The Ottawa free trader. [volume] (Ottawa, Ill.) 1843-1916, 1849-05-04

""'S o'.y ""e !" ,o"ch shBhliy upon
inns Interesting topic. 1t was found impos-
sible, IN attempting to construct powerful
rrlrdctihg leieScopes, 10 overcome certain
o''hcnhics' Inc hSh', IN passing through
.he ir't iehS, was reifactcd ahd separated
INTO us PRIMARY co'ors, winch could not be
restored. III Instruments of long local dis
lance, was Io'ihd necessary to raise long
poles to support the instrument, and to en-
able them to turn the object glass 10 differ
ent points in the heavens. Owing TO the
inconveniences attending the use of these
Telescopes, Sir Isaac Newton gave IN the
hope Of ever making them available, and
turned his attention to the construction of a
different kind of Telescope, the Refectng
Telescope. But the discovery was soon
made, that, by combining two pieces of
glass Of different character. cl7,wn and flint
glass, that double object glass could be
formed, and one Of the glasses correcting
the influence Of the other, by their combin-
ed action, formed a colorless image. As
soon as Ms discovery was made, nothing
stood in the way of periecting the Refract-
ing Telescope. At this period, the genious
Of Frauenhofer was directed TO the me-
chanical consi ruc,inc of the mounting ofthe
Telescope. lie established himself in Mu-
Mich, where aided by his skilfnl partner.
Ctschheider, he obstructed an object glass
nine inches in diameter. Two, three, four,
five inches had been the limit previously
But this was not all. When the object glass
was finished, II became necessary to mount
u, TO give 1t conrlvance which should en-
able the observer to watch, with accuracy.
the movements OF the stars.
There Is one difficulty TO be overcome by
the observer, in attempting 10 mask with
precision, the motion Of the stars, namely
when, by applying high power to the Tel.
eSoope, we magnify the object ! 200 times,
the reiocify of the object is increased in the
same ratio, which renders it 900 times
greater than il is 10 the naked eye. A star
located on the Equator, rises in the east,
traverses the heavens, and sets in the west
III twelve hours. Now, if we magnify that
object l2,OOO times, the velocity is intreaS-
60 l2,OOo tunes, and 1t would rise and set
in the tweive-thonsandth part of twelve
hours, which Is about the thiri part OF sec
ond. Now to follow the swift motions OF
these maginhed objects, and to measure the
s.sHHNe distances by whlce some OF the stars
are SpafareA~ItsW each other, required
some instrument that Wculd make the OBJ
/ JtCt s'dHU sui IN me heavens, ana rest Ghl-
city ill the observer had finished his obser-
walton; and that has been done by adjusting
/ to the instrume ut piece of mocha njsn tina,
will carry the Telescope with precisely the
same velocity as the planet moves, and such
is the accuracy with which this has beer
accomplished, that in the instrument have
been employing, set itupon the sun in the
morning, and il holds il there all day long
from morning till night. it keeps the pom.
derous instrument levelled with nnerrinc
accuracy upon the object.
The second great class Ct Telescopes are
reHectors. Sir VIM Herschel, whose name
IS known through all the world as having
,h e"rin'I more ~ .he investigation o
I'a Li.', go, ,,'.i,: s, ''.an any WI" Prect'
m, ,', ,u,." ms Se,'ouS' an" 'aieh'S ,'
80, $500 ", ", 'e'es'opes. ms cary
csa, roGa",o" .i ",'', W eonS'aue' ms ior'y
~, ,,o 49,. g.. ,p..u'"''' VI mirror
,,;uh,, a.h ", 'o,,' ,..L, 90 a'' '''sr" WIN
ohe !, ,ii "' va. r','on WV ''"'
rod ,, wv, $50, ~. :. az! ros,uo, "esI
iii. ,,ao, 80" ,, ""' ",',"p, ''I u's,''P.on
vn,,r .,,,;o., ~ 49, !; wv os !ou W sn
:, ,,,,.', '..;,, w., i 'es "'""o ~
nf ,ha ,,.:,Ia,cn ae " ~. ,u'', So,'' 'ie'
rho hu,nan.ra i ~" ,,on W ,i r s.opt
Son IT, III, ~. W. s,'"ua'" VI 'o'"ps
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