VELOCITY or 1 THE PULSE-WAVE IN MAN. 



155 



of the lower extremities than in those of the upper limb. For the same 

 reason it is less in the peripheral arteries and in the yielding arteries 

 of children (Czermak). 



E. H. Weber estimated the velocity at 9 '24 metres per sec.; Garrocl, 9 -10 '8 

 metres; Grashey, 8' 5 metres; Moens, 8" 3 metres, and with diminished pressure 

 during Valsalva's experiment (p. 112) 7'3 metres. 



In animals, haemorrhage (Haller), slowing of the heart produced by stimulation 

 of the vagus (Moens), section of the spinal cord, deep morphia-narcosis, and dilata- 

 tion of blood-vessels by heat, produce slowing of the velocity, while stimulation of 

 the spinal cord accelerates it (Grimm ach). 



The wave-length of the pulse-wave is obtained by multiplying the 

 duration of the inflow of blood into the aorta=0'OS to 0'09 sees. 

 (p. 86) by the velocity of the pulse-wave. 



Method. Place the knobs of two tambours (Fig. 52) upon the two arteries to 

 be investigated, or place one over the apex-beat and the other upon an artery. 

 These receiving tambours are connected with two registering tambours, as in 

 Brondgeest's pansphygmograph ( 67, Fig. 52) so that their writing-levers are 

 directly over each other, and so arranged as to write simultaneously on one vibrating- 

 plate attached to a tuning-fork. [Or they may be made to write upon a revolving 

 cylinder, whose rate of movement is ascertained by causing a tuning-fork of a 

 known rate of vibration to write under them.] In Fig. 68, H is the curve obtained 

 from the heart, and C from the radial artery. The apparatus is improved by using 

 rigid tubes and filling them with water, in which all impulses are rapidly communi- 

 cated. In arteries which are distant from each other, or in the case of the heart 

 and an artery, the two knobs of the receiving tambours may be connected by means 

 of a Y-tube with one writing-lever. In Fig. 68, B is a curve from the radial artery 

 taken in this way. In it v H P indicates contraction of the ventricle ; H, the 

 apex of the ventricular contraction ; P, the primary apex of the radial curve ; v, the 



H 



m 





B 



Fig. 68. 



A, curve of radial artery on a vibrating surface (1 vib. =0'01613 sec.) ; P, apex 

 of curve ; e, e, elastic vibrations ; B,, dicrotic wave ; B, curve of same radial 

 taken along with the heart-beat ; v, H, P, contraction of the ventricle ; H, 

 curve of the heart-beat ; C, of the radial artery, taken simultaneously. The 

 arrows indicate the identical points in both curves. In B, v to p = 9 vibrations. 



