invariable temperature.

To some minds it may appear very undesirable, from the point of view of
animate existences, that there should be no alternation of seasons on
the surface of a planet, but, instead, fixed conditions of climate; yet
it is not clear that such a state of affairs might not be preferable to
that with which we are familiar. Even on the earth, we find that
tropical regions, where the seasonal changes are comparatively moderate,
present many attractions and advantages in contrast with the violent and
often destructive vicissitudes of the temperate zones, and nature has
shown us, within the pale of our own planet, that she is capable of
bringing forth harvests of fruit and grain without the stimulus of
alternate frost and sunshine.

Even under the reign of perpetual summer the fields and trees find time
and opportunity to rest and restore their productive forces.

The circularity of Venus's orbit, and the consequently insignificant
change in the sun's distance and heating effect, are other elements to
be considered in estimating the singular constancy in the operation of
natural agencies upon that interesting planet, which, twin of the earth
though it be in stature, is evidently not its twin in temperament.

And next as to the all-important question of atmosphere. In what
precedes, the presence of an atmosphere has been assumed, and,
fortunately, there is very convincing evidence, both visual and
spectroscopic, that Venus is well and abundantly supplied with air, by
which it is not meant that Venus's air is precisely like the mixture of
oxygen and nitrogen, with a few other gases, which we breathe and call
by that name. In fact, there are excellent reasons for thinking that the