At the very outset, let us take the ventilation-mongers on their own ground. People of this class are always referring us to nature. Very well, we will be natural. Do you believe, sir, that the words of that dear lady, when she said she loved you everlastingly, were poisonous air rendered sonorous by the action of a larynx, tongue, teeth, palate, and lips? No, indeed; ladies, at any rate, although they claim a double share of what the cherubs want—and, possibly, these humps, now three times spoken of, are the concealed and missing portions of the cherubim torn from them by the fair sex in some ancient struggle. There, now, I am again shipwrecked on the wondrous mountains. I was about to say, that ladies, who, in some things, surpass the cherubs, equal them in others; like them, are vocal with ethereal tones; their breath is “the sweet south, stealing across a bed of violets,” and that’s not poisonous, I fancy. Well, I believe the chemists have, as yet, not detected any difference between a man’s breath, and a woman’s; therefore, neither of them can be hurtful. But let us grant the whole position. Breath is poisonous, but nature made it so; nature intended it to be so. Nature made man a social animal, and, therefore, designed that many breaths should be commingled. Why do you, lovers of the natural, object to that arrangement? Now let us glance at the means adopted to get rid of this our breath, this breath of which our words are made, libeled as poisonous. Ventilation is of two kinds, mechanical and physical. I will say something about each.