198 THE POPULAR SCIENCE MONTHLY. 



chest-walls, render a study of the condition of the heart entirely prac- 

 ticable by stethoscopic auscultation. By this method its size, its loca- 

 tion, and the state of each of its valves can be learned with much pre- 

 cision. 



The heart-sounds are sufficiently loud and distinct to be suscepti- 

 ble of much exactitude of description and characterization. The con- 

 traction of the ventricles, which mainly produces the " first sound," is 

 the exertion of a force equal to the grasp of a strong hand ; it is forci- 

 ble and quick, but its time as represented by its sound is measurable. 

 This sound is composed of two elements — one of propulsion, with a 

 "booming" quality which is the characteristic, and one of valvular, 

 or sudden clicking sound. Its rhythm, as observed in its succession, 

 is trochaic. 



The " second sound " is principally caused by the sudden arrest by 

 the semi-lunar valves, of the column of blood in its tendency to return 

 to the heart under the elastic recoil of the arteries after their forcible 

 distention. It is quick and valvular ; it is higher in pitch than the 

 first sound and its rhythm is iambic. 



Each of these sounds is more or less ringing and clear and has its 

 appropriate timbre. 



After an almost imperceptible interval, the " first sound " is fol- 

 lowed by the " second," then by a rest ; the whole cycle occupying 

 about one second of time. Its divisions may be represented as fol- 

 lows : first sound, ^^ ; second sound, yV j ^*6St, -f-^. Each has its ex- 

 act normal place of greatest intensity and perfection, relative to the 

 external topography of the chest, and variations from this rule will be 

 an index of change of structure within the heart itself, or of displace- 

 ment from malformations or morbid conditions of the adjacent organs. 



It is convenient to designate as heart-sounds those sounds which 

 are normal, and as heart-murmurs those sounds which are adventitious 

 and, as a rule, indicative of organic changes. 



The murmurs are of peculiar character, of great variety, and usu- 

 ally of important significance. They originate either within the heart 

 (endocardial) from defective valves or obstructed orifices, or else 

 without it (exocardial) from friction against morbid accumulations 

 within its membranous envelope ; or, finally, though exceptionally, they 

 are found to depend upon certain conditions of the blood. 



The murmurs are very numerous and variable, and difficult of de- 

 scription according to any rules of rhythmics, melodies, or dynamics ; 

 as will be seen from the following names applied to them — and these 

 only a fraction of the whole list : sawing, rasping, scratching, scrap- 

 ing, grinding, creaking, rubbing, churning, blowing, whistling, cooing, 

 purring. And, as if from poverty of language, fashion or necessity has 

 led to borrowing from abroad ; as fr'emissement cataire, bruit de souffle, 

 bruit de scie, etc. The terms in use should through some convention- 

 ality be revised. Many of them, however, are practicably indispensa- 



