REFLECTION OF LlGBT. 381 



ing point of the object is in front of the mirror. 

 Hence, images seen in still, clear water are inverted. 



(a.) In Fig. 281, let A represent a luminous point ; MM, a mirror ; 

 A A' and BC, lines perpendicular to the mirror. Rays from A enter 

 the eye at DD'. The angle ABC = the angle CBD ( 591). The 

 angle ABC = the angle BAA' (Olney's Geometry, Art. 150). There- 

 fore the angle CBD - the angle BAA. The angle CBD = the angle 

 BAA (Olney, 152). Therefore the angle BA A = the angle BAA. 

 Hence AM= A M (Olney, 287). In other words, A' is as far behind 

 the mirror as A is in front of it. 



(6.) Place a jar of water 10 or 15 cm. back of a pane of glass placed 

 upright on a table in a dark room. Hold a lighted candle at the 

 same distance in front of the glass. The jar will be seen by light 

 transmitted through the glass. An image of the candle will be 

 formed by light reflected by the glass. The image of the candle 

 will be seen in the jar, giving the appearance of a candle burning 

 in water. The same effect may be produced in the evening by partly 

 raising a window and holding the jar on the outside and the candle 

 on the inside. 



596. Reflection of Kays from Plane Mir- 

 rors. If the incident rays be parallel, the reflected rays 

 will be parallel. If the incident rays be diverging, the 

 reflected rays will be diverging ; they will seem to diverge 

 from a point as far behind the reflecting surface as their 

 source is in front of that surface (See Fig. 281). If the 

 incident rays be converging, the reflected rays will be con- 

 verging ; they will converge at a point as far in front of 

 the mirror as the point at which they were tending to 

 converge is behind the mirror. 



597. Construction for the Image of a 

 Plane Mirror. The position of the image of an object 

 may be determined by locating the images of several well-- 

 chosen points in the object and connecting these images. 



(a.) In Fig. 282, let AB represent an arrow ; MN, the reflecting 

 surface of a plane mirror, and E the eye of the observer. From 



