: Is Mars habitable? A critical examination of Professor Percival Lowell's book Mars and its canals with an alternative explanation by Wallace Alfred Russel - Lowell Percival 1855-1916. Mars and its canals; Mars (Planet)

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EARLY OBSERVERS OF MARS, --Mars the only planet the surface of which is distinctly visible --Early observation of the snow-caps and seas --The 'canals' seen by Schiaparelli in 1877 --Double canals first seen in 1881 --Round spots at intersection of canals seen by Pickering in 1892 --Confirmed by Lowell in 1894 --Changes of colour seen in 1892 and 1894 --Existence of seas doubted by Pickering and Barnard in 1894.

MR. LOWELL'S DISCOVERIES AND THEORIES, --Observatory at Flagstaff, Arizona --Illustrated book on his observations of Mars --Volume on Mars and its canals, 1906 --Non-natural features --The canals as irrigation works of an intelligent race --A challenge to the thinking world --The canals as described and mapped by Mr. Lowell --The double canals --Dimensions of the canals --They cross the supposed seas --Circular black spots termed oases --An interesting volume.

THE CLIMATE AND PHYSIOGRAPHY OF MARS, --No permanent water on Mars --Rarely any clouds and no rain --Snow-caps the only source of water --No mountains, hills, or valleys on Mars --Two-thirds of the surface a desert --Water from the snow-caps too scanty to supply the canals --Miss Clerke's views as to the water-supply --Description of some of the chief canals --Mr. Lowell on the purpose of the canals --Remarks on the same --Mr. Lowell on relation of canals to oases and snow-caps --Critical remarks on the same.

IS ANIMAL LIFE POSSIBLE ON MARS? --Water and air essential for animal life --Atmosphere of Mars assumed to be like ours --Blue tint near melting snow the only evidence of water --Fallacy of this argument --Dr. Johnstone Stoney's proof that water-vapour cannot exist on Mars --Spectroscope gives no evidence of water.

TEMPERATURE OF MARS--MR. LOWELL'S ESTIMATE, --Problem of terrestrial temperature --Ice under recent lava --Tropical oceans ice-cold at bottom --Earth's surface-heat all from the sun --Absolute zero of temperature --Complex problem of planetary temperatures --Mr. Lowell's investigation of the problem --Abstract of Mr. Lowell's paper --Critical remarks on Mr. Lowell's paper.

A NEW ESTIMATE OF THE TEMPERATURE OF MARS, --Langley's determination of lunar heat --Rapid loss of heat by radiation on the earth --Rapid loss of heat on moon during eclipse --Sir George Darwin's theory of the moon's origin --Very's researches on the moon's temperature --Application of these results to the case of Mars --Cause of great difference of temperatures of earth and moon --Special features of Mars influencing its temperature --Further criticism of Mr. Lowell's article --Very low temperature of arctic regions on Mars.

A SUGGESTION AS TO THE 'CANALS' OF MARS, --Special features of the canals --Mr. Pickering's suggested explanation --The meteoritic hypotheses of origin of planets --Probable mode of origin of Mars --Structural straight lines on the earth --Probable origin of the surface-features of Mars --Symmetry of basaltic columns --How this applies to Mars --Suggested explanation of the oases --Probable function of the great fissures --Suggested origin of blue patches adjacent to snow-caps --The double canals --Concluding remarks on the canals.

PAGE SUMMARY AND CONCLUSION, --The canals the origin of Mr. Lowell's theory --Best explained as natural features --Evaporation difficulty not met by Mr. Lowell --How did Martians live without the canals --Radiation due to scanty atmosphere not taken account of --Three independent proofs of low temperature and uninhabitability of Mars --Conclusion.

EARLY OBSERVERS OF MARS.

Few persons except astronomers fully realise 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 we could see it in the other planets. Of Venus we probably see only the upper surface of its cloudy atmosphere. 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 surfaces, and a somewhat similar condition seems to prevail in the far more remote planets Uranus and Neptune. It has thus happened, that, although as telescopic objects of interest and beauty, the marvellous 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 when examined with the powerful instruments of the nineteenth century have 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, but they were first proved to increase and decrease alternately, in the summer and winter of each hemisphere, by Sir William Herschell in the latter part of the eighteenth century. This fact gave the impulse to that idea of similarity in the conditions of Mars and the earth, which the recognition of many large dusky patches and streaks as water, and the more ruddy and brighter portions as 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 but of nearly double 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 some day obtain evidence of the fact.

In 1881 another strange feature was discovered by Schiaparelli, who found that about twenty canals which had previously been seen single were now distinctly double, that is, that they consisted of two parallel lines, equally distinct and either very close together or a considerable distance apart. This curious appearance was at first thought to be due to some instrumental defect or optical illusion; but as it was soon confirmed by other observers with the best instruments and in widely different localities it became in time accepted as a real phenomenon of the planet's surface.

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