PULSE-TKACIXGS. 



147 



back to its original position. For ordinary purposes, the 

 instrument is bound on the wrist (fig. 43). 



It is evident that the beating of the pulse with the 

 reaction of the spring will cause an up-and-down move- 

 ment of the lever, and if the extremity of the latter be 

 inked, it will write the effect on the card, which is made 

 to move by clockwork in the direction of the arrow. Thu^ 

 a tracing of the pulse is obtained, and in this way much 

 more delicate effects can be seen, than can be felt on the 

 application of the finger. 



Fig. 44 represents a healthy pulse-tracing of the radial 

 artery, but somewhat deficient in tone. On examination, 

 we see that the up-stroke which represents the beat of the 

 pulse is a nearly vertical line, while the down-stroke is 



Flrf. 44-* 



very blunting, and interrupted by a slight re-asceut. The 

 more vigorous the pulse, if it be healthy, the less is this 

 re-ascent, and vice versa. Fig. 45 represents the tracing 



* Fig. 44. Pulse-tracing of radial artery, somewhat deficient in tone. 

 f Fig. 45. Firm and long pulse of vigorous health. 

 + Fig. 46. Pulse-tracing of radial artery, with double apex. 

 The above tracings are taken from Dr. Sanderson's work " On the 

 Sphygmograph. " 



L 2 



