Mr. Denning, in the "Astronomische Nachrichten," No. 3926, gives the result of his observations on Mars in 1903. He says the canals, without doubt, are objective features; changes in the appearance of these markings he attributes to vaporous condensations. One rotation period of the planet satisfies the observation of all the markings, thus proving them to be definite features of the planet's surface rather than drifting vapors such as are seen when observing Jupiter and Saturn. In spite of these admissions Mr. Denning, in 1905, while repeating his convictions as to the objectivity of the canals, denied their sharp outline. Of the ten canals he drew, eight were discovered by Schiaparelli, and two were discovered by Lowell. Denning observed these lines with a ten inch reflector. Schiaparelli compared them in sharpness to lines of a steel engraving. It rests with the reader to judge who is most likely to be correct in his description of the character of the lines​—​Mr. Denning with a ten inch reflector, in a poor atmosphere, or Schiaparelli and Lowell, with a twenty-six and a twenty-four inch refractor, respectively, in a far superior atmosphere.

Among the many who have seen and drawn the canals comes first, of course, Professor Schiaparelli, the discoverer of them. It is only necessary to state here that he first detected these enigmatical markings, which he named canali, in 1877. In the opposition of 1879, he not only confirmed the discoveries of 1877, but added new canali, and for the first time saw the curious process of doubling, or gemination.

Astronomers in various parts of the world searched in vain for these markings, and despite the exalted character and remarkable work of the distinguished Italian in other lines of astronomic research, it was feared that, in this instance, Schiaparelli had been the victim of an hallucination. It is true that from the time of Huyghens, in 1659, a few astronomers, such as Secchi, Schroeter, Kaiser, and Dawes, have detected and drawn a few faint lines which seemed to be identical with the canali of Schiaparelli. It was not until 1886, however, that Perrotin and Thollon with a twenty-nine inch refractor of the Nice Observatory, first began to confirm the discoveries of Schiaparelli, and since that time observers in various parts of the world have detected and drawn these remarkable lines. The cumulative testimony of these men as to the veritable existence of these markings cannot be set aside.

It seems strange that nine years should elapse before an astronomer with an interest in the subject, coupled with an acute vision and the patience to observe assiduously, should arise to confirm the existence of these markings, but in another chapter I have called attention to the little interest astronomers have manifested in planetary markings of any kind. It has been shown elsewhere that acute vision, with a clear and, above all, a steady atmosphere, are the chief essentials in making out the markings. It is curious to note the attitude of some astronomers, who, having seen the canals and even drawn them, denied their veritability. Their explanations cover "illusions due to the property of light itself, the inability of the eye to maintain its mechanism of accommodation, the behavior of air waves, temporary alteration of the focus of the eye, undetected astigmatism," etc., etc. But, to return to the astronomers who have drawn them. On the unfavorable opposition of 1888, Schiaparelli declares that "the canali had all the distinctness of an engraving on steel, with the magical beauty of a colored engraving." He furthermore says: "As far as we have been able to observe them hitherto, they are certainly fixed configurations upon the planet, the Nilosyrtis has been seen in that place for nearly one hundred years and some of the others for at least thirty years."

In this connection it is interesting to quote from Schiaparelli who, until many years after he discovered the canals of Mars, had no doubt of their natural origin. As late as 1893, he still considered them natural. In speaking of the canals, he says: "It is not necessary to suppose here the work of intelligent beings; and in spite of the almost geometric appearance of their whole system, for the present we incline to believe that they are product of the evolution of a planet, much as on the Earth is the English Channel, or the Channel of Mozambique." This extract may be found in a memoir in "Natura ed Arte," 1893, page 22. On page 24 of the same memoir Schiaparelli illustrates the elasticity of his mind and a thoroughly unprejudiced attitude by saying: "Their singular aspect, and the fact that they are drawn with absolute geometric precision, as if they were the product of rule and compass, have induced some people to see in them the work of intelligent beings, inhabitants of the planet. I should be very careful not to combat this supposition, which involves no impossibility." (The italics are ours.) His comparison of the Martian lines with the English Channel and the Channel of Mozambique, if he means any resemblance in form and not in the manner of formation, is most unfortunate, for on the whole face of the Earth he could not have mentioned surface features more totally unlike any feature of the Martian surface, as drawn by him, than these two channels: the English Channel, 100 miles wide at its mouth and 200 miles long, tapering to the Straits of Dover; the Mozambique Channel, hour-glass shaped, 1,100 miles long, and, at its narrowest part, 260 miles wide, and at either end nearly 700 miles wide. Had he suggested the Red Sea, 1,200 miles long, or the Straits of Malacca, 350 miles long, a nearer resemblance to the canals of Mars might have been seen, though even here it would be impossible to find their counterparts in Mars. These channels are merging with the ocean, are nearly half the width of their length, and enlarge at both ends, while the canali of Mars run for hundreds of miles as straight as ruled lines. How slight the resemblance is may be appreciated by comparing the following figure of the Earth (Fig. 1), upon which the Red Sea, the English and the Mozambique Channels and the Straits of Malacca are indicated.

Fig. 1.

In 1897 Schiaparelli becomes still more convinced of their artificiality. In his Memoir XXV, in the Reale Academia del Lincei, in speaking of the canals, he says: "This whole arrangement presents an indescribable simplicity and symmetry which cannot possibly be the work of chance." In a letter to Mr. Lowell, dated December 4, 1904, he writes: "Your theory of vegetation becomes more and more probable." Mr. A. Stanley Williams, in the "Observatory" for June, 1899, in a paper entitled "Notes on Mars," described the appearance of certain canals, regions, etc., in great detail. He notices that at the crossing of the canals a little dark spot occurs, a feature, he says, which was first elucidated by Professor Lowell in 1894. Mr. Williams also noticed the black streak bordering the northern snow cap, which Mr. Lowell in his book on Mars has interpreted as a body of water resulting from the melting snow.

In the Quarterly Journal of the Astronomical Society of Wales, the Rev. Theo. E. R. Phillips publishes an excellent drawing of Mars in color. In this drawing he shows a large number of regions, a number of canals, and other features which, he says, "came out with the clearness and sharpness of an engraving, and bore no resemblance to the 'diffused streaks' or amorphous smudges one sees for the canals in imperfect seeing." In this drawing the polar snow caps show with remarkable vividness.

Professor W. H. Pickering, in a continuous record of observations on Mars, published in the "Annals of the Lowell Observatory," records under August 20: "The dark north canals are also noticeable, and, had they looked as they now do, could not possibly have been missed on the 16th."