LIBRARY UNIVERSITY OF CALIFORNIA I [ SAN DIEGO .- BOOKS BY PROF. JOHN C. VAN DYKE Art for Art's Sake. University Lectures on the Technical Beauties of Painting. With 24 Illus- trations. 12mo $1.50 The Meaning of Pictures. University Lectures at the Metropolitan Museum, New York. With 31 Illustrations. 12mo . ... net $1.25 Studies in Pictures. An Introduction to the Famous Galleries. With 40 Illustrations. 12mo .net $1.25 Text-Book of the History of Painting. With 110 Illustrations. 12mo $1.50 Old Dutch and Flemish Masters. With Timothy Cole's wood-engravings. Superroyal 8vo $7.50 Old English Masters. With Timothy Cole's wood-engravings. Superroyal 8vo . . . $8.00 Modern French Masters. Written by American artists and edited by Professor Van Dyke. With 66 full-page Illustrations. Superroyal 8vo $10.00 Nature for Its Own Sake. First Studies in Natural Appearances. With Portrait. 12mo $1.50 The Desert. Further Studies in Natural Ap- pearances. With Frontispiece. 12mo . net $1.25 The Opal Sea. Continued Studies in Impres- sions and Appearances. With Frontispiece. 12mo net $1.25 The Money God. Chapters of Heresy and Dis- sent concerning Business Methods and Mer- cenary Ideals in American Life. 12mo . net $1.00 (p. I/ X>y NATURE FOR ITS OWN SAKE FIRST STUDIES IN NATURAL APPEARANCES BY JOHN 0. |VAN DYKE AUTHOR Of " ART FOB ART'S SAKE " FIFTH EDITION NEW YORK CHARLES SCRIBNER'S SONS 1908 COPYRIGHT, 1896, BY CBART.K8 SCRIBNER'S SONS Co FRANK THOMSON WHO KNOWS AND LOVES NATURE- PREFACE THE title and the treatment of this book re- quire a few sentences of explanation. The word " Nature," as it is used in these pages, does not comprehend animal life in any form whatever. It is applied only to lights, skies, clouds, waters, lands, foliage the great elements that reveal form and color in landscape, the component parts of the earth-beauty about us. In treating of this nature I have not considered it as the classic or romantic background of human story, nor regarded man as an essential factor in it. Nature is neither classic nor romantic ; it is simply nature. Nor is it, as some would have us think, a sympathetic friend of mankind en- dowed with semi-human emotions. Mountains do not " frown/' trees do not ( ' weep," nor do skies "smile"; they are quite incapable of doing so. Indeed, so far as any sympathy with humanity is concerned, " the last of thy brothers might vanish from the face of the earth, and not iz PREFACE a needle of the pine branches would tremble. '' " Nature for its Own Sake," then, means simply that herein nature is considered as sufficient unto itself. The forms and colors of this earth need no association with mankind to make them beautiful. So far as application or illustration is con- cerned, my argument has no direct bearing upon any branch of science, literature, or art. I have used scientific facts occasionally to point a meaning without designing a scientific book ; I have in places spoken of literature, but the book is not an appeal to nature from those who have written about it ; and as for art, the word does not appear after this preface. Painters or writ- ers, with their truth or falsity of statement, are not my present concern. What, then, is the object of the book ? Simply to call attention to that nature around us which only too many peo- ple look at every day and yet never see, to show that light, form, and color are beautiful regard- less of human meaning or use, to suggest what pleasure and profit may be derived from the study of that natural beauty which is everyone's untaxed heritage, and which may be had for the lifting of one's eyes. In measure these pages are records of per- PREFACE 50 sonal impression, and must be so regarded by the reader. However objective in treatment one might wish to be, his point of view is always more or less warped by the personal equation, and I can pretend to nothing more than a view. As the sub-title indicates, these impres- sions are general in character in fact "first studies. " The book is designed as an intro- duction to a subject which I hope to consider more fully hereafter. SAGE LIBKABT, J. 0. V. D. NEW BKUNSWICK, N. J. CONTENTS CHAPTER I. Pure and Reflected Light. Our knowledge of light How light is obstructed by atmosphere Dust and vapor particles in the air Pure sunlight violet- blue White light the residue after filtering through the air Differences in light Shown in cleared air And from mountain-tops Earth coloring regulated by density of the air Warm and cold colorings The dust veil Krakatoa and the red skies Color ia the tropics And at the poles Sunlight in summer The dawn In Egypt with its wings of light In temperate climes Flooding of the dawn-light The sunrise Sunrise colors Noon- light Its great beauty in the fields The fall of light- Sunset Red sun disks Sunset colors Spectrum colors on the sky Sky effects Twilight Zodiacal light^The moon and its rise The misshapen moon Twilight and moonlight blended Horizon hues at twilight Star-light Star-colors Darkness of the upper space Lights of the night The great variety Countless changes Beauty of the world 1 CHAPTER II. Broken and Shaded Light. Cloud light and the cloud veil The lowery day Rain clouds Storm light Night and storm clouds Mists and fogs Vapor lights White horizons Fog lights Fog and smoke Fog effects Color in fog banks Nature's delicate hues Alternate sunlight and cloud light Sun-bursts The fall of sunbeams Sun-shafts with rain The sun " draw- xiii CONTENTS ing water " Sun-bursts and flying shadows in Scotland Moon-bursts and moon beams Shaded light The law of shadows Electric-light shadows Shadows lightened by light-diffusion Shadows in hot weather The colored shadow Scientifically explained Complementary hues in shadow Necessary conditions of the colored shadow- Blue shadows on snow Lilac shadows on clay and sand The mixed colors in nature Shadow complications The shadowless day Odd colors in shadow Shadows of the moon And of the stars 26 CHAPTER HI. The Slue Sky. Impressions of the sky Transparency of the blue Sky depth Through the clouds Sky reach Sky lines seen at sea Horizon lines Sky lines seen from heights Apparent changes across the face of the sky Sky waves and undulations The blue seen from mountain-tops The Great Silence of the firmament The blue seen from the valleys Its changes by day and by night The tenderness of its coloring Our non-observance of the sky And of sky tints Alpine glows at home Skies in different lands Color changes through atmosphere Season changes in the blue Luminosity of the blue Transmitted and reflected light Sky lights on the earth Reflection from the blue Atmospheric reflection The dawn an illustra- tion of atmospheric reflection And also a symbol in natural religion 47 CHAPTER IV. Clouds and Cloud Forms. Cloud- making Cloud forms Why clouds float Effect of the winds Effect of the air-currents Cloud caps Banner clouds Self-renewal of clouds Clouds, how acted upon How moved Day and night cloud* Classification of the families The cirrus Whiteness of the cirrus Color CONTENTS TV of the cirrus The cirro-stratus Sun and moon halos The cirro-cumulus Dappled and mackerel skies The stratus The strato-cumulus The cumulus Cumulus changes Summer clouds Heap clouds Cloud illusions The cumulo-nimbus Silver linings The nimbus Forms of the rain cloud Storm clouds Scattering forms of cloud Scud, wrack, etc. The lightness and drift of clouds Cloud fancies Cloud splendor and coloring Seen at sunset Seen at dawn and at noon-time Value of clouds in landscape Seen with a low sky line 66 CHAPTER V. Rain and Snow, The vapor-carrying capacity of air Condensation Causes of clouds and rain Eastern storms, how produced Warm winds and cold mountains In the high Alps The rain-drop Size of the drop The first heavy fall Thunder-storms Lightning and clouds at night Rain-fringes Surrounded by rain -The rainbow Three-day storms Rainy days After the storm City vs. country rain Hail Its forma- tionThe hail theories The falling stones Snow-flakes Snow on the mountains and rain in the valley The first fall Snow-storms The blizzard Flying snow The luminosity of snow Snow prisms Brilliancy of anow reflection The snowy landscape Under moonlight Snow lines Snow colors and shadows Swirls and drifts In early spring Nature's skeleton Nature's awakening 88 CHAPTBB VI. The Open Sea. First impressions Sea-changesWater forms The strife of the sea Its restlessness Wind and wave Wave crests Storm waves The hurricane sea The height of waves Thickness of waves Tropical swells Lines of a wave- Northern and Southern waves The undulation and wave XVI CONTENTS motion Depth of the undulation Local hues of water Sea-floors and their influence on coloring Deep-sea color Gulf and bay colorings Mineral hues in water Color patches Sea sawdust Transparency of sea-color Reflection from surface The smooth swell on the Southern seas Northern waters Sky effects at sea Sunlight on the wares Moonlight on the waves Cloud shadows upon water Colored shadows again Cloudy days at sea The emerald-greens of storm Atlantic and tropical waves Following the equator 113 CHAPTER VII. Along Shore On the beach The coast-wave Why waves break Dancing jets under a cliff The size of coast-waves And their power Forced and wedged waves The beach-comber Water-mirrors on the beach The undulation again The rising of the sea Thrust of the waves Curves of sand beaches Wave action on the rocks Cliff undermining Rock forms made by water Pulpits, bridges, and caverns Formation of sand-dunes Sea barriers Bars, lagoons, and marshes The tides Ebb and flood tides The bare shores Coast lines Color and light upon the shore Twilight colorings Moonlight on the sea The coast in storm The whipped waves The uses of storm Without the sea 134 CHAPTER VIII. Rwnnvng Waters. The river at the sea Meeting the ocean The river's path The Plain Track Through the meadows The river's basin The sluggish flow The Valley Track The river island- Hurrying waters New movement The wear of water The sculptor of the land Valley and mountain carvings Oscillations of the stream Lines of the banks and the vater Color on the river With enow and under ice CONTENTS rm Freshets Floods The Mississippi The river as it was and as it is European rivers The Thames, the Khine, the Danube The Mountain Track Brooks The moun- tain-brook and its motion In the ravine The gorge Following the brook By the waterfall The cataract Niagara Brook reflections The frozen stream Purity of brook waters The river's source Catch-basins The rivulet The beginning of the stream 153 CHAPTER IX. Still Waters. Names of seas and lakes-* Definitions Lakes vs. oceans The mountain-lake Its various features Purity and clarity of its waters Lake charm and sentiment Local coloring of the water Colors of background Local hue and reflection Con- fusion of hues Reflections Seen at night Confusion of reflections with shadows Surface appearances and phases of reflection On darkened waters On strong- hued waters Variations and distortions The likeness inexact The angle of reflection Elongated reflections The Angels' Pathway Romance Moonlight on the lake Material beauty of American lakes Lake George a type The pond in the forest The prairie pond In Indian days Artificial waters Venetian lagoons and canals Holland canals The mountain-lake once mow Its serene beauty 174 CHAPTER X. The Earth Frame. Earth and sea The earth's surface Inequalities of the surface The skeleton of the earth Strength of the frame Formation of the crust Geological formations Solidity of the earth Permanence of the flat prairies And of the primeval forests And of the desert The sands of Sahara The vaulting of the globe The understructure of the Alps The base of the Jungfrau from Miirren Foundations of xviii CONTENTS mountains The hardness of rocks Nature's building principle The self-supporting globe The lines of the earthShadow of the earth upon the sky The arch of the sky Horizon lines at sea and on the prairie The curved line and "the line of beauty" The law of the circle Shown in the forms of nature And in the elements and the solar system Circles in physical and intellectual life The uttermost rim of thought The Tanity of progress The universal law 197 CHAPTER XI. Mountains and Hills. Mountain ridges How the mountains are formed The wrinkle or fold theory The Alps The age of mountains Denudation and erosion The old Appalachians The worn-down mountains Exposed crusts Mountains cut out by water The approach to the mountains from the plains Seen from a distance Mountain-climbing The view The panoramic scene From the high Alps The look down- wardDistorted light and color The look upward The clouds and the sky The mountains from the valley Mountain colors The lower ranges Sky lines Moun- tains at sunrise At noon At sunset The western barrier Looking eastward at sunset Mountain glow at sunset The Alps in storm Storm in the lake-reflection Mountain individuality Changes of form Of color- Influence of atmosphere Light changes The green hills English bills New England ranges Hills in landscape The levelling down 213 CHAPTER XII. Plains and Lowlands. Impressions received from lines Valley silence Echoes and rever- berations Valley shadows Sunset valleys The age of the valley The brook again Valleys in autumn and in winter The valley home The table-lands In Mon- CONTENTS 3OX tana The Bad Lands Colors of decay Plateaus and steppes The primeval tracts The American prairie Prairie fires Treeless tracts The roll of the divides and swalea Prairie wildness Nature's revenges The wil- derness again Flat plains Low-lying tracts by sea OT river The livable lands Sky and horizon once more The marshes and meadows Reeds and rushes FlagB Beauty of the commonplace The marsh landscape- Near to civilization The bottom-lands Swamps and jungles 235 CHAPTER XIII. Leaf and Branch. The New World vegetation The foliage in America Timber growths Variety of forests Depths of the timber The "Big Woods" Botanical classes of trees Tree characteris- ticsTree forms Branch ramifications The pathetic fallacy The so-called sentiment of trees Life of the oak Tree motion Sounding-trees Leaves in motion Trees in storm Winds in the forest Bare boughs In March The March harmony Warming color The budding season Summer foliage Variety of the green Light transformations Swift color-changes The trees in blossom Blossom storms Autumn glory Indian summer The scarlet foliage Harmony of the scarlet landscape Nature's sacrifices Tree contrasts Tropical forests American forests European wood- lands 253 CHAPTER XIV. Earth Coverings. Trees and shrubs Bush growths The substitutes of nature Laurel and rhododendron California chapparal Sage brush Up- land bushes Common growths Wild roses Growths under shadow Fern and bracken Scotch heather Heather color Golden-rod Blue asters Bushes and CONTENTS flags Meadow growths The grasses The earth-pro- tectors Meadow and pasture The natural vs. the artificial Meadow flowers The wealth of color Past- ure changes Nature's care Cultivated growths House and lawn flowers The mosses Moss structure Moss colors and textures Gray lichens Rock-staining by lichens The work of the mosses and lichens Heat, light, and moisture Nature immortal The Great Peace 273 NATURE FOR ITS OWN SAKE NATURE FOR ITS OWN SAKE CHAPTER I PURE AND REFLECTED LIGHT A PISH at home under some ledge of rock in the depths of the sea, what does it know of sun- light ? Doubtless the pupils of its eyes con- tract and expand with the lights and shadows that break across the hills and valleys of the ocean world, but how dim must be those lights, how densely dark those shadows ! A ray of sun- shine passing through five hundred feet of wa- ter is broken, deflected, almost extinguished ; and the eyes that look upward toward the light through that great green lens of wave can gather but a faint glimmer of the truth. They are focused for the ocean depths, and when the fish is brought up to the open day the eyes are instantly set, and stare without meaning. The first flashing sunbeam doubtless shocks them senseless. The truth when revealed is blinding, and our sunlight is final truth to the fish. Knowledge of light. NATURE FOB ITS OWN SAKE We have, perhaps, a contempt for the knowl- edge of light possessed by the inhabitants of the deep, but our contempt is somewhat shal- low. For we ourselves are living at the bottom of an even greater sea the vast atmospheric ocean. We are looking up to the light through countless strata of air that break and twist and shatter the sunbeam looking up not through five hundred feet, but probably five hundred miles of air- wave. Perhaps, were we brought up and out of our sea and into the regions of space, our eyes, too, might be blinded by the sharp shaft of a pure and clear sunlight. Our knowledge of it is only comparative, a step upward from that of the fish. The truth in the superlative de- gree will never be attained. Human eyes have never seen pure sunlight, and that white light which we regard as such is anything but pure. It is not the sum of all radiation, as we are ac- customed to think, but the residue, that which remains after the passage through atmosphere. The air we breathe is filled with countless particles of dust, smoke, soot, salt crystals, vapor ; and these particles break light into color by obstructing the beams. The sun ray is thus disintegrated as soon as it encounters our outer atmosphere. Some of it is practically PURE AND REFLECTED LIGHT lost to us in the upper air, and that which finally comes on down to the earth has to our eyes a prevailing whitish, reddish, or yellow tone, dependent upon the density of the air. If we could sweep away our atmosphere entirely, the light would appear bluish and the sun itself violet- blue.* There is a predominance of vio- let and blue in sunlight, but the waves of these colors being the shortest and weakest in travel- ling power, are the first ones to be caught and absorbed by the upper atmosphere. Held in check, entangled as it were, quantities of them are massed above us, making what we call " the blue sky." The yellow and red waves, having greater length and power than the blue ones, penetrate the atmosphere deeper and come to us with the tale that the sun is yellow or red or, in combination with other colors, white. But the tale is deceptive. Sunlight in its entirety appears whiter and then bluer, in pro- portion as we rid ourselves of our atmospheric lens ; and the sky itself grows darker from the non-diffusion of the sun's rays. An ordinary rain-storm that clears the atmosphere will tem- * This is the conclusion of Professors Langley, Young, and other scientists. If seen from a distant world) our sun would appear as one of the blue stars. NATURE FOR ITS OWN SAKE porarily make the sky and distant hills look bluer, the sun whiter, the light purer. Cold that is intense enough to rid the air of moisture will also make a noticeable difference in the quality of the light. In Manitoba, where the thermometer often sinks many degrees below zero, a bright winter day reveals an air the moist- ure of which is frozen into floating crystals of hoar-frost, the sky appears cobalt-blue, the sun is white, and when it rises in the morning it is accompanied by two sun-dogs or parhelia, one on each side, and almost as brilliant as the sun itself. The result is a bewildering display of white light that borders upon blue. Every snow crystal glitters, the cup of the sky seems to be lifted into infinite space, the snow shad- ows are intensely blue, and the running waters are dark-purple in hue. As we rise above the denser strata of at- mosphere that lie along the earth, by ascend- ing mountain heights or otherwise, the light changes even more positively. From the top of Mt. Blanc the stars are seen at midday shin- ing upon a dark blue- violet field that extends down to the horizon ; from Pike's Peak the sky is seen to be of a violet hue at times, and not in- frequently blue-black ; and from Mt. Whitney PURE AND REFLECTED LIGHT Professor Langley observed the sun go down, not gorgeous in color, but coldly luminous, with the dark sky crowded close up to the disk, and the zenith deep violet-blue. Whenever or however the thickness of air between us and the sun is decreased, the coloring of light changes, growing from a yellow flame somewhat like candle-light to something kindred to the blue- violet flame of the electric arc-lamp. The atmosphere then is chiefly responsible for the quality of our light, and upon the clear- ness or thickness of the atmosphere depends also the quality of our coloring. If the air is comparatively clear, the light will be sharp and the prevailing notes of color in landscape will be blue and green, because the slightness of the interfering media allows the short color-waves of blue and green to come on down to earth in great quantities ; if the air is heavy with parti- cles, the light will be less intense and the notes of landscape will be yellow or red, because the density of the interfering media allows the stronger color-waves of yellow and red to pass through and down to earth, but obstructs the blues and greens. It is owing to density of at- mosphere that the heated portions of the globe, like Morocco, for instance, are less strong in NATURE FOR ITS OWN SAKE coloring than the temperate New England, not- withstanding the intensity and the directness of the sun's rays near the equator. The heat of the equatorial region produces