THE following lectures, drawn up under the pressure of more imperative and quite otherwise directed work, contain many passages which stand in need of support, and some, I do not doubt, more or less of correction, which I always prefer to receive openly from the better knowledge of friends, after setting down my own impressions of the matter in clearness as far as they reach, than to guard myself against by submitting my manuscript, before publication, to annotators whose str

LET me first assure my audience that I have no arrière pensée in the title chosen for this lecture. I might, indeed, have meant, and it would have been only too like me to mean, any number of things by such a title;—but, to-night, I mean simply what I have said, and propose to bring to your notice a series of cloud phenomena, which, so far as I can weigh existing evidence, are peculiar to our own times; yet which have not hitherto received any special notice or description fr

So far as the existing evidence, I say, of former literature can be interpreted, the storm-cloud—or more accurately plague-cloud, for it is not always stormy—which I am about to describe to you, never was seen but by now living, or lately living eyes. It is not yet twenty years that this—I may well call it, wonderful—cloud has been, in its essence, recognizable. There is no description of it, so far as I have read, by any ancient observer. Neither Homer nor Virgil, neither Ar

In those old days, when weather was fine, it was luxuriously fine; when it was bad—it was often abominably bad,[1] but it had its fit of temper and was done with it—it didn’t sulk for three months without letting you see the sun,—nor send you one cyclone inside out, every Saturday afternoon, and another outside in, every Monday morning. In fine weather the sky was either blue or clear in its light; the clouds, either white or golden, adding to, not abating, the lustre of the

In the entire system of the Firmament, thus seen and understood, there appeared to be, to all the thinkers of those ages, the incontrovertible and unmistakable evidence of a Divine Power in creation, which had fitted, as the air for human breath, so the clouds for human sight and nourishment;—the Father who was in heaven feeding day by day the souls of His children with marvels, and satisfying them with bread, and so filling their hearts with food and gladness. Their hearts

You will not think I waste your time in giving you two cardinal examples of the sort of evidence which the higher forms of literature furnish respecting the cloud-phenomena of former times. When, in the close of my lecture on landscape last year at Oxford, I spoke of stationary clouds as distinguished from passing ones, some blockheads wrote to the papers to say that clouds never were stationary. Those foolish letters were so far useful in causing a friend to write me the pr

With this bit of noonday from Homer, I will read you a sunset and a sunrise from Byron. That will enough express to you the scope and sweep of all glorious literature, from the orient of Greece herself to the death of the last Englishman who loved her. I will read you from Sardanapalus the address of the Chaldean priest Beleses to the sunset, and of the Greek slave, Myrrha, to the morning. “The sun goes down: methinks he sets more slowly, Taking his last look of Assyria’s emp

Thus much, then, of the skies that used to be, and clouds “more lovely than the unclouded sky,” and of the temper of their observers. I pass to the account of clouds that are , and—I say it with sorrow—of the dis temper of their observers. But the general division which I have instituted between bad-weather and fair-weather clouds must be more carefully carried out in the sub-species, before we can reason of it farther: and before we begin talk either of the sub-genera and s

That is the first idea you have to get well into your minds concerning the abodes of this visible vapour; next, you have to consider the manner of its visibility. Is it, you have to ask, with cloud vapour, as with most other things, that they are seen when they are there, and not seen when they are not there? or has cloud vapour so much of the ghost in it, that it can be visible or invisible as it likes, and may perhaps be all unpleasantly and malignantly there, just as much

That, I say, is broadly and comfortably so on the whole,—and yet with this kind of qualification and farther condition in the matter. If you watch the steam coming strongly out of an engine-funnel,—at the top of the funnel it is transparent,—you can’t see it, though it is more densely and intensely there than anywhere else. Six inches out of the funnel it becomes snow-white,—you see it, and you see it, observe, exactly where it is,—it is then a real and proper cloud. Twenty y

Then the next bit of the question, of course, is, What makes the vapour visible, when it is so? Why is the compressed steam transparent, the loose steam white, the dissolved steam transparent again? The scientific people tell you that the vapour becomes visible, and chilled, as it expands. Many thanks to them; but can they show us any reason why particles of water should be more opaque when they are separated than when they are close together, or give us any idea of the diff

And here I must parenthetically give you a little word of, I will venture to say, extremely useful, advice about scientific people in general. Their first business is, of course, to tell you things that are so, and do happen,—as that, if you warm water, it will boil; if you cool it, it will freeze; and if you put a candle to a cask of gunpowder, it will blow you up. Their second, and far more important business, is to tell you what you had best do under the circumstances,—put

