48 Capt. Kater’s experiments for determining the 
vibrations after the adjustment by the second weight has 
been completed, must be left in defect , for a reason which will 
be immediately apparent. 
There is a point in the pendulum where the effect of the 
slider in increasing the number of vibrations is a maximum ; 
and it appears from Dr. Young’s investigations, that this 
point in one position of the pendulum is different from that in 
the other. Very near either of these points, the pendulum 
being in its corresponding position, the motion of the slider 
produces scarcely any change in the number of vibrations ; 
but the slider being then more distant from the point of max- 
imum belonging to the other position of the pendulum, the 
corresponding increase of the number of vibrations arising 
from such motion of the slider, will, in that position be very 
perceptible. 
In the present instance, the point of maximum in either 
position of the pendulum, is about four tenths of an inch 
below the middle, and consequently the distance of the two 
points from each other, is about eight tenths of an inch. The 
slider which had remained stationary during the adjustment 
of the second weight at about one inch and a half from the 
middle of the pendulum towards the great weight, must now 
be shifted, (say one inch) towards the middle of the pendu- 
lum, in order to increase the number of vibrations which it 
may be recollected were left in defect, so that they may be in 
excess. It is evident that the true number of vibrations will 
be found, when the slider is somewhere between its first and 
second position. Let the slider be now placed half-way be- 
tween these two points. If the number of vibrations in this 
