Geometrical and graphical essays, containing a general description of the mathematical instruments used in geometry, civil and military surveying, levelling, and perspective; with many new practical problems (1803)
Adams, George, 1750-1795, Jones, William, 1763-1831 · London, Printed by W. Glendinning for, and sold by W. and S. Jones · leaf 349
ay, as the tangent, or half the angle at tlie centre, is to halfthe length of one of the sides j so is radius, to the perpendicularsought. The area of a circle is thus determined ; if the diameter begiven, say, as 1: is to 3.1415p2 : : so is the diameter : to the cir-cumference ; or, if the… … bases and perpendiculars of the several trapezia andtriangles in the field. Thus, for example,suppose the annexedfigure be a field to bemeasured according tothis method, the landmeasurer would mea-sure with the chain thebase B G, and the per-pendiculars H C, andI A, of the trapezium pABCG; the base…
Mathematical instruments
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