432 
MR. BA1LY ON THE CORRECTION OF 
“ and which may be considered as the additional weight gained by the pen- 
“ dulum, (or rather, the addition to its inertia) when moving in air, supposed 
“ to be applied to the centre of gyration This is the value given in the last 
column of the following Tablet- Its weight is expressed in grains troy ; 
and the air is supposed to be reduced to the temperature of 32°, and to 
the pressure of 29’92 1 8 inches : and its specific gravity is assumed equal to 
•001299. 
* “ The inertia of the whole pendulum, in resisting angular motion, is the same as if it were 
“ collected at the centre of gyration. The immediate result of the experiment and formula above 
“ given is, that the inertia of the whole pendulum ought to be increased in the proportion of 1 to 
“ (1 + 5 / — lf) : or Omt’ instead of supposing the inertia w applied at the centre of gyration, the 
“ inertia w (^1 + ^ — ought to be applied there. The addition to the inertia is therefore 
“ w (w ~ • applied where that of the whole pendulum may be supposed to be applied ; that is, 
“ at the centre of gyration .” 
t In all the computations, however, instead of using the approximate value I have taken the 
correct value (N + v)~ — N 2 . The difference is unimportant, unless the specific gravity of the pen- 
dulum be very small. 
