OF NAVIGATION.. T HE General Approbation of this Book, fince its firft Impreffion in 1686, hath obliged me not only to publifh my Grateful Acknowledgment thereof; but also excited my diligent Search into, and exact Survey of every Part of its Structure, to find out the Defects, to know all its Deficiencies, which I have fo far laboured in, That in this Impreffion, I have now Rectified what was amifs; Altered what was Disorderly; Explained what was Dark or Obscure; Enlarged where it was Scanty; Added where it was Wanting; And, Thele Retifications, Alterations, Emendations, and Additions, being in diverfe Places, I thought it needless to Enumerate them particularly; for they are obvious to a diligent Reader, that will but compare the Rules, Precepts, and Examples of this with the former Impreffions, in the plain and easy Method they are placed in, but which in general is thus; I. You have Pract Geometry, explained by Definitions, Problems and Proportions; In this Chapter is taught the making the most useful Geometric Figures, with the meafuring all Superficies and Solids; Alfo the Application thereof in Practical Meafuring, Board, Glafs, Plaistering, Painting, Paving, and Land; Timber and Stone; Gauging of Cafks, and a Ship's Hold: All being illuftrated with Rules, Proportions and Examples, eafy to the Understanding, and not burthenfome to the Memory and fo ftated that they may be performed both by Arithmetic, and by the Line of Numbers on Gunter's-Scale, in in 37 Problems The first Chapter I advise the Learner to ftudy well before II. Plane Trigonometry is next, in which are many And bere I must advertise the Young Student that would III. Then follows Plane Trigonometry, applied in Pro- blems of Sailing by the Plane Sea-Chart, commonly called And that nothing be wanting, I begin with the common Notes of the Julian Calendar (in this Edition tranfmuted for the Gregorian or New Calendar, or by the late Act of Parliament required) fhewing how to find the Prime, Epact, Dominical-Letter, Eafter-Day, the Moon's-Age, South- ing, and Time of Full-Sea, or High-Water, In 9 Prob. Then proceeding to the Defcription and Ufe of the Plane- 1. In a Right-angled Triangle, relating to a Single Courfe, in which are 6 Cafe, commonly called the 6 Cafes 2. In a Right-angled Triangle, to several Courses called a Traverse. 3. In an Oblique-Triangle, in which are but 4 Cafes, V. In Chapter 4th is Mercator's Sailing; To the right understanding of which, 'tis neceffary to defcribe Mr. Wright's Projection, commonly known by the Name of Mercator's Chart, and shew the Ufes of it, before I treat of the Problems of Sailing by it; which you will find performed in 12 Problems: In the first 9 the Table of Meridional V. Spheric Trigonometry, or the Dorine of Spheric And in Spheric Trigonometry properly fa called (the VI. The Description and Ufe of both Globes, is the To which is annexed a fhort Defcription and Ufe of the VII. Geography subject of this Chapter, which VIII. Great Circle Sailing comes next, which as it's the the Application of both Spheric and Plane Trigonometry, IX. Next you have Spheric Trigonometry, applied in fundry Aftronomic Problems useful in Navigation, wherein the Circles of the Sphere are defcribed, and the necessary Terms of Art explained to the meanest Capacity, with Respect to the diurnal Motion; and that either, 1. According to the Ptolomaic Syftem, wherein you bave in a Right-Angle Spheric Triangle, all the Variety of In an Oblique Spheric Triangle, you have great Variety both with Refpect to the Sun or a Star, in many Questions and Examples relating to the Sun's Altitude, Azimuth, and Hour of the Day, in any Place, at any Time of the Year : And relating to a Star, as to its Longitude, Latitude, Decli- nation, Right Afcenfion, Rifing, Setting, Amplitude, Alti- 2. According to the Pythagorean, or Copernic System, which is now generally receiv as most agreeable to the ob- ferved experienc'd Motion of the enly Bodies; wherein Spheric Trigonometry is applied in variety of Questions and Examples relating to the Earth's Diurnal Motion about its own Axis, once in 24 Hours, whereby all the vifible Ap- pearances of the Sun and Fixed Stars are folved, with the Defcription of the Circles of the Sphere, and how they are drawn Stereographically on the Plane of the Earth's Ecliptic, X. Then follow very ealy Rules to find the Variation of the Compafs, and how to rectify the fame, and to Correct |