CIRCULATION OF THE BLOOD. 87 
end in the left hand, and attached at the other extremity to the right 
wrist, is then pressed down on the inside of the left foot (which rests 
on the right knee), in such a way that its pulse-pad compresses the 
posterior tibial artery where its pulsation is most manifest. The lever 
is made to record on the lower part of the smoked paper, below the 
one connected with the wrist. When both levers are found to be 
working freely, the recording-paper is set’ moving by liberating the 
watchwork-catch with the left thumb, which is close to it. The respi- 
ration must be checked during the time the recording-paper is moving, 
to prevent irregularities in the trace. 
Results arrived at from the Study of the Simultaneous Wrist and Ankle Page 149. 
Tracings. 
In employing the tracings obtained from the above compound in- 
strument, two objects were kept in view—irst, to find the interval 
between the commencement of the primary rises in the wrist and 
ankle curves; and secondly, to observe whether or no the superposition 
of the one trace upon the other verified or falsified the statement 
made in Prop. III, that the lengths of the different parts of each 
element of the curve were the same in the two arteries. 
5 The following table contains the measurements of the lengths of 
the intervals between the commencement of the primary rise in the 
wrist and ankle tracings at different rapidities of pulse, from which it 
is clear that this interval varies very slightly within the range that 
can be obtained, and that the tendency is for it to be very slightly 
longer in the slower pulses. 
Rapidity of Length of interval between commencement of systolic rise 
pulse. at the wrist and at the ankle. 
62 00115’ occurring 14°08 times in each beat 
63 00125’ »? 12°7 ” 2 2 
67 001343’ z rst ee Sanat ¢ 
> 0013278’ 2 11°24 ” ” 2» 
70 001222’ ” 117 2? ” 23 
71 00136’ n 102 » ” ” 
” 00124 »” 11°41 2? 5 2 
. 0013’ 108 =, nies 
72 0012’ ” u7 »” ” » 
2 -001206' ss 1152 =, Gees 
79 001145’ 2? 11-06 » ” 2» 
< so 00126’ »” 9 96 ” ” 2 
81 001233’ »” 10 37 ” >»? 7 
82 001123’ Se 10°86, as ~ 
33 00122 » 10 3” »” 3 
95 00122’ ” 8 67 ” bP 2 
98 “001085' » . aE » » 
99 00116’ 3? 8 607 »” 2? 2? 
