Lords Justices dated the __ day of __ to the Lords Commissioners of his Majesty's Treasury directing the said sum to be paid him [Halley] & without account.' (RGO6/21/23)

Little original material from Halley's time survives and that which does can be difficult to interpret. Two key primary sources are the minutes of the Council of the Royal Society and Halley's observing books.

Extracts from the Council minutes from 1710–1830 deemed relevant to the Royal Observatory were transcribed for the sixth Astronomer Royal, George Airy, and can be found in RGO6/21 for the years 1710–1791 & RGO6/22 for the years 1792–1830. What, if anything, was omitted is not known and a comparison with the originals would be needed to find out – a task that no researcher has yet undertaken in any sort of a systematic manner. The only minutes transcribed for the period while Halley was Astronomer Royal are for the years 1726 & 1727 and primarily relate to the Visitation of May 1726 and the bills for the individual instruments which are also undated. The cost of the week clock is recorded as £5, whilst the month clocks are recorded as costing £12 each.

The minutes are therefore of little use in determining any sort of chronology as to when the clocks arrived. We do know however that at the time of the visitation, the week clock was in the Transit Hut, whilst one of the month clocks was in the Great (Octagon) Room and the other was in the quadrant room.

Given the lack of chronological information in the minutes, it is necessary to look at other sources to try and work out when Halley's three clocks might have been ordered and when they might have arrived at the Observatory. Of particular use in this respect are the letters sent after Flamsteed's death by his most recent assistant Joseph Crosthwait (who seems to have remained in Greenwich until at least 1728) to to his earlier assistant Abraham Sharp. These were transcribed in part by Baily and published by him in 1835 in An account of the Revd. John Flamsteed. Other useful sources are the observing books and papers that were published in Philosophical Transactions.

The key events that took place between 1720 and 1726 are tabulated below:

1719/20, Jan 2: Crosthwait informs Sharp of Flamsteed's death on 31 Dec 1719
Jan 9: Mead tells Hearne: 'I have been so happy to get Flamsteed's place for Dr. Halley, by means of my Lord Sunderland.'

Feb 9: Warrant issued appointing Halley as the New Astronomer Royal (copy made for Maskelyne in RGO4/302)
Mar 15: Crosthwait informs Sharp that he left the Observatory on the 7th March and that Halley took possession of it at the same time, going on to say 'we have removed all the instruments mentioned in your letter; but the Office of Ordnance demand the sextant and the two clocks, besides several books; and insist that Sir Jonas gave them to the house, and not to the person; so the executrixes must either give them up, or go to law with the Crown.'
1720, Jul 16: Crosthwait informs Sharp that Halley 'has borrowed a quadrant of the Royal Society; but 'tis so ill made that he cannot use it. He [Halley] would now quit his claim on the two clocks, and everything else, if Mrs. Flamsteed would part from the sextant. She hopes, it he, or any other person should write to you for an account of what you know of the instruments, as she believes they will, that you be pleased not to satisfy them.'
Aug 20: Crosthwait informs Sharp: 'Dr Halley has not yet got any instruments, besides the quadrant I formerly mentioned; and I and now in more hope than ever that he will not be able to get the sextant from Mrs Flamsteed: for, notwithstanding she has long been threatened with a law-suit, there is not any as yet commenced against her, neither do I think there ever will.'
Oct 8: Crosthwait tells Sharp: 'The Office of Ordnance, I believe, rather than go to law, are willing to quit all claim to the clocks &c, and to allow Mrs. Flamsteed something for the sextant, in order to put a stop to the noise he [Dr. Halley] makes, that he can do nothing for want of this instrument. and thereby to get rid of him; for I am confident he has no friends amongst them at this time.'
Dec 10: Crosthwait tells Sharp: 'We hear nothing further, as yet, of Dr. Halley and the Office of Ordnance; but I believe, in a little time, we shall; for I am informed the Attorney-General has been consulted by them in this affair, and has given his opinion against the office: because it does not appear, by their books, that they ever either repaired, or made, any instruments at their expense. But, however, he says he thinks it proper to prefer a bill in the Court of Exchequer, to oblige Mrs. Flamsteed to set forth what title she has to them; but he further declares in his opinion (which I have seen by means of a friend), that if Mrs. Flamsteed can prove that Mr. Flamsteed repaired the instruments, it will be a strong presumption that the property is in her.'
1721, Mar 25: Crosthwait tells Sharp: 'I think, in a former letter, I told you that the Attorney-General had given his opinion against the Board of Ordnance; but at the same time he advised a bill to be preferred against Mr. Flamsteed's executrixes, to oblige them to declare what they knew of this affair. They have since preferred a bill accordingly, to which Mrs. Flamsteed and Mr. and Mrs. Hodgson have given an answer. But, whether the Board, upon this, will drop the thing, I cannot tell: but this we shall know next term.'
Apr 21: Crosthwait tells Sharp: 'Mrs Flamsteed gives in her answer to the Office of Ordnance's bill on Wednesday next: after which, we shall soon see what turn that affair will take.'

