Vast plains of a dusky tint become visible, not perfectly level, but covered with ripples, pits, and projections.

Circular wells, which have no surrounding wall dip below the plain, and are met with even in the interior of the circular mountains and on the tops of their walls.

From some of the mountains great streams of a brilliant white radiate in all directions and can be traced for hundreds of miles.

We see, again, great fissures, almost perfectly straight and of great length, although very narrow, which appear like the cracks in moist clayey soil when dried by the sun."[14] But interesting as these views may be, it was not for such discoveries as these that astronomers examined the surface of the moon.

The examination of mere peculiarities of physical condition is, after all, but barren labour, if it lead to no discovery of physical variation.