oases, darkened with growing crops between August and October, and remained conspicuous until the close of the observations. The southern polar inundation thus ran itself out only when it had reached to about the fortieth parallel of northern latitude. It was expended, besides, in fertilizing districts just at the depth of the local winter. Surely there must be something wrong here. We can hardly imagine so shrewd a people as the irrigators of Thule and Hellas wasting labor, and the life-giving fluid economizing which their labor is devoted, after so unprofitable a fashion.

to

In reality, however, it would not b left to their discretion to share with the opposite hemisphere supplies which would certainly fall short of what was wanted for their own. There is every reason to believe that the Martian snow-caps are quite flimsy structures. Their material might be called snow soufflé, since, owing. to the small power of gravity on Mars, snow is almost three times lighter there than here. Consequently, its own weight can have very little effect in rendering it compact. Nor, indeed, is there time for much settling down. The calotte does not form until several months after the winter solstice, and it begins to melt, as a rule, shortly after the vernal equinox. (The interval between the two epochs in the southern hemisphere of Mars is one hundred and seventy-six days.) The snow lies on the ground, at the outside, a couple of months. At times it melts while it is still fresh-fallen Thus, at the opposition of 1881-82 the spreading of the northern snows was delayed until seven weeks after the equinox; and they had, accordingly, no sooner reached their maximum than they began to decline. And Professor Pickering's photographs of April 9 and 10, 1890, proved that the southern calotte may assume its in a definitive proportions single night.

No attempt has ever been made to estimate the quantity of water de

these formations; yet the experiment is worth trying as a help towards defining ideas. Let us grant that the average depth of snow in them, of the delicate Martian kind, is twenty feet equivalent, at the most, to one foot of water. The maximum area covered of two million four hundred thousand square miles, is nearly equal to that of the United States, while the whole globe of Mars measures fifty-five mil lion five hundred thousand square miles, of which one-third-on the present hypothesis-is under cultivation, and in need of water. Nearly the whole of these dark areas are situated, as we know, in the southern hemisphere, of which they extend over, at the very least, seventeen million square miles; that is to say, they cover an area, in round numbers, seven times that of the snow-cap. Only oneseventh of a foot of water, accordingly could possibly be made available for their fertilization, supposing them to get the entire advantage of the spring freshet. Upon a stint of less than two inches of water these "forest lands" are expected to flourish and bear abundant fruit; and, since they completely enclose the pole, they are necessarily served first. The great emissaries for carrying off the excess of their aqueous riches would then appear to be superfluous constructions; nor is it likely that the share in those riches due to the canals and oases, intricately dividing up the wide, dry, continental plains, can ever be realized.

We have assumed in our little calculation that the entire contents of a polar hood turn to water; but in actual fact a considerable proportion of them must pass directly into vapor, omitting the intermediate stage. The process may often be watched in London itself, where large patches of soiled and dishonored snow, ignored by the vestries, are, by a particula "courtesy of Nature," removed aërially. And in the rare atmosphere of Mars this cause of waste must be especially effective. Thus the polar

reservoirs are despoiled in the act of being opened. Further objections might be taken to Mr. Lowell's irrigation scheme; but enough has been said to show that it is hopelessly unworkable.

Mars is, nevertheless, a globe highly sensitive, if we may so express our meaning, to the vicissitudes of the seasons. At the time when frigid bonds are loosed in each hemisphere, striking variations occur in the configuration of what we must still continue to call land and water. Among the elements of change are assuredly to be reckoned polar inundations, on a scale much reduced from Mr. Lowell's portentous design, and there is no reason to deny that the development of vegetation may play its part. The effects of wintry rains on the hemisphere partially averted from sun and earth, and hence not directly perceptible to us, most likely become visible in the darkening of pre-equinoctial canals, while mountain torrents may here and there contribute to alter temporarily the planet's physiognomy. From his patient study of these phenomena, Schiaparelli has been led to conclude "that abnormal variations in the markings of Mars follow no casual or irregular succession, but that identical changes may be reproduced after long intervals of time. The form and extent of such variations, he continues, "are determined by some stable, or at least periodical, element."1

