A Compleat Treatise of Practical Navigation Demonstrated from It's First Principles; Together with All the Necessary Tables. to Which Are Added, the Useful Theorems of Mensuration, Surveying, and Gauging; With Their Application to Practice. Written for Th (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1734 Excerpt: ...the South West Rumb, &V. the other Rumbs are express'd according to their Situation with respect to thefe middle Rumbs, and the nearest Cardinals, as is plain from the annexed Scheme X 17. The 17, The Card is put into a round Box, made sot it, having a Pin erected in the Middle, upon which the hollow Center of the Needleis fix'd, so as the Card may lie Horizontal, and easily vibrate according the Motion of the Needle; the Box is cover'd pver with a smooth Glass, and is hung in a brass Hoop upon two cylindrical Pins, diametrically opposite to one another, and this Hoop is hung within another brass Circle, upon two Pins at right Angles with the former. These two Circles, and the Box, are placed in another square wooden Box, so that the innermost Box, and consequently the Card, may keep Horizontal which way soever the Ship heels. 18. Since the Meridians do all meet at the Poles, and there form certain A ngles with one another; and since if we move never so little towards the East or West, from one place to another, we thereby change our Meridian, and in every place the East and West Line being perpendicular to the Meridian; it follows, that the East and Weft Line in the first Place, will not coincide with the Eafl and Weft Line in the second, but be inclin'd to it at a certain Angle: and consequently all the other Rhomb Lines at each Place, will be inclin'd to each other, they always forming the fame Angles with the Meridian. Hence it follows that all Rumbs, except the four Cardinals, must be Curves or Helifpherical Lines, always tending towards the Polet and approaching it by infinite Gyrations or Turnings, but never falling into it. Thus let P be the Pole, FQan Arch of the Equator, PE, PA, &c. Mermians, and EFGHKL any Rumb; then because the Angles PE...