<p>A small cache of seven letters, now at the National Maritime Museum, which the Astronomer Royal <a href='/search?keyword=Nevil%20Maskelyne'>Nevil Maskelyne</a> sent to <a href='/search?keyword=Andrew%20Mackay'>Andrew Mackay</a> between 1787 and 1805. It forms part of a collection at Greenwich of some of the Scottish astronomer's correspondence, several papers relating to his career, a manuscript copy of his book The Theory and Practice of finding the Longitude at Sea or on Land, and several copies of his printed works. The two men's association began when Mackay, the unpaid head of the observatory at <a href='/search?keyword=Marischal%20College'>Marischal College</a> in <a href='/search?keyword=Aberdeen'>Aberdeen</a>, asked Maskelyne to lay his 'new method of finding the Longitude and Latitude of a Ship at Sea' before the Board of Longitude - which he did on 8 December 1787 [<a href='/view/MS-RGO-00014-00006/1'>RGO 14/6:118</a>]. Some of Mackay's own correspondence can be found in volume RGO 14/33 [<a href='/view/MS-RGO-00014-00033/506'>RGO 14/33:518r</a>]. These letters are interesting because they partially reveal Maskelyne's side of the conversation, less often preserved in the Board archives, and shed light on the importance of his wide-ranging social and working networks to his and to the Board's activities. They also illuminate the ways in which the Board and the <a href='/search?keyword=Royal%20Society'>Royal Society</a> operated in general.</p> <p>The first letter in this collection, written on 26 May 1787, shows that Maskelyne found Mackay's partially or wholly self-taught skills impressive enough to try to bring him to <a href='/search?keyword=Greenwich'>Greenwich</a> as an assistant. He cited [<a href='' onclick='store.loadPage(2);return false;'>1:2</a>] Mackay's submitted longitude proposal, position at the observatory in Aberdeen, and reference from a <a href='/search?keyword=Mr%20Kelly'>Mr Kelly</a> as having convinced him. However, he also backtracked somewhat in this letter by saying [<a href='' onclick='store.loadPage(1);return false;'>1:1</a>] that he would not want to steal the Scotsman away from his patrons at the College and especially from a <a href='/search?keyword=Professor%20Copley'>Professor Copley</a> without their approval, and that a written trial [<a href='' onclick='store.loadPage(2);return false;'>1:2</a>] would further be necessary. The second letter [<a href='' onclick='store.loadPage(5);return false;'>2:1-2:4</a>] of 24 January 1788 discussed further details of the assistantship at Greenwich, and that Maskelyne was still waiting for some of Mackay's references to arrive.</p> <p>After the assistantship at Greenwich did not come to pass, the next letter [<a href='' onclick='store.loadPage(9);return false;'>3:1-3:4</a>] in this collection shows that on 2 August 1790 Maskelyne responded positively to Mackay having attempted to visit him in Greenwich, addressing his note to an address in the <a href='/search?keyword=Minories'>Minories</a> on the eastern maritime-oriented side of London. Clearly the two men stayed in touch, even if the intervening communications have not survived in this specific volume. There are then three letters from shortly before the Scotsman moved to London in 1802, and one last communication from 1805. The earlier letters deal with Maskelyne's attempts to name Mackay the new astronomer on the <a href='/search?keyword=Matthew%20Flinders'>Matthew Flinders</a> voyage to <a href='/search?keyword=Australia'>Australia</a> despite confusion and delays. The Astronomer Royal asked [<a href='' onclick='store.loadPage(13);return false;'>4:1</a>] for the return of one of his previous letters to check whether he could have really mentioned a salary of £1000 to his correspondent, when the Board could only offer £400 a year for such an undertaking.