STETHOSCOPY. 



»93 



nating in a pen is so placed in contact with the membrane as to amplify 

 manifold in tracings the movement it receives. The inscription is 

 received on a slip of smoked glass, which is made to move before the 

 pen with precision by a mechanism which also acts as the chronograph, 

 indicating the time at the lower edge of the glass in seconds and 



Fia. 5.— Kbyt's Compound Sphtgmograph. 



fifths. A second pen with similar connection is made to trace on the 

 same slide the movement of another pulse at a distant part of the 

 system. 



Space will not permit of reference to the numerous and important 

 accessory contrivances of the complete instrument, nor to the numer- 

 ous indicatory marks on the following cuts. To the specialist they 

 are significant and essential. Simultaneous tracings of the heart and 

 a large blood-vessel of the neck are shown below (Fig. 6). It should 

 be explained that the upward stroke in the tracing answers to the 

 heart-beat ; the downward stroke and succeeding wavelets indicate 

 the recoil of the blood and the tension of the vessels ; while the whole 

 cycle with its chronometric line below furnishes a wonderful map. 



This graphic method includes cardiography, in which a tracing is 

 obtained of the pulsations of the heart, and pneumography, in which 

 are recorded the movements of respiration. It includes also the mul- 



VOL. XXV. — 13 



