Page:The Solar System - Six Lectures - Lowell.djvu/84



(11) second, because the quantity of the darkening is not offset by the synchronous lightening elsewhere. It cannot therefore be due to shift of substance;

(12) third, because they are seamed by a canal system counterparting that of the light areas, permanent in place.

(13) Extension of this shows that there are no permanent bodies of water on the planet.

(14) All the phenomena are accounted for by supposing them to be areas of vegetation.

(15) The polar sea being a temporary affair, the water from it is fresh.

(16) Observations on the terminator reveal no mountains on Mars, the details of the observations being incompatible with such supposition;

(17) but do reveal apparently clouds, which, however, are rare, and are chiefly visible at sunrise and sunset,

(18) and seem connected with the heat equator.

(19) The bright areas look and behave like deserts.

(20) In their winter, the south temperate light regions are covered by a white veil, which may be hoar-frost or may be cloud.

(21) Very brilliant patches appear also in the equatorial light regions that last for weeks, and seem independent of diurnal conditions.