therefore know that his position is somewhere on this circle. In practice, the mathematical process, called "reduction" of the observation, can be complex for the uninitiated. To the height observed with the sextant, it is necessary to apply a series of corrections to compensate for atmospheric refraction, parallax and other errors. Once this is done, it is necessary to solve a spherical triangle by mathematical and trigonometric methods. There are many methods to do this. The manual methods use tables (trigonometric, logarithms, etc.) to facilitate the calculations. The introduction of calculators and electronic computers at the end of the 20th century greatly facilitated the calculation, but the creation of GPS made celestial navigation no longer important, relegating it to the background as an alternative method in case of failure of the on-board electronics or as a hobby of scientific interest. Electronic navigation Navigation and location of the ship by positioning techniques based on the aids provided by global positioning systems, such as GPS, GLONASS, or GALILEO. It is the system most widely spread and easiest to use, in spite of the errors that may arise. Inertial navigation Navigation and location of the ship by means of the analysis of the data provided by accelerometers and/or gyroscopes located on board, which integrate the accelerations experienced in complex electronic systems, that converted into velocities (in the 3 possible axes of displacement) and according to the observed courses, make it possible to obtain the location of the ship. Iconography The harbinger of a successful navigation was the dolphin, which is why its representation became the symbol carried by all ships. More recently, navigation was represented as a woman crowned with ship's sterns whose clothes are agitated by the winds. She rests one hand on a rudder and the other holds the instrument for measuring height. At her feet, the ampoule, the compass, the trident of Neptune and the riches of commerce, while the sea can be seen on the horizon, completed by a lighthouse and traversed by ships at full sail. See also World Cruising Routes Navigation Notes References External links Navigation Ships Celestial navigation Sailors