The Sextant
The sextant is an instrument that allows measurements of celestial objects in relation to the horizon, which provides excellent results in finding the latitude of the ship. The sextant allows direct observation of the stars and can therefore be used 24 hours a day. For solar observations, the sextant is equipped with filters that protect the eyes from solar radiation.
The horizon and the celestial object always remain stable, even when the user is on a mobile boat. This is because the sextant sees the horizon directly, and sees celestial objects through two opposing mirrors that dampen the possible displacements of the sextant due to the ship’s movements caused by waves.
The scale of a sextant has a length of one-sixth of a full circle (60°); hence the name sextant . If the scale is one-eighth then the instrument is called an octant.
Isaac Newton (1643-1727) was the first to invent the principle of double reflection on which this navigational instrument is based, but he never published it. Two other researchers, working separately, developed the octant around 1730: John Hadley (1682-1744), an English mathematician, and Thomas Godfrey (1704-1749), a Philadelphia glassmaker.
At Antiquus, we have two types of presentation as can be seen in the photographs. The first is a compact embossed leather case, the second case is also leather but has a glass window. Either of them is a perfect presentation for the object. If you have a special preference, please indicate it to us in the “observations” section when you place the order, otherwise we will understand that any of them is valid.
We also send a small booklet with the history and principles of its operation as well as indicate where in iNTERNET learn how to use it.
Here I found a curious video that was filmed on board the Quinto Real at the end of May 2016. It explains with a real example how to calculate the distance to a point on the coast by observing the height of a reference represented on the chart measured with the sextant.
We hope you found this post helpful.
Sources: Antiquus, aytolacoruna, Navarre nautical school.