ON THE SPHYGMOGRAPH TRACE. 17 
and therefore the first part = 34; — zis PS in a pulse of 
that rapidity zy was found = 242°9. 
To save the trouble of extracting the cube root for any rapidity, 
these facts have been thrown into a co-ordinate form in the accom- 
panying table, and the observations on which the formula is based are 
represented by dots on their proper co-ordinates, the calculated curve, 
with k = 47, being represented by a continuous line. 
_ Since the above equation was worked out, a great many other 
observations have been made, several of which are recorded on the Page 354. 
table, and in health no cases have been found which depart from the 
curve more than those indicated on it. 
The observations made on the author are represented by simple 
black dots, those made on others are encircled by a ring; great size of 
a dot indicates that more than one independent observation has pro- 
duced exactly similar results. 
‘In none of the cases have measurements been made after violent 
exercise. Differences in the height and age of the subjects experi- 
mented on have not been found to produee any appreciable effect. 
The trace from infants has not been examined. 
- From the equation zy = */z.k the length of the second paki of the 
pulse trace may be represented in terms of 2, as htop t as 
from the nature of y it cannot be less than unity (no pulse having 
been seen with two contractions or more between two successive 
closures of the aortic valve), the limit of cardiac rapidity may be de- 
duced to be 322 in a minute (k = 47); but itis scarcely probable that 
pulses of such a rate could remain so sufficiently long te be counted. — 
Tn many cases of disease implicating the circulatory system, the 
equation given above indicates that the duration of the first part of the 
heart’s action is not normal; thus, in a boy suffering from typhoid 
fever, on the second day after the pyrexia had ceased, and when the 
temperature was below the normal, zy was found = 225-25, where 
-# = 60, which differs from the equation 
8/67 x 47 = 190°82, 
which shows that the length of the first part is considerably too short 
in the former. In the same case, three days later, the patient rapidly 
improving, with z = 56°5, 
vy = 188, 
which is much nearer the calculated normal result, 180°5, than on 
. the former occasion, the trace keeping pace with the other physical 
_ changes. 
It is probable that many other imperfections in the circulatory 
system can be similarly indicated, and it has been shown above with 
what facility a diagnosis may be arrived at. 
T wae 
c 
