Described by one reviewer as ‘one of the most perfect books ever written on theoretical astronomy’, this work in Latin by the German mathematician Carl Friedrich Gauss (1777-1855), the ‘Prince of Mathematicians’, derived from his attempt to solve an astronomical puzzle: where in the heavens would the dwarf planet Ceres, first sighted in 1801, reappear? Gauss’ predicted position was correct to within half a degree, and this led him to develop a streamlined and sophisticated method of calculating the effect of the larger planets and the sun on the orbits of planetoids, which he published in 1809. As well as providing a tool for astronomers, Gauss’ method also offered a way of reducing inaccuracy of calculations arising from measurement error; the primacy of this discovery was however disputed between him and the French mathematician Legendre, whose Essai sur la theorie des nombres is also reissued in this series.