This textbook presents principles, ratios and proportions, the circle and measurement of angles, the proportions of figures and the measurement of areas, regular polygons and measurement of the circle, planes and solid angles, polyhedrons, the three round bodies, spherical triangles and spherical polygons, regular polyhedrons, plane and spherical trigonometry, and mensuration. [This book was translated by David Brewster. It was revised and adapted by Charles Davies.]