The quantity of air for each minute for one person is from four to
fifteen feet—and from one-half to one foot should be allowed for each
gas jet or lamp.
Heated air cannot be made to enter a room unless means are provided for
permitting an equal quantity to escape, and the best places for such
exit openings is near the floor.
For healthful ventilation the indirect system of steam heating is by
far the best yet devised, for it not only warms the room, but insures
perfect ventilation as well. In this system, the air for warming the
room is introduced through registers, having first been heated by
passing over coils of pipe or radiators suitably located in the air
ducts. There is a large volume of pure air constantly entering the
room, which must displace and drive out an equal quantity of impure
air. This escapes principally around the doors and windows, so that
not only is the ventilation effected automatically without the use of
special devices, but all disagreeable indraft of cold air is prevented.
One of the cheapest and best methods of ventilation is to have an
opening near the floor, opening directly into the flue, or some other
outlet especially constructed for it, _with hot water or steam pipes
in this opening_. A moderate degree of heat in these pipes will create
a draft, and draw out the bad air. Only a few of these pipes are
necessary, and the amount of hot water or steam required to heat them
is too small to be worthy of consideration.
The use of a small gas-jet, burning continuously, in a pipe or shaft
has been found to be a most admirable method of ventilating inside
rooms, closets and similar places where foul air might collect if not
replaced by fresh. The following table exhibits the result of careful
experiments made by Mr. Thomas Fletcher, of England, with a vertical
flue 6 inches in diameter and 12 feet high: