Original Title: A Treatise On Spherical AstronomySpherical or positional astronomy is used primarily to map objects on the celestial sphere. In this technical work, first published in 1908 and intended for advanced students, Sir Robert Stawell Ball (1840-1913) breaks down the field into distinct areas of study. Assuming a good level of geometry and trigonometry, he begins with fundamental formulae before moving into the determination of coordinates, atmospheric refraction, the theory of cartography, and more. Each section contains exercises derived from a variety of sources, including contemporary Cambridge examinations. The coverage ranges from the calculation of stellar parallax to the geometrical principles behind the Mercator projection. Testifying to the knowledge expected of university students in the early twentieth century, Ball's book remains instructive to their modern counterparts. More accessible to the general reader, The Story of the Heavens (1885), Star-Land (1889) and A Popular Guide to the Heavens (1905) are also reissued in this series.