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gregorian telescope
(encz) | Gregorian telescope, |
Gregorian telescope
(gcide) | Gregorian \Gre*go"ri*an\, a. [NL. Gregorianus, fr. Gregorius
Gregory, Gr. ?: cf. F. gr['e]gorien.]
Pertaining to, or originated by, some person named Gregory,
especially one of the popes of that name.
[1913 Webster]
Gregorian calendar, the calendar as reformed by Pope
Gregory XIII. in 1582, including the method of adjusting
the leap years so as to harmonize the civil year with the
solar, and also the regulation of the time of Easter and
the movable feasts by means of epochs. See {Gregorian
year} (below).
Gregorian chant (Mus.), plain song, or canto fermo, a kind
of unisonous music, according to the eight celebrated
church modes, as arranged and prescribed by Pope Gregory
I. (called "the Great") in the 6th century.
Gregorian modes, the musical scales ordained by Pope
Gregory the Great, and named after the ancient Greek
scales, as Dorian, Lydian, etc.
Gregorian telescope (Opt.), a form of reflecting telescope,
named from Prof. James Gregory, of Edinburgh, who
perfected it in 1663. A small concave mirror in the axis
of this telescope, having its focus coincident with that
of the large reflector, transmits the light received from
the latter back through a hole in its center to the
eyepiece placed behind it.
Gregorian year, the year as now reckoned according to the
Gregorian calendar. Thus, every year, of the current
reckoning, which is divisible by 4, except those divisible
by 100 and not by 400, has 366 days; all other years have
365 days. See Bissextile, and Note under Style, n., 7.
[1913 Webster] |
Gregorian telescope
(gcide) | Telescope \Tel"e*scope\, n. [Gr. ? viewing afar, farseeing; ?
far, far off + ? a watcher, akin to ? to view: cf. F.
t['e]lescope. See Telegraph, and -scope.]
An optical instrument used in viewing distant objects, as the
heavenly bodies.
[1913 Webster]
Note: A telescope assists the eye chiefly in two ways; first,
by enlarging the visual angle under which a distant
object is seen, and thus magnifying that object; and,
secondly, by collecting, and conveying to the eye, a
larger beam of light than would enter the naked organ,
thus rendering objects distinct and visible which would
otherwise be indistinct and or invisible. Its essential
parts are the object glass, or concave mirror, which
collects the beam of light, and forms an image of the
object, and the eyeglass, which is a microscope, by
which the image is magnified.
[1913 Webster]
Achromatic telescope. See under Achromatic.
Aplanatic telescope, a telescope having an aplanatic
eyepiece.
Astronomical telescope, a telescope which has a simple
eyepiece so constructed or used as not to reverse the
image formed by the object glass, and consequently
exhibits objects inverted, which is not a hindrance in
astronomical observations.
Cassegrainian telescope, a reflecting telescope invented by
Cassegrain, which differs from the Gregorian only in
having the secondary speculum convex instead of concave,
and placed nearer the large speculum. The Cassegrainian
represents objects inverted; the Gregorian, in their
natural position. The Melbourne telescope (see Illust.
under Reflecting telescope, below) is a Cassegrainian
telescope.
Dialytic telescope. See under Dialytic.
Equatorial telescope. See the Note under Equatorial.
Galilean telescope, a refracting telescope in which the
eyeglass is a concave instead of a convex lens, as in the
common opera glass. This was the construction originally
adopted by Galileo, the inventor of the instrument. It
exhibits the objects erect, that is, in their natural
positions.
Gregorian telescope, a form of reflecting telescope. See
under Gregorian.
Herschelian telescope, a reflecting telescope of the form
invented by Sir William Herschel, in which only one
speculum is employed, by means of which an image of the
object is formed near one side of the open end of the
tube, and to this the eyeglass is applied directly.
Newtonian telescope, a form of reflecting telescope. See
under Newtonian.
Photographic telescope, a telescope specially constructed
to make photographs of the heavenly bodies.
Prism telescope. See Teinoscope.
Reflecting telescope, a telescope in which the image is
formed by a speculum or mirror (or usually by two
speculums, a large one at the lower end of the telescope,
and the smaller one near the open end) instead of an
object glass. See {Gregorian, Cassegrainian, Herschelian,
& Newtonian, telescopes}, above.
Refracting telescope, a telescope in which the image is
formed by refraction through an object glass.
Telescope carp (Zool.), the telescope fish.
Telescope fish (Zool.), a monstrous variety of the goldfish
having very protuberant eyes.
Telescope fly (Zool.), any two-winged fly of the genus
Diopsis, native of Africa and Asia. The telescope flies
are remarkable for having the eyes raised on very long
stalks.
Telescope shell (Zool.), an elongated gastropod ({Cerithium
telescopium}) having numerous flattened whorls.
Telescope sight (Firearms), a slender telescope attached to
the barrel, having cross wires in the eyepiece and used as
a sight.
Terrestrial telescope, a telescope whose eyepiece has one
or two lenses more than the astronomical, for the purpose
of inverting the image, and exhibiting objects erect.
[1913 Webster] |
gregorian telescope
(wn) | Gregorian telescope
n 1: a reflecting telescope that has a paraboloidal primary
mirror and a hyperboloidal secondary mirror; light is
brought to a focus through an aperture in the center of the
primary mirror [syn: Cassegrainian telescope, {Gregorian
telescope}] |
| | podobné slovo | definícia |
gregorian telescope
(encz) | Gregorian telescope, |
gregorian telescope
(wn) | Gregorian telescope
n 1: a reflecting telescope that has a paraboloidal primary
mirror and a hyperboloidal secondary mirror; light is
brought to a focus through an aperture in the center of the
primary mirror [syn: Cassegrainian telescope, {Gregorian
telescope}] |
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