1The buoyancy of solid bodies of a given specific gravity, in a given fluid, depends, first on their size, then on their forms.First, on their size; that is to say, on the proportion of the magnitude of the object (irrespective of the distribution of its particles) to the magnitude of the particles of the air.Thus, a grain of sand is buoyant in wind, but a large stone is not; and pebbles and sand are buoyant in water in proportion to their smallness, fine dust taking long to sink, while a large stone sinks at once. Thus, we see that water may be arranged in drops of any magnitude, from the largest rain-drop, about the size of a large pea, to an atom so small as not to be separately visible, the smallest rain passing gradually into mist. Of these drops of different sizes (supposing the strength of the wind the same), the largest fall fastest, the smaller drops are more buoyant, and the small misty rain floats about like a cloud, as often up as down, so that an umbrella is useless in it; though in a heavy thunder-storm, if there is no wind, one may stand gathered up under an umbrella without a drop touching the feet.Secondly, buoyancy depends on the amount of surface which a given weight of the substance exposes to the resistance of the substance it floats in. Thus, gold-leaf is in a high degree buoyant, while the same quantity of gold in a compact grain would fall like a shot; and a feather is buoyant, though the same quantity of animal matter in a compact form would be as heavy as a little stone. A slate blows far from a house-top, while a brick falls vertically, or nearly so.2There is a beautiful passage inSartor Resartusconcerning this old Hebrew scroll, in its deeper meanings, and the child’s watching it, though long illegible for him, yet “with an eye to the gilding.” It signifies in a word or two nearly all that is to be said about clouds.
1The buoyancy of solid bodies of a given specific gravity, in a given fluid, depends, first on their size, then on their forms.
First, on their size; that is to say, on the proportion of the magnitude of the object (irrespective of the distribution of its particles) to the magnitude of the particles of the air.
Thus, a grain of sand is buoyant in wind, but a large stone is not; and pebbles and sand are buoyant in water in proportion to their smallness, fine dust taking long to sink, while a large stone sinks at once. Thus, we see that water may be arranged in drops of any magnitude, from the largest rain-drop, about the size of a large pea, to an atom so small as not to be separately visible, the smallest rain passing gradually into mist. Of these drops of different sizes (supposing the strength of the wind the same), the largest fall fastest, the smaller drops are more buoyant, and the small misty rain floats about like a cloud, as often up as down, so that an umbrella is useless in it; though in a heavy thunder-storm, if there is no wind, one may stand gathered up under an umbrella without a drop touching the feet.
Secondly, buoyancy depends on the amount of surface which a given weight of the substance exposes to the resistance of the substance it floats in. Thus, gold-leaf is in a high degree buoyant, while the same quantity of gold in a compact grain would fall like a shot; and a feather is buoyant, though the same quantity of animal matter in a compact form would be as heavy as a little stone. A slate blows far from a house-top, while a brick falls vertically, or nearly so.
2There is a beautiful passage inSartor Resartusconcerning this old Hebrew scroll, in its deeper meanings, and the child’s watching it, though long illegible for him, yet “with an eye to the gilding.” It signifies in a word or two nearly all that is to be said about clouds.
CHAPTER II.
THE CLOUD-FLOCKS.
§ 1. Fromthe tenor of the foregoing chapter, the reader will, I hope, be prepared to find me, though dogmatic (it is said) upon some occasions, anything rather than dogmatic respecting clouds. I will assume nothing concerning them, beyond the simple fact, that as a floating sediment forms in a saturated liquid, vapor forms in the body of the air; and all that I want the reader to be clear about in the outset is that this vapor floats in and with the wind (as, if you throw any thick coloring matter into a river, it floats with the stream), and that it is not blown before a denser volume of the wind, as a fleece of wool would be.
§ 2. At whatever height they form, clouds may be broadly considered as of two species only, massive and striated. I cannot find a better word than massive, though it is not a good one, for I mean it only to signify a fleecy arrangement in which nolinesare visible. The fleece may be so bright as to look like flying thistle-down, or so diffused as to show no visible outline at all. Still if it is all of one common texture, like a handful of wool, or a wreath of smoke, I call it massive.
On the other hand, if divided by parallel lines, so as to look more or less like spun-glass, I call it striated. In Plate 69, Fig. 4, the top of the Aiguille Dru (Chamouni) is seen emergent above low striated clouds, with heaped massive cloud beyond. I do not know in the least what causes this striation, except that it depends on the nature of the cloud, not on the wind. The strongest wind will not throw a cloud, massive by nature, into the linear form. It will toss it about, and tear it to pieces, but not spin it into threads. On the other hand, often without any wind at all, the cloud will spin itself into threads fine as gossamer. These threads are often said to be a prognostic of storm; but they are not produced by storm.
§ 3. In the first volume, we considered all clouds as belonging to three regions, that of the cirrous, the central cloud, and the rain-cloud. It is of course an arrangement more of convenience than of true description, for cirrous clouds sometimes form low as well as high; and rain sometimes falls high as well as low. I will, nevertheless, retain this old arrangement, which is practically as serviceable as any.
Allowing, also, for various exceptions and modifications, these three bodies of cloud may be generally distinguished in our minds thus. The clouds of upper region are for the most part quiet, or seem to be so, owing to their distance. They are formed now of striated, now of massive substance; but always finely divided into large ragged flakes or ponderous heaps. These heaps (cumuli) and flakes, or drifts, present different phenomena, but must be joined in our minds under the head of central cloud. The lower clouds, bearing rain abundantly, are composed partly of striated, partly of massive substance; but may generally be comprehended under the term rain-cloud.
Our business in this chapter, then, is with the upper clouds, which, owing to their quietness and multitude, we may perhaps conveniently think of as the “cloud-flocks.” And we have to discover if any laws of beauty attach to them, such as we have seen in mountains or tree-branches.
