The Emporia news. [volume] (Emporia, Kan.) 1859-1881, 1870-01-28

4
with long out-reaching arms, the spiral
nebulae with mystic conyolutions
around their blazing naclei, the wild and
fantastic figures of the irregular nebulae,
all these forms of matter had been
forced to reveal their secret under the
searching eye of the great Parsonstown
reflector. Bat vast as are the powers
of this giant telescope, and interesting
as the revelations it had already made,
there was one defect which paralyZed
half its powers. 1t was an inert mass
well poised indeed, so that the merest
infant could sway it, but possessing no
power of self-motion. The telescopes
in our great observatories follow per-
sistently the motions of the stars upon
the celestial vault, but their giant broth
eEpossessed no such power. And when
we remember the enormous volume of
the Rose Telescope, its tube-fifty feet
in length-down which a tall man can
walk upright, and its vast metallic spec
ulum weighing several tons, the task of
applying clock-motion to so cumbrous
and seemingly unWieldy a mass might
well seem hopeless. Yet without this
it was debarred from taking its part in
multitude of processes of research to
which its powers were wonderfully
adapted. Spectroscopic analysis, as APP
piled to the stars, for example, requires
the most perfect uniformity of clock
motion, so that the light from a star,
once received on the jaws of the slit
which forms the entrance into the spec
troscope, may not move off them even
by a hairs breadth. And the determin-
alton of the moons heat required an
equally exact adaptation of the teles-
cope's motion TO the apparent move
ment of the celestial sphere. For so
daIi is fIo%
heat generated in turning the telescope
upon the moon by the ordinary arrange
ment would have served to mask the re-
suit.
AT enormous cost, and after many
difficulties bad been encountered, the
Rose reflector has at length had its
powers more than doubled, bv the adj
diton of the long-wanted power of
self-motion. And among the first
fruits of the labor thus bestowed upon
it, is the solution of the famous prob
lem of determining the moons heat.
The delicate heat-measure, known as
the thermopile, was used in this work,
as i'll Mr.. Huggins's experiments for es-
timating the heat we receive from the
stars. The moons heat, concentrated
by the great mirror, was suffered to fall
upon the face of the thermopile, and the
indications of the needle were carefully
watched. a small but obvious defiec-
ton in the direction signifying heat was
at once observed, and when the observ-
alton had been repeated several times
with the same result no doubt could re-
main. We actually receive an apprecia-
bic proportion of our warmth-supply
from ''the chaste beams of the wat'ry
moon" The view which Sir j Ohm Her
schel had long since formed on the be-
havior of the f1eecy clouds of a summer
night under the moons influence was
shown to be as correct as almost all the
guesses have been which the two Her.
schels have ever made.
And one of the most interesting of
the results which have followed from
the inquiry confirms in an equally strik-
ing manner another guess which Sir
John Herschel had made. By compar-
ing the heat received from the moon
with that obtained from several terres-
trial sources, Lord Rose has been led
to the conclusion that at the time of full
moon the surface of our satellite is
raised to temperature exceeding by
more than $50 dogs. (Fahrenheit) that
of boiling water. Sir John Herschel
long since asserted that this must be So
During the long lunar day, lasting some
800 of eur hours, the suns rays are
poured without intermission upon the
lunar surface. No clouds temper the
heat, no atmosphere even serves to in
terpOse any resistance to the continual
down-pour of the fierce solar rays
And for about the space of three of our
days the sun hangs suspended close to
the zenith of the lunar sky, so that if
there were inhabitants on our unfortu-
nate satellite, they would be scorched
for more than seventy consecutive hours
by an almost vertical sun.
There is only one point in Lord ROSES
inquiry which seems doubtful. That
we receive heat from the moon he has
shown conclusively, and there can be
no doubt that a large portion of this
heat is rddidted from the moon But
there is another mode by which the
heat may be sent to us from the moon,
and it might be worth while to inquire
little more closely than has yet been
done whether the larger share of the
heat rendered sensible by the great mir
ror may not have come in this way.
We refer to the moons power of re-
fecting heat. 1t need hardly be said
that the reflection and the radiation of
heat are very different matters. Let
any one hold FURNISHED metal plate in
such way that the suns light is reflect
ed towards his face, and he will feel
that with the light Il considerable
amount of heat is reflected. Let him
leave the same metal in the sun until it
is well warmed, and he will find that
the metal is capable of imparting heat
to him when it is removed from the
suns rays. This is radiation, and can
not happen unless the metal has been
warmed, whereas heat can be reflected
from an ice-cOld plate. There has been
nothing in the experiments conducted
by Lord Rose to show us by which of
these two processes the moons heat is
principally sent to US nor do we know
enough ofthe constitution of the moons
surface to estimate for ourselves the
relative proportions of the heat she re-
fleets and radiates towards us.
We do not mention this point from
any desire to cavil at the results of one
of the most interesting experiments
which has recently beeen carried out.
But the recent researches of Zoilner up
on the light from the planets, have
shown how largely the surfaces of the
celestial bodies differ as respects their
capacity for rejecting and absorbing
light, and there is every reason to infer
that similar peculiarities characterize
the planets power of absorbing and re-
fiecting heat. The whole question of
the heat to which the moons surface is
actually raised by the suns heat depends
upon the nature of that surface, and the
proportion between its power of alb
sorbing heat or rejecting il away into
space.-LoadOE Spectator.