Each developed mechanism is composed of three parts: the motor, the transmission, and the operating part. It is to the development of this last that the economic revolution of the eighteenth century is due. However, there was needed a motive power greater and more regular than those then available. The steam-engine, invented by James Watt, provided for this need and, in its turn, led to new developments of operating machinery. The steam-engine was capable of running many operating machines at the same time, and thus the modern factory was established. In branches in which the product requires a series of different manipulations, a system of machines has been contrived of which one furnishes the material to the next without the intervention of hands, so that a system of automatic mechanism has been produced. The revolution caused by the introduction of machines in one branch of industry necessitated its introduction into another, etc. The means of communication and of transportation were extended. The steamboat, the railroad, and the telegraph were invented. Because of important inventions in the manufacture of machines it finally became possible to produce the necessary quantity of machines of all kinds. What are the most important consequences of the new system of production? In the first place stands the introduction of the labor of women and children, since tending machines generally does not require great muscular strength. The advantages which accrue to the capitalist from the employment of women and children are obvious. Since the price of the workman’s labor is determined by the time necessary for the production of the necessities of life not only for himself, but also for his family, as soon as the whole family are compelled to sell their labor, the price of that labor will simply equal that of the labor of the workman alone. Ordinarily the income of the family will rise a little under these circumstances, but, because of the absence of the wife from the household, expenses will increase also. The increase of the surplus-value, obtained by the labor of women and children, is therefore important. Besides, the women and children have less power to resist the capitalist than men have, while the men, in their turn, are weakened by the competition of women and children.