 Whittaker's "reciprocal spiral" does have a footnote, which refers to Cotes's "Harmonia Mensurarum" and Newton's Proposition 9.However, it is misleading, since the spiral of Proposition 9 is the equiangular spiral, which he does not recognise as a Cotes's spiral at all.Unfortunately, subsequent authors have followed Whittaker's lead without taking the trouble to verify its accuracy.