OP OPTICS. 



237 



through the glass, more or less, as the candle is more LECT. 

 or less distant from the focus. < 



Tf th candle be placed farther from the glass than 

 its focal distance, the rays will converge after passing 

 through the glass, and meet in a point which will be 

 more or less distant from the glass, as the candle is 

 nearer to, or farther from its focus ; and where the rays 

 met, they will form an inverted image of the flame of 

 the candle ; which may be seen on a paper placed in 

 the meeting of the rays. 



Hence, if any object A BC 

 be placed beyond the focus 

 F of the convex glass def, 

 some of the rays which flow 

 from every point of the ob- 

 iect, on the side next the 



will fall upon it, and, after passing through it, 

 they will be converged into as many points on the op- 

 posite side of the glass, where the image of every point 

 will be formed : and consequently, the image of the 

 whole object, which will be inverted. Thus, the rays 

 Ad, Ae, Af, flowing from the point A, will converge 

 in the space daf, and by meeting at a, will there form 

 the image of the point A. The rays B d, Be, Bf, flow- 

 ing from the point B, will be united at b by the refrac- 

 tion of the glass, and will there form the image of the 

 point B. And the rays C d, C e, Cf, flowing from the 

 point C, will be united at c, where they will form the 

 image of the point C. And so of all the other interme- 

 diate points between A and C. The rays which flow 

 from every particular point of the object, and are united 

 again by the glass, are called, pencils of rays. 



If the object A B C be brought nearer to the glass, 

 the picture a be will be removed to a greater distance. 

 For then, more rays flowing from every single point, 

 will fall more diverging upon the glass ; and therefore 