dryness of the soil, and dryness produces dust, which is carried up into the air by rising currents. This obscures and changes the color of light more effectually than perhaps we realize. Professor Langley tells us that from the top of Mt. Whitney he saw this dust lying below him like a great reddish mist suspended four or five thousand feet above the level of the surrounding country. It can be imagined that light streaming through such a mist must be not only obscured, but must give a coloring to the earth of yellow, orange, and red, somewhat as the coloring of a room is affected by red or amber glass placed in the windows. A practical illustration of a dust-laden at- mosphere and its color effect was shown us in 1883. The volcanic eruption of Krakatoa threw a shaft of fine ashes some eighteen miles directly into the air, where it was caught by the winds, and swept around the globe ; and for months this fine ash was slowly settling through the atmos- phere to the earth again. The result was a tur- bid air and an extraordinary series of red dawns PUEE AND REFLECTED LIGHT and sunsets seen in many lands. In Spain, where I happened to be a year later, the dawns were the most ruddy I have ever witnessed ; and each night the sun went down hissing hot into the Atlantic like a ship on fire, throw- ing great naming signals of distress far up the zenith as it sank. But while the dust veil may produce great mass and variety of colors, these are not neces- sarily of the highest intensity. The most brill- 1 iant hues are to be seen where the light falls ' the clearest, and this is not in the heated tropics, but near the cold poles. The northern countries have not the many local colors of the tropical lands, but those they possess have more depth and clearness. No palm on the banks of the Nile ever had such brightness of greens as the pine and the spruce on the Norwegian mountains. In upper Scandinavia the flowers are brighter, the sky and water deeper blue, the mountains purer purple, the sunsets more scarlet than in Italy, Greece, or Algiers. And we all know what report the arctic explorers have brought back to us of brilliant skies, flaming Northern Lights, and intense blues in water, ice, and snow seen in the polar regions. There is not the slightest reason to doubt the truth of the Color in the tropic* and at the north. colors. NATURE FOB ITS OWN SAKE report. Theory and observation both confirm it. A red, a blue, or a green at the north is harsh, intense ; where near the equator it is slightly bleached or blended with other colors by reflection. That the latter is more harmo- nious than the former is quite aside from the present tale. The changes in color and light, and their effect upon the world about us, are things of which many of us living in the temperate climes have small appreciation. Our conventional remark to a neighbor in passing, " A fine day ! " means merely that we find the weather normal and the sun shining. We have never stopped to study the varieties of illumination and hue that weave and interweave through that day. It is merely a glittering generality to us ; yet from dawn to dawn how marvellous is the light, how splendid is the coloring of a clear day in summer! It usually begins with the faint graying of the eastern sky above the horizon, or it may be that the light appears at first high up in the sky. The air has been cooled and somewhat cleared by the night just past, moisture is more predominant than dust, and the consequent sky-color is gray or silver. The light soon extends down and PURE AND REFLECTED LIGHT around an eighth of the horizon circle, and then perhaps to a sixth of it ; or it may mount upward in the shape of a fan. Sometimes pale yellow is a predominant coloring, and in warm weather a rose hue is quite frequently shown. If the sky above the horizon is barred or streaked with clouds, almost any conceivable color may be reflected from them, dependent upon the state of the atmosphere and the posi- tion of the clouds. Again, if the air is dense with vapor or dust, the advance arms of the sun may be seen reaching far over the night like the silver shafts of an enormous search- light. These premonitory signs of the coming day are often extraordinary in their appearances. For instance, in Egypt, during the heated season, the dawn is not always the slow steal- ing of light along the horizon. On the con- trary, a single shaft like the pinion of a wing rises upward toward the zenith. In a moment another shaft begins rising by its side, and then another and another, until the whole half- arch of the heavens resembles two spread wings poised perpendicularly. These are, I imagine, the biblical wings of the morning that fly to the uttermost ends of the earth. At other ro NATURE FOR ITS OWN SAKE times the Egyptian dawn shows a mild effect of sun-dogs, such as are frequently seen in cold, snowy lands. In the one case, the parhelia are produced by ice crystals in the air, in the other case by dust crystals in the air. They are more brilliant from ice than from dust, and where with the one they centre in great spots of light, with the other they shape themselves into side illuminations that resemble wings spread laterally. These, I imagine again, are the wings of light supporting the golden disk of the sun, that may be seen to this day carved on the temple lintels of ancient Egypt. But the dawn in our temperate clime is not so unusual in appearance. It is with us the gradual expansion and intensifying of radiance. The light is a soft, lustrous one, illuminating the earth entirely by reflection. While the sun is below the horizon no direct rays can possibly reach us. The shafts are shot up against the blue vault, and from this trans- parent blue of atmosphere they are reflected back to earth. It is not a bright or sharp re- flection. The rays are bent and thrown back only by the infinitesimal particles that float in the upper air. Even when the shafts strike a cloud they simply make it glow like a great PUKE AND REFLECTED LIGHT 11 pearl, and the glow is infinitely more delicate for its surrounding of translucent atmosphere. Yet the great vault is illumined, and, as the sun rises higher, far to the north and far to the south, half-way around the circle, a tapes- try of silver and gold is weaving on a blue-gray ground, and the dark ultramarine of the west turns a shade paler and seems to lift into space as the light grows stronger. How like the flooding of the tide this light drifts up, and in this great aerial ocean bringing with it warmth and color ! Soundless and surgeless, rolling in waves too translucent to be seen, ris- ing higher and higher, yet meeting with no ultimate shore, how gloriously it sweeps up and over the world ! How swiftly even the ''meagre cloddy earth" borrows a splendor from above and reflects the flush of light and color ! The mists stir, the trees tremble gently, the dew slips from leaf to stem, and the whole globe seems to awaken from slumber. There is nothing more beautiful in all nature than this flooding of light across the sky, across the earth ; yet even as we watch it a great change takes place. The sun peers over the horizon and the first beam of light strikes full upon the mountain's highest minaret of 12 NATURE FOB ITS OWN SAKE rock, splashing it with a pale golden hue. At once the hue begins to creep down from the mountain-top, striking the oaks and cedars one by one with yellow shafts until the whole hill-side is mantled with its color. Swiftly the light spreads to the valley, and in a few mo- ments it falls upon the fields and meadows. Im- mediately begins the phenomenon of light being broken and obstructed by opaque bodies such as hills and trees, and we have the effect of light-and-shade. Immediately, too, the swift vibration of those points of light productive of color is increased, and we have the brilliant hues that mark the earth under sunshine. Every lake and stream and open sea warms in color and glances the image of the sun, and every hill-side and mountain-crag receives the stain of gold. Not the great objects alone, but the infinitely little, the pale wind-flower, the lowly buttercup, the yellow-centred daisy, the tiny violet, the leaf -whorl of the moss, all put on their brightest garments, each one lifting its head to the sun as the great glory of the universe. As the sun rises higher the splendor becomes more widely diffused. The color of the rose leaps to a high pitch, the top of the willow is a PURE AND REFLECTED LIGHT 13 mass of silver, the poplar seems to shake light from its leaves as though they were trembling little mirrors. By contrast the shadows across the lawn and along the mountain-side seem darker, though in reality they are lighter ; and the light itself may seem fainter because widely diffused, whereas it is stronger and fiercer. By ten o'clock the sun is quite high in the heav- ens. Heat is radiating from the earth. Strata of warm air are forming along the ground, moving uneasily hither and thither in their search for an exit through the colder air to the upper regions. Dust and moisture, too, are rising ; and by noon perhaps there is a haze lying along the hills and meadows, the distant valleys look gray and warm in the sunlight, the mountains beyond them are faintly blue, the sky itself looks yellow or rosy. Color is every- where, more predominant than in the morning, but less contrasted, because the atmosphere has blended and toned all nature to its own golden hue. How different this hot light of noon from the dawn-light ! The latter is preferred be- cause it is soft and agreeable to the eyes, but it would be difficult to imagine anything more beautiful or more splendid than bright sun- The light at 14 NATURE FOR ITS OWN SAKE light beating at midday npon a field of ripened grain where the fiery red of the poppy gleams in between the yellow stalks ; or again this same light falling upon fields of golden-rod or npon great masses of variegated autumn foliage. Blinding, too, as is the noon-light upon desert sands or prairie uplands or flat smooth seas, yet its breadth and intensity make it one of nature's great glories. And how invisibly it cuts through the air! On yonder mountain we should notice falling rain or snow or even a slight thickening of the atmosphere ; yet all day long the sunbeams fall upon it and we cannot see them. We see the mark they make on crag and tree, we feel their absence when a cloud shuts out the sun ; but that is all. As the day wears on, the heat increases. The leaves of the trees and the flowers curl and shrivel, the air rises quivering from the dusty road, the sky grows more rosy even iridescent. The ascending air-currents are active and the atmospheric particles more numerous. Hour after hour the aerial envelope grows denser and heavier, the shadows fainter, the light more diffused. At last, when the sun has fallen to the western horizon and throws its rays along PURE AND REFLECTED LIGHT 15 the surface of the earth, they pass through many miles of this heated dust-and-moisture- laden air. When they reach our eyes they tell the oft-told tale of the brilliant sunset. The pale grays and silvers of the dawn, produced by the sun's rays coming to us through a cleared and cooled atmosphere, have now changed to the golds and scarlets of the evening, produced by the rays coming to us through a heated and a thickened atmosphere. So dense is the air at times that the shafts of the setting sun may be distinctly seen radiating up the sky like the spokes of an enormous fiery wheel ; and again at other times the air may be so thick that it obscures the sun's rays, and we can see the red disk go down almost without a flash of light as though its own heat had consumed it. The glare and heat of sunset colors are per- haps more apparent than real. The same sun at the time it looks red to us may show the yellow of noon and the white of dawn to the people and the lands lying to the west of us. We are looking from a land of shadow toward one that is still in full sunlight, and the bright- ness of the sky-color is great by contrast. The colors and combinations of colors that we see on the western sky and clouds at sunset and 16 NATURE FOR ITS OWN SAKE twilight hardly admit of description. All hues, all tints are possible, and nothing is of long duration. The appearance is almost as tran- sient as the aurora, for it is shifting in position, shifting in light and color continually. When there are no clouds, the normal evening sky shows a continuous spectrum, and the order of colors begins with red at the horizon and ex- tends in successive bands through orange, yel- low, green, and finally shades into the blue of the upper sky. These colors are intensified or depressed by atmospheric conditions, and they are complicated by the appearance of clouds, though the order of their appearance even with clouds is usually maintained, the reds being the lowest down and the succession rising through the intermediate colors to blue. The most splendid evening effects are, gen- erally speaking, in the autumn, when with Indian summer there is much heat and dust in the air. Scarlets, carmines, rubies, and burn- ing golds are then apparent. After several days of rain have left a damp, thick atmos- phere, a clearing western sky with fleecy clouds will often show very brilliant yellows in bands, and in between these bands small spaces of malachite green. The winter and the early PUEE AND REFLECTED LIGHT 17 spring sometimes show wreaths and scarves of yellow or red upon the clouds after sunset ; but as a general rule these are not the seasons for bright displays. The coming of the dawn and the passing of the sunset doubtless occupy the same length of time, but to us the latter often seems of shorter duration. At the equator there is compara- tively no glow on the sky after the sun disap- pears. Almost immediately upon the vanish- ing of the disk from view there is darkness. Along the coast of Norway one may see the after-glow upon the sky far into the night ; and farther up the coast the sun itself may be seen at midnight. The shape of the globe and the inclination of its axis account for both these appearances. In the temperate zones we have something between the two extremes. The sun for some time after its disappearance from view keeps throwing light from below the horizon upon the upper sky, and thus produces the effect we call twilight. It used to be reck- oned that when the sun had fallen eighteen or nineteen degrees below the horizon the twilight ceased entirely; but according to astronomers it ceases whenever a star of the sixth magnitude can be seen in the sky directly overhead. The 18 NATURE FOR ITS OWN SAKE first twilight is, however, sometimes followed by a second glow; and after this has passed there is occasionally another light seen in the western sky called the zodiacal light. This usually forms itself in the shape of a pyramid, with its base toward the horizon and its apex extending zenith ward along the track the sun has traversed. It is a pale nebulous light, like that of the star clusters called the Milky Way ; it appears more frequently in the tropics than in the temperate zones, at dawn as well as at twilight, and is often referred to as the " False Dawn" and the " Wolfs Tail." The cause of its appearance has not yet been satisfactorily explained. No sooner is the sun gone (at times before it is gone) than the moon comes up beyond the eastern hills, at first rising slowly and then sud- denly bursting into view. If the day has been hot and dry the face of the disk is red or deep or- ange, abnormally large in appearance, and often bulged and misshapen as regards its circle. We are looking at it through that same lower stratum of dense air which has been rising all day from the earth, and is still rising though the sun has set. It is the dense air that gives the abnormal size and the ruddy color. As the orb rises PURE AND REFLECTED LIGHT 19 higher in the evening sky and gets out of the range of this heavy air lying along the earth, the disk apparently grows smaller and becomes clearer in light. The red and orange fade out, and we see what is called the " yellow moon." It grows still fainter as it rises toward the zen- ith and the earth's atmosphere clears and cools ; and when in the morning hours it sinks into the west, the disk is whitened and apparently shrunk in size. There is little color demonstra- tion as it nears the horizon again. It is cool and silvery, seldom red or yellow, and slips from view usually unnoticed. Moonlight is, of course, the light of the sun reflected from the moon. It is not reflected from a bright surface like water (there is no water on the moon) but from dull surfaces like rock ; and as a result the reflection is many de- grees feebler than its cause. Yet the moon has some surface gleam about it and is hardly like an illuminated transparency hung in the air. By comparison with the sun it has no sharp shafts and is so feeble that when sun and moon are both above the horizon the latter attracts no attention whatever ; but after the sun has gone down and the moon rising in the east mingles its light with the twilight of the west, it makes a 20 NATURE FOR ITS OWN SAKE decided impression on the landscape. The two lights together give us the most charming il- lumination imaginable. The expiring fire of the one and the soft glow of the other mingle in a strange amalgam ; and a lustrous light envelops the world as tender and as lovely as that reflected from mother-of-pearl. There is neither deep shadow nor sharp color ; and around the great ring of the horizon, stealing far up the sky, there is a vast blend and mystery of color. The molten golds and garnets of the west as they steal along the horizon circle to the north and south, change into opalescent tints of yellow, rose, and amethyst ; and the blue and silver of the east as they spread out to meet the flush of the west, pass through all the shades of gray, mauve, and lilac. For producing delicate tints of color there is no such light as this double il- lumination coming from the east and the west. Wonderful in their variety, more wonderful in their unity, these tints drape the whole circle of the horizon like a celestial tapestry. Never for a moment are they fixed or permanent. The great waves of light that came up the blue vault at dawn have calmed down to gentle undula- tions, but they still heave and roll along the ho- rizon-walls, and at every heave some beautiful PURE AND REFLECTED LIGHT 21 combination of color breaks and disappears, some equally beautiful one takes its place. And when the sun and its cloud coloring have gone, when the moon is not in our quarter, then falls the night shadow upon the earth and through it the shining of the stars. They, too, are affected in appearance by the density or the clarity of the air through which they are seen. The night sky hanging over Sahara is usually a very dark purple, but the stars do not shine brightly upon it, and they have no marked col- orings; yet they appear very near, as though one might reach them with an arrow. Where the air is more transparent, as in the north of America, the night sky is deeper, the stars sparkle and throw out tiny shafts of light, and they show to the eye different hues of em- erald, topaz, amethyst, ruby ; but they do not appear to be at all near us. Jewels shining through a dusky veil, they have but little light, and that in such small points that the impres- sion upon the great mass of shadow lying across the earth is not great. We are able to see about us on a starry night, but is it by the light of the stars alone that we see ? Is that light suf- ficient to illumine the world even in a feeble way ? At night one-half of the globe is shut 22 NATURE FOR ITS OWN SAKE out from the direct light of the sun, and though far above the shadow, above the atmospheric arch we call the sky, the light streams through the realms of space, yet it leaves no visible track, no illumination, no reflection. Beyond our sky it is supposed there is no air, no vapor, no dust to catch and to reflect light. In space the sun's rays travel direct with no diffusion, no halo, no radiation ; and could we see the sun itself it would appear as an intensely bright disk with- out shafts. It would seem then that, with sun- light and moonlight cut off, we gain little or no light from the upper regions of space, save that which comes from the stars. It is possible that our upper atmosphere may be illumined by reflected sun rays or moon rays, and that thus the light of the stars is helped out. And it is possible, too, that there is something of stored- up light or electrical phenomena to add to the night illumination. These accessories may aid the light of the stars somewhat, but they de- crease the total illumination decreases as the night wears on and out, and the darkest hour is just before dawn. So much for the direct and reflected lights of a summer's day. It is one day out of three hundred and sixty-five, and has been de- PURE AND REFLECTED LIGHT scribed only in its general features. There are no two days in the year just alike, nor will you ever find one day paralleled or repeated in an- other day. There is a warmth of coloring and light in midsummer and autumn, a bleaching of hues in the spring, a coldness of light in winter ; but these again are only general char- acteristics of the seasons, and do not indicate the infinite changes in each separate day. The va- riety of combinations made by nature can never be tabulated or classified. Night after night one may watch the moon rise watch it riding through clouds, first a dull disk, and then a growing light as it nears the edge of a cloud but the same effect is never repeated ; never the same moon, never the same clouds, air, and coloring. The sun comes up, the sun goes down ; but each morning light sets a different glory upon the eastern sky, and each evening light reveals new iris hues upon the burning western clouds. And so with a different radiance for each hour the splendor of the world goes round, night following day, hemispheres of shadow alternating with hemispheres of light. As the earth turns, midnight and noonday slip over its surface. Eevolving around the sun in a slightly 24 NATURE FOE ITS OWN SAKE The whirl- ing world. erratic orbit, flinging off heat or cold as the in- clination of its axis to the ecliptic, it follows necessarily that the earth must be continually changing in light and color. There shall never be any monotony so long as the sun lasts and the world spins ; and that light which was created on the earliest day is to this latest time the most varied and the most wonderful beauty of the universe. CHAPTER II BROKEN AND SHADED LIGHT ALL the lights that come from the sky and reach the earth, whether from sun, moon, or stars, are broken lights in the sense that they are somewhat shattered by passing throngh atmosphere. None of them reaches us in its pnrity ; yet, comparatively speaking, we say that sunlight is direct light, moonlight is re- flected light, and cloud light is broken light. A cloud between the sun and the earth is merely the interposition of a visible atmosphere dense with particles of moisture, but it has a very decided effect in subduing the intensity of light and darkening the earth. The more vapor- laden the cloud and the thicker through its mass, the darker it will appear and the feebler will be the light filtered through it. If it is a large cloud it will appear, perhaps, unusually dark to us, for the reason that we can see only its shadowed base. On its upper part or top it is, of course, shining white in the sunlight, like the cumulus of a summer day ; for a cloud 25 Cloud light. 