Conchoid Small 320×244 Medium 640×487 Large 1024×780 Download Tiff Original 2400×1827 | (586.6 KB) Description Illustration showing a conchoid, "a curve, shell-like in flexure (whence the name), invented by Nicomedes in the 2nd century B.C., and used by him for finding two mean proportionals." Keywords conchoid, conchoids, curve, mean proportional, proportionals Galleries Analytical Geometry Source: Frederick Converse Beach Encyclopedia Americana (New York, NY: Americana Company, 1903)
