I think, not only established the justness of my suspicions,
but ascertained the real cause both of dew and of several other natural
appearances which have hitherto received no sufficient explanation, I
venture now to submit to the consideration of the learned an account
of some of my labors, without regard to the order of time in which they
were performed, and of various conclusions which may be drawn from them,
mixed with facts and opinions already published by others:

"There are various occurrences in nature which seem to me strictly
allied to dew, though their relation to it be not always at first sight
perceivable. The statement and explanation of several of these will form
the concluding part of the present essay.

"1. I observed one morning, in winter, that the insides of the panes of
glass in the windows of my bedchamber were all of them moist, but that
those which had been covered by an inside shutter during the night were
much more so than the others which had been uncovered. Supposing that
this diversity of appearance depended upon a difference of temperature,
I applied the naked bulbs of two delicate thermometers to a covered
and uncovered pane; on which I found that the former was three degrees
colder than the latter. The air of the chamber, though no fire was kept
in it, was at this time eleven and one-half degrees warmer than that
without. Similar experiments were made on many other mornings, the
results of which were that the warmth of the internal air exceeded that
of the external from eight to eighteen degrees, the temperature of the
covered panes would be from one to five degrees less than the uncovered;
that the covered were sometimes dewed, while the uncovered were dry;
that at other times both were free from moisture; that the outsides of
the covered and uncovered panes had similar differences with respect to
heat, though not so great as those of the inner surfaces; and that no
variation in the quantity of these differences was occasioned by the
weather's being cloudy or fair, provided the heat of the internal air
exceeded that of the external equally in both of those states of the
atmosphere.

"The remote reason of these differences did not immediately present
itself. I soon, however, saw that the closed shutter shielded the glass
which it covered from the heat that was radiated to the windows by
the walls and furniture of the room, and thus kept it nearer to the
temperature of the external air