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автор Percival Lowell

MARS AND ITS CANALS

Mars’ Hill

MARS

AND ITS CANALS

BY

PERCIVAL LOWELL

DIRECTOR OF THE OBSERVATORY AT FLAGSTAFF, ARIZONA; NON-RESIDENT

PROFESSOR OF ASTRONOMY AT THE MASSACHUSETTS INSTITUTE OF

TECHNOLOGY; FELLOW OF THE AMERICAN ACADEMY OF ARTS AND

SCIENCES; MEMBRE DE LA SOCIÉTÉ ASTRONOMIQUE DE FRANCE;

MEMBER OF THE ASTRONOMICAL AND ASTROPHYSICAL SOCIETY

OF AMERICA; MITGLIED DER ASTRONOMISCHEN GESELLSCHAFT;

MEMBRE DE LA SOCIÉTÉ BELGE D’ASTRONOMIE; HONORARY

MEMBER OF THE SOCIEDAD ASTRONOMICA DE MEXICO;

JANSSEN MEDALIST OF THE SOCIÉTÉ ASTRONOMIQUE

DE FRANCE, 1904, FOR RESEARCHES ON MARS;

ETC., ETC.

ILLUSTRATED

New York

THE MACMILLAN COMPANY

LONDON: MACMILLAN & CO., Ltd.

1906

All rights reserved

Copyright, 1906,

By THE MACMILLAN COMPANY.

Set up and electrotyped. Published December, 1906.

Norwood Press

J. S. Cushing & Co.—Berwick & Smith Co.

Norwood, Mass., U.S.A.

To

G. V. SCHIAPARELLI

THE COLUMBUS OF A NEW PLANETARY WORLD

THIS INVESTIGATION UPON IT

IS APPRECIATIVELY

INSCRIBED

PREFACE

Eleven years have elapsed since the writer’s first work on Mars was published in which were recorded the facts gleaned in his research up to that time and in which was set forth a theory of their explanation. Continued work in the interval has confirmed the conclusions there stated; sometimes in quite unexpected ways. Five times during that period Mars has approached the earth within suitable scanning distance and been subjected to careful and prolonged scrutiny. Familiarity with the subject, improved telescopic means, and long-continued training have all combined to increased efficiency in the procuring of data and to results which have been proportionate. A mass of new material has thus been collected,—some of it along old lines, some of it in lines that are themselves new,—and both have led to the same outcome. In addition to thus pushing inquiry into advanced portions of the subject, study has been spent in investigation of the reality of the phenomena upon which so much is based, and in testing every theory which has been suggested to account for them. From diplopia to optical interference, each of these has been examined and found incompatible with the observations. The phenomena are all they have been stated to be, and more. Each step forward in observation has confirmed the genuineness of those that went before.

To set forth science in a popular, that is, in a generally understandable, form is as obligatory as to present it in a more technical manner. If men are to benefit by it, it must be expressed to their comprehension. To do this should be feasible for him who is master of his subject and is both the best test of, and the best training to, that post. Especially vital is it that the exposition should be done at first hand; for to describe what a man has himself discovered comes as near as possible to making a reader the co-discoverer of it. Not only are thus escaped the mistaken glosses of second-hand knowledge, but an aroma of actuality, which cannot be filtered through another mind without sensible evaporation, clings to the account of the pioneer. Nor is it so hard to make any well-grasped matter comprehensible to a man of good general intelligence as is commonly supposed. The whole object of science is to synthesize, and so simplify; and did we but know the uttermost of a subject we could make it singularly clear. Meanwhile technical phraseology, useful as shorthand to the cult, becomes meaningless jargon to the uninitiate and is paraded most by the least profound. But worse still for their employ symbols tend to fictitious understanding. Formulæ are the anæsthetics of thought, not its stimulants; and to make any one think is far better worth while than cramming him with ill-considered, and therefore indigestible, learning.

Even to the technical student, a popular book, if well done, may yield most valuable results. For nothing in any branch of science is so little known as its articulation,—how the skeleton of it is put together, and what may be the mode of attachment of its muscles.

CONTENTS

PAGE

  Preface vii   PART I  

NATURAL FEATURES

 

CHAPTER

 

I.

On Exploration 3  

II.

A Departure-point 12  

III.

A Bird’s-eye View of Past Martian Discovery 20  

IV.

The Polar Caps 32  

V.

Behavior of the Polar Caps 41  

VI.

Martian Polar Expeditions 54  

VII.

White Spots 73  

VIII.

Climate and Weather 82  

IX.

Mountains and Cloud 96  

X.

The Blue-green Areas 108  

XI.

Vegetation 119  

XII.

Terraqueousness and Terrestriality 128  

XIII.

The Reddish-ochre Tracts 148  

XIV.

Summary 159     PART II  

NON-NATURAL FEATURES

 

XV.

The Canals 173  

XVI.

Their System 184  

XVII.

Gemination of the Canals 192  

I.

The Diplopic Theory 196  

II.

The Interference Theory 201  

III.

The Illusion Theory 202    

XVIII.

The Double Canals 204  

XIX.

Canals in the Dark Regions 243  

XX.

Oases 249  

XXI.

Carets on the Borders of the Great Diaphragm 265  

XXII.

The Canals Photographed 271     PART III  

THE CANALS IN ACTION

 

XXIII.

Canals: Kinematic 281  

XXIV.

Canal Development Individually Instanced 304  

XXV.

Hibernation of the Canals 313  

XXVI.

Arctic Canals and Polar Rifts 325  

XXVII.

Oases: Kinematic 330     PART IV  

EXPLANATION

 

XXVIII.

Constitution of the Canals and Oases 337  

XXIX.

Life 348  

XXX.

Evidence 360  

XXXI.

The Husbanding of Water 366  

XXXII.

Conclusion 376    

INDEX

385

LIST OF ILLUSTRATIONS

PLATES

Mars’ Hill Frontispiece

PAGE

The Hermitage 8 The San Francisco Peaks 18 Martian Maps by

:

I.

Beer and Maedler. 1840 26

II.

