At the next opposition of Mars, Schiaparelli not only rediscovered his canals, but made the astonishing announcement that many of them were double, a second streak running exactly parallel to the first at some distance from it. His observations were received with a considerable amount of doubt and hesitation. Skilled observers declared that they could see nothing in the heavens the least corresponding to the network of hard lines which the Italian observer drew across the globe of Mars; and therein to some extent they were right, for the canals are not seen with that hardness of definition with which they are sometimes represented. But, at the same time, each successive opposition has added fresh proof of the fact that Schiaparelli was essentially right in his statement of what was seen. The question of the doubling of the canals is still under dispute, and it seems probable that it is not a real objective fact existing upon the planet, but is merely an optical effect due to contrast. There can be no question, however, about the positive reality of a great number of the canals themselves; their existence is too well attested by observers of the highest skill and experience. 'There is really no doubt whatever,' says Mr. Denning, 'about the streaked or striated configuration of the Northern hemisphere of Mars. The canals do not appear as narrow straight deep lines in my telescope, but as soft streams of dusky material with frequent condensations.' The drawings by Mr. Phillips well represent the surface of the planet as seen with an instrument of considerable power; and the reader will notice that his representation of the canals agrees remarkably well with Denning's description. The 'soft streams with frequent condensations' are particularly well shown on the drawing of April 22, 1903, which represents the region of 200° longitude (see Chart, Plate XXI.) on the centre of the disc. 'The main results of Professor Schiaparelli's work,' remarks Mr. Phillips, 'are imperishable and beyond question. During recent years some observers have given to the so-called "canals" a hardness and an artificiality which they do not possess, with the result that discredit has been brought upon the whole canal system.... But of the substantial accuracy and truthfulness (as a basis on which to work) of the planet's configuration as charted by the great Italian in 1877 and subsequent years, there is in my mind no doubt.' The question of the reality of the canal system may almost be said to have received a definite answer from the remarkable photographs of Mars secured in May, 1905, by Mr. Lampland at the Flagstaff Observatory, which prove that, whatever may be the nature of the canals, the principal ones at all events are actual features of the planet's surface.