Part 5

A fair sample of the subjects which occupy the astronomers' mind, and which are so remote from the study of planetary markings, and have so little interest for the public, may be gathered from the following list selected at random from an astronomical publication. Notes on variable stars; Maxima and minima of long period variables; Micrometrical measurements of the companion of Procyon; The problem of three bodies; Ephemeris of Comet a, 1901; On the eruptive energy of the stars; Eclipse cycles; Determinations of the aberration-constant from right ascension; Theory of a resisting medium upon bodies moving in parabolic orbits; Weights and systematic corrections of meridian observation in right ascension and declination; and other titles equally profound. Many of these memoirs consist of hundreds of pages of figures, and, as a friend of mine observed, not a column footed up! Take for example a title like the following: "Method of developing the perturbative functions, also precepts for executing their development." This memoir is accompanied by pages of algebraic formulæ which the layman turns over in despair, the only illumination consisting of a few words in English which render the gloom still more apparent,--such words as "hence," "or," "we therefore have," "if we put." Of what we "have," and why we "put," we are left in profound ignorance. Now I venture to believe that the great world of humanity takes but little interest in such pages, or in the kinds of titles above given, though fully realizing that they mean something and represent important steps in astronomic research. It would add greatly to the value of these contributions if a brief summary in plain English could be given at the end of these papers, but it is the rarest event that these collectors of data ever make any generalizations, or form any deductions.

My faith in the appalling character of algebraic formulæ[5] received a rude shock when I learned of an experience of Louise Michel, the anarchist, who was transported for life to New Caledonia (afterwards pardoned). On arriving at the savage island, true to her humanitarian instincts, "she immediately established a school for native children, who by a curious freak of their minds, she noted with rejoicing, took naturally to algebra before they learned arithmetic!"

Hovenden quotes Huxley as saying that mathematics "is that study that knows nothing of observation, nothing of induction, nothing of experiment, nothing of causation." He also quotes the words of Clerk Maxwell, who said, in regard to mathematicians, that it was "doubtful whether the ideas as expressed in symbols had ever quite found their way out of the equations into their minds." They never seem to appeal to the doctrine of probabilities nor do they in any way permit imagination to act as a stimulus to suggestive thought.

Least of all would a layman ridicule or question the painstaking labor involved in astronomic work, though he cannot see a glimmer of light or intelligence in the enigmatical pages. A certain class of astronomers might take a lesson from an intelligent public in ceasing to scoff and ridicule what they are unable to see themselves in the Martian markings. The chief work of these men indicates the cold precise measuring of points of light in the heavens, the determination of orbits, elements and ephemeris of heavenly bodies, the determination of solar parallax, etc., most of the subjects strictly mathematical, a question of careful measurements for which the necessary instruments are at hand, or simply sweeping the heavens for a new variable, binary or asteroid. Parallaxes and orbits are matters of measurement to be reckoned by the figures of anybody else. It is obvious from all this that little or no interest is manifested by astronomers in planetary markings, least of all in those of Mars. The exasperating feature of the matter is that they persistently repudiate the observation of others equally well equipped, and endowed with the same enthusiasm and devotion to their work.

The way in which the gatherers of the raw material arrogate to themselves the science of astronomy, relegating the thinkers and generalizers to the limbo of speculation, is as if the book-keepers of a corporation should assume themselves to be the master-minds of the concern and the banker, or financier, at the head of it, a dreamer not worth regarding.

An illustration of the conservativeness of astronomers in regard to planetary markings is shown in their cautious attitude concerning the polar snow caps of Mars. Here are white polar caps on Mars, precisely where they ought to be if they _are_ snow, they wax and wane at the time they should and at no other time, a dark band appears at their borders as the caps in turn diminish in size, which has been interpreted as water due to the melting snow, and no other substance known could possibly reproduce these varying conditions. Professor C. A. Young, in describing these white areas, says: "The one which happens to be turned toward the Sun continually diminishes in size, while the other increases, the process being reversed with the seasons of the planet." After these admissions Professor Young cautiously says: "These are believed to be ice caps." Sir John Herschel says: "The variety in the spots may arise from the planet not being destitute of atmosphere and clouds, and what adds greatly to the probability of this is the appearance of brilliant white spots at the poles--one of which appears in our figure--which have been conjectured with some probability to be snow, as they disappear when they have been long exposed to the Sun, and are greatest when just emerging from the long night of the polar winter." Had Michael Faraday been an astronomer, how long would it have taken him to pronounce these white polar caps snow and ice? De la Rive, in his memoir of Faraday, in speaking of his marvellous accomplishments, says: "One may easily understand what must be produced under such circumstances by a life thus wholly consecrated to science, when to a strong and vigorous intellect is joined a most brilliant imagination." Tyndall, in his discourse "On the Scientific use of the Imagination," says: "Bounded and conditioned by co-operant reason, imagination becomes the mightiest instrument of the physical discoverer. Newton's passage from a falling apple to a falling Moon was a leap of the imagination."

