Page 351. 
14 ON THE SPHYGMOGRAPH TRACE. 
3. ON THE RELATIVE DURATION OF THE COMPO- 
NENT PARTS OF THE RADIAL SPHYGMOGRAPH 
TRACE IN HEALTH.* 
(Piate I.) 
Tue graphic method of representing the various phenomena occurring 
in the body during life, which has been so much developed by MM. 
Marey and Chauveau of Paris, has placed within our reach great 
facilities for obtaining an accurate knowledge of the relations, in 
point of time, of mutually dependent physiological events, and the 
sphygmograph has become, among others, an instrument familiar to 
most interested in science. 
By means of this instrument a detailed and truthful record can be 
easily obtained of the modifications in the diameter of any superficial 
artery, and, as usually constructed, it is intended to be applied to the 
radial at the wrist. 
_ The traces to be referred to were taken with one of Marey’s instru- 
ments, as made by Breguet. The recording paper ran its whole length, 
43 inches, in seven seconds, and thus, by counting the number of 
pulse-beats in each trace, and multiplying the number thus obtained 
by 8°57143, the rate of the pulse at the time the trace was taken 
“was easily found. 
The lever-pen was of thin steel, sharply pointed, and it recorded 
by scratching on highly-polished paper previously smoked. 
It is now generally agreed that in each pulsation of the radial 
sphygmograph trace, the main rise is the effect of the contracting 
ventricle sending blood into, and thus filling, the arterial system. 
This rise is followed by a continuous fall when the pulse is quick, 
but when slow, its continuity is interrupted by a slight undulation, 
convex upwards. 
The major fall is followed by a secondary rise, not so considerable 
as the main one, but more marked than any other, and this secondary 
rise is evidently due to the closure of the aortic valves preventing 
further flow of blood heartwards. 
The two points therefore, the commencement of the primary and of 
the secondary rise, may be considered to mark the beginning of the 
systolé of the heart, and the closure of the aortic valve respectively, as 
far as they influence the artery at the wrist; and the interval between 
these two events may be called the first part of the arterial sphygmo- 
* “Proceedings of the Royal Society,’ XVIII. pp. 351-4, Pl. II. Read May 19, 
1870. 
