 This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Is Mars Habitable? A critical examination of Professor Percival Lovel's book Mars and Its Canals with an alternative explanation by Alfred Russell Wallace, fellow of the Royal Society, etc. Preface This small volume was commenced as a review article on Professor Percival Lovel's book Mars and Its Canals, with the object of showing that the large amount of new and interesting facts contained in this work did not invalidate the conclusion I had reached in 1902 and stated in my book on a man's place in the universe that Mars was not habitable. But the more complete presentation of the opposite view in the volume now under discussion required a more detailed examination of the various physical problems involved. The subject is one of great popular as well as scientific interest. I determined to undertake the task. This was rendered the more necessary by the fact that in July last Professor Lovel published in the Philosophical Magazine an elaborate mathematical article claiming to demonstrate that notwithstanding its much greater distance from the sun and its excessively thin atmosphere, Mars possessed a climate on the average equal to that of the south of England and in its polar and sub-polar regions even less severe than that of the earth. Such a contention of course required to be dealt with and led me to collect information bearing upon temperature in all its aspect and so enlarging my criticism that I thought would be necessary to issue it in book form. Two of my mathematical friends have pointed out the chief omission which vitiates Professor Lovel's mathematical conclusions. That of a failure to recognize a very large conservative and cumulative effect of a dense atmosphere. This very point however I had already myself discussed in Chapter 6 by means of some remarkable researches on the heat of the moon and an investigation of the causes of its very low temperature I have I think demonstrated the incorrectness of Mr. Lovel's results. In my last chapter, which I briefly summarized the whole argument, I have further strengthened the case for very severe cold in Mars by reducing the rapid lowering of temperature universally caused by diminishing of atmospheric pressure as manifested in the well-known phenomena of temperate climate at moderate heights even close to the equator. Cold climates at greater heights even on extensive plateau culminating in arctic climates and perpetual snow at heights where the air is still far denser than it is on the surface of Mars. This argument itself is in my opinion conclusive, but it is enforced by two others equally complete, neither of which is adequately met by Mr. Lovel. The careful examination which I have been led to give the whole of the phenomena which Mars presents and especially to the discoveries of Mr. Lovel has led me to what I hope will be considered a satisfactory physical explanation of them. This explanation which occupies the whole of my seventh chapter is founded upon a special mode of origin for Mars derived from the meteoric hypothesis now very widely adopted by astronomers and physicists. Then by a comparison with certain well-known and widely spread geological phenomena, I show how the great features of Mars, the canals, and oases may have been called. This chapter will perhaps be the most interesting to the general reader as furnishing a quite natural explanation of the features of the planet which had been termed non-natural by Mr. Lovel. Incidentally, also, I have been led to an explanation of the highly volcanic nature of the Moon's surface. This seems to be absolutely to require some such origin as Sir George Darwin has given it, as furnishes corroborative proof of the accuracy of the hypothesis that our Moon has had a unique origin among the known satellites in having been thrown off from the Earth itself. I am indebted to Professor J. H. Pointing of the University of Birmingham for valuable suggestions on some of the more difficult points of mathematical physics here discussed, and also for the critical note at the end of Chapter 5, Professor Lovel's Estimate to the Temperature of Mars. Broadstone Endorsement, October 1907 This is the end of the preface. Chapter 1 of Ismas Habitable This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org Ismas Habitable by Alfred Russell Wallace Chapter 1 Early Observance of Mars Few persons except astronomers fully realize that of all the planets of the solar system, the only one whose solid surface has been seen with certainty is Mars. And, very fortunately, that is also the only one which is sufficiently near to us for the physical features of the surface to be determined with any accuracy, even if you could see it in the other planets. Of Venus, we probably only see the upper surface of its cloudy atmosphere. See Footnote 1 at the end of this chapter. As regards Jupiter and Saturn, this is still more certain since their low density will only permit of a comparatively small proportion of their huge bulk being solid. Their belts are but the cloud strata of their upper atmosphere, perhaps thousands of miles above their solid surface, and a somewhat similar condition seems to prevail in the far more remote planets Uranus and Neptune. It has thus happened that although the telescopic objects of interest and beauty, the marvelous rings of Saturn, the belts and ever-changing aspects of the satellites of Jupiter, and the moon-like phases of Venus together with its extreme brilliancy still remain unsurpassed. Yet the greater amount of details of these features were examined with the powerful instruments of the 19th century that neither added much to our knowledge of the planets themselves, or led to any sensational theories calculated to attract the popular imagination. But in the case of Mars, the progress of discovery has had a very different result. The most obvious peculiarity of this planet, its polar snow caps, were seen about 250 years ago. They were first proved to increase and decrease alternately in the summer and winter of each hemisphere by Sir William Herschel in the latter part of the 18th century. This fact gave the impulse to that idea of similarity in the conditions of Mars and the Earth, which the recognition of many dusky patches as streaks of water and the more ruddy and brighter portions of this land further increased. Added to this, a day only about half an hour longer than our own and a succession of seasons of the same character as ours would have nearly doubled the length owing to its much longer year seemed to leave little wanting to render this planet a true Earth on a smaller scale. It was therefore very natural to suppose that it must be inhabited and that we should someday obtain evidence of the fact. The canals discovered by Chapparelli. Hence the great interns excited when Chapparelli at the Milan Observatory during the very favorable opposition of 1877 and 1879, observed that the whole of the tropical and temperate regions from 60 degrees north to 60 degrees south latitude were covered with a remarkable network of broader curve than narrower straight lines of dark color. At each successive favorable opposition, these strange objects called canali, channels by the discoverer, but rather misleadingly canals in England and America, were observed by means of all the great telescopes of the world and the reality and general features became well established. In Chapparelli's first map, they were represented as being much broader and less sharply defined than he himself and other observers found by later and equally favorable observations than they really were. Discovery of the double canals. In 1881, another strange feature was discovered by Chapparelli who found that about 20 canals which had previously been seen single were now distinctly double. That is, they consisted of two parallel lines equally distinct and either very close together or considerable distance apart. This curious appearance was at first thought to be due to some instrumental defect or optical illusion, but it was soon confirmed by other observers with the best instruments in widely different localities. It became in time accepted as a real phenomenon of the planet's surface. The round spots discovered in 1892. At the favorable opposition of 1892, Mr. W. H. Pickering noticed that besides the seas of various sizes, there were numerous very small black spots, apparently quite circular and occurring at every intersection or starting point of the canals. Many of these had been seen by Chapparelli as larger and ill-defined dark patches and were determined seas or lakes. But Mr. Pickering's observatory was at Araquipa in Peru, about 8,000 feet above the sea, and with such perfect atmospheric conditions as were, in his opinion, equal to a doubling of telescopic aperture. They were soon detected by other observers, especially by Mr. Lowell in 1894, who wrote thus of them. Scattered over the orange ochre groundwork of the continental regions of the planet are any