Kaiser. 1864 26

III.

Flammarion (Résumé). 1876 27

IV.

Green. 1877 27

V.

Schiaparelli. 1877 28

VI.

Schiaparelli. 1879 28

VII.

Schiaparelli. 1881 29

VIII.

Schiaparelli. 1884 29

IX.

Lowell. 1894 30

X.

Lowell. 1896 30

XI.

Lowell. 1901 31

XII.

Lowell. 1905 31 South Polar Cap. 1905 42 North Polar Cap. 1905 44 Mare Erythraeum, Martian date, December 30 120 Mare Erythraeum, Martian date, January 16 122 Mare Erythraeum, Martian date, February 1 124 Mare Erythraeum, Martian date, February 21 126 Mars, on Mercator’s Projection 384

CUTS APPEARING IN TEXT

South Polar Cap in winter 56 Hellas in winter 59 White south of Nectar and Solis Lacus 59 Northern Cap hooded with vapor 64 Northern Cap unmasked 65 Deposition of frost 70 First northern snow 72 White in Elysium 75 White in the Pons Hectoris 78 Projection on terminator 101 Lines in dark area 117 Map of North America at the close of Archæan time 132 North America at opening of Upper Silurian period 134 Map of North America after the Appalachian revolution 135 North America in the Cretaceous period 136 North America, showing the parts under water in the Tertiary era 137 Earth’s Desert Areas, Western Hemisphere 156 Earth’s Desert Areas, Eastern Hemisphere 157 Showing the Eumenides-Orcus 183 Martian doubles 206 Martian doubles 207 Mouths of Euphrates and Phison. June, 1903 219 Peculiar development of the Ganges 228 Djihoun, the narrowest double 229 The Sabaeus Sinus, embouchure for the double Hiddekel and Gihon 232 The Propontis, 1905 247 Fons Immortalis, June 19 254 Utopia Regio. 1903 256 Ascraeus Lucus and Gigas. March 2, 1903 258 Peculiar association of the Luci Ismenii with double canals 260 Lucus Ismenius. March, 1903 262 Showing seasonal change. I 285 Showing seasonal change. II 285 Mean Canal Cartouches 298 Showing development of the Brontes: I. February 25 306 II. March 30 307 III. April 3 307 IV. May 4 308 V. May 7 308 VI. July 18 309 Cartouches of the Brontes 311 Amenthes alone in February 319 Amenthes feebler and still alone in March 319 Appearance of Thoth with Triton and curved Nepenthes. Amenthes vanished, April 20 320 Advent of the Lucus Moeris. May 29 321 Amenthes with Thoth-Nepenthes. July 322 Cartouches of Amenthes, Thoth, and their combination 323 Phenology Curves—Earth 342 Phenology Curves—Mars 343

PART I
 
NATURAL FEATURES

MARS AND ITS CANALS

CHAPTER I
 
ON EXPLORATION

From time immemorial travel and discovery have called with strange insistence to him who, wondering on the world, felt adventure in his veins. The leaving familiar sights and faces to push forth into the unknown has with magnetic force drawn the bold to great endeavor and fired the thought of those who stayed at home. Spur to enterprise since man first was, this spirit has urged him over the habitable globe. Linked in part to mere matter of support it led the more daring of the Aryans to quit the shade of their beech trees, reposeful as that umbrage may have been, and wander into Central Asia, so to perplex philologists into believing them to have originated there; it lured Columbus across the waste of waters and caused his son to have carved upon his tomb that ringing couplet of which the simple grandeur still stirs the blood:—

Á Castilla y á Leon

Nuevo mondo dió Colon;

(To Castile and Leon beyond the wave

Another world Columbus gave;)

it drove the early voyagers into the heart of the vast wilderness, there to endure all hardship so that they might come where their kind had never stood before; and now it points man to the pole.

Something of the selfsame spirit finds a farther field today outside the confines of our traversable earth. Science which has caused the world to shrink and dwindle has been no less busy bringing near what in the past seemed inaccessibly remote. Beyond our earth man’s penetration has found it possible to pierce, and in its widening circle of research has latterly been made aware of another world of strange enticement across the depths of space. Planetary distances, not mundane ones, are here concerned, and the globe to be explored, though akin to, is yet very different from, our own. This other world is the planet Mars. Sundered from us by the ocean of ether, a fellow-member of our own community of matter there makes its circuit of the sun upon whose face features show which stamp it as cognate to that on which we live. In spite of the millions of miles of intervening matterless void, upon it markings can be made out that distantly resemble our earth’s topography and grow increasingly suggestive as vision shapes them better; and yet among the seemingly familiar reveal aspects which are completely strange. But more than this: over the face of it sweep changes that show it to be not a dead but a living world, like ours in this, and luring curiosity by details unknown here to further exploration of its unfamiliar ground.

To observe Mars is to embark upon this enterprise; not in body but in mind. Though parted by a gulf more impassable than any sea, the telescope lets us traverse what otherwise had been barred and lands us at last above the shores we went forth to seek. Real the journey is, though incorporeal in kind. Since the seeing strange sights is the essence of all far wanderings, it is as truly travel so the eye arrive as if the body kept it company. Indeed, sight is our only far viatic sense. Touch and taste both hang on contact, smell stands indebted to the near and even hearing waits on ponderable matter where sound soon dissipates away; only sight soars untrammeled of the grosser adjunct of the flesh to penetrate what were otherwise unfathomable space.

What the voyager thus finds himself envisaging shares by that very fact in the expansion of the sense that brought him there. No longer tied by means of transport to seas his sails may compass or lands his feet may tread, the traveler reaches a goal removed in kind from his own habitat. He proves to have adventured, not into unknown parts of a known world, but into one new to him in its entirety. In extent alone he surveys what dwarfs the explorer’s conquests on Earth. But size is the least of the surprises there in store for him. What confronts his gaze finds commonly no counterpart on Earth. His previous knowledge stands him in scant stead. For he faces what is so removed from every day experience that analogy no longer offers itself with safety as a guide. He must build up new conceptions from fresh data and slowly proceed to deduce the meaning they may contain. Science alone can help him to interpretation of what he finds, and above all must he wean himself from human prejudice and earthbound limitation. For he deals here with ultramundane things. With just enough of cosmogony in common to make decipherment not despairable this world is yet so different from the one he personally knows as to whet curiosity at every turn. He is permitted to perceive what piques inquiry and by patient adding of point to point promises at last a rational result.