That Herbert Hall Turner, Professor of Astronomy in the University of Oxford, does not regard the various contributions on the surface features of Mars as belonging to astronomical science may be inferred from his interesting book lately published, entitled "Astronomical Discovery." This book presents to us the history of the discovery of Uranus and Eros, of Neptune, Bradley's aberration of light, Schwabe and sun-spot period, the variation of latitude, etc., but not a word about the marvellous discoveries of the _canali_ of Mars by Schiaparelli, so fully confirmed by the observation and drawings of many others, and the great advances made by Lowell in the discovery of new features with his lucid and rational interpretation of the seeming enigmas.

Astronomy, the oldest and most conservative of all the sciences, has been the last to subdivide. Already one group of men has justified by its work a division of the science known as astrophysics. The lamented Keeler, in explaining the difference between astronomy and astrophysics, said: "Astrophysics seeks to ascertain the nature of the heavenly bodies, rather than their positions and motions in space, _what_ they are, rather than _where_ they are." This natural division suggests the propriety of making another division equally distinct, which should comprise the study and interpretation of the surface markings of the planets and satellites, under the name of planetology. The study would be the application to these bodies of the science of geology, in its broadest sense, meteorology, physical geography, geodesy, and related sciences.

With the science of planetology established, the student of this science will no longer call to his aid the astronomer, and, least of all, the astrophysicist, nor will he be mindful of their criticism or neglect. He will appeal to the sciences which are involved in the study of the surface features of his own globe, in the interpretation of planetary detail.

VII

DIFFICULTIES OF SEEING

_It is contrary to all the analogies of nature to suppose that life began only on a single world._

SIMON NEWCOMB.

For years I had been familiar with different representations of Mars in which the surface features had been strongly depicted in black and white; in other words, photo-reliefs, or engravings incorporated with the printed page. I had unwittingly come to believe that these features were equally distinct when one observed Mars through the telescope. I had not then seen Schiaparelli's original memoir in which his wonderful map presents the canals in light and tenuous lines, which are, however, as clear cut as the lines of a steel engraving, to use his words. For a long time I had hoped for a chance to observe Mars through a large telescope in a clear and steady atmosphere. It seemed reasonable to me--knowing nothing about it--that one who had traced out under the microscope delicate lines and structural features in diaphanous membranes, who had, in fact, used a microscope with high powers for forty years, would find it child's play to make out the canals, oases, regions, etc., of Mars, as represented in the various publications on the subject. Professor Percival Lowell, of Flagstaff, Arizona, finally gave me the opportunity I so much desired, and, through his courtesy and kindness, I was enabled to observe Mars every night for nearly six weeks through his twenty-four inch refractor, the last and probably the best telescope ever made by Clark, mounted in one of the steadiest atmospheres in the world and at an altitude above sea-level of over 7,000 feet. Imagine my surprise and chagrin when I first saw the beautiful disk of Mars through this superb telescope. Not a line! not a marking! The object I saw could only be compared in appearance to the open mouth of a crucible filled with molten gold. Slight discolorations here and there and evanescent areas outlined for the tenth of a second, but not a determinate line or spot to be seen. Had I stopped that night, or even a week later, I might have joined the ranks of certain observers and said "illusion" or something worse. And right here it was that my experience in microscopic work helped me, for, remembering the hours--nay, days--I had worked, in making out structural features in delicate organisms which my unprofessional friends could not see at all, I realized that patient observation would be required if I was to be successful in my efforts. My despair, however, was overwhelming when Professor Lowell and his assistants, looking for a few moments at the same object, would draw on paper the features which had been plainly revealed to them, consisting of definite shaded regions, a number of canals and other markings, of which, with the utmost scrutiny, I could hardly detect a trace. For the first time I realized that observing fixed diaphanous membranes under a microscope with rigid stand, and within four inches of one's nose, was quite a different matter from observing a brilliant disk 4,200 miles in diameter, 52,000,000 miles away, with an oscillating atmosphere of unknown depth between. Night after night I examined this golden, opalescent disk, drawing each time such features as I could convey by memory from the ocular to the drawing table, and, little by little, new features were detected, and to my delight the drawings agreed with those made by the others. Since the drawings made by the four observers coincided, it was evident that we had not been victims of subjective phenomena. Furthermore, as I discovered afterwards, by comparison, the drawings I made not only agreed with theirs but with those made by other observers, at different times, in other parts of the world. So slow were my acquisitions, however, that it soon became evident that at least months of continuous observation would be necessary before the more delicate markings would be revealed to me. It is interesting to learn that others have had a similar experience. Mr. A. Stanley Williams, of England, in an article entitled "Notes on Mars" ("Observatory," June, 1899), in stating the difficulties of observation, says: "My eye invariably requires at least two months of continuous observation of a planet before it acquires its full sensitiveness to the most minute details."