Jun 1: Crosthwait informs Sharp that Halley has pulled down the wall that held Flamsteed's Mural Arc and that he has 'built a little boarded shed, between the study and the summer-house, and has fixed a stone in the ground which stands about four feet high'. This was in preparation for receiving the Transit Instrument that was being made
Jun 24: Crosthwait tells Sharp: We hear nothing more of Dr. Halley, or the Board of Ordnance; therefore I am in hopes the law-suit is now at an end: I am more inclined to be of this opinion, because I am informed he has lost most of his interest with the Board Officers.'

Oct 1: First recorded observation made with new Transit Instrument (RAS.Add.Ms/38/2)
Oct 12: First mention of 'Horologium minus' and 'majus' in the manuscript observations - 'Steterat horologium minus me absente deinde vesperi secundum majus direxi ac statim habuimus sequentes observationes' (RAS.Add.Ms/38/4)
Oct 28: Crosthwait tells Sharp: 'I hear nothing further of Dr. Halley or the Office of Ordnance; the solicitor belonging to the office tells me the Board will proceed no further against Mrs. Flamsteed about the instruments.'
Nov 12: First use of the complete phrase 'Horologium majus' in the manuscript observations (RAS.Add.Ms/38/4/10)
Dec 28: Crosthwait tells Sharp: 'Dr. Halley has converted the sextant and quadrant houses into a pigeon-house.'
1721/2 Mar 6: Crosthwait tells Sharp: 'I hear nothing more of Dr. Halley about the instruments; so I believe the law-suit is at an end.'
1722, Jun 18:
Ready but unable to observe the lunar eclipse because of the weather (Phil Trans)
Nov 27:
Observation of the solar eclipse at Greenwich – presumably in the Great Room (Phil Trans)
1723, Oct 29: Observation of the Transit of Mercury with the 24? foot tube – presumably in the Great Room (Phil Trans)
1723/24 Feb 10: Crosthwait tells Sharp: 'Dr. Halley, I am informed, has got an order (by the favor and interest of the Lord Chancellor Parker) on the Board of Ordnance for £500, to be by him laid out in such instruments as he shall think proper. I hope, after he gets it, that he will either make new instruments, or purchase Mrs. Flamsteed's; the latter, I presume, he may like best, because he may then put some of the money in his own pocket.'
1724 Aug 1: Crosthwait tells Sharp: 'Dr. Halley has lately built a new meridian wall of stone; and, as I am informed, has a new quadrant a making, of the same radius with Mr. Flamsteed's arc. I presume his building this wall of stone is in order to find fault with Mr. Flamsteed for having one of brick, which was more liable to warp; and its being built so near the precipice of the hill caused it to sink, the hill being washed from it. Yet, for both these accidents, you know Mr. Flamsteed has made annually proper allowances. What he designs to do, I am satisfied is nothing but to cavil at, and undervalue, Mr. Flamsteed's performances; not to rectify any mistake, nor to corroborate and confirm what has been already done.'
1725, Jul 24: Crosthwait informs Sharp that 'Dr. Halley has got a quadrant of eight feet radius made; and Mr. Graham, the clock-maker, is now dividing it in the great room.'
Oct 20:
The date given by Baily as the first recorded observation with the mural quadrant (Baily & RAS.Add.Ms/38/200)
1726 May 11: First mention of 'Horologium Murale' in the manuscript observations (RAS.Add.Ms/38/4/222)
May 16: Date of the first and only Visitation that took place while Halley was Astronomer Royal. On the date of the visitation, the week clock was in the Transit Hut, one of the month clocks was in the Great Room and the other was in the Quadrant Room (RGO6/21/14)

Halley's observing books were removed by his executors and only came back into the Observatory's hands in 1765 when they were presented to the Royal Society by his daughter Catherine Price and subsequently deposited at Greenwich. They were examined in some detail by both Francis Baily and Stephen Rigaud in the 1830s, both of whom then published articles in MMRAS. When describing the books Baily wrote that they were difficult to make complete sense of as:

'The manuscripts here alluded to, are very badly and sometimes rather confusedly written; especially in the early part of the series: there being numerous computations, and much extraneous matter written on the same page with the observations, intermixed with and occasionally obliterating the more important figures: so that they cannot be so readily consulted with that ease and convenience, nor with that clearness and distinctness, which are desirable in works of this kind. ...

