July 12, 2007
Every day in London, England by the Thames River at 12:55 p.m, a red ball climbs halfway up a mast, hovers there for 3 minutes, then ascends all the way to the top and waits another 2
minutes. At precisely one o’clock, the ball drops. The act has been in practice since 1833.
Madam Toastmaster, my fellow toastmasters, and most welcomed guests:
There is a story behind this and it is very relevant to you and me and everyone else. Let me tell
you the story. Since the ancient times when humans started to sail, people have been asking: "Where am I?"
We specify our location by a grid system; that’s longitude and latitude. The Latitude lines run horizontally. Each line is called a parallel. The Equator is the 0 degree parallel. The North Pole is the 90-degree north and the South Pole is the 90-degree south parallel. When you know your latitude, you know where you are North-South-wise.
The Longitude lines run vertically. Each line is called a meridian. There are 180 lines, i.e. 180
degrees, to the east and 180 lines to the west. When you know your longitude, you know where you are East-West-wise from the 0-degree meridian.
It is easy to find the latitude, because there is always a fixed reference point: The Sun is
almost always directly above the Equator and never wanders beyond the 23.5 degrees north and south. When you know the angle between the horizon and the sun
To find the Longitude position is a very different story. Because there is no reference point: as
the Earth turns, the heavenly bodies you see change as the time goes, even if you stay at the
same place.
In a foggy day in 1707, four British war ships ran aground and killed nearly 2000 sailors in one
day, because they did now know their longitude position. All major European nations offered high rewards for a way to find the longitude. The British Parliament, in its famed Longitude Act of 1714, set the highest bounty of all, naming a prize equal to several million dollars in today’s
currency for a “Practicable and Useful” means of determining longitude. Finding the longitude
became the hottest scientific problem of the century.
Many great scientists tried to find a way to determine the longitude by mapping the heavenly
bodies without much success. Palatial observatories were founded at Paris, Berlin, and London for the express purpose of determining longitude by the heavens. They were not very successful.
Another approach was needed.
We know the Earth makes a turn in 24 hours and there are 360 longitude lines. 360/24 = 15.
Therefore, for every hour difference in time we have a 15-degree difference in longitude
position. If you are one hour off with your home port, you know you are 15 longitude degrees away from your home port. If the difference is 2 hours, it’s 30 degrees away.To know the time difference, you need to know the local time and the home port time.
It’s easy to know the local time—you set your watch to 12 o’clock noon when the sun is at the
highest point. It is not easy to know the time of the home port. The ship tosses around in the
ocean and makes all pendulums useless; the salty sea air rusts the watch’s components; the
drastic temperature changes at sea, make the watch gain or lose time accordingly. To make a watch that can withstand the hostilities of the sea and keep the time of the home port became the solution to the problem.
Many people have tried but failed. An English man, named John Harrison, designed and made a few watches that overcame those problems. Therefore, at precisely 1 p.m., all sea-going captains would set their watches when the red ball dropped to the Thames River. That’s the home port time. And, if you have a John Harrison watch, you can bring the home port time with you.
In 1773, Mr. Harrison was awarded the prize. Thus, by constructing watches that overcame the hostilities of the sea, a man with very humble upbringing and no formal education solved the greatest scientific problem of his time that is determining the longitude position.
The British government decided that the 0-degree meridian shall be the line running through the Royal Observatory at Greenwich. In 1884, the International Meridian Conference declared this line to be the Prime Meridian of the world. To this east of this line is the East Hemisphere; to the west, the West Hemisphere. The space of the Earth is now defined. We say Iraq is in the
middle east and Japan is in the far east. It is with Greenwich’s point of view.
Since the time defines the position (or space), so is the space defines the time. Every day
starts at Greenwich, 15 degrees to the east, you are one hour ahead of the standard time; 15
degrees to the west, you are one hour behind. Thus, the world’s time and space are both defined by Greenwich. This is not because of the British Empire’s political or military power, not because of its many world-renowned scientists, but because of one English watchmaker, who had a very humble upbringing and had never had any formal education. He solved the greatest scientific challenge of his time. He is Mr. John Harrison.
Madam Toastmaster
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Longitude--The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time; Dava Sobel; ISBN: 0-14-025879-5
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