20 are in the threble ratio of that in which their diameters are.' There are in all 15 propositions in the book. The Thirteenth Book teaches the most wonderful properties of a line divided by an extreme and mean proportion, the com. position of the five regular solids, a tetrahedron, a cube, an octo hedron, an icosahedron, adodecadedron (चतुष्फलकक्षऊघनहc, आ ऽफलतघनक्षेत्र, विंशतिफलकयुतत्र समभुजद्वादशकक्षेत्र respectively), bhe method of inscribing bhem in a sphere and a comparison of bhe solids to one another and to the sphere in which they are inscribed. The book contains 21 proposition The Fourteenthh Book which comprises ten propositions treats of the comparison and proportion of the five regular solids. The Fifteenth Book, which is the last book in our text, deals with the inscription of the five regular bodies within one another. It teaches how to inscribe an equilateral cone in a cube, an octohedron in an equilateral cone, or in a cube, a cube in an octohedron, and a dodecadedron in an icosahedron. The striking features of the Rekhanita Having thus given a resume of the contents of the Rekha. gapita, let me next point out the stariking features of the work as compared to English editions of Duclid. 1. Definitions, Postulates, and Axioms are called परिभाषा or 'Zerminology. 2. Axioms are given before Postulates and bhe last three Axioms are placed atter the Postulates. 8. The Twelfth Axiom has a simpler form. It is defined as follows:- If two straight lines which are not parallel be produced in the direction in which bhe distance between them is greater, bhe further bhey are produced, the greater the distance between them; while if they are produced in the direction in which the distance is less, the further they are produced, the less the distance between them till at length the two straight lines meet together, and then the distance between them goes on increasing.
