<p style='text-align: justify;'>A group of letters composed by the Admiralty's Resident Commissioner at Portsmouth Dockyards, Richard Hughes, to the Admiralty, between October 17 1761 and November 8 1761. These letters outline the problems encountered by members of the Admiralty based at Portsmouth through their interaction with the clockmaker John Harrison. This period at Portsmouth represents the initial stages of the first trial of Harrison's H4, which took place as part of the Board of Longitude's attempt to establish whether or not Harrison's machine could meet the criteria stated in the Act of finding Longitude to within 30 miles of Longitude. This first trial, which involved H4 being carried by Harrison on HMS Deptford along the well-known route to the sugar colonies in Jamaica and back, was so riddled with problems over ascertaining the rate at which the timekeeper had gained or lost time, that a second trial of H4 was ordered by the Board of Longitude, which this time took place aboard HMS Tartar in 1764 to Barbados, in which H4 was carried by John Harrison's son, William.</p><p style='text-align: justify;'>The letters in this document demonstrate that rating timekeepers in the second half of the eighteenth century could be incredibly problematic. In this case, at least two main reasons are demonstrated. The first, as can be seen in Richard Hughes' letter to John Clevland (the Secretary to the Admiralty) on October 31st, was the very material problem of checking the rate of the timekeeper by astronomical observations. Hughes tells Clevland that 'We have been hitherto very unfortunate in our Observations, of the Suns equal Altitudes, by Cloudy and wet weather.' This work was absolutely crucial, both for the day to day understanding of timekeepers by those hoping to use them on voyages, and for the larger project, co-ordinated by the Board of Longitude, the Admiralty, and certain London-based clock and watchmakers, of assembling a vast record of the going of numerous timekeepers sent on Admiralty and EIC backed voyages in the late eighteenth century. That the task of making observations to find local time could be so easily hampered by inclement weather, made the prospect of sending timekeepers on trials at sea incredibly problematic. In the Board of Longitude records numerous incidents can be found of poor weather halting the ability of astronomers or officers to establish the going of their timekeepers, thus rendering them temporarily useless.</p><p style='text-align: justify;'>The second problem, as demonstrated in some of Hughes' letters, was dealing with the relationship between clock and watchmakers and those individuals and institutions tasked with making the astronomical observations to find the 'correct' time at Portsmouth to which H4 had to correspond for the purpose of a trusted trial. In his letter written on November 2nd 1761, however, Hughes wrote that after a series of observations had shown that the time on Harrison's watch did not match the time given by observation at Portsmouth, he found 'Mr Harrison by no means inclinable to alter his watches, to the true time of this place'. Harrison did not trust that the observations had been performed correctly, and was reluctant to admit, at this early stage, that his watch was liable to err as much as Hughes and John Robertson (the master of the Royal Naval Academy at Portsmouth) claimed it had. As already stated, it was partly down to this problem of who to trust in terms of the recorded rate of the going of H4, that this trial was ordered to be repeated. The problems over who or what to trust to give the 'correct' time against which another technology or technique could be tested, are constantly present throughout the existence of the Board of Longitude, and survived well after Harrison was granted a reward by the Board. Documents like this exemplify the way in which trials of technology by necessity required the testing and management of social and institutional boundaries.</p><p style='text-align: justify;'>Eóin Phillips<br />History and Philosophy of Science<br />University of Cambridge<br /></p>
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