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ILLUSIONS EXPLAINED. 



which are remote. When the objects are birds (and we 

 know that, since they belong to the same flock, and are 

 consequently of the same species, they must be of substan- 

 tially the same size), the difference of apparent size sug- 



gests at once to our minds the difference of distance, and 

 so enables us unconsciously to correct the false impression 

 which would otherwise be produced ; but inasmuch as, in 

 the case of clouds, of the real magnitudes of which AVC have 

 no means of judging, there is nothing to correct the sensi- 

 ble impression, their apparent rising, though an illusion, 

 has the full force of reality upon our minds. 



The glittering colors which we think we see in the drops 



