IN POPULAR PHYSICS. 45 



27. Which will be seen at the greater distance , a yellow 

 or a gray body ? 



The yellow, since it is brighter. 



28. IVlien a star is near the horizon, does it seem higher 

 or lower than its true place ? 



Higher. The light in passing into our atmosphere, is re- 

 fracted downward, and the star appears in the direction from 

 which the ray enters the observer's eye. 



29. Why can we not see a rainbow at midday ? 



Because the sun is not in the right position. To produce 

 the ordinary rainbow, it must be toward the eastern or western 

 horizon. 



30. What conclusion do we draiv from the fact that 

 moonlight shows the same dark lines as sunlight ? 



That its light has the same source as that of the sun, and 

 is, indeed, reflected sunlight. 



31. IFliy does the bottom of a boat seen under clear 

 ivater appear flatter than it really is ? 



Because, by refraction, the bottom of the boat is apparently 

 elevated above its true place. 



32. Of what shape docs a round body appear in 

 ^vater ? 



It appears to be flattened ; and hence a round body looks 

 like an oval one. 



33. Why is rough glass translucent while smooth glass 

 is transparent ? 



The minute irregularities scatter the rays of light, and do 

 not allow them to pass freely to the eye of the observer. 



34. Why can a carpenter looking along the edge of a 

 board tell ivhether it is straight ? 



If the edge is straight, the light will be reflected uniformly 

 to his eye from the whole length. Any uneven places will make 

 dark and light spots. 



