e
spectroscope would tell us), contains often large quantities of the
vapor of water, would be as absurd as to believe in the green cheese
theory of the moon, or in another equally preposterous, advanced
lately by an English artist--Mr. J.T. Brett--to the effect that the
atmosphere of Venus is formed of glass.

There is another theory about Mars, certainly not so absurd as
either of those just named, but scarcely supported by evidence at
present--the idea, namely, advanced by a French astronomer, that the
ruddy color of the lands and seas of Mars is due to red trees and a
generally scarlet vegetation. Your poet Holmes refers to this in those
lines of his, "Star-clouds and Wind-clouds" (to my mind among the most
charming of his many charming poems):

"The snows that glittered on the disc of Mars
Have melted, and the planet's fiery orb
Rolls in the crimson summer of its year."

It is quite possible, of course, that such colors as are often seen
in American woods in the autumn-time may prevail in the forests and
vegetation of Mars during the fullness of the Martian summer. The fact
that during this season the planet looks ruddier than usual, in some
degree corresponds with this theory. But it is much better explained,
to my mind, by the greater clearness of the Martian air in the
summer-time. That would enable us to see the color of the soil better.
If our earth were looked at from Venus during the winter-time, the
snows covering large parts of her surface, and the clouds and mists
common in the winter months, would hide the tints of the surface,
whereas these would be very distinct in clear summer weather.

I fear my own conclusion about Mars is that his present condition
is very desolate. I look on the ruddiness of tint to which I have
referred as one of the signs that the planet of war has long since
passed its prime. There are lands and seas in Mars, the vapor of water
is present in his air, clouds form, rains and snows fall upon his
surface, and doubtless brooks and rivers irrigate his soil, and carry
down the moisture collected on his wide continents to the seas whence
the clouds had originally been formed. But I do not think there is
much vegetation on Mars, or that many living creatures of the higher
types of Martian life as it once existed still remain. All that is
known about the planet tends to show that the time when it attained
that stage of planetary existence through which our earth is now
passin