The elements of navigation : containing the theory and practice, with all the necessary tables, to which is added, a treatise of marine fortification ... (1754)
Robertson, J. (John), 1712-1776, Adams, Charles Francis, 1807-1886, former owner. BRL, Adams, John, 1735-1826, former owner. BRL, Boston Public Library) John Adams Library BRL · London : Printed for J. Nourse ... · leaf 150
in the diam. bd. i Make the arc p d = arc p b ; a ruler on E and dives c in db produced. Then on c with the radius c a defcribe b a E.1 For, As e is the projecting point, and p the pro-ved pole; Therefore p is the pole of the circle af to be projected. And b a e is the projection of the circle af.… … 444. 128 SPHERICS. 444. PROBLEM III. A projected circle being given, to find its poles. Case i. When the given circle aeb is the primi-tive. -}-« IB Const. Find the centre c, (161) and it is the, pole fought. Case 2. When the given circle acb is a rhbllE • 7 ° ^ s :—-~_ circle. 1 Const. Draw a…
Navigation · Nautical astronomy · Fortification
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![An illustration from Vnderweysung der Messung : mit dem Zirkel vn[d] Richtscheyt in Linien, Ebnen vnnd gantzen Corporen (1525)](https://img.insideoutlibrary.com/img/200/ia-vnderweysungderm00drer-53-97.webp)
