The biggest technological break-through in Navigation was to arrival in the West of the magnetic compass needle, thought to have been invented by the Chinese.
However, that in
conjuction with the direction of the sun's passage and observation of the stars still left a huge gap in navigational understanding.
The main problem was sorting out Longditude and Latitude and here the advance in accurate clock-making evenutally solved that problem. By setting an agreed universal time (at Greemwich) and starting off on a sailing journey with clocks set at 'Greenwich Time' navigators could work out their position at sea.
Problem of longitude
Determining longitude on land was fairly easy compared to the task at sea. A stable surface to work from, a comfortable location to live in while performing the work and the ability to repeat determinations over time made for great accuracy. Whatever could be discovered from solving the problem at sea would only improve the determination of longitude on land.
Determining latitude was relatively easy in that it could be found from the altitude of the sun at noon with the aid of a table giving the sun's declination for the day.[2] For longitude, early ocean navigators had to rely on dead reckoning. This was inaccurate on long voyages out of sight of land and these voyages sometimes ended in tragedy as a result.
In order to avoid problems with not knowing one's position accurately, navigators have, where possible, relied on taking advantage of their knowledge of latitude. They would sail to the latitude of their destination, turn toward their destination and follow a line of constant latitude. This was known as running down a westing (if westbound, easting otherwise).[3] This prevented a ship from taking the most direct route (a great circle) or a route with the most favourable winds and currents, extending the voyage by days or even weeks. This increased the likelihood of short rations,[4] which could lead to poor health or even death for members of the crew due to scurvy or starvation, with resultant risk to the ship.
Errors in navigation have also resulted in shipwrecks. Motivated by a number of maritime disasters attributable to serious errors in reckoning position at sea, particularly such spectacular disasters as the Scilly naval disaster of 1707, which took Admiral Sir Cloudesley Shovell and his fleet, the British government established the Board of Longitude in 1714:
"The Discovery of the Longitude is of such Consequence to Great Britain for the safety of the Navy and Merchant Ships as well as for the improvement of Trade that for want thereof many Ships have been retarded in their voyages, and many lost..." [and there will be a Longitude Prize] "for such person or persons as shall discover the Longitude."
The prizes were to be awarded for the discovery and demonstration of a practical method for determining the longitude of a ship at sea. Prizes were offered in graduated amounts for solutions of increasing accuracy. These prizes, worth the equivalent of millions of dollars in today's currency, motivated many to search for a solution.
Britain was not alone in the desire to solve the problem. France's King Louis XIV founded the Académie Royale des Sciences in 1666. It was charged with, among a range of other scientific activities, advancement of the science of navigation and the improvement of maps and sailing charts. From 1715, the Académie offered one of the two Prix Rouillés specifically for navigation.[5] Spain's Philip II offered a prize for the discovery of a solution to the problem of the longitude in 1567; Philip III increased the prize in 1598. Holland added to the effort with a prize offered in 1636.[1] Navigators and scientists in most European countries were aware of the problem and were involved in finding a solution. Due to the international effort in solving the problem and the scale of the enterprise, it represented one of the largest scientific endeavours in history.
[edit] Time equals longitude
Since the Earth rotates at a steady rate of 360° per day, or 15° per hour (in sidereal time), there is a direct relationship between time and longitude. If the navigator knew the time at a fixed reference point when some event occurred at the ship's location, the difference between the reference time and the apparent local time would give the ship's position relative to the fixed location. Finding apparent local time is relatively easy. The problem, ultimately, was how to determine the time at a distant reference point while on a ship.