antages. It is apparently clean. There are no ashes to be taken
up, no hearths to sweep, no andirons to polish, no stoves to black.
One fire will warm the entire house if well arranged, and, for a trump
card, there may be a supply of fresh air straight from the north pole,
but agreeably warmed, constantly entering the room.

The objections are less numerous but more weighty. The liability to
imperfect construction and careless management often makes a furnace,
especially a cast-iron one, a savor of death unto death rather than of
health and comfort; also, when we are warmed by air thrown into a room
at a high temperature, and dry at that, a greater degree of heat is
necessary for comfort than if our bodies and clothing absorb heat from
a radiating surface. The furnace, in short, compels us to breathe an
atmosphere highly rarefied. We have the most careful and competent
authority for believing this to be gravely injurious.

Direct radiation from stoves, or other heating apparatus, except open
fireplaces, is, moreover, economical of fuel, but, on the other hand,
unless abundant ventilation is provided, the atmosphere in rooms thus
warmed soon becomes unfit for respiration.

Now you may stop and think. Next time you shall have the conclusion of
the whole matter.

LETTER XXXIX.

From John.

HOW TO DO IT.

MY DEAR ARCHITECT: I'm in a hurry. Let me ask you a few square
questions. Give me square answers if you can; if not, say so. What
kind of a furnace shall I get? I've interviewed about a dozen; each
one is warranted to give more heat, burn less coal, leak less gas,
give less trouble and more satisfaction, than all the others put
together. I suppose you object to cast-iron, because it's liable to be
heated red-hot and burn the air.

Is wrought-iron any better?

Shall I put the registers in the floors or in the partitions?

What do you say to steam?

How shall I ventilate?

Will it answer to have the ventilating flues in the outer walls?

There seems to be no doubt that the foul air should be drawn from the
bottom of a room; but if it's cold, how am I to get it to the
ventilator on the top of the house? If a room is as tight as a
fruit-can, a chimney might draw like a yoke of oxen without doing any
good, and Nebuchadnezzar's furnace wouldn't drive air into it unless,
in both cases, the inlets and outlets were about equal! When I go to
sleep in such a room I want to be sure the dampers won't get
accid