Like mundane exploration, it is arduous too; ad astra per aspera is here literally true. For it is a journey not devoid of hardship and discomfort by the way. Its starting-point preludes as much. To get conditions proper for his work the explorer must forego the haunts of men and even those terrestrial spots found by them most habitable. Astronomy now demands bodily abstraction of its devotee. Its deities are gods that veil themselves amid man-crowded marts and impose withdrawal and seclusion for the prosecution of their cult as much as any worshiped for other reason in more primeval times. To see into the beyond requires purity; in the medium now as formerly in the man. As little air as may be and that only of the best is obligatory to his enterprise, and the securing it makes him perforce a hermit from his kind. He must abandon cities and forego plains. Only in places raised above and aloof from men can he profitably pursue his search, places where nature never meant him to dwell and admonishes him of the fact by sundry hints of a more or less distressing character. To stand a mile and a half nearer the stars is not to stand immune.

Thus it comes about that today besides its temples erected in cities, monasteries in the wilds are being dedicated to astronomy as in the past to faith; monasteries made to commune with its spirit, as temples are to communicate the letter of its law. Pioneers in such profession, those already in existence are but the precursors of many yet to come as science shall more and more recognize their need. Advance in knowledge demands what they alone can give. Primitive, too, they must be as befits the still austere sincerity of a cult, in which the simplest structures are found to be the best.

Still the very wildness of the life their devotee is forced to lead has in it a certain fittingness for his post in its primeval detachment from the too earthbound, in concept as in circumstance. Withdrawn from contact with his kind, he is by that much raised above human prejudice and limitation. To sally forth into the untrod wilderness in the cold and dark of a winter’s small hours of the morning, with the snow feet deep upon the ground and the frosty stars for mute companionship, is almost to forget one’s self a man for the solemn awe of one’s surroundings. Fitting portal to communion with another world, it is through such avenue one enters on his quest where the common and familiar no longer jostle the unknown and the strange. Nor is the stillness of the stars invaded when some long unearthly howl, like the wail of a lost soul, breaks the slumber of the mesa forest, marking the prowling presence of a stray coyote. Gone as it came, it dies in the distance on the air that gave it birth; and the gloom of the pines swallows up one’s vain peering after something palpable, their tops alone decipherable in dark silhouette against the sky. From amid surroundings that for their height and their intenancy fringe the absolute silence of space the observer must set forth who purposes to cross it to another planetary world.

The Hermitage

But the isolation of his journey is not always so forbidding. His coming back is no less girt with grandeur of a different though equally detached a kind. Even before the stars begin to dim in warning to him to return, a faint suffusion as of half-suspected light creeps into the border of the eastern sky. Against it, along the far pine-clad horizon, mesa after mesa in shaggy lines of sentineling earth, stands forth dark marshaled in the gloom, informed with prescience of what is soon to come. Imperceptibly the pallor grows, blanching the face of night and one by one extinguishing the stars. Slowly then it takes on color, tingeing ever so faintly to a flush that swells and deepens as the minutes pass. One had said the sky lay dreaming of the sun in pale imagery at first that gathers force and feeling till the dreamer turns thus rosy red in slumbering supposition of reality. Then the blush dies out. The crimson fades to pink, the pink to ashes. The stars have disappeared and yet it is not day. It is the supreme moment of the dawn, the hush with which the Earth awaits its full awakening. For now again the color gathers in the east, not with the impalpable suffusion it had before but nearer and more vivid. No longer reflectively remote, rays imminent of the sun strike the upper air, the most adventurously refrangible turning the underside of a few stray clouds into flame-hued bars of glowing metal. They burn thus in the silent east first red, then orange, and then gold, each spectral tint in prismatic revelation coming to join the next till in a sudden blinding burst of splendor the solar disk tops the horizon’s rim.

Not less impressive is the journey when the afternoon watch has replaced the morning vigil by the drawing of the planet nearer to the sun. Lost in the brilliance of the dazzling sky, the planet lies hid from the senses’ search. The quest were hopeless did not the mind guide the telescope to its goal. To theory alone is it visible still, and so to its predicted place the observer sets his circles, and punctual to the prophecy the planet swings into the field of view. One must be dulled by long routine to such mastery of mind not to have the act itself clothe with a sense of charmed withdrawal the object of his quest.

So much and more there are of traveler’s glimpses by the way, compensation that offsets the frequent discomfort, and even balking of his purpose by inopportune cloud. For the best of places is not perfect, and a storm will sometimes rob him of a region he wished to see. He must learn to wait upon his opportunities and then no less to wait for mankind’s acceptance of his results; for in common with most explorers he will encounter on his return that final penalty of penetration, the certainty at first of being disbelieved.

In such respect he will be even worse off than were the other world discoverers of the fifteenth and sixteenth centuries. For they at least could offer material proof of things that they had seen. Dumb Indians and gold spoke more convincingly than the lips of the great navigators. To astronomy, too, that other world was due. Without a knowledge of the earth’s shape and size got from Francisco of Pisa, Columbus had never adventured himself upon the deep. But more than this, an astronomer it was, in the person of Americus Vespucius, who first discovered the new world, by recognizing it as such; Columbus never dreaming he had lighted upon a world that was new. Nor does it impair one jot or tittle of his glory that he knew it not. Nothing can deprive him of the imperishable fame of launching forth into the void in hope of a beyond, though he found not what he sought but something stranger still.

