33 2 AMERICAN ANTHROPOLOGIST [n. s. t I, i8w
These devices for applying power are sometimes called the mechanical powers, and the powers themselves are called forces, for they are devices to produce modes of motion.
Again I must remind the reader that there is no such thing- as abstract power ; it is always concrete, and its concomitants must always be considered when we consider real power as such. Power exists as an abstraction only in consideration.
Having considered the nature of powers, we have now to con- sider them as they are utilized in tools and machines. A tool may be defined as an implement employed to utilize human power. A machine may be defined as an implement employed for using any other power than that of human muscle. The tool is dependent on the hand and is adapted to the use of the hand, while the machine is adapted to the use of other powers than that of the hand, though these powers may be directly or indi- rectly controlled by the hand. A flint may be fashioned into a knife on a grindstone supported by a wooden horse ; the grind- stone is a tool, but it may be run by water-power, when it be- comes a machine, for it must be provided with the apparatus necessary to utilize the fall of water. A hand-hammer is a tool ; but a trip-hammer is a machine, for some other power than that of human muscle is used in its operation. The hand-dasher in a churn is a tool ; a power dasher in our modern dairies is usually a machine. The flail is a tool used only by human power ; the thresher is a machine in which horse-power or steam-power is employed.
In the multiplication of processes, which we have already il- lustrated somewhat, many machines are employed in the manu- facture of a single class of products. Often these machines are housed for their protection and for the protection of the laborers who are operating them. Such a group of machines with their houses is called a mill or a factory. In the mill many machines may be used, and many tools, all designed for the common pur- pose of producing a class of objects.
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