_WIND-POWER._
Wind-power, aside from the objections of uncertainty and
irregularity, is the cheapest kind of motive-power. Steam
machinery, besides costing a large sum as an investment, is
continually deteriorating in value, consumes fuel, and requires
continual skilled attention. Water-power also requires a large
investment, greater in many cases than steam-power, and in
many places the plant is in danger of destruction by freshets.
Wind-power is less expensive in every way, but is unreliable
for constancy except in certain localities, and these, as it
happens, are for the most part distant from other elements of
manufacturing industry. The operation of wind-wheels is so simple
and so generally understood that no reference to mechanism need
be made here. The force of the wind, moving in right lines, is
easily applied to producing rotary motion, the difference from
water-power being mainly in the comparative weakness of wind
currents and the greater area required in the vanes upon which
the wind acts. Turbine wind-wheels have been constructed on
very much the same plan as turbine water-wheels. In speaking of
wind-power, the propositions about heat must not be forgotten.
It has been explained how heat is almost directly utilised by
the steam-engine, and how the effect of heat is utilised by
water-wheels in a less direct manner, and the same connection will
be found between heat and wind-wheels or wind-power. Currents of
air are due to changes of temperature, and the connection between
the heat that produces such air currents and their application as
power is no more intricate than in the case of water-power.
(1.) What is the difference in general between wind and water
wheels?--(2.) Can the course of wind, like that of water, be
diverted and applied at pleasure?--(3.) On what principle does
wind act against the vanes of a wheel?--(4.) How may an analogy
between wind-power and heat be traced?