THE KALEIDOSCOPE. 433 



If the position of the mirrors is not very incorrect, and you look at 

 the image of your face, the nose and mouth of the image will appear 

 either somewhat too narrow or too broad, but if the position is very 

 incorrect, only adjoining edges of the face are seen, the middle por- 

 tion being not visible at all, or a double face appears ; the correct 

 inclination of the mirrors may easily be found after a few alterations 

 by way of trial. The difference between the second image (that is, 

 the image of the first image) and the first image itself may be recog- 

 nised by placing a finger to one eye for example, upon the right 

 eye : the second image places the finger also upon the right eye, 

 while the ordinary image places it upon the left eye. 



If the angle between the mirrors is smaller than a 

 right angle, the number of images formed is greater. 

 Thus at an inclination of 60 the two first images are 

 each reflected twice again, but as two of these reflec- 

 tions coincide and give but one image, we have alto- 

 gether five images ; if the angle is 45 *, we have three 

 reflections of each primary image, and hence seven 

 images, which, with the object itself, form the eight an- 

 gular points of an octagon, while, in the case of the five 

 images produced when the angle between the mirrors 

 is 60, the figure formed is a hexagon. 



The kaleidoscope is a tube which contains two small 

 mirrors, placed lengthwise in the interior of the tube, 

 and inclined to one another at an angle of either 60 or 

 45. One end of the tube is closed by two parallel discs 

 of ground glass placed almost close to one another ; the 

 space between the discs contains small pieces of coloured 

 glass, bits of twisted glass of various shapes, &c., 

 which appear as a symmetrical figure with six or eight 

 rays when looked at through an aperture in the oppo- 

 site end of the tube. There is just room enough for 

 the small bodies to tumble about, and hence an endless 

 variety of symmetrical combinations present themselves 



to view as the tube is turned. 



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