§ 4. On one of the few mornings of this winter, when the sky was clear, and one of the far fewer, on which its clearness was visible from the neighborhood of London,—which now entirely loses at least two out of three sunrises, owing to the environing smoke,—the dawn broke beneath a broad field of level purple cloud, under which floated ranks of divided cirri, composed of finely striated vapor.
It was not a sky containing any extraordinary number of these minor clouds; but each was more than usually distinct in separation from its neighbor, and as they showed in nearly pure pale scarlet on the dark purple ground, they were easily to be counted.
§ 5. There were five or six ranks, from the zenith to the horizon; that is to say, three distinct ones, and then two or three more running together, and losing themselves in distance, in the manner roughly shown in Fig. 79. The nearest rank was composed of more than 150 rows of cloud, set obliquely, as in thefigure. I counted 150 which was near the mark, and then stopped, lest the light should fail, to count the separate clouds in some of the rows. The average number was 60 in each row, rather more than less.
There were therefore 150×60, that is, 9,000, separate clouds in this one rank, or about 50,000 in the field of sight. Flocks of Admetus under Apollo’s keeping. Who else could shepherd such? He by day, dog Sirius by night; or huntress Diana herself—her bright arrows driving away the clouds of prey that would ravage her fair flocks. We must leave fancies, however; these wonderful clouds need close looking at. I will try to draw one or two of them before they fade.
§ 6. On doing which we find, after all, they are not much more like sheep than Canis Major is like a dog. They resemble more some of our old friends, the pine branches, covered with snow. The three forming the uppermost figure, in the Plate opposite, are as like three of the fifty thousand as I could get them, complex enough in structure, even this single group. Busy workers they must be, that twine the braiding of them all to the horizon, and down beyond it.
And who are these workers? You have two questions here, both difficult. What separates these thousands of clouds each from the other, and each about equally from the other? How can they be drawn asunder, yet not allowed to part? Looped lace as it were, richest point—invisible threads fastening embroidered cloud to cloud—the “plighted clouds” of Milton,—creatures of the element—
“That in the colors of the rainbow liveAnd play in the plighted clouds.”
“That in the colors of the rainbow live
And play in the plighted clouds.”
Compare Geraldine dressing:—
“Puts on her silken vestments white,And tricks her hair in lovely plight.”
“Puts on her silken vestments white,
And tricks her hair in lovely plight.”
And Britomart’s—
“Her well-plighted frockShe low let fall, that flowed from her lanck sideDown to her foot, with careless modesty.”
“Her well-plighted frock
She low let fall, that flowed from her lanck side
Down to her foot, with careless modesty.”
And, secondly, what bends each of them into these flame-like curves, tender and various, as motions of a bird, hither and thither? Perhaps you may hardly see the curves well in the softly finished forms; here they are plainer in rude outline, Fig. 80.1
§ 7. What is it that throws them into these lines?
Eddies of wind?
Nay, an eddy of wind will not stay quiet for three minutes, as that cloud did to be drawn; as all the others did, each in hisplace. You see there is perfect harmony among the curves. They all flow into each other as the currents of a stream do. If you throw dust that will float on the surface of a slow river, it will arrange itself in lines somewhat like these. To a certain extent, indeed, it is true that there are gentle currents of change in the atmosphere, which move slowly enough to permit in the clouds that follow them some appearance of stability. But how to obtain change so complex in an infinite number of consecutive spaces;—fifty thousand separate groups of current in half of a morning sky, with quiet invisible vapor between, or none—and yet all obedient to one ruling law, gone forth through their companies;—each marshalled to their white standards, in great unity of warlike march, unarrested, unconfused? “One shall not thrust another, they shall walk every one in his own path.”
§ 8. These questions occur, at first sight, respecting every group of cirrus cloud. Whatever the form may be, whether branched, as in this instance, or merely rippled, or thrown into shield-like segments, as in Fig. 81—a frequent arrangement—there is still the same difficulty in accounting satisfactorily for the individual forces which regulate the similar shape of each mass, while all are moved by a general force that has apparently no influence on the divided structure. Thus the mass of clouds disposed as in Fig. 81, will probably move, mutually, in the direction of the arrow; that is to say, sideways, as far as their separate curvature is concerned. I suppose it probable that as the science of electricity is more perfectly systematized, the explanation of many circumstances of cloud-form will be rendered by it. At present I see no use in troubling the reader or myself with conjectures which a year’s progress in science might either effectively contradict or supersede. All that I want is, that we should have our questions ready to put clearly to the electricians when the electricians are ready to answer us.
§ 9. It is possible that some of the loveliest conditions ofthese parallel clouds may be owing to a structure which I forgot to explain, when it occurred in rocks, in the course of the last volume.
When they are finely stratified, and their surfaces abraded by broad, shallow furrows, the edges of the beds, of course, are thrown into undulations, and at some distance, where the furrows disappear, the surface looks as if the rock had flowed over it in successive waves. Such a condition is seen on the left at the top in Fig. 17, in Vol. IV. Supposing a series of beds of vapor cut across by a straight sloping current of air, and so placed as to catch the light on their edges, we should have a series of curved lights, looking like independent clouds.
§ 10. I believe conditions of form like those in Fig. 82 (turn the book with its outer edge down) may not unfrequently be thus, owing to stratification, when they occur in the nearer sky. This line of cloud is far off at the horizon, drifting towards the left (the points of course forward), and is, I suppose, a series of nearly circular eddies seen in perspective.
Which question of perspective we must examine a little before going a step farther. In order to simplify it, let us assume that the under surfaces of clouds are flat, and lie in a horizontal extended field. This is in great measure the fact, and notable perspective phenomena depend on the approximation of clouds to such a condition.
