279 



To set the question quite at rest of the possibility of the blood in 

 a vessel raising the pitch, especially at so short a distance as 2| 

 inches, the following experiment was devised : A tourniquet was 

 placed over a man's femoral artery, immediately below Poupart's 

 ligament, and an artificial murmur thus produced ; this was found 

 to rise rapidly in pitch in passing down the course of the vessel. 

 A well-marked difference was noticed at a distance of only an inch, 

 and decidedly more at a distance of 2^ inches. 



The intensity of the murmur quickly diminished in passing 

 to the right or left of the vessel, the pitch being at the same time 

 rapidly raised, which was due to the interposition of integuments ; 

 but this interposition could not be the cause of the rise of the pitch 

 in the course of the vessel, as the murmur could be heard in that 

 direction at a distance of at least 6 inches, whilst it was completely 

 lost at less distance than 2 inches to either side of the vessel ; thus 

 the murmur must have been conducted by the blood, whilst the same 

 thickness of integuments was over the artery at the lower and 

 the upper point listened to, for both points were above the place 

 where the sartorius muscle crosses the vessel. 



GASES. 



If a watch is pressed close to the ear and then gradually moved 

 away, the tick is heard to rise in pitch in proportion to the distance 

 the watch is withdrawn. 



*Or, if in place of the watch a tuning-fork be used, the same can 



be still more distinctly ascertained. Then let the fork, either freely 



. vibrating, or, still better, placed on a resounding board, be moved 



gradually away from the ear, the pitch will be found to rise the 



further the fork is carried away from the ear. 



An echo of a musical note is higher pitched than the original note. 

 Again, a loud cardiac murmur audible over the entire chest was 

 examined in the following manner: 



The patient was directed first to exspire to the utmost, and the 

 pitch of the heart-sound was then ascertained ; he was then ordered 

 to inspire to the full ; the pitch was then found to be raised. In 

 this experiment, the only variation was an increased amount of air 

 between the point where the murmur was generated, and the ear of 

 the observer. 



