Intelligence and Miscellaneous Aiiicles. 1 39 



rays, if the shadow of the disc be examined by an eye-lens of two 

 inches' focus, there ajipear at all points of the circumference streaks 

 of yelloM'ish light radiating into the shadow, and crossing at the 

 centre they form there a round bright spot ; but the streaks are 

 supposed to be chiefly due to irregularities in the edge. An analo- 

 gous phaenomenon is seen when a straight edge is used. A modifi- 

 cation of the same phaenomenon is observed in the case described by 

 the author to the British Association, at the meeting in 1846. 



The experiments above were all made by means of the sun's light. 

 There are well-known difficulties in performing any diflfraction ex- 

 periments by candle-light ; but the author succeeded in exhibiting 

 the ring by means of the light of a flame placed in the focus of a 

 short lens limited by a circular aperture. When the shadow is 

 thrown on a white screen at about one foot distance from the disc, 

 the middle of the shadow appears faintly illuminated ; but no streaks, 

 as in the case of solar light, could be detected, nor is the faint illu- 

 mination perceptible to the eye viewing the disc directly. The 

 author in conclusion makes mention of the theory of M. Babinet, 

 which attempts to explain the phenomenon on the undulatory hy- 

 pothesis on this principle, that " at points extei'ior to the area of the 

 rays there is no light, owing to the natural destruction of the secon- 

 dary waves. If, tlien, of the two rays proceeding to any such point 

 to destroy each other we intercept one by an obstacle, the other re- 

 mains, and gives rise to a point of light at that point ; that is, just 

 be)'ond the obstacle, a series of luminous points thus created by the 

 removal of interfering rays will give rise to the luminous borders 

 on the edge." (Nouv. Bulletin des Sciences, Nov. 1832. Quetelet, 

 Appendix to Translation of Herschel on Light.) 



I'he author, in conclusion, remarks that, imperfect as the whole 

 investigation confessedly is, it is by thus making the facts known 

 that we may most reasonably hope to elicit some better elucida- 

 tion of them. 



XXVII. Intelligence and Miscellaneous Articles. 



ON Newton's telescope at the royal society. 



To the Editors of the Philosophical Magazine and Journal. 



Royal Society, Somerset House, 

 Gentlemen, , Jan. 22, 1847. 



MY attention has been directed to a communication by Mr. 

 Hcineken, in the last Number of the Philosophical Magazine, 

 wherein he states, in allusion to tiie destruction of mechanical and 

 other instruments, " Two lamentable examples of this are, I learn 

 from a jiaper in the Magazine of Science, exhibited even at tiie 

 lloyal Society, where the reflectors of Newton and Hadley are in 

 a state of complete dilapidation." 



To this statement I beg to give an unqualified contradiction. The 

 reflectors arc in excellent preservation; and Sir Isaac Newton's 



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