The History of Latitudes and Longitudes

In The history of latitudes and longitudes, initially, people required a mechanism to pinpoint their location when they started travelling vast distances through deserts and seas. As a result, a global grid was created, which included latitude and longitude lines.

People used landmarks and primitive maps to orient themselves in the classical era. This functioned well in the short term, but for longer journeys across the featureless landscape like the ocean or desert, new strategies were required. To establish their location, travellers now needed a point of reference/coordinates.

History of latitudes and longitudes

Discovering Latitude

The skies were employed to compute latitude by the Phoenicians as well as the Polynesians in 600 AD and 400 Ad respectively. Throughout history, incredibly advanced instruments such as the gnomon as well as the Arabian Kamel have been developed to estimate the altitude of the sun over the horizon and thus latitude.

The quadrant, as well as the astrolabe, were used by astronomers for decades to calculate the tilt of stars. They were the first devices in use at ocean/seas to calculate latitude.

But, Calculating and knowing latitude was not enough. There was a need to measure longitude to calculate the precise location.

Discovering Longitude

Hipparchus

For centuries, brilliant thinkers had attempted to discover a way of establishing longitude. A Greek astronomer, Hipparchus (190–120 BC), first used longitude and latitude as coordinates to identify position. His proposal was a zero meridian that passed through the Rhodes. 

He also proposed that absolute time must be calculated by watching lunar phases, eclipses, calculating the time when the eclipse began and ended, and calculating the discrepancy between absolute and local time. His technique, however, necessitated the use of a precise clock, which had yet to be constructed. 

Gemma Frisuis

Gemma Frisius suggested a new way to calculate longitude by the use of a clock in 1530. On departure, the watch would be set to absolute time, which can then be matched to the local time upon arrival. Unfortunately, it would be another 200 years or more before fairly precise clocks became accessible, but when they did, Frisius’ technique was proven to work.

Cracking longitude was critical not just for navigational safety, but also for the expansion of maritime trade. In 1567, King Philip II of Spain declared to award compensation to anyone who could solve the problem.

The Italian astronomer Cassini

Cassini has mapped the globe using Jupiter’s moons, as Galileo originally advised. A pendulum clock was used in Paris to time the eclipse of Jupiter’s moons. He returned to the West Indian island of Goree in 1681 where absolute time was discovered, which was then compared to local time, allowing the island’s longitude to be computed.

Although the challenge of establishing longitude upon land had been overcome, the approach was rendered worthless at sea due to the inability to precisely time the eclipses of Jupiter’s moons due to the vessel’s motions.

The English Parliament promised a £20,000 reward to anybody who can calculate longitude at sea in the 1700s.  Many prominent experts started to work, but it was John Harrison, an anonymous clockmaker from Yorkshire, who rose to the occasion.

He realised that if local time based on the sun’s position could be figured out and also the time at a reference point, you could figure out the temporal distinction between the two. This allowed us to calculate the distance between the two locations in terms of longitude.

The difficulty was that no clock could be fixed at the house and trusted to keep exact time when at sea when pendulums were renowned for being inaccurate. Harrison went to find a solution to this challenge.

Harrison’s Clock – The Long-Awaited Answer

He finally developed his maritime chronometer named H4, the clock that can calculate longitude.

A navigator may now establish local time by measuring high noon and comparing it to the absolute time recorded on the accuracy of the chronometer at the outset of the voyage. He could then compute the value of the degree of longitude.

Finally, both longitude and latitude could be correctly calculated, allowing anyone to declare precisely where they were on the planet for the very first time.

Finally, the GPS!

It’s all done online now, thanks to GPS, a global radio navigation system consisting of orbiting satellites & their ground stations. They act as reference points for calculating a  position within several metres of precision. Modern GPS systems allow us to make readings down to the centimetre! 

Conclusion

The latitude was discovered in the 600’s followed by which Gemma Frisius proposed a new method of calculating longitude using a clock, which was successful for the land. Finally, for the sea, Harrison created the H4 maritime. chronometer, a timepiece that can compute longitude. Thus, the history of latitudes and longitudes dates back to  600 Ad and evolves to where we are today: the GPS! It took the brilliance and hard work of so many people to be able to achieve the target of calculating precise latitudes and longitudes, which is the reason why we can use it today for so many purposes.