A SINGULAR Is 
en impulfe, acquire a greater motion than the oil, and 
that therefore the waves excited on the furface of the one, 
will be greater than thofe on the furface of the other—Up- 
on this principle, then, if quickfilver be fubftituted in 
place of the water, the commotion excited in it would be 
ftill greater than that in the water; asit would “ receive 
the force of the impulfe, form its fuperior fpecific gravity, 
in a much greater proportion.” But zm fac? the dire con- 
trary will be found to be the cafe.. Moreover, if two flu- 
ids, of unequal {pecific gravities, be put feparately into 
two different glafles, and moved with equal velocities, the 
commotion excited in the Heavier fluid will be apparently 
fe/s than that in the lighter; the former, from its greater 
{fpecific gravity, preferving its level furface with more ob- 
ftinacy than the latter; which is contrary to what ought to 
take place upon the above principles. 
But without entering further into a refutation of the 
above folution, I fhall {ubmit to your confideration one, 
which to me, at leaft appears better to account for this 
fingular phenomenon. 
t. When the tendency of a body upwards is juff equal 
to its tendency downwards, it will then, upon the /eaf 
impulfive force, move indifferently in either direction. 
This is the cafe of a body immerfed in a fluid of the 
fame fpecific gravity; where the buoyancy of the fluid, to 
raife the body upwards, is juft equal to the power of grav- 
ity, to draw it downwards. 
2. When the tendency of a body xpwards is nearly 
equal to its tendency downwards, then, a /mall impulfive 
force upwards, will move it in that direCtion. . 
This is the cafe of a body immerfed in a fluid of early 
equal fpecific gravity; for then the relative gravity, or 
tendency of the body downwards, will be only the excefs 
of its {pecific gravity above that of the fluid in which it 
is immerfed.—But water immerfed in common oil is juft 
iy 
