The collections of lakes along the cracks on Mars which appear to us as “canals” are repeatedly filled up by sand and dried out. They are revived through new depressions along the dislocation fissures, corresponding to our earthquakes, when vapours of water and other gases pour forth and condense to lakes in the deepest pockets of the fissures. Canals are therefore created rather rapidly, sometimes over night, and vanish occasionally as suddenly. The most remarkable case of “new” canals was made known through a communication by Lowell. Two new canals, at the time the most conspicuous on the surface of Mars, were observed east of “Syrtis magna” on September 30, 1909, from Flagstaff observatory, when they also were photographed, which precludes an illusion. (On the other hand there was no sign of the great canal Amenthes, shown on the map Fig. 17, a short distance to the left, _i. e._, east of Syrtis in the very section where the new canals were observed.) Also two new oases through which the new slightly curved canals passed were observed for the first time, as were also a few minor canals in the neighbourhood. In 1913, the double canal Æthiops (see map at Long. 240°; the canal is there single) was rediscovered from the Lowell observatory after an absence of fifteen years. These data make it evident that one or possibly several rather strong earthquakes took place east of Syrtis major just prior to September 30, 1909 with the two oases as centres of collapse. The fissures now made visible have probably existed before but filled with sand and have now reappeared as a result of the condensation of water vapour when it emerged into the cold Martian air. This fact, that the most prominent canals in such manner now suddenly appear and now as rapidly vanish, ought to convince us beyond doubt that they are not magnificent products of engineering skill, for the construction of which we should require centuries on the Earth.