#Keep it coming 1760s portable
#Keep it coming 1760s trial
#Keep it coming 1760s series

It worked well, so Harrison incorporated it into his fourth longitude timekeeper, H4. Harrison sea clock – H4Īround 1751–52 Harrison commissioned John Jefferys to make a watch with a radically new type of balance. Harrison was forced to make many changes and adjustments. While it was running and being tested within five years, it became clear that the clock would struggle to keep time to the accuracy desired. Harrison began work on his third attempt, H3, in 1740, and would continue to work on it for 19 years. However, H2 never went to trial, because Harrison had discovered a fundamental flaw.

#Keep it coming 1760s trial

Harrison moved to London soon after the Lisbon trial and within the two years promised he finished his second sea-clock. £250 was to be paid up front, to allow Harrison to build an improved clock. The Commissioners agreed a payment of £500. The Admiralty requested a formal meeting of the Commissioners of Longitude.Īccordingly, eight of them assembled on 30 June 1737 to discuss Harrison’s ‘curious instrument’. The results of the trialīack in London, the results of the Lisbon trial suggested that Harrison might qualify for a reward under the Longitude Act. It also meant that the H1 was working correctly. This meant they were 60 miles off course and in danger. It was transferred to the Orford for the return, and this journey led to much better results.Īs they neared England, Harrison announced that a headland the officers had thought was the Start was in fact the Lizard. By the time they reached Lisbon however, the machine was going much more reliably. The voyage out to Lisbon began poorly for both Harrison and his clock. The aim was to put H1 to the test in a live setting. In May 1736, Harrison and H1 were taken aboard HM ship Centurion, which was about to set sail for Lisbon. John Harrison's H1 Marine Timekeeper A trial at sea It seemed that it would be successful in measuring longitude.

#Keep it coming 1760s portable

Because of the clock's two interconnected swinging balances, it is unaffected by the motion of a ship - it is essentially a portable version of Harrison's precision wooden clocks.

It was installed in Graham’s workshop, to be shown to London’s scientific community.Īt last, it seemed, here was a timekeeper that might be used to determine longitude at sea. He was most likely helped by his brother, James.Īfter testing the clock on the River Humber, Harrison proudly brought it to London in 1735. John Harrison's first attempt – H1įor the next few years Harrison worked in Barrow upon Humber on a marine timekeeper, now known as H1. Instead, he sent him to clockmaker George Graham. He was received warmly at Greenwich, but Halley felt unable to judge his work.

Harrison began his time working in London with Edmond Halley, second Astronomer Royal and a Commissioner of Longitude. The Longitude Act was an act of parliament that offered money in return for the solution to the problem of finding a ship's precise longitude at sea. John Harrison arrived in London, looking for both support and the rewards promised by the 1714 Longitude Act. This would make it far more accurate than even the best watches of the time. In order to solve the problem of Longitude, Harrison aimed to devise a portable clock which kept time to within three seconds a day. These clocks achieved an accuracy of one second in a month, far better than any clocks of the time.

#Keep it coming 1760s series

During the mid-1720s he designed a series of remarkable precision longcase clocks.

John Harrison was a carpenter by trade who was self-taught in clock making.