FLOODS, SNOW, THAW. 183 
or dews so refreshing and even essential to the 
vegetable world. Snow seems to be useful in 
preventing the deleterious effects of frost, and severe 
cold on plants, for while these disastrous results 
are too often witnessed, we almost invariably see, 
that plants which have lain inclosed in snow a 
long while, and this envelope been sealed over by a 
subsequent frost, appear nowise injured, but even 
fresh and green when a thaw again displays them 
to view. 
Persons generally consider that a thaw is nothing 
more than a solution of snow and ice by an 
alteration of temperature, and that the muddy state 
of roads is referrible to this circumstance alone ; 
but I remark, that the quantity of mud is far greater 
than could be expected from the amount of fallen 
snow combined as water with the loose soil and 
surface of roads and ground generally, and that 
by recollecting that heat is continually being evol- 
-ved from the interior of the earth, and that therefore 
the water retained in its substance from the rains 
and floods of autumn would not only be prevented 
from being frozen (or if frozen be again reduced 
speedily to water) but would with the soil wherein 
it lay, by the effect of gradually accumulating heat 
form a spongy mass, ready to be amalgamated with 
the dissolved snow and ice on the occurrence of 
the thaw,—we have a ready explanation of the 
circumstance. If there were not this internal heat 
of our earth, probably frosts would affect its watery 
particles to some depth, and then by the law of ex- 
pansion of water by cold, the ground would be rent 
and upheaved in all directions and without the 
possibility of solar heat, reducing it again to an 
aqueous state to its whole extent of depth. But, 
it is perhaps proof of heat escaping from the 
earth even through the ice and snows, that we find 
some portion of this mass is during day volatilized, 