26 NATURE FOB ITS OWN SAKE will have its light-and-shade like any other object, and the dark massed nimbus, which we call the rain cloud, is not very different from other clouds, save that its base is deeper sunk in shadow. The gray, lowery day, so often seen in spring and winter, shows us cloud forms so closely packed together that they make a continuous curtain across the sky, through which light passes to the earth in a neutral but widely dif- fused illumination. This is broken light in its most positive form. Dispersed in every ray by moisture particles, the crippled sunlight can do no more than throw a gray monotone over the face of nature, taking the cloud coloring for its chief note. Such a day is usually declared "dull." The sky and sun are completely shut out, there is no sharp flash of light, color, or shadow, no mellow haze upon the earth, no gilding and fretting of gold overhead. The cloud curtain covers the sky and draws down below the horizon-ring like a cap, a film of mist lies across the meadows, blue and purple drifts of air float high up in the valleys, and along the mountain-sides and over the craggy peaks hang gray fringes of rain. Upon days like these the clouds troop on across the sky, rank BROKEN AND SHADED LIGHT 27 npon rank, one so close upon the heels of the other that they are scarcely to be distinguished. How often the traveller has seen them in Paris swaying above the Arc de Triomphe and drift- ing down over the Champs Elysees, flooding the city with torrents of rain ! How often he has seen them defiling over the plains of Bava- ria, covering the Bohemian forests, or muf- fling the hill-tops of New England ! There is no break in the lines, no sunlight streaming through. At times a company seems to lift and lighten and the horizon appears to expand ; but it is soon followed by a thicker company, the light darkens, the horizon contracts, and the rain waves through the air like the folds of an enormous mantle shaken out by the wind. And how dark the night following such a day ! There is no moon, and only the sharp- pointed stars illumine the watery canopy from above. On such a night the wind seems to rise as the darkness falls, the mountains fade into vague black spots and then blur out, the break- ers with phosphor-white crests fall heavy and booming on the sea-shore, and the forest moans and vibrates like a vast ^Eolian harp. There is little beauty here, save in sound and contem- plation. Not even lightning throws a momen- NATURE FOB ITS OWN SAKE tary flash upon the scene. The swirl and the swish of the elements, especially on the sea or on the plains, the sublimity of the tempest, ap- peal to us perhaps ; but our eyes are almost useless. Nothing so darkens the earth as night and rain clouds under a moonless sky. It is, apparently, a very different light that we see when the clouds are not above us, but around us. A mist or fog is merely a cloud formed close to the ground, and is not different from the cloud that is about one at times on a mountain-top, except that the fog appears to be more luminous and to have more color. Doubtless something of this appearance is due to the thinness of the bank. It generally forms with a clear sky overhead, and is sometimes not higher above the earth than a house-top, though it is often a hundred or more feet in thickness. When the bank is shallow we are surrounded by diffused and refracted light, and an upward glance in the direction of the sun shows us a white light seen as through alabaster. This same light is sometimes seen in the early morn- ing illuminating the whole landscape when the fog has lifted a thousand or more feet above the earth and is spread out into a thin, gauze-like sheet. The thinness of the sheet prevents ob- BROKEN AND SHADED LIGHT 29 scurity and facilitates diffusion, as does aground- glass globe upon a lamp. The result is a vapor- like light of marvellous luminosity and great beauty. Unfortunately it is not of long duration, and here in America it is not often seen. In France along the Seine, in England along the southern coast, and in Japan it is of common occurrence. The so-called " white horizon " results from a similar set of circumstances. The vapor-laden atmosphere of the morning, seen in mass as we look toward the horizon, produces the white-light effect. Seen in the afternoon or at sunset, the same horizon shows rose, lilac, or mauve tints, because the vapor particles have been superseded, or at least alloyed by the dust particles, and the heat is greater. But to return to the fog along the ground, as soon as it begins to lift it becomes lighter and brighter until finally the sun peering through from above appears as a silver or pale-yellow disk without radiant shafts. The light grows more golden as the fog-bank decreases in thickness, until at last, the sun having burned its way through to the earth, we see the normal light of day. The fog then disperses in small patches, is evaporated and carried upward by rising cur- rents of air, and in a short time has disap- Vapor White horizons. Fog light* 30 NATURE FOB ITS OWN SAKE peared entirely. Of course the deepening and the thickening of the fog-bank enfeeble and gray the light. When combined with dust and smoke, as in large cities, it is sometimes dense enough to require the lighting of street lamps in the middle of the day. How it ob- scures the vision everyone knows who has been in London at such times, or has crossed on the New York ferry-boats, with the pilots picking their way by the sound of whistles and bells. In such fogs a few feet are often sufficient to efface objects entirely. In the country a fog never appears to be so thick as in the city, though in low marsh places it banks up and obscures land and water very effectually. Seen from a high place look- ing down, the shore-fog is not unlike a cloud below one in an Alpine valley ; and with the sunlight beating upon it the fleecy spun-silver effect is just as beautiful on the one as on the other. There is no limit to the fantastic forms a fog will assume when seen from a height. At times when the dark tree-tops protrude above it the appearance is that of a landscape buried in snow, at other times the meadows seem flooded with milk-white water, or suffocated with drifts and currents of smoke. The small islands off AJNU SHADED LIGHT 31 the coast of Maine are remarkable for fog ef- fects, and in cold weather, when the fog turns the bare trees into traceries of frozen silver, the effect is truly splendid. But close contact with fogs in either city streets or country lanes is not a thing enjoyed by the average person. People grumble and cough and talk about " disagreeable " and "horrible" weather, but not one out of a hun- dred gets his head far enough out of his coat- collar to see the beautiful pearl-gray tints about him. Broken and obscured as the light is, it still comes through in minute reflecting points. There is nothing opaque about the bank. It is luminous always ; and though we think of it and speak of it as gray and monotonous in color, we have only to contrast it with engine steam to find that it is often full of delicate pinks, lilacs, and pale yellows, especially when it is lifting. These minor broken color-notes seldom attract our attention, and yet they are perhaps as refined tones as we shall find in nature's gamut, if we except the notes of the upper sky at dawn. It is curious that people do not see them, and still more curious that they fail to appreciate them when they are pointed out. The average person is quick enough to remark the red flame Color in fog bank 32 NATURE FOR ITS OWN SAKE of sunset, but he seldom sees the dove-colors and steel-blues that lie back of him in the east ; he sees a scarlet maple or an orange stain upon a hillside meadow in October, but he overlooks the silvery sheen of the wind-swept poplar, or the cloud-like surface of the Indian grass ; he is not blind to Niagara and the Alps, and all the " big things," but he has an unhappy way of never regarding anything that is not " big," and hence loses a great deal of pleasure in life which comes from discovering and enjoying the beauty of the so-called commonplace. Direct light does not necessarily mean a per- fectly clear sky, nor broken light a completely clouded one. There are days of alternate sun- light and cloud light ; and indeed, a blue sky with drifting clouds is more frequently seen than any other. The heavy cumuli that lie along the horizon like distant mountain -ranges with snowy summits are not very noticeable as makers of shadow, nor are the thin clouds stretched in strata across the upper zenith pro- ductive of anything but a general veiling of the light. It is the thick, ragged, or round cloud, drifting across the sky in flocks, that makes the sunlight come and go upon the earth. When each of these moving clouds is surrounded by a BROKEN AND SHADED LIGHT 33 field of blue the shadow of the cloud is cast upon the earth in isolated silhouette. As the cloud moves, the shadow moves too, and we have that charming effect called the flying shadow. If there is a stiff wind blowing and the clouds are closely packed together with only loopholes of blue here and there, or if the clouds are long rolls of the nimbus with occasionally breaks in the line through which the sunlight falls, we then see that other charming effect called the sun-burst. The sun-burst is often seen in summer weather, especially if the day is hot, and the air is heavy with dust and moisture. Under such conditions the bright beam thrust through a cloud opening makes a Jacob's ladder of light from heaven to earth. The light falls in a shaft very much as the pinion of the Egyptian dawn rises toward the zenith, except that it is usually frailer and more golden in hue. And it always falls through the shadow cast by clouds just as a beam of sunlight flashes into a darkened room and is seen because it is surrounded by dark- ness. When a cloud passes across the face of the sun its edges may turn to molten silver and its thicker portions glow with light, yet the beam does not get through and the falling shaft 34 NATURE FOR ITS OWN SAKE is not seen ; but just as soon as a flash from the sun breaks through a torn portion of the cloud, the shaft falls to earth and is apparent from its shadowy envelope. It appears to fall earthward in a straight line, but, like all sun- beams, it in reality describes a curve through the lower atmosphere, especially if the sun is low in the heavens. The trajectory is not point-blank, but falls short like a spent rifle ball. Yet this is not seen by the eye and is known only to scientific calculation. To all appearances the shaft falls straight and remains fixed. It is the shadow of the cloud that glides across the meadows, up the valleys, and over the mountains ; the sun-shaft does not shift except where it falls more obliquely as the earth rotates from west to east, or its direction is changed by cloud breaks. The sun-burst is perhaps seen more frequently during showery weather or with thunder-storms than at other times, and it is usually more lumi- nous after than before a rainfall. As the first- comers of the storm-clouds begin to cover the sun, the shaft is often seen in a yellow beam falling diagonally toward the earth. When the shower is passing and the sunlight begins to show again, the shaft reappears frequently in BROKEN AND SHADED LIGHT 35 the form of a white beam, stronger than the yellow one, because falling through denser moisture. There may be many of these shafts, and they may radiate in all directions from the sun, as one often sees at evening, when the west is barred or streaked with clouds. . The reach- ing down of sun-shafts toward the earth, with or without a shower, is commonly referred to as the sun " drawing water." It is really the sun illuminating the dust or moisture in the air, just as the rainbow, which spans the opposite heavens from the sun, is but the sun's rays re- flected and refracted in prismatic colors from drops of rain. For variety in the display of sun-bursts I know of no country more interesting than Scot- land. In stormy weather at sunset the light falling through chinks of the clouds will often make a half- wheel or fan-shaped alternation of light and shadow most brilliant in its flashes of gray and silver. And again, I have never seen such effects of sun-bursts and flying shadows together as in the Grampians, particu- larly those more barren portions of the hills where the heather is absent and only a yellow- green of grass and a slate-gray of stone are seen as background. Over the slopes and down the 36 NATURE FOB ITS OWN SAKE valleys the lights and shadows seem to wave in bands, like the streamers of the Northern Lights across the sky. The shaking shimmer- ing effect and the alternate colorings of yellow, green, and gray, chasing each other across hill and dale, are most extraordinary in appearance. After watching them for a few moments, it is quite impossible for the eye to tell whether the light, the shadow, or the color is flying. At other times, when the clouds are rounder and larger, their shadows slip along majestically from crag to lake, from lake to crag again, glid- ing noiselessly and without obstruction up and down and over the Scottish moors like dark peer- ing spirits seeking a hiding-place and never finding it. They roam restlessly on and on, until at last they spread out upon the flat North Sea and their dark forms, changed to lilac in hue, go slipping over the waters to the east, still rest- less, still noiseless, still flying. In other lands the shadow is interesting to watch as it glides across the meadows covered with buttercups and daisies, and climbs the wooded mountains to vanish over the ridge ; but the bare hills and moors of Scotland always seem the best play- grounds for the sun-burst and the flying shadow. Light beams and flying shadows are some- BROKEN AND SHADED LIGHT 37 times seen under moonlight, but they are not so marked as those produced by the sun, be- cause of their want of definition. The moon- burst attracts little attention on the land ; and on the sea, where there is reflection from a ruf- fled surface, the spot made by falling light is apparent enough, but seldom the shaft itself. The light is oftenest seen far out upon the horizon, and is merely a flicker and a sparkle upon the water. As for the flying shadows of clouds at night, they are dark purple in tone and are sometimes weird in shape, but unless the night is very bright, they are not usually noticed. Shaded light is somewhat different from broken or clouded light. It is not produced by shattered parts of direct rays that steal through vapors and cloud- veils, but by widely diffused or reflected rays. The direct beams are usually cut off by an opaque substance, and the light in the shadow is received from the re- flecting sky, the air, or some other illuminating or light-diffusing body at the sides. The earth as a globe is a good illustration of this. It is light on one side, and its opposite side would be absolutely black were it not for such reflecting bodies as the moon, the planets, and possibly 38 NATURE FOB ITS OWN SAKE the illuminated upper atmosphere counting oat for the present the faint if direct light of the stars. Were it possible for a tree or a house to be in the far upper space where there is no air, its sunlit side would be intensely brilliant and its shaded side coal-black ; but on the earth the shadow of a tree or house is illu- minated by the atmosphere surrounding it, and by the side reflections thrown upon it. It is the diffused light, produced by atmosphere or otherwise, that makes a shadow luminous, and it is the sharp, direct light that makes a shadow dark. One may state a general rule in these terms : The greater the diffusion of light, the greater the expansion and illumination of shad- ows ; the sharper and more direct the light, the more contracted and the darker the shadows. We can see this well exemplified almost any night by studying the light of the electric arc- lamp. It is the strongest and the most direct artificial light we possess ; moreover, it is a white light, with much of blue and violet in it, and the shadows produced by it are very dark and clear-cut. Seen at night, these shadows cast by the bare limbs of a tree upon pavement or upon snow are precisely edged, have little penumbra, and are almost inky in BROKEN AND SHADED LIGHT 39 their blackness. Gas-light will cast no such shadows, nor will the sun, nor will the arc- light itself when muffled by a white globe. Anything like thick atmosphere, a cloud, or a milk-white glass that will spread the light over great space will lighten and expand the shadows at once. Hence it is that on cold, clear days, when there is little dust or vapor in the air to diffuse light, the shadows are darker, sharper, and less noticeable in their coloring than at any other time, while the hot days, with their thick atmospheres, produce opposite results. In America the heated days of early autumn, so remarkable for their hazy envelope of air and bright coloring, produce odd changes in the illumination of almost everything in land- scape. The shadows become much frailer in body, more transparent in light, with very pro- nounced hues, especially in the tones of lilac and blue. During the three heated days of September, in 1895, I had the opportunity of studying color effects, in both light and shade, in the woods and fields near Princeton, New Jersey one of the most brilliant spots in au- tumn I have ever known. The studies were interesting, but the material was so bewilder- ing in variety that I found great difficulty in 40 NATURE FOR ITS OWN SAKE locating causes and arriving at conclusions. The trees, the bushes, the field grasses were already tinged with autumn hues, and these hues, enhanced by the heat, made the land- scape appear crude and violent in its coloring. No imaginable tint was absent from the scene, and the greens, reds, yellows, and oranges were flaring in their intensities. But what impressed me more than anything else was the iridescent coloring of the atmosphere, the wavering of the heated air, the faintness of the shadows and their pronounced body of color. The pre- vailing tints in the shadows were lilac, violet, and rose. There were few shadows that were colorless, and few, if any, wherein the local color of the ground or object they fell upon was not twisted or distorted somewhat by a reflected or a complementary color. It is not a new theory of science that every color casts its complementary hue in shadow. The practical working of it may be frequently observed in nature. A sheet of white paper catching the light from a red sunset will receive a green shadow from an object interposed be- tween the paper and the sun. The same red light of sunset falling upon snow will some- times produce green in the shadows of trees BBOKEN AND SHADED LIGHT 41 and bushes. Dr. Weir Mitchell has noted yachts at sea sailing in the track of a fiery red sun with the shadowed white sails showing " a vivid green;"* and I have seen more than once the white sails of yachts crossing a yellow sunset when the change to blue in the sails was strongly marked blue being the complement- ary color of yellow as green is of red. Un- doubtedly the yellow sky at sunset is measur- ably responsible for the blues and purples of the mountains below it, and the more intense the yellow the stronger the blue-purple. If the sunset shows greenish-yellow, the mountain shadows will be violet ; if orange, the shadows will be cyan-blue ; and so on throughout the gamut each color will disclose its opposite in shadow. This is scientific theory, and it has been de- monstrated and proved true of nature when all the conditions are just right. The only trouble is the conditions in nature are seldom just right. The complementary coloring in the shadow is apparent only on certain days, and under certain lights, atmospheres, and temperatures. It is an error to suppose that a color is always casting its complementary hue * Doctor and Patient, page 176. 