An introduction to astronomy: designed as a text-book for the use of students in college. By Denison Olmsted ...

'288 FIXE1D) S'AllS.
lave been lbrollght to light, and a new and still more wonderfi't class of bodlies, called ]Ncbuhtl, have been reaclted in thie
tleptlus of thle stcelhlir universe.
41. 9. The introduction into practical astrlonomy of I [c-1
schecl's gcmat Ftorty-feet Reflector, itl 1789, was a great event
ill thle study of tlle stars.'This instl'llument in its previous
humble forms had b)et l very little ctlmployd upon tlhe stars,
tley) being supposed to be too remote for its powers, whtich
Sctlnel oliy suited to lnealrer worhls, as tlle sun and planets.
It was not- however, anl increase of magtnitfying powvel tlat
wavts wanted for researclhes on theset distant objects, bilt
an increase of liy]t, by whicll a few scattered rays sent to
us fi'tom bodies hidden in thie depths of space, miglht be collected in suclh linlnl)ls, and dircctct into thie eye, as would
rendler visible objccts otelrwise invisible, not because tlt (10o
not tranllslit tus any light, but )ecause ilot enout)h of Nwlhat they
tralunslmiLt en1te'rs the small plupil of tile eyre for te purposes of
distinct vision. Telescopes of great aplerture, theltfore, by collectting a large beam of liglt, and conveying it to thire eye,
greatly enlaige tile powelrs of thlis organl al11 cnablle it to 1)eIetrate )orportionally firtlher into tile most distant regiols of
the universe Si. Sir lW. Iterslc l ]himself made wonderfil prolt-:esds in tle knowlCeduge of tile starry heavens, and by llis otwn
researchels discovered a large portion of tlhose bodies wlhiclt vwe
are lnow to describe and Itis son, Sir John ci0snelchel, tas cutltivated, \\ith grcat sutccess, tle sanle field, anld (especially ))by at
residence of five years at tile Cape of Good Ilope, devoted assid(loullSl to ob iservations w\itht large is 11tltsllts, Ilas gieatly
auttgmented our knowled(ge of tlhe stellhar systems of tthe sotthe1n 1hem 1isphere. Mioreover, telescopes of still greaterl' 1)o0\tel'
than that of the elder [1rsellel, andll cspecially instlruments cal)tl)le of nicer angular measturements, have recently enriched
the d epartmtent of )practical astronomy. The mllost reii, atrkable
of thlese are the granid ]Rqtefetor constrlicted by I.ord RItosse, an
IrisI nobleman, and tile great R"fratosw belongitng respectively to tile lFPulkova and Camlbridgle Ob-servatories. jLord
tRosso's tolescope considcrably exceeds in diincnsions and in
po'\rt' thle forty-feet reflector of Sit' V. Jllrsellel), Ibcing 50t feet
in focal lcngtil, andl Ia1vinlg a diamlter of 6 feet) wheretas tlat