CHAPTER VI. ON THE NATURE AND OBJECTS OF MACHINERY.

Machines do not create or consume, but only transmit and apply power; and it is only by conceiving of power as a constant element, independent of every kind of machinery¹, that the learner can reach a true understanding of the nature of machines. When once there is in the mind a fixed² conception of power, dissociated from every kind of mechanism³, there is laid, so to speak, a solid foundation on which an understanding of machines may be built up.

To believe a fact is not to learn it, in the sense that these terms may be applied⁴ to mechanical knowledge; to believe a proposition is not to have a conviction of its truth; and what is meant by learning mechanical principles is, as remarked in a previous place, to have them so fixed in the mind that they will involuntarily arise to qualify everything met with that involves mechanical movement. For this reason it has been urged that learners should begin by first acquiring a clear and fixed conception of power, and next of the nature and classification of machines, for without the first he cannot reach the second.

Machines may be defined in general terms as agents for converting, transmitting, and applying power, or motion and force, which constitute power. By machinery the natural forces are utilised, and directed to the performance of operations where human strength is insufficient⁵, when natural force is cheaper, and when the rate of movement exceeds what the hands can perform. The term "agent" applied to machines conveys a true idea of their nature and functions.

Machinery can be divided into four classes, each constituting a division that is very clearly defined by functions performed, as follows:—

First. Motive⁶ machinery for utilising or converting the natural forces.

Second. Machinery for transmitting and distributing power.

Third. Machinery for applying power.

Fourth. Machinery of transportation.

Or, more briefly⁷ stated—

Motive machinery.
[29] Machinery of transmission.
Machinery of application.
Machinery of transportation.

These divisions of machinery will next be treated of separately, with a view of making the classification more clear, and to explain the principles of operation in each division. This dissertation⁸ will form a kind of base upon which the practical part of the treatise⁹ will in a measure rest. It is trusted that the reader will carefully consider each proposition that is laid down, and on his own behalf pursue the subjects farther than the limits here permit.

(1.) To what three general objects are machines directed?—(2.) How are machines distinguished¹⁰ from other works or structures?—(3.) Into what four classes can machinery be divided?—(4.) Name one principal type in each of these four divisions.

1 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。

2 fixed   

adj.固定的，不变的，准备好的；(计算机)固定的

参考例句：

• Have you two fixed on a date for the wedding yet?你们俩选定婚期了吗？
• Once the aim is fixed,we should not change it arbitrarily.目标一旦确定，我们就不应该随意改变。

3 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。

4 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。

5 insufficient   

adj.(for，of)不足的，不够的

参考例句：

• There was insufficient evidence to convict him.没有足够证据给他定罪。
• In their day scientific knowledge was insufficient to settle the matter.在他们的时代，科学知识还不能足以解决这些问题。

6 motive   

n.动机，目的；adv.发动的，运动的

参考例句：

• The police could not find a motive for the murder.警察不能找到谋杀的动机。
• He had some motive in telling this fable.他讲这寓言故事是有用意的。

7 briefly   

adv.简单地，简短地

参考例句：

• I want to touch briefly on another aspect of the problem.我想简单地谈一下这个问题的另一方面。
• He was kidnapped and briefly detained by a terrorist group.他被一个恐怖组织绑架并短暂拘禁。

8 dissertation   

n.（博士学位）论文，学术演讲，专题论文

参考例句：

• He is currently writing a dissertation on the Somali civil war.他目前正在写一篇关于索马里内战的论文。
• He was involved in writing his doctoral dissertation.他在聚精会神地写他的博士论文。

9 treatise   

n.专著；(专题)论文

参考例句：

• The doctor wrote a treatise on alcoholism.那位医生写了一篇关于酗酒问题的论文。
• This is not a treatise on statistical theory.这不是一篇有关统计理论的论文。

10 distinguished   

adj.卓越的，杰出的，著名的

参考例句：

• Elephants are distinguished from other animals by their long noses.大象以其长长的鼻子显示出与其他动物的不同。
• A banquet was given in honor of the distinguished guests.宴会是为了向贵宾们致敬而举行的。