number of dark round spots. How many there may be is not possible to state as the better the seeing, the more of them there seem to be. In spite, however, of their great number, there is no interest of one unconnected with a canal. What is more, there is apparently none that does not lie at the junction of several canals. Reversely, all the junctions appear to be provided with spots, plotted on a globe they and their connecting canals, like a most curious network over all the orange ochre equatorial hots of the planet. A mass of lines and knots, the one marking being as omnipresent as the other. Changes of color recognized. During the oppositions of 1892 and 1894, it was fully recognized that a regular course of change occurred dependent upon the succession of the seasons, as had first been suggested by Chapparelli. As the polar snows melt, the adjacent seas appear to overflow and spread out as far as the tropics and are often seen to assume a distinctly green color. These remarkable changes and the extraordinary phenomena of perfect straight lines crossing each other over a large portion of the planet's surface, with the circular spots at the intersections, had such an appearance of artificiality that the idea that they really were canals made by intelligent beings for the purposes of irrigation was first hinted at, and then adopted as the only intelligible explanation by Mr. Lowell and a few other persons. This had once seized upon the public imagination and was spread by the newspapers and magazines over the whole civilized world. Existence of Seas Doubted At this time, 1894, it began to be doubted whether there were any seas at all on Mars. Professor Pickering thought that they were far more limited in size than had been supposed and might even not exist as true seas. Professor Barnard, with the Lick 36-inch telescope, discerned an astonishing wealth of detail on the surface of Mars, so intricate, minute, and abundant that it baffled all attempts to delineate it, and these peculiarities were seen upon the supposed seas as well as on the land surfaces. In fact, under the best conditions these seas lost all trace of uniformity, their appearance being that of a mountainous country, broken by ridges, rifts, and canyons seen from a great elevation. As we shall see later on, these doubts soon became certainties, and it is now almost universally admitted that Mars possessed no permanent bodies of water. Put note one, in reference to the telescopic observation of planetary surfaces. Mercury also seems to have a scanty atmosphere, but as its mass is only one-thirtieth that of the Earth can only retain the heavier gases, and its atmosphere may be dust-lighting, as is that of Mars, according to Mr. Lowell. Its dusky markings, as seen by Chapparelli, seem to be permanent, and there are also considerable periods unchangeable in position, indicating that the planet keeps the same pace towards the Sun as does Venus. This was confirmed by Mr. Lowell in 1896. Its distance from us, an unfavorable position for observation, was to prevent us from obtaining any detailed knowledge of its actual surface, though its low-reflective power indicates that the surface may be really visible. This concludes Chapter 1, Chapter 2 of Ismar's Happenable. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Ismar's Happenable by Alfred Russell Wallace. Chapter 2 Mr. First of Lowell's Discoveries and Theories The Observatory in Arizona. In 1994, after a careful search for the best atmospheric conditions, Mr. Lowell established his observatory near the town of Flagstaff in Arizona, in a very dry and uniform climate, and at an elevation of 7,300 feet above the sea. He then possessed a fine equatorial telescope of 18 inches aperture and 26 feet focal length, besides two smaller ones, all of the best quality. To these, he added in 1896 a telescope with 24-inch object glass, the last work of the celebrated firm of Alvin Clarkensons, which he has made his later discoveries. He thus became perhaps more favorably situated than any other astronomer in the northern hemisphere, and during the past 12 years has made a specialty of the study of Mars, besides doing much valuable astronomical work on other planets. Mr. Lowell's Recent Books Upon Mars In 1905, Mr. Lowell published an illustrated volume giving a full account of his observations of Mars from 1894 to 1903, chiefly for the use of astronomers. He has now given us a popular volume, summarizing the whole of his work on the planet, and published both in America and England by the Macmillan Company. This very interesting volume is fully illustrated with 20 plates, four of them colored, and more than 40 figures in the text showing the great variety of details from which the larger general maps have been constructed. Non-natural features of Mars. But what renders this work especially interesting to all intelligent readers is that the author has here for the first time fully set forth his views both as to the habitability of Mars and as to its being actually inhabited by beings comparable with ourselves in intellect. The larger part of the work is in fact devoted to a detailed description of what he terms the non-natural features of the planet's surface, including especially a fully account of the canals single and double, the oasis as he terms the dark spots at their intersections, and the varying visibility of both, depending partly upon the Martian seasons, while the five concluding chapters deal with the possibility of animal life and the evidence in favor of it. He also upholds the theory of the canals having been constructed for the purpose of husbanding the scanty water supply that exists. And throughout the whole of this argument he clearly shows that he considers the evidence to be satisfactory and that the only intelligible explanation of the whole of the phenomena he so clearly sets forth is that the inhabitants of Mars have carried out on their small and naturally inhospitable planet a vast system of irrigation works, far greater both in its extent, in its utility, and its effect upon their world as a habitation for civilized beings than anything we have yet done on our Earth, where our destructive agencies are perhaps more prominent than those of an improving and recuperative character. A challenge to the thinking world. This volume is therefore in the nature of a challenge. Not so much to astronomers as to the educated world at large to investigate the evidence was so portentous a conclusion. To do this requires only a general acquaintance with modern science or especially with mechanics and physics for the main contention with which I shall cheaply deal that the features term canals are really works of art and necessitate the presence of intelligent organic beings requires only care and judgment in drawing conclusions from admitted facts. As I have already paid some attention to this problem and have expressed the opinion that Mars is not habitable, see foot number two at the end of the chapter, judging from the evidence then available and as few men of science have the leisure required for a careful examination of so speculative of its object. I propose here to point out what the facts as stated by Mr. Lowell himself do not render even probable, much less true. Incidentally, I may be able to induce evidence of a more or less weighty character which seems to negate the possibility of any high form of animal life on Mars and A40 or I, the development of such life might culminate in it being equal or superior to ourselves. As most popular works on astronomy for the last ten years at least, as well as many scientific periodicals and popular magazines have reproduced some of the maps of Mars by Chaperrelli, Lowell and others, the general appearance of its surface will be familiar to most readers who will thus be fully able to appreciate Mr. Lowell's account of his own further discoveries which I may have to quote. One of the best of these maps I am able to give as a frontispiece to this volume and to this I shall mainly refer. The Canals is described by Mr. Lowell. In the clear atmosphere of Arizona, Mr. Lowell has been able on various favorable occasions to detect a network of straight lines meeting or crossing each other at various angles and often extending to a thousand or even over 2,000 miles in length, nesting the cross both the light and the dark regions of the planet's surface, often extending up to or starting from the polar snow caps. Most of these lines are so fine as to only be visible on special occasions of atmospheric clearness and steadiness which hardly ever occurred lowland stations even with the best instruments and almost all seem to be as perfectly straight as if drawn with a ruler. The Double Canals Under exceptionally favorable conditions, many of the lines that have been already seen as single appear double. A pair of equally fine lines exactly parallel throughout their whole length and appearing as Mr. Lowell says clear cut up on the disk its twin lines like the rails