<p style='text-align: justify;'>A diary, eighty-seven pages in length, started by Astronomer Royal Nevil Maskelyne on 23rd November 1791, which forms his central record for co-ordinating the production and publication of the Nautical Almanac in this period. This volume contains abundant information regarding the co-ordination of various computers and comparers for the Nautical Almanac. By the 1790s there was an extensive network of calculators that worked from homes all over the country which Nevil Maskelyne co-ordinated from the Royal Observatory Greenwich. Within the volume there are periodic summary tables (at <a href='' onclick='store.loadPage(9);return false;'>RGO 4/324:4r-5v</a>, <a href='' onclick='store.loadPage(51);return false;'>RGO 4/324:25r-25v</a> and <a href='' onclick='store.loadPage(62);return false;'>RGO 4/324:30v</a>) of the work done by which computer for a year at a time; years in this volume include 1811 through to 1816. They list who did the work for each month and then who the comparer was. Getting the right combination of people so that all the work was checked thoroughly was complicated and here we see how Maskelyne organised it. Creating and filling these tables ensured that Maskelyne could co-ordinate the computers to certify that no two would be paired twice over the year and that both copies were sent to the comparer to check for discrepancies and to redo the calculation when required. The distances that the papers had to travel worked as an advantage for Maskelyne as there was minimal chance of copying or premature comparison if the computers were hundreds of miles apart.</p><p style='text-align: justify;'>There are also detailed accounts of his interactions with the majority of computers from this period, for example <a href='' onclick='store.loadPage(14);return false;'> dealings (RGO 4/324:6v-8r)</a> with Ms Mary Edwards are particularly well documented. There are notes for each calculator on their errors, methodology and general ability, their punctuality in returning work as well as the practical issues of pay and books lent out to individuals. Those working as Almanac computers could not often afford the books required for their calculations so Maskelyne would lend them the appropriate tables, charts and books. To illustrate this there is the case of Mr Philip Turner who died on 1st March 1800 and Mr Ward, his landlord, sent Maskelyne all the <a href='' onclick='store.loadPage(37);return false;'> tables and books (RGO 4/324:18r)</a> that Turner had in his possession when he died: Dr M's folio tables, Mayer's tables, Charles Mason's lunar tables of 1780, Garden's logarithms printed at Avignon, Lalande's tables, and the Nautical Almanac of 1799. But Taylor's logarithms were not returned and Maskelyne suspected they had been pawned or disposed of. Finally one of the last items in the notebook is a list of <a href='' onclick='store.loadPage(73);return false;'> instructions (RGO 4/324:36r-36v)</a> for the "Monthly Business of Two Computers" from the calculations themselves to how to write up the tables. This is followed by <a href='' onclick='store.loadPage(75);return false;'> instructions (RGO 4/324:37r-38r)</a> for the "Monthly Business of a Comparer", giving insight into Maskelyne's perferred operations.</p><p style='text-align: justify;'>Also contained within this diary are the Board's instructions for the Nautical Almanac, perhaps this was the book that Maskelyne took with him to the meetings. For example we see where Maskelyne has kept a record of the Board's financial report in addition to <a href='' onclick='store.loadPage(42);return false;'> notes on instructions (RGO 4/324:20v)</a> for the Almanac discussed at the Board of Longitude meetings held on 16th August 1799 and 31st May 1803.</p><p style='text-align: justify;'>The notebook has not been filled in chronologically page after page; it has several short page entries that have notes on the same subject but which span several years. For example, the <a href='' onclick='store.loadPage();return false;'> second page (RGO 4/324:2)</a> has dates running from 1790 to 1794, and is concerned with stationary orders and blank tables being sent out to different calculators. There are also <a href='' onclick='store.loadPage();return false;'> notes (RGO 4/324:33)</a> on the practicalities of getting the Nautical Almanac published; and <a href='' onclick='store.loadPage(35);return false;'> notes (RGO 4/324:17r)</a>on organising the purchasing and delivering of paper on time for printing with Mr Thomas Bensley, who was appointed printer to the Board in February 1799. This account of the publishing process gives insight into the practicalities of creating the Nautical Almanac and helps us to appreciate it not just as a set of tables but as a material object, an instrument, that is exported and carried around the globe as an aid to navigation.</p><p style='text-align: justify;'>Sophie Waring<br />History and Philosophy of Science<br />University of Cambridge<br /></p>
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