iKc.T. ni.] DISSERTATION SFXOND. 87 



by the Bishop of Sarum, and he says, " If the honour of 

 being a member of the Society shall be conferred on me, 

 I shall endeavour to testify my gratit'.ide by communi- 

 cating what my poor and solitary endeavours can effect 

 toward the promoting its philosophical designs." 1 Such 

 was the modesty of the man who was to effect a greater 

 revolution in the state of our knowledge of nature than 

 any individual had yet done, and greater, perhaps, than 

 any individual is ever destined to bring about. Success, 

 however, never altered the temper in which he began 

 his researches. 



Newton, after considering the reflection and refraction 

 of light, proceeded, in the third and last Book of his 

 Optics, to treat of its inflexion, a subject which, as has 

 been remarked in the former part of this discourse, was 

 first treated of by Grimaldi. Newton having admitted a 

 ray of light through a hole in a window-shutter into a 

 dark chamber, made it pass by the edge of a knife, or, 

 in some experiments, between the edges of two knives, 

 fixed parallel, and very near to one another; and, by re- 

 ceiving the light on a sheet of paper at different distan- 

 ces behind the knives, he observed the coloured fringes 

 which had been described by the Italian optician, and. 

 on examination, found, that the rays had been acted on 

 in passing the knife edges both by repulsive and attrac- 

 tive forces, and had begun to be so acted on in a sensi- 

 ble degree when they were yet distant by ^-g- of an inch 

 of the edges of the knives. His experiments, however, 

 on this subject were interrupted, as he informs us, and 

 do not appear to have been afterwards resumed. The) 

 enabled him, however, to draw this t conclusion, that the 

 path of the ray in passing by the knife edge was bent 

 in opposite directions, so as to form a serpentine line. 



1 Birch's History of the Royal Society, Vol. III. p. 3. 



