snow, if it be snow, is melted as on earth by vegetation; and the vegetation, if it be vegetation, melts the snow as on earth.
Observations of this character again were made on August 2, 1920, and the following date, September 20, Martian calendar. One of the first northern snowfalls occurred near that time, and a canal was easily seen going north from the Arethusa Lucus, but was obliterated completely further north by the new-fallen snow. The drawing of the next day, August 3, shows that the snow has melted over the canal—as it would over vegetation—and that there is left a rift where the day before the cap showed an even contour, but on the following is made up of two lobes, one on each side of the now triumphant and still flourishing canal.
Before this date, a snowfall occurred north of the Proponti, and from the rift seen in the drawing of July 8, this snow must have fallen earlier even than this and melted over the canal that leaves the Propontis in a northerly direction towards the cap. This is an identical example of the phenomenon seen on August 3. It is also interesting in that it shows the depth of the new-fallen snow to be much thinner, as Dr. Lowell suggests, than the old winter cap itself; which can be seen dimly, together with its dark surrounding band, through the new covering of snow.
That the tiny northern cap itself was thin is evidenced in the drawings of May 11 and 12, 1920, where a slight rift is visible cutting the cap nearly in two. This is no doubt similar to the "Open Polar Sea" that Dr. Lowell talks of in referring to the small southern cap.
Detail on Mars is so complex, and the conclusions one can draw from the secular and seasonal changes so interesting, that when by careful scrutiny of the disk a marking of great interest is observed—it would be really better to devote one's attention to that area alone and draw it—rather than attempt a drawing of the whole disk. The marking itself would be swamped in a complete drawing, without regard to the attention taken from it by an endeavor to portray the rest of the surface features of the planet.
Mars has given to this world a most interesting and instructive line of research—I might almost say vital to the future welfare of the race on Earth.
