Now, there is no good reason why the rooms immediately under the roof of a house should be any more uncomfortable on account of heat than those of the first story.  Nay, more, by the simplest application of common-sense, these upper rooms may be so coolly ventilated that the hotter the sun pours his rays upon the roof the more salubrious shall be your palace in the sky.  And this I call a triumph of genius, making the seemingly destructive wrath of the elements to serve and save us.

M. Figuier tells us with just how many hundred thousand horse-power the sun, by the caloric of its beams, operates upon the surface of the earth.  I cannot tell precisely how much force is spent upon the roofs of the houses that cover so much of the good mother’s bosom in certain localities, but I know that it is wonderfully great, and that rightly controlled it will make the space immediately under these roofs cool instead of hot.

And this is the way to cause the heat of a burning sun to cool the attic chamber:  Make the space between the rafters on the sunny sides of your building as smooth and unobstructed as possible.  Arrange openings into the outer air at the lower end of each, simple or complex, according to your taste and ability.  Provide also means for closing the same in cold weather.  Be sure that these spaces, or flues, are enclosed either by lath and plaster, or by smooth boards, quite to the highest part of the roof, whether your rooms are finished to the top or not,—­and provided with an abundant outlet at the top.  This may also be as simple as the dorsal breathing-holes of a tobacco barn, gorgeously imposing as an Oriental pinnacle, or it may be a part of the chimney; only let it be at the very summit, ample, and so arranged that an adverse wind shall not prevent the egress of the rising currents of air.  Mind this, too; it is by no means the same thing to let these flues open into a loft over the attic rooms, with windows in gables or other outlet.

Now, do you not see that as soon as the sun has warmed the flues, there will be a stiff breeze blowing, not over the roof, but really between the roof and the house, and the hotter the sun the stiffer the breeze; in the words of one who has tried it,—­“a perfect hurricane.”  That is, the lath and plaster, or sheathing, which forms the inner roof, is shaded by a canopy of slate, shingles, or tin, and fanned by a constant breeze as cool at least as the outer air.  But we can do vastly better than that.  Instead of opening the lower ends of these flues to the outer air, they may be extended wherever the needs of the house require, or its construction will allow.

Let me remind you, under the head of general principles, that there is no such thing as “suction.”  Of course, you know it when you stop to think, but bear it in mind, and wherever the motive-power seems to be applied on which you rely to lift the column of air, remember that if raised at all it must be raised from the bottom.  Maybe you will discover room for a moral here.