BLOOD FLOW IN MAN. 217 



curve so as to synchronize accurately the various cardiac events 

 represented in the three tracings. 



4. Determine in millivolts the manifest value of the potential 

 change occurring during the production of the R wave in lead III. 



5. Determine the direction of the electrical axis during the 

 production of the R wave. 



6. Draw a diagram showing the course of the cardiac action 

 current and the movement of the string during the production of the 

 P wave. 



