in southern hemisphere, [80], [92].

Huyghens, [23], [26], [108].

Ice sheet, effect of, [52].

Illumination, oblique, [97];

for measuring elevations, [98].

Illusion theories of canals, disproved, [293].

Image of sun, not reflected from dark areas, [112].

Insolation, [47], [79], [91].

Intelligence on other worlds, method of making itself known, [364].

Islands south, [91], [244];