PROPAGATION-VELOCITY OF THE PULSE-WAVES IN MAN. 155 



in height: The difference between the carotid and the radial was 0.074 second 

 (the distance being estimated as 62 cm.) ; between the carotid and the femoral, 

 0.068 second; between the femoral (at the fold of the groin) and the posterior 

 tibial, 0.097 second (the estimated distance being 91 cm.). 



Results.' The foregoing observations yield a propagation-velocity for the 

 pulse- waves in the distribution of the arteries of the upper extremities of 8.43 

 meters in i second, and for the arteries of the lower extremities 9.40 meters in i 

 second. 



It appears that in the less distensible arteries of the lower extremities the 

 propagation-velocity is greater for the same distance than in the arteries of the 

 upper extremities. For the same reason it is less in the peripheral arteries and 

 in the more yielding arteries of the child. 



Modifying Influences. Increase in blood-pressure accelerates, reduction in 

 blood-pressure diminishes, the propagation-velocity of the pulse-wave. Hence, in 

 animals, hemorrhage, slowing of the heart-beat through stimulation of the vagus, 

 division of the spinal cord, dilatation of the vessels (by heat, profound morphin- 

 narcosis or amyl nitrite) cause retardation; while, on the other hand, irritation of 

 the spinal cord causes an acceleration in the movement of the pulse-wave. 



The length of the pulse-waves is found by multiplying the time occupied by 

 the entrance of the blood into the aorta, which is from 0.08 to 0.09 second, by 

 the propagation- velocity of the pulse-waves. 



A more convenient method is to apply the two tambours of Brondgeest's pan- 

 sphygmograph (Fig. 44) to the two points on the artery to be examined and 

 have one writing-lever record its tracing above that of the other on a plate at- 

 tached to a tuning-fork. The method may be made quite trustworthy by con- 

 structing both apparatus with leaden pipes and filling these with water, in which 

 the propagation of the pulse-wave is quite uniform. A short tap on the tuning- 

 fork (at points indicated by the arrows in Fig. 61) marks the identical instant 



FIG. 61. Tracings from the Carotid and Posterior Tibial Arteries, Made Simultaneously with Brondgeest's Pan- 

 sphygmograph on a Tablet Attached to a Vibrating Tuning-fork. The arrows indicate identical moments. 



in the two curves. The difference in time is determined by simply counting the 

 vibrations. Fig. 61 shows the curves from the carotid and the posterior tibial 

 taken at the same time from a tall healthy student. The time-difference is 0.137 

 second. 



If the arteries are widely separated or if the observation is made on the heart 

 and on an artery, it is possible to connect the two pads by means of a forked 

 tube with a single writing-lever, and the two pulse-curves, when traced one into 

 the other, can be recognized in the sphygmogram. 



In Fig. 62, A is the curve of the ulnar artery, B the same, together with the 

 curve produced by the contraction of the ventricle v H p running through it, and 

 obtained by means of a forked tube. In the curve B, H indicates the apex of the 

 ventricular contraction, P the primary pulse-apex of the ulnar curve; v indicates 

 the beginning of the ventricular contraction, p that of the ulnar pulse. t appears 

 from these curves that the interval between the beginning of the ventricular con- 

 traction and the beginning of the pulse in the ulnar artery, in the individual 

 examined, was equivalent to 9 vibrations =0.15 second. 



Grashey applied two sphygmographs to two different arteries and caused the 

 writing-levers to strike sparks into their respective curves from a spark-inductor, 

 so that the sparks marked the identical instant of time in each curve. 

 way he determined the propagation-velocity (from the difference between the 

 radial pulse and that of the dorsalis pedis) to be 8.5 meters in i second. 



Pathological. In cases presenting diminished elasticity of the arteries, as, for 



