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Hand-sphygmoscopes placed upon the carotid, the brachial, the 

 radial, the femoral, and the dorsal artery of the foot, rise at the 

 same instant, and fall at the same point of time. 



These facts prove the existence of two great laws not previously 

 enunciated, 1st, that the heart's beat alternates with the pulse at 

 the wrist ; 2ndly, that the pulse of arteries beyond the chest takes 

 place in all parts at the same instant, and without any appreciable 

 interval. 



The pulse, it appears, occurs during the retirement of the heart 

 from the thoracic walls, and the collapse or fall of the arteries takes 

 place during the impulse of the heart. During the rise in the hand- 

 sphygmoscope placed over the arteries, the second sound of the 

 heart has been distinctly heard, and during the fall, the first, softer 

 and more prolonged sound has been easily distinguished. 



The horse has been subjected to examination, to learn the relative 

 time of the beat of the heart and arteries, but the respiratory move- 

 ments and the motions of the animal have hitherto restricted the 

 application of the instruments. However, it has been most distinctly 

 ascertained, by the hand placed upon the heart and upon the plantar 

 artery, that between the beat of these parts there is a decided inter- 

 val. The slowness of the action of the heart in the horse renders 

 this experiment less open to error than in man. In these experi- 

 ments upon the horse, Mr. Mavor, the eminent veterinarian, gave his 

 valuable aid. 



The sphygmoscope forms a good pneumoscope. It delicately 

 measures the rise and fall of the chest in respiration. It likewise 

 declares the relative duration of inspiration and expiration, and may 

 thus prove useful in the detection of incipient phthisis, and other 

 pulmonary diseases. "When the liquid has attained its highest eleva- 

 tion at the end of inspiration, it immediately begins to fall ; but when 

 it has reached the lowest point at the end of expiration, it remains 

 there some instants. The ascent is slower than the descent. After the 

 fall of an ordinary expiration, a forced expiration gives a second fall. 



The sphygmoscope may be employed without a stand and is then 

 more portable (fig. 3), but from the want of a fixed basis, and 

 from the motion of the ribs on which it must rest, its manifesta- 

 tions are less extensive and satisfactory. It may be maintained in 

 situ with an elastic band placed around the thorax. When em- 



