dudgeon's and ludwig's sphygmographs. 



99 



artery by means of the milled head, L. This must be determined for each pulse, but the rule is 

 to graduate the pressure until the greatest amplitude of movement of the lever is obtained. 

 Set the clock-work going, and a tracing is obtained, which must be " fixed " by dipping it in 

 a rapidly drying varnish, e.g., photographic. In every case scratch on the tracing with a needle 

 the name, date, and amount of pressure employed.] 



[(5) Dudgeon's Sphygmograph. This is a convenient form of sphygmograph, although 

 Broadbent regards its results as untrustworthy. The instrument after being carefully adjusted 



Fig. 74. 

 Ludwig's sphygmograph. 



upon the radial artery is kept in position by an inelastic strap. The pressure of the spring is 

 regulated by the eccentric wheel to any amount from 1 to 5 ounces. As in other instruments 



Fig. 75. 

 Dudgeon's sphygmograph. 



the tracing paper is moved in front of the writing- needle by means of clock-work. The writing- 

 levers are so adjusted that the movements of the artery are magnified fifty times (fig. 75).] 



(6) [Ludwig's improved form is a very serviceable instrument (fig. 74).] 



(7) Marey's tambours are also employed for registering the movements of the pulse. They 

 are used in the same way as the pansphygmograph. Two pairs of metallic cups (fig. 76, S, S, 



