CHASLES, Michel. Traité de Géométrie supérieure. 1880.

Second edition
Major book of the famous mathematician Chasles.
" La Géométrie supérieure, when it was published, was new, in many respects for the subjects, and mainly for the methods of demonstration which, thanks to the use of the signs and the introduction of the imaginary, participate to the advantages of the These methods are distinguished by the special character that the quantities likely to become imaginary do not enter in explicit form, but are represented by real elements, just as in Analysis the roots of an equation. are collectively represented by the coefficients of this equation.The work contains the theories of the anharmonic relationship, involution, homographic or correlative figures and their applications to polygons and circles, and ends with two interesting chapters: the one concerns certain properties of two circles leading to elegant representations of the equations relating to elliptic functions; the subject of the theory of circular cones and spherical cones, to which Chasles had, as early as 1830, devoted two remarkable contributions in Volume VI of the Memoirs of the Brussels Academy. " Eugene Rouchê.