ON THE SPHYGMOGRAPH TRACE, 15 
graph trace, while the interval between the beginning of the secondary Page 352. 
rise and that of the succeeding primary one constitutes the second 
part of the same trace. 
In 1865, Prof. Donders* published the results of experiments to 
determine the relative duration of the first and second part of the 
cardiac revolution with different rapidities of movements of the heart; 
taking as his data the commencement of the first and second sounds 
respectively, and he came to the conclusion that, though the second 
part varied with the rapidity, the first part was almost constant in all 
cases. 
On commencing work with the sphygmograph, the author came 
to the same conclusion with regard to the trace at the wrist, but, on 
improving his methods of observation, he has arrived at a different 
result. 
The best means of insuring an accurate measurement of any 
sphygmograph trace is to project all the points desired to be com- 
pared on to one straight line, and this is done by fixing the trace on 
to a piece of board, which has another pointed lever attached to it, 
with relations similar to those of the lever and recording apparatus in 
the original instrument. By this means lines can be scratched on the 
trace similar to those which would be produced by the instrument 
itself if the watch-work were not moving, and a result, as shown in 
Plate I. fig. 1. can be easily produced. 
The reason why this means has to be employed is, because the 
lever in the sphygmograph moves in part of a circle, not directly up 
. and down. 
> The ratio between the length of the first part of each pulse-beat 
in a trace and that of the whole beat was measured with a small pair 
; of compasses, and from these the average was obtained, which thus 
? eliminated, in a great degree, the variations produced by the respira- 
é tory movements, and also some of the clock-work imperfections. 
al For example, in fig. 1, the ratios in the several beats are :— 
4 1:18 
* | : 1-725 
: 1°725 
:1°775 
: 1°725 
es 
: 1725 
: 1775 
:18 
* “ On the Rhythm of the Sounds of the Heart.” By F.C. Donders. Trans- 
lated in the “ Dublin Quarterly Journal of Medical Science,” Feb. 1868, from the 
“Nederlandisch Archief voor Genees- en Natuurkunde,” Utrecht, 1865. 
