Geometrical and graphical essays, containing a general description of the mathematical instruments used in geometry, civil and military surveying, levelling, and perspective (1807)
Adams, George, 1750-1795 · London : Dillon · leaf 372
gle at the cen-ter: then say, as the tangent, of half the angle at the center, isto half the length of one of the sides j so is radius, to the per-pendicular sought. The area of a circle is thus determinedj if the diameter begiven, say, as 1 : is to 3.141592 :: so is the diameter : to the… … of AN IRREGULAR FIGURE. 3.53 pczium G C D F; and the base D F, and perpen-dicular M E, of the triangle D E F. In order to determine where on the base linesthe perpendiculars shall fall^ the land measurercommonly makes use of a square, consisting of apiece of wood about three inches square,…
Mathematical instruments
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