REFRACTION THROUGH PRISMS. 



461 



easily deflected by means of a prism; a bright luminous 

 spot may thus be produced upon the floor, where no 

 direct sunlight was received before. The prism may 

 be clamped in a retort-stand placed on the window-sill ; 

 if the edge is turned upwards the rays will be refracted 

 and fall upon a spot on the floor which is nearer 

 to the window than the portion illuminated previously 

 by the rays passing directly through the window ; if 

 the edge be turned downwards, a beam of light will 

 be sent to a spot farther away, that is, to the opposite 

 wall. 



By candle light the deviation of the rays which pass 



K S 1 1 



FIG. 262 (an. proj., -L rea l size}. 



through a prism may be demonstrated by the arrange- 

 ment shown in fig. 262. A sheet of card-board is fixed 

 in a vertical position, about l cm from the candle, and it 

 has at the same height as the candle flame, a circular 



