The effect produced by heat upon the movements of air--Air
a real substance--Exerts a pressure of fifteen tons on an
ordinary sized man--It cannot be moved without the expenditure
of power--The sun's rays the great moving power--They pass
through the forty-five miles of atmosphere without heating it,
and heat the solid substances of the earth's surface--Experiments
showing the effect of radiant heat and reflected heat--The air
of the room not pure and dry--The ordinary moisture absorbs
from fifty to seventy times as much as the air--Many gases
absorb much more--The moisture in the air the great regulator of
heat--Air is heated by coming in immediate contact with hotter
substances--Impossibility of any air remaining at rest--The
practical application of these principles--The open fire acts like
the sun, heating by radiation only--Probable electric or ozonic
change in furnace-heated air--The stove heats both by radiation
and circulation--The stove nor the open fire not suitable for
large crowded rooms--Circulating warmed air best--Erroneous views
in regard to ventilation--Experiments with liquids of different
densities--When warming and ventilating by circulating air, the
escape for the used air should be from the bottom of the room--But
when ventilating with cooler air the escape should be from the
top of the room--Windows should lower from the top and flues open
at the bottom of the room--The fashionable system of heating by
direct radiation, without any fresh air, very objectionable.