Chap, ii.] [ 293 ] 



CHAP. XI. 



OF THE INFLECTION OF LIGHT. 



F.c';-:ftetf of the Doffrine of Rtflb&Htm. Nature of Inflection Neva- 

 ton's Experiments, Analogy between this Property and Refraftion. 

 - Curious Ejfecls from this Property. 



f p -S HE direction of the rays" of light is changed, as 

 JL we have feen, in their approach to certain bo- 

 dies, by reflection and refraction, and confequently we 

 muft admit that there is fome power in thefe bodies 

 by which fuch effects are univerfally produced. If 

 reflection was produced (imply by the impinging of 

 particles of light on hard or elaftic bodies, or if they 

 were in themfclves elaftic, the fame effects would fol- 

 low as in the impulfe of other elaftic bodies $' but the 

 tingle of incidence could not be equal to the angle of re- 

 flection, unlefs the particles of light were perfectly elaf- 

 tic, or the bodies on which they impinged were perfectly 

 elaftic. Now we know that the bodies on which thefe 

 particles impinge are not perfectly elaftic, and alfo that 

 if the particles of light were perfectly elaftic, the dif- 

 fufion of light from the reflecting bodies would be very 

 different from its prefent appearance ; for as no body 

 can be perfectly poiiihed, the particles of light v/hich 

 are fo inconceivably fmall would be reflected back by 

 the inequalities on the furface in every direction; con- 

 fequently we are led to this concliifion, that the reflect- 

 ing bodies have a power which acts at fome little dif- 

 fance from their furfaces. 



If this reafoning is allowed to be juft, it neceffarily 



follows, that if a ray of light, inftead of impinging on 



U 3 a body, 



