SCIENCE OF COMMON THINGS. 



240 



Why windows blaze at sunset. 



light which is reflected in the direction R' S, towards the spectator, is not 

 sufficient to produce a sensible impression upon the eye. 



1653 Why do windows seem to blaze at sunrise and sunset f 



Because glass is a good reflector of light, and the 

 rays of the sun (striking against the window-glass) are 

 reflected, or thrown back. 



1054 On a lake of water the moon seems to make a path of light 

 towards the eye of the spectator, while ail the rest of the lake seems dark : 

 why is this ? 



The reason of this appearance is that eveiy little 

 wave, in an extent perhaps of miles, has some part of 

 its rounded surface with the direction or obliquity 

 which, according to the required relation of the angles 

 of incidence and reflection, fits it to reflect the light to 

 the eye, and hence every wave in that extent sends its 

 momentary gleam, which is succeeded by others. 



1S55 In a sheet of water at noon, the sun appears to shine upon only 

 one spot, and all the rest of the water seems dark : why is this f 



Because the rays fall 

 at various degrees of 

 obliquity on the water, 

 and are reflected at 

 similar angles / but as 

 only those which meet 

 the eye of the spectator 

 are visible, all the water 

 will appear dark ex- 

 cept that one spot. 



Here, of the rays S A, S B, 

 and S C, only the ray S C 

 meets the eye of the specta- 

 tor D. The spot C, therefore, 

 will appear luminous to the 

 spectator D, but no other spot of the water ABC. 



1050 Why can we not see into the street or road when candle* are 

 lighted f 



1. Because glass is a reflector, and throws the candle- 

 light lack into the room again ; and 



2. The pupil of the eye (having become contracted 

 by the light of the room) is too small to collect rays 



Fig. 67 



