CONTENTS.

LECTURE III.

MECHANICS.

s\ F the Centre of Magnitude, Motion, and^ Gravity, 148

How found Geometrically in all Bodies , 152

Of the Common Centre of Gravity of two ormore Bodies , 156

Exemplified and applied to the Earth and Moon,

156, 157

¥0 the Sun and System of Planets, 160

'The several Mechanical Powers , 161

MECHANIC POWERS.

Of the Lever, 161, 162

The Absurdity of a perpetual Motion, 163

Of the Balance, 164, 165

Of the False Balance, 169

Of the Statera, or Steel-yard, 170

Of the Pulley, ibid.

Of The Wheel and Axle, 171, 172

Of The Inclined Plane, 172

Of the Wedge, ibid.

Of the Screw, 173

Of the Nature of a Compound Pendulum,

174, &c.

Of Frictions in Machines , 179

Of Friction-Wheels, 184

The greatest Perfedlion of Machines^ ib. 185Of the Common Jack. i88