entally shut.

Give me your opinion on these points, but don't make a long story or a
tough one. If a house is to be kept warm from turret to
foundation-stone, I don't see that shutting up the spaces between the
timbers would amount to much, except to stop sounds from echoing
through them; but when the attic is as cold as out-doors, it's plain
that the cold air will be always crawling down next the inside
plastering of every room in the house if it finds a chance.

Yours,

JOHN.

LETTER XL.

From the Architect.

THE BREATH OF LIFE.

DEAR JOHN: No man ever built himself a house without getting out of
patience before it was finished.

Among all the furnaces you have examined, a certain one is doubtless
better for you than any other; when I find out which one, you shall be
informed. Reliable testimony on the subject can only be given by some
one who has tried different kinds in the same house under similar
circumstances for a considerable time. As we never have two seasons
alike, and do have about three new first-class furnaces every year,
it is difficult to find this valuable witness. Printed testimonials
are worth three or four cents per pound. I do not know that cast-iron
furnaces are more liable to be overheated than others, and you cannot
"burn the air" with them if they are, unless you burn the furnace too.
You may fill a room with air, every mouthful of which has been passed
between red-hot iron plates, not over half an inch apart, and I do not
suppose the essential properties of the air will be perceptibly
changed, or hurt for breathing when properly cooled.

The danger from cast-iron is in its weakness, not in its strength.

You speak of poison carbon. Carbonic acid is not poison. It is
harmless as water,--just. It will choke you to death if you are
immersed in it. Trying to breathe it in large quantities will strangle
you. But we drink it with safety and pleasure, and may breathe a
little of it, even as much as thirty per cent, for a short time,
without serious harm. But carbonic oxide, which is also liberated from
burning anthracite, is an active poison, and one per cent of it in the
air we breathe may prove instantly fatal. Now it is fully proven that
these gases laugh at cast-iron and pass through it freely whenever
they choose. Wrought-iron plates are supposed to be more impervious.
The popular notion that foul air must be drawn from the bottom of a
room is based, I think, upon a superfi