on a railway track. Both Shipper Alley and Lowell were first so surprised at this phenomenon that they thought it must be an optical illusion. It was only after many observations in different years and by the application of every conceivable test that they both became convinced that they witnessed a real feature of the planet's surface. Mr. Lowell says he has now seen them hundreds of times and that his first view of one was the most startlingly impressive sight he has ever witnessed. Dimensions of the Canals A few dimensions of these strange objects was be given in order that readers may appreciate their full strangeness and inexplicability. Out of more than 400 canals seen and recorded by Mr. Lowell, 51 or about 1 eighth are either constantly or occasionally seem to be double. The appearance of duplicity being more or less periodical. Of canals generally, Mr. Lowell states that they vary in length from a few hundred to a few thousand miles long and the largest being the Fison which she terms a typical double canal which is said to be 2,250 miles long. For the distance between its two constituents is about 130 miles. See footnote 3. The actual width of each canal is from a minimum of about a mile up to several miles, in one case over 20. The great feature of the doubles is that they are strictly parallel throughout their whole course and that in most cases they are so truly straight as to form parts of a great circle of the planet's sphere. A few, however, follow a gradual but very distinct curve and such of these are double present in the same strict parallelism as those which are straight. Canals extend across the seas. It was only after 17 years of observation of the canals it was found that they extended also into and across the dark spots and surfaces which by the early observers were termed seas and which then formed the only distinguishable and permanent marks on the planet's surface. At the present time Professor Lowell states that this curious triangulation has been traced over almost every portion of the planet's surface whether dark or light whether greenish, ochre or brown in colour. In some parts they are much closer together than in others forming a perfect network of lines and spots that to identify them all was a matter of extreme difficulty. Two such portions are figured at pages 247 and 256 of Mr. Lowell's volume. The Oasis The curious circular black spots which are seen at the intersections of many of the canals in which in some parts of the surface are very numerous are said to be more difficult of detection than even the lines being often blurred or rendered completely invisible by slight irregularities in our own atmosphere while the canals themselves continue visible. About 180 of these have now been found and the more prominent of them are estimated to vary from 75 to 100 miles in diameter. They are however many much smaller down to minute and barely visible black points. Yet they all seem a little larger than the canals which enter them where the canals are double the spots or Oasis as Mr. Lowell terms them lie between the two parallel canals. No one can read this book without admiration for the extreme perseverance and long continued and successful observation the results of which are here recorded and I myself except unreservedly the substantial accuracy of the whole series. It must however always be remembered the growth of knowledge of the detailed markings has been very gradual and that much of it has only been seen at a very rare and exceptional conditions. It is therefore quite possible if at some future time a further considerable advance in instrumental power should be made or a still more favorable locality be found the new discoveries might so modify present appearances as to render a satisfactory explanation of them more easy than it is at present. But though I wish to do the fullest justice to Mr. Lowell's technical skill and long years of varying work which have brought to light the most complex and remarkable appearances that any of the heavenly bodies present to us I'm obliged absolutely to part company with him as regards to the startling theory of artificial production which he thinks alone adequate to explain them. So much this is the case that the very phenomena which to him seem to demonstrate the intervention of intelligent beings working for the improvement of their own environment are those which seem to me to bear the unmistakable impress of being due to natural forces while they are wholly unintelligible as being useful works of art. I refer of course to the great system of what are termed canals with a single or double of these I shall give my own interpretation later on. Footnote 2 refers to man's place in the universe. Page 267 published in 1903 footnote 3 this is on the opposite side of Mars from that shown in the frontispiece this concludes chapter 2 chapter 3 of is Mars habitable this is a Liberbox recording all Liberbox recordings are in the public domain for more information if you volunteer please visit Liberbox.org is Mars habitable by Alfred Russell Wallace chapter 3 the climate and physiography of Mars Mr. Lowell admits and indeed urges strongly that there are no permanent bodies of water on Mars that the dark spaces and spots thought by the early observers to be sees are certainly not so now though they may have been at it earlier period the true clouds are rare even if they exist the appearances that have been taking for them being either dust storms or a surface haze that there is consequently no rain and that large portions about two-thirds of the planet's surface have all the characteristics of desert regions snow caps the only source of water the state of things is supposed to be ameliorated by the fact of the polar snows which in the winter cover the Arctic in about half of the temperate regions of each hemisphere alternately the maximum of the northern snow caps is reached for the period of the Martian winter corresponding to the end of February with us about the end of March the cap begins to shrink in size in the northern hemisphere and this goes on so rapidly that early in the June of Mars it is reduced to its minimum about the same time the changes of colors take place in the adjacent darker portions of the surface which become at first bluish and later a decided blue-green but by far the larger portion including almost all of the equatorial regions of the planet remain always of a reddish ochre tint see footnote 4 at the end of the chapter the rapid and comparatively early disappearance of the white covering is very reasonably supposed to prove that it is of small thickness corresponding perhaps to about a foot or two of snow in north tempered America and Europe and that by increasing the amount of sun heat it is converted partly into liquid and partly into vapor coincident with this disappearance and it's a presumed result of water or other liquid producing inundations the bluish-green tint which appears on the previously dark portion of the surface is supposed to be due to a rapid growth of vegetation but the evidence on this point does not seem to be clear or harmonious for the four colored plates showing the planet surface at successive martian dates from December 30th to February 21st not only is a considerable extent of the south tempered zone to change rapidly from bluish-green to chocolate brown and then again to bluish-green but that the portions furthest from the supposed fertilizing overflow are permanently green as are also considerable portions in the opposite or northern hemisphere which one would think would then be completely dried up no hills upon Mars the special point to which I here wish to call attention is this Mr. Lowell's main contention is that the surface of Mars is wonderfully smooth and level not only are there no mountains but there are no hills or valleys or plateau this assumption is absolutely essential to support the other great assumption that a wonderful network of perfectly straight lines over nearly the whole surface of the planet are irrigation canals it is not alleged that the irregularities or undulations of a few hundreds or even one or two thousands of feet could possibly be detected certainly all we know planetary formation or structure points strongly towards some inequalities of surface Mr. Lowell admits that the dark portions of the surface when examined on the terminator the margin of the illuminated portion do look like hollows and may be the beds dried up seas yet the supposed canals run across these old seabeds in perfect straight lines just as they do across the many thousands of miles that are admitted to be deserts which he describes in these forcible terms pitiless as our deserts are they are but faint forecasts that the state of things exist on Mars at the present time it appears then that Mr. Lowell has to face this dilemma only if the whole surface of Mars is an almost perfect level could the enormous network of straight canals each from hundreds to thousands of miles long