OF THE VIBRATIONS ON AN INVARIABLE PENDULUM. 
239 
of a vibration in the mean acceleration of the pendulum derived from the com- 
parison of the tropical and extra-tropical stations. 
The recalculation of those experiments, therefore, with the more correct ele- 
ments of reduction that we now possess, would have no other efFect than that 
of adding an equal amount to the number of vibrations of the experimental 
pendulum at every station : or an amount so nearly equal, that the difference 
is wholly inconsequential : leaving the acceleration of the pendulum at the dif- 
ferent stations, which was the object of research, as already deduced. 
