Home / Books / Longitude by Dava Sobel | Book Review

Longitude by Dava Sobel | Book Review

Most of us were born and grew up in the era when electronic items are of day-to-day use, especially today when digital space is a huge presence in our professional as well as social lives. But the electronic revolution is no older than a century.

Difficult though it is for us to imagine, only a few centuries back, scientists were struggling to determine what the earth was actually like, i.e., its dimensions, the nature of its rotation, its place in the solar system and its relationship with the rest of the universe in terms of effective motions and forces. The best way to determine the physical aspects of the earth in that time was to actually travel around and measure the dimensions of different continents and islands. The travel across the sea also had significance in terms of political and religious conquests that lead to the dominion of European countries over rest of the world in fifteenth to twentieth century.

Hence, for entire Europe, the art of navigation was at heart of their wealth and supremacy. And it was the art of navigation that presented Europe with a problem that kept scientists engaged for more than two centuries: “How to determine the longitude when the ship is at sea?”

Imagine you are on a voyage on a fifteenth century ship, with limited supplies of food and water, travelling in an unknown sea with only water around with no signs of land for days, fighting an unpredictable weather and storms with no warnings of it and no means to avoid it. What will be the most important thing? To know where you are at any point of time, i.e., to know you are following a correct path and to know when will you reach your destination. The position of any object on Earth is determined by its latitude and longitude. Latitudes are concentric circles parallel to the equator and it is relatively easy to determine it by observing the position of the sun in the sky at the noon. The problem is longitude. These are the elliptical rings starting from North Pole to South Pole and back to North Pole. The space between these imaginary lines is not fixed either, it increases when the line is near equator and decreases away from it, finally becoming zero at the pole.

Thousands of lives were lost at sea due to sailors not being able to determine their correct position at the sea. The problem rose to such levels that governments and kings declared prizes for the scientist who will solve the problem. The biggest reward was announced by the British Parliamet in 1714, who constituted a board of Longitude and announced a prize of 20,000 pounds (equivalent to millions of dollars today) for the winner. The most promising branch of science that was expected to offer a solution to the problem was astronomy, as astronomers busied themselves in preparing extensive catalogues of the position of the moon and various stars in the night sky. The method however, even if successful, would be time-consuming and requiring advanced skills of computation.

But, there was a simpler solution, “time”, as it is the longitude that controls the way time is measured on various locations on the Earth. For example, we all today follow Greenwich Mean Time because the imaginary prime longitude is situated at Greenwich. And that’s why you are either ahead of GMT or behind it based on your being either on the Eastern or Western side of it. So, if you were on a ship with a clock that would show the time at the reference port, you can easily determine the longitude by simple mathematical calculations.

Today we are able to keep the track of time with atomic clocks, but not then. The clocks in that time used pendulum, the motion of which will be disturbed by the swaying of the ship on the sea. Besides, the metal parts started malfunctioning with the change in temperature and hence, would not be able to keep the time. The sea clocks were expected to be such a precision machine that it was called a “chronometer”, not a watch or clock. And it was a self-educated son of a carpenter called John Harrison (1693-1776), who designed and developed the most accurate “chronometer” of his time.

Dava Sobel explains all these with reference to various historical resources available to us today in her book called “The Longitude”. It is a story of a man who made his own standards and did not accept what others thought about his work. He spent his entire life in perfecting his time measuring machines until he was satisfied. The book also shows glimpses of the rivalry and the politics played in the research field, where scientists are afraid of their ideas being stolen and reluctant to appraise a simple yet genius solution to difficult problem, only because it is not appealing to them. It tells us how John Harrison had to wait and fight for the recognition and the reward that he so truly deserved until almost last years of his life.

A must read for all the science lovers who like to unravel the journey of evolution for devices that we take for granted today. To remind ourselves that scientific history has been a big picture always where generations of scientists have contributed to provide parts and pieces to bring it where it is today. And the trend continues even today….our knowledge and technology keeps expanding every day, because everyday someone on this earth comes up with a new piece of information.

Read the book and remember John Harrison, whenever you look at your wrist watch……..Enjoy….

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