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an instrument that graphs certain physiological processes, such as heartbeat, respiration, and muscle contractions.
A mechanical kymograph was used for the first time by the German physiologist K. Ludwig in 1847 to record changes in blood pressure. The apparatus consisted of a metal drum, covered with smoked paper and evenly rotated by a clock mechanism. A stylus attached to a rod and connected to the contracting heart, muscle, or other functioning organ describes a curve on the drum.
The speed of rotation of the kymograph is regulated by the movement of a friction clutch along the axis and depends on the dimensions of an air brake. Electrokymographs are used for investigations demanding greater accuracy. These kymographs ensure a constant but easily regulated speed of movement. The driving drum of the electrokymograph is set in motion by an electric motor.
I. N. D’IAKONOVA