On the Pendulum Experiment. 213 
A power applied to the center of gravity of any body has no 
effect on its angular velocity. If therefore in this rotation aroun 
the axis of the earth, the center of the needle were stoppe 
while every other point of it retained a velocity equal to the 
difference between its former velocity and that of the center, the 
needle would continue to move, round a vertical line, with the 
same angular motion which it before maintained around the ver- 
tex of the cone. 
Let us now suppose a second needle, which, during a revolu- 
tion of the earth, has the same absolute velocity at every point, 
viz.: that due to its center. It was the difference in velocities 
that caused the angular movement of the first needle. But we 
have by supposition restored that difference. We have applied, 
as it were, to the first needle, in an opposite direction, the precise 
power which caused its own angular movement. So that if we 
take the first needle or meridian as the line of comparison, the 
second must continue to move from it with a uniform angular 
velocity equal to that of the first around the vertex of the cone. 
_ But we may view the phenomena in another and perhaps more 
simple light. care 
The second needle, supposed to start on the meridian, with 
rection constantly varying with that of the center. It follows 
e 
