""Periodic Orbits About An Oblate Spheroid"" is a scientific book written by William Duncan Macmillan and published in 1909. The book is a comprehensive study of the periodic orbits around an oblate spheroid, which is a three-dimensional shape that is flattened at the poles and bulging at the equator. The author provides a detailed analysis of the mathematical equations that govern the motion of particles around such a spheroid, and he explores the...