NAVIGATION is the Art which instructs the mariner how to conduct a ship over the wide and trackless ocean, from one port to another, with the greatest safety, and in the shortest time possible.

Navigation may be divided into two branches: viz. *Seamanship*, comprehending the method of managing a vessel by disposing her sails, rudder, &c. so that she may move in any assigned course or direction the wind or weather will permit; and *Navigation Proper* (the part we intend to treat of in the present site), which comprehends those methods by which a mariner determine at any time the situation of his vessel, the course she is to be steered, and the distance she has to run, to gain her intended port: hence the requisites for a mariner, in order to understand this branch of the Nautical Art, are, a competent knowledge of the figure of the earth, with the various imaginary circles drawn upon it, so as to be able to ascertain the distance and situation a places with respect to each other; the method of finding the ship’s latitude and longitude, either by her course and distance run, or by astronomical observations; the use of various instruments, as the log, compass, log-glass, quadrant, sextant, chronometer, &e.; the different allowances necessary to be made in estimanting a ship’s way, as for leeway, the variation and deviation of the compass, and currents; the method of finding the time of high water at any place; the use of charts, with the method of constructing them: all of which particulars, depending upon mathematical and astronomical principles, endeavour, in the following pages, to explain and illustrate in such a manner as to render every part as clear, concise, and methodical as possible.

## 0 commenti