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

Telephone to Temerity

(Tel"e*phone) n. [Gr. far off + sound.] (Physics) An instrument for reproducing sounds, especially articulate speech, at a distance.

The ordinary telephone consists essentially of a device by which currents of electricity, produced by sounds through the agency of certain mechanical devices and exactly corresponding in duration and intensity to the vibrations of the air which attend them, are transmitted to a distant station, and there, acting on suitable mechanism, reproduce similar sounds by repeating the vibrations. The necessary variations in the electrical currents are usually produced by means of a microphone attached to a thin diaphragm upon which the voice acts, and are intensified by means of an induction coil. In the magnetic telephone, or magneto- telephone, the diaphragm is of soft iron placed close to the pole of a magnet upon which is wound a coil of fine wire, and its vibrations produce corresponding vibrable currents in the wire by induction. The mechanical, or string, telephone is a device in which the voice or sound causes vibrations in a thin diaphragm, which are directly transmitted along a wire or string connecting it to a similar diaphragm at the remote station, thus reproducing the sound. It does not employ electricity.

(Tel"e*phone), v. t. To convey or announce by telephone.

(Tel`e*phon"ic) a. [Cf. F. téléphonique. See Telephone.]

1. Conveying sound to a great distance.

2. Of or pertaining to the telephone; by the telephone.

(Tel`e*phon"ic*al*ly) adv. By telephonic means or processes; by the use of the telephone.

(Te*leph"o*ny) n. The art or process of reproducing sounds at a distance, as with the telephone.

(Tel`e*po*lar"i*scope) n. [Gr. far off + E. polariscope.] (Opt.) A polariscope arranged to be attached to a telescope. Lockyer.

(Tel`e*ryth"in) n. [Gr. end + E. erythrin.] (Chem.) A red crystalline compound related to, or produced from, erythrin. So called because regarded as the end of the series of erythrin compounds.

(Tel"e*scope) n. [Gr. viewing afar, farseeing; far, far off + a watcher, akin to 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.

  By PanEris using Melati.

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