Page 150. 
88 ON POINTS CONNECTED WITH THE 
which gives an average length of ‘0012314 of a minute for all the 
rates. 
It being possible to estimate with considerable accuracy the dis- 
tance from the aortic valves of the spots on the arteries at which the 
instrument is usually applied, it becomes a point of interest to deter- - 
mine from the facts arrived at the rapidity with which the primary 
undulation travels from “its origin (the heart) to the peripheral 
vessels. The radial artery at the wrist and the posterior tibial artery 
at the ankle are, as nearly as can be determined, 29 inches and 52} 
inches respectively from the origin of the aorta in myself (on whom 
all the tracings have been taken), as previously mentioned; and as 
the time of transit of the wave varies very little with different rapid- 
ities of pulse, a single example may be taken to illustrate the point in 
question. With the heart beating 100 times in a minute, the time 
taken by the primary wave in reaching the wrist (that is, the length 
of the first cardio-radial interval with the syspasis subtracted) has 
been shown in a previous table to be ‘0021875 of a minute. Adding 
to this the interval between the radial and ankle primary rise at the 
same rapidity, which is very nearly ‘00116 of a minute, ‘0033475 of a 
minute is the time taken by the systolic wave in travelling from the 
heart to the ankle. But if this wave went the extra distance to the 
ankle (52°5 —29 =) 23°5 inches, at the same rate at which it reaches 
the wrist, the length of the first cardio-malleolar interval would be 
‘00459375 of a minute (29 : 52°5: : 21875 : 459375); but it is only 
‘0033475 of a minute, which is considerably less; consequently the 
wave augments in rapidity as its gets further from the heart, a phenome- 
non beyond my power to explain. 
By superimposing the wrist-trace from a simultaneous sphygmo- 
gram on that from the ankle, it is found that the components of each 
are of exactly similar duration, though the peculiar short interval 
following the dicrotic notch in the latter sometimes complicates the 
results. This exact similarity in length of the different elements of 
the two pulses is not, as will be found by those who attempt to 
measure them practically, self-evident from the tracings themselves ; 
because the one being slightly later than the other, and the watch- 
work varying in rapidity, gradually increasing and then declining, 
the radial, which is the earlier, is slightly the shorter in the com- 
mencement of the trace and the longer towards its end. In the middle 
of the recording-paper the two coincide. It may therefore be said 
that the compound sphygmograph-trace is entirely in favour of the 
correctness of Prop. IIT. 
In conclusion, the following is a summary of the results arrived at 
in this communication :-— 
I. The lengths of the different elements of the pulse-beat being 
