AND RADIAL SPHYGMOGRAPH TRACE. 35 
taneous 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 com- 
paring 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 cluses 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 valve closes, the shock wave indicates itself by an abrupt but Page 323 
not considerable rise, breaking the very gradual major descent. 
This explanation being correct, another means is obtained of check- 
ing the results arrived at by the combined instrument; and Table III, 
Column IT, 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 commenc- 
ing 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. 
Taste III. 
Number of times 
the conjugate cardio-arterial 
interval is 
Rapidity contained ra the first 
of 
— as found 
from as calculated 
measurement (approxi- 
of mately). 
radial trace 
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 
D2 
