The Focal and Bi-Tangent Properties of Bi-Circular Quartics
William P. Milne · Proceedings of the Edinburgh Mathematical Society · 1910
The following direct method of attack establishes the fundamental properties of the Foci and Bi-Tangents of a Bi-Circular Quartic very simply, using only the properties of a homographic correspondence. The method was suggested to me by my previous paper on the focal properties of Circular Cubics. I am indebted to Mr Peter Fraser, University of Bristol, for his criticism.