Co-ordinate geometry, plane, 128 et seq.

planes, 168

Coplanar forces, 91

Cosecant of an angle, 4

Cosine of an angle,

Cotangent of an angle, 4
Couples, 107

Coversed sine of an angle, 4
Cross-rolls, geometry of, 335
Cube, 182

Cubic equation, 144
Curtate cycloid, 69
Curvature, centre of, 13
circle of, 12

radius of, 13

Curve, harmonic, 149

y = a + bx", 137
y = a*, 139
y= a log, br, 140
y = br", 136

y = x", 135

yx"= c, 138

Curved surfaces and tangent planes, 313

Ellipse, 30, 32, 38-45, 48, 49
equation to, 133

Ellipsoid, 337

Elliptic paraboloid, 341
Elliptical cylinder, 255
Envelope, 13

- glissette, 78

- roulette, 77

Epicycloid, 70

spherical, 428

Epitrochoid, 72

Equation, graph of, 129
Equations, graphic solution of, 142
Equiangular spiral, 141
Error in measuring, 4

Escribed circles of a triangle, 20
Evolute of a conic, 49
of a curve, 13
Exponential curve, 139
equation, 139

Face mould, 371, 374
Falling moulds, 373
Figured plans, 279
Focus of a conic, 30
Forces, coplanar, 91

specification of, 91
Fourier series, 158
Frequency, 148

Funicular polygon, 92

Generating line, 313
Generation of surfaces, 313

Generatrix, 313
Geometrical mean,

Glissettes, 78

11

Gorge of hyperboloid, 331

Graph of equation, 129

Graphic arithmetic, 10

solution of equations, 142
statics, 91 et seq.

Gravity, centres of, 96

Great circle of a sphere, 249

Ground line, 168, 301