84 



NATURE 



\May 2 2, 1879 



A SPHYGMOGRAPHIC EXPERIMENT 



AN experiment which I have recently been enabled to 

 make by means of the sphygmograph may perhaps 

 be of sufficient interest to deserve a brief record in your 

 columns. 



It occurred to me while preparing for the Croonian 

 lectures, which I had the honour of delivering before the 

 College of Physicians a few weeks back, that some light 

 might be thrown on the movement of the blood in the 

 vascular system, if an ordinary tracing of the healthy 



pulse were compared with one taken under different 

 circumstances, wherein a large portion of the arterio- 

 capillary network was thrown out of the circuit. By the 

 kind assistance of my colleagues. Dr. Sharkey, Mr. Pitts, 

 and Mr. Sandwith, I was able to put this hypothesis to 

 the test, the result being the four pairs of tracings accom- 

 panying this communication. The patient in the first case 

 (No. i) was Mr. Butler,apupil of the St. Thomas's Hospital, 

 and in the last three instances one of the porters in this 

 institution. The modus operandi was very simple. The 

 sphygmograph having been firmly applied to the left 



Mr. Butler, 

 sj oz,- 



Immediate, 

 4 02. 



After 10 beats, 



4J 01. ( 



After 30 beatSj 

 401. 



i 



In all the tracings the lower is the normal pulse, the upper one with vessels compressed. Nos. 2, 3, 4, from the same patient, Georg^e Watts, set 37. 



radial pulse, a series of tracings was made to ascer- 

 tain the pressure which produced the most characteristic 

 curve-line. This proved in Mr. Butler's case to be two 

 and a half, in that of the porter, four or four and a 

 half ounces. This adjustment having been obtained, a 

 normal tracing was taken on a broad slip of smoked plate 

 glass at its lower portion. The three gentlemen above- 

 named were instructed to compress simultaneously the 

 two femoral arteries and the right axillary. A second 

 tracing was then taken on the upper half of the same slip, 

 so that it could be accurately compared with that already 

 taken. Mr. Butler's pulse, even after it had been excited 



by the administration of a full dose of whisky (abouf 

 three ounces), was too quiet and undemonstrative to give 

 very striking results, though it will be seen that the 

 excursion is diminished, the rate is rendered perceptibly 

 slower in the ratio of six to seven, and the distinctive 

 aortic notch is obscured by a number of smaller undula- 

 tions. In the case of the porter we had to deal with an 

 older man, of very muscular build, with a strong bounding, 

 though not morbid pulse, who has been for some years in 

 a Guards regiment. The first pair of tracings (No. 2) 

 here showed a very important modification in the contour 

 of the undulation. To eliminate any error due to a 



