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be, which disposes the different rays in fringes of different breadths ; 

 but he considers that the two properties are wholly independent of 

 each other. 



12. He thinks there is reason to believe that the dark intervals 

 between the fringes made in white light are only the dark tint of the 

 adjoining fringes, of which the red of one runs into the violet of the 

 other. The greatest care in repeating Sir I. Newton's experiment, 

 with the same distances and sizes both of the body and the beam, 

 leaves little or no doubt of the fringes running into each other. In 

 homogeneous light it is otherwise ; and the're appear in that case to 

 be the intervals, as might be expected from the different flexibility of 

 the different rays. 



13. The fringes made in homogeneous light have a considerable 

 admixture of colours from the scattered rays ; so have the small 

 spectra by refraction made when a second prism is placed behind a 

 small hole in the screen, through which hole the rays of the spectrum 

 made by the first prism are successively passed. 



14. The phenomena of flexion by bodies placed in the portion of 

 the spectrum near the prism, and therefore white, are stated to be 

 not easily accounted for in any received theory. 



15. The Newtonian hypothesis of the different breadths of the 

 fringes being caused by the action of flexion extending to different 

 distances over the different rays, is stated to be insufficient to account 

 for it, and also to account for the different colours in the fringes to 

 be made by white light. It is considered that the different flexibility 

 will account for the latter, but not for the different breadths of the 

 fringes, without another hypothesis, namely, the different ratio of the 

 force to the distance from the bending body, in different rays. 



16. The entire difference of flexion and refraction is shown from 

 the different breadths of the fringes, and from their formation upon any 

 possible hypothesis being shown to have nothing similar or analogous 

 in the phenomena of refraction, though the different flexibility is pre- 

 cisely similar to the different refrangibility, only applicable inversely 

 to the different rays. 



17. The relation of the doctrine of interference to the phenomena 

 of flexion is considered ; and it is shown that certain of these phe- 

 nomena are at variance with the doctrine. This is particularly ex- 

 emplified in the case of the phenomena observed where bodies acting 

 on light are not placed directly opposite to each other, but one be- 

 hind the other. 



18. The same phenomena are adduced to disprove M. Fresnel's 

 hypothesis, that the phenomena of flexion (termed by him diffraction) 

 depend entirely on the size of the aperture through which the light 

 enters. Three experiments are adduced in disproof of this ; the 

 first made on the aperture when the edges are directly opposite each 

 other ; the second, when the edges are moved to different distances 

 from each other on a line exactly parallel to the rays ; the third, 

 when the edges are moved on a line at any inclination to the rays. 

 In both the second and third experiment, the vertical distance of the 

 edges («. e. the aperture) being the same, the breadth as well as the 



