334 Upon the variegated Colours of Bodies 



treated the subject of inflexion with the same copioiisnes* 

 he has bestowed on his work upon coloured rings ; or even 

 that he did not turn his attention to the deviation of hght in 

 the adjacency of bodies, before examining its changes of 

 direction from the aetipn of surfaces : from these reflections 

 he would certainly have drawn some very valuable conse- 

 quences. 



In fact, the greatest analogy exists between the ph^eno- 

 menaof inflexion jiround a small body, and those of reflexion 

 or trandn)ission, by means of thin fjodies ; for the colours 

 of the fringes in the one seem to follow the same law with 

 that of the coloured rings in the others. And if this is not 

 very perceptible with respect to the fringes adjacent to the 

 shade of a body of small diameter received into a dark room, 

 this similitude becomes more evident with respect to the 

 fringes produced by the light which pg^sses between two bo- 

 dies very closely connected ; it is still more so in the course 

 of coloured images formed among the feathers of a quill, 

 tlirough v.'hich \vc look at the flame of a candle; and it is 

 also very manifestly recognised in bars seen by the eye, when 

 we place between us and the light, the texture of a piece of 

 cloth, or a number of metallic wires placed close together, 

 as in the experiments of M. Rittenhouse*. 



I have myself found a method still more proper for pro- 

 ducing this resemblance. For this purpose, I substitute in 

 place of the piece of cloth, the black gauze called crape, in 

 such a manner that if in a dark place we observe a light a 

 little distant, by covering the eye with a black crape we see 

 this light surrounded by a number of rings very apparent, 

 and of very lively colours, shaded with the same hue* with 

 those of the coloured rings of thin pellicles. 



If the flame of a candle is introduced into an aqueous va- 

 pour, a little abundant, where it cannot be seen except 

 through this vapour, we see the flame surrounded with rings 

 absolutely analogous to the preceding. I can Imitate them 

 also in an easy way, bv tarnishing with my breath a plate of 

 glass, which I mmiediately use for looking, either by re- 

 flexion or by transmission, at the image of a luminous body. 



*• Bib. Brit. Sciences ct Arts, torn- ix. 



The 



