instrument(redirected from McCall's instrument)
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a tool of human labor or an actuating mechanism of a machine, which “takes hold of an object of labor and alters it in an expedient fashion” (K. Marx, in K. Marx and F. Engels, Soch., 2nd ed., vol. 23, p. 384).
Instruments are divided into the following categories: (1) cutting (cutter, drill, broach, milling cutter), (2) pressing (stamp, knurl), (3) polishing (polishing wheel, whetstone), (4) percussion (hammer, chisel, punch), and (5) fastening-clamping (machine tool chuck, cutter tool post, vise, tongs). Various devices, apparatus, and equipment used in science and technology for measurements and other procedures and in medicine and veterinary science for surgical operations, therapeutic procedures, and research are also called instruments.