have been possibly constructed by intelligent beings for purposes of irrigation but if a complete and universal level surface exists no such system would be necessary for on a level surface or on a surface slightly inclined from the poles toward the equator which would be advantageous in either case the melting water would of itself spread over the ground and naturally irrigate as much of the surface as it was possible for it to reach if the surface were not level but consisted of slight elevations and expressions to the extent of a few scores or a few hundreds of feet then there would be no possible advantage in cutting straight troughs through these elevations in various directions with water flowing at the bottom of them in neither case and in hardly any conceivable case could these perfectly straight canals cutting across each other in every direction and at very varying angles be of any use or be the work of an intelligent race if any such race could possibly be developed under the adverse conditions which exist on Mars the scanty water supply but further if there were any superfluity of water derived from the melting snow beyond what was sufficient to moisten the hollows indicated by the darker portions of the surface which at the time the water reaches and acquire a green tint of superfluity under the circumstances highly improbable that superfluity would be best utilized by widening however little the borders to which natural overflow had carried it any attempt to make that scanty surplus by means of overflowing canals travel across the equator into the opposite hemisphere through such a terrible desert region and exposed to such a cloudless sky as Mr. Lowell describes would be the work of a body of madmen rather than of intelligent beings it may be safely asserted that not one drop of water would escape evaporation or insoak at even a hundred miles from its source Seafoot note 5 at the end of the chapter Ms. Clerk on the scanty water supply On this point I'm supported by no less an authority than a historian of modern astronomy the late Ms. Agnes Clerk In the Edinburgh Review of October 1896 there is an article entitled New Views About Mars exhibiting the writer's characteristic fullness of knowledge and charm of style Speaking of Mr. Lowell's idea of the canals carrying the surplus water across the equator far into the opposite hemisphere for purposes of irrigation there which we see he again states in the present volume Ms. Clerk writes we can hardly imagine so shrewd a people as the irrigators of Tully and Hellas Seafoot note 6 wasting labour and the life-giving fluid after so unprofitable a fashion there is every reason to believe that the Martian snow caps are quite flimsy structures the material might be called snow soufflé since owing to the small power of gravity on Mars snow is almost three times lighter 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 callot 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 these two epochs in the southern hemisphere of Mars is 176 days the snow lies on the ground at the outside a couple of months that times it melts while it is still fresh fallen thus at the opposition of 1881 1882 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 9th and 10th 1890 proved that the southern callot may assume its definitive proportions in a single night no attempt has yet been made to estimate the quantity of water derivable from the melting of one of these formations yet the experiment is worth trying as a help toward defining ideas let us grant that the average depth of snow in them of the delicate Martian kind is 20 feet equivalent at the most to one foot of water the maximum area covered of 2,400,000 square miles is nearly equal to that of the United States while the whole globe of Mars measures 55,500,000 square miles of which one third of the present hypotheses is under cultivation and in need of water nearly the whole of the dark areas as we know are situated in the southern hemisphere of which they extend at the very least 17 million square miles that is to say they cover an area in round numbers seven times that of the snow cap only one seventh of a foot of water could possibly be made available for their fertilization supposing them to get the entire advantage of the spring fresh it upon a stint of less than two inches of water these fertile lands are expected to flourish and bear abundant crops and since they completely cover the entire area they are necessarily served first the great emissies for carrying off the surplus 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 a large portion of them must pass directly into vapor omitting the intermediate stage even with us a large portion of snow is removed airily 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. Loa's irrigation scheme but it enough has been said to show that it is hopelessly it will be seen that the writer of this article accepted the existence of water on Mars on the testimony of Sir W. Huggins which in view of later observations he has himself acknowledged to be valueless Dr. John Stonestone's proof of its absence derived from the molecular theory of gases had not then been made public description of some of the canals at the end of his volume Mr. Lowell gives a large chart of Mars on Mercator's projection showing the canals and other features in the opposition of 1905 this contains many canals not shown in the map here reproduced see the Francis Feast and some of the differences between the two are very puzzling looking at our map which shows the north polar snow below so that the south pole can view with the top of the map the central feature is the large spot Ascraeus Lucas from which 10 canals diverged centrally and four from the sides forming wide double canals 14 in all there is also a canal named Ulysses which here passes far to the right of the spot but in the large chart enters it centrally looking at our map showing downwards a little to the left the canal Eudon which runs through large dark area quite to the outer margin in the dark area however there is shown on the chart a spot Asperidon Lucas where five canals meet and if this is taken as the terminus the Eudon canal is almost exactly 2000 miles long and another on his right Eudon is the same length while is running on a slightly curved line to the large spot Lucas Castorius on the chart is still longer the Ulysses canal which on the chart runs straight from the point of the Mari Serenium to the Astraeus Lucas is about 2200 miles long others however are even longer as the Lowell says with them 2000 miles is common while many exceed 2500 and Humanities Orcus is 3540 miles from the point where it leaves Lucas Phoenicius to where it enters the Trivium Carontis this last canal is barely visible on our map its commencement being indicated by the word Humanities the Trivium Carontis is situated just beyond the right hand margin of our map its triangular dark area decides about 200 miles long and is shown on the chart as being the center from which radiate 13 canals another center is Aquae Calide situated at the point of a dark area running obliquely from 55 degrees to 35 degrees north latitude and is shown on a map of the opposite hemisphere to our map has nearly 20 canals radiating from it in almost every direction here at all events there seems to be no special connection with the polar snow caps and the radiating lines seem to have no intelligent purpose whatever what are such as might result from fractures in a glass globe produced by firing at it with very small shots one at a time taken the whole series of them Mr. Lowell very justly compares them to a network which triangulates the surface of the planet like a geodetic survey into polygons of all shapes and sizes at the very lowest estimate the total length of the canals observed and mapped by Mr. Lowell must be over 100,000 miles while he assures us that numbers of others have been seen over the whole surface but so faintly on such rare occasions as to elude all attempts to fix their position with certainty with these being of the same character and evidently forming part of the same system must also be artificial and thus we are led to a system of irrigation of almost unimaginable magnitude on a planet which has no mountains no rivers and no rain to support it whose whole water supply is derived from polar snows the amount of which is ludicrously inadequate to meet any such worldwide system while the low atmospheric pressure would lead to a rapid evaporation thus greatly diminishing this small amount of moisture that is available everyone must, I think, agree with Ms. Clerk that even admitting the assumption that the polar snows consist of frozen water the excessively scanty amount of water thus obtained would render any scheme of worldwide distribution of it hopelessly unworkable the very remarkable phenomena of the duplication of many of the lines together with the dark spots the so-called oases at their intersections are doubtless all connected in some unknown