John Harrison, the watchmaker who brought about the accurate measurement of longitude, a task that astronomers had failed at

The importance of the chronometer to Britain cannot be overstated. The ability to increase the safety of voyages in ships turned it from a maritime power into a world-wide empire

Today, when we use GPS, the problem of locating the longitude where we are is a philosophical problem, but throughout history, it has had life and death consequences.

325 years ago, on March 24 according to the old calendar - a calendar that was used in Great Britain and its colonies, a date corresponding to April 3 in the Gregorian calendar, which is the calendar used today all over the world - John Harrison, a watchmaker by profession, was born in Yorkshire, Great Britain, who responded to the greatest challenge of Doro - locating the longitude where ships are in the middle of the sea.

In the book "The Longitude" Dova Sobel, then the editor of the science section of the New York Times, explains: "In the age of the great discoveries, the problem of the longitude was the greatest challenge facing the scientists. "
"Well-known scientists - from Galileo Galilei to Isaac Newton - mapped the sky, being sure that there lies the answer. But then one man stood up to the entire scientific establishment, his name was John Harrison, who dared to propose a mechanical solution - a clock that would indicate the exact time in the middle of the sea, something that no clock until then had been able to do even on land, and the race began..."
In the introductory chapter to the book, Sobel explains, among other things, that lines of latitude and longitude appeared on pictures of our world already in ancient times, at least 300 years BC. In 150 AD, the cartographer and astronomer Ptolemy drew them on 27 maps in his first world atlas. He also recorded the names of the places in alphabetical order. Next to each name (locality) he noted its longitude and latitude - as far as he could determine from the descriptions of the travelers who arrived in their days.

"Since the sailors were unable to determine the longitude they were in, many of them lost their way at sea. Many ships ran aground and others were easy prey for pirates. In 1714, the English Parliament offered a reward worth a huge fortune to anyone who could find an accurate method for measuring longitude. "

Ancient seafarers could estimate the north and south directions by celestial bodies such as the North Star or the position of the sun at noon, but the east and west directions were more difficult to determine. The problem was especially acute on long journeys when there was no land in sight. The solution is in the hands of the British watchmaker John Harrison who accepted the challenge and competed for the prize that will be awarded to whoever finds an efficient way to measure longitude. In the second half of the 18th century, he joined a sea voyage that began in Portsmouth in England to Bridgetown, the capital of Barbados in the Caribbean Sea. Harrison used a chronometer (precise clock) he built to keep accurate time in Britain, while making astronomical observations to estimate the local time on the ship making its way to Barbados. Having both times at his disposal, and since the longitude of Barbados was known, he could determine the position of the ship relative to that line. When he got to Bridgetown it turned out that he was wrong about the location of the ship by only 16 km.

Today it is possible, with the help of longitude and latitude, to map the exact location of each and every point on the surface of the globe. Nowadays the satellite GPS does all the work for us so that we don't get lost anymore, even in the forest..

Since the determination of latitude derives from nature itself (the equator), the determination of zero longitude was arbitrary. Harrison's discovery was the effect of time - in order to know the longitude in the middle of the sea, you must know at that exact moment what time it is on the ship you are on and the time in your home port. Knowing the time according to these two clocks allows the navigator to translate the time difference between them into a geographical distance.
Knowing the exact time in two different places at the same time, which is a prerequisite for finding the longitude, was not available until the invention of pendulum clocks and even after they were invented, on a ship swaying in the sea, pendulum clocks would lag behind, hurry or stop moving altogether.
The governments of the maritime countries including Spain, the Low Countries, and certain Italian cities offered enormous sums of money to anyone who would invent an effective method. In the Longitude Act passed by the British Parliament in 1714, a reward of 20 thousand pounds was offered, which is worth millions of dollars according to today's values, to whoever invents a practical and useful method for determining the longitude.
The English watchmaker John Harrison was a genius in mechanics and a pioneer in the field of portable precision timepieces and devoted his life to this search. He accomplished what in Newton's opinion was impossible, he invented a clock that would carry with it the real time as if Ash were always the manager of the house in every corner."

"Without formal education and without undergoing an apprenticeship with an expert watchmaker, he built a series of watches that were almost frictionless and did not need lubrication or cleaning. These clocks were made of rust-resistant materials and all their moving parts worked in perfect balance even as the world around them swayed and rocked from side to side. He removed the pendulum from his clocks and integrated different metals into their mechanisms, so that with the expansion or contraction of one component due to temperature changes, the action of another component would cancel out the effect of the change and ensure that the rate of deviation of the clock would be constant."

"However, the prize committee rejected it and changed the rules in favor of the astronomers and against the "mechanics". The committee was chaired by the Reverend Neville Masqueline, the fifth Astronomer Royal. But Harrison's method, due to its ease of use and due to its accuracy, won out in the end.
The aged and emaciated Harrison, who had been patronized by King George III, finally received the monetary reward he was entitled to in 1773, after forty difficult years of political intrigue, international wars, academic slander, scientific revolution and economic upheavals. "

He died on his 83rd birthday, on March 24, 1776.

For more - Longitude, the true story of the lone genius who solved the greatest scientific problem of his time by Deva Sobel. Translation by Neely Landsberger, scientific editor, Prof. Yoav Yair. The book was published by Keter in 1998

To the book page on the Keter Publishing website

In the same topic on the science website:

• The curse that became a blessing - about the disaster of the Isles of Scilly
• The introduction to the book: Everything in measure, the seven-year journey that changed the world by: Ken Elder