The Storm-Cloud of the Nineteenth Century

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Preface	iii
Lecture I. (February 4)	1
Lecture II. (February 11)	31

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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 stricture or suggestion I might often feel pain in refusing, yet hesitation in admitting.

But though thus hastily, and to some extent incautiously, thrown into form, the statements in the text are founded on patient and, in all essential particulars, accurately recorded observations of the sky, during fifty years of a life of solitude and leisure; and in all they contain of what may seem to the reader questionable, or astonishing, are guardedly and absolutely true.

In many of the reports given by the daily press, my assertion of radical change, during recent years, in weather aspect was scouted as imaginary, or insane. I am indeed, every day of my yet spared life, more and more grateful that my mind is capable of imaginative vision, and liable to the noble dangers of delusion which separate the speculative intellect of humanity from the dreamless instinct of brutes: but I have been able, during all active work, to use or refuse my power of contemplative imagination, with as easy command of it as a physicist's of his telescope: the times of morbid are just as easily distinguished by me from those of healthy vision, as by men of ordinary faculty, dream from waking; nor is there a single fact stated in the following pages which I have not verified with a chemist's analysis, and a geometer's precision.

The first lecture is printed, with only addition here and there of an elucidatory word or phrase, precisely as it was given on the 4th February. In repeating it on the 11th, I amplified several passages, and substituted for the concluding one, which had been printed with accuracy in most of the leading journals, some observations which I thought calculated to be of more general interest. To these, with the additions in the first text, I have now prefixed a few explanatory notes, to which numeral references are given in the pages they explain, and have arranged the fragments in connection clear enough to allow of their being read with ease as a second Lecture.

Herne Hill, 12th March, 1884.

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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 from meteorologists.

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 Aristophanes nor Horace, acknowledge any such clouds among those compelled by Jove. Chaucer has no word of them, nor Dante;[1] Milton none, nor Thomson. In modern times, Scott, Wordsworth and Byron are alike unconscious of them; and the most observant and descriptive of scientific men, De Saussure, is utterly silent concerning them. Taking up the traditions of air from the year before Scott's death, I am able, by my own constant and close observation, to certify you that in the forty following years (1831 to 1871 approximately—for the phenomena in question came on gradually)—no such clouds as these are, and are now often for months without intermission, were ever seen in the skies of England, France, or Italy.

In those old days, when weather was fine, it was luxuriously fine; when it was bad—it was often abominably bad, 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 luster of the sky. In wet weather, there were two different species of clouds,—those of beneficent rain, which for distinction's sake I will call the non-electric rain-cloud, and those of storm, usually charged highly with electricity. The beneficent rain-cloud was indeed often extremely dull and gray for days together, but gracious nevertheless, felt to be doing good, and often to be delightful after drought; capable also of the most exquisite coloring, under certain conditions;[2] and continually traversed in clearing by the rainbow:—and, secondly, the storm-cloud, always majestic, often dazzlingly beautiful, and felt also to be beneficent in its own way, affecting the mass of the air with vital agitation, and purging it from the impurity of all morbific elements.

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 observe, it is said, not merely their bellies,—or indeed not at all, in this sense, their bellies—but the heart itself, with its blood for this life, and its faith for the next. The opposition between this idea and the notions of our own time may be more accurately expressed by modification of the Greek than of the English sentence. The old Greek is—

ἐμπιπλῶν τροφῆς καὶ ἐυφροσύνης
τὰς καρδίας ήμῶν.

filling with meat, and cheerfulness, our hearts. The modern Greek should be—

ἐμπιπλῶν ἀνέμου καὶ ἀφροσύνης
τὰς γαστέρας ἡμῶν.

filling with wind, and foolishness, our stomachs.

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 pretty one I am about to read to you, quoting a passage about clouds in Homer which I had myself never noticed, though perhaps the most beautiful of its kind in the Iliad. In the fifth book, after the truce is broken, and the aggressor Trojans are rushing to the onset in a tumult of clamor and charge, Homer says that the Greeks, abiding them "stood like clouds." My correspondent, giving the passage, writes as follows:—

