Year: 1875

Let us examine, now, the other ways in which heat
may De pr0dnce ana sEe we havs t We
need only look at field upon Summer evening TO ace
In the ALTERING eSsTs hsa iOsa some er aS WS Mr.
Nasmyth OF England, an amateur observer, Thought
400 miles wide and LOCO miles long: hat bat
Illustration OF them. lProf. Langley here showed
Nasmyth's q" willow leaves" projected ON sereen.I
and most eminent natural philosopher went 50 far as
to of hs tns' sSey a that Vital
evolve light. heat, and electricity have given much
that they are not what Mr. Nssmyth thought, but
things not unlike clouds We need not therefore,
sensed BY vital force-and yet it is worth while to
ton IT, order to give proper idea Of the mystery
whiea whiea D could drive SO clear thinker as
Sir John Herschel to suggest th: hypothess
slow combustion Of the food and could not 80 on with


But there are other Ways Sf nVns out
familiar illustration Of what is called i1candescence


The poker need % mot % D4r Ho % Snee S ou lis %


would remain In the ron which would continue 10 send
have been heated without putting it the fire at all,
by laying It, for instance, cold on cold anvil ana
cal the heat would come from arrested motion Tnen
again electricity competent to produce and maintain
incandescence. you see in the case OF this iron


wire vas heated at this point IN the lecture, and made
to glow by the passage OF an electrical currentl


descent without auy burning IN tho ordinary sense Is
familiar enough to make further illustration unneces
sary But the is probably not solld We can have
liquids as in case 0; molten But
the sun probably not liquid. II is. as we see IT
chiefly, perhaps entirely, composed OF gaseous and
| metallic vapors Burning gas we are all acquainted
with but make ee son1 sns m


first sight 1t seems that could not Gas as We know
by tins iaminar form Sf ordinarily Snrns up 5 in sy
supplies. But this Is only because air reaches II,
could svs out light without taking fire. You that
we can with the specroscope tell In part what the sun


portion Of It's surface in this tube sealed
the air out. could lay 1t upon tire and heat 1t til 1t
ehone without making burn at ALI but as it would be
difficult TO do this without breaking or melting the
glass, we will take the more convenient method OF
| nasslng q current through II, as VIC did through
| lie iroD this having the advantage Of causing
light enough TO show the effect with very lltte heat


forever and without any waste OF gas We could
keep tine perfect oq. a. W 1e


fresh supplies of power think we may say that we
"a not burniDg" at all In the common sense Of the
word ) IL IN state OF incandescence That 10, OF
eher be drawing on fixed internal store of heat put


into u by unknown power ages since ana slowly
sovroe of snpply either from without within and It
| will be stiil our business to nnd what that 49,


We cannot possibly refuse admit that The Sun is
Intensely hot that It's heat without any renewal has
not pcrceptiby diminished during tho last 5000 year,


% Of n" m we move a one


showed that on the hypothesis Of q perfect conduct


would have cooled through over 500 Fab. in year


whereas it only cooled by the tenth part degree
! 10 thousands Of years. The suppOsitlOn Is then
most Improbable that the sun should be draw
ing on some internal stock of heat; yet
| we Will pronounce 1t absolutely impossi Die


especially view of the theory VI dssoclaton brought
forward in chemistry by NJ st. Clair Deville and n
| physical astronomy 10y M. Faye. Tue melting OF ice
a into water at $50 calls for an immense amount OF
heat yet leaves the water hotter than BEFORE Tie
has gone to push the molecules further apart is
latent lin the old phrasf) III the water md can DO
| got back from it without change OF temperature
| Again, water at 2l2' can be turned TO steam at
22o and yet all the heat required for tho change be
represented by the alteration IN The molecular
| Temperature then, measure Of heat but whst
here attention that the does
not stop with tho steam. AT certain high temperature
IL ceases be steam and under the continued action Of
hest dissocated resolved into two gases hydrogen
| and oxygen. A simple experiment will show this.
| Here hydrogen and oxygen, which are, or could
nave BEEN made out OF drop Of water by The pen-
| dlture Of heat or force. They will give out
| that force which is locked up In them,
| 80 energs!cally as ~ give forth An
argued the material Of the may exist At compare.
Iyey moderate temperatures in dissertation. and yet
eve out great heat they recOmbine THIS Is very
lrue and IL " extremely likely that thero IA