366 



CIRCULATION 



augmented, and therefore there is a heaping up of the fluid in the 

 earher tubes 1, 2 and 3, a rapid fall to tube 4, and thereafter a 

 fall of pressure at the same rate as in the earlier part of the system. 

 All the above is stated in terms of pressure. Putting the same 

 matter in terms of velocity of flow, one may say that if a tube be 

 used, the second segment of which is wider than the first and 

 third, the speed of flow will be decreased in the central one. 



Pressure by Force-Pump. In the preceding experiment, the 



A 



RUBBER 



COMt 



1 COMPRESSION CHAMBER j 



MEAN AORTIC 

 PR£55UR£-I05MH5. 



KtflN BRACHML 

 rR£55UR£ -90 HM5. 



Fig. 88. — Diagram of a simple force pump (outer circuit) to compare witli diagram of 

 circulation from left side of lieart (inner circuit). 



head pressure has always been kept constant by making provision 

 for a steady influx of water to the reservoir to compensate for the 

 outflow. If, however, the head of pressure is produced by the 

 action of a piston in a cylinder, it will not cause a continuous but 

 an intermittent flow in the main conduit. The pressures shown in 

 the piezometers will vary from a maximum to a minimum as the 

 wave of pressure passes down the system after each stroke. Such 

 conditions entail great loss of power. 



Elastic Regulator. In order to reduce this loss to a minimum, 



