Ernest William Brown (1866–1938) was a British astronomer who worked extensively on lunar theory. In this book, which was originally published in 1908, Brown's aim was to provide a comprehensive study of the effects of other planets on the motion of the moon. The text first appeared as an essay which obtained the Adams Prize in the University of Cambridge for the year 1907. This book will be of value to anyone with an interest in astronomy and the history of science.