Nautical Astronomy and Navigation: Part 1 - Containing Rules Foe Finding the Latitude and Longitude, and the Variation of the Compass

Two distinct methods are used for navigating a ship from one place to another : the first is an application of the common rules of Plane Trigonometry, the necessary angles and measurements being supplied by means of the compass and log-line ; the second and more exact method requires a knowledge of the rules of Spherical Trigonometry and of the principal definitions and facts in Astronomy, the necessary data being obtained by astronomical observations taken usually with the sextant. The latter method is for this reason called Nautical Astronomy ; the characteristic name of the former being Navigation or Plane Sailing.