First published in 1958, and composed primarily of presentations delivered at the Ninth General Assembly of the International Astronomical Union in 1955, this book contains sixteen papers on the subject of the Galactic System in the light of then-recent developments in radio astronomy. The contributors compare new knowledge of our Galactic System with what can be gleaned from other galaxies and star systems, such as the Andromeda nebula. This book will be of value to anyone with an interest in astronomy and in the development of astronomical knowledge.