§ 11. Referring the reader to my Elements of Perspective for statements of law which would be in this place tiresome, I can only ask him to take my word for it that the three figures in Plate 64 represent limiting lines of sky perspective, as they would appear over a large space of the sky. Supposing that the breadth included was one-fourth of the horizon, the shaded portions in the centralfigure represent square fields of cloud,2and those in the uppermost figure narrow triangles, with their shortest side next us, but sloping a little away from us.
In each figure, the shaded portions show the perspective limits of cloud-masses, which, in reality, are arranged in perfectly straight lines, are all similar, and are equidistant from each other. Their exact relative positions are marked by the lines connecting them, and may be determined by the reader if he knows perspective. If he does not, he may be surprised at first to be told that the stubborn and blunt little triangle,b, Fig. 1, Plate 64, represents a cloud precisely similar, and similarly situated, to that represented by the thin triangle,a; and, in like manner, the stout diamond,a, Fig. 2, represents precisely the same form and size of cloud as the thin strip atb. He may perhaps think it still more curious that the retiring perspective which causes stoutness in the triangle, causes leanness in the diamond.3
§ 12. Still greater confusion in aspect is induced by the apparent change caused by perspective in the direction of the wind. If Fig. 3 be supposed to include a quarter of the horizon, the spaces, into which its straight lines divide it, represent squares of sky. The curved lines, which cross these spaces from corner to corner, are precisely parallel throughout; and, therefore, two clouds moving, one on the curved line fromatob, and the other on the other side, fromctod, would, in reality, be moving with the same wind, in parallel lines. In Plate 66, which is a sketch of an actual sunset behind Beauvais cathedral (the point of the roof of the apse, a little to the left of the centre, shows it to be a summer sunset), the white cirri in the high light are all moving eastward, away from the sun, in perfectly parallel lines, curving a little round to the south. Underneath, are two straight ranks of rainy cirri, crossing each other; one directed south-east; the other, north-west. The meeting perspective of these, in extreme distance, determines the shape of the angular light whichopens above the cathedral. Underneath all, fragments of true rain-cloud are floating between us and the sun, governed by curves of their own. They are, nevertheless, connected with the straight cirri, by the dark semi-cumulus in the middle of the shade above the cathedral.
§ 13. Sky perspective, however, remains perfectly simple, so long as it can be reduced to any rectilinear arrangement; but when nearly the whole system is curved, which nine times out of ten is the case, it becomes embarrassing. The central figure in Plate 65 represents the simplest possible combination of perspective of straight lines with that of curves, a group of concentric circles of small clouds being supposed to cast shadows from the sun near the horizon. Such shadows are often cast in misty air; the aspect of rays about the sun being, in fact, only caused by spaces between them. They are carried out formally and far in the Plate, to show how curiously they may modify the arrangement of light in a sky. The woodcut, Fig. 83, gives roughly the arrangement of the clouds in Turner’s Pools of Solomon, in which he has employed a concentric system of circles of this kind, and thus lighted. In the perspective figure the clouds are represented as small square masses, for the sake of greater simplicity, and are so beaded or strung as it were on the curves in whichthey move, as to keep their distances precisely equal, and their sides parallel. This is the usual condition of cloud: for though arranged in curved ranks, each cloud has its face to the front, or, at all events, acts in some parallel line—generally another curve—with those next to it: being rarely, except in the form of fine radiating striæ, arranged on the curves as ata, Fig. 84; but as atb, orc. It would make the diagram too complex if I gave one of intersecting curves; but the lowest figure in Plate 65 represents, in perspective, two groups of ellipses arranged in equidistant straight and parallel lines, and following each other on two circular curves. Their exact relative position is shown in Fig. 2, Plate 56. While the uppermost figure in Plate 65 represents, in parallel perspective, a series of ellipses arranged in radiation on a circle, their exact relative size and position are shown in Fig. 3, Plate 56, and the lines of such a sky as would be produced by them, roughly, in Fig. 90, facing page 128.4
§ 14. And in these figures, which, if we look up the subject rightly, would be but the first and simplest of the series necessary to illustrate the action of the upper cirri, the reader may see, at once, how necessarily painters, untrained in observance of proportion, and ignorant of perspective, must lose in every touch the expression of buoyancy and space in sky. The absolute forms of each cloud are, indeed, not alike, as the ellipses in the engraving; but assuredly, when moving in groups of this kind, there are among them the same proportioned inequalities of relative distance, the same gradated changes from ponderous toelongated form, the same exquisite suggestions of including curve; and a common painter, dotting his clouds down at random, or in more or less equal masses, can no more paint a sky, than he could, by random dashes for its ruined arches, paint the Coliseum.
§ 15. Whatever approximation to the character of upper clouds may have been reached by some of our modern students, it will be found, on careful analysis, that Turner stands more absolutely alone in this gift of cloud-drawing, than in any other of his great powers. Observe, I say, cloud-drawing; other great men colored clouds beautifully; none but he ever drew them truly: this power coming from his constant habit of drawing skies, like everything else, with the pencil point. It is quite impossible to engrave any of his large finished skies on a small scale; but the woodcut, Fig. 85, will give some idea of the forms of cloud involved in one of his small drawings. It is only half of the sky in question, that of Rouen from St. Catherine’s Hill, in the Rivers of France. Its clouds are arranged on two systems of intersecting circles, crossed beneath by long bars very slightly bent. The form of every separate cloud is completely studied; the manner of drawing them will be understood better by help of the Plate opposite, which is a piece of the sky above the “Campo Santo,”5at Venice, exhibited in 1842. It is exquisite in rounding of the separate fragments and buoyancy of the rising central group, as well as in its expression of the wayward influence of curved lines of breeze on a generally rectilinear system of cloud.
