(See also Sections 60, and 12.)
=On land, vehicles, &c., may be propelled by:=
=a. Any engine= having contained in itself its source of power; such
as a steam engine, compressed-air engine, electric motor, &c.
=b. Any fixed source of power,= the moving vehicle being connected to
it by: 1, a rope or chain; 2, a tube; 3, an electric wire or other
electric connection.
=c. By gravitation= down an inclined or vertical road. See Section 69.
=d. By wind power,= using sails or windmill. See Section 95.
=e. Animal power.=
=On water, vessels are propelled by:=
=a. Wind.=
=b. Steam= or other heat engine.
=c. Wave motion.=
=d. Natural currents,= tides.
=e. Animal power.=
=In air, balloons have been propelled by:=
=a. Wind.=
=b. Some kind of engine power.=
=c. Hand power.=
But the two latter sources must be at present considered almost
impracticable.
MEANS EMPLOYED FOR PROPULSION.
=On land:=
=a. Steam or other engine and boiler= on the moving vehicle.
=b. A reservoir of compressed air= or gas, driving an engine on the
vehicle.
=c. An electric battery= or accumulator, driving an engine on the
vehicle.
=d. Rope railway:= the rope may be driven by any kind of engine.
=e. Endless rope= transmission. See Section 66.
=f. Inclined or vertical hoists.= See Section 69.
=g. Ice vessels,= or yachts, propelled by wind and sails, windmills,
&c. See Section 95.
=h. Velocipedes= of all kinds, hand power lifts and hoists. See