Atmospheric Optical Illusions 85 
splashes all over when you turn on the faucet over a sink full 
of dishes. 
Perspective should also be listed as an important contrib- 
utor to optical illusions. You are familiar with the way rail-* 
road tracks appear to meet in the distance even though you 
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know for a fact that they are really parallel all the way. Simi- 
lar effects of perspective are responsible for some of the 
strange things observed at sea. 
Once you have familiarized yourself with the above terms, 
you will find the following accounts of optical illusions 
readily understandable. 
