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



Landois was unable to find any difference in the propagation-velocity whether 

 the waves were produced rapidly or slowly, or whether they were large or small. 



In order to determine whether the material of which the elastic tube is made 

 has any influence on the propagation- velocity of pulse- waves, Landois employed 

 a rather rigid, slightly distensible tube made of gray vulcanized rubber. It was 

 found that the propagation-velocity of the waves in this tube is greater than 

 in a softer and more distensible elastic tube. 



This observation is in accord with the fact that the intravascular pressure 



FIG. 60. Method of Recording the Pulse-curves Obtained from an Elastic Tube on a Tablet Attached to a Vibrat- 

 ing Tuning-fork. Each indentation is equivalent to 0.01613 second. 



exerts a demonstrable influence on the propagation- velocity of the pulse- waves; 

 for when the pressure was raised, the waves were propagated with a somewhat 

 diminished velocity. This phenomenon is due to the fact that the distensibility 

 of rubber tubes increases with the pressure, whereas in the arteries the distensibility 

 of the walls diminishes under the same conditions. 



The influence exerted by the specific gravity of the fluid was determined by 

 Landois for mercury, the waves of which move with about one-fourth the velocity 

 of waves produced in water. 



PROPAGATION- VELOCITY OF THE PULSE-WAVES IN MAN. 



Method of Examination. Landois attached to two different arteries long 

 levers consisting of reeds and so arranged that they both recorded their pulse- 

 curves simultaneously on the same recording surface attached to a vibrating tuning- 

 fork. A quick tap on the fork noted the identical moment on both curves, and 

 by counting the indentations from this point to the beginning of each curve the 

 difference in time was obtained. 



In this way Landois developed the following values from a student 174 cm. 