In fact, many instances occur about this period where there exists much confusion as to the clock [being used], and consequently (since they were each in a different room), as to the instrument employed: and the observations in such cases require a close examination. For, though Dr. HALLEY frequently mentions the clock used, yet he appears sometimes to have omitted it: which is the more to be regretted because all the observations with these different instruments and different clocks, are entered alike in the journals, without any discriminating mark or index.'

When going through the observations, Baily identified the following two terms that Halley used to describe the clocks prior to the arrival of the Mural Quadrant in 1725. They were first used by him in October 1721.

  • Horologium minus
  • Horologium majus

Baily thought that the Horologium majus was so called because it was used in the great room and that the term Horologium minus was used to by way of distinction for the week clock that was used with the Transit Telescope. It is not impossible however that the terms majus and minus referenced the difference in their length of going. Another possibility is that the two clocks may have been different sizes especially as in his paper, Rigaud states that Bradley referred to the week clock as 'the smaller' or 'the little clock' and the month clocks as 'large'. A future examination of Bradley's observations from the 1740s may shed more light on the matter as it would tell us if the terms the smaller and the larger were the words that Bradley actually wrote, or if the words were Rigaud's translation of minus and majus and minus.

After the arrival of the Mural Circle, the following term also started to be used:

  • Horologium murale

Prior to the arrival of the Horologium Murale, Bradley had also started to use the term monitor. Exactly what Halley meant by it is difficult to fathom. Baily gave us these thoughts on the matter:

'Beside these two clocks [the majus and minor], we occasionally meet the term monitor: but whether this was applied to either of the two above mentioned, or, whether it was what is now called a journey-man clock, or merely an alarm clock is difficult to decide at the present day.'

It should be noted however that there was no mention of anything other than the week clock and the two month going clocks being seen at the 1726 Visitation. Further research is required to see whether Halley used the term monitor after 1725 and also to establish if he was ever loaned a clock in the early days.

Taking all the evidence together, it seems probable that both the week clock and Graham 1 date from 1721 and that Graham 2 probably dates from 1725. We can also conclude that although the £500 for re-equipping the observatory was promised no later than February 1723/4, it might have been promised as early as mid 1721.

Given that the cost of fitting out the Transit Room was just £61.10.0 (RGO6/21/23) and the cost of fitting out the Great Room just £34.10.0 (RGO6/21/24), it is feasible that Halley may have initially decided to pay these bills out of his own pocket.

According to Rigaud, when Bradley became the new Astronomer Royal in 1742, he used Graham 1 with the Transit Instrument and Graham 2 with the Quadrant, whilst the week clock was kept for occasional use in the Great Room and substituted for Graham 1 and Graham 2 when they were out of service.

In Bradley's Miscellaneous works and correspondence (compiled by Rigaud), it is stated that:

'the clock by the transit instrument was taken down Sept. 3 [1742] and fixed up again very firmly by means of three pieces of oak plank, about 2½ inches thick and 10 broad, which were wedged fast into the brick wall.'

Earlier in the volume, it was also recorded that 'on the 3d of September [1742] the clock was fixed firmly against the wall, and its dial was made to face N.W. It should be noted that Howse (1975) mistakenly thought this was a reference to the week clock and that the week clock was the only clock to have been used with Halley's Transit.

Rigaud seems to have been under the impression that Halley was using Graham 1 rather than the week clock as the transit clock:

'There is an expression, also, which favours the conjecture of HALLEY having, at least sometimes, used the "horologium minus" with his transit; for one of the larger clocks having been taken down in 1742, the time of the sun's passage the next day is given by the little clock set up again in the transit-room." When the larger was brought back, we find "the little clock taken out of the transit-room, and set in the great room above stairs." There it appears to have been kept for occasional use; for when the other large clock was taken down in 1744, "that in the great room was put up with the quadrant." ' (Rigaud)

At this point it is worth noting that the 1774 inventory records 'Doctor Halleys Transit Clock removed from the great to the middle room' (RGO4/309/4). Although the inventory does not give the length of its going, it is clearly the week clock as all the month clocks are accounted for elsewhere.

Graham supplied all three of Halley's clocks prior to his invention of the mercury compensated pendulum in 1726. Halley appears to have made no attempt to have the simple pendulums of his clocks upgraded following Graham's invention of the mercury compensated pendulum in 1726. The pendulums of the two month clocks were subsequently however upgraded for Bradley, but rather than be fitted with mercury compensated ones, they were fitted with gridiron ones instead. The first was fitted just seven months after his appointment. Rigaud records that the pendulum for Graham 1 cost £15.13.0. and was fitted in September 1742. That for Graham 2 was fitted in August 1744 and cost £10.0.0. The pendulums of both clocks were upgraded again in the nineteenth century, Graham 2 being fitted with one of zinc and steel by Dent in 1872.

