When this paper was submitted to the editors of CIRCULATION it called to their attention the desirability of enlarging the work that Dr. Braunstein has begun in the following paper. Accordingly, Dr. Howard Sprague, President of the American Heart Association appointed a committee to study the field and to make recommendations leading toward both a uniform terminology and uniform methods of presenting data secured by ballistocardiographs, and Dr. Braunstein kindly consented to withhold the publication of his paper until the committee was ready to report. This committee has now approved the terminology suggested by Dr. Braunstein and, in a first report, which immediately follows Dr. Braunstein's paper, makes other recommendations pertaining to terminology and conventions for parts of the field not covered by Dr. Braunstein's paper.