So, curiously, has it been with the trans-etherian. To Schiaparelli the republic of science owes a new and vast domain. His genius first detected those strange new markings on the Martian disk which have proved the portal to all that has since been seen, and his courage in the face of universal condemnation led to exploration of them. He made there voyage after voyage, much as Columbus did on Earth, with even less of recognition from home. As with Columbus, too, the full import of his great discovery lay hid even to him and only by discoveries since is gradually resulting in recognition of another sentient world.

CHAPTER II
 
A DEPARTURE-POINT

As the character of the travel is distinctive, so the outcome of the voyage is unique. If he choose his departure-point aright, the observer will be vouchsafed an experience without parallel on Earth. To select this setting-out station is the first step in the journey upon which everything depends. For it is essential to visual arrival that a departure-point be taken where definition is at its best. Now, so far as our present knowledge goes, the conditions most conducive to good seeing turn out to lie in one or other of the two great desert belts that girdle the globe. Many of us are unaware of the existence of such belts and yet they are among the most striking features of physical geography. Could we get off our globe and view it from without we should mark two sash-like bands of country, to the poleward side of either tropic, where the surface itself lay patently exposed. Unclothed of verdure themselves they would stand forth doubly clear by contrast. For elsewhere cloud would hide to a greater or less extent the actual configuration of the Earth’s topography to an observer scanning it from space.

One of these sash-like belts of desert runs through southern California, Arizona, New Mexico, the Sahara, Arabia Petræa and the Desert of Gobi; the other traverses Peru, the South African veldt, and Western Australia. They are desert because in them rain is rare; and even clouds seldom form. In a twofold way they conduce to astronomic ends. Absence of rain makes primarily for clear skies and secondarily for steady air; and the one of these conditions is no less vital to sight than the other. Water vapor is a great upsetter of atmospheric equilibrium and commotion in the air the spoiler of definition. Thus from the cloudlessness of their skies man finds in them most chance of uninterrupted communion with the stars, while by suitably choosing his spot he here obtains as well that prime desideratum for planetary work, as near a heavenly equanimity in the air currents over his head as is practically possible.

From the fact that these regions are desert they are less frequented of man, and the observer is thus perforce isolated by the nature of the case, the regions best adapted to mankind being the least suited to astronomic observations. In addition to what nature has thus done in the matter, humanity has further differentiated the two classes of sights by processes of its own contriving. Not only is civilized man actively engaged in defacing such part of the Earth’s surface as he comes in contact with, he is equally busy blotting out his sky. In the latter uncommendable pursuit he has in the last quarter of a century made surprising progress. With a success only too undesirable his habitat has gradually become canopied by a welkin of his own fashioning, which has rendered it largely unfit for the more delicate kinds of astronomic work. Smoke from multiplying factories by rising into the air and forming the nucleus about which cloud collects has joined with electric lighting to help put out the stars. These concomitants of advancing civilization have succeeded above the dreams of the most earth-centred in shutting off sight of the beyond so that today few city-bred children have any conception of the glories of the heavens which made of the Chaldean shepherds astronomers in spite of themselves.

The old world and the new are alike affected by such obliteration. Long ago London took the lead with fogs proverbial wholly due to smoke, fine particles of solid matter in suspension making these points of condensation about which water vapor gathers to form cloud. With the increase of smoke-emitting chimneys over the world other centres of population have followed suit till today Europe and eastern North America vie with each other as to which sky shall be the most obliterate. Even when the obscuration is not patent to the layman it is evident to the meteorologist or astronomer. By a certain dimming of the blue, smoke or dust reveals its presence high up aloft as telltalely as if the thing itself were visible. Some time since the writer had occasion to traverse Germany in summer from Göttingen to Cologne and in so doing was impressed by a cloudiness of the sky he felt sure had not existed when he knew it as a boy. For the change was too startling and extensive to be wholly laid to the score of the brighter remembrances of youth. On reaching Cologne he mentioned his suspicion to Klein, only to find his own inference corroborated; observations made twenty years ago being impracticable today. Two years later in Milan Celoria told the same story, the study of Mars having ceased to be possible there for like cause. Factory smoke and electric lights had combined to veil the planet at about the time Schiaparelli gave up his observations because of failing sight. With a certain poetic fitness the sky had itself been blotted just at the time the master’s eye had dimmed.

America is not behind in this race for sky extinction. In the neighborhood of its great cities and spreading into the country round about the heavens have ceased to be favorable to research. Not till we pass beyond the Missouri do the stars shine out as they shone before the white man came.

Few astronomers even fully appreciate how much this means, so used does man get to slowly changing conditions. It amounts, indeed, between Washington and Arizona to a whole magnitude in the stars which may be seen. At the Naval Observatory of the former sixty-four stars were mapped in a region where with a slightly smaller glass one hundred and seventy-two were charted at Flagstaff.

Besides their immediate use as observing stations these desert belts possess mediate interest on their own account in a branch of the very study their cloudlessness helps to promote, the branch here considered, the study of the planet Mars. They help explain what they permit to be visible. For in the physical history of the Earth’s development they are among the latest phenomena and mark the beginning of that stage of world evolution into which Mars is already well advanced. They are symptomatic of the passing of a terraqueous globe into a purely terrestrial one. Desertism, the state into which every planetary body must eventually come and for which, therefore, it becomes necessary to coin a word, has there made its first appearance upon the Earth. Standing as it does for the approach of age in planetary existence, it may be likened to the first gray hairs in man. Or better still it corresponds to early autumnal frost in the passage of the seasons. For the beginning to age in a planet means not decrepitude in its inhabitants but the very maturing of this its fruit. Evolution of mind in its denizens continues long after desolation in their habitat has set in. Indeed, advance in brain-power seriously develops only when material conditions cease to be bodily propitious and the loss of corporeal facilities renders its acquisition necessary to life.

The resemblance, distant but distinctive, of the climatic conditions necessary on earth for the best scanning of Mars with those which prove to be actually existent on that other world has a bearing on the subject worth considerable attention. It helps directly to an understanding and interpretation of the Martian state of things. Though partial only, the features and traits of our arid zones are sufficiently like what prevails on Mars to make them in some sort exponent of physical conditions and action there. Much that is hard of appreciation in a low, humid land shows itself an everyday possibility in a high and dry one. The terrible necessity of water to all forms of life, animal or vegetal, so that in the simple thought of the aborigines rain is the only god worth great propitiation upon the due observance of which everything depends, brings to one a deeper realization of what is really vital and what but accessory at best. One begins to conceive what must be the controlling principle of a world where water is only with difficulty to be had, and rain unknown.

