The tinman's manual and builder's and mechanic's handbook : designed for tinmen, japanners, coppersmiths, engineers ... with compositions and receipts for other useful and important purposes in the practical arts (1861)
Butts, I. R. (Isaac Ridler), 1795-1882 · Boston : I.R. Butts & Co. · leaf 25
2 equal 5,multiplied by 31416 equal 15-7080 inches circumference. TO FIND THE AREA OF AN ELLIPSE. Rule.—Multiply the longer diameter by the shorter diameter, andby •7854, and the product will be the area. Example.—Required the area of an ellipse whose longer diameteris 6 inches and shcrter diameter… … First construct a rectangle ADEB equal in width to the diameterof the elbow, and tlie length equal to the circumference; tlicn fromthe point J, the middle of the line AB, draw the line .III, and fromthe point F, the middle of tiie line AD, draw the line FG ; from tliopoint J draw two diagonal lines…