§ 16. To follow the subject farther would, however, lead us into doctrine of circular storms, and all kinds of pleasant, but infinite, difficulty, from which temptation I keep clear, believing that enough is now stated to enable the reader to understand what he is to look for in Turner’s skies; and what kind of power, thought, and science are involved continually in the little white or purple dashes of cloud-spray, which, in such pictures as the San Benedetto, looking to Fusina, the Napoleon, or the Temeraire, guide the eye to the horizon more by their true perspectivethan by their aërial tone, and are buoyant, not so much by expression of lightness as of motion.6
§ 17. I say the “white or purple” cloud-spray. One word yet may be permitted me respecting the mystery of that color. What should we have thought—if we had lived in a country where there were no clouds, but only low mist or fog—of any stranger who had told us that, in his country, these mists rose into the air, and became purple, crimson, scarlet, and gold? I am aware of no sufficient explanation of these hues of the upper clouds, nor of their strange mingling of opacity with a power of absorbing light. All clouds are so opaque that, however delicate they may be, you never see one through another. Six feet depth of them, at a little distance, will wholly veil the darkest mountain edge; so that, whether for light or shade, they tell upon the sky as body color on canvas; they have always a perfect surface and bloom;—delicate as a rose-leaf, when required of them, but never poor or meagre in hue, like old-fashioned water-colors. And, if needed, in mass, they will bear themselves for solid force of hue against any rock. Facing p. 339, I have engraved a memorandum made of a clear sunset after rain, from the top of Milan cathedral. The greater part of the outline is granite—Monte Rosa—the rest cloud; but it and the granite were dark alike. Frequently, in effects of this kind, the cloud is darker of the two.7And this opacity is, nevertheless, obtained without destroying the gift they have of letting broken light through them, so that, between us and the sun, they may become golden fleeces, and float as fields of light.
Now their distant colors depend on these two properties together;partly on the opacity, which enables them to reflect light strongly; partly on a spongelike power of gathering light into their bodies.
§ 18. Long ago it was noted by Aristotle, and again by Leonardo, that vaporous bodies looked russet, or even red, when warm light was seen through them, and blue when deep shade was seen through them. Both colors may, generally, be seen on any wreath of cottage smoke.
Whereon, easy conclusion has sometimes been founded by modern reasoners. All red in sky is caused by light seen through vapor, and all blue by shade seen through vapor.
Easy, indeed, but not sure, even in cloud-color only. It is true that the smoke of a town may be of a rich brick red against golden twilight; and of a very lovely, though not bright, blue against shade. But I never saw crimson or scarlet smoke, nor ultramarine smoke.
Even granting that watery vapor in its purity may give the colors more clearly, the red colors are by no means always relieved against light. The finest scarlets are constantly seen in broken flakes on a deep purple ground of heavier cloud beyond, and some of the loveliest rose-colors on clouds in the east, opposite the sunset, or in the west in the morning. Nor are blues always attainable by throwing vapor over shade. Especially, you cannot get them by putting it over blue itself. A thin vapor on dark blue sky is of a warm gray, not blue. A thunder-cloud, deep enough to conceal everything behind it, is often dark lead-color, or sulphurous blue; but the thin vapors crossing it, milky-white. The vividest hues are connected also with another attribute of clouds, their lustre—metallic in effect, watery in reality. They not only reflect color as dust or wool would, but, when far off, as water would; sometimes even giving a distinct image of the sun underneath the orb itself;—in all cases becoming dazzling in lustre, when at a low angle, capable of strong reflection. Practically, this low angle is only obtained when the cloud seems near the sun, and hence we get into the careless habit of looking at the golden reflected light as if it were actually caused by nearness to the fiery ball.
§ 19. Without, however, troubling ourselves at all about laws, or causes of color, the visible consequences of their operation arenotably these—that when near us, clouds present only subdued and uncertain colors; but when far from us, and struck by the sun on their under surfaces—so that the greater part of the light they receive is reflected—they may become golden, purple, scarlet, and intense fiery white, mingled in all kinds of gradations, such as I tried to describe in the chapter on the upper clouds in the first volume, in hope of being able to return to them “when we knew what was beautiful.”
The question before us now is, therefore, What value ought this attribute of clouds to possess in the human mind? Ought we to admire their colors, or despise them? Is it well to watch them as Turner does, and strive to paint them through all deficiency and darkness of inadequate material? Or, is it wiser and nobler—like Claude, Salvator, Ruysdael, Wouvermans—never to look for them—never to portray? We must yet have patience a little before deciding this, because we have to ascertain some facts respecting the typical meaning of color itself; which, reserving for another place, let us proceed here to learn the forms of the inferior clouds.
