Now what used to be paid to one person can be spread out over four. This increases the degree of exploitation. Since machinery increases the amount produced in a period of time, the working day can be lengthened to get the largest amount of productivity. In machinery the job of men becomes automated. The momentum to increase the amount of machinery in the production process is due to the fact that this can be more easily controlled than the elastic nature of people.
Machinery produces surplus value because it labor of higher degree and efficacy.
It enables the capitalist to replace the value of a day's labor power by a smaller portion of the value of the day's product. The rate of surplus value is determined by the relative duration of the necessary labor and of the surplus labor in a day. As the use of machinery becomes more common in the industry, the surplus value arises from the labor power employed by the human working the machinery. It is only from human labor power or variable capital that surplus value is created. The application of surplus value implies a contradiction.