way with the constitution and past history of the planet but on the theory of the whole being works of art they certainly do not help to remove any of the difficulties that have been shown to attend the theory that the single lines represent artificial canals of irrigation with the strip of verge here on each side of them produced by their overflow Lowell on the purpose of the canals before leaving this subject it will be well to quote Mr. Lowell's own words as it is supposed perfectly level surface of Mars and his interpretation of the origin and purpose of the canals a body of planetary size if unrotating becomes a sphere except for solar tidal deformation if rotating it takes on a severoidal form exactly expressive so far as observation goes of the so-called centrifugal force at work Mars presents such a figure being flattened out to correspond to its axial rotation its surface therefore is in fluid equilibrium or in other words a particle of liquid at any point of its surface at the present time would stay where it was and it would not be sufficient to move elsewhere now the water which quickens the verge over the canals moves from the pole down to the equator as the season advances this it does then irrespective of gravity no natural force propels it and the inference is forthright inevitable that it is a part officially helped to its end there seems to be no escape from this deduction water only flows downhill and there is no such thing as a downhill on a surface which is already in fluid equilibrium a few canals might presumably be so situated that their flow could by inequality of terrain lie equatorward but not all now it is not in particular but by general consent that the canal system of Mars develops from pole to equator from the perspective times at which the minima take place it appears that the canal quickening occupies 52 days as evidenced by the excessive vegetal darkening to descend from latitude 72 degrees north to latitude 0 degrees a journey of 2,650 miles this gives for the water a speed of 51 miles a day or 2.1 miles an hour the rate of progression is remarkably uniform and this abets the deduction as to assisted transference but the fact is more unnatural yet the growth pays no regard to the equator but proceeds across it as if it did not exist into the planet's other hemisphere here is something even more telling than travel to this point for even if we suppose for the sake of argument that natural forces took the water down to the equator their action must there be certainly reversed and the equator proved a deadline to pass which were impossible pages 374-375 I think my readers would agree with me that this whole argument is one of the most curious ever put forth seriously by an imminent man of science because the polar compression of Mars is about what the calculation shows it ought to be in accordance with its rate of rotation its surface is in a state of fluid equilibrium and must therefore be absolutely level throughout but the polar compression of the earth equally agrees with this calculation and therefore its surface is also of fluid equilibrium therefore it also ought to be as perfectly level on land as it is on the ocean surface we know this is very far from being the case why must it be so in Mars are we to suppose Mars to have been formed in some totally different way from the other planets and that there neither is nor ever has been any reaction between its interior and exterior forces again the assumption of perfect flatness is directly opposed to all observation and all analogy with what we see on the earth and moon it gives no account whatever of the numerous and large dark patches once termed seas but bound not to be so and to be full of detailed markings and very depths of shadow to suppose that these are all the same dead level as the light colored portions are assumed to be implies that the darkness is of one material and color only not only of diversified contour which again is contrary to experience since difference of material with us always leads to differences in rates of degradation and hence of diversified contour as these dark spaces actually show themselves on their favorable conditions to independent observers lowl on the system of canals as a whole we will now see what Mr. Lowell claims the plain heating of the canals as a whole but last and all embracing in its import is the system which the canals form instead of running at haphazard the canals are interconnected in the most remarkable manner they seek centers instead of avoiding them the centers are linked thus perfectly with one another an arrangement which could not result from centers whether of explosion or otherwise which were themselves discreet furthermore the system covers the whole surface of the planet dark areas and light ones alike a worldwide distribution which exceeds the bounds of natural possibility any force which could act longitudinally on such a scale must be limited latitudinally in its action as witness the belts of Jupiter and the spots upon the sun rotational, climactic other physical cause could not fail of zonal expression yet these lines are grandly indifferent to such competing influences finally the system after meshing the surface in its entirety runs straight into the polar caps it is then a system whose end and aim is the tapping of the snow cap for the water there semi-annually let loose then to distribute it over the planet's base 373 here again we have curiously weak argument to due to support of you that these numerous straight lines imply works of art rather than of nature especially in the comparisons made with the belts of Jupiter and the spots on the sun both purely atmospheric phenomena where as the lines on Mars or on the solid surface of the planet why should there be any resemblance between them every fact stated in the above quotation always keeping in mind the physical conditions of the planet its very tenuous atmosphere and rainless desert surface seem wholly in favor of a purely natural as opposed to artificial origin and at the close of this discussion I suggest one which seems to be at least possible and to explain the whole series of the phenomena set forth and largely discovered by Mr. Lowell in a simpler and more probable manner than does his tremendous assumption of their being's works of art readers who may not possess Mr. Lowell's volume will find most of his most recent maps of the canals reproduced in nature of October 11th 1906 footnote 4 in 1898 Mount Wilson, California Mr. W. H. Pickering's photographs of Mars on April 9th showed the southern polar cap of modern dimensions with a large dim adjacent area 24 hours later a corresponding plate showed the same area brilliantly white this result apparently of a great Martian snowfall in 1882 the same observer witnessed the steady disappearance of 1,600,000 square miles of the southern snow cap an area nearly one-third of that hemisphere of the planet footnote 5 what the evaporation is likely to be in Mars may be estimated by the fact stated by Professor J. W. Gregory in his recent volume on Australia in Stanford's Compendium that in northwest Victoria evaporation is at the rate of 10 feet per annum while in central Australia it is very much more the greatly diminished atmospheric pressure in Mars will probably more than balance the loss of sun-heat in producing rapid evaporation footnote 6 areas on Mars so named this is the end of Chapter 3 Chapter 4 of Is Mars Habitable this is a LibriVox recording all LibriVox recordings are in the public domain for more information or to volunteer visit LibriVox.org Is Mars Habitable by Alfred Russell Wallace Chapter 4 Is Animal Life Possible on Mars having now shown that even admitting the accuracy of all Mr. Leville's observations and provisionally accepting all his chief conclusions as to the climate the nature of the snow caps the vegetation and the animal life yet his interpretation of the lines on its surface as being veritably canals constructed by intelligent beings for the special purpose of carrying water to the more arid regions is wholly erroneous and rationally inconceivable I now proceed to discuss his more fundamental position as to the actual habitability of Mars by a highly organized and intellectual race of material organic beings water and air essential to life Here fortunately the issue is rendered very simple because Mr. Leville fully recognizes the identity of the Constitution of Matter and of physical laws throughout the solar system and that for any high form of organic life certain conditions with absolutely essential on our earth must also exist in Mars He admits for an example that it is essential that an atmosphere containing oxygen nitrogen and aqueous vapor and carbonic acid as gas is essential and that an abundant vegetation is essential and these of course involve a surface temperature through a considerable portion of the year that renders the existence of these especially of water possible and available for the purpose of