A. Yes; because the air is kept warm by fires, and the animal heat of the people in the room; in consequence of which, the air of a room suffers very little diminution of heat from the setting of the sun.
Q. Whence arises the vapour of a room?
A. 1st—The very air of the room contains vapour:
2ndly—The breath and insensible perspiration of the inmates increase this vapour: and
3rdly—Hot dinners, the steam of tea, &c. contribute to increase it still more.
Q. What is meant by “the insensible perspiration?”
A. From every part of the human body an insensible and invisible perspiration issues all night and day; not only in the hot weather of summer, but also in the coldest day of winter.
Q. If the perspiration be both insensible and invisible, how is it known that there is any such perspiration?
A. If you put your naked arm into a clean dry glass cylinder, the perspiration of your arm will soon condense on the glass, like mist.