Papers of the Board of Longitude : Observations on HMS Adventure

Bayly, William

Papers of the Board of Longitude

The astronomer William Bayly [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/154073.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] compiled this observations book on the voyage of HMS Adventure [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/86374.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] under the command of Tobias Furneaux from 1772 to 1774. It records the journey through the ice fields near Antarctica (see Hodges' <a target='_blank' class='externalLink' href='http://acms.sl.nsw.gov.au/album/ItemViewer.aspx?itemid=823696&suppress=N&imgindex=43'>drawing</a> in the State Library of New South Wales) and the islands of the South Seas. The voyage was part of the second expedition to the South Pacific led by then-Commander James Cook [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/14102.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>]. The main purpose of this tour was to search for an unknown continent, Terra Australis, in the Southern Ocean. A secondary aim was to test marine timekeepers made by Larcum Kendall and John Arnold (see portrait in the <a target='_blank' class='externalLink' href='http://www.britishmuseum.org/research/search_the_collection_database/search_object_details.aspx?objectid=55293&partid=1&searchText=john+arnold&fromADBC=ad&toADBC=ad&numpages=10&orig=%2fresearch%2fsearch_the_collection_database.aspx&rrentPage=2'>British Museum</a>). Bayly documented his astronomical, chronometric and natural philosophical work in this book.The expedition was a commission from the Royal Society. Cook sought to find Terra Australis by circumnavigating the globe eastward in a high southern latitude, and this expedition was the first to cross the Antarctic circle. Joseph Banks, famous from Cook's first voyage to the South Seas, originally intended to make this journey as well but backed out after disagreements over the arrangements to house him and a larger entourage than the ship could safely hold. Other staff including an artist and a natural historian joined the expedition to further examine and record the maritime and terrestrial sights instead.Cook's two ships, the Adventure and HMS Resolution [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/100618.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] left Plymouth on 13 July 1772. They were split up by heavy fog in the southern Indian Ocean from February to May 1773. Five months later, storms near New Zealand meant the ships lost contact permanently. Bayly and the Adventure returned alone around Cape Horn and docked at Spithead on 14 July 1774. The Resolution further explored the South Pacific and the Antarctic before returning home on 30 July 1775.While separated from Cook the first time, Furneaux and his crew explored much of Van Diemen's Land [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/540614.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] or Tasmania. They produced the earliest British chart of its geography. During the second separation, the Commmander took on board Cook's local interpreter and guide Mai [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/101256.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] (whom the British called Omai) of the Ulaietea or Raiatea people of Tahiti [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/15642.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>]. Mai was the second native inhabitant of the Pacific to travel to Britain and later returned home to Tahiti with Cook in 1776-1777.William Bayly, like his counterpart William Wales on the Resolution, was a long-time collaborator of the 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>] and of the Board of Longitude. He was one of the 'computers' of the figures published in the annual Nautical Almanac and served as Maskelyne's assistant at Greenwich from 1766 to 1771, with a break in 1769 to observe the Transit of Venus in Norway for the Royal Society. The Astronomer Royal recommended Bayly to the Board as the astronomer of one of Cook's two ships in 1772. His role was to make astronomical, navigational, ethnographic and natural philosophical observations both aboard ship and on the islands and continents that the vessel visited.On land, Bayly and Wales used portable tent-like observatories [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/149517.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>], which Bayly had designed, to house their instruments and make observations. Bayly oversaw the testing of two of the marine timekeepers made by John Arnold ('No. 1' and 'No. 2'), although one of these stopped working near the Cape of Good Hope [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/13258.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] on the journey out (Cook had more success with Larcum Kendall's timekeeper K1 [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/79143.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] on board the Resolution). The timekeepers were early attempts to move beyond the designs of John Harrison [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/136321.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>], which, while brilliant and effective one-offs, were too complex and expensive to reproduce for the entire Naval and mercantile fleets. Wales edited and published Bayly's observations in 1777 on behalf of the Board. From 1776 to 1780, Bayly served again as an expedition astronomer on Cook's third and final voyage to the (north) Pacific Ocean. He ended his working life as headmaster of the Royal Naval Academy in Portsmouth Dockyard from 1785 to 1807, with mixed results.Bayly used his observations book to record the results of his astronomical, chronometric and natural philosophical work aboard ship and in the portable tent observatory on land. He also noted the often difficult conditions under which they took place, and the resulting quality of his work. The astronomical work included making frequent observations of the altitudes, transits and relative distances of the Sun, Moon and stars. There were a number of reasons for this. Observations helped to determine the latitudes of maritime and terrestrial locations. They also aided setting and then deducing the rates of the longitude watches and astronomical regulator pendulum clock [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/243537.