</p> <p>Interestingly, he also discusses in the same letter [<a href='' onclick='store.loadPage(14);return false;'>4:2</a>] how he could put his friend up for election to membership in the Royal Society - in the process describing the workings of such an election and of the Society. Maskelyne added [<a href='' onclick='store.loadPage(15);return false;'>4:3</a>] that he could speak to the President of the Royal Society (then <a href='/search?keyword=Joseph%20Banks'>Joseph Banks</a>) about it and was almost certain of obtaining his approbation, in which case Mackay's election was practically assured. However, he asked whether Mackay was sure that he wanted to go to the expense of it, when he already held other honours. He also discussed possible co-signers for the election certificate, being sure of the Spanish-born <a href='/search?keyword=Joseph%20de%20Mendoza%20y%20Rios'>Joseph de Mendoza y Rios</a> but alerting Mackay that whomever else he has suggested had not attended the Society's meetings since the famous blowup between Banks and a number of mathematician F.R.S. in the early 1780s. He also suggested the Scotsman's friend <a href='/search?keyword=Professor%20Abraham%20Robertson'>Professor Abraham Robertson</a> of <a href='/search?keyword=Oxford'>Oxford</a> and perhaps <a href='/search?keyword=Lynn'>Lynn</a>, <a href='/search?keyword=Herschel'>Herschel</a> or <a href='/search?keyword=Aubert'>Aubert</a>.</p> <p>Maskleyne said [<a href='' onclick='store.loadPage(17);return false;'>5:1-5:4</a>] in the second letter from 1802 that he had been forgetting to ask for an extra £100 per year for Mackay's participation in the Flinders expedition but thought they could get it, reported that the Board of Longitude had declined to give him a reward for his longitude book, and continued the discussion of his election to the Royal Society. In the third letter [<a href='' onclick='store.loadPage(21);return false;'>6:1</a>], the Astronomer Royal explained that he ultimately had to choose someone else to join the expedition, as he had not heard from Mackay in some time and knew that if his contemporaneous litigation to take over the professorship of natural philosophy at <a href='/search?keyword=King%27s%20College'>King's College</a> were successful, that he would be unable to go. However, Maskelyne assured [<a href='' onclick='store.loadPage(22);return false;'>6:2</a>] his counterpart that he would still support his election to the Royal Society and even that he would try to get his longitude book 'advertised on the sheets of the nautical almanac'. He also encouraged his interest in naval architecture and asked to be put down as a subscriber to his new treatises on astronomy and navigation. Each of the letters from this year also concluded with some astronomical information. In the letter [<a href='' onclick='store.loadPage(25);return false;'>7:1-7:2</a>] from 1805, addressed to Mackay's new London address in Trinity Square on Tower Hill, the Astronomer Royal congratulated Mackay on the upcoming third edition of his longitude book and expressed pleasure that he would again be the dedicatee on it - although he also reported that Professor Robertson at Oxford had reported a number of errata in the last edition. He discussed again taking up their efforts to get the Scotsman elected to the Royal Society.</p> <p>Mackay was partially or wholly self-taught in astronomy, navigation and mathematics and was respected for his abilities but perhaps not fully welcomed into the circle of the intellectual elite. As Maskelyne's letters reflect, he was made an honourary MA by Marischal College and was appointed the keeper of its observatory in 1781, later being awarded the LLD by Marischal in 1786 and by King's College nine years later. His notebook of routine observations made until 1789 survives, including estimates which he made of the longitude via observations of the Jovian moons. In 1793, the astronomer was elected a fellow of the Royal Society of Edinburgh. He also published by subscription the first edition of his longitude book, in which he was said to have received the thanks of both the French and British longitude boards for his efforts.</p> <p>Since Mackay was not paid for his observatory work, he sustained himself by publishing and by teaching diverse mathematics-oriented subjects, later also becoming the superintendent of the Aberdeen harbour. In 1802, he brought an unsuccessful action in the court of session against King's College after having been passed over for the Professorship of Natural Philosophy there. At this time, as can be seen in the letters in this collection, Maskelyne was also suggesting that he belatedly replace the astronomer on Matthew Flinders' expedition in Australia. He moved to London in 1804, as is reflected in the last letter in this collection, and in addition to teaching was an examiner in mathematics for Trinity House, Christ's Hospital and the East India Company.</p> <p>Alexi Baker<br />History and Philosophy of Science<br />University of Cambridge<br /> </p>
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