a high animal life blue color the only evidence of water in attempting to show that these essentials actually exist on Mars he is not very successful he induces evidence of an atmosphere but of an exceedingly scanty one since the greatest amount he can give to it is not more than about 4 inches of barometric pressure as we reckon it see footnote 7 assumes as he is a fair right to do till this proved that it consists of oxygen and nitrogen with carbon dioxide and water vapor in approximately the same proportions as with us with regard to the last item the water vapor there are however many serious difficulties the water vapor of our atmospheres derive from the enormous area of our seas oceans, lakes and rivers as well as from the evaporation from heated lands and tropical forests of much of the moisture produced by frequent and abundant rains all these sources of supply are admittedly absent from Mars which is no permanent bodies of water no rain and tropical regions which are almost entirely desert many writers have therefore doubted the existence of water in any form upon the planet supposing the snow caps are not formed of frozen water but of carbon dioxide or some other heavy gas in a frozen state and Mr. Lowell evidently feels as to be a difficulty since the only fact he is able to reduce in favour of the melting snows of the polar caps and producing water is that at the time they are melting a marginal blue band appears which accompanies them in their retreat and this blue colour is said to prove conclusively that the liquid is not carbonic acid but water this point he dwells upon repeatedly stating on the blue borders this excludes the possibility of their being formed by carbon dioxide and shows that of all the substances we know the material composing them must be water this is the only proof of the existence of water he adduces it is certainly a most extraordinary and futile one for it is perfectly well known that of the water in large masses and by transmitted light is of a blue colour yet shallow water by reflected light is not so and in the case of the liquid produced by the snow caps of Mars which the whole conditions of the planet must show to be shallow and also be more or less turban it cannot possibly be the cause of the deep blue tint said to be the result from the melting of the snow but there is a very weighty argument depending on the molecular theory of gases against the polar caps of Mars being composed of frozen water at all the mass and elastic force of the several gases is due to the greater or less propidity of the vibratory motion of their molecules under identical conditions the speed of these molecular motions has been ascertained for all of the chief gases and it is found to be so great as in certain cases to enable them to overcome the force of gravity and escape from a planet surface into space Dr. G. John Stoney has specially investigated this subject and he finds that the force of gravity on the earth is sufficient to retain all the gases that are opposing its atmosphere but not sufficient to retain hydrogen and as a consequence although this is a gas produced in small quantities by volcanoes and by decomposing vegetation yet no trace of it is found in our atmosphere the moon however, having only one eightieth the mass of the earth cannot retain any gas hence its airless and waterless condition water vapor cannot exist on Mars now Dr. Stoney finds it in order to retain water vapor permanently a planet must have a mass of at least a quarter that of the earth but the mass of Mars is only one ninth that of the earth therefore unless there are some special conditions that prevent its loss this gas cannot be present in the atmosphere Mr. Lowell does not refer to this argument in Mr. Lowell's view neither does he claim the evidence of spectroscopy in his favor this was alleged more than 30 years ago to show the existence of water vapor in the atmosphere of Mars but of late years it has been doubted Mr. Lowell was complete silence on the subject while laying stress on such a very weak and inconclusive argument as that from the tinge of color that is observed from a little distance from the edge of the diminishing snow caps he himself does not think the fact to be thus proved if he did he would hardly do such an argument for its presence as the following the melting of the caps on the one hand and the reforming on the other affirmed the presence of water vapor in the Martian atmosphere of whatever else that air consists, page 162 yet absolutely the only proof he gives that the caps are frozen water is the almost frivolous color argument above referred to no spectroscopic evidence of water vapor as Sir William Huggins is a chief authority quoted for this fact and is referred to as being almost conclusive in the third edition of Miss Clerk's History of Astronomy in 1893 I have ascertained that his opinion at the present time is that there is no conclusive proof of the evidence of water vapor in the atmosphere of Mars and that observations at the Lick Observatory in 1895 where the conditions and instruments are of the highest order were negative he also informs me that Marschandt at the Peter Media Observatory was unable to obtain lines of water vapor in the spectrum of Mars and that in 1905 Slipper at Mr. Lowell's Observatory was unable to detect any indications of water vapor in the spectrum of Mars it thus appears that spectroscopic observations are quite according to the calculations founded on the molecular theory of gases as to the absence of aqueous vapor and therefore presumably of liquid water from Mars it is true that the spectroscopic argument is purely negative and may be due to the extreme delicacy of the observations required but that dependent on the inability of the force of gravity to retain its positive scientific evidence against its presence and till shown to be erroneous must be held to be conclusive this absence of water is of itself conclusive against the existence of animal life unless we enter into the regions of pure conjecture as to the possibility of some other liquid being able to take its place and that liquid being is on the present there as water is here Mr. Lowell however never takes this ground that bases his whole theory on the fundamental identity of the substance of the bodies of living organisms wherever they may exist in the solar system in the next two chapters I shall discuss an equally essential condition that of temperature which reports a still more conclusive and even crushing argument against the suitability of Mars for the existence of organic life put note 7 in a paper written since the book appeared the density of air at the surface of Mars is said to be one-twelfth of the earth this concludes Chapter 4 Chapter 5 of Is Mars Habitable This is a LibriVox recording All LibriVox recordings are in the public domain For more information or to volunteer please visit LibriVox.org Is Mars Habitable by Albert Russell Wallace Chapter 5 The Temperature of Mars Mr. Lowell's Estimate We have now to consider a still more important and fundamental question and one which Mr. Lowell does not grapple with in this volume the actual temperature on Mars due to its distance from the Sun and the atmospheric conditions on which he himself lays so much stress If I am not greatly mistaken we shall arrive at conclusions on the subject which are absolutely fatal to the conception of any high form of organic life being possible on this planet the problem of terrestrial temperatures in order that the problem may be understood and its importance appreciated it is necessary to explain the now generally accepted principles as to the causes which determine the temperatures on our Earth and presumably on all the other planets whose conditions are not wholly unlike ours The fact of the internal heat of the Earth which becomes very perceptible even at the moderate depths reached in mines and deep moorings and at the deepest mine becomes a positive inconvenience needs many people to suppose that the surface temperatures of the Earth are partly due to this cause but is now generally admitted that this is not the case the reason being that all the rocks and soils in their natural compacted state are exceedingly bad conductors of heat A striking illustration of this is the fact that a stream of lava often continues to be red hot at a few feet depth for years after the surface is consolidated and is hardly any warmer than a man A still more remarkable case is that of a glacier on the southeast side of the highest cone of Etna underneath a lava stream with an intervening bed of volcanic sand only 10 feet thick This was visited by Charles Lyell in 1828 and his second time 30 years later when he had made a very careful examination of the strata and was quite satisfied that the sand and the lava stream had actually preserved this massive ice which neither the heat of the lava at its first outflow nor the continued heat rising from the great volcano below it had been able to melt it