National Maritime Museum Manuscripts : Observations taken by Fisher in winter quarters on Parry's expedition, 1821-1823

National Maritime Museum Manuscripts

<p>George Fisher was acting Chaplin and astronomer for Captain <a href='/search?keyword=William%20Parry'>William Parry</a>'s 1821 voyage to the Arctic on board <a href='/search?keyword=HMS%20Fury'> <i>HMS Fury</i> </a>. Parry and Fisher sailed in convoy with <a href='/search?keyword=George%20Francis%20Lyon'>George Francis Lyon</a> on board <a href='/search?keyword=HMS%20Hecla'> <i>HMS Hecla</i> </a> for the northernmost side of the Hudson Bay. Many of the Fisher volumes are notebooks and papers from this voyage, including this extensive collection of predominantly astronomical observations taken during Parry's search for the North-West Passage and during time spent on land in the Arctic. Some of the observations in this volume were taken for the express purpose of navigation and to provide data for local and Greenwich time in the lunar distance method of finding longitude. Other observations, calculations and recordings in this volume are for Fisher's own interest in navigational astronomy, for example [<a href='' onclick='store.loadPage(54);return false;'>52</a>] he periodically draws the positions of various stars and discusses their brightness and visibility. The decision of which stars were used for navigation was a critical one and the impact of a series of overcast days on the course of a ship could be dramatic. Records of the visibility of stars are therefore common on scientific voyages; learning which stars were the most easily observed in different parts of the globe was essential to the improvement of navigation. The choice of which stars were included in several sets of published tables, particularly the <i>Nautical Almanac</i> was a point of contention in the early nineteenth century. Arguments over the stars included for astronomical interest rather than purely navigational utility in the <i>Nautical Almanac</i> broke out between the Board of Longitude who published it and several men associated with the Astronomical Society of London, such as <a href='/search?keyword=Charles%20Babbage'>Charles Babbage</a> and <a href='/search?keyword=Sir%20James%20South'>Sir James South</a>.</p> <p>There is also work in this volume that investigates the effects of the environment on observations; for example Fisher sketched the ice on the horizon [<a href='' onclick='store.loadPage(74);return false;'>72</a>] in order to measure the dip of the sun over a three and a half hour period. The dip is a phenomenon caused by colder air below the line of sight refracting the sunlight and making the sun appear higher than it is in reality. Collecting observations to determine refraction when stars were observed near the horizon in icy environments was one of Fisher's ambitions during this voyage and was an important part of navigational astronomy in this period of increased interest in the pursuit of the North-West Passage. As well as seeing the kind of observations performed by Fisher this volume also offers insight into the practise of attempting to achieve high levels of accuracy and precision in measurement in a field-sight space. Fisher recorded both his own observations but also those taken by other officers, for example [<a href='' onclick='store.loadPage(87);return false;'>85</a>] we see observations taken with a circular transit and a repeating circle by Fisher and <a href='/search?keyword=Lieutenant%20Palmer'>Lieutenant Palmer</a> both recorded. As well as using multiple sets of eyes and reaction times to improve readings, error rates for the various instruments were also calculated to be included in the reduction of observations. There is an example [<a href='' onclick='store.loadPage(112);return false;'>110</a>] in this workbook of Fisher concluding that the repeating circle that he was using had no error in its plane as well as many examples [<a href='' onclick='store.loadPage(268);return false;'>266</a>] of errors and rates of chronometers being recorded. The lack of error in the repeating circle is rather exceptional in a culture dominated by the ambition of cancelling out all possible error in data including environmental, instrumental, mathematical and personal in the pursuit of ever increasing accuracy.</p> <p>Also present in this volume are pendulum rates [<a href='' onclick='store.loadPage(300);return false;'>298</a>] that Fisher periodically recorded to investigate gravitational variation in the Arctic which was another booming interest at the time of this voyage as men of science endeavoured to establish an accurate description of the figure of the earth.</p> <p>Many of the observations in this volume were taken at Winter Island where <i>HMS Fury</i> and <i>HMS Hecla</i> wintered in 1821 as well as at Igloolik, an Inuit hamlet on an island close to the Melville Peninsula, where the crews wintered in 1822. Fisher established portable observatories during both winters and collected a wide variety of results from experiments and observations, of which this volume is only one. The other notebooks, [<a href='/view/MS-FIS-00007/1'>FIS/7</a>] and [<a href='/view/MS-FIS-00008/1'>FIS/8</a>], also contain a vast quantity of observational work from this expedition. This volume also contains records [<a href='' onclick='store.loadPage(271);return false;'>269</a>] of work done at Ham in South West London in the November of 1823, just weeks after the voyage returned to England.</p> <p>Sophie Waring<br />History and Philosophy of Science<br />University of Cambridge<br /> </p>

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