The existence of the surplus labor army being established, there remains to be established the economic necessity for the surplus labor army. The simplest and most obvious need is that brought about by the fluctuation of production. If, when production is at low ebb, all men are at work, it necessarily follows that when production increases there will be no men to do the increased work. This may seem almost childish, and, if not childish, at least easily remedied. At low ebb let the men work shorter time; at high flood let them work overtime. The main objection to this is, that it is not done, and that we are considering what is, not what might be or should be. Then there are great irregular and periodical demands for labor which must be met. Under the first head come all the big building and engineering enterprises. When a canal is to be dug or a railroad put through, requiring thousands of laborers, it would be hurtful to withdraw these laborers from the constant industries. And whether it is a canal to be dug or a cellar, whether five thousand men are required or five, it is well, in society as at present organized, that they be taken from the surplus labor army. The surplus labor army is the reserve fund of social energy, and this is one of the reasons for its existence. Under the second head, periodical demands, come the harvests. Throughout the year, huge labor tides sweep back and forth across the United States. That which is sown and tended by few men, comes to sudden ripeness and must be gathered by many men; and it is inevitable that these many men form floating populations. In the late spring the berries must be picked, in the summer the grain garnered, in the fall, the hops gathered, in the winter the ice harvested. In California a man may pick berries in Siskiyou, peaches in Santa Clara, grapes in the San Joaquin, and oranges in Los Angeles, going from job to job as the season advances, and travelling a thousand miles ere the season is done. But the great demand for agricultural labor is in the summer. In the winter, work is slack, and these floating populations eddy into the cities to eke out a precarious existence and harrow the souls of the police officers until the return of warm weather and work. If there were constant work at good wages for every man, who would harvest the crops? But the last and most significant need for the surplus labor army remains to be stated. This surplus labor acts as a check upon all employed labor. It is the lash by which the masters hold the workers to their tasks, or drive them back to their tasks when they have revolted. It is the goad which forces the workers into the compulsory "free contracts" against which they now and again rebel. There is only one reason under the sun that strikes fail, and that is because there are always plenty of men to take the strikers' places.