In this connection it is well to state that Mr. Lowell began the observation of Mars when he was a mere boy. His first telescope, which he still has, was a two and a quarter inch refractor. His observations were made from the roof of his house in Boston, and with this small glass he defined the general shaded regions that Huyghens had detected and drawn in 1659. Since then Mr. Lowell has observed in turn through a six inch, an eighteen inch of Brashear, and, for the last few years, through a twenty-four inch refractor made by Clark especially for this work.

To refute the accumulated observations of Mr. Lowell one must have the same acute eye, and a record of the same continuous and devoted study. Nothing short of that experience will avail. The jealous derision that has gone up from some observers endowed with less acuteness of vision is neither dignified nor just. Were these Martian details based upon the observations of Lowell alone, one might be inclined to say that some vagary of the mind had led him to imagine these markings which were first detected by the great Italian astronomer Schiaparelli. Up to the present time--to mention only a few--observations and drawings have been made by Perrotin, Thollon, and Flammarion, of France; Dr. Phil. Fauth, of Germany; Williams, of England; Lowell, W. H. Pickering, Douglass, Lampland, and Schaeberle, of America, while many others have made drawings of the more conspicuous details. With this record it is impossible to deny the existence of these markings essentially as they are drawn.

The difficulty of seeing the more delicate markings of the planet is unquestionable, and an examination of astronomical literature, from which we shall make numerous quotations, indicates only too plainly the acuteness of vision, and the time and care necessary to make competent observations. Sir Robert Ball says, in one of his recent works: "The detection of the Martian features indicates one of the utmost refinements of astronomical observations." Macpherson, in his "Astronomers of To-day," thus writes of Schiaparelli, "Professor Schiaparelli's observations have been distinguished by his keen-sightedness and care. He has taken every precaution to avoid all disturbances resulting from personal equation, and has found it well to adopt the rule (which he here quotes) 'to abstain from everything which could affect the nervous system, from narcotics and alcohol, and especially from the abuse of coffee, which I found to be exceedingly prejudicial to the accuracy of observation.'" What I might have accomplished in the way of seeing had I followed the wise example of Schiaparelli I do not know. A not too strict abstemiousness in any of these matters, coupled with long daily walks on the Mesa, with its fascinating flora and fauna, found me in the observer's chair every night, somewhat fatigued mentally and physically.

Sir Robert Ball, in his "Popular Guide to the Heavens," in describing the difficulty in making out the more delicate markings of Mars, says: "It should be understood that in the unsteady air of England it is almost hopeless to expect many of the finer details; not even in the most favorable climates are they to be seen always, or all at once, and much training of the eye is required before it is fit to decide for or against the existence of these details on the verge of invisibility." As another illustration, perhaps, of the difficulties of seeing, Sir Robert, in the same book, says: "Observers of Mars are divided into two camps, those who see the canals, and those who do not. The former are in the strong position that they are perfectly sure that they see what they represent in their drawings."

From the foregoing it must be evident that not only are the finer markings on Mars most difficult to see even under the best conditions but that exceptional acuteness of vision, which few possess, united with long practice, is necessary to make out the tenuous lines which enclose the field of Mars like a net. That Mr. Lowell has had a long and continuous practice, covering years, in observing Mars through the steadiest of atmospheres and with a superb glass, is simply a statement of fact. It may be said without fear of contradiction that he has devoted more time to the observation of Mars than all the other observers combined. Has he then an exceptional acuteness of sight, coupled with indefatigable industry, in the pursuit of this quest to which he is devoting his life and fortune? The following instance will illustrate his marvellous eyesight. We were walking along the shores of a lake some miles from Flagstaff, the expanse of shore left by the rapidly evaporating waters abounding with thousands of very small black spiders running hither and thither at our approach. I told him of one I had just seen in which the abdomen was covered with minute young spiders which the mother was carrying about with her--a well-known habit of certain species. This curious fact I had detected only while stooping close to the ground in search of minute shells. Mr. Lowell, while walking along, immediately began scanning the ground for the trace of a spider with minutely granulated abdomen, and finally exclaimed: "There is one of them!" On stooping down to examine the object it proved to my astonishment to be a female carrying its young in the way already described. This incident revealed a remarkable acuteness of vision to detect, while standing erect and walking, this tiny spider among hundreds of others of its species that were scampering away at our approach.