1Before going farther, I must say a word or two respecting method of drawing clouds.Absolutely well no cloudcanbe drawn with the point; nothing but the most delicate management of the brush will express its variety of edge and texture. By laborious and tender engraving, a close approximation may be obtained either to nature or to good painting; and the engravings of sky by our modern line engravers are often admirable;—in many respects as good as can be, and to my mind the best part of their work. There still exist some early proofs of Miller’s plate of the Grand Canal, Venice, in which the sky is the likest thing to Turner’s work I have ever seen in large engravings. The plate was spoiled after a few impressions were taken off by desire of the publisher. The sky was so exactly like Turner’s that he thought it would not please the public, and had all the fine cloud-drawing rubbed away to make it soft.The Plate opposite page 118, by Mr. Armytage, is also, I think, a superb specimen of engraving, though in result not so good as the one just spoken of, because this was done from my copy of Turner’s sky, not from the picture itself.But engraving of this finished kind cannot, by reason of its costliness, be given for every illustration of cloud form. Nor, if it could, can skies be sketched with the completion which would bear it. It is sometimes possible to draw one cloud out of fifty thousand with something like fidelity before it fades. But if we want the arrangement of the fifty thousand, they can only be indicated with the rudest lines, and finished from memory. It was, as we shall see presently, only by his gigantic powers of memory that Turner was enabled to draw skies as he did.Now, I look upon my own memory of clouds, or of anything else, as of no value whatever. All the drawings on which I have ever rested an assertion have been made without stirring from the spot; and in sketching clouds from nature, it is very seldom desirable to use the brush. For broad effects and notes of color (though these, hastily made, are always inaccurate, and letters indicating the color do nearly as well) the brush may be sometimes useful, but, in most cases, a dark pencil, which will lay shade with its side and draw lines with its point, is the best instrument. Turner almost always outlined merely with the point, being able to remember the relations of shade without the slightest chance of error. The point, at all events, is needful, however much stump work may be added to it.Now, in translating sketches made with the pencil point into engraving, we must either engrave delicately and expensively, or be content to substitute for the soft varied pencil lines the finer and uncloudlike touches of the pen. It is best to do this boldly, if at all, and without the least aim at fineness of effect, to lay down a vigorous black line as the limit of the cloud form or action. The more subtle a painter’s finished work, the more fearless he is in using the vigorous black line when he is making memoranda, of treating his subject conventionally. At the top of page 224, Vol. IV., the reader may see the kind of outline which Titian uses for clouds in his pen work. Usually he is even bolder and coarser. And in the rude woodcuts I am going to employ here, I believe the reader will find ultimately that, with whatever ill success used by me, the means of expression are the fullest and most convenient that can be adopted, short of finished engraving, while there are some conditions of cloud-action which I satisfy myself better in expressing by these coarse lines than in any other way.2If the figures are supposed to include less than one-fourth of the horizon, the shaded figures represent diamond-shaped clouds; but the reader cannot understand this without studying perspective laws accurately.3In reality, the retiring ranks of cloud, if long enough, would, of course, go on converging to the horizon. I do not continue them, because the figures would become too compressed.4I use ellipses in order to make these figures easily intelligible; the curves actuallyarevariable curves, of the nature of the cycloid, or other curves of continuous motion; probably produced by a current moving in some such direction as that indicated by the dotted line in Fig. 3, Plate 56.5Now in the possession of E. Bicknell, Esq., who kindly lent me the picture, that I might make this drawing from it carefully.6I cannot yet engrave these; but the little study of a single rank of cirrus, the lowest in Plate 63, may serve to show the value of perspective in expressing buoyancy. It is not, however, though beautifully engraved by Mr. Armytage, as delicate as it should be, in the finer threads which indicate increasing distance at the extremity. Compare the rising of the lines of curve at the edges of this mass, with the similar action on a larger scale, of Turner’s cloud, opposite.7In the autobiography of John Newton there is an interesting account of the deception of a whole ship’s company by cloud, taking the aspect and outline of mountainous land. They ate the last provision in the ship, so sure were they of its being land, and were nearly starved to death in consequence.
1Before going farther, I must say a word or two respecting method of drawing clouds.
Absolutely well no cloudcanbe drawn with the point; nothing but the most delicate management of the brush will express its variety of edge and texture. By laborious and tender engraving, a close approximation may be obtained either to nature or to good painting; and the engravings of sky by our modern line engravers are often admirable;—in many respects as good as can be, and to my mind the best part of their work. There still exist some early proofs of Miller’s plate of the Grand Canal, Venice, in which the sky is the likest thing to Turner’s work I have ever seen in large engravings. The plate was spoiled after a few impressions were taken off by desire of the publisher. The sky was so exactly like Turner’s that he thought it would not please the public, and had all the fine cloud-drawing rubbed away to make it soft.
The Plate opposite page 118, by Mr. Armytage, is also, I think, a superb specimen of engraving, though in result not so good as the one just spoken of, because this was done from my copy of Turner’s sky, not from the picture itself.
But engraving of this finished kind cannot, by reason of its costliness, be given for every illustration of cloud form. Nor, if it could, can skies be sketched with the completion which would bear it. It is sometimes possible to draw one cloud out of fifty thousand with something like fidelity before it fades. But if we want the arrangement of the fifty thousand, they can only be indicated with the rudest lines, and finished from memory. It was, as we shall see presently, only by his gigantic powers of memory that Turner was enabled to draw skies as he did.
Now, I look upon my own memory of clouds, or of anything else, as of no value whatever. All the drawings on which I have ever rested an assertion have been made without stirring from the spot; and in sketching clouds from nature, it is very seldom desirable to use the brush. For broad effects and notes of color (though these, hastily made, are always inaccurate, and letters indicating the color do nearly as well) the brush may be sometimes useful, but, in most cases, a dark pencil, which will lay shade with its side and draw lines with its point, is the best instrument. Turner almost always outlined merely with the point, being able to remember the relations of shade without the slightest chance of error. The point, at all events, is needful, however much stump work may be added to it.
Now, in translating sketches made with the pencil point into engraving, we must either engrave delicately and expensively, or be content to substitute for the soft varied pencil lines the finer and uncloudlike touches of the pen. It is best to do this boldly, if at all, and without the least aim at fineness of effect, to lay down a vigorous black line as the limit of the cloud form or action. The more subtle a painter’s finished work, the more fearless he is in using the vigorous black line when he is making memoranda, of treating his subject conventionally. At the top of page 224, Vol. IV., the reader may see the kind of outline which Titian uses for clouds in his pen work. Usually he is even bolder and coarser. And in the rude woodcuts I am going to employ here, I believe the reader will find ultimately that, with whatever ill success used by me, the means of expression are the fullest and most convenient that can be adopted, short of finished engraving, while there are some conditions of cloud-action which I satisfy myself better in expressing by these coarse lines than in any other way.
2If the figures are supposed to include less than one-fourth of the horizon, the shaded figures represent diamond-shaped clouds; but the reader cannot understand this without studying perspective laws accurately.
3In reality, the retiring ranks of cloud, if long enough, would, of course, go on converging to the horizon. I do not continue them, because the figures would become too compressed.
4I use ellipses in order to make these figures easily intelligible; the curves actuallyarevariable curves, of the nature of the cycloid, or other curves of continuous motion; probably produced by a current moving in some such direction as that indicated by the dotted line in Fig. 3, Plate 56.
