CHAPTER IX. WIND-POWER.

Wind-power, aside from the objections of uncertainty¹ and irregularity, is the cheapest kind of motive-power. Steam machinery², besides costing a large sum as an investment, is continually deteriorating³ 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 mechanism⁴ need be made here. The force of the wind, moving in right lines, is easily applied⁵ to producing rotary⁶ 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 [42] 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?

1 uncertainty   

n.易变，靠不住，不确知，不确定的事物

参考例句：

• Her comments will add to the uncertainty of the situation.她的批评将会使局势更加不稳定。
• After six weeks of uncertainty,the strain was beginning to take its toll.6个星期的忐忑不安后，压力开始产生影响了。

2 machinery   

n.(总称)机械，机器；机构

参考例句：

• Has the machinery been put up ready for the broadcast?广播器材安装完毕了吗？
• Machinery ought to be well maintained all the time.机器应该随时注意维护。

3 deteriorating   

恶化，变坏( deteriorate的现在分词 )

参考例句：

• The weather conditions are deteriorating. 天气变得越来越糟。
• I was well aware of the bad morale and the deteriorating factories. 我很清楚，大家情绪低落，各个工厂越搞越坏。

4 mechanism   

n.机械装置；机构，结构

参考例句：

• The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
• The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。

5 applied   

adj.应用的；v.应用，适用

参考例句：

• She plans to take a course in applied linguistics.她打算学习应用语言学课程。
• This cream is best applied to the face at night.这种乳霜最好晚上擦脸用。

6 rotary   

adj.(运动等)旋转的；轮转的；转动的

参考例句：

• The central unit is a rotary drum.核心设备是一个旋转的滚筒。
• A rotary table helps to optimize the beam incidence angle.一张旋转的桌子有助于将光线影响之方式角最佳化。