Since 1923, all determinations of the basal metabolic rate conducted in the Battle Creek Sanitarium Clinic have been made by the graphic method. These graphs form the subject of our present study. We have chosen to call them spirograms to differentiate them from the numerous other types of graphs used in medicine.
While a casual observation of these tracings gives the impression that every conceivable irregularity may be obtained, a closer inspection reveals that there is a certain order in the apparent chaos. One of us (P. R.) first noted that the spirograms could be divided into about ten types, each with definite characteristics. For the past four years all spirograms have thus been read and classified on a purely graphic basis by one technician. We take pains to state that the reader of the spirograms had not the slightest idea whether they had any clinical significance, but was interested