The mountains of Mars form a theme of no slight perplexity. The southern polar area beyond question bristles with peaks; they show isolated by the melting of the snows, and star-points of sunlight, directly flashed back by them, were caught by Green at Madeira in 1877, as well as by Lowell at Flagstaff in 1894. Yet the detection of numerous inequalities in the "terminator" (the dividing line between light and darkness when the planet is gibbous) ranks as one of the most noteworthy of the Flagstaff achievements; and bright spots above that same sunrise or sunset verge, as the case may be, have been frequently and surely observed, and

1 Astr. Nach. No. 3271.

seem to be most easily explained by the anticipated illumination or retarded extinction of lofty summits catching or detaining sun-rays. The effect was seen with peculiar distinctness on August 27 last, by Professor Hussey, of the Lick Observatory.

Nevertheless, we seem, as Mr. Lowell expresses it, to be placed "in a dilemma between mountains on the one hand and canals on the other." The network of watercourses, if such indeed they be, peremptorily demands, to our apprehension, a continental tabula rasa.

The system seems sublimely superior to possible obstructions in the way; the liues running, apparently, not where they may, but where they choose. The EumenidesOrcus, for example, pursues the even tenor of its unswerving course for nearly thirty-five hundred miles. Now, it might be possible so to select one's country that one canal should be able to do this; but that every canal should be straight, and many of them fairly comparable with the Eumenides-Orcus in length, seems to be beyond the possibility of contrivance.

Our present author extricates himself from the dilemma by substituting clouds for mountains everywhere, except at the pole, where they are innocuous to theory; but his reasonings on the subject fail to carry conviction. Additional facts are needed, and they will soon, we may hope, be forthcoming. Careful locations, for instance, of the "bright projections," just described as visible above the terminator, like the mountains of the moon, must prove decisive as to their nature. The key to Martian enigmas of all classes can only be found in persistent observations-in observations pursued night by night and month after month, excepting only when the planet's position is not merely unfavorable, but impossible. With modern telescopes its disc studied with profit when no more than seven seconds of arc in apparent diameter. Mr. Lovell has, then, taken the right way, and means, apparently, to persevere in it. He has arranged to observe the opposition of December nextnot a particularly propitious one-from a post near the city of Mexico, and has

can be

added to his equipment for the occasion a 24-inch refractor by Alvan G. Clark, the powers of which have already been displayed by Dr. See's re-detection with it of the long-hidden companion of Sirius.

The spectrum of Mars will probably receive much future attention. The presence in it of dark bands due to aqueous absorption was announced by Huggins and Janssen in 1867, was confirmed by Vogel in 1873, denied by Campbell of Lick in 1894, and almost immediately reaffirmed, on the ground of fresh and highly critical observations, by Dr. and Mrs. Huggins. They obtained, in addition, signs of the arresting action upon light of an unknown ingredient in the planet's atmosphere. Mr. Lewis E. Jewell, of Baltimore, U.S., no mean authority, holds that oxygen is not unlikely to disclose itself after a similar fashion. Nay, it has been suggested that the emergence of chlorophyll-bands in the rays derived from the greenish areas during the Martian spring might establish beyond appeal their sylvan character. But this is a one-sided test, since a negative result would be valueless.

One of the popular assumptions about our neighbor-planet is that it is far advanced in senile decay. Hence, according to Mr. Lowell, the perennial waterfamine by which its inhabitants are stimulated to superhuman exertions. It is "just what theory would lead us to expect." For Mars, being smaller than the earth, “is relatively more advanced in his evolutionary career. He is older in age, if not in years; for whether his birth as a separate world antedated ours or not, his smaller size, by causing him to cool more quickly, would necessarily age him faster." And again:

We have before us in Mars the spectacle of a world relatively well on in years, a world much older than the earth. To so much about his age Mars bears evidence on his face. He shows unmistakable signs of being old. Advancing planetary years have left their mark legible there. His continents are all smoothed down; his oceans have all dried up.

These inferences are, to say the least, questionable. The geological history of Mars is for the present a sealed book to us; nor can we pretend to determine the stage of development at which he has arrived. It may possibly be a backward one; in which case the anomalous mildness of his climate might be explained by the still sensible effects of his internal heat. We are ignorant of the epoch when he was first set spinning as an independent globe; we are ignorant as to the conditions by which his rate of cooling was regulated and modified.

