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 73
Fig. 108, … It will be remarked that, in all cases of circles tangential to each other,their centres and their j)oints of contact must lie in the same straight line. Peob. XXI.—To draw tangentsto two given circles.1st Jfethod (fig.110).—Draw thestraight line ABCthrough the cen-iig. no. tres of the two
