Year: 1864

When ball is discharged from gun
and strikes an object, it is found that both
the ball and the object struck have risen
in temperature. If the force is sufficiently
great you cannot touch the ball, it is SO
hot; and just in proportion to the power
of the gun will be the heat of the ball. If
the power be sufficiently great, the heat
NAV be SO intense as to bring it to a white
heat and melt the ball. The meteoric
stones that sometimes fall to our earth may
be regarded as balls, but moving with
much greater velocity. They strike against
our atmosphere with so much force that
the force is converted into heat, so intense
that they. glow or become incandescent.
Suppose our earth, in itsrevolution, struck
against some opposing object like target.
what would be the consequence: Inc
force would be converted into heat, and
the velocity is SO great-twenty miles sec
ond-that would be Immediately brought
to the melting point. 1t would glow like
the sun, and become luminous body.
The heat would be equal to that produced
by the burning of fourteen earths made of
coal. But this is not all. 1t would then
fall into the sun, and would by its loss of
momentum produce a heat four hundred
times greater than before, and it would be
seen on the suns disc as bright luminous
spot. The force of the earth falling upon
the sun would communicate heat to the
sun equivalent to the heat emitted by the
sun in century. 1t would serve as
fuel for that length of time. Now, the
e II, = 1hohl 1I1n
this source, the conversion of power into
heat. 1t is probable that it is not COM
bustion. If THE sun were composed OF
coal, 1t would last at the present rate only
five thousand years. The sun, in all prob
ability, is not burning but an iQcandes-
cent body. Its light is rather that of
glowing molten metal than that of burn
ing furnace. But it is impossible that the
sun should constantly be giving out heat,
without either losing heat or being sup
piled with new fuel. We know the heat
of the sun. Each point is about thirty
times hotter than the furnace Of locomo-
tive, that is, square foot of the suns sur
face gives thirty times more heat than
square foot of grating in locomotive.
Yet the mass of the sun is Sc great that it
would require three thousand five hundred
solar systems, if made of coal, to account
for the heat of the sun. Assuming that
the heat of the sun has been kept up by
meteoric bodies falling into it, and proof
has been given of such fall, it is possible
from the mass Of the solar system to de-
termine approximately the period during
which the sun has shone as a luminary.
On boarding steamer you can on exam
ining the hold for Goals, and ascertaining
its capacity, tell approximately how long
she has been on her voyage. Limits can
be set to the fuel of the solar system, and
therefore limits can also be assigned to the
existence of the sun as our luminary. The
limits lie between one hundred millions
and four hundred millions of years.


These are enormous periods, but still
they are definite. The mass is SO great,
and the cooling is so slow, that, even on
the supposition that no fuel was added, it
might be five or six thousand years before
the sun cooled down single degree.