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History Of The Sextant

October 27th, 2010

Brass Sextant Paperweight

The sextant is a very important item for the navigator. However, like everything else on this planet, it had to evolve. The very beginnings of the sextant were a bit more unrefined and couldn’t quit hit the nail on the head. While modern day brass sextants are outclassed by the global positioning system, which many navigators criticize for it’s many faults.

The need for a navigational tool in the nautical realm arose as a way for exploration to take place on the treacherous uncharted seas. In order to use a sextant, a few things had to be done first. For instance, an almanac had to exist that included the location of celestial objects and bodies in relation to our planet at every single hour of every single day for many years. Furthermore, a device capable of measuring time to a precise point must be utilized. This is called a chronometer. Cartographers were necessary to plotting and charting maps so that longitude and latitude could be found and marked by the observer. A simple mathematical formula to transform the relation of the celestial body and the horizon with the navigators position would also be needed. With these things in place the sextant would be the final key in locating an accurate position of one’s self on the globe.

However, long before the invention of the sextant, navigators had to rely on Polaris to find their way back to their home port. The Arabs were very good at doing this, and used a device known as a Kamal to their advantage. The Kamal relied on a short rope and an object that sighted Polaris at the top and the horizon at the bottom. A knot was tied at the exact location of which he could align the two. When returning from a voyage back home the navigator would adjust his sailing in order to bring Polaris into the same position he had when he left port.

In the 10th century Arabs gave Europe two very important astronomical devices that would lead to the sextant – the astrolabe and the quadrant. The quadrant was especially useful to the Portuguese explorers. Explorers such as Columbus would mark off the points of altitude witnessed of Polaris similar to the Arab way of tying knots in the Kamal. This would be done in ports that the sailors wished to return to, and would eventually the alturas would become published so other sailors could find their way around the coasts of Europe and Africa.

The astrolabe was a remarkable device for use on sea as it could retain its position amongst the ever changing harsh conditions at sea. It was used for more than 200 years because of this. The astrolabe used a circular scale, and rotatable alidade with sighting pinnules. When held at eye level a celestial object could be viewed through the pinnules and the altitude read from the point of crossing by the alidade on the scale.

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