34 MUTUAL RELATIONS OF THE APEX CARDIOGRAPH


is calculated from the formula #z = 39 /z. The chief source of error
in these observations is the slight uncertainty in the rate of movement:
of the watchwork of the instrument, on which the calculation of the
rapidity of the pulse depended. a

On comparing this equation, namely wz = 39,/2, with the one
above referred to as to the relations of the first cardiac interval, namely,
ay = 20/z, it is evident that the length of the first cardio-arterial
interval is ‘5128, or just over half that of the first cardiac interval,
whatever the rate of the pulse. :

This being the case, a more precise method is acquired of verifying
the results arrived at; for by finding the number of times that the first
cardio-arterial interval is contained inthe first cardiac interval, a
constant quantity ought to be the result, which is independent of the
rapidity of the pulse. Table II contains these measurements; and it
may be seen that, though there is a small range of variation, the num-
bers are all very near to the theoretical requirement, which is 1:95;
and their average is 1°983.
Tas.e II. {
Sak cesta 2 Number of times
ii that the first ae that the first
Rapidity | cardio-arterial | P®PIdity | cardio-arterial
of interval of interval
is contained is contained
pulse. in the first car- pulse. in the first car-
diac interval. diac interval.
