The sextant detailed a great step in the history of navigation. Centuries after its conception, the sextant continues to be a valued tool to traditional navigators. However, the introduction of the sextant required an evolutionary process of its own. The sextant had to endure large periods of growth in order to adapt to the ever changing demands of ocean travel. Sadly, all innovations must eventually become replaced by newer innovations. True to this, modern day sextants are outclassed by the global positioning system, though old school navigators criticize GPS for its many faults.
Before the sextant there were a long list of other navigational aids that helped sailors find their way around. Way before the first sextant was invented, sailors learned how to use Polaris to travel back and from home port. The Arabs in particular were proficient in using this technique. To aid them, the Arabs used what is known as a "Kamal". The Kamal used a short rope and an object that placed Polaris and the horizon on the top and bottom respectively. A knot was tied in the rope in order to mark the distance between Polaris and horizon. The knot which showed the relation of Polaris to the horizon was used for the sailors to find their way back to their original port.
The Arabs introduced the Europeans to two vital navigational aids that would help in the creation of the sextant. Among the two important instruments were the astrolabe and the quadrant. The astrolabe was a revolutionary sea travelling device as it could retain its position in relation to the fickle conditions that betray our senses at sea. Because of this, the astrolabe saw over 200 years of use. The astrolabe used a circular scale and rotatable alidade with sighting pinnules. The altitude of the celestial object is then gauged by viewing through the sighting pinnules and using the alidade.
The second of the two instruments that foreshadowed the sextant was the quadrant. The quadrant was used to great extent by the Portuguese in particular. A little known man by the name of Christopher Columbus enlisted the help of the quadrant to navigate the ocean easier. For example, Polaris was marked off and recorded in ports that sailors frequented. These alturas would eventually become published, allowing other sailors to travel around the coasts of Europe and Africa more easily.
As the needs of nautical exploration arose, so did the need for a navigational instrument that was accurate and reliable. In order to use a sextant, a few things had to be done first. For one, an almanac that detailed the location of stars and other points had to be accounted for at every hour of every day for several years. Also, there had to be an instrument capable of measuring time to an exact point. This device was called a chronometer. The cartographer was in charge of plotting and charting maps for securing the location of alturas. A mathematical formula for relating a celestial body with the horizon and navigator's position was also necessary. The sextant as the next logical step in the evolution of navigation thus made sense.
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