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Insight into marine science
The objectives of Liverpool Observatory were:
At that time, the longitude at Liverpool was uncertain, as was local time. Ships chronometers, therefore, carried unknown errors with them to sea, so captains were not accurately able to determine their ships' positions, leading to many losses at sea.
Hartnup obtained time from the observation of the stars, ie, sidereal time, which was kept by a sidereal clock at the Observatory. There is one more sidereal day in a year than a solar day, so the sidereal clock gained one second every six minutes and six seconds. When the seconds of the sidereal clock and the solar clock coincided, calculations were made to maintain the accuracy of the solar clock. To convert Liverpool time to Greenwich time, the difference in longitude was calculated.
To find the longitude at sea, it was necessary firstly to determine local time, and secondly to find Greenwich time at the same moment. The difference between the two is the longitude. Greenwich time at sea was often determined by the observation of lunar distances, which was often not possible. A much easier way was by chronometer. It was very important therefore that chronometers should be accurate so that the exact position of ships could be calculated.
Hartnup set up a series of chambers at the Observatory, heated to various specific temperatures, and chronometers were brought by sea captains to the Observatory to be tested through these temperatures. Hartnup proved that chronometers inaccuracies were usually due to the changes in temperature that they were subjected to on their voyages.
Having determined Greenwich time, a time ball was fitted to the side of the Observatory, being dropped at exactly one o'clock each day. The citizens of Liverpool were then able to check their timepieces.
Soon after the Observatory was built, the Astronomer Royal wanted to know the difference in longitude between Valentia, in Ireland, and Greenwich. To make the task easier, two intermediate stations were chosen, one of which was Liverpool, thus confirming Liverpool's longitude.
For years the US Coast Survey had been trying to determine the difference in longitude between Liverpool Observatory and Cambridge Observatory, USA. This had previously been impossible due to the unreliability of chronometers on ships that crossed the Atlantic. "The steam ships chronometers used for navigating the vessels were not rated at this Observatory, or the requisite information could have been supplied".
In 1849, Hartnup and Professor Bond, Director of Cambridge Observatory, USA, decided that they would undertake a massive exercise to solve this problem. Over the next few years, several hundred fully tested chronometers were loaded onto naval vessels and crossed and recrossed the Atlantic. Hartnup also devised a new balance for chronometers, 5 of which were made and fitted by a Liverpool manufacturer, Mr Shepherd, and employed on the expedition. These were tested through a range of 120 degrees Fahrenheit, with favourable results. On the successful conclusion of this experiment, Professor Bond presented Liverpool Observatory with a fine sidereal clock.
With so much experience of testing chronometers and the successful outcome of the Atlantic expedition, Hartnup was now in a position to advise and assist the Astronomer Royal to set up similar testing chambers to the ones at Liverpool Observatory, so that he also could test and rate chronometers.
Hartnup set up a fully operational meteorological station, recording temperatures, rainfall, barometric pressure and cloud cover. In 1853 Alfred King of Liverpool invented the barograph, with guidance from Hartnup.
Having resolved the longitude problem, provided accurate time to Liverpool and set up a successful chronometer testing system, Hartnup then recommended to the Observatory Committee of the Town Council that a more scientific character should be given to the Observatory. The 'magnificent equatoreal telescope' at the Observatory enabled him to make observations that gave the Observatory a much higher standing, astronomically speaking, than was originally anticipated. His observations were considered by astronomers to have increased the accuracy of navigation, extended the practical astronomy of Great Britain and added to the knowledge of the universe.
In 1855 the large equatorial telescope was used when taking photographs of the moon. These were exhibited at the Royal Astronomical Society and a meeting of the British Association for the Advancement of Science at St George's Hall, Liverpool as well as several photographic exhibitions. The photographs were projected to show the moon with a diameter of 50 feet, to much acclaim.
Under the direction of the Board of Trade, the Observatory then began supplying ships with Azimuth compasses. These were used to observe the sun, in order to determine the error of the ships' steering compasses. These were supplied free, on condition that records of observations be returned to the Meteorological Department of the Board of Trade. The object of this research was to improve the safety of vessels and assist improvements in variation charts. Soon afterwards, barometers and thermometers were supplied to ships under a similar arrangement.
As the Observatory became more renowned for its pioneering work, New York showed interest in also setting up a Nautical Observatory similar to that at Liverpool and Hartnup was able to render his assistance.
In order to provide accurate time to more people, in 1856 the clock at Exchange Building was electrically connected to the Observatory . The following year the Town Hall clock was also linked.
In 1866, with the re-development of Waterloo Dock, the observatory was relocated to Bidston Hill. This was a larger building, with better facilities. Chronometers continued to be tested and rated for shipping. Meteorological and astronomical observations continued to be made. In order to continue to provide time to Liverpool, a time gun was used, which was placed on the dockside at Birkenhead and electrically controlled, from the Observatory.
In 1885 John Hartnup retired, being succeeded by his son.