42 NATURE FOR ITS OWN SAKE in shadow or, at least, an error to suppose that it is always apparent to ns. There are in- fluences, too, such as the local color of the ground and the sky reflection, that may neutral- ize or utterly destroy the complementary hue. It might be thought that a yellow sun at midday would produce blue shadows under the green maple on the lawn, but as a matter of fact it does not. The color of the shadow, whatever it may be, is absorbed and lost in the green of the lawn upon which it falls. The same tree shadow falling on pale-gray clay, or across a sandy road, will show blue or lilac at once ; but I do not think this is owing necessarily to the presence of the complementary hue. It is more likely caused by sky reflection, helped out, perhaps, by atmospheric reflections from the sides. The blue shadows upon snow, so common in winter, are never seen except under a blue sky ; and the bluer the sky the more apparent the blue in the shadow. They are produced by sky reflection, and the sky coloring is faintly apparent on the snow in full sunlight, but more obvious, of course, in the shadow. These blue shadows are stronger at sunrise and at sunset than at any other time. Under a clouded BKOKEN AND SHADED LIGHT 43 sky they disappear entirely, and only a gray effect is apparent. Just before dusk, when sometimes the clouds become empurpled, the whole body of snow will take on a purple re- flection. The same or a similar effect is no- ticeable in the sand dunes along the sea-shore, though sand is perhaps not so good a reflector as snow. I should account for the lilac shadow on the clay or broken-stone road in the same way. It is a mingling of local color with sky reflection and side lights rather than comple- mentary hue. A rough surface like a green lawn or a meadow will not show a colored shadow at any time or under any conditions, so far as my observation goes ; and I believe the reason for it is that it has not a favorable sur- face for reflection. If colors were always pure, and if side lights, atmospheres, and sky reflections could be elim- inated, we should undoubtedly see the scientific theory of complementary colors always demon- strated in nature ; but the problem is compli- cated, and all talk about ' 'pure colors " is mis- leading. Nothing is pure ; everything is mixed and alloyed. The neutralizing effect of side lights, complementary and reflected hues, and local grounds, puts scientific calculation out 44 NATURE FOR ITS OWN SAKE of countenance. A pure color in nature is always more or less bleached, grayed, silvered, or gilded changed at least from its original estate by these conditions. "What might be the green of a maple-tree lighted by sunlight alone is one thing ; what it is lighted by sun- light, sky-light, and reflected light from the earth, not to mention atmospheric influence, is quite another thing. When all the factors are considered, we have anything but a pure green in the tree. It is, doubtless, a mingling of many hues that favors the mauve, the rose, and the lilac shadows. But then, again, they seldom appear unless the day is hot and the air thick, which leads one to think that atmospheric re- flection plays some part in their production. The cause can be conjectured only, but there is no doubt about the effect. The colored shadow is a reality, though its recent discovery finds people still somewhat sceptical about it. We have seen that clear light is favorable to the sharp-cut shadow, and that when the light is more widely diffused by atmosphere, or in- creased by reflection, the shadow begins to lighten, to become vague and soft on the edges, and to be enveloped by a penumbra. When the light is still more widely diffused and broken BROKEN AND SHADED LIGHT 45 by coming through clouds, it is commonly sup- posed that the shadow disappears entirely. We think of a cloudy day as a shadowless day, and practically it is so. The outlines of the shadow are lost, and yet the shadow itself is there, if we will but look for it. The green maple on the lawn has its breaks of light and dark seen in the foliage, and its form is cast in shadow on the ground, but the latter is very faint. It is only by the generally darkened tone that we can detect the shadow on such a day, and even then there is little distinction in color between it and its surroundings. Sometimes at a distance the shadow will appear bluish, but that effect is atmospheric rather than reflective. Sometimes, too, odd colors will creep into the shadows when the sky overhead is clouded and there are spots or breaks of light along the horizon ; but when the whole sky is under a veil of cloud, the color of the shadow is practically neutralized, and takes its hue from the ground upon which it is cast. The conditions of shadow production under moonlight are similar to those under sunlight, except that the degree of both light and shade is largely reduced. That the direct moonlight produces color wherever it strikes the garment- 46 NATURE FOB ITS OWN SAKE Star thadowt. ing of nature is undoubtedly true, but it is al- ways a subdued dull color. And the shadows, though they are luminous and not black opaque patches, have only dull shades of blue, purple, and gray. There is a modern tendency to see too much color in moonlight in fact, to see more than really exists. The old idea of the whiteness of its light and the blackness of its shadows has passed away, but the new idea has some extravagance about it. Colors of every kind under the moon are far removed from the feeblest of daylight tintings. Feebler still than the moonlight is the light that comes from the stars. The planet Venus and many of the fixed stars are bright enough to throw at times a long reflecting track upon ruffled water, but the colors produced by them upon landscape are blurred into smudges of dark purple and blue, and the hues of the shadows are too vague to be seen. CHAPTER III THE BLUE SKY THE two great expanses, the blue ocean at our feet and the blue sky over our heads, are both impressive in vastness the ocean more than the sky, possibly because we are familiar with its extent and have felt its power. We know, in a vague way, that the sky is even vaster than the sea, that it is the open field leading into interminable space ; but its very obvious coloring, its apparent arch on all sides springing upward and inward from the horizon, its fixity, give us something of a false impres- sion. We are inclined to regard it as a great blue dome or roof, a something tangible that is supported by the horizon-rim, a concave sur- face looked at instead of a vast transparency looked through. And there is some excuse for our regarding the blue sky as an actual surface. It is the outer envelope of the globe, and is made up of the blue rays of the sun reflected from atmospheric 47 Impret- tiontofthe iky. 48 NATURE FOB ITS OWN SAKE particles. These reflecting particles seen in mass apparently make a roof above us which *ooks to be ten or fifteen miles in height. It is merely an appearance, however, and our not too reliable eyes deceive us. It is known that the atmosphere is from two hundred to five hun- dred miles in thickness, perhaps more, and there is no demarcation line where the blue be- gins or ends. Nor is there any point in this blue where cloudiness, haziness, or opacity shows. There is not a blur or film upon it, save where it is influenced by earthly vapors and dust. The sky itself is everywhere transparent, else we should not receive light through it or see the sun, moon, and stars shining beyond it. The recognition of sky distances is not easily made by the eye. A glance upward may tell us of five or fifty miles, as our imagination rather than our focus is adjusted. Looking out and over a tract of earth, we conceive distance by perspective lines, by objects decreasing in size, by the diminution of color, and the in- creased thickness of atmosphere. They are all optical guide-posts by which we can reckon with depth and width. But no such conditions exist in looking skyward. It is true we are looking through thick air to thin air, and beyond that THE BLUE SKY into black space, but the color gradations are so subtle that we do not perceive the changes from one to another. Clouds help us somewhat in increasing the feeling of depth, for they are perspective points five or six miles on the way at least. Sometimes a pillar of cumulus will rise in the air thirty thousand feet from base to top, and tracing this upward the eye may see far above it the drift clouds of the stratus, and still higher, like specks upon the blue, the fine- spun fibres of the cirrus. This will give some idea of distance, though it is not entirely satis- factory. The view from Alpine peaks, where we are already twelve thousand feet up, and see still far above us against a violet sky the white spirals of the ice clouds, is not more satisfactory, save that in the thinner and clearer air the feel- ing of space is greater, and the sky becomes more of a blue wilderness than a domed roof. We comprehend the breadth and reach of the sky perhaps as little as its depth. Our horizon is an apparent circle as our zenith is an imagin- ary point. The circle is twenty, fifty, or from high ground perhaps seventy miles in diameter, but we always see its outside limit the com- plete circle no matter how vast the view. No- where is the eye so hemmed in, nowhere does 60 NATURE FOR ITS OWN SAKE the horizon-ring appear so small, as upon the open sea. The ship upon which we stand is the centre of a watery field, the mainmast points overhead to the centre of the blue firmament, and all around spreads the deep azure glow. Judging from vision alone the world appears very small. The uttermost rim is just beyond us. The ex- panse of the sea and the reach of the atmos- phere about the whole globe are practically un- felt. Even the height overhead seems greater than the sweep before and after us. The limi- tation becomes still more limited when the va- pors lying along the surface of the sea thicken the air and obscure the sight. We cannot as a general rule under favorable conditions see more than fifteen or twenty miles across sea water, and even in calm weather the horizon is often clouded by vapor banks that lie along it like a row of faintly seen hills. All this helps the illu- sion of being circled and shut in by the horizon. Then again the sense of distance by perspective lines is practically annihilated. Occasionally the skeleton masts and. black trailing smoke of an ocean steamer, or the tower-like looking sails of a square rigged ship appear, and act as catch-points ; but these are slight, and as for aerial distance we recognize it only by obscurity THE BLUE SKY 51 of coloring, which at sea dulls the vision in- stead of clearing it. It is on the land, and from the mountain-top, that we gain the best idea of the round reach of the sky. From such an elevation we not only see hills and valleys stretching away and down the sweeping world-circle, but if the sky be spattered with the white cirro-cumulus clouds, driving along in flocks before the wind, these, too, will seem to slope outward and down- ward like the earth. The result is that the im- pression of expanse in sky and earth is prodig- iously enhanced. The view is awe-inspiring ; and it is not necessarily so because it belittles the objects directly below us, but because it gives us a larger idea of distance, space, and sweep. The world seems a greater globe, the sky becomes enormous, and the imagination rises to meet the new presentation. There is no feature of the earth that can be regarded as more fixed, more permanent, than the blue sky overhead. And yet it seems as though a strong wind might blow it away. Winds, however, have small effect upon it. Clouds and storms pass across it, altering and obscuring it to our eyes, but beyond the local disturbance we know the sky is as serene and NATURE FOE ITS OWN SAKE unchanged as ever. It never seems to move, it never seems to shift ; and yet again, it is far from being an unvarying appearance. Sir Isaac Newton discovered years ago, from the twinkling of the stars and the shaking of shad- ows cast by high towers, that "the air is in a perpetual tremor/' Down close to the ground on a hot day we can see, in little, this tremor of the air as the heat currents rise from the earth ; and the mixture and intermixture of hot and cold currents in the upper air, the blowing of winds, and the drift of clouds must shake and disturb the lower layers of the blue, though this dis- turbance is not often noticed by us. At times I have seen, or fancied I have seen, in studying the clear sky, what might be called waves mov- ing across it. The motion did not seem to be that of ringed waves, such as one sees when a stone is thrown into a pond, but of deep undu- lations of varying blue succeeding each other slowly like the heave and roll of a glassy sea. Only on very hot days has this effect been ap- parent ; and I would not be certain that it is an actual fact, for the eye after long gazing at light and color is liable to become confused and see falsely. Still, I have seen the appearance a number of times, and I believe it to be reality THE BLUE SKY 53 rather than illusion. What causes it I cannot say, but it would seem to belong to some shak- ing of the lower atmosphere, for I have never seen it from high mountains. The lower atmosphere is, indeed, responsible for most of the volatile capricious appearances of the sky. From mountain-tops the sky is not so changeable, the stars twinkle less, show- ing that the atmosphere is quieter, and the face of the blue more uniform and serene. It lies there calm as at creation's dawn, lighted as was the old Mosaic firmament, and studded with the same jewel-like stars. It seems above and beyond all local and temporary disturbances. Winds mark it not, storms are far beneath it, heat, dust, and moisture effect it but slightly. It pales and lightens under the sun, deepens under the moon, and darkens under the stars, but in other respects it shifts not. An enor- mous sweep of violet-blue, it rests, a type and a symbol of unchanging serenity. And oh, the mighty silence of the upper sky ! What a contrast it is to the noisy, wind-swept earth and the restless ocean ! Infinite realms of violet-blue sweeping outward and upward, yet from them comes only the Great Silence the hush that tells of limitless space. No 54 NATURE FOB ITS OWN SAKE shock, no jar, no clash ; there are no hidden spots of earth so silent as the depths where the stars lie buried. This perpetual violet-blue glow, unmarred and unspotted by high light or shadow or vary- ing tint, save such as it receives from the sun, might be thought monotonous, did we always have it before us. But humanity does not make its abiding-place on mountain-tops. It prefers the valleys, and there the vapors and earth mists and dust particles produce a different- looking sky from that which is seen from the height of Mt. Blanc. It is fortunate that it is so ; yet, even in the valleys, people some- times complain (it is said that they do in South- ern California) of " the monotony of blue sky." In reality the " monotony" is not in the sky, but in the eyes that look at it. Seen through the lower strata of atmosphere, it is never the same for any length of time. Its form is con- tinually changed by clouds and cloud-flocks, new colors are being woven backward, forward, and across it, by shifting masses of atmosphere, its light is waxing and waning with the motion of the earth. There is a continuous weave and ravel of delicate-hued textures, and from dawn to dusk there is not a moment's pause. Sun THE BLUE SKY 55 flame shot through, earth reflection shot back, cloud light scattered between, all make their momentary impression ; and even at night, though the splendor is diminished, it is not extinguished. The moon lends a pallor to the blue, the Milky Way stretches its nebulous scarf across it, the Belt of Orion blazes out from it, the planets gleam on its dark ground, and through the long dusk of night the shift- ing splendor falls, the eternal round of beauty moves on. And by day or by night, seen from mountains or from valleys, what infinite tenderness in the blue ! Was ever depth and transparency of color so beautifully revealed, and by such subtle, elusive means ? Drifts upon drifts of air super- imposed one upon another, rings upon rings of illuminated atmosphere, rising higher and higher, and all of them deepening the tone, but never clouding its transparency. How far we seem to see into that blue, but there is no place where the eye reaches a background no place where a basic color appears. It is always a spectral abyss a blue dream resting above us, which the mind of the human has never been able to grasp as a reality. It is not to be wondered at that the tender- 56 NATURE FOB ITS OWN SAKE ness of color and the varied hues in the sky are unseen by the average person. I have never met anyone, other than a scientist or a landscape-painter, who could conscientiously say that he had spent five consecutive minutes of his life looking at the blue above him. Its colors are not violent enough, nor its changes swift enough to attract attention. A scarlet cloud draws the eye at once, but the clear sky, with the sun burning a great hole in the blue, and throwing off a ring of pale yellow light that radiates outward, decreasing in the most delicate gradations until lost in the pre- vailing azure, is scarcely ever remarked. From dawn to dusk pale tints of silver, lilac, and ashes of roses lie all around the horizon - circle, reaching up toward the zenith as though aspir- ing to be rid of earthly taint ; hour after hour the sky overhead is passing from dark blue to pale yellow, from pale yellow to amethyst, from amethyst to opal; evening after evening the cloudless sun goes down, leaving pale bands of spectrum colors on the twilight sky, but all this is waste splendor so far as the average person is concerned. People have an unhappy fashion of seeing with their ears. Someone tells them of the Alpine glow upon the snow-cap of the THE BLUE SKY 67 Jungfrau and they go there to watch, perhaps days at a time, for its appearance, when they might see the same pink glow upon their own skies at home almost any summer evening. It is not necessary for one to go beyond the door- yard to see beauty. The open sky will reveal more varied lights and colors than anyone could schedule or tabulate or talk about in a lifetime. Seen from our valleys, instead of being a monotonous blue roof above us, it is, perhaps, the most changeable transparency that human eyes have ever looked at or looked through. But while this variety is true of any one patch of sky, it does not follow that all blue skies are alike, even in their variety. Atmosphere, upon which so much responsibility for light and color has been thrown, is the potent cause of many different skies over many different lands. In dry countries, where there is much dust in the air, the blue is often a pale turquoise, or if there is great heat, then it is pinkish, or rose- hued. One hears much in tourists* descrip- tions of "the deep blue sky of Italy," but if they mean by that a, pure blue sky, their descrip- tions are not accurate. It is oftener pale lilac, rose-hued, or saffron-tinted, and not to be com- pared in intensity and purity of blue to the skies 58 NATURE FOB ITS OWN SAKE of Scotland. In no warm country is there such clear blue sky as one may see in the no~rthwest of America ; and if we may believe the descrip- tions of Dr. Nansen, the Arctic explorer, this blue grows more intense as we move toward the poles, until at last it becomes of that violet hue seen from mountain-peaks. The Egyptian blue is often "deep" when the air is clear and still, but with winds, heat and dryness it takes on a warm tone as though it were seen through a red dust - veil. A similar effect may be noticed over cities like London, where smoke and soot are continually fouling the air. The blue has a suffusion of pink or copper-color that gives it a hot look. In moist climates like Ger- many or Holland, there are often very clear skies, but the moisture particles in the air usually tend toward the production of a pale, milky whiteness in the blue. Again, in all countries of the northern temperate zone the purest summer skies are in the months of May and June. After these months the hot and dry summer begins to pale the blue, and in