Appleton's cyclopædia of drawing, designed as a textbook for the mechanic, architect, engineer, and surveyor (1866)
Worthen, William Ezra, 1819-1897, [from old catalog] ed, Appleton, firm, publishers, New York. (1866. D. Appleton & co.) [from old catalog] · New York, D. Appleton and company · leaf 563
f their ordinates,and the curves drawn from point to point by sweeps and variable curves.Approximately, knowing the central ordinate of the curve between twopoints, the central ordinate of one half that curve will be one quarter ofthe first. Thus, fig 32, G D is about one quarter of E F, hence by… … Fig. 34.
