Edgefield advertiser. [volume] (Edgefield, S.C.) 1836-current, 1845-12-31

shall nol in this place, enter INTO the discus
ison Of these two great theories, winch nas W
cupied The mind of the philosophical wotid . 81
long, and which has been handled 50 profoundly J
by the mos, accomplished philosophers
shall consequently bid farewell 10 this meta
physical branch oi lmy subject, and '"No w
that department which relules to Optics -o
Before the time OF Pitagoras, who Ived o'o
years before the advent of our ..avl"ur' we
| have no uccoun, of optics. This Philosopher
! believed that there emenated from about bon'es'
certain kinds OF visib"s. which acled upon lhe
corEea, and excited there the sensation O' 'hc
presence of objects. Plato ard EupedocieS,
not being content with this explcation. say t''a'
there emerates from the object and the eyes
certain efiluva, which encounter and mn hSIe'
| the one with the other. in the midst OF tneir
{ voyage. By this collissinn, The eitiuvIa "i''c"
wenlirom the eye, returned TO 1t, exciting mere M
I the sensation of the presence OF objects. lne
declpes of Plato adopted this system and tauSh.
the important discovery that light Is propasa'eu
it, finea recia and that the angles OF Incidence
are equal to angles Of reflection. THIS was ail
; rXcelIant principle for establishing theory ol
optics; but Aristotle. one OF the 0eclplrs OF
Plato. being more of dlsputani thana geo
mericiam in place OF securing thi' idea lie
applied it To explain vision. by mode more
conveniently: aud to know light and lis oD
ject Vision is effected according to him, by
! the reception of the images oF objects IN the
eye This matte is not difficult 10 understand.
hut The manner in which he explains light, IS
more difficult The light. he says. is that which
! makes bodies transparent. because bodies
are not so rrally-,lnr at night they acn
pakc. He imagined that the light which
exists in transparent media, is owing to The
presence of fire or some other lumll"ns fluid.
This is the conclusion of Aristotle.
The snccossors of Aristotle, who applied
themselves 10 optics. taught these notions as
obScurey us they found them. The next great
name after Aristotle, who applied himself TO
optics, is Euclides. He turned his attention
10 tho movement oflight, and to the laws of op.
lies, wilhou, explaining the nature oI light
He fixed his attention on lwn principal points.
These were to determine the apparent masn-
tude Of objects. which according To him, de
pended upon two angles, under which they
appeared, and 10 meet in the VISIBLE point oi
The image in mirrors which he believed was
formed by the concnnrse- of The rtflerted with
the perpendicular raw With these two prlm.
cipIes, they attempted To explain many optical
phenomena. aud was their main tlieor! of op.
tics. three hundred years before Cmist. This
theory is attributed TO EucIides, all able geone
uician Ills demonstrations nn this subject
are. very defective, and his method very inlr-
cafe.
Optics remained stationary for more than
four hundred years During this long period
Philosophers lever thought Of periec,ins this
interesting department Of science.
P,omy, one hundred and fifty years bel"rr
Christ, greatly cultivated mathematics. aud
believing optics 10 be Il branch Of his iarorlte
study, he applied himself also To This science.
He composed n learned work, which is said 10
he lost. but we can form some idea OF It, from
the fragments which the Opticians, his Succs-
.sors has conserved. Ptolnmy, first speaks Of
astronomical iefractons. anrl afterwards Of the
light which comes to us from the stars through
tile atmosphere. The second fragmrntls an
explication of the excessive magnitude OF the
stars, US seen Just above tlr HORIZON. Ptolomy
explains this phenomena, in manner very
i,mctaphysically. The soul, says he, is that
which Judges that Il star is very large, relative
" to the great number of objects nterpose'l.
with whose comparison we form lhr idea of II
great distance When The star is near The Iiorl-
Zon: but when ii is very elevated above The
horizonl' That is near the meridian, and having
no object intcrposed between the eye an'l the
star. we Judge that /, is sinIinteIy more distant.
Those wiln more appreciated The opinions OF
Ptrlrmy. were the Independent Arabs. They
studied with great diligence optics anu com
posed on this subject maTy works. Tie first
who wrote, whose name is Allaraho. treated
OF vision. which is an essential pant Of optics.
IloI Ihu, uoI
the matter more extensively He wrure on
vision dirccta, rctReEa, ref1acta, and on burning
leesms. lie examined first. The movement of
iigh, in strait lines; afterwards as ii comes 10
tire eye by reflection, and ultimately as il makes
Ell impression on this organ. from having been
relraclcd This author is the first who spoke
of butnins lenses. AMI also mentions that Ar
chimides was acquainted with these glasses.
We hnve occasion TO believe that the Greeks
we're The inventors of these lenses. In the
comedy Of the clouds ol AlStopllanes. in
have a focus uf three mileS;-with0nt tinldiy
which he so much satirrs Socrates, we read
tina, ail actor found kind OF stone with which
! hr was enabled TO pay his debts; by exposing
this stone to The sun. and by lis virtue Of con
! veylng the rays 10 focus aud by bringing this
(! forns to bear upon the WAX seal, mndrr Which
was written his debts, thereby melting the
seal, and consequently exemplns him from the
paymen, oil his deBf5. This stone no doubt
was fragment of glass. which reunited in II
Joint, the rays Of The sum- wlilcn IN substance
is kind of burning lens.
From Socrates to Archmid' :, who lived
230 years before the nativity Of Jesus Christ,
we see III history no other account oi these
lenses. until they were found TO be OF admira.
BILE use, by Arcnlmldes. fie, however, ncIther
speaks of their origen, nor the Improvement
OF their invention With these lenses, Lllcian
says, Archimides burnt the Roman fleet. at II
! distance of three miles. This statement is
now not received rs being fact, us it is inl.
possible for lens, even the most powerful, to
we place this in the class Of fables.
Abonl the year 1000. an Arab called .Alhazen,
ioined together all The ideas Of Plnlemy on the
reflection of hight, and taught with them his
own. Plolemy wrote on catoplrica; which is
the science of the reflection of light, and OF
diop,rica, which is the sclenc of the relracllon
of light He sIso described the torc, Of spher.
cal glasses, and the magnitude "l objects as
81, ,baeo ul,ccpc I'm The l,3lh Ceulll.