al illuminations in
celebration by her inhabitants of some periodically recurring
festivity, The materials for a flare-up on so grand a scale would, he
thought, exist in abundance, as he conjectured the vegetation of our
planetary neighbor to be more luxuriant than that of our Brazilian
forests. The phosphorescence of the Aphroditean oceans, warm and
teeming with life, as they are held to be by Zollner, was advanced as
an explanatory hypothesis, with scarcely more plausibility, by
Professor Safarik, while others have resorted to the supposition of
atmospheric or electrical luminosity producing on a large scale some
such display as that of the aurora borealis.

Professor Vogel, of Berlin, who himself saw part of the night-side of
Venus, in its semi-obscurity in November, 1871, ascribed its
visibility to a twilight effect caused by a very extensive atmosphere.
The light thus transmitted to us by aerial diffusion and giving the
ashen light, is reflected sunlight, while that sent by the luminous
arc on its edge is direct sunlight, refracted, or bent round to us,
from behind the planet. The silver selvedge of the dawn edging the
dark limb may consequently be the brightest part of the broken nimbus
that then seems to surround her.

A similar appearance is observed during transits of Venus, when she
passes directly between us and the actual solar disk. A silver thread
is then seen encircling that side of the planet which has not yet
entered on the face of the sun or "a shadowy nebulous ring," as it was
described by Mr. Macdonnell at Eden, surrounds the whole planetary
disk when two-thirds of it have passed the solar edge. As it moves off
it, the same aureole again becomes visible, testifying to the
existence of an atmosphere of considerable extent exterior to the
sharply outlined surface ordinarily visible. The shimmering haze of
reflected sunlight which perpetually enfolds her is only made apparent
to us under exceptional circumstances which cut off some portion of
her more immediate light, just as we see the motes in the air
illuminated by a candle if we hide the actual flame from our eyes. The
perennial twilight which seems to reign over the nocturnal hemisphere
of Venus may compensate, perhaps, for the want of a satellite to
modify its darkness.

The great prolongation at other times of the horns of her crescent, so
as to embrace almost her entire circumference with a tenuous ring of
light, is doubtless due to the same