you, in
proportion as they are dealt out. Herschel's volcano in the moon you
have doubtless heard of, and placed among the other vagaries of a head,
which seems not organized for sound induction. The wildness of the
theories hitherto proposed by him, on his own discoveries, seems to
authorize us to consider his merit as that of a good optician only. You
know also, that Doctor Ingenhouse had discovered, as he supposed from
experiment, that vegetation might be promoted by occasioning streams of
the electrical fluid to pass through a plant, and that other physicians
had received and confirmed this theory. He now, however, retracts it,
and finds by more decisive experiments, that the electrical fluid can
neither forward nor retard vegetation. Uncorrected still of the rage of
drawing general conclusions from partial and equivocal observations, he
hazards the opinion that light promotes vegetation. I have heretofore
supposed from observation, that light affects the color of living
bodies, whether vegetable or animal; but that either the one or the
other receives nutriment from that fluid, must be permitted to be
doubted of, till better confirmed by observation. It is always better to
have no ideas, than false ones; to believe nothing, than to believe what
is wrong. In my mind, theories are more easily demolished than rebuilt.

An Abbe here, has shaken, if not destroyed, the theory of De Dominis,
Descartes and Newton, for explaining the phenomenon of the rainbow.
According to that theory, you know, a cone of rays issuing from the sun,
and falling on a cloud in the opposite part of the heavens, is reflected
back in the form of a smaller cone, the apex of which is the eye of the
observer: so that the eye of the observer must be in the axis of both
cones, and equally distant from every part of the bow. But he observes,
that he has repeatedly seen bows, the one end of which has been very
near to him, and the other at a very great distance. I have often
seen the same thing myself. I recollect well to have seen the end of a
rainbow between myself and a house, or between myself and a bank, not
twenty yards distant; and this repeatedly. But I never saw, what he
says he has seen, different rainbows at the same time, intersecting
each other. I never saw coexistent bows, which were not concentric
also. Again, according to the theory, if the sun is in the horizon, the
horizon intercepts the lower half of the bow, if above the horizon, that