The problem was that no timepiece existed that could be set at home and relied on to keep time accurately while at sea, where pendulums were notoriously unreliable. So, even if local time could be determined from the noonday sun, there was no time to compare it against. This was the problem that Harrison set out to solve.
Despite this, Harrison was initially awarded only half the promised amount. On a voyage from England to Jamaica in —62, H4 lost just five seconds in over two months at sea. It was now possible for a navigator to determine local time by measuring high noon, and compare this to the absolute time, which had been set on an accurate chronometer at the start of the voyage.
At long last, both latitude and longitude could now be determined accurately, and for the first time you could say exactly where on Earth you were. Today, it's all done electronically through GPS, a world-wide radio navigation system made up of a constellation of 24 satellites and their ground stations.
These 'artificial stars' are used as reference points to calculate a terrestrial position to within an accuracy of a few metres. In fact, with advanced forms of GPS you can make measurements to within a centimetre! What would Harrison have made of it?
Fisher D. Larijani L. As a tribute to the historian Lisa Jardine, who died on October 25th, we're republishing her essay on the shady history of 17th Century timekeeping. How do you measure latitude or longitude? Here's a step-by-step guide on how to work out your latitude and longitude. This free course, Geography in education: exploring a definition, is aimed at geography teachers, or those with an interest in studying or teaching geography.
It looks at the contribution that geography can make in the education of young people and the characteristics and purpose of geography as a subject. What impact will global warming really have?
This free course, Climate change: island life in a volatile world, examines the potential problems faced by the people of the Pacific Island of Tuvalu as a result of rising sea levels.
Where would you go if your island is only a few feet above sea level? Who would you blame? Using the US and Mexico as the main example, this free course, Living in a globalised world, examines how inequalities in access to material wealth can lead to border tensions. You will also learn how many developed economies are now reliant on immigrant labour to perform jobs that their own citizens do not want to consider.
How equal is the globalised world? We invite you to discuss this subject, but remember this is a public forum. Please be polite, and avoid your passions turning into contempt for others.
We may delete posts that are rude or aggressive, or edit posts containing contact details or links to other websites. If you enjoyed this, why not follow a feed to find out when we have new things like it? Choose an RSS feed from the list below. With an angle of longitude and an angle of latitude, we can locate any point on the surface of the earth.
You've seen lines running across maps your whole life and may not have noticed them. The lines running North to South are called "Meridians" or "lines of longitude" Figure 2 , while the lines running East to West are called "Parallels" or "lines of latitude" Figure 3.
Figure 2. Meridians or "Lines of Longitude" and degree readings for longitudes in increments of 30 degrees. Parallels or "Lines of Latitude" and degree readings for latitudes in increments of 30 degrees. Note that the lines are parallel when we look at the earth from the equator. What is Latitude and Longitude? About Lat Long Latlong. TV Series Locations. Movies Locations. Music Videos Locations.
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