THE ARTERIAL PULSE 237 



mine the following: The character and rate of the outflow when water is 

 pumped into the rigid glass tube with no resistance to the outflow; when a 

 glass tube of smaller caliber is connected with the end of the larger glass 

 tube so as to produce, high resistance to the outflow. Pump the water into 

 a rubber tube of smalle^ ^ize and compare with the proceeding in which 

 there is no resistance to the outflow ; also when a glass tube of small caliber 

 is introduced into the end in order to produce high resistance to the outflow. 

 Determine the amount of resistance necessary to produce a constant out- 

 flow when the pump has a rate of 72 beats per minute. In this experiment 

 what effect is produced on the outflow if you vary the rate of the pump ? if 

 you vary the force of the stroke? if you vary the elasticity of the rubber 

 tube representing the artery? if you vary the resistance represented by the 

 size of the glass tube at the outflow ? 



15. The Arterial Pulse. The form of the arterial pulse may be 

 taken by one of the various sphygmographs applied to the radial 

 artery at the wrist or the common carotid in the neck. If the tambour 

 method is used, apply a sphygmograph tambour on the wrist with the central 

 pressure over the radial artery. Fasten it in place by the proper bands, 

 adjusting the tension by flexing the wrist. Connect the receiving tambour 

 with a delicately balanced, small-sized recording tambour, which should 

 write its movements on a cylinder revolving at the rate of i to 2 cm. 

 per second. 



A more convenient clinical instrument is the Dudgeon or the Jacquet 

 sphygmograph. These are to be applied at the wrist and give tracings 

 showing delicate variations in the form of the pulse wave with great magnifi- 

 cation and a considerable degree of accuracy. Make a comparison of the 

 form of the pulse wave from tracings taken from at least six different 

 individuals. 



The sphygmogram from the carotid artery may best be taken by apply- 

 ing a tambour sphygmograph to the neck over the carotid and fastening it 

 in position, usually by a spring. 



16. The Rate of Propagation of the Pulse Wave. Apply tambour 

 sphygmographs to the carotid in the neck and to the radial at the wrist, and 

 make simultaneous record on a recording drum, adjusting the writing levers 

 of the two recording tambours in an exact "vertical line. Let the recording 

 drum travel at the speed of 2 cm. or more per second, and record the speed 

 by a 50 double-vibration tuning-fork. The carotid pulse will be found to 

 precede the radial pulse by the fraction of a second. This short interval, 

 which can be determined in hundredths of a second by comparison with the 

 time tracing below, represents the time required for the pulse wave to travel 

 the distance from the carotid to the radial. Measure the distance on the 

 individual used in the experiment and calculate the rate of propagation of 

 the pulse wave in centimeters per second. 



