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 85
Dem. Draw the diameter cf ; then Z. acf is right. (209) Therefore the Z. acf is meafured by half the arc cdf. (107) But the angle dcf is meafured by half the arc df. (211)Therefore Z. acd (=z. acf—z.dcf) is meafured by half the arc DC (=CDF — DF). And z. c e d is meafured by half the arc c D» (211)… … GEOMETRY; 216. THEOREM XIX. Between a circular arc (ahf) audits tangent (ae),no right line can be drawn from the point of con-tact (a). -iB DeMon. For if any other right line can be drawn, let it be the right line ab. From d the centre of ahf, draw dg perpendicular to ab, cutting ab in g, and the…
Navigation · Nautical astronomy · Fortification
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