or perceptively to diminish it in 30 years Another fact that points in the same direction is the existence over the whole floor of the deepest oceans of ice cold water which originating in the polar seas owing to its greater density creeps slowly along the ocean bottom to the depths of the Atlantic and Pacific it is not perceptively worn by the internal heat of the earth Now the solid crust of the earth is estimated as at least about 20 miles in average thickness and keeping in mind that the other facts just referred to we can understand that the heat from the interior passes through it with such extreme slowness as not to be detected at the surface the varying temperatures of which are due entirely to solar heat A large portion of this heat is stored up in the surface soil and especially in the surface layer of the oceans and seas thus partly equalizing the temperatures of day and night, winter and summer it was greatly to ameliorate the rapid changes of temperature than would otherwise occur our dense atmosphere is also of immense advantage to us as an equalizer of temperature charged as it almost always is with a large quantity of water vapor this latter gas when not condensed into cloud allows the solar heat to pass freely to the earth but it has a singular and highly beneficial property of absorbing and retaining the dark or lower grade heat given off by the earth which would otherwise radiate into space much more rapidly and was therefore always remember that very nearly if not quite the whole of the warm we experience on the earth is derived from the sun See footnote 8 at the end of the chapter in order to understand the immense significance of this conclusion we must know what is meant by the whole heat or warm as unless we know this we cannot define what half any other proportion of the sun heat really means now I feel pretty sure that 9 out of 10 of the average educated public would answer the following question incorrectly the mean temperature of the southern half of England is about 48 degrees Fahrenheit supposing the earth received only half the sun heat it now receives what would then be the probable mean temperature of the south of England the majority would I think answer it once about 24 degrees Fahrenheit nearly as many would perhaps say 48 degrees Fahrenheit is 16 degrees above the freezing point therefore half the heat received would bring us down to 8 degrees above the freezing point or 40 degrees Fahrenheit very few I think would realize that our share of the half of the amount of the sun heat received by the earth would probably result in reducing our mean temperature to about 100 degrees Fahrenheit below the freezing point and perhaps even lower this is about the very lowest temperature ever experienced on the earth's surface you understand how such results are obtained a few words must be said about the absolute zero of temperature the zero of temperature heat is now believed to be entirely due to ether vibration which produces a correspondingly rapid vibration of the molecules of matter causing it to expand and producing all the phenomena we term heat we can conceive this vibration to increase indefinitely and thus it would appear to be no necessary limit to the amount of heat possible but we cannot conceive it to decrease definitely the same uniform rate as if at soon inevitably come to nothing now it has been found by experiment that gases under uniform pressure expand 1 273 of their volume for each degree centigrade of increased temperature so that in passing from zero degree centigrade to 273 degree centigrade they are doubled in volume they also decrease in volume at the same rate for each degree below zero degree centigrade the freezing point of water hence it goes on to minus 273 degrees centigrade a gas will have no volume or will undergo some change of nature hence this is called the zero of temperature or the temperature to which any matter pulse which receives no heat from any other matter it is also sometimes called the temperature of space or of the ether in a state of rest if that is possible all the gases have been proved to become first liquid and then most of them solid at temperatures considerably above the zero the only way to compare the proportional temperatures of bodies whether in the earth or in space is therefore by means of a scale beginning at this natural zero instead of those scales founded in the artificial zero of the freezing point of water or as in Fahrenheit 32 degrees below it only by using the natural zero and measuring continuously from it can we estimate temperatures and relative proportion to the amount of the heat received this is termed the absolute zero and so that we can start reckoning from that point it does not matter whether the scale adopted is the or that of Fahrenheit the complex problem of planetary temperatures now if as is with the case with Mars a planet receives only half the amount of solar heat that we receive going to its greater distance from the sun and if the mean temperature of our earth is 60 degrees Fahrenheit this is equal to 551 degrees Fahrenheit on the absolute scale it would therefore appear very simple to have this amount and obtain 275 0.5 degrees Fahrenheit as the mean temperature of that planet but this result is erroneous because the actual amount of sun heat intercepted by a planet is only one condition out of many that determine its resulting temperature radiation that is loss of heat is going on concurrently with gain and the rate of loss varies with the temperature according to a law recently discovered the loss being much greater at high temperatures in proportion to the fourth power of the absolute temperature then again the whole heat intercepted by a planet does not reach its surface unless it has no atmosphere when it has one much is reflected or absorbed according to complex laws dependent on the density and the composition of the atmosphere then again the heat that reaches the actual surface is partly reflected and partly absorbed according to the nature of that surface land or water, desert or forest or snow clad that part which is absorbed being the chief agent in raising the temperature of the surface and of the air in contact with it very important too is the loss of heat by radiation from these various heated surfaces at different rates while the atmosphere itself sends back to the surface an ever very important of both this radiant and reflected heat according to distinct laws further difficulties arise from the fact that much of the sun's heat consists of dark or invisible rays then it cannot therefore be measured by the quantity of light only for this rough statement it will be seen that the problem is an exceedingly complex one not to be decided offhand by any simple method it has in fact been usually considered as strictly speaking insoluble and only to be estimated by a more or less rough approximation or by the method of a general analogy from certain known facts it will be seen from what has been said in previous chapters that Mr. Lowell in his book has used the latter method and by taking the presence of water and water vapor and Mars proved by the behavior of the snow caps under the blueish color that results from their melting has deduced a temperature above the freezing point of water as prevalent in the equatorial regions permanently and in a temperate and Arctic zones during a portion of each year Mr. Lowell's mathematical investigation of the problem but as this result has been beheld to be both improbable in itself and founded on no valid evidence he is now with the London Edinburgh and Dublin Philosophical Magazine of July 1907 published in an elaborate paper of 15 pages entitled a general method for evaluating planets with special reference to the temperature of Mars by Professor Percival Lowell and in this paper by what purports to be strict mathematical reasoning based on the most recent discoveries as to the laws of heat as well as on measurements or estimates of the various elements and constants used in the calculations he arrives at a conclusion strikingly according with what I put forward in the recently published volume having myself neither mathematical nor physical knowledge sufficient to enable me to criticize this elaborate paper except on a few points I will here limit myself to giving a short account of it so as to explain its method of procedure after which I may add a few notes on what seem to be doubtful points while I also hope to be able to give the opinions of some more competent critics than myself Mr. Lowell's mode of estimating the surface temperature of Mars the author first states that Professor Young in his general astronomy of 1898 makes the mean temperature of Mars 223.6 degrees absolute by using Newton's law of heat being radiated in proportion to temperature and 363 degrees absolute which is equivalent to minus 96 degrees Fahrenheit by Du Long and Pettit's law but adds that a closer determination has been made by Professor Moulton using Steppen's