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diminished, is rendered more irritating ; 

 we can bear the full uninterrupted splen- 

 dour of the setting sun, nay can gaze on 

 the orb itself with little uneasiness ; but 

 when its rays ai'e broken by passing through 

 a thin screen of leaves and branches, no 

 eye is proof against the irritation. 



In all cases where there is a strong effect 

 of light, whether immediate or reflected, 

 there is v of course a real irritation on the 

 organ : and it probably will be admitted, 

 that there is a greater degree of it when 

 the rays strike on pointed or angular, than 

 on smooth and even surfaces : but it may 

 be said, that when there is no particular 

 light upon objects, as on a sunless day, 

 their roughness or abruptness causes no 

 irritation in the organs of sight. I ima- 

 gine, however, that besides the real irri^ 

 tation which is produced by means of 

 broken lights, all broken, rugged, and 

 abrupt forms and surfaces, have also by 

 sympathy somewhat of the same effect on 

 the sight, as on the touch. Indeed as it 

 js generally admitted, that the sense of 



