Asymptotes, 111, 113, 114, 115, 116, 117, 118, 148

Axes of a conic, 148

Axial pencil, 7, 8, 23, 50, 54

Axis of perspectivity, 8, 47

Bacon (1561-1626), 162

Bisection, 41, 109

Brianchon (1785-1864), 84, 85, 86, 88, 89, 90, 95, 105, 113, 174, 184

Calculus, 176

Carnot (1796-1832), 179

Cauchy (1789-1857), 179, 181

Cavalieri (1598-1647), 162

Center of a conic, 107, 112, 148

Center of involution, 141, 142

Center of perspectivity, 8

Central conic, 120

Chasles (1793-1880), 168, 179, 180, 184

Circle, 21, 73, 80, 145, 146, 147

Circular involution, 147, 149, 150, 151

Circular points, 146

Class of a curve, 183

Classification of conics, 110

Collineation, 175

Concentric pencils, 50

Cone of the second order, 59

Conic, 73, 81

Conjugate diameters, 114, 148

Conjugate normal, 151

Conjugate points and lines, 100, 109, 138, 139, 140

Constants in an equation, 21

Contingent relations, 180, 181

Continuity, 180, 181

Continuous correspondence, 9, 10, 21, 49

Corresponding elements, 64

Counting, 1, 4

Cross ratio, 46

Darboux, 176, 186

De Beaugrand, 170

Degenerate pencil of rays of the second order, 58, 93

Degenerate point-row of the second order, 56, 78

De la Hire (1640-1718), 168, 171, 175

Desargues (1593-1662), 25, 26, 40, 121, 125, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 174, 175

Descartes (1596-1650), 162, 170, 171, 174, 176

Descriptive geometry, 179

Diameter, 107

Directrix, 157, 158, 159, 160

Double correspondence, 128, 130

Double points of an involution, 124

Double rays of an involution, 133, 134

Duality, 94, 104, 161, 180, 182

Dupin (1784-1873), 174, 184

Eccentricity of conic, 159

Ellipse, 110, 111, 162

Equation of conic, 118, 119, 120

Euclid (ca. 300 B.C.), 6, 22, 104

Euler (1707-1783), 166

Fermat (1601-1665), 162, 171

Foci of a conic, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162

Fourier (1768-1830), 179

Fourth harmonic, 29

Fundamental form, 7, 16, 23, 36, 47, 60, 184

Galileo (1564-1642), 162, 169, 170, 176

Gauss (1777-1855), 179

Gergonne (1771-1859), 182, 184

Greek geometry, 161

Hachette (1769-1834), 179, 184

Harmonic conjugates, 29, 30, 39

Harmonic elements, 86, 49, 91, 163, 185

Harmonic lines, 33, 34, 35, 66, 67

Harmonic planes, 34, 35