Not only is acuteness of vision necessary to one who is to study planetary markings, but of importance also is a clear, and above all a steady atmosphere; and, strange as it may appear, telescopes of moderate size seem to be the instruments with which the best work has been done. It is also true in astronomy, as in warfare, that it is not the biggest gun but the man behind the gun that does the most efficient work. As an evidence of the importance of steady atmosphere Professor W. H. Pickering, in his observations on the satellites of Jupiter, says his work had two important bearings: "First, as showing the relative importance of atmosphere _versus_ aperture for delicate visual observations of this sort. In the same category would be included studies of planetary detail as distinguished from the examination of very faint objects. In other words, if an observer wishes to study very faint stars he must have a large telescope. If he wishes to study the neighboring planets and brighter satellites he may use a small telescope, but he must have a very good atmosphere."

The importance of a clear and steady atmosphere, for delicate observation, is known to all astronomers. The rarity of such days, even in our clear atmosphere so superior to that of England, is not generally known. Forty years ago Dr. Henry Draper, in an address entitled "Are Other Worlds Inhabited?" in speaking of Mars and the difficulties of seeing, said: "One of the greatest obstacles to distinct vision is our own atmosphere. Its currents and motions tend to confuse the outlines of objects, and, according to my experience, a whole year may pass without the occurrence of more than one good night. The only remedy is to carry the telescope as high up on a mountain as possible, so as to leave below the more injurious portions of the atmosphere. It might be possible to work 15,000 feet above the sea in the neighborhood of the Equator." I quote these words that the general reader may appreciate the advantages Lowell has with his fine telescope south of all European observatories, in the latitude, say of Algiers, at a high altitude, and in the dry and steady atmosphere of Arizona, with uninterrupted seeing for weeks together, and each night far superior to any night which Greenwich could ever be blessed with.

Professor W. H. Pickering attests to the importance of a steady atmosphere in studying the Moon from a station in Jamaica, when he says that, with a five inch refractor, he was able to detect minute details which were not revealed by the far larger telescopes at Harvard University.

Mr. W. D. Barbour, President of the Leeds Astronomical Society, using his four inch achromatic, says: "In one of those brief intervals of atmospheric steadiness I saw distinctly a number of well-known markings," the names of which he gives. Dr. Phil. Fauth, using a seven inch refractor, made sixty-three drawings of Mars, showing in wonderful detail the canals, oases, etc. Mr. W. J. Lockyer, in London "Nature," testifies that "a keen and patient observer, sitting at the eyepiece of a comparatively small equatorially mounted telescope, if he makes his observations carefully, and with due regard to atmospheric conditions for good seeing, can do more useful and valuable work than one who has a large aperture at his command and employs it indifferently." Mr. E. Ledger, in speaking of Dawes, who made a remarkable map of Mars, says he was justly famed for the remarkable distinctness of his vision; he had detected and drawn a few lines which seemed to be identical to those of Schiaparelli.

In the authorities above quoted we have endeavored to show that a steady atmosphere, a persistent devotion to the work, accompanied by acute vision, and also a talent for observation, are all the factors needed, not only to confirm the remarkable discoveries of Schiaparelli and Lowell, but possibly to detect, at favorable moments, new features which have escaped the eyes of these keen observers.

At this point we cannot resist giving the words of Sir David Gill, Director of the Royal Observatory at the Cape of Good Hope. Professor S. W. Burnham, of the Lick Observatory, in reviewing a memoir entitled "Double Star Observations at the Cape of Good Hope," quotes as follows from the preface: "Sir David Gill, in speaking of the routine character of the work involved in the investigation, says: 'There is no instance, as far as I know, of a long and valuable series of double star discovery and observation made by a mere assistant acting under orders. _It is a special faculty, an inborn capacity, a delight in the exercise of exceptional acuteness of eyesight and natural dexterity, coupled with the gift of imagination as to the true meaning of what he observes, that imparts to the observer the requisite enthusiasm for double star observing._ No amount of training or direction could have created the Struves, a Dawes, or a Dembowski. _The great double star observer is born, not made_, and I believe that no extensive series of double star measurement will ever emanate from a regular observatory, through successive directorates, unless men are specially selected who have previously distinguished themselves in that field of work, and who were originally driven to it from sheer compulsion of inborn taste.'" If the reader will substitute the words _planetary markings_ for _double star_ in the above quotation from Sir David Gill's report, he will understand why we have ventured to italicise certain lines, and will appreciate their significance. In no stronger or truer words could one have emphasized the conditions involved in a critical study of the surface features of Mars.