"canals" in the light regions from other celestial phenomena. In short, he detected in the dark regions what Schiaparelli had detected in the light. Counterparting exactly the network over the light areas, a mesh of similar lines overspread the blue-green areas. The lines were of uniform width, of unswerving directness, and went from definite points to other equally determinate ones. These points were always of geographic importance. They were at the ends of "seas," at the bottom of "bays," or at points on the "coast-line" where canals debouched. The lines connected these topographical centres, crossing one another in the process, and at the junctions there showed, just as in the light areas, dark round spots.
Instantly to be deduced from such engraving was that the "seas" were not bodies of water. We knew this already, as I have shown; but the evidence was valuable in completely convincing those who require more than mediate proof. Permanent lines cannot be writ on water. The seas lost their character forever.
The absence of any bodies of water outside of the temporary polar sea introduces a far-reaching difference between Mars and the Earth. On Earth three quarters of the surface is water; on
