388 



REFLECTION OF LIGHT. 



from A, but as they enter the eye, they diverge from a. Hence the 

 effect produced ( 594). 



(3.) From the similar triangles, ABC and abC, it is evident that 

 the linear dimensions of the object and of its image are directly 

 proportional to their distances from the centre of curvature. It 

 may also be proved that the length of the object is to the length of 

 the image as the distance of the object from the principal focus is 

 to the focal distance of the mirror. 



(4.) Since the lines that join corresponding points of object and 

 image cross at the centre of curvature, the real images formed by 

 concave mirrors are always inverted. 



FIG. 289. 



6O6. Projection of Real Images by Con- 

 cave Mirrors* The real image formed by a concave 

 mirror may be rendered visible even when the eye of the 

 observer is not in the position mentioned in the last article, 

 by projecting it upon a screen. In a darkened room, let a 

 candle flame be placed in front of a concave mirror, at a 

 distance from it greater than the focal distance. Incline 

 the mirror so that the flame shall not be on the principal 

 axis. Place a paper screen at the conjugate focus of any 



