THEORY OF CLOUDS. 
367 
showers of rain. It is, therefore, satisfactory to 
notice, that the explanation now offered, of the 
cause of the suspension of clouds, is perfectly con¬ 
sistent with our ideas respecting the general cause 
of rain; and, indeed, that the same principles that 
are requisite to account for the one phenomena, 
are equally applicable to the solution of the other. 
There is no great difficulty in accounting, on this 
theory, for the limited space occupied by clouds; 
though it could scarcely be expected to extend to 
an explanation of the various modifications ob¬ 
served, unless we had correct observations on the 
hygrometrical and tliermometrical states of the at¬ 
mosphere, where these different modifications oc¬ 
cur. Instead of a continuous stratum of cloud 
being formed by the process above stated, there 
would be a termination of the cloud, giving a de¬ 
finite edge, whenever the strata a and b became 
of the same temperature. Thus, all other things 
being the same, suppose the stratum b, which has 
been taken at the uniform temperature of 50° to 
be 40° at the place d. This being the same tem¬ 
perature as that of the upper stratum, could be 
productive of no deposition; consequently the 
cloud at this point would terminate. And again, 
let us suppose the strata b and c to be at rest, and 
the stratum a in motion, and, while the tempera¬ 
ture of a is uniformly the same, let that of the 