law that radiation is as the fourth power of the temperature whence results a mean temperature of minus 31 degrees Fahrenheit these estimates assume identity of atmospheric conditions of Mars and the Earth whereas none of these estimates take account of the many complex factors which interfere with such direct and simple calculations Mr. Lowell then proceeds to enunciate them and to work out mathematically the effects they produce number one the whole radiant energy of the Sun on striking a planet becomes divided as follows part is reflected back into space part absorbed by the atmosphere transmitted to the surface of the planet the surface again reflects a portion and only the balance goes left to warm the planet number two to solve this complex problem we are all helped by the albedos or intrinsic brilliancy at the planets which depend on the proportion of the visible rays which are reflected and which determines the comparative brightness of the respective surfaces we also have to find the ratio of the invisible to the visible rays and the heating power of each number three he then refers to the actinometer and pyro heliometer instruments for measuring the actual heat derived from the Sun and also the bellometer an instrument invented by Professor Langley for measuring the invisible heat rays which he has proved to extend more than three times the length of the whole heat spectrum is previously known and is also shown that the invisible rays contribute 68% of the Sun's total energy see footnote nine at the end of the chapter four there then follows an elaborate estimate of the loss of heat during the passage of the Sun's rays through our atmosphere from experiments made at different altitudes and from the estimated reflective power of the various parts of the Earth's surface rocks and soil, ocean, forest and snow the final result being the three pulse of the whole Sun's heat is reflected back into space forming our albedo only one force is absorbed by the soil and goes to warm the air and determine our mean temperature five we now have another elaborate estimate of the comparative amounts of heat actually received by Mars and the Earth there are very different amounts of atmosphere and this estimate depends almost wholly on the comparative albedos that Mars is observed by astronomers being 0.27 while ours has been estimated in a totally different way as being 0.75 whence he concludes that nearly three-fourths of the Sun's heat that Mars receives reaches the surface and determines its temperature while we get only one fourth of our total amount then by applying Steppen's law that the radiation is as the fourth power of the surface temperature he reaches the final result that the actual heating power at the surface of Mars is considerably more than on the Earth that would produce a mean temperature of 72 degrees Fahrenheit if it were not for the greater conservative or blanketing power of our denser and more water-laden atmosphere the difference produced by this latter fact is that it minimizes by dwelling on the probability of a greater proportion of carbonic acid gas and water vapor in the Martian atmosphere and thus brings down the mean temperature of Mars to 48 degrees Fahrenheit which is almost exactly the same as that of the southern half of England he is also, as a result of observations reduced the probable density of the atmosphere of Mars to two and a half inches of mercury or only one twelfth of that of the Earth critical remarks on Mr. Lowell's paper the last part of this paper indicated under parts 4 and 5 is the most elaborate occupying 8 pages and it contains much that seems uncertain if not erroneous in particular it seems very unlikely that under a clear sky over the whole Earth we should only receive at the sea level of 0.23 of the solar rays which the Earth intercepts in 167 these data largely depend on observations made in California and other parts of the southern United States where the lower part of the atmosphere is exceptionally thus laden till we have similar observations made in the tropical forest regions which cover so large an area where the atmosphere is purified by frequent rains it also won the prairies and the great oceans we cannot trust these very local observations for general conclusions affecting the whole Earth later in the same article page 170 Mr. Lowell says clouds transmit approximately 20% of the heat reaching them a clear sky at sea level 60% as the sky is half the time cloudy the mean transmission is 35% his statements seem incompatible with that quoted above the figure he uses in his calculations the actual albedo of the Earth 0.75 is not only improbable but almost self-contradictory because the albedo of cloud is 0.72 the data the great cloud covered planet Jupiter is given by Lowell is 0.75 while Zoner made it only 0.62 again Lowell gives Venus an albedo of 0.92 while Zoner made it only 0.50 and is the core 0.65 it shows the extreme uncertainty of these estimates while the fact that both Venus and Jupiter are wholly cloud covered although you are only half covered renders it almost certain that our albedo is far less than Mr. Lowell makes it it is evident that mathematical calculations found upon such uncertain data cannot yield trustworthy results but this by no means is the only case in which the data employed on this paper are of uncertain value everywhere we meet with figures of somewhat doubtful accuracy here we have somebody's estimate quoted there is another person's observation and they are adopted without further remark than using various calculations leading to the result above quoted it requires a practice mathematician and one fully acquainted with literature of this subject to examine these various data and track them through the maze of formula and figures so as to determine to what extent they affect the final result there is however one curious oversight which I must refer to as it is a point to which I have given much attention not only to soccer Lowell assume as in his book that the snows of Mars consist of frozen water or is water on the surface and water vapor in its atmosphere not only does he ignore altogether Dr. Johnston Stoney's calculations with regard to what I have referred to but he uses terms that imply that water vapor is one of the heavier components of our atmosphere the passage is at page 168 of the philosophical magazine after stating that owing to the very small barometric pressure in Mars water would boil at 110 degrees Fahrenheit he adds the sublimation at lower temperatures would be correspondingly increased consequently the amount of water vapor in the Martian air must on that score be relatively greater than our own then follows this remarkable passage carbon dioxide because of its greater specific gravity would also be in relatively greater amount so far as this cause is considered part Catererus perivus with its lighter gases the quickest when this regards both water vapor and carbon dioxide we have reason to think them in relatively greater quantity than in our own air at corresponding better measured pressure I cannot understand this passage except as implying that water vapor and carbon dioxide are among the heavier and not among the lighter gases of the atmosphere those which the planet parts with quickest but this is just what water vapor is being a little less than two-thirds of the weight of air 0.6225 and one of those which is planted would part with quickest and which according to Dr. John Stone-Stoney it loses altogether put note 8 Professor J. H. Pointing in his lecture to the British Association at Gainbridge in 1904 says the surface of the sun receives we know an amount of heat from the inside almost infinitesimal compared with that which it receives from the sun and on the sun therefore we depend for our temperature footnote 9 for a short account of this remarkable instrument see My Wonderful Century New Edition pages 143 to 145 note on Professor Lowell's article in the Philosophical Magazine by J. H. Pointing fellow of the Royal Society Professor of Physics at the University of Birmingham I think Professor Lowell's results are demerroneous which neglected the heat stored in the air by its absorption of radiation both from the sun and from its surface the air thus heated radiates to the surface and keeps up the temperature I have sent to the Philosophical Magazine a paper in which I think it is shown that when the radiation by the atmosphere is taken into account the results are entirely changed the temperature of Mars with Professor Lowell's data still comes out far below the freezing point still further below than the increased distance alone would make it indeed the lower temperature on elevated regions of the Earth's surface I think it is impossible to raise the temperature of Mars to anything like the value obtained by Professor Lowell unless we assume some quality in his atmosphere entirely different from any found in our own atmosphere J. H. Pointing October 19th 1907 This is the end of Chapter 5