( 94) 



interesting it seemed to us. since for the present our time was taken 

 up by other work. 



A couple of months afterwards Dr. A. G. Gibson of Oxford — 

 to whom our former publications on the recording of heart sounds were 

 known, but who could not be acquainted with our later observations 

 — asked whether in our collection of cardiophonograms of normal 

 persons there were any in which an extra sound was visible in the 

 diastolic phase. Gibson occupied himself with an investigation of the 

 venous pulse ') and had noticed that with some persons, without a 

 morbid affection of the heart, a low pitched sound could be heard 

 at the apex during the cardiac pause, something like a distant 2 nd 

 sound, but feebler and much lower in pitch. The sound is clear and 

 nothing like a murmur. This particular sound is of varying intensity 

 being louder during the interval between the end of an expiration 

 and the beginning of the subsequent inspiration. 



We hope elsewhere to publish in a more extensive paper the 

 cardiophonograms we obtained; here we shall only deal briefly with 

 them. When we try to predict from the shape and dimensions of 

 the curves what impression the third heart sound must make on the 

 ear of the observer, we cannot describe it otherwise than Gibson 

 did : a distant diastolic sound of low pitch and clear tone, varying 

 in intensity, but always feeble. 



There can be no doubt that the sound, heard by Gibson at Oxford, 

 is the same sound we recorded at Ley den. 



The measurements made with some cardiophonograms, show that 

 with Wi the beginning of the third sound falls on the average 

 0.13 sec. (varying between 0.11 and 0.15 sec.) after the beginning 

 of the second sound and on the average 0.32 sec. before the beginning 

 of the following first sound. In the same curves the duration of 

 the first sound is about 0.08 sec, of the second about 0.05 sec, of 

 the third 0.02 to 0.03 sec The first two sounds are murmurs, com- 

 posed of tones of irregular pitch. The mutual distance of some tops 

 in the curves shows that we have here tones of more than a hundred 

 double vibrations per second, whereas the third sound seems to be 

 built up of but one double vibration, the period of which amounts 

 to about 0.02 sec. 



The intensity of the third sound varies. While in some cardiac 

 beats it is entirely absent, the amplitude of its vibrations reaches in 

 other beats 1/7 of that of the first and second sounds. Putting the 



') Gibson's investigation will shortly be published in "The Lancet" under the 

 title : 'The significance of a hitherto undescribed wave in the jugular pulse". 



