This paper is based upon observations taken on patients at rarkside Mental Hospital, Macclesfield.

Martin's modification of a Riva-Rocci sphygmomanometer was used. The systolic pressure (S.P.) was taken at the point on the scale when the first audible click was heard through the stethoscope on decompression following obliteration of the left brachial artery, and the diastolic pressure (D.P.) at the point when the loud thuds suddenly became dull (the end of the third and beginning of the fourth phase).