CIRCULATION OF THE BLOOD. 



blood pressure in the same way that was done in the case of the 

 rabbit. 



The Riva-Rocci sphygmomanometer or some modification of it 

 is in most general use, and, although not the most accurate form of 

 apparatus, perhaps, for the purpose, it certainly is most convenient. 



The apparatus consists of an elastic tube, blind at both ends and 

 having a side piece for connection with the air-inflating pump (see 

 Fig. 35). This tube is covered by a leather cuff, so that when it is 



FIG. 35. Sphygmomanometer (Schematic). (Description in text.) 



adjusted around the arm or forearm the pressure is exerted in the 

 direction of the limb (see Fig. 35, A and C). The arm tube is con- 

 nected with some form of air pump (Fig. 35, P) and with a mercury 

 manometer (Fig. 35, B). By inflating the tube until sufficient 

 pressure upon the arm is produced to shut off the pulse at the wrist, 

 a rough estimate of the systolic blood pressure is obtained. This 



["9] 



