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Fixing the Longitude Downside

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Navigation on the open ocean is extraordinarily troublesome. It’s a talent that takes years to grasp. 

Even with years of talent, an skilled mariner was nonetheless in a position to floor their ship on an unseen reef, underwater rocks, or a sandbar, as a result of they didn’t know their exact location. 

The primary downside, which was unsolved for hundreds of years, was figuring out your longitude.

Be taught extra concerning the longitude downside, and the way it was ultimately solved, on this episode of All the things All over the place Each day. 


In an earlier episode, I spoke concerning the navigational achievements of the  Polynesians. They managed to discover the Pacific Ocean with out using any superior navigational instruments. Furthermore, they sailed giant outrigger ships that sat very excessive within the water. 

Not solely did they’ve superior information of reefs and methods to navigate them, however their ships, at excessive tide may typically simply sail proper over them. 

European navigators weren’t so fortunate. They’d a lot bigger ships that sat a lot decrease within the water. If there was an underwater hazard corresponding to a rock or a reef, they usually have been to unknowingly hit it, the outcomes might be devastating. 

The truth is, this occurred way more typically than most individuals understand. Simply for instance, Sable Island which is a big sand bar off the coast of Nova Scotia is estimated to have triggered at the least 350 shipwrecks and presumably as many as 500. 

This was only one island. There have been many different such hazards throughout which ships needed to keep away from. 

This was one of many explanation why correct mapping was so essential. There have been many voyages the place a cartographer was despatched alongside to deliver again info to enhance their maps. 

Nevertheless, the perfect map on the earth doesn’t imply something in the event you don’t know the place you’re. 

This was the issue that beset sailors. 

To know the place you have been, you wanted to know two issues: your latitude and your longitude. 

Latitude, that are the imaginary horizontal traces across the Earth, was a reasonably simple downside to unravel. As a result of the Earth rotates round its poles, and since there’s a star within the northern hemisphere the place the pole is, it’s attainable to find out your latitude by realizing the angle between the pole star and the horizon. 

This was achieved by way of a sextant which was a tool that might measure angles. 

In the event you add to this using a compass, you might know your route, however that was it.

There was no means, nevertheless, to find out your longitude.

Longitude traces are the imaginary vertical traces that go from north to south pole. As a result of the Earth is at all times rotating, it’s close to unattainable to get a repair in your longitude based mostly on the celebrities. 

This downside was so essential that the British Parliament handed the Longitude Act 1714 which supplied a prize to anybody who may remedy the issue. 

The prize was between £10,000 and £20,000 relying on the accuracy of the approach. In modern-day cash, that might be between $2 to $4 million {dollars}. Cash went lots additional again then. 

The important thing to figuring out longitude was time. In the event you knew the native time and the time at a hard and fast location, you possibly can decide the distinction in time, and therefore the distinction in longitude. 

The approach that everybody thought would win out was an astronomical approach. 

One of many concepts was the strategy of Lunar distance. The moon strikes throughout the celebrities at a price of about 0.5 levels per hour. When you’ve got good tables, an excellent measurement, and did the calculations, you might decide your native time. 

One other approach was to make use of the moons of Jupiter. As a result of the 4 main moons of Jupiter orbited at a selected price, in the event you knew the place of the moons, once more with some superb tables, you might decide the time. 

The issue with these strategies is that they didn’t actually work on the deck of a ship that was pitching and rolling on the ocean. You’ll be able to’t use a telescope in that kind of atmosphere. 

Furthermore, if the moon wasn’t out, or Jupiter wasn’t within the sky on the proper time of the 12 months, or if there have been clouds, the strategies wouldn’t work. 

The primary British Astronomer Royal in 1675 was principally commissioned to work on this downside and develop tables on the observatory in Greenwich.

These astronomical strategies did really work on land. In the event you have been in say Newfoundland or Kingstown, you might work out the longitude of that spot with respectable accuracy, and that helped in mapmaking.

Nevertheless, it did nothing for aiding navigators on a ship. 

The answer which ultimately received out was the event of an correct clock. 

Initially, nobody thought {that a} clock would work as a result of early clocks required using a pendulum. A pendulum clock on a rocking ship was about as ineffective as attempting to make astronomical observations on a ship with a telescope. 

An English clockmaker by the identify of John Harrison knew that constructing a chronograph was the important thing to fixing the issue of latitude. The trick was engineering a clock that might work at sea, but nonetheless, stay correct. 

Harrison spent 40 years engaged on 5 completely different clocks. His first clock, which was examined on a voyage in 1736, was in a position to decide the longitude of a ship to inside 60 miles. Good however not nice.

Over time he saved continuously bettering his clocks. His closing model regarded like a really giant pocket watch. 

He has solved many issues related to protecting time on a ship, together with the movement of the ship and modifications in temperature.

His closing clock, which was examined in 1772 by King George III himself, was discovered to be correct to inside ? of 1 second per day. Greater than correct sufficient to say the prize.

Nevertheless, he by no means did technically declare the prize. The astronomer royal was on the board overseeing the prize, and the board was very biased in opposition to any non-astronomical answer. In the long run, Harrison did accumulate the equal of the prize, however by no means the acknowledgment of parliament. 

All of the clocks within the British Navy have been synchronized to the Greenwich Observatory, which is the rationale why the Prime Meridian is there, and why Greenwich Imply Time, now known as Coordinated Common Time or UTC, is centered on Greenwich. 

The truth is, in the event you go to the Greenwich observatory in the present day, you possibly can see the primary 4 Harrison timepieces. All of them nonetheless work in the present day. You can even hear the cannon which is fired at midday day-after-day, which was used so ships may synchronize their clocks. 

The early clocks have been costly, however they proved their price. Captain Prepare dinner used a clock similar to Harrison’s fifth clock on his second and third voyages, and he had solely glowing issues to say about them.

Within the nineteenth century, the clocks continued to get higher and cheaper, and in consequence, navigation grew to become higher and safer. Because the clocks have been put in on extra ships, the variety of disasters involving ships operating aground plummeted, and crusing grew to become a lot safer.

Ultimately, because the telegraph grew to become widespread, time alerts can be despatched alongside the wire. Because the sign was nearly instantaneous, measurements of longitude between factors grew to become much more exact. 

Telegraphs didn’t do a lot for ships, however when wi-fi communication was developed, it allowed ships to get time alerts wirelessly, which improved the precision of their measurements. 

In 1912, a convention was held in Paris to coordinate world wi-fi time alerts on completely different frequencies, permitting ships to get correct time info nearly wherever on the globe. 

The pursuit of longitudinal measurement culminated within the growth of the International Positioning System, which permits for pinpoint measurement wherever on Earth. The event of GPS is a subject which I went into a lot larger element in a earlier episode. 

In the event you’ve ever traveled or bought one thing which was made abroad, you’ve gotten been the beneficiary of the answer to the issue of longitude. An issue solved by one decided English clockmaker within the 18th century. 

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