New-York tribune., 1875-03-10


GAIyAyoMETER AND THERM0-PILE.
Here IA agalvanometer, instrument consisting OF
two magnetic needles hung as to be under but very
slight tendency to point one way rather than another
and hung by this ber to be swayed by any cur.
rent from the wire 1t Is connected with this thermo
nile 40 az 10 form thermometer OF extreme deicacy
It has been arranged hero so as 70 project tae Image
image moves to the LETT when Place anything ,S,s cold
like this hammer or THIS piece OF %9Td 'as nnS hs or
cold hammer drive this cold nail into this cold
TTS%a, Iu o be- on now hot some years ago Sir William
Thompson suggested that meteortes which arc known
and heat t v string it, jIst the heated the
nal the ball the target The suggestion Is at hrst
FORMING part OF the systom would not fan on the
but doubt that meteors hurled into the sys
tenn from without may come In contact with the sun In
numbers and that they may ana indeed must cSnflD
valid cause far as II goes ana pass It by only because
after compulat which do not give mere, its con-
tribuon tho SUMS heat is found to be- though real
LEAVING this for tho present observe that every
uitSout sec5unting for the solar supply. One yet
mains however. which think does account for It, we
dalton It requires the force of many engines and men,
Now this force Is h amy ny co@nasad eer,s
Of hydrogen, the nghtest known gas, each cubic
mile OF It would far outweigh the largest
of force which would be required TO lift tho
structures OF Cheops Ghoch milo hsO, we SEQ what
OF the s5OOOO,OOooOo cubic miles next ,h,onas the
SUMS surface in fSns ,er eafa en- :, rc"gn c"g
municated in the statement that the heat produced Dy
the settling OF matter toward the center or IN other
words by the contraction OF tue suns mass 1t tends TO
cool keeps the temperature nearly CONSTANT a. the
pense OF the volume. Tsa ttu. OF this hypothesis. or
father this theory is shown by Its standing tho teS'oi
according to this view theu first, believe presented
y Uemhoitz the suns heat Is strictly m0dlo OF mo
ton tseIf renewed 70 u finite, but almost incODcevabe
extent BIZ the shrinking Of its mass The sum- then Is,
SEN has Shown that sbrlnkass OF Is diameter b; :ho
tenthousanth part "a Quantity PEI s 10 our
wEa % er so p" Ses' OF
sosn roSs wy the5 is nearly solved We believe know
the PRINCIPAL OF e of aa when
in the view Of its nebular hypothesis hI9t
SsT%tn .ssay aS IN ni The system in this his
from the s m 1Ss 1ssqa
nearly ceased here yet in the stil gracious
sun If we look backward We see that in some almost
been exerted that which would bc needed ia carrying
the substance Of the sun and its planetary attendants to
where their component atoms originally fell.
or else mat sos PHscf on igose
prmordal atoms OF the nebular mass that tendency to
eraytate 20 Which, WORKING @ through means hs nsars s
on the hearth to-day. We believe that through such
for miliio1s or Years But says Hemho.z though
the OF our planetary system Is so immense that
emission which has gone during the period of mans
history the inexorabe law Of mechanics that this
aay oe Teea Se T% history Of %a m b
minute ripple in the infinite ocean of time. For
nelves aud for long generetons. we have nothing to
fear Toe forces of air aud water and OF the vol
canic interior. still act upon the earhs crust They,
those distant cOsmical of which
have spoken, will pat an end to the human race. and
perhaps compel US to mako way Tor new ana more com
given way TO us.
DIFFERENCES OF HEAT on THE SUNS SURFACE.
On this point, have made good many experiments.
Among other points to be ascertained, we should know
the relative distances from the surface of the atmosphere
Of the the photosphere Even II do not know
the actual distance, we can calculate 1t, for II the
atmosphere deeper the proportion OF light would
not be the same. Now, in photograph Of the
the darEening toward edges Is apparent. The sun
itself is really bright there in any place, but
have % struggle through greater depth OF atmos
phere and are enreebled The spots on the surface
very much darker than the rest and look indeed black
really dark or cold et us consider how bright light
GSd eGs nG know s s m one Of the
we get the we-know lime light whose effects you
this light when held p against the face Of the sun Sp
pears Ike black spot upon IT. and In fact Is backer
ceus Of spot is in fact there dazzling bright and
as it appears from measurement about one-haf as
as is5 observed that these spots only darker
but cooler than tho potosphere, and NJ secchi had
shown tnat the heat as well as the light diminished
Some time ago the study of the suNjecr was made
cations, using the thermo-pe. the little instrument
hold hand, and which is the most sensitive to ra
diant heat Of anything we possess. 1t employed In
connection with the Thompson Ralvanometer the In
strument before you, which Ia so sensitive that with
tiny galvanic battery made out Of percussion cap for
jar and drop OF water for an acid, side OF the
Atlantic standing on the other side register sig
nails sent through the ocean cable. Its very decaoy
however, units IL for lecture experiment.
Placing this Instrument in different parts of
the solar image, 1t has been found that
of absorption OF heat was such to very
different result from that Of Laplace, and Indicate
the its atmosphere removed, would not
appear very greatly hotter than at present pre-
believed that he had discovered the
regions Of the hotter than the polar
whence IL would follow that immense It's IN its
atmosphere ANALOGOUS TO our trade-w winds would
up The at Allegheny Pennsylvania have
shown such difference exists, and have led 10
many other conclusions which, however are perhaps of
more interest the astronomer than to the general
reader.
One OF these conclusions, however may still deserve
mention You that In his pictures OF the sun
near the edges Ia not quite bright In the center
but far brighter umbre of the spots Here IA
n SPOT from drawings made at Allegheny on larger
icAle
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