ELEMENTARY EXPERIMENTAL PHYSIOLOGY 59 



tension of the spring by means of the eccentric till the largest range 

 of movement of the lever is secured, (viii) Slip the smoked paper 

 under the wheels and under the point of the lever, using a pin to 

 raise the point of the latter if necessary, (ix) Now start the clock- 

 work and run off a tracing, (x) Mark upon it the name and age 

 of the subject, the date and the rate of the heart per minute, and 



FIG. 56. Sphygmograph provided with time writer (Jacquet) 



fix it. Copy it carefully, and try to explain the various elevations 

 and depressions with reference to the events in the cardiac cycle 

 as shown by the cardiograph (p. 55). 

 (Read the Arterial Pulse in a Text Book.) 



III. Blood Pressure in Man 



Make an observation of the arterial blood pressure of a companion 

 by the Riva Rocci Instrument. 



