"Professor Campbell has, however, made similar experiments, and is of opinion that Professor Lowell has been deceived by the water vapour in our own atmosphere. Thus the matter stands at the present time, and we must await the result of further investigation before we can consider the matter settled. "I, however, regard it as a certainty that improved means will definitely show that water vapour undoubtedly exists in the Martian atmosphere, and it is not unlikely that other constituents of that atmosphere may also be identified, and possibly even the relative quantities may be ascertained." John here remarked that he had read of it being contended that life could not exist on Mars because as water would boil at a temperature a hundred degrees lower than it did on the earth, it would be impossible to boil a potato properly, or make a good cup of tea. He thought, however, that if water boiled at such a low temperature, then the proportion of water vapour in the air would be increased, as evaporation would be more rapid than on the earth. "Undoubtedly so," I replied. "The first argument, however, is very weak. For many thousands of years the people on the earth not only managed to live, but attained a high state of civilisation, yet we have no reason to believe that they ever ate potatoes or drank tea! Even in England we have only known and used these articles for about three hundred years! The inhabitants of any world would be suited to their environments. "The polar-caps on Mars are shown on very early drawings of the planet; but, up to the year 1877, little was known of the general surface details beyond the fact that the general colour was orange-red, diversified by dark patches of blue-green in some parts, and some narrow, serpentine markings here and there. All these markings are now much more accurately drawn, as the result of more careful and continuous observation. Sir William Herschel suggested that the red colour was attributable to the vegetation of Mars being red, instead of green as on our earth; but it was generally considered that the red areas indicated land and the dark areas water. The work of our modern observers has, however, resulted in a general revision of our ideas on these points. "It had long been reasoned that, as the earth was accompanied by a moon, and Jupiter had at least four, Mars, the intermediate planet, might be expected to possess a satellite. The planet itself being small, its moon would probably be very small, and likely to be overlooked when observing with the telescope, because its light would be overpowered by the light of the planet, which would make the telescopic field of view very bright. Up to the year 1877 the most powerful instruments had been used without success in the search for the supposed satellite.