DUDGEON'S SPHYGMOGRAPH 



167 



Fig. 131 gives two sphygmograms obtained by this instrument. 

 Tracing i is from a rather low-tension pulse, and tracing n from a 

 high-tension pulse. The dicrotic notch is much more conspicuous in 

 tracing i than in tracing n. In n the pre- and post-dicrotic waves 

 are much better marked than in the low-tension pulse. Note further 



Fig. 131. — Two Sphygmograms Taken by a Dudgeon's Sphygmograph. 

 Tracing i from a Low-tension, ii from a High-tension Pulse. 



the difference in excursion between the two and the difference in 

 rate of beat. The clock is so set that it carries the paper through in 

 exactly ten seconds, so that if the total number of waves recorded on 

 the paper be multiplied by 6 the rate of beat per minute is at once 

 given. 



