1871.] 



and Radial Sphygmo graph Trace. 



323 



valve closes, the shock wave indicates itself by an abrupt but not con- 

 siderable rise, breaking the very gradual major descent. 



This explanation being correct, another means is obtained of checking 

 the results arrived at by the combined instrument ; and Table III. 

 Column II. contains a few measurements of the number of times that the 

 conjugate arterial interval is contained in the first arterial interval, as found 

 by measuring the ratio of the interval between the commencing arterial 

 rise and the bottom of the notch in the major fall to the whole first arterial 

 interval. Column III. gives the theoretical results necessitated by the 

 equations given above. 



Table III. 



Rapidity 

 of 

 pulse. 



Number of times the con- 

 jugate cardio-arterial in- 

 terval is contained in the 

 first arterial interval, 



as found 



from 

 measurement 

 of radial 



trace. 



as calculated 

 (approxi- 

 mately). 



37 



1-595 



1-6 



45 



1-635 



1-625 



58 



1-69 





59 



1-7083 



1-72 



60 



1-74 



1-734 



68 



1-797 



1-78 



It may be mentioned that the reason why so few of these instances are 

 given, is that there is considerable difficulty in measuring these small 

 intervals into one another with precision ; but by practice a very fair esti- 

 mate can be made of their value, and in all cases they seem to agree with 

 theoretical requirement. The close accordance of the results obtained by 

 this method in very slow pulses, and the calculated results arrived at from 

 facts relating only to quicker ones, tends strongly to establish the correct- 

 ness of the law given with regard to them. 



In Table IV. the lengths, in parts of a minute, of the different intervals 

 referred to in this communication, are given as calculated from the 

 equations on which they have been shown to depend. With regard to the 

 second cardio-arterial interval, a reference to Column VII. will show that 

 it varies very slightly within the range of the heart's action, not being 

 -J longer in a pulse of 36 than in a pulse of 169 in a minute. 



