Key to the Universe, or a New Theory of Its Mechanism. Founded upon a I. Continuous Orbital Propulsion, Arising from the Velocity of Gravity and Its Consequent Aberrations; II. Resisting Ethereal Medium of Variable Density. With Mathematical Demonstrations and Tables Pratt, Orson Published by Published by the Author, and for Sale at the Historian's Office, Salt Lake City, 1879 2nd ed

book is in fair shape some soiling and heavy wear on hardcover but inside is solid and tight 118 pages