■^\'>x'\ 



JOURNAL 



OP 



NATURAL" PHILOSOPHY, CHEMISTRY, 



Ant> 



THE ARTS. 



AUGUST 1798. 



Ti 



ARTICLE L 



Farther Experiments and Obfervations en the JJ'eEliont and Properties of Li^ht, 

 By HENsr Brougham, jun. Efq. 



[Concluded from Page 155 of the prefent Volume.] 

 Oltfervatim 5. 



H E direfl: light falling on the fpeculum, and part of the reflected light on the horizontal 

 white ftage of a very accurate micrometer, I meafured the breadth of the fringes, fpots, &c. 

 Thefe, with the diftance of the fpeculum from the window and micrometer, and the fizc o£ 

 the fun's image, are fet down in the following table, all reduced to inches and decimals. 



Inches. Parts. 

 Diftance of the fpeculum from the bole in the window fliut - - 24. 



Diftance of the fpeculum from the flage of the micrometer - - 18. 



TrarWverfe axis of the fun's image . « - . 2. (J 



Conjugate axis of the fun's image - - - « 1. 4 



Length of the oblong dark fpot • - » - •+ , 



Breadth of the oblong dark fpot » - _ - '0074., ^ 



Breadth of its firft fringe » • - - .0022 • • 



Elliptic fpot's tranfverfe axis ; - - .0016 



• conjugate axis i • - - .0068 



Breadth of its firft fringe • - • 'Ofij^ 



Tranfverfe axis of a larger elliptic fpot - - - .013 



Conjugate axis of the fame fpot » » • ' .OO76 



Vol. IL— August 1798. C c I|k 



