TO THЕ TEACHERS OF NAVIGATION. I IN GENTLEMEN, N' the Course of your Tuition, it is probable that you have discovered many Errors in the last Edition of this Book; for the Rapidity of its Sale induced others to print Copies of it, without that accurate Revifion neceffary in a Work of this Nature. Fraught with fo many Errors, I blushed. to behold what they unjustly called my PRACTICAL NAVIGATOR. I am now, Gentlemen, happy in having the Opportunity of presenting you with a new Edition, revifed and improved, which I truft is more confiftent with my Credit, and convenient for your Ufe; Concifenefs of Method, and Facility of Operation, being the principal Points aimed at. I have inferted two Methods of reducing the apparent Distances of Celestial Objects to their true Diftances. These are exemplified and rendered easy. All the Tables requifite in the Calculations are properly numbered, for the more readily finding them; and the Examples are accommodated to the Year 1796, the Nautical Almanac for that Year being now published. I have only, Gentlemen, refpectfully to add, that by pointing out any Errors that may yet have escaped my Notice, you will confer a great Obligation on, Your much obliged, And very humble Servant, JOHN HAMILTON MOORE, Tower-Hill, Loudon, THE со CONTENT S. To work Middle Latitude and Mercator's Sailing together, 101 To find the Longitude by the Eclipfes of Jupiter's Satellites, 248 A Table for finding the Distance of TerreftrialObjects at Sea, 260 An Explanation of the Sea Terms, The Examination of a Young Sea Officer, refpecting the work- The Tables ftand in the following Order. TAB. I. The Difference of Latitude and Departure for Points TAB. III. The Meridional Parts TAB. IV. The Latitude and Longitude of Places TAB. V. The Refraction of the heavenly Bodies in Altitude TAB. VI. The Dip of the Horizon TAB, VII. The Sun's Parallax in Altitude TAB. VIII. The Augmentation of the Moon's Semi-diameter TAB. XV. Shewing the Time of the Sun, Moon, and Star's TAB, XVI. For finding the Latitude by two Altitudes of the Sun TAB. XVIII. For turning Degrees and Minutes, into Time TAB. XIX. The Proportional Logarithms TAB. XX. For computing the Effects of Parallax on the Moon's TAB. XXI. Of Logarithms TAB. XXII. Of artificial Sines, Tangents, and Secants. ERRAT A. Page 111, In the second Line under the Table, reject 55 Miles of Page 109, In the Anfwer to the feventh Question, for as Diff. of Page 139. In finding the Number of the Month, for 7 read 8. Page 200. The fifth Line from the Bottom, for Boards read Boats. Page 240, Question 6. Make the fuppofed Longitude 8° W. the re- duced Time 5h. 22' 57", the true Time will be 4h. 38′ 7′′, and the true Diftance 77° 38' 27". Find the Distances between 3 and 6 Hours, and the Longitude will be 7° 59′ West. N. B. The rapid Sale this Book has had fince its firft Publication, has THE PRACTICAL NAVIGATOR, AND SEAMAN's NEW DAILY ASSISTANT. GE GEOMETR Y. DEFINITIONS. EOMETRY is that Science by which we compare fuch Quantities together as have Extenfion, i. e. Lines, Superfices, and Solids, whofe original is from a Point. I. A Point hath no Parts; that is, a Geometrical Point is not any Quantity, but only an affignable Place in a Quantity denoted by a Point, as at A. A. Such a Place may be conceived fo infinitely small, as to be void ' of Length, Breadth, and Thickness; and therefore a Point may 'be faid to have no Parts.' II. A Right Line is the nearest Distance between two A Points, which limit its Length, as A B. III. Circular Lines are thofe which lie bending between two Points. IV. Parallel Lines are thofe that are equally diftant in all their Parts, which being infinitely extended on the fame Plane, will never meet. |