The herald and mail. [volume] (Columbia, Tenn.) 1873-188?, 1875-11-12
SCIENCE AND ART.

! HE ZODIACAL LIGHT. during hi
residence in the island of Jamaica il
1868 and 1869, NJ. Houseau assiduousll
observed the zodiacal light for si1
months consecutively, and has nov
communicated the results to the Bel
gian academy. NJ. Houzeau has fol
more than thirty years devoted great
attention to this pulling phenomenon
and he is fortunate in having now OBJ
tanned such fine series of observations
the boundary Of the zodiacal light i;
having been carefully determined by
him on 56 nights out Of the 179. As
far as these results go, it appears that
the zodiacal light is not appreciably i'll
clined to the ecIiptic, and does not ap-
proach to coincidence either with the
plane of the suns equator, as Cassini
supposed, or with that Of the moons
orbit, as Jones has more recent y sug-
gested. The observed deviations from
the plane of the ecliptic are explained
by NJ. Houzeau as the results Of greater
absorption of the light of the lower or
southern side by our atmosphere,
which is, of course, less transparent
near the horizon. From these obser-
vations, M. Houzeau concludes that we
must reject both the hypothesis which
regards the zodiacal light as an append
age of the sun, and that which assigns
it to the moon; and since, if it were a
ring round the earth, it would be seen
as a complete arch in the sky crossing
from the east to west, the author Is
driven to the conclusion that it il fan
shaped sector, somewhat similar to the
tail Of comet, spreading from the
earth towards the sun, thinning off
each side of this direction, so that it
extends to about 400 on the side to-
wards which the earth is moving, and
go or 100 ON the other side. This
must, of course, be modified, if we ac-
cept these observations in which the
zodiacal light has been distinctly traced
right across the heavens from east to
west; but NJ. Houzeau's conclusions are
founded on his own observations alone.
For the period of his watch there was q
sensible diminutiOn of brightness, the
zodiacal light being seen in January,
1869, as readily as a fourth-magnitude
star in twilight, while by June it was
not so bright as the fifth magnitude.
From observations on his voyage t.
Rodrigues and back, with the Transit of
Venus Expedition, Mr.. Burton has
been led to very different conclusions.
He was provided with binocular spec
troscope devised by himself specially
for this work, and with this he deter
mined the spectrum Of the zodiacal
light to consist of a continuous band
with brightline IN theyellow forming
the boundary Of the spectrum on that
side and a dark line in the green.
This same spectrum was given by every
part Of the sky unoccupied by the Milky
Way, most important observation,
which, in combination with the change
of form Of the zodiacal light seen when
the observer passed from S. to n. lati-
tudes, shows, according to Mr.. Burton,
that it reaches and probably surrounds
the earth. From the spectrum seen, as
well as from the fact Of polarization in
a plane through the axis of the zodiacal
light, Mr.. Burton further concludes
that it is emitted by matterpartly liquid
and partly solid, intermixed with gas.