As machine power rivalled hand work, promoters of industry until recently relied for its advancement on the perfection of technology, giving little thought to the perfection of labor. It was confidently assumed that labor, out of its own necessities, would adapt itself automatically to the new requirements of the machine, and to the shifts of business interest. When it was discovered that there were limitations to labor's voluntary adaptation under the conditions laid down, intelligent business in America decided that the responsibility for realizing labor's adaptation or "labor's coöperation" as they call it, must be assumed by the management of industry and that that management must be scientifically worked out and applied. Scientific management is scientific as it subjects the labor operations on each job, each specific job to be performed in a factory, to a testing out of the energy consumed; to discovering how to secure labor's maximum productivity without waste of time or energy. It is scientific as the manager's state of mind towards the physical and psychological reactions of the workers is one of inquiry and a readiness to accept, as facts of mechanical science are accepted, the reaction of the workers. A scientific manager, or engineer as he is often called, bears the same relation to the labor force in a factory that an electrical engineer bears to the electrical equipment. If his attention to the emotional reaction of the workers is less detached than scientific standards require, it must be remembered that he is trying to make adjustments which must first of all meet definite business conditions. Where the reactions of the workers interfere with the whole scheme of business administration, (and interfere they ceaselessly do), he has to substitute measures which are not strictly speaking scientific. On these occasions he adopts humanitarian schemes, which are generally spoken of as welfare work. It is the introduction of these schemes which look like a "slop over" from science to charity, that makes it difficult for outsiders to tell just what scientific management is and what it is not.