322 Mr. A. H. Garrod on the relation of the Cardiograph [Feb. 23, 



the pulse. Table II. contains these measurements ; and it may be seen 

 that, though there is a small range of variation, the numbers are all very- 

 near to the theoretical requirement, which is 1*95; and their average 

 is 1-983. 



Table II. 



Rapidity of 

 pulse. 



Number of times 

 that the first car- 

 dio-arterial inter- 

 val is contained 

 in the first car- 

 diac interval. 



Rapidity of 

 pulse. 



Number of times 

 that the first car- 

 dio-arterial inter- 

 val is contained 

 in the first car- 

 diac interval. 



58 



1 95 



81-5 



1-95 



64 



2- 



83 



2-1 



69 



1-9 



84 



2-1 



70 



1-9125 



85 



1-995 



71 



1-975 



85-5 



1-95 



72 



2-058 



86 



2- 



74 



1-975 



88-5 



2-05 



76 



1-98 



91 



2-15 



78 



1-9 



92 



1-85 



79 



1-925 



94 



1-95 



79-5 



1-9 



! 97 



2-15 



80 



1-95 



154 



I 



1-975 



It is generally known that in the sphygmograph traces of most slow 

 pulses there is a notch in the first arterial interval, immediately preceding 

 the major fall ; and one of the most marked results of the use of the 

 cardio-sphygmograph is the determination of the fact that the point of 

 closure of the aortic valve at the heart is always exactly synchronous with 

 the lowest part of this notch, or the point of abrupt change of direction 

 in the major fall of the sphygmograph trace. This leads to the almost 

 necessary conclusion that the subsequent slight rise or change in direction 

 of the trace is the result of the simultaneous movement of the whole 

 column of blood produced by the suddenness of the shock of closure of the 

 aortic valve, the secondary rise in the same trace being the more slowly 

 transmitted pressure wave resulting from the same cause. 



The slower the pulse the more distinct is this notch ; and by comparing 

 different rapidities, a gradual diminution in its conspicuousness is apparent, 

 it rising higher and higher above the point of termination of the major fall 

 as the pulse is quicker and quicker. When the heart's rate is about 75 in 

 a minute, the notch is halfway down the major descent, and is partially 

 blended with it ; when over 100 a minute, as the aortic valve closes when 

 the ascent is at its maximum, the notch is so blended with the pressure 

 wave as not to indicate itself separately. 



In slow pulses, the systolic main rise being quite over when the aortic 