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.[3] 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 empire.
How red he glares amongst those deepening clouds,[4]
Like the blood he predicts.[5] If not in vain,
Thou sun that sinkest, and ye stars which rise,
I have outwatch'd ye, reading ray by ray
The edicts of your orbs, which make Time tremble
For what he brings the nations, 't is the furthest
Hour of Assyria's years. And yet how calm!
An earthquake should announce so great a fall—
A summer's sun discloses it. Yon disk
To the star-read Chaldean, bears upon
Its everlasting page the end of what
Seem'd everlasting; but oh! thou true sun!
The burning oracle of all that live,
As fountain of all life, and symbol of
Him who bestows it, wherefore dost thou limit
Thy lore unto calamity?[6] Why not
Unfold the rise of days more worthy thine
All-glorious burst from ocean? why not dart
A beam of hope athwart the future years,
As of wrath to its days? Hear me! oh, hear me!
I am thy worshiper, thy priest, thy servant—
I have gazed on thee at thy rise and fall,
And bow'd my head beneath thy mid-day beams,
When my eye dared not meet thee. I have watch'd
For thee, and after thee, and pray'd to thee,
And sacrificed to thee, and read, and fear'd thee,
And ask'd of thee, and thou hast answer'd—but
Only to thus much. While I speak, he sinks—
Is gone—and leaves his beauty, not his knowledge,
To the delighted west, which revels in
Its hues of dying glory. Yet what is
Death, so it be but glorious? 'T is a sunset;
And mortals may be happy to resemble
The gods but in decay."

Thus the Chaldean priest, to the brightness of the setting sun. Hear now the Greek girl, Myrrha, of his rising.

How often now—young maids of London,—do you make sunrise the 'haunted epoch' of either?

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 distemper 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 sub-species, or super-genera and super-species of cloud, perhaps we had better define what every cloud is, and must be, to begin with.

Every cloud that can be, is thus primarily definable: "Visible vapor of water floating at a certain height in the air." The second clause of this definition, you see, at once implies that there is such a thing as visible vapor of water which does not float at a certain height in the air. You are all familiar with one extremely cognizable variety of that sort of vapor—London Particular; but that especial blessing of metropolitan society is only a strongly-developed and highly-seasoned condition of a form of watery vapor which exists just as generally and widely at the bottom of the air, as the clouds do—on what, for convenience' sake, we may call the top of it;—only as yet, thanks to the sagacity of scientific men, we have got no general name for the bottom cloud, though the whole question of cloud nature begins in this broad fact, that you have one kind of vapor that lies to a certain depth on the ground, and another that floats at a certain height in the sky. Perfectly definite, in both cases, the surface level of the earthly vapor, and the roof level of the heavenly vapor, are each of them drawn within the depth of a fathom. Under their line, drawn for the day and for the hour, the clouds will not stoop, and above theirs, the mists will not rise. Each in their own region, high or deep, may expatiate at their pleasure; within that, they climb, or decline,—within that they congeal or melt away; but below their assigned horizon the surges of the cloud sea may not sink, and the floods of the mist lagoon may not be swollen.

That is the first idea you have to get well into your minds concerning the abodes of this visible vapor; next, you have to consider the manner of its visibility. Is it, you have to ask, with cloud vapor, as with most other things, that they are seen when they are there, and not seen when they are not there? or has cloud vapor 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 when we don't see it, as when we do? To which I answer, comfortably and generally, that, on the whole, a cloud is where you see it, and isn't where you don't; that, when there's an evident and honest thundercloud in the northeast, you needn't suppose there's a surreptitious and slinking one in the northwest;—when there's a visible fog at Bermondsey, it doesn't follow there's a spiritual one, more than usual, at the West End: and when you get up to the clouds, and can walk into them or out of them, as you like, you find when you're in them they wet your whiskers, or take out your curls, and when you're out of them, they don't; and therefore you may with probability assume—not with certainty, observe, but with probability—that there's more water in the air where it damps your curls than where it doesn't. If it gets much denser than that, it will begin to rain; and then you may assert, certainly with safety, that there is a shower in one place, and not in another; and not allow the scientific people to tell you that the rain is everywhere, but palpable in Tooley Street, and impalpable in Grosvenor Square.

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,[8]—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 yards off the funnel it scatters and melts away; a little of it sprinkles you with rain if you are underneath it, but the rest disappears; yet it is still there;—the surrounding air does not absorb it all into space in a moment; there is a gradually diffusing current of invisible moisture at the end of the visible stream—an invisible, yet quite substantial, vapor; but not, according to our definition, a cloud, for a cloud is vapor visible.

