292 



PRACTICAL PHYSIOLOGY. 



[LXI. 



made as to form this plane. The fingers are to be semiflexed, so 

 that the back of the wrist, resting on the plane, makes an angle 

 of about 30 with the dorsal surface of the hand. 



(b.) Mark the position of the radial artery with ink or an aniline 



c 1 



FIG. 214. Marey's Sphygmograph applied to the Arm. 



pencil. Wind up the clock (H), apply the ivory pad of the instru- 

 ment exactly over the radial artery where it lies on the radius, and 

 fix it to the arm by the non-elastic straps (K, K). The sphygmo- 

 graph must be parallel to the radius, and the clockwork next the 

 elbow. Cover the slide with enamelled paper, smoke it, fix it in 

 position, and arrange the writing-style (C') to write upon the 

 smoked surface (G) with the least possible friction. Regulate the 



FIG. 215. Tracing taken from the Radial Artery by means of Marey's Sphygmograph. 

 A. A hard, and B, a softer pulse. 



pressure upon the artery by means of the milled head (L), i.e., 

 until the greatest amplitude of the lever is obtained. 



(<-.) Set the clockwork going, and take a tracing. Fix it, write 

 the name, date, and pressure, and study the tracing (fig. 215). 