the autumn, when the leaves are changing to gold and scarlet, the sky in perfect harmony becomes rosy and often opalescent. If people are little observant of the blue sky THE BLUE SKY 59 in its color transitions, they are, perhaps, even less observant of its luminosity or light-diffus- ing power. It is a popular belief that the sky is a screen or veil to the earth, and that its principal reason for existence is that it tempers light to human eyes by obscuring it. And that is partly true. But the blue also receives, dif- fuses, and transmits light. It is luminous, at times scintillant, in small bright points. By long and attentive watching one can actually see these little points of light twisting, curling, falling and disappearing quickly as though they were mere flashings of star dust. And this does not refer to that portion of the blue sky near the sun where shafts of light are thrown down, but to the portions far removed, which are seen, perhaps, when the sun itself is under a cloud. The pure blue throws out more light than we imagine. If a sheet of white paper be held under it, even when the sun is below the horizon and eliminated from the problem, it will appear much lighter than the sky. But is it lighter ? Paper is not a body luminous in itself. All the light there is in it is merely the reflection of what comes from the sky, and a reflection can never be so strong as its original. There is an apparent contradiction just here, 60 NATURE FOR ITS OWN SAKE which may, perhaps, be cleared up by some such explanation as this : Glancing up at the sky our eyes look inevitably into the shadows of air par- ticles ; the light that comes to us is transmitted through and between the particles. Glancing down at the paper, we are looking into the high lights of the paper instead of shadows ; the light is now reflected instead of transmitted. It is because of the coloring of the blue, and the transmission of light in countless infinitesi- mal points through it that we fail to appreci- ate its luminosity, and yet next to the sun and its reflections it is the most luminous phenom- enon in the universe. It blinds the light of the stars so that we fail to see them in the daytime, and even the moon looks pale and wan beyond it until the sun has gone down and the light fades out of the atmospheric canopy. Upon the earth its effect is equally apparent. The snow reflects the light of the blue sky like the sheet of paper ; and the white daisies of the meadow, the white foam of the sea, and the sil- ver flash from still waters are but reflections of it. From mountain-heights at twilight one may see below in the valley the thread-like river, the white farm-houses, and the fields of yellow grain showing like spots of light upon the shadowed THE BLUE SKY 61 landscape. Whence comes the light thrown back to heaven by these objects if not from the blue sky overhead ? Because sky-beams do not fall like rain-drops we think, perhaps, they do not fall at all ; but their presence in reflection is about us on every hand. But possibly more beautiful than the trans- mission of light is its reflection as shown upon this same blue dome of air. When the sun is in the zenith all the light is transmitted, but when the sun is below the horizon its light is thrown up and under the blue and is reflected. Instead of looking into the shadows of air par- ticles we are looking into their high lights. This gives the effect upon the eastern sky that we call the dawn, and the more gorgeous effect in the west, called twilight. These two effects are the only ones that reveal fully the reflecting power of the sky. If we could rise above the earth and from the moon look out tow- ard this world of ours, we should doubtless see it muffled by a great luminous covering. The light from it would all be reflected and the white, misty air might completely hide the earth from view. It would not, however, be a brilliant or scintil- lant light. Like that of the dawn, it would be softly pervasive. The atmosphere from which Reflection from the blue. 62 NATURE FOR ITS OWN SAKE the dawn is reflected is not hard or smooth like metal ; it is not so compact even as the softest, thinnest cloud of the stratus, yet what beautiful light it throws off ! The white light that hangs over a city at night when there is fog, caused by the glare of many lamps thrown back from the fog bank, is brutal and coarse by comparison ; and the ruddy sunset caused by dust and cloud is more palpable and less crys- talline. There is no glare or flare about the dawn. The light comes from a deep transpar- ency quivering under the rays of the sun, re- ceiving its illumination in straight shafts of fire, and yet reflecting it with a softness of glow that delights the eye by its purity and delicacy. Surely this light of dawn is the highest mani- festation of beauty in the universe. Colors do not equal it, lines and forms of cloud and earth are petty compared to it, shadow is its very antithesis. It is not wonderful that it should have been the inspiration of Orphic song and the symbol of deity in ancient religions. To- day it seems a sign of preternatural glory even to modern materialism. Not the sun itself. but its light (symbolic of the purity and lumi- nosity of Deity) bowed the head of Zoroaster. THE BLUE SKY 63 The faith is strange with us now, and yet how well founded it was in natural religion. In- stinctively all races of men, whether savage or civilized, lift the hands and raise the eyes toward the heavens as though beyond the blue dome rested the seat of final justice, and its shining light was a manifestation of Supreme Power. The spiritual in man has always looked upward and counted the future abiding-place as somewhere beyond that sky ; but the light wherewith God "covereth himself as with a garment'' is no longer regarded as a token and a message a call to thanksgiving and to prayer. The muezzin's voice, the angelus bell some human ritual now bends the knee where once the white dawn drew all eyes as to the open gate of paradise. In the long centuries of his- tory how many prophets and peoples have gone their way to the grave following symbols of their own making devices that have turned to dust and mingled with human clay ! How many times has the old order changed ! How many times have new faiths, new symbols, new signs arisen ! Yet the light in the east has never changed, never lost its lustre. Its glory was from the beginning as it shall be to the ending. Modern science may write it down as 64 NATURE FOB ITS OWN SAKE Significance a material phenomenon, and modern creeds may discard its worship as idolatrous ; but priest and scientist, in common with all hu- manity, have felt its splendor and known its beauty. Was beauty then made for ashes, and has splendor no significance ? The aspiring soul will not so account them. It believes that He who stretched out the heavens as a cur- tain and laid the beams of His chambers in the waters makes Himself manifest in the splendor of His light, and in the beauty of its reflection upon the morning sky. CHAPTER IV CLOUDS AND CLOUD FORMS A CLOUD is always a cloud, no matter by what name it may be called or what its form or height above the earth. The fog that knocks about our ears is made up of the same visible vapors as the heaped-up cumulus rising tower-like thousands of feet above us. That one lies along the ground and that the other rises to a lofty altitude is due merely to a differ- ence in temperature and density. Clouds are formed by sudden lowerings of the temperature of moist air; and this lower- ing of temperature is usually caused by warm air rising into higher altitudes, expanding as it rises and cooling as it meets with the upper cold-air currents. The simplest and most fre- quent manner of cloud-making is this : The radiation of heat from the earth forms into a column-like current of air, and the natural tendency of this current is to push upward, seeking an exit into cooler regions. It keeps rising, expanding as it reaches thinner air, 65 Cloud- making. 66 NATURE FOR ITS OWN SAKE cooling and becoming moister as it meets with cold currents, until at last it attains a height where the dew-point * is reached. Then begins the change into cloud. The hot air of summer rising upward reaches its dew-point very soon, and the usual result is the formation of the large cloud which we call the cumulus. When there is little heat or moisture in the rising air, and no pronounced cold in the aerial regions through which it passes, as is often the case in the spring of the year, the air-current may rise to a greater height, and when finally the dew-point is reached the condensation appears in the form of the stratus or cumulo-stratus cloud. The dryer and colder the ascending current, the higher it must rise before it condenses ; and so at times it rises to the region of frost, then freezes into the thin clouds of the upper cirrus, which are made up of tiny ice-needles floating in curls and wisps against the blue sky. When once formed, the clouds are heavier than the air in which they float, and their nat- ural tendency from the moment of their forma- tion is downward and earthward. Knowing this fact, we are often led to wonder why they * See Chapter V. for explanation of the dew-point. CLOUDS AND CLOUD FORMS 67 do not fall, why they do not rest upon the earth instead of in the air. There are several reasons for their not doing so, and all of these reasons taken together may account for the ap- parent defiance of the law of gravity. Thistle-down will speedily find an abiding- place on the ground if there be no wind, but a gentle breeze will carry it drifting for miles, now high, now low, always soaring, sinking, floating. Something of this effect is produced upon the clouds by the winds and the moving currents of air. They are always forming and changing and being kept in motion by the winds. The travelling capacity of the different cloud flocks is, as we shall see hereafter, much greater than is generally supposed. Another and perhaps more potent cause of certain clouds being kept above us lies in the warm currents of air that are continually rising from the earth and buoying them up, very much as the heated air from a stove or lamp- chimney may buoy up a feather. We can see this illustrated in the formation of the clouds that sometimes hang about a mountain's top. The warm currents of air in the valley seek to rise up the side of the mountain because it is a natural conductor protecting them in measure NATURE FOR ITS OWN SAKE from sudden gusts of wind and cold. They rush up the mountain-side quite rapidly, as everyone knows who has stood there at noon- time and felt the draft upward from the valley. As soon as they reach the top of the mountain they are forced from shelter by the currents coming after, and meet with the cold winds above the peak. The result is quick condensa- tion and the formation of that cloud which is called the " cloud cap " or " night cap " of the mountain. It is broken and blown away by the winds continually, but it is also being con- tinually renewed by the ascending currents, so that apparently it remains stationary and in- tact. It does not sink down, because of its re- newal and because the currents in measure lift it up. Something of the same process is apparent in the formation of what is called the "banner cloud," which appears to fly out like a streamer from some of the Alpine peaks. This cloud is usually on the warm valley-side of the peak. The moist air from below rises along this shel- tered side to the tip of the peak before it is struck by the cold currents and condensed into visible vapors. Above it and at the sides the cloud is being cut off and drifted away by CLOUDS AND CLOUD FORMS 39 the winds. It is visible only where it clings to the lee-side of the peak, and it stretches out into the air as far as shelter is afforded it in the shape of a long, thin flag. At a distance it looks as though it were something perma- nent, whereas it is only a continuous-forming cloud cut sharp on its sides by the keen edges of the wind. But these illustrations are of exceptional clouds, and even with them the rising currents alone are hardly sufficient to account for their being sustained in air. The majority of clouds are formed in open space and their air-currents have no mountain-sides to protect them. Nor j are the common clouds subject to such violent destruction as the banner clouds. Moist currents are rising, clouds are forming and reforming, changing, sinking, disappearing ; but they are not often slashed into strips by the winds. We must seek a third cause for their being sus- tained in air, and it has been suggested already by the word " renewal." Clouds after they are formed are practically self-renewing. When the ascending air-current condenses into cloud the heat of the air-current goes upward with a tendency to form newer and higher clouds as it rises ; but the moisture of the current, robbed formed in open space. Self-re- newal of 70 NATURE FOR ITS OWN SAKE of its heat, forms into tiny, cold-water globules which have a tendency to sink down toward the earth. If the globules are large and heavy enough, owing to sudden condensation, they do fall to the earth in the shape of rain ; if they are small, as is usually the case, they no sooner sink down into the warmer air from whence they came, than they are evaporated and carried up to the top of the cloud, to be once more condensed into mist. The " re- newal " of the cloud then means that the water- globules are continually falling down only to be evaporated and sent up again for recondensa- tion. The cloud is always losing at the bottom, and its flat base shows the line where evapora- tion takes place ; but it is continually adding to itself on the top. The tendency of the cloud at the top is to form above itself drifts of higher clouds, but this is held in check by the loss of moisture, the dryness of the upper air, and the dissipating action of the sun's rays from above ; the tendency of the cloud at the bottom is to sink down, but this is held in check by the continual evaporation as the water-globules fall into the warmer, lower air. The cloud then, though in reality always changing, is apparent- ly stationary and without change. The ascend- CLOUDS AND CLOUD FORMS 71 ing air-currents feed it, and when these are withdrawn at night by the decreased radiation from the earth, the cloud sinks and disappears. Hence it is that when radiation begins in the morning with the warming rays of the sun, clouds are formed, and when it ceases at even- ing the lower clouds disappear and only the high and comparatively dry ones remain. The meteorologists have established four broad classes of clouds according to their differ- ent forms, and the different heights at which they are usually seen. The classification is largely for the sake of convenience because, as has been already intimated, clouds are substan- tially the same thing whether high or low in the air ; and the different forms run into each other so closely that it is often difficult to tell one from another. The four classes, beginning with the highest and ending with the lowest, are the cirrus, the stratus, the cumulus, and the nimbus. There are some subdivisions which may be recited in order, but the broad divisions are given at first to avoid confusion. THE CIRRUS (1) is the frailest and the lightest of all the cloud forms, and drifts at the great- est altitude. It is sometimes seen fifty thou- sand feet or more above the earth, though its 72 NATURE FOR ITS OWN SAKE usual elevation is not so great. Apparently it stands still in thin wisps and curls against the blue, but in reality it is a rapid traveller with the wind, and sometimes reaches so great a ve- locity as ninety miles an hour. It is not a large cloud and in form is curled like hair, is fibrous, or perhaps feathery. At times it is streaked across the sky in a light film somewhat like the Milky Way, but more frequently it is in small, thin patches. It has also many patterns that resemble stripes, tails, plumes, and wings, but they are all diaphanous and film-like. When it appears in streaks and lines these are usually parallel to the wind, and are commonly spoken of as " mares'-tails," ' ' goats'-hair," or " cats'- tails." These clouds often move in irregular, straggling groups. There may be only a few straw-like wisps, and then again the upper space may be spattered with them. Too thin and nebulous as a general thing to show shadows, they are the brightest of all the receivers and reflectors of light. This may be for two rea- sons. First, they are higher than any other clouds and receive a more powerful light from the sun because of the clearness and thinness of the air in which they drift ; secondly, they are ice-clouds, that is, made up of needles of ice, CLOUDS AND CLOUD FORMS 73 and are more capable of reflecting light than the ordinary vapor clouds. Certainly their luminosity is their strongest feature aside from their peculiar spray-like or feathery form, though their color is often remarkable. At dawn they are the first ones to catch the light from below and reflect it in yellow or pink, and at twilight they are the last ones to fling back the scarlets of the sinking sun. These clouds are apparent in all countries and in all skies, and are ever tenants of the upper region, though some of their branches or manifestations appear in connection with clouds of the middle region. The cirro-stratus (a) is a mixed or composite cloud made up from the cirrus and the stratus. It is not one of the four large classes, but rather a hybrid variety that must figure under a sub- division. In reality it is a part of the cirrus, which has become slightly changed in its form and elevation by a sudden increase in its moist- ure. Grown heavier and denser, it has de- scended and woven itself into long, thread-like lines resembling a net or veil stretched across the sky. Its appearance is usually thought to be indicative of approaching storm, and the di- rection it takes shows whence the storm is com- ing. It is a frost cloud, is frequently seen at 74 NATURE FOR ITS OWN SAKE an altitude of thirty thousand feet, and has a maximum travelling velocity of about seventy miles an hour. It is the substance from which the halos about the sun and moon are woven, and is very thin, almost transparent. Like the cirrus, it casts no patches of shadow, is pale white, and when struck from beneath by the rays of the sun below the horizon is marvellous in its delicacy of light and color. The cirro-cumulus (b) is another mixed cloud. When the cirrus descends still lower than the region of the cirro-stratus, its edges of frost begin to melt like the sharp sides of a snow-bank. It then takes on a woolly appear- ance similar at times to the small, detached portions of true cumulus, though it lies in a much higher field of air. It has a fashion of breaking up into small, rounded patches like rotten ice in a river, and of drifting across the sky in vast companies that almost hide the blue. There are two forms in which it ap- pears. One is called the " dappled sky " or sometimes " wool - pack " from its fleecy nat- ure ; the other is the " mackerel sky," which is not fleecy but hard-looking. The latter is rarely seen as compared with other cloud forms, and in England it is always thought to be the CLOUDS AND CLOUD FOEMS 75 harbinger of fair weather. Both forms of this cirro-cumulus are frost clouds. They drift at an altitude of about twenty-two thousand feet, and have a maximum velocity of about eighty miles an hour. Their movements across the sky seem to be systematic and orderly, though of course the regularity of their driftings is dependent entirely upon the steadiness of the upper wind-currents. THE STRATUS (2) is a flat sheet cloud extend- ing in long lines across the sky, at times bridg- ing it, covering it from horizon to horizon. It is the cloud, let us say, of the middle-air re- gion, though every cloud that has a sheet-like form or looks stratified is some kind of stratus. It is usually formed when there is little wind and only a mild radiation is going on. The air as it rises gets gradually cooler until the dew- point is reached, when this cloud forms and extends itself across the sky in long, thin drifts like the smoke from factory chimneys in calm weather. In color it is a gray cloud, though occasionally, when very thin and the sun or moon is shining through it, it looks bluish in tint. At times it has a concave or a convex ap- pearance, and at other times it is wavy or un- dulating. It is from ten to twenty thousand 76 NATUKE FOE ITS OWN SAKE feet above the earth, and though its movement is hardly perceptible to the eye, it may be drift- ing at the rate of fifty miles an hour. Its effect in making a hazy day is quite noticeable, and at sunset, when it lies across the western hori' zon in bars, it is often very pronounced in reds or chrome-yellows. The strato-cumulus (a) is another and per- haps more common form of the stratus. It is a heavier variety, darker in color, and more roll-like in form, caused by its having about it something of the lumpy nature of the cumulus, yet with enough of the stratus to make it form in a layer along the sky. It is a cloud that may send forth rain, though it often overhangs the earth in dark folds for days at a time with- out giving forth a drop. At times it looks like