120 



HAND-BOOK OF PHYSIOLOGY. 



The knob (A) is for application to the chest-wall over the place of the 

 greatest impulse of the heart. The box or tympanum communicates by 



means of an air-tight elastic tube (/) with the 

 interior of a second tympanum (Fig. 102, l>), in 

 connection with which is a long and light lever 

 (a). The shock of the heart's impulse being 

 communicated to the ivory knob, and through 

 it to the first tympanum, the effect is, of course, 

 at once transmitted by the column of air in 

 the elastic tube to the interior of the second 

 tympanum, also closed, and through the elastic 

 and movable lid of the latter to the lever, which 

 is placed in connection with a registering appa- 

 101. ratus, which consists generally of a cylinder or 



drum covered with smoked paper, revolving 



according to a definite velocity by clockwork. The point of the lever 



writes upon the paper, and a tracing of the heart's impulse is thus obtained. 



By placing three small india-rubber air -bags in the interior respec- 



FIG. 102. Marey 's Tambour ( b ), to which the movement of the column of air in the first tym- 

 panum is conducted by the tube,/, and from which it is communicated by the lever, o, to a revolving 

 cylinder, so that the tracing of the movement of the impulse beat is obtained. 



tively of the right auricle, the right ventricle, and in an intercostal space 

 in front of the heart of living animals (horse), and placing these bags, by 

 means of long narrow tubes, in communication with three levers, arranged 



FIG. 103. Tracing of the impulse of the heart of man. (Marey.) 



one over the other in connection with a registering apparatus (Fig. 104), 

 MM. Chauveau and Marey have been able to measure with much accuracy 

 the variations of the endocardial pressure and the comparative duration 



