In order to find out of the longtitude for perfecting navigation and astronomy, we have resolved to build a small observatory within Our Park at Greenwich...
Charles II
This is the part of a letter that King Charles Ⅱ sent to John Flamsteed.
Everyone today knows that we can use the time difference between two points to calculate the distance. We see this idea very common today, but it was very important to sailors and navigators in the 17th century. They could measure the local time, by observing the sun. However, this was not enough for the safer voyage. They needed to know their longitude on the sea. Although accurate pendulum clocks existed in the 17th century, the motions of a ship and changes in humidity and temperature prevented a clock from keeping accurate time at sea.
King Charles II founded the Royal Observatory in 1675 to solve the problem of finding longitude at sea. John thought that if he could measure the position and the movement of the moon and stars, such imformaion would help sailors to know thier exact place on th sea. Therefore, he started to observe the fixed stars. He put the observational results together and published as his book 'ATLAS COELESTIS'
However, his great achievement was not good enough to solve the ploblem on the sea completely. The phrase 'finding the longitude' became a sort of catchphrase for the pursuits of fools and lunatics. Many people believed that the problem could not be solved before John Harrison suddenly burst upon the scientific scene.