5Now in the possession of E. Bicknell, Esq., who kindly lent me the picture, that I might make this drawing from it carefully.
6I cannot yet engrave these; but the little study of a single rank of cirrus, the lowest in Plate 63, may serve to show the value of perspective in expressing buoyancy. It is not, however, though beautifully engraved by Mr. Armytage, as delicate as it should be, in the finer threads which indicate increasing distance at the extremity. Compare the rising of the lines of curve at the edges of this mass, with the similar action on a larger scale, of Turner’s cloud, opposite.
7In the autobiography of John Newton there is an interesting account of the deception of a whole ship’s company by cloud, taking the aspect and outline of mountainous land. They ate the last provision in the ship, so sure were they of its being land, and were nearly starved to death in consequence.
CHAPTER III.
THE CLOUD-CHARIOTS.
§ 1. Betweenthe flocks of small countless clouds which occupy the highest heavens, and the gray undivided film of the true rain-cloud, form the fixed masses or torn fleeces, sometimes collected and calm, sometimes fiercely drifting, which are, nevertheless, known under one general name of cumulus, or heaped cloud.
The true cumulus, the most majestic of all clouds, and almost the only one which attracts the notice of ordinary observers, is for the most part windless; the movement of its masses being solemn, continuous, inexplicable, a steady advance or retiring, as if they were animated by an inner will, or compelled by an unseen power. They appear to be peculiarly connected with heat, forming perfectly only in the afternoon, and melting away in the evening. Their noblest conditions are strongly electric, and connect themselves with storm-cloud and true thunder-cloud. When there is thunder in the air, they will form in cold weather, or early in the day.
§ 2. I have never succeeded in drawing a cumulus. Its divisions of surface are grotesque and endless, as those of a mountain;—perfectly defined, brilliant beyond all power of color, and transitory as a dream. Even Turner never attempted to paint them, any more than he did the snows of the high Alps.
Nor can I explain them any more than I can draw them. The ordinary account given of their structure is, I believe, that the moisture raised from the earth by the sun’s heat becomes visible by condensation at a certain height in the colder air, that the level of the condensing point is that of the cloud’s base, and that above it, the heaps are pushed up higher and higher as more vapor accumulates, till, towards evening, the supply beneath ceases; and at sunset, the fall of dew enables the surroundingatmosphere to absorb and melt them away. Very plausible. But it seems to me herein unexplained how the vapor is held together in those heaps. If the clear air about and above it has no aqueous vapor in it, or at least a much less quantity, why does not the clear air keep pulling the cloud to pieces, eating it away, as steam is consumed in open air? Or, if any cause prevents such rapid devouring of it, why does not the aqueous vapor diffuse itself softly in the air like smoke, so that one would not know where the cloud ended? What should make it bind itself in those solid mounds, and stay so:—positive, fantastic, defiant, determined?
§ 3. If ever I am able to understand the process of the cumulus formation,1it will become to me one of the most interesting of all subjects of study to trace the connection of the threatening and terrible outlines of thunder-cloud with the increased action of the electric power. I am for the present utterly unable to speak respecting this matter, and must pass it by, in all humility, to say what little I have ascertained respecting the more broken and rapidly moving forms of the central clouds, which connect themselves with mountains, and may, therefore, among mountains, be seen close and truly.
§ 4. Yet even of these, I can only reason with great doubt and continual pause. This last volume ought certainly to be better than the first of the series, for two reasons. I have learned, during the sixteen years, to say little where I said much, and to see difficulties where I saw none. And I am in a great state of marvel in looking back to my first account of clouds, not only at myself, but even at my dear master, M. de Saussure. To think that both of us should have looked at drifting mountain clouds, for years together, and been content with the theory which you will find set forth in § 4, of the chapter on the central cloud region (Vol. I.), respecting the action of the snowy summits and watery vapor passing them. It is quite true that this action takes place, and that the said fourth paragraph is right, as far as itreaches. But both Saussure and I ought to have known—we both did know, but did not think of it—that the covering or cap-cloud forms on hot summits as well as cold ones;—that the red and bare rocks of Mont Pilate, hotter, certainly, after a day’s sunshine than the cold storm-wind which sweeps to them from the Alps, nevertheless have been renowned for their helmet of cloud, ever since the Romans watched the cloven summit, gray against the south, from the ramparts of Vindonissa, giving it the name from which the good Catholics of Lucerne have warped out their favorite piece of terrific sacred biography.2And both my master and I should also have reflected, that if our theory about its formation had been generally true, the helmet cloud ought to form on every cold summit, at the approach of rain, in approximating proportions to the bulk of the glaciers; which is so far from being the case that not only (A) the cap-cloud may often be seen on lower summits of grass or rock, while the higher ones are splendidly clear (which may be accounted for by supposing the wind containing the moisture not to have risen so high), but (B) the cap-cloud always shows a preference for hills of a conical form, such as the Mole or Niesen, which can have very little power in chilling the air, even supposing they were cold themselves, while it will entirely refuse to form round huge masses of mountain, which, supposing them of chilly temperament, must have discomforted the atmosphere in their neighborhood for leagues. And finally (C) reversing the principle under letter A, the cap-cloud constantly forms on the summit of Mont Blanc, while it will obstinately refuse to appear on the Dome du Goûte or Aiguille Sans-nom, where the snow-fields are of greater extent, and the air must be moister, because lower.
