190 , Of the SOLIDS 
will be no variation produced in the force which the folid exerts 
on the particle A, in the direction AB. 
Tue curve ACB, therefore, is the locus of all the points in 
which a body being placed, will attract the particle A in the 
direction AB, with the fame: force. 
Tus condition is fufficient to determine the nature of the 
curve ABC. From.C, any point in that curve, draw CE per- 
pendicular to AB ; then if a-mafs of matter placed at C be call- 
3 
ed m', aa will be the attraction of that mafs on A, in the di- 
m?>X AE 
rection AC, and AG 
will be its attraGtion in the direCtion 
AB. As this is conftant, it will be equal to ao and therefore. 
AB? -<AE = AC3. 
Aut the fections of the required folid, therefore, by planes 
pafling through AB, have this. property, that AC7-=AB*XAE ; 
and as this equation is fufficient to determine the nature of the 
curve to which it belongs, therefore all the fections.of the fo- 
lid, by planes that pafs through AB, are fimilar and equal 
curves ; and the folid of confequence may be conceived to be 
generated by the revolution of ACB, any one of thefe curves, 
about AB as an axis. 
Tue folid fo generated may be called the Solid of greatef 
Attraction ; and the line ACB, the Curve of equal Attraction. 
UW. 
To find the equation between the co-ordinates. of ACB, the 
curve of equal attraction. 
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