inued frost the course of a stream completely altered by this
bottom-ice (as it is called here), and I have also seen a weir
with a wall of ice on it three feet high (raised in a single
night) by the same cause. Now apply this to the bottom-ice in
ponds (which however I must confess I never saw). The night being
calm, the water gets cool below 32 degrees, but then a breeze
springing up the water becomes agitated, precipitation takes
place, and the plants serving as nuclei become immediately clothed
with this spongy ice, and the sun shining next morning imparts so
much warmth to the plants that the ice thaws which is in contact
with them, and rises to the surface. Of course if the sun does not
shine next morning, and the frost continues, the plants may be
clothed with ice for a long time.

To the foregoing the Editor of the "Agricultural Gazette" replied
as follows:--

We cannot admit the soundness of our correspondent's explanation
of the formation of bottom-ice or ground _gore_. We are well
acquainted with the statements of Arago and other writers as to
the cause of this curious phenomenon, and after a careful
consideration of the subject believe that it is due to radiation
and not to any other cause. Bottom-ice has been observed in ponds
on perfectly still nights when there was no breeze to agitate the
surface of the water.

The waters in the pools between the rapids of rivers can hardly
ever be still enough for the water to fall below the freezing-
point and yet remain fluid; the temperature of water in such
situations is not below 33 degrees.

The following was my rejoinder:--

You say at the end of remarks about bottom-ice that you cannot
admit the soundness of my explanation, and that you are well aware
of what is said by Arago and others on this curious phenomenon,
and that bottom-ice has been observed in ponds when there was no
breeze, and that the water in pools between the rapids of weirs
can hardly ever be still enough to fall below the freezing-point,
and yet remain fluid.

I was not aware before seeing your remarks that either Arago or
any other philosopher had ever written about bottom-ice, and even
now I do not know what are their opinions on the subject, and if
the discussions in your paper are to be settled by authority and
not by argument, I can only make my bow and withdraw; but if it
meets your views to allow your correspondents to state their
opinions temperately, and support them by such