ia_2009_b_paige

Summary of Evidence
(taken from http://www.amazon.co.uk/gp/product/0393315193/ref=sib_rdr_dp)

Previous to the 1700’s, sailors around the world found trouble in locating their position at sea. The technology that was at their disposal was lacking in accuracy and practicality. To judge their position, mariners often referred to landmarks //(given they were in sight)// and/or observed their bearing, with the use of a compass, and calculated their latitude by measuring the distance between the horizon and the sun.[|[2]]

However, these methods proved to be unsuccessful. The main issue that mariners faced was finding their longitude //(the distance east or west of the prime meridian of a point on the earth’s surface.//[2] //)// The simplest way to comprehend longitude is to visualise the geometric grid which we use to calculate an exact position on the earth, longitude are the lines that go up and down, joining the North to the South pole. With their longitude, sailors would be able to know their exact position at sea without apprehension. However, finding longitude was all too difficult for mariners, their most accurate method was astronomical observation. The most uncomplicated and practical method to have done this would have been to acquire the local time at the ship’s position and the time at a set place ( //Greenwich//). The only hindrance with this method was that clocks ran on pendulum mechanisms, consequently, with the rocking motion of the ship, the mechanism was swung out of place and the clock would lose minutes each day resulting in completely inaccurate readings. 'Isaac Newton's description of the timekeeping approach: "One [method] is by a Watch to keep time excatly. But, by reason of the motion of the ship, the variation of the heat and cold, wet and dry, and the difference of gravity in different latitudes, such a watch hath not yet been made." And not likely to be, either, he implied.' [3]

It took until 1714 for the British government to address this problem. Following the death of nearly 2,000 British sailors (//22nd October 1707),// having run aground from misjudging their latitude, the government issued a cash prize of £20,000 to anyone who could solve the problem of finding their longitude at sea through any system that was, “practicable and useful" [4] .

The rules for solving the longitude problem were as follows: The inventor had to design an idea that could find longitude within half a degree (//about thirty miles//) on a journey from England to the West Indies.

Hundreds of applications were received with plenty of them being good ideas, many were given grants to continue and develop their work into more useful solutions. Among these applicants was a Mr John Harrison; A carpenter and clockmaker by trade, John Harrison lived in Lincolnshire. Having previously created clocks that kept time impeccably (much to the non-belief of the board of longitude), he felt that he had a decent chance in winning the grand prize; and so he set about developing a time piece that could keep time onboard a ship.

What was demanded of a timepiece to be accurate at sea was a clock that could keep time to a minimum of two or three seconds a day. Harrison’s first attempt was called ‘H1’, and was tested on a crossing to Portugal; even though the voyage wasn’t to the West Indies (//which the government was convinced was a perfect testing method////),// the trip was successful and the clock ran exceedingly well. John Harrison’s design was proof that time could be kept at sea.

Consequently John Harrison continued to construct a further five marine timekeepers, each strategically named from the model ‘H1’ to the model ‘H5’. "Harrison's fourth timekeeper 'H4' proved to be the first of all precision watches" [5] He had broken through, and invented one of the greatest and "monumentally important in the history of science." [6]

[1] [| http://itotd.com/articles/532/the-longitude-problem/] (//Date Accessed - June 20th '08//) [2] http://www.maps-gps-info.com/maps-gps-glossary-kl.html (//Date Accessed - June 20th '08//) [3] Sobel, D., (1998). //Longitude: the True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time//. New York: Fourth Estate. ISBN 1-85702-571-7 (//Pg. 52//) [4] http://www.portcities.org.uk/london/server/show/ConNarrative.132/chapterId/2702/Greenwich-and-the-story-of-time.html (//Date Accessed - June 20th '08//) [5] Betts, J., (2006). //Time Restored//. Oxford: Oxford University Press and the National Maritime Museum. ISBN 0198568029 (//Pg. 3//) [6] Ibid (//Pg. 3//)