Page 353. 
16 ON THE SPHYGMOGRAPH TRACE. 
1:1:775 
: 1675 
: 1°75 
: 1°75 
: 1°725 
with an average of 1 : 1°7443. 
Again, in fig. 2, the ratios are :— 
1:38 
> B°775 
: 38 
: 3825 
with an average of 1 : 3°8. 
Calling the rate of the pulse z, and the number of times the first 
part is contained in the whole beat y, ey equals the number of times 
that the first part is contained in a minute, and ~ equals the part of a 
a 
minute occupied by the first part of each pulse-beat. 
From several observations, it was found that zy increases with 2, 
not directly as it, but as its eube root, consequently the following 
equation finds «xy in terms of 2, 
ay=k Sa, 
k being a constant, equal to 47 (about). 
For instance in fig. 1, ¢ = 137, y = 1°7443; | 
and in fig. 2, o= 44, ¥=3°8; 
and 137 x 1:7443 = 238-9691, 
44 x 3°38 = 167°2; 
and 238°9691 : 167:°2 :: 1:43 : 1, 
and ¥1387: Y44:: 
== 5'155 : 3°54: : 1:456: I, 
which shows that in these individual cases xy varies, within the limits 
of experimental error, as the cube root of «. 
If this statement of the ratio of the first part of the trace to the 
whole beat is a correct one, a knowledge of the rapidity of the pulse 
alone is sufficient to enable the length of the first part to be found by 
multiplying the cube root of the rapidity by the constant quantity 47. 
Thus, supposing the pulse beats 64 times in a minute, the cube 
root of 64 being 4, 4 x 47 = 188, and the length of the first part of 
the beat ought to be zi, of a minute. In one case with « = 64, wy 
was found to be 185°75, and in another with « = 63°5, ay = 181°77, 
both numbers which agree closely with the requirements of the equa- 
tion, 
With x = 140, and therefore */z = 5-2, 
52 x A7 = 244-4; 
