Alexandria gazette. [volume] (Alexandria, D.C.) 1834-1974, 1858-05-05
m1soELLANEoUs READING.
ASTRONOMICAL SPECULATION.

! On Monday, the 18th, Professor Michel,
LII. ID 4, delivered the third of course of
: lectures on A A-tronomy, at Manchester. The
subject treated upon bad reference chiefly TO
the rings Of Saturn, and other analogous
phenomena lie referred to an observation
made in the Introductory lecture, respecting
there being ring, or probably several rings
round the earth. What had hitherto been
called the zpdacal light was only visible
here 10 the iurm Of q cone, but an American
astronomer, who bad gone 70 Japan and 9TH
er favorable points to investigate the SUBJECT,
found that the cone opened out ana extenoeu
across the heavens from horizon to horizon;
and that be had, by observation dorng the
night, seen about tbree.fourths OF the circle.
This observer found that We bad only been
looking at the ring as We might do at a hoop
held edgewise, thus making it assume conf
cal form. The learned professor now pre-
ceeded to say that the theory preViousy y held
that the zOdiacal light proceeded from ne
bulous ring round the sun, was thought 10
be premature, and that the appearance came
from a great Debulous ring surrounding the
earth. He explained, by means of dia-
gram, that we should see the rays from this
ring reflected more strongly from our hori.
zon than at its points higher up in the hea-
vens. No ring round the sun could explain
this appearance, but one round the earth
would entirely. Tsey were forced also to the
conclusion that it was not one ring only, bue
perhaps several. Its distance was abouo
100 900 miles; its breadth 1000; its depth
vas not yet known; the mass oil matter IN u
must be enormous, and no doubt il was ful'
filing some i'm portant function in regard to
the earth and the solar system. Ibs COM
position Of Saturn rings vas then discovered,
and an account given Of the changes which
had been noticed 10 them, by various observ-
ers.
From the dynamicsl conclusion Of LapIsce
combined with the changes ascertained, the
lecturer drew the inference that the rings
have no conference; that they are neither va
por nor fluid; and gave as a theory OF their
constitution, that they are composed OF mil
lions of asteroids, circulating round the pla-
net the bright parts being where they are
most thckly strewed and the dark lines the
absence of them. There was faint slaty
colored ring seen within the others, ard this
appeared to be gradually approaching the
planet. 1t had approached at the rate OF fifty
miles year; latterly, at about eighty miles
year, hh0 u ~ ioSsOooOe w WV
miles year, it would reach the planet itself
10 $50 years. The remaining portion OF the
lecture was occupied with q consideration OF
the cause Of the suns heat, and how it was
sustained It's heat was estimated to be
equivalent to one-third of ton Of coal con-
sxmed on every square foot of its surface in
an hour. A certain amount OF heat would
produce q certain amount Of mechanical ef-
feet; and the converse was equally true, that
no mechanical effect or force could be de-
stroyed. without involving as much heat as
would reproduce it. The lecturer applied
the latter part of this reasoning TO the sun
Ii the planet Mercury were to fall upon the
suo, it would be at the rate OF 800 millions OF
miles 10 second. An amount OF mechani-
cal effect would thereby be destroyed as
would supply the sun with as much heat as
be radistes iu three years, and that heat
would Immediately fash through the stellar
spaces. The lecturer attributed the sustain.
ed heat Of the sun to vast numbers Of meteor
ties falling upon his surface, somo of which
might csuse eddiss in the atuosnhnrc. and
produce the spots which waro frequently 'isi
BILE. After expressing his belief that, from
the retarding effect Of either IN space, all
bodies were approaching their centres, he
concluded with some remarks OF an impres-
siye character.