coördination of data, [288], [289];

curves of visibility of (see Cartouches), [289], [290];

geometricism of, [175], [206], [365], [367], [368];

polar, [327].

Canals in the dark regions, [30], [31], [243-248];

of the southern hemisphere, [245];

of the northern hemisphere, [246], [247];

detection of, [243], [245];

deprived seas of marine character, [243];

part of canal system, [244], [245], [247].