Then the next bit of the question, of course, is, What makes the vapor 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 vapor 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 difference of the state of a particle of water, which won't sink in the air, from that of one that won't rise in it?[9]

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 the kettle on in time for tea; powder your ice and salt, if you have a mind for ices; and obviate the chance of explosion by not making the gunpowder. But if, beyond this safe and beneficial business, they ever try to explain anything to you, you may be confident of one of two things,—either that they know nothing (to speak of) about it, or that they have only seen one side of it—and not only haven't seen, but usually have no mind to see, the other. When, for instance, Professor Tyndall explains the twisted beds of the Jungfrau to you by intimating that the Matterhorn is growing flat;[10] or the clouds on the lee side of the Matterhorn by the wind's rubbing against the windward side of it,[11]—you may be pretty sure the scientific people don't know much (to speak of) yet, either about rock-beds, or cloud-beds. And even if the explanation, so to call it, be sound on one side, windward or lee, you may, as I said, be nearly certain it won't do on the other. Take the very top and center of scientific interpretation by the greatest of its masters: Newton explained to you—or at least was once supposed to have explained—why an apple fell; but he never thought of explaining the exactly correlative, but infinitely more difficult question, how the apple got up there!

You will not, therefore, so please you, expect me to explain anything to you,—I have come solely and simply to put before you a few facts, which you can't see by candlelight, or in railroad tunnels, but which are making themselves now so very distinctly felt as well as seen, that you may perhaps have to roof, if not wall, half London afresh before we are many years older.

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 22d page of his 'Glaciers of the Alps,' Professor Tyndall says that "the marvelous blueness of the sky in the earlier part of the day indicated that the air was charged, almost to saturation, with transparent aqueous vapor." Well, in certain weather that is true. You all know the peculiar clearness which precedes rain,—when the distant hills are looking nigh. I take it on trust from the scientific people that there is then a quantity—almost to saturation—of aqueous vapor in the air, but it is aqueous vapor in a state which makes the air more transparent than it would be without it. What state of aqueous molecule is that, absolutely unreflective[12] of light—perfectly transmissive of light, and showing at once the color of blue water and blue air on the distant hills?

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 healthily clear, and the sun bright. If it is hot also, the next day is a little mistier—the next misty and sultry,—and the next and the next, getting thicker and thicker—end in another storm, or period of rain.

I suppose the thick air, as well as the transparent, is in both cases saturated with aqueous vapor;—but also in both, observe, vapor 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 vapor with a fresh rainy breeze, or the clear blue vapor as still as the sky above. What difference is there between these aqueous molecules that are clear, and those that are muddy, these that must sink or rise, and those that must stay where they are, these that have form and stature, that are bellied like whales and backed like weasels, and those that have neither backs nor fronts, nor feet nor faces, but are a mist—and no more—over two or three thousand square miles?

I again leave the questions with you, and pass on.

Hitherto I have spoken of all aqueous vapor as if it were either transparent or white—visible by becoming opaque like snow, but not by any accession of color. But even those of us who are least observant of skies, know that, irrespective of all supervening colors from the sun, there are white clouds, brown clouds, gray clouds, and black clouds. Are these indeed—what they appear to be—entirely distinct monastic disciplines of cloud: Black Friars, and White Friars, and Friars of Orders Gray? Or is it only their various nearness to us, their denseness, and the failing of the light upon them, that makes some clouds look black[13] and others snowy?

I can only give you qualified and cautious answer. There are, by differences in their own character, Dominican clouds, and there are Franciscan;—there are the Black Hussars of the Bandiera della Morte, and there are the Scots Grays whose horses can run upon the rock. But if you ask me, as I would have you ask me, why argent and why sable, how baptized in white like a bride or a novice, and how hooded with blackness like a Judge of the Vehmgericht Tribunal,—I leave these questions with you, and pass on.

Admitting degrees of darkness, we have next to ask what color, 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 moderately deep rose—you can't have lemon yellows, or any kind of green except in negative hue by opposition; and though by stormlight you may sometimes get the reds cast very deep, beyond a certain limit you cannot go,—the Alps are never vermilion color, nor flamingo color, nor canary color; nor did you ever see a full scarlet cumulus of thundercloud.

On opaque white vapor, then, remember, you can get a glow or a blush of color, never a flame of it.

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[14] from its atoms any force conceivable by human mind of the entire group of the golden and ruby colors, from intensely burnished gold color, 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 green blue nearer the horizon, form the scales and chords of color possible to the morning and evening sky in pure and fine weather; the keynote of the opposition being vermilion against green blue, both of equal tone, and at such a height and acme of brilliancy that you cannot see the line where their edges pass into each other.

