National Maritime Museum Manuscripts : Observations and working at Dane's Island, Spitzbergen, including notes on magnetic dip and the specific gravity of ice

National Maritime Museum Manuscripts

<p> <a href='/search?keyword=Danes%20Island%20%28Dansk%C3%B8ya%29'>Danes Island (Danskøya)</a> lies just off the northwest coast of <a href='/search?keyword=Spitzbergen'>Spitzbergen</a> and was one of the places that the 1818 Arctic expedition commanded by <a href='/search?keyword=David%20Buchan'>David Buchan</a> on <a href='/search?keyword=HMS%20Dorothea'> <i>HMS Dorothea</i> </a>, accompanied by <a href='/search?keyword=John%20Franklin'>John Franklin</a> aboard <a href='/search?keyword=HMS%20Trent'> <i>HMS Trent</i> </a> went to. <a href='/search?keyword=George%20Fisher'>George Fisher</a>, who was recommended by the Royal Society to act as one of the astronomers serving on this voyage, took a large collection of readings throughout the expedition. This particular volume relates to his work on magnetic dipping needles, one of which was made by <a href='/search?keyword=Edward%20Troughton'>Edward Troughton</a>, as well as one page of Fisher’s measurements for the specific gravity and temperature of sea water in different latitudes. The voyage lasted only the summer of 1818 as the reports of retreating ice from whalers from the previous summer lead the two ships into pack ice where they were pulled north for sixty miles by rope before retreating to open water and finally returning to England in September, having only set out in April.</p> <p>Of particular interest in this volume are the accounts of the variations in several instruments; much work records the rates of clocks and chronometers [<a href='' onclick='store.loadPage(3);return false;'>1</a>], along with Fisher’s accounts of their adjustment and calibration. Fisher included not only the comparison of rates for a regulator clock and chronometers but several temperature measurements [<a href='' onclick='store.loadPage(4);return false;'>2</a>] in between the ratings with the thermometer held in different regions around the clock and its pendulum. There is intermittent text in the notebook; a short discussion [<a href='' onclick='store.loadPage(6);return false;'>4</a>] of the calibration of the nine chronometers that Fisher had access too with transit observations is interesting and contains a list of the makers and owners of the chronometers.</p> <p>Although starting with rates of chronometer, the volume is dominated by records of observations [<a href='' onclick='store.loadPage(9);return false;'>7</a>] of the variation in a dipping needle by Edward Troughton, in the early days of May 1818 and then a comparison [<a href='' onclick='store.loadPage(10);return false;'>8</a>] from the same position on Dane’s Island with a Thomas Jones dipping needle. Following this is an account of further observations [<a href='' onclick='store.loadPage(11);return false;'>9</a>] with the Jones dipping needle at the start of June in <a href='/search?keyword=%E2%80%98Magdalena%20Bay%E2%80%99%20%28Magdalenefjorden%29'>‘Magdalena Bay’ (Magdalenefjorden)</a> with the needle this time being place both in the magnetic meridian and then a series of eight angles to it. In addition to these readings some of the text in the notebook [<a href='' onclick='store.loadPage(14);return false;'>12</a>] tells us an <i>‘electrical chain conductor was attached to the masthead but no electricity was indicated the whole of the day by either of the electrometers’</i> and measurement [<a href='' onclick='store.loadPage(23);return false;'>21-22</a>] of the effect of the ship on the needle. Fisher was particularly interested in the relationship of electricity and magnetism in the Arctic as is also demonstrated in his workbook on the Aurora Borealis [<a href='/view/MS-FIS-00019-00001/1'>FIS/19/1</a>] in which he agreed with the dominant contemporary theory that it was fundamentally an electrical phenomena.</p> <p>Sophie Waring<br />History and Philosophy of Science<br />University of Cambridge<br /> </p>

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