Year: 1875

| nt SUuTCt Oi QUAR- 0cdls


PROF. S. P. LANGLEY, whose distin-
guished services in the department OF
solar physics have been recognized at
home and abroad, recently delivered a
lecture on the " Sources of Solar Heat" ,"
before the Stevens Institute of Tech
nology, at Hoboken, from which we con-
dense as follows:


"We hear so often nowadays" said the
speaker, "of the perfected achievements
of science that we may overlook the fact
that results which seem clear, when es-
tablished, are usually reached through
the hard lessons of wearying failure. We
SO commonly, hearing only of the final
success, forget that there is no known rule
to guide the search for it, that l may
bring before you something of new inter
est if l ask you to look with me at
problem which, though it is of the high
est Importance, science has only partly
solved, and with many of whose diff
culties her students are still struggling
This problem is that of the source and
probable duration of the heat of the sun
and of the degree of its temperature"


After this brief but suggestive preface
Prof Langley entered at once upon the
consideration of the subject to which it
refers. AS the address was essentially
popular one, the speaker adopted such
methods of illustration as should be
readily comprehended by the audience.
The sun is a globe 10S times the dame
ter of the earth, and about ,25O, 600 times
its volume. From this globe there is
now pouring upon the earth that nearly
measureless radiation which is sufficient
to sustain all life on its surface, from
| that of the date-palm in the scorchlng
| glare of Sahara's waste to that OF the
ea,weed at the bottom of the deepest
ocean cave, and yet the heat and light in
terrupted by this earth are but minute
fraction of the whole amount given forth
| from the sun. With view, if possible,
| to give some conceivable idea as to the
whole amount of this heat the following
Illustration was given:


"Let us imagine that all the ice in the
| world could be collected and stored upon
a plain till it formed a pile thirty-five
miles in diameter, and high enough TO
contain the ice from the arctic and ant
arctic poles and all the supplies OF the
temperate zones. Let this be supposed
to be shielded from all warmth until the
ice product of the world thus piled there
| winter after winter had formed column
| thirty-five miles in diameter and reach
ing out in space to the lunar orbit, so as
| to form bridge to the moon. Now let
the heat which the sun is constantly send
ing out be turned wholly upon it. 1t is
the subject of a simple proof that to first
| melt it all and then boil the oceans OF
| water it might be melted into, and finally
to dissipate the whole in vapor, would
occupy the suns ordinary radiations not
quite one second"


Again:


"The coal.beds of Pennsylvania would
probably supply the entire worlds con-
sumption for centuries; but | md that,
if the source of the suns heat (whatever
it isl were withdrawn, and it were posi-
Bile to transport these coal-beds there and
burn them fast enough to keep up the
present rate of emission and no more,
they would last considerably less than
one-thousandth part of second"


From these illustrations of the amount
of the suns heat the lecturer advanced
| to the considerations of the several theo'
ries propounded, with a view to solve the
great problem as to its true nature and
source.


The first of these theories is that the
sun is, as it were, on file, and that the
heat we experience is that given forth
by combustions of matter on its surface.
| This theory is regarded as untenable, for
the reason that, were the process one OF
simple combustion, the matter consti-
tuting the sun would have been con-
sumed long since, supposing that there
was present sufficient oxygen to keep up
the combustion, which is not the case.
A second and certainly curious story ad-
vanced by can eminent natural phlloso-
pher is to the effect that the heat is the
result of certain vital forces that are
still active on the suns surface, and the
action of which may be kindred to that
which produces the light of the FREELY
or the heat of the body. Passing from
these two theories to the third, the
speaker presents what may be regarded
as certainly the only reasonable explana-
ton of the problem. The body OF the
sun is in an incandescent state; that IS,
it is white hot, but not in condition OF
actual combustion. Assuming tins,
it is possible to conceive OF its
great heat-radiating power with
out an actual exhaustion of the
matter of which it is composed. The
question then arises: Whence proceeds
the heat by which the vast mass is kept
hot? 1t is in the answer to this question
that Prof Langley defines his views,
which indorse those originally presented
by Helmholtz The suns heat is, ac-
cording to this view, strictly ga mode OF
motion" itself renewed to finite but al
most inconceivable extent by the shrink
ing of its mass; that is, the heat given
off bv the sun is due to the matter OF
that body settling toward the center; or,
in other words, the contraction OF the
suns mass, as it tends to cool, keep the
temperature nearly constant at the ex'
pense of the volume. This, then. may be
accepted as the most reasonable theory
regarding the heat of the sun and, re-
ceiying as it has the Endorsement of one
so eminent as Prof. Langley, may be
accepted as authoritative. 1t is yet pos
sible, however, that continued observa-
tons may bring to light facts that will
call for more satisfactory theory. Till
then the reader may be safe in accept
ing this view as best standing the test
of external computation. ."-Appteto'a's 8
Journal.


Horses and cattle are liable to
sprains in cold weather from slipping
on ice, and horses often get calked." |
have found the following an excellent
embrocation for such injuries. 1t should
be well rubbed in when applied to
sprains. 1t is good fol- rheumatism if
well rubbed in while exposed to a hot
fire: Oil origanum, anise and spike, each
one ounce: spirits of turpentine, one
ounce; aqua ammonia, one ounce, and
alcohol, three ounces. Shake well be-