No colors that can be fixed in earth can ever represent to you the luster 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 colors 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 that of the day. The diagram is enlarged from my careful sketch of the sunset of 1st October, 1868, at Abbeville, which was a beautiful example of what, in fine weather about to pass into storm, a sunset could then be, in the districts of Kent and Picardy unaffected by smoke. In reality, the ruby and vermilion clouds were, by myriads, more numerous than I have had time to paint: but the general character of their grouping is well enough expressed. All the illumined clouds are high in the air, and nearly motionless; beneath them, electric storm-cloud rises in a threatening cumulus on the right, and drifts in dark flakes across the horizon, casting from its broken masses radiating shadows on the upper clouds. These shadows are traced, in the first place by making the misty blue of the open sky more transparent, and therefore darker; and secondly, by entirely intercepting the sunbeams on the bars of cloud, which, within the shadowed spaces, show dark on the blue instead of light.

But, mind, all that is done by reflected light—and in that light you never get a green ray from the reflecting cloud; there is no such thing in nature as a green lighted cloud relieved from a red sky,—the cloud is always red, and the sky green, and green, observe, by transmitted, not reflected light.

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, diffracting, the sun's rays. The particles of this cloud are said—with what truth I know not[15]—to send the sunbeams round them instead of through them; somehow or other, at any rate, they resolve them into their prismatic elements; and then you have literally a kaleidoscope in the sky, with every color of the prism in absolute purity; but above all in force, now, the ruby red and the green,—with purple, and violet-blue, in a virtual equality, more definite than that of the rainbow. The red in the rainbow is mostly brick red, the violet, though beautiful, often lost at the edge; but in the prismatic cloud the violet, the green, and the ruby are all more lovely than in any precious stones, and they are varied as in a bird's breast, changing their places, depths, and extent at every instant.

The main cause of this change being, that the prismatic cloud itself is always in rapid, and generally in fluctuating motion. "A light veil of clouds had drawn itself," says Professor Tyndall, in describing his solitary ascent of Monte Rosa, "between me and the sun, and this was flooded with the most brilliant dyes. Orange, red, green, blue—all the hues produced by diffraction—were exhibited in the utmost splendor.

"Three times during my ascent (the short ascent of the last peak) similar veils drew themselves across the sun, and at each passage the splendid phenomena were renewed. There seemed a tendency to form circular zones of color round the sun; but the clouds were not sufficiently uniform to permit of this, and they were consequently broken into spaces, each steeped with the color due to the condition of the cloud at the place."

Three times, you observe, the veil passed, and three times another came, or the first faded and another formed; and so it is always, as far as I have registered prismatic cloud: and the most beautiful colors I ever saw were on those that flew fastest.

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 masking the form of, the mountain, known as the Old Man of Coniston.

The top of that dome of cloud is two thousand eight hundred feet above the sea, the mountain two thousand six hundred, the cloud lying two hundred feet deep on it. Behind it, westward and seaward, all's clear; but when the wind out of that blue clearness comes over the ridge of the earth-cloud, at that moment and that line, its own moisture congeals into these white—I believe, ice-clouds; threads, and meshes, and tresses, and tapestries, flying, failing, melting, reappearing; spinning and unspinning themselves, coiling and uncoiling, winding and unwinding, faster than eye or thought can follow: and through all their dazzling maze of frosty filaments shines a painted window in palpitation; its pulses of color interwoven in motion, intermittent in fire,—emerald and ruby and pale purple and violet melting into a blue that is not of the sky, but of the sunbeam;—purer than the crystal, softer than the rainbow, and brighter than the snow.

But you must please here observe that while my first diagram did with some adequateness represent to you the color facts there spoken of, the present diagram can only explain, not reproduce them. The bright reflected colors of clouds can be represented in painting, because they are relieved against darker colors, or, in many cases, are dark colors, the vermilion and ruby clouds being often much darker than the green or blue sky beyond them. But in the case of the phenomena now under your attention, the colors are all brighter than pure white,—the entire body of the cloud in which they show themselves being white by transmitted light, so that I can only show you what the colors are, and where they are,—but leaving them dark on the white ground. Only artificial, and very high illumination would give the real effect of them,—painting cannot.

Enough, however, is here done to fix in your minds the distinction between those two species of cloud,—one, either stationary,[16] 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,[17] instead of aqueous vapor; but the only clue I have to this idea is in the purity of the rainbow formed in frost mist, lying close to water surfaces. Such mist, however, only becomes prismatic as common rain does, when the sun is behind the spectator, while prismatic clouds are, on the contrary, always between the spectator and the sun.

The main reason, however, why I can tell you nothing yet about these colors 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, 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 confusion of idea also, in using the words undulation and vibration as synonyms. "When," says Professor Tyndall, "you are told that the atoms of the sun vibrate at different rates, and produce waves of different sizes,—your experience of water-waves will enable you to form a tolerably clear notion of what is meant."

