of view, but the floor still appeared
equally dark.

"Others have suggested that the hot sun causes the growth of some kind
of vegetation all over the plain, the ripening of which makes the floor
darker in tint. As regards this suggestion, it is the fact that upon
Mars the old sea-beds are the places where vegetation is most luxuriant
at the present time; so, if Plato were at one time an enclosed sea, it
might not be impossible that vegetation in some low form might grow and
be nourished by the crude gaseous remains of a former atmosphere. A
greenish tint has occasionally been noticed by some observers, also
several light streaks across the floor, as well as several small
craterlets, which have been duly noted on the maps.

"But before we go any further we will have a better means of seeing, for
it is rather uncomfortable looking directly down upon the moon. So,
John, just lend a hand and we'll fetch one of those large mirrors."

This was done, and the mirror suspended with the upper part projecting
forward, so that when adjusted at the proper angle we could sit and look
straight into the mirror before us and see the reflection of all that
was below. We could still look down at the objects, if we wished to do
so, without shifting our position.

"There, John," I remarked, as we completed this arrangement, "I have
already arranged mirrors in the proper positions at the windows in the
forepart of the vessel, so that in future M'Allister will be able to see
what is nearly straight ahead of him. Now you will understand that I had
a scientific use for the mirrors I provided, and did not require them
merely to admire my beautiful face in as you suggested."

John laughed as I recalled his suggestion, saying, "All right,
Professor, I know you generally have a good reason for what you do."

Now, being more comfortably seated, I drew their attention to some small
isolated mountains on the area to the south of Plato, pointing out Pico,
an isolated mountain over 8000 feet in height, and another with three
peaks not very far from it. To the north-east of these, some distance
away, are the Teneriffe and Straight Ranges; also isolated groups.

"You will remember," I remarked, "that I said there were several
formations which seemed to me to owe their present appearance to the
action of water. Now look well at all this district before us--does it
not seem to bear out my contention? Those numerous small mountains and
isolated grou