Abstract
Ballistocardiograms, i.e., records of the heart''s recoil and the blood''s impacts, were obtained in 300 normal persons and over 400 patients. The amplitude of the ballistocardiogram is related to the cardiac output. Normal standards for cardiac output were defined by tests on 200 healthy persons from 20-84 yrs. of age. The form of the ballistocardiogram is detd. by the changes of systolic blood velocity in the great vessels. The normal form and common abnormalities were described, their physiological interpretations set forth, and their clinical significance discussed.