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Webster 1913 Edition


Telescope

Tel′e-scope

,
Noun.
[Gr. [GREEK] viewing afar, farseeing; [GREEK] far, far off + [GREEK] a watcher, akin to [GREEK] to view: cf. F.
télescope
. See
Telegraph
, and
-scope
.]
An optical instrument used in viewing distant objects, as the heavenly bodies.
☞ 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.
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
.
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, and 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.

Tel′e-scope

,
Verb.
T.
1.
To cause to come into collision, so as to telescope.
[Recent]

Webster 1828 Edition


Telescope

TEL'ESCOPE

,
Noun.
[Gr. end, or at a distance, probably the latter, and to see.] An optical instrument employed in viewing distant objects, as the heavenly bodies. It 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, and thus rendering objects distinct and visible which would otherwise be indistinct or invisible. Its essential parts are the object glass, which collects the beam of light and forms an image of the object, and the eye glass, which is a microscope by which the image is magnified.

Definition 2021


telescope

telescope

See also: télescope and télescopé

English

An optical telescope.

Noun

telescope (plural telescopes)

  1. A monocular optical instrument possessing magnification for observing distant objects, especially in astronomy.
  2. Any instrument used in astronomy for observing distant objects (such as a radio telescope).

Derived terms

Translations

Verb

telescope (third-person singular simple present telescopes, present participle telescoping, simple past and past participle telescoped)

  1. To extend or contract in the manner of a telescope.
  2. To slide or pass one within another, after the manner of the sections of a small telescope or spyglass.
  3. To come into collision, as railway cars, in such a manner that one runs into another.

See also