On the Resistance of Fluids. 319 
number is as its superficial area.” Now admitting it to be true that 
the number of material particles in contact with the plane, at any 
instant, is the same, whether it be perpendicular or inclined to the 
lection of the motion, it does not, we think, necessarily follow that 
the number of particles struck in any given time will be the same. 
But neither is it evident that the number of particles in contact with 
the plane is the same for every inclination of the plane. ‘The bur- 
den of proof, however, seems to lie with Prof. W. He has assumed 
the general physical fact that the number of particles in contact with 
the plane, at any instant, is the same for every position of the plane, 
and he has deduced an inference, not formally expressed, indeed, 
but surely implied, otherwise the argument is worth nothing, that 
the number of particles struck in any given time is as the number in 
contact with the plane at any instant. Now we think the fact and 
the conclusion may very safely be denied, and it becomes Prof. W. 
to shew that they are consistent with some hypothesis ae the 
form and relative position of the ultimate particles of a fluid body. 
In any hypothesis, we believe the following positions will i found 
to hold: 
First. Whether the — of particles, at any instant, in contact 
with the plane, in different positions, is the same, depends wholly 
on the hypothesis. 
Second. If the number is the same in different positions, it will 
be found that the number of fluid strata struck in any given time is 
as the sine of the inclination. 
ird. If the number is not the same then it varies as the sine of 
the inclination, a the number of strata struck will, in any given 
time, be the sam 
If Prof. W. can aes any hypothesis with which these positions 
do not agree, we will allow he can disturb our belief in the truth of 
the law of the square of the sines. 
The wide difference between the results of observation and those 
of the old theory, would tend rather to dissuade us from admitting 
the truth of the new, when we consider what important physical 
circumstances are and must be omitted in the conditions. 
Waterville College, (Me.) 