§ 5. The fact is, that the explanation given in that fourth paragraph can, in reality, account only for what may properly be termed “lee-side cloud,” slightly noticed in the continuation of the same chapter, but deserving most attentive illustration, as one of the most beautiful phenomena of the Alps. When a moist wind blows in clear weather over a cold summit, it has nottime to get chilled as it approaches the rock, and therefore the air remains clear, and the sky bright on the windward side; but under the lee of the peak, there is partly a back eddy, and partly still air; and in that lull and eddy the wind gets time to be chilled by the rock, and the cloud appears as a boiling mass of white vapor, rising continually with the return current to the upper edge of the mountain, where it is caught by the straight wind, and partly torn, partly melted away in broken fragments. In Fig. 86 the dark mass represents the mountain peak, the arrow the main direction of the wind, the curved lines show the directions of such current and its concentration, and the dotted lines enclose the space in which cloud forms densely, floating away beyond and above in irregular tongues and flakes. The second figure from the top in Plate 69 represents the actual aspect of it when in full development, with a strong south wind, in a clear day, on the Aiguille Dru, the sky being perfectly blue and lovely around.
So far all is satisfactory. But the true helmet cloud will not allow itself to be thus explained away. The uppermost figure in Plate 69 represents the loveliest form of it, seen in that perfect arch, so far as I know, only over the highest piece of earth in Europe.
§ 6. Respecting which there are two mysteries:—First, why it should form only at a certain distance above the snow, showing blue sky between it and the summit. Secondly, why, so forming, it should always show as an arch, not as a concave cup. This last question puzzles me especially. For, if it be a true arch, and not a cup, it ought to show itself in certain positions of the spectator, or directions of the wind, like the ring of Saturn, as a mere line, or as a spot of cloud pausing over the hill-top. But I never saw it so. While, as above noticed, the lowest form of the helmet cloud is not white as of silver, but like Dolon’s helmet of wolf-skin,—it is a gray, flaky veil, lapping itself over the shouldersof a more or less conical peak; and of this, also, I have no word to utter but the old one, “Electricity,” and I might as well say nothing.
§ 7. Neither the helmet cloud, nor the lee-side cloud, however, though most interesting and beautiful, are of much importance in picturesque effect. They are too isolated and strange. But the great mountain cloud, which seems to be a blending of the two with independent forms of vapor (that is to say, a greater development, in consequence of the mountain’s action, of clouds which would in some way or other have formed anywhere), requires prolonged attention, as the principal element of the sky in noblest landscape.
§ 8. For which purpose, first, it may be well to clear a few clouds out of the way. I believe the true cumulus is never seen in a great mountain region, at least never associated with hills. It is always broken up and modified by them. Boiling and rounded masses of vapor occur continually, as behind the Aiguille Dru (lowest figure in Plate 69); but the quiet, thoroughly defined, infinitely divided and modelled pyramid never develops itself. It would be very grand if one ever saw a great mountain peak breaking through the domed shoulders of a true cumulus; but this I have never seen.
§ 9. Again, the true high cirri never cross a mountain in Europe. How often have I hoped to see an Alp rising through and above their level-laid and rippled fields! but those white harvest-fields are heaven’s own. And, finally, even the low, level, cirrus (used so largely in Martin’s pictures) rarely crosses a mountain. If it does, it usually becomes slightly waved or broken, so as to destroy its character. Sometimes, however, at great distances, a very level bar of cloud will strike across a peak; but nearer, too much of the under surface of the field is seen, so that a well-defined bar across a peak, seen at a high angle, is of the greatest rarity.
§ 10. The ordinary mountain cloud, therefore, if well defined, divides itself into two kinds: a broken condition of cumulus, grand in proportion as it is solid and quiet,—and a strange modification of drift-cloud, midway, as I said, between the helmet and the lee-side forms. The broken, quiet cumulus impressed Turner exceedingly when he first saw it on hills. He uses it,slightly exaggerating its definiteness, in all his early studies among the mountains of the Chartreuse, and very beautifully in the vignette of St. Maurice in Rogers’s Italy. There is nothing, however, to be specially observed of it, as it only differs from the cumulus of the plains, by being smaller and more broken.
§ 11. Not so the mountain drift-cloud, which is as peculiar as it is majestic. The Plates 70 and 71 show, as well as I can express, two successive phases of it on a mountain crest; (in this instance the great limestone ridge above St. Michel, in Savoy.) But what colossal proportions this noble cloud assumes may be best gathered from the rude sketch, Fig. 87, in which I have simply put firm black ink over the actual pencil lines made at the moment, giving the form of a single wreath of the drift-cloud, stretching about five miles in a direct line from the summit of one of the Alps of the Val d’Aosta, as seen from the plain of Turin. It has a grand volcanic look, but I believe its aspect of rising from the peak to be almost, if not altogether, deceptive; and that the apparently gigantic column is a nearly horizontal stream of lee-side cloud, tapered into the distance by perspective, and thus rising at its apparently lowest but in reality most distant point, from the mountain summit whose shade calls it into being out of the clear winds.
Whether this be so or not, the apparent origin of the cloud on the peak, and radiation from it, distinguish it from the drift-cloud of level country, which arranges itself at the horizon in broken masses, such as Fig. 89, showing no point of origin; and I do not know how far they are vertical cliffs or horizontally extended fields. They are apt to be very precipitous in aspect, breaking into fragments with an apparently concentric motion, as in the figure; but of this motion also—whether vertical or horizontal—I can say nothing positive.
§ 12. The absolute scale of such clouds may be seen, or at least demonstrated, more clearly in Fig. 88, which is a rough note of an effect of sky behind the tower of Berne Cathedral. It was made from the mound beside the railroad bridge. The Cathedral tower is half-a-mile distant. The great Eiger of Grindelwald is seen just on the right of it. This mountain is distant from the tower thirty-four miles as the crow flies, and ten thousand feet above it in height. The drift-cloud behind it, therefore,being in full light, and showing no overhanging surfaces, must rise at least twenty thousand feet into the air.