'Tolerably clear'!—your toleration must be considerable, then. Do you suppose a water-wave is like a harp-string? Vibration is the movement of a body in a state of tension,—undulation, that of a body absolutely lax. In vibration, not an atom of the body changes its place in relation to another,—in undulation, not an atom of the body remains in the same place with regard to another. In vibration, every particle of the body ignores gravitation, or defies it,—in undulation, every particle of the body is slavishly submitted to it. In undulation, not one wave is like another; in vibration, every pulse is alike. And of undulation itself, there are all manner of visible conditions, which are not true conditions. A flag ripples in the wind, but it does not undulate as the sea does,—for in the sea, the water is taken from the trough to put on to the ridge, but in the flag, though the motion is progressive, the bits of bunting keep their place. You see a field of corn undulating as if it was water,—it is different from the flag, for the ears of corn bow out of their places and return to them,—and yet, it is no more like the undulation of the sea, than the shaking of an aspen leaf in a storm, or the lowering of the lances in a battle.

And the best of the jest is, that after mixing up these two notions in their heads inextricably, the scientific people apply both when neither will fit; and when all undulation known to us presumes weight, and all vibration, impact,—the undulating theory of light is proposed to you concerning a medium which you can neither weigh nor touch!

All communicable vibration—of course I mean—and in dead matter: You may fall a shivering on your own account, if you like, but you can't get a billiard-ball to fall a shivering on its own account.[18]

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 inexplicable, whatever manner of force, pulse, or palpitation may be instrumental in producing them: nor does any such force become light or sound, except in its rencontre with an animal. The leaf hears no murmur in the wind to which it wavers on the branches, nor can the clay discern the vibration by which it is thrilled into a ruby. The Eye and the Ear are the creators alike of the ray and the tone; and the conclusion follows logically from the right conception of their living power,—"He that planted the Ear, shall He not hear? He that formed the Eye, shall not He see?"

For security, therefore, and simplicity of definition of light, you will find no possibility of advancing beyond Plato's "the power that through the eye manifests color," but on that definition, you will find, alike by Plato and all great subsequent thinkers, a moral Science of Light founded, far and away more important to you than all the physical laws ever learned by vitreous revelation. Concerning which I will refer you to the sixth lecture which I gave at Oxford in 1872, on the relation of Art to the Science of Light ('The Eagle's Nest'), reading now only the sentence introducing its subject:—"The 'Fiat lux' of creation is therefore, in the deep sense, 'fiat anima,' and is as much, when you understand it, the ordering of Intelligence as the ordering of Vision. It is the appointment of change of what had been else only a mechanical effluence from things unseen to things unseeing,—from Stars, that did not shine, to Earth, that did not perceive,—the change, I say, of that blind vibration into the glory of the Sun and Moon for human eyes: so making possible the communication out of the unfathomable truth of that portion of truth which is good for us, and animating to us, and is set to rule over the day and over the night of our joy and our sorrow."

Returning now to our subject at the point from which I permitted myself, I trust not without your pardon, to diverge; you may incidentally, but carefully, observe, that the effect of such a sky as that represented in the second diagram, so far as it can be abstracted or conveyed by painting at all, implies the total absence of any pervading warmth of tint, such as artists usually call 'tone.' Every tint must be the purest possible, and above all the white. Partly, lest you should think, from my treatment of these two phases of effect, that I am insensible to the quality of tone,—and partly to complete the representation of states of weather undefiled by plague-cloud, yet capable of the most solemn dignity in saddening color, I show you, Diagram 3, the record of an autumn twilight of the year 1845,—sketched while I was changing horses between Verona and Brescia. The distant sky in this drawing is in the glowing calm which is always taken by the great Italian painters for the background of their sacred pictures; a broad field of cloud is advancing upon it overhead, and meeting others enlarging in the distance; these are rain-clouds, which will certainly close over the clear sky, and bring on rain before midnight: but there is no power in them to pollute the sky beyond and above them: they do not darken the air, nor defile it, nor in any way mingle with it; their edges are burnished by the sun like the edges of golden shields, and their advancing march is as deliberate and majestic as the fading of the twilight itself into a darkness full of stars.

These three instances are all I have time to give of the former conditions of serene weather, and of non-electric rain-cloud. But I must yet, to complete the sequence of my subject, show you one example of a good, old-fashioned, healthy, and mighty, storm.

