158 VIBRATIONS COMMUNICATED TO THE BODY BY THE HEART. 



person be placed in an erect attitude in the scale of a large balance, the index 

 oscillates, and its movements coincide with the heart's movements. 



Fig. 70, I, shows a curve obtained by Gordon, written directly by the index of 

 the spring balance. The lowest part of the curve corresponds to the systole of the 

 ventricle. 



Landois employed the following arrangement : Take a long four-sided box, K, 

 open at the top, and arrange several coils, a, b, of stout caoutchouc tubing round 

 one end. A wooden board, B, smaller than the opening in the box, is so placed 

 that it rests with one end on the caoutchouc tubing, and with the other on the 

 narrow end of the box. The person to be experimented upon, A, stands vertically 

 and firmly on this board. A receiving tambour, p, is placed against the surface 

 of the board next the elastic tube, which registers the vibrations of the foot 

 support. Fig. Ill is a curve showing such vibrations, each heart-beat being followed 

 in this case by four oscillations. It corresponds to I. To ascertain the relations 

 and causes of these vibrations, it is necessary to obtain, simultaneously, a tracing 

 of the heart and the vibratory curve. For this purpose use the two tambours of 

 Brondgeest's pansphygmograph (p. 71), placing one nob or pad over the heart, 

 and the other on the foot-support, and allow the writing-tambours to inscribe their 

 vibrations on a glass-plate attached to a tuning-fork. 



In the lower or cardiac impulse curve, Fig. 71, the rapidly-rising part is due to 

 the ventricular systole. It contains S vibrations (1 vib. =0'01G13 sec.). The 

 beginning of the ventricular systole is indicated in the fig. by - 36 - 3 - 17. 



If the corresponding numbers in the upper or vibratory curve are studied, it is 

 obvious that at the moment of ventricular systole the body males a downward vibration, 

 i.e., it exercises greater pressure upon the foot - support. Gordon interprets his 

 curve as giving exactly the opposite result. This downward motion, however, 

 lasted only during 5 vibrations of the tuning-fork : during the last 3 vibrations, 

 corresponding to the systole, there is an ascent of the body corresponding to a less 

 pressure upon the foot-plate. When the ventricle empties itself, it imdergoes a 

 movement in a downward and outward direction Gutbroclt's "reaction impulse." 



Fig. 71. 



The upper curve is the vibration-curve of a healthy person, and the lower one a 



tracing of the apex beat. 



In the upper curve analogous numbers are employed to indicate the vibrations 

 occurring simultaneously, viz., -28- 11 -10. The closure of the semi-lunar 



