1. E.g., Math. Monthly (ed. J. D. Runkle), 1, 1859, p. 249. There are also more elaborate papers such as “Sur les courbes de poursuite d'un cercle,” by M. L. Dunoyer, Nouv. Annales de Math., 4th series, Vol. 6, 1906, p. 193. [Compare page 91 of this issue.—Editor].