But in addition to the fundamental importance of water, the relative irrelevancy of some other conditions usually deemed indispensable to organic existence there find illustration too. On the high plateau of northern Arizona and on the still higher volcanic cones that rise from them as a base into now disintegrating peaks, the thin cold air proves no bar to life. To the fauna there air is a very secondary consideration to water, and because the latter is scarce in the lowlands and more abundant higher up, animals ascend after it, making their home at unusual elevations with no discomfort to themselves. Deer range to heights where the barometric pressure is but three fifths that of their generic habitat. Bear do the like, the brown bear of northern American sea-level being here met with two miles above it. Nor is either animal a depauperate form. Man himself contrives to live in comfort and propagate his kind where at first he finds it hard to breathe. Nor are these valiant exceptions; as Merriam has ably shown in his account of the San Francisco peak region for the Smithsonian Institution—a most interesting report, by the way—the other animals are equally adaptive to the zones of more northern latitudes on the American continent, zones paralleled in their flora and fauna by the zones of altitude up this peak. All which shows that paucity of air is nothing like the barrier to life we ordinarily suppose and is not for an instant to be compared with dearth of water. If in a comparatively short time an animal or plant accustomed to thirty inches of barometric pressure can contrive to subsist sensibly unchanged at eighteen, it would be rash to set limits to what time may not do. And this the more for another instructive fact discovered in this region by Merriam: that the existence of a species was determined not by the mean temperature of its habitat but by the maximum temperature during the time of procreation. A short warm season in summer alone decides whether the species shall survive and flourish; that it has afterward to hibernate for six months at a time does not in the least negative the result.

The San Francisco Peaks

That the point of departure should thus prove of twofold importance, speeding the observer on his journey and furnishing him with a vade mecum on arrival, is as curious as opportune. Without such furtherance, to the bodily eye on the one hand and the mind’s eye on the other, the voyage were less conclusive in advent and less satisfactory in attent.

CHAPTER III
 
A BIRD’S-EYE VIEW OF PAST MARTIAN DISCOVERY

With Mars discovery has from the start waited on apparent disk. To this end every optical advance has contributed from the time of Galileo’s opera-glass to the present day. For apparent distance stands determined by the size of the eye. But although it is the telescopic eye that has increased, not the distance that has diminished, the effect has been kin to being carried nearer the planet and so to a scanning of its disk with constantly increasing particularity. Mankind has to all intents and purposes been journeying Marsward through the years. Any historic account of the planet, therefore, becomes a chronicle of seeming bodily approach.

Perhaps no vivider way of making this evident and at the same time no better preface to the present work could be devised than by putting before the eye in orderly succession the maps made of Mars by the leading areographers of their day, since the planet first began to be charted sixty-five years ago. The procedure is as much as possible like standing at the telescope and seeing the phenomena steadily disclose.

Seen thus in order the facts speak for themselves. They show that from first to last no doubt concerning what was seen existed in the minds of those competent to judge by systematic study of the planet at first hand, and furthermore, from their mutual corroboration, that this confidence was well placed. For, far from there being any conflict of authorities in the case, those entitled to an opinion in the matter prove singularly at one.

Beginning with Maedler in 1840 the gallery of such portraitures of the planet comprises those by Kaiser, Green and Schiaparelli, continued since Schiaparelli’s time by the earlier ones of the present writer. To this list has been added one by Flammarion, which though not solely from his own work gives so just a representation of what was known at the date, 1876, as to merit inclusion. The remarkable drawings of Dawes and the excellent ones of Lockyer in 1862-1864 were never combined into maps by the observers, and though the former’s were so synthesized by Proctor in 1867, the result was conformed to what Proctor thought ought to be and so is not really a transcript of the drawings themselves.

Each of the maps presented marked in its day the point areography had reached; and each tells its own story better than any amount of text. They are all made upon Mercator’s projection and omit in consequence the circumpolar regions. The later ones give, too, only so much of the surface as was shown at the opposition they record, for Mars, being tipped now one way, now another, regards the earth differently according to its orbital position. In comparing them, therefore, the equator must be taken for medial line. Mercator’s projection has been the customary one for portraying Mars except for such oppositions as chiefly disclose the arctic pole. And this, too, with a certain poetic fitness. For it comes by right of priority to delineation of a new world; seeing that Mercator was the first to represent in a map the mundane new world in its entirety, by the rather important addition of North America to the southern continent already known, and to give the whole the title America with ‘Ame’ at the top of the map and ‘rica’ at the bottom.

In looking at the maps it is to be remembered that they are what we should call upside down, south standing at the top and north at the bottom. Inverted they show because this is the way the telescopic observer always sees the planet. The disk would seem unnatural to astronomers were it duly righted. Just the same do men in the southern hemisphere look at our own Earth topsy-turvy according to our view, the Sun being to the north of them and the cold to the south. Certain landmarks distinguishable in all the maps may serve for specific introduction. The V-shaped marking on the equator pointing to the north is the Syrtis Major, the first marking ever made out upon the planet and drawn by the great Huyghens in 1659. The isolated oval patch in latitude 26° south is the Solis Lacus, the pupil of the eye of Mars; while the forked bay on the equator, discovered by Dawes, is the Sabaeus Sinus, the dividing tongue of which, the Fastigium Aryn, has been taken for the origin of longitudes on Mars.

Twelve maps go to make the series. They are as follows:—

Maker Date I.

Map of Beer and Maedler

1840

II.

Map of Kaiser

1864

III.

Map of Flammarion (Résumé)

1876

IV.

Map of Green

1877

V.

Map of Schiaparelli

1877

VI.

Map of Schiaparelli

1879

VII.

