.50 Mr. Atwood's Propositions determining the Positions 
are elevated by the inclination, the force of the fluid's pressure 
must continually augment the inclination ; or, in other words, 
will cause the solid to overset, or change its position, until it 
settles in some other, in which the equilibrium is permanent. 
We observe, therefore, that a solid floats permanently in a 
given position, only because the smallest inclination from that 
position creates a force by which tl\e inclination is imme- 
diately counteracted, and the solid becomes restored to its up- 
right position ; and consequently, since the inclination is coun- 
teracted while of evanescent magnitude, no sensible deviation 
from the upright can take place : in cases of instability, the 
solid oversets, although placed on a fluid with the centre of 
gravity of the solid and that of the part immersed in the same 
vertical line, because the smallest deviation or inclination from 
that position creates a force by which the inclination is aug- 
mented. And since various causes concur in preventing the 
two centres from remaining adjusted to the vertical with a 
precision absolutely mathematical, it follows that the least or 
evanescent inclination here mentioned must necessarily sub- 
sist, and being continually augmented by the fluid's pressure, 
must become a sensible rotation, by which the solid oversets 
from its upright position. 
In either case, that is, whether the solid floats permanently, 
or oversets, if it is placed on the surface of a fluid, so that the 
centre of gravity of the solid and the centre of gravity of the 
part immersed shall be in the same vertical line, the solid is 
said to be in a position of equilibrium : and from the preced- 
ing observations it appears, that there are three species of 
equilibrium in which a solid may be situated when the two 
centres of gravity just mentioned are in the same vertical line. 