In Diagram 4, Mr. Severn has beautifully enlarged my sketch of a July thundercloud of the year 1858, on the Alps of the Val d'Aosta, seen from Turin, that is to say, some twenty-five or thirty miles distant. You see that no mistake is possible here about what is good weather and what bad, or which is cloud and which is sky; but I show you this sketch especially to give you the scale of heights for such clouds in the atmosphere. These thunder cumuli entirely hide the higher Alps. It does not, however, follow that they have buried them, for most of their own aspect of height is owing to the approach of their nearer masses; but at all events, you have cumulus there rising from its base, at about three thousand feet above the plain, to a good ten thousand in the air.

White cirri, in reality parallel, but by perspective radiating, catch the sunshine above, at a height of from fifteen to twenty thousand feet; but the storm on the mountains gathers itself into a full mile's depth of massy cloud, every fold of it involved with thunder, but every form of it, every action, every color, magnificent:—doing its mighty work in its own hour and its own dominion, nor snatching from you for an instant, nor defiling with a stain, the abiding blue of the transcendent sky, or the fretted silver of its passionless clouds.

We so rarely now see cumulus cloud of this grand kind, that I will yet delay you by reading the description of its nearer aspect, in the 'Eagle's Nest.'

"The rain which flooded our fields the Sunday before last, was followed, as you will remember, by bright days, of which Tuesday the 20th (February, 1872) was, in London, notable for the splendor, towards the afternoon, of its white cumulus clouds. There has been so much black east wind lately, and so much fog and artificial gloom, besides, that I find it is actually some two years since I last saw a noble cumulus cloud under full light. I chanced to be standing under the Victoria Tower at Westminster, when the largest mass of them floated past, that day, from the northwest; and I was more impressed than ever yet by the awfulness of the cloud-form, and its unaccountableness, in the present state of our knowledge. The Victoria Tower, seen against it, had no magnitude: it was like looking at Mont Blanc over a lamp-post. The domes of cloud-snow were heaped as definitely: their broken flanks were as gray and firm as rocks, and the whole mountain, of a compass and height in heaven which only became more and more inconceivable as the eye strove to ascend it, was passing behind the tower with a steady march, whose swiftness must in reality have been that of a tempest: yet, along all the ravines of vapor, precipice kept pace with precipice, and not one thrust another.

"What is it that hews them out? Why is the blue sky pure there,—the cloud solid here; and edged like marble: and why does the state of the blue sky pass into the state of cloud, in that calm advance?

"It is true that you can more or less imitate the forms of cloud with explosive vapor or steam; but the steam melts instantly, and the explosive vapor dissipates itself. The cloud, of perfect form, proceeds unchanged. It is not an explosion, but an enduring and advancing presence. The more you think of it, the less explicable it will become to you."

Thus far then of clouds that were once familiar; now at last, entering on my immediate subject, I shall best introduce it to you by reading an entry in my diary which gives progressive description of the most gentle aspect of the modern plague-cloud.

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The first time I recognized the clouds brought by the plague-wind as distinct in character was in walking back from Oxford, after a hard day's work, to Abingdon, in the early spring of 1871: it would take too long to give you any account this evening of the particulars which drew my attention to them; but during the following months I had too frequent opportunities of verifying my first thoughts of them, and on the first of July in that year wrote the description of them which begins the 'Fors Clavigera' of August, thus:—

"It is the first of July, and I sit down to write by the dismalest light that ever yet I wrote by; namely, the light of this midsummer morning, in mid-England, (Matlock, Derbyshire), in the year 1871.

"For the sky is covered with gray cloud;—not rain-cloud, but a dry black veil, which no ray of sunshine can pierce; partly diffused in mist, feeble mist, enough to make distant objects unintelligible, yet without any substance, or wreathing, or color of its own. And everywhere the leaves of the trees are shaking fitfully, as they do before a thunder-storm; only not violently, but enough to show the passing to and fro of a strange, bitter, blighting wind. Dismal enough, had it been the first morning of its kind that summer had sent. But during all this spring, in London, and at Oxford, through meager March, through changelessly sullen April, through despondent May, and darkened June, morning after morning has come gray-shrouded thus.

"And it is a new thing to me, and a very dreadful one. I am fifty years old, and more; and since I was five, have gleaned the best hours of my life in the sun of spring and summer mornings; and I never saw such as these, till now.

"And the scientific men are busy as ants, examining the sun, and the moon, and the seven stars, and can tell me all about them, I believe, by this time; and how they move, and what they are made of.