Map of Schiaparelli

1881

VIII.

Map of Schiaparelli

1884

IX.

Map of Lowell

1894

X.

Map of Lowell

1896

XI.

Map of Lowell

1901

XII.

Map of Lowell

1905

If these maps be carefully compared they will be found quite remarkably confirmatory each of its predecessor. To no one will their inter-resemblance seem more salient than to draughtsmen themselves. For none know better how surprisingly, even when two men have the same thing under their very noses to copy, their two versions will differ. Judgment of position and of relative size is one cause of variation; focusing of the attention on different details another. What slight discrepancies affect the maps are traceable to these two human imperfections. Maps IV and V make a case in point: it was to his new-found canals that Schiaparelli gave heed to the neglect of a due toning of his map; while Green, less keen-eyed but more artistic, missed the delicate canaliform detail to make a speaking portraiture of the whole.

Amid the remarkable continuity of progression here shown, in which each map will be seen to be at once a review and an advance, we may, nevertheless, distinguish three stages in the perception of the phenomena. Thus we may mark:—

I.

A period of recognition of larger markings only;

1840-1877

II.

A period of detection of canals intersecting the bright regions or lands;

1877-1892

III.

A period of detection of canals traversing the ‘seas’ and of oases scattered over the surface;

1892-1905

Each period is here represented by four charts; and each expresses the result of a more minute and intimate acquaintance with the disk than was possible to the one that went before. To realize, however, how accurate each was according to his lights it is only necessary to have the seeing grow steadily better some evening as one observes. He will find himself recapitulating in his own person the course taken by discovery for all those who went before, and in the lapse of an hour live through the observational experience of sixty years; in much the same way that the embryological growth of an individual repeats the development historically of the race.

Two verses of Ovid, which the poet puts into the mouth of Pythagoras, outline with something like prophetic utterance the special discoveries which mark the three periods apart. Ovid makes Pythagoras say of the then world:—

Vidi ego, quod fuerat quondam solidissima tellus

Esse fretum; vidi factas ex aequore terras;

—Ovid, Metamorphoses XV, 262.

(Where once was solid ground I’ve seen a strait;

Lands I’ve seen made from out the sea.)

True as the verses are of Earth, the poet could not have penned them otherwise had he meant to record the course of astronomic detection on Mars. For they sound like a presentiment of the facts. A surface thought at first to be part land, part water; the land next seen to be seamed with straits; and lastly the sea made out to be land. Such is the history of the subject, and words could not have summed it more succinctly. “Vidi ego, quod fuerat quondam solidissima tellus esse fretum” rings like Schiaparelli’s own announcement of the discovery of the ‘canals.’ Indeed, I venture to believe he would have made it had he chanced to recall the verse. So “vidi factas ex aequore terras” tells what has since been learned of the character of the seas.

Of the three periods the first was that of the main or fundamental markings only. It came in with Beer and Maedler, the inaugurators of areography. That they planned and executed their survey with but a four-inch glass shows that there is always room for genius at the top of any profession and that instruments are not for everything in its instrumentality. Up to their day the reality of the planet’s features had been questioned by some people in spite of having been certainly seen and drawn by Huyghens and others. Beer and Maedler’s labors proved them permanent facts beyond the possibility of dispute.

The second period was the period of the discovery of the now famous canals,—a new era in the study of Mars opened by Schiaparelli in 1877 (Map V). Unsuspicious of what he was to stumble on, he seized the then favorable opposition to make, as he put it, a geodetic survey of the planet’s surface. He hoped this undertaking feasible to the accuracy of micrometric measurement. His hopes did not belie him. He found that it was possible to measure his positions with sufficient exactness to make a skeleton map on which to embody the markings in detail—and thus to give his map vertebrate support. But in the course of his work he became aware of hitherto unrecognized ligaments connecting the seas with one another. Instead of displaying a broad unity of face the bright areas appeared to be but groundwork for streaks. The streaks traversed them in all directions, tesselating the continents into a tilework of islands. Such mosaic was not only new, but the fashion of the thing was of a new order or kind. Straits, however, Schiaparelli considered them and gave them the name canali, or channels. How unfamiliar and seemingly impossible the new detail was is best evidenced by the prompt and unanimous disbelief with which it was met.

Map I. Beer and Maedler, 1840.

Map II. Kaiser, 1864.
(From Flammarion’s Mars.)

Map III. Résumé by Flammarion, 1876.
(From Flammarion’s Mars.)

Map IV. Green, 1877.
(From Flammarion’s Mars.)

Unmoved by the universal scepticism which rewarded what was to prove an epoch-making discovery, Schiaparelli went on, in the judgment of his critics, from bad to worse—for in 1879 (Map VI) he took up again his scrutiny of the planet to the detecting of yet more particularity. He re-observed most of his old canals and discovered half as many more; and as his map shows he perceived an increased regularity in his lines.

In 1881-1882 (Map VII) he attacked the planet again and with results yet further out of the common. His lines were still there with more beside. If they had looked strange before, they now appeared positively unnatural. Not content with a regularity which seemed to the sceptics to preclude their being facts, he must needs see them now in duplicate. To the eyes of disbelief this was the crowning stroke of factitiousness.

In consequence no end of adverse criticism was heaped upon his observations by those who could not see. But curiously enough,—what did not attract attention,—the blindness of the critics was as much mental as bodily. For they failed to perceive that the very unnaturalness which seemed to them to discredit his observations really proved their genuineness. His discoveries were so amazing that any change in strangeness simply went to confirm the universal scepticism and clouded logic. Yet properly viewed, a pregnant deduction stands forth quite clearly on a study of the maps.

Map V. Schiaparelli, 1877.
(From Schiaparelli’s Memoria.)

Map VI. Schiaparelli, 1879.
(From Schiaparelli’s Memoria.)

Map VII. Schiaparelli, 1881.
(From Schiaparelli’s Memoria.)

Map VIII. Schiaparelli, 1884.
(From Schiaparelli’s Memoria.)

