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are fighting a losing battle, against the gradual desiccation of their planet, by means of a Titanic system of irrigation.
What has been the reason which has induced Mr Lowell to put forward an idea so little in accordance with the conclusions of astronomers in general? It is this. Just as he sees the «canals», so he fails to detect in them any evidence of detail or irregularity. They appear to him like pen-and-ink lines drawn with a ruler. The question between him and his critics is not, and has never been, a question as to the existence of certain apparently straight, narrow streaks on Mars. There are indeed a number of discrepancies between different observers to be readily explained by differences of eyesight, atmospheric conditions, telescopic power, and the like, but there is good substantial agreement as to the main details.
But what Mr Lowell contends is this: that the perfect regularity of form and position which he gives to the «canals» in his representations of the planet, proves that they are artificial objects — they are too regular to be natural — his assumption being that no improvement in telescopes, no increase in experience, no better eyesight, will ever break up that regularity into finer and more complex detail, but that it represents Mars as we should see it, if we were close to the planet itself.
But the history of our knowledge of the planet’s surface teaches us a very different lesson. If we turn to the drawings made by Beer and Mädler in 1830, two small objects, exceedingly like one another, appear repeatedly. These are two dark circular spots; the one isolated, the other at the end of a gently curved line. Both spots recall the «oases» of Mr Lowell, and the curved line at the termination of which one of the spots appears, represents closely the appearance presented in recent observations by several of the «canals». There can be no doubt that in the year 1830, no better drawings of Mars had appeared and that in representing these two spots as truly circular, and the curved line as narrow, sharp and uniform, Beer and Mädler pourtrayed the planet as they actually saw it. The one marking we call to-day the Lacus Soils, the other, the Sinus Sabaeus, and we can trace the gradual growth of our knowledge of both markings from 1830 up to the present time. These two re-