"And I do not care, for my part, two copper spangles how they move, nor what they are made of. I can't move them any other way than they go, nor make them of anything else, better than they are made. But I would care much and give much, if I could be told where this bitter wind comes from, and what it is made of.

"For, perhaps, with forethought, and fine laboratory science, one might make it of something else.

"It looks partly as if it were made of poisonous smoke; very possibly it may be: there are at least two hundred furnace chimneys in a square of two miles on every side of me. But mere smoke would not blow to and fro in that wild way. It looks more to me as if it were made of dead men's souls—such of them as are not gone yet where they have to go, and may be flitting hither and thither, doubting, themselves, of the fittest place for them.

"You know, if there are such things as souls, and if ever any of them haunt places where they have been hurt, there must be many about us, just now, displeased enough!"

The last sentence refers of course to the battles of the Franco-German campaign, which was especially horrible to me, in its digging, as the Germans should have known, a moat flooded with waters of death between the two nations for a century to come.

Since that Midsummer day, my attention, however otherwise occupied, has never relaxed in its record of the phenomena characteristic of the plague-wind; and I now define for you, as briefly as possible, the essential signs of it.

1. It is a wind of darkness,—all the former conditions of tormenting winds, whether from the north or east were more or less capable of co-existing with sunlight, and often with steady and bright sunlight; but whenever, and wherever the plague-wind blows, be it but for ten minutes, the sky is darkened instantly.

2. It is a malignant quality of wind, unconnected with any one quarter of the compass; it blows indifferently from all, attaching its own bitterness and malice to the worst characters of the proper winds of each quarter. It will blow either with drenching rain, or dry rage, from the south,—with ruinous blasts from the west,—with bitterest chills from the north,—and with venomous blight from the east.

Its own favorite quarter, however, is the southwest, so that it is distinguished in its malignity equally from the Bise of Provence, which is a north wind always, and from our own old friend, the east.

3. It always blows tremulously, making the leaves of the trees shudder as if they were all aspens, but with a peculiar fitfulness which gives them—and I watch them this moment as I write—an expression of anger as well as of fear and distress. You may see the kind of quivering, and hear the ominous whimpering, in the gusts that precede a great thunderstorm; but plague-wind is more panic-struck, and feverish; and its sound is a hiss instead of a wail.

When I was last at Avallon, in South France, I went to see 'Faust' played at the little country theater: it was done with scarcely any means of pictorial effect, except a few old curtains, and a blue light or two. But the night on the Brocken was nevertheless extremely appalling to me,—a strange ghastliness being obtained in some of the witch scenes merely by fine management of gesture and drapery; and in the phantom scenes, by the half-palsied, half-furious, faltering or fluttering past of phantoms stumbling as into graves; as if of not only soulless, but senseless, Dead, moving with the very action, the rage, the decrepitude, and the trembling of the plague-wind.

4. Not only tremulous at every moment, it is also intermittent with a rapidity quite unexampled in former weather. There are, indeed, days—and weeks, on which it blows without cessation, and is as inevitable as the Gulf Stream; but also there are days when it is contending with healthy weather, and on such days it will remit for half an hour, and the sun will begin to show itself, and then the wind will come back and cover the whole sky with clouds in ten minutes; and so on, every half-hour, through the whole day; so that it is often impossible to go on with any kind of drawing in color, the light being never for two seconds the same from morning till evening.

5. It degrades, while it intensifies, ordinary storm; but before I read you any description of its efforts in this kind, I must correct an impression which has got abroad through the papers, that I speak as if the plague-wind blew now always, and there were no more any natural weather. On the contrary, the winter of 1878-9 was one of the most healthy and lovely I ever saw ice in;—Coniston lake shone under the calm clear frost in one marble field, as strong as the floor of Milan Cathedral, half a mile across and four miles down; and the first entries in my diary which I read you shall be from the 22d to 26th June, 1876, of perfectly lovely and natural weather.

These extracts are, I hope, enough to guard you against the absurdity of supposing that it all only means that I am myself soured, or doting, in my old age, and always in an ill humor. Depend upon it, when old men are worth anything, they are better humored than young ones; and have learned to see what good there is, and pleasantness, in the world they are likely so soon to have orders to quit.

Now then—take the following sequences of accurate description of thunderstorm, with plague-wind.

