498 See an interesting paper by Whitworth, W. A., ãThe Equiangular Spiral, its chief properties proved geometrically,ã in the Messenger of Mathematics (1), I, p. 5, 1862.
499 I am well aware that the debt of Greek science to Egypt and the East is vigorously denied by many scholars, some of whom go so far as to believe that the Egyptians never had any science, save only some ãrough rules of thumb for measuring fields and pyramidsã (Burnetãs Greek Philosophy, 1914, p. 5).
500 Euclid (II, def. 2).
501 Cf. Treutlein, Z. f. Math. u. Phys. (Hist. litt. Abth.), XXVIII, p. 209, 1883.
502 This is the so-called DreifachôÙgleichschenôÙkelige Dreieck; cf. Naber, op. infra cit. The ratio 1ã₤:ã₤0ôñ618 is again not hard to find in this construction.