NAVIGATION is the art of conducting a vessel from one port to another, by ob servation of the heavenly bodies, calcula tion of the distance, or way, made daily, and by steering such a course, under guid ance of the compass, as may lead, in the most direct manner, from the place quit ted to the ship's destination. Before we proceed on this topic, it may be proper to stipulate for a competent knowledge of geography ; especially of the division of our globe, by the various circles and me ridians, by which it is intersected in theo ry. The student must also be thorough ly acquainted with all relating to the needle ; in particular the dip and varia tion, and be able to take an account of the ship's progress numerically, or, as it is termed, in dead-reckoning ; and if he should possess some skill in geometry and trigonometry, he will find that his task is more easily performed, and that he will, in due time, render himself conspicuous in that branch of his honourable profes sion.
We shall preface this subject with a few details that will be found useful : they will prepare the way for farther operations ; and serve, in addition to what has been premised in regard to mathematical ac. quirement, to give such a solid foundation, as will leave the reader at no loss as he proceeds in the more intricate parts of the science. We shall commence with the absolute necessity of readily boxing, i. e. telling the points of the compass. Under the head of Mairsx-rxsat, we have slight. ly touched on this subject, but shall now explain, that each quarter of the compass card, or index, is divided into eight equal portions called points. The four cardinal points, i. e. North, South, East and West, form the terminations of two diameters standing at right angles : the four points ascertained by dividing the several quad rants into two equal portions each, give compound points; which are named after the two adjunct cardinals respectively ; observing that North and South have pre cedence in each designation. Thus the mid-point between North and East is call.
ed " North East ;" that between North and West is called "North West ;" that between South and East is called "South East;' and that between South and West is called " South West." By this process we have divided the circumference into eight equal parts. Now let each segment between the several cardinals, and their compounds, be subdivided into four equal portions ; so that the whole circle may be partitioned into thirty.two parts ; i. e.. eight between each of the adjunct cardi nals ; the two points adjunct to North will be "North by East," and " North by West ;" those adjunct to South will be " South by East," and " South by West ;" those adjunct to East will be "East by North," and " East by South ;" while the adjuncts to West will be " West by North," and " West by South." The two adjuncts to the compounds will be as fol low ; to North East they will be " North East by North," and " North East by East ;" to South East they will be "South Ea.it by South," and " South East by East ;" to North West they will be "North West by North," and "North West by West ;" and to South West they will be " South West by South," and "South West by West." There yet re main eight points, equidistant between the several cardinals and the compounds : these have their designations made by prefixing, to that of the adjunct com pound, that of the cardinal to which it is nearest. Thus between North and North West, the point is called "North, North West," and that between North West and West, is called " West, North West:" thus we have " North, North East," and " East, North East ;" " South, South West," and " West, South West ;" " south, South East," and " East, South East." In Plate IX. Miscel. fig. 9 and 10, we have given figures of a compass and com pass-card, according to the mariner's ar rangement just described, in which only the initials are shewn : the North point being distinguished, as it always is, by a fluer de lys, or some particular indicial ornament. For further particulars, see compass.