460 
would require a great expenditure of muscular 
force, which is aided b the inclination of 
the trunk. That this inclination really takes 
place is confirmed by experience, and its 
amount has been measured by Weber, both in 
walking and running with various degrees of 
velocity. In order to take these measures with 
accuracy, a given path was passed over, some- 
times in running and sometimes in walking, 
with various d of speed, the time being 
measured and the steps counted. By means 
of a telescope, placed sideways to this path, 
the difference of inclination in walking and 
running was ascertained, but as it was extremely 
difficult to find the actual position of the centre 
of gravity of the trunk in such varying posi- 
tions, a conspicuous line marked on the trunk 
was substituted for the vertical line passing 
from the axis of the femurs through the centre 
of gravity, and thus its slightest deviations 
were observed. The vertical position of the 
trunk when at rest may be exactly estimated by 
the angle which it makes with this marked line 
in walking to and fro, in running to and fro, 
and in standing in the two opposite positions. 
The last angle, deducted from each of the two 
first, gives the double inclination of the trunk 
from the vertical in walking and running. . The 
results of these measurements are given in the 
following Tables. 
TaBLeE 1. 
Measure of the inclination of the trunk in 
walking and running. 
Angle between the 
two a posi- 
tions of the marked 
line in standing. 
130 74 
130 74 
130 66 
15° 46 
14° 00 
TABLE 2. 
Measure of the inclination of the trunk in 
walking slowly. 
Angle be- 
tween the ° 
two oppo-| = | Double 
site posi-| §& inclina- 
a a Duration |tions of the 2 tion 
° of marked of the 
Step. Step. line. . trunk. 
0.629 0.833 0.755 
0.664 0.777 18° 9 | 0.855] 4°9 
0.699 0.848 18° 9 | 0.824] 4°9 
0.664 | 0.793 | 20°6 | 0.837! 6°6 
0.699 | 0.839 | 20°6 | 0.833| 6°6 
0.629 0.812 18° 9 | 0.774] 4°9 
MOTION. 
TabLe 3. = 
Measure of the inclination of the trunk in 
é quick walking. - 
0.838 0.452 1.85 
0.838 0.426 27° 8 1.97 
0.838 0.429 26° 1 1.95 
0.838 0.428 27° 5 1.96 
0.838 0.444 32°6 | 1.89 
0.816 0.438 31° 8 1.86 
0.838 0.431 24° 9 1.945 
0.838 0.419 29° 2 2.00 
0.838 0.439 27° 5 1.91 
0.888 9.436 29° 2 2.04 
0 838 0.432 30° 9 1.94 
0.888 0.438 32° 6 2.03 
0.888 0.456 31° 8 1.95 
TABLE 4. 
Measure of the inclination of the trunk — 
in running. 
1.372 0.325 4.22 
1.509 0.323 48°1 | 4.67 
1.509 0.337 49° 8 5.00 
1.509 0.302 55° 8 5.03 
1.509 0.300 56° 7 4.72 
1.509 0.320 53° 3 
1.509 0.320 
We therefore conclude that when we vai 
our steps, the velocity of the upees ends of tl 
legs, together with a corresponding inclination 
is communicated to the trunk. run 
then, as has been before observed, exactly re- 
sembles a rod balanced on the fi ar 
carried forward; the inclination in cas 
depending on the laws of mechanics. y 
he force of the muscles which keep 
trunk in a state of equilibrium is likewise ec 
nomized in walking and running by the regu’ 
oscillations of the arms. The distance of t 
scapulo-humeral articulation from the ax 
which the trunk freely moves, gives an 
applied at the shoulder-joint a considera 
mechanical effect on the trunk. In prog 
the arms and legs move simultaneou: 
the following order. Whilst the right | 
swings forwards, the trunk is turned round h 
zontally on the head of the left femur, 
would pres! the right shoulder before the 
but at the same time the right arm swings ba 
ward and the left forwards, and by generati 
force in an opposite direction neutralises ” 
tendency. A corresponding compensation fa 
place when the left leg swings forward, 
this is effected by a good walker, without ¢ 
sensible lateral twisting of the trunk. 
length of the arms is so adjusted to that of 
legs, that they oscillate with the latter in sr 
curves simultaneously. Weber has comp 
the duration of a single oscillation of 
hanging straight down, at 0”.63, and wh 
at right angles at 0’.53. The pace is | 
strained and less fatiguing when the arms 
