VELOCITY 



75 



a record must be made not only of the average rate of 

 flow but also of the fluctuations due to the heart-beat. One 

 of the simplest instruments for showing this is Chauveau's 

 haemadromograph, a diagram of which is given. 



The apparatus is shown in Fig. 17. The horizontal part of 

 the tube is inserted into the cut artery, c being attached to the 



pO 



n 



pi 



D' 



Fig. 17. — Chauveau's htcmadromograpli. (From Starling'ti Principles of 



Physiology. ) 



central and p to the peripheral end. Into the tube is suspended 

 the pendulum pi, the movements of which are transmitted to the 

 tambour k, and by this recorded on a blackened surface. The 

 instrument is first calibrated on a stream of known velocity. 



The capillary velocity can|^be measured microscopically 

 in thin tissues such as the frog's mesentery. 



