This book is comprised of two papers written by Robert Goddard for the Smithsonian Institution: "A Method of Reaching Extreme Altitudes" and "Liquid Propellant Rocket Development." Two of the most significant publications in the history of rockets and jet propulsion, these reports--the first published in 1919 and the second in 1936--were issued at a time when little was known about rockets and jet propulsion. Goddard's first paper addressed the theoretical possibility of obtaining great ranges by means of well-designed rockets. It showed also that fairly high jet velocities were obtainable, and mentions progress in the construction of a solid cartridge magazine-type rocket. The second paper served as a progress report and indicated what had been accomplished during experimentation. Goddard went on to lay the foundations for the development of long range rockets, missiles, satellites and spaceflight. Unabridged republication of Rockets: "A Method of Reaching Extreme Altitudes" and "Liquid-Propellant Rocket Development," published by the American Rocket Society, New York, 1946. 96 black-and-white illustrations.