The Nautical Instrument Sextant is accompanied by a documentation with description in which their use is explained in detail. This model is in reality an octant, the precursor of the sextant (corresponding to its displacement to float a sixth part of a circle, 60°, hence its name), used by sailors from the seventeenth century to calculate the breadth, the position of the ship with the calculation of the height of the stars, the sun. This instrument is a pioneer and rudimentary model and during the taking measurements it has a very big mistake. For yet have the modern sextant still a mistake 10° arc and are not suited for astronomical measurements, only for navigation. These 10° correspond to an error of latitude of about 300 m (without regard to the error that is not caused by the refraction of light and the measurement itself). To determine the latitude with knowledge of the height of a star there are two different methods. Sextant (in reality an Octant). Nautical instrument made to find latitude. Wood frame, brass engraved by way of acid; glass; mirrors and plastic color  protections. Box size: Length 31cm  x  Width 38cm x Depth 8cm.