Seventy years elapsed between the description by Gordon1 of a method for graphically recording the motion of the body with each heart beat and Starr's Harvey Lecture2 reporting how such curves could be used in routine clinical diagnosis. Most ballistocardiographs are bulky; the latest model to be described weighs over a ton without the recording mechanism.3 However, since 1949 there have been available three systems for recording the body's motion with very simple attachments to any type of electrocardiograph,4 and routine use by practitioners, industrial medical and insurance examiners has become a reality. Physicians not only use the ballistocardiograph on patients, but have it used on themselves as they enter the "coronary age." It therefore is desirable to put before them a brief description of this simple diagnostic method.
When the body lies on a smooth solid surface, it moves with each respiratory and each cardiac