On comparing maps V, VI and VII an eye duly directed is struck by a difference in the aspect of the lines. In his first map the ‘canals’ are depicted simply as narrow winding streaks, hardly even roughly regular and by no means such departures from the plausible as to lie without the communicatory pale. Indeed, to a modern reader prepared beforehand for geometric construction they will probably appear no ‘canals’ at all. Certainly the price of acceptance was not a large one to pay. But like that of the Sibylline Books it increased with putting off. What he offered the public in 1879 was much more dearly to be bought. The lines were straighter, narrower, and in every way less natural than they had seemed two years before. In 1881-1882 they progressed still more in unaccountability. They had now become regular rule and compass lines, as straight, as even, and as precise as any draughtsman could wish and quite what astronomic faith did not desire. Having thus donned the character, they nevermore put it off.

Now, this curious evolution in depiction points, rightly viewed, to an absence of design. It shows that Schiaparelli started with no preconceived idea on the subject. On the contrary, it is clear that he shared to begin with the prevailing hesitancy to accept anything out of the ordinary. Nor did he overcome his reluctance except as by degrees he was compelled. For the canals did not change their characteristics from one opposition to another; the eye it was that learned to distinguish what it saw, and the brain made better report as it grew familiar with the messages sent it. In other words, it is patent from these successive maps that the geometrical character of the ‘canals’ was forced upon Schiaparelli by the things themselves, instead of being, as his critics took for granted, foisted on them by him. We have since seen the regularity of the canals so undeniably that we are not now in need of such inferential support to help us to the truth; but too late, as it is, to be of controversial moment the deduction is none the less of some corroboratory force.

With the third period enters what has been done since Schiaparelli’s time. For that master was obliged, from failing sight, to close his work with the opposition of 1890. In 1892 W. H. Pickering at Arequipa was the chief observer of the planet and made two important discoveries: one was the detection of small round spots scattered over the surface of the planet and connected with the canal system; the other the perception of what seemed to him more or less irregular lines traversing the Mare Erythraeum. Both were notable detections. The first set of phenomena he called lakes, the second river-systems, sometimes schematically ‘canals,’ but without committing himself to canaliform characteristics as his drawings make clear. The same phenomena were seen at that opposition at the Lick, by Schaeberle, Barnard and others, and called streaks. These discoveries took from the maria their supposed character of seas—a most important event in knowledge of Mars.

Map IX. Lowell, 1894.

Map X. Lowell, 1896.

Map XI. Lowell, 1901.

Map XII. Lowell, 1905.

The next advance was the detection at Flagstaff in 1894 of their canaliform characteristics by my then assistant Mr. Douglass, who in place of the irregular streaks and river-systems of his predecessors found the seas to be crossed by lines as regular and as regularly connected as the canals in the light regions. To him they appeared broad and ill defined, but so habitually did to him the canals in the light areas, while for directness and uniformity the one set showed as geometrically perfect as the other. All the dark maria of the southern hemisphere he found to be laced with them and that they formed a network over the dark regions, counterparting that over the light. Still more significant was the fact that their points of departure coincided with the points of arrival of the bright-region canals, so that the two connected to form in its entirety a single system. After the publication of his results (Lowell Observatory Annals, Volume I, 1895) Schiaparelli identified some of those in the Syrtis with what he had himself seen there in 1888 (Memoria, VI, 1899), though his own had not been sufficiently well seen of him to impress him as canals.

Of other additions to our knowledge since made by the writer the present book treats; as also of the theory they originally suggested to him and which his later observations have only gone to confirm.

CHAPTER IV
 
THE POLAR CAPS

Almost as soon as magnification gives Mars a disk that disk shows markings, white spots crowning a globe spread with blue-green patches on an orange ground. The smallest telescope is capable of this far-off revelation; while with increased power the picture grows steadily more articulate and full. With a two and a quarter inch glass the writer saw them thirty-five years ago.

After the assurance that markings exist the next thing to arrest attention is that these markings move. The patches of color first made out by the observer are shortly found by him to have shifted in place upon the planet. And this not through mistake on his part but through method in the phenomena; for all do it alike. In orderly rotation the features make their appearance upon the body’s righthand limb (in the telescopic image), travel across the central meridian of the disk and vanish over its lefthand border. One follows another, each rising, culminating and setting in its turn under the observer’s gaze. A constantly progressing panorama passes majestically before his sight, new objects replacing the old with a march so steady and withal so swift that a few minutes will suffice to mark unmistakably the fact of such procession. But for all this ceaseless turning under his gaze, after a certain lapse of time it is evident that the same features are being shown him over again. With such recognition of recurrence comes the first advance toward acquaintance with the Martian world. For that in all their journeying their configuration alters not, proves them permanent in place, part and parcel of the solid surface of that other globe. This surface, then, lies exposed to view and by its turning shows itself subject, like our earth, to the vicissitudes of day and night.

In such self-exposure Mars differs from all the four great planets, Jupiter, Saturn, Uranus and Neptune. Features, indeed, are apparent on the first two of these globes and dimly on the other two as well, but they lack the stability of the Martian markings. They are forever exchanging place. In the case of Jupiter what we see is undoubtedly a cloud-envelop through which occasional glimpses may possibly be caught of a chaotic nucleus below. With Saturn it is the same; and the evidence is that the like is true of Uranus and Neptune. What goes on under their great cloud canopies we can only surmise. With Mars, however, we are not left to imagination in the matter but so far as our means permit can actually observe what there takes place. Except for distance, which, through science, year by year grows less, it is as if we hovered above the planet in a balloon, with its various features spread out to our gaze below.

