Papers of the Board of Longitude : Correspondence on magnetic variation

Papers of the Board of Longitude

RGO 14/42 is, like the other volumes of correspondence, filled with requests for schemes and plans for inventions to be presented to the Commissioners of Longitude for judgement. The variation of schemes sent to the Board increased after a 1796 Act of Parliament expanded the mandate of the Board of longitude to sponsor schemes and inventions that were judged to be “useful discoveries and improvements in navigation" generally rather than specifically for finding longitude at sea. As a result the start of the nineteenth century saw an expansion of the subjects on which the Board received correspondence.A curiosity concerning magnetism and its relationship with electricity re-emerged in the conscious of the metropolitan scientific scene in the late eighteenth century with the development of the battery, which could manufacture electricity when required, thus making experimental work significantly easier. The work of Hans Christian Oersted and Michael Faraday [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/127729.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] followed at the start of the 1820s. The spike in interest in electricity and magnetism during this period lead to an increase in correspondence on this subject being sent to the Board of Longitude, enough to result in Astronomer Royal George Airy [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/136564.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] having to dedicate two volumes of papers from the Board of Longitude to correspondence on magnetic variation when he sorted the papers.The increase in correspondence of this nature probably contributed to Michael Faraday being chosen to become one of three committee members when the Board of Longitude was transformed into a closed consultative committee for the Admiralty in 1828. It would be fair to suggest that those setting up the committee anticipated that a significant amount of future correspondence would be regarding magnetic instruments and therefore Faraday's knowledge of the subject would be essential to the functioning of the new committee.Of particular interest in this volume is the account of experiments undertaken by Mr W Graham of Newcastle-Upon-Tyne investigating the “Cause of the Annual Variation of Magnetic Variation as it included a <a href='' onclick='store.loadPage(1);return false;'> handwritten booklet (RGO 14/42:34)</a> explaining his work with diagrams which was passed onto Astronomer Royal Nevil Maskelyne [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/379043.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] for further consideration in 1788. Also impressive in this volume is the sheer scale of correspondence from John Churchman, who worked as the land surveyor for the Districts of Delaware and Chester in Philadelphia. The <a href='' onclick='store.loadPage(1);return false;'> first letter (RGO 14/42:57)</a> of which was sent in 1787 and the <a href='' onclick='store.loadPage(1);return false;'> last (RGO 14/42:138)</a> in 1804. The collection contains sheets of data taken when measuring the North Magnetic Pole as it is found describing a circle from west to east, similar tables are also included in the <a href='' onclick='store.loadPage(1);return false;'> appendix (RGO 14/42:111)</a> of a forty-six page booklet that predicts the position of the north and southern magnetic point until the year 3877. Also within Churchman's correspondence is a <a href='' onclick='store.loadPage(253);return false;'> large folded magnetic atlas (RGO 14/42:116)</a>. There are also <a href='' onclick='store.loadPage(1);return false;'> pamphlets (RGO 14/42:133)</a> that criticise the prior work of Leonhard Euler (see <a target='_blank' class='externalLink' href='http://www.sil.si.edu/digitalcollections/hst/scientific-identity/CF/by_name_display_results.cfm?scientist=Euler,%20Leonhard'>portrait</a> at Smithsonian Library) a mathematician at the Berlin Academy and tutor to the niece of Fredrick the Great of Prussia. Churchman felt compelled to create a <a href='' onclick='store.loadPage(257);return false;'> list (RGO 14/42:118v)</a> of socially and academically significant people who had subscribed to his work that included Sir Joseph Banks [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/107455.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>], several members of the Barclay banking family, William Herschel [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/14237.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] and Nevil Maskelyne. This desire to show that his scheme was socially sponsored as well as pertinent to improvements in scientific theory and navigation is telling of what it took to have work recognised in this period; the recognition of potential based only on merit is still only a Radical ambition at this point.The last collection filed in this volume is from Captain John Ross [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/14456.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] from his 1818 voyage to the Arctic [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/533989.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>], a journey in which he was accompanied by Edward Sabine [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/107845.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] and William Edward Parry [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/108658.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] aboard the HMS Isabella and HMS Alexander (see portraits of HMS Isabella and HMS Alexander [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/102854.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] and both vessels at Prince Regents Bay [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/102855.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>]. This particular piece of <a href='' onclick='store.loadPage(1);return false;'> work (RGO 14/42:319)</a> that Ross has sent back to the Board is an account of the Variation of the Compass and Deviation of the magnetic needle, with Experiments and Facts established. The work is seven pages long, including a <a href='' onclick='store.loadPage(1);return false;'> data table (RGO 14/42:326)</a> and several stunning <a href='' onclick='store.loadPage(1);return false;'> illustrations (RGO 14/42:322)</a> as well as accounts of HMS Isabella's and HMS Alexander's deviation from set courses. This work was sent by Ross directly to the Admiralty and John Barrow [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/107724.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] sent a copy over to <a target='_blank' class='externalLink' href='http://www.npg.org.uk/collections/search/portrait/mw81992/Thomas-Young?LinkID=mp04986&role=sit&rNo=5'>Thomas Young</a> for the Board of Longitude.Sophie Waring History and Philosophy of Science University of Cambridge