6. And now I come to the most important sign of the plague-wind and the plague-cloud: that in bringing on their peculiar darkness, they blanch the sun instead of reddening it. And here I must note briefly to you the uselessness of observation by instruments, or machines, instead of eyes. In the first year when I had begun to notice the specialty of the plague-wind, I went of course to the Oxford observatory to consult its registrars. They have their anemometer always on the twirl, and can tell you the force, or at least the pace, of a gale,[19] by day or night. But the anemometer can only record for you how often it has been driven round, not at all whether it went round steadily, or went round trembling. And on that point depends the entire question whether it is a plague breeze or a healthy one: and what's the use of telling you whether the wind's strong or not, when it can't tell you whether it's a strong medicine, or a strong poison?

But again—you have your sun-measure, and can tell exactly at any moment how strong, or how weak, or how wanting, the sun is. But the sun-measurer can't tell you whether the rays are stopped by a dense shallow cloud, or a thin deep one. In healthy weather, the sun is hidden behind a cloud, as it is behind a tree; and, when the cloud is past, it comes out again, as bright as before. But in plague-wind, the sun is choked out of the whole heaven, all day long, by a cloud which may be a thousand miles square and five miles deep.

And yet observe: that thin, scraggy, filthy, mangy, miserable cloud, for all the depth of it, can't turn the sun red, as a good, business-like fog does with a hundred feet or so of itself. By the plague-wind every breath of air you draw is polluted, half round the world; in a London fog the air itself is pure, though you choose to mix up dirt with it, and choke yourself with your own nastiness.

Now I'm going to show you a diagram of a sunset in entirely pure weather, above London smoke. I saw it and sketched it from my old post of observation—the top garret of my father's house at Herne Hill. There, when the wind is south, we are outside of the smoke and above it; and this diagram, admirably enlarged from my own drawing by my, now in all things best aide-de-camp, Mr. Collingwood, shows you an old-fashioned sunset—the sort of thing Turner and I used to have to look at,—(nobody else ever would) constantly. Every sunset and every dawn, in fine weather, had something of the sort to show us. This is one of the last pure sunsets I ever saw, about the year 1876,—and the point I want you to note in it is, that the air being pure, the smoke on the horizon, though at last it hides the sun, yet hides it through gold and vermilion. Now, don't go away fancying there's any exaggeration in that study. The prismatic colors, I told you, were simply impossible to paint; these, which are transmitted colors, can indeed be suggested, but no more. The brightest pigment we have would look dim beside the truth.

I should have liked to have blotted down for you a bit of plague-cloud to put beside this; but Heaven knows, you can see enough of it now-a-days without any trouble of mine; and if you want, in a hurry, to see what the sun looks like through it, you've only to throw a bad half-crown into a basin of soap and water.

Blanched Sun,—blighted grass,—blinded man.—If, in conclusion, you ask me for any conceivable cause or meaning of these things—I can tell you none, according to your modern beliefs; but I can tell you what meaning it would have borne to the men of old time. Remember, for the last twenty years, England, and all foreign nations, either tempting her, or following her, have blasphemed[20] the name of God deliberately and openly; and have done iniquity by proclamation, every man doing as much injustice to his brother as it is in his power to do. Of states in such moral gloom every seer of old predicted the physical gloom, saying, "The light shall be darkened in the heavens thereof, and the stars shall withdraw their shining." All Greek, all Christian, all Jewish prophecy insists on the same truth through a thousand myths; but of all the chief, to former thought, was the fable of the Jewish warrior and prophet, for whom the sun hasted not to go down, with which I leave you to compare at leisure the physical result of your own wars and prophecies, as declared by your own elect journal not fourteen days ago,—that the Empire of England, on which formerly the sun never set, has become one on which he never rises.

What is best to be done, do you ask me? The answer is plain. Whether you can affect the signs of the sky or not, you can the signs of the times. Whether you can bring the sun back or not, you can assuredly bring back your own cheerfulness, and your own honesty. You may not be able to say to the winds, "Peace; be still," but you can cease from the insolence of your own lips, and the troubling of your own passions. And all that it would be extremely well to do, even though the day were coming when the sun should be as darkness, and the moon as blood. But, the paths of rectitude and piety once regained, who shall say that the promise of old time would not be found to hold for us also?—"Bring ye all the tithes into my storehouse, and prove me now herewith, saith the Lord God, if I will not open you the windows of heaven, and pour you out a blessing, that there shall not be room enough to receive it."

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March 11th, 1884.

It was impossible for me, this spring, to prepare, as I wished to have done, two lectures for the London Institution: but finding its members more interested in the subject chosen than I had anticipated, I enlarged my lecture at its second reading by some explanations and parentheses, partly represented, and partly farther developed, in the following notes; which led me on, however, as I arranged them, into branches of the subject untouched in the former lecture, and it seems to me of no inferior interest.