Attention shows these areographic features to be on hand with punctual precision for their traverse of the disk once every twenty-four hours and thirty-seven minutes. For over two hundred years this has been the case, their untiring revolutions having been watched so well that we know the time they take to the nicety of a couple of hundredths of a second. We thus become possessed of a knowledge of the length of the Martian day and it is not a little interesting to find that it very closely counterparts in duration our own, being only one thirty-fifth the longer of the two. We also find from the course the markings pursue the axis about which they turn; and just as the period of the rotation tells us the length of the Martian day so the tilt of the axis, taken in connection with the form of the orbit, determines the character of the Martian seasons. Here again we confront a curious resemblance in the circumstances of the two planets, for the tilt of the equator to the plane of the orbit is with Mars almost precisely what it is for the Earth. The more carefully the two are measured the closer the similitude becomes. Sir William Herschel made the Martian 28°, Schiaparelli reduced this to 25°, and later determination by the writer puts it nearer 24°. The latter is the one now adopted in the British Nautical Almanac for observers of the planet. This is a very close parallelism indeed; so that in general character the Martian seasons are nearly the counterpart of ours. In length, however, they differ; first because the year of Mars is almost double the length of the terrestrial one and secondly because from the greater ellipticity of Mars’ orbit the seasons are more unequal than is the case with us, some being run through with great haste, others being lingered on a disproportionate time. It is usual on the Earth to consider spring as the period from the vernal equinox, about March 21, to the summer solstice, about June 20; summer as lasting thence to the autumnal equinox; autumn from this latter date, about September 20, to the winter solstice on December 21; and winter from that point on to the next spring equinox again. On this division our seasons in the northern hemisphere last respectively: spring, 91 days; summer, 92 days; autumn, 92 days; and winter, 90 days. On Mars these become, reckoned in our days: spring, 199 days; summer 183 days; autumn, 147 days; and winter, 158 days. If we had counted them in Martian days they would have totaled about one thirty-fifth less in number each.

In its days and seasons, then, Mars is wonderfully like the Earth; except for the length of the year we should hardly know the difference in reckoning of time could we some morning wake up there instead of here. Only in one really unimportant respect should we feel strange; in months we should find ourselves turned topsy-turvy. But lunations have nothing to do with climate nor with the alternation between night and day; and in these two important respects we should certainly feel at home.

Though the axis could be determined by the daily march of any marking and thus the planet’s tropic, temperate and polar regions marked out, the process is made easier by the presence of white patches covering the planet’s poles and known, in consequence, as the polar caps. It is from measures of the patches that the position of the Martian poles has actually been determined. These polar caps are exactly analogous in general position to those which bonnet our own Earth. They reproduce the appearance of the ice and snow of our arctic and antarctic regions seen from space, in a very remarkable manner. In truth they are things of note in more ways than one and would claim precedence on many counts. Priority of recognition, however, alone entitles them to premier consideration. Among the very first of the disk’s detail to be made out by man, they justly demand description first.

With peculiar propriety the polar caps have thus the pas. Not only do they stand first in order of visibility, but they prove to occupy a like position logically when it comes to an explanation of the planet’s present physical state. It is not matter of hazard that the most evident of all the planet’s markings should also be the most fundamental, the fountainhead from which everything else flows. It is of the essence of the planet’s condition and furnishes the key to its comprehension. The steps leading to this conclusion are as interesting as they are cogent. They start at the polar caps’ visibility. For their size first riveted man’s attention and then attention to them disclosed that most vital of the characteristics of the planet’s surface: change.

Just as almost all of the features we note are permanent in place, showing that they belong to the surface, so are they all impermanent in character. Change is the only absolutely unchanging thing except position about the features the planet presents to view. It was in the aspect of the polar caps that this important fact first came to light. Not only did they thus initially instance a general law, they have turned out to make it; for by themselves changing they largely cause change in all the rest. But for a long time they alone exemplified its workings. To Sir William Herschel we owe the first study of their change in aspect. This eminent observer noted that their varying size was subject to a regular rhythmic wax and wane timed to the course of the seasons of the planet’s year. The caps increased in the winter of their hemisphere and decreased in its summer and being situate in opposite hemispheres they did this alternately with pendulum-like precision. His observations were soon abundantly confirmed, for the phenomena take place upon a vast scale and are thus easy of recognition. At their maximum spread the caps cover more than one hundred times as much ground as when they have shrunk to their minimum. In the depth of winter they stretch over much more than the polar zone, coming down to 60° and even 50° of latitude north or south as the case may be, thence melting till by midsummer they span only five or six degrees across.

In this they bear close analogue to the behavior of our own. Ours would show not otherwise were they viewed from the impersonal standpoint of space. Very little telescopic aid suffices to disclose the Martian polar phenomena in this their more salient characteristics and convince an observer of their likeness to those of the earth. Any one may note what is there going on by successive observations of the planet with a three-inch glass. Nor is the change by any means slow. A few days at the proper Martian season, or at most a couple of weeks, produces conspicuous and conclusive alterations in the size of these nightcaps of the planet’s winter sleep. Resembling our own so well they were early surmised to be of like constitution and composed, therefore, of ice and snow. Plausible on its face, this view of them was generally adopted and common sense has held to it ever since. It has encountered, of course, opposition, partly from very proper conservatism, but chiefly from that earth-centred philosophy which has doubted most advances since Galileo’s time, and carbonic acid has been put forward by this school of sceptics to take its place. We shall critically examine both objections; the latter first, because a certain physical fact enables us to dispose of it at once. In casual appearance there is not much to choose between the rival candidates of common sense and uncommon subtlety, water and frozen carbonic acid gas, both being suitably white and both going and coming with the temperature. But, upon closer study, in one point of behavior the two substances act quite unlike, and had half the ingenuity been expended in testing the theory as in broaching it this fact had come to light to the suggestors as it did upon examination to the writer and had served as a touchstone in the case. At pressures of anything like one atmosphere or less carbonic acid passes at once from the solid to the gaseous state. Water, on the other hand, lingers in the intermediate stage of a liquid. Now, as the Martian cap melts it shows surrounded by a deep blue band which accompanies it in its retreat, shrinking to keep pace with the shrinkage in the cap. This is clearly the product of the disintegration since it waits so studiously upon it. The substance composing the cap, then, does not pass instantaneously or anything like it from the solid to the gaseous condition.

This badge of blue ribbon about the melting cap, therefore, conclusively shows that carbonic acid is not what we see and leaves us with the only alternative we know of: water.