No natural force propels it, and the inference is forthright and inevitable that it is artificially helped to its end.

There seems to be no escape from this deduction.

Water only flows downhill, and there is no such thing as downhill on a surface already in fluid equilibrium.

A few canals might presumably be so situated that their flow could, by inequality of terrane, lie equatorward, but not all....Now it is not in particular but by general consent that the canal-system of Mars develops from pole to equator.

From the respective times at which the minima take place, it appears that the canal quickening occupies fifty-two days, as evidenced by the successive vegetal darkenings, to descend from latitude 72 deg.