The Importance Of Longitude

Longitude

Navigation was one of the greatest scientific challenges of the Age of Exploration. To be lost at sea meant wandering an empty ocean which was a big peril. Until just over 200 years ago there was no accurate way to find your position at sea. In October 1707 a fleet of British warships were returning home from a battle with the French. Even though they could not be exactly sure of their positions, they believed they were far from the Scilly Islands, but they were actually 1 day 's sail away. In a matter of minutes one of the Navy 's fleets had drowned. There were many days of sadness and confusion due to the fact that England was King of the Seas. The English Parliament offered a prize of £20 000 to anyone who found the answer to finding longitude at sea within half a degree or 4 minutes. John Harrison, was a middle class carpenter who devoted his life to finding the answer to Longitude at sea and to getting the prize. He made 4 accurate time keepers during his lifetime H1, H2, H3, and H4, but only on his 4 time piece did he receive any

The method John Harrison used was time. We know that the Earth revolves around its axis once every 24 hours which means the sun crosses all of the 360 meridians in 24 hours. In 1 hour the Sun moves 15° and in 4 minutes, it moves 1°. So you need to measure the time aboard your ship and compare it to the time in Greenwich or anywhere on the Prime Meridian. The time difference between these places determines how far apart the places are. You would have to multiply the difference of hours by 15 to get you longitude. A seafarer could calculate time at their location by observing the position of the sun at noon through a sextant. However, it was still impossible to find accurate time at the Meridian line without a precise timekeeper like a clock, but at that time most clocks had pendulums and it was impossible for a pendulum clock keep accurate time because the ships swaying movement would affect the movement of the