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 

 telescopes 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 30-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.] 



