234 EXPERIMENTAL PHYSIOLOGY. 



Mode of Application. (a.) Cause the patient to seat 

 himself beside a low table, and place his fore-arm on the 

 double-inclined plane (Fig. 108), which, in the improved 



c' 



Fig. 108. Marey's Sphygmograph applied to the Arm. 



form of the instrument, is the lid of the box so made as to 

 form this plane. The fingers are to be seminexed, 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 pencil. See that the clock (H) is wound up, and 

 apply the ivory pad of the instrument 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 sphygmograph 

 must be parallel to the radius, and the clock-work must be 

 next the elbow. Cover the slide with enamelled paper, 

 smoke it, fix it in position, and arrange the writing-style 

 (C') so as to write upon the smoked surface (G) with 

 the least possible friction. Regulate the pressure upon 

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

 greatest amplitude of movement of the lever is obtained. 



(c.) Set the clock-work going, and take a tracing. Fix it, 

 scratch on the name, date, and pressure. 



3. Dudgeon's Sphygmograph (Fig. 109). 



(a.) Adjust the instrument on the radial artery by means 