a compact, dense rain cloud, and when it as- sumes this shape it is often confused with the nimbus. CUMULUS (3) is the name given to any cloud that has a heaped-up, mountainous, or lumpy look about it. The white patches that bowl across the sky on a summer's day are detached portions of cumulus ; but the most noticeable form of it is the " heap " cloud that on warm afternoons lies off in the southern sky, rising CLOUDS AND CLOUD FORMS 77 far upward toward the blue in fantastic turrets, domes, and peaks. The bases of these clouds are usually dark in shadow, flat, and cut sharp ; while their tops are cast in wreaths and billows of vapor. They appear at times to be of great height, for though their bases are usually not more than five thousand feet up, their tops sometimes reach forty thousand feet from the ground. At such an altitude the crests look woolly, which probably indicates that the cloud has reached a cold region and has changed to frost-dust on its top. Usually these clouds appear to stand firmly and to be motionless, though they are always changing, their bottoms sinking away and their tops being continually renewed. Moreover, they are drifted by winds at the rate of about twenty-five miles an hour, though at other times they may scarcely move at all. After sunset they usually sink and dis- appear entirely. The heavy cumuli are summer clouds, and are not seen in cold climates nor upon cold days. The tropical region is their home, though they are native to the temperate zones in midsummer, and are often seen rising along the horizon like a range of snow-clad moun- tains, with hills and valleys running up or down 78 NATUKE FOE ITS OWN SAKE or across them. In outline they are graceful, and in light-and-shade they are often sharp-marked. The best time to study them is in the evening, when they are lying back at the south or east. Then the pinnacles and peaks glow with light, and make the snowy-mountain illusion more palpable than ever ; or they turn into phantom, rock-based promontories with spectral tides of vapor at their feet that sound not and shock not, yet rise slowly higher and higher upon the snowy walls. Occasionally a tall, heavy mass is veiled by a thin layer of the stratus, through which the form of the cumulus is seen to burn like a great opal. Sometimes, too, a heavy cumulus is seen through city smoke at sunset glowing like molten metal. When in the west and in front of the sun this cloud is the one that shows us the gold or silver lining ; and under sunset light it is possible for it to take on all tints and shades. When it is not near the sun but lies off at the side, we often see the pink, " Alpine glow " suffusing the white cas- tellated tops ; and the shadows caused by sharp breaks of form often show blue, lilac, and even pale green in hue. v The cumulo-nimbus (a) is substantially the same cloud as the cumulus except that it drifts CLOUDS AND CLOUD FOEMS 79 at a slightly lower level, is not a tall tower cloud, and has in it an admixture of the nim- bus or rain cloud. It is in fact a form of rain cloud and is responsible for the "sun-shower " as well as for others of greater force, like the thun- der-shower. It is also a cloud that shows a sil- ver lining when seen against the sun, and at night it reflects heat-lightning very brilliantly. In the daytime its base appears dark, its top light ; and at twilight, when lying off in the east, it banks up at times like a table mountain in layers and terraces that reflect the pinks and violets of the sunset. Its usual altitude is about four thousand feet, and its movement is more rapid than that of the cumulus. THE NIMBUS (4) is the rain cloud, and every cloud from which rain falls is some form or combination of the nimbus, though the nimbus proper is the flat, sheet-like or rolled rain cloud. It is the closest to the earth of all the clouds and is consequently the first one to receive the smoke, dust, and heat arising from the earth. By comparison it is a foul cloud, and is for that reason a rain cloud the formation of vapor spherules being, perhaps, dependent upon the presence of dust-particles in the air. The nim- bus takes all forms according to its density and 80 NATURE FOR ITS OWN SAKE velocity. In afternoon showers it resembles the cumulus ; in driving storms it lies lower to the earth, moves in great, rolling puffs, or flattens out into thin, fast-flying sheets with ragged edges and long, projecting arms like antennae. At times, when a storm is prolonged for days, the forms of the clouds are hardly discernible ; the masses are lying low in the air and spread from one to another with such close connection that they look like one vast stretch of gray across the sky. In thunder-storms these clouds often bank up dark and threatening in the form of an advance-guard. They move forward quite rapidly and carry with them a rushing wind. The first-comers are always the darkest-looking and most violent of the storm, yet they give forth neither lightning nor rain. They seem to be only wind-makers, though it is common knowledge that clouds are not makers of wind, but merely manifestations of wind existent. The gray clouds behind the dark advance-guard are the ones that carry the rain. In tornadoes the darker ones often twist, writhe, and roll over one another as though pulled by a violent under-current of wind ; in cyclones the move- ment is similar, but from an opposite cause. In the latter case the pull is likely to change CLOUDS AND CLOUD FORMS 81 to a push caused by rising swirls of heated air trying to escape up a vortex into cooler regions. The color of the nimbus is always cast in gray, and the darkest portions are usually the ones under deepest shadow. Poet and romancer to the contrary, there is no such thing as a " black " cloud seen in the daytime nor for that mat- ter at any other time. The heavy storm-cloud may border upon purple, and sometimes pre- ceding cyclones it is sea-green, but it is never " black." The different forms and kinds of clouds given above enumerate only certain families. Aside from the large groups there are patches of cloud being continually woven or torn from one family to blend and intermingle with another family, thus making many hybrid varieties. It would be almost impossible to catalogue the dif- ferent cloud forms that one may see on an ordi- nary summer day ; or the parts of clouds such as scud, wrack, wreaths, and sprays wrenched away from the parent body by storms and squalls. The form of clouds usually gives the ear-mark of recognition to such families as the cirrus, the stratus, and the cumulus ; and yet this form is never the same for any length of time. It is Scattering cloud farmi. 82 NATURE FOB ITS OWN SAKE always shifting, changing being added to or subtracted from by varying conditions. It may describe the species, and yet is hardly to be called the characteristic feature. That which strikes us as peculiar and determinate about any and every cloud is its drifting, swaying lightness. The glide down a vast in- cline of air that marks a white swan settling to water is usually considered the most poetic of all motions ; yet it is somewhat gross and heavy compared with the grace of a moving cloud. A cloud drifts with the wind, not be- fore it ; it lies in the air, not beyond it ; it has no visible support and yet appears supported. Apparently defying the law of gravitation, it seems to have no relation to the earth, but like a phantom ship sails the celestial blue, wholly unconcerned as to destination, wholly careless as to dangers. All of them, singly or in flocks, are mere vapors such things as dreams are made of the wonder- world of childish fancy, yet how beautiful they are ! " Forming and breaking in the sky, I fancy all shapes are there ; Temple, mountain, monument, spire, Ships rigged out with sails of fire And blown by the evening air." CLOUDS AND CLOUD FORMS 83 They rise, fall, or change before onr eyes with no effort, no sound, no apparent design. Now they are scattered wide over the blue, now they are huddled together and driven in flocks by the wind ; but they never seem to be in a hurry. An epitome of idle content, having no actual power in themselves, they are, never- theless, the visible sign of aerial energy. The wind blows them whither it listoth. They drift around and about the world and have no abid- ing-place, no resting-place on land or sea ; yet wherever they go they gladden the eye and cheer the heart, and in every landscape they are the bright spots of beauty. And what wonderful luminosity there may be in a cloud ! The upper cirrus just before sunset is often dazzling in its light, and when struck full by the sun's rays, there is nothing more intense in luminosity than the cap of the tall cumulus. The ancients felt the splendor of this cloud light, and it is not strange that the Old Testament writers should speak of the " pillar of cloud " that guided the wanderings in the wilderness, of God descending on a cloud, of a cloud as the resting-place of the Mercy Seat and the standing-place of angels. The purity of these white vapors of the upper air Drift of NATURE FOR ITS OWN SAKE seems uncontaminated by earthly touch, and their shining surfaces are not comparable to any terrestrial thing save the newly fallen snow glistening on the highest Alpine peaks. And in color what is, what could be, more gorgeous, without a note of discord, than the western clouds at sunset ? They have no hue in themselves, and yet, like the flowers of the fields and the waters in the lakes, they have the power of reflecting and refracting colors of the utmost brilliancy. And how vivid these hues become as the hot sun throws his parting shafts of fire over and under and through the fleecy drifts of vapor ! After the red disk has fallen below the horizon the scattered patches con- tinue to burn and glow in scarlets, golds, and pinks all imaginable hues from bright blood- red to dark violet. As the sun sinks still lower its shafts strike upward upon the under-sur- faces of the clouds, and for a time the color seems even more brilliant. And when the cloud-bars just across the horizon begin to dim their lustre the high, " mackerel sky " catches up the color and the flame mounts upward to the zenith, from cloud to cloud, like steps in a ladder of fire, lessening in glory as the height is reached, and finally lost entirely in the blue. CLOUDS AND CLOUD FORMS 85 Last of the twilight glories, when the light has gone out of the lower clouds and the white cumulus has turned to dark purple, the wavy forms of the cirrus may be seen flaming like wind-blown torches far up the western sky. Common as the sunset colors are, we never seem to weary of them. They are always things to look at and to wonder over. No hues seen upon the earth are so full of light and fire, so brilliant in variety. The colors of the rainbow show a celestial spectrum, but they seem to pale beside the sky-splendors of the west ; and as for the colors of the clouds at dawn, they are much paler than those of the sunset. At noon- time the clouds show no color in particular. Occasionally low-lying cloud flocks over a city like London will have a heated, flushed look, and when close to or under the sun they will glow like plates of hot iron ; but this is caused by local dust and soot in the air. Often, too, in all warm countries a cloud passing across the face of the sun will have silvery or golden edges, and a pyramid of cumulus may be pink in the lights and blue in the shadows ; but, aside from such exceptions, the clouds at noonday are practically white in light or grayed under shadow. 86 NATURE FOR ITS OWN SAKE We realize quickly enough how important to our enjoyment of landscape are the sky and the white clouds as soon as they are cut off from our view by the drawn veil of a rainy day. The variety of color in the sky and of movement and form in the cloud, the feeling of space, dis- tance, loftiness in them both, are gone ; and with them perhaps the most effective features of all landscape. Anything that obscures or shuts out sky-space, with its interminable depths of blue and its bright clouds, mars one of nat- ure's greatest beauties. Even a horizon-line so high as to narrow the sweep is objectionable ; and hence the valleys of the Alps, though grand enough in view of mountain bulk and snowy peak, are the least livable places in Europe. The great palisade of rock breaks the reach of the sky and we lose directly in color, light, and atmospheric perspective. On the contrary, a flat, low-lying land, though perhaps the last to be loved by humanity, is in the end the most livable of all. The prairies of North America, the plains of Lombardy, the flat lands of eastern England, are supreme in the feeling of space in sky and of distance in cloud. Something of the great charm of Venice lies in her flat lagoons and her great, uplifted sky ; and to those who CLOUDS AND CLOUD FOEMS 87 know their book of landscape well, the green fields of Holland arched by blue and white are the most restful, enjoyable, serenely beautiful lands on the face of Europe. CHAPTER V The vapor- capacity of air. RAIN AND SNOW IN order to understand the phenomena of ran and snow we must consider for a mo- ment some facts established by the weather men. I have no notion of trenching upon the domain of the meteorologist. Indeed, I had thought to write a book that would suggest some of nature's beauties rather than its bare facts, but I find it continually necessary to ex- plain beauty by first showing structural char- acter. The capacity of air for receiving and holding vapor depends upon temperature. It is small at low temperatures ; it is large at high tem- peratures. That is to say, the vapor-carrying capacity of a cubic foot of air is ten times as large at 100 Fahrenheit as at 32. At either temperature, when the cubic foot has all the vapor it can carry, it is called " saturated. " When more vapor is crowded in than the cubic foot can carry the result is condensation of the surplus into cloud and rain. Perhaps this can RAIN AND SNOW 89 be illustrated in a simple way by putting a sup- posititious case in which I shall use the figures of Dr. Eobert Mann. At 32 Fahrenheit a cubic foot of air can hold or carry 2.37 grains of vapor in invisible form. It is then said to have reached its " dew- point." If into that cubic foot of air 2.38 grains of vapor were injected, the result would be one- hundredth of a grain of condensed mist or cloud. At a temperature of 60 each cubic foot of air can carry 5.87 grains of invisible vapor ; at 80 each cubic foot can carry 10.81 grains. Consequently, if at any time or for any reason a saturated air at a temperature of 80 were sud- denly chilled down to 60, nearly 5 grains of sur- plus vapor would be condensed out of each aerial cubic foot in the form of tiny droplets of rain. If at a temperature of 32, the freezing point, similar conditions prevailed that is, if a saturated air at 32 were suddenly chilled down to zero a similar surplus quantity of vapor would be condensed in the form of crys- tallized spicnles of ice or snow. A more violent reduction in the temperature of a saturated cloud say from 100 down to 60 would pro- duce more vapor than the cloud could hold, 90 NATURE FOB ITS OWN SAKE and it would inevitably fall to earth as a shower. It is now generally held, I believe, that the cause of clouds and rain is largely, if not en- tirely, the cooling of air by expansion as it as- cends ; and that intermingled cold and warm air, and the chilling of air by cold bodies such as mountain-tops, have little or no effect. Cer- tainly the expansion of air is the final but not always the most immediate cause. The chill- ing produced by warm air driven against cold air and its result may be frequently witnessed in the winter season along the Atlantic coast of North America. When the wind shifts to the east we are all quite sure that thirty-six hours at least will bring rain, and usually it is not so long before the clouds begin to drift inland from the sea. It is sometimes thought that there is a storm on the ocean, and that it has been travelling landward for hundreds of miles. Occasionally that is the case, but more often the clouds and rain are formed along our own coast, and in this way : The sea is much warmer than the land, especially in the Gulf Stream region. Vast bodies of moist air overhanging it are driven in upon the land by the eastern winds. This land is ice-locked and very cold. BAIN AND SNOW 91 As soon as the warm air of the sea meets the cold air of the land a chilling-down process be- gins and condensation into clouds is the result. The coast is the line of condensation, and as these clouds move into the cold interior their vapor-carrying capacity grows less and less un- til finally rain is precipitated. Another illustration of cloud and rain mak- ing is often seen in the spring of the year, when a warm air blowing from the south meets a cold air blowing from the west. The warm air is forced up and over the cold air, clouds are formed all along the line of con- tact, and heavy rain is not the unusual result. Again, a sirocco blowing up from the south across the Adriatic will make the cool stones in the pavement of the Piazza San Marco at Ven- ice "sweat ;" and when this sirocco meets the Southern Alps and is tilted up into the cold snow regions of the peaks, condensation, clouds, and rain follow. Just how the rain-drop is formed seems not better known than the constitution of the spherule of moisture in the cloud. A recently advanced theory would seem to argue that moisture forms upon and about the tiny dust- particle in the air, using the particle as a nu- 92 NATURE FOR ITS OWN SAKE clens, so to speak, and that by augmented con- densation the spherule gradually grows to a rain-drop. Once formed, the drop has about it an elastic skin or envelope that prevents it from breaking unless pressed or struck by some body. Oftentimes it preserves its form against sharp shocks, as we may test by shaking the dewdrops on flowers, or observing the drops from a fountain thafc run across the surface of the water like pearls for some distance before coalescing with the main body. In the air the rain-drop is always perfectly round, as the camera shows us, even if it were not a necessity of that phenomenon, the rainbow. The size of the drop is doubtless dependent upon the amount of surplus moisture in the cloud. This in turn is dependent upon the temperature of the air and the extent to which this temperature has been reduced. Doubtless, too, the suddenness of condensation has some- thing to do with thp size ; and besides that the drop in falling probably unites with other drops, somewhat as globules of mercury co- alesce, or a rain-drop running down a window- pane gathers other drops in its downward course. That the temperature has much to do with the quantity of vapor in the cloud, and KAIN AND SNOW consequently the size of the drop, we may be- lieve when we consider how small are the rain- drops in winter and how large they are in summer. The first ones falling in a thunder- shower, for instance, are unusually large. Pos- sibly the size is caused by the outer edge of a heavily saturated cloud being driven by the wind against cold air and swift condensation following the meeting ; or it may be that the heavy drops fall from a very high cloud and coalesce with others in falling. It is usually only the first-coming clouds that cast the heavy drops, and after the first dash they grow finer, smaller, and more numerous. A thunder-storm comes and goes quickly, the moisture being in measure localized. Both its coming and its going present interesting, sometimes fantastic, forms of clouds that are continually torn, scattered and reunited by the drive forward of the wind. Usually the cloud is a thick one, and in its lowest part is dark, becoming lighter in its main body, and if it is a towering, cumulus cloud, its upper peaks may sometimes be seen before or after the storm, shining white in the sunlight. Beautiful by day, all the forms of thunder-clouds are even more beautiful by night, when lightning flashes 94 NATURE FOB ITS OWN SAKE illuminate them. Then they have a pale- bluish coloring, the light-and-shade upon them is clear-cut, and the feeling of massive form is convincingly brought home to us. The great, dark clouds lying underneath seem but the flat pedestals of the white peaks and spurs that far up the zenith seem to tower and rock slowly like icebergs on a stormy sea. At other times the clouds seem softer and roll upward in bil- lows and wreaths great vapory masses of blue- white that boil and seethe with the force of the winds. And how the currents of lightning pass through these heavy clouds without pro- ducing the slightest disturbing effect upon them ! If lightning were shaped like the classic bolt of Zeus, or zig-zagged and raw- edged, as popularly depicted, it might disrupt even cloud forms ; but instead of that it runs in streams and rivulets, and when seen in pho- tograph it often looks like an outlined map of the Nile, with its many mouths leading to the Mediterranean. Another accompaniment of the thunder- shower is the fringe of rain that may be seen trailing from the clouds as the shower passes to one side of us. This fringe waves slightly with the wind, and when seen at a distance looks as KAIN AND SNOW though it did not reach to the ground. As a matter of fact, some precipitations never do fall to earth. They are evaporated in mid-air and returned to the sky. The travel of the rain-fringe across the country, veiling and often obscuring the hills and meadows, is most interesting to watch as it shifts its form, color, and density, and darkens the green of the country over which it passes. It changes more frequently than we think, and is sometimes temporarily lost before our eyes, only to reap- pear again with startling brilliancy when struck by a chance sun-shaft. When the shower comes our way, the clouds themselves seem to undergo changes as soon as the rain begins to fall from them. The lumpy roll breaks and flattens in strata, or else it trails down in long, shaggy points. The whole landscape darkens as the shower approaches, the clouds become obscured, the trees blurred, and presently we are in the centre of a circle of rain through which we can perhaps see not more than a few hundred feet. When the shower is passing away, everything is, of course, reversed. The light increases, and often the vanishing rain clouds struck by the sun, gleam as frost-white as the castle-clouds of a summer afternoon. 