than those parts could be which, from
being uncovered, received the heat emitted to them by the bodies just
mentioned.

"In making these experiments, I seldom observed the inside of any pane
to be more than a little damped, though it might be from eight to twelve
degrees colder than the general mass of the air in the room; while, in
the open air, I had often found a great dew to form on substances
only three or four degrees colder than the atmosphere. This at first
surprised me; but the cause now seems plain. The air of the chamber had
once been a portion of the external atmosphere, and had afterwards
been heated, when it could receive little accessories to its original
moisture. It constantly required being cooled considerably before it
was even brought back to its former nearness to repletion with water;
whereas the whole external air is commonly, at night, nearly replete
with moisture, and therefore readily precipitates dew on bodies only a
little colder than itself.

"When the air of a room is warmer than the external atmosphere, the
effect of an outside shutter on the temperature of the glass of the
window will be directly opposite to what has just been stated; since
it must prevent the radiation, into the atmosphere, of the heat of the
chamber transmitted through the glass.

"2. Count Rumford appears to have rightly conjectured that the
inhabitants of certain hot countries, who sleep at nights on the tops of
their houses, are cooled during this exposure by the radiation of their
heat to the sky; or, according to his manner of expression, by receiving
frigorific rays from the heavens. Another fact of this kind seems to be
the greater chill which we often experience upon passing at night from
the cover of a house into the air than might have been expected from the
cold of the external atmosphere. The cause, indeed, is said to be the
quickness of transition from one situation to another. But if this were
the whole reason, an equal chill would be felt in the day, when the
difference, in point of heat, between the internal and external air was
the same as at night, which is not the case. Besides, if I can trust my
own observation, the feeling of cold from this cause is more remarkable
in a clear than in a cloudy night, and in the country than in towns. The
following appears to be the manner in which these things are chiefly to
be explained:

"During the day our bodies while in the open air, although not
immediate