Besace

Cramer studied and named this quartic in 1750. Take the circle on the diameter from A(a, 0) to B(0, b), and on each horizontal line mark the point whose distance from the y axis equals the distance from O to where the line meets the circle; the marks make the curve. With b = 0 it is the lemniscate of Gerono, and its parametric form shows it is a Lissajous curve.

(x² - by)² = a²(x² - y²)

On mathcurve.com as Besace