96 NATURE FOR ITS OWN SAKE With the sun shining after a thunder-storm, and the light striking upon the clouds heyond us, comes one of the most noticeable beauties of the sky, the rainbow. It is caused by the drops of water in the air becoming prisms of light and casting the spectrum colors. A thin sheet of these falling drops is struck obliquely by the sun's rays, and each drop has light entering the upper portion of it, and undergoing two refrac- tions and one reflection. The exact scientific explanation of the arch of light, and how it casts the colors of the spectrum, is foreign to the present purpose. Suffice it to say that the arch is seen only when sunlight strikes falling rain obliquely, and that it shows the colors of the spectrum, beginning with red on the outside. The secondary or upper bow is like the first, only fainter, owing to a double reflection within the drops, and with the colors reversed that is, the violet is on the outside. The bow caused by the moon is much fainter than that caused by the sun, and is not fre- quently seen. It rarely shows distinct colors, and is most commonly seen as a pale gleam of white or yellow light. The three-days' storm of rain, common to all temperate climates, is quite a different affair BAIN AND SNOW 97 from the thunder-storm. It begins with no such frowning front, but has infinitely more en- durance because it is not localized. The clouds are spread over a large area of sky and they gather themselves together slowly at first. When condensation sets in and rain begins to fall it is slight, almost like a Scotch mist. But it soon gains in power, the wind rises, and the small rain-drops begin to drive toward the earth with great swiftness and force. The heavy drops of the thunder-shower, falling a long distance from high clouds, and falling straight, seem to have much less striking power than the smaller drops driven diagonally by the wind. Nor is the wave of a rain-fringe from a thunder-shower anything like so violent as the sheet of driving rain in the three days' storm. The latter shakes banner-like in the wind as though it were a veritable sheet held down from above, or it rolls in swift-moving undulations across the sky like the wavy light-flashes of the aurora. But there is little in the long storm to be ad- mired or enjoyed unless we ourselves happen to be in a tempestuous mood. The domed sky is shut out, the clouds make a flat, lead-colored roof overhead, or else they form in gray billows NATURE FOR ITS OWN SAKE like an inverted sea in storm. Color is gone save the vast monotone of gray, and form is al- most obliterated except in the lines of falling rain. The splash and beat of gusts upon the roof and the window-pane, the moaning and raving of the wind, are rather dreary ; and with- out, everything is even more dismal. Decidedly the best place is by an open fire with a book in one's hand. When, however, the rain has passed, and the sun is once more seen, we have an irre- pressible desire to come out from hiding, like the birds, and see what the rain has done for the world about us. The freshness of nature, the smell of the ground, the clearness of the air, the brightness of the vegetation the feeling as though the earth had had a bath and was waking, clean and refreshed are omnipresent. Color, too, seems revivified. The geranium and the rose are more brilliant, the grass greener, the trees more luminous, and overhead the blue sky is deeper in its coloring and light than possibly we have ever noticed before. This is all more marked in the country than in the city. The only noticeable thing about rain in the city is that it washes down the build- ings and cleans up the streets. The patches of grass and the trees in the parks do not seem RAIN AND SNOW 99 to respond to it so quickly as those on the lawns and fields out of town. This may be imagination with the observer, and yet it is well known that the rain which falls in the city is not the same rain as that which falls in the country, though both precipitations may come from the one cloud. City rain is fouled by passing through smoke, dust, and gases. It gathers sulphuric acid, which corrodes metal, paint, and iron, and certainly does not help vegetation. The coun- try rain is always purer because falling through a clearer air. Precipitation from the clouds usually takes the form of rain and hail in the summer, sleet in the spring, and snow or frozen ice-crystals in the winter. They are all easy to account for as regards their forms except hail, which is frozen rain perhaps, but a satisfactory explanation of how it is formed and frozen has not yet been offered. Hail falls in hot, sultry weather and with a thunder-storm. For that reason it is sus- pected that it has to do with electricity or is caused by it. It would seem at first blush as though those heavy drops of rain, which have been spoken of as the first to fall from the thun- der-cloud, were sometimes congealed to ice and united to other drops in the congealing proc- 100 NATURE FOB ITS OWN SAKE ess, and that hail was made in that way. The two precipitations, one in rain and one in hail, correspond in time, place, and circumstance, and apparently are identical with one another ; but the perplexing question arises, How does hail freeze in its peculiar form ? If a rain-drop fall- ing from a warm cloud should pass through a very cold current on its way earthward, it would be frozen into transparent ice ; but that is not the make-up of the hail-stone. The cen- tre of the stone is opaque, milky, cloudy, as though it were a tiny, frozen snow-ball ; and around this centre are usually thin, concentric layers of ice and snow formed like the layers of an onion. From its appearance one might say that it was a frozen particle whirled around through rain and ice clouds, gathering bulk to itself by contact, much like a snow-ball rolling down hill on a moist, winter day. The theory has been advanced that the rain- drop is caught up by powerful, ascending cur- rents and carried to regions of snow and cold, and afterward allowed by the declining winds to fall back to earth ; but if so, how does it arrange to get back in time to form the first fall from a thunder cloud ? It is more probable perhaps that the top of the thunder cloud reaches up RAIN AND SNOW 101 into the snow regions of the air, and inat pre- cipitation falling from it in the shape of snow gathers bulk to itself in descending until, pass- ing through the rain region, it adds an outer coat of ice. The hail-stone certainly falls a long dis- tance, as we may know from its striking power, but whence it falls, and just hoiv it is formed, the meteorologists have not yet definitely told us. The hail-stone is usually not larger than a cherry, though in description it is sometimes " as large as a hen's egg ; " and it has been seen as large as a good-sized apple, but not in the temperate zones. It is elastic, and the bounce of hail from the walk or lawn is a commonly observed fact. Sometimes with wind it drives diagonally to the earth, but more frequently it falls like the heavy drops of the thunder- shower. Usually there is nothing marked about its color. It is lighter in tone than rain, and when falling through the air shows blue- white. At times a very beautiful effect is pro- duced during sun-showers by the sun's rays flashing npon the stones as they fall. They are then dazzling opal-white, and quite dif- ferent from the rain-drops, which fall through sunlight like glittering diamonds. Occasional- ly one may see a hail-storm turned into some- 102 NATURE FOR ITS OWN SAKE thing like a rain of fiery red or yellow pebbles, by having the shower between him and a red or yellow sunset ; but this effect is of rare ob- servance. Snow is the excess vapor in the air condensed into spicules of ice. It forms whenever the temperature is below freezing, and many are the forms of flakes produced by the crystal- lizing process. When the fall is light and feathery, owing to a low temperature, countless variations of the six-pointed star may be seen on a dark ground, such as a coat-sleeve. When the temperature is higher there is a tendency toward agglomeration, or the union of many flakes into one. Snow falling from a cold into a warm stratum of air is softened around the edges, and we have what is called a "wet" snow that is, a snow containing considerable moisture and in form large and fluffy. The re- verse of this takes place when the snow is fall- ing from a cloud warmer than the temperature of the lower air. Then we have a hard, round snow, sometimes called "ball " snow. It would seem to be hardened and compacted by passing through the colder, lower air ; and when it reaches the earth its form is that of the fine snow that falls in the long, cold storms of winter. BAIN AND SNOW 103 In the highest clouds snow is always a possi- ble and often a necessary result of condensation. When it falls it frequently melts into rain in passing through the warmer and lower air. The storm that covers the top of Mt. Blanc with snow falls as rain in the valley of Chamonix. Many of the high mountains have their snow- line above which rain is not known, and we hear their peaks spoken of as being covered with "eternal snow." The words are not accurate, to be sure, for snow even on mountain-tops is continually melting and passing away into gla- ciers to be replenished by new falls ; but the de- scription is true enough in the sense that the peaks are always snow-capped. At the beginning of a snow-storm the flakes are few and large, and they settle to the earth like eider-down or thistle-spray. Nothing can exceed the gentleness of these first-falling flakes. They whirl and float and hover and fall so soft- ly, that not a leaf or grass-blade is stirred ; and they melt into the smooth surface of the lake without making the slightest visible impression. And how absolute the silence of their fall ! One by one they gather together on the earth without a sound, and in the morning when the children look out of the window they are sur- 104 NATURE FOR ITS OWN SAKE prised to see the white fairy-land, and they had no intimation whatever of its making. During the day, if the storm increases, the flakes are likely to grow smaller and harder the fall be- ing much like the smaller rain that follows the few large premonitory drops. With a high wind the snow drives almost horizontally at times, and when the wind is in gusts the snow- sheet waves more lightly and easily than the corresponding rain-sheet. In Northern countries the light snow driven by high gales often results in what is called a " blizzard " something almost impossible in the region of New York, though the name has been and is frequently applied to every severe snow-storm. A blizzard proper, such as they have occasionally in Dakota, brings with it a fine, driving snow that strikes the face like a shower of sand, stinging, cutting, and almost blinding one. The temperature during its prevalence is usually so low that there is little or no moisture in the air, and the blowing of the wind does not allow the snow to catch and lie upon the ground except in sheltered places. Gusts and eddies are continually swirling great sheets of it through the air. If the ground was previously covered with snow, the low temperature has RAIN AND SNOW 105 possibly prevented it from having anything like a crust upon it, and the first sweep of wind raises its light particles in the air to join the new-comers. The total result is blinding and confusing to the wayfarer. The air is full of flashing, dashing flakes, and one can see no farther in the maze than in a dense fog often not so far. All landmarks, roadways, and trails are obscured in a few minutes, and people per- ish in such storms through losing their way and being overcome by the cold, the wind, and the driving snow. Once fallen, a mantle of snow produces the most decided change in the appearance of the earth, excepting the change from night to day, of which we have knowledge. The earth is naturally a light-absorber. It drinks in sun- light and reflects just as little as possible, so that its general appearance is comparatively dark, with sheets of water showing here and there as spots of white. "When snow covers the ground the appearance is reversed, and such objects as trees and bare rocks appear merely as spots and patches of dark upon the white. The inten- sity of this white is common knowledge. It is a bluish- white and much lighter than the clouds casting it forth. This is largely for a reason 106 NATURE FOR ITS OWN SAKE already given. That is, to repeat it, looking up we see the shadows of countless cloud-par- ticles ; looking down we see light reflected from countless snow-surfaces. But the intensity of the white is not wholly explained by the difference between reflected and shadowed light. There is another reason for its whiteness, and perhaps it is not uninter- esting to know that if the new, fine snow is ex- amined under a magnifying glass each separate flake will be found to disperse as well as to reflect light, and everyone of them will show prismatic edges casting the rainbow colors. These colors are the component parts of light light disintegrated, in fact. The tiny prisms scatter the light into colors, but the mass of them taken together reunite the colors into light. It has long been known in painting that small stipplings of red, yellow, and blue, placed close together, will throw out more light than a pure white ground. Light recomposed from colors is stronger than light reflected. It is this principle, practically demonstrated by nat- ure, that lends something of peculiar brilliancy to the newly fallen snow. And how brilliant, how dazzling is that newly fallen snow onlj those know who have seen it in very cold conn- KAIN AND SNOW 107 tries, where vapor is a practical impossibility and only the ice- or snow-crystal exists. In such lands the covering of the earth glitters as though thickly sprinkled with diamond dust, and the mist rising from swift-running streams is frozen into hoar-frost that drifts in the air, sparkling in the sharp sun-light. It is flash and gleam from every point of view as though a dozen suns were in the sky and all were flaming brightly. This splendor is greatly modified in the re- gions where the snow is moist and forms in heavy masses, loading the branches of the pine and the spruce, muffling the eaves and chimneys of the houses, and piling up in pyra- mids on the tops of the gate-posts. The bril- liancy is pronounced for only a few hours. Under the sun and its warmth the crystals lose their sharp angles and melt down into ice-par- ticles, the pyramids soon slip from the gate- posts, and the pine, shaking its long branches in the breeze, throws its burden of snow from it. The purity and serenity of the morning follow- ing such a snow-fall, when the sun is up and we are out walking the fields and woods through the still whiteness, are not lost upon us. We all feel the solemn beauty of the scene, the hush Brilliancy of mow. 108 NATURE FOR ITS OWN SAKE of the earth, the dark ranks of trees, the gleam of the cold sky, the glitter of the snow lying so fluffily upon earth and tree and hill and house- top. How calm and pure it seems ! How im- pressive it is, too, under moonlight, with the hills stretching far away in their white, heaving mantle, the frozen woods standing up so darkly along the night horizon, the stars glistening in their violet depths, and over all the great si- lence of the sky ! And what a multitude of sharp angles, harsh forms, and bleak colors are hidden under the muffling of snow ! The ragged mound, the rough cornfield, the tumbled meadow, the bushy foot-hills of the mountains are smoothed out, and evened over, and cast in new forms. Everywhere there are flowing, rounded lines running hither and thither to meet other lines, intertwining and uniting in graceful and rhythmic combinations. In the open fields, where the wind has been at work, the snow may be cast in rolls, like the long swells of a smooth sea ; and when the sun is low these swells show pink light on their crests and blue shadows in their hollows shadows even more delicate and tender in hue than those cast upon water. Above the open fields even the mountain-lines RAIN AND SNOW 109 against the sky are softened by the snow ; and the ragged promontories, smoothed into heav- ing mounds of white, glow with a pinkish hue under the sunlight and at evening turn to cold purple. And how sharp is the contrast where the river runs darkly flashing through banks of snow that come down and meet the water's edge ! It is a picture in black-and-white. The bend and sweep of the lines in the banks are clear- cut and sharp, defining on either side the flow in and out of the most graceful thing in the world running water. There is nothing more rhythmical than the curves made by water, and the flowing river in winter is emphasized and intensified by its white borders. Sometimes it happens that the stream is frozen with clear ice, and then from a high point like a bridge, when the wind is blowing, one may see little rivulets and streams of snow running over the top of the ice, following channels, swirling and eddy- ing almost like the stream itself except that the motion is much faster and more serpentine. Very graceful are these little currents of snow. They may be seen again chasing, whirling, and drifting on the crusted and frozen fields, but not so readily as upon a dark background of flO NATURE FOB ITS OWN SAKE ice. The winding courses they follow and the beautiful forms of snow-drifts into which they finally resolve themselves, are distinct features of the snow-landscape. The early days of March when the snow is beginning to melt, when the rocks on the hill- side heave out of the white, and odd patches of ground show dull gray or brown, are usually considered the dreary days of the year. Most people declare the country "stupid" at this time and house themselves in cities if they can ; but to some nature-lovers it is perhaps the most interesting season of all. The snow on the side- hill still lingers ; but the meadows are bare, the brooks are swollen, the ice is gorged in the river, the valleys are shining with pools of water. The skeleton of nature is pushing through its winter mantle at every point ; but if we look at it with appreciative eyes we shall find the hills and the rocks and the bare trees beautiful as outlines merely beautiful in their rugged, broken angles and their traceries of line against the snow or sky. Besides, there is some little color noticeable all through the winter in the red stems of the maples and the birch, in the ruddy glow of the swamp bushes. This color begins to heighten in March and BAIN AND SNOW 111 with it comes the sense or feeling of stirring life. It is in the very air. Nature is turning as though anxious to rouse from slumber. The evidence of life is not great, but we feel under stillness, coldness, and bareness a potential power. The great oaks and chestnuts that stand high up on the mountain, their trunks showing against snow - banks, their branches against the sky, will soon be turning green, and the meadows and swales of the valley will glow with new life and color. Perhaps just at this time, when nature has not yet started out of winter, there comes a late snow-storm which turns to rain, covering the limbs of the trees with ice and putting a crystal coating upon the earth. Then what a spectacle we see the next morning, with all the world glit- tering like spun glass under the rays of the sun ! It is a brilliant sight, and at times a most aston- ishing one in color. For, if we can get the ice- bound trees between us and the sun they will take on any color that the sun or sky may show. Occasionally, with a red sunset, a whole grove of trees will look to be on fire, and under a yellow sunset the same grove of trees will appear of the most brilliant topaz hue. It is not unlike a similar effect seen in falling hail. 112 NATUBE FOB ITS OWN SAKE The awa- kening of nature. The icy landscape is not a sight of any long duration. The sun soon melts the ice, the trees rock in the wind, and the glassy covering slips and rattles upon the frozen ground. When once nature begins to move, it is not easy for cold winds and blustering sleet to stop it. The grass starts under the snow, the early plants begin to stir, the stems and buds grow redder ; and when the last patch of dirty white in the deep gulch among the bowlders is slipping and melting away, the trees above it are perhaps al- ready showing a fuzzy, muffled look, the moss on the bowlders has shot its pale, pin-like points of green upward toward the sun, and the grass grows in thick tufts where the brook winds through the meadow. CHAPTER VI THE OPEN SEA ONE'S first impression of the open sea, gained from a steamer's deck, is usually not too happy. The mind is distracted or it is dull, even if the body be not racked, and a sorry conclusion about the sea is a common result. It is a dreary waste of waters. The horizon rim makes a perfect circle about one, the sky is a great arch overhead, and there is nothing to be seen but an occasional school of porpoises or the misty form of some sailing craft straining along the sky-line. The nouveau thinks the whole affair monoto- nous and, indeed, at first glance variety does seem lacking. Yet in reality there is not an hour when the wind does not shift the form of the waves, not an hour when the light and color of the water are not changing, not an hour from dawn to dawn when the uneasy, faceted surface is not throwing back reflections of the sky in a thousand variegated hues. The sea and the sky are always changing. What appears at first a 113 Firtt im pretsi&n! changes. 