An examination of Bradley's observations at some future date is highly desirable as a check on what Rigaud has told us (or not told us) in his two publications. Very few of the observations he made at Greenwich prior to 1750 have been published, meaning that the original manuscript observations would need to be examined instead. After his death they became the property of his daughter. They passed from her to her uncle, the Revd Samuel Peach, and then to his son, John Peach, whose younger brother Samuel presented them to Oxford University in 1776. All except the transit observations for the year 1742 were returned to Greenwich by the University in 1861 and are now in the archives at Cambridge (RGO3). The 1742 transit observations are in the Bodleian Library at Oxford (MS Bradley 31).


The main uses to which Graham 2 was put
  • To time transits observed with the Mural Quadrant (until around 1750)
  • Occasional use as Transit Clock when Hardy was out of action (1849 & 1851)
  • Sent to Rodriguez Island for the 1874 Transit of Venus where it was used as the Transit Clock
  • Longitude determinations (1891-1909)
  • Loaned to Rosyth Dockyard for use with their timeball (1918-1926)
  • Chronometer workshop clock at Herstmoncuex (1960-1984?)


The upgrading of the pendulum

Bills for pendulums for Graham 1 & 2 (RGO4/305/B2)

9 Feb 1742 for £15.13.0. Said to have been fitted on 11 October 1742 (Rigaud)
3 Jan 1744 for £10.0.0. Said to have been fitted in Aug 1744 (Rigaud)

See also Rigaud


The recasing of Graham 2


Ruby palletts

Added by 1774


From month going to 8 day going

From the 1775 inventory (RGO4/309/7) - 'The clock called a week clock only goes two days'. In the next full inventory (1781) (RGO6/21/192), it is described as 'A two day clock with a simple pendulum'

Great Room: 'The month clock is removed to Mr Arnold for further correction


Graham 2 today

The following description is taken from the National Maritime Museum's website:

Dimensions: 1795mm x 450mm (hood) x 280mm (hood)

'The typical Graham/Shelton movement has angled shoulders to the plates which have been given a curled finish and are united by six latched knopped and stepped pillars. The lower centre of the backplate is punch marked 675. The painted brass cased weight is suspended by a silk cord which is hooked onto a projecting bracket (screwed to the frontplate) and runs through a brass pulley which has three curved crossings over a turned barrel pivoted between the plates and onto the main barrel (16 turns) which carries the great wheel and Harrison’s maintaining power with vertically pivoted stop work. All train wheels have four curved crossings. The dead beat escapement has a long shank pallet frame and jewelled pallets. The movement is secured to the heavy cast iron integral seatboard and suspension block via four screwed brackets. The Dent type, zinc-tube temperature compensated pendulum runs against a silvered pendulum scale reading 0-2 degrees.

The twelve-inch signed silvered dial has an outer minute circle enclosing a subsidiary seconds dial with observatory marks. The recessed hour subsidiary dial has a shaped blued steel hand which runs counter clockwise against an Arabic chapter. The dial is mounted to the movement by four dog-legged brackets and polished steel screws. To the right-hand side of the dial the original slot for bolt and shutter maintaining power can be seen. The minute hand is a tapering baluster shape whereas the counterpoised seconds hand is flat in section.

The 20th century blonde oak case has a moulded cornice to the sliding hood, the trunk has a glazed door and rests on a short base with moulded plinth.'


Historical Summary


11 May: First definitive mention of Graham 2 ('Horologium Murale') in the manuscript observations (RAS.Add.Ms/38/4/222)

16/26 May: described as 'a plain Month Clock' and the price paid recorded as £12.0.0.  (RGO6/21/ 22,24&26)
1744 '1744, August 18, "'The Great Clock by the quadrant was taken down and sent to Mr. GRAHAM to have a new pendulum" ... in the transit-book it is noted (1744, September 6), that " the quadrant clock has now the same sort of pendulum as the transit" [i.e. as Graham 1 which was fitted with a gridiron pendulum in September 1842]' (Rigaud, MMRAS, May 1836, see also Rigaud: Miscellaneous Works and Correspondence of the Rev. James Bradley). The bill for this work appears to have been £10.0.0 which is considerably less than the £15.13.0. that appears to have been paid for the pendulum that was fitted to Graham 1 (RGO6/21/43)
1772? At the meeting of Council on 2 April 1772, Maskelyne presented a list of improvements he wanted to be carried out. These included applying Ruby pallets to Graham 1 and Graham 2(RGO6/21/121). The First mention of the clock actually having Ruby Pallets comes in the 1774 inventory (RS/660/8&9), which was the first to be taken since 1765. There is a record of John Arnold to making a similar upgrade to Graham 3 in July 1771 and it seems likely that he also did the work on Graham 1 and Graham 2