The difficulty of assigning

on any cut-and-dried principle the order of planetary seniority is illustrated by the significant fact that Uranus and Neptune, the exterior members of the solar system, although small by comparison with Jupiter and Saturn, are unmistakably less advanced on the road towards completion as habitable worlds.

Such Mars appears now to be; to assert more would be to launch into the realms of speculation. The extraordinary difficulty of interpreting the map of this planet cannot legitimately be evaded by attributing its peculiarities to the intervention of engineering genius. The Alexander's sword of cosmical intelligence, so freely wielded by Mr. Lowell, is not a scientific weapon. In physical investigations knots have to be untied, not cut. Upon the geometrical regularity of the canal system our author bases his chief argument for their artificial production. Its "very aspect," he exclaims, "is such as to defy natural explanations." "Diversity in uniformity" he takes to be distinctive of unassisted nature; while "too great regularity" raises more than a suspicion "that some finite intelligence has been at work." The doubling of the canals, although he has no recipe of explanation at hand for it, strengthens this persuasion. "It is the most artificial-looking phenomenon of an artificial-looking disc."

To the Greek mind, however, the making of the world was, it might be said by rule and compass; the Divine idea was essentially mathematical. Schia

parelli has made some admirable re marks in this very connection. Speak ing of Martian "geminations," he says:

The geometry of nature is manifested in many other facts, which entirely exclude the idea of artificial labor. The perfect spheroids of the heavenly bodies and the ring of Saturn were not constructed in a turning-lathe, and not with compasses has Iris described in the clouds her beautiful and regular arch. And what shall we say of the infinite variety of those exquisite and regular polyhedrons in which the world of crystals is so rich! In the organic world also, what wonderful geometry presides over the distribution of foliage on certain plants, orders the nearly symmetrical star-like forms of flowers and marine animals, and produces in the shell a perfect conical spiral excelling the finest masterpieces of Gothic architecture! In all these objects the geometrical figure is the simple and necessary consequence of the principles and laws which govern the physical and physiological world. That such principles and laws are but an indication of a higher intelligent Power we may admit; the admission has, however, nothing to do with the present argument.

There is, then, no compulsion upon us to regard the surface of Mars as modelled to suit their vital needs by the industry of rational creatures. Irriga tion hypotheses, inland navigation hypotheses, and the like, are superfluous, and, being superfluous, are inadmissible. Not that they are, in all shapes, demonstrably false, but that they open the door to pure license in theorizing. The admission of vegetable growth and decay as an element of visible change is less objectionable, and is apparently capable of being justified spectroscopically; but. until that or some other kind of definite evidence is forthcoming, the subject invites only nebulous conjecture. In any case, Martian seas cannot be abolished, their presence being indispensable to the

systematic and rapid circulation of water, which is the most obviously executed process of the planet's internal economy.

We venture to disclaim, on behalf of humanity, the extramundane jealousy imputed to it by Mr. Lowell. At the close of this nineteenth century, after so many poignant disillusions, amid the wreck of so many passionate hopes, it is not enamoured with its own destinies to the point of desiring to impose them as a maximum of happiness upon the universe. Rather, men cherish the vision of other and better worlds, where intelligence, untrammelled by moral disabilities, may have risen to unimaginable heights, and sense and reason alike are dominated by incorrupt will. But it is improbable that the vision can ever be located in any one of the disseminated orbs around us. The problem of universal life is an enticing, yet insoluble one. That inorganic nature has, everyappointed final cause the production of where and always, for its designed and organic life may be true, but can scarcely be assumed as a matter of course; while, on the other hand, the thought that millions of globes roll through space tenantless for all time revolts our sense of the rational in creation. Science can only declare that a given planet appears, so far as physical investigation can tell, to be habitable; nihil obstat is its last word on the subject. The word "habitable" has, however, a very wide implication. The hierarchy of life has endless gradations. The "roof and crown of things" in some remote worlds may be a race as far below the genus homo as it is above it in others. Could the veil be lifted, incomprehensible diversity would, without doubt, be found to prevail here as elsewhere in the works of Infinite Wisdom. For "one star differeth from another star in glory."