114 NATURE FOR ITS OWN SAKE monotony is, in fact, an unending diversity. Time was doubtless in the infancy of the earth when the beds of the oceans were filled with pestilent gases and vapors, and time may be in the earth's old age when the seas will be great frozen depths of ice ; but to-day they are in their prime, in the heyday of their glory, strong in mass and movement, overwhelming in extent and power, splendid in color and light. Water at rest, like the air, would seem at first blush to be quite formless. It is the flat, even- filling of a hollow. Its positive forms are shown only when it is agitated by wind, or pushed in tides and currents, or seeking its level in lower places. There are currents in the sea, but they are hardly recognizable in the open water except by their color. Their forms are not definitely marked not even that of the Gulf Stream though they have certain movements, widths, and lengths, that are well known to the navigator. These currents flowing through the main body of the ocean have always called up an analogy or a likeness to human physiology. For they seem like sea arteries in their move- ments ; and the tides rising and falling liken human lungs respiring. We are, through such resemblances, often led in a romantic way to THE OPEN SEA imagine vain things about the sea; and more than once writers have pictured it as a living body a wrinkled monster writhing in a cramped bed from which there is no escape. And the waves as they come up the rocky coast, flinging long arms upward to grapple with the rocks, have been likened to companies and legions of the deep sent to battle against the rocky barriers companies utterly inexhaust- ible and gaining vantage ground always by wearing out their opponent. There is strife between land and sea, to be sure, but it is the warfare of unthinking elements and there is no enmity about it or in it. Each side is obeying the law of its nature without knowing why or wherefore. It is continuous strife, too. For the so-called legions of the sea are always marching. The "flat sea" is a misnomer. There is no such thing. At times the surface is unruffled, light and color are thrown back from it as from a burnished shield, but the shield is never motionless. Even in the tropics, where the surface may be unbroken for days at a time, there is always the great, heaving "swell" underneath. The restlessness of the sea is un- ceasing. When the wind is rising over an unbroken 116 NATURE FOB ITS OWN SAKE sea-surface it makes itself apparent at first in little catches or quivers on the water. The wind itself comes in fitful puffs and squalls, and it is these little inequalities of wind-pressure that make possible the breaking of the surface at the start. As the wind increases in force the surface is covered with small, facet-like waves that flash light and color with great brilliancy. With a stronger wind we have what is called a " chop sea," in which waves scurry hither and thither, driven by local gusts, crossing and breaking upon each other in small dashes of foam. If the wind is long continued from one direction the general drift of the waves and the water will be toward the opposite point of the compass. The harder and stronger the blowing of the wind, the more uniform the travel of the waves, though they are always more or less ruffled on their surfaces by eddies and contrary gusts, and occasionally a wave set in a lateral direction breaks in upon the line and churns up a great yeast of foam. With a stiff wind the sea shows us waves crested with foam and commonly referred to as " white-caps." These caps are produced by the crest being driven faster with the wind than the body of the wave, thus losing its support ; or THE OPEN SEA 117 by the crest being thrown up in the air with the upward push of the wave. The wedge- shaped cap thus dashed upward or forward breaks into spray, is filled with countless air- bubbles, and shows bluish- or greenish-white to the eye. In heavy winds this " white-cap " is apparent in every direction, but it does not break so regularly or so smoothly as in a common gale. Storm waves are usually marked by flawed and broken surfaces and their crests are ragged and torn, often being wrenched away by gusts of wind and driven across the ocean in the form of flying spray. But despite its irregularity of ! storm surface, one is never deceived about the bulk and weight of a storm wave. Its rise and heave are indicative of its power. The lift of the wave seems one long, straining effort at pushing up the gable-shaped crest. It heaves and heaves until at last, having pushed the top to an un- sustainable height, it suddenly lets go as though exhausted and the crest pitches forward in foam. In long-continued storms these same waves are beaten into white, bubbling, froth-hung surfaces, foam is festooned in wreaths from every crest, and water dust rolls into every hollow ; the air is full of flying spray, the clouds are obliterated, 118 NATURE FOR ITS OWN SAKE and sky and sea seem to melt and mingle into one. But this is the hurricane storm that lit- erally beats the sea into yeast and blurs both form and color. It is not frequently seen, and has too much chaos about it to be more than awe-inspiring by its power. It is little more enjoyable than the night-scene at sea, when rain and wind are howling through the rigging, and the white-caps gleam dull and ghost-like beside the black hulk of the vessel. Nature is some- times too violent for either love or admira- tion. The height of storm waves is more moderate than one would suppose. In fresh-water lakes they rise to a greater relative pitch than on the sea, because fresh water is lighter than salt water. The waves on Lake Superior, for in- stance, are higher in proportion to wind and water-depth than on the Mediterranean ; but on neither is there any mountainous altitude at- tained. The heavy waves of the Mediterranean average only from thirteen to eighteen feet in the perpendicular ; and on the North Atlantic, one of the most tempestuous of all seas, they are only from nineteen to forty-three feet the latter height being the greatest ever known there. This is certainly high enough, but hardly THE OPEN SEA 119 the " mountain high " that we hear about so often from the returned tourist. It is not even hill high. It has been asserted that off the Cape of Good Hope waves one hundred and eight feet in height have been seen, but one may venture to doubt the assertion. The Cape of Good Hope region has always furnished the marvellous in sea-tales, but this one is some- thing too wonderful for belief. The breadth through or thickness of a wave is usually determined by its height considered in relation to its class or kind. On the open sea, where the friction of the sea-bottom is eliminated, the longer waves are often several hundred feet through from hollow to hollow. The long heaving swell of the tropical seas which moves under the ship, lifts it, and then passes on across the distance, its glassy sur- face unbroken by any dash of wave or spray, is probably the thickest of all ocean waves. The estimate has been made that it is some- times from five to six hundred feet in its largest dimension. But this long swell be- longs only to the region of the trade winds, where the push of the wind against the wave is regular and continuous. In localities of Gross-winds and local storm-centres such waves NATURE FOB ITS OWN SAKE and such thicknesses are infrequent, if, indeed, not impossible. The lines of a wave made by light-and-shade and the variation of color are somewhat de- pendent upon wave motion. The swell of the Southern seas has about the same lines as the smaller rolls of a Dakota prairie. The horizontal ridge and its corresponding valley are distinctly marked, light-and-shade and color play all along them, and the heavens above are rolled and unrolled from them in long, flashing reflections. As soon as the sur- face is broken by wind the lines are blurred, and the reflection is lost in local hue, though each little wave continues to throw off from itself the tiny reflection of light and color, like a portion of a broken mirror. The general form and heave of the wave are not lost ; its surface only is changed. The waves on the North Atlantic are quite different from this tropical undulation. They are shorter, sharper, more ragged in surface, and they have a cross- blow tumble and toss about them that some- times defy the line and make only flashing light and color possible. In heavy and steady winds they heap up in enormous ridges, follow- ing each other, file upon file, like other waves', THE OPEN SEA 121 but their surfaces are always irregular, owing to flaws in the wind. In fact, the only line on the North Atlantic that has any stability about it is the horizon-line the darkest line usually on the face of the waters. Even that is not too strong, owing to the presence of vaporous at- mosphere. It is only on cold, clear days that it is sharply defined. Wave motion is more of an appearance than a reality, though there is always some move- ment forward in each wave, and a general drift of the water in the direction of the blowing wind. That which has real movement about it is the undulation. This movement of the undulation is very apparent in the shaking of a carpet on the lawn or the bend and roll of standing grain over which the wind moves swiftly. Neither the carpet nor the grain moves forward, but the undulation certainly does. And it often moves at a great rate of speed say fifty miles an hour out-stripping sometimes the winds that set it in motion, just as a heavy log in a river current when once started will move faster than the cur- rent itself. One has but to watch the move- ment of floating objects on the waves to be convinced that the water itself moves but NATURE FOB ITS OWN SAKE slowly. A chip rises and pitches forward on a crest, but it is drawn back almost an equal dis- tance into the succeeding hollow. Eventually it is carried many miles, to be tossed perhaps upon some island shore ; but it makes a very slow passage. The undulation is generally supposed to be only a surface affair a disturbance like the ringed waves that ride shoreward from a stone cast in a pond. And so it may be ; but the depth at which the movement is felt is often very great. In the bays and harbors along shore a wave four feet in height can be seen swaying and tossing the sea-weed many feet below the surface, and in the Mediterranean, where the water is very clear, the bottom of a swell has been seen rush- ing through rock passages twenty-five fathoms down. There is little doubt that the heaviest waves can be felt a hundred fathoms below the surface. The local color of sea water is determined by its density, its depth, the ground underneath it, or foreign matter held in it. Salt water is denser and generally bluer than fresh water, and the regions of intense salinity are generally the deepest hued of all. The Mediterranean, the Red Sea, the Caribbean are at times violet- THE OPEN SEA 123 blue, while the waters near the poles, in which melted snow and ice are ingredients, appear greenish-hued. The temperature of water also has some effect upon the coloring, for certainly the warmest waters are the darkest. And, too, deep waters appear much bluer than shallow ones. The bays and harbors and coast waters generally look light-hued, possibly because of the land waters brought down and mingled with the sea, and also because of their reflecting bottoms ; but chiefly because of their compara- tive shallowness. The open sea on an average is about two miles deep, and in spots it is probably five or six miles ; but this depth, which should, and usually does, give great body of coloring, is sometimes offset by remarkable clearness in the water. Trans- parency is, of course, dependent upon the mass of particles held in the water, and in this there is great inequality in the different sea areas. It is said that the bottom can be seen in the polar seas at so great a distance as seventy fathoms down. How the bottom at that depth may effect the coloring I am not able to say, but in shallow bays and harbors there is no question about the sea floor changing the coloring of the water. It is well known that certain bays with 124 NATURE FOB ITS OWN SAKE red mud bottoms have reddish waters and others with sandy bottoms have yellow waters. Black streaks in the water are often indicative of hidden rocks or dark masses of seaweed, and a sunken mud-bank will occasionally produce a silver-gray stripe for miles across an inlet. But however the bottom may change the local color in shallow waters, it has little or no effect upon the great seas. Their coloring is produced largely by particles of salt and other substances held in the water. The dust and moisture par- i tides floating in the atmosphere are productive of the blue sky, and if we regard the waters of the sea as colored by similar phenomena, we shall not go far astray, though the analogy may not be quite exact in every way. It is doubtless the salt-particles in sea- water having the power of reflecting blue that make the Mediterranean such a dark ultramarine ; and the rock -par- ticles carried down from the Alps by the Ehone make the water of that stream assume a beauti- ful green-blue tone even when the reflecting blue sky is shut out by clouds. Again, the ef- fect of the Blue Grotto, near Capri, is produced by light shining through the water from beneath and striking particles that apparently turn to blue and produce that tone throughout the cave. THE OPEN SEA 126 Certain particles or floating matters animal, vegetable or mineral, I know not which make I Gulf color. the Gulf Stream an indigo current travelling tngt ' through a lighter body of water, make the Gulf of Lyons a darker blue than the sky above it, and make the Gulf of Gascony a dark green. Refer- ence is now being made solely to local color and not to sky reflection of any kind. For if these waters be taken up in white jars the difference in hue will still be well marked. It is inherent in the water and is a part of it, just as the Yel- low Sea is yellow because of vegetable deposits, and the North Sea off Scheveningen is yellow- brown from carrying in it a solution of earth matter. We can see the same local color effects in fresh-water lakes, as, for instance, in the Yel- lowstone region, where mineral deposits may produce red, green, blue, brown, or almost any colored water ; and the warmer the water the more astonishing the coloring. Aside from this coloring matter, the hue of ocean water is sometimes changed in spots by the presence of great swarms of animalculae, or patches of algae, or "sea-sawdust." The spots and areas of white, red, and brown that look so picturesque upon the surfaces of the Indian and Pacific Oceans, and occasionally 126 NATURE FOE ITS OWN SAKE in the Arctic seas, are accounted for in this way. But these are mere patches of surface-color in isolated regions. The general hue of sea-water is controlled largely by the matter of depth. It requires a great mass of air-particles to pro- duce a blue sky, and it takes a great depth of sea- water and much reflection from salt-particles to produce " the deep blue sea." It is safe to say, then, that the greatest depths are the bluest, that the shallower depths incline to green, and the shallowest waters the waters near shore are the ones that show the browns, reds, or yel- lows. All of these colors are peculiarly beautiful for a reason we seldom take into consideration namely, their transparency. The ordinary colors of nature as shown in grass, flowers, trees, fields, mountains, are opaque. The hue is on the surface, and is only a veneer an outer coating so far as our eyes are concerned. But the sky in its interminable height and the sea in its vast depth are blue by virtue of super- imposed layers or strata of transparent sub- stances. It is not until stratum has been heaped upon stratum in countless numbers that the color begins to show. We see into them as into open space, the quality of the color breaks THE OPEN SEA 127 upon us slowly, and its greatest tenderness is revealed to us only in its profoundest depths. But beautiful as the local hues of sea- water may be, they are nearly equalled by the colors that may be reflected from the surface. Light will penetrate water as it does glass, coloring it as the rays are broken and reflected by the floating particles ; but like glass, water will also reflect color and light from its face with wonderful clearness. In this respect the ocean is not very different from the mountain lake and the road- side pool. The whole dark sweep of the sea brightens under the dawn and flames under the twilight, and every heaving wave is a convex mirror. Reflection is, however, conspicuously apparent only when the surface is smooth. On the glassy Southern swell it is possible to see the white clouds pass by one as in a panorama, the blue sky shaken out in great undulations, and the round, flashing sun riding the smooth waves like an enormous diamond. Whatever the sky contains will appear in the reflection. The sunsets off the Isle of Shoals in the calm even- ings of August are quite as gorgeous on the water as in the heavens. Every little wave that ripples in is like liquid fire, or at times like the rounded surface of an iridescent vase. Even a 128 NATURE FOR ITS OWN SAKE more gorgeous coloring, running at times through almost every note of the scale, is seen at twilight in the short, lapping waves off the western coast of Scotland. The Mediterranean about Spain and Algiers, the Adriatic at Ven- ice, the seas of the Southern Pacific are won- derful in their color harmony, but in inten- sity of hue they seem less positive than at the North. Dawns and sunsets far out on the open water are seldom so varied or so gorgeous as near or over the land. The air at sea is less charged with dust than moisture, and ruddiness of col- oring is not perhaps so possible of attainment. Occasionally, however, in the summer months there is a sharp display of colors as the sun comes up or goes down over the water-line. I find in one of my note-books the following memoranda : " July 11. Gulf Stream : The sunset colors are deep- orange, pink, and yellow, with greenish hues in the sky spaces ; a fog-bank just beneath the sun is lilac-hued, turning to purple. The smooth water resplendent like a gold floor; far up the zenith the wispy cirrus clouds are shining like snow against the blue." " July 14. Bright yellow sunset, light from the blue not very clear, yellow sun-shafts. The sun is barred with dark purple clouds. In the east, north, and south pale tints of lilac, pearl-gray, and pink." THE OPEN SEA 129 If the ocean surface is very smooth, one may occasionally see at sunset the double sun that is, the sun's reflection as a round, fiery light in the water, just below the sun itself on the western horizon. If the water is ruffled, we have, instead of the round light, a long flicker- ing pathway across the waves. It takes the coloring of the sun, and is in fact only its broken reflection. When the sun is high up in the heavens and is beating down diagonally on slightly ruffled water, this pathway is less marked in color, but broader and more brilliant in light. At times when looking at it with half -closed eyes one can see, or at least imagine, the sun's rays striking the water like shot and splashing up light by the impact. The long trail of moonlight on the ocean which we all love to watch, and think about romantically as the same moonlight shining on the river at home, is a similar appearance, only the light is feebler and more mellow, and the apparent splash of the falling rays striking the water is not so noticeable. Cloud-shadows are as conspicuous on ruffled water as upon the land, and the number of color- changes on the sea surface caused by clouds is little short of astonishing. Sometimes these Sunlight