[Footnote 7: 'More beautiful in that variety.'--This line, with the one italicized beneath, expresses in Myrrha's mind, the feeling which I said, in the outset, every thoughtful watcher of heaven necessarily had in those old days; whereas now, the variety is for the most part, only in modes of disagreeableness; and the vapor, instead of adding light to the unclouded sky, takes away the aspect and destroys the functions of sky altogether.]
[Footnote 8: 'Steam out of an engine funnel.'--Compare the sixth paragraph of Professor Tyndall's 'Forms of Water,' and the following seventh one, in which the phenomenon of transparent steam becoming opaque is thus explained. "Every bit of steam shrinks, when chilled, to a much more minute particle of water. The liquid particles thus produced form a kind of water dust of exceeding fineness, which floats in the air, and is called a cloud."
But the author does not tell us, in the first place, what is the shape or nature of a 'bit of steam,' nor, in the second place, how the contraction of the individual bits of steam is effected without any diminution of the whole mass of them, but on the contrary, during its steady _expansion_; in the third place he assumes that the particles of water dust are solid, not vesicular, which is not yet ascertained; in the fourth place, he does not tell us how their number and size are related to the quantity of invisible moisture in the air; in the fifth place, he does not tell us how cool invisible moisture differs from hot invisible moisture; and in the sixth, he does not tell us why the cool visible moisture stays while the hot visible moisture melts away. So much for the present state of 'scientific' information, or at least communicativeness, on the first and simplest conditions of the problem before us!
In its wider range that problem embraces the total mystery of volatile power in substance; and of the visible states consequent on sudden--and presumably, therefore, imperfect--vaporization; as the smoke of frankincense, or the sacred fume of modern devotion which now fills the inhabited world, as that of the rose and violet its deserts. What,--it would be useful to know, is the actual bulk of an atom of orange perfume?--what of one of vaporized tobacco, or gunpowder?--and where do _these_ artificial vapors fall back in beneficent rain? or through what areas of atmosphere exist, as invisible, though perhaps not innocuous, cloud?