Professor W. H. Pickering has advanced a new speculative theory called "The Theory of Aerial Deposition." According to this theory the major canals are natural marshes fed by storm laden air currents. These marshes furnish Mars a substitute for our oceans. Without them "the water evaporated from the summer pole would find its way too rapidly, through the natural general atmospheric circulation of the planet, to the southern polar regions, where, wrapped at this season in the long winter night and subjected to the cold of space, it would quickly be withdrawn from further use in support of vegetal and perhaps animal life. The function of the so-called canals or marshes in the economy of the planet is in short to furnish a substitute for our oceans, and to furnish by evaporation during the Martian summer a steady and continuous supply of water after that derived from the northern snows has appreciably diminished." The above is quoted from a report on Mars by Professor Pickering in the January number of _Popular Astronomy_, 1918. Professor Pickering believes that the "canals" "are either bands of moistened soil or vegetation growing on moistened soil" and that they cannot be anything else "for we know of no solid in the mineral world that darkens and then fades out in the sunlight." He does not think that the major canals are necessarily the work of intelligent beings, but they do serve the purpose of furnishing the northern hemisphere with a supply of water in the form of natural marshes during the long northern summer until the southern polar cap starts to melt at the coming of the autumnal equinox. Professor Pickering, who has written a book called "Mars," gives the following interesting information as to how the planet appears through the telescope at Flagstaff: "We may examine the moon some night through a small opera-glass. The sharpness and amount of detail visible in the two cases will be similar, although the appearance of the two bodies is quite unlike." General public interest in Mars is probably keener than in any other planet and since the great event of August 23rd, 1924, when Mars shone like a lantern in the sky, this interest will probably grow greater than ever. This small matter of 34,648,000 miles--not much over a third of the distance to the sun away from us--is almost as near as the earth and Mars will ever approach one another. An association of observers interested in Mars who are stationed in different parts of the world has recently been formed. All parts of the planet are now kept under inspection and regular reports are sent to a central bureau which publishes the results in an astronomical magazine. THE SATELLITES OF MARS