Theory and Practice 



87 



foreshortened but that below him, while the opposite 

 hill will appear to him far above the head of the man 

 at A, and above the cow at b. In the section, the dotted 

 lines are the respective horizons of the two spectators. 



tig. 10. 



and the sketches shew the landscape seen by each, in 

 which the forked tree may serve as a scale to measure 

 the height of each horizon. 



The reflections of objects in water are no less depend- 

 ent on the laws of perspective, or of vision, than the 

 instances already enumerated. 



If the water be raised to the level of the ground 

 beyond it, we lose all advantage of reflection from the 

 distant ground or trees : this is the case with pieces of 

 water near the house in many places, for all ponds on 

 high ground present a constant glare of light from the 

 sky ; but the trees beyond can never be reflected on the 

 surface, because the angle of incidence and the angle of 

 reflection are always equal, and the surface of the water 

 will always be a perfect horizontal plane. This I shall 

 farther explain by the following lines [Fig. 11]. 



The spectator at a, in looking ^on the upper water, 

 will see only sky, because the angle of incident, b, and 

 that of reflection, c, being equal, the latter passes over 

 the top of the trees, d, on lower ground: but the same 



