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The instrument described records the time interval between successive r wave impulses of the electrocardiogram, thereby providing a graphic record of the rate of each beat. A description is given of the electronic circuits, which are of the simplest type, requiring a minimum of adjustment during construction. Tube and circuit elements are not critical in value and are available at any radio supply house. Application of the instrument in the measurement of the heart rate in man during exposure to positive acceleration on the human centrifuge is briefly discussed.
Sturm et al. (Wed,) studied this question.