FROM THE HUMAN CHEST-WALL. 19 
first described ; after these the slow ones, by which means an idea can 
be best formed of the relation between curves at first sight so dif- 
ferent as those produced when the heart’s action is over 100 and 
those when it is below 50 in a minute (compare Figs. I and VI). 
There is a great similarity in traces from pulses above 105 to 
those over 140 in a minute; and the description of one will include 
them all. Figure I is from a heart beating 125, and it represents all 
the characteristic features. The movements of the lever are very 
extensive and sudden, so as to give the impression that they depend 
‘ more on its momentum than on the heart’s action; but that such is 
& not the case is shown by applying the instrument a little way from 
Sy the point of greatest pulsation, when (as in Fig. IT) all the same 
* elements appear, though much less ample and otherwise modified. 
The main ascent commences abruptly immediately after a slight 
rise and fall (a, Figs. I, Il), and is always broken about midway (6) 
by a small fall; it is followed by a most considerable and rapid 
descent, which carries the lever in an unbroken line, down to a point 
almost as low as that from which it started. Subsequently to this 
comes a less sudden rise (f), which reaches about as high as the break 
in the main ascent; its summit is not nearly so sharp as the previous 
one, and from it a fall, frequently a little irregular, commences slowly, 
becoming more rapid, though it is interrupted by a slight rise (q), 
after which it continues to sink until it reaches the lowest point of the 
trace, from which it makes a sudden slight ascent (*), which soon 
becomes more gradual, continuing until the rise (a) from which the 
description commenced. 
Neglecting for the present small differences in the relative dura- 
tions of these components, the pulse of 140 differs from that of 110 a 
minute in the movements being more extensive and consequently the 
angles more sharp, the intermediate rates being intermediate in 
character. 
In the pulse of about 90 a minute (Fig. III) another small rise Page 19. 
and fall appears (¢) in addition to those previously described, which is 
very constant, and becomes more considerable when the heart’s actio 
is slower. 
Here also, as shown in Fig. IV in a trace taken directly after 
Fig. III between the sixth and seventh ribs, there is sometimes seen a 
reduplication of the first part of the main rise (b, c, Fig. IV), which is 
disguised in Fig. III probably by the momentum of the lever. Another 
point in which it differs from the quicker pulses is in the formation of 
a second undulation (b) in the main descent before it reaches its 
lowest point. The main ascent also is not so extensive. 
When about 70 beats are made in a minute, the main rise can fre- 
quently be shown to be doubly broken (5, c, Fig. V); but these often 
c2 
