Wheel and Axle.--Thickness of the Rope.--Ways of applying the Power. --Projecting Pins.--Windlass.--Winch.--Axle.--Horizontal Wheel.-- Tread-Mill.--Cranes.--Water-Wheels.--Paddle-Wheel.--Rachet-Wheel.-- Rack.--Spring of a Watch.--Fusee.--Straps or Cords.--Examples of.-- Turning Lathe.--Revolving Shafts.--Spinning Machinery.--Saw-Mill.-- Pinion.--Leaves.--Crane.--Spur-Wheels.--Crown-Wheels.--Bevelled Wheels.--Hunting-Cog.--Chronometers.--Hair-Spring.--Balance-Wheel. 178 CHAP. XV. OF THE PULLEY. Cord.--Sheave.--Fixed Pulley.--Fire Escapes.--Single moveable Pulley.--Systems of Pulleys.--Smeaton’s Tackle.--White’s Pulley.-- Advantage of.--Runner.--Spanish Bartons. 199 CHAP. XVI. ON THE INCLINED PLANE, WEDGE, AND SCREW. Inclined Plane.--Effect of a Weight on.--Power of.--Roads.--Power Oblique to the Plane.--Plane sometimes moves under the Weight.-- Wedge.--Sometimes formed of two inclined Planes.--More powerful as its Angle is acute.--Where used.--Limits to the Angle.--Screw. --Hunter’s Screw.--Examples.--Micrometer Screw. 209 CHAP. XVII. ON THE REGULATION AND ACCUMULATION OF FORCE. Uniformity of Operation.--Irregularity of prime Mover.--Water-Mill. --Wind-Mill.--Steam Pressure.--Animal Power.--Spring.--Regulators. --Steam-Engine.--Governor.--Self-acting Damper.--Tachometer.-- Accumulation of Power.--Examples.--Hammer.--Flail.--Bow-string.-- Fire Arms.--Air-Gun.--Steam-Gun.--Inert Matter a Magazine for Force.--Fly-Wheel.--Condensed Air.--Rolling Metal.--Coining-Press. 224 CHAP. XVIII. MECHANICAL CONTRIVANCES FOR MODIFYING MOTION. Division of Motion into rectilinear and rotatory.--Continued and reciprocating.--Examples.--Flowing Water.--Wind.--Animal Motion.-- Falling of a Body.--Syringe-Pump.--Hammer.--Steam-Engine.--Fulling Mill.--Rose-Engine.--Apparatus of Zureda.--Leupold’s Application of it.--Hooke’s universal Joint.--Circular and alternate Motion.-- Examples.--Watt’s Methods of connecting the Motion of the Piston with that of the Beam.--Parallel Motion. 245 CHAP. XIX. OF FRICTION AND THE RIGIDITY OF CORDAGE. Friction and Rigidity.--Laws of Friction.--Rigidity of Cordage.-- Strength of Materials.--Resistance from Friction.--Independent of the Magnitude of Surfaces.--Examples.--Vince’s Experiments.--Effect of Velocity.--Means for diminishing Friction.--Friction Wheels.-- Angle of Repose.--Best Angle of Draught.--Rail-Roads.--Stiffness of Ropes. 260 CHAP. XX. ON THE STRENGTH OF MATERIALS.