The naval architect's and shipbuilder's pocket-book of formulae, rules, and tables and marine engineer's and surveyor's handy book of reference (1884)
Mackrow, Clement · London, C. Lockwood and co. · leaf 79
2. Trapezoid.Fig. 105. AF. 3 __ (Fig. 105.) Rule.—Bisect ab in e and cd in p,and join ef. Produce AB beyond B to--^.-..2 ^ Daaking bh^^CD, and produce CDbeyond C to i, making 01 = A3; thenjoin HI, and where this line intersectsEF is the centre of gra\ity G. 3. Trapezium.Fig. 106. (Fig. 106.) … Rule.—Draw the diagonals adand CB intersecting in e ; along CBset ofE CF equal to eb, and join faand fd : the centre of the triangleafd will be the centre of the tra-pezium. 4. Circular arc.Fig. 107. (Fi
