434 THE KALEIDOSCOPE. 



When the kaleidoscope is held in the usual way that is, in a 

 nearly horizontal position directed towards a window or a lamp the 

 small bodies collect near the lower edge of the disc; to give a 

 greater variety to the figures, the tube should be held ver- 

 tically downwards, light being reflected into the tube by means of a 

 mirror which receives it from a window, the mirror being held in 

 the proper position by the retort-stand. 



If the two moveable mirrors are opened only about 4 or 5 cm , and 

 a short piece of a small wax taper be placed in the opening, a whole 

 wreath of flames will be formed by repeated reflection ; the circle 

 of flames can, however, only be completely seen by applying the eye 

 very closely to the opening of the angle formed by the two mirrors. 



A mirror does not reflect the whole of the light which falls upon it ; 

 hence the reflected image is never so bright as the object which is 

 reflected, and the images become fainter and fainter after repeated 

 reflection. This is also seen in the kaleidoscope, for the different 

 parts of the figure are not equally bright : the part opposite to the 

 one which is seen by direct light is always the least bright. For in- 

 vestigating repeated reflection a bright object, such as a very lumi- 

 nous flame, must be selected, as otherwise the images will not be 

 visible after the reflection has been repeated a number of times. 



The experiment with the candle should only last just long enough 

 for observing the result ; otherwise the mirrors might crack by the 

 heat of the candle, or the amalgam at the back might be injured. 



Two parallel mirrors would produce an infinite 

 number of reflected images of an object placed between 

 them, if there were not so much loss of light as to 

 render the images at last invisible. Nevertheless, if a 

 candle be placed between two mirrors, a long series of 

 images will be observed, which are placed along a 

 straight line if the two mirrors are exactly parallel, 

 but appear along a curve if the mirrors are even 

 slightly inclined to one another. 



Two pieces of looking-glass, about as large as those used for the 

 inclined mirrors, are fixed vertically by two retort- stands, 15 or 

 20 cm distant from, and parallel to, one another. A burning candle 

 is placed between them, and the eye applied close to the edge of one 

 of the mirrors, so as to see the greatest possible number of reflected 

 images. 



