Prelude to Space, the first of the novels, is a vivid account of the events that culminate in a man's first voyage to the moon. Written when the adventure seemed a remote possibility, and now regarded as a classic in its field, it gains fresh interest from an introduction discussing ways in which the actualities of space travel are overtaking the author's speculations about it. Actuality has yet to overtake Sands of Mars, a novel in which courageous and visionary men bring off a vast experiment to make permanent colonization of that forbidding planet possible.