1871.] 



and Radial Sphygmograph Trace. 



321 



then measured into its component beat in each pulsation of the trace, from 

 which the average of the observation was obtained. The results are given 

 in Table I. Column II. ; and in Column III. some of these are expressed 

 in parts of a minute, whereby a better idea can be obtained as to their 

 significance. 



Table I. 



I. 



II. 



III. 



IV. 







1 



1 



X. 







z. 



xz' 



39 sjx 



58 



5-2 



— 



•003316 



— 



•0033649 



64 



5-083 







70 



474 







71 



4-52 







74 



4-50625 



•00299 



•00298 



79 



4-3127 







80 



4-4437 







81-5 



4-1125 







85 



4-355 







86 



4-2 



•002768 



•002802 



97 



4-17 







102 



3-885 



•002524 



•002538 



132 



3-41 



•002222 



•002229 



154 



3- 







170 



2-95 



•00197 



•001957 



From these results it is seen that the first cardio-arterial interval is 

 longer in slow than in quick pulses, and that it does not increase as quickly 

 as the pulse diminishes in rapidity ; but that the statement that it varies 

 inversely as the square root of the rapidity is correct, or very nearly so, is 

 rendered evident by comparing Columns III. and IV., in the latter of 

 which the duration of the first cardio-arterial interval is calculated from 

 the formula ##=39 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. 



' On comparing this equation, namely xz=39*/x, with the one above 

 referred to as to the relations of the first cardiac interval, namely 

 xy—20s/x, 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 in the first cardiac interval, a constant 

 quantity ought to be the result, which is independent of the rapidity of 



