Telepolariscope. A polariscope arranged to be attached to a 

 telescope. [8, 14.} 



Telescope. An optical instrument for " magnifying " distant 

 objects, so as to make them look nearer to the eye than 

 they actually are. There are two principal forms refracting 

 tele'scopes and reflecting telescopes. The optical system of 

 a refracting telescope, in its simplest form, consists of two 

 co-axial lenses : the object-glass or objective (q.v.), to produce 

 a real image of the distant object, and the eyelens, through 

 which this image is viewed. In reflecting telescopes the 

 image is formed by means of a concave mirror of large 

 radius. [1, 2, 3, 5, 6, 8, 9, 11, 13, 14, 15, 16, 17, 18, 20, 21, 

 23, 24, 26, 27, 28.] 



Telescope, Achromatic. A form of refracting telescope in which 

 achromatic lenses are used to avoid chromatic aberration. 

 [2, 3, 8, 9, 10, 11, 13, 15, 17, IS, 20, 21, 22, 23, 25, 26, 27, 28.] 



Telescope, Astronomical. A refracting telescope in which the 

 objective forms a real, inverted image which is viewed 

 through a convergent eye-lens, acting as a magnifying glass. 



Telescope, Binocular. An instrument, compounded of two 

 similar telescopes, by which an object is viewed simultane- 

 ously with both eyes. [2, 3, 5, 9, 13, 15, 17, 18, 20, 21, 26, 

 27.] 



Telescope, Cassegrain's. A reflecting telescope in which the 

 concave mirror is pierced with a small central aperture and 

 a subsidiary, small, convex reflector forms a secondary 

 image which is viewed through the aperture in the large 

 mirror by means of an eyepiece. [3, 11, 13, 18.] 



Telescope, Catadioptrical. A combined reflecting and refracting 

 telescope. 



Telescope, Catoptric. A reflecting telescope. 



Telescope, Coastguard. A 3o-in. refracting telescope, strongly 

 mounted, with a power of 25. [2, 3, 5, 8, 9, 13, 15, 16, 17, 

 18, 20, 23, 24, 25, 26, 27.] 



Telescope, Day and Night. A refracting ship's telescope with 

 a power of 12 or 25. [3, 5, 8, 9, 10, 13, 15, 16, 17, 20, 26, 

 27, 28.] 



Telescope, Dioptric. A refracting telescope. [1, 3, 11, 13, 17, 

 20] 



Telescope, Equatorial. A telescope mounted in such a manner 

 that, by suitable mechanism, it follows the apparent motion 

 of the observed star, due to the rotation of the earth. [2, 

 3, 6, 8, 9, 11, 13, 17, 18, 20, 21, 25, 26, 27.] 



Telescope, Floating Photographic. An observatory photographic 

 telescope floating on a liquid for observing absolute zenith 

 distances of stars within 80 of the zenith. [13.] 



Telescope, Galilean. A refracting telescope in which the eye- 

 lens is divergent, giving an erect image. It is shorter than 

 an astronomical telescope of equal magnifying power. 

 [1, 3, 6, 8, 10, 11, 13, 15, 16, 17, 18, 20, 21, 26, 27.] 