I go back to my point—the way in which clouds, as a matter of fact, become visible. I have defined the floating or sky cloud, and defined the falling or earth cloud. But there’s a sort of thing between the two, which needs a third definition: namely, Mist. In the 22nd page of his Glaciers of the Alps , Professor Tyndall says that “the marvellous blueness of the sky in the earlier part of the day indicated that the air was charged, almost to saturation, with transparent aqueou

I put the question—and pass round to the other side. Such a clearness, though a certain forerunner of rain, is not always its forerunner. Far the contrary. Thick air is a much more frequent forerunner of rain than clear air. In cool weather, you will often get the transparent prophecy: but in hot weather, or in certain not hitherto defined states of atmosphere, the forerunner of rain is mist. In a general way, after you have had two or three days of rain, the air and sky are

I suppose the thick air, as well as the transparent, is in both cases saturated with aqueous vapour;—but also in both, observe, vapour that floats everywhere, as if you mixed mud with the sea; and it takes no shape anywhere: you may have it with calm, or with wind, it makes no difference to it. You have a nasty haze with a bitter east wind, or a nasty haze with not a leaf stirring, and you may have the clear blue vapour with a fresh rainy breeze, or the clear blue vapour as s

Hitherto I have spoken of all aqueous vapour as if it were either transparent or white—visible by becoming opaque like snow, but not by any accession of colour. But even those of us who are least observant of skies, know that, irrespective of all supervening colours from the sun, there are white clouds, brown clouds, grey clouds, and black clouds. Are these indeed—what they appear to be—entirely distinct monastic disciplines of cloud: Black Friars, and White Friars, and Friar

Admitting degrees of darkness, we have next to ask what colour from sunshine can the white cloud receive, and what the black? You won’t expect me to tell you all that, or even the little that is accurately known about that, in a quarter of an hour; yet note these main facts on the matter. On any pure white, and practically opaque, cloud, or thing like a cloud, as an Alp, or Milan Cathedral, you can have cast by rising or setting sunlight, any tints of amber, orange, or mode

But when the cloud is transparent as well as pure, and can be filled with light through all the body of it, you then can have by the light reflected from its atoms any force conceivable by human mind of the entire group of the golden and ruby colours, from intensely burnished gold colour, through a scarlet for whose brightness there are no words, into any depth and any hue of Tyrian crimson and Byzantine purple. These with full blue breathed between them at the zenith, and gr

No colours that can be fixed in earth can ever represent to you the lustre of these cloudy ones. But the actual tints may be shown you in a lower key, and to a certain extent their power and relation to each other. I have painted the diagram here shown you with colours prepared for me lately by Messrs. Newman, which I find brilliant to the height that pigments can be; and the ready kindness of Mr. Wilson Barrett enables me to show you their effect by a white light as pure as

But now note, there is another kind of cloud, pure white, and exquisitely delicate; which acts not by reflecting, nor by refracting, but, as it is now called,2 dif fracting, the sun’s rays. The particles of this cloud are said—with what truth I know not3—to send the sunbeams round them instead of through them; somehow or other, at any rate, they resolve them into their prismatic element; and then you have literally a kaleidoscope in the sky, with every colour of the prism in

This second diagram is enlarged admirably by Mr. Arthur Severn from my sketch of the sky in the afternoon of the 6th of August, 1880, at Brantwood, two hours before sunset. You are looking west by north, straight towards the sun, and nearly straight towards the wind. From the west the wind blows fiercely towards you out of the blue sky. Under the blue space is a flattened dome of earth-cloud clinging to, and altogether masquing the form of, the mountain, known as the Old Man

Enough, however, is here done to fix in your minds the distinction between those two species of cloud,—one, either stationary, or slow in motion, reflecting unresolved light; the other, fast-flying, and transmitting resolved light. What difference is there in the nature of the atoms, between those two kinds of clouds? I leave the question with you for to-day, merely hinting to you my suspicion that the prismatic cloud is of finely-comminuted water, or ice, instead of aqueous

The main reason, however, why I can tell you nothing yet about these colours of diffraction or interference, is that, whenever I try to find anything firm for you to depend on, I am stopped by the quite frightful inaccuracy of the scientific people’s terms,[1] which is the consequence of their always trying to write mixed Latin and English, so losing the grace of the one and the sense of the other. And, in this point of the diffraction of light I am stopped dead by their conf

Yet observe that in thus signalizing the inaccuracy of the terms in which they are taught, I neither accept, nor assail, the conclusions respecting the oscillatory states of light, heat, and sound, which have resulted from the postulate of an elastic, though impalpable and imponderable ether, possessing the elasticity of air. This only I desire you to mark with attention,—that both light and sound are sensations of the animal frame, which remain, and must remain, wholly inexp