intercepts more than the half, in proportion. So that generally the bow
is less than a semicircle, and never more. He says he has seen it more
than a semicircle. I have often seen the leg of the bow below my level.
My situation at Monticello admits this, because there is a mountain
there in the opposite direction of the afternoon's sun, the valley
between which and Monticello is five hundred feet deep. I have seen a
leg of a rainbow plunge down on the river running through the valley.
But I do not recollect to have remarked at any time, that the bow was
more than half a circle. It appears to me, that these facts demolish the
Newtonian hypothesis, but they do not support that erected in its stead
by the Abbe. He supposes a cloud between the sun and observer, and that
through some opening in that cloud, the rays pass, and form an iris on
the opposite part of the heavens, just as a ray passing through a hole
in the shutter of a darkened room, and falling on a prism there, forms
the prismatic colors on the opposite wall. According to this, we might
see bows of more than the half circle, as often as of less. A thousand
other objections occur to this hypothesis, which need not be suggested
to you. The result is, that we are wiser than we were, by having an
error the less in our catalogue; but the blank occasioned by it, must
remain for some happier hypothesist to fill up.

The dispute about the conversion and reconversion of water and air, is
still stoutly kept up. The contradictory experiments of chemists, leave
us at liberty to conclude what we please. My conclusion is, that art has
not yet invented sufficient aids, to enable such subtle bodies to make a
well defined impression on organs as blunt as ours: that it is laudable
to encourage investigation, but to hold back conclusion. Speaking one
day with Monsieur de Buffon on the present ardor of chemical inquiry, he
affected to consider chemistry but as cookery, and to place the toils
of the laboratory on a footing with those of the kitchen. I think it,
on the contrary, among the most useful of sciences, and big with future
discoveries for the utility and safety of the human race. It is yet,
indeed, a mere embryon. Its principles are contested; experiments seem
contradictory; their subjects are so minute as to escape our senses; and
their result too fallacious to satisfy the mind. It is probably an
age too soon, to propose the establishment of a system. The attempt,
therefo