THE MYSTERY OF MARS — WILKTNS 233 



of these in the northern hemisphere which, as we have already said, 

 is chiefly desert, one is very prominent and sometimes even more prom- 

 inent than the Syrtis Major. This dark spot is called the Mare 

 Acidalium, and is connected with the Pearl Bearing Gulf by a wide 

 canal called Indus. A little to the right, or west, of Acidalium is one 

 of the dark spots in the desert, called Lacus Lunae or Lake of the 

 Moon. From this spot a wide canal, Gauges, crosses the desert to the 

 patch of vegetation Aurorae Sinus, near the Eye of Mars. The last 

 desert outpost is the Lucus Ascreus. Then comes the great desert 

 of Amazonia, which extends over 90° of longitude to Trivium 

 Charontis. This desert is crossed by a few canals of which Lycus, 

 Brontes and Oreus are the largest. Immediately to the west of 

 Trivium is a large white area called Elysium, bordered by canals and 

 with a network of them right up to the pole. 



These are the chief permanent markings on Mars, but they are never 

 seen all together. During the winter the polar caps are large, while 

 the canals are then either invisible or can only be traced with diffi- 

 culty ; but as the cap melts, a dark girdle appears around it, probably 

 a temporary polar sea, and then the canals begin to appear. At first 

 only a little bit near the melting snow can be seen, but this gradually 

 gets longer and longer until the whole of the canal is marked out as 

 far as one of the patches of vegetation. Like the canals, these patches 

 are mere shades during the winter, but begin to darken as the canals 

 from the poles fill up, and are very prominent during the summer. 

 With the onset of autumn they change from a dark grayish-green to 

 brown, and then become mere shades in winter. 



All this fits in beautifully with Lowell's idea of artificial waterways, 

 but there are other opinions. With his 24-inch telescope Lowell saw 

 and drew the canals as narrow and continuous lines, but another emi- 

 nent observer, Antoniadi, using a larger telescope, the 33-inch at 

 Meudon, near Paris, declared that these narrow lines were illusions. 

 He said that the reason why Lowell saw and drew them as continuous 

 lines was due solely to his telescope being too small to show their 

 true nature. With the great telescope at Meudon, the canals were 

 seen not to be continuous but made up of a series of dots and dashes, 

 arranged one after the other in straight lines. Whether the canals are 

 continuous or not, whether they are natural or artificial, all observers 

 agree that what we see is not the actual ditch, assuming they are 

 ditches, but the vegetation to either side of them. An American ob- 

 server, John E. Mellish, declares that with the 40-inch refracting tele- 

 scope at the Yerkes Observatory, the largest instrument of its type in 

 the world, the canals appeared as cracks, wide and eroded down, com- 

 paratively shallow and filled with water. Some of the very wide 

 canals were distinctly seen to be darker in the center, and resembled 

 ditches filled with water and with marshes and vegetation along their 



