92 Dr. Young’s remarks on the reduction 
as fa to c, or as y/ |toi. Thus if d were />", or — J , the 
^ 206265’ 
horizontal force would be ~~ = — — , and the acceleration 
of a pendulum - * or 1.5" of time in a day. It is true that 
a part of the deviation might depend on a defect of density as 
well as on an excess; but this defect could not amount to 
any great proportion of the whole, while the excess above 
the general density might easily be much more considerable, 
so that the acceleration of the pendulum could scarcely be 
less than a second in a day, if the greatest deviation of the 
plumb line were 5"; and if the deviation were 5" at any other 
place, there would be a greater acceleration than a second at 
a point more or less remote from it. 
F. If there were an excess of density on one side, and a 
deficiency on the other, so as to constitute virtually two 
centres of attraction and repulsion, and supposing their dis- 
tances to be equal, and such as to produce the greatest devia- 
tion, if the excess of density were twice as great as the 
deficiency, a deviation of 5" would correspond to an accelera- 
tion of half a second ; if 3 times as great, to J ; if 4 times, 
to and if five, to a second. 
It may perhaps be considered as an omission in this calcu- 
lation, that the attraction of the parts of the earth’s surface, 
elevated by means of the irregular gravitation, has not been 
included in it. But it depends on the supposition that we 
may adopt respecting the cause and date of the irregularity, 
whether or no we ought to consider it as likely to have occa- 
sioned such a general elevation ; and it does not appear that 
the result of the computation would very materially alter our 
conclusions, though it would be somewhat laborious to go 
