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is appreciably affected by the regurgitant wave in the jugu- Fi g- 2 

 lar veins, and by the wave in arteries greatly smaller than 

 the radial. From its nicety in manifesting the beat of the 

 blood-wave, it is very valuable, and is called the hand- 

 sphygmoscope. 



By means of this hand instrument applied to the arteries, 

 a comparison is readily made between the time of the beat 

 of the heart and the rise of the arteries under the influence 

 of the blood-wave. This instrument is much more delicate 

 than the finger in such an inquiry. The impressions made 

 upon the fingers of two hands fail to be conveyed with suf- 

 ficient nicety to the mind to tell with certainty the relative 

 time flf the beat of the heart and arteries. Except in cases of 

 extreme slowness, the sensations obtained from the two 

 hands impressed at nearly the same time, do not admit of 

 a distinct difference in respect to time being made out. It sphygmo- 

 has been to this very defect that the erroneous idea, that sc P e - 

 the beat of the heart and the beat of the pulse are synchronous, 

 or nearly so, has owed its origin and continuance. 



The hand-sphygmoscope, placed upon the radial artery, shows a 

 rise of the liquid while there is a fall in the sphygmoscope placed 

 over the heart. As the liquid in the one instrument starts from 

 below, the liquid in the other starts from above, and as the liquid 

 in the one reaches the top of its ascent, the liquid in the other 

 reaches the bottom of its descent, to renew their opposing course. 

 The movements in the two instruments at the same instant are always 

 opposed, and the whole time occupied in the movement of one in- 

 strument in one direction appears to be occupied by the movement 

 of the other in the opposite direction. The movements alternate 

 with as much apparent exactitude as the arms of a well-adjusted 

 balance. When the lapse of time between the beat of the heart and 

 the pulse at the wrist was first observed, suspicion of disease of the 

 aorta was entertained, but the subsequent examination of many 

 persons proved that this alternation was natural. In some twenty 

 persons subjected to examination, the complete alternation has been 

 made out without the shadow of a doubt. These persons were of all 

 ages above childhood, and had the pulse of different degrees of rapidity 

 from 60 to 100. 



