All the vast extent of the continents is furrowed upon every side by a network of numerous lines or fine stripes of a more or less pronounced dark colour, whose aspect is very variable. They traverse the planet for long distances in regular lines, that do not at all resemble the winding courses of our streams. Some of the shorter ones do not reach three hundred miles; others extend for many thousands, occupying a quarter or even a third of the circumference of the planet … The canals may intersect among themselves at all possible angles, but by preference they converge towards the small spots to which we have given the name of lakes. – Schiaparelli
Schiaparelli, 1888
E. Antoniadi, 1900
De Vaucouleurs, 1950