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Papers of the Board of Longitude : Correspondence regarding methods and instruments used to establish longitude and the use of chronometers at sea

Papers of the Board of Longitude

<p style='text-align: justify;'>This volume contains correspondence dating from 1783 to 1828. During this period, the Board of Longitude transformed and effectively closed. This is the final volume of correspondence regarding finding longitude at sea. Unlike the astronomical focus of volumes 35, 36 and 37, proposed instruments and improvements to instruments are the main subject of this volume. Astronomical methods only appear as a part of schemes focused on an instrument or instrumental technique.</p><p style='text-align: justify;'>The mandate of the Board had been opened up by Acts of Parliament from 1796. Alongside finding the longitude at sea, its remit expanded to include “other discoveries and improvements in navigation, and for making experiments relating thereto”. As a result, correspondence the Board received from that date onwards tends to be more varied.</p><p style='text-align: justify;'>The instruments and methods for longitude filed in this volume are from a range of both British and international correspondents and include printed pamphlets as well as correspondence sent straight to the Board. For example there are <a href='' onclick='store.loadPage();return false;'> several letters (RGO 14/38:8)</a>, from Antonio Maria Jaci, a professor of philosophy and mathematics in Messina regarding his <a href='/view/MS-RGO-00014-00037/1'> scheme for the longitude using “mercurial clepsydra” (RGO 14/37:15)</a> that were sent to the Board between 1784 and 1788 with several <a href='' onclick='store.loadPage();return false;'> printed versions of the scheme (RGO 14/38:31)</a> as well as detailed <a href='/view/MS-RGO-00014-00011/'> illustrations (RGO 14/11:25)</a>. Another printed pamphlet sent to the Board of Longitude came from the Reverend William Mitchel entitled “two easy methods for finding longitude at sea” and inscribed to the Right Honourable Lord Viscount Howe [<a target='_blank' class='externalLink' href=''><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>], First Lord of the Admiralty [<a target='_blank' class='externalLink' href=''><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] and Commissioner of the Board of Longitude in July 1787. Mitchel added an interesting <a href='' onclick='store.loadPage();return false;'> note (RGO 14/38:118)</a> to the front of his pamphlet that shows his awareness of other developments in navigational instruments: “It is said Mr Ramsden [<a target='_blank' class='externalLink' href=''><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] at London has invented a machine for dividing quadrants to such a nicety, that the mistake of a hundred parts of a line many be avoided; - and that it is of twenty two inches and an half radius which will be fit for the two within mentioned quadrants.”</p><p style='text-align: justify;'>Some of the proposals included in this volume are quite extensive pieces of work, for example, a Mr G Kirton of Whitby sent the Board of Longitude, via Captain Stephen Burn, a marbled and bound booklet with a <a href='' onclick='store.loadPage();return false;'> movable cardboard model (RGO 14/38:136)</a> of his instrument attached to the back in January of 1788 to explain his machine for finding the longitude. Due to the instrument focus of this collection, there are a number of paper and cardboard models as well as diagrams in the correspondence in addition to those sent from Mitchel and Kirton. Two other examples are Monsieur de Cruchent's method who sent a <a href='' onclick='store.loadPage();return false;'> short booklet (RGO 14/38:154)</a> with <a href='' onclick='store.loadPage();return false;'> diagrams (RGO 14/38:168)</a> in 1792. The same year the efforts of Joseph Bonasera to design another instrument were made know to the Board by way of another <a href='' onclick='store.loadPage();return false;'> short hand-written booklet (RGO 14/38:184)</a> with <a href='' onclick='store.loadPage();return false;'> coloured illustrations (RGO 14/38:197)</a>. A comparison of the diagrams within this volume serves to illustrate the point that communication by image was complicated and by no means standardised in this period. For example the “dial to find the longitude” of Mr W Parr, sent to the Commissioners in 1799, included a <a href='' onclick='store.loadPage();return false;'> drawing (RGO 14/38:226)</a> where the front of the instrument's face is drawn in two dimensions whilst the dial or compass is drawn over it in three dimensions.</p><p style='text-align: justify;'>Also evident in this volume is the importance that these proposals had to their authors. It is easy to presume that proposers would be invested in their fate but this volume reveals the extent to which this was the case. For example, there is an 1815<a href='' onclick='store.loadPage();return false;'> letter (RGO 14/38:332)</a> to Captain Thomas Hurd, then Secretary for the Board of Longitude from Mr R Boullanger, a watchmaker from Jersey, asking for compensation as he had been working on his instrument, or plans for it, for the past three months. There is also the <a href='' onclick='store.loadPage();return false;'> correspondence (RGO 14/38:390)</a> that Thomas Young (see <a target='_blank' class='externalLink' href=''>portrait</a> at the National Portrait Gallery) exchanges with a James Leslie near to the end of 1821 who first presented a scheme and then a month later asked if the package had arrived safely “as the attempt has cost me considerable pains and trouble, I am most anxious to know”. Some of Young's responses are also included in this volume. For example, Young wrote <a href='' onclick='store.loadPage();return false;'> a letter (RGO 14/38:415)</a> from the Admiralty office to Mr F Parkinson, on the 5th of June 1823 a year after Parkinson sent a plan for an instrument to the Board. He informed Parkinson him that, “the Nautical instrument described in it appeared to the Board to be of a nature which is not required in the present state of nautical astronomy and navigation.”</p><p style='text-align: justify;'>There continues from the last volume confusion, particularly in the correspondence from the provinces and the continent, about where and to whom schemes should be addressed. This is perhaps a result of the lack of physical space dedicated to the Board; schemes end up <a href='' onclick='store.loadPage();return false;'> addressed to the Admiralty (RGO 14/38:427)</a> as well as to Nevil Maskelyne [<a target='_blank' class='externalLink' href=''><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] the Astronomer Royal, who received several <a href='' onclick='store.loadPage();return false;'> letters (RGO 14/38:465)</a> from continental professors including Christian Gottlieb Kratzenstein in Copenhagen. </p><p style='text-align: justify;'>Sophie Waring<br />History and Philosophy of Science<br />University of Cambridge<br /></p>

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