“ It was further investigated by John Wallis, Christiaan Huygens (who determined the length of any arc in 1657) , and Pierre de Fermat (who evaluated the area between the curve and its asymptote in 1661) . It is constructed in the following manner. Let APB be a semicircle, BT the tangent at B, and APT a line cutting the circle in P and BT at T; take a point Q on AT so that AQ always equals PT; then the locus of Q is the cissoid. Sir Isaac Newton devised the following mechanical construction. Take a rod LMN bent at right angles at M, such that MN = AB ”