Sextant

The Sextant: Math Solved the Longitude Problem

Mathematics in Nautical Navigation

The Challenge: Dead Reckoning


Imagine you go out for a walk. You have to close your eyes and walk for 10 minutes. You know what direction you are walking in, you know how fast you were walking. So you should know exactly where you are without opening your eyes, right? This is dead reckoning. It is a navigation technique that uses speed and direction to figure out distance. The problem is that you probably opened your eyes and weren't as far as you thought you were. Imagine being on a ship and there are waves pushing you, currents that move you subtly further East without you realizing. That's a problem. Land could be just over the horizon but you sail right past because you were 1 mile too far to see it. As you can imagine, a lot of people died.
Double Reflection Principle 4

Around the 17th century, there was a great issue with finding longitude while at sea. It was referred to as the Longitude Problem. Latitude (north-south) was easy to find during the day because all one has to do is reference the sun. Longitude (east-west) was more difficult to find and resulted in the invention of the sextant and pocket watches. Sextants were used for calculating the degree the sun was at in the sky. This would then be compared to the time of day and it was all based back to Greenwich, England.


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