Year: 1869




THIS is the question that selenographers
are now earnestly discussing. 1t is strange
that so little should be known of the near
est heavenly body, as to leave such ques-
ton open and championed on both sides
by men of genius and great experience in
lunar observations. That two theories so
precisely opposite should exist with regard
to the state of the moon, may well throw
doubt on some of the most confident
gucsscs into the condition of the moro dis
tant sun and planets and stars. Sir John
Hcrschcl stood forth as the chief defender
of what we may call for brevity, the
furnace theory" of the moon. He be-
lievcd that, owing to the long lunar days
lasting some three hundred of our
hours-the moon warns up under the
fierce heat of the sun, until its temperature
is more than 900 degrees F. above that of
boiling water-or about 492 degrees. For
nearly seventy hours any given point on
the moons surface turned toward the sun
is exposed to the almost vertical rays of
that body. The moon having no atmOs-
phere, or one so tcnuOus as to be invisible
to us, there would be no mitigation of
shelter from the blazing downpour of the
-.
such as we are familiar with, could live for
an hour under such torrid influcnccs-to
say nothing of the want of atmosphere,
which in the terrestrial order of things, is
indispensable to the vitality of animals and
plants So far the Herschel theory. But
Captain John Ericsson, the distinguished
American inventor, man OF profound
originality, and slow and cautious OBJ
md rict "
an opinion, that the moons surface is one
mass of ice. He has arrived at this con-
clusion from novel and ingenious expert
ments to ascertain the actual intensity of
the solar rays in absolute space, that is
before they enter the earths atmosphere.
We have not room to detail his processes
of investigation which were given in full
to the American Association for the Adj
vancement of Science at its late meeting,
and will only say that they are regarded
by him as proving the actual heat of the
solar rays in absolute space to be more
than 500 degrees below the freezing
point of water-a degree of cold which
has no parallel in human experience, and
which would be as deadly to animal life
and vegetation as the high heat imagined
by Herschel. The reason why the earth
is not as cold as the moon is that the for
mcr has an atmosphere, which prevents
the earth from parting with the solar heat
as fast as received, by radiating it back
into space In other words, the atmOs-
phere permits the solar rays to reach the
earth, and then keeps the resulting heat
imprisoned, until it is augmented up to
the existing average temperature, when
other causes step in to prevent it going
higher. Captain Ericsson, in attaching
such importance to the atmosphere as
preventive of the escape OF heat once i'm
parted to the earth, has the familiar
experience of aerOnauts and mount
ain climbers on his side. At the
height of a few miles from the earth
freezing atmosphere is encountered, which
is satsfac.o .orily explained by the thinness
of the air, the radiation of the earth's sur
face expending its principal heating effects
on the denscr strata of atmosphere below.
Assuming, as may be properly done, from
all the evidence, that there is no atm0s-
phcre about the moon, it would follow that
the Hcrschel theory must be erroneous {:
and it will remain one of the curiositics OF
science that Herschel should have regard
cd the absence of a lunar atmosphere as
causing an intense heat on the moons sur
face, while Captain Ericsson takes that
fact to be a positive proof of the superla-
lively cold condition of that body.


The Herschcl party claim that recent
experiments with the great Rose tclc-
scope sustain their theory. That gigantic
instrument has the largest metallic reflector
in the world, and, by connecting the tcle
scope with clock work during the present
year, Lord RosSc has been able to cOnccn-
tratc the rays of the moon upon n delicate
heat meaSurer, for the purpose of deter
mining whether the moon gives out heat
or not No tests previously made were
satisfactory on that point; but this one
settled the question beyond II doubt. The
lunar rays do transmit sensible degree of
heat. This fact is quoted to substantiate
the Hcrschcl theory, but it does not neccs-
sarily do SO. For it is 4 well
established truth that heat may. be
reelected from surfaces of ice, or iron,
or glass, or other substances, themselves
cold Reflected heat from cold bodies, or
heat radiatcd from hot bodies, would pro-
ducc exactly the same effects upon objects
receiving the rays. No means are now
known by which reflected and radiatcd heat
can he told apart, except by an examination
of the surface from which they proceed.
The Rossc experiments, therefore, while
tllcN dlC NCly OCNiNihso ~
mootcd point, and demonstrating that the
"chaSte beams of the watery moon" arc
not altogether devoid Of heat, settles moth
ing conclusively as between Ericsson and
Hcrschcl; for there is no doubt that
Ericsson's Hypothetical lunar ice would re-
fleet as much heat as Ierschers supposed
burning temperature would radiate.


Under the impulse of the discussion
which the bold and original Ericsson has
started, the moon will now become more
than ever an object of inquisitorial ex-
animation. Perhaps some telescope may
yet be made powerful enough to determine
by direct inspection, once and forever, the
question whether the lunar mountains are,
as Ericsson says, enormous cones of ice,
fed by water from the interior, which
freezes the moment ii comes to the surface


or the peaks of extinct volcanoes, us astron-
omers generally suppose them to be.-NeG
York Journal Of Commerce.


Light in the School