Of the remainder, that the lines called canals are truly great furrows or depressions in the surface of the planet, destined for the passage of the liquid mass and constituting for it a true hydrographic system, is demonstrated by the phenomena which are observed during the melting of the northern snows.  We have already remarked that at the time of melting they appear surrounded by a dark zone, forming a species of temporary sea.  At that time the canals of the surrounding region become blacker and wider, increasing to the point of converting at a certain time all of the yellow region comprised between the edge of the snow and the parallel of 60 degrees north latitude into numerous islands of small extent.  Such a state of things does not cease until the snow, reduced to its minimum area, ceases to melt.  Then the breadth of the canals diminishes, the temporary sea disappears, and the yellow region again returns to its former area.  The different phases of these vast phenomena are renewed at each return of the seasons, and we were able to observe them in all their particulars very easily during the oppositions of 1882, 1884, and 1886, when the planet presented its northern pole to terrestrial spectators.  The most natural and the most simple interpretation is that to which we have referred, of a great inundation produced by the melting of the snows; it is entirely logical and is sustained by evident analogy with terrestrial phenomena.  We conclude, therefore, that the canals are such in fact and not only in name.  The network formed by these was probably determined in its origin in the geological state of the planet, and has come to be slowly elaborated in the course of centuries.  It is not necessary to suppose them the work of intelligent beings, and, notwithstanding the almost geometrical appearance of all of their system, we are now inclined to believe them to be produced by the evolution of the planet, just as on the earth we have the English Channel and the channel of Mozambique.

It would be a problem not less curious than complicated and difficult to study the system of this immense stream of water, upon which perhaps depends principally the organic life upon the planet, if organic life is found there.  The variations of their appearance demonstrated that this system is not constant.  When they become displaced or their outlines become doubtful and ill defined, it is fair to suppose that the water is getting low or is even entirely dried up.  Then, in place of the canals there remains either nothing or at most stripes of yellowish color differing little from the surrounding background.  Sometimes they take on a nebulous appearance, for which at present it is not possible to assign a reason.  At other times true enlargements are produced, expanding to 100, 200 or more kilometers (60 to 120 miles) in breadth, and this sometimes happens for canals very far from the north pole, according to laws which are unknown.  This occurred in Hydaspes in 1864, in Simois in 1879, in Ackeron in 1884, and in Triton in 1888.  The diligent and minute study of the transformations of each canal may lead later to a knowledge of the causes of these effects.