204 CIRCULATION. 



studying these phenomena, to take the systole as a point of 

 departure, instead of the action of the auricles, which we 

 cannot appreciate without vivisections ; and the sounds, 

 which are two in number, have been called first and second, 

 with reference to the systole. 



The first sound is absolutely synchronous with the apex 

 beat. The second sound follows the first without any appre- 

 ciable interval. Between the second and first sounds there 

 is an interval of silence. 



Some writers have attempted to represent the sounds of 

 the heart, and their relations to each other, by certain sylla- 

 bles, as, " lubb-dup or lubb-tub /" 1 but it seems unnecessary to 

 attempt to make a comparison, which can only be appre- 

 ciated by one who is practically acquainted with the heart- 

 sounds, when the sounds themselves can be so easily studied. 



Both sounds are generally heard with distinctness over 

 any part of the prsecordia. The first sound is heard with its 

 maximum of intensity over the body of the heart, a little 

 below and within the nipple, between the fourth and fifth 

 ribs, and is propagated with greatest facility downwards, 

 towards the apex. The second sound is heard with its max- 

 imum of intensity at the base of the heart, between the nipple 

 and the sternum, about the locality of the third rib, and is 

 propagated upwards, along the course of the great vessels. 



The rhythm of the sounds bears a certain relation to the 

 rhythm of the heart's action, w T hich we have already dis- 

 cussed ; the difference being, that we here regard the heart's 

 action as commencing with the systole of the ventricles, while 

 in following the action of different parts of the organ, we 

 followed the course of the blood, and commenced with the 

 systole of the auricles. Laennec, the father of auscultation, 

 was the first to direct special attention to the rhythm of these 

 sounds, though they had been recognized by Harvey, who 

 compared them to the sounds made by the passage of fluids 



1 C. J. B. WILLIAMS, in Dunglison's Human Physiology. Philadelphia, 1856, 

 rol. i., p. 398. 