184- Fitted by Dent with gravity escapement of Airy's design in order to test its effectiveness. Dent engraved the words "Gravity Escapement by Dent 184?' on the dial (since removed by punching the dial from the back to form a bulge over the area in the front which was then removed and the dial resilvered - the punch marks still being visible on the back of the dial). Gravity escapement removed by dent (date currently unknown) and the original dead-beat escapement refitted
1849 Oct: Used as Transit Clock while Hardy was being serviced. On 22 Oct: 'After the observation of the Sun, the Transit Clock was taken down to be cleaned; and another clock by Graham (G 2) was used instead of it till its return.' Hardy was remounted on 29 Oct & brought into use on 30 Oct.
1851 Used as Transit Clock on two occasions: Feb 28 - Mar 10 and Jul 2–25
1854 'Placed by the side of the galvanic motor clock [Shepherd] ... for facilitating the regulation of that clock'. The Shepherd clock at this time was located on the ground floor of the North Dome i.e. The eastern Summer House (Intro to Greenwich Obs). The motor clock was moved to the lobby at the foot of the Octagon Room staircase. (Intro to Greenwich Obs ). The time desk in the computing room appears to have been set up at this time (Report)
1857 Moved to Upper Record Room (Intro to Greenwich Obs)
1860 In 'Middle Room of the South East Dome' (Intro to Greenwich Obs)
1862 'generally preserved in the passage that was formally part of the Quadrant Room (Intro to Greenwich Obs). It appears to have remained there until 1871 (Intro to Greenwich Obs)

Fitted with new pendulum of zinc and steel similar to that of the Sidereal Standard ready for the forthcoming Transit of Venus Expeditions (1872 Visitor Minutes (ADM190/4/377) & Introduction to Greenwich Observations p.xxv)
1874 Sent to Transit of Venus Station C (Rodriguez Island) and used as Transit Clock (RGO59/58). Where it was kept once it had been returned is not clear
1891 Aug: Mounted in new Transit Pavilion in courtyard (Report)
Sent to Paris for use in Greenwich-Paris longitude determination
1894 1 November, Pendulum (old?) in wood case in Lower Chronometer Room under Great Equatorial(RGO39/10/53)
1898? In Thompson Dome Set to sidereal time (ROG39/10/132)
1902/3 Cleaned & repaired (Report)
1909 Dismounted and sent to Dent for repair (source?)
Feb 5: Sent on longitude expedition to Malta
1910 Cleaned by Dent on return from Malta (source?)
1915 Fitted with electro-magnetic corrector and contact springs to give minute signals (source?)
1918 Jun 17: Loaned to Rosyth for use with their timeball (RGO39/4/60), having been adapted for the purpose by Edwin Cottingham (MNRAS Obituary). Loan also mentioned in 1919 Report
1926 'Clock Graham 2 has been returned by the Admiralty in consequence of the closing of the Chart and Chronometer Depot at Rosyth Dockyard' (1926 Report). Placed in Lower Record Room at east end of Meridian Building (1926 Inventory RGO39/5/222)
1933 Still in Lower Record Room (1933 Inventory, RGO39/6/208)
1960 Mounted on wall of new chronometer Workshop at Herstmonceux. A cast iron mounting plate weighing 78kg being bolted to the wall. It is not clear when the mounting plate dates from
1984 Mounted in Herstmonceux Castle Library, standing alongside the Archives Office, this appears to have been after it had been 'overhauled and restored' by Robin Thatcher in the chronometer workshop. This included making and fitting the present oak plinth, this aspect of the restoration being carried out by staff member Horace L.
1990 Moved to Cambridge and mounted in office of Neil Parker
1998 ? Transferred to National Maritime Museum on closure of RGO


Further Reading

George Graham, ODNB

Baily, MNRAS 1834

Some Particulars respecting the principal Instruments at the Royal Observatory at Greenwich, in the time of Dr. Halley.  S. P. Rigaud, Esq., Savilian Professor of Astronomy at Oxford. MMRAS, May 1836

Timing the stars: Clocks and complexities of precision in eighteenth-century observatories

Image licensing

The portrait of George Graham is reproduced under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 Licence courtesy of The Board of Trustees of the Science Museum. Object Number: 1868-249