THE CARDIOGRAM. 



81 



air-tight manner over the apex-beat. The disc, p, capable of being regulated by the 

 screw, s, presses upon the region of the apex-beat, while t is a tube which may 

 be connected with a registering tambour (Fig. 28). B is an improved form of 

 the instrument, consisting essentially of a tambour, while attached to the mem- 

 brane is a button, p, to be applied over the apex-beat. The movements of the air 

 within the capsule are communicated by the tube, t, to a registering tambour. Fig. 

 25, C, is the pansphygmograph. of Brondgeest, which consists of a Marey's tam- 

 bour, in an iron horse-shoe frame, and adjustable by means of a screw, s. Burdon- 

 Sanderson's cardiograph is shown in D. The button, p, carried by the spring, e, 

 does not rest upon the caoutchouc membrane, but on an aluminium plate 

 attached to it. The apparatus is adjusted to the chest by three supports. 

 Fig. 25, E, shows a modified instrument on the same principle by Grunmach 

 and v. Knoll. In all these figures the t indicates the exit-tube communicating 

 with a registering tambour (Fig. 28). D and E may be used for other purposes, 

 e.y., for the pulse, so that they are polygraphs. See also Fig. 52.] 



Fig. 25. 



Various cardiographs A, original form as used by Marey; B, improved form by 

 Marey; C, Pansphygmograph of Brondgeest; D, Cardiograph of Burdon- 

 Sandersou ; E, that of Grunmach and v. Knoll. 



Fig. 25a, A, shows the cardiogram or the impulse-curve of the heart of 

 a healthy man ; B, that of a dog, obtained by means of a sphygmo- 

 graph. In both the following points are to be noticed a, &, corre- 

 sponds to the time of the pause and the contraction of the auricles. As 

 the atria contract in the direction of the axis of the heart from 

 the right and above towards the left and below, the apex of the 

 heart moves towards the intercostal space. The two or three smaller 