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>]. In addition, observations were essential for using the lunar-distance method to estimate longitude and for comparing it with the chronometric method. Amongst the instruments involved were a one-foot radius astronomical quadrant and a transit instrument with a Dollond achromatic object glass [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/43724.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] made by John Bird [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/127570.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>]. Bird was a widely respected instrument maker who worked with the Board of Longitude many times, for example producing the first sextant [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/43389.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>] in 1757 and receiving a reward of £500 from the Board in 1766 to spread his method of precision dividing instrument scales.The astronomer's natural philosophical efforts mainly consisted of making observations of conditions including the temperature, pressure and magnetic variations. He also recorded the tides in different locations. After the initial 79 pages of observations in this volume, there are <a href='' onclick='store.loadPage(165);return false;'> freshly numbered pages of observations of the two watches' going rates (RGO 14/57:2:1r)</a>. The first observation is from Nevil Maskelyne before the voyage. Daily observations are then recorded during the voyage with signatures from each of three keyholders. Bayly recorded the rates alongside the temperatures inside and outside the cabin and comments on any difficulties. He made periodic comparisons between the watches and either the voyage's astronomical regulator clock or regulators accessed during some landfalls. One of the most striking things apparent from these records is the difficulties which Bayly faced in transporting and using his instruments, and the marine chronometers to be tested, aboard ship and at landfall. This was due to factors including chance, human error, logistical challenges, and dramatic changes in movement, temperature and humidity. Great patience and ingenuity were required to overcome or to compensate for these obstacles. In the Antarctic waters, fantastical sights of icebergs, whales, dolphins, penguins and the Aurora Australis alternated with horrendous weather including violent storms and snow, waves breaking over the decks, and poor visibility. A number of times, Bayly mentions mishaps with the secure cases in which the longitude timekeepers were stored - with their three different locks and keyholders to ensure the fairness of the trials. Bayly <a href='' onclick='store.loadPage(1);return false;'> recorded (RGO 14/57:1:3)</a> that on 23 December 1772, he had to break open one of the chronometer boxes due to another keyholder having accidentally warped part of a lock, and then repaired and replaced the lock. There were <a href='' onclick='store.loadPage(1);return false;'> additional (RGO 14/57:1:5)</a> such breakages and repairs, including in May and June 1773. (Meanwhile, William Wales faced similar problems with the two trial timekeepers on the Resolution.)Bayly's observations book also provides details about the complexities of setting up the tent observatories, larger astronomical instruments and pendulum regulator clocks on land. In October and November 1772, the astronomer had to overcome a number of irritations when he set up his instruments and observatory at Table Bay at the Cape of Good Hope, where Mason & Dixon had made their observations of the Transit of Venus in 1761. He first filled the stand of his astronomical quadrant with water to weigh it down, but then resorted to sand after the water began leaking. On <a href='' onclick='store.loadPage(1);return false;'> 4 November (RGO 14/57:1:12)</a>, a strong wind 'brought great Quantities of sand from the Table mountains which greatly Affected the Instruments by Covering them with sand & shaking them & it was with difficulty we secured the tents from oversetting'. A few days later, a heat wave struck and his 'Clock C lifted qui[c]k of[f] the Iron it rested on I imagine by the Expansion of the Iron bar it was screwd to. I made it steady by applying wood wedges'. Later in April 1773, when the ship reached Charlotte Sound in New Zealand [<a target='_blank' class='externalLink' href='http://collections.rmg.co.uk/collections/objects/13385.html'><img title="Link to RMG" alt='RMG icon' class='nmm_icon' src='/images/general/nmm_small.png'/></a>], Bayly had to <a href='' onclick='store.loadPage(1);return false;'> go so far (RGO 14/57:1:27)</a> as to cut stone steps into a hillside in order to 'Observe Equal Altitudes with any propriety'.It was sometimes difficult for the astronomer to locate the cause of errors in his observations and calculations, given the number of finicky technologies and complex mathematics often involved. For example, Bayly recorded how <a href='' onclick='store.loadPage(1);return false;'> in (RGO 14/57:1:31)</a> he suddenly noted that his astronomical regulator appeared to be running at a slower rate that normal while in the tent observatory at Charlotte Sound in New Zealand. At first, he was not sure whether the disparity was due to an error in the timekeeper or in Bird's transit instrument, which he was using to observe equal altitudes and transits over the meridian. He eventually determined that it must be the clock in error but could not figure out why, since he had been the only one to enter the observatory and had not touched anything vital.Bayly's corresponding log book for this voyage is in volume <a href='/view/MS-RGO-00014-00056'> (RGO 14/56)</a>, while the log and observation books kept by William Wales onboard the HMS Resolution are in volumes <a href='/view/MS-RGO-00014-00058'> (RGO 14/58)</a> and <a href='/view/MS-RGO-00014-00059'> (RGO 14/59)</a>. Both astronomers also appear in a number of other volumes in RGO 14 -- in relevant minutes, accounts and correspondence -- as well as in the papers of individual actors such as Maskelyne. It is extremely interesting to see in the two men's log and observations books, their disparate approaches to their tasks (and perhaps also disparate abilities) and reactions to the different landscapes and especially native peoples whom they encountered.Alexi Baker History and Philosophy of Science University of Cambridge