§ 13. The extreme whiteness of the volume of vapor in this case (not, I fear, very intelligible in the woodcut3) may be partly owing to recent rain, which, by its evaporation, gives a peculiar density and brightness to some forms of clearing cloud. In order to understand this, we must consider another set of facts. When weather is thoroughly wet among hills, we ought no more to accuse the mountains of forming the clouds, than we do the plains in similar circumstances. The unbroken mist buries the mountains to their bases; but that is not their fault. It may be just as wet and just as cloudy elsewhere. (This is not true of Scottish mountain, by the way.) But when the wet weather is breaking, and the clouds pass, perhaps, in great measure, away from the plains leaving large spaces of blue sky, the mountains begin to shape clouds for themselves. The fallen moisture evaporates from the plain invisibly; but not so from the hill-side. There, what quantity of rain has not gone down in the torrents, ascends again to heaven instantly in white clouds. The storm passes as if it had tormented the crags, and the strong mountains smoke like tired horses.
§ 14. Here is another question for us of some interest. Why does the much greater quantity of moisture lying on the horizontal fields send up no visible vapor, and the less quantity left on the rocks glorify itself into a magnificent wreath of soaring snow?
First, for the very reason, that it is less in quantity, and more distributed; as a wet cloth smokes when you put it near the fire, but a basin of water not.
The previous heat of the crags, noticed in the first volume, p. 249, is only a part of the cause. It operates only locally, and onremains of sudden showers. But after any number of days and nights of rain, and in all places exposed to returning sunshine and breezes, thedistributionof the moisture tells. So soon as the rain has ceased, all water that can run off is of course gone from the steep hill-sides; there remains only the thin adherent film of moisture to be dried; but that film is spread over a complex texture—all manner of crannies, and bosses, and projections, and filaments of moss and lichen, exposing a vast extent of drying surface to the air. And the evaporation is rapid in proportion.
§ 15. Its rapidity, however, observe, does not account for its visibility, and this is one of the questions I cannot clearly solve, unless I were sure of the nature of the vesicular vapor. When our breath becomes visible on a frosty day, it is easily enough understood that the moisture which was invisible, carried by the warm air from the lungs, becomes visible when condensed or precipitated by the surrounding chill; but one does not see why air passing over a moist surface quite as cold as itself should take up one particle of water more than it can conveniently—that is to say, invisibly—carry. Whenever youseevapor, you may not inaccurately consider the air as having got more than it can properly hold, and dropping some. Now it is easily understood how it should take up much in the lungs, and let some of it fall when it is pinched by the frost outside; but why should it overload itself there on the hills, when it is at perfect liberty to fly away as soon as it likes, and come back for more? I do not see my way well in this. I do not see it clearly, even through the wet cloth. I shall leave all the embarrassment of the matter, however, to my reader, contenting myself, as usual, with the actual fact, that the hill-side air does behave in this covetous and unreasonable manner; and that, in consequence, when the weather is breaking (and sometimes, provokingly, when it is not), phantom clouds form and rise in sudden crowds of wild and spectral imagery along all the far succession of the hill-slopes and ravines.
§ 16. There is this distinction, however, between the clouds that form during the rain and after it. In the worst weather, the rain-cloud keeps rather high, and is unbroken; but when there is a disposition in the rain to relax, every now and then a sudden company of white clouds will form quite low down (inChamouni or Grindelwald, and such high districts, even down to the bottom of the valley), which will remain, perhaps, for tenminutes, filling all the air, then disappear as suddenly as they came, leaving the gray upper cloud and steady rain to their work. These “clouds of relaxation,” if we may so call them, are usually flaky and horizontal, sometimes tending to the silky cirrus, yet showing no fine forms of drift; but when the rain has passed, and the air is getting warm, forms the true clearing cloud, in wreaths that ascend continually with a slow circling motion, melting as they rise. The woodcut, Fig. 91, is a rude note of it floating more quietly from the hill of the Superga, the church (nearly as large as St. Paul’s) appearing above, and thus showing the scale of the wreath.
§ 17. This cloud of evaporation, however, does not always rise. It sometimes rests in absolute stillness, low laid in the hollows of the hills, their peaks emergent from it. Fig. 92 shows this condition of it, seen from a distance, among the Cenis hills. I do not know what gives it this disposition to rest in the ravines, nor whether there is a greater chill in the hollows, or a real action of gravity on the particles of cloud. In general, the position seems to depend on the temperature. Thus, in Chamouni, the crests of La Côte and Taconay continually appear in stormy weather as in Plate 36, Vol. IV., in which I intended to represent rising drift-cloud, made dense between the crests by the chill from the glaciers. But in the condition shown in Fig. 92, on a comparatively open sweep of hill-side, the thermometer would certainlyindicate a higher temperature in the sheltered valley than on the exposed peaks; yet the cloud still subsides into the valleys like folds of a garment; and, more than this, sometimes conditions of morning cloud, dependent, I believe, chiefly on dew evaporation, form first on thetopsof the soft hills of wooded Switzerland, and droop down in rent fringes, and separate tongues, clinging close to all the hill-sides, and giving them exactly the appearance of being covered with white fringed cloth, falling over them in torn or divided folds. It always looks like a true action of gravity. How far it is, in reality, the indication of the power of the rising sun causing evaporation, first on the hill-top, and then in separate streams, by its divided light on the ravines, I cannot tell. The subject is, as the reader perceives, always inextricably complicated by these three necessities—that to get a cloud in any given spot, you must have moisture to form the material of it, heat to develop it, and cold4to show it; and the adverse causes inducing the moisture, the evaporation, and the visibility are continually interchanged in presence and in power. And thus, also, the phenomena which properly belong to a certain elevation are confused, among hills at least, with those which in plains would have been lower or higher.
I have been led unavoidably in this chapter to speak of some conditions of the rain-cloud; nor can we finally understand the forms even of the cumulus, without considering those into which it descends or diffuses itself. Which, however, being, I think, a little more interesting than our work hitherto, we will leave this chapter to its dulness, and begin another.